WO2025178745A1

WO2025178745A1 - Methods for laser forming transparent articles from a transparent sheet and processing the transparent articles in-situ

Info

Publication number: WO2025178745A1
Application number: PCT/US2025/014260
Authority: WO
Inventors: Jonas Bankaitis; Garrett Andrew Piech
Original assignee: Corning Inc
Current assignee: Corning Inc
Priority date: 2024-02-23
Filing date: 2025-02-03
Publication date: 2025-08-28
Anticipated expiration: 2026-08-23

Abstract

A glass article includes a polished edge extending between a first major surface and a second major surface. The glass article is chemically strengthened via ion exchange such that the glass article comprises a first layer, a second layer, and an edge layer in which a concentration of an exchanged ion is heightened as compared to a bulk of the glass article. The first layer extends from the first major surface to a first depth of layer (DOL₁) within the glass article. The second layer extends from the second major surface to a second depth of layer (DOL₂) within the glass article. The edge layer extends inward from the polished edge and to an edge depth of layer (DOL_E) that is at least 5 µm. DOL_E is at least 5 µm less than DOL₁ and DOL₂.

Description

METHODS FOR LASER FORMING TRANSPARENT ARTICLES FROM A TRANSPARENT SHEET AND PROCESSING THE TRANSPARENT ARTICLES IN-SITU

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Application Serial No. 63/557,021, filed on February 23, 2024, the content of which is relied upon and incorporated herein by reference in its entirety.

BACKGROUND

Field

[0002] The present specification generally relates to apparatuses and methods for laser processing transparent workpieces, such as transparent articles and transparent sheets, and more particularly to laser forming transparent articles from a transparent sheet and processing the transparent articles in-situ.

Technical Background

[0003] Transparent articles, such as glass or glass ceramic substrates, are used in a wide variety of applications. Certain applications, such as use of transparent articles as a cover in automotive interiors, demand that the articles possess high strengths to meet various regulatory requirements. Subjecting transparent articles to various strengthening processes, such as ion exchange strengthening in the case of glass or glass ceramic substrates, can aid in providing transparent articles with relatively high strengths. In addition to high strength, some applications require transparent articles to undergo additional processing, such as the application of inks or an anti-reflection surface treatment which entail the deposition of at least one additional layer thereon. Performing such a variety of process steps on transparent articles can create complexities in mass production. For example, performing both ion exchange strengthening and depositing additional layers on a plurality of glass substrates individually can lead to difficulties stemming from handling each individual substrate. Many articles may be damaged from such handling, leading to low process yields. Accordingly, a need exists for a transparent article that can exhibit attributes required for various applications that can be produced through a process that avoids at least some complexities associated with individualized part handling. SUMMARY

[0004] An aspect (1) of the present disclosure pertains to a glass article comprising: a first major surface, a second major surface disposed opposite from the first major surface; a polished edge extending between the first major surface and the second major surface, wherein: the glass article is chemically strengthened via ion exchange such that the glass article comprises a first layer, a second layer, and an edge layer in which a concentration of an exchanged ion is heightened as compared to a bulk of the glass article, the first layer extends from the first major surface to a first depth of layer (DOLi) within the glass article, the second layer extends from the second major surface to a second depth of layer (DOL2) within the glass article, the edge layer extends inward from the polished edge and to an edge depth of layer (DOLE) that is at least 5 pm, and DOLE is at least 5 pm less than DOLi and DOL2.

[0005] An aspect (2) of the present disclosure pertains to a glass article according to the aspect (1), wherein: the concentration of the exchanged ion is elevated above that of the bulk throughout an entirety of the polished edge, and the polished edge comprises an Ra surface roughness that is less than or equal to 100 nm.

[0006] An aspect (3) of the present disclosure pertains to a glass article according to any of the aspects (l)-(2), wherein DOLE is greater than 20 pm and at least 50% of DOLi and DOL2.

[0007] An aspect (4) of the present disclosure pertains to a glass article according to any of the aspects (l)-(3), wherein: a maximum value of the concentration of the exchanged ion occurs in the first layer and/or or the second layer, and a minimum value of the concentration of the exchanged ion along the polished edge is at least 50% of the maximum value.

[0008] An aspect (5) of the present disclosure pertains to a glass article according to any of the aspects (l)-(4), wherein over a central segment of the polished edge disposed at least 100 pm from either the first major surface and the second major surface, the concentration of the exchanged ion varies by no more than 20% of a minimum value of the concentration along the polished edge.

[0009] An aspect (6) of the present disclosure pertains to a glass article according to any of the aspects ( 1 )-(5), wherein the polished edge comprises a plurality of brush marks arranged thereon in a substantially parallel configuration, the brush marks imparted by a brush polishing process. [0010] An aspect (7) of the present disclosure pertains to a glass article according to the aspect (6), wherein, as a result of the brush polishing process, ends of the polished edge are rounded but still under a compressive stress from the exchanged ion.

[0011] An aspect (8) of the present disclosure pertains to a glass article according to any of the aspects (l)-(7), wherein the first layer and the second layer exhibit maximum compressive stresses that are greater than or equal to 800 MPa.

[0012] An aspect (9) of the present disclosure pertains to a glass article according to any of the aspects (l)-(8), wherein, an Ra surface roughness of the polished edge is less than or equal to 20 pm.

[0013] An aspect (10) of the present disclosure pertains to a glass article according to any of the aspects ( l)-(9), wherein, when the glass article is subjected to headform impact testing according to FMVSS 201 with an impactor contacting an edge region of the first major surface and the second major surface, the glass article does not fracture.

[0014] An aspect (11) of the present disclosure pertains to a glass article according to any of the aspects (l)-(10), wherein a plurality of the glass articles with the same composition, thickness, and chemical strengthening exhibit a Weibull distribution with a B10 value that is greater than or equal to 700 MPa, when tested for mechanical edge strength using a four-point bend test in accordance with ASTM C158-02.

[0015] An aspect (12) of the present disclosure pertains to a glass article comprising: a first major surface, a second major surface disposed opposite from the first major surface; and a polished edge, wherein: the glass article is chemically strengthened via ion exchange such that the glass article comprises a first layer, a second layer, and an edge layer in which a concentration of an exchanged ion is heightened as compared to a bulk of the glass article, a maximum value of the concentration of the exchanged ion occurs within the first layer and/or the second layer, a minimum value of the concentration of the exchanged ion along the polished edge is at least 50% of the maximum value, and over a central segment of the polished edge disposed at least 100 pm from either the first major surface and the second major surface, the concentration of the exchanged ion varies by no more than 20% of the minimum value.

[0016] An aspect (13) of the present disclosure pertains to a glass article according to the aspect (12), wherein: the first layer extends from the first major surface to a first depth of layer (DOLi) within the glass article, the second layer extends from the second major surface to a second depth of layer (DOL2) within the glass article, the edge layer extends inward from the polished edge and to an edge depth of layer (DOLE) that is at least 5 pm, and DOLE is at least 5 pm less than DOLi and DOL2.

[0017] An aspect (14) of the present disclosure pertains to a glass article according to any of the aspects ( 12) -( 13), wherein DOLE is greater than 20 pm and at least 50% of DOLi and DOL2.

[0018] An aspect (15) of the present disclosure pertains to a glass article according to any of the aspects ( 12)-( 14), wherein the polished edge comprises a plurality of brush marks arranged thereon in a substantially parallel configuration, the brush marks imparted by a brush polishing process.

[0019] An aspect (16) of the present disclosure pertains to a glass article according to the aspect (15), wherein, as a result of the brush polishing process, ends of the polished edge are rounded but still under a compressive stress from the exchanged ion.

[0020] An aspect (17) of the present disclosure pertains to a glass article according to any of the aspects (12)-(16), wherein the first layer and the second layer exhibit maximum compressive stresses that are greater than or equal to 500 MPa.

[0021] An aspect (18) of the present disclosure pertains to a glass article according to any of the aspects (12)-(17), wherein, the Ra surface roughness is less than or equal to 20 nm.

[0022] An aspect (19) of the present disclosure pertains to a glass article according to any of the aspects ( 12)-( 18), wherein, when the glass article is subjected to the headform impact test in accordance with ECE R21 with the impactor contacting an edge region of the first major surface and the second major surface, the glass article does not fracture.

[0023] An aspect (20) of the present disclosure pertains to a glass article according to any of the aspects (12)-(19), wherein a plurality of the glass articles with the same composition, thickness, and chemical strengthening exhibit a Weibull distribution with a B10 value that is greater than or equal to 700 MPa, when tested for mechanical edge strength using a four-point bend test in accordance with ASTM C158-02. [0024] An aspect (21) of the present disclosure pertains to a glass article according to any of the aspects (12)-(20), wherein the polished edge comprises an Ra surface roughness that is less than or equal to 10 nm.

[0025] An aspect (22) of the present disclosure pertains to a method of forming a transparent article from a transparent sheet, the method comprising: forming one or more closed contours in the transparent sheet separated from the edge of the transparent sheet, each closed contour comprising a plurality of defects in the transparent sheet such that each closed contour defines a perimeter of the transparent article, wherein forming each of the one or more closed contours comprises: directing a pulsed laser beam oriented along a beam pathway and output by a beam source into the transparent sheet such that a portion of the pulsed laser beam directed into the transparent sheet generates an induced absorption within the transparent sheet, the induced absorption producing defects within the transparent sheet along the one or more closed contours; and translating the transparent sheet and the pulsed laser beam relative to each other along one or more closed contour lines, thereby laser forming defects along the one or more closed contour lines within the transparent sheet. The method further includes subjecting the transparent sheet to an ion exchange treatment where the defects act as conduits for ion exchange such that the transparent sheet is strengthened along the one or more closed contours throughout a thickness of the transparent sheet; and separating a transparent workpiece from the transparent sheet at the one or more closed contours after the ion exchange treatment, wherein after the separating and prior to any processing of an edge of the transparent article, the edge of the transparent workpiece exhibits a minimum exchanged ion concentration that is greater than 80% of a maximum ion exchange concentration of the transparent workpiece.

[0026] An aspect (23) of the present disclosure pertains to a method according to the aspect (22), further comprising applying one or more surface treatments to at least one of the major surfaces of the transparent sheet after the ion exchange treatment and prior to the separating, the one or more surface treatments comprising at least one of depositing a decoration layer, application of an anti-glare surface treatment, depositing an antireflective coating, and depositing an anti -fingerprint coating.

[0027] An aspect (24) of the present disclosure pertains to a method according to any of the aspects (22)-(23), further comprising forming one or more release lines in the transparent sheet to singulate the transparent workpiece. [0028] An aspect (25) of the present disclosure pertains to a method according to any of the aspects (22)-(24), wherein the portion of the pulsed laser beam directed into the transparent sheet comprises: a wavelength ; a spot size w₀; and a cross section that comprises a Rayleigh range Z_R that is greater than F_D A where F_D is a dimensionless divergence factor comprising a value of 10 or greater.

[0029] An aspect (26) of the present disclosure pertains to a method according to the aspect (25), wherein the pulsed laser beam comprises a beam core radius that is from 1 pm to 2.5 pm and ZR is from 1 mm to 2 mm.

[0030] An aspect (27) of the present disclosure pertains to a method according to any of the aspects (22)-(26), wherein a spacing between adjacent defects is 50 pm or less.

[0031] An aspect (28) of the present disclosure pertains to a method according to any of the aspects (22) -(27) , wherein the beam source comprises a pulsed beam source that produces pulse bursts with from 1 sub-pulse per pulse burst to 30 sub-pulses per pulse burst and a pulse burst energy is from 100 pj to 1500 pj per pulse burst.

[0032] An aspect (29) of the present disclosure pertains to a method according to any of the aspects (22)-(28), further comprising subjecting the edge to polishing to remove at least 5 pm of material of the transparent workpiece from the edge and form the transparent article with a polished edge.

[0033] An aspect (30) of the present disclosure pertains to a method according to the aspect (29), wherein, after the separating and polishing, the transparent article comprises a first layer, a second layer, and an edge layer in which a concentration of an exchanged ion is heightened as compared to a bulk of the glass article, the first layer extends from a first major surface of the transparent article to a first depth of layer (DOLi) within the transparent article, the second layer extends from a second major surface of the transparent article to a second depth of layer (DOL2) within the transparent article, the edge layer extends inward from the polished edge and to an edge depth of layer (DOLE) that is at least 5 pm, and DOLE is at least 5 pm less than DOLi and DOL2.

[0034] An aspect (31) of the present disclosure pertains to a method according to the aspect (30), wherein the polishing is brush polishing. [0035] An aspect (24) of the present disclosure pertains to a method according to any of the aspects (22)-(31), wherein the ion exchange treatment comprises immersing the transparent sheet in a molten salt bath at a temperature of at least 390°C for a time period of at least 1 hour.

[0036] Additional features and advantages of the processes and systems described herein will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description which follows, the claims, as well as the appended drawings.

[0037] It is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated into and constitute a part of this specification. The drawings illustrate the various embodiments described herein, and together with the description serve to explain the principles and operations of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The embodiments set forth in the drawings are illustrative and exemplary in nature and not intended to limit the subject matter defined by the claims. The following detailed description of the illustrative embodiments can be understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which:

[0039] FIG. 1A schematically depicts a transparent article formed via the process described herein, according to one or more embodiments of the present disclosure;

[0040] FIG. IB schematically depicts a cross-sectional view of the transparent article through the line I-I in FIG. 1A, according to one or more embodiments of the present disclosure;

[0041] FIG. 2A is a flow diagram of a process of fabricating a transparent article by laser processing a transparent sheet to form one or more contours of defects and ion exchanging the transparent sheet, according to one or more embodiments of the present disclosure; [0042] FIG. 2B schematically depicts a beam spot of a pulsed laser beam traversing a closed contour line to form a closed contour of defects in a transparent sheet and a contour line, according to one or more embodiments described herein;

[0043] FIG. 2C schematically depicts the formation of a closed contour of defects, according to one or more embodiments described herein;

[0044] FIG. 2D schematically depicts an example pulsed laser beam focal line during processing of a transparent sheet, according to one or more embodiments described herein;

[0045] FIG. 2E schematically depicts an optical assembly for pulsed laser processing, according to one or more embodiments described herein;

[0046] FIG. 2F graphically depicts the relative intensity of laser pulses within an exemplary pulse burst vs. time, according to one or more embodiments described herein, according to one or more embodiments described herein;

[0047] FIG. 2G graphically depicts relative intensity of laser pulses vs. time within another exemplary pulse burst, according to one or more embodiments described herein;

[0048] FIG. 2H schematically depicts one or more surface treatments being deposited within the closed contour depicted in FIG. 2B, according to one or more embodiments of the present disclosure;

[0049] FIG. 21 schematically depicts a plurality of release lines formed in the transparent sheet depicted in FIG. 2H for separation of a plurality of transparent workpieces from a frame portion of the transparent sheet, according to one or more embodiments of the present disclosure;

[0050] FIG. 2J schematically depicts a stack of transparent workpieces undergoing brush polishing, according to one or more embodiments of the present disclosure;

[0051] FIG. 3 schematically depicts an example transparent article formed via the process depicted in FIG. 2A, according to one or more embodiments of the present disclosure;

[0052] FIG. 4A is a plot of edge strength testing for 1.1 mm thick examples formed via the process depicted in FIG. 2A both with and without brush polishing, according to one or more embodiments of the present disclosure; [0053] FIG. 4B is a plot of edge strength testing for 1.3 mm thick examples formed via the process depicted in FIG. 2A both with and without brush polishing, according to one or more embodiments of the present disclosure;

[0054] FIG. 5 schematically depicts a setup for conducting headform impact testing, according to one or more embodiments of the present disclosure;

[0055] FIG. 6 schematically depicts a 1 mm wide section of a sample including measurement regions for concentration of an exchanged ion as a function of depth, according to one or more embodiments of the present disclosure;

[0056] FIG. 7A is a scanning electron microscope (SEM) image of a first sample prepared by cutting sample already subjected to ion exchange strengthening, according to one or more embodiments of the present disclosure;

[0057] FIG. 7B is a SEM image of a second sample prepared by separating a workpiece from a transparent sheet and then subj ecting the workpiece to ion exchange strengthening, according to one or more embodiments of the present disclosure;

[0058] FIG. 7C is a SEM image of a third sample prepared by the process depicted in FIG. 2A, without polishing, according to one or more embodiments of the present disclosure;

[0059] FIG. 7D is a SEM image of a fourth sample prepared by the process depicted in FIG. 2A, with brush polishing after separation from a transparent sheet, according to one or more embodiments of the present disclosure;

[0060] FIG. 8A is a plot of K2O concentration as a function of depth at a plurality of measurement locations for the first sample depicted in FIG. 7A, according to one or more embodiments of the present disclosure;

[0061] FIG. 8B is a plot of K2O concentration as a function of depth at a plurality of measurement locations for the second sample depicted in FIG. 7B, according to one or more embodiments of the present disclosure;

[0062] FIG. 8C is a plot of K2O concentration as a function of depth at a plurality of measurement locations for the third sample depicted in FIG. 7C, according to one or more embodiments of the present disclosure; [0063] FIG. 8D is a plot of K2O concentration as a function of depth at a plurality of measurement locations for the fourth sample depicted in FIG. 7D, according to one or more embodiments of the present disclosure; and

[0064] FIG. 8E is a plot of K2O concentration for a central segment of an edge of interest of the third sample depicted in FIG. 7C, according to one or more embodiments of the present disclosure.

DETAILED DESCRIPTION

[0065] Reference will now be made in detail to embodiments of processes for laser processing a transparent sheet into a plurality of transparent workpieces that are polished into a plurality of transparent articles, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. According to one or more embodiments described herein, a transparent sheet may be laser processed to form one or more closed contours in the transparent sheet, each closed contour comprising a series of defects that define a perimeter of one or more transparent workpieces that may be separated from the transparent sheet and subsequently formed into transparent articles. According to one embodiment, a beam source outputs a pulsed laser beam, which is directed into the transparent sheet to create a series of defects in the transparent sheet, thereby laser forming the one or more closed contours, which each define a perimeter of a transparent workpiece formed from the transparent sheet. The defects may be referred to, in various embodiments herein, as line defects, perforations, or nano-perforations in the workpiece. After formation of the defects, the transparent workpiece is not broken apart from the transparent sheet. For example, the transparent workpiece can remain frictionally engaged with the transparent sheet without an additional processing step because a minimal separation gap (i.e. minimal kerf) is present between the perimeter of transparent workpieces and a frame portion of the transparent sheet.

[0066] Such frictional engagement allows for additional processing of the transparent sheet as well as the transparent workpiece formed therein as a single unit. The process described herein utilizes this frictional engagement to perform chemical strengthening on the entire transparent glass sheet with the contours formed therein. As will be described in greater detail herein, laser processing in accordance with the present disclosure produces defects that serve as effective conduits for ion exchange strengthening treatments. As a result, the portions of the transparent workpiece adjacent to the closed contours are subjected to ion exchange strengthening throughout an entirety of their thickness. Such portions of the transparent workpieces can form edge regions of transparent articles that are under compressive stress, resulting in edge strength improvements over articles cut from a transparent sheet that was strengthened prior to formation of laser defects therein.

[0067] A further benefit of the process described herein is that the chemical strengthening does not result in the separation of the transparent workpieces from the transparent sheet. That is, the chemically strengthened transparent workpieces remain engaged with the frame portion of the transparent sheet after chemical strengthening. This enables further treatments to be applied to multiple transparent workpieces while they are still substantially in the form of the transparent sheet. As an example, one or more layers of material (e.g., a decorative ink layer, a multilayer antireflective coating, an easy-to-clean layer) may be applied to a surface of one or more transparent workpieces (and optionally, a surface of the remaining frame portion of the transparent sheet) after the chemical strengthening. Alternatively or additionally, a surface of one or more transparent workpieces (and optionally, a surface of the remaining frame portion of the transparent sheet) may be modified (e.g., polished, roughened, cleaned, or the like). Such processing being performed at the batch level eliminates costly and laborious individual part handling.

[0068] After the chemical strengthening and additional surface treatments, the one or more transparent workpieces may be singulated from the frame portion of the transparent sheets (or “singulated”) by cutting the frame portion using any suitable technique (e.g., mechanical or laser cutting). Such a process yields one or more transparent workpieces that include surface treatments and strengthened edge regions from an elevated concentration of an exchanged ion. Applicant has found that polishing the individual workpieces post separation can result in transparent articles of improved edge strength. In order to remove flaws (e.g., chips and cracks) from the laser contour formation and singulation steps, such polishing removes a portion of the edge of the workpiece under compressive stress from the chemical strengthening, resulting in the edge layers of each article having a diminished depth of layer as compared to the major surfaces thereof. However, as a result of the processing, the articles described herein can exhibit a Weibull distribution with a BIO value that is greater than or equal to 700 MPa, when tested for mechanical edge strength using a four-point bend test in accordance with ASTM C158-02. Moreover, when the transparent articles described herein are subjected to the headform impact test in accordance with ECE R21 and/or FMVSS 201, with the impactor contacting an edge region of one of the major surfaces, the glass article may have a smaller probability of fracture as compared with articles prepared with existing techniques involving individual chemical strengthening. This renders the methods described herein suitable for making transparent articles for use in automotive applications, such as cover glass for automotive interior displays.

[0069] Thus, the processes described herein yield glass articles with favorable edge strength for numerous applications, all while eliminating various complexities and costs associated with individual part handling during numerous process steps (chemical strengthening, application of coatings or surface treatments, etc.). Various embodiments of forming and processing transparent articles from a transparent sheet will be described herein with specific reference to the appended drawings.

[0070] The phrase "transparent workpiece," as used herein, means a workpiece formed from glass or glass-ceramic which is transparent, where the term "transparent, " as used herein, means that the material has an optical absorption of less than about 20% per mm of material depth, such as less than about 10% per mm of material depth for the specified pulsed laser wavelength, or such as less than about 1% per mm of material depth for the specified pulsed laser wavelength. According to one or more embodiments, the transparent workpiece may have a thickness of from about 50 microns (pm) to about 10 mm (such as from about 100 pm to about 5 mm, from about 0.5 mm to about 3 mm, or from about 100 pm to about 2 mm, for example, 100 pm, 250 pm, 300 pm, 500 pm, 700 pm, 1 mm, 1.2 mm, 1.5 mm, 2 mm, 5 mm, 7 mm, or the like). Transparent workpieces described herein include a "transparent sheet," a "transparent article," and a "frame portion." As used herein, "transparent sheet" refers to a transparent workpiece from which additional (smaller) transparent workpieces may be separated. As used herein "transparent article" refers to a transparent workpiece that is singulated from a transparent sheet. Further, as used herein, "frame portion" refers to some or all of the remaining portion of transparent sheet from which the transparent article(s) are separated (e.g., a contiguous remaining portion that surrounds the transparent article(s)).

[0071] As used herein, the terms “article,” “glass article,” “ceramic-article,” “glass-ceramics,” “glass elements,” “glass-ceramic article” and “glass-ceramic articles” may be used interchangeably, and in their broadest sense, to include any object made wholly or partly of glass and/or glass-ceramic material.

[0072] As used herein the term “separate” refers to the propagation of a crack between defects formed in a transparent sheet by laser processing. As described herein, this crack propagation can result in a physical disconnection between portions of a transparent sheet (e.g., between a transparent workpiece and a frame portion of the transparent sheet. However, the separated portions of the transparent sheet can remain frictionally engaged with one another. In some cases, separation can be induced by applying a stress along a contour of defects (e.g., via exposure to light from a CO2 laser).

[0073] As used herein, the term “singulation” has a different meaning than the term “separation.” Singulation refers to the physical removal of one piece of glass from another. That is, after singulation, there is no frictional engagement or any contact between the pieces (e.g., there is an air gap between the pieces). In accordance with the present disclosure, transparent workpieces can be singulated from a frame portion of a transparent sheet to form transparent articles.

[0074] Further, the present disclosure describes methods for laser processing transparent workpieces. As used herein, “laser processing” may include forming contours (e.g., closed contours) in transparent workpieces, separating transparent workpieces, or combinations thereof. Transparent workpieces may comprise a glass having any of the compositions described herein.

[0075] The phrase “contour line,” as used herein, denotes a line (e.g., a line, a curve, etc.) of intended separation on the surface of a transparent workpiece along which the transparent workpiece will be singulated into multiple portions upon performance of appropriate processing conditions. Further, the phrase “closed contour line,” as used herein, denotes a particular contour line (e.g., a line, a curve, etc.) that extends along a closed pathway on the surface of a transparent workpiece (e.g., along a surface of a transparent sheet). The closed contour line defines a desired perimeter of a transparent article, which may be singulated from the rest transparent sheet. Further, the phrase “contour,” as used herein, refers to a plurality of defects introduced into the transparent workpiece using various techniques along the contour line and the phrase “closed contour,” as used herein, refers to a contour that is formed along a closed contour line. Moreover, as used herein, a “defect” may include an area of modified material (relative to the bulk material), void space, scratch, flaw, hole, or other deformities in the transparent workpiece which enables controlled separation of material of the transparent sheet along the contour lines and closed contour lines (e.g., separation of the contours and the closed contours) to form transparent articles from the transparent sheets. The physical separation of the transparent articles from the sheet material surrounding them, which occurs when a crack fully propagates around the internal contours, may be accomplished by additional processing, such as by infrared laser processing (e.g. a carbon dioxide laser) to apply thermal stress, application of mechanical bending stress, use of ion exchange to create stress in the glass, or other separation processes. The defects may penetrate the full depth of the glass. It should be understood that while sometimes described as “holes” or “hole-like,” the defects disclosed herein may generally not be void spaces, but are rather portions of the transparent sheet which has been modified by laser processing as described herein.

[0076] FIGS . 1 A and IB schematically depict a transparent article 52 according to one or more embodiments of the present disclosure. The transparent article 52 is formed by the process described herein. Particularly, as shown in FIGS. 1A and IB, the transparent article 52 has been formed from a transparent workpiece (not shown) that has been separated and singulated from a transparent sheet after being ion exchanged and subjected to surface treatments while engaged with a frame portion of the transparent sheet. After separation from the transparent sheet, the depicted transparent article 52 is the result of subjecting the transparent workpiece to a suitable polishing process (e.g., brush polishing). FIG. 1A depicts a perspective view of the transparent article 52. FIG. IB depicts a cross-sectional view through the line I-I in FIG. 1A, with the line I-I extending through a geometric center C of the part and in a direction perpendicular to polished edges 58 of the glass substrate. As shown, the transparent article 52 comprises a first major surface 54, a second major surface 56 disposed opposite to the first major surface 54, and a plurality of polished edges 58 extending between the first major surface 54 and the second major surface 56 at the periphery of the transparent article 52. Substantial (e.g., majority) portions of the first and second major surfaces 54 and 56 can extend parallel to one another. Central portions of the first and second major surfaces 54 and 56 may be substantially planar in shape (e.g., exhibiting an Ra value that is less than or equal to 100 nm, such as from 1 nm to 20 nm, or even less than or equal to lOnm), with such portions of the first major surface 54 that are unmodified during polishing residing in the X-Y plane depicted in FIGS. 1A and IB. The X-Y plane may represent a vertical position of an average surface height of unmodified portions of the first major surface 54 (e.g., measured via white light interferometry) when measured relative to a common reference point in the coordinate system represented in FIGS. 1A-1B. While FIGS. 1A-1B depict a transparent article 52 with a rectangular peripheral shape, it should be understood that the present disclosure is applicable to transparent articles having any shape and any number of distinct polished edges (e.g., a circular glass substrate may have a single polished edge). Embodiments are also envisioned where the major surfaces of the transparent article 52 are not planar (e.g., they can be curved).

[0077] As a result of the polishing processes described herein, the first major surface 54 can include a first peripheral region 60 extending outward from a boundary 62 to the polished edges 58. The first peripheral region 60 therefore represents a portion of the first major surface 54 that was modified during a polishing process (e.g., a rounded comer). As shown in FIG. IB, the second major surface 56 can also include a second peripheral region 70 from the polishing process. In embodiments, for example, a brush polishing process can be employed, with such brush polishing inducing slurry flow lines and brush marks in the polished edges 58 and/or the first and second peripheral regions 60 and 70. In embodiments, material removal via the polishing process described herein is symmetrical so that the polished edges include comers 64 and 74 that have a have substantially similar shape. In embodiments, material removal is asymmetric so that the comers 64 and 74 have different shapes (e.g., different chamfers). While FIGS. 1A and IB include the first and second peripheral regions 60 and 70 where material is removed from major surfaces the transparent workpiece during polishing in forming the transparent article 52, embodiments are also envisioned where no material is removed from the major surface and the first and second peripheral regions 60 and 70 are absent.

[0078] Various structural and compositional details of the transparent article 52 will now be provided. In embodiments the transparent article 52 has a thickness t that is substantially constant over the width and length of the transparent article 52 (e.g., inward of the first and second peripheral regions 60 and 70). The thickness t is defined as a distance (in the Z- direction) between the first major surface 54 and the second major surface 56. In various embodiments, t may refer to a maximum thickness of the transparent article 52 (in portions unmodified during polishing). In addition, the transparent article 52 includes a width W defined as a first maximum dimension of one of the first or second major surfaces 54, 56 orthogonal to the thickness t, and a length L defined as a second maximum dimension of one of the first or second major surfaces 54, 56 orthogonal to both the thickness and the width. In various embodiments, width W and the length L are a range from 5 cm to 250 cm. [0079] In various embodiments, thickness t is 6 mm or less. In particular embodiments, the thickness t is from 0.30 mm to 2.0 mm. For example, thickness t may be in a range from about 0.30 mm to about 2.0 mm, from about 0.40 mm to about 2.0 mm, from about 0.50 mm to about 2.0 mm, from about 0.60 mm to about 2.0 mm, from about 0.70 mm to about 2.0 mm, from about 0.30 mm to about 1.9 mm, from about 0.30 mm to about 1.8 mm, from about 0.30 mm to about 1.7 mm, from about 0.30 mm to about 1.6 mm, from about 0.30 mm to about 1.5 mm, from about 0.30 mm to about 1.4 mm, from about 0.30 mm to about 1.4 mm, from about 0.30 mm to about 1.703 mm, from about 0.30 mm to about 1.2 mm, from about 0.30 mm to about 1.1 mm, from about 0.30 mm to about 1.0 mm, from about 0.30 mm to about 0.90 mm, from about 0.30 mm to about 0.80 mm, from about 0.30 mm to about 0.70 mm, from about 0.30 mm to about 0.60 mm, or from about 0.30 mm to about 0.40 mm. In other embodiments, the t falls within any one of the exact numerical ranges set forth in this paragraph.

[0080] The composition of the transparent article 52 is not particularly limited. In embodiments, the transparent article 52, may be formed from any suitable glass composition comprising soda lime glass, aluminosilicate glass, borosilicate glass, boroaluminosilicate glass, alkali-containing aluminosilicate glass, alkali-containing borosilicate glass, and alkali- containing boroaluminosilicate glass.

[0081] As shown in FIGS. 1A and IB, the transparent article 52 is chemically strengthened to comprise layers in which a concentration of an exchanged ion is heightened compared to a bulk of the glass article (e.g., at the geometric center C). Such layers can approximately correspond to regions within the transparent article 52 that are under a compressive stress from the presence of the exchanged ion. As shown in FIG. IB, in the depicted embodiment, the transparent article 52 comprises a first layer 76 extending from the first major surface 54 to a first depth of layer (DOLi) in the Z-direction and a second layer 78 extending from the second major surface 56 to a second depth of layer (DOL2). The transparent article 52 further comprises edge layers 80 extending inward from polished edges 58. As depicted, the edge layers 80 can have an edge depth of layer DOLE extending inward from the polished edge 58 that forms an outer boundary of each edge layer. The edge depth of layer DOLE is measured in a direction parallel to the X- Y plane described herein with respect to FIG. 1A.

[0082] In the process described herein, the layers 76, 78, 80 are formed during ion exchange strengthening a transparent glass sheet having a plurality of defects in one or more contours, with the contours serving as conduits for ion exchange to form the edge layers 80. In the ion exchange process, ions at or near an outer surface 81 of the transparent article 52 are replaced by - or exchanged with - larger ions from a salt bath having the same valence or oxidation state (hereinafter referred to as the “larger ion” or “exchanged ion”). As described herein, the ions from the salt bath also diffuse into the defects to form the edge layers 80 when the workpiece is still a component of the transparent sheet. In embodiments in which the transparent article 52 comprises an alkali aluminosilicate glass, ions in the layers 76, 78, 80 of the article and the larger ions are monovalent alkali metal cations, such as Li+, Na+, K+, Rb+, and Cs+. Alternatively, monovalent cations in the layers 76, 78, 80 may be replaced with monovalent cations other than alkali metal cations, such as Ag+ or the like. In such embodiments, the monovalent ions (or cations) exchanged into the glass article generate a compressive stress.

[0083] Ion exchange processes are typically carried out by immersing a glass article in a molten salt bath (or two or more molten salt baths) containing the larger ions to be exchanged with the smaller ions in the glass article. It should be noted that aqueous salt baths may also be utilized. In addition, the composition of the bath(s) may comprise more than one type of larger ion (e.g., Na+ and K+) or a single larger ion. It will be appreciated by those skilled in the art that parameters for the ion exchange process, comprising, but not limited to, bath composition and temperature, immersion time, the number of immersions of the glass article in a salt bath (or baths), use of multiple salt baths, additional steps such as annealing, washing, and the like, are generally determined by the composition of the glass layer(s) of a decorated glass structure (comprising the structure of the article and any crystalline phases present) and the desired depth of compression DOC and surface compressive stress (surface CS) of the glass layer(s) of a decorated glass structure that results from strengthening. Exemplary molten bath composition may comprise nitrates, sulfates, and chlorides of the larger alkali metal ion. Typical nitrates comprise KNO3, NaNO.v LiNO.v NaSOr and combinations thereof. The temperature of the molten salt bath typically is in a range from about 380°C up to about 500°C, while immersion times range from about 15 minutes up to about 100 hours depending on the glass thickness, bath temperature and glass (or monovalent ion) diffusivity. However, temperatures and immersion times different from those described above may also be used. As used herein, “depth of compression” (DOC) refers to the depth at which the stress within the glass article changes from compressive to tensile stress. At the DOC, the stress crosses from a positive (compressive) stress to a negative (tensile) stress and thus exhibits a stress value of zero. According to the convention normally used in mechanical arts, compression is expressed as a negative (< 0) stress and tension is expressed as a positive (> 0) stress. Throughout this description, however, compressive stress (CS) and central tension (CT) is expressed as a positive or absolute value - i.e., as recited herein, CS = I CS I and CT = | CT | .

[0084] In embodiments, the transparent sheet from which the transparent article 52 is formed may be immersed in a molten salt bath of 100% NaNCh, 100% KNO3, or a combination of NaNO. and KNO3 having a temperature from about 370 °C to about 500 °C. In some embodiments, the transparent sheet may be immersed in a molten mixed salt bath comprising from about 5% to about 90% KNO3 and from about 10% to about 95% NaNCh. In one or more embodiments, the transparent sheet may be immersed in a second bath, after immersion in a first bath. The first and second baths may have different compositions and/or temperatures from one another. The immersion times in the first and second baths may vary. For example, immersion in the first bath may be longer than the immersion in the second bath. In embodiments, the transparent sheet may be immersed in a molten, mixed salt bath comprising NaNCL and KNO3 (e.g., 49%/51%, 50%/50%, 51%/49%) having atemperature less than about 420 °C (e.g., about 400 °C or about 380 °C), for less than about 5 hours, or even about 4 hours or less.

[0085] Compressive stress (CS) is measured using those means known in the art, such as by surface stress meter (FSM) using commercially available instruments such as the FSM-6000, manufactured by Orihara Industrial Co., Ltd. (Japan). Surface stress measurements rely upon the accurate measurement of the stress optical coefficient (SOC), which is related to the birefringence of the glass. SOC in turn is measured by those methods that are known in the art, such as fiber and four point bend methods, both of which are described in ASTM standard C770-98 (2013), entitled “Standard Test Method for Measurement of Glass Stress-Optical Coefficient,” the contents of which are incorporated herein by reference in their entirety, and a bulk cylinder method. As used herein CS may be the “maximum compressive stress” which is the highest compressive stress value measured within the compressive stress layer. In some embodiments, the maximum compressive stress is located at the surface of the glass article. In other embodiments, the maximum compressive stress may occur at a depth below the surface, giving the compressive profile the appearance of a “buried peak.”

[0086] Depth of compression may be measured by FSM or by a scattered light polariscope (SCALP) (such as the SCALP-04 scattered light polariscope available from GlasStress Ltd., located in Tallinn Estonia), depending on the strengthening method and conditions. When the glass article is chemically strengthened by an ion exchange treatment, FSM or SCALP may be used depending on which ion is exchanged into the glass article. Where the stress in the glass article is generated by exchanging potassium ions into the glass article, FSM is used to measure DOC. Where the stress is generated by exchanging sodium ions into the glass article, SCALP is used to measure DOC. Where the stress in the glass article is generated by exchanging both potassium and sodium ions into the glass, the DOC is measured by SCALP, since it is believed the exchange depth of sodium indicates the DOC and the exchange depth of potassium ions indicates a change in the magnitude of the compressive stress (but not the change in stress from compressive to tensile); the exchange depth of potassium ions in such glass articles is measured by FSM. Central tension or CT is the maximum tensile stress and is measured by SCALP.

[0087] With continued reference to FIG. IB, it is believed that using the laser parameters described herein to form defects leads to particularly effective ion exchange at the contours in the transparent sheet. As a result, in the edge layers 80, the concentration of the exchanged ion is elevated above that of the bulk throughout an entirety of the polished edge 58 and the entirety of the polished edge 58 is under compressive stress. As described in greater detail herein, the concentration of the exchanged ion may not significantly vary from the layers 76, 78, 80. In embodiments, for example, a maximum value of the concentration of the exchanged ion occurs in the first layer 76 and/or or the second layer 78. However, as a result of the effective ion exchange achieved via the defects described herein, a minimum value of the concentration of the exchanged ion along the polished edge 58 in the edge layers 80 can be at least 50% of this maximum value, even after polishing removes material from the transparent workpiece.

[0088] Each of the polished edges 58 includes a central segment 90. As shown, a first boundary of the central segment 90 is disposed a distance 93 in the Z-direction from the first major surface 54 and a second boundary of the central segment 90 is disposed a distance 94 in the Z- direction from the second major surface 56. The distances 93, 94 are greater than DOLi and DOL2. As a result, each central segment 90 represents a portion of one of the polished edges 58 that does not overlap with either the first layer 76 and the second layer 78. The central segment 90 is strengthened solely by introduction of exchanged ions through the laser processing-induced defects described herein. In embodiments, the distances 93, 94 are greater than 0.1 *t (e.g., when t is 1.0 mm or greater, then the distances 93, 94 are greater than 100 pm) and less than 0.2*t). As described in greater detail herein, the effective ion exchange through the defects generated during laser processing the transparent sheet effectuate very uniform ion exchange throughout the central segment 90 such that, over the central segment 90, the concentration of the exchanged ion varies by no more than 20% of a minimum value of the concentration along the polished edge 58. Such uniform concentration of the exchanged ion throughout the central segment 90 indicates a uniform amount of compressive stress therein, which contributes to edge strength.

[0089] As a result of the edge of the transparent workpiece being subjected to polishing to form the polished edge 58, DOLE is less than DOLi and DOL2. In embodiments, DOLE is at least 5 pm (or at least 10 pm, such as, 10 pm, 11 pm, 12, pm, 13 pm, 14 pm, 15 pm, 16 pm, 17 pm, 18 pm, 19 pm, 20 pm, 30 pm, 40 pm or any value between such differences) less than DOLi and DOL2. The difference between DOLE and DOLi, DOL2 may roughly correspond to an amount of material removed from the edge of the transparent workpiece during polishing. A benefit of the laser processing techniques described herein is that relatively high edge strength (e.g., a plurality of the transparent articles 52 from the same transparent sheet may exhibit a Weibull distribution with a B 10 value that is greater than or equal to 700 MPa, when tested for mechanical edge strength using a four-point bend test in accordance with ASTM C158-02) can be achieved with relatively low amounts of material removal from the transparent workpiece. In embodiments, polishing can be conducted to remove only 20 pm or less (e.g., 5 pm to 20 pm, 10 pm to 20 pm) of material from the edge of the transparent workpiece to provide the transparent article 52 with such an edge strength. The transparent workpiece (prior to edge polishing) may exhibit an edge DOL (not depicted) that is greater than an amount of material removed during the edge polishing, such that DOLE in the resultant transparent article 52 is greater than 20 pm and at least 50% of DOLi and DOL2.

[0090] In embodiments, DOLi and DOL2 may be equal to or greater than about 0.05t, equal to or greater than about 0. It, equal to or greater than about 0. 1 It, equal to or greater than about 0. 12t, equal to or greater than about 0. 13t, equal to or greater than about 0. 14t, equal to or greater than about 0.15t, equal to or greater than about 0.16t, equal to or greater than about 0. 17t, equal to or greater than about 0. 18t, equal to or greater than about 0. 19t, equal to or greater than about 0.2t, equal to or greater than about 0.2 It. In some embodiments, DOLi and DOL2 may be in a range from about 0.08t to about 0.25t, from about 0.09tto about 0.25t, from about 0.18t to about 0.25t, from about 0.1 It to about 0.25t, from about 0.12t to about 0.25t, from about 0.13t to about 0.25t, from about 0. 14t to about 0.25t, from about 0.15t to about 0.25t, from about 0.08t to about 0.24t, from about 0.08t to about 0.23t, from about 0.08t to about 0.22t, from about 0.08t to about 0.2 It, from about 0.08t to about 0.2t, from about 0.08t to about 0. 19t, from about 0.08t to about 0. 18t, from about 0.08t to about 0. 17t, from about 0.08t to about 0.16t, or from about 0.08t to about 0. 15t . In one or more embodiments, DOLi and DOL2 may be about 25 pm or greater (e.g., from about 25 pm to about 300 pm, from about 30 pm to about 300 pm, from about 40 pm to about 300 pm, from about 50 pm to about 300 pm, from about 60 pm to about 300 pm, from about 70 pm to about 300 pm, from about 80 pm to about 300 pm, from about 90 pm to about 300 pm, from about 100 pm to about 300 pm, from about 110 pm to about 300 pm, from about 120 pm to about 300 pm, from about 140 pn to about 300 pn, from about 150 pn to about 300 pn, from about 40 pn to about 290 pn, from about 40 pn to about 280 pn, from about 40 pn to about 260 pn, from about 30 pn to about 250 pn, from about 30 pn to about 240 pn, from about 40 pn to about 230 pn, from about 40 pn to about 220 pn, from about 40 pn to about 210 pn, from about 40 pn to about 200 pn, from about 40 pn to about 180 pn, from about 40 pn to about 160 pn, from about 40 pn to about 150 pn, from about 40 pn to about 140 pn, from about 40 pn to about 130 pn, from about 40 pn to about 120 pn, from about 40 pn to about 110 pn, or from about 40 pn to about 100 pn.

[0091] In embodiments, the first and second layers 76 and 78 may exhibit a maximum compressive stress (which may be found at the surface or a depth within the glass article) of about 200 MPa or greater, 300 MPa or greater, 400 MPa or greater, about 500 MPa or greater, about 600 MPa or greater, about 700 MPa or greater, about 800 MPa or greater, about 900 MPa or greater, about 930 MPa or greater, about 1000 MPa or greater, or about 1050 MPa or greater. In embodiments, a central portion 96 of the transparent article 52, in which the concentration of the exchanged ion is not elevated, exhibits a maximum tensile stress or central tension (CT) of about 20 MPa or greater, about 30 MPa or greater, about 40 MPa or greater, about 45 MPa or greater, about 50 MPa or greater, about 60 MPa or greater, about 70 MPa or greater, about 75 MPa or greater, about 80 MPa or greater, or about 85 MPa or greater. In some embodiments, the maximum tensile stress or central tension (CT) may be in a range from about 40 MPa to about 100 MPa.

[0092] Referring still to FIG. IB, in embodiments, the polished edges 58 exhibit a relatively low surface roughness. For example, in embodiments, the polished edges 58 exhibit an Ra value that is greater than or equal to 1 nm and less than or equal to 100 nm (e.g., greater than or equal to 1 nm and less than or equal to 20 nm). As used herein, the term “Ra value” refers to a surface roughness measure of the arithmetic average value of a fdtered roughness profile determined from deviations from a centerline of the filtered roughness. For example, a Ra value may be determined based on the relation: where Hi is a surface height measurement of the surface and HCL corresponds to a centerline (e.g., the center between maximum and minimum surface height values) surface height measurement among the data points of the filtered profile. Filter values (e.g., cutoff wavelengths) for determining the Ra values described herein may be found in ISO 25178. Surface height may be measured with a variety of tools, such as an optical interferometer, stylus-based profilometer, or laser confocal microscope. Unless otherwise specified herein, Ra, rms, and PV values were measured via an optical interferometer. Alternatively or additionally, the polished edges 58 can exhibit a rms roughness (calculated from the same measurements used to determine the Ra value) that is greater than or equal to 1 nm and less than or equal to 30 nm. Alternatively or additionally, the polished edges can exhibit a PV surface roughness that is greater than or equal to 10 nm and less than or equal to 50 nm. As such, the polished edges 58 described herein can exhibit at least one of: (a) an Ra surface roughness that is greater than or equal to 1 nm and less than or equal to 100 nm; (b) a root mean squared surface roughness that is greater than or equal to 1 nm and less than or equal to 30 nm and (c) a peak to valley surface roughness that is greater than or equal to 10 nm and less than or equal to 50 nm. The process described herein can produce edges directly after laser cutting (prior to any brush polishing) that exhibit Ra values of approximately 1 pm.

[0093] Another benefit of the process described herein is that surface treatments can be applied to the transparent workpiece prior to separation of the transparent workpiece from the transparent sheet. The allows such treatments to be applied to each workpiece formed from the transparent sheet in a batch and eliminates costs and complexities associated with individual part handling. In the example shown in FIG. IB, the transparent article 52 includes a decoration layer 92 disposed on the second major surface 56. The decoration layer 92 may be any suitable decoration for providing the transparent article 52 a desired appearance. For example, in embodiments, the decoration layer 92 is a suitable black matrix ink applied by existing processes (e.g., inkjet printing, screen printing). In embodiments, the decoration layer 92 is a black ink comprising a thickness of less than 100 pm and exhibiting an optical density of at least 3.0 in the visible spectrum from 400 to 700 nm. The particular pattern formed on the second major surface 56 by the decoration layer 92 is not particularly limiting. For example, the decoration layer 92 may include a central opening (not depicted) having a peripheral shape corresponding to the peripheral shape of the transparent article 52, such that the decoration layer 92 is a frame covering a periphery of the second major surface 56. While only the decoration layer 92 is shown, the transparent article 52 can include any other number of surface treatments that were applied while the workpiece is engaged with a frame portion of the transparent sheet. Such additional treatments can include one or more of anti-reflective coatings (disposed on one or both of the first and second major surfaces 54 and 56), anti-glare treatments (application of an anti-glare film, or roughening either the first major surface or second major surface 54 and 56 by etching, sandblasting, or other suitable treatment), provision of an easy-to-clean coating, or any other suitable surface treatment.

[0094] It should be noted that, in some embodiments, the laser does not interact with the decoration layer 92 during laser processing, as the laser processing is done before ion exchange, so after the transparent workpiece is singulated ,the decoration layer 92 has substantially the same pattern as it did when deposited on the transparent sheet. Moreover, the size and shape of the decoration boundary 94 may be set by the deposition process used (e.g., screen printing, inkjet printing, or the like) and be precisely controlled. In some embodiments, at least some of the decoration layer 92 can be removed during polishing the edges of the transparent workpiece in forming the transparent article 52. For example, brush polishing may be employed such that an outer portion of the decoration layer 92 is removed during brush polishing. For example, when brush polishing is employed to obtain the edge profile described herein, a decoration boundary 95 may exhibit slurry flow lines that are visible in 50 to 100 times magnification images, indicating that at least some of the material of the decoration layer 92 was removed during the polishing. The slurry flow lines are generally on the scale of 0.5 pm to 3 pm (in width). Such material removal during polishing of the decoration layer 92 (or any other surface treatments present) may result smoothing the decoration boundary 95 of the decoration layer 92 (e.g., so that the outer shape of the decoration layer 92 corresponds in shape to the periphery of the transparent article 52 formed by the polished edges 58). In other embodiments, the decoration layer 92 is not at all damaged during the process described herein. In such cases, brush polish conditions may be selected so that the shape of the decoration layer 92 may not be modified by brush polishing, which may increase material utilization and lower costs. This can be accomplished, for example, by altering the thickness of the interposer used between the individual glass pieces that comprise the polishing stack, as described in greater detail herein. A thicker interposer will allow more brush access to the glass surfaces and hence more decoration layer modification, whereas a thinner interposer will inhibit brush access during polishing and prevent decoration layer modification.

[0095] FIG. 2A is a flow diagram of a process 200 for fabricating a transparent article, according to one or more embodiments of the present disclosure. For example, the process 200 can be used to fabricate the transparent article 52 described herein with respect to FIGS. 1A- 1B. At block 202, a transparent sheet is provided. The transparent sheet can be provided by melting batch materials in accordance with a suitable glass or glass-ceramic composition and using any suitable forming technique (e.g., a down-draw process or a float process) to form the transparent sheet from the batch materials.

[0096] At block 202, a pulsed laser beam is directed into the transparent sheet to form one or more contours therein. The one or more contours contain defects induced in the material of the transparent sheet by the pulsed laser beam, as described herein. The one or more contours outline one or more transparent workpieces to be formed from the transparent sheet. FIG. 2B schematically depicts a transparent sheet 160 with a closed contour 170 comprising defects being formed therein. FIG. 2B depicts a closed contour line 165 before laser processing (right side of FIG. 2B) and a closed contour 170 comprising defects 172 being formed along a closed contour line 165 (left side of FIG. 2B). While the closed contour 170 and closed contour line 165 depicted in FIG. 2A have 90 degree comers (such that the closed contour 170 has a rectangular shape), it is preferrable to include rounded comers to prevent cracks from occurring during ion exchange. Rounded comers also facilitate separation by guiding crack propagation. The closed contour line 165 delineates a line of intended separation along which the closed contour 170 may be formed in the transparent sheet 160 to form a transparent workpiece that is separated from the transparent sheet 160. In other words, each closed contour line 165 and closed contour 170 defines edges of a transparent workpiece that may be separated from the transparent sheet 160. Further, each closed contour 170 comprises a plurality of defects 172 that extend into the transparent sheet 160 and establish a path for separation of the material of the transparent sheet 160 enclosed by the closed contour 170 from the remaining portion of transparent sheet 160. This “remaining portion” need not be used to form any transparent workpieces. That is, the material of the transparent sheet 160 not contained in any of the closed contours 170 constitutes this remaining portion, which is referred to as the frame portion 180 of the transparent sheet 260 herein.

[0097] FIGS. 2C and 2D schematically depict one of the closed contours 170 shown in FIG. 2B being formed in the transparent sheet 160, according to an example embodiment. In operation, the closed contour 170 may be formed by irradiating the closed contour line 165 with the pulsed laser beam 112 (depicted as the beam spot 114 in FIG. 2B) and translating the pulsed laser beam 112 and the transparent sheet 160 relative to each other along the closed contour line 165 in the translation direction 101 to form the defects 172 of the closed contour 170.

[0098] FIGS. 2C and 2D depict the pulsed laser beam 112 along a beam pathway 111 and oriented such that the pulsed laser beam 112 may be focused into a pulsed laser beam focal line 113 within the transparent sheet 160, for example, using an aspheric optical element 120 (FIG. 2E), for example, an axicon and one or more lenses (e.g., a first lens 130 and a second lens 132, as described below and depicted in FIG. 2E). For example, the position of the pulsed laser beam focal line 113 may be controlled along the Z-axis and about the Z-axis. Further, the pulsed laser beam focal line 113 may have a length in a range of from about 0. 1 mm to about 100 mm or in a range of from about 0. 1 mm to about 10 mm. Various embodiments may be configured to have a pulsed laser beam focal line 113 with a length 1 of about 0. 1 mm, about 0.2 mm, about 0.3 mm, about 0.4 mm, about 0.5 mm, about 0.7 mm, about 1 mm, about 2 mm, about 3 mm, about 4 mm, or about 5 mm e.g., from about 0.5 mm to about 5 mm. Further, the pulsed laser beam focal line 113 may be a portion of a quasi -non-diffracting beam, as defined in more detail below.

[0099] FIG. 2C depicts that the pulsed laser beam 112 forms a beam spot 114 projected onto a first major surface 162 of the transparent sheet 160. While the pulsed laser beam 112 is depicted initially irradiating the transparent sheet 160 at the first major surface 162 in FIG. 1A, it should be understood that in other embodiments, the pulsed laser beam 112 may instead initially irradiate the transparent sheet 160 at a second major surface 164. Further, as also used herein “beam spot” refers to a cross section of a laser beam (e.g., the pulsed laser beam 112) at a point of first contact with a transparent workpiece (e.g., the transparent sheet 160).

[00100] While the closed contour 170 is depicted in FIGS. 2B and 2C as a rectangle, it should be understood that other closed configurations are contemplated and possible including, without limitation, circles, ellipses, squares, hexagons, ovals, regular geometric shapes, irregular shapes, polygonal shapes, arbitrary shapes, and the like. Further, as depicted in FIG. 2B, the embodiments described herein may be used to form multiple closed contours 170 in the transparent sheet 160 and thereby form multiple transparent workpieces therefrom. The workpieces can vary in size and/or shape form one another.

[00101] Referring still to FIGS. 2B and 2C, in the embodiments described herein, a pulsed laser beam 112 (with a beam spot 114 projected onto the transparent sheet 160) may be directed onto the transparent sheet 160 (e.g., condensed into ahigh aspect ratio line focus that penetrates through at least a portion of the thickness of the transparent sheet 160). This forms the pulsed laser beam focal line 113. Further, the beam spot 114 is an example cross section of the pulsed laser beam focal line 113 and when the pulsed laser beam focal line 113 irradiates the transparent sheet 160 (forming the beam spot 114), the pulsed laser beam focal line 113 penetrates at least a portion of the transparent sheet 160.

[00102] Further, the pulsed laser beam 112 may be translated relative to the transparent sheet 160 (e.g., in the translation direction 101) to form the plurality of defects 172 of the closed contour 170. Directing or localizing the pulsed laser beam 112 into the transparent sheet 160 generates an induced absorption within the transparent sheet 160 and deposits enough energy to break chemical bonds in the transparent sheet 160 at spaced locations along the closed contour line 165 to form the defects 172. According to one or more embodiments, the pulsed laser beam 112 may be translated across the transparent sheet 160 by motion of the transparent sheet 160 (e.g., motion of atranslation stage 190 coupled to the transparent sheet 160, as shown in FIG. 2E), motion of the pulsed laser beam 112 (e.g., motion of the pulsed laser beam focal line 113), or motion of both the transparent sheet 160 and the pulsed laser beam focal line 113. By translating the pulsed laser beam focal line 113 relative to the transparent sheet 160, the plurality of defects 172 may be formed in the transparent sheet 160.

[00103] In some embodiments, the defects 172 may generally be spaced apart from one another by a distance along the closed contour 170 of from about 0. 1 pm to about 500 pm, for example, about 1 pm to about 200 pm, about 2 pm to about 100 pm, about 5 pm to about 30 pm, or the like. For example, suitable spacing between the defects 172 may be from about 0. 1 pm to about 50 pm, such as from about 5 pm to about 15 pm, from about 5 pm to about 12 pm, from about 7 pm to about 15 pm, or from about 7 pm to about 12 pm. In some embodiments, a spacing between adjacent defects 172 may be about 50 pm or less, 45 pm or less, 40 pm or less, 35 pm or less, 30 pm or less, 25 pm or less, 20 pm or less, 15 pm or less, 10 pm or less, or the like. In embodiments, the spacing of the defects used is based on a shape of the beam spot 114. For example, in embodiments, the pulsed laser beam 112 (and hence the beam spot 114) has a substantially axisymmetric cross-sectional shape. In such embodiments, the spacing between adjacent defects is relatively small (e.g., less than or equal to 10 pm or approximately 5 pm). In other embodiments, the pulsed laser beam 112 (and hence the beam spot 114) has a non-axisymmetric (e.g., elliptical) cross-sectional shape. For example, any of the techniques described in U.S. Patent No. 10,730,783 can be employed to provide such a non- axisymmetric beam shape, which controls the directionality of microcracks that extend from the defects 172 so that such microcracks from adjacent defects 172 connect to one another to facilitate separation. In such embodiments, the spacing between adjacent defects 172 may be larger than when axisymmetric beam spots or used, such as greater than or equal to 20 pm or approximately 30 pm. It is believed that either axisymmetric or non-axisymmetric beams shapes can be employed in the process described herein, yielding similar ion exchange and edge strength results.

[00104] With reference to FIGS. 2B and 2C, the pulsed laser beam 112 at the beam spot 114 or other cross sections may comprise a quasi -non-diffracting beam, for example, a beam having low beam divergence as mathematically defined below, by propagating the pulsed laser beam 112 (e.g., outputting the pulsed laser beam 112, such as a Gaussian beam, using a beam source 110) through an aspheric optical element 120, as described in more detail below with respect to the optical assembly 100 depicted in FIG. 2E. Beam divergence refers to the rate of enlargement of the beam cross section in the direction of beam propagation (i.e., the Z direction). As used herein, the phrase “beam cross section” refers to the cross section of the pulsed laser beam 112 along a plane perpendicular to the beam propagation direction of the pulsed laser beam 112, for example, along the X-Y plane. One example beam cross section discussed herein is the beam spot 114 of the pulsed laser beam 112 projected onto the transparent sheet 160. Example quasi non-diffracting beams include Gauss-Bessel beams and Bessel beams.

[00105] As used herein, the term “quasi-non-diffracting beam” is used to describe a laser beam having low beam divergence as mathematically described below. In particular, the laser beam 112 has an intensity distribution I(X,Y,Z), where Z is the beam propagation direction of the laser beam, and X and Y are directions orthogonal to the beam propagation direction, as depicted in the FIGS . 2B-2E. The X-direction and Y -direction may also be referred to as cross- sectional directions and the X-Y plane may be referred to as a cross-sectional plane. The coordinates and directions X, Y, and Z are also referred to herein as x, y, and z; respectively. The intensity distribution of the laser beam in a cross-sectional plane may be referred to as a cross-sectional intensity distribution.

[00106] The length of the laser beam focal line 113 produced from a quasi-non-diffracting beam is determined by the Rayleigh range of the quasi-non-diffracting beam. Particularly, the quasi-non-diffracting beam defines a laser beam focal line 113 having a first end point and a second end point each defined by locations where the quasi-non-diffracting beam has propagated a distance from the beam waist equal to a Rayleigh range of the quasi-non- diffracting beam. The length of the laser beam focal line corresponds to twice the Rayleigh range of the quasi-non-diffracting beam. A detailed description of the formation of quasi-non- diffracting beams and determining their length, including a generalization of the description of such beams to asymmetric (such as non-axi symmetric) beam cross sectional profiles, is provided in U.S. Pat. No. 10,730,783 which is incorporated by reference in its entirety.

[00107] The Rayleigh range corresponds to the distance (relative to the position of the beam waist as defined in Section 3.12 of ISO 11146-1 :2005(E)) over which the variance of the laser beam doubles (relative to the variance at the position of the beam waist) and is a measure of the divergence of the cross sectional area of the laser beam. The Rayleigh range can also be observed as the distance along the beam axis at which the peak optical intensity observed in a cross sectional profile of the beam decays to one half of its value observed in a cross sectional profile of the beam at the beam waist location (location of maximum intensity). Laser beams with large Rayleigh ranges have low divergence and expand more slowly with distance in the beam propagation direction than laser beams with small Rayleigh ranges.

[00108] Beam cross section is characterized by shape and dimensions. The dimensions of the beam cross section are characterized by a spot size of the beam. For a Gaussian beam, spot size is frequently defined as the radial extent at which the intensity of the beam decreases to 1/e² of its maximum value. The maximum intensity of a Gaussian beam occurs at the center (x = 0 and y = 0 (Cartesian) or r = 0 (cylindrical)) of the intensity distribution and radial extent used to determine spot size is measured relative to the center. [00109] Beams with Gaussian intensity profiles may be less preferred for laser processing to form defects 172 because, when focused to small enough spot sizes (such as spot sizes in the range of microns, such as about 1-5 pm or about 1-10 pm) to enable available laser pulse energies to modify materials such as glass, they are highly diffracting and diverge significantly over short propagation distances (low Rayleigh range). To achieve low divergence (high Rayleigh range), it is desirable to control or optimize the intensity distribution of the laser beam to reduce diffraction. Laser beams may be non-diffracting or weakly diffracting. Weakly diffracting laser beams include quasi-non-diffracting laser beams. Representative weakly diffracting laser beams include Bessel beams, Gauss-Bessel beams, Airy beams, Weber beams, and Mathieu beams.

[00110] Non-diffracting or quasi-non-diffracting beams generally have complicated intensity profiles, such as those that decrease non-monotonically vs. radius. By analogy to a Gaussian beam, an effective spot size w₀,eff can be defined for any beam, even non-axisymmetric beams, as the shortest radial distance, in any direction, from the radial position of the maximum intensity (r = 0) at which the intensity decreases to 1/e² of the maximum intensity. Further, for axisymmetric beams w_Ojeff is the radial distance from the radial position of the maximum intensity (r = 0) at which the intensity decreases to 1/e² of the maximum intensity. A criterion for Rayleigh range ZR based on the effective spot size w_{0 e}ff for axisymmetric beams can be specified as non-diffracting or quasi-non-diffracting beams for forming damage regions in Equation (1), below:

2 ™O,eff

ZR P_D (2)

A where F_D is a dimensionless divergence factor having a value of at least 10, at least 50, at least 100, at least 250, at least 500, at least 1000, in the range from 10 to 2000, in the range from 50 to 1500, in the range from 100 to 1000. For a non-diffracting or quasi-non-diffracting beam the distance (Rayleigh range), Z_R in Equation (1), over which the effective spot size doubles, is F_D times the distance expected if a standard Gaussian beam profde were used. The dimensionless divergence factor F_D provides a criterion for determining whether or not a laser beam is quasi-non-diffracting. As used herein, the laser beam 112 is considered quasi-non- diffracting if the characteristics of the laser beam satisfy Equation (1) with a value of F_D > 10. As the value of F_D increases, the first, second, and third beams 122, 124, 126 approach a more nearly perfectly non-diffracting state. [00111] Additional information about Rayleigh range, beam divergence, intensity distribution, axisymmetric and non-axisymmetric beams, and spot size as used herein can also be found in the international standards ISO 11146-1 :2005(E) entitled “Lasers and laser-related equipment — Test methods for laser beam widths, divergence angles and beam propagation ratios — Part 1: Stigmatic and simple astigmatic beams”, ISO 11146-2:2005(E) entitled “Lasers and laser-related equipment — Test methods for laser beam widths, divergence angles and beam propagation ratios — Part 2: General astigmatic beams”, and ISO 11146-3:2004(E) entitled “Lasers and laser-related equipment — Test methods for laser beam widths, divergence angles and beam propagation ratios — Part 3: Intrinsic and geometrical laser beam classification, propagation and details of test methods”, the disclosures of which are incorporated herein by reference in their entirety

[00112] Referring now to PIG. 2E, an optical assembly 100 for producing a pulsed laser beam 112 that that is quasi-non-diffracting and forms the pulsed laser beam focal line 113 at the transparent sheet 160 using the aspheric optical element 120 (e.g., an axicon 122) is schematically depicted. The optical assembly 100 includes a beam source 110 that outputs the pulsed laser beam 112, and a first and second lens 130, 132.

[00113] Further, the transparent sheet 160 may be positioned such that the pulsed laser beam 112 output by the beam source 110 irradiates the transparent sheet 160, for example, after traversing the aspheric optical element 120 and thereafter, both the first lens 130 and the second lens 132. An optical axis 102 extends between the beam source 110 and the transparent sheet 160 along the Z-axis such that when the beam source 110 outputs the pulsed laser beam 112, the beam pathway 111 of the pulsed laser beam 112 extends along the optical axis 102. As used herein “upstream” and “downstream” refer to the relative position of two locations or components along the beam pathway 111 with respect to the beam source 110. For example, a first component is upstream from a second component if the pulsed laser beam 112 traverses the first component before traversing the second component. Further, a first component is downstream from a second component if the pulsed laser beam 112 traverses the second component before traversing the first component.

[00114] Referring still to FIG. 2E, the beam source 110 may comprise any known or yet to be developed beam source 110 configured to output pulsed laser beams 112. In operation, the defects 172 of the closed contour 170 (FIGS. 2B and 2C) are produced by interaction of the transparent sheet 160 with the pulsed laser beam 112 output by the beam source 110. In some embodiments, the beam source 110 may output a pulsed laser beam 112 comprising a wavelength of for example, 1064 nm, 1030 nm, 532 nm, 530 run, 355 nm, 343 run, or 266 nm, or 215 nm. Further, the pulsed laser beam 112 used to form defects 172 in the transparent sheet 160 may be well suited for materials that are transparent to the selected pulsed laser wavelength.

[00115] Suitable laser wavelengths for forming defects 172 are wavelengths at which the combined losses of linear absorption and scattering by the transparent sheet 160 are sufficiently low. In embodiments, the combined losses due to linear absorption and scattering by the transparent sheet 160 at the wavelength are less than 20%/mm, or less than 15%/mm, or less than 10%/mm, or less than 5%/mm, or less than 1%/mm, where the dimension “/mm” means per millimeter of distance within the transparent sheet 160 in the beam propagation direction of the pulsed laser beam 112 (e.g., the Z direction). Representative wavelengths for many glass workpieces include fundamental and harmonic wavelengths of Nd³⁺ (e.g. Nd³⁺:YAG or Nd³⁺:YVC>4 having fundamental wavelength near 1064 nm and higher order harmonic wavelengths near 532 nm, 355 nm, and 266 nm). Other wavelengths in the ultraviolet, visible, and infrared portions of the spectrum that satisfy the combined linear absorption and scattering loss requirement for a given substrate material can also be used.

[00116] In operation, the pulsed laser beam 112 output by the beam source 110 may create multi -photon absorption (MPA) in the transparent sheet 160. MPA is the simultaneous absorption of two or more photons of identical or different frequencies that excites a molecule from one state (usually the ground state) to a higher energy electronic state (i.e., ionization). The energy difference between the involved lower and upper states of the molecule is equal to the sum of the energies of the involved photons. MPA, also called induced absorption, can be a second-order or third-order process (or higher order), for example, that is several orders of magnitude weaker than linear absorption. It differs from linear absorption in that the strength of second-order induced absorption may be proportional to the square of the light intensity, for example, and thus it is a nonlinear optical process.

[00117] The perforation step that creates the one or more closed contours 170 (FIGS. 2B and 2C) may utilize the beam source 110 (e.g., an ultra-short pulse laser) in combination with the aspheric optical element 120, the first lens 130, and the second lens 132, to project the beam spot 114 on the transparent sheet 160 and generate the pulsed laser beam focal line 113. The pulsed laser beam focal line 113 comprises a quasi-non-diffracting beam, such as a Gauss- Bessel beam or Bessel beam, or such as a non-axisymmetric quasi-non diffracting beam (see U.S. Patent No. 10,730,783), as defined above, and may fully perforate the transparent sheet 160 to form defects 172 in the transparent sheet 160, which may form the closed contour 170. In some embodiments, the pulse duration of the individual pulses is in a range of from about 1 femtosecond to about 200 picoseconds, such as from about 1 picosecond to about 100 picoseconds, 5 picoseconds to about 20 picoseconds, or the like, and the repetition rate of the individual pulses may be in a range from about 1 kHz to 4 MHz, such as in a range from about 10 kHz to about 3 MHz, or from about 10 kHz to about 650 kHz.

[00118] Referring also to FIGS. 2F and 2G, in addition to a single pulse operation at the aforementioned individual pulse repetition rates, the pulses may be produced in pulse bursts 500 of two pulses 500A (e.g., sub-pulses) or more (such as, for example, 3 sub-pulses, 4 subpulses, 5 sub-pulses, 10 sub-pulses, 15 sub-pulses, 20 sub-pulses, or more per pulse burst, such as from 1 to 30 sub-pulses per pulse burst 500, or from 5 to 20 sub-pulses per pulse burst 500). While not intending to be limited by theory, a pulse burst is a short and fast grouping of subpulses that creates an optical energy interaction with the material (i.e. MPA in the material of the transparent sheet 160) on a time scale not easily accessible using a single-pulse operation. While still not intending to be limited by theory, the energy within a pulse burst (i.e. a group of pulses) is conserved. As an illustrative example, for a pulse burst having an energy of 100 pj/burst and 2 sub-pulses, the 100 pj/burst energy is split between the 2 pulses for an average energy of 50 pj per sub-pulse and for a pulse burst having an energy of 100 pj/burst and 10 sub-pulses, the 100 pj/burst is split amongst the 10 sub-pulses for an average energy of 10 pj per sub-pulse. Further, the energy distribution among the sub-pulses of a pulse burst does not need to be uniform. In fact, in some instances, the energy distribution among the sub-pulses of a pulse burst is in the form of an exponential decay, where the first sub-pulse of the pulse burst contains the most energy, the second sub-pulse of the pulse burst contains slightly less energy, the third sub-pulse of the pulse burst contains even less energy, and so on. However, other energy distributions within an individual pulse burst are also possible, where the exact energy of each sub-pulse can be tailored to effect different amounts of modification to the transparent sheet 160.

[00119] While still not intending to be limited by theory, when the defects 172 of the one or more closed contours 170 are formed with pulse bursts having at least two sub -pulses, the stress necessary to propagate a crack between adjacent defect sites, and hence to separate the transparent sheet 160 along closed contour 170 (i.e. the maximum break resistance) is reduced compared to the maximum break resistance of a closed contour 170 of the same shape with the same spacing between adjacent defects 172 that is formed using a single pulse laser. For example, the maximum break resistance of a closed contour 170 formed using a single pulse is at least two times greater than the maximum break resistance of a closed contour 170 formed using a pulse burst having 2 or more sub-pulses. Further, the difference in maximum break resistance between a closed contour 170 formed using a single pulse and a closed contour 170 formed using a pulse burst having 2 sub-pulses is greater than the difference in maximum break resistance between a closed contour 170 formed using a pulse burst having 2 sub-pulses and a pulse burst having 3 sub-pulses. Thus, pulse bursts may be used to form closed contours 170 that separate easier than closed contours 170 formed using a single pulse laser.

[00120] Referring still to FIGS. 2F and 2G, the sub-pulses 500A within the pulse burst 500 may be separated by a duration that is in a range from about 1 nsec to about 50 nsec, for example, from about 10 nsec to about 30 nsec, such as about 20 nsec. In other embodiments, the sub-pulses 500A within the pulse burst 500 may be separated by a duration of up to 100 psec (for example, 0.1 psec, 5 psec, 10 psec, 15 psec, 18 psec, 20 psec, 22 psec, 25 psec, 30 psec, 50 psec, 75 psec, or any range therebetween). For a given laser, the time separation T_p (FIG. 4B) between adjacent sub-pulses 500A within a pulse burst 500 may be relatively uniform (e.g., within about 10% of one another). For example, in some embodiments, each sub-pulse 500A within a pulse burst 500 is separated in time from the subsequent sub-pulse by approximately 20 nsec (50 MHz). Further, the time between each pulse burst 500 may be from about 0.25 microseconds to about 1000 microseconds, e.g., from about 1 microsecond to about 10 microseconds, or from about 3 microseconds to about 8 microseconds.

[00121] In some of the exemplary embodiments of the beam source 110 described herein, the time separation Tb (FIG. 2G) is about 5 microseconds for the beam source 110 outputting a pulsed laser beam 112 comprising a burst repetition rate of about 200 kHz. The laser burst repetition rate is related to the time Tb between the first pulse in a burst to the first pulse in the subsequent burst (laser burst repetition rate = 1/Tb). In some embodiments, the laser burst repetition rate may be in a range of from about 1 kHz to about 4 MHz. In embodiments, the laser burst repetition rates may be, for example, in a range of from about 10 kHz to 650 kHz. The time Tb between the first pulse in each burst to the first pulse in the subsequent burst may be from about 0.25 microsecond (4 MHz burst repetition rate) to about 1000 microseconds (1 kHz burst repetition rate), for example from about 0.5 microseconds (2 MHz burst repetition rate) to about 40 microseconds (25 kHz burst repetition rate), or from about 2 microseconds (500 kHz burst repetition rate) to about 20 microseconds (50k Hz burst repetition rate). The exact timing, pulse duration, and burst repetition rate may vary depending on the laser design, but short pulses (Ta <20 psec and, in some embodiments, Ta~ 15 psec) of high intensity have been shown to work particularly well.

[00122] The burst repetition rate may be in a range of from about 1 kHz to about 2 MHz, such as from about 1 kHz to about 200 kHz. The pulse burst laser beam may have a wavelength selected based on the material of the transparent sheet 160 being operated on such that the material of the transparent sheet 160 is substantially transparent at the wavelength. The average laser power per burst measured at the material may be at least about 40 pj per mm of thickness of material. For example, in embodiments, the average laser power per burst may be from about 40 pj/mm to about 2500 pj/mm, or from about 500 pj/mm to about 2250 pj/mm. The energy required to modify the transparent sheet 160 is the pulse energy, which may be described in terms of pules burst energy (i.e., the energy contained within a pulse burst 500 where each pulse burst 500 contains a series of sub-pulses 500A), or in terms of the energy contained within a single laser pulse (many of which may comprise a burst). The pulse energy (for example, pulse burst energy) may be from about 25 pj to about 750 pj, e.g., from about 50 p J to about 500 pj, or from about 50 pj to about 250 pj. For some glass compositions, the pulse energy (e.g., pulse burst energy) may be from about 100 pj to about 250 pj.

[00123] While not intending to be limited by theory, the use of a pulsed laser beam 112 capable of generating pulse bursts is advantageous for cutting or modifying transparent materials, for example glass (e.g., the transparent sheet 160). In contrast with the use of single pulses spaced apart in time by the repetition rate of the single-pulsed laser, the use of a burst sequence that spreads the pulse energy over a rapid sequence of pulses within the burst allows access to larger timescales of high intensity interaction with the material than is possible with single-pulse lasers. The use of pulse bursts (as opposed to a single pulse operation) increases the size (e.g., the cross-sectional size) of the defects 172, which facilitates the connection of adjacent defects 172 when separating transparent sheet 160 along the one or more closed contours 170 to form the transparent workpieces, thereby minimizing crack formation. Further, using a pulse burst to form defects 172 increases the randomness of the orientation of cracks extending outward from each defect 172 into the bulk material of the transparent sheet 160 such that individual cracks extending outward from defects 172 do not influence or otherwise bias the separation of the closed contour 170 such that separation of the defects 172 follows the closed contour 170, minimizing the formation of cracks extending into the transparent workpieces.

[00124] Referring again to FIG. 2E, the aspheric optical element 120 is positioned within the beam pathway 111 between the beam source 110 and the transparent sheet 160. In operation, propagating the pulsed laser beam 112, e.g., an incoming Gaussian beam, through the aspheric optical element 120 may alter the pulsed laser beam 112 such that the portion of the pulsed laser beam 112 propagating beyond the aspheric optical element 120 is quasi-non-diffracting, as described above. The aspheric optical element 120 may comprise any optical element comprising an aspherical shape. In some embodiments, the aspheric optical element 120 may comprise a conical wavefront producing optical element, such as an axicon lens, for example, a negative refractive axicon lens (e.g., negative axicon), a positive refractive axicon lens, a reflective axicon lens, a diffractive axicon lens, a programmable spatial light modulator axicon lens (e.g., a phase axicon), or the like.

[00125] In the embodiment depicted in FIG. 2E, the first lens 130 is positioned upstream the second lens 132 and may collimate the pulsed laser beam 112 within a collimation space 134 between the first lens 130 and the second lens 132. Further, the second lens 132 may focus the pulsed laser beam 112 into the transparent sheet 160, which may be positioned at an imaging plane 104. In some embodiments, the first lens 130 and the second lens 132 each comprise plano-convex lenses. When the first lens 130 and the second lens 132 each comprise planoconvex lenses, the curvature of the first lens 130 and the second lens 132 may each be oriented toward the collimation space 134. In other embodiments, the first lens 130 may comprise other collimating lenses and the second lens 132 may comprise a meniscus lens, an asphere, or another higher-order corrected focusing lens.

[00126] Referring again to FIG. 2A, at block 206, after the one or more closed contours are formed, the transparent sheet 160 is subjected to an ion exchange treatment. FIGS. 2B-2C will be referred to in the remaining description of the process 200. In the ion exchange treatment, the defects 172 serve as conduits for ion exchange, such that regions of the transparent sheet 160 directly adjacent to the closed contours 170 have a heightened concentration of an exchanged ion as compared to a bulk of the transparent sheet 160 (e.g., at a geometric center of the transparent sheet 160). The ion exchange treatment can be performed by immersing the transparent sheet 160, after formation of the closed contours 170, in a molten salt bath having any of the compositions described herein. The immersion time and temperature of the molten salt bath may have any suitable value, depending, among other factors, on the composition of the transparent sheet, the thickness of the transparent sheet 160, and a desired level of compressive stress after strengthening.

[00127] At block 208, once the ion exchange treatment is completed, one or more surface treatments can be applied to at least one of the first and second major surfaces 162, 164 of the transparent sheet 160. In embodiments, the one or more surface treatments can include at least one of depositing a decoration layer (e.g., depositing an ink layer on the first major surface 162 via inkjet or screen printing), application of an anti -glare surface treatment (e.g., subjecting the second major surface 164 to chemical etching or sandblasting), depositing an antireflective coating (e.g., depositing an anti-reflective coating anti-glare surface treatment comprising a plurality of alternating layers of low or high refractive index on the second major surface 164 and, in some cases, on an anti-glare treatment), and depositing an anti-fingerprint coating (e.g., depositing an ETC coating on the second major surface 164 or anti-reflective coating). Any suitable combination of surface treatments on either of the first and second major surfaces 162, 164 is possible.

[00128] FIG. 2H schematically depicts an example where the transparent sheet 160 has two closed contours 170 of defects 172 therein (so as to form two transparent workpieces from the transparent sheet 160. As shown, a decoration layer 150 is disposed within each of the closed contours 170. The decoration layer 150 can be deposited using any suitable technique (e.g., screen printing, inkjet printing, or the like). In embodiments, the decoration layer 150 is deposited onto the first major surface 162 in liquid form and subsequently cured (e.g., via exposure to radiation at a suitable wavelength and/heating) in a desired pattern. In the example shown, the decoration layer 150 is frame-shaped and extend inward of an entire circumference of a closed contour 170. In such embodiments, the decoration layer 150 is a black matrix implemented as a border on the resultant transparent article (e.g., as the decoration layer 92 depicted in FIG IB). While FIG. 2H depicts each decoration layer 150 as being disposed entirely inward of the corresponding closed contour 170, it should be understood that any of the surface treatments described herein can also extend over the closed contour 170. That is, any of the surface treatments described herein may be disposed in both the frame portion 180 and the areas of the transparent sheet 160 disposed inward of the closed contours 170 that are used to form transparent workpieces. Such extension over the closed contours 170 can facilitate complete coverage of the resultant transparent article.

[00129] Referring again to FIG. 2B, after application of all surface treatments that will be included in the resultant transparent article are applied, at block 210, the transparent workpieces are singulated from the transparent sheet. In embodiments, the separation can be performed by forming one or more release lines in the frame portion 180 of the transparent sheet 160. FIG. 21 schematically depicts an example where a plurality of release lines 152 are formed in the transparent sheet 160. The plurality of release lines 152 can be formed using any suitable cutting technique (e.g., by laser processing to form defects in accordance with the present disclosure or by mechanical cutting). In the example shown, at least some of the plurality of release lines 152 extend from the closed contours 170 to the perimeter surfaces 166 of the transparent sheet 160. Additionally, in embodiments, some ofthe release lines 152 can connect different ones of the closed contours 170 to one another. The plurality of release lines 152 can be formed in any suitable arrangement so that the frame portion 180 can be moved away from the areas of the transparent sheet 160 disposed inward of the closed contours 170. In operation, separating the frame portion 180 along the plurality of release lines 152 can include applying a stress to the release lines 152. Such a stress can be applied, for example, by directing an infrared laser beam along or near the plurality of release lines 152, applying a mechanical force to the plurality of release lines 152, or other suitable method. But typically the stress inside the glass sheet itself, which is imparted by the ion exchange process, is sufficient to propagate cracks along any release lines, immediately causing the glass pieces to separate, resulting in singulated workpieces. Application of such stress may release transparent workpieces 220 from engagement and with the frame portion 180, thereby removing the transparent workpieces 220 from contact with the frame portion 180.

[00130] At block 212, after separation and singulation from the frame portion 180, edges of the transparent workpieces 220 can be polished to form one or more transparent articles with polished edges. The polishing step can remove any chipping that occurs from the block 210 and subsequent handling of each of the transparent workpieces 220 individually. As described herein, a benefit of the process described herein is that an amount of polishing required to provide relatively high edge strength is relatively low. Applicant has found that typically only 10 pm to 20 pm of material removal from the transparent workpieces 220 is required to provide suitable edge strength for various applications, including preventing breakage of the resultant articles during headform impact testing for automotive interiors, as described herein. This is in stark contrast with other alternative process involving the cutting of individual parts and subjecting each individual part to ion exchange, which often requires grinding to remove much more (e.g., more than 100 pm) material to due to cutting damage, and then polishing. The process 200 beneficially eliminates such a grind step and minimizes the time and cost of the polishing step.

[00131] In embodiments, brush polishing is employed on the transparent workpieces 220 after separation from the frame portion 180. For example, in embodiments, a plurality of the transparent workpieces 220 can be subjected to a batch brush polishing process. FIG. 2J shows one embodiment of a stack of transparent workpieces 220 with an interposer 230 arranged between each pair of adjacent workpieces. As shown, a compressive force 232 may be applied to the stack, and edges 234 of the workpieces may be exposed to a brush 236. The shape of the interposer 230 can be selected depending on a desired shape of the polished edges 158 (see FIG. 1A). For example, in embodiments, the interposer 230 is smaller than the transparent workpieces 220 and, as a result, portions of opposing major surfaces 238, 240 of the transparent workpieces 220 can be exposed to the brush 236. Such an arrangement may result in the transparent article 52 have rounded comers (e.g., the first and second peripheral regions 60 and 70 described herein with respect to FIGS. 1A and IB). Other interposer configurations can be used to provide other edge shapes, as described in international patent application publication no. WO 2020/257034 Al, entitled “Method and Apparatus for Edge Finishing of High Mechanical Strength Thin Glass Substrates,” hereby incorporated by reference in its entirety.

[00132] In embodiments, the brush 236 can include bristles of any suitable shape. For example, the brush 236 can include cylindrical bristles composed of engineered filaments of small (< 0.200mm) diameter and a range of lengths fastened together in bundles or “tufts” of a range of sizes (e.g., 3-5mm), patterns (e.g., spiral, staggered, straight), and brush densities, and may be rotated at prescribed linear or surface speeds (10 - 1000 rpm). The workpieces 220 may be brush polished until residual subsurface damage is largely eliminated and the desired edge profile is imposed. Embodiments where the workpieces 220 are exposed to multiple brush polishing cycles are also envisioned (e.g., using the same brush in each successive cycle, or using a finer brush and/or different slurry in subsequent cycles). In embodiments, the brush polishing occurs using a polishing slurry. The polishing slurry may include a cerium oxide with a grain size ranging from 0.3 to 15.0 pm. The polishing slurry may include a mechanical abrasive slurry with an abrasive size ranging from 30 nm to 100 pm. Moreover, the polishing slurry may have an alkalinity ranging from pH 6-10. In some embodiments, the brush may have a plurality of filaments, each having a diameter of not more than 0.2 mm. Such a process may result in the transparent article 52 having polished edges 58 with a desired edge profile and so that the polished edges 58 have average roughness (Ra) of no more than 100 nm, root mean square roughness (Rms) of no more than 20 nm, and a peak to valley (PV) or no more than 500 nm.

Examples

[00133] Embodiments of the present disclosure may be further understood in view of the following examples.

Evaluation of Edge Strength and Impact Performance

[00134] To fabricate a first set of examples, two 50 mm x 100 mm closed contours were laser processed into a 190 mm x 190 mm transparent sheet (1.1 mm thick) of Gorilla Glass® 3 from Coming Incorporated. An optical assembly similar to the optical assembly 100 depicted in FIG. 2E was used to form the closed contours, where the second lens 132 had a focal length of 40 mm. The beam source 110 was controlled generate pulses in pulse bursts (10 pulses/burst) at a repetition rate of 100 kHz. Each pulse had an energy of 400 pj/burst. The transparent sheet and laser beam were translated relative to one another at a translation speed of 12 m/min. The laser was focused to generate a focal line length (FWHM) of 1.9 mm, with a Bessel core radius (distance to the nulls of the Bessel function) of 1 .53 pm. Such a setup provided defects with a 5 pm pitch along a contour line.

[00135] After laser processing, the 1.1 mm thick transparent sheet was immersed in a 100% KNO3 salt bath for 6.25 hours at a temperature of 420°C. Transparent workpieces were then released from the frame portion of the transparent sheet by forming release lines with laser processing. This process resulted in transparent workpieces having a straight edge (with comer angles being approximately 90°). About half the samples were then subjected to bmsh polishing where they were stacked as shown in FIG. 2 J (100 pm thick sheets of cleanroom paper were used for the interposers), with a bmsh employing 36 mm long filaments being employed to remove approximately 20 pm of material from the edges of the transparent workpieces to form transparent articles. The brush polish process was employed to impart very little change in shape of the edges of the workpieces. An example workpiece is shown in FIG. 3. Notably, the polished edges do not exhibit a C-chamfer, but rather a very small rounding of the corners. It has been found that this slight chamfering beneficially provides robustness against edge impacts.

[00136] Each set of samples (those subjected to brush polishing and those not subjected to brush polishing) for both thickness was subjected to edge strength testing using a four-point bend test in accordance with ASTM C158-02. The results are shown in FIG. 4A. FIG. 4A is a Weibull distribution of a percentage value as a function of bending stress for the samples. FIG. 4B is a Weibull distribution of a similar set of samples with a 1.3 mm thickness (these samples were processed to have a 44 mm x 60 mm, with this size difference not expected to significantly impact the results). The 1.3 mm thick samples were ion exchanged by being immersed in a 100% KNO3 salt bath for 4 hours at a temperature of 400°C. As shown, for both thicknesses, the brush polishing significantly improved edge strength, with both polished sets exhibiting a B10 value greater than 750 MPa.

[00137] Various 90x150 mm samples were subjected to headform impact testing (HIT) under Federal Motor Vehicle Safety Standards (FMVSS) 201. The HIT under FMVSS 201 is used to simulate passenger head impact on dashboard and adjacent areas in the event of crash. FIG. 5 depicts a setup 500 for conducting such testing in accordance with the present disclosure. As shown, a pendulum 502 is used to direct a headform 504 onto a major surface of sample 506. The headform 504 can be a semi-sphere that is typically 165 mm in diameter and has a mass of about 6.8 kg. The headform 504 can be configured to impact the sample 506 at different angles and typically at a speed of 6.67 meters per second. Unless otherwise noted herein, the impact angle is 90°. The total impact energy can be around 152 Joules. As shown, the sample 506 is integrated into a testing assembly 508 for analysis. The sample 506 may be adhered (e.g., using a suitable pressure sensitive adhesive) to a support plate 510 having mounting brackets 512 secured thereto by fasteners. In the testing conducted herein, the support plate 510 was either a 3.2 mm thick Aluminum plate or a 3 mm Delrin® plate (for a combined stiffness with the sample 506 of approximately 206 N/mm). The support plate 510 was 150 mm x 190 mm, with the sample 506 being centered on the support plate 510 (for centered impacts) or centered along a longer edge (for edge impact tests). The mounting brackets 512 were commercially available C-clamps (4.8 mm thick) and used to secure the assembly to a base (not shown). The mounting brackets 512 had a stiffness of 4152 N/mm. The pendulum 502 was configured to either impact the sample 506 in a central impact location 514 or an edge impact location 516 at the edge of a major surface of the sample 506.

[00138] Eight of the 1. 1 mm thick samples were subjected to the HIT at the central impact location 514, while 10 were subjected to the HIT at the edge impact location 516. None of the samples fractured when impacted at the central impact location 514, while only 1 of the 8 samples fractured when impacted at the edge impact location 516. This represents a significant improvements over comparative examples (formed using the same material, ion exchange, and brush polishing conditions) that were first ion exchanged at the sheet level (without laser processing-induced defects therein), then laser cut to the 90 x 150mm size, and finally brush polished. Of 8 such counterexamples tested at the central impact location 514, 2 fractured. Of 8 such counterexamples tested at the edge impact location 516, 5 failed. These results demonstrate that the process described herein provides samples of superior edge strength and improved reliability.

Evaluation of Ion Exchange Performance

[00139] To quantify the efficacy of conducting ion exchange via laser processing -induced defects in a transparent sheet, four samples were prepared for examination with electron probe microanalysis (“EPMA”). Each sample was formed from a 1. 1 mm thick sheet of GG3. Each sample was ion exchanged for a period 6.25 hours in a 100% KNO3 salt bath at 420°C. A first sample (“Sample A”) was cut from an ion exchanged transparent sheet (without laser processing-induced defects therein) . A second sample (“Sample B”) was cut from a transparent sheet and individually ion exchanged. A third sample (“Sample C”) was fabricated using the process 200 described herein with respect to FIG. 2A, without being subjected to brush polishing. A fourth sample (“Sample D”) was fabricated using the process 200 described herein with respect to FIG. 2A, including the brush polishing. All samples A-D were ion exchanged in the same salt bath at the same time.

[00140] To prepare for EPMA, each sample was diced into a 1 mm wide section (extending 1 mm inward from an edge of interest). FIG. 6 depicts a section 600 after being prepared for EMPA. As shown, the section 600 includes a first major surface 602, a second major surface 604, and an edge of interest 606. The edge of interest 606 corresponds an edge formed by cutting from the transparent sheet (e.g., one of the polished edges 58 in the transparent article 52 described herein). As a result of the ion exchange treatment, layers of elevated potassium concentration are present and extend inward from the first and second major surfaces to first and second depth of layers DOLi and DOL2. Scanning electronic micrographs are taken at measurement locations to determine the potassium concentration of the function of depth. The micrographs image 200 pm of depth (in a direction perpendicular to the surface at which the micrograph begins). A reference measurement location 608 is taken on the first major surface 602. A plurality of edge measurement locations 610 are distributed throughout the edge of interest 606. The plurality of edge measurement locations 610 can be uniformly distributed over the entirety of the edge of interest 606, with the locations being selected so that the two outermost locations are within DOLi from the first major surface 602 and DOL2 from the second major surface 604, respectively.

[00141] SEM images of Samples A, B, C, and D are depicted in the corresponding FIGS. 7A, 7B, 7D, and 7C. The bright regions in the glass indicate the presence of K, which entered the glass from the ion-exchange process. All glass pieces have K present on the top/bottom surfaces. Sample A has no K on the left edge, since it was cut after ion exchange. Sample B has K on all edges, since it was cut before IOX and hence all edges were exposed to the salt bath. Sample C shows K on all edges, the thickness and intensity of the bright K ion band along the part (left) edge is nearly constant. Sample D shows a similar pattern to Sample C, expect the width of the bright K ion band along the left edge is clearly reduced. This is attributable to the brush polish, which would have removed approximately 20um of the edge after the IOX process was complete. Further, as shown in FIG. 7D, the sample had rounded comers. Thus, a result of the brush polishing for Sample D, ends of the polished edge are rounded but still under a compressive stress from the exchanged ion (K in this example). It should be noted that the sample preparation process can introduce some artifacts to the edges, mostly in causing the comers of the parts to spall off during cut and polish, and in the presence of small cracked regions near some of the comers. The locations where this spalling has occurred is noted in the images.

[00142] FIGS. 8A-8D are plots of K2O concentration vs depth (measured in a direction perpendicular to the edge of interest 606 shown in FIG. 6) at a plurality of edge measurement locations 610. To generate the plots in FIGS. 8A-8D, K2O concentration values were generated for every 1 pm in depth from the edge of interest. Such values were averaged using a 5 pm depth bin size to reduce noise. The K2O concentration is representative of the amount of K ions that entered the glass during the ion exchange process, replacing the Na ions in the glass matrix, creating a compressive layer. Reference measurement locations 608 are also plotted in FIGS. 8A-8D. The vertical distances (perpendicular to the direction in which the K2O concentration is measured) between the particular edge measurement locations 610 and the first and second major surfaces 602, 604 are indicated in each plot. FIG. 8 A is a plot for each measurement location for Sample A. FIG. 8B is a plot for each measurement location for Sample B. FIG. 8C is a plot for each measurement location for Sample C. FIG. 8D is a plot for each measurement location for Sample D. Each of FIGS. 8A-8D show the reference measurement location 608 scans for all four samples A-D, to illustrate the consistency of the ion exchange across those four samples.

[00143] As shown in FIG. 8 A, for sample A, only the first major surface 602 shows any appreciable K concentration, as all the other scans were made along the cut edge of the glass piece which was cut after IOX and hence not exposed to the salt bath. The measurement at the reference measurement location 608 indicates that DOLi is just above 40 pm for each of Samples A, B, C, and D. As shown in FIG. 8B, for sample B, all edge locations exhibit a similar K2O concentration, which is expected given that the complete edge was exposed to the ion exchange treatment. As shown in FIG. 8C, all the edge scans show a nearly equivalent K2O concentration, which is slightly less (~ 10%) than the reference scans at the top surface of the parts. The depth-of-layer for each of the edge scan is also consistent, at just over 40um. Thus, referring briefly to FIG. 2A between the blocks 210 and 212, or after the separating and prior to any processing of an edge of the transparent workpiece, the edge of the transparent workpiece exhibits a minimum exchanged ion concentration that is greater than 80% of a maximum ion exchange concentration of the transparent article. Indeed, as shown in FIG. 8C, at the first and second major surfaces 602 and 604 (see FIG. 6) the maximum K2O concentrations are from 10% to 11 mol%, whereas a minimum value for the K2O concentration at the edge of interest 606 is about 9 mol%. Moreover, over a central segment of the edge of interest 606, inward extending from 120 pm from the first major surface 602 to 920 pm from the first major surface 602), the concentration of the exchanged ion varies from a maximum value of approximately 9.8 mol% to a minimum value of approximately 9 mol%. That is, over a central segment of the edge of interest 606 not overlapping the layers of elevated exchanged ion concentration at the first and second major surfaces 602, 604, the concentration of the exchanged ion varies by less than 10%. It is also worth noting that there is no observable trendline in exchanged ion concentration over this central segment. FIG. 8E plots the exchanged ion concentration as a function of depth along the edge of interest 606 for the Sample C, over the central segment of the cut edge of the transparent workpiece (from 120 pm to 920 pm from the first major surface 602 along the edge of interest 606). As shown, the concentration of the exchanged ion is very consistent, with no trend exhibiting diminished concentration in the center of the workpiece . Further, the edge depth of layer of the transparent workpiece represented in FIG. 8C is very consistent over the entirety of the edge of interest 606 (approximately 42 pm throughout the edge). This indicates that the ion exchange process is consistent throughout the thickness of the workpieces. The fact that such uniformity was exhibited for workpieces having thicknesses of greater than or equal to 1 mm further emphasizes the efficacy of the laser defects described herein as serving effective conduits for ion exchange.

[00144] As shown in FIG. 8D, for Sample D, the K2O concentration is reduced along the edge of interest 606 in areas inward of DOLi and DOL2. This is believed to be due to the material removal caused by the brush polishing. Indeed, the edge measurement locations 610 that are between 220 pm and 820 pm from the first major surface 602 (that is, with the bottom measurement location being approximately 280 pm from the second major surface 604) exhibit peak K2O concentrations at the edge of interest 606 that range from approximately 6 mol% to approximately 6.9 mol%. Thus, for this particular example, the central segment of the polished edge exhibits a concentration of the exchanged ion that varies approximately 15 %. Further, as shown in FIG. 8D, this particular example exhibited an edge depth of layer of approximately 28 pm, while the reference scans indicate that DOLi and DOL2 is approximately 44 pm. This difference is attributable to approximately 16 pm of material removal from the edge of the transparent workpiece to form the sample depicted in FIG. 7D. Despite brush polishing removing such material to form the edge of interest 606, a minimum value of the exchanged ion is still well above 50% of the maximum value of the exchanged ion at the first and second major surfaces 602, 604. These results demonstrate the efficacy of the defects produced via the laser processing described herein as serving as conduits for ion exchange strengthening along contours.

[00145] Without wishing to be bound by theory, it is believed that the laser processing- induced defects provide such effective ion exchange strengthening along the edges of the resulting article due at least in part to the assembly used to form a quasi-non-diffracting laser beam including the laser beam focal line 113 (see FIG. 2A). Particularly, it is believed that machining a sharp aspheric optical element 120 to minimize an axicon-tip interference induced intensity oscillations in the focal line, as well as using a focusing lens designed to minimize any astigmatism and coma aberrations, is effective at providing uniform laser power along the laser beam focal line 113. Use of asymmetric quasi-non-diffracting laser beams is also leveraged to directionally guide microcracks, helping ensure that the individual defects are well connected to adjacent defects by microcracks, which allows for easy salt penetration during the ion exchange process. Such consistent laser exposure along the thickness of the transparent sheet 160 is believed to result in defects with spatially uniform qualities, as well as interconnection of the defects with microcracks through the full thickness of the substrate, to provide consistent ion exchange through the full depth of the glass or glass ceramic sheet.

[00146] In short, it is believed that the process described herein results in articles having unique combination of edge shape and ion exchange properties to provide very favorable edge strength, despite only a small amount of material being removed from the workpieces with the polishing. The uniform edge depth of layer facilitates removing defects resulting from the singulation process, while still leaving the entire polished edge under compressive stress. That comers of the article are rounded but still under compressive stress also contributes to the favorable headform impact testing performance described herein. The present disclosure therefore provides a favorable combination of performance attributes while also eliminating the complexities of individual part handling during ion exchange and other surface treatments, leading to decreased costs and production efficiencies.

[00147] As used herein, the term “about” means that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate and/or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art. When the term “about” is used in describing a value or an end-point of a range, the specific value or end-point referred to is included. Whether or not a numerical value or end-point of a range in the specification recites “about,” two embodiments are described: one modified by “about,” and one not modified by “about.” It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. [00148] Directional terms as used herein - for example up, down, right, left, front, back, top, bottom - are made only with reference to the figures as drawn and are not intended to imply absolute orientation.

[00149] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order, nor that with any apparatus specific orientations be required. Accordingly, where a method claim does not actually recite an order to be followed by its steps, or that any apparatus claim does not actually recite an order or orientation to individual components, or it is not otherwise specifically stated in the claims or description that the steps are to be limited to a specific order, or that a specific order or orientation to components of an apparatus is not recited, it is in no way intended that an order or orientation be inferred, in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps, operational flow, order of components, or orientation of components; plain meaning derived from grammatical organization or punctuation, and; the number or type of embodiments described in the specification.

[00150] As used herein, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a” component includes aspects having two or more such components, unless the context clearly indicates otherwise.

[00151] It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Thus it is intended that the specification cover the modifications and variations of the various embodiments described herein provided such modification and variations come within the scope of the appended claims and their equivalents.

Claims

CLAIMS What is claimed is:

1. A glass article comprising: a first major surface; a second major surface disposed opposite from the first major surface; and a polished edge extending between the first major surface and the second major surface, wherein: the glass article is chemically strengthened via ion exchange such that the glass article comprises a first layer, a second layer, and an edge layer in which a concentration of an exchanged ion is heightened as compared to a bulk of the glass article, the first layer extends from the first major surface to a first depth of layer (DOLi) within the glass article, the second layer extends from the second major surface to a second depth of layer (DOL2) within the glass article, the edge layer extends inward from the polished edge and to an edge depth of layer (DOLE) that is at least 5 pm, and

DOLE is at least 5 pm less than DOLi and DOL2.

2. The glass article of claim 1, wherein: the concentration of the exchanged ion is elevated above that of the bulk throughout an entirety of the polished edge, and the polished edge comprises an Ra surface roughness that is less than or equal to 100 nm.

3. The glass article of any of claims 1-2, wherein DOLE is greater than 20 pm and at least 50% of DOLi and DOL2.

4. The glass article of any of claims 1-3, wherein: a maximum value of the concentration of the exchanged ion occurs in the first layer and/or or the second layer, and a minimum value of the concentration of the exchanged ion along the polished edge is at least 50% of the maximum value.

5. The glass article of any of claims 1-4, wherein over a central segment of the polished edge disposed at least 100 pm from either the first major surface and the second major surface, the concentration of the exchanged ion varies by no more than 20% of a minimum value of the concentration along the polished edge.

6. The glass article of any of claims 1-5, wherein the polished edge comprises a plurality of brush marks arranged thereon in a substantially parallel configuration, the brush marks imparted by a brush polishing process.

7. The glass article of claim 6, wherein, as a result of the brush polishing process, ends of the polished edge are rounded but still under a compressive stress from the exchanged ion.

8. The glass article of any of claims 1-7, wherein the first layer and the second layer exhibit maximum compressive stresses that are greater than or equal to 800 MPa.

9. The glass article of any of claims 1-8, wherein, an Ra surface roughness of the polished edge is less than or equal to 20 pm.

10. The glass article of any of claims 1-9, wherein, when the glass article is subjected to headform impact testing according to FMVSS 201 with an impactor contacting an edge region of the first major surface and the second major surface, the glass article does not fracture.

11. The glass article of any of claims 1-10, wherein a plurality of the glass articles with the same composition, thickness, and chemical strengthening exhibit a Weibull distribution with a B10 value that is greater than or equal to 700 MPa, when tested for mechanical edge strength using a four-point bend test in accordance with ASTM C158-02.

12. A glass article comprising: a first major surface; a second major surface disposed opposite from the first major surface; and a polished edge, wherein: the glass article is chemically strengthened via ion exchange such that the glass article comprises a first layer, a second layer, and an edge layer in which a concentration of an exchanged ion is heightened as compared to a bulk of the glass article, a maximum value of the concentration of the exchanged ion occurs within the first layer and/or the second layer, a minimum value of the concentration of the exchanged ion along the polished edge is at least 50% of the maximum value, and over a central segment of the polished edge disposed at least 100 pm from either the first major surface and the second major surface, the concentration of the exchanged ion varies by no more than 20% of the minimum value.

13. The glass article of claim 12, wherein: the first layer extends from the first major surface to a first depth of layer (DOLi) within the glass article, the second layer extends from the second major surface to a second depth of layer (DOL2) within the glass article, the edge layer extends inward from the polished edge and to an edge depth of layer (DOLE) that is at least 5 pm, and

DOLE is at least 5 pm less than DOLi and DOL2.

14. The glass article of any of claims 12-13, wherein DOLE is greater than 20 pm and at least 50% of DOLi and DOL2.

15. The glass article of any of claims 12-14, wherein the polished edge comprises a plurality of brush marks arranged thereon in a substantially parallel configuration, the brush marks imparted by a brush polishing process.

16. The glass article of claim 15, wherein, as a result of the brush polishing process, ends of the polished edge are rounded but still under a compressive stress from the exchanged ion.

17. The glass article of any of claims 12-16, wherein the first layer and the second layer exhibit maximum compressive stresses that are greater than or equal to 500 MPa.

18. The glass article of any of claims 12-17, wherein, the Ra surface roughness is less than or equal to 20 nm.

19. The glass article of any of claims 12-18, wherein, when the glass article is subjected to the headform impact test in accordance with ECE R21 with the impactor contacting an edge region of the first major surface and the second major surface, the glass article does not fracture.

20. The glass article of any of claims 12-19, wherein a plurality of the glass articles with the same composition, thickness, and chemical strengthening exhibit a Weibull distribution with a BIO value that is greater than or equal to 700 MPa, when tested for mechanical edge strength using a four-point bend test in accordance with ASTM C158-02.

21. The glass article of any of claims 12-20, wherein the polished edge comprises an Ra surface roughness that is less than or equal to 10 nm.

22. A method of forming a transparent article from a transparent sheet, the method comprising: forming one or more closed contours in the transparent sheet separated from the edge of the transparent sheet, each closed contour comprising a plurality of defects in the transparent sheet such that each closed contour defines a perimeter of the transparent article, wherein forming each of the one or more closed contours comprises: directing a pulsed laser beam oriented along a beam pathway and output by a beam source into the transparent sheet such that a portion of the pulsed laser beam directed into the transparent sheet generates an induced absorption within the transparent sheet, the induced absorption producing defects within the transparent sheet along the one or more closed contours; and translating the transparent sheet and the pulsed laser beam relative to each other along one or more closed contour lines, thereby laser forming defects along the one or more closed contour lines within the transparent sheet; subjecting the transparent sheet to an ion exchange treatment where the defects act as conduits for ion exchange such that the transparent sheet is strengthened along the one or more closed contours throughout a thickness of the transparent sheet; separating a transparent workpiece from the transparent sheet at the one or more closed contours after the ion exchange treatment, wherein after the separating and prior to any processing of an edge of the transparent article, the edge of the transparent workpiece exhibits a minimum exchanged ion concentration that is greater than 80% of a maximum ion exchange concentration of the transparent workpiece.

23. The method of claim 22, further comprising applying one or more surface treatments to at least one of the major surfaces of the transparent sheet after the ion exchange treatment and prior to the separating, the one or more surface treatments comprising at least one of depositing a decoration layer, application of an anti-glare surface treatment, depositing an antireflective coating, and depositing an anti-fingerprint coating.

24. The method of any of claims 22-23, further comprising forming one or more release lines in the transparent sheet to singulate the transparent workpiece.

25. The method of any of claims 22-24, wherein the portion of the pulsed laser beam directed into the transparent sheet comprises: a wavelength ; a spot size w₀; and a cross section that comprises a Rayleigh range Z_R that is greater than F_D — A -.²¹, where

F_D is a dimensionless divergence factor comprising a value of 10 or greater.

26. The method of claim 25, wherein the pulsed laser beam comprises a beam core radius that is from 1 pm to 2.5 pm and ZR is from 1 mm to 2 mm.

27. The method of any of claims 22-26, wherein a spacing between adjacent defects is 50 pm or less.

28. The method of any of claims 22-27, wherein the beam source comprises a pulsed beam source that produces pulse bursts with from 1 sub-pulse per pulse burst to 30 sub-pulses per pulse burst and a pulse burst energy is from 100 pj to 1500 pj per pulse burst.

29. The method of any of claims 22-28, further comprising subjecting the edge to polishing to remove at least 5 pm of material of the transparent workpiece from the edge and form the transparent article with a polished edge.

30. The method of claim 29, wherein, after the separating and polishing, the transparent article comprises a first layer, a second layer, and an edge layer in which a concentration of an exchanged ion is heightened as compared to a bulk of the glass article, the first layer extends from a first major surface of the transparent article to a first depth of layer (DOLi) within the transparent article, the second layer extends from a second major surface of the transparent article to a second depth of layer (DOL2) within the transparent article, the edge layer extends inward from the polished edge and to an edge depth of layer (DOLE) that is at least 5 pm, and

DOLE is at least 5 pm less than DOLi and DOL2.

31. The method of claim 30, wherein the polishing is brush polishing.

32. The method of any of claims 22-31, wherein the ion exchange treatment comprises immersing the transparent sheet in a molten salt bath at a temperature of at least 390°C for a time period of at least 1 hour.