WO2009029513A1 - Method for production of covert markers - Google Patents

Abstract

A method for producing covert markers is disclosed. The method includes providing a substrate, providing a radiation source, providing a mask intermediate the substrate and the radiation source and transmitting radiation from the radiation source through the mask onto the substrate to ablate a portion of the substrate thereby creating the covert marker. The covert markers can be applied to genuine articles for later authentication.

Description

METHOD FOR PRODUCTION OF COVERT MARKERS

RELATED APPLICATIONS

[0001] This application claims priority to U.S. Prov. App. No. 60/957,824 filed August 24, 2007 and entitled "Method for Production of Covert Markers" which is hereby incorporated by reference in its entirety.

FIELD

[0002] The present invention is generally directed to methods of producing markers and more specifically to methods of producing markers which cannot readily be seen by the naked eye, such as those which are sometimes used for the identification and authentication of genuine articles to deter counterfeiting.

BACKGROUND

[0003] Identity theft and black market sales of counterfeit goods are significant problems faced with increasing regularity in today's world. Each year many millions of dollars are lost through the fraudulent use and sale of non-authentic documents and branded goods. The increasing sophistication of optical scanners, copy machines and other devices used for replicating items and identification labels continues to enhance the counterfeiter's ability to produce fraudulent documents and other imitation goods which often go undetected.

[0004] Various measures have been introduced to combat these techniques and ensure consumers are receiving genuine articles. One manner of deterring counterfeiting involves applying some form of covert marker, also referred to as a taggant or microtag, to the article that cannot be viewed by the unassisted eye.

[0005] Currently, such covert markers are produced from extruded fibers, such as the creating and sectioning of "islands-in-the-sea" filaments, made in accordance with the methods disclosed in U.S. Patent No. 4,640,035 to Kind et al., for example. Photolithography or other printing, casting or extrusion methods are also used. [0006] Known methods of covert marker production require multiple processing and handling steps that are often time consuming and as a result, can be very expensive. Filament production of covert markers may also be susceptible to some variations in quality, either of the marker itself and/or any indicia incorporated therein. Current production processes are further limited by the types of materials that can readily be used for the marker, which may, in turn, limit the scope or types of articles to or on which the markers may be applied. Furthermore, with current extrusion processes, the size of the covert markers that can be created is limited by the size of the holes that can be formed in the die and the flow characteristics of the material being extruded.

[0007] These and other drawbacks are found in conventional covert marker production processes. Exemplary embodiments of the invention may overcome some or all of these drawbacks.

SUMMARY

[0008] According to an exemplary embodiment of the invention, a method for producing a covert marker is disclosed. The method includes providing a substrate, providing a radiation source, providing a mask intermediate the substrate and the radiation source and transmitting radiation from the radiation source through the mask onto the substrate to ablate a portion of the substrate thereby creating the covert marker.

[0009] According to another embodiment of the invention, a method for deterring counterfeit production of articles is disclosed. The method includes providing a substrate, providing a laser as a radiation source, providing a mask intermediate the substrate and the laser, projecting radiation from the laser through the mask onto the substrate by projection laser lithography to create a covert marker having a maximum dimension less than about 120 microns, and applying a plurality of covert markers to a genuine article to be authenticated. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG. 1 schematically illustrates a system for creating covert markers in accordance with an exemplary embodiment of the invention.

[0011] FIG. 2 illustrates a substrate containing a plurality of covert markers formed in accordance with an exemplary embodiment of the invention.

[0012] FIG. 3 illustrates a covert marker formed in accordance with an exemplary embodiment of the invention.

[0013] FIG. 4 illustrates a covert marker formed in accordance with another exemplary embodiment of the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0014] According to an exemplary embodiment of the invention, a method for making covert markers is provided that uses laser ablation by projection laser lithography and other techniques in which one or more masks are used to create the covert markers from a substrate. Exemplary embodiments thus use laser ablation as a method to create covert markers, such as microtags, useful in anti-counterfeit technology, brand management or any other application where it is desirable to employ covert markers for later identification or authentication. Exemplary embodiments of the invention provide a way to create a precision product from flat stock at high speed and further provide for an expanded range of materials for use in covert marker production beyond more traditional thermoplastic materials. Thus, prior challenges of combining manufacturing speed with precision can be solved using the methods of the instant disclosure.

[0015] As used herein, the term "microtag" refers to microparticles less than about 120 microns in size in each dimension and which are not readily discernible by the naked eye, but which can easily be seen or detected with the use of an identifying aid such as a microscope, and generally contain at least one attribute for later identification, as well as that of the article to which it is applied. Because markers used for identification and/or authentication are often covert, microtags are generally a preferred form of marker. However, it will be appreciated that exemplary embodiments of the invention can be used to make microparticles of any size.

[0016] FIG. 1 illustrates schematically a covert marker production system 10 in accordance with an exemplary embodiment of the invention. A radiation source 12 is provided. A substrate 20 of sheet stock from which the covert markers are to be created is also provided. The substrate 20 can be a single layer of material or can be multi-layered, such as a metallized polymer, for example. As shown in FIG. 1, the substrate is a two-layer substrate 20 having a first layer 22 and a second layer 24 underlying the first layer 22. The second layer 24 is different from the first layer 22 in some manner, most often in composition, although the difference may be one of color or other physical property.

[0017] A mask 14 corresponding to a negative version of a pattern to be produced is placed intermediate the laser 12 and the substrate 20. Radiation 16, such as collimated light in the case of a laser, is emitted by the radiation source 12 toward the mask 14. Because the mask 14 is a negative of the pattern to be produced, the radiation 16 that passes through the mask 14 is projected onto the substrate 20 only at locations that are to be ablated. One or more layers of the substrate 20 is ablated at certain locations based upon the radiation 16 passing through certain transmissive regions of the mask 14. While illustrated in FIG. 1 with respect to projection laser lithography, scanning laser lithography techniques may also be used.

[0018] The radiation source 12 used with the mask 14 may be any suitable source of producing radiation to be projected by the mask 14 onto the substrate 20. In one embodiment, the radiation source 12 may be a collimated radiation source. According to another embodiment, the radiation source 12 is an exiplex laser, sometimes referred to as an excimer laser. It will be appreciated that if the radiation source 12 is a laser, the laser may include a homogenizer and/or other devices used in conjunction with laser operation. It will further be appreciated that covert markers can be created according to exemplary embodiments using other radiation sources, such as infrared laser, carbon dioxide lasers or other gas or solid lasers. [0019] The first layer 22 of the substrate 20 can be a polymer, metal film or other material from which covert markers are to be produced, and which is responsive to the source of energy used for the ablation. Stock materials from which covert markers may be produced in accordance with exemplary embodiments include, but are not limited to, ceramic, metal, ferromagnetic, inorganic crystal or non-organic material, thermoset polymer, thermoplastic polymer, natural products (e.g., cotton, linen, gelatin) and various combinations of the same. The second layer 24, and any other additional layers, of the substrate 20 can also be selected from these same materials.

[0020] The use of a multi-layered substrate 20 permits exemplary embodiments of the invention to incorporate complex indicia as a single or multi-staged photonic multi-plexed event through the use of multiple masks and/or multiple laser passes. Thus, in one embodiment, a multi-layer substrate 20 can be used in combination with ablation techniques such that multiple layers 22, 24 of the substrate 20 contribute to an overall intended outcome. For example, the depth of radiation penetration can be controlled to ablate one or more upper layers 22 without impacting an underlying layer 24.

[0021] The mask 14 may include a glass master or similar structure that serves as a stencil for the covert marker 30 to be created and/or for any indicia 32 (FIG. 2) provided therein. The mask 14 can be formed of quartz, glass or any other transmittant material in which a master negative or positive can be incorporated for the projection of radiation in a pattern to form the indicia 32 and/or the shape of the covert marker 30. In one embodiment, radiation in the form of laser energy is projected through the transmissive sections of the mask 14 to the substrate 20, ablating to a predetermined depth the areas of the substrate 20 on which the radiation 16 is projected or otherwise directed. As previously mentioned, the predetermined depth may be less than or equal to the thickness of the substrate 20.

[0022] Multiple masks 14 may be used to perform the ablations in a stepped fashion. For example, a first mask 14 containing text, an image or other pattern may be provided to create indicia 32 within the covert marker 30 for later authentication of a genuine article when applied thereto. A second mask 14 can be provided to establish the perimeter of the covert marker 30 in a way that acts as a cookie-cutter during ablation forming the desired shape and physically separating the covert marker from the substrate 20, so that the covert markers can subsequently be collected and separated from any remaining scraps of the substrate.

[0023] Conversely, separation with the "second" (i.e., perimeter) mask can occur first, followed by imparting any indicia through ablation with the "first" (i.e., indicia) mask. It will further be appreciated that depending on the complexity of the design and/or perimeter for the microtag to be formed, a single mask may be used to accomplish both the indicia and the separation in a single step. Likewise, it will also be appreciated that a single mask could be used for the production of multiple covert markers in a single ablation step.

[0024] Thus, in one embodiment, a first mask 14 to project radiation in a predetermined pattern to form indicia 32 could be used when the laser is operated at a lower power, penetrating to a first depth less than the thickness of the entire substrate 20 to remove only the top layer 22 and thereby reveal the underlying second layer 24. A second mask 14 could then be used to project radiation in a pattern that forms the perimeter of the covert marker. When the radiation source 12 is operated at a higher power level with the second mask, the radiation 16 penetrates the entire substrate 20 so as to make the newly formed covert marker 30 removable from the sheet stock. In one embodiment, the initial radiation projection could remove the first layer 22 of a first color to create indicia that reveals the underlying layer 24 having a different color or some other attribute, so that covert marker has a multi-planar surface. Alternatively, the void left by the ablated first layer 22 could be back-filled with a different material by electroplating or other suitable technique.

[0025] FIG. 2 illustrates a top view of a substrate 20 in which four covert markers 30 have been created using laser ablation such that indicia 32 has been incorporated into each of the covert markers 30 and in which the covert markers 30 have been physically separated, but not yet been removed from, the remnants of the substrate 20. It will be appreciated that FIG. 2 is exemplary only and the sheet stock used as the substrate is ordinarily enough to make many hundreds or even thousands of microtags from a single sheet.

[0026] After all desired ablation has been completed, the covert markers 30 are removed from the remnants of sheet stock. For example, the covert markers 30 may be harvested by vacuuming, leaving behind the scraps of substrate 20.

[0027] The covert markers 30 may have any geometry. In one embodiment, the covert markers have a maximum dimension, which is generally a distance across a major surface 34, of about 1 to about 120 microns, preferably about 5 to about 30 microns. It will be appreciated that the maximum dimension may be larger or smaller, but that as the size of the covert marker increases, it may be more readily distinguished by the human eye once it exceeds a maximum dimension of about 100 to about 120 microns. In one embodiment, the covert markers 30 are disc-like and the distance across a major surface corresponds to the diameter of the covert marker 30. In some embodiments, the marker's geometry itself may be an attribute for later identification.

[0028] The thickness of the covert markers 30 can range from about 1 micron to about 40 microns, preferably about 15 microns to about 30 microns. The substrate 20 can be of any thickness and may be the same or thicker than the microtags to be created. That is, in one embodiment, the covert marker 30 (FIG. 3) contains fewer layers than the substrate used to create the marker.

[0029] For example, with reference to FIG. 2, a multi-layer piece of flat stock can be provided as a substrate 20 having a metal layer 22 applied over a polymeric base layer 24 that is dissolvable in a solution that will not also dissolve the metallized layer 22. After ablation, the metal layer 22 can be removed from the base layer 24 by placing the semi-finished product in water or other liquid in which the base layer 24 is dissolvable, leaving only the metal markers 30 and first layer remnants behind as a finished product. The covert markers 30 can be separated from the remnants and collected by filtration. This may be advantageous where the base layer is needed during production for the support of a particularly thin or fragile film material from which the covert marker is to be produced.

[0030] In another embodiment, the substrate is provided as an embossed base sheet as a template over which additional layers are applied by subsequent deposition and can be used to produce an embossed marker (FIG. 4). These additional layers when ablated into the microtags may have a positive or negative footprint of indicia depending on the desired end product.

[0031] In yet another embodiment, a substrate 20 is provided so that layers impart an independent functionality for the application and/or operation of the covert marker in situ. For example, a multi-layer substrate may include a layer of ferromagnetic material to impart a magnetic property to the covert marker.

[0032] The use of a projection laser to create microtags and other covert markers decreases process time and permits rapid tag production in a high volume format. Little or no post processing, such as cleaning and size exclusion, may be needed. Thus, the transition time from stock substrate to the final microtag product can be nearly instantaneous. Furthermore, the materials of construction for the microtags are limited only to exclude those which do not respond to the selected radiation source and its operational profile. An additional advantage is that exemplary embodiments provide the ability to create a nearly infinite number of covert markers with precision.

[0033] Once formed, the covert markers can be applied to articles for later authentication using any suitable manner. Application techniques may include providing a dispersion of covert markers in a carrier and applying by spraying or coating the dispersion to an original document, product packaging, or other genuine article.

[0034] Exemplary embodiments allow for the production of covert markers from materials beyond those traditionally used. For instance, a gold microtag can be created that would be useful as an excipient graded material for inclusion with pharmaceuticals and biopharmaceuticals. A multi-layer substrate may be built up in a manner similar to high density interconnect structures found in the printed wire and integrated circuit technology to create a microtag that can be imparted with electronic and/or conductive properties. Buried chemistries within the layers of a multi-layer covert marker may be provided to give the tag a specific function, which may include diagnostic functions, for example, based on selection of outer layers that are environmentally resistant and inner layers that are environmentally responsive or vice versa.

[0035] Other features that can be achieved according to exemplary embodiments of the invention include the production of covert markers which are part of an RFID active system. A microtag system that is atomic weight contrast readable by SEM/EDS or other suitable spectroscopic and microscopic method can be produced. A conductive microtag system can be produced so that the tag can be part of conductive samples without disturbing current flow. Incorporation of base sheet plasma treatment allows for the creation of unique multi-layer microtags. Thus, it will be appreciated that while useful for authentication of genuine articles to deter counterfeiters, exemplary embodiments of the invention are not so limited.

[0036] While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. A method for producing a covert marker comprising: providing a substrate; providing a radiation source; providing a mask intermediate the substrate and the radiation source; and transmitting radiation from the radiation source through the mask onto the substrate to ablate a portion of the substrate thereby creating the covert marker.

2. The method of claim 1, wherein the substrate comprises multiple layers.

3. The method of claim 2, further comprising dissolving at least one layer of the substrate in a solvent following the step of transmitting radiation, wherein at least one other layer of the substrate is insoluble in the solvent.

4. The method of claim 2, wherein at least one layer of the substrate is metallic.

5. The method of claim 1, further comprising transmitting radiation from the radiation source through the mask onto the substrate to create indicia within the covert marker.

6. The method of claim 1, wherein the covert marker has a maximum dimension in the range of about 1 to about 120 microns.

7. The method of claim 1, wherein the covert marker has a maximum dimension in the range of about 5 to about 30 microns.

8. The method of claim 1, wherein the covert marker has a multi-planar major surface.

9. The method of claim 1, wherein the covert marker comprises an RFID active material, a magnetic material, a conductive material, or an excipient graded material.

10. The method of claim 1, wherein the radiation source is a laser and the step of transmitting radiation includes projecting radiation through the mask onto the substrate by projection laser lithography.

11. The method of claim 1 , wherein the radiation source is a laser and the step of transmitting radiation includes directing radiation through the mask onto the substrate by scanning laser lithography.

12. The method of claim 1, wherein the substrate comprises a material selected from the group consisting of ceramic, metal, ferromagnetic, inorganic crystal, thermoset polymer, thermoplastic polymer, cotton, linen, gelatin and combinations thereof.

13. The method of claim 1, wherein the substrate comprises a material that is atomic weight contrast readable by SEM/EDS.

14. The method of claim 1, wherein the covert marker has a thickness in the range of about 1 micron to about 40 microns.

15. The method of claim 1, wherein the covert marker has a major surface having a circular geometry.

16. A method for deterring counterfeit production of articles comprising providing a substrate; providing a laser as a radiation source; providing a mask intermediate the substrate and the laser; projecting radiation from the laser through the mask onto the substrate by projection laser lithography to create a covert marker having a maximum dimension less than about 120 microns; and applying a plurality of covert markers to a genuine article to be authenticated.

17. The method of claim 16, wherein the substrate comprises multiple layers.

18. The method of claim 17, wherein at least one layer of the substrate is metallic.

19. The method of claim 16, further comprising projecting radiation from the laser through the mask onto the substrate to create indicia within the covert marker.

20. The method of claim 16, wherein the covert marker has a maximum dimension in the range of about 5 to about 30 microns.

21. The method of claim 16, wherein the covert marker has a multi-planar major surface.

22. The method of claim 16, wherein the covert marker comprises an RFID active material, a magnetic material, a conductive material, or an excipient graded material.

23. The method of claim 16, further comprising authenticating the genuine article by identifying the presence of the covert marker.

24. The method of claim 16, wherein the substrate comprises a metallic layer overlying a polymeric layer and wherein the method further comprises producing a metallic covert marker by removing the polymeric layer after the step of projecting radiation and before the step of applying.

25. The method of claim 16, wherein the laser is selected from the group consisting of an excimer laser, an infrared laser, and a carbon dioxide laser.