WO2003005786A1 - Method for manufacturing printed wiring board - Google Patents

Abstract

A method for manufacturing a very-thin printed wiring board a plurality of which can be stacked, characterized by comprising the steps: A. preparing a silicon wafer (20) having a thickness of 50 to 300 µm; B. attaching the silicon wafer (20) to a jig (10) for holding only the edge of the silicon wafer (20), covering the whole surface of the silicon wafer (20) with a film, and fixing the silicon wafer (20) to the jig (10); C. patterning the film to expose the front and back faces of the silicon wafer (20); D. making a through hole in a predetermined position of the exposed silicon wafer (20), and forming a metallic thin film on the exposed surface of the silicon wafer (20) having the through hole; and E. patterning the metallic thin film, and performing etching so as to produce a predetermined conductor pattern.

Description

 Description Manufacturing method of printed wiring board Technical field

 The present invention relates to a method for manufacturing a printed wiring board using an extremely thin silicon wafer as a base material. Background art

 In response to the demand for high-density mounting of electronic components, multilayer printed wiring boards (multilayer printed wiring boards) are used. However, the multilayer printed wiring board uses a ceramic substrate, a laminate, a composite laminate, or the like as its substrate, and the requirements for the thickness of the substrate and the electrical characteristics did not match. Disclosure of the invention

 An object of the present invention is to provide a method for manufacturing an extremely thin printed wiring board capable of manufacturing a printed circuit board that can be stacked in multiple stages.

 That is, the present invention is a method for manufacturing a printed wiring board, comprising the following steps.

A. The thickness is 50! Prepare ~ 300 m of silicon wafer;

 B. attaching the silicon wafer to a jig capable of holding only the periphery thereof, covering the entire surface with the jig with a film, and fixing the silicon wafer to the jig;

C. patterning the film to expose the front and back surfaces of the silicon wafer (the exposed portions become work areas for forming wiring patterns, through holes and bump lands);

 D. forming a through hole at a predetermined position of the exposed silicon wafer 18, and forming a metal thin film on an exposed surface of the silicon wafer including the through hole;

E. Pattern the metal thin film, then perform etching to Get a turn. BRIEF DESCRIPTION OF THE FIGURES

 FIG. 1 is a block diagram showing a method for manufacturing a printed wiring board according to the present invention along a flow of main steps.

 FIG. 2 is a plan view showing a jig used in the method for manufacturing a printed wiring board of the present invention together with a substrate material held thereon.

 FIG. 3 is a partially enlarged cross-sectional view (cut along the line AA) showing one embodiment of a jig holding the substrate material shown in FIG.

 FIG. 4 is a partially enlarged sectional view (cut along the line AA) showing another embodiment of the jig holding the substrate material shown in FIG.

 FIG. 5 is a partially enlarged cross-sectional view (cut along the line AA) showing still another embodiment of the jig holding the substrate material shown in FIG.

 FIG. 6 is a partially enlarged cross-sectional view (cut along the line AA) showing still another embodiment of the jig holding the substrate material shown in FIG.

 FIG. 7 is a partially enlarged cross-sectional view showing a state where the jig holding the substrate material shown in FIG. 3 is covered with a film and the front and back surfaces of the substrate material are exposed.

 Where each sign is

1 0 Jig

1 0a Main part of jig

1 0 b Step of jig

 1 0 c Slope part of jig (one slope part)

10 d Slope of jig (other slope)

1 1 One component of jig

1 1 a Step of one component of jig

1 1 b One component of jig (main part)

 1 1c Slope of one component of jig or slope of main part (one slope)

1 Id Slope of one component (main part) of jig (other slope) 12 The other component of the jig

 12 a Step of the other component of the jig

 12 b The other component of the jig (donut-shaped member)

 12 c Slope of the other component of the jig

 13 Jig groove

 14 Opening

 15 Coating film

 20 Substrate material

 20a Peripheral edge of substrate material

, Respectively. BEST MODE FOR CARRYING OUT THE INVENTION

 DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail with reference to the accompanying drawings showing one embodiment (except for FIG. 1, the dimensions shown in the drawings are not to scale because the purpose is to show the interrelation and structure of each member).

 FIG. 1 shows a standard process diagram of the present invention.

 A. Board preparation

 In the present invention, a silicon wafer cut from an ingot is used as the substrate material (20). Its thickness is 50-300 m (for semiconductors, it is 735 m for an 8-inch one. In the state of a chip, it is at least about 30 m thick, but it was cut out from an ingot.) It was reduced by applying a separate grinding process. The surface roughness of about 1,000 to 5,000 A (10-point average roughness specified in JIS B 0601: Rz) is sufficient, and a mirror finish like that for semiconductors is not required.

 B. Installation on jig

Since the thickness of the substrate material (20) prepared in the previous process is thin, the substrate is held by a special jig (10) in consideration of handling properties and processing accuracy in the subsequent processing. Specifically, as shown in FIG. 2, the peripheral part (20a) of the substrate is connected to the main part (10a) of the jig by a step (10b) provided on the inner peripheral part (in the figure, Shape around Although it is configured as described above, it may be formed in a claw shape at predetermined intervals in the circumferential direction. In such a case, the jig and the substrate are integrated with a film in the next step as described below. Usually, mounting is sufficient). The jig (10) shown in FIG. 3 is composed of one member (10a) (hereinafter referred to as the main part of the jig). Force is more secure for holding the substrate on the jig. In order to make the member into two members

(1 1) and (12), and the inner peripheral edges of both members are stepped (11a,

12a) (The height of the cut portion is 1Z2 of the thickness of the substrate, respectively) is provided, and the peripheral portion (20a) of the substrate may be sandwiched between both members (see FIG. 4). A step (11a) (the height is the same as the thickness of the substrate) is provided only on the inner peripheral edge of the member (11), and the other member (12) has a flat lower surface and a front end of the lower surface. The upper surface of the peripheral portion (20a) of the substrate placed on the step portion may be pressed by the portion (see FIG. 5), or the jig may be moved to a main portion having a step portion (11b). (The two members (11, 12) that substantially constitute the jig shown in FIGS. 4 and 5 are in the form of a core, and the bottom of the step portion has the thickness of the main portion. Formed substantially at a position lower than the center by 12 times the thickness of the substrate), and the depth of the step is set to the width, and the outer peripheral edge of the step is substantially in contact with the deepest part of the step of the jig. Disk (12b) ( The other member shown in Fig. 5

(12) has only its tip) (see FIG. 6). In the figure, reference numeral 14 denotes an opening of the jig (FIG. 2 shows the state where the substrate is attached to the jig, so that reference numerals 20 and 14 and 20a and 10b 1 1a, 12a, 12b and force are assigned to the same places, respectively, and reference numerals 10a, 11 and lib and 12 are also viewed from above with their upper and lower surfaces abutting against each other. So it is attached to the same place). The slope portions (10 c, 10 d, lie, lld, 12 c, 11 d) of the members constituting the jig are used to smoothly cover the jig and the substrate in a film coating step described later. This is done in order to make the thickness of the resist applied in the step (1) and / or (2) of forming the metal thin film and the step of forming the conductor pattern uniform (slot coating-coating). (1) Spin coating-Smooth discharge of excess resist, etc.) The angle of the substrate to be held on the jig The diameter may be set appropriately according to the diameter of the jig, the diameter of the jig, and the properties of the resist to be applied. Generally, it is selected within the range of 3 to 10 °. In addition, an appropriate radius is applied to the corners of the jig, for example, the transition from the outer peripheral surface to the upper and lower surfaces, and the corners, in order to secure coating with the film in the next step. Is preferred.

Here, the jig is made of a metal such as aluminum, copper, or brass in that the jig has a certain degree of rigidity and is excellent in conductivity and resistance to chemical agents. In an embodiment in which one of the members is a donut-shaped disk, the member is preferably made of metal because its weight also contributes to holding the substrate.) Further, the step of the jig has a distance H between the upper surface of the jig and the upper surface of the substrate when the substrate is placed thereon (in the embodiment shown in FIGS. 4 and 5, The distance between the upper surface of the other member of the jig and the upper surface of the substrate, in the embodiment shown in FIG. 6, the distance between the upper surface of the main portion of the jig and the upper surface of the substrate) is the lower surface of the jig and the upper surface of the substrate. Distance from the lower surface of the substrate: H (In the embodiment shown in FIGS. 4 and 5, the distance between the lower surface of one member of the jig and the lower surface of the substrate, and in the embodiment shown in FIG. (The distance between the lower surface of the main part of the tool and the lower surface of the substrate). In order to use the upper and lower surfaces of the substrate as a formation point thereof in order to increase the density of the conductor pattern, it is possible to easily perform exposure in patterning as a forming operation by overturning the upper and lower surfaces of the substrate. is there. Further, in the drawing, one jig is shown for one silicon wafer as the substrate material, but of course, one jig is used for a plurality of silicon wafers. Needless to say, the one-to-one correspondence is good from the flexibility of securing the exposure work area, while the plural-to-one correspondence is good in terms of the efficiency of forming the metal thin film described later. It should be selected appropriately according to the situation). Although the jig is shown as being substantially square in the drawing, the outer shape thereof may of course be circular or polygonal. A plurality of radially arranged upper and lower surfaces of the jig and slopes connected to the jig (the number is appropriately selected according to the diameter of the substrate to be held on the jig, and therefore the diameter of the jig) The air vent groove (13) is provided in consideration of the composite distribution of the jig (the starting point or the end point is the outer peripheral end of the jig, and the end point or the starting point is the Is the inner peripheral end of the tool slope). This is for surely performing the film coating described later. Here, the shape (cross section) of the groove is a semicircle, Any shape may be used as long as the air existing between the film and the jig and the substrate when the film is coated, such as a semi-ellipse, a corner, or a triangle, can smoothly escape. However, it is preferable that the transition from the upper end of the wall of the groove to the upper and lower surfaces including the slope portion of the jig is provided with a radius in order to secure the adhesion of the film.

 C. Coating with film

 In order to secure the accuracy of the subsequent processing, the substrate material held by the jig is covered and fixed together with a film (14) together with the jig. As the film, a dry resist, for example, a negative type dry film can be cited as a candidate from the viewpoint of handleability. The coating with the film is performed by, for example, bringing the film into close contact with the entire jig holding the substrate material by, for example, a vacuum laminating method, and bonding the film to the peripheral portion (20 a) of the substrate. This is done by patterning so that the front and back surfaces of the substrate material are exposed, except for the area near the inside (see Fig. 7. The substrate material exposes most of the front and back surfaces (the area indicated by arrows in the figure)). In addition, since the jig is held tightly in this state, since the cross-sectional view is shown in FIG. 7, the coating film should be displayed with diagonal lines, but the display is not complicated. Therefore, diagonal lines have been omitted.)

 D. Formation of through hole

 Through holes are formed at predetermined positions in the substrate material for multi-layered printed circuit boards. Since the substrate material has a small thickness, the through hole can be formed by a laser, for example, a perforation method using a carbon dioxide laser or a YAG laser, a plasma etching method, or a photolithography method.

 E. Formation of metal thin film-1

In order to secure the adhesion of the metal thin film 12 described later, a metal thin film-1, for example, a thin film (thickness: at least 5 OA) such as IT〇 or copper [Cu] is formed on the exposed surface of the substrate material. As the method, a vapor deposition method can be used. On the other hand, for applications in which the thickness of the obtained metal thin film does not need to be so large, the metal thin film-1 is formed by an electroless plating method (after forming a nickel [Ni] thin film and then using gold [A u]). (In this case, a part of the nickel thin film is replaced) (in this case, the formed thin film is a composite film of nickel in the lower layer or the base layer and gold in the upper layer or the surface layer). Note that this metal thin film-1 is applied not only to the surface of the substrate material but also to the wall surface of the previously formed through hole. Form.

 F. Formation of metal thin film 1

 On the surface of the substrate material on which the metal thin film 11 is formed, a metal thin film 12 serving as a main component of the conductor pattern, for example, Cu or the like is formed. An example of the method is an electroless plating method (if the electroless plating method is applied in step E, this step is unnecessary). If a thicker metal thin film (thickness: 3 m or more) is desired, an electric plating method is further applied. The metal thin film is formed not only on the surface of the substrate material but also on the wall surface of the previously formed through hole.

 G. Formation of conductive pattern

 Similar to the formation of a conventional conductor pattern, resist coating (the resist coating may be performed in accordance with a conventional method. However, the slot for rotating the jig after the coating using the slot co one time only or the slot co one time only) The application of the AND spin method is preferable because it can reduce the consumption of the resist and can also be applied to the concave portions.In addition, the slot core is preferably used for the diameter of the jig (10) and the substrate (20). It is good to rotate the slot core around the center of the jig and the substrate.) Exposure and development (exposing the metal thin film other than the desired conductor pattern) Etch removal of the exposed metal thin film, and stripping and removal of resist. When a negative type dry film is used as a film for fixing the substrate material to the substrate, a positive type resist is used here. This is because the dissolution of the film in the developer used in this step can be prevented.

 H. Other

For the time being, a product having a function as a printed wiring board is manufactured in the steps up to this point. After that, the printed wiring board can be obtained by cutting to a desired size. Before cutting, if necessary, apply resist, expose and develop (expose the bumps in the conductor pattern), and form the bumps (by using a solution containing gold ions). In addition, since the bump needs a certain height, it is only necessary to first form an underlayer made of copper, nickel, or the like, and then apply gold plating only to the surface layer of the underlayer.) Or a solder ball may be applied to a predetermined position according to a conventional method. So far, a case has been described in which a conductor pattern is newly formed on a substrate. However, the feature of the manufacturing method using the jig of the present invention is that an ultra-thin substrate (silicon wafer) which has never been seen before. This is also applicable to the case where a conductor pattern has already been formed on a substrate, for example, a case where only bumps are formed on a circuit-formed I, since the problem caused by the thinness can be solved. It is. By the way, in conventional IC manufacturing, bumps are formed after the back surface of a thick substrate (silicon wafer) is physically ground to a desired thickness. A method in which a bump is formed on a substrate (silicon wafer) that is still bad or thick, and then the back surface of the substrate is ground to a desired thickness by dry etching or the like (a considerable cost is required to provide dry etching equipment). Was applied.

Example

 Using an 8-inch silicon wafer (thickness: 200 mm; nominal diameter: 200 thighs). 20 printed wiring boards were manufactured in the following manner.

 1. Jig for holding substrate material

 Uses a jig with the following specifications (specifics are shown in Fig. 3).

 • Vertical: 230 thighs;

 • Horizontal: 23 O mm;

 • Thickness: 1 thigh;

 · Aperture diameter: 196 thighs;

 • Step width: 2 mm;

 • Step formation range: all around;

 • Upper mouth slope: about 7.6.

 • Inclination of lower mouth: about 4.6 °

 2. Film coating

Using a vacuum laminator (Nichigo Morton CVA MO DEL 7 25), dry film (Nichigo One Morton NIT 3 1) was applied to both sides of the silicon 5; Thickness: 15 // m), covering the jig together with the jig and fixing the silicon wafer tightly to the jig. The film was exposed and developed to secure a work area (both sides) with a diameter of 190 marauders on the silicon wafer.

 3. Through-hole formation

 10 through-holes (diameter: 100 m) were formed in the silicon layer 8 in the work area by Z-etch etching.

 4. Formation of metal thin film 1

 Using a sputtering device (SH-450 manufactured by Nihon Vacuum Co.), a metal thin film 1 (ITO; thickness: 10 OA) was placed on a silicon wafer (both sides, including the inner wall of a through hole) in the work area. Formed (Target: Number of wafers: 1).

 The electroless plating method (using Melplate Ni-867M1-M2 and Au-601 manufactured by Meltex Co., Ltd.) can also be applied to the metal thin film-1 (1 ^ 1 + 8 \ 1; thickness: 0.5 m). ) Was formed (the number of target A eight sheets: 1).

 5. Formation of metal thin film 1

 In the electroless plating method (using Cu Po sit 251 manufactured by Shipley Furist Co., Ltd.), a metal thin film 1 (Cu; thickness: 20 im) is further formed on the metal thin film 11 formed in advance by the sputtering method. Formed.

 6. Formation of conductor pattern

 A resist (positive resist: s PR-6800, manufactured by Shipley Farst Co., Ltd.) was applied on the metal thin film 1 and the metal thin film 1 formed only by the electroless plating method. A development pattern was formed on the silicon wafer (both sides) by performing development, etching, and resist stripping. The details are as follows.

 'Used Koichi Yuichi: Hirata Kiyoshi Co., Ltd. Slot Koichiyuichi

 • Resist coating thickness: 10 m (after drying: 3 m)

 'Mask pattern: use 3m LZS

 • Exposure light source: 200 Φ PRO J-2001 manufactured by Mejiro Investment Co., Ltd. • Etch solution: VPositeEtch 746 manufactured by Shipley Far East Co., Ltd.

• Stripper: Shipley Faster remover 1 177 A 7. Bump formation

 A resist (positive resist manufactured by Shipley Pfist Co., Ltd .: SPR-6800) was applied, and then exposure, development, electric plating, and resist stripping were performed to form gold bumps on the bump lands of the wiring pattern. The details are as follows.

 'Use Koichi Yoichi: Hirata Kiyoshi's slot Koichiichi (αKoichiyuichi). The direction of the slot is the radial direction of the substrate.

 • Resist coating thickness: 10 im

 • Mask pattern: Bump land diameter of 100 100Φ and 200ΠΙΦ

 • Exposure light source: Use 200 Φ PRO J-2001 manufactured by Mejiro Investment Co., Ltd. Mesh liquid: Evalon NiBM-2 (for base) and Riptorores SMT 250 (gold plated) manufactured by Rironal. Use each

 • Peel off liquid: Use Shipper Faust remover 1 1 77 A

 8. Dicing

 Conforms to conventional IC dicing.

 When the completed printed wiring boards (20 bandages) were stacked in five layers in the vertical direction and electricity was passed, conduction to all the wiring boards was confirmed. Industrial applicability

 As described above, according to the present invention, it is possible to provide a method for manufacturing a printed wiring board capable of manufacturing an ultrathin printed circuit board that can be stacked in multiple stages and that meets the requirements for the thickness of the substrate and the requirements for electrical characteristics.

Claims

The scope of the claims 1. A method for manufacturing a printed wiring board, comprising the following steps: A. A thickness of 50; Prepare up to 300 wafers of silicon wafer; Β. Attach the silicon wafer to a jig capable of holding only the periphery thereof, cover the entire surface with a film, and fix the silicon wafer to the jig;  C. patterning the film to expose the front and back of the silicon wafer; D. forming a through hole at a predetermined position of the exposed silicon wafer and forming a metal thin film on an exposed surface of the silicon wafer including the through hole;  Ε. The metal thin film is patterned and then etched to obtain a predetermined conductor pattern. 2. After the formation of the conductor pattern, a resist is applied and the coating is further performed, and then a bump is formed at a predetermined position on the conductor pattern by gold plating using copper or nickel as a base layer. The method according to paragraph 1 above. 3. The method according to claim 1 or 2, wherein said silicon wafer has a surface roughness of 100 to 500 OA. 4. The method according to any one of claims 1 to 3, wherein the film is a negative type dry film, and the resist used for patterning the metal thin film is a positive type. . 5. The method according to any one of claims 1 to 4, wherein the metal thin film is formed by vapor deposition and electroless Cu plating or electroless Ni-Au plating. 6. The method according to claim 5, wherein an electric plating is further performed after the electroless Cu plating. 7. The method according to any one of claims 1 to 6, wherein the formation of the through hole is performed by a laser drilling method, a plasma etching method, or a photolithography method. 8. A substantially square or circular jig for manufacturing a silicon printed wiring board having an opening in the center thereof and a step near the opening on which a peripheral portion of the silicon wafer 18 can be placed. The step is formed so that the central axis in the thickness direction of the jig and the central axis in the thickness direction of the silicon wire 8 are coaxial; A linear downward slope that rises from the lower surface toward the inner peripheral end of the horizontal surface of the step and a slope from the upper surface toward the upper end of the wall surface of the step or at the same slope as the lower slope. A downwardly extending linear upper slope; and a groove extending radially of the opening on the upper and lower slopes and the upper and lower slopes, the starting and ending ends of which are outer peripheral ends of the upper and lower faces and the step. The upper end of the section wall or the end of the upper slope and the tip of the horizontal plane of the step Silicon printed circuit board jig manufacturing, characterized in that it comprises a. 9. The jig according to claim 8, wherein said jig is formed of one member. 10. The jig is composed of two members, upper and lower, which abut on the upper surface and the lower surface thereof. The step is formed on each member, and the peripheral portion of the silicon wafer is placed. Are sandwiched by horizontal surfaces of both steps, the center axis in the thickness direction of the jig is a contact surface of these members, and the slope of the upper member is the tip of the horizontal surface of the step of the upper member. 9. The jig according to claim 8, wherein the jig descends toward. 1 1. The jig is composed of two members, upper and lower, which abut on the upper surface and the lower surface thereof, and the step is formed only on the lower member, and the peripheral portion of the silicon wire 8 is mounted on the jig. Is sandwiched between a horizontal surface of the step portion and a horizontal surface that is the lower surface of the upper member, The center axis in the thickness direction of the jig is located at a position lower than the contact surface of the members by 12 members below the thickness of the substrate, and the slope of the upper member is the same as the slope of the lower member. 9. The jig according to claim 8, wherein the jig descends with the same inclination. 1 2. The slope of the upper slope is the same as the slope of the lower slope, but the tip ends at the upper end of the wall of the step, and the depth of the wall of the step is A holding member having a thickness greater than the thickness of the silicon wafer 18, a peripheral thickness corresponding to the difference and a slope having the same inclination as the upper slope above, and a horizontal surface facing the horizontal surface of the step below, is provided. The jig according to claim 9, further comprising: placing the peripheral portion of the silicon wire 8 between the horizontal surface of the step portion and the horizontal surface of the pressing member. 13. The method according to any one of claims 1 to 7, wherein the jig according to any one of claims 8 to 12 is used.