Printed wiring board

Abstract

To provide a printed wiring board which is suitable for high densification.SOLUTION: A printed wiring board has: a core material which has a first surface and a second surface opposite to the first surface, the core material which is composed of a glass cloth formed of warps and wefts and a resin; a first conductor layer formed on the first surface; a second conductor layer formed on the second surface; through holes for first and second through-hole conductors which penetrate through the glass fiber of the glass cloth and reach the second surface from the first surface; a through hole for a resin member which penetrates through the glass fiber, reaches the second surface from the first surface and fills the resin member positioned between the through holes for the first and second through hole conductors; a through-hole conductor which is formed in the through holes for the first and second through-hole conductors, and connects the first conductor layer and the second conductor layer; and the resin member which fills the through hole for the resin member.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The technology disclosed in this specification relates to a printed wiring board. [Background technology]

[0002] Patent Document 1 discloses a multilayer wiring board including a composite insulation layer in which glass fibers of a glass cloth extend in mutually orthogonal vertical and horizontal directions, a plurality of through holes penetrating the composite insulation layer, and through hole conductors formed in the plurality of through holes. When viewed in a plan view, when the gap between two adjacent through holes is 200 μm or less, an imaginary center line connecting the centers of the two through holes forms an angle with an imaginary vertical line and an imaginary horizontal line extending in the vertical and horizontal directions. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-142826 A Summary of the Invention

[0004] [Problem of Patent Document 1] In the printed wiring board of Patent Document 1, the through holes cannot be positioned freely, which is thought to hinder high density printed wiring boards. [Means for solving the problem]

[0005] The printed wiring board of the present invention has a first surface and a second surface opposite to the first surface, and comprises a core material made of glass cloth formed of warp and weft threads and resin, a first conductor layer formed on the first surface, a second conductor layer formed on the second surface, through holes for first and second through hole conductors penetrating the glass fibers of the glass cloth and reaching from the first surface to the second surface, through holes for a resin member penetrating the glass fibers and reaching from the first surface to the second surface and positioned between the through holes for the first and second through hole conductors for filling with a resin member, through hole conductors formed in the through holes for the first and second through hole conductors and connecting the first conductor layer and the second conductor layer, and the resin member filling the through holes for the resin member.

[0006] In the printed wiring board according to the embodiment of the present invention, a through hole for a resin member for filling the resin member is formed between the through holes for the first and second through-hole conductors. The through hole for the resin member is formed in the core material, extends from the first surface to the second surface, and penetrates the glass fibers of the glass cloth. Therefore, migration along the glass fibers is unlikely to occur. According to the embodiment, migration is suppressed by the through hole for the resin member located between the through holes for the two through-hole conductors and the resin member filled in the through hole for the resin member. The position of the through hole can be freely arranged. Therefore, high density of the printed wiring board is not hindered. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a cross-sectional view illustrating a printed wiring board according to an embodiment. [Diagram 2] FIG. 4 is a plan view illustrating a schematic arrangement of through holes. [Figure 3A] 1A to 1C are cross-sectional views each showing a schematic diagram of a method for manufacturing a printed wiring board according to an embodiment. [Figure 3B] 1A to 1C are cross-sectional views each showing a schematic diagram of a method for manufacturing a printed wiring board according to an embodiment. [Figure 3C] 1A to 1C are cross-sectional views each showing a schematic diagram of a method for manufacturing a printed wiring board according to an embodiment. [Figure 4A]1A to 1C are cross-sectional views each showing a schematic diagram of a method for manufacturing a printed wiring board according to an embodiment. [Figure 4B] 1A to 1C are cross-sectional views each showing a schematic diagram of a method for manufacturing a printed wiring board according to an embodiment. [Figure 4C] 1A to 1C are cross-sectional views each showing a schematic diagram of a method for manufacturing a printed wiring board according to an embodiment. [Figure 5A] 1A to 1C are cross-sectional views each showing a schematic diagram of a method for manufacturing a printed wiring board according to an embodiment. [Figure 5B] 1A to 1C are cross-sectional views each showing a schematic diagram of a method for manufacturing a printed wiring board according to an embodiment. [Figure 5C] 1A to 1C are cross-sectional views each showing a schematic diagram of a method for manufacturing a printed wiring board according to an embodiment. [Figure 6A] 1A to 1C are cross-sectional views each showing a schematic diagram of a method for manufacturing a printed wiring board according to an embodiment. [Figure 6B] 1A to 1C are cross-sectional views each showing a schematic diagram of a method for manufacturing a printed wiring board according to an embodiment. [Figure 6C] 1A to 1C are cross-sectional views each showing a schematic diagram of a method for manufacturing a printed wiring board according to an embodiment. [Figure 7A] 1A to 1C are cross-sectional views each showing a schematic diagram of a method for manufacturing a printed wiring board according to an embodiment. [Figure 7B] 1A to 1C are cross-sectional views each showing a schematic diagram of a method for manufacturing a printed wiring board according to an embodiment. [Figure 7C] 1A to 1C are cross-sectional views each showing a schematic diagram of a method for manufacturing a printed wiring board according to an embodiment. [Figure 8A] 1A to 1C are cross-sectional views each showing a schematic diagram of a method for manufacturing a printed wiring board according to an embodiment. [Figure 8B] 1A to 1C are cross-sectional views each showing a schematic diagram of a method for manufacturing a printed wiring board according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] <Embodiment> FIG. 1 is a schematic cross-sectional view of a schematic configuration of a printed wiring board 30 of an embodiment. The printed wiring board 30 has a core material 1, first conductor layers 10Ua, 10Ub, and second conductor layers 10La, 10Lb. The core material 1 has a first surface F and a second surface S opposite to the first surface F. The core material 1 is made of glass cloth and resin. The glass cloth is formed of vertical glass fibers (warp threads) Sx and horizontal glass fibers (weft threads) Sy. The first conductor layers 10Ua, 10Ub are formed on the first surface F. The second conductor layers 10La, 10Lb are formed on the second surface S.

[0009] The printed wiring board 30 has through holes 50A, 50B and a through hole 150 that penetrate the glass fibers of the glass cloth. The through holes 50A, 50B, and 150 reach the first surface F to the second surface S. FIG. 2 is a plan view that typically illustrates the general arrangement of the through holes 50A, 50B, and 150.

[0010] A power through-hole conductor (first through-hole conductor) 15A is formed in the through-hole (through-hole for the first through-hole conductor) 50A. The through-hole conductor 15A connects the first conductor layer 10Ua and the second conductor layer 10La. The through-hole conductor 15A is connected to a power circuit (not shown). A ground through-hole conductor (second through-hole conductor) 15B is formed in the through-hole (through-hole for the second through-hole conductor) 50B. The through-hole conductor 15B connects the first conductor layer 10Ub and the second conductor layer 10Lb. The through-hole conductor 15B is connected to a ground circuit (not shown).

[0011] The through hole (through hole for a resin member) 150 is filled with the resin member 100. The through hole 150 is located between the through holes 50A and 50B. The through hole 150 is formed at the midpoint of the line connecting the adjacent through holes 50A and 50B. The distance between the centers of the adjacent through holes 50A and 50B is 2L. The distance between the centers of the through holes 150 and 50A is L. The distance between the centers of the through holes 150 and 50B is L. The resin member 100 contains epoxy and glass particles.

[0012] The through holes 50A, 50B, and 150 penetrate the same glass fibers among the multiple glass fibers Sx and Sy that form the glass cloth. The through holes 50A, 50B, and 150 adjacent in the horizontal direction penetrate the same horizontal glass fiber Sx. The through holes 50A, 50B, and 150 adjacent in the vertical direction penetrate the same vertical glass fiber Sy.

[0013] A through hole 150 for the resin member 100 is formed between the through hole 50A for the through hole conductor 15A and the through hole 50B for the through hole conductor 15B. The through hole 150 penetrates the glass fibers of the glass cloth. Therefore, migration along the glass fibers is unlikely to occur. Since the resin member 100 filled in the through hole 150 suppresses migration, the position of the through hole can be freely arranged. Therefore, the high density of the printed wiring board 30 is not hindered.

[0014] <Method of manufacturing a printed wiring board according to an embodiment> 3A to 8B show a method for manufacturing a printed wiring board 30 according to an embodiment.

[0015] As shown in FIG. 3A, a copper-clad laminate in which copper foil 2 is laminated on both sides of a core material 1 made of resin is used as a starting material. As shown in FIG. 3B, holes are drilled in the copper-clad laminate to form through holes 50A, 50B, and 150. A resin member 100 containing epoxy and glass particles is filled in the through hole 150. In FIG. 3B, in order to avoid complication of the illustration, the through hole 50A is illustrated, and the through holes 50B and 150 are omitted. Hereinafter, in FIG. 3B to FIG. 8B, a process of forming a power through hole conductor 15A in the through hole 50A is illustrated, and a process of forming a ground through hole conductor 15B in the through hole 50B is omitted. In the following description, a process of forming a power through hole conductor 15A in the through hole 50A is illustrated, but the same applies to a process of forming a ground through hole conductor 15B in the through hole 50B.

[0016] 3C, through hole 50A is subjected to electroless plating to form through hole 3. Electrolytic copper plating is applied to form conductor layer 4 made of an electroless copper plating film and an electrolytic copper plating film.

[0017] 4A, the entire substrate is washed with water, degreased with an alkaline system, activated with a weak acid for the conductor layer, dried, and then immersed in a predetermined solution for cleaning. An organic compound layer 4a is formed on the entire surface of the conductor layer 4.

[0018] 4B, a predetermined conductive paste 5 is filled into the through-hole 3, dried, and then cured by heating. The roughened surface on the conductor top surface and the conductive paste 5 protruding from the through-hole 3 are removed by polishing. Furthermore, appropriate buff polishing is performed to flatten the surface of the entire board.

[0019] As shown in FIG. 4C, a catalyst is applied to the entire surface of the planarized substrate, and electroless copper plating is performed to form an electroless copper plating film 6.

[0020] 5A, electrolytic copper plating is performed under predetermined conditions to form an electrolytic copper plating film 7. The portions that will become the inner layer conductor circuits 9 described below are thickened, and the portions that will become the first conductor layer 10Ua and the second conductor layer 10La that cover the conductive paste 5 filled in the through holes 3 are formed. A photosensitive dry film is attached on the electrolytic copper plating film 7, and a mask is placed on it, exposed to light, and developed to form an etching resist 8.

[0021] 5B, the electrolytic copper plating film 7 in the portion where the etching resist 8 is not formed is dissolved and removed by etching, and the etching resist 8 is further peeled off and removed. An independent inner layer conductor circuit 9, a first conductor layer 10Ua, and a second conductor layer 10La are formed. A through-hole conductor 15A is formed by the conductive paste 5 between the first conductor layer 10Ua and the second conductor layer 10La.

[0022] As shown in Fig. 5C, an organic compound layer 11 is formed on the inner layer conductor circuit 9, the first conductor layer 10Ua, and the second conductor layer 10La by a dipping method. A resin filler 21a of a predetermined composition is applied and filled between the inner layer conductor circuit 9 and the first conductor layer 10Ua, and between the inner layer conductor circuit 9 and the second conductor layer 10La, and is cured. The surface of the organic compound layer 11 is polished and smoothed until the surface is exposed.

[0023] As shown in FIG. 6A, a predetermined adhesive for electroless plating is applied to both sides of the entire substrate, and after drying, an adhesive layer 12b of a predetermined thickness is formed.

[0024] As shown in Fig. 6B, a photomask film with black circles printed on it is placed on the adhesive layer 12b, exposed to light, and then developed. Openings 13 for forming via holes are formed in the adhesive layer 12b. Furthermore, the entire substrate is exposed to light and heat-treated to form an interlayer resin insulating layer having openings 13 corresponding to the photomask film.

[0025] The entire substrate is immersed in a predetermined solution, and after the surface of adhesive layer 12b is roughened, it is washed with water. A predetermined catalyst is applied to the entire substrate, and catalyst nuclei are applied to the surfaces of adhesive layer 12b and openings 13. As shown in Fig. 6C, the entire substrate is immersed in a predetermined aqueous electroless copper plating solution, and an electroless copper plating film 14 is formed on the entire rough surface.

[0026] A photosensitive resin film is attached onto the electroless copper plating film 14. A glass substrate on which the non-plating resist portion is drawn as a mask pattern is attached to the photosensitive resin film, and then exposed and developed. As shown in Fig. 7A, a pattern of plating resist 16 with a predetermined thickness is formed.

[0027] As shown in FIG. 7B, electrolytic copper plating is performed under predetermined conditions, and an electrolytic copper plating film 65 is formed on the electroless copper plating film 14 exposed from the pattern of the plating resist 16.

[0028] As shown in Fig. 7C, plating resist 16 is peeled off and removed, and electroless copper plating film 14 beneath plating resist 16 is dissolved and removed by etching. Outer layer conductor circuit 9 and via-hole conductor 17 made of electroless copper plating film 14 and electrolytic copper plating film 65 are formed. An organic compound layer 11 (see Fig. 8A) of a predetermined thickness is formed on the surfaces of outer layer conductor circuit 9 and via-hole conductor 17.

[0029] 6B to 7C are repeated to further form an outer interlayer resin insulating layer, outer conductor circuits 9, and via-hole conductors 17, as shown in Fig. 8A. A multilayer wiring board in which organic compound layers 11 are formed on the surfaces of the outer conductor circuits 9 and the via-hole conductors 17 is obtained.

[0030] As shown in FIG. 8B, a predetermined solder resist composition is applied to both sides of the multilayer wiring board. After drying, a glass substrate on which a mask pattern of solder resist openings is drawn is adhered to the solder resist layer, exposed to ultraviolet light, and then developed. Heat treatment is performed under predetermined conditions to form a solder resist pattern layer 18 in which the upper surfaces of the solder pads, via holes, and land portions are opened. Thereafter, the entire multilayer wiring board is immersed in an electroless nickel plating solution to form a nickel plating layer 19 in the openings. The entire multilayer wiring board is immersed in a predetermined electroless gold plating solution to form a gold plating layer 20 on the nickel plating layer 19. Solder paste is formed in the openings of the solder resist pattern layer 18, and solder bumps 21 are formed by reflow treatment. A multilayer printed wiring board 30 having solder bumps 21 is obtained. [Explanation of symbols]

[0031] 1: Core material 2: Copper foil 3:Through hole 4: Conductive layer 4a:Organic compound layer 5: Conductive paste 6: Electrolytic copper plating film 7: Electrolytic copper plating film 8: Etching resist 9: Conductor circuit 10La: Second conductor layer 10Lb: Second conductor layer 10Ua: First conductor layer 10Ub: First conductor layer 11:Organic compound layer 12b: Adhesive layer 13:Aperture 14: Electroless copper plating film 15A: First through-hole conductor 15B: Second through-hole conductor 16: Plating resist 17: Via hole conductor 18: Solder resist pattern layer 19: Nickel plating layer 20: Gold plating layer 21: Solder bumps 21a: Resin filler 30: Printed wiring board 50A: Through hole 50B: Through hole 65: Electrolytic copper plating film 100: Resin material 150:Through hole F: 1st page S: 2nd side Sx: Glass fiber Sy: Glass fiber

Claims

1. a core material having a first surface and a second surface opposite to the first surface, the core material being made of glass cloth formed of warp and weft threads and a resin; a first conductor layer formed on the first surface; a second conductor layer formed on the second surface; through holes for first and second through-hole conductors passing through glass fibers of the glass cloth and reaching from the first surface to the second surface; a through hole for a resin member for filling the resin member with the resin member, the through hole penetrating the glass fiber from the first surface to the second surface and positioned between the through holes for the first and second through-hole conductors; a through-hole conductor formed in a through hole for the first and second through-hole conductors and connecting the first conductor layer and the second conductor layer; and the resin member filling the through hole for the resin member.

2. 2. A printed wiring board according to claim 1, wherein a through hole for the resin member for filling the resin member is formed at the midpoint of a line connecting adjacent through holes for the first through hole conductor and the second through hole conductor.

3. 3. The printed wiring board according to claim 2, wherein the resin member contains epoxy and glass particles.

4. 2. The printed wiring board of claim 1, wherein the through-hole conductor formed in the through hole for the first through-hole conductor is a first through-hole conductor, the through-hole conductor formed in the through hole for the second through-hole conductor is a second through-hole conductor, the first through-hole conductor is connected to a power supply circuit, and the second through-hole conductor is connected to a ground circuit.

5. 2. The printed wiring board of claim 1, wherein the through hole for the first through-hole conductor, the through hole for the second through-hole conductor, and the through hole for the resin member penetrate the same glass fiber among the multiple glass fibers forming the glass cloth.

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