JPH10126054A - Manufacture of printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of disconnection between the surface of a circuit and the internal surface of a cavity by inserting a jig having a projection which is shorter than the length of a cavity and thicker than a substrate into the cavity in polishing an excessive amount of a resin filling up a hole. SOLUTION: After a through hole 2 is formed through a laminated plate 1, a plated-copper film 5 is formed. Then a hole is filled up with a resin 6 and the resin 6 is cured. Thereafter, the surface of the laminated plate 1 is flattened by polishing the excessive amount of the resin 6 with a belt sander while a jig in which a projection 11 which is thicker than a substrate by 0.1mm and shorter than the length of the cavity 3 of the substrate by 0.05mm is stuck to a glass epoxy laminated board having a thickness of 0.8mm as a back board 12 is put in the cavity 3. Since the projection 11 receives the polishing force of the polishing machine, the stress concentration to the corner sections of the cavity 3 can be prevented and the occurrence of disconnection between the surface of a circuit and the internal surface of the cavity can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a printed wiring board.

[0002]

2. Description of the Related Art Printed wiring boards are formed by drilling through holes and cavities in a copper-clad laminate, plating the holes, filling the through holes, polishing excess filling resin, laminating a dry film, and the like. Circuits are formed by printing, developing, and etching, and solder resist printing is performed to produce products. As the filling resin, an epoxy resin or the like is used, and if necessary, an inorganic filler such as talc, wollastonite, or clay is used in combination. Belts, brushes, rolls, jets, and the like are used to polish excess filling resin.

[0003]

However, when the excess filling resin is shaved off, stress is concentrated on the corners of the cavity and is cut off, so that the cavity wall surface and the circuit surface may be disconnected. As a countermeasure, it is conceivable to increase the thickness of copper (copper foil, plating thickness),
This makes it difficult to form a fine circuit.

[0004] It is an object of the present invention to provide a method for manufacturing a printed wiring board in which a cavity corner is not broken in a polishing step.

[0005]

According to the method of manufacturing a printed wiring board of the present invention, a copper-clad laminate is formed after drilling through holes, cavities and the like, followed by plating, filling the through holes, and removing the excess. Polishing of filling resin, lamination of dry film, baking, development, forming a circuit by etching, in the method of manufacturing a printed wiring board having a cavity structure, when polishing excess filling resin, smaller than the cavity length than the base material Polishing is performed in a state in which a projecting portion of a jig having a thick projection is inserted into the cavity.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The material of the polishing jig is not particularly specified, such as metal such as SUS, plastic, etc. Those having much higher hardness are suitable. Also,
Since the jig will come off if it is a single piece, it is desirable to fix the jig to the backboard 12 and overlap the backboard 12 with the base material and polish the jig. In addition, the back board 12 and the base material may be displaced during polishing and an effective jig effect may not be obtained. Therefore, it is desirable to fix the back board 12 with a guide pin or the like. The thickness of the projection is suitably from 0 to 0.1 mm thicker than the substrate. If the thickness is thinner than the base material, no effect is obtained.
If it is thicker than 1 mm, the periphery of the substrate is not polished.

[0007] When the protruding portion receives the polishing force of the polishing machine, stress concentration on the cavity corner portion is prevented, and disconnection between the circuit surface and the cavity cross section is prevented.

[0008]

【Example】

Example As shown in FIG. 1 (a), a plate thickness of 0.8 mm and a copper foil thickness of 12 mm
μm double-sided copper-foiled glass cloth epoxy resin impregnated laminate 1
MCL-E-679 (manufactured by Hitachi Chemical Co., Ltd.
(Product name), and as shown in FIG.
After opening a through hole 2 of 3 mm, a cavity 3 is formed by router processing. As shown in FIG. 1C, copper plating 5 (plating thickness: 15 μm)
After forming m), as shown in FIG. 1 (d), CCR-5 which is a filler-containing epoxy resin is used as the filling resin 6.
06 (trade name, manufactured by Asahi Chemical Laboratory Co., Ltd.) is filled by a silk screen printing method, and then cured at 160 ° C. for 60 minutes. Here, LE-67 (a product of Hitachi Chemical Co., Ltd., trade name: As shown in FIG. 1 (e), the jig adhered to (1) is aligned with the cavity 3 of the base material, and excess filling resin is polished with a belt sander (belt roughness: # 1000).
Flatten as shown in FIG. As shown in FIG. 1 (g), after a wiring pattern 7 is formed by a normal tenting method, as shown in FIG. (Trade name, manufactured by Co., Ltd.) was formed by a silk screen printing method to obtain a wiring board with a cavity. As a result of measuring the conductor thickness at the corners of the cavity of this wiring board, the conductor thickness in the cavity was 23 μm on average, and the disconnection rate of the wiring pattern was 0%.

Comparative Example A wiring board with a cavity was obtained in the same manner as in the example except that no jig was used in FIG. 1 (e) of the example.
As a result of measuring the conductor thickness at the corners of the cavity of the wiring board, the minimum conductor thickness in the cavity was 4 μm on average, and the disconnection rate of the wiring pattern was 25%.

[0010]

According to the present invention, when polishing an excess filling resin, a jig having a projection smaller than the cavity length and thicker than the base material is inserted into the cavity.
A printed wiring board that does not break at the corner can be manufactured.

[Brief description of the drawings]

1 (a) to 1 (h) are cross-sectional views in respective steps for explaining one embodiment of the present invention.

[Explanation of symbols]

1. 1. laminated board Through hole 3. Cavity 5. Copper plating 6. Filling resin 7. 7. Wiring pattern Solder resist 11. Protrusion 12. Backboard

Claims (2)

[Claims] 1. After drilling through holes and cavities in a copper clad laminate, plating and filling the through holes, polishing excess filling resin, laminating a dry film, baking, developing and etching. In the method of manufacturing a printed wiring board having a cavity structure, a protrusion portion of a jig having a protrusion smaller than the cavity length and thicker than the base material is inserted into the cavity when polishing excess filling resin. A method for manufacturing a printed wiring board, characterized by polishing in a state. 2. The method for manufacturing a printed wiring board according to claim 1, wherein the thickness of the jig is 0 to 0.2 mm thicker than the base material.