JP2001177245A - Method of manufacturing smooth printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a durable smooth printed wiring board which is suitable for applications in which electrodes are moved slidingly. SOLUTION: This printed wiring board is manufactured, in such a way that a circuit board 5 having an etched circuit pattern section 3, insulating recessed sections 4, and through-holes 7 formed here and there in the recessed sections 4 is laminated upon a prepreg 10 and the circuit board 5 and prepreg 10 is thermocompression bonded to the circuit board 5 and prepreg 10 by laying adhesive-coated peeling films 16 on the outside so as to fill the recessed sections 4 with a resin 11 through the through-holes 7, until the surface of the packed resin 11 is flush with the surfaces of circuit pattern sections 3.

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 having smoothness.

[0002]

2. Description of the Related Art Conventionally, when a printed wiring board is a four-layer board as an example, a copper foil is thermocompression-bonded to an inner circuit board on which a circuit is formed via a semi-cured adhesive sheet (prepreg) to form a copper containing inner circuit. A laminated board was produced, and then holes were formed and plated with copper to form an outer layer circuit.

[0003]

In such a printed wiring board, since the outer layer circuit and the insulating portion have irregularities, the electrode slides on the surface thereof. However, there is a problem that the shoulder of the circuit of the printed wiring board is shaved, the durability of the printed wiring board is deteriorated, and short circuit occurs between adjacent circuits due to shavings of the circuit. In addition, the sliding electrode itself also suffers from abrasion due to irregularities in the outer layer circuit and the insulating portion, resulting in a problem that durability is deteriorated.

[0004]

SUMMARY OF THE INVENTION The present invention has been studied to solve the problems of the prior art, and has the following features. That is, a prepreg 10 and a circuit board 5 having a circuit pattern portion 3 and an insulating concave portion 4 based on an etching process, and having a through hole 7 at each part of the insulating concave portion 4, are laminated, and an adhesive with an adhesive is provided outside. Mold film 1
6 and thermocompression bonded, and the insulating recess 4
A method for manufacturing a printed wiring board having smoothness, in which resin 11 is filled flush with the circuit pattern portion 3, a method for manufacturing a printed wiring board having smoothness, in which the circuit pattern portion 3 is plated, and thermocompression bonding with a vacuum press This is a method for manufacturing a printed wiring board having smoothness. Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view of a circuit board 5 used in the present invention. By etching and drilling a copper clad laminate, a circuit pattern portion 3 and an insulating recess 4 are formed. Through holes 7 are provided in some places. As the copper-clad laminate, a laminate obtained by impregnating a paper base or a glass base with an epoxy resin, a phenol resin, a polyimide resin, or the like and laminating a copper foil can be used.

FIG. 2 is a perspective view of a printed wiring board 20 having smoothness obtained by the present invention. The surface on which the electrode slides is formed in the insulating recess 4 through the through hole 7 and the resin is flush with the circuit pattern portion 3. 11 are filled. Copper foil 8 is used as a base material of the lower layer. As the base material, in addition to the copper foil, an aluminum foil, a nickel foil, a substrate on which a circuit is formed, an insulating plate, and a copper-clad laminate as described above by etching and drilling to form a circuit pattern portion 3 '. And an insulating recess 4 ′ are formed, and through holes 7 ′ are formed in places of the insulating recess 4 ′.
Is provided, but is not particularly limited.

FIG. 3 is a cross-sectional view schematically illustrating a method of manufacturing a printed wiring board 21 having smoothness according to another embodiment, and FIG. 4 is a cross-sectional view illustrating the configuration of the printed wiring board 21 having smoothness. The circuit board 5 and a similarly processed circuit board 5 'are overlapped via a prepreg (semi-cured adhesive sheet) 10 and a release film 16 with an adhesive is provided on the outside of the circuit board 5, 5' with an adhesive surface. 17 is arranged so as to be in contact with the circuit boards 5 and 5 'and thermocompression-bonded. When the thermocompression bonding is performed, the resin in the prepreg melts, flows outward through the through holes 7 and 7 ′, and fills the insulating concave portions 4 and 4 ′ flush with the circuit pattern portions 3 and 3 ′, and the resin 11 is cured. Then, the circuit pattern part 3,
3 'and the electrode slides on this surface.

By using the release film 16 with an adhesive, the adhesive is sufficiently adhered to the circuit pattern portions 3 and 3 'of the circuit boards 5 and 5', and the resin does not overflow onto the circuit pattern portions 3 and 3 '. Finished smoothly. Therefore, a buff polishing step for removing the overflowing resin is unnecessary, which is convenient.

The release film 16 with an adhesive is, for example,
Acrylic adhesives such as polypropylene films, fluorine films, polyamide films, polyimide films, polyester films, polycarbonate films, or composite films obtained by laminating these films, such as those coated with a rubber-based adhesive, and the like. There is no particular limitation on the material of the film, the type of the adhesive, the raw material, and the like. The film may have any heat resistance and mold release properties, and any adhesive may be used as long as it is in close contact with the circuit pattern portion. The surface of the film on which the pressure-sensitive adhesive is not applied may be subjected to a release treatment as required.

Polymers serving as bases of rubber-based pressure-sensitive adhesives include, for example, natural rubber, isoprene rubber, SBR (styrene-butadiene rubber), SBS (styrene-butadiene block copolymer), and SIS (styrene-isoprene block copolymer) ), Silicone rubber, chloroprene rubber, butyl rubber, nitrile rubber, polyisobutylene, recycled rubber, and the like.

The main monomers of the acrylic pressure-sensitive adhesive include, for example, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate and the like.

The prepreg 10 may be a known one, for example, a semi-cured material obtained by impregnating a base material made of glass fiber or aramid fiber with a resin having excellent heat resistance such as epoxy resin, triazine resin or polyimide resin. .

[0013] The means for thermocompression bonding may be any means capable of flowing out the resin in the prepreg.
A vacuum press, such as a hydraulic press, a hydraulic vacuum press, and an autoclave vacuum press, may be used. The use of a vacuum press is preferable because the resin has a smoother filling of the insulating recesses with very few bubbles.

FIG. 5 is a sectional view showing the configuration of a printed wiring board 22 having plating on the circuit pattern portions 3 and 3 'and having smoothness. By forming the plated portions 6 and 6 ', the circuit pattern portions 3 and 3' are sufficiently protected, and the durability is further improved. Examples of plating include gold plating and nickel plating, but are not particularly limited. Examples will be described below.

[0015]

Example 1 Epoxy resin impregnated paper base material with a thickness of 35 micron
Etching and drilling a copper-clad laminate with laminated copper foil
By drilling, the circuit pattern and circuit
Through holes with a hole diameter of 0.9 mm in insulating recesses at 2.5 mm intervals
Were provided at intervals of 2.54 mm. Next
In this circuit board and copper foil between the glass cloth base epoxy resin
Two prepregs are interposed, and 2-ethylhexyl
Acrylic pressure-sensitive adhesive mainly containing
Adhesive side of the wrapped polypropylene film contacts the circuit board
170 ° C, pressure using a hydraulic press
10kg / cm ^TwoThermocompression bonding for 100 minutes. Then
Epoxy resin flows out through the insulating recess through the through-hole circuit
Print with smoothness filled flush with the pattern part
A wiring board was obtained.

[0016]

Example 2 Two circuit boards similar to those in Example 1 were prepared. Next, two glass cloth-based epoxy resin prepregs were interposed between these circuit boards, and a fluorine film coated with a silicone-based pressure-sensitive adhesive was arranged such that the adhesive face was in contact with the circuit board. Thereafter, using an autoclave vacuum press, the conditions during molding were as follows: a degree of vacuum of 50 mmHg, and a temperature of 1 mm.
When thermocompression bonding was performed at 70 ° C. for 100 minutes, a printed wiring board having smoothness was obtained.

[0017]

Embodiment 3 A copper-clad laminate obtained by laminating a copper foil having a thickness of 70 μm on an epoxy resin-impregnated paper base material is subjected to etching, drilling, and gold plating to apply gold plating to a circuit pattern portion, thereby forming a circuit portion. Two circuit boards were prepared in which through holes having a hole diameter of 0.9 mm were provided at intervals of 2.54 mm in insulating recesses at intervals of 2.5 mm without holes. Next, two glass cloth base epoxy resin prepregs are interposed between these circuit boards, and a fluorine film coated with an acrylic pressure-sensitive adhesive having 2-ethylhexyl acrylate as a main monomer is applied so that the adhesive surface is in contact with the circuit board. Arranged. Thereafter, using a hydraulic vacuum press, the condition during molding was a vacuum of 50 mm.
When thermocompression bonding was performed at Hg at a temperature of 170 ° C. for 100 minutes, a printed wiring board having smoothness was obtained.

[0018]

According to the present invention, the insulating concave portion adjacent to the circuit pattern portion is smoothed, so that even if the electrode slides on the surface, the shoulder of the circuit is not shaved, and the durability is improved. The shavings do not short-circuit adjacent circuit parts.

Furthermore, the wear of the sliding electrode is significantly reduced, and the durability of the electrode is also improved. Further, if the circuit pattern portion is plated as shown in FIG. 5, the durability is further improved, which is extremely preferable.

Further, as shown in FIG. 3, by performing thermocompression bonding using a release film with an adhesive, the resin in the prepreg can be smoothly formed on the circuit pattern portion without overflowing. Therefore, a buffing step is not required at all, which is very preferable in production.

[Brief description of the drawings]

FIG. 1 is a perspective view of a circuit board 5 used in the present invention.

FIG. 2 is a perspective view of a printed wiring board 20 having smoothness.

FIG. 3 is a schematic cross-sectional view showing a method for manufacturing a printed wiring board 21 having smoothness.

FIG. 4 is a configuration sectional view of a printed wiring board 21 having smoothness.

FIG. 5 is a sectional view showing the configuration of a printed wiring board 22 having smoothness.

[Explanation of symbols]

 Reference Signs List 3 circuit pattern portion 3 'circuit pattern portion 4 insulating concave portion 4' insulating concave portion 5 circuit board 5 'circuit board 6 plated portion 6' plated portion 7 through hole 7 'through hole 8 copper foil 10 prepreg 11 resin 16 release with adhesive Film 17 Adhesive surface 20 Printed wiring board having smoothness 21 Printed wiring board having smoothness 22 Printed wiring board having smoothness

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5E314 AA32 BB06 CC20 FF05 GG02 GG24 5E346 AA32 CC03 CC04 CC09 CC32 CC41 DD02 DD22 EE09 EE13 EE14 EE20 GG08 GG15 GG22 HH11 HH33

Claims (3)

[Claims] 1. A circuit pattern portion 3 based on an etching process and an insulating recess 4 are provided.
The prepreg 10 is laminated with the circuit board 5 provided with the adhesive, a release film 16 with an adhesive is disposed on the outside, and thermocompression-bonded, and the circuit pattern portion 3 and the surface are in contact with the insulating recess 4 through the through hole 7. A method for manufacturing a printed wiring board having smoothness, characterized by filling a resin 11 at a time. 2. The method for manufacturing a printed wiring board having smoothness according to claim 1, wherein said circuit pattern portion 3 is plated. 3. A thermocompression bonding method using a vacuum press.
A method for producing a printed wiring board having the described smoothness.