JPH1027966A - Manufacture of multi-layer flexible-rigid wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate operation in multi-layer pressing by coating a flexible circuit board with solder resist and setting the resist, then coating a circuit surface of a rigid circuit board with adhesive and semi-setting the adhesive, arranging the adhesive-coated surface on the solder-resist coated surface, and heat-pressing the surfaces. SOLUTION: A flexible circuit board (a) is constructed by forming a circuit on a flexible board, both surfaces of which are laminated with copper, and solder resist for flexible circuit board is printed and set, to obtain a flexible circuit board (b) with the solder resist. A rigid circuit board (c) is obtained by forming a single-side circuit on a copper foil of a double-side glass epoxy- resin copper-laminated board, where both surfaces of a prepreg, obtained by soaking a glass cloth with epoxy resin and setting the glass cloth, are laminated with copper foils. A rigid circuit board (e) with adhesive is obtained by printing adhesive (d) on the circuit surface of the rigid circuit board (c) drying the adhesive d to semi-set the adhesive. The flexible and rigid circuit boards are overlapped and heat-pressed. By controlling the semi-set condition of the adhesive, operation in pressing can be simplified.

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 multilayer flex-rigid wiring board used for electronic equipment and the like, and particularly to a method excellent in drilling workability and productivity.

[0002]

2. Description of the Related Art Conventionally, a multilayer flex-rigid wiring board is composed of, for example, a flexible circuit board with a coverlay obtained by laminating a coverlay film on a circuit surface of a flexible circuit board on which a circuit is formed, and one side of a copper-clad laminate. A rigid circuit board formed only on the circuit is overlapped with an interlayer adhesive sheet with the rigid circuit surface inside, and integrated by heating and pressing to produce a multilayer flex-rigid laminate.
Thereafter, post-processing such as drilling, plating, and outer layer circuit processing was performed to produce a multilayer flex-rigid wiring board.

[0003]

However, the above-mentioned manufacturing process of the multilayer flex-rigid wiring board includes a process of laminating a coverlay film, a process of manufacturing an interlayer adhesive sheet, and disposing the sheet on the circuit surface of the copper-clad laminate. There is a drawback that it is long and has poor productivity because of the provisional fixing step and the like. In addition, the adhesive of the coverlay film and the adhesive of the interlayer adhesive sheet contain a flexible component such as rubber in order to form the adhesive into a film, and due to this, the glass transition point is higher than that of a normal epoxy resin. It is low and has the drawback of restricting drilling conditions.

The present invention has been made to solve the above-mentioned drawbacks, and aims to provide a multilayer flex-rigid wiring board which is excellent in productivity such as drilling workability while shortening a manufacturing process. .

[0005]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have arranged a flexible circuit board with solder resist applied and cured with solder resist in an inner layer, and The adhesive containing the components is applied to the circuit surface of the rigid circuit board, dried and semi-cured, and the rigid circuit board with the adhesive is integrated by heating and pressurizing with the flexible circuit board with the solder resist. It has been found that the object of the present invention can be achieved, and the present invention has been completed.

That is, the present invention provides a step of applying and curing a solder resist on a flexible circuit board on which a circuit is formed to obtain a flexible circuit board with a solder resist, and a method of forming an adhesive on a circuit surface of a rigid circuit board on which a circuit is formed. Coating, drying, and semi-curing to obtain a rigid circuit board with an adhesive, and disposing the adhesive-coated surface of the rigid circuit board with the adhesive on the solder resist-coated surface of the flexible circuit board with the solder resist, and heating. A method for manufacturing a multilayer flex-rigid wiring board, comprising: a step of forming a multilayer flex-rigid laminate by pressure integration; and a step of post-processing the multilayer flex-rigid laminate. Further, the adhesive is (A) an epoxy resin,
This is a method for producing a multilayer flex-rigid wiring board which is an epoxy resin composition containing (B) a novolak type phenol resin and (C) an imidazole derivative as essential components.

Hereinafter, the present invention will be described in detail.

[0008] As the solder resist used in the present invention, a commercially available solder resist for a flexible circuit board is widely used. As a specific example, NPR-5
(Trade name, manufactured by Nippon Polytech), SR-29 (trade name, manufactured by Tamura Kaken), CF-30G (trade name, manufactured by Shikoku Chemicals), and the like.

As the flexible circuit board used in the present invention, a flexible circuit board based on a polyimide film can be used. A solder resist is applied to a flexible circuit board having a circuit surface on both sides or one side and cured to obtain a flexible circuit board with a solder resist.

As the interlayer adhesive used in the present invention,
An epoxy resin composition containing (A) an epoxy resin, (B) a novolak-type phenol resin, and (C) an imidazole derivative as essential components can be used.

As the epoxy resin (A) used herein, an epoxy resin having two or more epoxy groups in one molecule can be used. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolak type epoxy resin Epoxy resins, glycidyl-type ether epoxy resins such as bromides thereof, glycidyl ester-type epoxy resins, glycidylamine-type epoxy resins, alicyclic epoxy resins, heterocyclic epoxy resins, and the like. A mixture of more than one species can be used.

The novolak type phenol resin (B) which is a component of the adhesive has at least two phenolic hydroxyl groups in the molecule, and is a phenol novolak resin, a cresol novolak resin, a bisphenol A novolak resin, a cyclocyclic Including terpene diphenol novolak resins and modified resins thereof,
These can be used alone or in combination of two or more.

The imidazole derivatives (C) which are other components of the adhesive include 2-methylimidazole and 2-ethyl-4
-Methylimidazole, 2-undecylimidazole, 2-
Phenylimidazole, 1-cyanoethyl-2-ethyl-4-
Methylimidazole, etc., which may be used alone or
A mixture of more than one species can be used.

The interlayer adhesive used in the present invention contains the above-mentioned epoxy resin, novolak-type phenol resin and imidazole derivative as essential components, but as long as the object of the present invention is not adversely affected, and if necessary, fine powder And inorganic or organic fillers, pigments, deterioration inhibitors and the like.

The copper-clad laminate for the rigid circuit board used in the present invention is not particularly limited. However, due to the characteristics of the multilayer flex-rigid wiring board, glass-based epoxy copper-clad laminate, glass-based polyimide copper-clad laminate A plate or the like can be particularly preferably used. These copper-clad laminates are formed into a circuit to form a rigid circuit board, and the surface is coated with the above-mentioned adhesive and adjusted to a semi-cured state by a drying process. The adjustment of the degree of curing of the adhesive is performed for the purpose of facilitating the operation at the time of multilayer press of the multilayer flex-rigid wiring board.
Also, there is no particular limitation on the method of applying the adhesive,
Any of a roll coater, curtain coater, screen printing and the like may be used. The thickness of the adhesive must be such that it satisfies the circuit embedding property, the total thickness, etc., and should be adjusted according to the copper foil thickness, total thickness, etc. of the copper-clad laminate. I can do it.

The above-described rigid circuit board with an adhesive, in which an adhesive containing a specific component is applied to the circuit forming surface and the adhesive is in a semi-cured state by a drying step, is overlapped with a flexible circuit board with a solder resist and heated. Then, the resultant is press-integrated to obtain a multilayer flex-rigid laminated board, which is then subjected to post-processing such as drilling and circuit processing to produce a multilayer flex-rigid wiring board.

In the multilayer flex-rigid wiring board of the present invention, an adhesive containing a specific component is applied to a bonding surface of the flexible circuit board with a solder resist, which is coated and cured with the solder resist, and dried. By arranging the rigid circuit board with the adhesive adjusted to a semi-cured state by the process, the manufacturing process was shortened, and the drill workability and the productivity were excellent.

[0018]

EXAMPLES The present invention will be described specifically with reference to examples, but the present invention is not limited to these examples. In the following Examples and Comparative Examples, “parts” means “parts by weight”. FIG. 1 is a flowchart showing a manufacturing process of an example, and FIG. 2 is a flowchart showing a manufacturing process of a comparative example.

EXAMPLE As shown in the chart of FIG. 1, a TFL of a flexible double-sided copper-clad laminate having a polyimide film having a thickness of 25 μm as a base and a copper foil having a thickness of 35 μm laminated on both sides thereof via an adhesive. -W-521MR (manufactured by Toshiba Chemical Corporation,
A circuit was formed by the etched foil method on the trade name) to produce a flexible circuit board (a). The flexible circuit board is provided with a solder resist CF for the flexible circuit board.
-30G (trade name, manufactured by Shikoku Chemicals Co., Ltd.) was printed by screen printing so as to have a thickness of 20 μm, and cured to prepare a flexible circuit board (b) with a solder resist. Glass cloth impregnated with epoxy resin, semi-cured 0.3 mm thick prepreg, 18 μm thick on both sides
A single-sided circuit is formed on a 35 μm copper foil of TLC-W-551 (trade name, manufactured by Toshiba Chemical Co., Ltd.), a glass-epoxy resin double-sided copper-clad laminate obtained by laminating a copper foil having a thickness of 35 μm and a rigid circuit board (c). made.

85.5 parts of epoxy resin YDB-700 (trade name, manufactured by Toto Kasei), cresol novolak resin CRG
-950 (manufactured by Showa Polymer Co., Ltd., 14.2 parts) and 2E4MZ of imidazole derivative (manufactured by Shikoku Chemicals, Inc.)
0.3 part was dissolved in ethyl cellosolve to prepare an adhesive (d). This adhesive (d) was printed on the circuit surface of the rigid circuit board (c) by screen printing so as to have a thickness of 50 μm, and dried and semi-cured to obtain a rigid circuit board (e) with an adhesive.

The flexible circuit board (b) with the solder resist and the rigid circuit board (e) with the adhesive are overlapped, and the temperature is 160 ° C. by the pin lamination method.
Multi-layer flex-rigid laminate (f) by press-forming integrally under heat and pressure under conditions of pressure of 40 kgf / cm ² and 120 minutes
made.

The multilayer flex-rigid laminate (f) thus obtained was perforated with a diameter of 0.3 to 4.0 mmφ using an NC perforator. Further, the laminate (f) was immersed in a copper pyrophosphate plating solution for about 5 hours to form a plating of about 25 μm on the through-hole portion and the surface. Further, a circuit is formed on the outer layer of the laminate (f) by an etched foil method.
A six-layer flex-rigid wiring board (g) was manufactured.

Comparative Example As shown in the chart of FIG. 2, an adhesive was applied to a polyimide film having a thickness of 25 μm to a thickness of 40 μm, dried and semi-cured to form a coverlay TFA-577 (Toshiba Chemical). Company name, trade name)
A flexible circuit board (h) with a cover lay was fabricated by laminating the same flexible circuit board (a) as in the example under the conditions of a temperature of 160 ° C., a pressure of 30 kgf / cm ² and 40 minutes.

The adhesive (d) prepared in the examples and Nipol 10 of carboxy-containing acrylonitrile-butadiene rubber were used.
72 (manufactured by Zeon Corporation, trade name) in a ratio of solid content of 1: 1 to produce an adhesive (i). This adhesive (i) is applied to a polypropylene film having a thickness of 40 μm with a roll coater, dried and semi-cured, and the adhesive thickness is 40 μm.
A polypropylene film (j) was prepared. This adhesive film (j) was cut into a predetermined size to obtain an interlayer adhesive sheet (k). This interlayer adhesive sheet (k) was temporarily attached to a circuit surface of the same rigid circuit board (c) as that prepared in the example through a heat roll to obtain a rigid circuit board (1) with an interlayer adhesive sheet.

Flexible circuit board with coverlay (h)
And a rigid circuit board (1) with an interlayer adhesive sheet from which a polypropylene film as a protective film has been peeled off, and laminated under heating and pressure under the same conditions as in the example, and a multilayer flex rigid laminate (m) made. Subsequently, drilling, plating, and formation of an outer layer circuit were performed in the same manner as in the example to manufacture a six-layer flex-rigid wiring board (n).

With respect to the six-layer flex-rigid wiring boards manufactured in Examples and Comparative Examples, tests were conducted on the heat resistance of solder and the occurrence of smear during drilling. The results are shown in Table 1. The multilayer flex-rigid wiring board of the present invention has the same solder heat resistance as that of the conventional one, while the smear occurrence rate is remarkably small and excellent, and the effect of the present invention could be confirmed.

[0027]

[Table 1] * 1: The state when immersed in a solder bath after drying at 80 ° C for 30 minutes was observed. *: No abnormality * 2: Drill feed speed 1.5 m / min, rotation speed 60,000 rpm * 3: Drill feed speed 3.0 m / min, rotation speed 60,000 rpm.

[0028]

As is clear from the above description and Table 1, according to the method for manufacturing a multilayer flex-rigid wiring board of the present invention, the manufacturing process is shortened and the drilling workability is reduced without lowering the solder heat resistance. A highly reliable multilayer flex-rigid wiring board with excellent reliability can be manufactured.

[Brief description of the drawings]

FIG. 1 is a flowchart for explaining a manufacturing process of a multilayer flex-rigid wiring board of the present invention.

FIG. 2 is a flowchart for explaining a manufacturing process of a conventional multilayer flex-rigid wiring board.

Claims (2)

[Claims] 1. A step of applying and curing a solder resist on a flexible circuit board on which a circuit is formed to obtain a flexible circuit board with a solder resist, and applying and drying an adhesive on a circuit surface of the rigid circuit board on which the circuit is formed. Obtaining a rigid circuit board with an adhesive by semi-curing, and disposing the adhesive-coated surface of the rigid circuit board with the adhesive on the solder resist-coated surface of the flexible circuit board with the solder resist, and integrating by heating and pressing. Forming a multilayer flex-rigid laminate by post-processing the multilayer flex-rigid laminate, and post-processing the multilayer flex-rigid laminate. 2. The adhesive in a rigid circuit board with an adhesive is an epoxy resin composition comprising (A) an epoxy resin, (B) a novolak-type phenol resin, and (C) an imidazole derivative as essential components. Method for manufacturing a multilayer flex-rigid wiring board.