JPH09260850A - Manufacture of multilayered flex-rigid printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the manufacturing process of a multilayered flex-rigid printed wiring board and improve its drilling machinability, by applying a bonding agent containing specific components to the circuit surface of a rigid circuit board to dry thereafter the bonding agent and bring it into a semi-hardened state, and by heating and pressing this bonding-agent-bearing rigid circuit board and a cover-bearing flexible circuit board to integrate both the circuit boards with each other. SOLUTION: In a bonding-agent-bearing rigid circuit board, there is used an epoxy resin bonding agent containing respectively as a hardening agent, bis-p-aminobenzoate expressed by a chemical formula as shown (where m, n denote respectively integers of 1-12 and (m×n) is not larger than 12}, and as a hardening accelerator, an epoxy resin composite having boron trifluoride complex compound as its essential component. In this case, especially, the bonding-agent-bearing rigid circuit board is adjusted in its drying process to bring it into such a semi-hardened state that the flow of the bonding agent is made not larger than 0.5mm in the case of the heating and pressing of the conditions of 160 deg.C and 40kgf/cm<2> . Thereby, the manufacturing process of a multilayered flex-rigid printed wiring board is reduced and its drilling machinability can be made excellent.

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 multi-layer flex-rigid wiring board which is excellent in drilling workability and productivity used in electronic equipment and the like.

[0002]

2. Description of the Related Art Conventionally, a multilayer flex-rigid wiring board includes, for example, a flexible circuit board with a coverlay obtained by laminating a coverlay film on the circuit surface of a flexible circuit board, and a copper clad laminated circuit formed on only one side. The board and the rigid circuit surface are placed on the inside with an interlayer adhesive sheet in between, and heat and pressure are integrated to form a multilayer flex-rigid laminated board. Thereafter, post-processing such as drilling, plating, and outer layer circuit processing was performed to produce a multilayer flex-rigid wiring board.

[0003]

However, in the manufacturing process of the above-described Rex-rigid wiring board, an interlayer adhesive sheet is manufactured and the sheet is placed on the circuit surface of the copper clad laminate.
Since there is a temporary fixing process for fixing, there is a drawback that it is long and the productivity is poor. In addition, the interlayer adhesive sheet contains a flexible component such as rubber to form an adhesive film,
Due to this, the glass transition point is lower than that of ordinary epoxy resins, and there is a drawback that drill processing conditions are restricted.

The present invention has been made in order to solve the above-mentioned drawbacks, and an object of the present invention is to provide a flex-rigid wiring board which shortens the manufacturing process and is excellent in productivity such as drill workability.

[0005]

Means for Solving the Problems As a result of intensive studies aimed at achieving the above object, the present inventor has applied an adhesive containing a specific component described below to the circuit surface of a rigid circuit board The inventors have found that the above-mentioned object can be achieved by integrating a semi-cured rigid circuit board with an adhesive with a flexible circuit board with a coverlay by heating and pressurizing, and have completed the present invention.

That is, according to the present invention, a flexible circuit board with a cover lay, in which a circuit is formed and laminated with a polyimide cover lay film, is formed on a circuit surface of a rigid circuit board having a circuit formed on an adhesive surface to the flexible circuit board with the cover lay. A method of manufacturing a multilayer flex-rigid wiring board, in which a rigid circuit board with an adhesive is applied, dried, and semi-cured on the The adhesive in the rigid circuit board with the adhesive is (A) an epoxy resin and (B) a bis-p-aminobenzoate represented by the following formula as a curing agent.

[0007]

Embedded image (However, in the formula, m and n each represent an integer of 1 to 12, and m ×
n is 12 or less) and (C) is an epoxy resin composition containing a boron trifluoride complex compound as an essential component as a curing accelerator, and a method for producing a multilayer flex-rigid wiring board.

Hereinafter, the present invention will be described in detail.

As the cover lay film used in the present invention, a polyimide film can be used. For example, polypyromellitic imide film, polybiphenylimide film, polyketone imide film, polyamide imide film, polyether imide film. Examples include films.

As the flexible circuit board used in the present invention, the one using a polyimide film as a base material similar to the coverlay can be used. A cover lay is press-molded on the flexible circuit board to obtain a flexible circuit board with a cover lay.

The adhesive used in the present invention is (A) an epoxy resin, (B) a curing agent of bis-p-aminobenzoate represented by the above formula, and (C) a curing accelerator of boron trifluoride complex. An epoxy resin composition containing a compound as an essential component 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 epoxy resin, bisphenol F epoxy resin, novolak 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.

As the bis-p-aminobenzoate (B) which is a component of the adhesive, those represented by the above formula are used. As a specific compound, for example, CUA-4,
Erasmer 1000 (trade name, manufactured by Ihara Chemical Co., Ltd.) and the like can be mentioned, and these can be used alone or in combination of two or more kinds. The mixing ratio of the curing agent is such that the equivalent ratio of the epoxy group (x) of the epoxy resin (A) to the amino group (y) of the bis-p-aminobenzoate (B) [(x) /
(Y)] is preferably in the range of 0.3 to 1.5.
If the equivalent ratio is less than 0.3, curing will be insufficient, and if the equivalent ratio exceeds 1.5, many unreacted functional groups will remain, which is not preferable because the characteristics of the multilayer flex-rigid wiring board are deteriorated. Further, unless the object of the present invention is violated, this bis-p
Other curing agents can be used in addition to the aminobenzoate.

As the (C) boron trifluoride complex compound, which is another component of the adhesive, those used as usual curing accelerators can be used. Examples thereof include boron trifluoride monoethylamine complex, boron trifluoride piperidine complex, boron trifluoride triethanolamine complex, boron trifluoride benzylamine complex, boron trifluoride imidazole complex, etc., which may be used alone or 2 A mixture of two or more species can be used.

The interlayer adhesive used in the present invention contains an epoxy resin, bis-p-aminobenzoate and a boron trifluoride complex compound as essential components, but it is also necessary as long as it does not defeat the purpose of the present invention. Accordingly, a fine powder of an inorganic or organic filler, a pigment, a deterioration inhibitor, or the like can be added and blended.

The copper clad laminate used in the present invention is not particularly limited, but due to the characteristics of the multilayer flex-rigid wiring board,
A glass-based epoxy copper-clad laminate and a glass-based polyimide copper-clad laminate can be particularly preferably used. Then, these copper clad laminates are formed into a circuit to form a rigid circuit board, the surface of which is coated with the above-mentioned adhesive and a drying step, for example,
Adjust to a semi-cured state so that the flow of adhesive is 0.5 mm or less when heated and pressed under the conditions of 160 ° C and 40 kgf / cm ² . This flow adjustment of the adhesive is carried out for the purpose of facilitating the step of removing the unnecessary copper-clad laminate portion of the multilayer flex-rigid wiring board. The method of applying the adhesive is not particularly limited, and a roll coater,
A curtain coater, screen printing or 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.

A 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 semi-cured by a drying process, is superposed on a flexible circuit board with a cover lay and heated. Then, pressure integration is performed to obtain a multilayer flex-rigid laminated board, and then post-processing such as punching and circuit processing can be performed to manufacture a multilayer flex-rigid wiring board.

In the multilayer flex-rigid wiring board of the present invention, a flexible circuit board with a cover lay laminated with a cover lay is coated with an adhesive containing a specific component on the adhesive surface to the flexible circuit board, and a drying step is particularly preferable. By arranging a rigid circuit board with an adhesive that is adjusted to a semi-cured state so that the flow of the adhesive becomes 0.5 mm or less when heated and pressed under the conditions of 160 ° C and 40 kgf / cm ² by Shortened, drill workability,
It was possible to make it excellent in productivity.

[0019]

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 TLF of a flexible double-sided copper-clad laminate was prepared by using a polyimide film having a thickness of 25 μm as a base and laminating a copper foil having a thickness of 35 μm on both sides thereof with an adhesive agent. -W-521MR (manufactured by Toshiba Chemical Co.,
A flexible circuit board was made by forming a double-sided circuit on the product name) by the etched foil method.

The thickness of a 25 μm thick polyimide film
TFA-577 (trade name, manufactured by Toshiba Chemical Co., Ltd.), a polyimide film cover lay coated with an adhesive so as to have a thickness of 40 μm, dried and semi-cured, is applied to the flexible circuit board at a temperature of 160 ° C. and a pressure of 30 kg / cm ² , 40. A flexible circuit board (a) with a cover lay was produced by laminating under the press molding condition for a minute.

TLC-a glass epoxy resin double-sided copper-clad laminate in which copper foils having a thickness of 18 μm and a thickness of 35 μm are laminated on both sides of a prepreg having a thickness of 0.3 mm, which is obtained by impregnating glass cloth with an epoxy resin and semi-curing the resin. A single-sided circuit was formed on a 35 μm copper foil of W-551 (manufactured by Toshiba Chemical Co., Ltd.) to prepare a rigid circuit board (b).

Epoxy resin YDB-70 used as an adhesive raw material
0 (Toto Kasei Co., Ltd., trade name) 91 parts, CUA-4 (Ihara Chemical Co., trade name) 9 parts, and boron trifluoride monoethylamine 1 part were dissolved in ethyl cellosolve to obtain the adhesive (c). Manufactured. The adhesive (c) was printed by screen printing on the circuit surface of the rigid circuit board (b) to a thickness of 40 μm, and dried and semi-cured to obtain a rigid circuit board (d) with an adhesive. .

The flexible circuit board with a cover lay (a) and the rigid circuit board with an adhesive (d) are superposed on each other, and the temperature is 160 ° C. and the pressure is 40 by a pin lamination method.
A multilayer flex-rigid laminate (e) was produced by press-molding integrally under heating and pressure under the conditions of kg / cm ² and 120 minutes.

The multi-layer flex-rigid plate (e) thus obtained was perforated with an NC boring machine to make holes of 0.3 to 4.0 mmφ. Also, immerse the above laminated plate in copper pyrophosphate plating solution for about 5 hours, and apply about 25μ
m plating was formed. Further, a circuit was formed on the outer layer of this laminate by the etched foil method to manufacture a 6-layer flex-rigid wiring board (f).

Comparative Example As shown in the chart of FIG. 2, a carboxy-containing acrylonitrile-butadiene rubber, Nipol 1072 (trade name, manufactured by Nippon Zeon Co., Ltd.) was added to the adhesive (c) produced in the example in a solid content ratio of 1: 1. To prepare an adhesive (g). The adhesive (g) was applied to a polypropylene film having a thickness of 40 μm by a roll coater, dried and semi-cured to prepare an adhesive film (h) having an adhesive thickness of 40 μm. This adhesive film (h) was cut into a predetermined size to obtain an interlayer adhesive sheet (i). This interlayer adhesive sheet (i) is temporarily attached to the circuit surface of the rigid circuit board (b) prepared in the embodiment by passing it through a heat roll, and the rigid circuit board with the interlayer adhesive sheet (j).
And

A flexible circuit board with a cover lay (a) made in the example is overlaid with the rigid circuit board with an interlayer adhesive sheet (j) from which a polypropylene film as a protective film has been peeled off, and the same as in the example. A multilayer flex-rigid laminate (k) was produced by heating and pressurizing under the conditions. Subsequently, drilling, plating, and outer layer circuit formation were performed in the same manner as in the example to manufacture a 6-layer flex-rigid wiring board (1).

With respect to the 6-layer flex-rigid wiring boards manufactured in Examples and Comparative Examples, solder heat resistance and smear generation rate during drilling were tested. The results are shown in Table 1. The multilayer flex-rigid wiring board of the present invention retains the conventional solder heat resistance and is excellent in the smear occurrence rate to a large extent, and the effect of the present invention can be confirmed.

[0029]

[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.

[0030]

As is apparent 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 prevented without lowering the solder heat resistance. It was possible to manufacture an excellent and reliable multilayer flex-rigid wiring board.

[Brief description of 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 flexible circuit board with a cover lay in which a circuit is formed and a polyimide cover lay film is laminated, and an adhesive is applied to the circuit surface of a rigid circuit board with a circuit formed on the adhesive surface with the flexible circuit board with the cover lay. A method of manufacturing a multilayer flex-rigid wiring board, which comprises applying, drying, and arranging a semi-cured rigid circuit board with an adhesive, forming a multilayer flex-rigid laminated board by heat and pressure integration, and post-processing. The adhesive in the rigid circuit board with the adhesive is bis-p-aminobenzoate represented by the following formula as (A) epoxy resin and (B) curing agent. (However, in the formula, m and n each represent an integer of 1 to 12, and m ×
n is 12 or less) and (C) is an epoxy resin composition containing a boron trifluoride complex compound as an essential component as a curing accelerator, and a method for producing a multilayer flex-rigid wiring board. 2. The multilayer flex-rigid wiring board according to claim 1, wherein the flow of the adhesive in the rigid circuit board with the adhesive is 0.5 mm or less when heating and pressurizing under conditions of 160 ° C. and 40 kgf / cm ² . Production method.