JPH08148836A - Multilayered flexrigid wiring board - Google Patents

Abstract

PURPOSE: To improve adhesion between layers, and prevent exfoliation due to thermal shock or the like during the post-working process. CONSTITUTION: A circuit 1c is formed on a double-sided flexible board formed by laminating copper foils 1b on both surfaces of a polyimide film 1a, and a flexible printed board 1 is obtained. Adhesive agent is spread, dried and semicured, and a coverlay film 2 is obtained. A flexible circuit board provided with a cover lay is formed by laminating the coverlay films 2 on both surfaces of the flexible circuit board 1. A circuit is formed on a copper foil 4c 35μm thick on a double-sided copper clad lamination board. By treatment is sodium hydroxide aqueous solution for 3 minutes, a rough surface circuit 4d is obtained, and a circuit board 4 is formed. An interlayer adhesive sheet 3 is stuck on the circuit forming surface, and stacked on the flexible circuit board 1 provided with the coverlay film 2. By heat.pressing and integration, a multilayered flexrigid lamination board 5 is formed. A circuit 6a is formed on the outer layer. Thereby a board which is excellent in adhesion and free from exfoliation can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is used in electronic devices and the like.
The present invention relates to a multilayer flex-rigid wiring board having excellent adhesion between layers.

[0002]

2. Description of the Related Art Conventionally, a multilayer flex-rigid wiring board is manufactured, for example, by laminating a coverlay film on a circuit-formed flexible circuit board, stacking an interlayer adhesive sheet on the laminated flexible circuit board, and further forming a circuit on only one side. The laminated laminates are stacked with the circuit surface inside (facing the interlayer adhesive sheet) and heated.
Pressurize and integrate. After that, post-processing such as drilling, plating, and outer layer circuit processing is performed to manufacture a multilayer flex-rigid wiring board.

However, the adhesion between the circuit surface of the copper clad laminate and the interlayer adhesive sheet is very poor, and peeling occurs at the interface between the circuit surface and the interlayer adhesive sheet due to thermal shock during the post-processing step. There was a drawback.

[0004]

Since the present invention has been made to solve the above-mentioned drawbacks, it has excellent adhesion between layers, and the circuit surface and the interlayer adhesive sheet due to thermal shock or the like during the post-processing step. The present invention is intended to provide a highly reliable multilayer flex-rigid wiring board which is free from peeling at the interface.

[0005]

DISCLOSURE OF THE INVENTION As a result of intensive studies to achieve the above object, the present invention can achieve the above object by roughening the smooth surface of the circuit of the copper clad laminate. The present invention has been completed and the present invention has been completed.

That is, according to the present invention, an interlayer adhesive sheet is superposed on a flexible circuit board on which a circuit is formed and a coverlay film is laminated, and a circuit-formed copper clad laminate is arranged on the adhesive surface with the interlayer adhesive sheet. In the multilayer flex-rigid wiring board which is subjected to post-processing after heating and pressure integration, the copper-clad laminate has a circuit surface roughened. It is a wiring board.

The present invention will be described in detail below.

As the coverlay film used in the present invention, an imide 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 interlayer adhesive sheet used in the present invention,
There is no particular limitation as long as it satisfies the characteristics for a multilayer flex-rigid wiring board. Examples include interlayer adhesive sheets of modified acrylic resin type, acrylonitrile butadiene rubber / epoxy resin type, carboxy group-containing acrylonitrile butadiene rubber / phenolic resin type and the like.

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 polyimide copper-clad laminate and a glass-based polyimide copper-clad laminate can be particularly preferably used. These copper-clad laminates are obtained by subjecting the copper surface on which a circuit has been formed to a roughening treatment before heating and pressure integration.

The copper-clad laminate, which has been subjected to a surface roughening treatment in advance on the copper surface on which the circuit has been formed as described above, is laminated with an interlayer adhesive sheet and a flexible circuit board with a coverlay, and integrated by heating and pressurization to form a multilayer flex-rigid laminate. The board can be obtained and then post-processed such as drilling and circuit processing to produce a multilayer flex-rigid wiring board.

[0012]

The multi-layer flex-rigid wiring board of the present invention comprises a flexible circuit board laminated with a coverlay film, an interlayer adhesive sheet, and a copper-clad laminate, which are superposed on each other by heating and pressurizing them. By preliminarily roughening the copper surface, it was possible to obtain excellent adhesion at the interface with the interlayer adhesive sheet.

[0013]

EXAMPLES The present invention will be specifically described 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”.

Example 1 A multilayer flex-rigid wiring board was manufactured through the steps of FIGS. 1 (a) to 1 (h).

FIG. 1 (a) A double-sided flexible substrate TLF-W-521MR (Toshiba Chemical Co., Ltd.) in which a polyimide film 1a having a thickness of 25 μm is used as a base, and a copper foil 1b having a thickness of 35 μm is laminated on both sides thereof with an adhesive. (Product name, manufactured by the company) was prepared.

FIG. 1 (b) A flexible circuit board 1 was prepared by forming a circuit 1c on the above-mentioned double-sided flexible substrate by the etched foil method.

FIG. 1 (c) Acrylonitrile butadiene rubber Nipol 1432J (manufactured by Nippon Zeon Co., Ltd.)
40 parts, epoxy resin YD-7011 (manufactured by Tohto Kasei Co., trade name epoxy equivalent 470) 58 parts, dicyandiamide 1.8
Part, and 0.2 parts of imidazole 2E4MZ (trade name, manufactured by Shikoku Kasei Co., Ltd.) are dissolved in a mixed solvent of methyl ethyl ketone and toluene to produce an adhesive, and the adhesive is 25 μm in thickness.
A cover lay film was prepared by coating and drying and semi-curing a polyimide film of apical AH (trade name, manufactured by Kanegafuchi Chemical Industry Co., Ltd.) with a roll coater to a thickness of 35 μm. This coverlay film 2 was laminated on both sides of the flexible circuit board 1 under conditions of a temperature of 165 ° C. and a pressure of 40 kg / cm 2 for 1 hour to prepare a flexible circuit board with a coverlay.

FIG. 1 (d) Glass cloth impregnated with epoxy resin and semi-cured, 0.3 mm thick prepreg 4a is laminated on both sides with 18 μm thick copper foil 4b and 35 μm thick copper foil 4c. Double-sided copper clad laminate TLC-W-55
1 (manufactured by Toshiba Chemical Co., Ltd., trade name) was prepared.

FIG. 1 (e) Thickness of the double-sided copper clad laminate 35
A circuit is formed on a copper foil 4c of μm and treated with an aqueous solution of sodium hydroxide having a concentration of 30g / l for 3 minutes to form a roughened circuit 4d.
I made a circuit board 4.

FIG. 1 (f) An adhesive sheet having a thickness of 50 μm, Pyrax LF-200 (trade name, manufactured by Dupont Co., Ltd.) was cut into a predetermined size to obtain an interlayer adhesive sheet. The interlayer adhesive sheet 3 was attached to the circuit forming surface of the circuit board 4.

FIG. 1 (g) The circuit board 4 to which the interlayer adhesive sheet 3 is attached and the flexible circuit board 1 with the coverlay film 2 are superposed, and the temperature is 180 ° C. and the pressure is 60 kg / cm by the pin lamination method. ^2. Heat and pressure were integrated under the conditions of time 120 minutes to make a multilayer flex-rigid laminate 5.

FIG. 1 (h) The multi-layer flex-rigid laminate plate 5 was perforated (not shown) with a diameter of 0.3 to 4.0 mm using an NC boring machine. Further, the laminated plate 5 was immersed in a copper pyrophosphate plating solution for about 5 hours to form a plating (not shown) of about 25 μm on the through holes and the surface. Further, a circuit 6a was formed on the outer layer of the laminate 5 by the etched foil method to manufacture a 6-layer flex-rigid wiring board 6.

Comparative Example In all of the examples, except that the step of FIG. 1 (e), that is, the step of roughening treatment with a sodium hydroxide aqueous solution on the double-sided copper clad laminate was not performed, 6 A layer flex rigid wiring board was manufactured.

The 6-layer flex-rigid wiring boards manufactured in Examples and Comparative Examples were tested for solder heat resistance after humidification. The results are shown in Table 1. The present invention has excellent interlayer adhesion, and the effects of the present invention could be confirmed.

[0025]

[Table 1] * 1: The state was observed when floated in a solder bath at 260 ° C for 60 seconds. ○: No abnormality, ×: Delamination occurred

[0026]

As is apparent from the above description and Table 1, the multilayer flex-rigid wiring board of the present invention is excellent in the adhesion between layers and has a circuit surface and an interlayer adhesive sheet due to thermal shock during the post-processing step. There is no peeling at the interface, and it is highly reliable.

[Brief description of drawings]

1A to 1F are schematic cross-sectional views for explaining a manufacturing process of a multilayer flex-rigid wiring board of the present invention.

[Explanation of symbols]

 1 flexible circuit board 2 coverlay film 3 interlayer adhesive sheet 4 circuit board 4d roughened circuit 5 flex-rigid laminated board 6 flex-rigid wiring board

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[Procedure amendment]

[Submission date] March 3, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

1 (a) to 1 ( h ) are schematic cross-sectional views for explaining a manufacturing process of a multilayer flex-rigid wiring board of the present invention.

Claims (1)

[Claims] 1. A flexible circuit board on which a circuit is formed and a cover lay film is laminated is laminated with an interlayer adhesive sheet, and a copper clad laminate having a circuit formed on the adhesive surface with the interlayer adhesive sheet is arranged and heated. After pressure integration
In a multi-layer flex rigid wiring board that is post-processed,
A multilayer flex-rigid wiring board, characterized in that the circuit surface of the copper-clad laminate is roughened.