JPH10173342A - Multilayer flexible rigid wiring board and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce production cost by forming both a protective layer for a flexible conductor circuit and a layer for bonding a rigid printed wiring board by applying a liquid material. SOLUTION: A conductor circuit 9 is formed as an inner layer of a flexible wiring board 1, and then a plating resist 5 is applied by printing to the surface of the rear of the flexible wiring board 1 and dried. Subsequently, a circuit is formed on copper clad plate, laminated with a copper foil on the opposite sides thereof, thus constituting a rigid printed wiring board. On the other hand, a liquid adhesive is produced of an epoxy resin, imidazole dielectric, etc. The rigid printed wiring board is screen printed, on the circuit plane thereof except the unwonted part, with the liquid adhesive, and then it is dried and semicured to produce a rigid printed wiring board 4 with adhesive. Finally, the rigid printed wiring board 4 is laminated with an adhesive on the flexible wiring board 1 with a plating resist and hot pressed integrally for forming a multilayer flex rigid printed laminated plate which is then subjected to a through-hole plating 7 and then a conductor patterning 8 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called multilayer flex-rigid printed circuit board having a flexible portion and a method of manufacturing the same.

[0002]

2. Description of the Related Art An example of a typical multilayer flex-rigid wiring board having a conventional structure is shown in FIG. In the figure, the range A is a rigid portion, and the range B is a bendable flexible portion. The conductor circuit 9 of the flexible wiring board 1 in the flexible portion B is covered with a coverlay film 2 with an adhesive for protection.

The protective coating with the coverlay film 2 needs to be previously performed by lamination molding or hot roll pressing on the flexible wiring board 1 serving as the inner layer board of the multilayer flex-rigid wiring board. It takes.

Further, in the rigid part A, reference numeral 3
The flexible wiring board 1 and the rigid wiring board 4 are bonded or laminated by an adhesive bonding sheet or prepreg indicated by the following formula. In the flexible portion B where the flexible wiring board 1 is exposed, the bonding sheet or the prepreg 3 is partially removed. Then, multilayer molding is performed in a structure that avoids adhesion between the flexible wiring board 1 and unnecessary portions of the rigid wiring board 4 on both sides. Reference numeral 7 denotes a through hole processed after the multilayer molding.

As described above, the conventional multilayer flex-rigid wiring board uses a coverlay film for protecting the conductor circuit of the flexible wiring board, and a bonding sheet or prepreg sheet material for bonding. It costs money to make and incurs high costs for the materials used.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems, and it is an object of the present invention to provide a multilayer flex-rigid wiring board having a structure that does not use a sheet-like material, which causes an increase in cost. The manufacturing method is provided.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and uses a liquid material as a sheet-like material, which is a factor of high cost, to form a laminate for forming a protective layer using a coverlay film. This problem has been solved by reducing the production cost by adopting a process of directly applying a liquid material instead of using hot roll press bonding and further using an adhesive bonding sheet or prepreg.

That is, in the multilayer flex-rigid wiring board of the present invention, a rigid printed wiring board is adhered and laminated on a part or all of both sides of a flexible board having a conductor circuit and its protective layer as an inner layer board. In a multilayer flex-rigid wiring board having the above-described conductive circuit and a part of the protective layer also in a portion that can be bent, both the protective layer of the flexible conductive circuit and the adhesive layer for bonding the rigid printed wiring board are made of a liquid material. Characterized by being formed by application using

Further, the method of the present invention for manufacturing a multilayer flex-rigid wiring board according to the present invention comprises the steps of: forming a protective layer of a flexible conductive circuit including a bendable portion by coating a liquid material; Forming a bonding layer by coating a liquid material on the protective layer or the rigid printed wiring board in a portion to be laminated with the rigid printed wiring board, and forming a flexible substrate and a rigid wiring board after the formation of the bonding layer. And laminating and bonding.

Hereinafter, the present invention will be described in detail.

As the flexible board used in the present invention, a flexible printed board which can be used conventionally can be used as it is. That is, a film based on a polypyromellitic imide-based film, a polybiphenylimide-based film, a polyketone imide-based film, a polyamide imide-based film, a polyetherimide-based film, or the like can be used. For the rigid printed wiring board, a rigid printed wiring board material, a multilayer printed wiring board material, or the like which can be used conventionally can be used as it is. That is, a glass-base epoxy copper-clad laminate, a glass-base polyimide copper-clad laminate, and the like can be particularly preferably used.

As the liquid material used for the protective layer of the flexible conductive circuit in the present invention, a solder resist usually used for a printed wiring board is suitable. Specific examples include an epoxy resin solder resist and a polyimide liquid cover coat material. Further, as the liquid adhesive for bonding the flexible printed circuit board on which the protective layer is formed and the rigid printed wiring board, an adhesive mainly composed of an epoxy resin is preferable. Specific examples include an epoxy resin composition containing an epoxy resin, a novolak-type phenol resin, and an imitasesol superior conductor as essential components.
A printing method, a roll coater method, a curtain coater method, or the like can be applied as a method for applying these two liquid materials.

FIG. 1 shows the structure of a multilayer flex-rigid wiring board according to the present invention. In FIG. 3 showing the conventional structure, the protective layer of the conductor circuit of the flexible wiring board 1 is formed by a coverlay film 2 of a film with an adhesive, and the flexible printed circuit board 1 covered with the coverlay film 2 is rigid-printed. The bonding with the wiring board 4 has been performed using a bonding sheet or a prepreg 3. On the other hand, in the present invention, the protective layer of the conductor circuit of the flexible wiring board 1 is the layer 5 coated with a solder resist (liquid material), and the flexible printed board 1 and the rigid printed wiring board 4 The adhesive layer is a layer 6 of a liquid adhesive mainly containing an epoxy resin.

[0014]

According to the multilayer flex-rigid wiring board of the present invention and the method of manufacturing the same, the number of coverlay films that would have conventionally been two in the case of a six-layer board is reduced, and the material of the bonding sheet for bonding is good. The rubber-containing interlayer adhesive sheet used is an adhesive layer 6 mainly composed of an epoxy resin.
In this case, drilling of a through-hole with a drill becomes easy, the shape of the through-hole plating 7 is good, and the generation of cracks due to stress during heating can be suppressed. In addition, since the number of lamination presses is reduced from two to one, a multilayer flex-rigid wiring board with small dimensional change in the process and good dimensional stability can be manufactured.

By directly applying a liquid material to the production cost of the coverlay film or the interlayer adhesive sheet material from the raw material and the auxiliary material cost, the cost required for the production of the sheet material can be reduced, and the multilayer flex-rigid wiring having a lower product cost than the conventional product. Boards can be manufactured.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described with reference to the drawings, but the present invention is not limited by these embodiments.

Embodiment FIG. 2 is a view for explaining an embodiment of a method for manufacturing a multilayer flex-rigid wiring board according to the present invention.

First, as shown in FIG. 2A, a conductor circuit 9 as an inner layer was formed on the flexible substrate 1 by an etched foil method. A plating resist 5 is applied to the front and back surfaces of the circuit-formed flexible wiring board so as to have a thickness of 40 μm by a printing method and dried. When a part of the flexible conductor is used as a connection terminal, the coating is applied so that the part is exposed.

Next, TLC-W-5 of an epoxy double-sided copper-clad laminate obtained by laminating a copper foil having a thickness of 18 μm and a thickness of 35 μm was used.
A circuit was formed on a 51 (manufactured by Toshiba Chemical Co., trade name) 35 μm copper foil to make a rigid printed wiring board. On the other hand, an epoxy resin YDB-700 (trade name, manufactured by Toto Kasei Co., Ltd.) 85.5
A liquid adhesive was prepared by dissolving 14.2 parts of CRG-951 (trade name, manufactured by Showa Polymer Co., Ltd.) of cresol novolak resin and 0.3 part of 2E4MZ of imidazole derivative (trade name, manufactured by Shikoku Chemicals) in ethyl cellosolve. . This liquid adhesive is applied to the circuit surface of the rigid printed wiring board excluding an unnecessary area by a screen printing method to a thickness of 40%.
μm, and dried and semi-cured to obtain a rigid printed wiring board with an adhesive.

As shown in FIG. 2B, the rigid printed wiring board 4 with the adhesive and the flexible board 1 with the plating resist are superposed on each other, and the temperature is 160.degree.
A multilayer flex-rigid laminate was formed by heating and pressing integrally under the conditions of kg / cm ² and 120 minutes.

After laminating and bonding, as shown in FIG. 2C, drilling, through-hole plating 7, and a conductor pattern 8 are formed on the outer layer copper foil. The multilayer flex-rigid wiring board of the present invention shown in FIG.

As described above, by manufacturing using liquid materials in place of the sheet-like auxiliary materials used in the conventional structure, it has become possible to greatly reduce costs. Moreover, the multilayer flex-rigid wiring board manufactured by this manufacturing method has electrical characteristics and workability equal to or higher than those of the conventional configuration.

[0023]

As is apparent from the above description, according to the multilayer flex-rigid wiring board of the present invention and the method of manufacturing the same, the lamination press of the coverlay sheet for protecting the conductor circuit on the front and back of the flexible wiring board can be omitted. By using a liquid material instead of a sheet material, a significant cost reduction has become possible. Further, a multilayer flex-rigid wiring board having excellent workability, high through-hole connection reliability, and good electric characteristics can be manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing the structure of a multilayer flex-rigid wiring board according to the present invention.

2 (a) to 2 (c) are schematic cross-sectional views for explaining a manufacturing process of a multilayer flex-rigid wiring board according to the present invention. FIG. (B) shows a step of laminating and bonding using a liquid adhesive, and (c) shows a post-processing step such as a through hole.

FIG. 3 is a schematic sectional view showing the structure of a multilayer flex-rigid wiring board according to a conventional manufacturing method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Flexible wiring board 2 Coverlay film 3 Adhesive sheet material (bonding sheet, prepreg, etc.) 4 Rigid printed wiring board 5 Liquid material (solder resist) 6 Liquid adhesive 7 Through-hole plating 8 Outer layer conductor pattern 9 Conductor circuit

Claims (2)

[Claims] A flexible printed circuit board having a conductive circuit and a protective layer thereof is used as an inner layer board, and a rigid printed wiring board is adhesively laminated on a part or all of both surfaces thereof, and the above-mentioned conductor is also provided on a part of the flexible board which can be bent. In a multilayer flex-rigid wiring board with a circuit and a part of its protective layer, both the protective layer of the flexible conductive circuit and the adhesive layer for bonding the rigid printed wiring board are formed by applying a liquid material. Characteristic multilayer flex-rigid wiring board. 2. A flexible printed circuit board having a conductive circuit and its protective layer is used as an inner layer board, and a rigid printed wiring board is bonded and laminated on a part or all of both surfaces thereof, and the above-mentioned conductor is also provided on a part of the flexible board that can be bent. In manufacturing a multilayer flex-rigid wiring board having a circuit and a part of its protective layer, a step of forming a protective layer of a flexible conductive circuit including a bendable portion by coating with a liquid material; Forming a bonding layer by coating a liquid material on the protective layer or the rigid printed wiring board in a portion to be laminated with the printed wiring board, and laminating a flexible substrate and a rigid wiring board after the formation of the bonding layer And adhering to the multilayer flex-rigid wiring board.