JPH0766558A - Manufacture of rigid and flexible multilayer printed board - Google Patents

Abstract

PURPOSE:To remove easily an unnecessary prepreg hardened material and the rigid circuit board part of the title printed board by a method wherein the printed board has prepregs and a non-adhesive surface and after laminated boards, which respectively have a rigid internal layer circuit, laminated boards for insulation and metal foils are laminated and molded, unnecessary metal foils and laminated boards of the metal foils and the laminated boards are removed from the non-adhesive surface. CONSTITUTION:Prepregs 2, which are used as covering layers, are respectively superposed on the surface and rear of a flexible intermediate layer circuit sheet 1 and laminated boards 3, which are respectively formed with a non-adhesive film at a prescribed position thereon, are respectively superposed on the upper and lower covering layers. Moreover, rigid circuit boards 5, which are respectively formed with a circuit on one surface thereof and are respectively bonded with a copper foil on the whole other one surface thereof, are respectively superposed via prepregs 4 for interlayer bonding and the prepregs 2, the boards 3, the prepregs 4 and the boards 5 are respectively laminated on the surface and rear of the sheet 1 and are molded. Then, surface-rear through holes and an external layer circuit are formed in and on an integrally formed copper-clad multilayer laminated board and a multilayer printed board is formed. When, after an electronic component is mounted on the multilayer printed board, V-shaped notches are respectively cut in breaking surfaces and a hardened resin layer on a flexible circuit sheet part to be exposed, unnecessary metal foils and the like are torn off from the surface of the non-adhesive film to remove.

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 so-called rigid flexible multilayer printed board which is a multilayer printed board and is used for mounting components in a narrower space with higher density.

[0002]

2. Description of the Related Art A rigid-flexible multilayer printed board is a structure in which at least two hard multilayer printed boards are physically and electrically connected by at least one flexible (flexible) circuit sheet. The rigid / flexible multilayer printed board can function as a single printed board, and can be bent at the flexible circuit sheet part. As a result, it is possible to fold a rigid (hard) multilayer printed board on which components are mounted. Is a multilayer printed board that can be mounted in a narrower space. The exposed portion of the flexible circuit sheet, that is, the front and back of the portion other than the rigid multilayer printed board, is generally protected by a flexible insulating layer.

In the method of manufacturing a rigid-flexible multilayer printed board, there are the following methods for forming a rigid multilayer printed board part and a flexible circuit sheet part. First, a rigid circuit board is laminated and molded integrally with a prepreg having substantially the same size as a rigid circuit board above and below a predetermined position of a part of a flexible circuit sheet to form a rigid circuit board. This is a method of making a circuit board part conductive on both sides.

Secondly, a flexible circuit sheet,
Make a rigid circuit board of substantially the same size as this,
Both of them are laminated and molded using a prepreg that is substantially the same size as the rigid circuit board, and only the positions that should be the rigid multilayer printed board are integrated, processed as a multilayer printed board, and finally made into a flexible board. In order to expose the circuit sheet, there is a method in which a rigid circuit board covering the surface is selectively removed by a method such as forming a V-shaped groove at a position to be broken.

[0005]

SUMMARY OF THE INVENTION The present invention is intended to solve the drawbacks of the conventional manufacturing method and manufacture a highly reliable and inexpensive rigid flexible multilayer printed board material. In the conventional method, it is necessary to previously remove only the portion corresponding to the flexible intermediate layer circuit sheet in the prepreg or prevent the resin from flowing out to the intermediate layer circuit sheet surface during the pressing step of the prepreg. Or there is a prepreg cut to the same size as the rigid circuit board, and must be placed in the correct position on the flexible intermediate layer circuit sheet, etc.
There were many problems in the manufacturing process.

Further, when a film obtained by forming an adhesive layer on a polyimide film is used as the cover layer,
There is a problem that the cover layer of the rigid portion has a large thermal expansion, so that the through hole reliability of the rigid portion is impaired, and delamination is likely to occur during soldering after absorbing moisture. Also,
As an improved method, a method has been proposed in which a cover lay of a polyimide film is adhered only to a portion where the flexible circuit sheet is exposed and is not used on the front and back sides of the flexible circuit sheet formed in the rigid multilayer printed board. However, this improved method has a problem in that the cover lay that has been cut in advance to a size corresponding to the exposed portion of the flexible circuit sheet must be accurately placed at a predetermined position, which makes the manufacturing process complicated. was there.

[0007]

According to the present invention, by making the size of each layer to be multi-layered substantially the same, the step of cutting a predetermined place in advance is skipped, and the alignment between layers is performed. It is easy and the flowability of the prepreg resin is
This is a method in which a material having a fluidity sufficient to fill the uneven conductor circuit surface can be used. The cover layer uses a prepreg that has flexibility even after thermosetting, and is a portion of the cover layer exposed as a flexible circuit sheet, which is located outside the cover layer after laminating and molding. , A method for easily removing an unnecessary prepreg cured product or a rigid circuit board portion. Specifically, at least one part of a flexible cover layer is bonded to a flexible intermediate layer circuit sheet and a circuit surface of the intermediate layer, and the flexible layer connects two or more rigid circuit boards. In manufacturing a rigid-flexible multi-layer printed circuit board of a fixed shape, a flexible intermediate-layer circuit sheet and a prepreg to be a cover layer and an inner-layer circuit to be a part of the rigid multi-layer circuit of substantially the same size Laminated plate and prepreg for interlayer adhesion, and / or insulating laminated plate,
And or after metal foil is laminated and formed, by removing the metal foil and the laminated plate other than the flexible intermediate layer circuit sheet and the flexible cover layer, which are in the positions to be finally the flexible circuit sheet portion, A method for producing a rigid flexible multilayer printed board, comprising preparing a laminated board having a film having a non-adhesive surface and a prepreg on one surface at a position corresponding to a flexible circuit sheet portion in advance. Is laminated on both outer sides of the cover layer so that the film having a non-adhesive surface is in contact with the prepreg to be the cover layer, and a laminated inner layer circuit is formed on both outer sides of the laminated plate via the interlayer prepreg. A plate and / or an insulating laminate, and / or a metal foil are stacked and laminated, and finally, a film having the non-adhesive surface. More, a method for manufacturing a rigid flexible multilayer printed board, wherein a build by removing the flexible intermediate layer circuits other than the sheet and a flexible cover layer, unnecessary metal foil and laminates.

In the present invention, the flexible intermediate layer circuit sheet means a metal-clad plastic film such as a polyimide film formed by forming a metal foil such as copper foil, a glass woven cloth or a non-woven fabric base material. Flexible thermosetting resin impregnated prepreg and metal foil stretched metal foil sheet, organic fiber woven fabric such as polyester fiber aramid fiber, non-woven fabric and flexible thermosetting resin impregnated prepreg and metal A metal foil sheet made by heating and pressing foil, or a sheet obtained by bonding a metal foil to a thermoplastic resin such as a fluororesin using a glass woven cloth or nonwoven cloth base material as a reinforcing substrate is used. The thickness of the insulating layer is 0.03 to 0.
20 mm is suitable, and the thickness of the metal foil is 5 to 70 μm.
Is preferred. The metal foil sheet is etched by a known method to form a circuit.

The prepreg which is to be the flexible cover layer of the present invention uses the same kind as a flexible circuit board sheet as a reinforcing base material. A prepreg having a thickness of 50 to 200 μm is suitable by impregnating the reinforcing base material with a flexible thermosetting resin composition even after thermosetting and drying. The thermosetting resin is a thermosetting resin such as an epoxy resin, a cyanate resin, a polyimide resin, an unsaturated polyester resin or a polybutadiene resin, and a rubber-based resin such as a nitrile butadiene rubber, an acrylic rubber or an epichlorohydrin rubber, or a thermoplastic resin. A composition in which 5 to 40% by weight of a flexibility-imparting component such as an elastomer is mixed is suitable.

The rigid circuit board of the present invention is a known metal-clad glass cloth / epoxy resin laminated board glass cloth / polyimide resin laminated board, etc., having an insulating layer thickness of 0.05 mm to
A 2 mm laminate is preferred. Copper foil thickness is 5-70μ
m is preferred. The prepreg of the present invention is a prepreg used when manufacturing the rigid circuit board laminate, and a prepreg having a thickness of 0.05 mm to 0.2 mm is suitable.

The following method is exemplified for the laminated plate of the present invention in which a prepreg and a non-adhesive film are formed on one surface at a position corresponding to the flexible circuit sheet portion. It is the same as the metal-clad laminate for a rigid circuit board, the insulating layer has a thickness of 0.03 to 0.20 mm, and the metal foil has a thickness of 5 to 7
Using a metal foil-clad laminate of 0 μm, a film with a non-adhesive surface is formed at a predetermined position by a known method such as printing or thermocompression, and a metal foil of a portion where the film is not formed is known. The method of making by removing by etching, the laminated sheet without metal foil or the laminated sheet obtained by completely removing the metal foil of the metal-clad laminated sheet by etching, the prepreg and the non-adhesive coating film. Examples of the method include forming a film by a method such as printing or adhesion. The combined use of metal foil has a feature that the thickness of the cover layer can be made thinner than the thickness of the rigid layer.

The non-adhesive film is specifically an acrylic epoxy composition, which is a photo-curable or thermosetting photo solder resist or a thermosetting resin solution such as an epoxy resin in which a silicone resin, a fluororesin or the like is added. For example, a solution obtained by mixing a releasing compound is printed, dried, and heat-cured. The film thickness is not particularly limited, but usually 200 μm or less is suitable.

[0013]

EXAMPLE A specific manufacturing method will be described with reference to the drawings. 1
The two prepregs serving as cover layers are stacked on the front and back of the flexible intermediate-layer circuit sheet, and the laminated plate 3 having the non-adhesive film formed at predetermined positions is stacked above and below the cover layers. Furthermore, a circuit board is formed on one surface through the interlayer adhesive prepreg 4, and one surface is entirely bonded with copper foil to provide a rigid circuit board 5.
Are stacked and laminated. Integrated copper-clad multilayer laminate
By a known method, front and back conduction holes and outer layer circuits are formed to make a multilayer printed board. If necessary, after mounting the electronic component, the cured resin layers and metal foils above and below the flexible circuit sheet portion to be exposed are peeled off from the non-adhesive film surface and removed. In order to facilitate the removal, a known method such as making a V-shaped cut in the fracture surface is performed.

[0014]

As is clear from the detailed description of the invention and the examples, the present invention is a method of manufacturing a rigid flexible multilayer printed board, in which a prepreg for a cover layer is integrally molded and a mold release property is applied to an unnecessary rigid portion. By adding the above, it is possible to easily and inexpensively prepare a rigid flexible multilayer printed board, and the industrial practicality and economical efficiency are extremely high.

[0015]

[Brief description of drawings]

FIG. 1 is a perspective view schematically showing a layer structure used for manufacturing a rigid flexible multilayer printed board of the present invention.

FIG. 2 is a sectional view showing a V-shaped cut portion of a manufactured multilayer board.

FIG. 3 is a perspective view schematically showing a V-shaped multi-layer board.

FIG. 4 is a perspective view schematically showing a rigid flexible multilayer printed board from which a cured product on the release film surface of the multilayer board is removed.

[Explanation of symbols]

Reference numerals in FIGS. 1 to 3 are respectively 1: flexible intermediate layer circuit board, 2: cover layer prepreg, 3: laminated plate having a non-adhesive film formed thereon, 4: interlayer adhesive prepreg, 5:
Rigid circuit board with copper foil bonded to the entire surface on one side, showing a V-shaped hole.

Claims (2)

[Claims] 1. A flexible intermediate layer circuit sheet and at least a part of a flexible cover layer adhered to a circuit surface of the intermediate layer, and the flexible layer connects two or more rigid circuit boards. In the production of a rigid flexible multilayer printed circuit board of a fixed shape, a flexible intermediate layer circuit sheet and a prepreg to be a cover layer and an inner layer circuit to be a part of the rigid multilayer circuit are substantially the same size. A flexible intermediate-layer circuit sheet, which is in a position to finally become a flexible circuit sheet portion after the formed laminate and the prepreg for interlayer adhesion and / or the insulating laminate and / or the metal foil are laminated and molded. And a rigid flexible multilayer ply made by removing the metal foil and laminate except the flexible cover layer. A method for manufacturing a printed circuit board, wherein a laminated board having a film having a non-adhesive surface with a prepreg is prepared on one surface at a position corresponding to a flexible circuit sheet portion in advance, and the laminated board is non-adhesive. A laminate having a surface-containing film stacked on both outer sides of the cover layer so as to be in contact with the prepreg to be the cover layer, and a laminate having a rigid inner layer circuit formed on both outer sides of the laminate through interlayer adhesive prepregs, and or After stacking and laminating the insulating laminated plate and / or the metal foil, finally, from the film surface having the non-adhesive surface, unnecessary metal other than the flexible intermediate layer circuit sheet and the flexible cover layer is removed. A method of manufacturing a rigid-flexible multilayer printed board, characterized in that the rigid flexible multi-layer printed board is manufactured by removing the laminated board. 2. A laminate having a film having a non-adhesive surface is formed on a metal-clad laminate, and a film having a non-adhesive surface is formed at a predetermined position. The method for producing a rigid-flexible multilayer printed board according to claim 1, wherein a laminated plate produced by removing metal foil other than the film is used.