JPH0239486A - Manufacture of metal core printer substrate for bending - Google Patents

Abstract

PURPOSE:To enable bending without lowering a breakdown voltage and generating rising at a bent part by using a combination of two types (stage B and stage C) of heat curing resin layers. CONSTITUTION:One side surface of a metal core plate 1 having a through hole 11 is provided with a heat curing resin layer 3 of stage C consisting of resin component alone whereon a metal foil 4 is laminated outside through a heat curing resin layer 2 of stage B consisting of resin component alone. Another side of the metal core plate 1 is provided with a heat curing resin layer II and then made one-body after heating and fixed by pressure. The heat curing resin layer II consists of the heat curing resin layer 2 and the heat curing resin layer 3 laminated on the outside thereof. The heat curing resin layer II is formed by a prepreg sheet consisting of heat curing resin infiltrate into fiber cloth 51.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a printed circuit board, which yields a metal-core printed wiring board that can be bent without deteriorating its performance.

(Prior art) A metal core printed wiring board consists of a metal core plate and a conductive circuit layer provided on the surface of the metal core plate through an insulating layer, and has excellent heat dissipation and magnetic shielding properties, and is suitable for hybrid IC boards. It is supplied for various purposes such as

Conventionally, as shown in the cross-sectional schematic diagram of FIG. 4, the substrate for this metal-core printed wiring board has been made using an epoxy resin-impregnated glass fiber mat (glass epoxy) on a metal core plate 1 in which a large number of through holes 11 have been formed in advance. 7 is bonded under heat to cover the surface of the core plate, and at the same time, the epoxy resin impregnated into the glass fiber mat is flowed into the holes.

(Problems to be Solved by the Invention) In the substrate using the above-mentioned glass epoxy, as shown in the cross-sectional schematic diagram of FIG. When the bending process is applied, separation occurs between the glass fiber mat and the cured resin at the bent part, which tends to form a deformed part (bulge) F with a convex cross section. If the degree of bulge is severe, the conductive circuit There was a problem with the wire breaking.

However, with this configuration, the above-mentioned blistering problem can be easily solved, but there is a problem that it is difficult to make the thickness of the insulating layer uniform and the insulation properties are poor.

An object of the present invention is to provide a method for manufacturing a metal-core printed circuit board that eliminates the above-mentioned drawbacks.

(Means for Solving the Problems) In order to achieve the above object, the present invention uses a combination of B-stage and C-stage thermosetting resin layers and integrates them by thermocompression bonding. On one side of the metal core plate 1 having the through hole 11, a C stage thermosetting resin layer 3 consisting of only a resin component with a metal foil 4 laminated on the outside is placed on a B stage thermosetting resin layer 3 consisting only of a resin component. The metal core plate 1 is disposed via the thermosetting resin layer 2.
The method of manufacturing a metal-core printed circuit board for bending is characterized in that a thermosetting resin layer II is disposed on the opposite side and then integrated by thermocompression bonding.

Here, the B stage referred to in the present invention is 50 to 180''
The C stage refers to a semi-cured state at room temperature that has sufficient fluidity to fill the through holes of the metal core in the range of C, and the C stage refers to a state of curing that does not cause a significant decrease in viscosity in the range of 50 to 180 °C. state the condition.

The present invention will be specifically described below with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of a printed circuit board material used in the method of one embodiment of the present invention. The printed circuit board made of the material shown in FIG.
It has been established.

The metal core plate 1 is made of iron, aluminum, copper, etc., has a thickness of usually about 0.1 to 3.0 mm, and is preferably subjected to chromate treatment.

The through holes 11 usually have a diameter of about 165 to 3.5 mm, and are punched or drilled in advance into the required pattern.

In the method of the present invention, on one side of the metal core plate 1, a C-stage thermosetting resin layer 3 made of only a resin component with a metal foil 4 laminated on the outside is coated with a B-stage thermosetting resin layer 3 made of only a resin component. It is necessary to arrange the resin layer 2 through the adhesive resin layer 2. As the above thermosetting resin, common epoxy resins, polyimide resins, unsaturated polyester resins, etc. can be used.

By using only a resin component for the insulating layer, it is possible to prevent blistering due to bending, and because the B-stage thermosetting resin is placed in contact with the metal core plate, it is difficult to inject the resin into the through-hole of the metal core plate. Filling becomes easier. This B-stage resin has the advantage that the lower the viscosity, the easier it is to fill.

Furthermore, since the resin on the metal foil side is always a C-stage thermosetting resin, there is no change in thickness due to thermocompression bonding, making it easier to make the thickness of the insulating layer uniform, and reducing the effect on the conductive circuit to be formed. You can do less.

Further, it is necessary to arrange a thermosetting resin layer II on the opposite side of the metal core plate 1.

In the example shown in FIG. 1, a laminate (3) in which a B-stage thermosetting resin layer 2 is provided on a C-stage thermosetting resin layer 3 without laminating a metal foil 4, and a laminate (3) in which a B-stage thermosetting resin layer 2 is provided on a C-stage thermosetting resin layer 3 and a C-stage resin layer 3 are similarly provided. The thermosetting resin layers II of the laminate each having a B-stage thermosetting resin layer were prepared in advance and placed on both sides of a metal core plate.

By using a material in which B stage and C stage resin layers are laminated in advance in this manner, the work process can be simplified.

Next, FIG. 2 shows a schematic cross-sectional view of a printed wiring board material used in another embodiment of the present invention. In the printed wiring board material shown in FIG.
The laminated weight shown in the figure is arranged, and a thermosetting resin layer II of a prepreg sheet made of a thermosetting resin impregnated with fiber cloth 51 is arranged on the opposite side of the metal core plate. The above fiber cloth 51
A woven fabric or a non-woven fabric made of glass fiber or polyester fiber can be used as the material, and the thermosetting resin may be the same as or different from the resin used for the bent inner surface.

By interposing the fiber cloth in the insulating resin layer on one side in this way, there is an effect that fine air hoids generated in the thermocompression bonding process can easily escape from between the fibers.

Next, it is necessary to integrate the materials arranged in the configuration described above by thermocompression bonding. The thermocompression bonding conditions may be normal press conditions, and the B-stage resin placed on one or both sides should be sufficiently filled into the through hole. The press conditions are as follows:
If the press temperature is in the range of 120°C to 180°C, the pressing pressure is in the range of 10 to 100 kg/-, and the degree of reduced pressure (difference between normal pressure and residual pressure) is about 730 mmHg, voids will not occur. Preferably, it can be prevented. The obtained substrate is
It is then sent to the subsequent printed wiring board manufacturing process, where it undergoes processing such as pattern printing on the metal foil, etching, washing, and if necessary, forming through holes. ! The final printed wiring board can be obtained without bending.

The present invention will be explained below with reference to Examples.

(Example) Example 1 A metal core printed circuit board was obtained with the layer structure shown in FIG. 1 and the following content.

(a) A C-stage thermosetting resin layer 3 made of bisphenol A type epoxy resin and an aromatic amine curing agent and having a thickness of 40 to 50 JJ, m is provided on the chemical conversion treatment surface of the electrolytic copper foil 4 (thickness 35 μm), Next, a film with the same composition as above and a thickness of 70
A B-stage thermosetting resin layer 2 of ~80 μm is provided to obtain a laminate (2).

(B) Similarly, a thermosetting resin layer II of a laminate in which a B-stage thermosetting resin layer 2 is provided on a C-stage thermosetting resin layer 3 having the same content as above is created, and the above laminates The B-stage thermosetting resin is placed on the inside, and a 0.8 mm thick metal core plate (L plate) having a through hole with an inner diameter of 1 to 5 nm is placed between them.

(c) Next, the surface pressure is 60Kg/cd, and the heating temperature is 17o-
'c''''C- Perform vacuum press and heat press to seal.

The breakdown voltage of the insulating layer was measured at 135° for the obtained laminate.
A bending test was conducted so that the bending angle was 165° or 165°.

As a result, the breakdown voltage was 5 kV, and no blisters were observed at the bent portions of both 135' and 165' in the bending test.

Example 2 The layer structure was as shown in FIG. 2, and the thermosetting resin layer II was made of a B-stage thermosetting resin consisting of a bisphenol A epoxy resin and an aromatic amine curing agent.
The structure was the same as in Example 1 except that the prepreg sheet was impregnated with. When the obtained laminate was subjected to the same test as in Example 1, the breakdown voltage was 6 kV or more, 135
No blisters were observed at the bent portions at both 165° and 165°.

Comparative Example 1 A printed circuit board with the layer structure shown in the diagram, using the same metal core as in Example 1.2, with epoxy resin-impregnated glass fiber mats provided on both sides of the metal core as an insulating layer, Furthermore, place copper foil on one side, press temperature 160°C, 5 surface pressure 4
The total thickness of the insulating layer is 300 μm to be integrally bonded by thermocompression under the condition of 0 kg/-. The obtained printed circuit board was evaluated in the same manner as in the example. As a result, the breakdown voltage was 5 kV or more, but blistering occurred due to bending.

Comparative Example 2 The structure was the same as that of Comparative Example 1 except that the insulating layer was made of a B-stage thermosetting resin without using glass fibers, and the same evaluation as above was performed after thermocompression bonding. As a result, although there was no bulge due to bending, the thickness of the insulating layer was not uniform and the breakdown voltage was 3 kV or less.

(Effects of the Invention) As described above, the printed circuit board obtained according to the present invention can be bent without decreasing breakdown voltage or blistering at the bent portion, and is suitable for bending substrates for keyboards, etc. It has great applicability in fields that require

FIG.

1...Metal core plate 11...Through hole 2...B stage thermosetting resin layer 3... C-stage thermosetting resin layer 4...Metal foil ■・・・Thermosetting resin layer

[Brief explanation of the drawing]

Claims (3)

[Claims] 1. On one side of the metal core plate (1) having the through hole (11), a C-stage thermosetting resin layer (3) consisting only of a resin component with a metal foil (4) laminated on the outside is applied. At the same time, a thermosetting resin layer II is placed on the opposite side of the metal core plate (1), and then integrated by thermocompression bonding. A method for manufacturing a metal core printed circuit board for bending processing, characterized by: 2. Thermosetting resin layer II is composed of a B-stage thermosetting resin layer (2) consisting only of resin components, and a C-stage thermosetting resin layer (3) consisting only of resin components laminated on the outside thereof. 2. The method of manufacturing a metal core printed circuit board for bending according to claim 1. 3. 2. The method of manufacturing a metal core printed circuit board for bending according to claim 1, wherein the thermosetting resin layer II is composed of a prepreg sheet made of a thermosetting resin impregnated with a fiber cloth (51).