JPH05183275A - Manufacture of metal core multilayer printed wiring board - Google Patents

Abstract

PURPOSE:To improve the reliability of a through hole and enhance heat dissipating properties, without largely changing the conventional manufacturing method of a metal core multilayered printed wiring board which method contains one time curing process. CONSTITUTION:In the manufacturing method of a metal core multilayer printed wiring boad, the following are laminated in order and heated with pressure; an inner layer circuit board 47 wherein a circuit 47b for an inner layer is formed on an insulative substrate 47a, B-stage type prepregs 45 and 46, a metal plate 43 subjected to hole working for a through hole, an adhesive agent sheet 42 containing filler, and a copper foil 41. An adhesive agent sheet 44 containing filler is interposed between the prepreg 45 and the metal plate 43, and heated with pressure.

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 metal core multilayer printed wiring board, and more particularly to a method for manufacturing a metal core multilayer printed wiring board having high reliability of through holes and excellent heat dissipation. is there.

[0002]

2. Description of the Related Art Today, with the high integration of electronic parts and the mounting density of electronic devices that progress at high speed, metal core multilayer printed wiring boards, which have particularly excellent heat dissipation characteristics, are becoming more and more important. It's starting. By the way, in the generally used manufacturing method of a metal core multilayer printed wiring board, the following four types of methods are mainly used for laminating and pressing the multilayer boards.

(1). As shown in FIG. 3A, an inner layer circuit board 1, a prepreg 2, a metal plate 3 having holes for through holes, a B-stage resin sheet 4, and an adhesive sheet 5 containing a filler. A method of sequentially laminating the copper foils 6 on which the above has been applied, and heating and pressing to cure the copper foils. (2). As shown in FIG. 4 (A), an uncured copper clad metal laminate in which a copper foil 12 is bonded to a metal plate 13 having holes for through holes via an adhesive sheet 11 containing a filler. A method in which the board 14 is laminated on the inner layer circuit board 16 via the prepreg 15 and heated under pressure to be cured.

(3) As shown in FIG. 5 (A), a copper foil 22 is attached to a metal plate 23 having holes for through holes via a filler-containing adhesive sheet 21, and heat-cured in advance to be molded. The copper clad metal laminate 24 thus prepared is laminated on the inner layer circuit board 26 via the prepreg 25, and is heated under pressure to be cured. (4). As shown in (A) to (C) of FIG. 6, a copper clad metal laminate in which a copper foil 32 is bonded to a metal plate 33 having holes for through holes via a filler-containing adhesive sheet 31. Board 34
In addition, the adhesive sheet 31 containing the filler is also adhered to the surface of the copper clad metal laminate 34 on the opposite side of the surface where the copper foil 32 is adhered, and the holes of the metal plate 33 are also filled with the adhesive containing the filler ( Figure (A)) is heated under pressure to obtain a copper-clad metal laminate cured product 35 (Figure (B)), and the copper-clad metal laminate cured product 3 is obtained.
5 is laminated on the inner layer circuit board 37 via the prepreg 36 (Fig. (C)), and is heated and cured again to cure (31a).
Indicates a cured adhesive layer containing a filler).

[0005]

However, the above conventional method has the following problems. (a). In the case of the above (1), as shown in (B) of FIG. 3, B is added to the filler-containing cured adhesive layer 5a between the metal plate 3 and the copper foil 6.
The resin overflowed from the stage-shaped resin sheet 4 and the prepreg 2 is mixed (2a indicates a prepreg cured insulating layer, 4a indicates a cured resin sheet), and the heat dissipation characteristic of the filler-containing adhesive cannot be expected. There was a problem in that it was inferior in appearance. (b). In the case of the above (2) as well, as shown in FIG. 4B, the prepreg 15 is formed on the layer of the filler-containing cured adhesive layer 11a between the metal plate 13 and the copper foil 12, as described above. The overflowed resin is mixed (15a indicates a prepreg cured insulating layer), the heat dissipation characteristics of the adhesive containing the filler cannot be expected, and the appearance is inferior.
Since hole 3 is simply resin, the coefficient of thermal expansion of the through-hole insulating layer is large, the difference in thermal expansion from the plated copper is large, stress is generated at the plating / resin interface, and the adhesion with the through hole Therefore, there is a problem in that the reliability of the through hole becomes low and the reliability of the through hole becomes low.

(C). In the case of the above (3), as shown in FIG. 5 (B), since the hole of the metal plate 23 is only a resin made of the prepreg 25 (21a is a filler-containing cured adhesive) Agent layer, 25a indicates a prepreg cured insulating layer), above
(b) Similarly, there is a problem that the reliability of the through hole is reduced. Moreover, since the curing process is performed twice, the process is complicated and the manufacturing cost is increased.

(D). In the case of the above (4), as shown in FIG. 6D (36a indicates a prepreg cured insulating layer), there is no problem in physical properties, but the curing step is 2 Because there is a degree,
There is a problem that the process becomes complicated and the manufacturing cost also rises. The present invention has been devised by focusing on such a conventional problem, without significantly changing the conventional method for manufacturing a metal core multilayer printed wiring board having one curing step.
It is an object of the present invention to provide a method for manufacturing a metal core multilayer printed wiring board having a highly reliable through hole and excellent heat dissipation characteristics.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the gist of the present invention is to apply pressure and heat with an adhesive sheet containing a filler interposed between a prepreg and a metal plate.

[0009]

The present invention is configured as described above, and the adhesive sheet containing the filler is disposed between the metal plate having the through hole hole and the prepreg for adhesion and insulation, and is heated under pressure. , It is possible to avoid the resin of the prepreg overflowing during curing and mixing into the holes of the metal plate and the adhesive sheet containing the filler between the metal plate and the copper foil. A metal core multilayer printed wiring board having high heat dissipation is manufactured by forming only a cured adhesive layer containing a filler having excellent heat dissipation properties.

Further, only the adhesive containing the filler can be filled in the holes of the metal plate, and a through-hole insulating layer having a low coefficient of thermal expansion and an excellent adhesion to the plated copper is formed, and therefore a highly reliable through hole is formed. A hole is formed. Further, it is possible to manufacture a metal core multilayer printed wiring board having excellent heat dissipation characteristics and high reliability of through holes, which conventionally requires two curing steps in one curing step.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a stacking diagram for manufacturing a metal core multilayer printed wiring board, and FIG. 2 shows a manufacturing process for the metal core multilayer printed wiring board. 1A shows the state before pressure heating, and FIG. 1B shows the state after pressure heating. In FIG. 1, 41 is copper foil, and 42 and 4
4 is an uncured filler-containing adhesive sheet having excellent heat dissipation properties, which contains a filler having excellent thermal conductivity such as alumina.
Reference numeral 43 is a metal plate such as an aluminum plate, an iron plate or a copper plate, and 45 and 46 are sheet-like prepregs obtained by impregnating a base material such as a glass cloth with a resin such as an epoxy resin and curing it to the B stage.

Reference numeral 47 is an inner layer circuit board in which an inner layer circuit 47b is formed on an insulating substrate 47a, and 48 is a filler-containing cured adhesive layer in which the filler-containing adhesive sheets 42 and 44 are cured after heating under pressure, Reference numeral 49 is a prepreg cured insulating layer in which the prepregs 45 and 46 are cured and integrated. In the manufacturing process, as shown in FIG. 2, first, a hole for a through hole is formed in the metal plate 43 (step), and then an edge portion of the formed hole is deburred (step). A surface treatment is applied to the surface of the substrate by a predetermined method (step). Further, the produced adhesive containing filler is applied to a film to form an uncured filler-containing adhesive sheet 44 formed into a film shape (step), and at the same time, the copper foil 41 is applied with the filler-containing adhesive. An adhesive sheet-attached copper foil 51 having an uncured filler-containing adhesive sheet 42 is formed (step).

Next, the metal plate 43 surface-treated in the step and the copper foil 5 with the adhesive sheet formed in the step 5
1 and the copper-clad metal laminated plate 52 are bonded to each other (step), and the adhesive sheet with a filler 44 formed in the step and the prepreg 45 are bonded to each other to form a prepreg 53 with an adhesive sheet (step).

Then, in a separate step, the inner layer circuit board 47 in which the circuits 47b for inner layers are formed on both surfaces of the insulating substrate 47a by the conventional method, the copper clad metal laminate 52, and the prepreg 53 with the adhesive sheet are used as inner layers. From both sides of the circuit board 47, the prepreg 46, the prepreg 45, the filler-containing adhesive sheet 44, the metal plate 43, and the filler-containing adhesive sheet 4
2. The copper foil 41 is laminated in this order (step), and heated under pressure.

At the time of pressurizing and heating, the filler-containing adhesive sheet 44, which is difficult to flow by itself, is pressed by the resin overflowing from the prepregs 45 and 46, and the filler-containing resin of the filler-containing adhesive sheet 44 is processed into the processed hole of the metal plate 43. The filler-containing adhesive sheet 44 causes the resin of the prepreg 45 to overflow and the filler-containing adhesive sheet 42 interposed between the processed holes of the metal plate 43 and the copper foil 41 and the metal plate 43. It is prevented from mixing in with the copper foil 4 after curing, as shown in Fig. 1 (B).
1 and around the metal plate 43, a cured adhesive layer 4 containing a filler
It is possible to obtain the multi-layer plate 54 formed of only 8 pieces.

The metal plate 4 of the multi-layer plate 54 laminated and hardened as described above in the conventional steps conventionally used
A through hole can be formed in the hole 3 and an electric circuit can be formed in the copper foil 41 to obtain a metal core multilayer printed wiring board. The hole machining of the metal plate 43 may be performed by punching with an NC drill, a press or the like, chemical milling, etc. Deburring is performed by sanding the surface with sandpaper, or by dissolving with an alkali. In the case of copper, an ordinary oxidation treatment or the like may be performed.

Adhesive sheet 4 containing filler for copper foil 41
In the construction of No. 2, a filler-containing adhesive may be applied to the copper foil 41, or a filler-containing adhesive sheet 42 formed by applying a filler-containing adhesive to a film may be laminated on the copper foil 41. .. In order to ensure the insulation between the copper foil 41 and the metal plate 43, after laminating the copper foil 51 with an adhesive sheet on the metal plate 43, the uncured filler-containing adhesive sheet 42 is B-staged or resin flow is applied. Taking into consideration, the uncured filler-containing adhesive sheet 42
Is preferably set thick beforehand.

Further, the resin of the prepreg 45 overflows at the time of pressurizing and heating to prevent the resin from mixing with the filler-containing adhesive sheet 42 interposed between the copper foil 41 and the metal plate 43. The agent sheet 44 is
Has a sufficient thickness to prevent mixing, preferably 40μ
The value is from m to 200 μm, but is not limited to the above numerical value.

The pressurizing and heating method is not particularly limited, but a vacuum press die is used, and the inner layer circuit board 47, the prepreg 53 with an adhesive sheet, and the copper clad metal laminated board 52 are laminated under heating vacuum. When the body is pressed in a vacuum-deaerated state, even if a metal plate having a poor surface smoothness is used, it is possible to form a multi-layer plate 54 in which air bubbles and the like do not mix in the filler-containing cured adhesive layer 48. It is possible to suppress bubbles remaining in the holes of 43.

In the above embodiment, the method of manufacturing a metal core multilayer printed wiring board having four conductive layers has been described. You may use it for a manufacturing method.

[0021]

As described above, according to the present invention, since an adhesive sheet containing a filler is interposed between the prepreg and the metal plate and heated under pressure, the filler interposed between the prepreg and the metal plate is used. The filled adhesive sheet prevents the resin of the prepreg from overflowing, and it is possible to prevent the resin of the prepreg from being mixed in the hole portion of the metal plate, and the filler-containing adhesive sheet between the metal plate and the copper foil, There is an effect that a metal core multilayer printed wiring board having high heat dissipation can be manufactured by forming only the cured adhesive layer containing a filler having excellent heat dissipation properties around the copper foil and the metal plate.

Further, only the adhesive containing the filler can be filled in the holes of the metal plate, the coefficient of thermal expansion and the adhesion of the through-hole insulating layer to the through-hole plating are improved, and a highly reliable through-hole is formed. The effect is that you can do it. Further, it is possible to manufacture a metal core multilayer printed wiring board having excellent heat dissipation characteristics and high through-hole reliability, which conventionally required two curing steps, in only one curing step. There is an effect that the manufacturing cost can be reduced by simplifying the manufacturing process.

[Brief description of drawings]

1 (A) and 1 (B) are cross-sectional views showing a configuration before and after curing in a method for manufacturing a metal core multilayer printed wiring board according to the present invention.

FIG. 2 is a block diagram showing a manufacturing process of the metal core multilayer printed wiring board of the present invention.

3 (A) and 3 (B) are cross-sectional views showing a configuration before and after curing in a method for manufacturing a metal core multilayer printed wiring board of a first conventional example.

4 (A) and (B) are cross-sectional views showing a configuration before and after curing in a method for manufacturing a metal core multilayer printed wiring board according to a second conventional example.

5A and 5B are cross-sectional views showing a configuration before and after curing in a method for manufacturing a metal core multilayer printed wiring board according to a third conventional example.

6 (A), (B), (C) and (D) are cross-sectional views showing configurations before and after curing in a method for manufacturing a metal core multilayer printed wiring board according to a fourth conventional example.

[Explanation of symbols]

41 Copper Foil 42,44 Adhesive Sheet with Filler 43 Metal Plate 45,46 Prepreg 47 Inner Circuit Board 48 Cured Adhesive Layer with Filler 51 Copper Foil with Adhesive Sheet 52 Copper Clad Metal Laminate 53 Prepreg with Adhesive Sheet 54 Multilayer Board

Claims (1)

[Claims] 1. An inner layer circuit board in which circuits for inner layers are formed on an insulating substrate, a B-stage prepreg, a metal plate having holes for through holes, a filler-containing adhesive sheet, and copper. In the method for producing a metal core multilayer printed wiring board in which foils are laminated in the above order and heated under pressure, heating with pressure is performed by interposing a filler-containing adhesive sheet between the prepreg and the metal plate. A method of manufacturing a metal core multilayer printed wiring board, which is characterized.