JPS61241151A - Manufacture of metallic-base printed substrate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method of manufacturing a printed circuit board used for configuring electronic component circuits, and in particular to a method for manufacturing a printed circuit board for use in the construction of electronic component circuits. The present invention relates to a method of manufacturing a highly thermally conductive metal-based printed circuit board made of metal.

(Conventional technology) In recent years, the penetration of electronic technology into the industrial world has been remarkable, and electronic devices are playing an active role in all industrial fields. However, the recent trend of electronic devices is toward miniaturization, and for this reason, electronic components are mounted on printed circuit boards at a high rate to cope with miniaturization, and the higher the mounting, the more ICs are mounted.

The amount of heat generated from electronic components such as MSI, , and LSI is
The mounting unit area increases significantly. Therefore, one issue is how to efficiently dissipate that heat.

Generally, electronic components are mounted on a printed circuit board by soldering or the like, and in order to improve the heat dissipation, a metal-based printed circuit board made of a highly thermally conductive metal is used. Conventionally, the manufacture of such metal-based printed circuit boards with high thermal conductivity has been described, for example, in "Electronic Technology" Vol. 26,
No. 7 (1984), laminates were formed by a hot press method, similar to paper phenol resin laminates or glass-based epoxy resin laminates.

Figure 2 is a cross-sectional view showing the structure of a metal-based printed circuit board, where l is a metal base, 2 and 3 are insulating layers, 4 is a metal conductor such as metal foil, and insulating layer 2.3 is a metal base 1. The adhesive used to bond the conductor 4 and the conductor 4 is hardened and denatured.

To manufacture such a metal-based printed circuit board, as shown in Figure 3, for example, a highly thermally conductive filler (hereinafter referred to as A highly thermally conductive adhesive comprising a dispersed inorganic filler (simply referred to as an inorganic filler) is applied to each surface of the metal base l and the conductor 4 to form an adhesive insulating layer 2.3.
3 (&), (b)), and then in the next step of pressing, the applied high thermal conductive adhesive is applied to each surface S.

The insulating layer 2゜3 (
After a drying process to prevent the layer thickness from becoming uneven as shown in Fig. 2), they are stacked as shown in Fig. 3(C), and finally heated press 5a as shown in Fig. 3(d). , 5b, and are laminated by pressing with metal backing plates 6a, 6b interposed.

However, in the production of metal-based printed circuit boards as described above, a highly thermally conductive adhesive in which an inorganic filler is dispersed in an organic polymer is used as an adhesive that is made only of an organic polymer without an inorganic filler. On the other hand, as the amount of inorganic filler is increased, the clay will rise, making it easier for air bubbles to remain in the adhesive.

Therefore, in the metal-based printed circuit board after lamination, air bubbles will be present in the insulating layer formed by the hardening of the adhesive, thereby reducing the dielectric strength and adhesive strength of the insulating layer. In order to compensate for this insulation loss, metal-based printed circuit boards have traditionally been designed with two
The insulating layers 2, 3 of the layers are formed by applying adhesive to both the metal base 1 and the conductor 4 described in FIG.

(Problems to be Solved by the Invention) As described above, the conventional method for manufacturing a metal e-sprint board using the hot press method includes a drying step to prevent the adhesive from flowing out. However, this drying impairs the fluidity of the adhesive, and therefore reduces the wettability of the adhesive surface S, that is, the conformability. This poses a fatal problem for printed circuit boards, as it does not allow for strong bonding. In addition, this weak bonding strength has a disadvantage that it has an adverse effect on the physical properties of the metal-based glint substrate, such as dielectric strength, solder heat resistance, and moisture resistance, and greatly reduces the substrate performance.

In addition, when the adhesive insulating layer 3 is formed on the conductor 4 and dried, the conductor 4 may warp due to curing and shrinkage, the insulating layer may crack, or the hot pressing process may take at least 2 hours. There was a problem with sexuality. The present invention aims to eliminate the problems of the prior art described above.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a highly thermally conductive adhesive made by dispersing highly thermally conductive fibers in an adhesive organic polymer. After coating the surface to form an adhesive insulating layer and curing the adhesive insulating layer, the above-mentioned high thermal conductive adhesive or an equivalent high thermal conductive adhesive is applied to the upper surface of the cured adhesive insulating layer. By forming an adhesive insulating layer of The metal-based printed circuit board is manufactured by a process of pressing the adhesive layer to transform it into a hardened insulating layer.

(Function) The present invention has a step of temporarily adhering a conductor in a state where the cured insulating layer on the metal base and the adhesive insulating layer are blended to ensure sufficient fusion between the insulating layers, and then pre-curing is performed at a low temperature. Conventionally, conductors (generally metal foil) due to thermal expansion that occurs when adhesives are cured at high temperatures with good fluidity.
There is no temporary adhesive, so the conductor does not peel off easily, and there is no blistering of the conductor, which is caused by air bubbles remaining in the adhesive expanding due to temperature rise.
At the same time, it is possible to manufacture a printed circuit board with high adhesion strength that eliminates the drawbacks such as the above-mentioned insulating properties.

(Example) Hereinafter, the present invention will be described in detail using one example) with reference to the drawings.

FIG. 1 is a cross-sectional process diagram showing an embodiment of the present invention, where 7 m r 7 b indicates a roll press, 8 indicates a cured insulating layer formed by curing an adhesive insulating layer, and other symbols are explanatory. is until last time! 5! According to Ming.

The method for manufacturing the metal-based glint substrate of the present invention includes, for example,
A highly thermally conductive adhesive consisting of an inorganic filler dispersed in an organic polymer such as an adhesive phenol resin or epoxy resin material is applied to the surface of the metal base 1, and then cured. to form a hardened insulating layer 8 (see FIG. 1(a)
), (b)). Next, on the cured insulating layer s, an uncured adhesive insulating layer 3t, which is the same as or equivalent to the above-mentioned highly thermally conductive adhesive, is formed, and then the conductor 4 is overlaid (FIG. 4(C)).
), then roll press 7m as shown in (d) of the same figure.
A metal base glint substrate is formed by press-bonding and laminating the adhesive and insulating layer 3 to +7b, and finally subjecting the adhesive insulating layer 3 to preliminary curing and main curing heat treatment at a relatively low temperature. This will be explained in detail below.

First, a metal with good heat dissipation, such as aluminum, is used for the metal base 1, and an adhesive organic polymer,
For example, a highly thermally conductive adhesive made of phenol resin or epoxy resin material with inorganic filler dispersed, a blade coater method, a screen printing method, a metal mask printing method, or a roll coater method may be used alone or in combination. Coating to a thickness of 20 to 100 μm to form an adhesive insulating layer,
This is then cured at a temperature of 50 to 200° C. to form a cured insulating layer 8. Next, as shown in FIG. 1(b), the adhesive insulating layer 3 is formed by applying the highly thermally conductive adhesive to a thickness of 20 to 100 #l by the same method on the cured insulating layer 8. Figure (c)) Lay the conductor 4 on top of it and press and bond it to roll presses 7m and 7b set at a linear pressure of 1o to 5oogATn. The roll presses 7a and 7b at this time may be at room temperature, or
It may be heated to 200C to 200C. Thereafter, the adhesive and insulating layer 3 is precured by leaving it in an environment of, for example, 5° C. to 125° C. for at least 30 minutes. This eliminates the curling of the conductor (generally metal foil) 4 due to thermal expansion in the initial stage of subsequent curing, which conventionally occurs when the adhesive is cured at high temperature with good fluidity, and therefore the conductor 4 is easily formed. Furthermore, the so-called blistering of the conductor, which is caused by the expansion of air bubbles remaining in the adhesive due to the rise in temperature, is completely eliminated, and the above-mentioned drawbacks such as poor adhesive strength and insulation properties can be solved. Finally, by fully curing the adhesive insulation N3 in a temperature environment of 150° C., a sgelint substrate is formed on the metal insulated by the hardened insulating layer 8 and the hardened adhesive insulating layer 3. Ru.

As described above, the present invention forms a hardened insulating layer on the metal base constituting the metal base glint substrate, then applies an uncured adhesive insulating layer to that surface, and overlays the conductor 4 on the uncured adhesive insulating layer. The adhesive insulating layer is bonded together using a roll press or the like in a cured state, and the adhesive insulating layer is formed into a cured insulating layer through a two-step heat curing process: preliminary curing of the adhesive insulating layer at a relatively low temperature, and subsequent main curing. This is a method of manufacturing a highly thermally conductive metal-based printed circuit board by.

(Effects of the Invention) As is clear from the above detailed description, the present invention provides a hardened insulating layer on a metal base constituting a metal-based printed circuit board, further coats an adhesive insulating layer thereon, and then applies a conductor. The metal base and conductor are laminated and pressed together in this state using a roll press, etc., and are pre-cured at a low temperature, followed by main curing at a high temperature to produce a metal base glint board with perfect adhesion. According to actual measurements, the peel strength of the conventional peeling strength was 1.4 to 9/cm, but the peel strength of the laminated product according to the present invention was 1.8 kg/cm.
cm O strength.

In addition, the metal-based glint board according to the present invention has excellent properties such as insulation and moisture resistance, soldering heat resistance, and humidity resistance, and has excellent heat radiation properties, so that it can be used to manufacture printed circuit boards that are highly mounted with electronic components. There are places where you can benefit greatly by performing alms.

[Brief explanation of the drawing]

FIG. 1 is a process diagram showing a disaster example of the present invention, and FIG.
FIG. 3, which is a sectional view showing a metal-based printed circuit board to which the present invention is applied, is a process diagram showing a conventional example. 1...Golden base, 2, 3...Adhesive insulating layer, 4...
・Conductor, 5m, 5b...heat press, 6m+6b...
- (Metal) backing plate, 7m, 7b...Roll press, 8...Hardened insulating layer. Patent applicant: Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] A highly thermally conductive adhesive made by dispersing a highly thermally conductive filler in an adhesive organic polymer is applied to the surface of a metal base to form an adhesive insulating layer, and the adhesive insulating layer is cured. Afterwards, an adhesive layer made of the above-mentioned highly thermally conductive adhesive or an equivalent highly thermally conductive adhesive is formed on the upper surface of this cured adhesive insulating layer, and a conductor is crimped onto the upper surface while this adhesive layer is uncured. A method for manufacturing a metal-based printed circuit board, characterized in that the adhesive layer is transformed into a cured insulating layer by laminating the two substrates together and performing a two-step thermosetting process of preliminary curing and main curing.