JPH06334287A - Aluminum-based printed wiring board and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a favorable adhesiveness between an insulating adhesive layer and a base aluminum board and between the adhesive layer and metal foil, and suppress the degradation in withstand voltage characteristic due to long time heating. CONSTITUTION:A base aluminum board whose surfaces have been subjected no treatment or anodization, is bonded with a sheet of metal foil, with in-between an insulating adhesive layer, containing silica or alumina, obtained by treating thermosetting resin with silane coupling agent. Thus an aluminum-based printed wiring board is manufactured. The surface of the base aluminum board to be in contact with the insulating adhesive layer, is coated with silane coupling agent. That of the metal foil to be in contact with the insulating adhesive layer is also coated with silane coupling agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum base printed wiring board in which an aluminum plate used in the field of electronic equipment is used as a base material, and a metal foil such as a copper foil is attached to the base material via an insulating adhesive layer. The present invention relates to a manufacturing method thereof.

[0002]

2. Description of the Related Art Aluminum-based printed wiring boards have a base material such as an aluminum plate with no surface treatment or an aluminum plate with an alumite-treated surface, and a metal foil such as copper foil on this base material, which has a high heat dissipation property. It is formed by pasting together via a thermosetting resin-based insulating adhesive layer containing an inorganic filler of particles. As a method for producing this aluminum base printed wiring board, generally, an insulating adhesive is applied to a metal foil with a roll coater or the like, and this is preliminarily cured (B = Stage state), and then the base A method of bringing it into close contact with an aluminum plate and applying pressure and heat curing is used. At this time, in order to increase the contact area with the insulating adhesive layer and enhance the adhesiveness, the aluminum plate of the base substrate is a metal foil that is roughened by alumite-treating the surface on the adhesive side. Also in this case, a copper foil or the like whose adhesive surface side was roughened by an electrolytic deposition method or the like was used.

[0003]

Aluminum-based printed wiring boards are used in intelligent power modules and the like in the field of power electronics, and are recently expected to be used in automobiles and other applications. As mounting and high-density mounting progress, even better heat dissipation and heat resistance than before are required.
Due to such requirements, an inorganic filler is generally blended in the insulating adhesive to enhance heat dissipation, and a thermosetting resin is often used as the base resin.

However, an insulating adhesive containing an inorganic filler, which uses a resin having high heat resistance as a thermosetting resin which is the base of the insulating adhesive, has poor adhesiveness to the alumite surface and is hardened after pressure and heat curing. However, there was an unbonded portion, peeling occurred, and a good adhesion state with the base material could not be obtained. Further, the adhesion to the metal foil was poor and a high peel strength value could not be obtained. Recently, JP-B-63-49920 proposes to obtain a hybrid integrated circuit substrate having sufficient adhesive strength by mixing a silane coupling agent and / or a titanate coupling agent in an insulating adhesive. . However, even if this technique is applied to an aluminum-based printed wiring board, if the base of the insulating adhesive is a heat-resistant thermosetting resin, particularly a bismaleimide triazine resin, the effect cannot be sufficiently obtained. Further, this insulating adhesive has a large flow property after pressure and heat curing, which causes a problem that it is difficult to uniformly control the film thickness.

[0005]

Means for Solving the Problems The inventors have found that the adhesiveness to a base aluminum plate and a metal foil such as a copper foil, which is observed when an insulating adhesive using a heat-resistant thermosetting resin is used. As a result of earnest research on the point of improving the adhesiveness, the film thickness of the insulating adhesive layer after pressure and heat curing is almost uniform, and the adhesiveness between the insulating adhesive layer and the base aluminum plate and the metal foil is good. The inventors of the present invention have found a method for producing an aluminum-based printed wiring board and have reached the present invention. That is, the method of the present invention is a surface-untreated or alumite-treated base aluminum plate with an insulating adhesive layer formed by mixing silica or alumina treated with a silane coupling agent to a thermosetting resin. In manufacturing an aluminum-based printed wiring board in which metal foils are integrally laminated, a surface-untreated or alumite-treated aluminum plate with a silane coupling agent applied as the base aluminum plate to the insulating adhesive layer When,
As the metal foil, a metal foil having a silane coupling agent applied to the adhesive surface of the insulating adhesive layer is used. In particular, the insulating adhesive layer is formed by interposing an insulating adhesive layer obtained by blending silica or alumina treated with a silane coupling agent with a thermosetting resin mainly containing the bismaleimide triazine resin produced by the method of the present invention. The aluminum base printed wiring board, which is made by laminating a metal foil and a base aluminum plate that is untreated or anodized with a silane coupling agent applied to the adhesive surface, has excellent heat resistance and withstand voltage value. The retention rate was also high. The amount of silica or alumina that has been treated with a silane coupling agent to be added to the insulating adhesive is
It is about 60 to 80 wt% of the entire insulating adhesive.

[0006]

In the present invention, the silica or alumina treated with the silane coupling agent in the insulating adhesive has a vinyl group on its surface, and this vinyl group acts as a reaction accelerator for the base resin. The curing reaction is accelerated, so that the viscosity of the adhesive increases upon pressurization, and the flowability of the coating film after pressurization / heating is suppressed. In addition, since the silane coupling agent is present on the bonding surface of the aluminum plate and the metal foil, the coupling layer is interposed between the aluminum plate and the metal foil and the insulating adhesive layer that is organic, and the coupling layer is inorganic. An oxane bond is formed between an aluminum plate and a metal foil, and the organic functional group of the silane coupling agent reacts with the organic insulating adhesive layer to form a crosslinked bond. With the aluminum plate as the base material, the adhesive force with the insulating adhesive layer is improved, and with the metal foil, the adhesive force with the insulating adhesive layer is further improved. In particular, as an insulating adhesive, an aluminum-based printed wiring board manufactured by using an insulating adhesive that is a thermosetting resin mainly composed of a bismaleimide triazine resin and a silica or alumina compounded with a silane coupling agent treatment is mixed The heat resistance was excellent and the withstand voltage value retention rate was also high.

[0007]

EXAMPLES The present invention will be described below with reference to examples. Example 1 A copper foil was prepared by roughening the adhesive surface and applying a silane coupling agent to the rough surface. Next, using a roll coater, an insulating adhesive containing 65 wt% of crystalline silica surface-treated with a silane coupling agent in a liquid bismaleimide triazine resin as a base resin is applied to the copper foil to a coating thickness of 100 to 120 μm. did. This was heated at 120 ° C. for 30 minutes to be temporarily cured to prepare a prepreg. The surface-untreated aluminum plate having a thickness of 1 mm, which had a silane coupling agent applied to the adhesive surface, and the prepreg were superposed, and heated and pressed under vacuum at a temperature of 200 ° C. and a surface pressure of 40 kg / cm ² . With respect to the produced aluminum-based printed wiring board, the copper foil was peeled off and the insulating adhesive layer was visually observed. The non-bonded portion or the one having uneven adhesiveness was indicated as poor, and the one having good adhesiveness was indicated as good. Regarding the adhesion of the copper foil, a 1 cm wide pattern was formed by etching.
A 0 degree peel test was performed. Regarding the film thickness of the insulating adhesive layer, the film thickness value was measured and the difference between the minimum value and the maximum value was calculated. For the evaluation of heat resistance, the withstand voltage value after standing for 1000 hours in a constant temperature bath at 200 ° C. was measured, and the characteristic retention rate with respect to the initial value was calculated. The results obtained are shown in Table 1.

(Example 2) Example 1 except that a mixture of a liquid bismaleimide triazine resin and a bisphenol type epoxy resin (mixing ratio 70/30) was used as the base resin.
An insulating adhesive was prepared in the same manner as in. An aluminum-based printed wiring board was produced in the same manner as in Example 1 except that this insulating adhesive was used. Various characteristics of the produced aluminum-based printed wiring board were examined in the same manner as in Example 1. The results obtained are shown in Table 1.

Example 3 An insulating adhesive was prepared in the same manner as in Example 1 except that a liquid bismaleimide triazine resin obtained by mixing 5 wt% of a silane coupling agent with a base resin was used. An aluminum-based printed wiring board was produced in the same manner as in Example 1 except that this insulating adhesive was used. Regarding the manufactured aluminum-based printed wiring board, Example 1
Various characteristics were investigated in the same manner as in. The results obtained are shown in Table 1.

(Example 4) The same procedure as in Example 1 was carried out except that an insulating adhesive prepared by mixing 65 wt% of the total amount of alumina surface-treated with a silane coupling agent into a liquid bismaleimide triazine resin as a base resin was used. To produce an aluminum-based printed wiring board. Various characteristics of the produced aluminum-based printed wiring board were examined in the same manner as in Example 1. The results obtained are shown in Table 1. (Example 5) Insulation prepared by using a mixture of a liquid bismaleimide triazine resin and a bisphenol type epoxy resin (mixing ratio 70/30) as a base resin and compounding 65% by weight of alumina surface-treated with a silane coupling agent. An aluminum-based printed wiring board was produced in the same manner as in Example 1 except that an adhesive was used. Various characteristics of the produced aluminum-based printed wiring board were examined in the same manner as in Example 1. The results obtained are shown in Table 1.

Example 6 A mixture of a liquid bismaleimide triazine resin and a polyalkylene oxide adduct of novolac phenol with a base resin (mixing ratio 70/3).
0), an insulating adhesive prepared by mixing 65 wt% of crystalline silica surface-treated with a silane coupling agent, and a silane coupling agent applied to the adhesive surface to a thickness of 1 m.
An aluminum-based printed wiring board was produced in the same manner as in Example 1 except that the surface-anodized aluminum plate of m was used. Various characteristics of the produced aluminum-based printed wiring board were examined in the same manner as in Example 1. The results obtained are shown in Table 1.

Example 7 An aluminum base printed wiring board was produced in the same manner as in Example 1 except that an insulating adhesive prepared by using a polyimide resin as the base resin was used. Regarding the manufactured aluminum-based printed wiring board, Example 1
Various characteristics were investigated in the same manner as in. The results obtained are shown in Table 1. (Example 8) Example 6 except that an insulating adhesive prepared by using a bisphenol type epoxy resin as a base resin was used.
An aluminum-based printed wiring board was produced in the same manner as.
Various characteristics of the produced aluminum-based printed wiring board were examined in the same manner as in Example 1. The results obtained are shown in Table 1.

(Example 9) Example 6 was repeated except that a liquid bismaleimide triazine resin was used as a base resin and an insulating adhesive prepared by mixing 65 wt% of alumina surface-treated with a silane coupling agent was used. Similarly, an aluminum-based printed wiring board was produced. Various characteristics of the produced aluminum-based printed wiring board were examined in the same manner as in Example 1. The results obtained are shown in Table 1.

(Comparative Example 1) A bisphenol type epoxy resin was used as a base resin, and crystalline silica was contained at 65 wt% of the whole.
Aluminum was used in the same manner as in Example 1 except that an insulating adhesive prepared by blending was used, and a copper foil having no adhesive surface treatment and an aluminum plate having a thickness of 1 mm on which no silane coupling agent was applied were used. A base printed wiring board was produced. Various characteristics of the produced aluminum-based printed wiring board were examined in the same manner as in Example 1. The results obtained are shown in Table 1. (Comparative Example 2) Aluminum base print was carried out in the same manner as in Example 1 except that a copper foil having no adhesive surface treatment was used and a 1 mm-thick surface-anodized aluminum plate having no silane coupling agent applied to the adhesive surface was used. A wiring board was produced. Various characteristics of the produced aluminum-based printed wiring board were examined in the same manner as in Example 1. The results obtained are shown in Table 1.

Comparative Example 3 A liquid bismaleimide triazine resin prepared by mixing 5 wt% of a silane coupling agent with a base resin was used, and an insulating adhesive prepared by mixing 65 wt% of alumina was used. With treated copper foil,
1mm thickness without applying silane coupling agent on the adhesive surface
An aluminum-based printed wiring board was produced in the same manner as in Example 1 except that the surface-anodized aluminum plate was used. Various characteristics of the produced aluminum-based printed wiring board were examined in the same manner as in Example 1. The results obtained are shown in Table 1.

Comparative Example 4 An insulating adhesive prepared by blending 65 wt% of crystalline silica with a liquid bismaleimide triazine resin as a base resin was used, and a copper foil having no adhesive surface treated and silane coupling on the adhesive surface were used. Thickness without applying agent 1
An aluminum-based printed wiring board was produced in the same manner as in Example 1 by using a surface-anodized aluminum plate having a thickness of mm. About the manufactured aluminum base printed wiring board,
Various characteristics were examined in the same manner as in Example 1. The results obtained are shown in Table 1.

[0017]

[Table 1] Note: The withstanding voltage value retention ratios of Comparative Examples 2 to 5 cannot be measured because the copper foil peeled from the aluminum plate.

As is clear from Table 1, in the products of Examples 1 to 9 according to the method of the present invention, the adhesiveness between the aluminum plate and the insulating adhesive layer is good, and the products with the insulating adhesive layer of the copper foil are good. Adhesion is also 90kg peel test, both are 2.0kg / c
It kept a high value of m or more. Further, the variation in the film thickness of the insulating adhesive layer is as small as 10 μm or less.
The withstanding voltage value retention rate after standing for 1000 hours in a thermostatic bath at 00 ° C. was 90% or more of the initial value, which was extremely high. In particular, an aluminum-based printed wiring board manufactured using an insulating adhesive made by blending a silica or alumina treated with a silane coupling agent into a thermosetting resin mainly composed of a bismaleimide triazine resin has excellent heat resistance. The withstand voltage value retention rate was also high. On the other hand, Comparative Example 1
The product had good adhesion between the aluminum plate and the insulating adhesive layer, but the adhesion between the copper foil and the insulating adhesive layer was 1.7k.
The g / cm 3 and withstand voltage value retention ratios were as low as 56% of the initial values. In addition, in Comparative Examples 2 to 4, the adhesion between the aluminum plate and the insulating adhesive layer is poor, and the adhesion of the copper foil to the insulating adhesive layer is 0.9 to 1.1 kg / cm. The adhesive strength was less than half that of the invented method product, and the variation in the thickness of the insulating adhesive layer was as large as 28 to 37 μm. The withstand voltage value retention rate after standing in a thermostatic oven at 200 ° C. for 1000 hours could not be measured because the copper foil peeled off from the aluminum plate during the heating and leaving time.

[0019]

As is apparent from the above examples, according to the method of the present invention, the variation in the film thickness of the insulating adhesive layer is small, and the insulating adhesive layer, the base aluminum plate, the insulating adhesive layer and the metal foil are formed. It is possible to manufacture an aluminum-based printed wiring board that has good adhesive strength with and has little deterioration in withstand voltage characteristics even after being heated for a long time, and its industrial value is extremely large.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Fumiha Osawa 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd.

Claims (2)

[Claims] 1. A base aluminum plate and a metal foil, which are surface-untreated or alumite-treated through an insulating adhesive layer formed by blending a silica or alumina treated with a silane coupling agent in a thermosetting resin. When manufacturing an aluminum-based printed wiring board in which and are integrally bonded together, an aluminum plate coated with a silane coupling agent on the bonding surface with the insulating adhesive layer as the base aluminum plate and an insulating adhesive layer as the metal foil are bonded together. A method for manufacturing an aluminum-based printed wiring board, characterized in that a metal foil having a silane coupling agent applied to its surface is used. 2. Adhesion to an insulating adhesive layer via an insulating adhesive layer made of a thermosetting resin mainly containing a bismaleimide triazine resin and silica or alumina treated with a silane coupling agent. An aluminum-based printed wiring board, characterized in that a base aluminum plate coated with a silane coupling agent and a metal foil are integrally laminated on the surface.