JPS6349920B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a hybrid integrated circuit board, and particularly to a hybrid integrated circuit board having excellent heat dissipation properties. (Prior art) Conventionally, an adhesive layer made of an organic polymer compound such as an epoxy resin with a thickness of several tens of micrometers is provided on a metal substrate such as aluminum, iron, or iron-nickel alloy, and then copper foil, etc. A hybrid integrated circuit board to which conductive metal foil is attached is known;
No. 25756 and JP-A No. 56-62388 disclose composite materials in which a conductive metal thin layer is provided on an adhesive layer containing 60% by weight or less and 60 to 80% by weight of insulating and thermally conductive powder, respectively. Substrates for integrated circuits have been proposed. However, such circuit boards still do not provide sufficient heat dissipation, which is a hindrance to increasing the density of high-power integrated circuits. (Problems to be Solved by the Invention) The purpose of the present invention is to solve these drawbacks, and is to provide a hybrid integrated circuit board containing 60 to 65 volume % of insulating and thermally conductive powder. Furthermore, by interposing an adhesive containing a coupling agent between the metal substrate and the conductive metal thin layer, it has sufficient adhesive strength and has better thermal conductivity than conventional metal substrates. The present invention aims to provide a substrate for hybrid integrated circuits. (Means for Solving the Problems) That is, the present invention provides a metal substrate, an adhesive layer provided on at least one main surface of the metal substrate, and a conductive metal thin layer provided on the adhesive layer. A hybrid integrated circuit board comprising an adhesive layer containing 60 to 65% by volume of aluminum oxide (hereinafter referred to as Al ₂ O ₃ ) and a silane coupling agent and/or a titanate coupling agent. characterized by something. Embodiments of the present invention will be described below with reference to the drawings.
First, as shown in the drawings, the hybrid integrated circuit board of the present invention has a metal substrate 1 made of aluminum, iron, iron-nickel alloy, etc., and has an insulating property and excellent thermal conductivity provided on this substrate. It is composed of an adhesive layer 3 containing 60 to 65% by volume of Al ₂ O ₃ powder 2 and a coupling agent, and a conductive metal thin layer 4 made of, for example, copper foil provided on this adhesive layer. be. The Al ₂ O ₃ powder 2 used for the adhesive layer of the hybrid integrated circuit board (hereinafter referred to as circuit board) of the present invention has an average particle size of 0.2 to 50 μ, a specific resistance of 10 ^{to 10} Ω·cm or more, and a thermal conductivity of 0.05 cal. /cmsec℃ or higher. If the average particle size of the Al ₂ O ₃ powder is less than 0.2μ, the adhesive will exhibit thixotropic properties, and the adhesive resin layer using this powder will be prone to voids, and the withstand voltage of the insulating layer will be reduced. to disappear,
Furthermore, since the viscosity of the adhesive becomes extremely high, a large amount of solvent must be used when coating a metal plate with the adhesive, which is not preferable because the residual solvent causes problems with withstand voltage. Also, on the other hand
If the powder exceeds 50μ, the thickness of the insulating layer becomes large and the thermal resistance increases. The reason why the specific resistance is set as above is because if the specific resistance is less than 10 ¹⁰ Ωcm, the insulation property will be poor. Further, the adhesive for the circuit board of the present invention has good heat resistance, chemical resistance, moisture resistance, and flexibility, and specific examples include phenol resin, epoxy resin, phenol-butyral resin, silicone resin, Examples include polyimide resin, and these
More than one species can be used together. The adhesive used as the adhesive layer of the circuit board of the present invention facilitates the filling of 60% by volume or more of Al ₂ O ₃ powder, and also contains a coupling agent, concrete, etc. as an additive for activating the adhesive surface. For example, a silane coupling agent and/or a titanate coupling agent and various primers include a carboxylic acid alcohol primer, a phosphoric acid primer, and the like. Among these additives, especially in the absence of a coupling agent, it is practically impossible to achieve the high powder filling according to the present invention, and the adhesive strength as an adhesive is not sufficient. These additives can be used by attaching them to the surface of Al ₂ O ₃ powder, or they can be used during the production of adhesives.
It can be added and used at the same time when adding and dispersing Al ₂ O ₃ powder. According to the inventor's experiments, it contains 0.5% by volume of silane coupling agent.
The adhesive with high Al ₂ O ₃ powder filling has improved adhesion to aluminum by approximately 1.5 to 2 times compared to the case without additives, and its adhesive strength in tensile shear is 150 to 200 Kg/cm ²
It was hot. Please note that these additives are used in adhesives.
The higher the filling of Al ₂ O ₃ powder, the more significant the difference (physical and physical properties) from the case without additives becomes, and it becomes necessary to perform a thin and uniform surface treatment on the surface of the Al ₂ O ₃ powder. The highly filled Al ₂ O ₃ powder adhesive used in the circuit board of the present invention is manufactured by adding the various additives described above, but the particle size and distribution of the highly filled Al ₂ O ₃ powder in the adhesive are It is important to do so. In other words, the smaller the particle size of these Al ₂ O ₃ powders, the more likely they are to cause secondary agglomeration, and even within the particle size range that can be used in the present invention, secondary agglomeration occurs. must be solved to uniformly disperse the Al ₂ O ₃ powder into the adhesive. Unless this can be achieved, the amount of 60-65% by volume indicated in the present invention
It is not possible to coat the adhesive with high _{Al 2} O ₃ powder filling on the metal substrate referred to in the present invention in a uniform thin _layer state. For example, when using the inventor's high shear mechanical dispersion machine, if the dispersion conditions are poor, even if Al ₂ O ₃ powder with a particle size of 50μ or less is used, the presence of particles larger than 100μ can be detected by the crush gauge. However, when dispersed at the optimum shear, no particles larger than 100μ were observed, and it was possible to form an adhesive resin layer with a uniform coating surface of 60μ in thickness on the aluminum substrate. moreover
When highly loaded with Al ₂ O ₃ powder, it is necessary that the particle size distribution of the Al ₂ O ₃ powder is wide, thereby suppressing the increase in viscosity. The curing agent in the adhesive used in the adhesive layer of the circuit board of the present invention is preferably an aromatic amine type curing agent, which has a high heat distortion temperature and good adhesion that cannot be obtained with an aliphatic amine type curing agent. An adhesive layer is obtained whose thermal conductivity is also high. Therefore, it is ideal for high heat resistance and high heat conduction substrates. At first glance, the relationship between the curing agent and thermal conductivity may seem unrelated, but when the Al ₂ O ₃ powder is highly loaded as in the present invention, the crosslinking density of the cured product differs depending on the curing agent. For,
This is thought to affect thermal conductivity. (Example) Example and Comparative Example Average particle size of 1.6μ and average particle size of bisphenol A type liquid epoxy resin surface treated with the above additive
A mixture of 30μ Al ₂ O ₃ powder at a weight ratio of 1:1 and an aromatic amine curing agent were kneaded using a high shear mechanical disperser, and the thermal conductivity of the cured product was measured.
It was shown to. Next, the highly thermally conductive adhesive was applied to a polished 2 mm thick aluminum substrate to a film thickness of 50 μm. After heating this substrate to the B stage, a 35μ back-treated copper foil was laminated using a hot roll, and its peel strength and through-layer withstand voltage were measured according to JISC-6481 and JISC-2110, respectively. . The results are shown in Table 2.

【table】

[Table] As shown above, when the volume is less than 60%, heat dissipation is insufficient, and when it exceeds 65%, the withstand voltage decreases due to the generation of voids, and the adhesive strength also decreases. (Effects of the Invention) As described above, according to the present invention, a hybrid integrated circuit board having good heat dissipation properties and high withstand voltage can be obtained, and high-density packaging can be performed.

[Brief explanation of drawings]

The drawings are cross-sectional views of embodiments of the invention. Code, 1... Metal substrate, 2... Al ₂ O ₃ powder, 3
...adhesive layer, 4...metal thin layer.

Claims (1)

[Claims] 1. In a hybrid integrated circuit board comprising a metal substrate, an adhesive layer provided on at least one main surface of the metal substrate, and a conductive metal thin layer provided on the adhesive layer, the adhesive layer is oxidized. 1. A board for a hybrid integrated circuit, characterized in that it is an adhesive comprising 60 to 65% by volume of aluminum and a silane coupling agent and/or a titanate coupling agent.