JPH04367763A - Preparation of synthetic resin coated metal plate - Google Patents

Abstract

PURPOSE:To obtain a synthetic resin coated metal plate for a printed circuit board having an insulating layer of uniform quality. CONSTITUTION:A synthetic resin and an inorg. filler are kneaded and subsequently ground to prepare a fine powder which is, in turn, applied to a metal plate by electrostatic painting to form an insulating layer. A metal foil or plate is further placed on the surface of the insulating layer and the insulating layer is compressed under heating and pressure to be unified with the metal foil or plate to obtain a synthetic resin coated metal plate having uniform quality. The insulating layer containing a large amount of the inorg. filler and having uniform quality can be formed by electrostatic painting and a metal core or metal base printed wiring board especially excellent in radiation properties is obtained.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method for manufacturing a synthetic resin-coated metal plate in which an insulating layer made of synthetic resin is provided on the surface of the metal plate, and in particular, a metal core or metal-based printed wiring board with excellent heat dissipation is used. The present invention relates to a method for producing the obtained product.

0002

[Prior art and its issues] In response to the increasing density of electronic devices in recent years, the characteristics required for the printed wiring boards used are becoming more sophisticated. There is a demand for a substrate with excellent heat dissipation properties that can quickly eliminate heat dissipation. As such a substrate, a metal plate is used, and an insulating layer containing an inorganic filler having excellent thermal conductivity is formed on the surface.

[0003] As a method for forming the above-mentioned insulating layer, the insulating layer is formed by applying a synthetic resin powder mixed with a large amount of an inorganic filler having excellent thermal conductivity to one or both sides of a metal plate by electrostatic coating. is being considered. However, with this electrostatic coating method, the mixing ratio of the inorganic filler and synthetic resin powder tends to fluctuate locally, making it difficult to achieve uniform coating.
In addition, during electrostatic coating, the raw materials that were not coated on the metal plate surface were collected and electrostatically coated again, and consideration was given to reusing the raw materials, but due to the uneven mixing ratio, reuse was not possible. There was a problem that I couldn't do it enough.

0004

[Means for Solving the Problems] The present invention involves kneading an inorganic filler and a synthetic resin, pulverizing them into fine powder, and applying the fine powder onto a metal plate by electrostatic coating to form an insulating layer. It has been discovered that the above problems can be solved by this.

The metal plate used in the present invention is made of aluminum, copper, zinc, iron, silicon steel, iron-nickel alloy, etc., and usually has a thickness of about 0.2 to 5.0 mm. This metal plate is preferably subjected to surface treatment, such as chromate treatment, sandblasting, etching, or the like.

[0006] Furthermore, various thermoplastic resins and thermosetting resins can be used as the synthetic resin used for the above-mentioned insulating layer.
In particular, it is preferable to use a heat-resistant thermoplastic resin for applications requiring heat resistance. As the heat-resistant thermoplastic resin, a resin having a flow start temperature of 200° C. or higher and excellent high frequency properties can be suitably used. Specific examples include polysulfone, polyphenylene sulfide, polyetheretherketone, thermoplastic fluororesin, polyetherimide, polyethersulfone, polyamideimide, polyphenylene oxide, and the like. As the thermosetting resin, epoxy resin, polyimide resin, etc. can be used.

Furthermore, various inorganic fillers having excellent thermal conductivity, such as silicon nitride, aluminum nitride, and boron nitride, can be used as the inorganic filler, and they may be used alone or in combination. The above inorganic filler has an average particle size of 0.1
A material with a diameter of ~10 μm can be suitably used, and the amount used may be in the range of 50 to 80% by weight based on the entire composition containing the above-mentioned synthetic resin, and if the amount used is less than 50%, the heat dissipation property will deteriorate If it exceeds 80% by weight, the dispersibility tends to be poor. The inorganic filler can be surface-treated with various coupling agents in order to improve its affinity with the resin.

In the method of the present invention, it is necessary to uniformly knead the above-mentioned synthetic resin and inorganic filler, and the kneading can be carried out using a conventional kneader. In the case of a thermosetting resin, it is necessary to perform kneading under such conditions that the curing reaction stops at the B stage. After kneading, pulverize into fine powder,
The fine powder is applied to one or both sides of a metal plate by electrostatic coating. The pulverization may be carried out using a conventional pulverizer, if necessary under cooling conditions, so that the average particle size of the fine powder after pulverization is in the range of 10 to 100 μm.

[0009] Next, the fine powder is applied onto one or both sides of a metal plate by electrostatic coating. The electrostatic coating method may be a normal electrostatic coating method, and the spraying distance to the metal plate may be adjusted within a range of 5 cm to 1 m, and the coating may be performed under appropriate conditions to achieve a predetermined coating thickness. good. The thickness of the insulating layer after coating varies depending on the required heat dissipation properties, etc., but is preferably about 50 to 300 μm.

When the synthetic resin-coated metal plate of the present invention is used as a printed wiring board, a metal foil or a metal plate is laminated on the surface of the insulating layer formed by the above method. As the metal foil, electrolytic copper foil, rolled copper foil, etc. having a thickness of about 10 to 100 μm can be used. As the metal plate, one having a thickness of about 500 μm or less can be used. Methods of laminating metal foils or metal plates include a method using an adhesive and a method of laminating and integrating the metal foils or plates by heating and pressing without using an adhesive. According to the present invention, a printed wiring board without surface irregularities, pinholes, voids, etc. can be obtained. Further, if the insulating layers are laminated and integrated while compressing the insulating layers by increasing the pressure by heating and pressing, the insulating layers can be made more uniform.

[0011] The present invention will be explained below with reference to Examples.

[Example] Aluminum nitride (average particle size 2.5 μm) as inorganic filler, polyetheretherketone powder (melting point 340°C, average particle size 10.0 μm) as synthetic resin
It was used. Aluminum nitride accounts for 6% of the above raw materials.
After mixing with a mixer so that the concentration was 0% by weight, the mixture was kneaded with a kneader and cooled to form pellets. This pellet-like material was pulverized with a pulverizer to obtain a fine powder with an average particle size of 40 μm. Next, an aluminum plate with a roughened surface (
The above-mentioned fine powder was electrostatically coated on one side of a 250 mm x 250 mm x 3 mm thick sheet. The thickness of the insulating layer after coating is 25
It was 0 μm. Then, the obtained laminate was placed in an electric furnace and heat-treated at 400° C. for 10 minutes.

After the heat treatment, an electrolytic copper foil (thickness: 70 μm) was placed on the surface of the insulating layer and hot pressed for 20 minutes (pressing temperature: 380° C., pressing pressure: 40 kg/cm 2 ). The obtained substrate (insulating layer thickness: 150 μm) had no surface irregularities and had excellent smoothness, and no pinholes or voids were observed in the insulating layer. Furthermore, there was no effect on quality due to reuse of raw materials during electrostatic coating.

[0013]

As described above, according to the manufacturing method of the present invention, the insulating layer containing a large amount of inorganic filler can be made uniform, so that a synthetic resin-coated metal plate with excellent heat dissipation and electrical properties can be obtained. It is highly applicable to metal core or metal base printed wiring boards.

Claims (2)

[Claims] 1. A synthetic resin characterized in that a synthetic resin and an inorganic filler are kneaded and then ground into fine powder, and the fine powder is applied onto a metal plate by electrostatic coating to form an insulating layer. A method for producing a coated metal plate. 2. After kneading the synthetic resin and the inorganic filler, the synthetic resin and the inorganic filler are pulverized into fine powder, and the fine powder is applied onto a metal plate by electrostatic coating to form an insulating layer. A method for manufacturing a synthetic resin-coated metal plate, which comprises placing a foil or metal plate thereon and then applying heat and pressure to compress the insulating layer and integrate the layers.