JPS58213493A - Electrically insulating board - 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 The present invention relates to electrically insulating substrates intended for heat dissipation, voltage withstand properties, and machinability.

Conventionally, circuit boards that include parts that generate heat, and electrically insulating boards that require bending or drawing processing,
The substrate used is a metal plate such as an aluminum plate or a steel plate, after surface treatment, a synthetic resin-based adhesive insulating layer is provided, and a metal foil such as copper foil is bonded by heat and pressure. However, when such circuit boards are integrated by heating and pressurizing, the synthetic resin may flow out and the thickness of the insulating layer tends to be uneven, resulting in a decrease in the reliability of the heat and pressure resistance characteristics. This has the disadvantage that the surface of the aluminum plate is significantly reduced, and the aluminum plate surface treated with alumite tends to crack when heated. Therefore, the reliability of `` as an electrically insulating substrate is extremely low. In order to improve these shortcomings, a circuit board has been developed in which a glass base material such as woven or non-woven glass fiber is interposed between an electrically insulating layer made of synthetic resin. Although the generation and non-uniformity of the insulating layer are improved, bubbles tend to exist in the insulating layer, and when the voltage withstands.

It cannot be said that the electrical reliability is good, and in order to improve this reliability, the insulating layer must be made significantly thicker.

However, in this type of electrically insulating substrate, it is natural that a thin insulating layer is desirable from the point of view of heat dissipation, and when the glass substrate is in direct contact with a metal plate, bending, Due to the drawing process or the like, the glass base material may break or cracks may occur in the insulating layer, resulting in a decrease in the reliability of the insulating substrate.

This invention was made in view of the current situation, and consists of forming a synthetic resin electric insulating layer on at least one side of a metal plate using a powder coating method, and applying a synthetic resin layer on top of this using a glass paper cloth. The present invention provides an electrically insulating substrate characterized by forming a resin-based electrically insulating layer, and an electrically insulating substrate characterized by further forming an electrically conductive layer on the electrically insulating substrate. The details are described below.

First, the gold plate used in this invention is usually an aluminum plate, iron plate, or stainless steel plate, and the surface of these metal plates is cleaned by mechanical, chemical, or electrochemical treatment. Next, examples of the synthetic resin applied to the surface of this metal plate include thermosetting resins such as epoxy resin and polyester resin, but powder electrostatic coating is generally used to apply these resins. After electrostatic coating, the metal plate is usually heated to 120-250℃ in a drying oven.
The metal plate is heated for 5 to 60 minutes to form a synthetic resin electrical insulation layer on the surface of the metal plate. To improve the thermal conductivity of this electrically insulating layer, Al2O3, Bed.

Metal oxides such as 5in2, BN, AIN, Si3N4
It is recommended to mix metal nitrides such as SiC, and metal carbides such as SiC.In order to improve mechanical strength, machinability, and electrical properties, it is highly effective to mix mica group compounds.

The thickness of the electrically insulating layer thus formed is 30 to 30 mm.
300 μm is preferable. This is because if it is thinner than 30 μm, there is a risk that the reliability of withstand voltage characteristics will be reduced, and if it is thicker than 300 μm, there is a risk that the mechanical or thermal strength of the insulating layer will be reduced. In order to further improve the withstand voltage characteristics, it is desirable to laminate multiple layers through multiple steps even when forming electrical insulating layers of the same thickness. For example, to obtain an electrical insulating layer with a thickness of 100 μm, It is much better to apply two 50 μm layers for a total layer thickness of 100 μm than to apply a 100 μm thick layer in one coat.

Next, on the insulating layer formed by the above method, a synthetic resin electrical insulating layer with a glass paper cloth interposed therein,
The synthetic resin used here is preferably a thermosetting resin such as epoxy resin, polyester resin, or phenol resin, and the glass paper cloth has a thickness of 30 to 180 μm.
m is common, and in the case of glass woven fabric, plain weave,
Any type of satin weave may be used. Spraying, dipping, etc. can be used to coat such glass paper cloth with synthetic resin, but it is preferable to apply it using a coating machine that is conventionally used when manufacturing electrically insulating laminates. A prepreg is produced by heating and drying, which is superimposed on an electrically insulating layer formed by a powder coating method, and then heated and pressed to form a composite electrically insulating layer. Furthermore, if necessary, a conductor may be formed by simultaneously overlapping metal foils such as copper foil, or a conductor layer may be formed by an additive method or the like after forming an electrically insulating layer.

In this way, the electrically insulating base plate according to the present invention can be obtained, but since the electrically insulating layer is first formed on the surface of the metal plate by powder coating, the electrically insulating layer is coated with glass paper cloth. Compared to the case where only a single insulating layer is formed, the generation and inclusion of air bubbles, which cause a decrease in withstand voltage characteristics, are significantly reduced.Furthermore, since the coating method is powder coating, the thickness of the insulating layer can be adjusted arbitrarily. It can be coated over and over again if necessary. Furthermore, since a synthetic resin-based electrical insulating layer is formed on this insulating layer via a glass paper cloth, the mechanical strength and reliability of the electrical insulating layer can be improved.

Furthermore, as is clear from the shape of the electrical insulating layer of this invention, since the lath paper cloth is not in direct contact with the metal plate, it has the advantage that it can be easily bent, drawn, etc., and this is the significance of this invention. is extremely large.

Examples and comparative examples are shown below.

[Example 1] One side of a 1.5 mm thick aluminum plate whose surface had been chemically treated was coated with epoxy resin powder and heated at 180°C.
The bake cured for 30 minutes. - The thickness of the insulating layer formed at this time was 100 μm. Next, three layers of 70 μm glass cloth prepreg impregnated with epoxy resin were superimposed on this insulating layer, and heated and pressed at 160° C. for 30 minutes to obtain an electrically insulating substrate. The thickness of the insulating layer obtained is an actual value measured using a microscope, and the breakdown voltage and bending (
90°) The measurement results of the processability characteristics are summarized in the table.

Table [Example 2] Thickness of mechanically polished surface 1. Q mm iron plate (SI)
Both sides of C2) are coated with epoxy resin powder coating,
It was cured by baking at 180° C. for 15 minutes. The thickness of the electrically insulating layer formed at this time was 100 μm. Next, one side of this insulating layer was impregnated with 100 μm epoxy resin.
A sheet of glass cloth was placed thereon, and a 35 μm copper foil was further placed on top of the glass cloth, and heated and pressed at 160°C for 30 minutes to obtain an electrically insulating substrate. Various properties of the obtained insulating substrate were measured in the same manner as in Example 1, and the results are also listed in the table.

[Example 3] One side of a 2 mm thick aluminum plate whose surface had been chemically treated was coated with epoxy resin powder and heated at 180°C for 3
Baking for 0 minutes cured. At this time, the thickness of the insulating layer is 70μ
It was m. Next, on top of this insulating layer, two sheets of 70 μm glass cloth impregnated with epoxy resin were superimposed, and
'C130 minutes of heating and pressing was performed to obtain an electrically insulating substrate. Various properties of the obtained insulating substrate were measured in the same manner as in Example 1, and the results are also listed in the table.

[Comparative Example 1] Aluminum sea urchin 2::Z2'7':::;:'8&:::bS with a thickness of l and 5 mm whose surface was chemically treated
, o 1'' was heated and pressed at 60° C. for 30 minutes to obtain an electrically insulating substrate.

Various properties of the obtained insulating substrate were measured in the same manner as in Example 1, and the results are also listed in the table.

[Comparative Example 2] On both sides of a 1 mm thick iron plate (SPC2) whose surface was mechanically polished, one sheet of 100 μm glass cloth prepreg impregnated with epoxy resin was superimposed on one side and two sheets on the other side. Then, a 35 μm thick copper foil was placed and heated and pressed at 160° C. for 30 minutes to obtain an electrically insulating substrate. Regarding this insulating substrate, various properties were measured in the same manner as in Example 1, and the results are also listed in the table.

[Comparative Example 3] Three sheets of 70 μm glass cloth prepreg impregnated with epoxy resin were layered on one side of a 2 mm thick aluminum plate whose surface had been chemically treated, and heated at 160° C. for 30 minutes to form an electrically insulating substrate. Obtained. Various properties of this insulating substrate were measured in the same manner as in Example 1, and the results are also shown in the table.

As is clear from the table above, the electrical insulating board according to the present invention was found to have excellent withstand voltage characteristics and excellent bending workability.

Patent applicant Risho Kogyo Co., Ltd.

Claims (2)

[Claims] (1) A synthetic resin electrical insulating layer is formed on at least one side of the metal plate by powder coating, and a ζ synthetic resin electrical insulating layer is further formed on this via glass paper cloth. Electrical insulation board. (2) A synthetic resin-based electrical insulating layer is formed on at least one side of the metal plate by powder coating, a synthetic resin-based electrical insulating layer is formed on this using a glass paper cloth, and an electrically insulating layer is formed on this using a glass paper cloth. An electrically insulating substrate characterized by forming a conductor layer.