JPH047296B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of manufacturing an electrically insulating substrate that greatly improves the adhesive strength between an insulating layer and a metal plate and improves heat dissipation characteristics. BACKGROUND ART Conventionally, electrically insulating substrates obtained by laminating a metal foil layer, an insulating layer, and a metal plate in the presence of an adhesive and press-molding them have been widely used, for example, in the fields of electronics and electrical industries. This type of insulating substrate is made by processing the above-mentioned laminate using a heat press machine, usually by about 100%.
It is obtained by press molding at a temperature of about 200°C and a pressure of about 1 to 50 kg/cm ² . At this time, when bonding the insulating layer and the metal plate, the surface of the metal plate is usually degreased or sandblasted. However, with this method, the reliability of adhesion between the insulating layer and the metal plate was low, and defects were likely to occur in tests such as solder resistance and aging. An object of the present invention is to provide a method for manufacturing an electrically insulating substrate that greatly improves the adhesive strength between an insulating layer and a metal plate and also has excellent heat dissipation properties. That is, the present invention provides a method for manufacturing an electrically insulating substrate by laminating a metal foil layer, an insulating layer, and a metal plate with an adhesive interposed, and press-molding them using a hot press machine.
The present invention relates to a method for manufacturing an electrically insulating substrate, characterized in that the surface of the metal plate is pretreated using a combination of sandblasting and etching. In the present invention, when bonding an insulating layer and a metal plate with an adhesive, the surface of the metal plate is subjected to both sandblasting and etching processes in advance to greatly improve the adhesive strength and at the same time improve heat dissipation properties. I found something that could be improved. The reason why the above effect is achieved is not clear, but it is assumed that the improvement in adhesive strength is related to the anchoring effect, the formation of chemical bonds through surface activation, and the improvement in heat dissipation is related to the increase in surface area. be done. Next, the present invention will be explained with reference to the drawings. 1st
The figure is an enlarged cross-sectional view of an electrically insulating substrate obtained by the method of the present invention, and the surface of the metal plate 3 has been subjected to both sandblasting and etching treatments.
1 is a metal foil layer, and 2 is an insulating layer. In the present invention, any metal plate can be used, such as ordinary aluminum plates, various corrosion-resistant aluminum plates, iron plates, steel plates, copper plates, nickel plates, stainless steel plates, brass plates, silicon steel plates, duralumin plates, etc. Although it is possible, an aluminum plate is particularly preferable. The thickness of this metal plate is usually preferably 0.3 mm or more, particularly preferably about 0.5 to 5 mm, from the viewpoint of self-retainability. Next, various resins can be used to form the insulating layer, such as epoxy resin, phenol resin, silicone resin, polyester resin,
Polyesterimide resin, polyamideimide resin, polyimide resin, polysulfone resin,
Examples include phenoxy resin. The thickness of the insulating layer depends on the insulation properties, heat dissipation properties, etc., but is usually approximately
The thickness is preferably 150 μm or less, particularly preferably about 50 to 100 μm. Various metal foils can be used, but copper foil, aluminum foil, nickel foil, etc. are preferred from the viewpoint of etching properties, electrical conductivity, ease of plating, etc. The thickness of the metal foil layer is usually preferably about 1 to 150 .mu.m, particularly preferably about 5 to 50 .mu.m, in view of etching accuracy during processing of the obtained substrate. In the present invention, press working is performed with an adhesive present between the metal plate and the insulating layer and between the insulating layer and the copper foil. Various types of adhesives can be used, but those with heat resistance are particularly preferred, such as epoxy adhesives (Chiver Geigy, Adaldite LY556) and silicone adhesives (Toshiba Silicon, Inc., Adaldite LY556).
YR-3286), epoxy-nylon type (3M Company,
AF-42), imide type (Mitsubishi Gas Chemical Co., Ltd., BT Resin), etc. can be used. Alternatively, the insulating layer forming resin can be directly cured and formed on the metal plate and/or the metal foil layer to bond the two, with or without using a curing agent. In the present invention, sandblasting and etching can be performed by known methods. Sandblasting can be performed, for example, by degreasing a metal plate and then hitting the surface of the aluminum plate with compressed air using an abrasive such as iron powder, diamond sand, or alumina. For etching, use an etching solution such as H ₃ PO ₄ (66.5%), H ₂ SO ₄ (4.5%), HNO ₃ (2.8
%), H ₃ BO ₃ (0.5%), etc., and is usually immersed in these solutions at a temperature of 95±10° C. for about 1 to 3 minutes. The insulating substrate of the present invention can be manufactured by a known method, such as the Hot-Hot method or the Cold-Hot method.
It can be manufactured by the Hot-Cold method. To show an example of the Hot-Hot method, for example, a press machine is heated to about 190℃, the hot plate and cushion pad are taken out, a sample (object to be pressed) is inserted into the press machine, and about 40 kg/cm The insulating substrate of the present invention can be manufactured by applying a pressure of ² and holding for about 5 minutes, and then removing the load. The electrically insulating substrate of the present invention is suitable for various integrated circuit boards, printed wiring boards, heat sinks, and others. A detailed explanation will be given below with reference to examples. Example 1 A 100 μm thick glass cloth was placed on an aluminum plate (2.2 mm thick) that had been subjected to sandblasting and etching treatment, and a mixed solution of 75 parts by weight of epoxy resin and 35 parts by weight of methyl ethyl ketone solution of an amine hardener was placed on top of this. After coating and drying at 120℃ for 10 minutes, 35μ
Place m-thick electrolytic copper foil at a pressure of 5Kg/cm ² and a temperature of 150℃.
The insulating substrate of the present invention was obtained by press molding at ℃ for 60 minutes, unloading, and cooling. Adhesive strength test T between the insulating layer and the aluminum plate of the electrically insulating substrates (Comparative Examples 1 to 4) obtained in the same manner as in Example 1 and the following various surface treatments were applied to the aluminum plate
The peel strength (90° peel, Kg/cm) was measured and the results are shown in Table 1. Comparative example 1 No treatment 〃 2 Alumite treatment (6μm) 〃 3 〃 (15μm) 〃 4 Sandplast treatment Table 1 T peel strength Example 1 5.2 Comparative example 1 3.0 〃 2 3.5 〃 3 3.5 〃 4 4.5 Example 2~ 4 and Comparative Example 2 Using silica sand with an average particle size of 0.5 mm, the surface of the aluminum plate was sandblasted at a pressure of 6 kgf/cm ² for 10 minutes, and then etched under the conditions shown in Table 2. An insulating substrate was obtained in the same manner as in Example 1. Note that Comparative Example 2 was obtained by omitting the etching process in the above. Next, the average adhesive strength of the 100 insulating substrates obtained was measured at room temperature and at 100°C in the same manner as in Example 1.
Measured in points. In addition, as the adhesion defect rate, when measured at room temperature, the occurrence rate of T peel strength of less than 2.0 kg/cm is shown, and when measured at 100°C, the occurrence rate of less than 1.0 kg/cm is shown. The results are shown in Table 2.

[Table] Examples 5 to 6 and Comparative Example 3 The surface of the aluminum plate was sandblasted for 8 minutes in the same manner as in Example 2, and then etched under the conditions shown in Table 3. Next, apply imide adhesive (Mitsubishi Gas Chemical Co., Ltd.) on both sides.
A 100 μm thick polyimide film having a BT resin layer was further placed on top of a 35 μm thick electrolytic copper foil and press-molded at a pressure of 5 Kg/cm ² and a temperature of 220°C for 60 minutes, unloading, It was cooled to obtain an insulating substrate. Note that Comparative Example 3 was obtained by omitting the etching process in the above. Next, the average adhesive strength and adhesion failure rate of the 100 obtained insulating substrates were measured in the same manner as in Example 2.
The results are shown in Table 3.

【table】

[Table] As is clear from Tables 2 and 3, when both sandblasting and etching are performed, it is sufficient even at room temperature and high temperature (this means that various processing and operations of insulating substrates are performed at high temperatures). It can be seen that the adhesive strength is high, and there are no adhesive defects at both temperatures, which is industrially advantageous. On the other hand, in the case of only sandblasting, even if the average strength at room temperature is fair, there are some problems with production stability due to the occurrence of defective products, and this tendency becomes even stronger at high temperature adhesive strength. The reason why the adhesive strength is high and the production stability is good in the present invention is that relatively large irregularities are first formed on the surface of the Al plate by sandblasting, and then by etching, while maintaining the irregularities,
This is thought to be due to the double anchor effect, which creates a double structure in which fine irregularities are added to the entire uneven surface. Heat Dissipation Test In order to evaluate the heat dissipation properties of the electrically insulating substrates of Example 1 and Comparative Example 1, the thermal resistance values of the electrically insulating substrates were measured. The measurement was carried out by placing the above insulating substrate (30 x 40 mm) on an aluminum block, and placing a 10 x
A 14 mm copper foil surface was etched so that it remained. In the measurement circuit, we used Kikusui Electric's PAC16-10 type as a constant voltage power supply.
Use Yokogawa Electric M2E1005 as a current-voltmeter,
Moreover, temperature measurement was performed using a thermocouple. As a result, the thermal resistance values of the substrates of Example 1 and Comparative Example 1 (both having a copper foil layer of 35 μm, an insulating layer of 50 μm, and an aluminum plate of 2.2 mm) were 2.9 and 3.6° C./W, respectively.

[Brief explanation of drawings]

FIG. 1 is an enlarged cross-sectional view of an electrically insulating substrate obtained by the method of the present invention. 1...Metal foil layer, 2...Insulating layer, 3...Metal plate.

Claims (1)

[Claims] 1. A method of manufacturing an electrically insulating substrate by laminating a metal foil layer, an insulating layer, and a metal plate with an adhesive interposed and press-molding them using a heat press machine, in which the surface of the metal plate is subjected to both sandblasting and etching treatments. 1. A method for producing an electrically insulating substrate, which comprises pre-processing.