JPH01181597A - Manufacture of printed wiring board - Google Patents

Abstract

PURPOSE:To improve electrical insulating property of the title printed wiring board together with assurance of high accuracy of the same by forming a porous type anodic oxide film on an aluminum base plate, then forming a barrier type anodic oxide film, further forming an insulating layer by electroplating insulating resin by an electrophoretic method, and forming a conductor circuit on the insulating layer. CONSTITUTION:A porous type anodic oxide film 3 is formed by the use of an aluminum base plate 1 as a substrate, and a barrier type anodic oxide film 4 is formed on the side of an aluminum host material 1 by making use of a barrier type anodic oxide coating 4 treatment. Then, an insulating resin layer 5 is formed by an electrophoretic method, to which a plating layer 6 is plated, and thereafter an etching resist layer 7 is formed to form a conductor circuit by etching. Hereby, an aluminum-based printed wiring board with a high accuracy and high electrical insulating property can be assured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an aluminum-based printed wiring board with good thermal conductivity.

[Conventional technology]

Various methods have been proposed for manufacturing aluminum-based printed wiring boards. For example, Matsushita Electric Works (Public Patent Publication 1980-21458)
7), there is a method of insulating the through hole wall by filling the entire hole with an insulating resin, leaving an insulating layer, drilling the hole again, and then forming a circuit.

[Problem to be solved by the invention]

The latter method has a limit in achieving high accuracy due to the difficulty of alignment during re-drilling. Furthermore, the former method has the disadvantage that it is difficult to maintain high reliability in electrical insulation.

The present invention provides a method for manufacturing an aluminum-based printed wiring board that has high precision and high reliability in electrical insulation by eliminating both of the above-mentioned drawbacks.

[Means to solve the problem]

In the present invention, after forming a porous type anodic oxide film on an aluminum base material, a barrier type anodic oxide film is formed,
This method of manufacturing a printed wiring board is characterized by forming an insulating layer by electrodepositing an insulating resin by electrophoresis, and forming a conductor circuit thereon.

As the aluminum base material according to the present invention, there is used an aluminum metal or an alloy thereof, or a base material in which a metal foil such as a copper foil is bonded onto an aluminum metal or an alloy thereof using an insulating adhesive.

The present invention will be described below with reference to the above-mentioned base material process diagram. Figures 1 to 7 show the manufacturing process of a printed wiring board using aluminum metal or its alloy as the aluminum base material, and Figures 8 to 12 show the manufacturing process of a printed wiring board using aluminum metal or its alloy as the base material. The manufacturing process of the printed wiring board is shown below.

In Figures 1 and 8, Figure 1 shows the aluminum plate 1.
The base material shown in FIG. 8 is an aluminum plate A with a copper foil bonded to it using an adhesive C. Throughhole 2. if necessary. Holes for B are drilled, but in the case of an aluminum substrate with metal foil adhered, the method of the present invention is applied only to the through-hole hole walls, whereas in the case of aluminum substrates, the method of the present invention is applied to both the substrate surface and the through-hole hole walls. Processing is performed by

Blown porous type anodic oxide film 3. E (Figure 2.9)
form. To form a porous film, a sulfuric acid bath,
The barrier type anodic oxidation coating 4, F (Fig. 3.9) treatment is performed using an oxalic acid bath, phosphoric acid bath, or chromic acid bath. It is important for the present invention that the 21fJ barrier type film is not formed on the porous film, but on the aluminum base material side, and this improves the insulation properties of the aluminum base material itself. 3. The electrophoretic insulation film that is applied in the first step is a porous type anodic oxide film, which is much improved compared to the conventional method. The barrier-type anodic oxide film, which can adhere well to H and form a highly reliable layer structure, has much higher insulation properties than the conventional porous anodic oxide film alone. This is achieved through the combined use of a very highly insulating film. Electrolytic baths for forming barrier-type films include ammonium boric acid bath, ammonium phosphate bath,
Buffer solutions such as organic acids and ammonia are used. In this case, the formation voltage needs to be higher than the formation voltage of the first porous anodic oxide film and lower than the electrophoresis voltage of the insulating resin, and is preferably as high as possible to ensure high insulation.

The aluminum base material anodized in two stages is then subjected to electrophoresis to form an insulating resin layer 5.0 (FIG. 4.9). As the electrodeposited resin, a cationic epoxy resin or anionic acrylic resin is used. Next, a copper plating layer 6 is formed using an additive method or a panel plating method. After plating H (Fig. 5.10), a conductor circuit is formed using a conventional photoetching method. Chapter 6.11
The figure shows the etching resist layer 7 before etching. FIG. 7.12 shows the formation of a conductor circuit by etching.

〔Example〕

The present invention will be further explained below with reference to Examples.

Example 1 An aluminum plate with a plate thickness of 1 l and a hole with a diameter of 1 mm was drilled in an aqueous solution of 50 g/l of sodium hydroxide.
Degreased by immersing for 1 minute at 0°C, electrolyzed at 1.3 A/dm for 30 minutes at 20°C in an aqueous solution containing 150 g/31 of 82SO4, using an aluminum plate as an anode and a lead plate as a cathode. By doing so, a porous anodic oxide film was formed, and the pH was adjusted to 7.8.
100 at a pressure increase rate of l v/sec at 50 °C in an aqueous solution containing 20 g/JL ammonium borate adjusted to
After increasing the pressure to V, anodic electrolysis was performed at 100 V for 3 minutes to form a barrier type anodic oxide film.

Next, an anionic electrophoresis bath (Vanilite 8800:
Anodic electrolysis was performed for 3 minutes by applying a voltage of 140 V at 20° C. in a container (manufactured by Honey Kasei Co., Ltd.). Furthermore, HSlolB
After catalytic treatment (manufactured by Hitachi Chemical Co., Ltd.), electroless copper plating was performed, and then a printed wiring board with through holes was formed using the zero-order photoetching method on which electrolytic copper plating was formed to a thickness of 30 scales. Formed. The obtained printed wiring board had high reliability in electrical insulation and high dissipation properties, and could be wired even in bent parts.

Example 2 A printed wiring board with through holes was formed in the same manner as in Example 1, except that an aluminum-based double-sided copper-clad laminate (manufactured by Nippon Light Metal Co., Ltd.) having a thickness of 1.8 mm was used. A porous anodic oxide film produced by the method of the present invention,
Formation of barrier type anodic oxide film and electrophoretic insulating resin was applied only to the through-hole pore walls. The obtained printed wiring board had the same performance and effects as the printed wiring board of Example 1.

〔Effect of the invention〕

As explained above, the aluminum-based printed wiring board manufactured by the method of the present invention has excellent thermal conductivity, so it is advantageous for mounting components that require a large amount of current, and has the advantage that it can be wired even in bent parts. There is. Furthermore, it has become possible to significantly reduce the manufacturing cost of aluminum-based printed wiring boards with high precision and high electrical insulation.

[Brief explanation of the drawing]

Figures 1 to 7 are schematic cross-sectional views showing the manufacturing process of an aluminum-based printed wiring board according to the present invention, and Figures 8 to 12 show the manufacturing process of an aluminum-based printed wiring board to which metal foil is bonded according to the present invention. It is a schematic cross-sectional view. l... Aluminum plate 2... Through hole 3... Porous type anodic oxide film 4... Barrier type anodic oxide film 5... Electrophoretic insulating resin layer 6... Copper plating layer 7... Etching resist layer A...Aluminum plate B...Through hole C...Adhesive D...Copper foil E...Porous type anodic oxide film F...Helia type anodic oxide film G... Electrophoretic insulating resin layer H...Copper plating layer J...Etching resist layer Patent applicant: Canon Co., Ltd. Representative Yu Wakabayashi! PJ1 figure 2 figure 5 fi7 figure fi8 figure Me figure JA10 figure: A12 figure

Claims (1)

[Claims] 1. After forming a porous type anodic oxide film on the aluminum base material, a barrier type anodic oxide film is formed, an insulating layer is formed by electrodepositing an insulating resin by electrophoresis, and a conductor circuit is formed on top of that. A method of manufacturing a printed wiring board, comprising: forming a printed wiring board.