JPS5884494A - Method of producing metal core printed circuit - 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 a method for manufacturing a metal-core printed circuit that has excellent mechanical strength and is capable of high-density wiring.

Conventionally, paper-based phenol resin laminates, glass fiber epoxy resin laminates, and the like have been used as printed circuit wiring boards. However, with the recent development of electronic devices, the printed circuit wiring boards used are also required to have higher density, mechanical strength, and lower cost, and copper-clad laminates, which have been used in the past, have become more demanding. From the method of manufacturing using
Attempts have been made to form an organic insulating layer such as a modified phenolic resin and form a conductor circuit thereon. However, printed circuit boards in which conductive circuits are formed by direct electroless plating or electrolytic plating on epoxy-based or polyester-based organic insulating layers have poor adhesion between the organic insulating layer and the conductive circuits, so molten soldering is not recommended. At present, it is hardly put into practical use because it has poor high-temperature durability when connecting parts and has an extremely high rate of defective products.

In addition, in order to improve the adhesion between the metal plate and the conductor circuit, which has the above drawback, NBR modified phenol resin is electrostatically coated on the metal plate.
When a conductor circuit is formed, the adhesion is good, but the coating film is not uniform, so there is a drawback that high-density wiring cannot be achieved.

Therefore, in order to improve these drawbacks, the inventor of the present invention has created a material that has excellent mechanical strength and adhesive strength by electrocoating a metal plate with nitrile rubber-modified phenol resin to insulate the metal plate and then forming a conductor circuit. We have developed a metal-core printed circuit board that enables high-density wiring.

Hereinafter, the method of the present invention will be explained in detail with reference to the drawings. FIGS. 1 to 6 are cross-sectional views of the manufacturing process of the metal core printed circuit according to the present invention. That is, as shown in FIG. 1, after making a through hole 2 in the metal plate 1, as shown in FIG. did. There are methods such as solvent-based coating and electrostatic powder coating to coat a metal plate with NBR-modified phenolic resin to create an insulating plate, but it is difficult to achieve a 100μ coating that is reliable for insulating with solvent-based coating. Also, although electrostatic powder coating allows thick film coating, the state of the coating is uneven and high-density printing is not possible.

Therefore, good results were obtained when electrodeposition coating was used, which provided a good coating film condition and was easy to control the film thickness. The film thickness in electrodeposition coating can be controlled by voltage, time, and bath temperature, but the voltage is 300V.
An electrodeposited film of 100 μm could be obtained under electrodeposition conditions of 2 minutes and a bath temperature of 25° C. The conditions for baking the electrodeposited film are as follows: Since a small amount of water is adsorbed in the deposited film, rapid heating tends to cause pinholes. Let's do it. After baking, electroless plating 4 of several microns is formed on the surface of insulating layer 3, and then anti-corrosion ink 5 is applied as a coating material to prevent electroplating from depositing on areas other than those where conductive circuits are to be formed. Next, as shown in FIG. 5, a circuit pattern 6 is formed by electrolytic plating, and then, as shown in FIG. 6, the corrosion-resistant ink 5 and the electroless plating film 4 thereunder are removed to form a conductor circuit. This is a method for manufacturing a metal core printed circuit. This will be explained below using examples.

Example: A hole with a diameter of 1.1 am was arbitrarily made in an iron plate with a thickness of 1.0 mm, and after degreasing, an NBR made of 70 parts of nitrile rubber containing 35% acrylonitrile and 140 parts of phenolic resin was prepared.
Place the modified phenol resin in a water-dispersed electrodeposition solution and apply a DC voltage of 300 V with the iron plate as the cathode and the carbon plate as the anode.
was applied for 2 minutes to obtain an electrodeposited film of 100μ. 80℃ after air drying
After processing for 30 minutes, baking was performed at 220°C for 20 minutes. Thereafter, it was etched with a chromium sulfuric acid solution, further activated with a palladium chloride-hydrochloric acid aqueous solution, and washed with water.

Next, a film of about 0.5μ is formed by electroless nickel plating, washed with water and air-dried, and then coated with anti-corrosion ink on areas other than those that will become conductors.
/dm' Electrolytic plating was performed for 60 minutes to obtain a film thickness of 40
A copper circuit of μ was formed.

Next, the anti-corrosion ink was dissolved and removed using an organic solvent, and the electroless plating film other than the circuit area was removed using a phosphoric acid-hydrogen peroxide etching agent to increase the adhesive strength to 1.4/9/cm.
A metal core printed circuit board with high temperature durability of 260'010 seconds or more and arc resistance of 135 seconds was obtained.

As explained above in the Examples, a metal core printed circuit board with excellent mechanical strength and adhesive strength and high density wiring can be obtained by the method of the present invention.

[Brief explanation of drawings]

1 to 6 are cross-sectional views of the manufacturing process of a metal core printed circuit board according to the present invention. 1...Metal plate 2...Through hole 3...Insulating layer 4...Electroless plating layer 5... Corrosion resistant ink 6... Electrolytic plating layer)! ' 1 Figure 2 yen - ++ hit

Claims (1)

[Claims] After electrodepositing nitrile rubber modified phenol resin powder on a perforated metal plate to make an electrical insulating plate, apply thick electroless plating directly on top of it, or use a combination of electroless plating and electrolytic plating. A method for manufacturing a metal core printed circuit, comprising forming a conductor circuit.