JPS60254788A - Method of producing printed circuit 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 (Industrial Field of Application) The present invention relates to a method of manufacturing a printed wiring board by electroless plating.

(Prior Art) Printed wiring boards incorporated in various electrical devices are becoming more dense as the devices become smaller, and circuits (1) and circuit spacing are required to be narrower.

When manufacturing printed wiring boards using an electroless plating method such as the CC-4 method, an adhesive containing a plating catalyst is applied to the substrate, a plating resist is printed, and then a metal such as copper is applied to the adhesive surface by electroless plating. However, at this time, copper or the like deposits and adheres to the surface of the plating resist, resulting in short circuits between the circuits, which is a drawback that is increasing particularly with increasing density.

In addition, electroless plating solutions have the disadvantage that plating oil contaminants increase with use, and these contaminants cause cracks and voids to occur between crystals, making circuits more likely to break due to bending. As the width becomes narrower, there is a drawback that the circuit becomes more easily disconnected.

(Objective) It is an object of the present invention to provide a method for manufacturing a printed wiring board that can improve the above-mentioned drawbacks and prevent disconnections and short circuits.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a method for manufacturing a printed wiring board in which a circuit is formed on a substrate by electroless plating. Provided is a method for manufacturing a printed wiring board, comprising the steps of depositing plating and, after the step, depositing plating with a smaller brain size than the plating using a second electroless plating solution. It is.

(Function) According to the present invention, plating with a larger brain size is first deposited on the side closer to the substrate, and then plating with a smaller brain size is deposited. Even if plating adheres to the surface, this plating will hardly grow during the next plating process, and short circuits between circuits can be prevented. Also,
Plating with a smaller brain size is inserted between the crystals with a larger brain size, improving the mechanical strength of the circuit and preventing disconnection defects.

Note that it is more effective to prevent circuit disconnection if the brain size of the deposits deposited by the second electroless plating solution is 10 μm or less.

(Example) Hereinafter, the present invention will be explained based on examples.

First, an insulating substrate such as a paper phenol resin base material or a paper epoxy resin base material containing a plating catalyst such as palladium is used as a substrate, and an adhesive containing a plating catalyst is applied to the surface. After applying adhesive to the insulating substrate, a plating resist is printed in a predetermined pattern. After printing the plating resist, the insulating substrate is immersed in a roughening solution to roughen the exposed adhesive surface. After roughening the adhesive surface, the insulating substrate is immersed in a first electroless copper plating solution to deposit copper plating. Next, the insulating substrate is immersed in a second electroless copper plating solution that has a lower concentration of plating solution contaminants than the first electroless copper plating solution, and copper plating with a small brain size is deposited. Manufacture boards.

Next, the number of times the copper foil was bent until it broke was measured for the present invention and the conventional example, and the results shown in the table were obtained. Each sample was prepared by immersing a stainless steel substrate with a ram plating catalyst on its surface in an electroless copper plating solution to deposit copper plating, and peeling off the copper plating from the stainless steel substrate. As is clear from the table, according to the present invention, the number of times of bending is increased by more than four times compared to the conventional example, and the mechanical strength of the copper plating layer is improved.

(Effects) As described above, according to the present invention, there is provided a method for manufacturing a printed wiring board that effectively prevents short circuits caused by metal deposited on the surface of a plating resist and disconnections caused by bending or the like.

Patent applicant: Hitachi Capacitor Co., Ltd.

Claims (1)

[Claims] (1) A method for manufacturing a printed wiring board in which a circuit is formed on a substrate by S electrolytic plating, which includes a step of depositing plating on the substrate with a first electroless plating solution, and a second step after the step.
A method for manufacturing a printed wiring board, comprising: depositing a plating having a smaller brain size than the plating using an electroless plating solution. (2) Claim 1, in which the brain size of the plating deposited by the second electroless plating solution is 10 μm or less
A method for manufacturing a printed wiring board as described in Section 1.