JPS63174384A - Manufacture of printed 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 Application Field> The present invention relates to a method of manufacturing a printed circuit board using a metal plate as a base and forming a conductive pattern on the surface thereof.

<Conventional technology> Printed circuit boards for mounting various electronic components such as ICs and capacitors are constructed using insulating plates such as resin and ceramics, as well as metal plates with excellent mechanical strength and workability. There are things that have been done. The latter printed circuit board based on a metal plate is used to mount a power IC etc. that generates a large amount of heat, and as shown in FIG. 3, an insulating layer 2 and a copper foil I are sequentially deposited on a metal base plate 3. It is configured as follows.

Here, the insulating layer 2 is made of glass epoxy resin, epoxy resin, polyimide film, etc. with a thickness of 25 to 100 μm, and the metal base plate 3 is made of iron with a thickness of 1.0 to 1.5 tm, which has higher heat dissipation than copper. , a silicon steel plate or an aluminum plate is used, and also serves as a heat sink.

A printed circuit board based on a metal plate as described above differs from a printed circuit board manufactured using an insulating material as a base in the following points.

(2) Since the base plate is made of metal, it tends to corrode unless the untreated surface is protected with resist beforehand during plating or etching.

(2) When drilling a through hole in the board or cutting it into a desired shape, there is a risk that the insulating layer may collapse, causing a short circuit between the copper foil on the surface and the metal plate on the base.

FIGS. 2(a) to 2(f) are diagrams illustrating the manufacturing process of a printed circuit board based on a metal plate as described above. figure(
An etching resist 4 is applied to the surface of the copper foil 1 as shown in a), and the exposed portion is removed by etching as shown in FIG. Next, in order to plate a conductive pattern on the copper foil 1, a conductive pattern is left as shown in Figure (C), and a plating resist 5 is printed on the surface of the copper foil, and using the plating resist 5 as a mask, IN(d) is printed on the copper foil. Nickel and then gold plating are applied as shown in the figure. After the plating process, the plating resist 5 is peeled off, and instead, an etching resist 7 is applied to the back surface of the metal base substrate 3 as shown in FIG. 3(e). Using the etching resist 7 and the gold plating layer 6 as a mask, the exposed copper foil serving as the plating lead is removed by etching. That is, even if an attempt is made to cut the plated lead by punching or the like, there is a risk of a short circuit with the substrate as described in (2) above, and the purpose cannot be achieved. Next, the etching resist 7 which has completed its role is peeled off to produce a printed circuit board having a conductive pattern 6 on the metal base substrate 3 as shown in FIG. 3(f).

<Problems to be Solved by the Invention> In the manufacturing process of the conventional printed circuit board based on the metal plate described above, the first etching process is performed to pattern the copper foil in advance, and the plated leads are removed after plating with nickel and gold. Two steps of second etching are required to
However, for each of these etching steps, it is necessary to perform a step of printing etching resist on the entire surface of the copper foil and gold i base as a pretreatment, and a step of peeling off the etching resist as a post-process. This must be done twice as ancillary steps. Therefore, the process is complicated, the work is time-consuming, and the process is not economical.

Means for Solving the Problems> The present invention provides a printed circuit board manufacturing method that eliminates the above-mentioned conventional drawbacks and simplifies the process.

In the present invention, after depositing an insulating layer and a base conductor layer on a metal plate serving as a base, a plating mask having a pattern opposite to the conductor pattern to be formed on the surface of the base conductor layer is applied, and this is used as a mask. A plating layer is formed on the base conductor layer.

At least the surface of the plating layer is made of a gold plating layer, and the underlying conductor layer is etched using the gold plating layer as a mask to produce a printed circuit board having a desired conductor pattern.

<Function> By using the gold plating layer constituting the conductor pattern as a mask, patterning of the underlying conductor and etching of the plated leads can be performed simultaneously, which not only reduces the number of etching steps but also reduces pre-treatment. This eliminates the need for post-processing and significantly simplifies the manufacturing process of printed circuit boards based on metal plates.

<Example> The manufacturing process of an example according to the present invention will be explained using FIGS. 1(a) to 1).

In the figure (axis), an insulating layer 2 and a copper base conductor layer 1 are deposited on a base substrate 3 made of a metal material with a large heat dissipation effect, such as iron or aluminum. Next, leaving a region corresponding to the conductor pattern to be formed, a plating resist 5 is printed on the other regions including the side and back surfaces of the substrate as shown in FIG. 3(b). That is, a Menki resist 5 having a pattern opposite to the conductor pattern to be formed is printed on the back surface of the substrate and the surface of the base conductor layer 1. Nickel and then gold are sequentially plated on the base conductor layer 1 that exposes the metskiresist 5 as a mask,
A plating layer 6 is formed as shown in Figure (c). After the above plating process is completed, the coating resist 5 is peeled off, and an etching resist 7 is applied again to the back surface of the substrate 1, as shown in FIG. 3(d).

Using the etching resist 7 and the gold plating layer 6 as a mask, the base conductor N1 is etched as shown in FIG. A printed circuit board having pattern 6 on its surface is produced.

<Effects of the Invention> According to the present invention, since the base conductor is etched using the plating layer as a mask and patterned into a desired shape, the process of patterning the base conductor can be carried out in a significantly simpler and fewer number of steps. Not only is the process shortened, but the burden on the substrate and insulating layer is also reduced, making it possible to obtain an economically efficient printed circuit board manufacturing process.

[Brief explanation of the drawing]

FIGS. 1(a) to (f) are cross-sectional views showing the manufacturing process of an embodiment of the present invention, FIGS. 2(a) to (f) are cross-sectional views showing the conventional printed circuit board manufacturing process, and FIG. is a cross-sectional view of a printed circuit board based on a metal plate. 1. Metal base substrate 2: Insulating layer 3: Base conductor layer 5
: Plating resist 6: Plating layer 7: Etching resist Representative Patent attorney Takeshi Sugiyama (and 1 other person) Figure l

Claims (1)

[Claims] 1) In a printed circuit board formed by forming a conductor pattern on a metal plate as a base via an insulating layer, the process includes: depositing an insulating layer and a base conductive foil on the base metal plate; A step of forming a mask having a pattern opposite to the conductor pattern to be formed on the back surface of the plate and the base conductor foil, a step of applying gold plating to the exposed surface of the base conductor, and a step of applying gold plating to the base conductor foil using the gold plating as a mask. A method for manufacturing a printed circuit board, comprising the steps of patterning.