JPH03183190A - Manufacture of printed-circuit board - Google Patents

Abstract

PURPOSE:To prevent burring and flaking of a conductor at its cut edge by making notches at the edges of the conductor before it is cut. CONSTITUTION:A conducting pattern 1 on a printed circuit board is electroplated in its necessary area. Before the electroplating, notches 4 are provided in a conductor for electroplating, where the conductor is cut. The depth of the notches is 1/3 to 2/3 of the conductor so as not to affect the insulating base of the printed circuit board. The conductor 3 is cut, for example, by routing or spot-facing to make a recess 6.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a method for manufacturing a printed wiring board.

Conventional technology and its problems When mounting components on printed wiring boards, precious metals such as gold and rhodium, which have excellent wear resistance, corrosion resistance, and electrical conductivity, are used to ensure reliability at the connection parts. Often plated.

The method of plating precious metal on a conductor circuit is to form a pattern using a plating resist and perform precious metal plating before forming a conductor pattern by etching, and after peeling off the plating resist, form a printed wiring board by etching. , a so-called pre-plating method, and a so-called post-plating method, in which a necessary conductor pattern is formed by etching and then electrolytic noble metal plating is performed.

Among these methods, the pre-plating method does not allow partial noble metal plating, so parts that do not require noble metal plating are also plated, leading to an increase in costs. Further, since the circuit edge portions are not covered with precious metal plating, there is a lack of reliability, and furthermore, since etching is performed after precious metal plating, there are drawbacks such as contamination of the noble metal plating surface.

The post-plating method eliminates the above-mentioned drawbacks, but printed wiring boards with complex circuits will have isolated conductor circuits left inside, so it is difficult to plate these parts. Can not. For this reason, a method is used in which a conductive wire for electrolytic plating is separately provided, the necessary portions are plated with precious metal, and then a recess is provided in the printed wiring board by so-called counterbore processing and the conductive wire is cut. However, in general, the method of forming a concave portion by counterbore processing and cutting the conductive wire causes burrs and blisters on the cut surface, which causes short circuits between circuits on the printed wiring board. As a countermeasure against this problem, a method has been proposed in which the conductive wire to be cut is coated with a synthetic resin film and counterbored (Utility Model Publication No. 56-28787). However, although this method is somewhat effective in preventing burrs and blisters, it cannot completely prevent the occurrence of burrs and blisters, and has the drawback that it requires time and effort to correct them.

Means for Solving the Problems In view of the above-mentioned problems, the inventor of the present invention has conducted intensive research and found that after performing other electrolytic metal plating on the conductor pattern using a post-plating method, counterbore processing, etc. In the method of cutting a conductive part for electrolytic plating by cutting, 173 mm of conductive material is pre-coated at the end of the cut part of the conductive part.
It was discovered that by making a cut with a thickness of about 2/3 and then cutting it, the occurrence of cracks, curling, etc. in the conductive part at the cut surface was prevented, and a good cut surface was formed. .

That is, the present invention forms a conductive pattern and a conductive part for electrolytic plating on an insulating substrate, performs electrolytic metal plating, and then cuts the end of the part to be cut of the conductive part, and then performs cutting. The present invention relates to a method of manufacturing a printed wiring board, characterized in that four parts are formed on an insulating substrate and the conductive parts are cut.

The method of the present invention can be applied to various types of printed wiring boards, such as single-sided, double-sided, and multilayer boards, regardless of the type of printed wiring board. The material of the insulating substrate is also not particularly limited, and can be widely applied to, for example, an epoxy resin substrate, a polyimide resin substrate, a composite substrate, a metal core substrate, etc.

In the method of the present invention, after a conductor pattern is formed on a printed wiring board, necessary portions on the conductor pattern are plated with another metal by a post-plating method.

There is no particular limitation on the method of forming the conductor pattern on the printed wiring board, and any method such as panel plating, pattern plating, etc. can be applied.

It is necessary to form a conductive part for electrolytic plating for post-plating on a printed wiring board on which a conductive pattern is formed. The conductive portion can be formed by separately providing a conductive line from the outline of the printed wiring board in the area to be post-plated, or by providing a conductive line from a conductor pattern part continuous with the outline within the wiring board to an isolated conductor pattern part. It can be formed by various known methods such as. Among these methods, the method of routing conductive wires from the outline line increases the wiring density and leaves unnecessary wiring, which can easily cause trouble. Since it is difficult to route the conductor directly, it is advantageous to provide a conductive line from the continuous circuit section to the isolated conductor circuit section.

FIG. 1 is a plan view showing a part of a printed wiring board provided with a conductive part for electrolytic plating, in which a conductor part (1) connected to the outline of the printed wiring board and a conductor part (1) independent from the outline
2) is connected to the conductive wire (3) for electrolytic plating.

As for the plating of other metals provided on the conductor pattern, in addition to noble metal plating such as gold, silver, and rhodium, various electrolytic platings such as nickel and solder are possible, and the plating may be performed according to a conventional method.

In the method of the present invention, after performing electrolytic metal plating on the required portions of the conductor pattern, incisions are made in advance at the ends of the portions to be cut of the conductive portions for electrolytic plating formed on the printed wiring board. The depth of the cut may be approximately 173 to 2/3 of the thickness of the conductive material of the conductive portion, and may be set to a depth that does not adversely affect the insulating base material of the printed wiring board.

The method of making the cut is not particularly limited, and any method that can form a sharp cut of the required depth may be used.For example, a cut similar to that used as a mold for cutting out wiring boards may be used. A cut in the required shape can be made using a mold with a predetermined shape and a blade.

Next, the conductive portion for electrolytic plating is cut. The method for cutting the conductive portion is not particularly limited, and it is sufficient to remove the conductive portion and the surface portion of the insulating substrate using a normal cutting method to form a recess in the insulating substrate. Generally, a router or the like is used to cut the conductive portion. This can be done by so-called counterboring, in which a recess is formed by cutting.

In Fig. 2(a), a conductor pattern part (1) connected to the outline of the printed wiring board and a conductor pattern part (2) isolated from the outline are connected by a conductive part (3) for electrolytic plating. This is a cross-sectional view of the state in which a cut (4) is made in advance in the conductive portion (3) as shown in FIG. 2(b), and then the second
As shown in Figure (c), a recess (6) is formed in the insulating substrate (5) by a counterboring method or the like, and the conductive part (3) is cut.

The shape, size, depth, etc. of the four parts can be set arbitrarily.For example, in a printed wiring board on which an integrated circuit chip is mounted, a recess slightly larger than the chip is created in the insulating substrate at the same time as cutting the conductive part by cutting. can be equipped with a chip. In addition, for printed wiring boards such as sliding contact boards where the presence of recesses is a problem, it is also possible to form recesses by counterboring, cut the conductive parts, and then fill the recesses with a synthetic resin to make them smooth.

Although there are no particular limitations on the method of cutting, a method of cutting from the center of the recess outwards is preferred from the viewpoint of the finish of the cut surface.

Effects of the Invention According to the method of the present invention, after performing electrolytic metal plating such as precious metal plating by the so-called post-plating method, when cutting the conductive part for electrolytic plating, there is no problem such as generation of paris or peeling of the conductor part on the cut surface. It is possible to produce a good printed wiring board without causing any problems.

Furthermore, according to the method of the present invention, the entire process from forming a cut in the conductive part for electrolytic plating to cutting for cutting the conductive part is performed using a numerically controlled machine tool (NC machine tool). This makes it possible to accurately determine the machining position and machining depth, increasing accuracy and reliability.

Example Hereinafter, the present invention will be explained in more detail by showing examples.

Practical Example 1 A printed wiring board having a conductive pattern and a conductive part for electrolytic plating as shown in FIG. 1 was produced by a pattern plating method.

The conductive pattern and the conductive portion are made of a copper layer with a thickness of about 50 μm. Next, a plating film consisting of 5 μm of base nickel plating and 1 μm of gold plating was formed on the pad portion of the conductor pattern and the conductive portion for electrolytic plating by electrogold plating.

Using an NC machine tool equipped with a mold equipped with a cutting blade, a cut (4) with a depth of 30 μm was made at the position shown in FIG. 3 in the conductive portion for plating of the printed wiring board described above. The cross-sectional shape of the cut is similar to that shown in FIG. 2(b). The mold used had the same shape as the part in which the recesses were to be formed in the next step, and the notches (4) were all made at the same time.

Next, using an NC router, processing was carried out from the center of the cut outwards to form a recess (6) for mounting an integrated circuit chip with a depth of 11111, as shown in FIG. Then, according to the usual method, the type of router bit,
The edges of the cut surface were processed by changing the rotation speed, movement speed, etc.

The concave portion formed by the counterboring process was in good condition with no flaking or peeling of the copper film on the cut surface of the conductive wire.

[Brief explanation of drawings]

Fig. 1 is a plan view showing a part of a printed wiring board provided with a conductive part for electrolytic plating, Fig. 2 is a sectional view of the printed wiring board, and Fig. 3 is a plan view of the printed wiring board with a notch. FIG. 4 is a plan view of a printed wiring board that has been subjected to counterbore processing. (1)...Conductor pattern part continuous with the outline of the printed wiring board, (2)...Conductor pattern part isolated from the outline, (3)...Continuity line for electrolytic plating, (4)...・・・
Notch, (5)...Insulating substrate, (6)...Recess formed by counterboring. (Above) Figure Figure (C) Broken Figure

Claims (2)

[Claims] (1) After forming a conductor pattern and a conductive part for electrolytic plating on an insulating substrate and performing electrolytic metal plating, a notch is made at the end of the part to be cut of the conductive part, and then the insulating substrate is cut by cutting. A method of manufacturing a printed wiring board, comprising forming a recess in the conductive part and cutting the conductive part. (2) The method for manufacturing a printed wiring board according to claim 1, wherein the cut formed in the conductive portion for electrolytic plating has a depth of 1/3 to 2/3 of the conductive portion.