JPS5819154B2 - Manufacturing method of through-hole printed board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a through-hole printed board, in particular, a through-hole printed board in which the hole wall and round part of the through-hole are selectively plated with good solderability, and the wiring part is formed only with copper. The present invention relates to a method for manufacturing a hole printed board.

As an example of a conventional method for manufacturing through-hole printed boards, a through-hole is drilled at a desired position on a board with copper foil on both sides, such as a copper-clad laminate, and the entire surface of the board, including the hole walls, is subjected to activation treatment. After that, electroless copper plating and electrolytic copper plating are sequentially performed.Next, only the hole wall and the round part around the hole are plated with a metal with good soldering properties, such as solder, or gold plated, and then the board surface is plated with gold. There is a method of removing unnecessary copper except for the wiring part by etching, but electrolytic copper plating is used to make holes into through holes, and the thickness is 25μ on the hole wall and round part.
degree is necessary.

However, in the above-mentioned conventional method, electrolytic copper plating to a required thickness is performed on the entire surface of the substrate including the hole walls and round portions at one time.

Therefore, a large amount of electric capacity is required, which poses a problem in terms of production efficiency, and the plating thickness also increases.

Furthermore, since thick electrolytic copper plating is applied to the entire surface, the amount of etching required to remove unnecessary copper increases, making it difficult to form wiring sections with high precision and high density.

Furthermore, it has disadvantages such as being economically disadvantageous because it requires a large amount of expensive electrolytic copper plating and etching solution.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a through-hole printed board that eliminates the above-mentioned conventional drawbacks, has excellent productivity and economical efficiency, and can achieve high precision and high density wiring sections.

In the present invention, the electrolytic copper plating process is divided into two steps, the first electrolytic copper plating is performed on the entire surface of the board including the hole walls and the lounge area, and the second electrolytic copper plating is performed on the hole walls and the areas where thicker plating is required. It is characterized in that it is applied only to the round part.

An embodiment of the present invention will be described below with reference to the drawings.

Figure 1 is a process diagram. In FIG. 1A, reference numeral 1 denotes an insulating substrate, such as a copper-clad laminate, with copper foil 2 coated on both sides. First, a through hole 3 is drilled or punched at a desired position on this substrate 1 (the first Figure B).

Next, an activation treatment is performed on the copper foil 2 on the surface of the substrate 1 including the hole walls of the through holes 3, and then an electroless copper plating layer 4 is formed to provide conductivity (FIG. 1C).

On this electroless copper plating layer 4, a primary electrolytic copper plating layer 5 with a thickness of about 5 to 10 μm is formed on the entire surface (Fig. 1D).
.

This turns hole 3 into a through hole.

Next, except for the hole wall 3a and the round part 3b, the anti-stick resist 6 is covered by printing or a photosensitive film (FIG. 1E).

Then, on the electrolytic copper plating layer 5 of the hole wall 3a and the round part 3b exposed in this state, a secondary electrolytic copper plating layer 7 is applied so that the total thickness of these layers is about 25μ.
It is formed to a thickness of about 5 to 20 microns, and a metal plating layer 8 with good solderability (for example, solder plating, gold plating, etc.) is formed thereon (FIG. 1F).

Next, the anti-stick resist 6 is peeled off (FIG. 1G), and then a printing method is applied so that the portions other than the round portion 3b and the wiring portion 9 are exposed.

Alternatively, the etching resist 10 is covered with a photoresist film (FIG. 1H), and unnecessary copper on the surface of the substrate 1 other than the round portion 3b and the wiring portion 9 is removed by etching treatment (FIG. 1).

In this way, the hole wall 3a and the round part 3b are soldered.

A through-hole printed board as shown in FIG. 2 is obtained in which a plating layer 8 with good properties is formed and only copper is formed in the wiring portion 9.

In fact, as shown in FIG. 1J, the entire process is completed by covering the parts other than the round part 3b with the solder resist 11, and then applying flux to the round part 3b.

As described above in one embodiment, in the present invention, electrolytic copper plating is performed in two stages, primary and secondary, and the primary electrolytic copper plating is performed on the entire surface of the board including the hole walls and round parts. In contrast, secondary electrolytic copper plating is applied only to the hole walls and round portions.

Therefore, by making the primary electrolytic copper plating thinner, the capacitance required for the electrolytic copper plating process can be reduced.
As a result, productivity is improved, and uniform plating thickness can be obtained with less variation in plating thickness.

Furthermore, since the etching process only needs to be carried out for the secondary electrolytic copper plating, the amount of etching is small, and therefore the wiring portion can be made with higher accuracy and higher density.

Furthermore, it is economical because the amount of electrolytic copper plating and the consumption of etching solution are reduced.

In addition, the soldering part becomes the through-hole part.

In other words, since the hole walls and round portions are plated with good soldering properties, they can withstand long-term storage, and the soldering work can be performed reliably and easily.

[Brief explanation of the drawing]

Fig. 1 is a process diagram showing one embodiment of the present invention, and Fig. 2 is a process diagram showing an embodiment of the present invention.
It is a top view of the through-hole printed board obtained by the process of a figure. 1...--Insulating substrate, 2...Copper foil, 3...
...Through hole, 3a... Hole wall, 3b...
... Round part, 4 ... Electroless copper plating layer, 5
・・・・・・Electrolytic copper plating layer (primary), 6・・・・・・
Anti-metallic resist, 7... Electrolytic copper plating layer, (
secondary), 8... Metal plating layer with good soldering properties, 9... Wiring section, 10... Etching resistant resist, 11... solder resist.

Claims (1)

[Claims] 1. A through hole is provided at a desired position on an insulating substrate with copper foil on both sides, and after activation treatment is performed on the entire surface of the substrate including the hole wall of the through hole, electroless copper plating and electrolytic copper plating are sequentially performed. Next, the hole walls and round parts around the holes are coated with an anti-stick resist, and these hole walls and round parts are sequentially coated with electrolytic copper plating and metal plating with good soldering properties, and then the anti-stick resist is coated. After removing the copper, the round part and the wiring part are covered with an etching-resistant resist, and unnecessary copper is removed by etching.