JP2002121694A - Method and apparatus for plating through-hole of printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for plating a through-hole of a printed wiring board capable of arbitrarily controlling the thickness of front/rear copper plating layers in a double-sided printed wiring board. SOLUTION: In a through-hole plating wiring method, for plating the through- hole, etc., in the printed board in a plating bath filled with a plating liquid, in which the printed wiring board (b) as another electrode is arranged between a pair of electrodes (a), (a), by interposing an object, the ion flowability between one of the pair of electrodes and the printed wiring board is set lower than the ion flowability between the other one of the pair of electrodes and the printed wiring board. A plating treatment is conducted so that the plating thickness of front/rear sides of the printed wiring board are different.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for performing through-hole plating on a printed circuit board, and more particularly to an apparatus for appropriately selecting and processing the thickness of a plating layer on each surface of a double-sided printed circuit board.

[0002]

2. Description of the Related Art In order to form a pattern on a double-sided copper-clad printed circuit board, generally, (a) through-hole plating (panel plating) is performed on a hole-formed double-sided copper-clad laminate. (B) Form a pattern with a mask film (dry film) on both sides. (C) A pattern is formed by etching. Process.

[0003] The pattern formed in this manner is obtained by adding the thickness of copper by panel plating to the thickness of copper foil previously provided on the substrate. Usually, the thickness of the front and back of the substrate is the same.

[0004] However, depending on the use of electronic equipment, it may be necessary to change the thickness of copper on the front and back of the substrate. For example, there is a case where there is a ground layer through which a large current flows on one side and a fine pattern exists on the other side.

[0005]

In such a case,
It is customary to change the thickness of the material copper foil on the front and back.

[0006] However, abnormal deposition such as burnt plating, ie, roughness, is likely to occur on the surface near the electrode, and control is difficult. To solve this, there is a method of turning off the current on one side or reducing the current on the one side, etc., to adjust the current supply amount.However, uneven distribution of the current density in the plating tank also causes plating burning. It's easy to get up and has problems.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to provide a method and an apparatus for through-hole plating a printed circuit board which can arbitrarily control the thickness of a copper plating layer on both sides of a double-sided printed circuit board. Aim.

[0008]

In order to achieve the above object, according to the present invention, in a plating tank filled with a plating solution, a print as the other electrode is provided between a pair of electrodes provided in the plating tank. In a through-hole plating method for a printed circuit board in which a substrate is arranged and a plating process is performed on a through-hole or the like in the printed circuit board, an ion fluidity between one of the pair of electrodes and the printed circuit board is inserted by interposing an object. Wherein the plating process is performed such that the plating thickness on the front and back surfaces of the printed board is different by lowering the ion mobility between the other of the pair of electrodes and the printed board. Through-hole plating method of the substrate, and in a plating tank filled with a plating solution, the other between a pair of electrodes provided in the plating tank A printed circuit board as a pole is arranged, and in a through-hole plating apparatus for a printed circuit board for plating a through hole or the like in the printed circuit board, an adjustment having a through hole between one of the pair of electrodes and the printed circuit board. The present invention provides a through-hole plating apparatus for a printed circuit board, wherein a plating process is performed by interposing a plate.

[0009]

FIG. 1 shows the configuration of an embodiment of the present invention. FIG. 1 shows a side cross-sectional shape of the plating tank, and the plating tank is filled with a plating solution.
Then, electrodes (anodes) a, a
Is provided, and a printed board b as the other electrode (cathode) is provided between the two electrodes, and an adjustment plate c is provided between one of the electrodes a and the printed board b.

Thus, the electrodes a, a forming two anodes
Looking at the two ion flow paths between the substrate and the printed circuit board b serving as a cathode, one of the flow paths is provided with an object for reducing ion flow, that is, an adjustment plate. For this reason, one flow path has lower ion flowability than the other ion flow path.

This plating apparatus deposits copper ions, which are moved by flowing copper ions between an anode and a cathode, on a printed circuit board. In this case, when the adjusting plate c is inserted between the electrodes a and b, the amount of copper ions flowing decreases, and the amount of copper ions deposited on the printed circuit board decreases.

FIG. 2 shows an example of the structure of an adjusting plate used in the plating apparatus of FIG. In this configuration example, two adjustment plates c1 and c2 are used in an overlapping manner, and both adjustment plates c1 and c2 are relatively movable, and each of the adjustment plates c1 and c2 is moved by the movement.
The degree of overlap of the through-holes X opened in FIG.

That is, since the two adjusting plates c1 and c2 have the same structure, if the two are completely overlapped, the through-holes X formed in the two overlap with each other. The opening degree of the hole X is maximized. Then, as one adjustment plate is moved relative to the other adjustment plate in the horizontal direction in the drawing, the degree of opening of the through-hole X decreases. In other words, it acts as an adjusting plate for adjusting the flow rate of copper ions.

(Actual Measurement Example) Two titanium cylindrical baskets each having a diameter of 20 cm and a length of 130 cm were prepared as anodes.
These baskets are each filled with an appropriate number of copper balls having a diameter of 8 cm. Then, these anodes are provided at diagonal positions in the plating tank. At the center of the plating tank, a printed circuit board as a cathode is arranged.

At this time, the distance between the positive electrode and the printed circuit board is set to be about 30 cm. And FIG.
Are inserted between the positive electrode a and the printed circuit board b. The adjusting plates c1 and c2 each have a rectangular through hole having a width of 20 mm as shown in FIG.
It is configured to be arranged at intervals. The plating solution is filled with a copper nitrate solution having a concentration of 75 g / liter so that the electrodes and the printed board are completely immersed. Then, a direct current is applied to apply copper plating to the printed circuit board.

FIG. 3 shows a sectional structure of a printed circuit board b plated by the plating apparatus of FIG. In FIG. 3, outermost layers A and B are a copper plating layer on the control plate side and a copper plating layer on the opposite side, and the substrate material copper foils C and C
There is an insulating base material D at the center.

Then, while adjusting the opening ratio of the through-hole of the adjusting plate, a plating process was performed in which a direct current of 20 A / m ² was passed for 35 minutes, and the thickness of the copper plating tanks A and B thus formed is shown in the following table. .

Table opening ratio (%) Adjusting plate side plating thickness A Opposite side plating thickness B 50 (max) 22 27 40 18 26 30 15 28 20 11 26 10 8 28 By adjusting the thickness, the plating thicknesses A and B can be greatly different between the adjustment plate side and the opposite side.

[0019]

According to the present invention, as described above, a printed circuit board as the other electrode is arranged between a pair of electrodes provided in the plating tank in a plating tank filled with a plating solution. When plating a through hole in a printed circuit board, the amount of ion flow between one of the pair of electrodes and the printed circuit board is made different from the amount of ion flow between the other electrode and the printed circuit board. It is possible to provide a printed board in which the plating thickness on the front and back of the board is changed.

Since the plating process is performed by interposing an adjusting plate having a through hole between one of the pair of electrodes and the printed board, the amount of ion flow can be changed with a simple configuration.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is an explanatory view showing a configuration example of an adjustment plate used in the embodiment shown in FIG.

FIG. 3 is a sectional view showing a sectional structure of a printed circuit board b plated by the plating apparatus of FIG. 1;

[Explanation of symbols]

 a Electrode b Printed circuit board c Adjustment plate X Through hole A Copper plating on adjustment plate side B Copper plating on opposite side C Board material copper plating D Insulation base material

Claims (4)

[Claims] In a plating bath filled with a plating solution, a printed circuit board as the other electrode is disposed between a pair of electrodes provided in the plating bath, and plating is performed on through holes in the printed circuit board. In the through-hole plating method for a printed circuit board to be processed, the ion fluidity between one of the pair of electrodes and the printed circuit board by interposing an object between the other of the pair of electrodes and the printed circuit board. A through-hole plating method for a printed circuit board, wherein the plating treatment is performed so that the plating thickness on the front and back surfaces of the printed circuit board is different by lowering the ion fluidity between the two. 2. A printed circuit board as the other electrode is disposed between a pair of electrodes provided in the plating tank in a plating tank filled with a plating solution, and plated through holes and the like in the printed circuit board. In a through-hole plating apparatus for a printed circuit board to be processed, wherein a plating process is performed by interposing an adjustment plate having a through hole between one of the pair of electrodes and the printed circuit board. PCB through-hole
Plating equipment. 3. The through-hole plating apparatus for a printed circuit board according to claim 1, wherein said adjusting plate has a function of restricting a flow amount of copper ions. 4. The through-hole plating apparatus for a printed circuit board according to claim 1, wherein a plurality of said adjusting plates are arranged so as to be mutually movable.