JPS5821840B2 - Through-hole plating method and device for printed wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a through-hole plating method and apparatus for a printed wiring board (hereinafter referred to as a board), and its purpose is to achieve high-speed plating and obtain high-quality plating with uniform thickness.

The processing time required for the through-hole plating process in the manufacturing process of the substrate is extremely long compared to, for example, the etching process.

Therefore, shortening the through-hole plating time improves production efficiency and directly leads to cost reduction.

As a high-speed means for this purpose, the applicant proposed a method and apparatus for spraying the plating solution onto the substrate from a reciprocally movable liquid spray tube in Japanese Patent Application No. 58,118/1982.

According to that method, 158/
High-speed operation with a high current density of dm2 is now possible.

Also, by improving the diffusion layer, the distance between the substrate plane and the anode, which was previously around 300 mm, has been increased to 150 mm.
Even before and after, the film variation was comparable to that of 300ii.

The present invention was developed based on the results of such research in order to achieve even higher quality and higher speed processing.

The gist of this is that the liquid is sprayed and concentrated on the plane of the substrate where the diffusion layer can be improved the most, increasing the current density to speed up the plating process, and moving back and forth to successively cover the entire plane of the substrate. Electroplating is carried out using an anode that moves along with the liquid injection tube.

Alternatively, depending on the size of the substrate, a stationary anode may be provided in addition to the reciprocating anode.

In other words, in a conventional flat counter electrode electrical system in which a flat plate substrate and a flat anode face each other, the current density is determined as the average value over the entire substrate plane, so more current is passed at the point where the liquid jetting effect is best. Also good.

The best place for this liquid jet effect is where the liquid jet hits vertically or very close to it.

If plating is performed while improving the diffusion layer over the entire surface of the substrate by spraying a liquid, the distance between the electrodes can be significantly narrowed compared to the conventional method (for example, simply stirring the liquid in the plating bath). , the fruiting device can be miniaturized, and the voltage decreases with respect to the current density, contributing to a reduction in power consumption.

Therefore, if the current density is set to match the area where the diffusion layer is most improved, the overall speed can be further increased.

Therefore, high speed was achieved by providing an anode near the liquid injection tube that was formed to reciprocate in synchronization with the liquid injection tube.

When plating is performed with the above configuration, the current that flows due to the current tip effect is low at the center of the substrate plane and high at the periphery, resulting in the effect of eliminating non-uniformity in the plating thickness.

This is because when the liquid jet tube faces the side surface of the substrate once, its central portion faces twice.

Also, depending on the condition of the substrate, stable plating can be achieved by coexisting a stationary electrode in addition to the moving electrode.

The structure will be described in detail below with reference to the drawings.

The figure is a side sectional view of the through-hole plating apparatus for substrates according to the present invention, with a part of the plating tank cut away.

1 is a plating treatment tank, which continues toward the left in the figure.

2 is a side cross section of the substrate, and 2' is a required number of through holes formed on the surface of the substrate 2.

3 is a liquid injection tube whose length is generally longer than the medium length of the substrate, and the figure shows its cross section, and 3' is an injection port with a required number of openings in the longitudinal direction of the liquid injection tube. The direction of is directed toward the substrate 2.

Reference numeral 6 denotes a suction pipe for the tank liquid that opens at the bottom of the tank, 5 a pump, 4 a pipe, and 4' a telescopic tube, which constitute a pressurizing device for the tank liquid jetted from the liquid injection pipe.

Reference numeral 7 denotes a power source (not shown), which is a transition electrode installed on both sides (upper and lower in the figure) of the liquid injection pipe 3 and parallel to the longitudinal direction with approximately the same length as the liquid injection pipe. The conducting wire 11 has a sufficient length for vertical movement.

Numeral 10 is a pair of gears disposed on the upper edge 1' of the tank wall, and is driven by a motor (not shown).

In the figure, the gears 10 overlap, so only one gear is shown.

Note that 10" is a shaft. 10' is also the aforementioned gear 10.
The rotation is transmitted to the sprocket 8 by the gear meshing with the sprocket 8.

On the other hand, a similar sprocket 8' is installed near the bottom of the lower tank of the pair of sprockets 8, and the upper and lower sprockets l-8, 8
A chain 9 is stretched endlessly between them, and the above-mentioned liquid injection pipe and moving electrode are fixed to the substrate 2 side of the chain 9.

Note that the lower end (A in the drawing) of the telescopic pipe 4' is connected to the longitudinal end of the liquid injection pipe 3 to form a circulation pipe.

Next, to outline the operation, first, by the usual method;
is immersed in the plating bath 1, and the plating process is performed by using this as a cathode and the other electrode as an anode, and supplying power from a power supply device (not shown).

On the other hand, when the motor (not shown) is driven, the gear 10.10
The sprocket 8 rotates via '.

A chain 9, which is stretched between a lower sprocket 8' installed in the tank, rotates.

The rotation speed and rotation direction of the gear 10 can be adjusted and changed in a conventional manner by a control device (not shown), so the liquid injection pipe 3 is moved vertically between the upper and lower ends of the substrate 2 from the central position shown in the figure. Produces reciprocating motion.

On the other hand, when the pump 5 of the pressurizing device is driven, the plating liquid in the plating tank is sucked through the suction port 6 and is forcedly sent to the liquid injection pipe 3 via the piping 4 and the telescopic pipe 4', and is passed through the substrate 2 and especially through the liquid injection pipe 3. Since a strong plating liquid is sprayed into the hole 2' from the injection port 3', its diffusion layer is improved, and in addition, since the moving electrode is located very close, the current density is increased, making extremely high-speed plating possible. do.

Furthermore, depending on the state of the substrate 2, a stationary electrode 7' may be formed as shown in the figure.
By installing it on the back side of the liquid injection pipe, it is possible to perform stable stagnation treatment.

Generally, the stationary electrode 7' has approximately the same width and height as the substrate 2, and faces the water plate 2.

In this embodiment, the case where the liquid is sprayed only from one side of the substrate is illustrated, but the liquid may be sprayed from both sides, that is, from the right side in the figure, and there is no limitation.

As explained above, according to the present invention, in addition to being able to perform high-speed, high-quality plating processing as described above, it also reduces equipment costs and power costs, and greatly contributes to improving productivity.

[Brief explanation of the drawing]

The drawing is a side sectional view of a plating apparatus according to the present invention. 1...Plating treatment tank, 2...Substrate, 2
'...Through hole, 3...Liquid injection pipe, 3'...Injection port, 4...Piping, 4'
...Extensible tube, 5...Pump, 6...
...Suction pipe, 7...Moving anode, 7'...
・Stationary anode, 8.8'・・・Sprocket,
8"...shaft, 9...chain, 10.
10'...Gear, 10''...Shaft, 11
・・・・・・Conducting wire.

Claims (1)

[Scope of Claims] 1. In the through-hole plating process of a printed wiring board, a liquid injection tube configured to face each other along the plane of the printed wiring board and move back and forth, and an anode that moves in synchronization with the liquid injection tube. A method for plating through-holes in a printed wiring board, the method comprising: spraying a plating solution into the through-holes of the printed wiring board and applying electricity. 2. A plating bath for accommodating printed wiring boards to be through-hole plated, and a plating bath attached to the plating bath so that the accommodated printed wiring boards can be moved back and forth from one end to the other end face to face along the plane. It consists of a liquid injection pipe and an anode, and a pressurizing device for pressurizing the liquid in the plating tank and supplying it to the liquid injection pipe. A featured through-hole plating device for printed wiring boards. 3. The through-hole plating apparatus for a printed wiring board according to claim 2, wherein the reciprocating anodes are disposed parallel to each other and facing each other on both sides of the liquid injection tube. 4. A plating tank for accommodating a printed wiring board to be plated through holes, and a plating tank attached to the plating tank so that the stored printed wiring board can be moved back and forth from one end face to the other end face along a plane. a stationary anode disposed outside the liquid injection tube with respect to the printed circuit board, and a pressurizing device for pressurizing the liquid in the plating tank and supplying it to the liquid injection tube. A through-hole plating device for printed wiring boards, which is characterized by plating while spraying a plating solution into the through-holes.