JPS5818798B2 - 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 through-hole plating during the substrate manufacturing process is extremely long compared to, for example, an etching process.

Therefore, shortening the through-hole plating time directly leads to improving the production efficiency and reducing the cost, which governs the efficiency of this manufacturing process.

Therefore, as a means of high-speed plating, the applicant previously proposed in Japanese Patent Application No. 58118/1983 a method and apparatus for injecting plating solution onto the substrate from a reciprocating liquid injection tube.

In other words, in order to perform uniform plating processing at high speed within the through holes, the current density is increased by improving the diffusion layer on the surface of the workpiece, along the plane of the substrate.
For example, in the case of copper pyrophosphate, the substrate is plated by spraying a plating solution into the substrate, especially through holes, from a liquid injection tube configured to move back and forth from one end face to the other end face. Compared to the current limit of 2 to 3 A per unit area (di) of plating, the speed has been significantly increased, and there is no burning or variation in film thickness even when processing at a current density of 15 A/dm. Processing time is approximately 115 ~
Shortened to 1/7.

However, according to Japanese Patent Application No. 54-58118, in order to reciprocate the liquid injection tube from one end to the other end while facing the substrate plane, the reciprocating device for the liquid injection tube becomes complicated. If the direction of reciprocating transfer is the vertical direction of the plating tank, the transfer device must be configured to avoid the transport device for transporting the substrate that travels above the plating tank, and in large plating processing equipment, liquid injection Since the reciprocating distance of the tube becomes longer, various technical problems have arisen that need to be improved, such as the need to increase the moving speed of the liquid injection tube in order to maintain a constant quality.

Subsequent research confirmed that even higher speeds could be achieved by varying the distance between the poles, the moving speed of the liquid injection tube, and the injection liquid speed.

In addition, when the liquid injection tube position equivalent is set to a low speed, it was quantitatively clarified that the range of the substrate where the diffusion layer can be improved varies depending on the liquid injection speed and the like.

Specifically, the facing distance between the liquid injection tube and the substrate is 200 mm,
When the liquid injection speed is 4 m/B, the current density is 12
It was found that the effective plating range of the substrate in A/dm was ±250 m with reference to the height equivalent to the position of the liquid injection tube.

Therefore, the applicant proposed in Japanese Patent Application No. 114292/1983 that multiple liquid injection tubes were arranged at a constant pitch based on the experimental results that determined the area on the substrate plane that could be covered by one liquid injection tube according to factors such as the liquid injection speed. We have proposed a system in which uniform plating is performed at high speed across both left and right or top and bottom ends of the substrate plane by arranging them and reciprocating the group of liquid jet tubes by a distance equivalent to the pitch.

As a result, the reciprocating distance of the liquid injection tube is shortened, and since the liquid injection tube does not continue to stand still against the substrate, uniform and high-speed processing can be performed, and this greatly contributes to the cost of the apparatus.

In the present invention, by arranging a plurality of liquid injection tubes at a constant pitch and reciprocating the substrate by at least a distance equivalent to the pitch, as a result, the liquid ejecting tubes are arranged at a constant pitch, and as a result, the liquid ejecting tubes are reciprocated across the left and right and upper and lower ends of the substrate plane. We focused on the fact that not only can uniform plating be performed at high speed, but also high-speed, high-quality plating can be done inside through-holes as well.
Ru.

-As a result, compared to the above invention, when plating both sides of the substrate, there is no need to move two liquid injection pipes,
It does not need to be operated underwater, making it an extremely effective dog.

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

FIG. 1 is a side sectional view of the present invention, and FIG. 2 is a plan view.

FIG. 3 is a side cross-sectional view of a different embodiment in which reciprocating motion is performed in the lateral direction.

1 is a plating processing tank, 1' is the upper edge of the tank wall, 2 is a substrate, and 2' is a through hole thereof.

3 is a liquid injection pipe, and 3' is its injection port.

4 is a pipe outside the tank for circulating the processing liquid, and 41 is a branch pipe inside the tank branched from the pipe 4, and the illustration shows four branch pipes rising up.

5 is a processing liquid circulation pump.

The liquid injection pipe 3 equipped with a large number of injection ports 3' is a branch pipe 4'.
Both are arranged with the same pitch P.

Note that the injection port 3' is not limited to a round shape, but may be slit-shaped.

Reference numeral 6 is a transport frame, which is equipped with a hanging tool 6' to which the substrate 2 is attached, and is configured to be able to reciprocate up and down by a pitch P by means of an air cylinder 7 via a reciprocating moving tool 8 (Figs. 1 and 2). figure).

That is, the conveyance frame moves up and down on the frame support 9.

Accordingly, the substrate 2 to which the hanger is attached is reciprocated up and down by the pitch P within the plating tank as the transport frame 6 moves.

The reciprocating transfer device 8 and the air cylinder 7 are collectively referred to as a reciprocating drive device.

A frame support 9 provided at the upper edge 1' of the plating bath 1 can be used as a power supply plate for the substrate 2.

Further, the air cylinder 7 reciprocates the transport frame 6 by a pitch P by a control device (not shown), and its speed can also be varied.

Incidentally, the piping on the suction side of the pump 5 may be connected to an appropriate position as shown by the chain line in FIG. 2 so that the plating liquid in the plating tank 1 can be sucked in.

Also, FIG. 3 shows a different embodiment, and the difference from the above is that the cylinder 7 and the reciprocating device 8 are installed horizontally, so that the conveyance frame 6 reciprocates in the left-right direction, and as a result, the substrate 2 also reciprocates in the left-right direction. Since it moves, the liquid injection pipe 3 is also erected.

Next, to outline the operation, first, the substrate 2 attached to the transport frame 6 carried by a transport device (not shown) by a conventional method is immersed in the plating bath 1, and this is used as a cathode, and the other electrode 10 is shown as an anode. The plating process is performed by supplying power from the power supply unit.

The liquid injection pipe 3 has a branch pipe 4' for facing the liquid injection pipe 3 and the substrate 2': X1, an area determined by the liquid injection speed, etc. Assuming that the carrier frame 6 is mounted so as to share the range that can be effectively plated on the plane of the substrate, the transport frame 6 is moved up and down by the pitch P using the air cylinder 7.

On the other hand, the pump 5 is operated to suck the plating solution in the plating tank 1 through the suction pipe 4, and press it to the liquid injection pipe 3 through the branch pipe 4', and the large number of injections provided in the injection pipe 3 The processing liquid is ejected from the opening 3' toward the substrate 2 and the through hole 2'.

The embodiment shows a state in which the ink is ejected from both sides of the substrate 2.

In this case, the ejection pipe 3 is located between the substrate 2 and the electrode 10, but since the substrate 2 is always moving, there is no electrical problem in the relationship between the electrode 10 and the substrate 2.

In a flat plate counter electrode electrical system, the current density at the center of the flat plate, that is, the substrate 2, is low, so for that purpose, the diameter of the jet nozzle 3' in the center can be made narrow, or the both ends of the jet tube 3 can be covered with masking material. The problem can be solved by covering it with water.

However, according to experimental results, it has been confirmed that when the liquid jetting speed is set to 4 m/s or more, a uniform finish can be obtained over the entire surface without taking such measures.

As explained above, the facing distance between the liquid injection tube and the substrate is 200
The current density was increased to 12 A/dm by reciprocating the substrate 2 by the pitch P at a liquid jetting speed of 4 m/s, which made it possible to further speed up the plating process, and only the substrate 2 was moved up and down. As a result, we were able to perform a good plating process on the entire board, and even in all the through-holes, we were able to obtain a uniform plating thickness.

Furthermore, by moving the board 2 up and down as in the present invention, the drawbacks of the previous application are overcome, equipment costs are rationalized, the operation is effective, and the method and apparatus for through-hole plating of wiring boards are even more productive. It became a thing.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of the present invention, and FIG. 2 is a plan view thereof. FIG. 3 is a side sectional view of a different embodiment. 1...Plating tank, 2...Substrate, 21.
...Through hole, 3...Injection pipe, 31
...Injection port, 4'...Branch pipe, 6...
...Transportation frame, 7...Air cylinder, 8.
...Reciprocating transfer tool, P...Pitch.

Claims (1)

[Claims] 1. In the through-hole plating process of printed wiring board 2, board 2 is hung vertically on a transport frame, immersed in a plating bath, and horizontally placed in the tank at a fixed pitch. The processing liquid is continuously injected from a large number of jetting ports arranged in a plurality of liquid jetting pipes (or vertically installed), and the substrate 2 is reciprocated up and down (or reciprocated left and right) at a constant pitch. A through-hole plating method for printed wiring boards, characterized in that plating is performed using a processing solution. 2. The through-hole plating method for a printed wiring board according to claim 1, wherein plating is performed while spraying a plating solution from both the front and back sides of the printed wiring board 2. 3. A plating bath 1 for accommodating a printed wiring board 2 to be plated through-holes, and a plurality of tubes for spraying a plating solution into the through-holes 2' of the printed wiring board installed in the plating bath. It consists of an injection pipe 3, a reciprocating drive device for reciprocating the injection pipe by a stroke equivalent to a fixed pitch, and a pressurizing device for pressurizing the plating solution in the plating tank and supplying it to the injection pipe. A through-hole plating device for printed wiring boards, which is capable of plating while spraying a plating solution into the holes. 4 The reciprocating drive device includes the air cylinder 7 and the reciprocating transfer tool 8
A through-hole plating apparatus for a printed wiring board according to claim 3.