JPS5816625B2 - 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. 58,118/1982 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 treatment at high speed within the through holes, it is possible to increase the current density by improving the diffusion layer on the surface of the first treated object.
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. The current per unit area (di) was limited to 2 to 3 A, but the speed has been significantly increased, and even when processed at a current density of 15 A/dmj, no burns or variations in film thickness occur. Plating processing time is approximately
It was shortened to tassel.

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.
, if the liquid injection speed is 4rrys, the current density is $ 12
'/dyl, the effective plating range of the substrate was found to be ±250 degrees with reference to the height equivalent to the position of the liquid injection tube.

In order to eliminate the drawbacks of the prior application, the present invention has been developed based on the experimental results in which the area on the substrate plane that can be covered by one liquid injection tube is determined by factors such as the liquid injection speed. By arranging the liquid jet tubes at a pitch and reciprocating the group by a distance corresponding to the pitch, uniform plating can be performed at high speed across the left and right or top and bottom ends of the substrate plane. .

As a result, the reciprocating distance of the liquid injection tube is shortened, and since the liquid injection tube does not remain stationary relative to the substrate, uniform high-speed processing is possible, and the equipment is extremely economical.

Examples will be described below with reference to the drawings.

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

FIG. 3 is a partially sectional side 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, 4' is an expansion pipe thereof, 5 is a pump, 6 is a suction pipe, and 7 is an electrode.

The above configuration is the same as the previous application. A frame 10 supports a plurality of liquid injection tubes 3 at the same pitch, and the frame 10 is reciprocated up and down by an air cylinder 8 as a reciprocating drive device.

That is, the pitch P becomes the round trip distance.

In this case, the frame body 10 is made into a hollow body, and the liquid injection pipe 3 and the piping 4 are
It also serves as

The air cylinder 8 is supported by a support 9 fixed to the upper edge 1' of the tank wall, and is controlled by a control device (not shown) to reciprocate the frame 10 by a pitch P, and the speed can be varied. It is.

Note that FIG. 3 shows a different embodiment in which the frame body 10 reciprocates in the left-right direction.

Note that 14 is a rail. The overflow tank 11 is provided with the same purpose as the suction pipe 6.

That is, the liquid is sucked in by the pump 5 on the upper side of the tank 1 to enhance the stirring effect of the liquid and to adjust the flow of the injected liquid smoothly.

However, the suction of liquid is not limited to the bottom and top as described above.

Reference numeral 12 denotes a hanging tool for suspending the substrate 2 and connecting the cathode 7.

Reference numeral 13 is a steadying device which prevents the lower side of the substrate 2 from swinging due to liquid jetting, and is fixed to the bottom of the plating tank 1.

The structure is preferably U-shaped with an upward concave shape.

A collection of the piping 4, expansion pipe 4', pump 5, absorption pipe 6, etc. is collectively referred to as a pressurizing device.

Next, to outline the operation, first, the substrate 2 is immersed in the plating bath 1 in a conventional manner, and the plating process is performed by using this as a cathode and the other electrode 7 as an anode, and supplying power from a power supply device (not shown).

The frame 10 has an area determined by the facing distance between the liquid injection tube and the substrate, the liquid injection speed, etc. (the area that can be effectively plated on the substrate plane if one liquid injection tube is kept stationary). Since each injection pipe is assigned a share, the frame body 10 is moved up and down by the pitch P using the air cylinder 8, without moving the injection pipe across the top and bottom of the processing liquid as in the previous application.

On the other hand, when the pump 5 is operated, the plating liquid in the plating tank 1 is sucked through both the suction pipe 6 at the bottom of the tank and the overhaul tank 11 on the top surface of the processing liquid, and passes through the pipe 4 and the telescopic pipe 4' to the hollow part of the frame. The liquid is pressed and fed under pressure to a plurality of liquid injection pipes 3 provided in the frame.

The embodiment shows a state in which the processing liquid is sprayed from both sides of the substrate 2.

In this case, the injection tube 3 is located between the substrate 2 and the electrode 7, but since it is constantly moving, there is no electrical problem.

In a flat plate counterelectrode 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 injection port 3' in the center may be made narrow, or the both ends of the injection tube 3 may be covered with masking material. The problem can be solved by covering it with water.

As explained above, the facing distance between the liquid injection tube and the substrate is 200
Dragon, liquid jet speed is 4m! By moving the frame 10 back and forth by the pitch P at 1/s, the current density increased to 12 AA=, making it possible to further speed up the plating process. A good plating process was achieved, and a uniform plating thickness was obtained within all through holes.

Furthermore, the present invention eliminates the drawbacks of the prior application, streamlines equipment costs, is effective in terms of operation, and is extremely productive as a through-hole plating method and apparatus for printed wiring boards.

BRIEF DESCRIPTION OF THE DRAWINGS: Fig. 1 is a partially sectional side view of the present invention, and Fig. 2 is a plan view thereof.

FIG. 3 is a partially sectional side view of a different embodiment.

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, 8...Air cylinder, 10
...Frame body, 11...One overflow tank, P...Pitch.

Claims (1)

[Scope of Claims] 1. In the through-hole plating process of a printed wiring board, a plurality of liquid injection pipes for injecting a plating solution into the through-holes of the printed wiring board are provided in a frame at a constant pitch, and the frame Through-hole plating of a printed wiring board characterized by plating while reciprocating the body by a stroke corresponding to the pitch and spraying a plating solution from the injection port of a liquid injection pipe into the through-hole of the printed wiring board. Method. 2. Claim 1, in which plating is performed by spraying a plating liquid from both the front and back surfaces of the printed wiring board.
Through-hole plating method for printed wiring boards as described in Section 2. 3. A plating bath for accommodating printed wiring boards to be plated through-holes, a plurality of injection pipes attached to the plating bath for injecting plating solution into the through-holes of the accommodated printed wiring boards, and the injection tubes. A frame body on which pipes are mounted at a constant pitch, a reciprocating drive device for reciprocating the frame body by a stroke corresponding to the constant pitch, and pressurizing plating liquid in a plating tank and supplying it to the liquid injection pipe. A through-hole plating device for printed wiring boards, comprising a pressurizing device for plating, and capable of plating while spraying a plating solution into the through-holes. 4. The printed wiring according to claim 3, wherein the frame body 10 is located in a plating tank and is capable of vertically reciprocating movement, and is formed of a hollow material, and the frame body 10 also serves as a conduit. Through-hole plating equipment for substrates. 5. A through-hole in a printed wiring board according to claim 3, which is a frame 10 that is located in a plating bath and is movable back and forth in the left and right directions, and is made of a hollow material and also serves as a conduit. Plating equipment. 6. The through-hole plating apparatus for a printed wiring board according to claim 3, which is a reciprocating drive device having a function of varying the number of reciprocating movements per minute.