JPS5826546Y2 - Auxiliary cathode for plating printed circuit boards - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an auxiliary cathode used in plating printed circuit boards.

When manufacturing printed circuit boards, plating is usually applied during the solder adhesion process to conductive through-hole parts or conductive pattern parts. It is common practice to perform electroplating with a separately immersed anode metal to obtain a predetermined plating thickness using an appropriately set time and current density.

This state is shown in the schematic diagram of FIG. 1. Reference numeral 1 denotes a plating bath, in which a printed circuit board 3 held by a hanging device 2 is immersed in a built-in plating solution, and one end thereof is connected to a negative electrode.

When electroplating is performed between the separately immersed positive electrode metal (not shown) in this way, due to the influence of the current density distribution, both sides of the printed circuit board 3 and near the bottom (
There is a tendency for the plating thickness to be larger in the portion 3' indicated by the dashed line in FIG. 1 than in other portions.

The above-mentioned tendency becomes more pronounced as the current density is increased in order to increase the plating speed, and it is also exacerbated as the shape of the object to be plated, such as a substrate, becomes larger.

The above 3' part not only has a large plating thickness, but also causes irregularities due to deterioration of the plating assembly, so-called clouding phenomenon, which adversely affects electrical characteristics.To prevent this, current Measures have been taken to reduce the ratio of negative effects, such as reducing the density and working for long periods of time, or increasing the capacity of the plating bath, but these all cause a decrease in efficiency and an increase in costs, and the root cause is This is not a practical solution.

The present invention has been devised in view of the above, and aims to eliminate the drawbacks of the conventional plating methods described above, provide a means for obtaining uniform plating thickness, and improve mass productivity. In order to achieve the above purpose, a conductive material is attached to the inside of a U-shaped base material to serve as an auxiliary cathode.
The present invention discloses a length adjustment mechanism for an auxiliary cathode for plating a printed circuit board, characterized in that the auxiliary cathode is immersed in a bath containing a plating solution.

FIG. 2 shows an embodiment to which the present invention is applied.
Reference numeral 11 denotes a plating tank containing a plating solution, and an auxiliary cathode, such as a conductive material 13 attached to the inside of a U-shaped base 12, is inserted into the tank.

Although the material may be selected as appropriate, a non-conductive plate made of synthetic resin is prepared as the base material 12, and the conductive material 1 on the inner side of the non-conductive plate is prepared.
A negative electrode 14 is provided on the edge of the plating bath 11, and a conductive material 13 is connected to the conductive material 13 by a wire 15.
is connected with.

On the other hand, reference numeral 16 denotes a movable suspension device for transporting and vertically moving the board, etc., which is constructed using a conductor, and moves and ascends and descends while holding the printed circuit board 19 with a holding piece 17 and a clip 18. It acts like tightening.

In the above state, when the printed circuit board 19 is immersed in the plating liquid by descending as shown by arrow A, one end of the movable suspender 16 holding the board is connected to the negative electrode as shown by the imaginary line. 14, a charge is applied to the printed circuit board 19 and the plating process is started.

Electroplating is performed by applying ten charges to a separately inserted positive electrode metal (not shown) and maintaining the set time and current density.

According to this embodiment, due to the influence of the current density distribution, the phenomenon of increase in plating thickness on both sides of the substrate and near the bottom 3', which occurred in FIG. The effect is that no adverse effects occur within the circuit board 19.

In other words, the increase in plating thickness and the accompanying clouding phenomenon that tend to occur in the conventional 3' portion are not transferred to the auxiliary cathode, thereby making it possible to obtain a uniform plating thickness over the entire surface of the printed circuit board 19. It is possible.

The auxiliary cathode can be used repeatedly, and if it becomes enlarged due to plating metal, it can be replaced or regenerated.

The auxiliary cathode of the present invention is as shown in Figure 3, A2.

That is, when changing the size of the printed circuit board 19 as the object to be plated, it is necessary to change the size of the auxiliary cathode.
First, when it is desired to move the auxiliary cathode in the vertical direction relative to the wall surface in the plating bath, the joint portion between the base material 12 and the conductive material 13 shown in FIG. By making it so that it cannot be easily removed in the lateral direction, it can be slid only in the vertical direction, and only the conductive material 13 can be moved up and down depending on the size of the substrate.

In this case, the joint B' near the bottom in FIG.
/ may be joined arbitrarily.

Next, move the auxiliary cathode in a direction perpendicular to the vertical direction, that is, in the bottom direction (
If you want to move the conductive material 13 in the horizontal direction (in the lateral direction in Fig. 2), the connection at the C part in Fig. 2 should be devised so that it fits into the recess provided on the side of the conductive material 13 provided in the bottom direction as shown in the opening in Fig. 3. The conductive material 13' may have a structure having a convex portion, and the conductive material 13' may be freely moved laterally as shown by the arrow to match the size of the substrate to be plated.

The length adjustment mechanism of the auxiliary cathode as described above is merely an example of implementation, and is not limited to the concavo-convex mechanism shown in the drawings.

The structure and operation of the auxiliary cathode for plating printed circuit boards according to the present invention have been explained above, and by applying the present invention, the following advantages and effects can be achieved.

In other words, irregularities caused by the size of the plating thickness and deterioration of the plating composition that tend to occur when conventionally plating printed circuit boards can be transferred to the auxiliary cathode. This eliminates all negative effects.

Furthermore, since there is no need to worry about the conventional clouding phenomenon, it is possible to increase the current density and increase the plating efficiency, which shortens the plating process time and greatly improves workability and mass productivity. Contribute.

Since the plated printed circuit board has a uniform plating thickness, it is possible to measure the electrical characteristics and, ultimately, the quality of the product.

Moreover, since the auxiliary cathode is installed in the plating bath and the spacing in the vertical and horizontal directions can be adjusted according to the shape of the printed circuit board to be plated, the shape of the printed circuit board to be plated can be adjusted. In particular, even if the sizes are different, the distance between the printed circuit board and the conductive material can be maintained constant, and irregularities due to variations in the plating thickness of the printed circuit board or changes in the plating composition will not occur, so It is extremely convenient and can be applied to all substrate materials whose shapes vary widely, and can be adjusted simply by moving the conductive material to match the shape of the printed circuit board. The hanging device for holding the printed circuit board also has great effects, such as being able to use a conventional simple hanging device that can be used regardless of the size of the printed circuit board.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a conventional plating device, and FIG. 2 is a plating device to which the present invention is applied and its mode of operation.
Figure 3A shows the adjustment mechanism for the auxiliary cathode. 1.11...Plating tank, 2...Hanging tool, 3,19...Printed circuit board, 12...
Base material, 13.13'... Conductive material, 14...
...Cathode, 15...Wire, 16...
...Moving suspension device, 17...Holding piece, 18...
····clip.

Claims (1)

[Scope of utility model registration request] A U-shaped base material is attached to the inner surface of the plating tank that stores the plating solution, and the inside of this base material is provided with adjustable spacing in the vertical and horizontal directions to match the shape of the printed circuit board to be plated. An auxiliary cathode for plating printed circuit boards characterized by being equipped with a U-shaped conductive material.