JPS636159B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plating apparatus that performs uniform pattern plating on printed wiring boards used for electronic parts and the like.

There are two ways to form electrical circuits, so-called patterns, on a printed wiring board: first, the entire surface of the printed wiring board is plated, then masked and etched to leave only the patterned area; and the other is to apply insulating paint to the area other than the patterned area in advance. It can be roughly divided into two methods: pasting it on and then plating it on the pattern area. Generally, the ratio of the pattern portion to the entire surface of a printed wiring board is 20 to 30%. Therefore, from the standpoint of saving resources and energy, the latter pattern plating method is increasingly being adopted.

Conventionally, the pattern plating is carried out by immersing the printed wiring board in a processing tank equipped with electrodes and applying electricity. This will be explained with reference to FIGS. 2 and 3. An electrode 4 made of a conductive material is suspended from an electrode support rod 2 provided in a processing tank 5. Then, the printed wiring board 3 suspended from the transport frame 1 is immersed between the electrodes by a crane (not shown). The reason why the electrodes 4 are on both sides in the figure is because both sides of the printed wiring board are plated at the same time. In FIG. 3, the anode of the power supply device 6 is connected to the electrode 4 via the electrode support rod 2, and the cathode is connected to the printed wiring board 3 via the transport frame 1. By the way, the printed wiring board to be patterned is the first
As shown in the figure, when pattern plating is applied only to areas 8 and 8' in the figure, in the planar counter electrode electrical system, the current concentrates near the area 9 where there is no pattern or where the pattern is sparse due to the tip effect, resulting in a thick film. Ta.
In order to solve this drawback, technical measures have conventionally been taken in which dummies are attached to sparse portions 9, etc., so that the current distribution appears to be uniform. However, this method is undesirable in terms of resource conservation because it is also attached to a dummy.

The present invention eliminates these drawbacks and provides an apparatus that can reliably perform pattern plating of a uniform film while saving resources and energy. Examples will be described in detail below with reference to the drawings.

FIG. 4 is a perspective view of the main parts of the plating apparatus according to the present invention, and FIG. 5 is a power supply connection diagram according to the present invention. 6 and 7 are similarly different power supply connection diagrams. As an example, first, as shown in FIG. 1, the case where the same patterns 8 and 8' are provided on both planes of the printed wiring board 3 and is to be plated will be described. 8 is a dense pattern, 8' is a sparser pattern, and 9 is no pattern. The printed wiring board 3 is hung on the transport frame 2, and as shown in FIG.
It can be immersed so as to be located between 4 and 4. In this case, the electrode 4 is divided into four parts by the insulating frame 7. These divided portions 4-1, 4-2, 4-3, and 4-4 are respectively referred to as electrode elements. Therefore, the more electrode elements there are, the easier it will be to plate a uniform film when various patterns are formed on the same substrate 3.
A plurality of printed wiring boards 3 may be hung on the transport frame 1, and even if they have different patterns, it is applicable. An anode of a power supply device 6-1 is connected to the electrode element 4-1. That is, N power supply devices and N electrode elements are connected one-to-one. In this case, it is possible to connect the electric wire directly to the electrode element in practice, but it is more convenient to connect the electrode support rod 2 to the electrode element with a bus bar or the like, and then connect the power supply device 6 and the electrode support rod 2. be. On the other hand, the cathodes of each of the power supply devices 6-1 to 6-4 are connected to the transport frame 1 and to the printed wiring board 3 hung thereon. Therefore, when the patterns on one side and the other side of the printed wiring board 1 are different, it is sufficient to use different power supply devices on both sides as shown in FIG. 6, and connect each power supply device to the electrode element. .
If the pattern is uniform only on one side, the electrode on the right side in FIG. 6 may be used as one electrode element as shown in FIG. 7, and only one power supply device may be used.

Next, to outline the operation, the printed wiring board 3 shown in FIG.
Soak for 4 hours. When the transport frame 1 is placed in the processing tank 5, the cathodes of each power supply device 6-1 to 6-4 are connected to the printed wiring board 3 via the transport frame 1 by a conventional means.
connected to. As described above, the power source 4 is divided into four by the insulating material 7, and the power devices 6-1 to 6-4 are connected to each electrode element 4-1 to 4-4 on a one-to-one basis. Each power supply device has the same capacity, and in this case, the power supply capacity of ^one unit shown in FIG. /4. When each power supply device is activated, current is applied between each electrode element and the printed wiring board 3, and plating is performed. If we assume that the energization setting value of each power supply device is the same, the current will flow from the electrode elements 4-2 and 4-3 corresponding to the areas without pattern 9, just as in the conventional method shown in FIGS. 2 and 3. is distributed into patterns 8 and 8', resulting in patterns 8 and 8'.
8' is plated at a current density exceeding the allowable current density, resulting in "scorching" and loss of product value.
Even if the film does not become discolored, the film becomes thicker, for example, on the periphery of the pattern 8, especially near the area 9 where there is no pattern, and the film lacks uniformity, resulting in a defective product. Therefore, the power supply devices 4-2 and 4-3 are made stationary, the power supply device 4-4 is adapted to pattern 8, and the power supply device 4-4 is made stationary.
1 is operated with the set value adapted to pattern 8'. That is, it is possible to perform plating with a permissible current density determined from the composition of the plating solution, the physical properties of the plated object, and the production efficiency. In this case, the power supply capacity of one unit becomes 1/N of the number of divisions N, which results in a smaller size. Furthermore, it can be made even more compact as a high frequency power supply device.

As described above, the present invention makes it possible to operate the permissible current value according to the density of the pattern, and at the same time, the pattern can be coated with a uniform and high-quality plating, and at the same time, the power supply device of unnecessary parts can be set at a low value or completely stopped. This makes it possible to contribute to energy conservation and cost reduction.

[Brief explanation of the drawing]

FIG. 1 shows a printed wiring board to be pattern plated, FIG. 2 shows a conventional plating apparatus, and FIG. 3 shows a conventional power supply connection diagram. FIG. 4 is a perspective view of a plating apparatus showing the main parts of the present invention, FIG. 5 is a power supply connection diagram according to the present invention, and FIGS. 6 and 7 are different power supply connection diagrams according to the present invention. 1... Transport frame, 2... Power support rod, 3... Printed wiring board, 4... Electrode, 4-1... Electrode element, 5... Processing tank, 6-1..., 6-N ……
Power supply device, 7... Insulator, 8... Pattern, 9...
...A part with no pattern or a part with a sparse pattern.

Claims (1)

[Claims] 1. Immerse the printed wiring board suspended in the transport frame in the processing tank so that it faces the electrodes provided in the processing tank,
In a plating device that conducts plating with electricity, the electrode is made up of N electrically insulated elements, and N power supplies are provided, each corresponding to the N electrode elements.
The N anodes of each power supply device are respectively connected to the corresponding electrode elements of the electrodes, and the cathodes of all power supply devices are configured to be connected to the printed wiring board via the transport frame or directly, so that the printed wiring board A pattern plating device for a printed wiring board, characterized in that the amount of current applied can be adjusted according to the density of the pattern to be plated.