JPH0256434B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to plating technology, and provides a novel diaphragm that can suppress the coarsening of the structure during thick plating and the generation of lump-like precipitates on the plating surface. It concerns the plating method.

[Conventional technology]

In electroplating, various types of plating are performed by immersing the anode plate and the object to be plated in a plating solution in a plating tank.In particular, when applying thick lead plating, the film thickness is 100μm.
When it reaches a certain level, the structure becomes coarser and so-called nodule-like precipitates are generated. This is thought to be caused by impurities present in the plating solution, and conventionally, as a means of suppressing the generation of lump-like precipitates, an anode bag is used to capture impurities that dissolve from the anode plate. We are taking measures to

[Problem that the invention seeks to solve]

However, with the above method of trapping impurities using an anode bag, due to the structure of the anode bag, it is not possible to prevent the slight leakage of impurities from seams and cracks, resulting in coarsening of the structure and lumps in the thick plating. However, it was not possible to completely prevent the formation of precipitates.

The present invention has been made in view of the above problems, and is a diaphragm plating method that eliminates the influence of impurities precipitated from the anode plate in the plating solution, refines the plating structure, and prevents the formation of lump-like precipitates. Its purpose is to advocate the law.

[Means for solving problems]

A diaphragm tank having a diaphragm is installed in the plating tank, and the plating solution in the diaphragm tank where the object to be plated is arranged and the plating solution between the diaphragm tank where the anode plate is arranged and the plating tank is separated several times. The plating solution between the diaphragm tank and the plating tank is partitioned by the diaphragm having micropores with an average pore diameter of microns or less, and the plating solution is circulated into the diaphragm tank via piping and a filtration device installed midway through the piping. The plating solution inside the diaphragm tank overflows into the space between the diaphragm tank and the plating tank, and the liquid level in the diaphragm tank is maintained at a higher level than the liquid level between the diaphragm tank and the plating tank.

[Effect]

According to the present invention, the side of the object to be plated and the side of the anode electrode plate are partitioned by the diaphragm of the diaphragm tank, and the liquid level in the diaphragm tank in which the object to be plated exists is controlled between the diaphragm tank in which the anode electrode plate exists and the plating tank. By maintaining the liquid level higher than the liquid level of the diaphragm, the liquid pressure in the diaphragm tank becomes relatively high, so impurities dissolved from the anode plate can enter the diaphragm tank through the micropores of the diaphragm. Or,
There have been no reports of impurities biting into the micropores and causing clogging, and these impurities are removed by a filtration device during the process in which the plating solution is circulated from between the diaphragm tank and the plating tank to the diaphragm tank via piping. Therefore, the plating solution around the object to be plated in the diaphragm tank is always maintained at a high purity.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a plating apparatus for carrying out the diaphragm plating method according to the present invention will be described below with reference to the drawings. Reference numeral 1 denotes a lead plating tank, in which a diaphragm tank 2 is disposed, and a plating solution 3 is stored between the two tanks 1 and 2 and in the diaphragm tank 2. A rectangular window 4 formed on the side surface of the diaphragm tank 2 is covered with a diaphragm 5 having fine holes. The anode plate 7 is suspended so as to be immersed in the plating solution 3, and the object a to be plated is suspended so as to be immersed in the plating solution 3 in the diaphragm tank 2. The above diaphragm tank 2
On the side of the plating liquid 3 level L1 between both tanks 1 and 2
A liquid overflow hole 8 is bored at a higher position, and the plating liquid 3 is configured to flow down between the two tanks 1 and 2 from the level L2 of the third surface of the plating liquid in the diaphragm tank 2 through the overflow hole 8. Become. As shown in FIG. 3, the diaphragm 5 has a porous structure (average pore diameter 0.1 μm
A membrane material 10 with a thickness of 1 to 10 μm is attached.
Reference numeral 11 denotes a filtration device installed outside the lead plating tank 1, in which the suction side pipe 12 is opened near the bottom of the lead plating tank 1, and the discharge side pipe 13 is opened into the diaphragm tank 2. .

In the plating tank configured as described above, the plating solution 3 is filtered through the filtration device 1.
1, the plating process is performed by applying a DC voltage of a predetermined voltage to the anode plate 7 and the object to be plated while constantly circulating in the direction of the arrow A. During the plating process, the overflow hole 8 is always kept closed. The plating solution 3 in the diaphragm tank 2
From surface level L2 to plating liquid level L1 of lead plating tank 1
Plating liquid 3 is flowing down. Furthermore, by setting the levels L1 and L2, the liquid pressure inside the diaphragm tank 2 in which the object to be plated a is immersed is lower than the liquid pressure outside the diaphragm tank 2 where impurities dissolved from the anode plate 7 are mixed. The pressure is also relatively high, and the plating solution flows inside the micropores of the diaphragm 5 toward the outside of the diaphragm tank 2. Therefore, impurities dissolved into the plating solution 3 from the anode plate 7 are prevented from entering the diaphragm tank 2 by the diaphragm 5. Further, the impurities are discharged from the suction side piping 12 to the filtration device 11 together with the plating solution 3, and are filtered and removed by the filtration device 11, and the purified plating solution 3 that can be reused is transferred to the discharge side piping. 12 into the diaphragm tank 2.

Therefore, the plating solution 3 free of impurities dissolved from the anode plate 7 is ensured in the diaphragm tank 2, and the plating structure can be refined in thick lead plating (film thickness of 100 μm or more).

〔Effect of the invention〕

As described above, the diaphragm plating method according to the present invention
In electroplating, a diaphragm is interposed in the plating solution between the anode electrode plate and the object to be plated, and the plating liquid on the anode electrode plate side is circulated to the object to be plated through a filtration device, thereby reducing the plating around the object to be plated. The liquid is always maintained at a high purity, and the liquid pressure on the object to be plated is maintained at a higher pressure than the liquid pressure on the anode plate due to the liquid level difference, so that impurities dissolved from the anode plate are not covered. It has excellent effects such as being able to prevent adhesion to plated objects and preventing clogging of the diaphragm due to impurities.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a diaphragm plating apparatus showing an embodiment of the plating apparatus for carrying out the diaphragm plating method according to the present invention;
FIG. 2 is a sectional view of the main part of the plating tank, and FIG. 3 is an enlarged sectional view showing the structure of the diaphragm. 1...Lead plating tank, 2...Diaphragm tank, 3...Plating solution, 5...
Diaphragm, 7... Anode plate, 8... Overflow hole, 11... Filtration device, 12... Suction side piping, 13... Discharge side piping.

Claims (1)

[Claims] 1 Install a diaphragm tank with a diaphragm in the plating tank,
The plating solution in the diaphragm tank in which the object to be plated is arranged and the plating solution between the diaphragm tank in which the anode plate is arranged and the plating tank are partitioned by the diaphragm having micropores with an average pore diameter of several microns or less. The plating solution between the diaphragm tank and the plating tank is circulated into the diaphragm tank via piping and a filtration device installed midway through the pipe, while the plating solution in the diaphragm tank overflows into the space between the diaphragm tank and the plating tank. A diaphragm plating method characterized in that the liquid level in the diaphragm tank is maintained at a higher level than the liquid level between the diaphragm tank and the plating tank.