JPH0559599A - Device for regenerating rhodium sulfate plating liquid - Google Patents

Abstract

PURPOSE:To eliminate the need for a waste liquid disposition in the state of a high rhodium metal ion concn. and to regenerate a rhodium sulfate plating liquid which does not elute org. matter, etc., to induce contact faults and allows a plating treatment with high quality. CONSTITUTION:The rhodium sulfate liquid 5 and pure water 14 are respectively admitted into 1st and 2nd rooms 3, 4 in a vessel 1 separated by a diffusion dialysis membrane 2 and are disposed to face each other via the diffusion dialysis membrane 2 so that only the sulfuric acid component in an original liquid 5 is migrated from the 1st room 3 to the 2nd room 4 by a dialysis reaction and the rhodium metal ions of the original liquid is not migrated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rhodium sulfate plating solution regenerator, and more particularly to a rhodium sulfate plating solution regenerator suitable for forming a rhodium contact by an electrolytic plating method in a reed switch.

[0002]

TECHNICAL BACKGROUND A wet electrolytic plating method is generally adopted as a plating method necessary for forming a contact of a reed switch. Further, since the purpose of use of the contact of the reed switch, that is, the characteristic as an opening / closing contact is required, a rhodium plating solution is mainly used as the contact plating solution. This rhodium plating solution is composed of rhodium sulfate, which is a base based on sulfuric acid, and an organic substance.

[0003]

2. Description of the Related Art As a conventional method for regenerating a rhodium plating solution for depositing rhodium metal, a stock solution of rhodium sulfate is discarded, for example, about 1/3, and the remaining solution is diluted with pure water or the like, and then a rhodium sulfate replenishing solution. The method of regenerating the rhodium sulfate plating solution by injecting is generally used.

[0004]

However, in the above-mentioned conventional regenerating method, each time the regenerating treatment of the rhodium plating liquid is performed, a fixed amount of the stock liquid, for example, about 1/3 of the total amount must be disposed of as a waste liquid. Therefore, in the waste liquid, the rhodium metal ion concentration is often high enough to withstand use, for example, about 5 g / l, so that the stock solution has a high rhodium metal ion concentration, that is, an expensive state. There was a problem that the liquid waste had to be disposed of.

Further, with the deposition of rhodium metal, the concentration of sulfuric acid present in the plating solution becomes relatively high and the concentration of sulfuric acid rises, which causes a reduction in rhodium deposition efficiency as an adverse effect on plating. In order to obtain a constant deposited film thickness, it is necessary to apply a high current and long-time treatment, and the treatment efficiency is extremely poor, and the base plating and the material such as iron-nickel alloy material are eroded by acid. There is a problem in that a metal oxide is generated, which is separated from the material and intervenes between the contacts to induce contact failure such as an increase in contact resistance value.

Further, in the case of the conventional regenerating method, it is necessary to perform a troublesome and dangerous long-time work such as pumping out the stock solution, waste solution treatment work, deionized water injection work, replenishment liquid injection work, and stopping of the plating apparatus. There was a problem. On the other hand, as a method of simply lowering the sulfuric acid concentration of the stock solution, for example, there is a barium sulfate producing method of adding barium hydroxide, which easily reacts with sulfuric acid, or a method of passing an ion exchange resin. Due to the inclusion of fine particles in the regeneration liquid and the elution of organic substances, for example, it is not possible to obtain a rhodium sulfate plating liquid sufficient to form the contact of the reed switch.

The present invention has been made to solve the above-mentioned problems, and it eliminates the need to dispose of waste liquid in a state where the rhodium metal ion concentration is high, and elutes organic substances that cause contact failure. It is an object of the present invention to provide a reclaiming device for a rhodium sulfate plating solution that enables high-quality plating processing without any problems.

[0008]

In order to achieve the above object, a rhodium sulfate plating solution regenerator according to the present invention comprises a container whose internal space is divided into a first chamber and a second chamber by a diffusion dialysis membrane, and a first chamber. First inflow means for inflowing the rhodium sulfate solution into the first chamber, first outflow means for outflowing the regenerant liquid having passed through the first chamber, and second inflow means for inflowing pure water into the second chamber And a second outflow means for outflowing the liquid that has passed through the second chamber, and the regeneration liquid is a rhodium sulfate plating liquid.

[0009]

In the rhodium sulfate plating solution regenerator according to the present invention, the diffusion dialysis membrane is separated by separating the inside of the container into the first chamber and the second chamber by the diffusion dialysis membrane having large selective permeability of ions. The rhodium sulphate solution and pure water are made to face each other. As a result, a dialysis reaction occurs due to the movement of SO ⁴ − negative ions across the diffusion dialysis membrane, and only the sulfuric acid component in the stock solution moves from the first chamber to the second room, while the rhodium metal ion of the stock solution is moved. Remains without moving. As a result, it is possible to obtain, as a rhodium sulfate plating solution, a regenerant solution in which only the sulfuric acid concentration is reduced without elution of impurities while maintaining the rhodium metal ion concentration.

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a conceptual diagram showing one embodiment of a rhodium sulfate plating solution regenerator according to the present invention. In the figure, the internal space of the sealed container 1 is divided into a first chamber 3 and a second chamber 4 by a diffusion dialysis membrane 2 having a large selective ion permeability in the center thereof.

A rhodium sulfate liquid for the purpose of regeneration, that is, the stock solution 5 is filled in a tank 6, and from this tank 6 through an inflow pipe 7, a pump 8 and a regulating valve 9.
Flows into the room 3 and flows in the room 3 in the direction of the arrow 10. The inflow speed (hereinafter, abbreviated as flow speed) of the stock solution 5 can be adjusted by the adjusting valve 9. The regenerant liquid 11 that has passed through the first chamber 3 is filled into the container 13 through the outflow pipe 12 and used as a rhodium sulfate plating liquid.

On the other hand, the pure water 14 is filled in the container 15, and flows from the container 15 into the second chamber 4 of the container 1 through the inflow pipe 16 and the pump 17 and the adjusting valve 18.
Flow in the room 4 in the direction of arrow 19. The flow rate of the pure water 14 can be adjusted by the adjusting valve 18. The liquid 20 that has passed through the second chamber 4 passes through the discharge pipe 21 and then the container 22.
And treated as waste acid.

Next, the regenerating process of the rhodium sulfate plating solution by the regenerating apparatus having such a structure will be described. Tank 6
The stock solution 5 that has flowed into the first chamber 3 of the container 1 from the above sufficiently contacts the diffusion dialysis membrane 2 when flowing in the chamber 3 in the direction of the arrow 10. As a result, the SO
The migration of ^4- negative ions causes a dialysis reaction.
At this time, only the sulfuric acid component in the undiluted solution 5 moves from the first chamber 3 to the second chamber 4, but the rhodium metal ion in the undiluted solution 5 remains without moving. As a result, it is possible to obtain the regenerant liquid 11 in which only the sulfuric acid concentration is lowered as a rhodium sulfate plating liquid without eluting impurities while maintaining the rhodium metal ion concentration.

On the other hand, from the container 15 to the second chamber 4 of the container 1
When the pure water 14 that has flowed into the chamber 4 flows in the direction of the arrow 19 in this chamber 4, the pure water 14 is introduced into the container 22 through the discharge pipe 21 while dissolving the sulfuric acid component that has moved from the first chamber 3 by dialysis. The liquid 20 containing the sulfuric acid content is treated as waste acid. The direction of inflow of pure water 14 (direction of arrow 19)
Is the opposite direction to the inflow direction of the undiluted solution 5 (the direction of arrow 10), but it does not necessarily have to be the opposite direction. However, the reverse direction is preferable because the dialysis reaction can be actively performed.

Further, the stock solution 5 and pure water 1 are adjusted by the adjusting valves 9 and 18.
4 by adjusting each flow rate of 4
Since the dialysis reaction rate can be controlled by controlling the respective flow rates of, the sulfuric acid concentration of the rhodium sulfate plating solution can be continuously maintained. Table 1 shows a list of sulfuric acid concentrations obtained by the diffusion dialysis.

[Table 1]

FIG. 2 shows a rhodium sulfate plating solution (regeneration solution) 11 obtained by the reproduction apparatus according to the present invention.
The principle of electrolytically plating the contact portion of the reed switch lead piece will be described. First, the container 23 is filled with the rhodium sulfate plating solution 11 and the metallic electrode 24 is arranged at the bottom of the container 23 to serve as an anode, while the lead piece 25, which is the object to be processed, is held by the jig 26 to serve as a cathode. To do. And both 24 and 2
For example, the voltage of 10
When electric power of about V and a current density of about 0.5 A / dm ² is supplied, rhodium metal is deposited only on the tips of the lead pieces 25 dipped in the rhodium sulfate plating solution 11.

FIG. 3 shows the structure of a reed switch 31 manufactured by using the reed pieces 25 plated in this way. In FIG. 3, at the tip of the lead piece 25,
A contact (hereinafter, referred to as a rhodium contact) 28 made of rhodium metal is formed, and a pair of lead pieces 25 having the rhodium contact 28 are sealed by a pair of glass tubes 32, for example. The hollow portion 33 of the glass tube 32 is sealed with an inert gas such as nitrogen gas, a mixed gas of nitrogen and hydrogen, or sulfur hexafluoride, or kept in a vacuum state.

FIG. 4 is a principle diagram in the case where a low load is applied to the reed switch 31 having the above-mentioned structure and an operation test is performed by driving a coil. First, the reed switch 31 is excited by the driving coil 34 to open and close the contact portion (rhodium contact) 28 of the reed switch 31. Then, the contact resistance value when the contact portion 28 forms a closed contact is measured every time. The load during the test is, for example, 5 V, 100 μA
Supply power. In addition, the driving coil 34 is 50H
It is driven at z, 20 mA.

The test results of this operation test are shown in FIG. In FIG. 5, the vertical axis represents the contact resistance value, the horizontal axis represents the number of operations, and shows the contact resistance value transition data.
As is clear from the contact resistance value transition data, according to the test result, the reed switch 31 has, for example, 5V,
It is understood that when a load of about 100 μA is applied, the contact resistance value does not change even when the number of operations reaches 100 million times. From the above results, the reed switch having the rhodium contact formed by using the rhodium sulfate plating solution obtained by the reproducing apparatus according to the present invention becomes sufficiently practical.

[0020]

As described above in detail, according to the present invention, the rhodium sulfate liquid and the pure water are respectively introduced into the first and second chambers in the container separated by the diffusion dialysis membrane for diffusion. Due to the configuration of facing each other through the dialysis membrane, only the sulfuric acid component in the stock solution moves from the first chamber to the second room by the dialysis reaction, and the rhodium metal ion in the stock solution remains without moving, so that the regeneration is performed. Even if you do not use barium sulfate generation method or ion exchange resin method that may cause contamination of fine particles or elution of organic substances in the solution, rhodium sulfate plating solution that reduces the sulfuric acid concentration while maintaining the rhodium metal concentration Moreover, since it is not necessary to dispose of the waste liquid when the rhodium metal ion concentration of the raw liquid is high, it is possible to regenerate the whole amount of the raw liquid.

Further, the increase in the sulfuric acid concentration of the rhodium sulfate plating solution reduces the corrosion of the base plating and the raw material, so that high quality plating can be performed. Furthermore, because the flow rate of the stock solution and pure water can be adjusted with the adjusting valve, it is not necessary to stop the process associated with the sulfuric acid concentration adjustment work, and rhodium sulfate plating can be performed by controlling the flow rates of the stock solution and pure water. It also means that the sulfuric acid concentration of the liquid can be maintained continuously.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an embodiment of a rhodium sulfate plating solution regenerator according to the present invention.

FIG. 2 is a principle diagram in the case where a contact portion of a reed switch lead piece is electrolytically plated by using a rhodium sulfate plating solution obtained by a reproducing apparatus according to the present invention.

FIG. 3 is a configuration diagram of a reed switch manufactured using a lead piece plated according to the principle of FIG.

FIG. 4 is a principle diagram of a case where a low load is applied to a reed switch and an operation test is performed by driving a coil.

FIG. 5 is a contact resistance value transition data diagram showing an operation test result.

[Explanation of symbols]

1 Container 2 Diffusion Dialysis Membrane 3 First Room 4 Second Room 5 Stock Solution (Rhodium Sulfate Solution) 8,17 Pump 9,18 Control Valve 11 Regeneration Solution (Rhodium Sulfate Plating Solution) 14 Pure Water 20 Waste Acid 24 Metallic Electrode 25 Reed piece 28 Rhodium contact point 31 Reed switch 34 Drive coil

Claims (2)

[Claims] 1. A container whose internal space is divided into a first chamber and a second chamber by a diffusion dialysis membrane, a first inflow means for inflowing a rhodium sulfate solution into the first chamber, and the first chamber. A first outflow means for outflowing the regenerated liquid that has passed through, a second inflow means for inflowing pure water into the second chamber, and a second outflow means for outflowing the liquid that has passed through the second chamber. A rhodium sulphate plating solution regenerator, characterized in that the regenerant is a rhodium sulphate plating solution. 2. The regenerator for rhodium sulfate plating solution according to claim 1, wherein the first and second inflowing means respectively have adjusting valves capable of adjusting inflow rates of the rhodium sulfate solution and pure water. ..