JP2001316893A - Surface treatment method and device using insoluble anode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface treatment method and device using an insoluble anode capable of operating plating work or electroforming with electrolytic dissolution of a metal, while receiving a metallic cationic ion which is apt to be insufficient during use of an insoluble anode and preventing generation of a nixious halogen gasses and improving uniformity of a plating or electroforming film. SOLUTION: In the surface treatment method in which an insoluble anode 12 is used and a surface treatment replenishing liquid is supplied from a replenishing electrolytic cell 11 to conduct plating or electroforming, the cathode chamber 17 of the replenishing electrolytic cell 11 is separated from an anode chamber 16 by a cation exchange membrane 15 through which metallic cation can pass but halogen ions can not pass and the surface treatment replenishing liquid substantially containing halogen ions are produced to prevent generation of halogen gas in the surface treatment tank 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the surface treatment of plating or electroforming using an insoluble anode. The present invention relates to a surface treatment method and apparatus for preventing generation of halogen gas in a surface treatment tank.

[0002]

2. Description of the Related Art With the recent performance and miniaturization of semiconductor devices, various electronic components supporting the semiconductor devices, particularly, plating films such as lead frames, heat sinks, ceramic circuit boards, etc., are required to have a plating film thickness and a thickness. In crystal plating and alloy plating, further uniformity of variation in alloy composition has been required. Also,
Even in electroforming used to form complex shapes,
There is a demand for highly accurate and inexpensive electroforming. Electroforming is one application of plating.In contrast to normal plating, which forms a metal thin film on a material by electrolysis or electroless, a metal thick film is formed by plating on the surface of a matrix. It is separated from plating because it is formed and peeled from the matrix to obtain a plated film product. In order to cope with these, generally, a plating metal is used for an anode, a work is connected to a cathode, and electrolysis is performed, thereby depositing a target metal on the work,
Dissolves metal cations equivalent to the amount consumed from the anode,
There was a way to replenish. However, in such an anode-consuming plating method, since the distance between the anode and the object to be plated gradually changes, when plating a work having a complicated shape, the current density distribution is not uniform and the plating film is not uniformly formed. There is a problem that the thickness becomes non-uniform, and it is not possible to reduce variations in characteristics. Therefore, in order to obtain a more uniform plating film, an insoluble anode (for example, platinum-coated titanium or the like) processed into a predetermined shape in accordance with the object to be plated is used, and plating is performed while keeping the shape constant. Will be In this case, since the plating metal ion concentration in the plating tank gradually decreases, the consumed amount is a metal salt (for example,
Compounds such as nickel sulfate and nickel sulfamate in the case of nickel plating, and compounds such as stannous sulfate in the case of tin plating). However, in the above-described plating method using an insoluble anode, when the shortage of the plating metal is replenished with a metal salt, anions become excessive. For example, in the case of nickel plating, if nickel sulfate is replenished as a metal salt, the sulfate ion of the anion becomes excessive, and as the use is repeated, the specific gravity of the plating solution increases, and defects such as pits and variations in plating thickness occur. However, there is a problem that the plating solution must be renewed. In particular, in a plating process operating at a high current density and a large current, there is a problem that the plating solution must be frequently updated. Therefore, the present inventors have already provided a replenishing electrolytic tank that dissolves a plating metal and generates only cations separately from a plating tank when an insoluble anode is used. A plating method and an apparatus using an insoluble anode for supplying cations are proposed. That is, when an insoluble anode is used, a replenishment electrolytic tank is provided separately from a surface treatment tank (plating tank) for performing plating and electroforming, and a surface treatment solution is circulated between the surface treatment tank and the replenishment electrolytic tank.

[0003]

However, in the above-mentioned conventional plating method and apparatus using an insoluble anode, halogen ions necessary for mobilizing and dissolving the metal in the replenishing electrolytic cell, that is, chlorine ions and chlorine ions are required. Bromine ions are sent to the surface treatment tank and generate halogen gas in the surface treatment tank. Halogen gas is harmful to the human body. In addition, when they occur, complete recovery is difficult, and the recovery processing device is expensive. The present invention has been made in view of such circumstances, and a surface treatment method using an insoluble anode capable of preventing generation of toxic halogen gas and improving the uniformity of plating and an electroformed film. It is intended to provide the device.

[0004]

According to the present invention, there is provided a surface treatment method using an insoluble anode according to the present invention, which comprises using an insoluble anode and removing a surface treatment replenisher containing insufficient metal cations in a surface treatment tank. In the surface treatment method of plating or electroforming by receiving a supply from a replenishing electrolytic cell, the cathode chamber of the replenishing electrolytic cell is separated from the anode chamber by a cation exchange membrane through which metal cations pass but halogen ions do not pass. A surface treatment replenisher substantially free of halogen ions is generated in the chamber to prevent generation of halogen gas in the surface treatment tank. Thereby, economical regeneration of the plating or electroforming surface treatment liquid can be obtained, the uniformity of the plating or electroforming film can be improved, and generation of harmful gas can be prevented. Here, the energizing current of the surface treatment tank and the energizing current of the replenishing electrolytic tank may be controlled to be substantially equal. As a result, the amount of hydrogen ions generated at the insoluble anode is equal to the amount of hydroxide ions generated at the replenishing electrolytic cell, and almost no pH change occurs. Further, the amount of metal cation consumed in the surface treatment and the amount of metal cation replenished can be made substantially equal.

[0005] A surface treatment apparatus using an insoluble anode according to the present invention, which meets the above object, comprises a surface treatment tank using an insoluble anode and, separately from the surface treatment tank, a plating metal or an electroformed metal which is melted to melt the metal. In a surface treatment apparatus having a replenishing electrolytic cell for generating ions and a liquid sending means for supplying and returning a liquid between the surface treating tank and the replenishing electrolytic tank, the replenishing electrolytic tank was partitioned by a cation exchange membrane. It has an anode chamber and a cathode chamber, and the anode chamber is supplied with a solution containing halogen ions, and the cathode chamber is supplied with a surface treatment liquid in a surface treatment tank. As a result, the cation exchange membrane that separates the replenishing electrolytic cell into an anode chamber and a cathode chamber allows only metal cations to pass through, so that only metal cations electrolyzed and dissolved by halogen ions in the anode chamber enter the cathode chamber. Does not pass. Therefore, it is possible to supply a surface treatment replenisher which does not cause generation of halogen gas harmful to the human body in the surface treatment tank, and no special device for recovering the halogen gas is required. Here, porous carbon may be used for the electrode of the cathode chamber of the replenishing electrolytic cell, and an air diffuser for generating air bubbles may be provided. By using porous carbon with high porosity as a cathode, air can be generated as microbubbles by a diffuser tube and suspended in the surface treatment liquid and air to cause an active oxygen reduction reaction. Thus, it is possible to prevent adhesion of plating to the porous carbon electrode.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention. Here, FIG. 1 is an explanatory view of a surface treatment apparatus using an insoluble anode according to a first embodiment of the present invention, and FIG. 2 is a surface treatment using an insoluble anode according to a second embodiment of the present invention. FIG. 3 is an explanatory view of the apparatus, and FIG. 3 is a process chart for explaining a method of manufacturing a plated film product by electroforming surface treatment.

[0007] Usually, before performing the surface treatment of electrolytic plating or electroforming, immersion is performed to remove grease or rust attached to the surface of the object to be plated or electroformed to clean the surface. There are pre-treatments such as degreasing and electrolytic degreasing, etching of workpieces, and neutralization treatment.After performing surface treatment such as electrolytic plating and electroforming, there are post-treatments such as washing and drying. Is appropriately selected according to The following embodiments were applied to the method and apparatus of the present invention in nickel plating, nickel alloy plating, nickel electroforming, and the like in this series of processing.

As shown in FIG. 1, a surface treatment apparatus A using an insoluble anode according to a first embodiment of the present invention has a surface treatment tank 10 and a replenishment electrolytic tank 11. The surface treatment tank 10 uses an insoluble anode 12 made of platinum-coated titanium (may be lead or the like) as an anode, and a workpiece 13 to be subjected to surface treatment to a cathode has a support member 1 made of a conductor.
4 is held. On the other hand, the replenishing electrolytic cell 11 is partitioned by a cation exchange membrane 15 that allows only metal cations to pass through, and an anode chamber 16 and a cathode chamber 17 are formed.
6 is provided with a nickel plate 18 as an anode. In the cathode chamber 17, a porous carbon electrode 19 having a high porosity, for example, a porosity of 90% or more, is disposed as a cathode serving as an oxygen reduction electrode. Further, in the cathode chamber 17, an air diffuser 20 for generating air as micro bubbles for oxygen supply is disposed so that the bubbles hit the porous carbon electrode 19. In the cathode chamber 17,
There are provided degassing partition plates 21 and 22 for passing a surface treatment replenisher generated by obtaining metal cations from the anode chamber 16. The surface treatment replenisher is supplied to the surface treatment tank 10 via a replenisher supply pipe 28 provided with a pump 23, a filter 24, and a heat exchanger 25 on the way, and is supplied to the surface treatment tank 10 to perform the surface treatment. A part of the liquid is treated liquid return pipe 2
9 and is returned to the replenishing electrolytic cell 11 by gravity flow. The pump 23, the filter 24, the heat exchanger 25, the replenisher supply pipe 28, and the processing liquid return pipe 29 constitute a liquid supply unit. A temperature sensor 26 is provided in the surface treatment tank 10, and the measured temperature is input to a temperature controller 27 to control the heat exchanger 25 to keep the surface treatment liquid in the surface treatment tank 10 constant. To maintain the temperature.

Next, a surface treatment method using an insoluble anode according to the first embodiment of the present invention will be described. In the anode chamber 16 of the replenishing electrolytic cell 11, nickel chloride or nickel bromide is added as an electrolytic solution, for example, to a surface treatment solution at a rate of 40 g / liter to prevent passivation of the metal and dissolve nickel by electrolysis. Let it. The cation exchange membrane 15 allows only the nickel ions, which are an example of metal cations, to pass through the cathode chamber 17 without allowing the passage of the halogen ions of nickel chloride or nickel bromide. Cathode room 1
The surface treatment liquid in which metal cations have been consumed is returned from the surface treatment tank 10 to 7. In the porous carbon electrode 19, air generated from the air diffuser 20 is used to give priority to the oxygen reduction reaction by causing air bubbles to strike the porous carbon electrode 19 so that plating deposition does not occur. The entrained bubbles are defoamed while passing through the partition plates 21 and 22, supplied with nickel ions, and supplied with a surface treatment replenisher containing no halogen ions to the surface treatment tank 10.

In the operation of the replenishing electrolytic cell 11 alone, the pH is raised by electrolysis, and nickel ions precipitate as hydroxides.
The surface treatment solution (excess solution) whose pH has been lowered by performing the surface treatment quickly flows into the cathode chamber 17 of the replenishing electrolytic cell 11 and replenishes the main part of the insufficient solution in the replenishing electrolytic cell 11. Therefore, it is necessary to minimize fluctuations in pH. As the method, the surface treatment tank 10 and the replenishment electrolytic tank 1
If the amount of current (conduction current) is equal, the insoluble anode 1
Since the amount of hydrogen ions generated in step 2 becomes equal to the amount of hydroxide ions generated in the porous carbon electrode 19 of the replenishing electrolytic cell 11, the pH can be hardly changed. Furthermore,
The amount of metal ions consumed in the surface treatment and the amount of replenished metal ions can be made equal. Thereby, the surface treatment tank 10
Insufficient nickel ions are supplied as a replenishing solution for surface treatment from the replenishing electrolytic bath 11, and the surface treatment of the work 13 can be performed in the surface treatment bath 10 while maintaining a stable salt concentration. Since the surface treatment replenisher supplied to the surface treatment tank 10 does not contain halogen ions, no halogen gas is generated in the surface treatment tank 10.

In the present invention, plating and electroforming are distinguished from each other. Electroforming is one application of plating, but ordinary plating forms a metal thin film on a material by electrolysis or electroless. On the other hand, this is classified because a thick metal film is formed on the surface of the matrix by plating and peeled from the matrix to obtain a plated film product. As shown in FIGS. 3A and 3B, a method of forming a plating film product by surface treatment by electroforming includes the following steps.
There are types. In the method shown in FIG. 3A, for example, a base made of plastic, aluminum, or the like is plated with an underlayer by electrolysis or electroless, and then thick plating is performed by electroforming, and the base is melted. Obtain a product consisting of a plating film. In the method of FIG. 3B, for example, after a base plate is plated on a matrix that is difficult to dissolve after electroforming, such as brass or the like, the surface is electrically connected by anodic treatment or dichromate treatment. Is subjected to a mold release treatment by an oxidation treatment, and electroforming is performed thereon, and then the mother mold is peeled off to obtain a product comprising a plating film. In any of the electroforming shown in FIGS. 3A and 3B,
The surface treatment method and treatment apparatus using the insoluble anode according to the present invention can be applied.

Next, a second embodiment of the present invention will be described with reference to FIG.
A surface treatment apparatus B using an insoluble anode and a surface treatment method according to the embodiment will be described. In this embodiment, the work 31 is plated with a nickel-iron alloy. The surface treatment apparatus B includes a surface treatment tank 30 for performing a plating or electroforming surface treatment using an insoluble anode 32 made of platinum-coated titanium (or lead or the like).
And a first replenishment electrolytic cell 41 and a second replenishment electrolytic cell 51
And a reserve tank 61 for collecting all surface treatment liquids and surface treatment replenishers. The substantial structure of the surface treatment tank 30 is the same as that of the surface treatment tank 10 shown in FIG. 1. The surface treatment tank 30 uses an insoluble anode 32, and a workpiece 31 to be subjected to surface treatment on the cathode is a conductor. It is held via a support member 33 made of. The surface treatment liquid in which metal cations have been consumed in the surface treatment tank 30 is supplied to the reserve tank 61 using gravity.

The first replenishing electrolytic cell 41 is partitioned by a cation exchange membrane 42 that allows only cations to pass therethrough.
And a cathode chamber 44, a nickel plate 45 is disposed as an anode in the anode chamber 43, and the electrolyte contains halogen ions. The cathode chamber 44 has a high porosity, for example, a porosity of 90, as a cathode serving as an oxygen reduction electrode.
% Or more of the porous carbon electrodes 46 are arranged,
The electrolyte solution (surface treatment replenisher) does not contain halogen ions. Further, in the cathode chamber 44, an air diffuser 47 for generating air as micro bubbles for oxygen supply is disposed so that the bubbles hit the porous carbon electrode 46. Electrolyte generated by obtaining nickel ions as an example of metal cations from the anode chamber 43 in the cathode chamber 44 is supplied to the reserve tank 61 as a surface treatment replenisher by passing through the partition plates 48 and 49 for defoaming. I do.

The second replenishing electrolyzer 51 has the same flow as the first replenishment electrolyzer 41, and is partitioned by a cation exchange membrane 52 that allows only cations to pass without allowing halogen ions to pass therethrough. And a cathode chamber 54 are formed, and an iron plate 55 is disposed in the anode chamber 53 as an anode. In the cathode chamber 54, a porous carbon electrode 56 is arranged. Further, in the cathode chamber 54, an air diffuser 57 is disposed so that air bubbles hit the porous carbon electrode 56. In the cathode chamber 54, an electrolytic solution (a surface treatment replenisher) generated by obtaining iron ions, which are examples of metal cations, from the anode chamber 53
Is supplied to the reserve tank 61 through the defoaming partition plates 58 and 59.

A surface treatment liquid from the surface treatment tank 30, a surface treatment replenisher with nickel ions replenished from the first replenishing electrolytic tank 41, and a surface treatment replenisher with iron ions replenished from the second auxiliary electrolytic tank 51. It is accumulated in the reserve tank 61.
The liquid mixed in the reserve tank 61 is supplied to a pump 62,
It is supplied to the surface treatment tank 30 via the filter 63, and is returned to the cathode chamber 44 of the first replenishing electrolytic tank 41 via the pump 64.
Is returned to the cathode chamber 54 of the replenishing electrolytic cell 51 of the above.
In the reserve tank 61, the surface treatment liquid is maintained at a constant temperature by a temperature controller 68 having a temperature sensor 66 and a heater 67.

The surface treatment method of the workpiece 31 by the surface treatment apparatus B is substantially the same as the surface treatment method of the first embodiment. The difference is that the surface treatment solution from the surface treatment tank 30, the electrolyte solution with nickel ions replenished from the first replenishment electrolysis tank 41, and the electrolyte solution with iron ions replenished from the second replenishment electrolysis tank 51 are stored in the reserve tank 61. This is the point that nickel ions and iron ions are supplied to the surface treatment liquid in which nickel ions and iron ions have been consumed in the surface treatment tank 30 and are supplied to the surface treatment tank 30 again. on the other hand,
In order to replenish nickel and iron ions to the surface treatment liquid in which nickel ions and iron ions have been consumed in the surface treatment tank 30, the nickel ions and iron ions are returned to the first replenishment electrolytic tank 41 and the second replenishment electrolytic tank 51, respectively. Nickel ions and iron ions are supplied to the electrolytic solution in substantially the same manner as in the first embodiment. The flow of the current in the surface treatment tank 30, the first replenishment electrolyzer 41, and the second replenishment electrolyzer 51 depends on the total current of the rectifier of the first replenishment electrolyzer 41 and the rectifier of the second replenishment electrolyzer 51. Is set to be equal to the current of the rectifier of the surface treatment tank 30, and the rectifier of the first replenishment electrolytic tank 41 and the second
The current ratio of the rectifier of the replenishment electrolytic cell 51
In order to achieve the electrochemical equivalent ratio of the alloy plating composition in the above, the operation is performed by distributing the composition so that the surface treatment is performed. The anode chambers 43 and 53 of the first and second replenishment electrolysis tanks 41 and 51 may be added with chlorides or the like as aqueous solutions of the respective metal salts so as to dissolve the anode smoothly. Good. In the above embodiment, the method and apparatus for plating surface treatment have been described. However, the present invention is naturally applied to the surface treatment for electroforming.

[0017]

According to the surface treatment method using an insoluble anode according to the first and second aspects of the present invention, the cathode compartment of the replenishing electrolytic cell is separated from the anode compartment by a cation exchange membrane through which metal cations pass but not halogen ions. In addition, a surface treatment replenisher substantially free of halogen ions is generated in the cathode chamber to prevent the generation of halogen gas in the surface treatment tank, so that the surface treatment solution for plating and electroforming can be economically regenerated. Thus, the uniformity of the plating and the electroformed film can be enhanced, and generation of harmful gas can be prevented. In particular, in the surface treatment method using the insoluble anode according to the present invention, the current supplied to the surface treatment tank and the current supplied to the replenishment electrolytic cell are controlled to be substantially equal, so that hydrogen ions generated at the insoluble anode are supplied. The amount becomes equal to the amount of hydroxide ion generated in the electrolytic cell, and almost no pH change occurs. Further, the amount of metal cation consumed in the surface treatment and the amount of metal cation replenished can be made substantially equal. A surface treatment apparatus using an insoluble anode according to claim 3 or 4, wherein the replenishing electrolytic tank has an anode chamber and a cathode chamber partitioned by a cation exchange membrane, and the anode chamber contains a solution containing a halogen ion, Since the chamber is supplied with the surface treatment liquid from the surface treatment tank, only the cations pass through the cation exchange membrane that separates the replenishment electrolytic tank, and only the metal cations electrolytically dissolved by the halogen ions in the anode chamber become the cathode. Enters the chamber and does not pass halogen ions. Therefore, metal cations that do not generate halogen gas can be supplied to the surface treatment tank. In particular, in the surface treatment apparatus using the insoluble anode according to the fourth aspect, since a porous carbon is used for the electrode of the cathode chamber of the replenishing electrolytic cell and a diffuser for generating air bubbles is provided, the porosity is large. Microporous air is blown out of the air using porous carbon to create a suspended state of the surface treatment liquid and the air, and a vigorous oxygen reduction reaction can be caused without plating deposition.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a surface treatment apparatus using an insoluble anode according to a first embodiment of the present invention.

FIG. 2 is an explanatory view of a surface treatment apparatus using an insoluble anode according to a second embodiment of the present invention.

FIG. 3 is a process chart for explaining a method for producing a plated film product by electroforming surface treatment.

[Explanation of symbols]

A: Surface treatment device, B: Surface treatment device, 10: Surface treatment tank, 11: Supplementary electrolytic cell, 12: Insoluble anode, 13: Work, 14: Support member, 15: Cation exchange membrane, 16: Anode chamber, 17: cathode chamber, 18: nickel plate, 19: porous carbon electrode, 20: diffuser tube, 21: partition plate, 2
2: partition plate, 23: pump, 24: filter, 2
5: heat exchanger, 26: temperature sensor, 27: temperature controller, 28: replenisher supply pipe, 29: treatment liquid return pipe, 30:
Surface treatment tank, 31: Work, 32: Insoluble anode, 33:
Supporting member, 41: first replenishing electrolytic cell, 42: cation exchange membrane, 43: anode chamber, 44: cathode chamber, 45: nickel plate, 46: porous carbon electrode, 47: air diffuser, 4
8: partition plate, 49: partition plate, 51: second replenishing electrolytic cell, 52: cation exchange membrane, 53: anode compartment, 54: cathode compartment, 55: iron plate, 56: porous carbon electrode, 57:
Air diffuser, 58: partition plate, 59: partition plate, 61: reserve tank, 62: pump, 63: filter, 64:
Pump, 65: pump, 66: temperature sensor, 67: heater, 68: temperature controller

Claims (4)

[Claims] 1. A surface treatment method in which an insoluble anode is used and plating or electroforming is performed by receiving a supply of a surface treatment replenisher containing insufficient metal cations in the surface treatment tank from a supply electrolytic tank. Separating from the anode compartment by a cation exchange membrane through which metal cations pass but not halogen ions through the cathode compartment of the cell, a surface treatment replenisher substantially free of halogen ions is produced in the cathode compartment, A surface treatment method using an insoluble anode, wherein generation of a halogen gas in a treatment tank is prevented. 2. The method for treating a surface using an insoluble anode according to claim 1, wherein a current supplied to said surface treatment tank and a current supplied to said replenishment electrolytic cell are controlled to be substantially equal. Using surface treatment method. 3. A surface treatment tank using an insoluble anode, a replenishment electrolytic tank that separates a plating metal or an electroformed metal to generate metal cations separately from the surface treatment tank, In a surface treatment apparatus having a liquid feeding means for supplying and returning a liquid between the replenishing electrolytic cell and the replenishing electrolytic cell, the replenishing electrolytic cell has an anode chamber and a cathode chamber partitioned by a cation exchange membrane, and the anode chamber A surface treatment apparatus using an insoluble anode, wherein a solution containing halogen ions is supplied to the cathode chamber, and a surface treatment liquid of the surface treatment tank is supplied to the cathode chamber. 4. A surface treatment apparatus using an insoluble anode according to claim 3, wherein a porous carbon is used for an electrode of a cathode chamber of the replenishing electrolytic cell, and an air diffuser for generating air bubbles is provided. A surface treatment device using an insoluble anode.