JP2003147539A - Surface treatment method by liquid phase - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of the deficiency of a film even to a fine pore or a fine structure in the material to be treated, and to form a uniform film. SOLUTION: For the purpose of forming a film 3 on the inside face 2a of a fine pore or a fine structure in the material 2 to be treated, the pressure in a sealed chamber is made into an evacuated state of <=1 Pa to a state of atmospheric pressure by a decompression pump. By making the evacuated state, the volume of bubbles stuck to the inside face 2a of the fine pore or fine structure in the material 2 to be treated increases, and the buoyancy thereof increases, so that the bubbles are separated from the inside face 2a of the fine pore or fine structure. Then, a treatment solution infiltrates into the fine pore or fine structure by the separation of the bubbles, and the treatment solution comes into contact with the inside face 2a of the fine pore of fine structure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid-phase surface treatment method for subjecting a material to be treated to a surface treatment such as a film by immersing the material to be treated in a treatment liquid.

[0002]

2. Description of the Related Art Liquid surface treatment methods include, for example,
A plating method for electrochemically forming a metal film or the like on the surface of a material to be processed such as metal parts, a passivation treatment for forming a passivation film on the surface of the material to be processed, and a chemical conversion to the material to be processed There is a chemical conversion treatment for forming a film or a chemical polishing treatment for polishing a material to be treated in a liquid phase state.

For example, the plating method is, for example, the corrosion resistance of parts to be plated such as ceramics, glass and resins, and the plated materials such as metal products,
This is a method of forming a metal plating film on the surface of a material to be plated in order to improve heat resistance, electromagnetic characteristics, decorativeness, and the like. The plating method includes an electrolytic plating method and an electroless plating method.

In the electroless plating method, a metal produced by a redox reaction occurring in an electroless plating solution is deposited on the surface of a material to be plated. The electroless plating solution is a solution containing a metal salt to be deposited on the surface of the material to be plated and a reducing agent to oxidize the metal salt. In the electroless plating method,
Depending on the type of metal salt contained in the electroless plating solution, a plating treatment for forming a metal plating film of nickel, copper, gold, silver or the like on the surface of the material to be plated can be performed. The electroless plating method is carried out by a relatively simple apparatus because the metal plating film is formed on the surface of the material to be plated by the redox reaction occurring in the plating solution.

In the electroless plating method, since the metal plating film is formed on the surface of the material to be plated where the material to be plated and the plating solution are in contact with each other, the plating solution is well spread over the surface of the material to be plated. It is possible to prevent the occurrence of plating chipping. As a method for distributing the plating solution, for example, there is a method in which a plating tank is equipped with a stirring mechanism including a stirring blade or the like and an ultrasonic mechanism for emitting ultrasonic waves to stir the plating solution. The electroless plating method is characterized in that it is possible to form a metal plating film on the surface of various materials such as resin, ceramics, and glass, in addition to metal.

[0006]

However, in the above-mentioned electroless plating method, in the case where the material to be plated has minute holes, that is, through holes or bottomed holes having a diameter of several microns, or a complicated fine structure on the surface. When the material to be plated is immersed in the plating solution, gas such as air in the micropores or the fine structure may be trapped by the plating solution. Then, in the electroless plating method, even if the plating solution is agitated by the agitation mechanism as described above, the surface that acts at the boundary between the plating solution and the bubbles trapped in the micropores or microstructure of the material to be plated It has been difficult to remove air bubbles from within micropores or microstructures by energy. Therefore, in this electroless plating method, it is difficult to bring the plating solution into contact with the inner surface of the micropores or microstructure of the material to be plated due to the air bubbles trapped in the micropores or microstructure. Plating chipping may occur on the inner surface. Incidentally, not only the above-mentioned electroless plating method, but also the surface treatment method using other liquid phase may similarly cause the film chipping.

In view of the above, the present invention prevents the occurrence of film chipping on the inner surface of the minute pores or the complicated fine structure formed on the material to be processed, and applies the film of uniform thickness to the material to be processed. It is an object of the present invention to provide a surface treatment method by a liquid phase that enables the above.

[0008]

A liquid phase surface treatment method according to the present invention which achieves the above-mentioned object is a treatment tank filled with a treatment liquid, and a hermetically sealed chamber in which the treatment tank is housed. A liquid phase surface treatment apparatus provided with a decompression means for decompressing the inside of the closed chamber is used, and a material to be treated having fine pores and / or a complicated fine structure of the surface is supplied to a treatment tank to be treated. The method is characterized in that it includes a step of immersing and a step of bringing the inside of the closed chamber into a reduced pressure state by a pressure reducing means, and the inside of the closed chamber is brought into a reduced pressure state and the material to be treated is subjected to a surface treatment.

According to this surface treatment method using the liquid phase, the inside of the closed chamber in which the treatment tank is housed is depressurized by the depressurization mechanism so that the inside of the micropores or microstructure of the material to be treated immersed in the treatment liquid is reduced. Since the volume of the bubbles trapped in the chamber increases, the buoyancy of the bubbles increases and the bubbles are removed from the inner surfaces of the micropores and microstructure, and the treatment liquid contacts the entire inner surface of the micropores and microstructure of the material to be treated. So that the processing liquid can be spread. Therefore, according to the surface treatment method using a liquid phase, it is possible to prevent the occurrence of film cracks on the inner surfaces of the micropores and the fine structure of the material to be processed, and to form a film having a uniform film thickness.

Further, the liquid-phase surface treatment method according to the present invention has at least a cleaning step for cleaning the material to be treated as a pre-step of supplying the material to be treated to the treatment tank. The process has a step of immersing the material to be treated in the cleaning liquid filled in the cleaning tank housed in, and a step of bringing the closed chamber into a decompressed state by a decompression means, and the decompressed state of the closed chamber is used to remove the material to be treated. It is characterized by washing.

According to this liquid-phase surface treatment method, even in the cleaning step of the preceding step in which the material to be treated is supplied to the treatment tank, the pressure-reducing mechanism is used to reduce the pressure inside the closed chamber in which the cleaning tank is housed. Since the volume of the air bubbles trapped in the micropores and / or the microstructure of the material to be treated immersed in the cleaning liquid increases, the buoyancy of the air bubbles increases and the air bubbles are removed from the inner surfaces of the micropores and the microstructure. The cleaning liquid can be spread so that the cleaning liquid comes into contact with the entire inner surface of the micropores or the fine structure of the treatment material. Therefore, according to the surface treatment method using the liquid phase, it is possible to clean the entire inner surfaces of the micropores and the microstructure of the material to be treated, and remove unnecessary substances adhering to the micropores and the inner surface of the microstructure. Therefore, the bond between the inner surface of the micropore or the fine structure and the film formed on the inner surface is strengthened.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings. The liquid-phase surface treatment method shown as the embodiment is a method of forming a nickel plating film 3 on a material to be plated 2 which is a material to be processed by an electroless nickel plating method as shown in FIG. . The material to be plated 2 is made of metal, resin, ceramic, glass or the like having minute holes, so-called through holes in the unit of several microns, bottomed holes, undercut portions or fine structures having complicated surfaces.

The electroless plating apparatus 1 comprises a plating mechanism 4 and a drying mechanism 5. The plating mechanism 4 includes a closed chamber 6, a decompression pump 7, and an opening / closing valve 8. Inside the closed chamber 6, a plurality of tanks are provided for performing the plating process on the material 2 to be plated. Specifically, the closed chamber 6 includes a degreasing tank 9, a first pure water cleaning tank 10, an acid cleaning tank 11, a neutralization tank 12, and a plating tank 1.
3 and a second pure water cleaning tank 14 are provided. The closed chamber 6 may be provided for each process to perform each process.

The degreasing tank 9 is filled with a degreasing liquid 15 capable of removing oil adhering to the surface of the material to be plated 2. The degreasing tank 9 dips the material to be plated 2 in the degreasing liquid 15 to remove the oil component attached to the surface of the material to be plated 2.

In the first pure water cleaning tank 10, the material to be plated 2
Pure water 16 for cleaning the degreasing liquid 15 remaining on the surface of the is filled. In the first pure water cleaning tank 10, the material to be plated 2
Is immersed in pure water 16 to remove the degreasing liquid 15 attached to the surface of the material to be plated 2.

The acid cleaning tank 11 is filled with an acidic solution 17 which enables removal of dirt adsorbed by a chemical reaction such as an oxide film adhering to the surface of the material 2 to be plated. In the acid cleaning tank 11, the material to be plated 2 is immersed in the acidic solution 17 to remove the oxide film and the like adhering to the surface of the material to be plated 2.

The neutralization tank 12 has an alkaline solution 18 for neutralizing the acidic solution 17 remaining on the surface of the material 2 to be plated.
Is filled. In the neutralization tank 12, the material to be plated 2 is immersed in the alkaline solution 18 to neutralize the acidic solution 17 attached to the surface of the material to be plated 2.

The plating bath 13 is filled with an electroless nickel plating solution 19 capable of depositing nickel to form the nickel plating film 3 on the surface of the material 2 to be plated. As the electroless nickel plating solution 19, a mixed solution containing a metal salt such as nickel chloride and a reducing agent such as sodium hypophosphite is used. The plating tank 13 immerses the material to be plated 2 in the electroless nickel plating solution 19 to form the nickel plating film 3 on the surface of the material to be plated 2.

The material to be plated 2 is placed in the second pure water cleaning tank 14.
In order to clean the electroless nickel plating solution 19 remaining on the surface of the pure water 16, pure water 16 similar to the pure water 16 filled in the first pure water cleaning tank 10 is filled. The second pure water cleaning tank 14 removes the electroless nickel plating solution 19 remaining on the surface of the material 2 to be plated by immersing the material 2 to be plated having the nickel plating film 3 formed thereon in pure water 16. To do.

In order to keep the concentration of the solution filled in each of the above-mentioned tanks uniform and to bring the solution and pure water 16 into sufficient contact with the surface of the material 2 to be plated, the solution and pure water 16 are filled. A stirring mechanism 20 having a stirring blade 20a for stirring and an ultrasonic mechanism 21 for stirring by vibration by ultrasonic waves are provided. Further, in the plating tank 13, the electroless nickel plating solution 19 filled in the plating tank 13 is provided.
Mechanism 2 for keeping the liquid temperature of the liquid in the range of 90 to 100 ° C
2 is provided.

The closed chamber 6 is brought into a depressurized state by driving the decompression pump 7 and adjusting the on-off valve to exhaust the gas inside.

The on-off valve 8 is connected between the decompression pump 7 and the closed chamber 6 by connecting pipes 23a and 23b. The open / close valve 8 opens the closed chamber 6 so that the closed chamber 6 and the operating decompression pump 7 communicate with each other through the connecting pipes 23a and 23b, thereby reducing the pressure in the closed chamber 6. The on-off valve 8 is operated to close the closed chamber 6 and the decompression pump 7 when the closed chamber 6 reaches a predetermined depressurized state, so that the pressure in the closed chamber 6 is kept at a constant depressurized state. Hold on. The opening / closing valve 8 opens the closed chamber 6 so that the outside is communicated with the outside via the connection pipe 23a, thereby setting the pressure in the closed chamber 6 to a normal pressure state.

The drying mechanism 5 is provided outside the closed chamber 6 and, for example, by using a clean air blow or a heating / drying furnace, the material to be plated 2 that has been plated.
The water remaining on the surface of is removed.

In the electroless plating apparatus 1 having the above structure,
As shown in FIG. 2, when the material to be plated 2 is plated, the pressure in the closed chamber 6 is reduced to
The bubbles 24 trapped in the fine holes and the fine structure of the plated material 2 are removed.

Specifically, the electroless plating apparatus 1 is shown in FIG.
As shown in (A), when the material to be plated 2 is immersed in the electroless nickel plating solution 19 in the closed chamber 6 before depressurization, the bubbles 24 are trapped in the fine holes and the fine structure of the material to be plated 2. Will end up. Next, in the electroless plating apparatus 1, as shown in FIG. 2 (B), by decompressing the inside of the closed chamber 6, bubbles 24 trapped in the micro holes of the material to be plated 2 or the inner surface 2a of the microstructure are formed. The volume increases. Next, in the electroless plating apparatus 1, as shown in FIG. 2C, the buoyancy is increased by increasing the volume of the bubbles 24 trapped in the micropores or the fine structure of the material to be plated 2 and the plated material is plated. Bubbles are released from the micropores of the material 2 or the inner surface 2a of the microstructure. Next, in the electroless plating apparatus 1, as shown in FIG.
As shown in (D), the bubbles 24 are removed from the fine holes and the fine structure of the plated material 2. Therefore, in the electroless plating apparatus 1, it is possible to spread the electroless nickel plating solution 19 so that the electroless nickel plating solution 19 is brought into contact with the micropores of the plated material 2 or the entire inner surface 2a of the microstructure in the plating tank 13. it can.

Similarly, in the electroless plating apparatus 1, the pressure in the closed chamber 6 is also reduced when degreasing and cleaning the plated material 2 before the plated material 2 is plated. In the electroless plating apparatus 1, for example, the material to be plated 2
When degreasing the surface of the degreasing tank 9 in the degreasing tank 9, as shown in FIG.
The degreasing liquid 15 traps the gas in the micropores and the microstructure of the plated material 2 dipped in the metal 5. next,
In the electroless plating apparatus 1, as shown in FIG. 3 (B), the material to be plated 2 is reduced by depressurizing the closed chamber 6.
The volume of the bubbles 24 confined in the micropores and the microstructure of is increased. Then, in the electroless plating apparatus 1, as shown in FIG.
As shown in (C), the buoyancy is increased by increasing the volume of the air bubbles 24 trapped in the micropores or the microstructure of the material to be plated 2, and the micropores of the material to be plated 2 or the inner surface 2a of the microstructure are increased. The oil / fat 25 is also removed when the oil / fat 25 is removed. Next, in the electroless plating apparatus 1, as shown in FIG. 3D, the bubbles 24 are separated from the fine holes or the fine structure of the plated material 2. As a result, in the electroless plating apparatus 1, it is possible to properly clean the entire inner surface 2a of the micropores or the microstructure of the material to be plated 2 in the degreasing tank 9, and adhere to the inner surface 2a of the micropore or microstructure. The oil / fat 25 that is being removed is also removed.

Next, an electroless nickel plating method using the above electroless plating apparatus 1 will be described. As shown in FIG. 4, the electroless nickel plating method using the electroless plating apparatus 1 described above includes a degreasing step S1, a second pure water washing step S2, an acid washing step S3, and a neutralization step S4. ,
It has a plating step S5, a second pure water washing step S6, and a drying step S7.

First, the material to be plated 2 is subjected to a degreasing step S1. In the degreasing step S1, when the material to be plated 2 is degreased, the material to be plated 2 is immersed in the degreasing liquid 15 filled in the degreasing tank 9. As the degreasing liquid 15, an organic solvent such as acetone or methanol, or a degreasing liquid such as a detergent is used. next,
In the degreasing step S1, the degreasing liquid 15 in which the material to be plated 2 is immersed has a frequency of 20 KHz to 5 by the ultrasonic mechanism 21.
While the ultrasonic wave of 0 KHz and the stirring speed of the stirring mechanism 20 are added 5 times / minute, the closed chamber 6 and the decompression pump 7 are added.
The opening / closing valve 8 is opened so that the and are communicated with each other via the connecting pipes 23a and 23b, and the pressure in the closed chamber 6 is reduced to 1 Pa or less with respect to the atmospheric pressure. At this time, in the degreasing step S1, the inside of the closed chamber 6 is depressurized to remove the air bubbles 24 trapped in the micropores of the material to be plated 2 and the microstructure.

Next, in the degreasing step S1, the opening / closing valve 8 is opened so that the closed chamber 6 communicates with the outside via the connecting pipe 23a, and the pressure in the closed chamber 6 is returned to the normal pressure state. Next, the material to be plated 2 is taken out from the degreasing liquid 15. Thus, in the degreasing step S1, the oil / fat 25 adhering to the material 2 to be plated is removed.

Next, the material to be plated 2 is subjected to a first pure water cleaning step S2. In the first pure water cleaning step S2, when the material 2 to be plated is cleaned with pure water, the material 2 to be plated is immersed in the pure water 16 filled in the first pure water cleaning tank 10.
Next, in the first pure water cleaning step S2, the frequency 20 by the ultrasonic mechanism 21 is applied to the pure water 16 in which the material to be plated 2 is immersed.
Rotation speed 6 by ultrasonic waves of up to 50 KHz and stirring mechanism 20
The opening / closing valve 8 is opened so that the closed chamber 6 and the decompression pump 7 communicate with each other through the connecting pipes 23a and 23b while stirring at 0 times / minute, and the pressure in the closed chamber 6 is brought to atmospheric pressure. On the other hand, the pressure is reduced to 1 Pa or less. At this time, in the first pure water cleaning step S2, the pre-degreasing step S1 for removing the air bubbles 24 trapped in the fine holes and the fine structure of the plated material 2 and attaching the inner surface 2a of the fine holes and the fine structure. The degreasing liquid 15 used in step 1 is extruded.

Next, in the first deionized water cleaning step S2, the on-off valve 8 is opened so that the closed chamber 6 and the outside are communicated with each other through the connecting pipe 23a, and the pressure in the closed chamber 6 is kept constant. Return to pressure. Next, the plated material 2 is pure water 1
Taken out from 6. In this way, in the second pure water cleaning step S2, the degreasing liquid 15 adhering to the material 2 to be plated is removed.

Next, the material to be plated 2 is subjected to an acid cleaning step S3.
Give. In the acid cleaning step S3, when the material to be plated 2 is subjected to acid cleaning, the acidic solution 17 filled in the acid cleaning tank 11 is used.
The material to be plated 2 is dipped in. As the acidic solution 17, a mixed solution of 10% hydrochloric acid and 10% sulfuric acid is used. Next, in the acid cleaning step S3, while applying ultrasonic waves having a frequency of 20 to 40 KHz by the ultrasonic mechanism 21 and stirring 60 times / minute by the stirring mechanism 20 to the acidic solution 17 in which the material to be plated 2 is immersed, Connection pipe 2 for connecting closed chamber 6 and decompression pump 7
The on-off valve 8 is opened so that the closed chamber 6 is communicated with the closed chamber 6 by 3 so that the pressure in the closed chamber 6 is reduced to 1 Pa or less with respect to the atmospheric pressure. At this time, in the acid cleaning step S3, the bubbles 2 trapped in the micropores and the microstructure of the material 2 to be plated.
4 is removed, and the pure water 16 used in the previous first pure water cleaning step S2 is pushed out.

Next, in the acid cleaning step S3, the on-off valve 8 is opened so that the closed chamber 6 communicates with the outside air via the connecting pipe 23a, and the inside of the closed chamber 6 is returned to the normal pressure state. Next, the plated material 2 is taken out of the acidic solution 17. Thus, in the acid cleaning step S3, the oxide film attached to the material 2 to be plated is removed.

Next, the material to be plated 2 is subjected to a neutralization step S4. In the neutralization step S4, when the material to be plated 2 is neutralized, the material to be plated 2 is immersed in the alkaline solution 18 filled in the neutralization tank 12. As the alkaline solution 18, a 5 to 10% alkaline solution 18 is used. Next, the neutralization step S
In No. 4, at normal temperature, ultrasonic waves with a frequency of 20 to 100 KHz by the ultrasonic mechanism 21 and rotation speed 6 by the stirring mechanism 20
The opening / closing valve 8 is opened so that the closed chamber 6 and the decompression pump 7 are communicated with each other through the connecting pipe 23 while stirring at 0 times / minute, and the pressure in the closed chamber 6 is set to the atmospheric pressure. The pressure is reduced to 1 Pa or less. At this time, in the neutralization step S4, the microscopic holes of the material to be plated 2 and the bubbles 24 trapped in the fine structure are removed, and the acidic solution 17 used in the pre-acid cleaning step S3 is extruded.

Next, in the neutralization step S4, the on-off valve 8 is opened so that the closed chamber 6 communicates with the outside via the connecting pipe 23a, and the pressure in the closed chamber 6 is returned to the normal pressure state. . Next, the plated material 2 is an alkaline solution 18
Taken from. Thus, in the neutralization step S4, the acidic solution 17 adhering to the plated material 2 is neutralized.

Next, the material to be plated 2 is subjected to a plating treatment step S5. In the plating treatment step S5, the material to be plated 2 is immersed in the electroless nickel plating solution 19 when the material to be plated 2 is plated. Electroless nickel plating solution 1
For 9, a general electroless nickel plating solution 19 such as a mixed solution in which an aqueous solution containing a nickel salt such as nickel chloride and a reducing agent such as sodium hypophosphite are mixed is used. Next, in the plating treatment step S5, while the electroless nickel plating solution 19 is kept at 90 to 100 ° C. by the heating mechanism 22, stirring is performed by the stirring mechanism 20 at a rotation speed of 30 times / minute. Next, in the plating process S5, the closed chamber 6
The on-off valve 8 is opened so that the pressure reducing pump 7 and the pressure reducing pump 7 communicate with each other via the connecting pipes 23a and 23b, and the closed chamber 6
The internal pressure is reduced to 1 Pa or less with respect to the atmospheric pressure. At this time, in the plating process S5, the material to be plated 2
24 attached to the inner surface 2a of the micropores or microstructure of the
Is removed and the alkaline solution 18 used in the pre-neutralization step S4 is extruded.

Next, in the plating step S5, the on-off valve 8 is opened so that the closed chamber 6 communicates with the outside through the connecting pipe 23a, and the inside of the closed chamber 6 is returned to the normal pressure state. Next, the material to be plated 2 is taken out from the electroless nickel plating solution 19.

As described above, in the plating step S5, as shown in FIG. 5, it is possible to prevent the occurrence of plating chipping on the micropores of the material to be plated 2 and the inner surface 2a of the fine structure, and to obtain a uniform film thickness. The nickel plating film 3 is formed.

Next, the material to be plated 2 is subjected to a second pure water cleaning step S6. In the second pure water cleaning step S6, the pure water 16 is applied to the material 2 to be plated when the material 2 to be plated is cleaned.
Soak. Next, in the second pure water cleaning step S6, a frequency of 20 to 100 KH is generated by the ultrasonic mechanism 21 at room temperature.
The open / close valve 8 is provided so that the closed chamber 6 and the decompression pump 7 communicate with each other through the connecting pipes 23a and 23b while adding ultrasonic waves of z and stirring by the stirring mechanism 20 at a rotation speed of 60 times / min.
Is opened to bring the pressure in the closed chamber 6 into a reduced pressure state of 1 Pa or less with respect to the atmospheric pressure. At this time, in the second pure water cleaning step S6, the air bubbles 24 trapped in the micropores and the fine structure of the plated material 2 are removed, and the electroless nickel plating solution used in the pre-plating step S5 is removed. 19 is extruded.

Next, in the second pure water cleaning step S6, the on-off valve 8 is opened so that the closed chamber 6 communicates with the outside air via the connecting pipe 23a, and the pressure in the closed chamber 6 is kept constant. Return to pressure. Next, the plated material 2 is pure water 1
Taken out from 6. In this way, in the second pure water cleaning step S6, the material 2 to be plated having the nickel plating film 3 can be cleaned with pure water.

Next, the material to be plated 2 is subjected to a drying step S7. When performing the drying step S7 on the material to be plated 2, dry air is blown onto the material to be plated 2 by the clean air blow provided in the drying mechanism 5. In the drying step S7, the water adhering to the material to be plated 2 is removed at room temperature and atmospheric pressure. Next, the plated material 2 is taken out from the drying mechanism 5. As described above, in the electroless plating apparatus 1, it is possible to prevent the occurrence of plating defects on the micropores of the material to be plated 2 and the inner surface 2a of the fine structure, and to form the nickel plating film 3 having a uniform film thickness. can do.

In the above-mentioned electroless nickel plating method, the inside of the closed chamber 6 is depressurized by the depressurizing pump 7 to perform the plating step S5, so that the material to be plated 2 immersed in the electroless nickel plating solution 19 is processed. The bubbles 24 are removed from the inner surface 2a of the micropores or the microstructure, and the electroless nickel plating solution 19 can be spread into the micropores or the microstructure of the plated material 2. Therefore, according to the electroless nickel plating method, it is possible to prevent the occurrence of plating chipping on the micropores of the material to be plated or the inner surface 2a of the fine structure, and to form the nickel plating film 3 having a uniform film thickness.

In the electroless nickel plating method, the degreasing step S1 to the neutralization step S are performed before the plating treatment step S5.
4 is performed by reducing the pressure in the closed chamber 6 by the decompression pump 7, bubbles are removed from the micropores of the material to be plated 2 or the inner surface 2a of the microstructure, and the micropores of the material to be plated 2 or the inner surface of the microstructure. The cleaning liquid or pure water can be spread over the entire surface of 2a. As a result, the electroless nickel plating method uses the inner surface 2a of the micropores or the fine structure of the plated material 2
Wash the entire surface.

Therefore, according to the electroless nickel plating method, it is possible to clean the entire inner surface 2a of the micropores or the fine structure of the material 2 to be plated and adhere to the inner surface 2a of the micropore or the fine structure. Since the unnecessary substances are removed, the bond between the inner surface 2a of the micropores or the fine structure and the nickel plating film formed on the inner surface 2a is strengthened.

In the above-described embodiment, the electroless nickel plating solution 19 is used to perform the plating treatment on the material to be plated 2, but the present invention is not limited to this.
An electroless copper plating solution, an electroless gold plating solution, an electroless silver plating solution, an electroless cobalt plating solution or the like may be used.

In the electroless nickel plating method, each step is applied to the material to be plated 2 by utilizing an automatic transport mechanism for connecting the respective tanks and moving the material to be plated 2.
It is possible to perform each step while maintaining the reduced pressure state of 1 Pa or less with respect to the atmospheric pressure without performing the operation of returning the pressure reduced state to the normal pressure state in each step. As a result, the electroless nickel plating method simplifies the manufacturing process and reduces the manufacturing cost.

[0047]

As described above in detail, according to the present invention, when a film is formed on a material to be treated, the pressure in the closed chamber in which the treatment tank is housed is reduced by the pressure reducing means. As a result, it is possible to remove the air bubbles trapped in the fine pores and the fine structure of the material to be processed. Therefore, according to the present invention, by distributing the treatment liquid so that the treatment liquid comes into contact with the entire inner surfaces of the micropores and the fine structure of the material to be treated,
It is possible to prevent the occurrence of film chipping on the inner surface of the micropores or the microstructure of the material to be treated, and to obtain a film having a uniform film thickness.

Further, according to the present invention, even in the cleaning step, which is a pre-step of supplying the material to be processed to the processing tank, the decompressing means depressurizes the inside of the closed chamber in which the cleaning tank is housed. It is possible to remove air bubbles trapped in the micropores and the microstructure of the processing material, and stains attached to the micropores and the inner surface of the microstructure. Therefore, in the present invention, the cleaning liquid is spread so that the cleaning liquid is brought into contact with the entire inner surface of the micropores or the fine structure of the material to be treated, and the metal plating formed on the inner surface of the micropores or the fine structure and the inner surface thereof. The bond with the membrane is strengthened.

[Brief description of drawings]

FIG. 1 is a schematic view of an electroless plating apparatus used in an electroless nickel plating method according to the present invention.

FIG. 2 is a cross-sectional view of a microstructure of a material to be plated in a plating process. FIG. 2A is a cross-sectional view of micropores and a microstructure of the material to be plated when the pressure in the chamber is normal pressure. Yes, (B) is a cross-sectional view in which the volume of the micropores of the material to be plated and the bubbles of the microstructure are increased, and
FIG. 4D is a cross-sectional view of the micropores and microstructure of the plated material from which bubbles have separated, and FIG. 6D is a cross-sectional view of the micropores and microstructure of the plated material into which the electroless nickel plating solution has entered. .

FIG. 3 is a cross-sectional view of the micropores and microstructure of the material to be plated in the degreasing / purifying step, and FIG. 3A is a cross-sectional view of the micropores and microstructure when the pressure in the sealed chamber is normal pressure. FIG. 2B is a cross-sectional view of bubbles in the micropores due to depressurization, and FIG. 3C is a cross-sectional view of the micropores and microstructure of the plated material from which the bubbles have separated. (D) is a cross-sectional view of the micropores and microstructure of the plated material in which the degreasing liquid has entered.

FIG. 4 is a flowchart of an electroless nickel plating method according to the present invention.

FIG. 5 is a cross-sectional view of micropores and microstructure of a material to be plated on which a nickel plating film is formed.

[Explanation of symbols]

1 Electroless nickel plating equipment, 2 Plated materials, 3
Nickel plating film, 4 plating mechanism, 5 drying mechanism, 6
Closed chamber, 7 decompression pump, 8 on-off valve, 9 degreasing tank, 10 first pure water cleaning tank, 11 acid cleaning tank, 12
Neutralization tank, 13 plating tank, 14 second pure water cleaning tank,
15 degreasing liquid, 16 pure water, 17 acidic solution, 18 alkaline solution, 19 electroless nickel plating solution, 20 stirring mechanism, 21 ultrasonic mechanism, 22 heating mechanism, 23 connecting pipe, 24 air bubble, 25 oil and fat

Claims (2)

[Claims] 1. A liquid surface treatment apparatus comprising: a treatment tank filled with a treatment liquid; a hermetically sealed chamber in which the treatment tank is housed; and a decompression means for decompressing the interior of the hermetic chamber. A step of supplying a material to be treated having fine pores or a complicated microstructure of the surface to the treatment tank and immersing it in the treatment liquid; and a step of reducing the pressure inside the closed chamber by the pressure reducing means. Then, a surface treatment method using a liquid phase is characterized in that the inside of the closed chamber is depressurized to subject the material to be treated to a surface treatment. 2. A cleaning step of cleaning the material to be processed as a pre-step of supplying at least the material to be processed to the processing tank, wherein the cleaning step is performed in a cleaning tank housed in the closed chamber. A step of immersing the material to be treated in the filled cleaning liquid, and a step of bringing the closed chamber into a decompressed state by the decompression means, and decompressing the closed chamber to wash the material to be treated The method for surface treatment with a liquid phase according to claim 1, wherein