JP3857108B2 - Electroless plating method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention provides a material to be treated by immersing the material to be treated in a treatment liquid.Electroless platingApplyElectroless platingRegarding the method.
[0002]
[Prior art]
The surface treatment method using a liquid phase includes, for example, a plating method in which a metal film or the like is electrochemically formed on the surface of a material to be processed such as a metal component, or a passivation film is formed on the surface of the material to be processed. There are a passivation treatment, a chemical conversion treatment for forming a chemical film on the material to be treated, or a chemical polishing treatment for polishing the material to be treated in a liquid phase.
[0003]
For example, in the plating method, a metal plating film is formed on the surface of the material to be plated in order to improve the corrosion resistance, heat resistance, electromagnetic properties, or decorative properties of the material to be plated such as ceramic, glass, resin, or metal parts. This is a method of forming a film. The plating method includes an electroplating method and an electroless plating method.
[0004]
In the electroless plating method, a metal generated by an oxidation-reduction reaction that occurs 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 deposited on the surface of the material to be plated and a reducing agent that oxidizes the metal salt. In the electroless plating method, depending on the type of metal salt contained in the electroless plating solution, a plating process for forming a metal plating film such as nickel, copper, gold or silver on the surface of the material to be plated is performed. Can do. The electroless plating method is performed by a relatively simple apparatus because the metal plating film is formed on the surface of the material to be plated by the oxidation-reduction reaction that occurs in the plating solution.
[0005]
In the electroless plating method, a metal plating film is formed on the surface of the material to be plated which is in contact with the material to be plated, so that the plating solution is well spread over the surface of the material to be plated. It is possible to prevent the occurrence. As a method of spreading the plating solution, for example, there is a method of stirring the plating solution by providing a stirring mechanism provided with a stirring blade or the like in a plating tank or an ultrasonic mechanism that emits ultrasonic waves. The electroless plating method has a feature that a metal plating film can be formed on the surface of various materials such as resin, ceramic and glass in addition to metal.
[0006]
[Problems to be solved by the invention]
However, in the above-described electroless plating method, the material to be plated is immersed in the plating solution when 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. In some cases, a gas such as air in the minute holes or in the fine structure is trapped by the plating solution. In the electroless plating method, as described above, even when the plating solution is stirred by a stirring mechanism or the like, the surface that acts at the boundary between the micropores of the material to be plated and the bubbles confined in the microstructure and the plating solution It was difficult to remove bubbles from the inside of micropores and fine structures by energy. Therefore, in this electroless plating method, it is difficult to contact the plating solution with the micropores of the material to be plated or the inner surface of the microstructure due to the bubbles confined in the micropores or the microstructure. In some cases, chipping occurred on the inner surface. In addition, not only the electroless plating method described above, but also surface treatment methods using other liquid phases may cause chipping of the film.
[0007]
  Therefore, the present invention prevents the occurrence of film chipping on the inner surfaces of the minute holes formed on the material to be processed and the complicated fine structure on the surface, and makes it possible to apply a film having a uniform film thickness to the material to be processed. DoElectroless platingIt aims to provide a method.
[0008]
[Means for Solving the Problems]
  The present invention achieves the above-described object.Electroless platingThe method isFor applying electroless plating to materials to be processed having micropores and / or complex microstructures on the surfaceFilled with processing solutionpluralA treatment tank;pluralA hermetically sealed chamber in which the treatment tank is housed, and a decompression means for reducing the pressure in the sealed chamber;A transporting means for transporting the material to be treated;A liquid phase surface treatment apparatus comprising:DegreasingImmersion in processing solutionAndThe inside of the sealed chamber is decompressed by the decompression means.InFor processed materialsDegreasing treatmentGivingThen, the degreased material to be treated was immersed in pure water, the inside of the sealed chamber was depressurized by a decompression means, and the material to be treated was subjected to the first pure water washing treatment, and the first pure water washing treatment was performed. The material to be treated is immersed in an acidic solution, the inside of the sealed chamber is decompressed by a decompression means, the material to be treated is subjected to an acid cleaning treatment, and the material to be treated that has been subjected to the acid cleaning treatment is immersed in an alkaline solution, The inside of the sealed chamber is reduced in pressure by the step of neutralizing the material to be treated, the neutralized material to be treated is immersed in the plating solution, and the inside of the sealed chamber is reduced in pressure by the pressure reducing means. A plating process is performed, the plated material to be processed is immersed in pure water, the inside of the sealed chamber is decompressed by a decompression means, and the material is subjected to a second pure water cleaning process.It is characterized by that.
[0009]
  thisElectroless platingAccording to the method, the volume of the air bubbles confined in the micropores or the fine structure of the material to be processed immersed in the processing liquid is increased by making the inside of the sealed chamber in which the processing tank is accommodated into a reduced pressure state by the pressure reducing mechanism. As a result, the buoyancy of the bubbles is increased, the bubbles are removed from the inner surfaces of the micropores and the fine structure, and the processing liquid is spread so that the processing liquid contacts the entire inner surfaces of the micropores and the fine structure of the material to be processed. it can. Therefore,Electroless platingAccording to the methodDuring the degreasing process, the first pure water cleaning process, the acid cleaning process, the neutralization process, the plating process, and the second pure water cleaning process,It is possible to prevent film chipping from occurring on the micropores of the material to be processed and the inner surface of the microstructure, and to form a film with a uniform film thickness.
[0010]
  Also, according to the liquid phase according to the present inventionElectroless platingThe method isWhile maintaining the reduced pressure in the sealed chamber, the material to be treated is degreased, first pure water cleaning, acid cleaning, neutralization, plating, and second pure water cleaning by the transport means in order. ApplyIt is characterized by that.
[0011]
  According to this electroless plating method, the material to be treated is degreased by the transporting means, the first pure water washing treatment, the acid washing treatment, the neutralization treatment, the plating treatment, while the reduced pressure state in the sealed chamber is maintained. By sequentially performing the second pure water cleaning treatment, it is possible to perform electroless plating without requiring a work of reducing the pressure to a normal pressure for each process. Therefore, the manufacturing process is simplified and the manufacturing cost is reduced.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The surface treatment method using a liquid phase shown as an embodiment is a method of forming a nickel plating film 3 on a material to be plated 2 as a material to be treated by electroless nickel plating as shown in FIG. . The to-be-plated material 2 consists of metal, resin, ceramics, glass, or the like having minute holes, so-called through holes or bottomed holes in units of several microns, undercut portions, or a fine structure with a complicated surface.
[0013]
The electroless plating apparatus 1 includes a plating mechanism 4 and a drying mechanism 5. The plating mechanism 4 includes a sealed chamber 6, a decompression pump 7, and an on-off valve 8. A plurality of tanks are provided in the sealed chamber 6 in order to perform the plating process on the material to be plated 2. Specifically, the sealed chamber 6 includes a degreasing tank 9, a first pure water cleaning tank 10, an acid cleaning tank 11, a neutralization tank 12, a plating tank 13, and a second pure water cleaning tank 14. Is provided. The sealed chamber 6 can be provided for each process to perform each process.
[0014]
The degreasing tank 9 is filled with a degreasing liquid 15 that can remove oil adhering to the surface of the material to be plated 2. The degreasing tank 9 removes oil adhering to the surface of the material to be plated 2 by immersing the material 2 to be plated in the degreasing liquid 15.
[0015]
The first pure water cleaning tank 10 is filled with pure water 16 for cleaning the degreasing liquid 15 remaining on the surface of the material to be plated 2. In the 1st pure water washing tank 10, the degreasing liquid 15 adhering to the surface of the to-be-plated material 2 is removed by immersing the to-be-plated material 2 in the pure water 16. FIG.
[0016]
The acid cleaning tank 11 is filled with an acidic solution 17 that enables removal of dirt adsorbed by a chemical reaction such as an oxide film adhering to the surface of the material to be plated 2. In the acid cleaning tank 11, the plating film 2 attached to the surface of the material to be plated 2 is removed by immersing the material to be plated 2 in the acidic solution 17.
[0017]
The neutralization tank 12 is filled with an alkaline solution 18 for neutralizing the acidic solution 17 remaining on the surface of the material to be plated 2. In the neutralization tank 12, the acidic solution 17 attached to the surface of the material to be plated 2 is neutralized by immersing the material to be plated 2 in the alkaline solution 18.
[0018]
The plating tank 13 is filled with an electroless nickel plating solution 19 capable of depositing nickel and forming the nickel plating film 3 on the surface of the material to be plated 2. 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 forms the nickel plating film 3 on the surface of the material to be plated 2 by immersing the material to be plated 2 in the electroless nickel plating solution 19.
[0019]
The second pure water cleaning tank 14 is similar to the pure water 16 filled in the first pure water cleaning tank 10 in order to clean the electroless nickel plating solution 19 remaining on the surface of the material 2 to be plated. Of pure water 16 is filled. The second pure water cleaning tank 14 removes the electroless nickel plating solution 19 remaining on the surface of the plated material 2 by immersing the plated material 2 on which the nickel plating film 3 is formed in the pure water 16. To do.
[0020]
In each of the above-described tanks, the solution and pure water 16 are agitated in order to keep the concentration of the filled solution uniform and to make the solution and pure water 16 sufficiently contact the surface of the material 2 to be plated. The agitating mechanism 20 having the agitating blade 20a and the ultrasonic mechanism 21 for agitation by ultrasonic vibration are provided. The plating tank 13 is provided with a heating mechanism 22 for keeping the temperature of the electroless nickel plating solution 19 filled in the plating tank 13 in the range of 90 to 100 ° C.
[0021]
The sealed chamber 6 is decompressed by driving the decompression pump 7 and exhausting the internal gas by adjusting the on-off valve.
[0022]
The on-off valve 8 is connected between the decompression pump 7 and the sealed chamber 6 by connecting pipes 23a and 23b. The on-off valve 8 opens the sealed chamber 6 in a decompressed state by opening the sealed chamber 6 and the operating decompression pump 7 so as to communicate with each other via the connecting pipes 23a and 23b. The on-off valve 8 is closed so that the sealed chamber 6 and the decompression pump 7 are shut off when the sealed chamber 6 reaches a predetermined decompressed state, so that the pressure in the sealed chamber 6 is kept at a constant decompressed state. Hold on. The on-off valve 8 opens the sealed chamber 6 and the outside so as to communicate with each other via the connecting pipe 23a, thereby bringing the pressure in the sealed chamber 6 into a normal pressure state.
[0023]
The drying mechanism 5 is provided outside the sealed chamber 6, and removes moisture remaining on the surface of the material 2 to be plated by using, for example, a clean air blow or a heating / drying furnace.
[0024]
In the electroless plating apparatus 1 having the above-described configuration, as shown in FIG. 2, when the plating material 2 is subjected to a plating process, the pressure in the sealed chamber 6 is reduced, so that the micropores of the plating material 2 are reduced. In addition, the bubbles 24 trapped in the fine structure are removed.
[0025]
Specifically, as shown in FIG. 2 (A), the electroless plating apparatus 1 immerses the material to be plated 2 in the electroless nickel plating solution 19 in the sealed chamber 6 before decompression. The bubbles 24 are confined in the micropores and microstructure. Next, in the electroless plating apparatus 1, as shown in FIG. 2B, by reducing the pressure in the sealed chamber 6, the bubbles 24 confined in the micropores of the material to be plated 2 or the inner surface 2 a of the fine structure are formed. Volume increases. Next, in the electroless plating apparatus 1, as shown in FIG. 2 (C), the buoyancy is increased by increasing the volume of the fine holes or the bubbles 24 confined in the fine structure of the material 2 to be plated, Bubbles are released from the minute holes of the material 2 and the inner surface 2a of the microstructure. Next, in the electroless plating apparatus 1, as shown in FIG. 2D, the bubbles 24 are removed from the minute holes and the fine structure of the material to be plated 2. Therefore, in the electroless plating apparatus 1, the electroless nickel plating solution 19 can be distributed in the plating tank 13 so that the electroless nickel plating solution 19 contacts the entire micropores of the material to be plated 2 and the entire inner surface 2 a of the microstructure. it can.
[0026]
Similarly, in the electroless plating apparatus 1, the pressure in the sealed chamber 6 is reduced even when the material to be plated 2 before being plated is degreased and cleaned. In the electroless plating apparatus 1, for example, when the surface of the material to be plated 2 is degreased in the degreasing tank 9, as shown in FIG. 3A, the object to be immersed in the degreasing liquid 15 in the sealed chamber 6 before decompression. The fine holes in the plating material 2 and the gas in the fine structure are confined by the degreasing liquid 15. Next, in the electroless plating apparatus 1, as shown in FIG. 3B, the volume of the bubbles 24 confined in the minute holes or the fine structure of the material to be plated 2 is increased by depressurizing the sealed chamber 6. To do. In the electroless plating apparatus 1, as shown in FIG. 3C, the buoyancy is increased by increasing the volume of the bubbles 24 confined in the micropores or the fine structure of the material 2 to be plated. 2 and the oil 25 are also removed. Next, in the electroless plating apparatus 1, as shown in FIG. 3D, the bubbles 24 are detached from the minute holes and the fine structure of the material to be plated 2. Thereby, in the electroless plating apparatus 1, in the degreasing tank 9, it is possible to appropriately clean the fine holes of the material to be plated 2 and the entire inner surface 2a of the fine structure, and adhere to the inner surfaces 2a of the fine holes and the fine structure. The oil / fat 25 is removed.
[0027]
Next, an electroless nickel plating method using the above-described 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 cleaning step S2, an acid cleaning step S3, and a neutralization step S4. , A plating treatment step S5, a second pure water washing step S6, and a drying step S7.
[0028]
First, the degreasing step S1 is performed on the material to be plated 2. In the degreasing step S <b> 1, 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, while adding ultrasonic waves having a frequency of 20 KHz to 50 KHz by the ultrasonic mechanism 21 and stirring by the stirring mechanism 20 to the degreasing liquid 15 in which the material to be plated 2 is immersed, The on-off valve 8 is opened so that the sealed chamber 6 and the decompression pump 7 communicate with each other through the connecting pipes 23a and 23b, and the pressure in the sealed 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 sealed chamber 6 is depressurized to remove the fine holes of the material to be plated 2 and the bubbles 24 confined in the fine structure.
[0029]
Next, in the degreasing step S1, the on-off valve 8 is opened so that the sealed chamber 6 communicates with the outside via the connecting pipe 23a, and the pressure in the sealed 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 and fat 25 adhering to the material to be plated 2 is removed.
[0030]
Next, the material 2 to be plated is subjected to a first pure water cleaning step S2. In the first pure water cleaning step S <b> 2, when the material to be plated 2 is cleaned with pure water, the material to be plated 2 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, ultrasonic waves with a frequency of 20 to 50 KHz by the ultrasonic mechanism 21 and a rotation speed of 60 times / minute by the stirring mechanism 20 in the pure water 16 in which the material to be plated 2 is immersed. While adding agitation, the on-off valve 8 is opened so that the sealed chamber 6 and the decompression pump 7 communicate with each other via the connecting pipes 23a and 23b, and the pressure in the sealed chamber 6 is reduced to 1 Pa or less with respect to the atmospheric pressure. Reduce pressure. At this time, in the first pure water cleaning step S2, the bubbles 24 confined in the fine holes and the fine structure of the material to be plated 2 are removed, and the pre-degreasing step S1 for attaching the inner surface 2a of the fine holes and the fine structure. The degreasing liquid 15 used in the above step is extruded.
[0031]
Next, in the first pure water cleaning step S2, the on-off valve 8 is opened so that the sealed chamber 6 and the outside communicate with each other through the connecting pipe 23a, and the pressure in the sealed chamber 6 is brought to a normal pressure state. return. Next, the material to be plated 2 is taken out from the pure water 16. In this way, in the second pure water cleaning step S2, the degreasing liquid 15 attached to the material to be plated 2 is removed.
[0032]
Next, the material to be plated 2 is subjected to an acid cleaning step S3. In the acid cleaning step S <b> 3, when performing the acid cleaning on the material to be plated 2, the material to be plated 2 is immersed in the acidic solution 17 filled in the acid cleaning tank 11. 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 adding the ultrasonic wave having a frequency of 20 to 40 KHz by the ultrasonic mechanism 21 and the stirring by the stirring mechanism 20 to the acidic solution 17 in which the material to be plated 2 is immersed, The on-off valve 8 is opened so that the sealed chamber 6 and the decompression pump 7 communicate with each other via the connection pipe 23, and the pressure in the sealed 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 micropores of the material to be plated 2 and the bubbles 24 confined in the fine structure are removed, and the pure water 16 used in the first pure water cleaning step S2 is pushed out. .
[0033]
Next, in the acid cleaning step S3, the open / close valve 8 is opened so that the sealed chamber 6 communicates with the outside air via the connecting pipe 23a, and the inside of the sealed chamber 6 is returned to the normal pressure state. Next, the material to be plated 2 is taken out from the acidic solution 17. In this manner, in the acid cleaning step S3, the oxide film attached to the material to be plated 2 is removed.
[0034]
Next, the to-be-plated material 2 is subjected to a neutralization step S4. In neutralization process S4, when performing neutralization to the to-be-plated material 2, the to-be-plated material 2 is immersed in the alkaline solution 18 with which the neutralization tank 12 is filled. As the alkaline solution 18, a 5 to 10% alkaline solution 18 is used. Next, in the neutralization step S4, while adding ultrasonic waves with a frequency of 20 to 100 KHz by the ultrasonic mechanism 21 and stirring at a rotational speed of 60 times / minute by the stirring mechanism 20 at room temperature, the sealed chamber 6 and the vacuum pump 7 Is opened so as to communicate with each other via the connecting pipe 23, and the pressure in the sealed chamber 6 is reduced to 1 Pa or less with respect to the atmospheric pressure. At this time, in the neutralization step S4, the micropores of the material to be plated 2 and the bubbles 24 confined in the fine structure are removed, and the acidic solution 17 used in the pre-acid cleaning step S3 is pushed out.
[0035]
Next, in the neutralization step S4, the opening / closing valve 8 is opened so that the sealed chamber 6 communicates with the outside via the connecting pipe 23a, and the pressure in the sealed chamber 6 is returned to the normal pressure state. Next, the material to be plated 2 is taken out from the alkaline solution 18. Thus, in neutralization process S4, the acidic solution 17 adhering to the to-be-plated material 2 is neutralized.
[0036]
Next, a plating treatment step S5 is performed on the material to be plated 2. In the plating process S <b> 5, when the plating material 2 is plated, the plating material 2 is immersed in the electroless nickel plating solution 19. As the electroless nickel plating solution 19, a general electroless nickel plating solution 19 such as a mixed solution obtained by mixing an aqueous solution containing a nickel salt such as nickel chloride and a reducing agent such as sodium hypophosphite is used. Next, in the plating treatment step S5, stirring is performed at a rotation speed of 30 times / minute by the stirring mechanism 20 while keeping the electroless nickel plating solution 19 at 90 to 100 ° C. by the heating mechanism 22. Next, in the plating treatment step S5, the opening / closing valve 8 is opened so that the sealed chamber 6 and the decompression pump 7 communicate with each other via the connecting pipes 23a and 23b, and the pressure in the sealed chamber 6 is reduced to the atmospheric pressure. The pressure is reduced to 1 Pa or less. At this time, in the plating treatment step S5, the bubbles 24 attached to the minute holes of the material to be plated 2 and the inner surface 2a of the microstructure are removed, and the alkaline solution 18 used in the pre-neutralization step S4 is pushed out.
[0037]
Next, in the plating treatment step S5, the opening / closing valve 8 is opened so that the sealed chamber 6 and the outside communicate with each other via the connecting pipe 23a, and the inside of the sealed 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.
[0038]
In this way, in the plating step S5, as shown in FIG. 5, it is possible to prevent the occurrence of lack of plating in the minute holes of the material to be plated 2 or the inner surface 2a of the fine structure, and the nickel plating film having a uniform film thickness. 3 is formed.
[0039]
Next, a second pure water cleaning step S6 is performed on the material 2 to be plated. In the second pure water cleaning step S <b> 6, the material to be plated 2 is immersed in the pure water 16 when the material to be plated 2 is cleaned with pure water. Next, in the second pure water cleaning step S6, the sealed chamber 6 and the reduced pressure are added while applying ultrasonic waves with a frequency of 20 to 100 KHz by the ultrasonic mechanism 21 and stirring at a rotational speed of 60 times / minute by the stirring mechanism 20 at room temperature. The on-off valve 8 is opened so as to communicate with the pump 7 via the connecting pipes 23a and 23b, and the pressure in the sealed chamber 6 is reduced to 1 Pa or less with respect to the atmospheric pressure. At this time, in the second pure water cleaning step S6, the micropores of the material to be plated 2 and the bubbles 24 confined in the fine structure are removed, and the electroless nickel plating solution used in the pre-plating treatment step S5. 19 is extruded.
[0040]
Next, in the second pure water cleaning step S6, the on-off valve 8 is opened so that the sealed chamber 6 and the outside air communicate with each other through the connection pipe 23a, and the pressure in the sealed chamber 6 is brought to a normal pressure state. return. Next, the material to be plated 2 is taken out from the pure water 16. Thus, in the 2nd pure water washing | cleaning process S6, the to-be-plated material 2 to which the nickel plating film 3 was given can be washed with pure water.
[0041]
Next, the to-be-plated material 2 is subjected to a drying step S7. When the drying step S <b> 7 is performed on the material to be plated 2, dry air is blown onto the material to be plated 2 by a clean air blow provided in the drying mechanism 5. In the drying step S7, moisture adhering to the material to be plated 2 is removed at room temperature and normal pressure. Next, the material to be plated 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 lack of plating in the minute holes of the material to be plated 2 or the inner surface 2a of the fine structure, and to form the nickel plating film 3 having a uniform film thickness. can do.
[0042]
In the electroless nickel plating method described above, the inside of the sealed chamber 6 is decompressed by the decompression pump 7 and the plating treatment step S5 is performed, so that the micropores of the material 2 to be plated immersed in the electroless nickel plating solution 19 The bubbles 24 are removed from the inner surface 2a of the fine structure, and the electroless nickel plating solution 19 can be spread into the minute holes and the fine structure of the material 2 to be plated. Therefore, in the electroless nickel plating method, it is possible to prevent the occurrence of lack of plating in the minute holes of the material to be plated and the inner surface 2a of the microstructure, and to form the nickel plating film 3 having a uniform film thickness.
[0043]
In addition, the electroless nickel plating method performs the degreasing step S1 to the neutralization step S4 in the sealed chamber 6 with a reduced pressure pump 7 before the plating treatment step S5. In addition, air bubbles are removed from the inner surface 2a of the fine structure, and the cleaning liquid and pure water can be spread over the micropores of the material to be plated 2 and the entire inner surface 2a of the fine structure. As a result, the electroless nickel plating method cleans the micropores of the material to be plated 2 and the entire inner surface 2a of the fine structure.
[0044]
Therefore, according to the electroless nickel plating method, it is possible to clean the micropores of the material to be plated 2 and the entire inner surface 2a of the fine structure, and there is no unnecessary matter attached to the microholes or the inner surface 2a of the fine structure. Since it is removed, the bonding between the inner surface 2a of the minute hole or microstructure and the nickel plating film formed on the inner surface 2a is strengthened.
[0045]
In the above-described embodiment, the electroless nickel plating solution 19 is used for plating the material to be plated 2. However, the electroless copper plating solution and the electroless gold plating are not limited thereto. A solution, an electroless silver plating solution, an electroless cobalt plating solution, or the like may be used.
[0046]
In addition, the electroless nickel plating method uses an automatic conveyance mechanism that moves the material to be plated 2 by connecting the tanks to each other, and applies each step to the material to be plated 2 to obtain a reduced pressure state for each step. Thus, each step can be performed while maintaining a reduced pressure state of 1 Pa or less with respect to the atmospheric pressure without performing the operation of returning to the normal pressure state. Thereby, the electroless nickel plating method simplifies the manufacturing process and reduces the manufacturing cost.
[0047]
【The invention's effect】
  As described above in detail, according to the present invention, when a coating film is formed on a material to be treated, the inside of the sealed chamber in which the treatment tank is housed is decompressed by the decompression means, thereby being treated. It is possible to remove bubbles trapped in the micropores and microstructures of the material. Therefore, according to the present invention,During the degreasing process, the first pure water cleaning process, the acid cleaning process, the neutralization process, the plating process, and the second pure water cleaning process,It is possible to prevent a film chip from occurring on the micropores of the material to be processed and the inner surface of the microstructure, and to obtain a film having a uniform film thickness.
[0048]
  Further, according to the present invention, even in the cleaning step that is a pre-process for supplying the material to be processed to the processing tank, the inside of the sealed chamber in which the cleaning tank is housed is reduced by the pressure reducing means. It is possible to remove bubbles confined in the micropores and the fine structure, dirt attached to the inner surfaces of the micropores and the fine structure, and the like. Therefore, in the present invention, the cleaning liquid is spread so that the cleaning liquid contacts the entire inner surface of the micropores and microstructure of the material to be processed, so that the metal plating formed on the inner surface of the micropores and microstructure and the inner surface thereof is formed. Bonding with the membrane is strengthened.In addition, the material to be treated is degreased by the transport means, the first pure water washing treatment, the acid washing treatment, the neutralization treatment, the plating treatment, and the second pure water washing treatment while maintaining the reduced pressure in the sealed chamber. By sequentially applying the electroless plating, it is possible to perform electroless plating without requiring a work of reducing the pressure to a normal pressure for each step. Therefore, the manufacturing process is simplified and the manufacturing cost can be reduced.
[Brief description of the 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 the fine structure of the material to be plated in the plating process, and FIG. 2 (A) is a cross-sectional view of the fine hole and fine structure of the material to be plated when the pressure in the chamber is normal pressure. FIG. 5B is a cross-sectional view in which the volume of micropores and fine structure bubbles in the material to be plated is increased, and FIG. FIG. 4D is a cross-sectional view of a minute hole and a fine structure of a material to be plated into which an 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 process, and FIG. 3A is a cross-sectional view of the micropores and microstructure in a state where the pressure in the sealed chamber is normal pressure. FIG. 4B is a cross-sectional view of the bubbles in the micropores due to the reduced pressure, and FIG. 4C is a cross-sectional view of the micropores and the fine structure of the material to be plated from which the bubbles are released. (D) is sectional drawing of the micropore and fine structure of the to-be-plated material which the degreasing liquid 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 minute holes and microstructures of a material to be plated on which a nickel plating film is formed.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Electroless nickel plating apparatus, 2 to-be-plated material, 3 nickel plating film, 4 plating mechanism, 5 drying mechanism, 6 sealed chamber, 7 pressure reduction pump, 8 on-off valve, 9 degreasing tank, 10 1st pure water washing tank, DESCRIPTION OF SYMBOLS 11 Acid washing tank, 12 Neutralization tank, 13 Plating tank, 14 2nd pure water washing 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 Connection tube, 24 Air bubble, 25 Oil

Claims (2)

A plurality of treatment tanks filled with a treatment liquid for performing electroless plating on a material to be treated having minute holes and / or a complicated fine structure on the surface ;
A hermetically sealed chamber in which the plurality of treatment tanks are stored;
Pressure reducing means for reducing the pressure in the sealed chamber ;
A liquid phase surface treatment apparatus comprising a conveying means for conveying the material to be treated is used,
The material to be treated is immersed in a degreasing treatment liquid, the inside of the sealed chamber is decompressed by the decompression means , and the material to be treated is degreased ,
The degreased material to be treated is immersed in pure water, the inside of the sealed chamber is depressurized by the decompression means, and the material to be treated is subjected to a first pure water cleaning treatment,
The material to be treated that has been subjected to the first pure water cleaning treatment is immersed in an acidic solution, and the sealed material is subjected to an acid cleaning treatment by reducing the pressure in the sealed chamber by the pressure reducing means.
The acid-cleaned material to be treated is immersed in an alkaline solution, the inside of the sealed chamber is decompressed by the decompression means, and the material to be treated is neutralized.
The neutralized material to be treated is immersed in a plating solution, the inside of the sealed chamber is decompressed by the decompression means, and the material to be treated is plated.
The treated material which is the plating was immersed in pure water, and characterized by applying a second deionized water cleaning process on the workpiece in the vacuum state the sealed chamber by the pressure reducing means electroless Plating method. The degreasing treatment, the first pure water washing treatment, the acid washing treatment, the neutralization treatment, the plating treatment, and the above are performed on the material to be treated by the transporting means while maintaining the reduced pressure state in the sealed chamber. The electroless plating method according to claim 1, wherein the second pure water cleaning treatment is sequentially performed .

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