WO2004024985A1

WO2004024985A1 - Electroless-plating solution, method of electroless plating with the same, and object plated by electroless plating

Info

Publication number: WO2004024985A1
Application number: PCT/JP2003/011663
Authority: WO
Inventors: Kazuya Saiki; Tsutomu Aoyagi; Heitaro Ban
Original assignee: Inspire Technology Resource Management Corporation
Priority date: 2002-09-11
Filing date: 2003-09-11
Publication date: 2004-03-25
Also published as: JP2009102750A; JPWO2004024985A1; JP4294589B2; AU2003264410A1; JP4910005B2; TW200406504A

Abstract

A work to be treated is exposed to a first electroless-plating solution containing a metal salt, a metal complexing agent, a reducing agent, and at least one member selected from the group consisting of a composition comprising ammonia water and a thiosulfate and of thiourea to thereby form a first deposit layer on the surface of the work. This work is then exposed to a second electroless-plating solution containing a fluororesin, a metal salt, a metal complexing agent, and a surfactant to form a second deposit layer on the first deposit layer. Thus, a plated work is provided which has a fluororesin coating having excellent adhesion to the base work.

Description

Description Electroless plating solution, electroless plating method using the same, and electroless plating object

The present invention relates to an electroless plating solution, an electroless plating method using the same, and an electroless plating object. Background art

Fluororesins have extremely high durability against chemicals, have excellent electrical properties, and are stable at high temperatures. It is common practice to coat fluororesin. In order to improve the adhesion of such a fluororesin to the object to be treated, a method of roughening the surface of the object to be treated in advance and then coating the fluororesin is generally performed. Alternatively, after a treatment with an organic binder, a method of applying a relatively thick coating of a fluorine resin so that the layer thickness becomes about 100 to 200 ^ m is also performed (see, for example, 1-3 2 8 1 2 1 JP, JP 2 00 0-3 2 8 2 56 6 JP, JP-A 4 3 6 5 8 7 5 JP, Tokuhei 1 1 6 0 5 8 4 Gazette, JP-A-61-234202, JP-A-5-11112348).

However, in the method of applying a fluorine resin coating on the roughened surface after the roughening forming treatment of the surface of the object to be processed as in the above-described conventional technology, the following problems may occur depending on the shape of the unevenness. . In other words, if the unevenness of the concave and convex portions is not so high, about 1 ^, and the roughened surface is formed, There was a problem that the height of the unevenness almost disappeared by filling up the concave portion, the adhesion of the fluororesin was remarkably low, and peeling occurred.

In addition, since fluororesins are relatively expensive, the market demands that the thickness of the fluororesin be reduced, the amount of the fluororesin used be reduced, and the cost be reduced. However, simply reducing the thickness of the fluororesin coating results in extremely poor adhesion due to the low coefficient of friction between the fluororesin and the fluororesin coating, and pinholes are easily generated in the coating. There was a problem that it was impossible to form a thin fluororesin coating film. Disclosure of the invention

Therefore, an object of the present invention is to provide an electroless plating object having a fluororesin coating having extremely good adhesion to an object, an electroless plating method thereof, and an electroless plating solution used for the same. To provide.

The present inventor has conducted intensive studies in order to solve the above-mentioned problems. As a result, the first object containing at least one selected from ammonia water and a composition solution containing thiosulfate, and thiourea is described. Forming a first plating layer by exposing to a second plating liquid containing a fluororesin on the surface of the first plating layer to form a second plating layer; It has been found that a good fluororesin thin film is formed.

That is, in a first embodiment of the present invention, at least one of a group consisting of a metal salt, a metal complexing agent, a reducing agent, a composition solution containing aqueous ammonia and thiosulfate, and thiourea, The present invention provides an electroless plating solution characterized by containing:

In the electroless plating solution according to the present invention, the concentration of the thiourea may be 0.1 to 100 ppm. In the electroless plating solution according to the present invention, the metal complexing agent may be lactic acid.

In the electroless plating solution according to the present invention, the concentration of the metal complexing agent is 1 to 1;

0 0 g Z 1.

In the electroless plating solution according to the present invention, the metal salt is at least one selected from the group consisting of a nickel salt, a cobalt salt, a chromium salt, a titanium salt, and a hypophosphite. Can be.

In a second embodiment of the present invention, a step of exposing the object to be processed to the first electroless plating solution to form a first plating layer on the surface of the object to be processed; Forming a second plating layer on the first plating layer by further exposing the object to be treated to a second electroless plating liquid containing a salt, a metal complexing agent, a reducing agent, and a surfactant; An electroless plating method is provided, comprising:

In the electroless plating method according to the present invention, the metal salt contained in the second electroless plating solution is selected from the group consisting of a nickel salt, a cobalt salt, a chromium salt, a titanium salt, and a hypophosphite. It can be at least one or more species.

In the electroless plating method according to the present invention, the surfactant contained in the second electroless plating solution may be at least one of a group consisting of a cationic surfactant and a nonionic surfactant. it can.

In the electroless plating method according to the present invention, the concentration of the fluororesin contained in the second electroless plating solution may be 20 to 60 g / 1.

In a third embodiment of the present invention, there is provided an object to be plated, which is obtained by the above electroless plating method.

In the plating object to be treated according to the present invention, the plating hardness is 400 HV or more. Can be.

In the plating object to be treated according to the present invention described above, the plating adhesion strength may be 350 kgf / cm or more. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a cross-sectional view showing a state in which a first plating layer is formed on a plating object.

FIG. 2 is a cross-sectional view showing a state where a first plating layer and a second plating layer are formed on a plating object. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of the electroless plating solution according to the present invention, an electroless plating method using the same, and an electroless plating object to be processed will be described in detail.

The electroless plating solution (first electroless plating solution) according to the present invention comprises a metal salt, a metal complexing agent, a reducing agent, a composition solution containing aqueous ammonia and thiosulfate, and thiourea. At least one of the group and Further, in the electroless plating method according to the present invention, the first plating layer is formed on the surface of the processing object by exposing the processing object to the above electroless plating solution (first electroless plating solution). And further exposing the object to a second electroless plating solution containing a fluororesin, a metal salt, a metal complexing agent, and a surfactant to form a second plating layer on the first plating layer. Forming a step. FIG. 1 is a cross-sectional view conceptually showing a state in which a first plating layer is formed on a plating object. FIG. 2 is a cross-sectional view conceptually showing a state in which a first plating layer and a second plating layer are formed on an object to be treated. 1 denotes an object to be processed, 2 denotes a convex portion, 3 denotes a concave portion, 4 denotes a first plating layer, and 5 denotes a second plating layer. The above “electroless plating” is a method of plating on an object to be processed without supplying electricity. A wide range of materials, such as metal products, alumina products, rubber products, and synthetic resins, can be used for the object to be processed. It is desirable that the object to be treated is subjected to a pretreatment for improving the adhesion to the object to be treated, etc., according to each material.

The metal salt contained in the first electroless plating includes a nickel salt, a cobalt salt, a chromium salt, a titanium salt, a hypophosphite and the like, and can be used alone or in combination. However, it is not limited to these. It is preferably at least one or more selected from the group consisting of nickel salts and cobalt salts.

The metal complexing agent contained in the first electroless plating solution of the present invention is an organic substance or the like which forms a complex with a metal salt, but a metal complexing agent which can provide a preferable concave surface on the object to be treated is preferable. Although not limited, lactic acid is preferably used as the metal complexing agent. When the metal complexing agent is reduced in the plating solution, fine particles of the metal complexing agent are formed in the plating solution, but when large metal complexing agent powder particles of about 2-3 zm are formed, It is not desirable to obtain concave surfaces because it becomes unstable in liquid and promotes liquid decomposition. Since lactic acid has a fine particle powder of 1 m or less, it is preferable for obtaining a concave surface due to small liquid decomposition. Incidentally, as the metal complexing agent contained in the second electroless plating solution, a metal complexing agent such as glycine can be used.

The concentration of the metal complexing agent contained in the first electroless plating solution is preferably from 1 to 100 g / 1, and more preferably from about 10 to 20 g / 1. When the concentration of the metal complexing agent in the plating solution is increased, the plating layer is roughened, the degree of unevenness (difference in height) on the plating layer surface is increased, and good adhesion to the fluororesin coating can be obtained. . When the concentration of the metal complexing agent is in the above range, a difference in height of unevenness suitable for fluorine coating is obtained, and liquid decomposition is eliminated, so that particularly preferable adhesion to fluorine resin coating is obtained. The ammonia solution and the thiosulfate-containing composition solution and thiourea contained in the first electroless plating solution are used to equalize the height of the projections of the irregularities formed on the plating layer surface. As a result, an object to be treated having very good adhesion to the fluororesin coating can be obtained. Hereinafter, this will be described in more detail. As described above, when the object to be treated is plated with an electroless plating solution containing a low concentration of a metal complexing agent (first electroless plating solution), the surface of the plating layer has almost no irregularities. Even if a coating with a fluororesin is applied on a plating layer having a small surface (difference in height), good fluororesin coating cannot be obtained. On the other hand, as the concentration of the metal complexing agent in the plating solution increases, the plating layer becomes rougher and the degree of unevenness (difference in height) on the plating layer surface increases, but the height of the projections is not uniform and constant. A plating layer that does not change is formed. Even if a fluororesin coating is applied on such a plating layer having uneven surface protrusions, a fluororesin coating with good adhesion cannot be obtained. The present inventors have found that the first electroless plating solution contains the above composition solution or thiourea or a mixture thereof when forming the first plating layer formed on the surface of the object to be processed. The height of the upper part of the layer surface is made uniform, that is, the first plating layer having only the concave portions formed on the flat surface of the plating layer is formed, and the first plating layer containing a fluororesin on the first plating layer is formed. The present inventors have found that, when the fluororesin coating is performed with the electroless plating solution of No. 2, the fluororesin coating having an extremely good adhesion to an object to be processed is obtained, and the present invention has been achieved. It should be noted that the mechanism of forming the plating layer in which only the concave portion is formed on the flat portion by making the height of the convex portion on the surface constant by using the above-mentioned composition liquid thiourea has not been elucidated yet, It is considered that the composition solution thiourea suppresses the precipitation of irregularities in some way.

As the thiosulfate contained in the above-mentioned composition solution containing aqueous ammonia and thiosulfate, sodium thiosulfate and the like can be used. The first nothing The composition solution containing aqueous ammonia and thiosulfate contained in the electrolytic plating solution may further contain chlorine and the like.

The content of the composition liquid contained in the first electroless plating solution is preferably 1 to 40 g Z1 from the viewpoint of obtaining a fluorine-containing resin coating having good adhesion. , 10 to 30 g Zl.

The content of thiourea contained in the electroless plating solution is set such that the concentration of thiourea contained in the first electroless plating solution is 0 from the viewpoint of obtaining a fluororesin coating having good adhesion. It is preferably from 1 to 100 ppm, more preferably from 50 to 100 ppm. In addition, when a large amount of thiourea is used, the toxic effect becomes stronger, the resin is decomposed by reacting with the fluororesin, and it becomes difficult to form a film of the fluororesin. A coating is obtained.

The reducing agent contained in the first electroless plating solution and the second electroless plating solution may be a reducing agent, for example, sodium borohydride or the like.

The pH of the first electroless plating solution and the second electroless plating solution may be a pH at which a metal salt contained in the plating solution can precipitate as a metal. The metal salt in the plating solution forms a stable soluble complex with lactic acid, but the free metal ion concentration decreases as the pH increases, and the equilibrium potential shifts in the negative direction. If the pH is too high, the metal is less likely to precipitate, while if the pH is too low, the coating is redissolved, and the metal is less likely to precipitate. The pH of the first electroless plating solution and the second electroless plating solution is more preferably from 4.1 to 6.0 in order to favorably perform metal deposition in the plating process of the present invention.

The fluorine resin contained in the second electroless plating solution is a resin containing a fluorine group, and a fluorine resin such as tetrafluoroethylene (PTFE) is used. Can be. The concentration of the fluororesin in the second electroless plating solution can be arbitrarily selected depending on the application, and is preferably 20 to 60 g / 1, but is not limited thereto.

The surfactant contained in the second electroless plating solution prevents the precipitation of the substance to be complexed, and the dispersing agent of the fluororesin so that the fluororesin can be dispersed and penetrated well into the concave portions of the first plating layer. Demonstrate the function as. As such a surfactant, it is preferable to use at least one of the group consisting of a cationic surfactant and a nonionic surfactant. Cationic surfactants include quaternary ammonium salts, secondary amines, tertiary amines, and indazolines, and nonionic surfactants include polyoxyethylene, polyethylene, carboxylic acid, and sulfonic acid. The nonionic surface activity of the system can be used, but is not limited thereto. It is also preferable to use a fluorine surfactant having a bond of a carbon element or a fluorine atom in the molecule. The content of the surfactant in the second electroless plating solution is preferably from 0.1 to L gZl, and more preferably from 0.1 to 0.5 gZl. While the fluororesin containing the metal salt in the above range can satisfactorily disperse and penetrate into the recesses of the first plating layer, can the second plating layer have a low surface roughness and an appropriate smooth surface? It is. The second electroless plating solution preferably contains a dispersing aid in order to further improve the penetration and penetration of the fluorine resin into the concave portions of the first plating layer. Such dispersing aids include, but are not limited to, cerium oxide and silicon carbide.

The electroless plating process of the present invention can be performed in the same manner as the electroless plating method generally used in the plating industry. Hereinafter, an example of the plating process will be described, but the present invention is not limited thereto. First, the object to be treated is immersed in the first electroless plating solution at a solution temperature of about 60 to 70 ° C for about 5 to 30 minutes, taken out, washed with water, and left in an environment at room temperature of about 25 ° C. And dry. Use the first electroless plating solution The height of the convex portions of the plating layer obtained by the keying treatment is made uniform. Next, the workpiece treated with the first plating solution is immersed in the second electroless plating solution at a temperature of about 60 to 70 ° C for about 60 to 120 minutes, taken out, washed with water, and then washed at room temperature at about 25 ° C. Leave to dry underneath. Next, the workpiece with the first plating layer and the second plating layer adhered to the surface is placed in a furnace maintained at a temperature of about 300 to 500 ° C and left for about 10 to 60 minutes for baking. The treatment is performed to obtain a plating object according to the present invention having a fluororesin coating on the surface of the object.

Hereinafter, the plating object processed by the electroless plating method according to the present invention will be described. The thickness of the first plating layer of the plating object is preferably from 0.1 to 50 m, more preferably from 0.1 to 10 m, in order to obtain the adhesion between the object and the fluororesin. . The thickness of the second plating layer of the plating processing object is also preferably 0.1 to 50 m, and 0.1 to 30 xm, in order to obtain a film thickness capable of exhibiting good fluororesin adhesion. More preferred.

The plating object to be treated obtained by the above method has an excellent adhesion between the fluororesin coating and the object to be treated, and has an adhesion of 350 kgf Zcm, preferably 600 kgf / cm or more, and 750 kgf / cm or more. Has strength. The plating object to be treated obtained by the above method has a hardness of 400 HV or more, preferably 500 HV or more, more preferably 950 HV or more. Example

Hereinafter, specific examples of the electroless plating solution according to the present invention, the electroless plating method using the same, and the plating object are shown, but the examples are exemplifications of embodiments of the present invention, and are not limited thereto. Not something. In addition, under the following measurement conditions, the surface roughness measurement, the plating hardness measurement, and the plating adhesion were performed on the plated material obtained in each example. A strength measurement, a corrosion resistance test, and a surface analysis were performed.

The surface roughness was measured using a fluorescent X-ray method.

The plating adhesion strength was measured by a metal bending method specified in JIS B 7721 (ie, a method of bending a metal plate and confirming peeling of surface treatment by the bending force).

In the hardness measurement, Shimadzu Micro Hardness Tester HNV-2000 (manufactured by Shimadzu Corporation) was used as the hardness tester.

The corrosion resistance test is as follows: (A) Soak in hydrochloric acid solution (concentration: 36.47%) at 100 ° C for 60 minutes, take out from the solution, wash with water, leave at room temperature and dry, (B) 100 ° After infiltrating into C sodium hydroxide solution (concentration 50%) for 80 minutes, take out from the solution and leave it at room temperature to dry. (C) Tricrene solution (concentration 50%) at 100 ° C (hydrofluoric acid solution, Hydrochloric acid solution and sulfuric acid solution both have a concentration of 20%, temperature 25 ° (: 24 hours after infiltration, take out from the solution, wash with pure water and dry at room temperature. This was investigated by observing the surface at a magnification of 50,000 times using).

Surface analysis is to check for missing particles or pinholes. It was examined by observing the surface of the object to be processed at a magnification of 50,000 with an electron microscope. Example 1

Nickel 40 g / ⁷ 1 sulfate, cobalt acetate 25 GZL, sodium hypophosphite 0. 5 GZL, lactate 10 gZ 1, and aqueous ammonia 40 by weight% and Chio sodium sulfate 50 wt% and chlorine as a metal complexing agent A 10% by weight solution containing 40 gZl, a pH of 5.8, and a first electroless plating solution maintained at a temperature of 80 ° C, a stainless steel plate (J1S standard SUS 304 ) For 30 minutes, The stainless steel plate was taken out of the first electroless plating solution, washed with water, allowed to stand at room temperature, and dried. The surface roughness of the stainless steel plate was 0.18 m. On the surface of the stainless steel plate, a first plating layer having a layer thickness of 52111 and a concave portion having a groove depth of about 4 ^ 111 was formed on a flat surface.

Next, the stainless steel plate having the first plating layer is further immersed in the first electroless plating solution held at 70 ° C. for 20 minutes, and then the stainless steel plate is taken out from the second electroless plating solution. After washing with water, it was left in a normal temperature environment and dried. The second electroless plating solution contains nickel sulfate 30 g / l, cobalt acetate 20 gZl, sodium hypophosphite 0.5 g / l, glycine 0.5 gZl as a metal complexing agent, and a dispersion aid. 15 gZl as cerium oxide, 60 g / l polytetrafluoroethylene (PTEF) as fluororesin, 10 gZ1 phosphorus oxide as surface stabilizing effect, Megafac F-150 as a cationic surfactant (Dainippon Ink Industries, Ltd.) ), And Triomnx-100, a nonionic surfactant (Ishizu Pharmaceutical Co., Ltd.), and the pH of the solution was adjusted to 3.5. On the first plating layer of the stainless steel plate, a second plating layer having a thickness of 7 m and having a bronze color was formed. The surface of this second plating layer was flat by PTFE.

A stainless steel plate with the first and second plating layers adhered to the surface is placed in a furnace maintained at 380 ° C and left for 30 minutes to perform baking treatment. To be processed, which is the final product formed in the above.

The surface roughness of the final object to be treated was 0.81. As described above, the surface roughness of the first plating layer and the surface roughness of the stainless steel plate are 0.35 m and 0.18 m, respectively. It can be seen that the roughness is extremely smooth.

Further, the plating hardness of the thin film obtained as described above was an extremely high value of 480 HV. The plating adhesion density of the final plating object is 750 k. g fZcm. In addition, the above (A) to (C) were performed as corrosion resistance tests. In each case, no missing particles or abnormal pinholes were observed, and there was no change. Example 2

Nickel sulfate 30gZl, Cobalt acetate 20gZl, Sodium hypophosphite 0.5g / Lactic acid 1.5g / as metal complexing agent and 40% by weight of ammonia water, 50% by weight of sodium thiosulfate and 10% by weight of chlorine A stainless steel plate (J1S standard SUS 304) is immersed for 20 minutes in the first electroless plating solution maintained at a pH of 5.3, a liquid temperature of 70 ° C, containing 5 g Zl. Thereafter, the stainless steel plate was taken out of the first electroless plating solution, washed with water, left in a room temperature environment, and dried. The surface roughness of the stainless steel plate was about 1 m. On the surface of the stainless steel plate, a first plating layer with a thickness of 10 ^ 311 and a concave part with a groove depth of about 3 m was formed on a flat surface.

Next, the stainless steel plate having the first plating layer is further immersed in the first electroless plating solution maintained at 70 ° C. for 20 minutes, and then the stainless steel plate is taken out from the second electroless plating solution, After washing with water, it was left in a normal temperature environment and dried. The second electroless plating solution contains nickel sulfate 40 gZl, cobalt acetate 20 g / l, sodium hypophosphite 0.5 g / l, glycine 0.5 gZl as a metal complexing agent, and cerium oxide as a dispersion aid. 1.5gZl, 40gZ of polytetrafluoroethylene (PTEF) as fluororesin and titanium oxide as reducing agent 1.5gZ1, Megafax F-150 (Dainippon Inkie Co., Ltd.) which is a cationic surfactant, and non- Triomnx-100 (Ishizu Pharmaceutical Co., Ltd.), which is an ionic surfactant, was added, and the pH of the solution was adjusted to 5.3. On the first plating layer of the stainless steel plate, a second plating layer having a bronze color and a thickness of 10 m is formed. Was. The surface of this second plating layer was flat by TEF.

The stainless steel plate with the first and second plating layers adhered to the surface is placed in a furnace maintained at a temperature of 70 ° C and left for 20 minutes to perform baking treatment, and a thin film by electroless plating is formed. An object to be treated, which is a final product formed on the surface, was obtained.

The surface roughness of the final plating object was 5 m. As described above, the surface roughness of the first plating layer and the surface roughness of the stainless steel plate are 3 m and 4 m, respectively, which means that the surface roughness of the final plating object (second plating layer) is extremely high. It turns out that it is smooth.

In addition, the plating hardness of the thin film obtained as described above was an extremely high value of 980 HV. The plating adhesion density of the final plating object was 750 kgf Zcm. In addition, the above (A) to (C) were performed as corrosion resistance tests. In each case, no missing particles or abnormal pinholes were observed, and there was no change. Example 3

Nickel sulfate 40 g / l, cobalt acetate 40 gZl, sodium hypophosphite 0.5 g / l, lactic acid 1.5 gZ1 as a metal complexing agent, and ammonia water 40% by weight and sodium thiosulfate 50% by weight And a 10% by weight of chlorine solution, containing a stainless steel plate (J1S) in the first electroless plating solution maintained at a solution pH of 6.0 and a solution temperature of 75 ° C. After immersing standard SUS 304) for 30 minutes, the stainless steel plate was taken out from the first electroless plating solution, washed with water, allowed to stand at room temperature, and dried. The surface roughness of the stainless steel plate was 3 m. On the surface of the stainless steel plate, a first plating layer having a thickness of 10 m with a recess having a depth of about 3 m on a flat surface was formed.

Next, the stainless steel plate having the first plating layer was further kept at 70 ° C. After immersion in the obtained first electroless plating solution for 20 minutes, the stainless steel plate was taken out from the second electroless plating solution, washed with water, allowed to stand at room temperature and dried. In the second electroless plating solution, nickel sulfate 20 g / 1, cobalt acetate 15 gZ1, sodium hypophosphite 0.5 g / l, glycine 0.5 gZl as a metal complexing agent, dispersion aid 0.5 gZl of cerium oxide as a surfactant, 45 gl of polytetrafluoroethylene (PTEF) as a fluororesin, 10 g of titanium oxide as a reducing agent / 1 Megafac F-150, a cationic surfactant (Dai Nippon Ink Kogyo Co., Ltd. )) And Tritonx-100 (Nonionic surfactant) (Ishizu Pharmaceutical Co., Ltd.), and the pH of the solution was adjusted to 5.8. On the first plating layer of the stainless steel plate, a second plating layer having a bronze color and a layer thickness of 10 im was formed. The surface of this second plating layer was flat by TEF.

The surface roughness of the final plating object was 2 zm. As described above, the surface roughness of the first plating layer and the surface roughness of the stainless steel plate are 1 and 2 m, respectively, which means that the surface roughness of the final plating object (second plating layer) is extremely high. It turns out that it is smooth.

Further, the plating hardness of the thin film obtained as described above was an extremely high value of 480 HV. The plating adhesion density of the final plating object was 750 kgf Zcm. In addition, the above (A) to (C) were performed as corrosion resistance tests. In each case, no missing particles or abnormal pinholes were observed, and there was no change. Example 4 Nickel sulfate 30 g "Cobalt acetate 10 g / l, Sodium hypophosphite 0.5 g / Lactic acid 15 gZ1 as metal complexing agent, and ammonia water 40% by weight, sodium thiosulfate 50% by weight and chlorine In a first electroless plating solution maintained at a solution pH of 5.3 and a solution temperature of 70 ° C, a stainless steel plate (J13 standard 3113304) was added. ) Was immersed for 20 minutes, the stainless steel plate was taken out of the first electroless plating solution, washed with water, allowed to dry at room temperature, and dried using the same second electroless plating solution as in Example 1 above. In the same manner, plating was performed, and baking was performed under the same conditions to obtain a workpiece to be treated.The stainless steel plate had a flat surface with a recess with a groove depth of about 2 m and a layer thickness of 2 m. A first plating layer was formed On the first plating layer, a second layer having a thickness of 15 / m and having a bronze color was formed. Was formed.

The surface roughness of the final processed object was 2 / m. The surface roughness of the first plating layer and the surface roughness of the stainless steel plate are 2 and 5 m, respectively, which means that the final plating object (second plating layer) has extremely smooth surface roughness. You can see that.

Further, the plating hardness of the thin film obtained as described above was an extremely high value of 480 HV. The plating adhesion density of the final plating object was 780 kgf / cm. In addition, the above (A) to (C) were performed as corrosion resistance tests. In each case, no missing particles or abnormal pinholes were observed, and there was no change. Example 5

Contains nickel sulfate 40 g / l, cobalt acetate 5 g / l, sodium hypophosphite 20 g / l, lactic acid 15 gZ1 as a metal complexing agent, and 0.5 ppm of thiourea. 5, into the first electroless plating solution maintained at a solution temperature of 60 ° C, After immersing a stainless plate (J1S standard SUS304) for 20 minutes, the stainless plate was taken out of the first electroless plating solution, washed with water, allowed to stand at room temperature, and dried. Next, the same plating process was performed using the same second electroless plating solution as in Example 1 described above, and a baking process was performed under the same conditions to obtain a plating processed object. On the surface of the stainless steel plate, a first plating layer having a thickness of 3 m and a recess having a depth of about 2 m on a flat surface was formed. On the first plating layer, a second plating layer having a layer thickness of 10 m and having a bronze color was formed.

The surface roughness of the object to be plated was 4 m. The surface roughness of the first plating layer and the surface roughness of the stainless steel plate are 2 and 3, respectively, which means that the surface roughness of the final plating object (second plating layer) is extremely smooth. I understand.

Further, the plating hardness of the thin film obtained as described above was an extremely high value of 480 HV. The plating adhesion density of the final plating object was 780 kgfZcm. In addition, the above (A) to (C) were performed as corrosion resistance tests. In each case, no missing particles or abnormal pinholes were observed, and there was no change.

Claims

The scope of the claims

1. An electroless method characterized by comprising a metal salt, a metal complexing agent, a reducing agent, at least one of a group consisting of a composition solution containing aqueous ammonia and thiosulfate, and thiourea. Meat liquid.

2. The electroless plating solution according to claim 1, wherein the concentration of the thiourea is 0.1 to 100 ppm.

3. The electroless plating solution according to claim 1, wherein the metal complexing agent is lactic acid.

4. The electroless plating solution according to any one of claims 1 to 3, wherein the concentration of the metal complexing agent is 1 to 100 g / 1.

5. The metal salt is at least one selected from the group consisting of a nickel salt, a cobalt salt, a chromium salt, a titanium salt, and a hypophosphite. Or the electroless plating solution according to item 1.

6.A step of forming a first plating layer on the surface of the workpiece by exposing the workpiece to the first electroless plating solution according to any one of claims 1 to 5, A second plating layer is formed on the first plating layer by further exposing the object to a second electroless plating liquid containing a fluororesin, a metal salt, a metal complexing agent, a reducing agent, and a surfactant. Forming an electroless plating method.

7. The metal salt contained in the second electroless plating solution is at least one selected from the group consisting of a nickel salt, a cobalt salt, a chromium salt, a titanium salt, and a hypophosphite. 7. The electroless plating method according to claim 6, wherein:

8. The surfactant contained in the second electroless plating solution is at least one of a group consisting of a cationic surfactant and a nonionic surfactant. The electroless plating method according to claim 6, wherein the electroless plating method is used.

9. The electroless plating method according to claim 6, wherein the concentration of the fluororesin contained in the second electroless plating solution is 20 to 60 gZ1.

10. A plating object to be processed, obtained by the electroless plating method according to any one of claims 6 to 9.

11. The plating object according to claim 10, wherein the plating hardness is 400 HV or more.

12. The plating object to be treated according to claim 10 or 11, wherein the plating adhesion strength is 350 kg fZcm or more.