KR100568389B1 - Surface treatment agent, and surface-treated article and electroless nickel plating method using the same - Google Patents

Abstract

An object of the present invention is to provide a surface treatment liquid capable of reducing the frequency of drying of the catalyst liquid used for electroless nickel plating on copper or copper alloy, and to improve the stability of the surface treatment agent.

The surface treating agent is a liquid obtained by mixing or reacting a silane coupling agent having a functional group having a metal trapping ability in a molecule with a noble metal compound in advance, and further adding an oxidizing agent improves the stability of the treating agent. In addition, the surface treatment agent also has an effect of improving the wettability of the surface, particularly the metal surface.

Description

SURFACE TREATMENT AGENT, AND SURFACE-TREATED ARTICLE AND ELECTROLESS NICKEL PLATING METHOD USING THE SAME}

The present invention relates to a surface treatment agent, an article surface-treated using the same, and a method of electroless nickel plating on copper or copper alloy surface-treated using the same.

More specifically, the present invention is a mixture or reaction of a silane coupling agent and a noble metal compound having both a function of capturing a noble metal serving as a catalyst for electroless plating and a function of fixing on a plated substrate in the same molecule. The present invention relates to a surface treatment agent having improved liquid stability, a surface treatment product using these treatment agents, and an electroless nickel plating method by adding a surface treatment agent and an oxidizing agent made of the prepared liquid.

The electroless plating method is a method of forming a metal film on a substrate having no conductivity, and is used in a method of forming a printed wiring on a resin substrate. As a pretreatment of this electroless plating, a method called "activation" in which a noble metal such as palladium is previously attached to the substrate as a catalyst is generally used. After treating the substrate with an aqueous hydrochloric acid solution of SnCl ₂ and then immersing it in an aqueous PdCl ₂ solution to adsorb Pd to the substrate, or using a colloidal solution containing Sn and Pd, Pd is supported on the surface of the substrate. Has been used. These methods have many problems, such as the use of Sn which has high toxicity, and a complicated process.

In order to electroless nickel-plated on copper or copper alloy, the use of a catalyst is required. In general, a method in which palladium is used as a substitution plating by immersion in a hydrochloric acid solution of palladium chloride is used. However, in this method, since the copper eluted into the solution through the substitution reaction gradually accumulates in the catalyst solution, the copper eluted in the relationship of liquid equilibrium is an obstacle to the substitution reaction.

Therefore, when the catalyst liquid is used continuously for repeatedly performing the above catalyst use mechanism for a certain time, a sufficient amount of palladium catalyst for electroless nickel plating is not attached at any point, so that the new catalyst liquid is bathed. (建 浴) is necessary. As the frequency of the bath increases, the amount of palladium used increases. Since palladium is an expensive precious metal, a method of reducing the frequency of bathing is required.

In recent years, as a method of supporting precious metals such as Pd, which is a catalyst for electroless plating, various methods of using a silane coupling agent having a functional group capable of forming a complex with these precious metals have been proposed. 52701, Japanese Patent Application Laid-Open No. 60-181294, Japanese Patent Application Laid-Open No. 61-194183, and Japanese Patent Application Laid-Open No. 3-44149. The present inventors also proposed several methods using the plating surface treatment agent obtained by mixing or reacting a silane coupling agent and a noble metal compound in advance (Japanese Patent Application 2000-1645 and Japanese Patent Application 2000-238047).

However, these liquids have a problem that they are liable to change over time, and there is insufficient liquid stability such as precipitation.

[Initiation of invention]

The technical problem of the present invention is to improve this problem of the surface treatment agent for electroless plating. That is, it aims at providing the surface treating agent which reduces the frequency of the dry bath of the catalyst liquid used at the time of electroless nickel plating, and it aims at providing the electroless nickel plating method using this surface treating agent. Moreover, it aims at improving the liquid stability of the said surface treating agent.

As a result of earnest examination, the present inventors have found that the use of a silane coupling agent having a functional group having a metal trapping ability as the surface treating agent is useful for reducing the frequency of drying.

Further, it has been found that the cause of the change over time in the liquid in which the noble metal compound and the silane coupling agent having a function of capturing it are mixed or reacted in advance is in the reduction reaction of the noble metal compound. As a countermeasure, the present inventors have found that the change over time is suppressed by adding an oxidizing agent, and the present inventors have found that the liquid stability is improved.

That is, this invention is as follows.

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(1) A surface treatment agent obtained by adding an oxidizing agent to a liquid obtained by mixing or reacting a silane coupling agent having a functional group having a metal trapping ability in a molecule with a noble metal compound in advance.

(2) The surface treatment agent according to the above (1), wherein the silane coupling agent having a functional group having metal trapping ability in the molecule is a silane coupling agent obtained by the reaction of an azole compound and an epoxy silane compound.

(3) The surface treating agent according to the above (1), wherein the functional group having a metal trapping ability is an imidazole group.

(4) The surface treatment agent according to the above (1), wherein the noble metal compound is a palladium compound.

(5) The surface treatment agent according to the above (1), wherein the silane coupling agent and the noble metal compound are mixed or reacted in advance at a weight ratio shown below.

1/10 <(silane coupling agent / noble metal compound) <5/1

(6) The surface treating agent according to the above (1), wherein the oxidizing agent is persulfate.

(7) The surface treatment agent according to the above (1), wherein the pH of the surface treatment agent is 2.0 or less.

(8) An electroless nickel plating method characterized by electroless nickel plating after pretreatment of copper or copper alloy with the surface treatment agent according to any one of (1) to (6).

(9) The surface treated material treated with the surface treating agent in any one of said (1)-(6).

In this invention, it is important to use the said specific silane coupling agent. That is, by the presence of a functional group having a metal trapping ability in the molecule, it is possible to obtain an electronic state or orientation that effectively expresses the activity of the plating catalyst, and by using the silane coupling agent, It becomes possible to express the adhesiveness of. In addition, the surface treatment agent of the present invention also has an effect of improving the wettability of the surface, particularly the metal surface.

Examples of the silane coupling agent having a functional group having a metal trapping ability used in the surface treatment agent of the present invention include, but are not limited to, a silane coupling agent having an amino group, a carboxyl group, an azole group, a hydroxyl group, a mercapto group, and the like. Do not. Among these, the silane coupling agent which has an azole group is preferable. Examples of the azole group include imidazole, oxazole, thiazole, selenazole, pyrazole, isoxazole, isothiazole, triazole, oxadiazole, thiadiazole, tetrazole, oxtriazole, thia Triazole, bendazole, indazole, benzimidazole, benzotriazole and the like. Especially, imidazole group is especially preferable. In addition, the silane coupling agent means a compound having a -SiX ₁ X ₂ X ₃ group in addition to the noble metal ion capture group, wherein X ₁ , X ₂ , X ₃ are each an alkyl group, a halogen, an alkoxy group, and the like. It is a functional group that can be fixed. X ₁ , X ₂ and X ₃ may be the same or different.

Such silane coupling agents themselves are known. For example, Japanese Unexamined Patent Application Publication No. 6-256358 discloses a silane coupling agent obtained by the reaction of an azole compound and an epoxy silane compound. Moreover, as an epoxy-group containing silane compound made to react with such a nitrogen-containing heterocyclic azole compound,

Epoxysilane coupling agents represented by (wherein R ¹ and R ² each represent hydrogen or an alkyl group having 1 to 3 carbon atoms and n is an integer of 1 to 3) are preferable.

The reaction between the azole compound and the epoxy group-containing silane compound can be carried out under the conditions disclosed in Japanese Patent Laid-Open No. 6-256358. For example, 0.1-10 mol of epoxy group containing silane compounds are dripped at 80-200 degreeC with respect to 1 mol of azole compounds, and it is made to react for 5 minutes-2 hours. At this time, the solvent is not particularly required, but an organic solvent such as chloroform, dioxane, methanol, or ethanol may be used.

As other examples of the silane coupling agent having a metal trapping ability used in the present invention, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxy Silane, N- (beta) (aminoethyl) (gamma) -aminopropyl triethoxysilane, (gamma)-mercaptopropyl trimethoxysilane, etc. are mentioned.

Examples of the noble metal compound include chlorides such as palladium, silver, platinum, and gold, amine complexes such as hydroxides, oxides, sulfates, and ammonium salts, which exhibit a catalytic effect in depositing copper, nickel, and the like from an electroless plating solution. Etc .; Especially a palladium compound, especially palladium chloride is preferable. The noble metal compound is preferably used as an aqueous solution, and the concentration in the solution to be treated is preferably 5 to 300 mg / L. In particular, when depositing nickel on the surface of copper or copper alloy from an electroless plating solution, the concentration of the noble metal compound in the solution to be treated is more preferably 5 to 100 mg / L.

When the surface treatment of the substrate to be electroplated is carried out using the obtained liquid obtained by mixing or reacting a silane coupling agent having a functional group having a metal trapping ability and a noble metal compound in the above molecule, the liquid is water, methyl alcohol, ethyl It can be used as a solution dissolved in a suitable solvent such as alcohol, 2-propanol, acetone, toluene, ethylene glycol, polyethylene glycol, dimethylformamide, dimethyl sulfoxide, dioxane, or mixtures thereof. In particular, when water is used, the pH of the solution should be optimized according to the surface to be plated and the plating conditions.

For cloth or plate-like substrates, a solvent is volatilized after surface coating by dipping or brush application, but is not limited thereto. What is necessary is just the method of making a silane coupling agent adhere. For copper or copper alloy, a method of volatilizing a solvent after surface coating by dipping treatment is common, but it is not limited to this, What is necessary is just a method of attaching a silane coupling agent uniformly to the surface of copper or a copper alloy. Depending on the adhered state, only washing with water and the drying step may be omitted.

In addition, in the case of powder, in addition to the method of forcibly attaching the silane coupling agent contained in the solution to the substrate surface by volatilizing the solvent after the immersion treatment, due to the uniform film formation ability of the silane coupling agent Adsorption of the silane coupling agent to the surface of the substrate in the immersion state is also possible, and thus a method of drying the wet powder by filtration of the solvent after the treatment is also possible. Depending on the adhered state, only washing with water and the drying step may be omitted.

Although the density | concentration of the silane coupling agent which has a functional group which has a metal trapping ability in a molecule | numerator in a solution to be processed is 0.001-10 weight% easily, although it is not limited to this. In the case of less than 0.001% by weight, the amount of the compound adhering to the surface of the substrate tends to be low, and effects are hardly obtained. Moreover, when it exceeds 10 weight%, it will become difficult to dry because it is too much adhesion amount, or it will become easy to cause aggregation of powder.

In the present invention, the change over time due to the reduction reaction of a noble metal exhibiting a catalytic effect by adding an oxidizing agent to a liquid obtained by mixing or reacting a silane coupling agent having a functional group having a metal trapping ability in a molecule and a noble metal compound in advance. Is suppressed and the liquid stability is improved. In the present invention, as the oxidizing agent, persulfates such as sodium persulfate, potassium persulfate, or ammonium persulfate, peroxides such as hydrogen peroxide, ferric chloride, cupric chloride, nitric acid, and the like can be used. Especially, persulfate is especially preferable. As for the density | concentration of the oxidizing agent to add, 0.01-100 g / L is preferable. If the concentration is lower than 0.01 g / L, the effect of the oxidizing agent is not sufficiently exhibited. On the other hand, if the concentration is higher than 100 g / L, there is a fear that the oxidizing agent adversely affects the substrate to be plated. The stability of a liquid in which a silane coupling agent having a functional group having a metal trapping ability and a noble metal compound are mixed or reacted in advance in the molecule is improved by adding an oxidizing agent to the liquid, but is further improved by lowering the pH. In particular, by setting the pH to 2.0 or less, the stability of the liquid is improved. Moreover, stability of a liquid improves significantly by setting pH to 1.5 or less.

In order to volatilize the solvent used after the surface treatment, it is sufficient to dry the surface by heating above the evaporation temperature of the solvent. When water is used as the solvent, the drying step may be omitted, and plating may be performed only by washing with water after surface treatment. However, in this case, in order to prevent the catalyst which is not trapped by the silane coupling agent from being carried into the plating liquid, it is necessary to sufficiently wash the water.

When a silane coupling agent having a functional group having a metal trapping ability in the molecule and a noble metal compound are mixed or reacted in advance in the weight ratios shown below, and used as a surface treatment agent for electroless nickel plating on copper or copper alloy, it is room temperature (10 to 10). Electroless nickel plating is possible by the said pretreatment in 30 degreeC).

1/10 <Silane coupling agent / Precious metal compound <5/1

When the said weight ratio is less than 1/10, the ratio of a silane coupling agent is too low, and metal trapping ability does not appear sufficiently. Moreover, when the said weight ratio exceeds 5/1, interaction of silane coupling agents becomes large and metal capture | acquisition ability does not appear sufficiently, either. In addition, when the silane coupling agent and the noble metal compound which have a functional group which has a metal trapping ability in a molecule | numerator are mixed or reacted previously by the weight ratio shown below, and used as a surface treating agent for electroless nickel plating on copper or copper alloy, 10 to 30 DEG C) allows electroless nickel plating by a shorter time of pretreatment.

1/2 <silane coupling agent / noble metal compound <2/1

Of course, you may wash | clean (for example, with dilute sulfuric acid) of a to-be-plated surface before plating pretreatment.

Although pretreatment temperature is enough at room temperature, heating may be effective depending on the to-be-plated material. Of course, the plating surface may be washed before the plating pretreatment is performed. When excellent adhesiveness is especially required, the conventional etching treatment with chromic acid or the like may be used. In the case of plating, it is sometimes effective to pretreat the plated body with the surface treatment agent and then to treat the solution with a solution containing a reducing agent. In particular, in the case of copper plating, it may be treated with a dimethylamine-borane solution, sodium hypophosphite solution or the like as a reducing agent. In addition, it is also possible to first conduct electroless plating to form a thin metal film to give the substrate which is not conductive to a certain degree of conductivity, and then to perform electroplating or substitution plating with a base metal. According to the present invention, metals such as copper, nickel, cobalt, tin, and gold can be plated by electroless plating.

In addition, the surface treating agent of the present invention can be used not only for the pretreatment of plating but also for improving the wettability of the substrate surface. Liquids with this effect are liquids of high polarity; In particular, the wettability to water can be greatly improved. It is a substrate with improved wettability and exhibits a great effect on copper, nickel and the like. When the wettability of the metal surface is improved, the coating property and adhesion can be improved when applying solder, resin, or the like to the metal surface.

1 is a graph showing the relationship between the copper concentration in the surface treatment agent and the minimum immersion time in the surface treatment agent required to deposit nickel plating.

FIG. 2 is a photograph illustrating wettability of a surface treated with the surface treating agent shown in Example 14. FIG.

3 is a photograph illustrating wettability of a surface treated with the surface treating agent shown in Comparative Example 3. FIG.

Best Mode for Carrying Out the Invention

Preliminary Test Example 1

Electrolytic copper foil (thickness: 20 µm) was used as the material to be plated, and after washing with 5% dilute sulfuric acid (1 minute), equimolar with imidazole and γ-glycidoxypropyltrimethoxysilane An aqueous solution containing 50 mg / L of a silane coupling agent and 50 mg / L of palladium chloride as a reaction product was immersed and washed at 20 ° C. for a predetermined time, and electroless nickel plated under the following conditions.

Nickel Sulfate: 20g / L

EDTA: 10g / L

Ammonium Sulfate: 40g / L

Sodium hypophosphite: 20 g / L

pH: 9.0

Bath temperature: 30 ℃

Plating time: 1 minute

Preliminary Test Example 2

It was electroless as in Preliminary Test Example 1 except that the surface treatment agent was changed to an aqueous solution containing 40 mg / L of silane coupling agent and 40 mg / L of palladium chloride, which is an equimolar reaction product of imidazole and γ-glycidoxypropyltrimethoxysilane. Nickel plating was performed.

Preliminary Test Example 3

It was electroless as in Preliminary Test Example 1 except that the surface treatment agent was changed to an aqueous solution containing 30 mg / L of silane coupling agent and 30 mg / L of palladium chloride, which is an equimolar reaction product of imidazole and γ-glycidoxypropyltrimethoxysilane. Nickel plating was performed.

Preliminary Test Example 4

It was electroless as in Preliminary Test Example 1 except that the surface treatment agent was changed to an aqueous solution containing 20 mg / L of silane coupling agent and 20 mg / L of palladium chloride, which is an equimolar reaction product of imidazole and γ-glycidoxypropyltrimethoxysilane. Nickel plating was performed.

Comparative Example 1

Electroless nickel plating was carried out as in Preliminary Test Example 1 except that the surface treatment agent was changed to an aqueous solution containing 50 mg / L of palladium chloride and 10 mL / L of 36% concentrated hydrochloric acid.

Comparative Example 2

Electroless nickel plating was carried out as in Preliminary Test Example 1 except that the surface treatment agent was changed to an aqueous solution containing 40 mg / L of palladium chloride and 10 mL / L of 36% concentrated hydrochloric acid.

In any of Preliminary Test Examples 1 to 4 and Comparative Examples 1 and 2, nickel plating was deposited within 30 seconds of immersion in the surface treatment agent. In addition, copper chloride was gradually added to each of the surface treatment agents in order to investigate the effect of elution of copper. Table 1 and FIG. 1 show the relationship between the copper concentration in the surface treatment agent and the minimum immersion time in the surface treatment agent required to deposit nickel.

Table 1

Copper concentration in surface treatment agent (mg / L) 0 300 400 500 600 700 1000 1500 2000 2500 Preliminary Test Example 1 20 seconds 20 seconds 20 seconds 20 seconds 20 seconds 20 seconds 20 seconds 40 seconds 50 seconds 50 seconds Preliminary Test Example 2 20 seconds 20 seconds 20 seconds 30 seconds 30 seconds 30 seconds 30 seconds 50 seconds 60 seconds 70 seconds Preliminary Test Example 3 20 seconds 20 seconds 20 seconds 30 seconds 30 seconds 40 seconds 40 seconds 60 seconds 80 sec 90 sec Preliminary Test Example 4 30 seconds 30 seconds 30 seconds 50 seconds 60 seconds 70 seconds - - - - Comparative Example 1 20 seconds 30 seconds 50 seconds 60 seconds 70 seconds 80 sec 110 seconds - - - Comparative Example 2 30 seconds 70 seconds 100 sec - - - - - - -

Compared with 60 seconds of immersion time in the surface treatment agent, in Comparative Examples 1 and 2 using a general surface treatment agent composed of palladium chloride and hydrochloric acid, the copper concentration was only 500 or 250 mg / L even if the palladium chloride concentration was 50 or 40 mg / L. Plating was not possible; However, in the case of the surface treatment agent containing the silane coupling agent shown in the preliminary test examples 1 to 4, plating can be performed even if the copper concentration is 5 times or more at the same palladium chloride concentration (preliminary test examples 1 and 2), and also the palladium chloride concentration. Even if it was as low as 20 mg / L (preliminary test example 4), the copper concentration could be plated to 600 mg / L.

When the electrolytic copper foil (30 mm x 40 mm x 20 micrometers) was immersed for 300 minutes at 20 degreeC in 100 mL of the pretreatment example 1 and the surface treating agents of the comparative example 1, the amount of copper dissolution (the stirring speed of stirrer 0 and 100 rpm) is shown in Table 2 . In the case where the stirring speed of the stirrer is 0 rpm, the amount of copper eluted in Preliminary Test Example 1 is less than half of Comparative Example 1, and in the case of 100 rpm, the difference becomes larger and becomes about 1/8.
TABLE 2

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Stirring Speed of Stirrer (rpm) Copper Elution Rate (mg / L) Preliminary Test Example 1 0 22 Preliminary Test Example 1 100 74 Comparative Example 1 0 52 Comparative Example 1 100 564

As described above, by using the surface treating agent of the present invention, the amount of copper eluted into the surface treating agent is reduced, and the allowable concentration of copper in the surface treating agent is also increased; As a result, the frequency of the dry bath of the surface treatment agent can be significantly reduced, thereby reducing the use of expensive palladium.

Examples 1-6, Comparative Examples 3-5

To the aqueous solution containing 40 mg / L of silane coupling agent and 40 mg / L of palladium chloride, which are equimolar reaction products of imidazole and γ-glycidoxypropyltrimethoxysilane, various amounts of sodium persulfate were added, and the pH was also changed. To make; The stability of each product was investigated by observing the change over time when left at room temperature (up to 30 days). The results are shown in Table 3.

TABLE 3

Sodium Persulfate (g / L) pH Days until sedimentation occurs Example 1 0.1 1.0 No precipitation Example 2 0.1 1.5 No precipitation Example 3 1.0 2.0 12 days Example 4 0.4 2.0 6 days Example 5 1.0 2.5 2 days Example 6 3.0 3.0 2 days Comparative Example 3 0 2.0 1 day Comparative Example 4 0 2.5 1 day Comparative Example 5 0 3.0 1 day

As shown in Examples 1 and 2, in the system in which sodium persulfate was added at pH 1.5 or less, no precipitation occurred at room temperature for 30 days. In addition, as shown in Examples 3 and 4, it can be seen that, at pH 2.0, the higher the concentration of sodium persulfate, the longer the number of days until precipitation occurs, and the oxidant is effective in improving liquid stability. On the other hand, as shown in Comparative Example 3, in the system without addition of sodium persulfate, precipitation occurred on day 1 even at pH 2.0. In addition, as shown in Examples 5 and 6, even when the pH is higher than 2.0 by adding a large amount of sodium persulfate, the liquid stability is improved. As shown in Table 3, the more the amount of sodium persulfate added and the lower the pH, the higher the inhibitory effect of the change over time. Moreover, after the test of Table 3, these liquids were used for electroless nickel plating on the electrolytic copper foil (thickness 20 micrometers). The treatment was performed in the order of 5% dilute sulfuric acid washing (1 minute), water washing, immersion in the surface treatment agent (25 ° C, 1 minute), water washing, and electroless nickel plating. The conditions of electroless nickel plating are as follows. For each liquid, electroless nickel plating could be done without a problem.

Nickel Sulfate: 20g / L

EDTA: 10g / L

Ammonium Sulfate: 40g / L

Sodium hypophosphite: 20 g / L

pH: 9.0

Bath temperature: 30 ℃

Plating time: 1 minute

Example 7

A copper plate plated with 1 μm of nickel was added to an aqueous solution containing 40 mg / L of coupling agent, 40 mg / L of palladium chloride, and 1.0 g / L of sodium persulfate, which is an equimolar product of imidazole and γ-glycidoxypropyltrimethoxysilane. It was immersed for 1 minute at room temperature. After washing with water, wetting on water was observed. Although the surface was partially discolored, as shown in FIG. 2, the wettability of the nickel plated copper plate was greatly improved, and no water shedding was observed.

Comparative Example 6

The wetness to water was observed by using the nickel plated 1 micrometer plated copper plate untreated. As shown in Fig. 3, the wettability of the nickel-plated copper sheet was poor, and water repulsion was observed.

As described above, in order to perform electroless nickel plating on copper or copper alloys, the provision of a catalyst is not required, and in the past, the catalyst is imparted by substitution plating of palladium or the like on copper or copper alloys.

However, as described above, the catalyst adhesion by the substitution reaction accumulates copper ions in the catalyst liquid and gradually hinders the catalyst adhesion. As a result, the expensive catalyst liquid needs to be dried. On the other hand, in the case of the surface treatment agent of the present invention, catalyst adhesion to the substrate surface is not performed by substitution plating, and the silane coupling agent is fixed on copper or copper alloy, so that the catalyst bound to the silane coupling agent is simultaneously used. By adhering on copper or copper alloys; Therefore, the influence of the elution of copper can be reduced, and the frequency of drying of a new catalyst liquid (surface treatment agent) can be reduced significantly.

In the present invention, by further adding an oxidizing agent to the surface treatment agent, the reduction reaction of the noble metal is suppressed, and as a result, the liquid stability is improved.

In addition, by using the surface treating agent of the present invention, the wettability of the metal surface can be improved.

Claims (10)

An oxidizing agent selected from the group consisting of persulfate, peroxide, ferric chloride, cupric chloride, and nitric acid is added to a liquid obtained by mixing or reacting a silane coupling agent having a metal-containing functional group with a metal and a noble metal compound in a molecule in advance. Surface treatment agent which is added by addition. The surface treatment agent according to claim 1, wherein the silane coupling agent having a functional group having a metal trapping ability in the molecule is a silane coupling agent obtained by a reaction between an azole compound and an epoxy silane compound. The surface treating agent according to claim 1, wherein the functional group having a metal trapping ability is an imidazole group. The surface treating agent according to claim 1, wherein the noble metal compound is a palladium compound. The surface treatment agent according to claim 1, wherein the silane coupling agent and the noble metal compound are mixed or reacted in advance in a weight ratio shown below. 1/10 <(silane coupling agent / noble metal compound) <5/1 The surface treatment agent according to claim 1, wherein the oxidant is persulfate. The surface treatment agent according to claim 1, wherein the pH of the surface treatment agent is 2.0 or less. An electroless nickel plating method comprising electroless nickel plating after pretreatment of copper or copper alloy with the surface treating agent according to any one of claims 1 to 6. A surface treatment treated with the surface treatment agent according to any one of claims 1 to 6. delete

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