JP3277463B2 - Metal plating pretreatment agent and metal plating method using the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for metal plating by electroless plating on a surface of a material having low conductivity, a mirror-like object, a powder, or the like, and a metal plating pretreatment agent therefor.

BACKGROUND ART Electroless metal plating is one of the methods for forming a metal film on a non-conductive base. As a pre-treatment for electroless plating, activation and pre-adhesion of a noble metal such as palladium as a catalyst to the base are performed. The method called is common. Until now, PdCl ₂ after treatment with a hydrochloric acid aqueous solution of SnCl ₂
A method has been used in which Pd is adsorbed by immersion treatment in an aqueous solution, or Pd is supported on the surface by a colloid solution containing Sn and Pd. These methods have many problems such as the use of Sn and the complicated processing steps. Recently, various methods using a silane coupling agent having a functional group capable of forming a complex with such a noble metal have been proposed as a method for supporting a noble metal such as Pd, which is a catalyst for electroless plating, on the surface (see, for example, Japanese Patent Application Laid-Open No. H11-157572). JP 59-52701, JP 60-181294, JP 6
1-194183, Tokuhei 3-44149). However, when trying to uniformly adsorb the silane coupling agent shown here on the substrate, general amino silane coupling agents and epoxy silane coupling agents tend to gel in an aqueous solution due to the dehydration condensation reaction and have a high concentration. Insoluble in
In addition, hydrolytic condensation hardly occurs in an organic solvent, and the viscosity of the liquid is low because most of the monomer is present. For this reason, it is difficult to adjust the film thickness even if it is applied uniformly on a mirror object,
The coupling agent film could only be formed as a thin film. For this reason, only a small number of functional groups for capturing the noble metal can be present on the surface, so that the adhesion of the noble metal having the function of the plating catalyst in the subsequent process becomes uneven. As a result, it was difficult to form a uniform electroless plating film. For this reason, a method of electroless plating on mirror-surface glass is currently used in which the surface is roughened with hydrofluoric acid or a heated strong alkaline solution. In addition, even when treating powder, general amino silane coupling agents and epoxy silane coupling agents adhere little to the surface, so after completely evaporating the solvent of the treatment liquid and forcibly attaching it to the surface It had to be heated, dried and hydrolyzed and condensed.

DISCLOSURE OF THE INVENTION The present invention is a metal plating method by a new electroless plating that can be suitably electrolessly plated even on powders and mirror-like objects that have been difficult to apply the electroless plating in the past under such circumstances,
And a metal plating pretreatment agent therefor.

As a result of intensive studies, the present inventor has found that it can be solved by selecting a specific silane coupling agent as the silane coupling agent having the ability to form a complex with the noble metal ion, and has reached the present invention.

That is, the present invention provides (1) a metal plating pretreatment agent comprising a silane coupling agent obtained by reacting an azole compound having an active functional group that forms a complex with a noble metal ion with an epoxysilane compound; ) After treating an object to be plated, which has been surface-treated with a silane coupling agent obtained by a reaction between an azole compound having an active functional group that forms a complex with a noble metal ion and an epoxysilane compound, with a solution containing a noble metal ion, (3) The metal plating method according to (2), wherein the azole compound is an imidazole, (4) the metal plating method according to (2), wherein the noble metal ion is palladium ion. (5) The metal plating method according to (2), wherein the electroless plating is copper or nickel.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention provides a silane coupling agent used for supporting a noble metal such as Pd, which is a catalyst for electroless plating, on a surface to be plated, that is, a functional group having a complex forming ability with a noble metal. It is important to use a reaction product of an azole compound having an active functional group capable of forming a complex with the noble metal ion and an epoxysilane compound as the silane coupling agent having the above formula.

Examples of the azole compound include pyrrole, indole, imidazole, pyrazole, benzimidazole,
Examples include, but are not limited to, indazole. The epoxysilane-based compound is a compound having an epoxy group and an alkoxysilyl group in a molecule, and a general compound is γ-glycidoxypropylalkoxysilane, but is not limited thereto. . The silane coupling agent itself obtained by the reaction between the azole compound and the epoxysilane compound,
It is already known. For example, JP-A-6-256358 discloses that an imidazole silane compound is obtained by a reaction between an imidazole compound and epoxysilane,
The reaction with another azole compound can be carried out in the same manner. The silane coupling agent of this reaction product may be obtained in a state containing intermolecular and intramolecular condensates, but it is not necessary to separate them, and they can be used in a mixture state. This silane coupling agent has characteristics such as high reactivity, being able to adjust the concentration of the aqueous solution to an arbitrary value by adjusting the acidity of the aqueous solution, and giving the dissolved solution a certain degree of viscosity. For this reason, a film having a certain thickness and uniform thickness can be formed on the base of the object to be plated using the silane coupling agent. In addition, electroless plating can be easily applied to various bases including mirrors and powders that could not be processed without evaporating the solvent, which were difficult with general coupling agents represented by conventional aminosilanes. It is possible. Examples of the noble metal include palladium, silver, platinum, and gold, which exhibit a catalytic effect when depositing a metal such as copper or nickel on the surface of an object to be plated from an electroless plating solution. Palladium is particularly preferred.

According to the metal plating method of the present invention, the object to be plated is not limited in its properties. For example, inorganic materials such as glass and ceramics, plastic materials such as polyester, polyamide, polyimide, and fluororesin; insulating materials such as films, sheets, fibers, and insulating plates such as epoxy resins reinforced with glass cloth base materials as necessary. It is applied to substrates with low conductivity such as semiconductors such as silicon wafers and Si wafers, but the objects to be plated may be mirror-like objects such as transparent glass plates, Si wafers, other semiconductor substrates, or powder. However, the method of the present invention can be preferably applied. Examples of such a powder include glass beads, molybdenum disulfide powder, magnesium oxide powder, graphite powder, SiC powder, zirconium oxide powder, alumina powder, silicon oxide powder, mica flake, glass fiber, silicon nitride, and Teflon (trademark). Name) powder.

When the base to be subjected to electroless plating is treated with a silane coupling agent which is a reaction product of the azole compound and the epoxysilane compound as described above, the silane coupling agent may be treated with a suitable solvent such as water or methyl alcohol. , Ethyl alcohol, 2-propanol, acetone,
It can be used for a solution dissolved in toluene, ethylene glycol, polyethylene glycol or a mixed solution thereof. For plate-like substrates, it is common practice to volatilize the solvent after surface coating by dipping or brushing, but this is not a limitation, and the silane coupling agent is uniformly applied to the surface. Any method may be used. For powders, after the immersion treatment, the solvent is volatilized to forcibly attach the silane coupling agent contained in the solution to the base surface. Thus, the solvent can be adsorbed on the surface of the base in the immersion treatment state, so that a method of filtering off the solvent after treatment and drying the wet powder is also possible.

The concentration of the silane coupling agent in the solution to be treated is not limited to this, but 0.001 to 10% by weight is easy to use. If the amount is less than 0.001% by weight, the amount of the coupling agent adhering to the surface of the base material tends to be low, and it is difficult to obtain the effect. On the other hand, if it exceeds 10% by weight, the amount of adhesion is so large that it is difficult to dry and that the powder is apt to agglomerate. In order to volatilize the solvent used after the surface treatment, it is sufficient if the surface can be dried by heating to a temperature equal to or higher than the volatilization temperature of the solvent.
It is preferable to heat and dry at 60 to 120 ° C for 10 to 60 minutes.

The method of chemically plating the surface treated as described above is a known method. That is, by contacting with a solution containing a noble metal ion such as palladium, the noble metal is captured by the azole group of the coupling agent treated on the base surface. After washing away a soluble noble metal salt such as an excess halide and a solubilizing agent such as hydrochloric acid, a chemical plating treatment such as electroless plating is performed.

Alternatively, it is also possible to form a metal thin film by performing electroless plating first, and to give a certain degree of conductivity to a non-conductive base, and then 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. Typical electroless plating solutions used in the present invention include the following.

Fast thickness electroless copper plating composition for with a typical example _{CuSO 4 .5H 2 O 0.04~0.06mol / l} EDTA.2Na 0.04~0.12mol / l HCHO (37%) 0.08~0.5mol / l pH 12~12.5 plating temperature 70 to 90 ° C. lower temperature electroless copper plating composition typical example _{CuSO 4 .5H 2 O 12.5~14.5g / l} HCHO (37%) 20~25g / l Rochelle salt 25~40g / l pH 12.2~12.5 plating temperature 20 to 30 ° C. High temperature type acidic bath Electroless Ni plating composition typical example Nickel sulfate 20-22g / l Lactic acid 25-30g / l Propionic acid 2-3g / l Sodium hypophosphite 20-22g / l pH 4.5-5.5 Plating temperature 80-90 ℃ Low temperature type ammonia alkaline bath Electroless Ni plating composition typical example Nickel sulfate 24-26g / l Sodium pyrophosphate 48-52g / l Sodium hypophosphite 24-26g / l pH 10-11 Plating temperature 55-65 ℃ Example 1 After a slide glass plate having a thickness of 1 mm was treated with an alkaline degreasing solution, imidazole and γ-glycidoxypropyl ester were placed on the surface of the glass plate. 2 containing 0.4% by weight of a silane coupling agent which is an equimolar reaction product with limethoxysilane
-Spin-coated at 500 RPM using propanol solution. Thereafter, the plate was dried at 105 ° C. for 30 minutes. Further P
d After immersing in an activation solution CG-535A (activator, manufactured by Nikko Metal Plating Co., Ltd.) for 1 minute at room temperature,
The glass plate surface was washed with about 100 ml of deionized water and dried at 105 ° C. for 30 minutes to perform a precious metal activation treatment. Next, it was immersed in an electroless nickel plating solution Nikom 7N (manufactured by Nikko Metal Plating Co., Ltd.) at 80 ° C. for 4 minutes. The electroless nickel plating solution uniformly deposited a glossy film on the entire surface of the glass, and it was confirmed that the electroless nickel plating solution had good adhesion without peeling off with a cellophane tape.

Comparative Example 1 A slide glass plate having a thickness of 1 mm was treated with an alkaline degreasing solution, immersed in a Pd activation treatment solution CG-535A for 1 minute at room temperature without treating the surface with a coupling agent, and then treated with about 10
After washing with 0 ml and drying at 105 ° C. for 30 minutes, the surface of the glass plate was subjected to a noble metal activation treatment. Next, it was immersed in an electroless nickel plating solution Nicom 7N at 80 ° C. for 4 minutes. Electroless nickel plating hardly precipitated on the glass plate.

Comparative Example 2 A 1 mm-thick slide glass plate was immersed in a mixed solution of fluorine and nitric acid (hydrofluoric acid 100 ml / L, nitric acid 100 ml / L) at 25 ° C. for 10 minutes to roughen the surface. This glass plate is treated with an alkaline degreasing solution, immersed in a Pd activation treatment solution CG-535A for 1 minute at room temperature, washed with about 100 ml of deionized water, dried at 105 ° C. for 30 minutes, and the noble metal An activation process was performed. Next, it was immersed in an electroless nickel plating solution Nicom 7N at 80 ° C. for 4 minutes. Electroless nickel plating hardly precipitated on the glass plate.

Comparative Example 3 After a slide glass plate having a thickness of 1 mm was treated with an alkaline degreasing solution, an aminosilane coupling agent KBM-903 (γ-aminopropyltrimethoxysilane manufactured by Shin-Etsu Chemical Co., Ltd.) was added to the surface of the glass plate by 0.4. Spin coating was performed at 500 RPM using a 2-propanol solution containing weight%. Thereafter, the plate was dried at 105 ° C. for 30 minutes. Further, the glass plate surface was immersed in a Pd activation treatment liquid CG-535A for 1 minute at room temperature, washed with about 100 ml of deionized water and dried at 105 ° C. for 30 minutes to perform a precious metal activation treatment on the glass plate surface. Next, it was immersed in an electroless nickel plating solution Nicom 7N at 80 ° C. for 4 minutes. The electroless nickel plating was deposited only on a part of the glass plate.

Comparative Examples 4 and 5 To promote the hydrolysis-condensation reaction, a solution obtained by adding a small amount of hydrochloric acid to a mixture of water and 2-propanol equivalents was added with 0.4% by weight of aminosilane coupling agent KBM-903 and a concentration of 10%.
A solution was prepared by dissolving the doubled 4 wt% (Comparative Example 5), and after performing a noble metal activation treatment in the same manner as in Comparative Example 3, electroless nickel plating was performed. In each case, the electroless nickel plating was sparsely deposited on about half of the glass plate.

Example 2 A pet film (trade name: Diafoil) was subjected to ultrasonic cleaning in 2-propanol for 5 minutes to degrease the surface, and then dried at 105 ° C for 10 minutes. Next, this film was immersed for 1 minute in a 2-propanol solution containing 4% by weight of a silane coupling agent, which is an equimolar reaction product of imidazole and γ-glycidoxypropyltriethoxysilane. Dried for minutes. Furthermore, Pd activation treatment solution CG
After immersion in -535A for 1 minute at room temperature, rinse with deionized water
After drying at 105 ° C. for 10 minutes, the surface of the pet film was subjected to a noble metal activation treatment. Next, electroless copper plating solution KC-500
72 ° C in (trade name of Nikko Metal Plating Co., Ltd.)
For 20 minutes. The electroless copper plating uniformly deposited a glossy film on the entire surface of the pet film.

Example 3 A glass cloth-based epoxy resin insulating plate (Matsushita Electric Works) in a 2-propanol solution containing 0.4% by weight of a silane coupling agent, which is an equimolar reaction product of imidazole and γ-glycidoxypropyltrimethoxysilane. (Copper-clad laminate FR-4, copper is removed by chemical etching)
Was immersed for 1 minute and then dried at 105 ° C. for 60 minutes. Next, this laminate was immersed in a Pd activation treatment solution CG-535A at room temperature for 1 minute, washed with deionized water and dried at 105 ° C. for 60 minutes to perform a noble metal activation treatment on the laminate surface. When this plate is immersed in the electroless nickel plating solution Nikom 7N at 80 ° C for 2 minutes,
Electroless nickel plating was uniformly deposited on the laminate. Further, when the laminate treated with the same noble metal activation treatment was immersed in an electroless copper plating solution KC-500 at 70 ° C. for 30 minutes, copper was uniformly deposited on the surface.

Comparative Example 6 A glass cloth-based epoxy resin insulating plate similar to that of Example 3 was prepared by dissolving 0.4% by weight of an aminosilane coupling agent KBM-903 in a solution obtained by adding a small amount of hydrochloric acid to a mixture of water and 2-propanol equivalents. After being immersed in the solution for 1 minute, it was dried at 105 ° C. for 60 minutes. Further, the laminate was immersed in a Pd activation treatment solution CG-535A for 1 minute at room temperature, washed with deionized water, dried at 105 ° C. for 60 minutes, and subjected to a noble metal activation treatment on the laminate surface. When this plate was immersed in an electroless nickel plating solution Nicom 7N at 80 ° C. for 2 minutes, electroless nickel plating was deposited on the laminated plate, but about 80% of the total.

Example 4 20 g of glass beads having a diameter of about 1.5 mm was added to 50 ml of a 2-propanol solution in which 0.08 g of a silane coupling agent which is an equimolar reaction product of imidazole and γ-glycidoxypropylmethyldiethoxysilane was dissolved. Soak for a minute. The solution is filtered and dried at 105 ° C. for 30 minutes. Next, the glass beads were immersed in a Pd activation treatment solution CG-535A for 1 minute at room temperature, and the activation treatment solution was filtered, washed with 50 ml of deionized water, and dried at 105 ° C. for 30 minutes. Noble metal activation treatment was applied to the bead surface. When this glass bead was immersed in an electroless nickel plating solution Nicom 7N at 80 ° C. for 4 minutes, the electroless nickel plating was deposited almost uniformly on the entire surface of the bead.

Example 5 A silane coupling agent, which is an equimolar reaction product of imidazole and γ-glycidoxypropyltrimethoxysilane with 25 g of molybdenum disulfide powder having an average particle size of 50 μm
0.1 g was dissolved in 50 ml of 2-propanol solution at room temperature.
Stir for minutes. After distilling off the solvent 2-propanol, 10
Dry at 5 ° C for 60 minutes. Next, this molybdenum disulfide powder was stirred at room temperature for 20 minutes in 50 ml of a Pd activation treatment solution CG-535A, and the activation treatment solution was filtered off, washed with 50 ml of deionized water and then at 105 ° C. for 60 minutes. Drying was performed to activate the noble metal on the powder surface. The molybdenum disulfide powder was plated at 72 ° C. using an electroless copper plating solution KC-500. A uniform copper plating film could be formed on the powder surface by 1 wt% electroless copper plating, and the underlying molybdenum disulfide could be completely covered.

Comparative Example 7 After molybdenum disulfide powder having an average particle diameter of 50 μm was stirred in 50 ml of a Pd activation treatment solution CG-535A at room temperature for 20 minutes, the activation treatment solution was removed by filtration and further washed with 50 ml of deionized water. Thereafter, drying was performed at 105 ° C. for 60 minutes to activate the noble metal on the powder surface. The molybdenum disulfide powder was plated at 72 ° C. using an electroless copper plating solution KC-500, but a copper plating film could hardly be formed by the electroless copper plating.

Example 6 Silane coupling agent which is an equimolar reaction product of 50 g of magnesium oxide powder having an average particle diameter of 100 microns with imidazole and γ-glycidoxypropyltriethoxysilane
0.2 g was dissolved in 100 ml of 2-propanol solution at room temperature.
Stir for 0 minutes. After filtration of the solvent 2-propanol 1
Dry at 05 ° C for 30 minutes. Next, the magnesium oxide powder was stirred at room temperature for 20 minutes in 100 ml of a Pd-activating solution CG-535A, and the activated solution was filtered off, washed with 100 ml of deionized water, and dried at 105 ° C. for 30 minutes. Then, the precious metal activation treatment was performed on the powder surface. This magnesium oxide powder was plated at 72 ° C. using an electroless copper plating solution KC-500. A uniform copper plating film could be formed on the powder surface by electroless copper plating of only 1 wt%, and the underlying magnesium oxide could be completely covered.

Example 7 25 g of natural graphite powder having an average particle size of 100 microns was added to 2-ethyl-
The mixture is stirred at room temperature for 10 minutes in a 50 ml ethanol solution in which 0.1 g of a silane coupling agent which is an equimolar reaction product of 4-methylimidazole and γ-glycidoxypropyltrimethoxysilane is dissolved. After distilling off the solvent, 2-propanol, the mixture is dried at 105 ° C. for 30 minutes. Next, this graphite powder was stirred for 20 minutes at room temperature in 100 ml of Pd activation treatment solution CG-535A,
The activated liquid was filtered off, washed with 50 ml of deionized water and dried at 105 ° C. for 30 minutes to activate the noble metal on the powder surface. This graphite powder is electroless copper plating solution KC
Plating was performed at 72 ° C. using −500. A uniform copper plating film could be formed on the powder surface by electroless copper plating of 6wt%. Similarly, when the graphite powder that has been activated with a noble metal is immersed in the electroless nickel plating solution Nicom 7N at 80 ° C for 4 minutes, the electroless nickel plating precipitates almost uniformly on the surface, and the powder color changes from black to gray. The underlayer was completely covered with nickel.

Example 8 50 g of SiC powder having an average particle size of 70 microns was mixed with imidazole and γ.
-0.2 g of silane coupling agent, which is an equimolar reaction product with glycidoxypropyltrimethoxysilane, was dissolved
Stir in 100 ml of methanol solution for 10 minutes at room temperature. After distilling off the solvent methanol, it is dried at 105 ° C. for 30 minutes. Next, this SiC powder was added at room temperature to 100 ml of Pd activation treatment solution CG-535A.
After stirring for 20 minutes, the activated solution is filtered and
After washing with 0 ml of deionized water and drying at 105 ° C. for 30 minutes, the surface of the powder was activated with a noble metal. This SiC powder was plated at 72 ° C. using an electroless copper plating solution KC-500.
A uniform copper plating film can be formed on the powder surface by electroless copper plating of only 1 wt%, and it becomes a complete copper-colored powder.
The SiC could be completely covered.

Comparative Example 8 50 g of SiC powder having an average particle size of 70 microns was subjected to Pd activation treatment liquid CG
After stirring in 100 ml of -535A at room temperature for 20 minutes, the activated solution was filtered, washed with 100 ml of deionized water, and then washed with 105 ml of deionized water.
After drying at 30 ° C. for 30 minutes, the surface of the powder was activated with a noble metal. This SiC powder was treated with an electroless copper plating solution KC-500 for 72 hours.
Plating was performed at ℃. Electroless copper plating could be formed on the powder surface, but could not cover more than 20% of the SiC powder.

Example 9 50 g of zirconium oxide powder having an average particle size of 30 microns
-Stir at room temperature for 10 minutes in a 100 ml methanol solution in which 0.2 g of a silane coupling agent, which is an equimolar reaction product of methylimidazole and γ-glycidoxypropyltriethoxysilane, is dissolved. After distilling off the solvent methanol, 10
Dry at 5 ° C for 30 minutes. Next, the zirconium oxide powder was stirred for 20 minutes at room temperature in 100 ml of a Pd activation treatment solution CG-535A, and the activation treatment solution was filtered, washed with 100 ml of deionized water, and dried at 105 ° C. for 30 minutes. The precious metal activation treatment was performed on the powder surface. When this zirconium oxide powder was immersed in the electroless nickel plating solution Nicom 7N at 80 ° C. for 4 minutes, the electroless nickel plating was deposited almost uniformly on the surface of the zirconium oxide, and the base was completely covered.

Example 10 About 1 g of Teflon (trade name) yarn having a diameter of 0.3 mm was used in an amount of 0.02 g of a silane coupling agent which is an equimolar reaction product of imidazole and γ-glycidoxypropyltrimethoxysilane.
Is immersed in a 250 ml ethanol solution at room temperature for 10 minutes. After distilling off the solvent ethanol, it is dried at 105 ° C. for 30 minutes. Next, the yarn was immersed in 50 ml of a Pd activation treatment solution CG-535A at room temperature for 20 minutes, and the activation treatment solution was filtered, washed with 50 ml of deionized water, and dried at 105 ° C. for 30 minutes. Surface was subjected to a noble metal activation treatment. When this Teflon yarn was immersed in the electroless nickel plating solution Nicom 7N at 80 ° C. for 4 minutes, the electroless nickel plating was uniformly deposited on the surface of the yarn, and completely covered the base, and the yarn became gray.

INDUSTRIAL APPLICABILITY As described above, according to the electroless plating method using the novel metal plating pretreatment agent of the present invention, the electroless plating method is suitable even for mirror-like objects and powders that are difficult to adapt with the conventional method. Plating can be performed, and there is no restriction on the property and shape of the object to be plated.

Claims (5)

(57) [Claims] 1. A metal plating pretreatment agent comprising a silane coupling agent obtained by reacting an azole compound having an active functional group capable of forming a complex with a noble metal ion with an epoxysilane compound. 2. An object to be plated, which is surface-treated with a silane coupling agent obtained by reacting an azole compound having an active functional group which forms a complex with a noble metal ion and an epoxysilane compound, with a solution containing a noble metal ion. A metal plating method characterized by performing electroless plating after the treatment. 3. The metal plating method according to claim 2, wherein the azole compound is an imidazole. 4. The metal plating method according to claim 2, wherein the noble metal ion is a palladium ion. 5. The metal plating method according to claim 2, wherein the electroless plating is a body or nickel.