JP2006225712A - Catalyst for electroless plating, and electroless plating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a catalyst for electroless plating which are excellent in terms of the cost, and capable of ensuring excellent conductivity, and to provide an electroless plating method using the catalyst. <P>SOLUTION: The catalyst for electroless plating contains alloy nano-particles consisting of metals M<SB>1</SB>and M<SB>2</SB>, wherein the metal M<SB>1</SB>is Ag, and the metal M<SB>2</SB>is one or two or more selected from a group consisting of Pd, Pt, Rh, Bi, Ru, Ni, Sn and Au. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to an electroless plating catalyst and an electroless plating method.

Conventionally, as an electroless plating catalyst used for electroless plating, a Pd catalyst made of Pd metal, Pt metal, or the like, a Pt catalyst, or the like has been used. When using such a catalyst, for example, the substrate is immersed in a stannous chloride solution, and after stannous chloride is applied on the substrate, the substrate is immersed in a palladium chloride solution, and tin and A method is generally employed in which the stannous chloride on the substrate is converted into palladium chloride by ion exchange with palladium, and then the palladium chloride on the substrate is reduced to palladium by dipping in a reducing solution. Yes. However, these metals are expensive, and there is a problem that Pd adversely affects conductivity if it is excessively deposited on the substrate.

In order to solve such a problem, an Ag catalyst made of a single Ag metal has been studied. For example, Patent Document 1 discloses a metal fine particle ink made of Ag metal fine particles having an average particle diameter of 100 nm or less, which is applied using an ink jet apparatus. However, it has been difficult to exhibit catalytic ability comparable to that of a Pd catalyst, a Pt catalyst, or the like using a single Ag metal.

As a method for solving such a problem, a method for producing alloy particles made of Pd and other metals and a method for using them as a catalyst for electroless plating are disclosed (for example, see Patent Document 2). However, such a method cannot be said to sufficiently suppress the amount of Pd used, and is not satisfactory in terms of ensuring conductivity and cost. Furthermore, there is no disclosure of details of a method for producing an alloy colloid, and there is a description that it is preferable to make the reduction rates of two kinds of metals comparable, but the specific means is not clarified. . Furthermore, in this method, single metal colloidal particles that are not alloyed are formed simultaneously, and it is substantially difficult to remove them.

JP 2002-134878 A Japanese Patent Laid-Open No. 2003-160876

The present invention has been made in view of the above-described situation, and an object thereof is to provide an electroless plating catalyst that is favorable in terms of cost and can ensure good conductivity, and an electroless plating method using the same. It is.

The present invention contains an alloy nanoparticles composed of metal _{M 1} and _{M 2,} the metal _{M 1} is Ag, the metal _{M 2} are, Pd, Pt, Rh, Bi , Ru, Ni, Sn and Au An electroless plating catalyst characterized by being one or more selected from the group consisting of:
In the alloy nanoparticles, the content of the metal M ₂ is preferably 3% by mass or less.
The alloy nanoparticles are produced by a reduction reaction after depositing metal hydroxides from a metal solution containing metal M ₁ ions and metal M ₂ ions in the presence of a polymer pigment dispersant. It is preferable that it is obtained by.
The present invention includes a step (1) of forming an alloy nanoparticle layer on a substrate using the above-described electroless plating catalyst, and a step of further electroless copper plating or electroless nickel plating of the obtained substrate ( It is also an electroless plating method characterized by comprising 2).
The step (1) is preferably performed by an ink jet method.
The present invention is described in detail below.

Electroless plating catalyst of the present invention is mainly composed of Ag, Pd, Pt, Rh, Bi, Ru, Ni, a metal _{M 2} is one or more selected from the group consisting of Sn and Au It consists of alloy nanoparticles. Here, the alloy nanoparticles have an average particle diameter of several to several tens of nanometers, and have properties different from the normal bulk state (melting point drop, nonlinear optical effect, expression of catalysis, coloration due to plasmon absorption) Etc.). In the present invention, by compounding as alloy nanoparticles, even if the amount of metal M ₂ is small, it is possible to obtain the same catalytic effect as when metal M ₂ is used alone, Catalytic performance that is overwhelmingly higher than when the main component Ag is used alone can be exhibited.

Moreover, since the said alloy nanoparticle has Ag as a main component, it can suppress cost. Furthermore, since a large amount of components such as Pd that adversely affect the conductivity does not remain on the substrate surface, the substrate using the electroless plating catalyst of the present invention can ensure good conductivity. it can.

In the alloy nanoparticles, the content of the metal M ₂ is preferably 3% by mass or less. Conventionally, while sufficiently suppressing the content of the metal M _2, although it is difficult to exhibit good catalytic ability as an electroless plating catalyst, the alloy nanoparticles of the present invention, the nanoscale metal particles surface Since different metals are compounded in a smaller scale and it is considered that highly active catalytic sites are likely to be generated, even when the content of the metal M ₂ is 3% by mass or less, sufficient catalytic ability is obtained. It can be demonstrated.

In the present invention, an alloy means that two or more kinds of metals are mixed from an atomic level to a micro level such as layered, granular or amorphous. The above mixture is not entirely in the same state, and some parts have a layered structure, and some parts have a different amorphous structure, such as an amorphous state. It is presumed that

The method for producing the alloy nanoparticles is not particularly limited. For example, after depositing metal hydroxides from a metal solution containing metal M ₁ ions and metal M ₂ ions in the presence of a polymer pigment dispersant, Examples of the method for producing the alloy nanoparticle-containing solution include a reduction reaction step. The above method is preferable from the viewpoint that a nanocatalyst particle having a highly catalytically active surface can be easily synthesized without requiring a special apparatus.

The polymer pigment dispersant is an amphiphilic copolymer having a structure containing a solvated portion and a functional group having a high affinity for the pigment surface introduced into a high molecular weight polymer. It is used as a pigment dispersant when producing a pigment paste.

The polymer pigment dispersant is considered to function to stabilize the generation of the alloy nanoparticles and the dispersion in the solvent after the generation.
The number average molecular weight of the polymer pigment dispersant is preferably 1,000 to 1,000,000. If it is less than 1000, the dispersion stability may not be sufficient, and if it exceeds 1,000,000, the viscosity may be too high and handling may be difficult. More preferably, it is 2000-500,000, More preferably, it is 4000-500,000.

The polymer pigment dispersant is not particularly limited as long as it has the above-described properties, and examples thereof include those exemplified in JP-A-11-80647. As the polymer pigment dispersant, various types can be used, but commercially available ones can also be used. The polymer pigment dispersant can be selected from those suitable for the type of alloy nanoparticle-containing solution to be produced. A polar polymer pigment dispersant is selected when the solvent is water-based, and a nonpolar polymer pigment dispersant is selected when the solvent is non-polar.

Examples of commercially available polar polymer pigment dispersants include Dispersic R, Dispersic 154, Dispersic 180, Dispersic 187, Dispersic 184, Dispersic 190, Dispersic 191 and Dispersic 192 (above Big Chemie). Manufactured by Co., Ltd.), Solsperse 20000, Solsperse 27000, Solsperse 12000, Solsperse 40000, Solsperse 41090, Solsperse HPA34 (manufactured by Lubrizol), EFKA-450, EFKA-451, EFKA-453, EFKA-4540, EFKA -4550, EFKA-1501, EFKA-1502 (manufactured by Efka Chemicals), Floren TG-720W, Floren TG-730W FLOREN TG-740W, FLOREN TG-745W, FLOREN TG-750W, FLOREN G-700DMEA, FLOREN G-WK-10, FLOREN G-WK-13E (manufactured by Kyoeisha), Dispar Aid W-30, Dispar Aid W-39 (Made by Elementis), K-SPERSE XM2311 (made by King), Neolets BT-24, Neolets BT-175 (manufactured by Zeneca), SMA1440H (made by Atchem), Orotan 731DP, Orotan 963 (Rohm and Manufactured by Hearth), Yonelin (produced by Yoneyama Chemical), Sunspearl PS-2 (produced by Sanyo Chemical), Triton CF-10 (produced by Union Carbide), Jonkrill 678, Jonkrill 679, Jonkrill 683, Jonkrill 611, Jonkrill 68 0, John Crill 682, John Crill 52, John Crill 57, John Crill 60, John Crill 63, John Crill 70, John Crill HPD-71, John Crill 62 (manufactured by Johnson Polymer), Surfynol CT-111 (Air Products) For example).

On the other hand, commercially available non-polar polymer pigment dispersants are Dispersic 110, Dispersic LP-6347, Dispersic 170, Dispersic 171, Dispersic 174, Dispersic 161, Dispersic 166, Dispersic. 182, Disperbic 183, Disperbic 185, Disperbic 2000, Disperbic 2001, Disperbic 2050, Disperbic 2150, Disperbic 2070 (manufactured by Vic Chemie), Solsperse 24000, Solsperse 28000, Solsperse 32500, Solsperse 32550, Solsperse 31845 Solsparse 26000, Solsparse 36600, Solsparse 37500, Solsparse 5100, Solsperse 38500 (manufactured by Lubrizol), EFKA-46, EFKA-47, EFKA-48, EFKA-4050, EFKA-4055, EFKA-4009, EFKA-4010, EFKA-400, EFKA-401, EFKA- 402, EFKA-403 (manufactured by Fuka Chemicals Co., Ltd.), florene DOPA-15B, florene DOPA-17, floren DOPA-22 (manufactured by Kyoeisha), disparon 2150, disparon 1210 (manufactured by Enomoto Kasei) and the like. .

In the present invention, the metal M ₁ that becomes the alloy nanoparticles is Ag, and the metal M ₂ is one or two selected from the group consisting of Pd, Pt, Rh, Bi, Ru, Ni, Sn, and Au. That's it.

The metal solution is obtained by dissolving a metal compound containing the metal M ₁ or M ₂ in a solvent described later. Here, the metal solution refers to a solution in which a compound such as a metal oxide, a metal hydroxide, or a metal salt containing an ionic metal is dissolved. Any metal compound containing the metal M ₁ or M ₂ may be used as long as it dissolves in the solvent and generates metal M ₁ ions or metal M ₂ ions.
Examples of the metal compound include silver nitrate, silver acetate, silver perchlorate (IV) when the metal is silver, and hexachloroplatinic acid (IV) hexahydrate (chloroplatinic acid) when the metal is platinum. Potassium chloroplatinate, tetrachloroauric (III) acid tetrahydrate (chloroauric acid) when the metal is gold, rhodium (III) trihydrate when the metal is rhodium Each thing can be listed.

When the metal is bismuth, examples of the metal compound include bismuth chloride, bismuth oxychloride, bismuth bromide, bismuth silicate, bismuth hydroxide, bismuth trioxide, bismuth nitrate, bismuth nitrate, bismuth oxycarbonate. Inorganic bismuth-containing compounds such as bismuth lactate, triphenyl bismuth, bismuth gallate, bismuth benzoate, bismuth citrate, bismuth methoxyacetate, bismuth acetate, bismuth formate, bismuth 2,2-dimethylolpropionate, etc. For example, an organic acid-modified bismuth that can be produced by mixing and dispersing a (basic) bismuth compound such as bismuth oxide, bismuth hydroxide, basic bismuth carbonate and an organic acid in an aqueous medium (International Publication WO99 / Organic bismuth-containing compounds such as No. 31187) It can gel. Especially, when water is included as a solvent, bismuth chloride and bismuth nitrate are preferable from the viewpoint of solubility in water.

When the metal is nickel, examples of the metal compound include nickel chloride (II), nickel chloride (II) hexahydrate, nickel bromide (II), nickel fluoride (II) tetrahydrate. , Halides such as nickel iodide (II) n hydrate; nickel nitrate (II) hexahydrate, nickel perchlorate (II) hexahydrate, nickel sulfate (II) hexahydrate, phosphoric acid Mineral acid compounds such as nickel (II) n hydrate and basic nickel carbonate (II); nickel inorganic compounds such as nickel hydroxide (II), nickel (II) oxide, nickel (III) oxide; nickel acetate (II) ) Nickel organic acid compounds such as tetrahydrate, nickel lactate (II), nickel oxalate (II) dihydrate, nickel (II) tartrate trihydrate, nickel citrate (II) n hydrate, etc. To mention Kill. The nickel organic acid compound can be prepared from, for example, basic nickel carbonate and an organic acid. Of these, highly soluble nickel acetate (II) tetrahydrate, nickel chloride (II) hexahydrate, and nickel (II) nitrate hexahydrate are preferable.
When the metal is tin, tin (II) acetate, tin (II) chloride dihydrate and the like can be mentioned.

The above-mentioned ions of Ag, Pd, Pt, Rh, Bi, Ru, Ni, Sn, and Au are metals that are reduced in the presence of the polymer pigment dispersant, so that the reduced metal is stabilized in nano size. is there. In a state where these metal ions are mixed, if the metal ions are first precipitated as metal hydroxides before being reduced, they may become composite metal hydroxides combined in a micro size. If the reduction reaction proceeds in such a situation, it is presumed that alloy nanoparticles having a high catalytic ability combined with a micro size can be obtained.

On the other hand, even when the precipitated metal hydroxides are metal hydroxides composed of a single metal species, some of the precipitated metal hydroxide particles are reduced to metal, resulting in instability. In other words, a highly active surface is formed, which becomes a reaction field, promotes the reduction reactivity of the dissolved metal ions, advances the complexation of dissimilar metals, and has a high catalytic capacity that is compounded at a micro size. It is presumed that alloy nanoparticles can be obtained.

A metal compound (a compound described above) serving as a supply source of metal M ₁ ions and metal M ₂ ions contained in the metal solution has a metal molar concentration (total amount of metals M ₁ and M ₂ ) in the metal solution of 0. It is preferably used so as to be 0.01 mol / l or more. When it is less than 0.01 mol / l, the metal molar concentration of the obtained alloy nanoparticle-containing solution is too low, which is not efficient. Preferably it is 0.05 mol / l or more, More preferably, it is 0.1 mol / l or more.

The alloy nanoparticles may contain other metals. In this case, a metal solution containing a metal compound serving as a supply source of metal M ₁ ions and metal M ₂ ions and a metal compound serving as a supply source of other metals may be used. Metal molar concentration of metal in solution of a metal compound serving as a supply source of the other metals, with respect to the metal M _1, is preferably in the range of 0.1 to 50 mass%. However, it is preferable that the upper limit of the amount of M ₂ is 3% by mass based on the total amount of other metals and metal M _1.

The solvent in the metal solution is not particularly limited as long as it can dissolve the metal compound, and examples thereof include water and organic solvents. The organic solvent is not particularly limited, and examples thereof include alcohols having 1 to 4 carbon atoms such as ethanol and ethylene glycol, alcohols including ether bonds such as 1-methoxy-2-propanol and ethoxyethanol; ketones such as acetone. And esters such as ethyl acetate. These may be used alone or in combination of two or more. When the solvent is a mixture of water and an organic solvent, the organic solvent is preferably water-soluble, and examples thereof include acetone, methanol, ethanol, ethylene glycol, and the like.

The amount of the polymer pigment dispersant used is preferably 90% by mass or less based on the total amount of the metal (the total amount of M ₁ and M ₂ ) and the polymer pigment dispersant in the metal compound. If it exceeds 90 mass%, an effect corresponding to the increment cannot be expected. More preferably, it is 60 mass% or less, More preferably, it is 40 mass% or less.

In the above-described method for producing an alloy nanoparticle-containing solution, a precipitant is added to the metal solution thus prepared to precipitate metal hydroxides. These metal hydroxides mean metal hydroxides, metal oxyhydroxides, metal oxides, and mixtures thereof, and the configuration differs depending on the types of metals M ₁ and M ₂ used. come.

A basic compound is used as a precipitant used here. By making the system basic, it is considered that metal hydroxides that are hardly soluble in a solvent are generated. Specific precipitants include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, basic alkali metal salts such as sodium bicarbonate and sodium carbonate, and water-soluble organic bases such as amine, guanidine and imidazole. Compounds and the like. These can be appropriately selected depending on the metal M ₂ used. In particular, a water-soluble aliphatic amine having a reducing action is preferably used. The amount of the precipitating agent to be added can be 0.1 to 10 times the normality of the metal salt to be precipitated.

In the method for producing the alloy nanoparticle-containing solution described above, the reduction is performed in a state where the metal hydroxides are precipitated. The reduction is performed by adding a reducing agent to the system. As described above, when the precipitate is a metal hydroxide containing metal M ₁ and metal M ₂ , alloy nanoparticles can be obtained by reducing this. Moreover, as an example in which the metal hydroxides deposited as described above are metal hydroxides composed of a single metal species and the reaction proceeds further, the metal M ₁ is Ag and the metal M ₂ is A combination of Pd can be given.

Examples of the reducing agent include amines. By using the above-mentioned amine, it is not necessary to use a reducing agent having high risk and harmfulness, and it is about 5 to 100 ° C., preferably 20 to 80 ° C. without using heating or a special light irradiation device. The metal compound can be reduced at about the reaction temperature.

The amine is not particularly limited and, for example, those exemplified in JP-A No. 11-80647 can be used. Propylamine, butylamine, hexylamine, diethylamine, dipropylamine, dimethylethylamine, diethylmethyl Amine, triethylamine, ethylenediamine, N, N, N ′, N′-tetramethylethylenediamine, 1,3-diaminopropane, N, N, N ′, N′-tetramethyl-1,3-diaminopropane, triethylenetetramine Aliphatic amines such as tetraethylenepentamine; alicyclic amines such as piperidine, N-methylpiperidine, piperazine, N, N′-dimethylpiperazine, pyrrolidine, N-methylpyrrolidine, morpholine; aniline, N-methylaniline, N, N-dimethylaniline Aromatic amines such as toluidine, anisidine, phenetidine; benzylamine, N-methylbenzylamine, N, N-dimethylbenzylamine, phenethylamine, xylylenediamine, N, N, N ′, N′-tetramethylxylylenediamine, etc. And aralkylamine. Examples of the amine include methylaminoethanol, dimethylaminoethanol, triethanolamine, ethanolamine, diethanolamine, methyldiethanolamine, propanolamine, 2- (3-aminopropylamino) ethanol, butanolamine, hexanolamine, dimethylamino. Mention may also be made of alkanolamines such as propanol. These may be used alone or in combination of two or more. Of these, alkanolamine is preferable, and dimethylaminoethanol is more preferable.

In addition to the above amines, alkali metal borohydride salts such as sodium borohydride and lithium borohydride conventionally used as reducing agents; hydrazine compounds such as hydrazine and hydrazine carbonate; citric acid; tartaric acid; malic acid; Ascorbic acid; formic acid; formaldehyde; dithionite, dithionite derivatives of sodium formaldehyde sulfoxylate (called Rongalite), zinc thionite and sulfoxylate derivatives such as zinc formaldehyde sulfoxylate Can be used. Moreover, thiourea dioxide, sodium aluminum hydride, dimethylamine borane, hypophosphorous acid, and hydrosulfite can also be mentioned. These can be used alone or in combination with the above amines, but when combining an amine with citric acid, tartaric acid and ascorbic acid, each of citric acid, tartaric acid and ascorbic acid should be in the form of a salt. preferable. In addition, citric acid or a sulfoxylate derivative can be used in combination with iron (II) ions to improve reducibility. Among the other reducing agents of the amines described above, it is preferable that the reducing agent has a reducing power stronger than that of the amine if necessary. Among those having a reducing power stronger than that of amine, sodium formaldehyde sulfoxylate (Longalite) and hydrazine carbonate are preferable from the viewpoint of safety and reaction efficiency. These reducing agents can be used in combination.

The amount of the reducing agent added is preferably equal to or greater than the amount necessary to reduce the metal M ₁ ions and metal M ₂ ions contained in the metal solution. If the amount is less than this amount, reduction may be insufficient. The upper limit is not particularly defined, it is preferably not more than 30 times the amount required to reduce the metal M ₁ and M ₂ of the metal compound, and more preferably 10 times or less.
In addition to the method of chemically reducing by adding these reducing agents, a method of irradiating light using a high-pressure mercury lamp can also be used.

As a method of adding the reducing agent, when a reduction reaction is performed after metal hydroxides containing metals M ₁ and M ₂ are deposited, for example, a compound containing metal M ₁ and a compound containing metal M ₂ are used. And by adding a reducing agent to a solution obtained by dissolving the polymer pigment dispersant and a solution containing the metal M ₁ in a solution obtained by dissolving the polymer pigment dispersant and the reducing agent, and This can be done by adding a solution in which a compound containing metal M ₂ is dissolved. Also, previously advance by mixing the reducing agent polymer pigment dispersing agent, the mixture may take the form added to the solution of a compound containing compound and a metal M ₂ comprises a metal M _1. In the production of the alloy nanoparticle-containing solution, the mixed liquid of the compound containing the metal M ₁ and the compound containing the metal M ₂ and the polymer pigment dispersant may be cloudy.

As a method for adding the reducing agent, when the metal hydroxide to be precipitated contains only M ₁ out of the metals M ₁ and M ₂ , for example, a compound containing the metal M ₂ and a polymer pigment dispersant and a solution obtained by dissolving the reducing agent can be carried out by adding a solution of a compound containing a metal M _1.

By carrying out the steps described above, precipitation of metal hydroxides and a reduction reaction are carried out to obtain a solution containing alloy nanoparticles having an average particle diameter of about 5 to 100 nm.
The solution after performing the above step contains the alloy nanoparticles and the polymer pigment dispersant described above, and becomes an alloy nanoparticle-containing solution. The alloy nanoparticle-containing solution means a solution in which fine particles containing metals M ₁ and M ₂ are dispersed in a solvent and can be visually recognized as a solution. In addition, although the metal concentration of the said alloy nanoparticle containing solution can be determined by measuring with TG-DTA etc., when not measuring, use the value calculated from the compounding quantity used for preparation. It doesn't matter.

In addition to the alloy nanoparticles and the polymer pigment dispersant, the alloy nanoparticle-containing solution obtained in this way includes miscellaneous ions such as chloride ions derived from raw materials, salts generated by reduction, and in some cases. Since it contains a reducing agent and these miscellaneous ions, salts and reducing agent may adversely affect the stability of the alloy nanoparticle-containing solution, it is desirable to remove them by ultrafiltration. Ultrafiltration of the alloy nanoparticle-containing solution not only removes miscellaneous ions, salts and amines in the alloy nanoparticle-containing solution, but also removes part of the polymer pigment dispersant.

In the ultrafiltration, a substance to be separated usually has a diameter of 1 nm to 5 μm. By targeting the diameter, the polymer pigment dispersant can be removed together with the unnecessary miscellaneous ions, salt and reducing agent. If it is less than 1 nm, unnecessary components may not be eliminated without passing through the filtration membrane, and if it exceeds 5 μm, many of the alloy nanoparticles pass through the filtration membrane, and a desired alloy nanoparticle-containing solution cannot be obtained. There is a case.

The filtration membrane for ultrafiltration is not particularly limited, but usually, for example, a resin made of a resin such as polyacrylonitrile, vinyl chloride / acrylonitrile copolymer, polysulfone, polyimide, polyamide or the like is used. Of these, polyacrylonitrile and polysulfone are preferable, and polyacrylonitrile is more preferable.
The ultrafiltration filtration membrane is preferably a filtration membrane that can be back-washed from the viewpoint of efficiently washing the filtration membrane that is usually performed after the ultrafiltration.

As the membrane for the ultrafiltration, those having a fractional molecular weight of 3000 to 80000 are preferable. If it is less than 3000, unnecessary polymer pigment dispersants and the like are not easily removed, and if it exceeds 80000, the alloy nanoparticles easily pass through the filtration membrane, so that a target alloy nanoparticle-containing solution is obtained. It may not be possible. More preferably, it is 10,000 to 60000. The molecular weight cut off generally refers to the molecular weight of a polymer that passes through the pores of the ultrafiltration membrane and is excluded when the polymer solution is passed through the ultrafiltration membrane. Used to evaluate. The larger the molecular weight cut off, the larger the pore size of the filtration membrane.

The form of the ultrafiltration filtration module is not particularly limited, and examples include a hollow paper type module (also called a capillary module), a spiral module, a tubular module, a plate type module, etc., depending on the form of the filtration membrane. Is also preferably used in the present invention. Among these, since the time required for filtration can be shortened as the membrane area increases, a hollow paper type module having a compact form relative to the filtration area is preferable from the viewpoint of efficiency. Further, when the amount of the metal colloid particle solution to be treated is large, it is preferable to use one having a large number of ultrafiltration membranes to be used.

The ultrafiltration method is not particularly limited. For example, a conventionally known method is used. Usually, the obtained solution containing the alloy nanoparticles and the polymer pigment dispersant is passed through an ultrafiltration membrane. This eliminates the filtrate containing the miscellaneous ions, salts, reducing agents and polymeric pigment dispersants described above. The ultrafiltration is usually repeated until the miscellaneous ions in the filtrate are removed below the desired concentration. At that time, it is preferable to add the same amount of solvent as the amount of filtrate removed in order to keep the concentration of the alloy nanoparticle-containing solution to be treated constant. As the solvent added at this time, it is possible to replace the solvent in the alloy nanoparticle-containing solution by using a different type of solvent from that used during the reduction. For example, when the solvent of the alloy nanoparticle-containing solution to be treated is water, substitution with alcohol such as ethanol can make the drying property, wettability to the substrate, etc. excellent, while the solvent In the case where is an alcohol such as ethanol, it can be made environmentally friendly by substituting it with water.

The ultrafiltration can be performed by a normal operation, for example, a so-called batch system. This batch method is a method of adding the alloy nanoparticle-containing solution to be processed as the ultrafiltration progresses. The ultrafiltration can be further performed to increase the solid content concentration after the miscellaneous ions are removed to a desired concentration or less.

The miscellaneous ions and the reducing agent are removed from the alloy nanoparticle-containing solution by the ultrafiltration treatment. Furthermore, since a part of the polymer pigment dispersant is removed at the same time, the concentration of alloy nanoparticles in the solid content in the alloy nanoparticle-containing solution can be increased as compared with that before the treatment. In addition to the ultrafiltration, the miscellaneous ions and the reducing agent can be removed by centrifugation. Even in this case, the alloy nanoparticle concentration can be increased as compared with that before the treatment.

In addition to the ultrafiltration treatment and centrifugal separation, the miscellaneous ions and the reducing agent can be removed by removing the colorless and transparent supernatant by decantation and further washing with water. Since the oily substance thus obtained contains the solvent used in the reaction such as water, methanol and ethanol having high solubility in water and high volatility and toluene that can be azeotroped with water are used. After the addition, the sol-like alloy nanoparticles and the polymer pigment dispersant are first obtained by drying. Subsequently, an organic solvent is added to this, and it is made to melt | dissolve and an alloy nanoparticle containing solution can be obtained.

By using the above-described method for producing an alloy nanoparticle-containing solution, an alloy nanoparticle-containing solution containing alloy nanoparticles having an average of 5 to 100 nm can be obtained. The alloy nanoparticles are mixed from various atomic levels such as layered, granular, amorphous, etc., and it is presumed that the structure is different in partial portions.

The electroless plating catalyst of the present invention comprises the above-described alloy nanoparticles. Examples of the electroless plating catalyst include those obtained by diluting the alloy nanoparticles with a solvent so that the metal content is 0.1 to 30% by mass. It does not specifically limit as said solvent, For example, the solvent described by the manufacturing method of the said alloy nanoparticle containing solution can be used. The electroless plating catalyst may contain a flow characteristic adjusting agent, a surface tension adjusting agent, a viscosity adjusting agent and the like as other components.

The substrate to which the electroless plating catalyst of the present invention is applied is not particularly limited, such as plastic, paper, metal, glass, ceramic, and wood. In particular, when the substrate is a substrate as an electronic material, imide film, polyamideimide film, polyamide film, polyester film, glass-epoxy substrate, paper-phenol substrate, silicon substrate, ceramic substrate, glass substrate, etc. are specific. It is mentioned as a thing. These substrates may be washed with isopropyl alcohol or the like as necessary. When the electroless plating catalyst is applied by an ink jet method, it is preferable to form an ink jet ink receiving layer on the substrate surface.

The inkjet ink receiving layer comprises a pigment component and a binder resin component. Examples of the pigment component include synthetic silica, calcium carbonate, alumina, colloidal silica, and the like, but preferably contains silica. On the other hand, examples of the binder resin component include starch, polyvinyl alcohol, styrene-butadiene resin, polyvinyl pyrrolidone, acrylic resin, and urethane resin.

In addition to the above components, the ink-jet ink receiving layer may contain a water-proofing agent such as polyamine compounds, polyethyleneimine compounds, dicyandiamide condensates, cationized polyurethane resins, and cationized acrylic acid derivatives. It may also contain auxiliary agents such as pigment dispersants, thickeners, fluidity improvers, antifoaming agents, mold release agents, penetrants, lubricants, light stabilizers, antioxidants, preservatives, and crosslinking agents. Good.

The use of these base materials is not particularly limited, and can be suitably used for electronic materials such as formation of conductor circuits such as electrodes and wirings in semiconductor substrates, printed boards, thermal heads, electronic components, etc., and electromagnetic shielding.

The present invention includes a step (1) of forming an alloy nanoparticle layer on a substrate using the above electroless plating catalyst, and a step of further electroless copper plating or electroless nickel plating (2) It is also an electroless plating method characterized by comprising.

The step (1) is not particularly limited, and for example, the electroless plating catalyst can be performed by a conventionally known method such as spraying, spin coating, dip coating, roll coating, screen printing, or dispense printing. Although it does not specifically limit as said alloy nanoparticle layer, A sufficient catalytic effect is expressed if a film thickness is 1 micrometer or less. When the electroless plating catalyst is patterned on the substrate by inkjet, the conductive film pattern is not post-processed because the metal film is selectively formed only on the portion where the catalyst layer is formed by the electroless plating process. Can be formed.

The step (1) is preferably performed by an ink jet method in order to cope with the finer circuit in the semiconductor. The application method by the ink jet method is preferable because the drawing is performed by directly ejecting the alloy nanoparticles, so that the minimum line width that can be drawn and the minimum distance between the circuits can be set to an extremely narrow range. In particular, the alloy nanoparticles obtained by the above-described method for producing an alloy nanoparticle-containing solution have an average particle diameter of about 5 to 100 nm, and can be suitably applied by an ink jet method. As the ink jet method, any of a piezo type that discharges using a piezo element and a thermal type (bubble jet (registered trademark)) that discharges ink by heating and boiling can be used.

The step (2) is not particularly limited, and can be performed by a conventionally known method using a commercially available electroless plating solution (bath) such as a build copper bath (Okuno Pharmaceutical Co., Ltd.).

According to the present invention, it is possible to obtain an electroless plating catalyst which is favorable in terms of cost and can ensure good conductivity.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited only to these examples.

Production Example 1
(Preparation of ethanol-based silver / palladium (= 97/3) composite nanoparticle paste)
Dispersic 190 (aqueous solution of 40% active ingredient, manufactured by Big Chemie) 24.8 g and deionized water 400.0 g were taken in Kolben, and dissolved by stirring. To this was added 7.83 g of a chloropalladium acid (H ₂ PdCl ₄ ) aqueous solution (palladium content 15.22% by mass, manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.). Further, 164.1 g of 2-dimethylaminoethanol was added and stirred well. The obtained mixed aqueous solution was heated to 80 ° C. in a hot water bath.

In a container different from the Kolben, 60.64 g of silver nitrate (I) and 150.0 g of deionized water were taken. This was stirred in a 50 ° C. hot water bath to dissolve silver nitrate.
An aqueous silver nitrate solution was added to the Kolben instantaneously with stirring. The liquid turned gray in an instant. After that, it became blackish. When the liquid temperature dropped to 80 ° C., this temperature was maintained and stirring was continued for 4 hours to obtain a brown black aqueous silver / palladium composite nanoparticle paste liquid.

Next, ultrafiltration module AHP1010 (manufactured by Asahi Kasei Co., Ltd .; molecular weight cut off 50000, number of membranes used 400), magnet pump, 3 liter stainless steel cup with tube connection port at the bottom are connected by silicon tube, and ultrafiltration is performed. The device. The previous reaction solution was put in a stainless steel cup and ethanol was added. Thereafter, ultrafiltration was performed in the same manner, and when the amount of the filtrate reached 2 liters, 2 liters of ethanol was added to the stainless steel cup. Thereafter, the same operation was repeated, and it was confirmed that the filtrate had a conductivity of 6 μS / cm or less, and concentration by ultrafiltration was performed until the amount of the mother liquor became 500 ml.

Subsequently, an ultrafiltration apparatus comprising a 500 ml stainless steel cup containing mother liquor, an ultrafiltration module AHP0013 (manufactured by Asahi Kasei Corporation; molecular weight cut off 50000, number of membranes used 100), a tube pump, and an aspirator was assembled. The mother liquor obtained previously was put into this stainless steel cup and concentrated to increase the solid content concentration. When the mother liquor reached about 150 ml, the pump was stopped and the concentration was terminated to obtain an ethanol solution of silver / palladium composite nanoparticles having a solid content of 31.7%. The composition ratio of the silver / palladium alloy nanoparticle paste was silver / palladium = 97/3 (mass ratio). The average particle diameter of the silver / palladium composite nanoparticles in this solution was 27 nm. Moreover, as a result of TG-DTA measurement, the obtained ethanol-based silver / palladium composite nanoparticle paste has a metal content of 30.0% by mass, Dispersic 190 of 1.7% by mass, and ethanol of 68.3% by mass. Met.

Production Example 2
(Preparation of aqueous silver / palladium (= 97/3) composite nanoparticle paste)
Dispersic 190 (aqueous solution of 40% active ingredient, manufactured by Big Chemie) 24.8 g and deionized water 400.0 g were taken in Kolben, and dissolved by stirring. To this was added 7.83 g of a chloropalladium acid (H ₂ PdCl ₄ ) aqueous solution (palladium content 15.22% by mass, manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.). Further, 164.1 g of 2-dimethylaminoethanol was added and stirred well. The obtained mixed aqueous solution was heated to 80 ° C. in a hot water bath.

In a container different from the Kolben, 60.64 g of silver nitrate (I) and 150.0 g of deionized water were taken. This was stirred in a 50 ° C. hot water bath to dissolve silver nitrate.
An aqueous silver nitrate solution was added to the Kolben instantaneously with stirring. The liquid turned gray in an instant. After that, it became blackish. When the liquid temperature dropped to 80 ° C., this temperature was maintained and stirring was continued for 4 hours to obtain a brown black aqueous silver / palladium composite nanoparticle paste liquid.

Next, ultrafiltration module AHP1010 (manufactured by Asahi Kasei Co., Ltd .; molecular weight cut off 50000, number of membranes used 400), magnet pump, 3 liter stainless steel cup with tube connection port at the bottom are connected by silicon tube, and ultrafiltration is performed. The device. The previous reaction solution was put in a stainless steel cup and ethanol was added. Thereafter, ultrafiltration was similarly performed, and when the amount of the filtrate reached 2 liters, 2 liters of deionized water was added to the stainless steel cup. Thereafter, ultrafiltration was similarly performed, and when the amount of the filtrate reached 2 liters, 2 liters of deionized water was added to the stainless steel cup. Thereafter, the same operation was repeated, and it was confirmed that the filtrate had a conductivity of 60 μS / cm or less, and concentration by ultrafiltration was performed until the amount of the mother liquor became 500 ml.

Subsequently, an ultrafiltration apparatus comprising a 500 ml stainless steel cup containing mother liquor, an ultrafiltration module AHP0013 (manufactured by Asahi Kasei Corporation; molecular weight cut off 50000, number of membranes used 100), a tube pump, and an aspirator was assembled. The mother liquor obtained previously was put into this stainless steel cup and concentrated to increase the solid content concentration. When the mother liquor reached about 120 ml, the pump was stopped and the concentration was terminated, whereby an aqueous solution of silver / palladium composite nanoparticles having a solid content of 31.8% was obtained. The composition ratio of the silver / palladium alloy nanoparticle paste was silver / palladium = 97/3 (mass ratio). The average particle diameter of the silver / palladium composite nanoparticles in this solution was 27 nm. Moreover, as a result of TG-DTA measurement, the obtained aqueous silver / palladium composite nanoparticle paste had a metal content of 30.0% by mass, Dispersic 190 of 1.8% by mass, and water of 68.2% by mass. there were.

Example 1
A glass epoxy substrate obtained by chemically etching Cu of the copper-clad laminate was polished with sandpaper # 400 and then washed with isopropyl alcohol. A solution obtained by diluting the ethanol-based silver / palladium composite nanoparticle paste prepared in Production Example 1 with ethanol to a metal concentration of 0.5% by mass is used as a catalyst for electroless plating, and the glass epoxy substrate is used in 2 to 3 It was immersed for 2 seconds and leaned against a 70 ° gradient. Next, it was left at room temperature in a horizontal state, dried at 100 ° C. for 5 minutes, and subjected to electroless Cu plating. The drug used is a build copper bath manufactured by Okuno Pharmaceutical. The time required for forming the Cu plating layer is 3 minutes.

Example 2, Comparative Examples 1 and 2
A test plate was prepared in the same manner as in Example 1 except that the ethanol-based silver / palladium composite nanoparticle paste was changed to the alloy nanoparticles and metal nanoparticles shown in Table 1. Table 1 shows the time required to form the Cu plating layer. It is considered that the shorter the time required for forming the Cu plating layer, the higher the catalytic ability.

As shown in Table 1, the electroless plating catalytic ability of silver / palladium composite nanoparticles containing only 3% by mass of palladium in the catalyst is equivalent to that of a nanoparticle catalyst composed of 100% palladium. It was done. On the other hand, it was found that the electroless plating catalytic ability of the silver nanoparticle catalyst not containing palladium is very low.

Production Example 3 Preparation of Inkjet Silver / Palladium Nanoparticle Solution To 50 g of the aqueous silver / palladium nanoparticle paste obtained in Production Example 2, 11 g maltitol, 16 g glycerin, 3 g methyl ethyl ketone and 20 g deionized water were added to form a metal. A silver / palladium nanoparticle solution having a content of 15% by mass was prepared.

Example 3 Formation of Cu Thin Film Pattern by Selective Electroless Cu Plating on Electroless Plating Catalyst Layer Formed by Inkjet The silver / palladium nanoparticle solution obtained in Production Example 3 was obtained using a commercially available piezo ink jet printer. A linear pattern was formed on a polyester film provided with an ink jet receiving layer on both surfaces with a line width of 50 μm and a film thickness of 0.5 μm. The reproducibility of the shape and dimensions of the drawn pattern was very high. After drying at 100 ° C. for 5 minutes, by immersing in an electroless Cu plating bath, a Cu plating film having a thickness of about 5 μm is formed only on the linear pattern on which the silver / palladium composite nanoparticle catalyst is patterned, No variation in line width due to electroless plating was observed.

Example 4 Selection of Electroless Plating Catalyst Layer Formed by Inkjet Conductive Production of Cu Thin Film Formed by Electroless Cu Plating The silver / palladium nanoparticle solution obtained in Production Example 3 was converted into a commercially available thermal ink jet Solid printing with a size of 5 cm × 5 cm was performed on a polyester film provided with an ink jet receiving layer on both surfaces by a printer. The film thickness was 0.5 μm. After drying at 100 ° C. for 5 minutes, by immersion in an electroless Cu plating bath, a Cu plating film having a film thickness of about 5 μm was formed only on the solid part where the silver / palladium composite nanoparticle catalyst was patterned. . The surface resistance was measured by a Lorester EP MCP-T360 (manufactured by Mitsubishi Chemical Corporation, four-terminal four-probe method). As a result, it was about 1 mΩ / □, and good conductivity was shown with high reproducibility.

According to the present invention, an electroless plating catalyst having a catalytic ability comparable to that of using Pd alone at low cost can be obtained. The electroless plating catalyst can ensure good conductivity because Pd or the like does not remain in large amounts on the base material, and can be used for electrodes in semiconductor substrates, printed boards, thermal heads, electronic components, etc. It can be suitably applied when conducting electroless plating on the formation of conductor circuits such as wiring and electronic materials such as electromagnetic wave shields.

Claims (5)

Containing alloy nanoparticles composed of metal _{M 1} and _{M 2,}
The metal M ₁ is Ag, and the metal M ₂ is one or more selected from the group consisting of Pd, Pt, Rh, Bi, Ru, Ni, Sn, and Au. Electroless plating catalyst. The catalyst for electroless plating according to claim 1, wherein the alloy nanoparticles have a metal M ₂ content of 3% by mass or less. The alloy nanoparticles are produced by a production method comprising a step of causing a reduction reaction after depositing metal hydroxides from a metal solution containing metal M ₁ ions and metal M ₂ ions in the presence of a polymer pigment dispersant. The catalyst for electroless plating according to claim 1, which is obtained. A step (1) of forming an alloy nanoparticle layer on a base material using the electroless plating catalyst according to claim 1, 2 or 3, and the obtained base material is further subjected to electroless copper plating or electroless nickel plating. An electroless plating method comprising the step (2) of: The electroless plating method according to claim 4, wherein step (1) is performed by an inkjet method.