JPH10317153A - Photosetting primer composition for electroless plating and electroless plating method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosetting primer compsn. which makes it possible to obtain an electroless plating film having a good adhesion property even to a nonconductive base material having a smooth surface without the selection of the quality of the base material and is capable of easily dealing with partial plating as well and an electroless plating method using the same. SOLUTION: At the time of forming the electroless plating layer on the surface of the noncnductive base material for electroless plating, the photosetting primer compsn. contg. (A) (meth)acrylate derived from monohydric or polyhydric alcohol and (B) a photopolymn. initiator is applied on the base material surface and the coating film is cured by photoirradiation to form a primer layer before providing a cotalyzer and electroless plating. The treatment before plating to immerse the base material into an aq. strong alkaline soln. is then executed. In the method for partially forming the electroless plating layer on the base material surface, the coating film of the compsn. described above is cured by the photoirradiation while the parts not requiring the plating of the coating film are subjected to light shielding via a mask. The uncured coating films of the light shielding parts are removed by washing to form the primer layer. This base material is then immersed into the aq. strong alkaline soln.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a primer composition for photocurable electroless plating and an electroless plating method using the same. More specifically, the present invention is particularly useful in the field of plastic processing, for example, for the electroless plating of plastic decoration and electromagnetic wave shielding casings, printed wiring boards, and three-dimensional circuit-forming components, and the use of non-conductive substrates by light irradiation. Form a primer layer for electroless plating that does not contain catalyst or metal powder on it, perform pretreatment with a strong alkaline aqueous solution without using harmful chemicals such as chromic acid, and then perform catalyst application and electroless plating And a photocurable primer composition used for the method.

[0002]

2. Description of the Related Art As a technique for imparting conductivity to an insulating material such as plastic, there are a method of imparting conductivity to the surface and a method of rendering the plastic itself of the insulating material conductive. It has been applied to various fields such as electromagnetic wave shielding material, antistatic, image recording and the like. Techniques for imparting conductivity to the surface include a method of forming a metal film on the surface of an insulating material, such as a spray method, a chemical vapor deposition method, a vacuum vapor deposition method, a sputtering method, a plating method, and a metal spraying method, and a method of forming conductive particles. There is a method of applying or sticking a dispersed paint or film on the surface of an insulating material.
On the other hand, as a method of imparting conductivity to the insulating material itself, a method of dispersing conductive particles in the insulating material is known, a method using metal particles as the particles, a method using carbon black, and a method of plating a conductive layer on the surface. There is a method using a filled filler. In addition, recently, a binder resin, which has been considered only as a carrier for metal particles, has been developed to provide electromagnetic wave absorption characteristics.

[0003] In recent years, particularly, electromagnetic waves generated from digital circuits cause problems such as malfunction of electronic devices. Therefore, radio wave regulations have been applied, and electromagnetic wave shielding materials and methods have been actively developed. In particular, the electroless copper plating film has excellent conductivity, and has a high electromagnetic wave shielding effect.
90 m by coating a copper layer having a thickness of
It has a shielding capability of up to 100 dB, and is currently the mainstream method of shielding electromagnetic waves. Electroless plating is a method in which ions in a plating solution are reduced by the action of a reducing agent and deposited on an object to be plated without using an electric current, and are applied to the surface of a non-conductive substrate such as plastic, ceramics, or fiber. Is widely used in various fields as a plating method. Then, the surface of the non-conductive substrate on which the electroless plating is performed usually requires a catalyst providing step for generating a metal salt to be a reduction catalyst, and Pd, Pt, Au, Ag,
Metal salts such as Ir, Os, and Ru are used. The catalyst application is generally performed in two stages of a sensitizing step (sensitizing step) and an activating step (catalyzing step). In order to supply active points of the catalytic metal to the etched surface of the object to be plated. The sensitizing step is performed, for example, by applying a hydrochloric acid solution of stannous chloride, and the activating step is performed, for example, using Pd.
It is carried out by applying a solution of a salt, Au salt, Ag salt or the like.

In order to perform electroless plating on a non-conductive substrate such as plastic, a catalyst is not usually provided on the substrate as it is. Therefore, after modifying the surface of the substrate, a catalyst such as palladium is used. And metal plating. The surface modification of the substrate is performed to attach a catalyst to the substrate and to enhance the adhesion between the plating film deposited by electroless plating and the substrate by an anchor effect. As a method of etching, the surface of the base material is previously etched with an etchant (a mixed acid obtained by adding sulfuric acid or phosphoric acid to chromic acid as needed) to roughen the surface, or an etching process for further roughening the surface. Before the chemical method combined with a process of swelling with a high-temperature alkaline solvent, or ion implantation,
There is a surface roughening method using physical means such as laser irradiation, plasma irradiation, and ozone irradiation. However, in the physical surface modification, the processing equipment itself is expensive, the productivity is low and the manufacturing cost is high, and furthermore, the treatment is not limited to the surface of the base material but extends to the inside, and the processing of the base material itself is performed. There are problems such as deterioration of strength and characteristics, and it is not suitable for general use. Therefore, a chemical etching method is generally employed.

As the chemical etching method, for example, A
For resins such as BS resin (acrylonitrile-styrene-butadiene polymer) and polyphenylene sulfide (PPS) containing filler such as glass, the resin surface is treated with a mixed solution of chromic acid and sulfuric acid at high concentration. As a result, the surface of the resin is modified into a fine irregular shape that can provide an anchor effect. Polypropylene (PP) other than ABS resin, modified polyphenylene oxide (modified PP)
O), polysulfone (PSF), polycarbonate (P
C), polyamide (PA), polyacetal (PO
M), electroless plating films are also formed on plastics such as modified polyphenylene ether (PPE) and polybutylene terephthalate (PBT). In the case of roughening plastics other than ABS resin, only an etchant is used. In this case, since the surface is not sufficiently roughened, it is necessary to perform a process of swelling with an alkaline organic solvent called pre-etching before the etching step. In addition, if the etching treatment is performed with a mixed solution of chromic acid and sulfuric acid, the resin is decomposed and destroyed. Therefore, there are materials that are etched with a mixed solution of sulfuric acid and phosphoric acid or an alkaline solution. For the above reasons, the pre-etching method differs depending on the type of plastic, so that optimal pretreatment conditions and plating conditions are set according to the type, manufacturer, and grade of plastic. However, when a plating-grade plastic that is easily etched is used for the substrate, plating can be performed, but the physical properties inherent in the plastic may be impaired.

[0006]

In order to modify the surface of a substrate in electroless plating, a chromic acid mixed solution or the like is generally used as an etching solution. Therefore, there are difficult problems such as deterioration of the physical properties of the plastic, consideration of the stability of the liquid, and management of waste liquid treatment from the viewpoint of environmental problems. After etching with chromic acid mixture, neutralization, conditioning,
A pre-dip step needs to be performed. The neutralization step is a step of reducing and removing Cr ⁶⁺ of the etching solution to Cr ³⁺ ,
If this step is inadequate, problems such as a decrease in the activation of the subsequent bath and a partial precipitation of plating will occur. The conditioning and pre-dipping processes are surface adjustment processes, and several different chemical solutions are used in combination according to a plastic base material to be plated and an etching solution thereof. The plating pretreatment process performed by chromic acid etching requires various processes such as pre-etching, etching, neutralization, conditioning, and pre-dip before the catalyst is applied, and the surface affected by the material and its processing process. Therefore, appropriate treatment must be performed in accordance with the properties of the liquid, and a single treatment liquid and treatment method cannot cope with all of them.

In the plating method in which the surface is modified using an etching solution, the entire substrate is treated and a plating film is formed on the entire surface of the plastic. It is necessary to further apply a cosmetic exterior coating on the plating film. However, recently, there are various demands such as wanting to use one side of the resin surface as a design surface as it is, uneasy about the adhesion of the coating film on the electroless plating film, and wanting only a necessary part to have an electromagnetic wave shielding effect. For this reason, many methods for performing partial plating have been proposed. As one of the partial plating methods, an etching resist film is formed on the portion where plating is not desired, and after etching with a mixed solution of chromic acid and sulfuric acid, a catalyst is applied in a predetermined process, the etching resist film is peeled off, and then electroless plating is performed. However, in terms of using a chromic acid / sulfuric acid etching solution, the solution management and environmental problems cannot be solved as in the conventional technology.

As an electroless plating method that does not use chromic acid, a method of plating on a painted film is known as a recent technique. Generally, a method of dispersing catalyst particles of palladium or silver oxide in a paint and directly depositing copper, or a method of applying a nickel-based paint and selectively plating only the applied portion is used. In the case of the former method, since the catalyst particles are dispersed in the paint, the amount of the contained catalyst increases, and in the case of the noble metal catalyst, the ratio of the catalyst cost to the plating cost increases. Further, there is a concern that the area of the catalyst contacting on the surface of the coating film is insufficient and the adhesion is poor. On the other hand, in the latter method using a coating material in which metal particles are dispersed, since the binder resin contains a large amount of metal particles, there is a concern about the adhesion to the underlying substrate.

Further, as a recent technique, a method of applying a polymer paint having no catalyst or metal particles and having a catalytic adsorption property to the surface of a base material and forming a plating film after the surface catalysis is disclosed in Japanese Patent Laid-Open Publication No. Hei.
64481, JP-A-3-1938881, JP-A-4-193
No. 103771. A method of applying a treatment liquid containing chitosan or a chitosan derivative to the surface of a non-conductive substance, forming a hydrophilic film on the surface, and then applying a catalyst is reported in JP-B-6-33461. However, these methods have problems in that the drying time is long, plating is not performed unless drying is performed sufficiently, and adhesion between the coating film and the plating film cannot be obtained. Furthermore, when a plating film is partially obtained by the above method, since it is a dry-curing type, it is necessary to completely coat the surface of a portion where the paint is not to be applied with a jig or the like before coating. If there is a slight gap between the jig and the jig at the boundary between the part and the covering part, the paint will seep out from there, so the jig to be used requires very high precision, and the electroless plating method further costs Cause.

[0010] Accordingly, an object of the present invention is to solve the above-mentioned problem of surface modification before applying a catalyst in electroless plating, to use any material for the base material and to use an etching solution containing chromic acid. There is no need to modify the surface of the material, and a primer layer can be easily formed in a relatively short time to form an electroless plating film with good adhesion even to a nonconductive substrate having a smooth surface. An object of the present invention is to provide a primer composition for photocurable electroless plating and an electroless plating method using the same. Furthermore, an object of the present invention is to eliminate the need for using an expensive precision-processed jig when performing partial plating, and to selectively form a plating film having good adhesion at a desired position on the surface of a non-conductive substrate. An object of the present invention is to provide an electrolytic plating method and a photocurable primer composition that can be suitably used for the method.

[0011]

According to the present invention, there is provided, according to the present invention, (A) a (meth) acrylic ester derived from a monohydric or polyhydric alcohol and (B)
A primer composition for photocurable electroless plating characterized by containing a photopolymerization initiator is provided. Further, according to the present invention, there is provided an electroless plating method characterized by forming a primer layer on the surface of a non-conductive substrate using the above-mentioned composition before applying a catalyst. The basic aspect is a method for forming an electroless plating layer on the surface of a non-conductive substrate, wherein (A) a (meth) acrylic acid derived from a monohydric or polyhydric alcohol is formed on the surface of the non-conductive substrate. A primer composition for photocurable electroless plating containing an ester and (B) a photopolymerization initiator is applied, and the formed coating film is cured by light irradiation to form a primer layer. It is characterized in that a catalyst pretreatment and an electroless plating are performed after performing a plating pretreatment of immersion in a metal. Further, in the method of partially forming the electroless plating layer on the surface of the non-conductive substrate, the primer composition for photocurable electroless plating is applied to the surface of the non-conductive substrate, and the formed coating film is formed. The plating unnecessary portion is cured by light irradiation while blocking light through a mask, the uncured coating film of the light blocking portion is removed by washing to form a primer layer, and then a plating pretreatment is performed by immersing the primer layer in a strong alkaline aqueous solution. After going,
It is characterized by applying a catalyst and performing electroless plating.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the electroless plating method according to the present invention, a photocurable primer composition is used instead of a conventional surface roughening treatment using an etching solution containing chromic acid prior to the application of a catalyst and the electroless plating. Is used to form a primer layer having a catalytic metal-adsorbing property.
That is, (A) a monomer, oligomer or polymer having at least one (meth) acrylate portion in a molecule derived from a monohydric or polyhydric alcohol in combination with (B) a photopolymerization initiator. After applying the photocurable primer composition for electroless plating on a non-conductive substrate, the composition is cured by irradiating ultraviolet rays, and surface treatment is performed with a strong alkaline aqueous solution. By the treatment with a strong alkaline aqueous solution, the ester bond of a monomer, oligomer or polymer having at least one (meth) acrylate portion derived from a monohydric or polyhydric alcohol in a molecule is hydrolyzed by a strong alkali. A catalyst can be provided by utilizing the fact that a hydroxyl group is generated and the oxygen atom of the negatively charged hydroxyl group and the metal serving as a catalyst are adsorbed. In addition, since the primer composition used in the present invention is photocurable, it is exposed to light while shielding it with a mask, and the unexposed portion of the non-photocured coating film is washed and removed to remove the non-conductive substrate. , A catalytic metal-adsorbing primer layer is formed only on the desired surface, and electroless plating can be performed. Therefore, partial plating can be easily performed without using an expensive jig that has been precision processed as in the related art.

Hereinafter, the primer composition for photocurable electroless plating according to the present invention will be described. First, the component (A) is derived from a monohydric or polyhydric alcohol (meth)
It is a monomer, oligomer or polymer having one or more acrylate moieties in the molecule. Examples of the (meth) acrylate (monomer, oligomer) derived from a monohydric alcohol include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n- or i-
Propyl (meth) acrylate, n-, i- or t-butyl (meth) acrylate, n- or i-amyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, lauryl (Meth) acrylate, stearyl (meth) acrylate, butoxyethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxypolyethylene glycol (meth)
Acrylates, (meth) acrylic acid esters such as tetrahydrofurfuryl (meth) acrylate,
Examples of the (meth) acrylate (monomer, oligomer) derived from a polyhydric alcohol include, for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and ethylene glycol di (meth) acrylate. , Diethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, glycerin Tri (meth) acrylate, bisphenol A glycidyl ether di (meth) acrylate, polyester (meth) acrylate and the like.

Further, as the polymer, a phenol resin,
Modified (meth) acrylates such as epoxy resin, polyurethane resin and polyester resin are exemplified. Further, alkylene oxide modified products such as ethylene oxide and propylene oxide can also be used. A high molecular weight polymer has the effect of improving film forming properties, but on the contrary, the viscosity of the composition increases, the polymer itself has poor wettability, the softening point of the cured coating film increases, and In order to prevent the surface of the obtained cured product from becoming hydrophilic, 7 parts by weight of the monomer or oligomer component
It is not preferable that the content is more than 0 parts by weight. Therefore, the ratio of (monomer component + oligomer component): polymer component is preferably from 100 to 30: 0 to 70 (weight basis). In this specification, (meth) acrylate ((meth) acrylate) refers to acrylate,
Methacrylic acid esters and their mixtures are used as a general term.

The weight-average molecular weight of the oligomer or polymer of the (meth) acrylate used in the primer composition for electroless plating of the present invention is 100 to 10, from the viewpoint of curability and washability of the uncured portion protected from light. 000 is preferable, but when the coating is performed by masking the unnecessary portion in advance as in the conventional method or when plating is performed on the entire surface, there is no need to wash, so that it functions as an electroless plating primer paint. Is not limited to this range.
In addition, since the electroless plating method of the present invention utilizes the hydrolysis action of a strong alkaline aqueous solution, the softening point of the cured coating film has a great effect on the ability to impart a catalyst. If the illuminance is too large or infrared rays (heat) are applied during light irradiation, the reaction rate increases and the softening point of the cured coating film increases, so that sufficient surface treatment may not be performed. Therefore, the softening point of the cured coating film is preferably 100 ° C. or lower, more preferably 60 ° C. or lower. When the composition contains a component having a skeleton that increases Tg, the same tendency is obtained.

The (meth) acrylate monomers, oligomers and polymers used in the present invention may contain various functional groups in the molecule. Particularly, the hydroxyl group is effective for providing a catalyst for the above-mentioned reason. It is preferable because the functional group of carboxyl group, amino group, epoxy group, etc. does not cause any problem.The functional groups of these monomers, oligomers and polymers are related to the polymerizability of the photopolymerizable unsaturated double bond. There is no. However, if it becomes too negative electrically depending on the type and amount of the functional group, in the catalyst application step,
Since it is difficult to form a palladium nucleus serving as a catalyst, it is preferable not to include a carboxyl group and an amino group.

As the photopolymerization initiator (B), various known photopolymerization initiators can be used, but those having good storage stability after blending are desirable. Such photopolymerization initiators include, for example, benzoin, benzyl, benzoin methyl ether, benzoin isopropyl ether,
Acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexylphenyl ketone, 2-methyl-
1- {1- (methylthio) phenyl} -2-morpholino-propan-1-one, 2-methylanthraquinone,
2-ethylanthraquinone, 2-amylanthraquinone, 2-aminoanthraquinone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4
-Diisopropylylthioxanthone, acetophenone dimethyl ketal, benzophenone, 4,4'-bisdiethylaminobenzophenone, and the like. These photopolymerization initiators can be used alone or in combination of two or more. Further, known or common photosensitizers such as N, N-dimethylaminobenzoic acid ethyl ester, N, N-dimethylaminobenzoic acid isoamyl ester, triethanolamine, triethylamine and Michler's ketone are used alone or in combination of two or more. Can also be used. In the composition of the present invention, a preferable blending amount of the photopolymerization initiator is 0.5 to 100 parts by weight of the component (A).
20 parts by weight, more preferably 1 to 10 parts by weight.

The primer composition for electroless plating of the present invention comprises a monomer having a photopolymerizable unsaturated group as described above,
If an oligomer or polymer is included, a compound having no photopolymerizable unsaturated bond may be included. When the compound having no photopolymerizable unsaturated double bond is a high molecular weight polymer, the photocurable polymerization is prevented, or the treatment with the alkaline aqueous solution, which is a feature of the present invention, is not effectively performed. In such a case, the catalyst solution or the plating solution may ooze out of the coating film, so that it is desirable that both are not included as much as possible.

Further, the photocurable primer composition of the present invention may contain, if necessary, a filler such as barium sulfate, silica, talc, mica, calcium carbonate, aluminum hydroxide, aluminum oxide and titanium oxide. . The filler is preferably one that imparts fine irregularities to the surface of the coating film after application, thereby obtaining an anchor effect. In addition, a sufficient surface area can be obtained by adding a filler, and plating may be precipitated without performing pretreatment with an alkaline aqueous solution. However, the plating may be derived from the monohydric or polyhydric alcohol of the present invention (meta). A) blending a filler with a composition comprising a monomer, oligomer or polymer (A) having at least one acrylate moiety in the molecule and a photopolymerization initiator (B), and performing a pretreatment with the alkaline aqueous solution of the present invention; Thus, a plating film having a sufficient adhesion can be obtained. The compounding amount of the filler is 0 to 200 parts by weight, preferably 50 to 100 parts by weight based on 100 parts by weight of the component (A).

Since the primer composition for electroless plating of the present invention is in the form of a paste, it can be screen-printed with a high viscosity, and the viscosity is adjusted to a low viscosity by diluting with an appropriate solvent.
There is no problem if UV curing is performed after coating and drying.
As an application method, any method such as brushing, spraying, dipping, and the like can be used. Examples of the solvent to be used include aliphatic hydrocarbons, aromatic hydrocarbons, halogen hydrocarbons, alcohols, aldehydes, esters, ketones, ethers, acetals, nitrogen compounds, water, and the like. It is selected from solvents that can be dried within the heat-resistant temperature range of the non-conductive substrate. Preferably, it is selected from solvents having a low boiling point and a high evaporation rate, for example, diethyl ether, dipropyl ether, methyl alcohol, ethyl alcohol, (iso) propyl alcohol,
Ethyl acetate, isopropyl acetate, methyl propionate,
Ethyl propionate, dimethyl carbonate, acetone, diethyl ketone, methyl ethyl ketone, methyl propyl ketone, methyl formate, propyl formate, isobutyl formate, ethylene dichloride, ethylene trichloride, acetylene dichloride, acetyl dichloride, propylene dichloride, ethyl bromide, diethyl carbonate, Examples include methylene chloride, butyl chloride, isoamyl chloride, ethylidene chloride, carbon tetrachloride, carbon disulfide, benzene, cyclohexane, and water. Further, as the solvent for cleaning the uncured coating film in the case of partial plating, the solvents listed above can be used. However, when partial plating is performed by a photographic method, which is a feature of the present invention, the uncured portion is washed and removed, so that it is derived from a monohydric or polyhydric alcohol (meth).
As the acrylate (A), the solvent and the solvent used for cleaning, it is necessary to use a raw material that does not dissolve the base material.

The primer composition for electroless plating of the present invention is applied to a substrate and then cured by irradiation with ultraviolet rays. Excessive curing is not preferable because the softening point of the cured product becomes high and the surface of the coating film is not sufficiently treated with a strong alkaline aqueous solution to make it difficult to provide a catalyst. Although unreacted substances may be present on the surface of the coating film due to oxygen inhibition during ultraviolet curing, they can be removed by washing with a suitable solvent or degreasing agent. When the ester bond on the surface of the coating film is hydrolyzed by the strong alkaline aqueous solution, the coating film becomes wettable.
Usually, the thickness of the coating film is preferably about 10 to 50 μm.
When the film thickness is less than 10 μm, the surface is insufficiently cured due to oxygen inhibition during ultraviolet curing, the strength of the coating film itself is insufficient, and it is difficult to obtain sufficient adhesion to the substrate during processing or after plating. May cause problems. When the coating film is thick, insufficient curing of the deep portion is likely to occur, but there is no particular problem as long as the adhesion between the base material and the coating film can be obtained. Exposure conditions are
Ultraviolet light at 80 W / cm, 3 lamps and about 5 to 60 seconds is usually sufficient. The illuminance and the exposure amount are set so that the softening point of the cured product does not become too high. For the same reason, it is desirable to avoid the heat radiated during irradiation. If partial plating is to be performed, ultraviolet light irradiation is performed in a light-shielded manner with a predetermined pattern, and then the unexposed portions are removed by washing with a solvent. Various known light sources such as a high-pressure mercury lamp, a metal halide lamp, and a xenon lamp can be used as the exposure light source.

In the electroless plating method of the present invention, a strongly alkaline aqueous solution having a pH of 13 or more, preferably 13.5 or more, such as sodium hydroxide or potassium hydroxide, is used as a surface treatment agent for the plating pretreatment. The concentration of the strong alkaline aqueous solution is not particularly limited, but it can be usually used (0.
5 to 5% by weight). At this time, the temperature of the strongly alkaline aqueous solution is set according to the softening point of the cured coating film. If the temperature is low, it is difficult to achieve sufficient hydrolysis of the component (A). The coating film obtained from the composition having high hydrophilicity and low alkali resistance shows adsorption of the catalyst and deposition of plating even when treated with an aqueous solution of sodium hydroxide at about room temperature (20 ° C.).
Usually, these coating films have poor resistance to warm water, and thus are inferior in strength of the coating films themselves, such as swelling in a plating bath, and are not preferred. For this reason, the treatment temperature of the strong alkaline aqueous solution is 40
It is preferable to use a primer composition for electroless plating that has a sufficient resistance even at a temperature of not less than ° C, whereby a good plating film can be obtained. Generally, the maximum temperature in each processing step is often limited by the heat resistance of a non-conductive substrate such as plastic. If the method of the present invention is used, it can be processed at 90 ° C. or less, which is a general heat deformation temperature of a general-purpose plastic and a low heat resistance of an ABS resin, so that a usable plastic substrate is not limited by the processing temperature. The immersion time is performed until the hydrophilicity of the coating film is obtained.
It may be immersed for about a minute.

As a well-known method, calcium carbonate is added to the coating material in order to increase the adhesion between the plating and the substrate, and calcium carbonate particles are dissolved in an aqueous acid solution from the surface of the formed coating film to roughen the surface. It is known that calcium carbonate may be blended in the primer composition for electroless plating of the present invention. In this case, a sulfuric acid aqueous solution is preferably used as a treatment liquid for performing the surface roughening step. The concentration of the aqueous sulfuric acid solution may be appropriately selected, but is usually 5 to
% By weight. If the temperature at the time of the surface roughening treatment is low, the surface is not sufficiently roughened. When calcium carbonate is added to the composition of the present invention and the plating pretreatment method of the present invention is used, the step of surface roughening with a sulfuric acid aqueous solution is always performed after the pretreatment of a strongly alkaline aqueous solution. When immersed first in a sulfuric acid aqueous solution, it is difficult to obtain the effect of surface roughening.

After the pretreatment with the strong alkaline aqueous solution as described above, sensitizing is performed with an aqueous solution of, for example, stannous chloride (SnCl ₂ ).
Activating (catalyzing) with a catalytic metal such as Pd, Ni, Cu, Fe, Co, Au, Ag, or Pt or a compound thereof completes the catalyst applying step. Depending on the base material, the catalyst application step can be performed in one step. Then, the surface to be plated with the catalyst is C
When immersed in a plating bath of u, Ni, Co, Pd, Au or an alloy thereof, the electroless plating layer can be efficiently formed by the reducing action of the active catalyst. For example, a stannous chloride solution (SnCl ₂ solution) and a palladium chloride solution (PdCl ₂ ) which are known as a catalyst for electroless copper plating.
Solution), and a primer layer which has been catalyzed by a two-stage method of sensitization with a stannous chloride solution and catalysis with a palladium chloride solution can be subjected to electroless copper or nickel plating. After performing electroless copper or nickel plating, electrolytic plating of copper, nickel, gold, or the like may be further performed. In addition, nickel or gold plating or the like can be performed on the copper plating layer according to the purpose to finish.

[0025]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but it is needless to say that the present invention is not limited to the following examples. In addition, the base material used in the following examples of electroless plating is an ABS resin plate (for example, Tough Ace R, manufactured by Tsutsunaka Plastics Industry Co., Ltd.) cut into a size of 100 × 50 mm.

Example 1 of electroless plating (Examples 1, 2, 4 to
7) Each of the primer compositions for electroless plating of Compositions 1 to 6 shown in Table 1 was diluted with ethanol, applied to a substrate with a brush, and dried in a hot-air drying oven at 50 ° C for 5 minutes. Was. Curing is performed at 80 W / c with a conveyor type ultraviolet irradiation device.
m, 3 lights, transfer speed 6 m / min. (Using a cooling device). In Examples 1 and 2, a portion where plating was not performed was shielded from light, but a light-shielding material was selected from a material that does not transmit ultraviolet rays, and a 1 × 4 cm copper plate was used in this plating example. After the exposure, washing was performed with ethanol. In Examples 4 to 7, the test piece was exposed entirely without light shielding. In each of Examples and Comparative Examples, the thickness of the primer composition for electroless plating after photocuring was between 11 and 15 μm. Each test piece was then immersed in a 1% aqueous sodium hydroxide solution at 60 ° C. for 1 minute, and then washed with water.
Subsequently, a plating catalyst application step was performed. Immerse in a sensitizer (Nikko Metal Plating Co., Ltd., tin chloride solution) for 1 minute at room temperature to sensitize, wash with water, and immerse in activator (Nikko Metal Plating, Co., Ltd., palladium chloride solution) for 1 minute Then, a palladium catalyst was applied. Next, an electroless nickel plating solution (manufactured by Meltex Co., Ltd., Melplate NI-865M 200 ml /
1, 800 ml / l of ion-exchanged water) to perform plating for 10 minutes to form a plating film having a thickness of 1 to 2 μm. The plating was not deposited on the portion where the coating was washed and light was shielded at the time of exposure, and partial plating was performed.

After each of the test pieces electrolessly nickel-plated as described above is sufficiently dried at room temperature, 25 squares are formed on the 1 × 1 cm plating surface every 2 mm in length and width, and a peeling test using a cellophane tape is performed. The initial (primary) adhesion was evaluated. Furthermore, secondary adhesion was evaluated by a peeling test using a cellophane tape under the conditions of a room temperature test, a high temperature test, and a humidity resistance test shown in Table 2, and the adhesion was good. The criteria for determining the plating adhesion are as follows. ：: A plating film was formed. Δ: A plating film was formed, but blisters occurred. ×: No plating film was formed.

Example 2 of Electroless Plating (Comparative Examples 1, 2 and 4) Except that two pretreatments were performed: one in which no treatment with an aqueous solution of sodium hydroxide was performed and the other in which it was immersed at room temperature for 5 minutes. When electroless plating was performed under the same conditions as in electrolytic plating example 1, no plating film was formed in composition-1 (comparative examples 1 and 2), and in composition-2 (comparative example 4), an aqueous sodium hydroxide solution was used. When not immersed in the plating solution, a plating film was formed, but the adhesion was insufficient.

Electroless Plating Example 3 (Example 3 and Comparative Example 3) Electroless plating was performed under the same conditions as in Electroless Plating Example 1, except that the plating time was lengthened using Composition-1 or 2. However, in Example 1, a plating film having good adhesion was formed, but in Comparative Example 3, blisters occurred in the plating film. In addition, when the plating time was long (the film thickness was about 5 μm) and the primary adhesion was evaluated in the case where the composition-2 was not immersed in the aqueous sodium hydroxide solution for pretreatment, the immersion was performed. Those who did not perform peeled off partly, but those who did immersion did not peel off.

Electroless Plating Example 4 (Comparative Example 5) Electroless plating was performed under the same conditions as in Electroless Plating Example 1 using Composition 7, and no deposition of a plating film was observed. Table 1 shows the composition of the primer composition for electroless plating used in each of the Examples and Comparative Examples, and Tables 2 and 3 show the test results of the electroless plating examples.

[Table 1]

[0031]

[Table 2]

[0032]

[Table 3]

Electroless Plating Example 5 Further, when electroless plating was performed under the same conditions as in the above electroless plating example 1 using polyester and polyimide as the base material, respectively, a good plating film could be formed. .

[0034]

As described above, in the electroless plating method of the present invention, prior to the application of the catalyst and the electroless plating,
Instead of the conventional surface roughening treatment using an etchant containing chromic acid, to form a catalytic metal-adsorbing primer layer using a photocurable primer composition, regardless of the material of the substrate to be electrolessly plated, An electroless plating film having good adhesion can be formed on a non-conductive substrate having a smooth surface as well as a substrate having a fine uneven surface. In addition, since it is not necessary to use an etching solution such as a chromic acid solution, wastewater treatment does not cause environmental pollution and does not deteriorate the physical properties of the plastic substrate. Further, since the coating is cured by light irradiation, the primer layer can be formed in a relatively short time, and the productivity of the electroless plating product can be improved.

Further, even in the case of performing partial plating, if light is shielded using a mask during light irradiation, the unexposed portions of the uncured coating film can be peeled and washed with an appropriate solvent. It can be freely and selectively formed at a required portion, and does not require expensive and expensive jigs or equipment that are precisely processed unlike a generally known partial plating method using a heat-drying paint. Therefore, partial plating can be performed at low cost. Since the electroless plating method of the present invention does not roughen the base material itself, it is particularly effective for plating on plastics whose pretreatment methods differ depending on the material, and the case of a mobile personal computer or a mobile phone performed for the purpose of electromagnetic wave shielding. It can be advantageously applied to plating on a body or the like. In addition, printed wiring boards,
It is also useful for electroless plating in various fields such as three-dimensional circuit forming parts.

Claims (3)

[Claims] 1. A photocurable electroless plating primer composition comprising (A) a (meth) acrylic acid ester derived from a monohydric or polyhydric alcohol, and (B) a photopolymerization initiator. Stuff. 2. A method for forming an electroless plating layer on a surface of a non-conductive substrate, comprising: (A) a (meth) acrylate derived from a monohydric or polyhydric alcohol on the surface of the non-conductive substrate; (B) A primer composition for photocurable electroless plating containing a photopolymerization initiator is applied, and the formed coating film is cured by light irradiation to form a primer layer, which is then immersed in a strongly alkaline aqueous solution. An electroless plating method characterized by performing catalyst application and electroless plating after performing plating pretreatment. 3. A method for partially forming an electroless plating layer on a surface of a non-conductive substrate, comprising: (A) a (meth) acrylic derivative derived from a monohydric or polyhydric alcohol on the surface of the non-conductive substrate. A primer composition for photocurable electroless plating containing an acid ester and (B) a photopolymerization initiator is applied, and cured by light irradiation while shielding a plating unnecessary portion of the formed coating film through a mask, The uncured coating film of the light-shielding portion is removed by washing to form a primer layer, which is then subjected to a plating pretreatment in which the primer layer is immersed in a strongly alkaline aqueous solution, followed by catalyst application and electroless plating. Electroplating method.