JP6779136B2 - Surface treatment agent for metal substrates - Google Patents

Description

The present invention relates to a surface treatment agent for a metal substrate (hereinafter, also simply referred to as a “surface treatment agent”). Specifically, an ink is applied onto a metal substrate by an inkjet method to form a high-definition pattern coating film. The present invention relates to a surface treatment agent for a metal substrate used for the purpose and a method for forming a pattern coating film using the same.

Generally, a metal pattern is obtained by forming an etching resist pattern on a metal base material such as a copper plate and removing unnecessary portions by etching. For example, a copper circuit of a printed wiring board can be obtained by forming an etching resist of a desired pattern on a copper-clad base material and etching it. In addition, the solder resist on the printed wiring board is formed on the copper circuit to protect the circuit and prevent solder bridges.

Etching resists and solder resists are generally formed by a printing method using a screen plate or the like, or a photolithography method in which exposure and development steps are performed. In addition, since it is possible to handle small lot production and omit plates and photomasks, a method of drawing a pattern of an etching resist or a solder resist by an inkjet method has also been proposed.

For example, Patent Document 1 proposes a method of drawing an etching resist by an inkjet method, and Patent Document 2 proposes a method of drawing a solder resist by an inkjet method. However, the viscosity of the resist ink that can be applied to the inkjet method is very low, and when it is applied to a non-absorbent base material such as the surface of copper, bleeding occurs.

Therefore, for example, in Patent Document 3, a method of heating or cooling a base material to increase the viscosity of ink after printing with ink is used, and in Patent Document 4, a partition wall is formed by a letterpress reversal printing method and an inkjet method is used inside the partition wall. Each method of injecting ink has been proposed. Further, as in Patent Document 5, there has been proposed an apparatus in which an ultraviolet irradiation means is provided in the vicinity of an injection nozzle by using an ultraviolet curable ink. This technique can reduce bleeding by curing the ink after coating in a short time, and is used for printed wiring boards.

Japanese Unexamined Patent Publication No. 56-263845 Japanese Unexamined Patent Publication No. 7-263845 JP-A-5-309831 Japanese Unexamined Patent Publication No. 2011-171453 Japanese Unexamined Patent Publication No. 2-283452

When applying ink using the inkjet method, if the object to be coated is a base material that does not have absorbency such as a metal surface, as described above, an apparatus as described in Patent Document 5 is used. If used, it is possible to reduce bleeding.

However, the effect is not sufficient, and as a result, a satisfactory high-definition pattern coating film cannot be obtained, and a conventional printing method using a screen plate or the like or a photolithography method in which an exposure and development process is performed. Compared with, only the ones with inferior drawing quality were obtained. In particular, in the case of marking ink, this problem was remarkable.

Therefore, an object of the present invention is a surface treatment agent used for pretreatment of a metal base material, which can draw a high-definition pattern coating film without bleeding when forming a pattern coating film by an inkjet method. , And a method for forming a pattern coating film.

As a result of diligent studies to solve the above problems, the present inventors have obtained a surface treatment agent comprising a composition containing phosphoric acid, a surfactant excluding a metal salt of a fatty acid, and water. We have found that the above problems can be solved, and have completed the present invention.

That is, the surface treatment agent for a metal base material of the present invention is a surface treatment agent for a metal base material used prior to forming a pattern coating film by applying ink on the metal base material by an inkjet method. It is characterized by comprising a composition containing phosphoric acid, a surfactant excluding a metal salt of a fatty acid, and water.

Further, the method for forming a pattern coating film of the present invention is to apply an ink by an inkjet method onto a metal substrate surface-treated with the above-mentioned surface treatment agent for a metal substrate of the present invention to form a pattern coating film. It is characterized by.

According to the surface treatment agent for a metal substrate of the present invention, when a pattern coating film is formed by using an inkjet method, it is possible to draw a high-definition pattern coating film without bleeding. Further, when a circuit is formed by etching a metal substrate via an etching resist, it is necessary to peel off the etching resist from the metal substrate. According to the surface treatment agent for a metal substrate of the present invention, this is required. It has the effect of shortening the peeling time.

Hereinafter, embodiments of the present invention will be described in detail.
The surface treatment agent for a metal base material of the present invention is used for pretreatment prior to forming a pattern coating film by applying ink on a metal base material by an inkjet method, and is used for phosphoric acid and. It is important that the composition comprises a surfactant excluding the metal salt of the fatty acid and water.

As described above, when ink is applied to a metal substrate such as copper that does not have absorbency by an inkjet method, the conventional method sufficiently suppresses bleeding to obtain a high-quality high-definition pattern. I couldn't get it. As a result of diligent studies, the present inventors have found that the cause is that the surface energy of the metal base material is too large compared to the surface energy of the ink. As a result of further studies, the present inventors have been able to adjust the surface energy, that is, the surface tension of the metal substrate by pretreating it with a specific composition, whereby the ink is ink by an inkjet method. It has been found that it is possible to draw a high-definition pattern coating film without bleeding in the case of coating. Further, by performing the pretreatment with the surface treatment agent of the present invention, the etching resist can be easily peeled off from the metal substrate, and the peeling time can be shortened. Here, the surface treatment agent of the present invention requires water because phosphoric acid is an unstable crystal by itself, and it is difficult to mix it with a surfactant unless it contains water. is there.

(phosphoric acid)
The phosphoric acid used in the surface treatment agent of the present invention is not particularly limited, and any phosphoric acid can be used.

(Surfactant)
As the surfactant used in the surface treatment agent of the present invention, known and commonly used surfactants can be used as long as they exclude the metal salt of the fatty acid. For example, an anionic surfactant, a nonionic surfactant, and a cation. Examples include system surfactants and amphoteric surfactants.

Examples of anionic surfactants include sodium lauryl sulfate, sodium alkyl sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl ether phosphate, and polyoxyethylene alkyl phenyl ether. Phosphate, alkyl sulphate triethanolamine, polyoxyethylene alkyl ether sulphate triethanolamine, sodium 2-ethylhexyl sulphate, sodium di-2-ethylhexyl sulfosuccinate, sodium linear alkylbenzene sulfonate, linear alkylbenzene sulfone Acid, fatty acid sodium methyl taurate, coconut oil fatty acid sodium methyl taurate, N-decanoyl-N-methyl taurate sodium, α-sulfo fatty acid methyl ester sodium, fatty acid amide ether sulfate sodium, N-oleyl-N-methylglycine , N-lauroyl-N-methylglycine sodium, polyoxyethylene polycyclic phenyl ether sulfate ester salt, polyoxyethylene aryl ether sulfate ester salt, polyoxyalkylene alkyl ether phosphate ester, sodium polyacrylate, sulfonate and the like. ..

Nonionic surfactants include polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, polyoxyethylene stearyl ether, polyoxyethylene isodecyl ether, polyoxyethylene-2-ethylhexyl ether, and polyoxy. Ethylene branched alkyl ether, polyoxyethylene polyoxypropylene alkyl ether, polyoxypropylene stearyl ether, polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene monoolate, sorbitan monocaprilate, sorbitan monolaurate, Solbitan Monomillistate, Solbitan Monopalmitate, Solbitan Monostearate, Solbitan Monooleate, Solbitan Sesquiolate, Solbitan Triolate, Polyoxyethylene Solbitan Monolaurate, Polyoxyethylene Solbitan Monostearate, Polyoxyethylene Solbitan Monooleate, Ethylene glycol distearate, polyethylene glycol distearate, polyethylene glycol dioleate, polypropylene glycol distearate, polypropylene glycol disuccinate, glycerylol monostearate, glycerylol monomillistate, polyoxyethylene palm fatty acid glyceryl, polyoxy Ethylene-hardened castor oil, polyoxyethylene triisostearic acid, polyoxyethylene tetraoleic acid, polyglycerin oleic acid ester, polyglycerin lauric acid ester, polyglycerin stearic acid ester, N-hydroxyethyllaurylamine, polyoxyethylene laurylamine, Polyoxyethylene polyoxypropylene laurylamine, polyoxyethylene alkylamine, polyoxyethylene stearylamine, polyoxyethylene oleylamine, polyoxyethylene beef alkylamine, polyoxyethylene alkylpropylene diamine, coconut fatty acid diethanolamide, bovine fatty acid diethanolamide, Lauric acid diethanolamide, coconut fatty acid diethanolamide, oleic acid diethanolamide, coconut fatty acid monoethanolamide, lauric acid isopropanolamide, polyoxyethylene fatty acid monoethanolamide, polyoxyaryl ether, polyoxyalkylenearyl ether, polyoxyethylene Examples thereof include cumylphenyl ether, polyoxyethylene polyoxypropylene block polymer, polyoxyethylene oleate, and polyoxyethylene alkylamine ether.

Cationic surfactants include tetradecylamine acetate, octadecylamine acetate, lauryltrimethylammonium chloride, cetyltrimethylammonium chloride, dioctyldimethylammonium chloride, dodecyltrimethylammonium chloride, coconut alkyltrimethylammonium chloride, hexadecyltrimethylammonium chloride. , Beef Acetate Alkyltrimethyl-Ammonium Chloride, Octadecyltrimethylammonium Chloride, Behenyltrimethylammonium Chloride, Didecyldimethylammonium Chloride, Dihardened Beef Alkyldimethylammonium Chloride, Dioleyldimethylammonium Chloride, Palm Alkyldimethylbenzylammonium Chloride, Tetradecyldimethylbenzylammonium Examples thereof include chloride, N, N-diacyloxyethyl-N-hydroxyethyl-N-methylammonium methyl sulfate, 1-methyl-1-hydroxyethyl-2-beef alkylimidazolium chloride, alkylammonium hydride and the like.

As amphoteric surfactants, coconut oil dimethyl betaine, coconut oil fatty acid amide propyl dimethylaminoacetic acid betaine, palm kernel oil fatty acid amide propyl dimethylamino acetate betaine, lauryl dimethyl amino acetate betaine, stearyl dimethyl amino acetate betaine, lauric acid amide propyl dimethyl Aminoacetate betaine, dodecylaminomethyldimethylsulfopropyl betaine, octadecylaminomethyldimethylsulfopropyl betaine, cocamidopropyl hydroxysultaine, 2-alkyl-N-carboxymethyl-N-hydroxyethyl-imidazolium betaine, laurylaminodiacetate mono Examples thereof include sodium, lauryldiaminoethylglycine sodium, lauroylmethylalanine sodium, sodium lauroylglutamate, potassium lauroylglutamate, lauroylmethyl-β-alanine, lauryldimethylamine N-oxide, and oleyldimethylamine N-oxide.

Fatty acids such as potassium myristate, potassium laurate, potassium coconut fatty acid, potassium palmitate, potassium stearate, potassium oleate, sodium coconut fatty acid, sodium myristate, sodium stearate, sodium oleate, etc., even if they are surfactants. The metal salt of is not effective in the present invention. Here, in the present invention, the metal salt of a fatty acid means a fatty acid forming a salt with the metal. This is because when a metal salt of a fatty acid is used as a surfactant, solid content is precipitated when the metal salt of the fatty acid and phosphoric acid are mixed, and the function as a surfactant cannot be achieved.

In the composition used as the surface treatment agent of the present invention, the mass ratio of phosphoric acid to the surfactant can be preferably 100: 0.1 to 100: 50, and more preferably 100: 0. .2 to 100:20. By setting the ratio of each component within the above range, it is possible to more reliably obtain a high-definition pattern coating film without bleeding. On the other hand, the minimum amount of water to be blended may be an amount in which phosphoric acid is dissolved, and the maximum amount can be an amount in which the concentration of the surfactant does not become 0.0001% by mass or less, and more preferably. The amount is such that the concentration of the surfactant is 0.001 to 0.1% by mass.

In the treatment of the metal base material with the surface treatment agent of the present invention, whether the surface treatment agent is applied to the surface of the metal base material as it is or in a state of being diluted with water or various water-soluble solvents at an arbitrary concentration. Alternatively, it can be carried out by dipping, washing if necessary, and drying.

(Metal base material)
Examples of the metal base material include metal foils such as copper, iron, tin, aluminum, silver, stainless steel, brass, nickel, titanium, and alloys thereof, which are usually used for printed wiring boards. In particular, the present invention applies ink to a copper foil as a metal base material disposed on a printed wiring board by an inkjet method to form a coating film of a resist ink for a printed wiring board. It is useful. Above all, it is particularly useful when forming a coating film of an etching resist ink or a solder resist ink.

The base material to which the etching resist ink is applied is an insulating sheet formed of a metal foil such as copper as a metal base material. The insulating sheet is generally a glass cloth, a non-woven fabric, paper or the like impregnated with an epoxy resin or a phenol resin and cured, but a non-impregnated sheet can also be selected depending on the intended use. For example, epoxy resin, melamine resin, phenol resin, urea resin, unsaturated polyester resin, heat-curable resin such as polyimide, polyethylene, polypropylene, polystyrene, ABS resin, vinyl chloride resin, methyl methacrylate resin, nylon, polyester resin, fluorine. Thermoplastic resins such as resins, polycarbonates, polyacetals, polyamides, polyphenylene ethers, acrylate polyarylates, polysulfones, polyether sulfone, polyphenylene sulphide, polyether ether ketones, thermoplastic polyimides, polyetherimides, liquid crystal polymers, silicon nitride Ceramics such as a sintered body, a sialone sintered body, a silicon carbide sintered body, an alumina sintered body, and an aluminum nitride sintered body can be preferably used. As a method for forming a metal foil on such a sheet, a method of attaching a single metal foil by heat fusion or an adhesive, a method of forming a seed layer by a plating method, or a thin-film deposition method is used. There are methods for forming and the like, and they may be combined to form.

As the base material to which the solder resist ink is applied, the same base material as that used for the etching resist ink can be used, and the etching resist is formed on an insulating sheet on which a metal foil such as copper is formed as a metal base material. A circuit pattern formed by applying ink and an etching method, or a circuit pattern printed directly with a metal paste or the like can be used.

In the method for forming a pattern coating film of the present invention, an ink is applied by an inkjet method on a metal substrate surface-treated with the above-mentioned surface treatment agent to form a pattern coating film.

As described above, in the present invention, the surface tension of the metal base material can be adjusted by subjecting the metal base material to a surface treatment using the above-mentioned surface treatment agent. Specifically, in the present invention, the surface tension of a metal base material can be reduced by subjecting it to a surface treatment. Normally, the metal substrate to be coated must have a higher surface energy (surface tension) than the ink to be coated. This is because if the metal base material to be coated has a lower surface energy (surface tension) than the ink to be coated, repelling and non-adhesion are violently generated, and the coating film cannot be formed. However, in the case of the immediate curing type inkjet, it was found that even if the surface energy of the metal substrate is lower than that of the ink to be applied to some extent, good results are obtained.

In the present invention, specifically, for example, the difference between the wetting index of the metal substrate and the surface tension of the ink can be +2 or less, preferably -13 or more and +2 or less, and more preferably -12. More than +2 or less. Here, in the present invention, the difference between the wetting index of the metal substrate and the surface tension of the ink is determined from the wetting index of the metal substrate (equivalent to the surface tension (unit: mN / m)) to the surface tension of the ink ( Unit: mN / m) is subtracted. When the difference between the wetting index of the metal base material and the surface tension of the ink is +2 or less, it is preferable in that both lines and characters become clearer. It should be noted that it is difficult to adjust the surface tension of the metal base material to bring it closer to the metal base material because the surface tension of the metal base material is generally too large as compared with the ink. Because. As a specific method of surface treatment on a metal base material, in addition to using the above-mentioned surface treatment agent of the present invention, for example, a method of applying a metal surface conditioner to the surface of a metal base material can be mentioned.

(ink)
As the ink used in the present invention, at least one of a solder resist ink and an etching resist ink can be used.

As the etching resist ink, any composition having a low viscosity that can be applied by an inkjet method and that can be peeled off after etching can be used, but a composition that is cured by ultraviolet rays after coating and can be peeled off with an alkaline aqueous solution. Is desirable. Such a composition can be produced by a combination of a carboxyl group-containing monomer, a monofunctional monomer, a polyfunctional monomer, a photopolymerization initiator, and other optional components.

Examples of the carboxyl group-containing monomer include acid-modified epoxy (meth) acrylate, (meth) acrylic acid, (meth) acrylic acid dimer, crotonic acid, α-chloroacrylic acid, silicic acid, maleic acid, fumaric acid, and itaconic acid. Citraconic acid, mesaconic acid, β-carboxyethyl (meth) acrylate, ω-carboxypolycaprolactone mono (meth) acrylate, monosuccinate [2- (meth) acryloyloxyethyl], maleate mono [2- (meth) acryloyl Oxyethyl], 2-acryloyloxyethyl succinate, a reaction product of phthalic acid anhydride and hydroxyethyl (meth) acrylate, a reaction product of hexahydrophthalic anhydride and hydroxyethyl (meth) acrylate, and the like.

Examples of the monofunctional monomer include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, and 2-hydroxyethyl (meth) acrylate. , (Meta) acrylates such as hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, glycidyl methacrylate, γ-butyrolactone acrylate, γ-butyrolactone methacrylate, and acryloyl morpholine.

Examples of the polyfunctional monomer include polyethylene glycol diacrylates such as diethylene glycol diacrylates, triethylene glycol diacrylates and tetraethylene glycol diacrylates, polyurethane diacrylates and their corresponding metaacrylates, pentaerythritol triacrylates and triacrylates. Methylolpropane triacrylate, trimethylolmethane triacrylate, ethylene oxide-modified trimethylolpropane triacrylate, propylene oxide-modified trimethylolpropane triacrylate, epichlorohydrin-modified trimethylolpropane triacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, tetramethylolmethanetetra Examples thereof include acrylate, ethylene oxide-modified phosphoric acid triacrylate, epichlorohydrin-modified glycerol triacrylate, dipentaerythritol hexaacrylate, dipentaerythritol monohydroxypentaacrylate, bisphenol full orange hydroxy acrylate, and bisphenol full orange methacrylate.

Examples of the photopolymerization initiator include benzoin and benzoin alkyl ethers such as benzoin, benzoin methyl ether, benzoin ethyl ether, and benzoin isopropyl ether; acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-. Acetphenones such as phenylacetophenone and 1,1-dichloroacetophenone; 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-( Aminoacetophenones such as 4-morpholinophenyl) -butane-1-one, N, N-dimethylaminoacetophenone; anthraquinones such as 2-methylanthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone and 1-chloroanthraquinone. Thioxanthones such as 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2,4-diisopropylthioxanthone; Ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; 2,4,5-tria Lille imidazole dimer; riboflavin tetrabutyrate; thiol compounds such as 2-mercaptobenzoimidazole, 2-mercaptobenzoxazole, 2-mercaptobenzothiazole; 2,4,6-tris-s-triazine, 2,2,2 Organic halogen compounds such as -tribromoethanol and tribromomethylphenylsulfone; benzophenones such as benzophenone and 4,4'-bisdiethylaminobenzophenone or xanthones; 2,4,6-trimethylbenzoyldiphenylphosphine oxide and the like.

The solder resist ink can be used as long as it has a low viscosity that can be applied by an inkjet method, can be cured by heat or ultraviolet rays, and has heat resistance after curing, but it is cured by ultraviolet rays after application. After that, a composition that is further cured by heat is desirable. Such a composition can be produced by combining various arbitrary components with a curing agent such as an epoxy compound or an isocyanate compound in addition to a combination of various monomers used for the etching resist ink.

Hereinafter, the present invention will be described in more detail with reference to examples.

(Preparation of base material for coating)
Each of the high-concentration solutions of Examples 1 to 10 and Comparative Examples 1 to 13 was prepared with the blending amounts (parts by mass) shown in Tables 1 to 3 below, diluted 50-fold with water, and used as a surface treatment agent. did. As a base material, a FR-4 copper-clad laminate (copper thickness 18 μm) having a size of 150 × 90 mm was used, the surface was roughened by scrub polishing, and this was immersed in each surface treatment agent at 23 ° C. for 60 seconds. Then, it was washed with running water and dried to obtain a base material for each coating. The wetting index of the untreated substrate is considered to be about several hundred to 1,000. The wettability index of the base material after the surface treatment is shown in Tables 4 to 7 below.

Here, the wetting index is measured according to the method described in JIS K6768, and the wetting index 30 to 42 is obtained by using a wet tension test mixture manufactured by Wako Pure Chemical Industries, Ltd., and the wetting index is 28 to 29. Up to this point, a mixed solution containing pure water, ethanol, and, in some cases, a fluorine-based surfactant was used, and the surface tension was measured and adjusted with a dynometer manufactured by BYK-GARDNER. The value of the wetting index is the same as the surface tension (unit: mN / m).

＊１）ノニオン系界面活性剤１：ポリオキシエチレンラウリルエーテル
＊２）ノニオン系界面活性剤２：ソルビタンモノオレート
＊３）カチオン系界面活性剤１：ラウリルトリメチルアンモニウムクロライド
＊４）カチオン系界面活性剤２：ジオクチルジメチルアンモニウムクロライド
＊５）アニオン系界面活性剤１：ポリオキシエチレンアルキルフェニルエーテルフォスフェート
＊６）アニオン系界面活性剤２：アルキル硫酸エステルトリエタノールアミン
＊７）両性界面活性剤１：２−アルキル−Ｎ−カルボキシメチル−Ｎ−ヒドロキシエチル−イミダゾリウムベタイン
＊８）両性界面活性剤２：ラウリルジメチルアミンＮ−オキシド
＊９）脂肪酸の金属塩１：ステアリン酸カリウム
＊１０）脂肪酸の金属塩２：ミリスチン酸ナトリウム

* 1) Nonionic surfactant 1: Polyoxyethylene lauryl ether * 2) Nonionic surfactant 2: Solbitan monooleate * 3) Cationic surfactant 1: Lauryltrimethylammonium chloride * 4) Cationic surfactant 2: Dioctyldimethylammonium chloride * 5) Anionic surfactant 1: Polyoxyethylene alkylphenyl ether phosphate * 6) Anionic surfactant 2: Alkyl sulfate ester triethanolamine * 7) Amphoteric surfactant 1: 2 -Alkyl-N-carboxymethyl-N-hydroxyethyl-imidazolium betaine * 8) Amphoteric surfactant 2: Lauryldimethylamine N-oxide * 9) Metallic salt of fatty acid 1: Potassium stearate * 10) Metallic salt of fatty acid 2: Sodium myristate

(Preparation of etching resist ink)
4-Hydroxybutyl acrylate 20 g, isobolonyl acrylate 20 g, 2-acryloyloxyethyl succinate 30 g, γ-butyrolactone methacrylate 15 g, pentaerythritol triacrylate 5 g, 2,4,6-trimethylbenzoyldiphenylphosphine oxide 5 g, phenylbis ( 2,4,6-trimethylbenzoyl) phosphine oxide (3 g) and acrylic polymerization leveling agent (0.3 g) were mixed, stirred to homogenize, filtered with 1 μm accuracy, and measured with a dynometer manufactured by BYK-GARDNER. An etching resist ink having a surface tension of 38 mN / m was obtained.

(Preparation of solder resist ink)
Trimethylolpropane triacrylate 30 g, 1,6-hexanediol diacrylate 30 g, butyl acrylate 10 g, 2,4,6-trimethylbenzoyldiphenylphosphine oxide 5 g, phenylbis (2,4,6-trimethylbenzoyl) phosphine oxide 3 g , 20 g of blocked isocyanate in which the trimmer of 1,6-hexamethylene diisocyanate is blocked with dimethylpyrazole and 0.01 g of silicone-based leveling agent are blended, stirred and homogenized, and filtered with 1 μm accuracy, manufactured by BYK-GARDNER. A solder resist ink having a surface tension of 27 mN / m was obtained by measuring with a dynometer.

(Inkjet coating)
A line having a line width of 200 μm was drawn on each coating substrate by using the etching resist ink and the solder resist ink prepared above with an inkjet printer Dimatix Materials Printer DMP-2831 manufactured by FUJIFILM Corporation. At this time, a spot-type UV irradiator was attached to the side surface of the print head, and curing was performed immediately while drawing.

(Evaluation of line width)
For each base material, the line width of the drawn line was measured, and the difference from the design value was calculated. The results of the etching resist are shown in Tables 4 and 5 below, and the results of the solder resist are shown in Tables 6 and 7 below.

(Visual evaluation)
The drawn lines were visually observed and the sharpness was evaluated. Those with clear lines and no bleeding were marked with ◯, and those with bleeding and thick lines were marked with x. The results of the etching resist are shown in Tables 4 and 5 below, and the results of the solder resist are shown in Tables 6 and 7 below.

(Removability)
For the base material coated with the etching resist, the copper foil in the portion where the resist is not patterned is etched with a ferric chloride-based etching solution, and then immersed in a 3% sodium hydroxide aqueous solution at 40 ° C. to allow a peeling time. Observed. Those that could be peeled off within 30 seconds were marked with ◯, those that could be peeled off within 45 seconds were marked with Δ, and those that took longer than that were marked with x. The results are shown in Tables 4 and 5 below.

From the results of each example shown in the above table, by using a composition in which phosphoric acid and a surfactant are used in combination as a surface treatment agent, the difference in line width from the design value is about 20 to 30 μm. It can be seen that a high-definition pattern without bleeding is obtained, and that the etching resist has improved peelability. Further, in the examples, it can be seen that the difference between the wetting index of the copper substrate and the surface tension of the ink is −10 to +2, and the lines are clear and no bleeding is confirmed.

On the other hand, Comparative Examples 1 to 8 in which the pretreatment was performed using a composition containing a surfactant and not containing phosphoric acid, and the pretreatment was performed using a composition containing phosphoric acid and a metal salt of a fatty acid. Comparative Examples 9 and 10, pretreatment was performed using a composition containing a surfactant and concentrated sulfuric acid or concentrated hydrochloric acid instead of phosphoric acid, and Comparative Examples 11 and 12, containing phosphoric acid and containing a surfactant. In Comparative Example 13 in which the pretreatment was performed using the same composition, the difference in line width from the design value exceeded 100 μm, bleeding was visually observed, and it took time to peel off the etching resist. It was. Further, in the comparative examples, the difference between the wetting index of the copper substrate and the surface tension of the ink was +3 or more, and bleeding was visually observed.

Claims (5)

A surface treatment agent for a metal substrate, which is used prior to forming a pattern coating film by applying ink on a metal substrate by an inkjet method.
And phosphoric acid, Ri Do from a composition comprising a surfactant other than a metal salt of a fatty acid, and water, and
The surface tension (unit: mN / m) of the ink was subtracted from the wetting index (same value as the surface tension (unit: mN / m)) of the metal base material surface-treated with the surface treatment agent for the metal base material. A surface treatment agent for a metal substrate, characterized in that the value is -13 or more and +2 or less . A method for forming a pattern coating film, which comprises coating an ink on a metal substrate surface-treated with the surface treatment agent for a metal substrate according to claim 1 by an inkjet method to form a pattern coating film. The method for forming a pattern coating film according to claim 2, wherein the metal base material is arranged on a printed wiring board. The method for forming a pattern coating film according to claim 2, wherein the ink is a resist ink for a printed wiring board. The method for forming a pattern coating film according to claim 4, wherein the resist ink for a printed wiring board is at least one of a solder resist ink and an etching resist ink.