JP5445474B2 - Metal pattern manufacturing method - Google Patents

Description

  The present invention relates to a novel metal pattern manufacturing method.

  Conventionally, as a manufacturing method for forming a metal pattern, a metal-clad laminate in which a metal foil is pasted on a substrate is used. The most common method is a printed circuit board in which an adhesive layer is provided between the substrate and a metal (mainly copper) foil, and a resin imparted with adhesiveness and flexibility characteristics is employed for this adhesive layer. However, after forming this adhesive layer, a process of laminating a metal foil with a hot press, a process of forming a metal pattern with photolithography, etc. are required, which complicates the process, and a large amount of resin and metal are used in the photolithography process. Since the foil is edged, there is a problem that man-hours and costs are excessive (see, for example, Patent Document 1).

  In recent years, attention has been focused on a metal pattern forming method in which a metal pattern is directly drawn using an ink containing a so-called metal nanoparticle having an average particle size of 100 nm or less, using a screen printing method, an ink jet printing method, or the like.

  This metal pattern formation method is a method of forming a circuit by firing at a temperature of about 200 to 300 ° C. utilizing the fact that the melting point is lowered by minimizing the particle size of the metal nanoparticles. Although this technology certainly has advantages such as reduced man-hours and improved utilization efficiency of raw materials, it is difficult to completely fuse metal nanoparticles together, and in post-processing to lower the electrical resistance in the fired metal pattern The problem of severe restrictions on temperature and conditions remained.

  There is a method of forming a conductive pattern from a solution containing a reducing agent having a reducing property under heating by using a metal salt in the form of metal ions in an ink without using metal nanoparticles. However, since the complexing agent that coordinates and stabilizes the metal salt does not have sufficient performance, the reduction reaction of the metal salt tends to proceed and the solution storage stability is poor.

  On the other hand, as a means for forming and depositing metal under mild conditions, a method of forming a metal pattern by utilizing an electroless plating technique has also been proposed. For example, a method is disclosed in which a circuit pattern is formed with an ink containing a catalyst capable of electroless plating, and then a metal pattern is formed by electroless plating (for example, Patent Document 2 and Non-Patent Document 1). reference.).

  In any of the methods disclosed above, a catalyst (precursor) is contained in an ink, the ink is printed on a substrate to form a pattern, and then an activation process and electroless plating are performed to form a catalyst pattern. This is a method of forming a metal pattern on the top. However, since a metal pattern is formed by electroless plating after ink droplets are directly applied on a substrate that does not have ink absorbability at all, the adhesion between the substrate and the formed metal pattern is insufficient. It was.

  Also disclosed is a method of forming a metal pattern by electroless plating after placing a polymer layer as an anchor layer on a substrate and immersing it in a catalyst solution (see, for example, Patent Document 3).

  This method proposes a printed circuit board that is provided with adhesion and catalyst adsorptivity (electroless plating property) by causing a catalyst to be present in the surface region of the anchor layer with an aqueous catalyst solution. However, since the catalyst solution containing a large amount of expensive metal is immersed in the entire substrate and unnecessary edging treatment of the metal portion is required later, the manufacturing cost is very high.

  Further, the catalyst solubility and catalyst solution storage stability of the aqueous catalyst solution are poor, and an acid is added for the purpose of solving this problem. However, in the usage method in which the catalyst liquid is printed by the ink jet head, the solubility and the storage stability are insufficient, and there is a problem that the head member is damaged in some cases.

  Further, even if ink jet printing is performed with the above ink, repelling or wetting spread occurs, and the fine line reproducibility is particularly poor.

JP 2006-265444 A JP 7-131135 A JP 2010-138475 A

Proceedings of the 21st Electronics Packaging Society Conference p. 105 (2007)

  The present invention has been made in view of the above-mentioned problems, and the object thereof is an electroless plating property using an ink excellent in catalyst solution storage stability and head emission property in a simple and inexpensive process without a photolithography process. Another object of the present invention is to provide a method for producing a metal pattern capable of forming a metal pattern excellent in fine line reproducibility.

  The above object of the present invention is achieved by the following configurations.

1. After forming an anchor layer containing a polymer on a substrate, an ink containing an electroless plating catalyst or a precursor thereof and a solvent is applied on the anchor layer by an ink jet method, and a metal pattern is formed by electroless plating treatment. in the manufacturing method of forming metal patterns, the average concentration of the catalyst or its precursor on the surface side region of the anchor layer (the surface opposite to the contact surface of the substrate) and D _1, and the substrate of the anchor layer when the average concentration of the catalyst or its precursor was D ₂ in the interface side region, satisfy the relation of D _1> D ₂ × 5, and that the ink is a non-aqueous ink containing no water as the solvent A method for producing a metal pattern.

  2. 2. The method for producing a metal pattern according to 1 above, wherein the catalyst or a precursor thereof is a palladium metal salt.

  3. 3. The method for producing a metal pattern according to 1 or 2, wherein the polymer contained in the anchor layer is an acrylate copolymer having an acrylonitrile component.

  4). 4. The method for producing a metal pattern according to 3 above, wherein the anchor layer further contains an epoxy resin as a polymer.

  5. 5. The method for producing a metal pattern according to any one of 1 to 4, wherein the anchor layer contains a compound having an adsorptivity (coordination property) to a catalyst or a precursor thereof.

  6). Any one of 1 to 5 above, wherein after forming the anchor layer, electroless plating is performed by applying a compound having adsorptivity (coordination) to the catalyst or its precursor to the surface of the anchor layer. The method for producing a metal pattern according to claim 1.

  7). The anchor layer is composed of two layers, an upper layer and a lower layer, the upper layer is composed of a polymer having a functional group that interacts with a catalyst or a precursor thereof, and the lower layer is composed of a curable polymer. The manufacturing method of the metal pattern of any one of 1-6.

  8). 1 to 7 above, wherein the solvent contained in the ink is at least one solvent selected from glycol diesters, glycol diethers, glycol ethers / esters, tertiary alcohols, and amides. The manufacturing method of the metal pattern of any one of these.

  According to the present invention, it is possible to form a metal pattern excellent in electroless plating property and fine line reproducibility using an ink excellent in catalyst solution storage stability and head emission property in a simple and inexpensive process without a photolithography process. The manufacturing method of the metal pattern which can be provided was able to be provided.

  Hereinafter, embodiments for carrying out the present invention will be described in detail.

As a result of intensive studies in view of the above problems, the present inventor has formed an anchor layer containing a polymer on a substrate and then contains an electroless plating catalyst or a precursor thereof and a solvent on the anchor layer. In a metal pattern manufacturing method in which ink is applied by an ink jet method and a metal pattern is formed by an electroless plating process, a catalyst or a precursor thereof in a surface side region of the anchor layer (a surface opposite to the contact surface of the substrate) When the concentration of the body is D ₁ and the concentration of the catalyst or its precursor in the region of the anchor layer at the interface side with the substrate is D ₂ , the relationship of D ₁ > D ₂ × 5 is satisfied, and the ink is By using a metal pattern manufacturing method characterized in that it is a non-aqueous ink that does not contain water as the solvent, an ink having excellent catalyst solution storage properties and head emission properties can be used. Method for producing a metal pattern can be formed can and excellent metal pattern reproducibility of fine lines found that can be realized, it is up to the present invention has been completed.

  A substrate used for forming a metal pattern generally has no absorbability with respect to ink (liquid) such as insulating resin, glass or ceramic. Even if an ink containing an electroless plating catalyst is applied (printed or applied) to such a substrate to form a metal on the substrate, sufficient adhesion cannot be obtained. This is because when the metal pattern is formed on the substrate, both have almost no function of interacting with each other, so that only those having low adhesion can be obtained.

  As a result of intensive studies on the above problems, the present inventor has installed an anchor layer made of a polymer on a substrate and contains an ink containing a catalyst or a precursor thereof and a solvent (hereinafter also simply referred to as “catalyst ink”). We have found that this is achieved by forming a metal pattern by electroless plating after printing by an inkjet method.

[Catalyst concentration of anchor layer]
In the present invention, the average concentration of the catalyst or its precursor on the surface side region of the anchor layer (the surface opposite to the contact surface of the substrate) and D _1, at the interface side region of the substrate of the anchor layer when the average concentration of the catalyst or its precursor was D _2, and a satisfy the relationship D _1> D ₂ × 5.

The surface side region of the anchor layer in the present invention is the surface of the anchor layer (the surface opposite to the contact surface of the substrate) when the total thickness of the anchor layer provided on the substrate is A (μm). It means a region of up to a / 2 (μm) in the depth direction from defines the average concentration of the catalyst or its precursor in the surface side region and D _1. Similarly, the interface side region means a region from the contact surface with the substrate to A / 2 (μm) to the surface direction, defines the average concentration of the catalyst or its precursor in the interface side region and D _2.

In the present invention, as a method for measuring the concentration of the catalyst or its precursor in the anchor layer, an ink containing the catalyst or its precursor and a solvent is applied to the anchor layer made of a polymer by an ink jet method, and then a sample is sufficiently obtained. dry. Next, the anchor layer film is sliced up and down at a position of A / 2 (μm), and is divided into a surface side area as an upper layer film and an interface side area as a lower layer film. This sample was quantified in terms of the amount of catalyst (mg) using an inductively coupled plasma-mass spectrometry (ICP-MS) apparatus and converted into the sample area, whereby the average catalyst concentrations D ₁ and D ₂ (mg / m ² ) is measured.

  The progress of electroless plating on the surface of the anchor layer is improved by increasing the catalyst concentration in the surface side region as compared with the region on the interface side with the substrate of the anchor layer according to the present invention. As a result, there is no need to increase the catalyst concentration in the ink more than necessary, and the amount of expensive catalyst is reduced, and the catalyst solubility and catalyst storage stability are also improved. In addition, ink ejection defects that occur due to catalyst deposition or the like are reduced.

In the present invention, in order to realize the relationship of D ₁ > D ₂ × 5, as a specific means for increasing the catalyst concentration in the surface side region of the anchor layer,
Method A) An acrylate copolymer containing an acrylonitrile component is used as the anchor layer polymer.

  In the case of a catalyst, particularly a palladium metal salt, it has been found that an acrylate copolymer having an acrylonitrile component has a high adsorptivity (coordination property). That is, by forming an anchor layer using an acrylate copolymer containing an acrylonitrile component, the distribution relationship of the catalyst concentration defined above can be realized. At this time, it is preferable to further contain an epoxy resin from the viewpoint of durability of the anchor layer.

  Method B) The anchor layer further contains a compound having an adsorptivity (coordination property) to the catalyst or its precursor.

  Method C) After forming the anchor layer, a compound having an adsorptivity (coordination property) to the catalyst or its precursor is applied to the surface of the anchor layer, and electroless plating is performed.

  Method D) The anchor layer is composed of two layers, an upper layer and a lower layer, the upper layer is composed of a polymer having a functional group that interacts with the catalyst or its precursor, and the lower layer is composed of a curable polymer.

Furthermore, in the present invention, as a catalyst ink applied to the anchor layer using an ink jet method,
1) Sufficient solubility and storage stability are obtained in the catalyst ink;
2) The wetness and permeability of the catalyst ink to the anchor layer surface;
The above two points are important. In order to satisfy these two requirements, the ink according to the present invention is characterized by using a non-aqueous ink that does not contain water.

  When the catalyst ink contains water, the above two requirements cannot be satisfied and a desired metal pattern cannot be formed.

Therefore, as a method E), by selecting the solvent of the catalyst ink according to the present invention, the penetration and absorption into the anchor layer can be controlled, and the relationship of D ₁ > D ₂ × 5 defined in the present invention is also realized. One means for doing this. It is preferable that the ink solvent has a certain degree of swelling and solubility with respect to the anchor layer polymer. Therefore, a solvent such as water or a lower alkyl alcohol is not preferable because it has almost no permeability. However, if a solvent that clearly dissolves the anchor layer polymer is selected, the permeability to the anchor layer becomes too high, and even in this case, it is difficult to make the catalyst exist on the surface portion of the anchor layer as in the present invention. .

  Particularly preferred solvents are at least one solvent selected from glycol diesters, glycol diethers, glycol ethers / esters, tertiary alcohols, and amides.

  Hereinafter, the details of the method for producing a metal pattern of the present invention will be further described.

〔substrate〕
In the method for producing a metal pattern of the present invention, the substrate on which the metal pattern is formed is not particularly limited as long as it has insulating properties. For example, from a highly rigid material such as glass or ceramics, PET ( Polyethylene terephthalate) and a film-like material composed of a resin such as polyimide.

  In the board | substrate used for this invention, you may perform a surface modification process from a viewpoint of adhesiveness improvement or the installation improvement of an anchor layer. Specific examples include plasma treatment, corona discharge treatment, UV irradiation treatment, silane coupling agent treatment, and the like.

[Anchor layer]
One feature of the present invention is that an anchor layer containing a polymer is provided on a substrate.

  Examples of the polymer constituting the anchor layer according to the present invention include polycarbonate, polyacrylonitrile, polystyrene, polyacrylic acid, polymethacrylic acid, polyacrylic ester, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyester, Polyamides, polyethers, polyurethanes, epoxy resins, phenol resins, etc., and their copolymers and their salts.

These polymers include:
1) Good adhesion between the substrate and the anchor layer polymer;
2) The electroless plating catalyst or its precursor in the ink and the polymer of the anchor layer have adsorptivity (coordination);
It is preferable to select from.

  In order to improve the adhesion between the substrate and the anchor layer, the polymer of the anchor layer preferably has a functional group that interacts with the substrate. Specific examples include a carboxyl group, an amino group, and a hydroxyl group.

  Examples of the functional group that can be adsorbed (coordinated) to the catalyst or its precursor in the ink include a carboxyl group, a hydroxyl group, a sulfonic acid group, an amino group, a cyano group, and an amide group.

In the present invention, in order to realize the relationship of D ₁ > D ₂ × 5, the above-mentioned methods A) to D) mentioned as the configuration of the anchor layer for increasing the catalyst concentration in the surface side region of the anchor layer explain.

  Method A) A method using an acrylate copolymer containing an acrylonitrile component as the polymer of the anchor layer.

  In the present invention, it is preferable to use an acrylate copolymer containing an acrylonitrile component in order to increase the catalyst concentration in the surface region compared to the region on the interface side with the substrate of the anchor layer. In this polymer, it is presumed that the acrylonitrile group is adsorbing (coordinating) with respect to a catalyst, particularly a palladium metal salt.

  As an acrylonitrile component, 5-90 mol% is preferable with respect to the whole acrylic acid ester copolymer (100 mol%), More preferably, it is 10-50 mol%. The weight average molecular weight (MW) of the acrylic ester copolymer is preferably from 5,000 to 1,000,000, more preferably from 100,000 to 850,000. Moreover, as Tg, from a viewpoint of the adhesiveness to a board | substrate, -30 degreeC-50 degreeC is preferable, More preferably, it is -10 degreeC-20 degreeC.

  At this time, it is preferable to further contain an epoxy resin from the viewpoint of durability of the anchor layer. As a compounding ratio (mass ratio) of the acrylic ester copolymer and the epoxy resin, the acrylic ester copolymer / epoxy resin = 10/90 to 90/10 is preferable. More preferably, it is 20 / 80-40 / 60.

  The epoxy resin is preferably an aromatic type, more preferably a bisphenol A type or a bisphenol F type. Further, it is preferable to further add a curing agent that reacts with the epoxy resin to be cured (crosslinked). In addition, the kind of hardening | curing agent and hardening conditions are selected suitably.

  Method B) A method in which the anchor layer further contains a compound having an adsorptivity (coordination property) to the catalyst or its precursor.

  Examples of the compound having a high adsorptivity (coordination property) to a catalyst, for example, a palladium metal salt, include compounds capable of forming a complex. Such a compound specifically includes an organic acid having a carboxyl group, and examples thereof include oxalic acid, malonic acid, succinic acid, adipic acid, maleic acid, tartaric acid, and citric acid.

  Examples of other compounds include amine compounds and nitrogen-containing heterocyclic compounds. An amine compound is a compound in which one or more hydrogen atoms of ammonia are substituted with a hydrocarbon residue, and is a complexing agent for Pd ions. Here, ammonia is also included. The amine retains an unshared electron pair on the N atom and tends to complex with palladium ions. As amines, ammonia, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, tripropylamine, butylamine, dibutylamine, tributylamine, pyridine, 2-aminopyridine, 3-aminopyridine , 4-aminopyridine, ethylenediamine, ethanolamine, triethanolamine, linear amine compounds such as ethylenediaminetetraacetic acid, and cyclic amine compounds. Examples of the nitrogen-containing heterocyclic compound include pyridine, bipyridine, phenanthroline and the like.

  Method C) A method in which after forming the anchor layer, a compound having an adsorptivity (coordination property) to the catalyst or its precursor is applied to the surface of the anchor layer to perform electroless plating.

  The compound having the adsorptive property (coordinating property) in this case is the same as the compound described in the method B). Examples of the method for imparting to the surface of the anchor layer include a method of immersing the anchor layer in a liquid containing a compound having an adsorptive property (coordinating property), a method of applying on the anchor layer, and the like.

  Method D) The anchor layer is composed of two layers, an upper layer and a lower layer, the upper layer is composed of a polymer having a functional group that interacts with the catalyst or its precursor, and the lower layer is composed of a curable polymer.

  That is, when installing an anchor layer composed of two layers, the lower layer (layer close to the substrate) is a curable polymer that can prevent moisture and oxygen from entering from the substrate side (for example, epoxy resin, Phenolic resin, melamine resin, etc.), and the upper layer (layer far from the substrate) is preferably composed of a polymer having a functional group that interacts with the catalyst or its precursor.

  As a film thickness of an anchor layer, 0.05-10 micrometers is preferable and 0.1-5 micrometers is more preferable. When the thickness is less than 0.05 μm, the adhesion with the substrate is reduced, and when the thickness is greater than 10 μm, the adhesion is likely to deteriorate due to the cohesive failure of the polymer in the anchor layer.

  As a method for forming a polymer anchor layer, a polymer solution (dispersion) can be used, which can be appropriately selected from known coating methods, coated on a substrate and dried. Examples of the coating method include a roll coating method, a rod bar coating method, an air knife coating method, a spray coating method, and a dip method.

[Catalyst ink]
One of the characteristics of the ink used in the method for producing a metal pattern of the present invention is that it contains an electroless plating catalyst or a precursor thereof and a solvent.

(Electroless plating catalyst or its precursor)
The electroless plating catalyst contained in the catalyst ink according to the present invention is a metal that forms itself as a reaction active nucleus in the electroless plating treatment step. Specifically, palladium, silver, copper, nickel , Metals such as aluminum and iron.

  Moreover, the precursor of the electroless plating catalyst according to the present invention means a compound before being modified into an electroless plating catalyst, and can be a catalyst by an activation treatment step. Specifically, it is a metal salt compound, which becomes a zero-valent metal upon activation, for example, palladium metal salt, silver metal salt, copper metal salt, nickel metal salt, aluminum metal salt, iron metal salt Among them, palladium metal salts are preferable. Further, a palladium metal complex in which a palladium metal salt is complexed with a complexing agent may be used.

  Examples of the palladium metal salt applicable to the present invention include palladium fluoride, palladium chloride, palladium bromide, palladium iodide, palladium nitrate, palladium sulfate, palladium acetate, palladium acetoacetate, palladium trifluoroacetate, palladium hydroxide. , Palladium oxide, palladium sulfide and the like. Among them, in particular, those which are soluble in the solvent contained in the ink according to the present invention and insoluble in water are preferable, and specifically, palladium acetate, palladium acetoacetate and the like are preferable.

  The content of the palladium metal salt in the ink is preferably 0.01% by mass or more and 1.0% by mass or less. If the concentration of the palladium metal salt is 0.01% by mass or more, the necessary activity of the electroless plating reaction as the next step can be obtained, and if it is 1.0% by mass or less, the palladium metal in the ink is obtained. This is preferable in that the stability of the salt can be maintained.

(solvent)
Since the ink according to the present invention is a non-aqueous ink that does not contain water, the solvent is selected from organic solvents other than water.

In the present invention, as the method E), by controlling the penetration and absorption into the anchor layer by selecting the solvent of the catalyst ink according to the present invention, it is also possible to satisfy D ₁ > D ₂ × 5 as defined in the present invention. It is one means for realizing the relationship. It is preferable that the ink solvent has a certain degree of swelling and solubility with respect to the anchor layer polymer. Therefore, a solvent such as water or a lower alkyl alcohol is not preferable because it has almost no permeability. However, if a solvent that clearly dissolves the anchor layer polymer is selected, the permeability to the anchor layer becomes too high, and even in this case, it is difficult to make the catalyst exist on the surface portion of the anchor layer as in the present invention. .

  At this time, it is preferable to select a solvent having good solubility and storage stability with respect to the catalyst or catalyst precursor.

As a solvent applicable to the present invention,
Alcohols (eg, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol, etc.),
Polyhydric alcohols (for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol, etc.),
Polyhydric alcohol monoethers (for example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene Glycol monobutyl ether, dipropylene glycol monomethyl ether, dichloropyrene glycol monoethyl ether, dipropylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, ethylene glycol monophenyl Vinyl ether, propylene glycol monophenyl ether, etc.),
Polyhydric alcohols whose alcohol terminals are all etherified or esterified (for example, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, dipropylene glycol dimethyl ether, Triethylene glycol dimethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether Ether acetate, dipropylene glycol monomethyl ether acetate, ethylene glycol diacetate, diethylene glycol diacetate, propylene glycol diacetate, triethylene glycol diacetate, etc.),
Amines (e.g., ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyl Diethylenetriamine, tetramethylpropylenediamine, etc.),
Amides (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, etc.),
Heterocycles (eg, 2-pyrrolidone, N-methyl-2-pyrrolidone, cyclohexyl pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone),
Sulfoxides (for example, dimethyl sulfoxide),
Etc.

  Examples of other solvents include acetone, methyl ethyl ketone, toluene, benzene, cyclohexane, cyclohexanone, tetradecane, ethyl acetate, butyl acetate, γ-butyllactone, butyl lactate, ethylene carbonate, and propylene carbonate.

  As the solvent for the catalyst ink according to the present invention, at least one solvent selected from glycol diesters, glycol diethers, glycol ethers / esters, tertiary alcohols, and amides is used among the above-mentioned various solvents. That is.

(Complexing agent)
Examples of the complexing agent applicable to the ink according to the present invention include compounds capable of forming a complex with the palladium metal salt. Examples of the compound include organic acids having a carboxyl group, and examples thereof include oxalic acid, malonic acid, succinic acid, adipic acid, maleic acid, tartaric acid, and citric acid. Other compounds are preferably amine compounds or nitrogen-containing heterocyclic compounds. An amine compound is a compound in which one or more hydrogen atoms of ammonia are substituted with a hydrocarbon residue R, and is a complexing agent for Pd ions. Here, ammonia is also included. The amine retains an unshared electron pair on the N atom and tends to complex with palladium ions. As amines, ammonia, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, tripropylamine, butylamine, dibutylamine, tributylamine, pyridine, 2-aminopyridine, 3-aminopyridine , 4-aminopyridine, ethylenediamine, ethanolamine, triethanolamine, linear amine compounds such as ethylenediaminetetraacetic acid, and cyclic amine compounds. Examples of the nitrogen-containing heterocyclic compound include pyridine, bipyridine, phenanthroline and the like.

(Other various additives)
The ink according to the present invention can contain various conventionally known additives in other metal pattern forming inks as required. For example, fluorescent brighteners, antifoaming agents, lubricants, preservatives, thickeners, antistatic agents, matting agents, water-soluble polyvalent metal salts, acid bases, pH adjusters such as buffers, antioxidants, surfaces Tension modifiers, non-resistance modifiers, rust inhibitors, inorganic pigments and the like can be mentioned.

《Metallic pattern manufacturing process》
A method for producing a metal pattern using the ink of the present invention is performed as follows.

  1) a step of forming an anchor layer on the substrate, 2) a step of applying a catalyst ink, 3) an activation treatment for converting (reducing) the catalyst into a catalyst when the catalyst ink is a catalyst precursor, 4) an electroless plating solution Electroless plating process that generates metal. Thereafter, 5) the metal pattern portion may be made thicker in the electroplating step.

  In the pattern formation according to the present invention, it means both the case where only a necessary portion is formed and the case where it is formed on the entire anchor layer.

[Process of applying catalyst ink onto anchor layer by inkjet method]
When a conductive pattern such as a circuit is drawn by the ink jet method, the catalyst ink is printed on the anchor layer using an ink jet head having a droplet size corresponding to the target line width. Since the mist of the catalyst and the landing deviation of the ink deteriorate the circuit characteristics, an inkjet printing process with high landing accuracy and few defects is desired, and the existing inkjet printing technology can be used. Note that the ink jet head is preferably made of a member that is durable against a metal salt and a solvent contained in the ink. As a method, a piezo type head is preferable. The amount of the catalyst ink applied is selected in consideration of the concentration of the electroless plating catalyst in the ink or the precursor concentration, the boiling point of the solvent, the drying property, and the electroless plating property. The application amount of a specific catalyst ink ^is preferably ^{0.5ml / m 2 ~50ml / m 2} , more 2.0ml ^{/ m 2} ~30ml ^/ m 2 is preferred. When the applied amount is less than 0.5 ml / m ² , the electroless plating property (metal forming property) becomes insufficient, and when it exceeds 50 ml / m ^2, from the viewpoint of ensuring uniformity of catalyst ink application and drying properties. It becomes difficult.

  After applying the catalyst ink, it is preferable to provide a drying step. As a drying method, a method such as heating or blowing is preferable from the viewpoint of shortening the time or simplifying the step.

[Activation process]
The activation step in the method for producing a metal pattern of the present invention refers to a step of converting the catalyst precursor into a catalyst capable of electroless plating. When a precursor of an electroless plating catalyst is used for the catalyst ink, the activation treatment step is performed before the electroless plating treatment step in order to denature the catalyst electroless plating catalyst. When a metal salt compound is used as a precursor of the electroless plating catalyst, it is a step of reacting with a zero-valent metal by a reduction reaction, and this activation step can become an electroless plating catalyst.

  In the activation step, it is necessary to select an appropriate method depending on the type of the catalyst, and examples thereof include application of an acid, heating, and application of a reducing agent. As a preferable reducing agent, a boron-based compound is preferable, and specifically, sodium borohydride, trimethylamine borane, dimethylamine borane (DMAB) and the like are preferable. As a reduction method, an activation treatment can be performed by immersing a substrate provided with a catalyst ink in a solution of a reducing agent.

[Electroless plating process]
The electroless plating process according to the present invention will be described.

  Usually, the electroless plating treatment is a step of immersing in an electroless plating solution (bath) and forming a metal pattern by an electroless plating reaction at the anchor layer portion to which the catalyst ink is applied.

  The electroless plating solution mainly contains 1) metal ions, 2) complexing agent for electroless plating solution, and 3) reducing agent. Examples of the metal formed by electroless plating include gold, silver, copper, palladium, nickel, and alloys thereof, and copper, nickel, and alloys thereof are preferable from the viewpoint of adhesion and conductivity. Also as a metal ion used for an electroless plating bath, a metal ion corresponding to the above metal is contained. The complexing agent and reducing agent for the electroless plating solution are also selected to be suitable for metal ions. Examples of the complexing agent include ethylenediaminetetraacetic acid (hereinafter abbreviated as EDTA), Rochelle salt, D-mannitol, D-sorbitol, dulcitol, iminodiacetic acid, trans-1,2-cyclohexanediaminetetraacetic acid, and the like. EDTA is preferred. Examples of the reducing agent include formaldehyde, potassium tetrahydroborate, dimethylamine borane, glyoxylic acid and sodium hypophosphite, and formaldehyde is preferred.

  The electroless plating step can control the metal formation speed and film thickness by controlling the temperature, pH, immersion time, and metal ion concentration of the plating bath.

[Surface treatment process]
In the metal pattern manufacturing method of the present invention, before the electroless plating process (the activation process in the case of a catalyst precursor), the anchor layer increases the surface wettability with respect to the plating solution or the activation solution. It is preferable to perform a process.

  In the present invention, when a catalyst ink is applied to the anchor layer and the anchor layer is swollen or dissolved, the portion is formed into a film and becomes hydrophobic, so that the wettability to the plating treatment solution and the activation treatment solution is reduced. Plating properties are extremely lowered. Further, since the ink containing the catalyst penetrates into the anchor layer, the plating property is further lowered. Therefore, it is preferable to improve the wettability between the portion to which the catalyst ink is applied and the plating treatment liquid (or activation treatment liquid).

  Since the plating treatment solution or the activation treatment solution is usually an aqueous treatment solution, the improvement in wettability here means a surface treatment step for increasing the wettability of the anchor layer surface and water. If the contact angle of the anchor layer with respect to water decreases before and after the surface treatment step, the surface treatment is effective.

  Specifically, a means for reducing the contact angle with water by 20% or more before and after the surface treatment step is preferable. As the surface treatment method, there are a method of treating with a solution containing a cation, nonion, or anionic surfactant, and a method of improving wettability with respect to the plating solution by a surface hydrophilization treatment step such as plasma, corona, flame, or UV irradiation. . Above all, liquid treatment with a surfactant is simple and highly effective.

[Electroplating process]
In the method for producing a metal pattern of the present invention, an electroplating process may be further performed after performing an electroless plating process for the purpose of increasing the thickness of the metal pattern.

  In the electroplating process, after the electroless plating process, electroplating can be performed using the conductive film formed by the electroless plating process as an electrode. Accordingly, a conductive film having an arbitrary thickness can be easily formed on the basis of the conductive film having excellent adhesion to the substrate. By adding this step, the metal film can be formed to a thickness according to the purpose, and the conductive film formed according to the metal pattern manufacturing method of the present invention can be used for various applications that require high conductivity. Suitable for application.

  A conventionally known method can be used as the electroplating method. In addition, as a metal used for the electroplating of this process, copper, chromium, lead, nickel, gold, silver, tin, zinc, etc. are mentioned. From the viewpoint of conductivity, copper, gold, and silver are preferable. More preferred.

  About the film thickness of the electrically conductive film obtained by electroplating, it changes according to a use, It can control by adjusting the metal density | concentration contained in a plating bath, immersion time, or current density. In addition, from the viewpoint of conductivity, the film thickness when used for general electric wiring or the like is preferably 0.3 μm or more, and more preferably 3 μm or more.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

<< Preparation of base material with anchor layer >>
[Preparation of base material 1 with anchor layer]
(Preparation of anchor layer coating solution 1)
The following polymer A as polymer (1) was dissolved in methyl ethyl ketone under the condition of 20% by mass to prepare anchor layer coating solution 1.

Polymer (1); Polymer A (structure: acrylate copolymer, main monomer: butyl acrylate / ethyl acrylate / acrylonitrile / glycidyl modified, acrylonitrile monomer mass ratio: 30%, trade name: SG-P3, (Manufactured by Nagase ChemteX Corporation)
(Formation of anchor layer)
As a substrate, a polyimide film (Toray film processing (manufactured), Kapton 100EN film thickness 50 μm) was used, and the surface thereof was subjected to oxygen plasma treatment. Thus, the anchor layer was formed by applying and drying using a wire bar.

[Preparation of base material 2 with an anchor layer]
In the production of the anchor layer-provided substrate 1, an anchor layer-provided substrate 2 was produced in the same manner except that the following anchor layer coating solution 2 was used instead of the anchor layer coating solution 1.

(Preparation of anchor layer coating solution 2)
The following polymer A as the polymer (1), the following polymer B as the polymer (2) and the following additive a as the additive (1) are mixed in a mass ratio of 70: 27: 3, and this is mixed with methyl ethyl ketone. It melt | dissolved on the conditions which total mass becomes 20 mass%, and prepared the anchor layer coating liquid 2.

Polymer (1); Polymer A (structure: acrylate copolymer, main monomer: butyl acrylate / ethyl acrylate / acrylonitrile / glycidyl modified, acrylonitrile monomer mass ratio: 30%, trade name: SG-P3, (Manufactured by Nagase ChemteX Corporation)
Polymer (2); Polymer B (structure: epoxy resin, main monomer: bisphenol A type, trade name: iER828, manufactured by Japan Epoxy Resin Co., Ltd.)
Additive (1); Additive a (2-ethyl-4-methylimidazole)
[Preparation of anchor layer-attached base material 3]
In the production of the anchor layer-provided substrate 1, the anchor layer-provided substrate 3 was produced in the same manner except that the following anchor layer coating solution 3 was used instead of the anchor layer coating solution 1.

(Preparation of anchor layer coating solution 3)
The following polymer A as the polymer (1), the following additive a as the additive (1), and the following additive b as the additive (2) are mixed at a mass ratio of 77: 3: 10. An anchor layer coating solution 3 was prepared by dissolving in methyl ethyl ketone under the condition that the total mass was 20% by mass.

Polymer (1); Polymer A (structure: acrylate copolymer, main monomer: butyl acrylate / ethyl acrylate / acrylonitrile / glycidyl modified, acrylonitrile monomer mass ratio: 30%, trade name: SG-P3, (Manufactured by Nagase ChemteX Corporation)
Additive (1); Additive a (2-ethyl-4-methylimidazole)
Additive (2); Additive b (triethanolamine)
[Preparation of anchor layer-attached substrate 4]
(Formation of anchor layer)
In the production of the anchor layer-coated substrate 1, an anchor layer was formed on the substrate in the same manner except that the anchor layer coating solution 4 was used instead of the anchor layer coating solution 1.

<Preparation of anchor layer coating solution 4>
The following polymer B as the polymer (1) and the following polymer C as the polymer (2) are mixed at a mass ratio of 80:20, and this is dissolved in methyl ethyl ketone under the condition that the total mass is 20% by mass. A layer coating solution 4 was prepared.

Polymer (1); Polymer B (structure: epoxy resin, main monomer: bisphenol A type, trade name: iER828, manufactured by Japan Epoxy Resin Co., Ltd.)
Polymer (2); Polymer C (structure: NBR resin, main monomer: acrylonitrile / butadiene, monomer mass ratio of acrylonitrile: 27%, trade name: Nipol 1072J, manufactured by Nippon Zeon)
(Immersion in additive solution)
After immersing the formed base material with an anchor layer in a 10% by mass solution of additive c (a plating conditioner containing a nonionic surfactant, trade name: PC-321, manufactured by Meltac Co., Ltd.) at 60 ° C. for 5 minutes. The substrate 4 with an anchor layer was produced by drying.

[Preparation of the base material 5 with an anchor layer]
(Preparation of anchor layer lower layer coating solution 5)
The following polymer B as the polymer (1) and the following additive a as the additive (1) are mixed at a mass ratio of 90:10 and dissolved in methyl ethyl ketone under the condition that the total mass is 20% by mass. Then, an anchor layer lower layer coating solution 5 was prepared.

Polymer (1); Polymer B (structure: epoxy resin, main monomer: bisphenol A type, trade name: iER828, manufactured by Japan Epoxy Resin Co., Ltd.)
Additive (1); Additive a (2-ethyl-4-methylimidazole)
(Preparation of anchor layer upper layer coating solution 5)
The following polymer D as polymer (1) was dissolved in methyl ethyl ketone under the condition that the total mass was 20% by mass to prepare anchor layer upper layer coating solution 5.

Polymer (1); Polymer D (structure: acrylate copolymer, main monomer: butadiene / styrene, trade name: Nipol Lx430, manufactured by Nippon Zeon Co., Ltd.)
(Formation of anchor layer)
As a substrate, a polyimide film (Toray film processing (manufactured), Kapton 100EN film thickness 50 μm) is used, and after the surface is subjected to oxygen plasma treatment, the anchor layer lower layer coating solution 5 is dried to have a film thickness of 10 μm. The anchor layer lower layer was formed by applying and drying using a wire bar. Next, the anchor layer upper layer coating solution 5 was applied and dried using a wire bar so that the film thickness after drying was 2 μm to form an anchor layer upper layer, and the anchor layer-attached substrate 5 was produced.

[Preparation of anchor layer-attached substrate 6]
In the production of the anchor layer-provided substrate 1, the anchor layer-coated substrate 6 was produced in the same manner except that the following anchor layer coating solution 6 was used instead of the anchor layer coating solution 1.

(Preparation of anchor layer coating solution 6)
The following polymer D as polymer (1) was dissolved in methyl ethyl ketone under the condition that the total mass was 20% by mass to prepare anchor layer coating solution 6.

Polymer (1); Polymer D (structure: acrylate copolymer, main monomer: butadiene / styrene, trade name: Nipol Lx430, manufactured by Nippon Zeon Co., Ltd.)
Table 1 shows the configurations of the anchor layer-attached substrates 1 to 6 produced as described above.

  In addition, the detail of each constituent material described with the abbreviation in Table 1 is as follows.

<polymer>
Polymer A; structure: acrylate copolymer, main monomer: butyl acrylate / ethyl acrylate / acrylonitrile / glycidyl modified, acrylonitrile monomer mass ratio: 30%, trade name: SG-P3, manufactured by Nagase ChemteX Corporation ,
Polymer B; structure: epoxy resin, main monomer: bisphenol A type, trade name: iER828, manufactured by Japan Epoxy Resin Co., Ltd.
Polymer C; structure: NBR resin, main monomer: acrylonitrile / butadiene, monomer mass ratio of acrylonitrile: 27%, trade name: Nipol 1072J, manufactured by Nippon Zeon Co., Ltd.
Polymer D; structure: acrylate copolymer, main monomer: butadiene / styrene, trade name: Nipol Lx430, manufactured by Nippon Zeon Co., Ltd.
<Additive>
Additive a; 2-ethyl-4-methylimidazole,
Additive b; Triethanolamine Additive c; Plating conditioner containing nonionic surfactant, trade name: PC-321, manufactured by Meltac,
<Preparation of catalyst ink>
[Preparation of catalyst ink 1]
Catalyst ink 1 was prepared by mixing the following additives.

Electroless plating catalyst precursor; palladium acetate 0.2% by mass
Solvent: 99.8% by mass of ethylene glycol diacetate (EGDAc)
[Preparation of catalyst inks 2 to 6]
Table 2 shows the types and addition amounts of electroless plating catalyst precursors, the types and addition amounts of solvents, the presence or absence of addition of water, and the presence or absence of addition of complexing agents in the same manner as in the preparation of the catalyst ink 1. Catalyst inks 2 to 6 were prepared as combinations.

  In addition, the detail of each additive described by the abbreviation in Table 2 is as follows.

<Catalyst precursor for electroless plating>
PdAc: Palladium acetate PdCl: Palladium chloride Silver behenate <Organic solvent>
EGDAc: ethylene glycol diacetate DEGDEE: diethylene glycol diethyl ether DEGMBE: diethylene glycol monobutyl ether DMF: dimethylformamide t-BuOH: ter-butyl alcohol <complexing agent>
2-AP: 2-aminopyridine [Characteristic evaluation of catalyst ink]
Each of the catalyst inks prepared above was subjected to the following evaluations.

(Evaluation of ink storage stability)
Each catalyst ink prepared above was filled in a glass bottle, sealed, and stored in a constant temperature bath at 60 ° C., 40 ° C., and 25 ° C. for 4 weeks, and then the presence or absence of precipitates in each catalyst ink, 25% The above viscosity fluctuations and discoloration were evaluated, and ink storage stability was evaluated according to the following criteria.

A: No precipitation, no change in viscosity, no change in color change, etc. is observed even after storage for 4 weeks at 25 ° C. to 60 ° C. ○: Generation of a precipitate even after storage for 4 weeks at 25 ° C. and 40 ° C. No changes such as viscosity change or discoloration are observed. However, when stored at 60 ° C. for 4 weeks, slight changes are observed in at least one of the generation of precipitates, viscosity fluctuations, and discoloration. However, the quality is acceptable in practice. ×: 4 weeks at 25 ° C. After storage, there is a clear change in at least one of the occurrence of precipitates, viscosity fluctuation, and discoloration, and this is a quality that poses a practical problem (evaluation of ink ejection stability)
Using Konica Minolta IJ 512S head capable of ejecting 4 pl size droplets, after performing continuous ejection at 20 kHz for 1 hour, and after stopping the ejection by changing the rest time, the ink when ejected again The flying state of the droplets was observed, and the ink ejection stability was evaluated according to the following criteria.

A: No nozzle missing or ink bending occurs even after continuous discharge for 1 hour. In addition, even if re-ejecting after resting for 1 hour, no problem occurs. ○: No nozzle missing or ink bending occurs even after continuous ejection for 1 hour. Moreover, even if it discharged again after resting for 10 minutes, it discharged without a problem. However, if the stop time exceeds 10 minutes, slightly weak ink bending occurs, but this is acceptable in practice. ×: Nozzle missing or ink bending occurs during continuous discharge for 1 hour. Table 2 shows the results obtained as described above, which are practically problematic quality.

  As is apparent from the results in Table 2, it can be seen that the catalyst ink used in the present invention containing no moisture is excellent in the storage stability and ejection stability of the ink.

<Formation of metal pattern>
[Formation of metal pattern 1]
Metal pattern 1 was formed according to the following process.

(Metal pattern formation process)
1) Catalyst ink application process 2) Activation process (in the case of a catalyst precursor, it was not performed in the case of a catalyst)
3) Electroless plating process (Catalyst ink application process: inkjet method)
The prepared catalyst ink 1 is loaded into an ink jet printing apparatus, and 75 μm, 100 μm, 150 μm, and 200 μm line and space patterns are drawn on a substrate 1 with an anchor layer, and a solid image of 500 mm × 500 mm is drawn. It was. The inkjet head was drawn using a Konica Minolta IJ 512S head capable of ejecting droplets of 4 pl size.

(Activation process)
After image printing with the catalyst ink 1, it was immersed in the following activation liquid at 35 ° C. for 10 minutes.

<Activation liquid>
Alcup MRD2-A (Uemura Kogyo Co., Ltd.) 18ml
Alcup MRD2-C (made by Uemura Kogyo Co., Ltd.) 60ml
Finished with 1000 ml of pure water (electroless plating process)
An electroless copper plating solution was prepared according to the following method.

  The electroless copper plating solution has a copper concentration of 2.5 mass%, a formalin concentration of 1.0 mass%, and an ethylenediaminetetraacetic acid (EDTA) concentration of 2.5 mass%. Moreover, the pH of the electroless copper plating solution was adjusted to 13.0 with sodium hydroxide. The prepared electroless copper plating solution was heated to 50 ° C., and the activated sample was subjected to electroless plating to form a metal pattern having a thickness of about 0.2 μm.

<Electroless copper plating solution>
Melplate CU-5100A (Meltex) 60ml
Melplate CU-5100B (Meltex) 55ml
Melplate CU-5100C (Meltex) 20ml
Melplate CU-5100M (Meltex) 40ml
Finished with 1000 ml of pure water [Formation of metal patterns 2 to 13]
In preparation of the said metal pattern 1, the metal patterns 2-13 were formed similarly except having set the kind of base material with an anchor layer, and the kind of catalyst ink as the combination of Table 3.

<Measurement of catalyst amount of metal pattern>
[Measurement of D1 and D2]
In the preparation of each metal pattern, the solid image portion of 500 mm × 500 mm subjected to the application of the catalyst ink was subjected to the following method in the surface side region of the anchor layer (surface opposite to the contact surface of the substrate). the average density D ₁ of the catalyst or its precursor, to measure the average density D ₂ of the catalyst or its precursor in the interface side region of the substrate of the anchor layer.

After each sample subjected to the application of the catalyst ink is sufficiently dried, first, the catalyst amount (mg) of the entire anchor layer is quantified using an inductively coupled plasma-mass spectrometry (ICP-MS) apparatus, and the unit area The amount of catalyst per mg (m / m ² ) C ₁ was determined.

Next, the sample is sliced by a microtome to 1/2 the position of the anchor layer (anchor layers 1 to 4 and 6 are at a position of 5.0 μm, anchor layer 5 is at a position of 6.0 μm) to form an upper layer film. The surface side region is deleted, leaving only the interface side region that is the lower layer film, and the amount of catalyst (mg) in this interface side region is quantified using an inductively coupled plasma-mass spectrometry (ICP-MS) device, and the unit area The amount of catalyst per mg (m ² ) D ₂ was determined.

From the above measurement results, the value of the catalyst amount (mg / m ² ) C ₁ -catalyst amount (mg) D _{2 in} the interface region was determined as the catalyst amount (mg) D _{1 in the} surface region.

<Evaluation of metal pattern>
Each of the formed metal patterns was subjected to the following evaluations.

[Evaluation of plating speed]
In the production of the metal pattern, the time until the copper film formed by the electroless plating process in the electroless plating process grew to 0.2 μm was measured, and the plating rate was evaluated according to the following criteria.

A: Time until the copper film thickness grows to 0.2 μm is less than 10 minutes O: Time until the copper film thickness grows to 0.2 μm is 10 minutes or more and less than 20 minutes Δ: The time until the copper film thickness grows to 0.2 μm is 20 minutes or more and less than 40 minutes. X: The time until the copper film thickness grows to 0.2 μm is 40 minutes or more. Evaluation of〕
The above-prepared metal patterns of 75 μm, 100 μm, 150 μm, and 200 μm lines and spaces were observed using an optical microscope, and fine line reproducibility was evaluated according to the following criteria.

◎: Each line & space of 75 to 200μ is accurately reproduced, and the plated line & space is uninterrupted and has good quality. ○: Slight variation in line width is recognized, but almost good Line and space are reproduced. ×: Line break due to bulge generation, line position deviation due to beading between droplets, and generation of streaks within the line are recognized. The results obtained are shown in Table 3.

  As is clear from the results shown in the table, the metal pattern produced by the method for producing a metal pattern of the present invention has a higher plating speed than the comparative example and is excellent in fine line reproducibility of the formed metal pattern. I understand.

Claims (8)

After forming an anchor layer containing a polymer on a substrate, an ink containing an electroless plating catalyst or a precursor thereof and a solvent is applied on the anchor layer by an ink jet method, and a metal pattern is formed by electroless plating treatment. in the manufacturing method of forming metal patterns, the average concentration of the catalyst or its precursor on the surface side region of the anchor layer (the surface opposite to the contact surface of the substrate) and D _1, and the substrate of the anchor layer when the average concentration of the catalyst or its precursor was D ₂ in the interface side region, satisfy the relation of D _1> D ₂ × 5, and that the ink is a non-aqueous ink containing no water as the solvent A method for producing a metal pattern.   The method for producing a metal pattern according to claim 1, wherein the catalyst or a precursor thereof is a palladium metal salt.   The method for producing a metal pattern according to claim 1 or 2, wherein the polymer contained in the anchor layer is an acrylate copolymer having an acrylonitrile component.   The method for producing a metal pattern according to claim 3, wherein the anchor layer further contains an epoxy resin as a polymer.   The method for producing a metal pattern according to any one of claims 1 to 4, wherein the anchor layer contains a compound having an adsorptivity (coordination property) to the catalyst or a precursor thereof.   6. The electroless plating is performed by forming a compound having an adsorptivity (coordination property) with respect to a catalyst or a precursor thereof on the surface of the anchor layer after forming the anchor layer. The manufacturing method of the metal pattern of any one of Claims 1.   The anchor layer is composed of two layers, an upper layer and a lower layer, the upper layer is composed of a polymer having a functional group that interacts with a catalyst or a precursor thereof, and the lower layer is composed of a curable polymer. Item 7. The method for producing a metal pattern according to any one of Items 1 to 6.   The solvent contained in the ink is at least one solvent selected from glycol diesters, glycol diethers, glycol ethers / esters, tertiary alcohols, and amides. 8. The method for producing a metal pattern according to any one of 7 above.