WO2009150936A1

WO2009150936A1 - Metal pattern forming method and metal pattern

Info

Publication number: WO2009150936A1
Application number: PCT/JP2009/059581
Authority: WO
Inventors: 眞一鈴木; 智史森
Original assignee: コニカミノルタＩｊ株式会社
Priority date: 2008-06-11
Filing date: 2009-05-26
Publication date: 2009-12-17
Also published as: JP5418497B2; JPWO2009150936A1

Abstract

Provided are a metal pattern forming method for obtaining a thick metal pattern having excellent drawing characteristics and scratch resistance, and a metal pattern formed by using such metal pattern forming method. A pattern section is printed on a substrate by employing an inkjet system using an ink containing a catalyst, and the metal pattern is formed on the pattern section by nonelectrolytic plating. The substrate has a porous layer containing inorganic fine particles on the surface, and has the catalyst being dissolved in the ink.

Description

Metal pattern forming method and metal pattern

The present invention relates to a metal pattern forming method and a metal pattern, and more particularly to a metal pattern forming method and a metal pattern used for circuit formation by an ink jet method.

Conventionally, formation of a metal pattern used for a circuit has been performed mainly by a method using a resist material. That is, after applying a resist material on a thin metal layer and exposing the required pattern to light, the unnecessary resist is removed by development, the exposed thin metal is removed by etching, and the remaining resist portion is peeled off. As a result, a metal thin film on which a metal pattern was recorded was formed.

However, in this method, the process is diverse and time-consuming, and unnecessary resist and removal of thin metal are wasteful in terms of production time, energy and raw material use efficiency, and improvement is required.

In recent years, attention has been focused on a metal pattern forming method in which a metal pattern is directly drawn by screen printing, ink jet printing or the like using an ink containing so-called metal nanoparticles having a particle size of 100 nm or less (see, for example, Patent Document 1). .)

This metal pattern forming 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 the advantages of reducing man-hours and improving the utilization efficiency of raw materials, it is difficult to completely fuse metal particles together, and the temperature in post-processing to lower the electrical resistance in the fired metal pattern The problem remains that there are severe restrictions on the conditions.

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 without using metal nanoparticles and heating. However, since the complexing agent that coordinates and stabilizes the metal salt does not have sufficient performance, the reduction reaction of the metal salt easily proceeds and the liquid 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 using electroless plating technology has also been proposed. For example, after forming a circuit pattern with the ink containing the catalyst which can form electroless plating, the method of forming a metal by an electroless-plating process is disclosed (for example, refer patent document 2).

In any of the above cases, the substrate on which the metal pattern is formed usually uses glass, resin film, etc., and most of these substrates do not have ink absorbability, so that the ink that has landed repels and spreads wet. It was difficult to obtain fine pattern drawing performance.

In response to the above problems, a method of obtaining a conductive pattern by providing a layer (receiving layer) having excellent ink absorption capacity on a substrate and applying a metal nanoparticle (for example, metal colloid) solution thereto by an inkjet method is disclosed. (For example, see Patent Document 3). However, since the metal particles are fine particles (colloid), most of them remain on the surface of the receiving layer, and a conductive pattern is formed there. Therefore, there is a drawback that only a very thin film pattern can be obtained.

JP 2002-299833 A JP 10-65314 A JP 2004-207558 A

The present invention has been made in view of the above problems, and its purpose is to print an ink containing a catalyst on a substrate provided with a porous layer using inorganic fine particles, and to perform good drawing by electroless plating. It is to provide a metal pattern forming method capable of obtaining a thick-film metal pattern having good properties and scratch resistance, and a metal pattern formed using the metal pattern forming method.

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

1. In a metal pattern forming method in which a pattern portion is printed by ink jet ink containing a catalyst on a substrate and a metal pattern is formed on the pattern portion by electroless plating, the substrate has inorganic fine particles F on the surface. A method for forming a metal pattern, comprising: a porous layer containing the catalyst, wherein the catalyst is present in a dissolved state in the ink.

2. 2. The method for forming a metal pattern according to 1 above, wherein the catalyst is a palladium compound.

3. 3. The method for forming a metal pattern according to 2, wherein the ink contains a compound capable of forming a complex with the palladium compound.

4. 4. The method for forming a metal pattern according to any one of 1 to 3, wherein the inorganic fine particles F are silica fine particles or alumina fine particles.

5. 5. The method for forming a metal pattern according to any one of 1 to 4, wherein the porous layer contains an organic binder B.

6. 6. The metal pattern forming method as described in 5 above, wherein a mass ratio (F: B) between the inorganic fine particles F and the organic binder B is 2: 1 to 20: 1.

7. Any one of the above 1 to 6, further comprising a catalyst activation step between the step of printing the ink containing the catalyst on the porous layer of the substrate and the step of performing the electroless plating treatment. The method for forming a metal pattern according to Item.

8. 8. A metal pattern formed by the metal pattern forming method according to any one of 1 to 7.

According to the present invention, it was possible to provide a metal pattern forming method capable of obtaining a thick film metal pattern having good drawability and scratch resistance, and a metal pattern formed using the metal pattern forming method.

Hereinafter, the best mode 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 printed a pattern portion by ink jet ink containing a catalyst on a substrate, and formed a metal pattern on the pattern portion by electroless plating treatment. In the metal pattern forming method, the substrate has a porous layer containing inorganic fine particles on the surface, and the catalyst is present in a dissolved state in the ink. As a result, the present inventors have found that a metal pattern forming method capable of obtaining a thick metal pattern having good properties and scratch resistance can be realized.

The metal pattern forming method of the present invention is characterized in that after the ink containing the catalyst is printed on the substrate having the porous layer containing inorganic fine particles, the metal pattern is formed by electroless plating treatment. This process can be performed under mild conditions of 100 ° C. or lower. On the other hand, for example, a conventionally known method using metal nanoparticles requires a sintering temperature of 150 to 300 ° C. for fusing the nanoparticles and decomposing the organic dispersant. In addition, in the case of an oxidizing metal such as copper, an inert gas (nitrogen) or a reducing gas (hydrogen) is required in the sintering atmosphere. This has the advantage that a pattern can be formed.

In addition, as one of the features of the present invention, by using a substrate provided with a porous layer containing inorganic fine particles, there is no repellency or ink wetting and spreading that occurs on a substrate that does not have ink absorption capability, and high definition. Pattern drawability can be obtained. Further, since the catalyst contained in the ink exists in a dissolved state, the catalyst can be present uniformly throughout the porous layer by sufficiently permeating the porous layer without staying only on the surface of the porous layer. As a result, a metal can be formed in the porous layer in the subsequent electroless plating process. Further, a desired metal film thickness can be obtained according to the film thickness of the porous layer.

In addition, by forming a metal pattern in the porous layer, it was possible to impart excellent properties such as scratch resistance against external stress. Further, since the catalyst is present in a dissolved state in the ink, there is no fear of clogging in the ink jet head, the emission stability is improved, and it is excellent for forming a fine pattern.

Hereinafter, the metal pattern forming method of the present invention and details of the metal pattern formed using the method will be described.

"ink"
〔catalyst〕
Examples of the catalyst used in the ink according to the present invention include metals such as palladium, silver, copper, gold, nickel, aluminum, and tin. Of these, palladium, silver, and tin are preferable, and palladium is more preferable because of high catalytic activity. A feature of these catalysts is that they exist in a dissolved state in the ink, not metal fine particles or metal salt colloids (for example, palladium-tin colloid). This is a dissolved homogeneous ink, so that the porous layer on the substrate can be sufficiently penetrated in the thickness direction.

Conventionally, when the catalyst is a metal fine particle or a metal salt colloid, the catalyst cannot uniformly penetrate into the porous layer, and a part of the catalyst is exposed on the surface of the porous layer. Even if the electroless plating treatment is performed in such a state, uniform and sufficient metal cannot be formed inside, and good conductivity cannot be obtained. In addition, the metal is also exposed outside the porous layer, and the scratch resistance is low.

Furthermore, the ink according to the present invention is superior in emission stability because there is no concern about clogging in the ink jet head because the catalyst exists in a dissolved state in the ink as compared with the fine particles of metal fine particles and metal salt colloids.

In the ink according to the present invention, when palladium is used as a catalyst, it is not particularly limited as long as it is a divalent ion. Examples thereof include palladium fluoride, palladium chloride, palladium bromide, palladium iodide, palladium nitrate, palladium sulfate, palladium acetate, palladium oxide, palladium sulfide and the like.

The content of palladium in the ink is preferably 0.0001 to 1% by mass. The palladium concentration is preferably 0.0001% by mass or more from the viewpoint of electroless plating reaction activity, and is preferably 1% by mass or less from the viewpoint of the stability of palladium in the ink.

It is preferable to add a compound capable of forming a complex with a palladium compound for the purpose of improving the solubility and stability in palladium ink and the emission from the head.

Examples of compounds capable of forming a complex applicable to the present invention include amine compounds such as ethylenediamine, ethanolamine, ethylenediaminetetraacetic acid, and benzylamine, and nitrogen-containing heterocyclic compounds such as pyridine, bipyridyl, and phenanthroline.

In order to improve the solubility and storage stability of palladium ions in the ink, it is preferable to adjust the pH of the ink to a range of 8 to 14, more preferably a pH of 9 to 14.

[Ink solvent]
As the solvent applicable to the ink according to the present invention, an aqueous liquid medium is preferably used from the viewpoint of solubility of the catalyst, and as the aqueous liquid medium, a mixed solvent such as water and a water-soluble organic solvent is more preferably used. . The composition of these solvents is selected in consideration of the dissolved state of the catalyst.

Examples of water-soluble organic solvents preferably used include alcohols (eg, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol, etc.), polyhydric alcohols (eg, ethylene glycol, diethylene glycol) , Triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol, etc.), polyhydric alcohol ethers (eg, ethylene glycol monomethyl ether) , Ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol Ether monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, ethylene Glycol monophenyl ether, propylene glycol monophenyl ether, etc.), amines (eg ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylene) Tetramine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine, etc.), amides (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, etc.), heterocyclics (eg, 2-pyrrolidone, N-methyl-2-pyrrolidone, cyclohexyl pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, etc.), sulfoxides (eg dimethyl sulfoxide, etc.) and the like.

[Surfactant]
Surfactants applicable to the ink according to the present invention include alkyl sulfates, alkyl ester sulfates, dialkyl sulfosuccinates, alkyl naphthalene sulfonates, alkyl phosphates, polyoxyalkylene alkyl ether phosphates, fatty acids Anionic surfactants such as salts, nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyalkylene alkyl phenyl ethers, acetylene glycols, polyoxyethylene-polyoxypropylene block copolymers, glycerin esters, sorbitan Examples include surfactants such as esters, polyoxyethylene fatty acid amides, and amine oxides, and cationic surfactants such as alkylamine salts and quaternary ammonium salts.

[Other various additives]
The ink according to the present invention may contain other conventionally known additives 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.

《Catalyst activation process》
In the metal pattern formation method of this invention, it is preferable to have a catalyst activation process between the process of printing the ink containing the said catalyst on the porous layer of a board | substrate, and the process of performing the electroless-plating process mentioned later. .

That is, by performing a catalyst activation treatment before the step of performing the electroless plating treatment, after the ink containing the catalyst in a dissolved state is printed on the porous layer of the substrate, the catalyst metal present in the porous layer is removed. By making it a zero-valent metal, the electroless plating reaction is more activated. In the present invention, the step of making the catalyst metal zero is referred to as the catalyst activation step. In the catalyst activation step, it is necessary to select an appropriate method depending on the type of catalyst, and examples thereof include application of acid, heating, and application of a reducing agent. For example, in the case of a palladium-tin colloidal catalyst, by adding sulfuric acid or the like, an oxidation-reduction reaction between tin and palladium proceeds to produce zero-valent palladium metal. In the case of palladium ions, zero-valent palladium metal is generated by the reducing agent. A preferable reducing agent for palladium ions is a boron-based compound. Specifically, sodium borohydride, trimethylamine borane, dimethylamine borane (DMAB), and the like are preferable.

"substrate"
The substrate applicable in the present invention is not particularly limited as long as it has insulating properties. For example, the substrate is made of a material having high rigidity such as glass or ceramics, or a resin such as PET (polyethylene terephthalate) or polyimide. The film-like thing to mention is mentioned.

The substrate used in the present invention may be subjected to so-called primer treatment or plasma treatment from the viewpoint of improving adhesion. Similarly, an undercoat layer may be provided on the substrate. Examples of the material for the undercoat layer include thermoplastic resins such as acrylic resins and coupling agents such as silane coupling agents.

(Porous layer)
The substrate according to the present invention has a porous layer containing inorganic fine particles on the surface.

That is, a porous layer having ink absorbing ability is provided on the substrate, and the porous layer is preferably formed by forming a porous layer from inorganic fine particles and an organic binder.

Examples of the inorganic fine particles that can be used in the porous layer according to the present invention include light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, and hydroxide. Zinc, zinc sulfide, zinc carbonate, hydrotalcite, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, pseudoboehmite, aluminum hydroxide, lithopone, zeolite, hydroxylation Mention may be made of white inorganic pigments such as magnesium. From the viewpoint of ink absorbability and low-cost production, inorganic fine particles selected from silica-based fine particles and alumina-based fine particles are preferable.

The shape of the inorganic fine particles is not particularly limited, and may be any shape such as a spherical shape, a rod shape, a needle shape, a flat plate shape, and a bead shape.

The inorganic fine particles may be used in a state of being uniformly dispersed in the organic binder as primary particles, or may be used in a state of being dispersed in the organic binder by forming secondary agglomerated particles. From the viewpoint of achieving fast ink absorption, the latter is more preferable. From the same viewpoint, it is preferable to use inorganic fine particles having an average particle diameter of 3 to 200 nm in the film. Further, from the viewpoint of production of inorganic fine particles, the average particle diameter is more preferably 10 to 100 nm.

The average particle size of the inorganic fine particles can be obtained as a simple average value (number average) by observing the cross-section or surface of the fine particles themselves or the porous layer with an electron microscope, measuring the particle size of a large number of arbitrary fine particles. . The individual particle diameter referred to in the present invention is represented by a diameter assuming a circle equal to the projected area.

In the present invention, silica or colloidal silica synthesized by a gas phase method is preferable as the inorganic fine particles having anionic surfaces because of low cost. In addition, as the inorganic fine particles having a cationic surface, vapor phase silica having a cationic surface treatment, colloidal silica having a cationic surface treatment, alumina, colloidal alumina, pseudoboehmite, or the like can be used.

The film thickness of the porous layer is preferably 0.5 μm or more and 30 μm or less from the viewpoint of ink absorbency for pattern formation with catalyst ink and metal film thickness formed by electroless plating.

The amount of inorganic fine particles used in the porous layer depends largely on the required ink absorption capacity, the porosity of the porous layer, the type of inorganic fine particles, and the type of organic binder, but is generally 1 per 1 m ² of the porous layer. -30 g, preferably 3-25 g.

The ratio (F: B) between the inorganic fine particles F and the organic binder B is preferably 2: 1 to 20: 1, and more preferably 3: 1 to 10: 1. As the amount of inorganic fine particles added increases, the ink absorption capacity increases. On the other hand, curling, cracking, and the like are liable to deteriorate. Therefore, a method of increasing the ink absorption capacity by controlling the porosity is preferable.

From the viewpoint of resistivity, cracks, etc. of the metal pattern formed by electroless plating on the porous layer, the preferable porosity is 40 to 75%. The porosity can be set to a desired value depending on the type of inorganic fine particles and hydrophilic binder to be selected, or the mixing ratio thereof, or by appropriately adjusting the amount of other additives. The porosity here is the ratio of the total volume of the voids to the volume of the porous layer, and can be calculated from the total volume of the constituents of the layer and the thickness of the layer. Further, the total volume of the voids can be easily determined by measuring the amount of saturation transition and water absorption by Bristow measurement.

Examples of the organic binder applicable in the porous layer according to the present invention include polyvinyl alcohol, gelatin, polyethylene oxide, polyvinyl pyrrolidone, casein, starch, agar, carrageenan, polyacrylic acid, polymethacrylic acid, polyacrylamide, and polymethacrylamide. And hydrophilic polymers such as polystyrene sulfonic acid, cellulose, hydroxyl ethyl cellulose, carboxyl methyl cellulose, hydroxyl ethyl cellulose, dextran, dextrin, pullulan, and water-soluble polyvinyl butyral. Two or more of these organic binders can be used in combination.

Next, a method for producing a porous layer according to the present invention will be described.

As the method for producing the porous layer, it can be suitably selected from known coating methods and coated on the 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, a curtain coating method, or US Pat. Nos. 2,761,419 and 2,761,791. A slide bead coating method using an hopper, an extrusion coating method, or the like is preferably used.

《Ink and porous layer》
In order to draw a high-resolution fine line well and quickly, it is necessary to appropriately select the conditions of the ink droplet and the porous layer. As these conditions, the ink droplet is preferably as small as possible, and is 10 pl or less, preferably 4 pl or less. With such a fine droplet size, a thin line pattern with a line width of about 50 μm can be drawn. In order to draw such fine lines, high resolution is required for printing. A resolution of 360 dpi or more and 720 dpi or more is more preferable. In addition, dpi as used in the field of this invention represents the number of dots per 2.54 cm. In order to print such fine droplets quickly with high resolution, the amount of absorption and the absorption speed must be sufficient in the ink performance of the porous layer. If the amount of absorption or the absorption speed is insufficient, ink overflow or bleeding occurs, and the drawing performance of thin lines is deteriorated. From this point of view, the porous layer has a film thickness of 0.5 μm or more, preferably 5 μm, and a porosity of 40% or more, preferably 60% or more, so that the ink absorption and absorption speed can be sufficiently obtained.

《Electroless plating treatment》
The electroless plating process according to the present invention will be described.

After pattern printing of the catalyst ink on the substrate provided with the porous layer by the inkjet method, electroless plating treatment is performed to obtain a metal pattern in which a metal is formed on the pattern portion.

Usually, the step of immersing the substrate printed with the above pattern in an electroless plating solution (bath) is a common method.

The electroless plating solution mainly contains 1) metal ions, 2) complexing agents, and 3) reducing agents. Examples of the metal formed by electroless plating include gold, silver, copper, palladium, nickel, and alloys thereof. From the viewpoint of conductivity and safety, silver or copper is preferable, and copper is more preferable. Therefore, metal ions corresponding to the above metals are contained as metal ions used in the electroless plating bath. Accordingly, copper ions are preferable, and examples thereof include copper sulfate. Complexing agents and reducing agents are also selected that are 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.

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

In the present invention, since a catalyst is present in the porous layer, it was confirmed by a cross-sectional photograph that a metal was formed in the porous layer when immersed in an electroless plating bath. The metal film thickness thus formed is related to the film thickness of the porous layer, but is preferably 0.1 μm or more and 30 μm or less.

<Method for forming metal pattern>
In the metal pattern forming method of the present invention, the ink containing the catalyst is ejected from the ink jet head to the substrate provided with the porous layer to form a pattern. The size of the droplets to be ejected is not particularly limited, but in the case of circuit wiring or the like, it is necessary to form fine lines, so the amount of droplets is 50 pl or less, preferably 20 pl or less.

The ink jet head is not particularly limited, and either a piezo type or a thermal type head can be used.

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 ink>
[Preparation of Ink 1: Present Invention]
Ink 1 was prepared using 0.02% by mass of palladium acetate as a catalyst, 50% by mass of ethylene glycol, 20% by mass of glycerin as a water-soluble organic solvent, and pure water as a residue. The pH of the ink was adjusted to 12.0 with sodium hydroxide, and it was confirmed that palladium acetate was dissolved.

[Preparation of ink 2: the present invention]
0.04% by mass of palladium chloride as a catalyst, 0.2% by mass of 2-aminopyridine complexed therewith, 50% by mass of ethylene glycol as a water-soluble organic solvent, 20% by mass of glycerin, pure water remaining Ink-2 was prepared as follows. The pH of the ink was adjusted to 13.0 with sodium hydroxide, and it was confirmed that palladium chloride was dissolved.

[Preparation of Ink 3: Comparative Example]
As a colloidal solution of palladium / tin, 3.0% by mass of Predep PN-104 (manufactured by World Metal), 27.0% by mass of catalyst PN105 (manufactured by World Metal), 30% by mass of water-soluble solvent ethylene glycol, glycerin Comparative ink 3 was prepared by adding 20% by mass and using pure water as a residue.

<Production of substrate>
[Preparation of substrate 1]
(Preparation of silica dispersion)
Gas phase method silica (QS-20, average particle size 12 nm, manufactured by Tokuyama Corporation) 15% by mass
25% by mass of 10% aqueous solution of polyvinyl alcohol (PVA235, saponification degree 88%, polymerization degree 3500, manufactured by Kuraray Co., Ltd.)
n-propanol 5% by mass
Pure water remaining amount The above-mentioned mixed solution was dispersed using a high-speed disperser to prepare a silica dispersion.

(Formation of porous layer)
On a polyethylene terephthalate (PET) sheet having a thickness of 100 μm, the silica dispersion was applied by a rod bar coating method under the condition that the dry film thickness was 20 μm, and dried to prepare a substrate 1 having a porous layer. As a result of measuring the porosity of the formed porous layer from the amount of water absorbed by the Bristow method, it was 65%.

[Substrate 2]
The substrate 2 was a polyethylene terephthalate (PET) sheet having a thickness of 100 μm.

<Formation of metal wiring pattern>
[Formation of metal wiring pattern 1]
(Wiring pattern formation)
The inkjet head evaluation device EB100 (manufactured by Konica Minolta IJ Co., Ltd.) mounted on the transport system option XY100 has a piezoelectric nozzle having an nozzle diameter of 20 μm, a suitable liquid amount of 2 pl, a maximum drive frequency of 25 kHz, a nozzle count of 1024, and a nozzle density of 360 dpi. A type inkjet head is mounted, and an input image can be recorded by an 8-pass interleaving method. Both the main scanning and sub-scanning recording resolutions are 1440 dpi, and the prepared ink 1 can be ejected. The prepared substrate 1 was attached to the stage, and the ink 1 containing the catalyst was discharged to form 100 fine line patterns with a wiring width of 50 μm, a wiring distance of 50 μm, and a wiring length of 30 mm.

(Activation step 1)
The substrate 1 after pattern formation by the above method was dried at 50 ° C. for 5 minutes, and then immersed in the following activation liquid containing a boron-based reducing agent for 15 minutes at room temperature. In this step, the Pd complex was reduced to form Pd metal. The substrate 1 after immersion was washed with pure water.

Alcup MDR2-A (Uemura Kogyo Co., Ltd.) 1.8% by mass
Alcup MDR2-C (manufactured by Uemura Kogyo Co., Ltd.) 6% by mass
Pure water remaining (electroless plating process)
The following electroless copper plating solution was prepared. The finished plating solution has a copper concentration of 2.5 mass%, a formalin concentration of 1 mass%, and an ethylenediaminetetraacetic acid (EDTA) concentration of 2.5 mass%. Further, the pH of the plating solution was adjusted to 13.0 with sodium hydroxide.

Melplate CU-5100A (Meltex) 6.0% by mass
Melplate CU-5100B (Meltex) 5.5% by mass
Melplate CU-5100C (Meltex) 2.0% by mass
Melplate CU-5100M (Meltex) 4.0% by mass
Pure water Remaining amount The activated substrate 1 is immersed in the electroless copper plating solution kept at 50 ° C. for 90 minutes, and the Pd metal pattern portion is plated on the copper metal with a wiring width of 50 μm and the distance between the wirings. 100 metal wiring patterns 1 were formed with a thickness of 50 μm and a wiring length of 30 mm.

[Formation of metal wiring pattern 2]
In the formation of the metal wiring pattern 1, the metal wiring pattern 2 was formed in the same manner except that the ink 2 was used instead of the ink 1 and the activation process in the activation step 1 was not performed.

[Formation of metal wiring pattern 3]
In the formation of the metal wiring pattern 1, the metal wiring pattern 3 was formed in the same manner except that the ink 2 was used instead of the ink 1.

[Formation of metal wiring pattern 4]
In the formation of the metal wiring pattern 1, the metal wiring pattern 1 is similarly used except that the comparative ink 3 is used instead of the ink 1, and the activation process 2 described below is used instead of the activation process of the activation process 1. Pattern 4 was formed.

(Activation step 2)
Palladium / tin colloidal ink 3 was immersed in the following solution at room temperature for 2 minutes to remove tin, leaving palladium metal. By this step, a wiring pattern of palladium metal of ink 3 was formed.

Accelerator AC-250 (World Metal) 25% by mass
Pure water remaining amount [Formation of metal wiring pattern 5]
In the formation of the metal wiring pattern 3, the metal wiring pattern 5 was formed in the same manner except that the substrate 2 was a polyethylene terephthalate (PET) sheet alone instead of the substrate 1 provided with the porous layer.

[Formation of metal wiring pattern 6]
In the formation of the metal wiring pattern 4, the metal wiring pattern 6 was formed in the same manner except that the substrate 2 was a polyethylene terephthalate (PET) sheet alone instead of the substrate 1 provided with the porous layer.

<< Evaluation of metal wiring pattern >>
Each evaluation below was performed about each produced metal wiring pattern and the ink used for the production.

[Evaluation of drawability of fine lines]
Each copper wiring pattern formed above was observed with an optical microscope, and fine line descriptiveness was evaluated according to the following criteria.

○: Fine line breakage (disconnection), no contact between thin lines, and line shape disorder (thinning or thickening) is less than 10%. Δ: Fine line breakage (breakage), no contact between thin lines, and line. Disturbance of shape (thinning or thickening) is 10% or more and less than 30% ×: Fine line chipping (disconnection), contact between thin lines is recognized, and line shape disorder (thinning or thickening) is 30% or more Yes [Evaluation of abrasion resistance of fine wires]
The surface of each copper wiring pattern thus formed was rubbed 20 times back and forth using a cloth (BEMCOT; manufactured by Asahi Kasei Kogyo Co., Ltd.) wetted with water. About the thin wire | line part after rubbing, lack of a metal film and peeling of a metal film were observed visually, and the abrasion resistance of the thin wire was evaluated according to the following reference | standard.

○: The number of fine lines in which metal film is missing or peeled off is less than 10%. Δ: The number of thin lines in which metal film is missing or peeled off is 10% or more and less than 50%. X: The number of thin lines in which the metal film is missing or peeled off is 50% or more [Measurement of film thickness of metal pattern]
A metal pattern having a size of 10 mm × 10 mm was formed by the method for forming each metal pattern. Next, the metal pattern was cut with a microtome, the cross section was observed with an optical microscope, the film thickness at 50 points was measured, and the average value was obtained. When the film thickness was less than 1 μm, the film thickness was measured using a scanning electron microscope.

[Evaluation of ink ejection stability]
The ink used in forming the wiring pattern and the ink jet ejection device are continuously ejected for 1 hour with all the nozzles in a low temperature and low humidity (10 ° C., 20% rh) environment, and the occurrence of missing nozzles after 1 hour. The ink was observed with a magnifying glass, and the ink ejection stability was evaluated according to the following criteria.

○: The number of missing nozzles is less than 2% with respect to the total number of nozzles. Δ: The number of missing nozzles is 2% or more and less than 10% with respect to the total number of nozzles. Table 1 shows each evaluation result obtained as described above.

As is clear from the results shown in Table 1, the metal wiring produced by the metal pattern forming method of the present invention in which the ink containing the catalyst of the present invention was discharged onto a substrate having a porous layer and electroless plating was performed. As compared with the comparative example, the pattern showed a metal pattern with good drawability, a sufficient metal film thickness was obtained, and a metal pattern excellent in scratch resistance could be formed.

Claims

In a metal pattern forming method in which a pattern portion is printed by ink jet ink containing a catalyst on a substrate and a metal pattern is formed on the pattern portion by electroless plating, the substrate has inorganic fine particles F on the surface. A method for forming a metal pattern, comprising: a porous layer containing the catalyst, wherein the catalyst is present in a dissolved state in the ink.
The metal pattern forming method according to claim 1, wherein the catalyst is a palladium compound.
The metal pattern forming method according to claim 2, wherein the ink contains a compound capable of forming a complex with the palladium compound.
The method for forming a metal pattern according to any one of claims 1 to 3, wherein the inorganic fine particles F are silica fine particles or alumina fine particles.
The metal pattern forming method according to any one of claims 1 to 4, wherein the porous layer contains an organic binder B.
6. The metal pattern forming method according to claim 5, wherein a mass ratio (F: B) of the inorganic fine particles F to the organic binder B is 2: 1 to 20: 1.
The catalyst activation step is provided between the step of printing the ink containing the catalyst on the porous layer of the substrate and the step of performing the electroless plating treatment. 2. The metal pattern forming method according to item 1.
A metal pattern formed by the metal pattern forming method according to any one of claims 1 to 7.