JPWO2010067696A1 - Metal pattern forming ink and metal pattern - Google Patents

Abstract

The present invention has a storage stability of a palladium metal salt in an ink and a good discharge property from an ink jet recording head, and the palladium metal salt functions as a catalyst for electroless plating, and draws a formed metal pattern. An ink for forming a metal pattern excellent in film thickness uniformity and adhesion and a metal pattern formed using the same are provided. This metal pattern forming ink is a method of forming a metal pattern on a substrate by printing a pattern portion by ink-jet ink containing a catalyst and forming a metal pattern on the pattern portion by electroless plating. In the ink for use, the catalyst contains a palladium metal salt and a complexing agent, and a complex is formed by the palladium metal salt and the complexing agent.

Description

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

  Conventionally, formation of a metal pattern used in a circuit has been performed 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, this method requires many processes and takes a lot of time, and is unnecessary in terms of production time, energy and raw material use efficiency, such as removing unnecessary resist and thin metal, and has been required to be improved.

  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 formation method is a method for forming a circuit by firing at a temperature of about 200 to 300 ° C. by 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 reducibility 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 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 forming electroless plating, and then a metal is formed by electroless plating (for example, Patent Document 2 and Non-Patent Document 1). reference.).

  In any of the above cases, a soluble palladium metal salt is contained in an ink, and the ink is printed on a substrate by an ink jet method to form a palladium catalyst pattern. Thereafter, electroless plating is performed to form a metal pattern on the catalyst pattern. However, since the palladium metal salt has poor dissolution stability, the palladium metal salt is deposited in the ink, or the palladium metal salt is in a non-uniform state on the printed circuit board, and the electroless plating is adversely affected. There was also a problem.

JP 2002-299833 A JP 7-131135 A

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

  The present invention has been made in view of the above-mentioned problems, and has as its object the storage stability of the palladium metal salt in the ink and the good dischargeability from the ink jet recording head, and the palladium metal salt is electroless plated. It is an object of the present invention to provide a metal pattern forming ink which functions as a catalyst for the metal pattern and is excellent in the drawability and film thickness uniformity of the formed metal pattern, and a metal pattern formed using the same.

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

  1. In a metal pattern forming ink used for printing a pattern portion by ink jet ink containing a catalyst on a substrate and forming a metal pattern on the pattern portion by electroless plating, the catalyst is palladium An ink for forming a metal pattern, comprising a metal salt and a complexing agent, wherein a complex is formed by the palladium metal salt and the complexing agent.

  2. 2. The metal pattern forming ink as described in 1 above, wherein the molar ratio of the palladium metal salt to the complexing agent is 1: 0.5 or more and 1:10 or less.

  3. 3. The metal pattern forming ink as described in 1 or 2 above, wherein the concentration of the palladium metal salt is 0.01% by mass or more and 1.0% by mass or less.

  4). 4. The metal pattern forming ink according to any one of 1 to 3, wherein the complexing agent is an amine compound or a nitrogen-containing heterocyclic compound.

  5. 5. The metal pattern forming ink according to any one of 1 to 4, wherein the pH is 9.0 or more and 13.5 or less.

  6). 6. The metal pattern forming ink according to any one of 1 to 5, wherein the organic solvent is contained in an amount of 5.0% by mass to 90% by mass with respect to the ink.

  7). 7. A metal pattern formed using the metal pattern forming ink according to any one of 1 to 6 above.

  According to the present invention, the storage stability of the palladium metal salt in the ink and the good dischargeability from the ink jet recording head, and further the palladium metal salt functions as a catalyst for electroless plating, and the drawability of the formed metal pattern In addition, it was possible to provide a metal pattern forming ink excellent in film thickness uniformity and adhesion, and a metal pattern formed using the same.

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

  The inventor of the present invention provides a metal pattern forming ink used for printing a pattern portion on a substrate by ink-jet ink containing a catalyst and forming a metal pattern on the pattern portion by electroless plating. The catalyst contains a palladium metal salt and a complexing agent, and is complexed with the palladium metal salt and the complexing agent. Metal that has stability and good discharge from an ink jet recording head, and also has a metal metal layer that functions as a catalyst for electroless plating and has excellent drawing performance, uniformity of film thickness, and adhesion. It has been found that a pattern forming ink can be realized, and has reached the present invention.

  In general, a palladium metal salt used as a catalyst is unstable and has a property of easily causing precipitation in a solution. In particular, it is difficult to say that the dissolution stability in water or a water-soluble organic solvent often used as a solvent for a metal pattern forming ink is good.

In order for the palladium metal salt to function as a catalyst, it is necessary to perform a reduction reaction from palladium ions (Pd ²⁺ ) to palladium metal (Pd ⁰ ). However, in the reduction reaction from palladium ion (Pd ²⁺ ) to palladium metal (Pd ⁰ ), the reaction rate often changes drastically depending on the reduction conditions (eg, reducing agent, temperature, pH, etc.). When the reaction is slow, it becomes difficult to produce palladium metal, and conversely, when the reaction is too fast and produced in the state of agglomerated palladium metal, a defect that adversely affects metal formation in the next electroless plating process often occurs.

  As a result of intensive studies in view of the above problems, the present inventor has found that the object effect of the present invention can be efficiently expressed by including a palladium metal salt and a complexing agent in the ink, and has led to the present invention. It depends on you.

Palladium ions (Pd ²⁺ ) are complexed with a complexing agent (Ch) that is a compound capable of being coordinated electrostatically (Pd-Ch), which has increased solubility and stability in ink. It has been found that the occurrence of precipitation and the like can be suppressed. At the same time, the reactivity of the complexed compound (Pd-Ch) by the reducing agent is relaxed, so that the application range of the reduction reaction condition is widened and can be controlled as a gradual reduction reaction. It became possible to make the metal uniform and dense. With this uniform and dense catalyst, it was possible to demonstrate excellent results in the reproducibility of thin wires and copper film thickness of metals produced by subsequent electroless plating, such as copper.

  That is, according to the present invention, the ink having high storage stability is free from clogging in the ink-jet head, the emission stability is increased, and a metal pattern by good electroless plating can be obtained.

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

《Metal pattern forming ink》
One feature of the metal pattern forming ink (hereinafter also simply referred to as ink) used for pattern formation by the inkjet method of the present invention is that the catalyst contains a palladium metal salt and a complexing agent.

〔catalyst〕
The catalyst used in the ink of the present invention is not in the form of metal fine particles or metal salt colloid (for example, palladium-tin colloid), but in a dissolved state in the ink by complexing a palladium metal salt with a complexing agent. The palladium metal salt present is preferred. This means that the ink is a homogeneously dissolved ink. As a result, there is no occurrence of clogging of the ink jet head, and stable emission can be realized.

  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 which palladium chloride is 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.

[Complexing agent]
Examples of the complexing agent applicable to the ink of 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. And it is preferably an amine compound or a nitrogen-containing heterocyclic compound. 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.

  In the ink of the present invention, the molar ratio of the palladium metal salt (Pd) and the complexing agent (Ch) is preferably in the range of 1: 0.5 or more and 1:10 or less. By setting the molar ratio of the palladium metal salt to the complexing agent to 1: 0.5 or more, the ratio of the complex formed by the palladium metal salt and the complexing agent increases, so that the solubility in the ink and the reduction reactivity are increased. Becomes better. Moreover, it is preferable when the molar ratio is 1:10 or less in order to suppress reaction inhibition by an excessive complexing agent.

  In order to improve the solubility and storage stability of the complex formed of the palladium metal salt and the complexing agent in the ink, the pH of the ink is preferably adjusted to a range of 8.0 or more, more preferably pH 9. It is 0-14.0, More preferably, it is pH 9.0-13.5, Most preferably, it is pH 10.0 or more and 13.5 or less. The complex formed by the palladium metal salt and the complexing agent is preferably formed at a pH of 8.0 or higher because the formation proceeds more easily as the pH of the ink is more alkaline. In combination with a non-ink-absorbing resin substrate, the higher the pH of the ink, the better the adhesion and the better.

[Ink solvent]
As the solvent applicable to the ink of the present invention, an aqueous liquid medium is preferably used from the viewpoint of solubility of the palladium metal salt and the complexing agent, and the aqueous liquid medium is a mixed solvent such as water and a water-soluble organic solvent. Is more preferably used. The composition of these solvents is preferably selected in consideration of the dissolved state of the complex formed with the palladium metal salt and the complexing agent.

  Examples of the water-soluble organic solvent preferably used include alcohols (for example, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol, etc.) and 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 ethers (eg, ethylene glycol monomethyl ether) , Ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol Cole 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, triethyl) 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 (for example, dimethyl sulfoxide, etc.) and the like.

  A simple catalyst solution containing only water as a solvent is not suitable as an ink-jet ink. The presence of the organic solvent gives an appropriate viscosity (viscosity) for the ink to be stably ejected from the inkjet head, and the viscosity can be adjusted in the range of 1.5 to 30 mPa / s. In addition, when the moisture of the ink is volatilized, moisture retention is imparted in order to avoid solidification and ejection failure in the head nozzle, and the surface tension of the ink can be adjusted to 50 to 25 mN / m suitable for inkjet using an organic solvent. is important. Therefore, the organic solvent is preferably 5 to 90% by mass in the ink, and more preferably 30 to 80% by mass. Moreover, as a boiling point of an organic solvent, 80 degreeC or more and 250 degrees C or less are preferable at the point of moisture retention and drying property.

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

[Other various additives]
The ink of the present invention may contain various conventionally known additives for 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.

〔substrate〕
In the metal pattern formation using the ink 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.

  However, in the metal pattern forming method of the present invention, it is preferable to use a non-ink-absorbing resin substrate. By using a non-ink-absorbing resin substrate, particularly a resin film, as the base material, excellent flexibility can be obtained, and it can be applied to a wide range of fields, and in addition, a non-ink-absorbing substrate can be obtained. Therefore, the expansion and contraction of the substrate in the metal pattern forming process is suppressed, so that a highly precise metal pattern can be formed.

  The non-ink-absorbing resin is not particularly limited as long as it has insulating properties. For example, a polyester resin, a diacetate resin, a triatesate resin, a polycarbonate resin, a polyvinyl chloride resin, a polyimide resin A film having a material such as, for example, is preferable. Among them, a film-like material composed of a resin such as PET (polyethylene terephthalate) or polyimide is preferable, and a polyimide film is more preferable.

  The substrate used in the present invention may be subjected to surface modification 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 a coupling agent such as a silane coupling agent.

<Metal pattern formation process>
The metal pattern forming method using the ink of the present invention includes 1) pattern printing in which an ink containing a palladium metal salt and a complexing agent is ejected from a inkjet head onto a non-ink-absorbing resin substrate to print a pattern portion. And 2) an electroless plating process for forming a metal pattern by performing an electroless plating process on the pattern portion, and further between the above 1) pattern printing process and 2) electroless plating process 3) It is preferable to provide a catalyst activation step.

[Pattern printing process]
In the metal pattern forming method according to the present invention, the ink of the present invention containing a palladium metal salt and a complexing agent is ejected from an inkjet head onto a non-ink-absorbing resin substrate to form a pattern. The size of the ink droplets to be ejected is not particularly limited. However, in the case of circuit wiring or the like, it is necessary to form fine lines, and therefore the amount is preferably 50 pl or less, and more preferably 20 pl or less.

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

[Catalyst activation process]
In the metal pattern forming method according to the present invention, the catalyst activation is performed between the step of printing on the substrate the ink containing the palladium metal salt of the catalyst and the complexing agent and the step of performing the electroless plating process described later. It is preferable to have a process.

That is, by performing a catalyst activation treatment before the step of performing the electroless plating treatment, an ink containing the catalyst in a dissolved state is printed on a substrate, and then palladium ions (Pd ²⁺ ) are converted to zero-valent metal ( By using Pd ⁰ ), the electroless plating reaction is more activated. In the present invention, the step of making the catalyst palladium 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. 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.

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

  After the ink containing the catalyst and the complexing agent is printed on the non-ink-absorbing resin substrate by an ink jet method, an electroless plating process is performed to obtain a metal pattern in which a metal is formed on the pattern portion. Usually, the step of immersing the non-ink-absorbing resin 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 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 silver or copper is preferable from the viewpoint of conductivity and safety, 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. 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.

  The metal film thickness formed in the present invention is preferably 0.01 μm or more and 30 μm or less.

  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 ink>
[Preparation of Ink 1: Present Invention]
0.2% by mass of palladium chloride as a catalyst, 0.2% by mass of 2-aminopyridine as a complexing agent, 30% by mass of ethylene glycol, 10% by mass of glycerin, and pure water as a residue as a water-soluble organic solvent An ink was prepared. Next, the pH of the ink was adjusted to 11.0 using sodium hydroxide to obtain ink 1. As a result of visually observing the appearance of the prepared ink 1, it was confirmed that palladium chloride was completely dissolved. The molar ratio (Pd: Ch) of palladium chloride (Pd) to 2-aminopyridine (Ch) in ink 1 is 1: 1.9.

[Preparation of inks 2 to 5: the present invention]
Ink 2 was prepared in the same manner as in the preparation of Ink 1, except that the amount of sodium hydroxide added was appropriately adjusted to change the pH of the ink to 7.5, 8.5, 13.2, and 13.6, respectively. ~ 5 were prepared. As a result of visual observation of the appearance of the prepared inks 2 and 5, it was confirmed that some undissolved palladium chloride was present.

[Preparation of Ink 6: Present Invention]
Ink 6 was prepared in the same manner as in Preparation of Ink 1 except that the amount of 2-aminopyridine as a complexing agent was changed to 0.047% by mass. The molar ratio (Pd: Ch) of palladium chloride (Pd) to 2-aminopyridine (Ch) in the ink 6 is 1: 0.38.

[Preparation of ink 7: the present invention]
Ink 7 was prepared in the same manner as in Preparation of Ink 1 except that the amount of 2-aminopyridine as a complexing agent was changed to 0.055% by mass. The molar ratio (Pd: Ch) of palladium chloride (Pd) to 2-aminopyridine (Ch) in ink 7 is 1: 0.50.

[Preparation of ink 8: the present invention]
Ink 8 was prepared in the same manner as in Preparation of Ink 1 except that the addition amount of palladium chloride was changed to 0.01% by mass and the addition amount of 2-aminopyridine as a complexing agent was changed to 0.026% by mass. did. The molar ratio (Pd: Ch) of palladium chloride (Pd) to 2-aminopyridine (Ch) in the ink 8 is 1: 4.9.

[Preparation of Ink 9: Present Invention]
Ink 9 was prepared in the same manner as in Preparation of Ink 1 except that the addition amount of palladium chloride was changed to 0.9% by mass and the addition amount of 2-aminopyridine as a complexing agent was changed to 0.9% by mass. did. The molar ratio (Pd: Ch) of palladium chloride (Pd) to 2-aminopyridine (Ch) in the ink 9 is 1: 1.9.

[Preparation of Ink 10: Present Invention]
Ink 10 was prepared in the same manner as in Preparation of Ink 1 except that the addition amount of palladium chloride was changed to 1.1% by mass and the addition amount of 2-aminopyridine as a complexing agent was changed to 1.1% by mass. did. The molar ratio (Pd: Ch) of palladium chloride (Pd) to 2-aminopyridine (Ch) in the ink 10 is 1: 1.9.

[Preparation of Ink 11: Present Invention]
Ink 11 was prepared in the same manner as in Preparation of Ink 1 except that the amount of addition of 2-aminopyridine as a complexing agent was changed to 1.0% by mass. The molar ratio (Pd: Ch) of palladium chloride (Pd) to 2-aminopyridine (Ch) in the ink 11 is 1: 9.5.

[Preparation of Ink 12: Present Invention]
Ink 12 was prepared in the same manner as in Preparation of Ink 1 except that the amount of addition of 2-aminopyridine as a complexing agent was changed to 1.16% by mass. The molar ratio (Pd: Ch) of palladium chloride (Pd) to 2-aminopyridine (Ch) in the ink 12 is 1: 11.0.

[Preparation of Ink 13: Present Invention]
0.1% by mass of palladium acetate as a catalyst, 0.2% by mass of ethylenediaminetetraacetic acid as a complexing agent, 30% by mass of ethylene glycol, 10% by mass of glycerin, and pure water as a residue as a water-soluble organic solvent An ink was prepared. Next, the pH of the ink was adjusted to 10.0 using sodium hydroxide to obtain ink 13. As a result of visually observing the appearance of the prepared ink 13, it was confirmed that palladium acetate was completely dissolved. The molar ratio (Pd: Ch) of palladium acetate (Pd) to ethylenediaminetetraacetic acid (Ch) in the ink 13 is 1: 1.5.

[Preparation of Ink 14: Comparative Example]
Ink was prepared using 0.1% by mass of palladium chloride as a catalyst, 30% by mass of ethylene glycol, 10% by mass of glycerin, and pure water as a residue as a water-soluble organic solvent. Next, ink 14 was prepared by slowly dropping hydrochloric acid until the palladium chloride was dissolved. As a result of measuring the pH of the ink 14, it was 1.0 or less.

[Preparation of Ink 15: Comparative Example]
As a metal 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, Comparative ink 15 was prepared by adding 20% by mass of glycerin and using pure water as a residue.

[Preparation of Ink 16: Present Invention]
Ink was prepared using 0.2% by mass of palladium chloride as a catalyst, 0.2% by mass of bipyridine as a complexing agent, 30% by mass of ethylene glycol, 10% by mass of glycerin as a water-soluble organic solvent, and pure water as a residue. did. Next, the pH of the ink was adjusted to 10.0 using sodium hydroxide to obtain ink 16. As a result of visual observation of the appearance of the prepared ink 16, it was confirmed that palladium chloride was completely dissolved. The molar ratio (Pd: Ch) of palladium chloride (Pd) and bipyridine (Ch) in the ink 16 is 1: 1.5.

[Preparation of Ink 17: Present Invention]
Prepare an ink using 0.2% by mass of palladium chloride as a catalyst, 0.2% by mass of ethylenediamine as a complexing agent, 30% by mass of ethylene glycol, 10% by mass of glycerin as a water-soluble organic solvent, and pure water as a residue. did. Next, the pH of the ink was adjusted to 10.0 using sodium hydroxide to obtain ink 17. As a result of visual observation of the appearance of the prepared ink 17, it was confirmed that palladium chloride was completely dissolved. The molar ratio (Pd: Ch) of palladium chloride (Pd) to ethylenediamine (Ch) in the ink 17 is 1: 1.5.

<Evaluation of ink>
Each of the inks prepared above was subjected to the following evaluations.

[Evaluation of output stability]
Ink jet ejection apparatus in which each of the inks prepared above is mounted with an ink jet head KM256Aq water system head (manufactured by Konica Minolta IJ) on an ink jet head evaluation apparatus EB100 (manufactured by Konica Minolta IJ) mounted on the transport system option XY100. Attached, and under a low-temperature, low-humidity (10 ° C, 20% RH) environment, all nozzles emit light continuously for 1 hour, and the state of nozzle missing after 1 hour is observed with a magnifying glass. Ink emission stability was evaluated.

A: The number of missing nozzles is less than 2% with respect to the total number of nozzles. O: The number of missing nozzles is 2% or more and less than 5% with respect to the total number of nozzles. Δ: The number of missing nozzles is 5% or more and less than 10% with respect to the total number of nozzles x: Number of missing nozzles is 10% or more with respect to the total number of nozzles [Evaluation of storage stability]
Put each ink prepared above in a glass bottle, 1) store at 50 ° C. for 8 hours, then 2) return the temperature to room temperature, then 3) store for 8 hours at −10 ° C. The cycle was repeated. Subsequently, the ink after cycle storage and the ink before storage were compared and observed visually, and the storage stability of the ink was evaluated according to the following criteria.

A: No change in ink liquid was observed before and after storage, and no precipitate was observed. ○: A slight change was observed in the ink liquid before and after storage, but the occurrence of precipitate was confirmed. △: Precipitation was observed before and after storage, but the amount of precipitate after storage was very small. ×: Precipitate increased before and after storage, or a large amount of precipitate both before and after storage. Confirmed Each evaluation result obtained as described above is shown in Table 1.

  As is clear from the results shown in Table 1, it can be seen that the ink according to the present invention is superior in emission stability and storage stability compared to the comparative example.

<Formation of metal wiring pattern>
[Formation of metal wiring pattern 1]
(Wiring pattern formation)
An inkjet head KM256Aq aqueous system head (manufactured by Konica Minolta IJ Co., Ltd.) is attached to the ink jet head evaluation apparatus EB100 (manufactured by Konica Minolta IJ Co., Ltd.) attached to the transport system option XY100 so that the prepared ink 1 can be ejected. did. A polyimide sheet (substrate 1) having a thickness of 75 μm is attached to the stage as a non-ink-absorbing resin substrate, and ink 1 is ejected, wiring width 50 μm, wiring distance 50 μm, wiring length 30 mm, 100 fine line patterns and 10 mm A square metal pattern of × 10 mm was formed.

(Activation step 1)
The substrate 1 after pattern formation by the above method was dried at 80 ° 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.

<Activation liquid>
Alcup MRD2-A (manufactured by Uemura Kogyo Co., Ltd.) 1.8% by mass
Alcup MRD2-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 following electroless copper 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%. The pH of the electroless copper plating solution was adjusted to 13.0 with sodium hydroxide.

<Electroless copper plating solution>
Melplate CU-5100A (Meltex) 6% 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
The remaining amount of pure water is immersed in the electroless copper plating solution kept at 50 ° C. for 90 minutes, and the substrate 1 subjected to the activation step 1 is immersed for 90 minutes, and the Pd metal pattern portion is plated with copper metal at a wiring width of 50 μm, 100 metal wiring patterns and a 10 mm × 10 mm square metal wiring pattern 1 were formed with a wiring distance 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 catalyst activation treatment 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 substrate 2 (75 μm thick polyethylene terephthalate film) was used instead of the substrate 1 (75 μm thick polyimide sheet). .

[Formation of metal wiring patterns 4 to 16]
In the formation of the metal wiring pattern 1, metal wiring patterns 4 to 16 were formed in the same manner except that the inks 2 to 14 were used instead of the ink 1, respectively.

[Formation of metal wiring pattern 17]
In the formation of the metal wiring pattern 1, the metal wiring pattern 17 was formed in the same manner except that the ink 1 was changed to the ink 15 and the activation process 1 was changed to the activation process 2 described below.

(Activation step 2)
A square metal pattern was formed using palladium / tin colloidal ink 6 and then 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 6 was formed.

Accelerator AC-250 (World Metal) 25% by mass
Pure water remaining amount (formation of metal wiring patterns 18, 19)
In the formation of the metal wiring pattern 1, metal wiring patterns 18 and 19 were formed in the same manner except that the inks 16 and 17 were used in place of the ink 1, respectively.

<< Evaluation of metal wiring pattern >>
Each of the following evaluations was performed on the formed metal wiring pattern.

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

◎: There is no chipping (disconnection) or contact between the thin wires, and the line shape disorder (thinning or thickening) is less than 5%. ○: There is no chipping (disconnection), there is no contact between the thin wires, and The line shape disorder (thinning or thickening) is also 5% or more and less than 10%. Δ: Fine line breakage (breakage), no contact between the thin lines, and line shape disorder (thinning or thickening) is 10% or more. Less than 30% ×: Fine line chipping (disconnection) or contact between thin lines is recognized, and line shape disorder (thinning or thickening) is 30% or more [Evaluation of film thickness uniformity]
The formed 10 mm × 10 mm square metal pattern was cut with a microtome, the cross section was observed with an optical microscope, and the film thicknesses at 50 arbitrary points were measured. When the film thickness was less than 1 μm, the film thickness was measured using a scanning electron microscope.

  Subsequently, the average film thickness T and the variation in film thickness were measured, and the film thickness uniformity was evaluated according to the following criteria.

Average film thickness T (μm) = (T1 + T2 +... + T50) / 50 × 100
In the formula, T1, T2,... Represent the film thickness at the first measurement position, the film thickness at the second measurement position,.

Film thickness variation = {(maximum film thickness−minimum film thickness) / average film thickness} × 100
A: Film thickness variation is less than 2% B: Film thickness variation is 2% or more and less than 5% Δ: Film thickness variation is less than 10 μm and film thickness variation is 5% or more X: Film thickness variation is 5% or more [Evaluation of adhesion]
A metal pattern having a size of 10 mm × 10 mm was formed by the method for forming each metal pattern. The adhesion of the metal pattern was evaluated by a tape peeling test according to JIS C5600. Specifically, notches in a grid pattern of 25 mm in length and width at intervals of 2 mm were formed with a cutter, and cellophane tape was attached from above the grid pattern. When the tape was peeled off, the number of pieces peeled off to the tape side was counted and evaluated according to the following rank, and used as an index of adhesion.

A: The peeled metal pattern is not recognized. B: The peeled metal pattern is recognized, but the number of occurrence is less than 5%. C: The peeled metal pattern is recognized, but the number of occurrence is 5% or more and less than 9%. D: Although a peeled metal pattern is observed, the number of occurrences is 9% or more and less than 13%. E: A peeled metal pattern is recognized and the number of occurrences is 13% or more. A rank C or higher in both adhesion was evaluated as a practically favorable range.

  Table 2 shows the evaluation results obtained as described above.

  As is clear from the results shown in Table 2, it can be seen that the metal wiring pattern of the present invention is excellent in fine line delineability and film thickness uniformity as compared with the comparative example.

Claims (7)

  In a metal pattern forming ink used for printing a pattern portion by ink jet ink containing a catalyst on a substrate and forming a metal pattern on the pattern portion by electroless plating, the catalyst is palladium An ink for forming a metal pattern, comprising a metal salt and a complexing agent, wherein a complex is formed by the palladium metal salt and the complexing agent.   2. The metal pattern forming ink according to claim 1, wherein the molar ratio of the palladium metal salt to the complexing agent is 1: 0.5 or more and 1:10 or less.   3. The metal pattern forming ink according to claim 1, wherein the concentration of the palladium metal salt is 0.01% by mass or more and 1.0% by mass or less.   4. The metal pattern forming ink according to claim 1, wherein the complexing agent is an amine compound or a nitrogen-containing heterocyclic compound. 5.   The metal pattern forming ink according to any one of claims 1 to 4, wherein the pH is 9.0 or more and 13.5 or less.   6. The metal pattern forming ink according to claim 1, wherein the organic solvent is contained in an amount of 5.0% by mass to 90% by mass with respect to the ink.   A metal pattern formed using the metal pattern forming ink according to claim 1.