WO2013141174A1

WO2013141174A1 - Conductive ink, base material including conductor, and production method for base material including conductor

Info

Publication number: WO2013141174A1
Application number: PCT/JP2013/057527
Authority: WO
Inventors: 智柏原; 平社　英之; 米田　貴重
Original assignee: 旭硝子株式会社
Priority date: 2012-03-22
Filing date: 2013-03-15
Publication date: 2013-09-26
Also published as: JP2015110683A; TW201343823A

Abstract

Provided is a conductive ink having no ink residue on a liquid-repellant section, even if printed upon a lyophilic/lyophobic pattern and forming wiring having a wiring width of no more than 50 µm. Also provided is a production method for a base material including a conductor, suitable for the formation of highly reliable wiring, without ink residue on the liquid-repellant section. The conductive ink includes: a dispersion solvent including a main solvent being a non-aqueous organic solvent, and an added solvent having a boiling point greater than the boiling point of the main solvent, and having a surface tension at 20°C of 35-73 dyn/cm; and copper hydride fine particles dispersed in the dispersion solvent.

Description

Conductive ink, base material with conductor, and method for manufacturing base material with conductor

The present invention relates to a conductive ink, a base material with a conductor, and a method for manufacturing a base material with a conductor.

As a method for forming a wiring having a predetermined pattern used in an electronic circuit or an integrated circuit, a conductive ink made of a dispersion liquid in which fine metal particles such as silver and copper are dispersed in a solvent is printed on a substrate by ink jet printing. A method of forming a conductor by printing by a method such as the above and heating is known. In this ink jet method, a pattern liquid material (functional liquid) is directly arranged on a substrate, and then a desired pattern is formed by heat treatment or laser irradiation, or a lyophilic region and a liquid repellent region There is a method of forming a desired pattern by applying a functional liquid on a substrate provided with the above pattern (hereinafter also referred to as a lyophilic liquid repellent pattern). These methods are advantageous in that the process is greatly simplified and the raw material can be directly arranged at the pattern position.

In recent years, the density of circuits constituting a device has been increased, and further miniaturization and thinning of wiring have been required. However, in the pattern forming method using the conductive ink described above, it is difficult to stably form a fine pattern because droplets spread on the substrate. In particular, since the pattern is a conductor, a liquid pool (bulge) or a residue is generated due to the spread of the above-described droplets, which may cause problems such as disconnection or short circuit.

For such a problem, for example, Patent Document 1 discloses a method of forming a flat pattern by curing each time one droplet is applied. In Patent Document 2, in droplet printing by an inkjet method, a substrate on which a pattern is formed is surface-treated with a low-boiling liquid containing fluorine, and the surface energy is temporarily lowered to spread ink droplets. A method of suppressing this is disclosed. Patent Document 3 discloses a method of forming a lyophilic liquid repellent pattern by controlling the concentration of a component that exhibits liquid repellency contained in a coating liquid that imparts liquid repellency to the surface of a substrate or the like. . However, when the wiring is formed using these methods, the conductive ink 4 is applied on the lyophilic liquid-repellent pattern having the lyophilic part 3 and the lyophobic part 2, as shown in FIG. Even when it is formed, there is a problem that the conductive ink residue 5 is generated in the liquid repellent portion 2 because the surface tension of the conductive ink is not sufficient.

Japanese Unexamined Patent Publication No. 2007-329446 Japanese Unexamined Patent Publication No. 2008-31648 Japanese Unexamined Patent Publication No. 2009-255007

The present invention has been made in order to solve the above problem. Even when a wiring having a wiring width of 50 μm or less is formed by printing on a lyophilic liquid repellent pattern, there is no ink residue in the liquid repellent portion, and the volume is reduced. An object of the present invention is to provide a conductive ink capable of forming a conductor having a low resistivity.
Another object of the present invention is to provide a method for producing a substrate with a conductor that is suitable for forming a highly reliable wiring having no ink residue in the liquid repellent portion.

The present invention provides the following conductive ink, substrate with conductor, and method for producing a substrate with conductor.
(1) a main solvent which is a water-insoluble organic solvent;
A dispersion solvent comprising: an additive solvent having a boiling point exceeding the boiling point of the main solvent and having a surface tension at 20 ° C. of 35 to 73 dyn / cm;
Copper hydride fine particles dispersed in the dispersion solvent;
A conductive ink comprising:
(2) The conductive ink according to (1), wherein a content ratio of the additive solvent is 0.2 to 10.0% by mass with respect to the main solvent.
(3) The conductive ink according to (1) or (2), wherein the content ratio of the copper hydride fine particles is 10 to 50% by mass of the entire conductive ink.
(4) The conductive ink according to any one of (1) to (3), wherein the content ratio of the main solvent is 40 to 90% by mass of the entire conductive ink.
(5) The conductive ink according to any one of (1) to (4), wherein the copper hydride fine particles have an average primary particle diameter of 5 to 100 nm.
(6) The conductive ink according to any one of (1) to (5) is used on the surface of a polymer film having a pattern of a lyophilic region and a liquid repellent region formed on a substrate. A base material with a conductor, characterized in that it has a conductor formed.

(7) preparing a substrate;
Forming a polymer film having a pattern of a lyophilic region and a liquid repellent region on the substrate;
Forming a conductive ink coating layer according to any one of (1) to (5) on the surface of the polymer film;
And a step of heating the coating layer to form a conductor containing copper.

When the conductive ink of the present invention is printed on a polymer film having a lyophilic liquid repellent pattern to form a wiring having a wiring width of 50 μm or less, there is no ink residue in the liquid repellent portion, and a conductor can be accurately formed. . The method for producing a substrate with a conductor of the present invention can produce a substrate with a conductor having a small volume resistivity and no ink residue in the liquid repellent part.

It is a figure which shows typically the case where a conductor is formed in the lyophilic liquid repellent pattern surface with the conductive ink of this invention. It is a figure which shows typically the case where a conductor is formed in the lyophilic liquid repellent pattern surface with the conventional conductive ink.

Hereinafter, embodiments of the present invention will be described. Note that the present invention is not limited to the embodiments described below.

The conductive ink of the present invention comprises a main solvent which is a water-insoluble organic solvent, and an additive solvent having a boiling point exceeding the boiling point of the main solvent and having a surface tension at 20 ° C. of 35 to 73 dyn / cm. A dispersion solvent containing the copper hydride fine particles dispersed in the dispersion solvent. Therefore, as schematically shown in FIG. 1, the conductive ink 4 of the present invention is conductive when printed on a lyophilic liquid repellent pattern having a liquid repellent part 2 and a lyophilic part 3 on a substrate 1. The ink 4 stays on the lyophilic portion 3, and a conductor can be formed without causing ink residue in the lyophobic portion 2.

In the conductive ink of the present invention, the solvent in which the copper hydride fine particles are dispersed includes a main solvent having a relatively low boiling point and an additive solvent having a boiling point higher than that of the main solvent. Therefore, the additive solvent having a high boiling point is concentrated in the process of heating the coating layer of the conductive ink, and sufficient surface tension is imparted to the conductive ink. This surface tension prevents the ink from spreading and stays in the lyophilic region on the surface of the polymer film having the lyophilic liquid repellent pattern, and a conductor can be formed without leaving a residue in the liquid repellent region. In the present specification, the “lyophilic region” may be referred to as “lyophilic portion”, and the “liquid repellent region” may be referred to as “liquid repellent portion”.
Hereinafter, each component contained in the conductive ink of the embodiment will be described.

<Copper hydride fine particles>
The copper hydride fine particles become a conductive component of the conductive ink of the embodiment.
As the copper hydride fine particles, it is preferable to use copper hydride fine particles in a copper hydride fine particle dispersion produced by a method to be described later, but it is not limited thereto. In addition, since the copper hydride fine particle dispersion produced by the method described later contains not only the copper hydride fine particles but also an alkylamine having a boiling point of 250 ° C. or less, which is a protective agent, the copper hydride fine particles. The conductive ink of the present invention can be obtained by using the dispersion as it is. A method for preparing the conductive ink of the present invention using the copper hydride fine particle dispersion will be described later.

The average primary particle size of the copper hydride fine particles (primary particles) is preferably 5 to 100 nm, more preferably 5 to 70 nm, and particularly preferably 5 to 35 nm. If the average primary particle diameter of the copper hydride fine particles is 100 nm or less, the sinterability at a low temperature, which is a feature of the fine particles, becomes good, and the volume resistivity of the obtained conductor can be lowered. Moreover, if the average primary particle diameter of the copper hydride fine particles is 5 nm or more, the copper hydride fine particles can be stably dispersed.
The average primary particle size of the copper hydride fine particles was determined by measuring the particle size of 100 randomly extracted fine particles using a transmission electron microscope (TEM) or a scanning electron microscope (SEM). This is a value obtained by averaging the values of.

The content (concentration) of copper hydride fine particles as a solid content in the conductive ink is preferably 10 to 70% by mass. More preferably, it is 15 mass% or more, More preferably, it is 20 mass% or more. More preferably, it is 60 mass% or less, More preferably, it is 50 mass% or less, More preferably, it is 40 mass% or less. In the conductive ink, when the content (concentration) of the copper hydride fine particles as a solid content is 10% by mass or more, it is easy to form a conductor having a sufficient thickness. If the content ratio of the copper hydride fine particles is 70% by mass or less, it is easy to control ink characteristics such as viscosity and surface tension, and it becomes easy to form a conductor.

<Method for producing copper hydride fine particle dispersion>
The dispersion containing the copper hydride fine particles contained in the conductive ink of the present invention contains a copper (II) salt with a hydride reducing agent in the presence of an alkylamine (B) in a solvent (A) described below. It is preferably obtained by a reduction method. Hereinafter, this manufacturing method will be described.

As the copper (II) salt, a salt capable of forming an alkylamine (B) and a copper (II) amine complex can be used. The copper (II) salt may be an anhydride or a hydrate.
The copper (II) salt is represented by CuX ₂ or CuY. Here, X is a monovalent base and Y is a divalent base. When this copper (II) salt is reduced by a hydride-based reducing agent to produce copper hydride fine particles, it is considered that X contained in the copper (II) salt is liberated as HX and Y as H ₂ Y. In the present invention, it is preferable to use a salt in which the boiling point or decomposition point of this liberated HX or H ₂ Y (hereinafter also referred to as free acid) is 150 ° C. or less. This is because the free acid produced by the reduction of the copper (II) salt is likely to volatilize during heating during conductor formation, and easily forms a conductor with a low volume resistivity.

Examples of the copper (II) salt include copper oxalate (II) (decomposition point of liberated oxalic acid: 189.5 ° C.), copper chloride (II) (boiling point of liberated hydrochloric acid 110 ° C.), copper acetate (II ) (Boiling point of free acetic acid: 118 ° C.), copper (II) formate (boiling point of free formic acid: 100.75 ° C.), copper (II) nitrate (boiling point of free nitric acid: 82.6 ° C.), copper sulfate (II) (boiling point of free sulfuric acid: 290 ° C), copper (II) tartrate (boiling point of free tartaric acid, decomposition point: unknown), copper (II) citrate (decomposition point of free citric acid: 175 ° C) , Copper carbonate (II), and copper (II) oleate (boiling point of liberated oleic acid: 193 ° C./100 Pa, decomposition point: 400 ° C. or higher). Of these, copper (II) acetate, copper (II) formate, copper (II) nitrate, and copper (II) carbonate are preferred.
A copper (II) salt may be used individually by 1 type, and may use 2 or more types together.

Examples of hydride-based reducing agents include NaBH ₄ , LiBH ₄ , Zn (BH ₄ ) ₂ , (CH ₃ ) ₄ NBH (OCOCH ₃ ) ₃ , NaBH ₃ CN, LiAlH ₄ , (i-Bu) ₂ AlH (DIBAL ), LiAlH (t-BuO) ₃ , NaAlH ₂ (OCH ₂ CH ₂ OCH ₃ ) ₂ (Red-Al), and the like. Among these, at least one selected from the group consisting of NaBH ₄ , LiBH ₄ , and NaBH ₃ CN is preferable because the reduction rate, which is important for controlling the particle size of the copper hydride fine particles, can be easily adjusted.
A hydride type reducing agent may be used individually by 1 type, and may use 2 or more types together.

The solvent (A) is a solvent having an SP value of 8 to 12. When the SP value is 8 to 12, the compatibility between the solvent (A) and water is low, and the mixing of water into the reaction system can be suppressed. Thereby, it can suppress that the hydride type | system | group reducing agent melt | dissolved in the solvent (A) reacts with water and inactivates.
The SP value of the solvent (A) is more preferably 8.5 to 9.5.

Examples of the solvent (A) include cyclohexane (SP value 8.2), isobutyl acetate (SP value 8.3), isopropyl acetate (SP value 8.4), butyl acetate (SP value 8.5), and tetrachloride. Carbon (SP value 8.6), ethylbenzene (SP value 8.8), xylene (SP value 8.8), toluene (SP value 8.9), ethyl acetate (SP value 9.1), tetrahydrofuran (SP value) 9.1), benzene (SP value 9.2), chloroform (SP value 9.3), methylene chloride (SP value 9.7), carbon disulfide (SP value 10.0), acetic acid (SP value 10. 1), pyridine (SP value 10.7), dimethylformamide (SP value 12.0) and the like.

Further, as the solvent (A), a solvent inert to the hydride reducing agent used for the reduction reaction is used. That is, as the solvent (A), a solvent that is not reduced by the hydride reducing agent used in the reduction reaction or a solvent that does not have active hydrogen is preferable because it can suppress the inactivation of the hydride reducing agent.

As the solvent (A), hydrocarbons such as toluene, xylene, and benzene; ethers such as tetrahydrofuran; ethyl acetate, from the viewpoint of easy control of the reduction reaction and dispersibility of the produced copper hydride fine particles. Esters such as isopropyl acetate and isobutyl acetate are preferred, and toluene and xylene are particularly preferred.
A solvent (A) may be used individually by 1 type, and may use 2 or more types together.

Further, hydride-based reducing agents have different reducing power depending on the type. For example, NaBH ₄ does not reduce esters, whereas LiAlH ₄ reduces esters. Therefore, an appropriate solvent is selected from the solvent (A) depending on the type of hydride-based reducing agent used.

The alkylamine (B) is an alkylamine having an alkyl group having 7 or more carbon atoms and having a boiling point of 250 ° C. or lower.
If the carbon number of the alkyl group in the alkylamine (B) is 7 or more, the dispersibility of the produced copper hydride fine particles will be good. In the present invention, since the reaction field is an organic phase, it is not necessary to use an alkylamine having a large carbon number for the purpose of protection from water. The number of carbon atoms of the alkyl group in the alkylamine (B) is preferably 11 or less from the viewpoint of suppressing the boiling point from becoming too high.

If the boiling point of the alkylamine (B) is 250 ° C. or less, the alkylamine (B) is detached from the surface of the fine particles and volatilizes to form a conductor with a low volume resistivity when the conductor is formed using the conductive ink. it can. The boiling point of the alkylamine (B) is preferably 250 ° C. or less, and more preferably 200 ° C. or less, from the viewpoint of desorption and volatility during heating. Moreover, the boiling point of the alkylamine (B) is usually preferably 150 ° C. or higher from the viewpoint that the alkyl group has 7 or more carbon atoms.

The alkyl group of the alkylamine (B) is preferably a linear alkyl group from the viewpoint of dispersion stability of the obtained copper hydride fine particles. However, the alkyl group of the alkylamine (B) may be a branched alkyl group.

Examples of the alkylamine (B) include n-heptylamine (alkyl group having 7 carbon atoms and a boiling point of 157 ° C.), n-octylamine (alkyl group having 8 carbon atoms and a boiling point of 176 ° C.), n-nonylamine (carbon of the alkyl group). (9, boiling point: 201 ° C.), 1-aminodecane (alkyl group having 10 carbon atoms, boiling point: 220 ° C.), 1-aminoundecane (alkyl group having 11 carbon atoms, boiling point: 242 ° C.), n-heptylamine, n- Octylamine is more preferred.
An alkylamine (B) may be used individually by 1 type, and may use 2 or more types together.

In such a method for producing a copper hydride fine particle dispersion, copper hydride fine particles are generated by reducing a copper (II) salt with a hydride-based reducing agent in the presence of an alkylamine (B). In the presence of alkylamine (B), after alkylamine (B) is coordinated to copper (II) to form a copper (II) amine complex, the copper (II) amine complex is formed by a hydride reducing agent. Reduced. Thereby, formation of the copper hydride lump by rapid reduction of the copper (II) salt can be suppressed, and copper hydride fine particles in which alkylamine (B) is coordinated on the surface of the copper hydride fine particles are generated.

Moreover, in this manufacturing method, since the solubility with respect to the solvent (A) of a hydride type | system | group reducing agent is not so high, most of a hydride type | system | group reducing agent exists in a solvent (A) in a solid state, and a part is solvent (A ) Is dissolved in. When the hydride reducing agent dissolved in the solvent (A) reduces and consumes the copper (II) salt, the hydride reducing agent present in a solid state gradually dissolves in the solvent (A). And since the hydride type | system | group reducing agent which melt | dissolved in the solvent (A) gradually contributes to a reduction reaction, a reduction reaction does not advance rapidly but a copper hydride microparticles | fine-particles produce | generate stably.
The produced copper hydride fine particles can be dispersed in the solvent (A) because the alkylamine (B) is coordinated on the surface.

The order of adding the copper (II) salt, hydride reducing agent, and alkylamine (B) to the solvent (A) is preferably the order of alkylamine (B), copper (II) salt, and hydride reducing agent. Thereby, after the said copper (II) amine complex is formed, reduction | restoration by the hydride type | system | group reducing agent of this copper (II) amine complex becomes easy to advance, and copper hydride microparticles | fine-particles are obtained more stably.
However, the order of adding the copper (II) salt, the hydride reducing agent, and the alkylamine (B) to the solvent (A) is the order in which the reduction reaction with the hydride reducing agent proceeds in the presence of the alkylamine (B). If there is, the order is not limited. For example, the alkylamine (B), the hydride reducing agent, and the copper (II) salt may be added to the solvent (A) in this order. In this case, the hydride reducing agent is present in a solid state in the solvent (A), and after the copper (II) amine complex is formed in the solvent (A), the copper (II) present in the solid state. ) Amine complex reacts with hydride reducing agent. Further, a hydride reducing agent, an alkylamine (B), and a copper (II) salt may be added in this order.

The reduction reaction with the hydride-based reducing agent may be performed while stirring the solvent (A). This facilitates the reduction reaction.
The reaction temperature is preferably 0 to 80 ° C, more preferably 15 to 50 ° C. If reaction temperature is 0 degreeC or more, a reductive reaction will advance easily. If reaction temperature is 80 degrees C or less, the dispersibility of the copper hydride microparticles in the obtained copper hydride microparticle dispersion liquid will be favorable, As a result, it will become easy to form a conductor with small volume resistivity.

The addition amount of the copper (II) salt is preferably 0.1 × 10 ⁻³ mol or more with respect to 1 g of the solvent (A) from the viewpoint of productivity of copper hydride fine particles, and preferably 0.15 × 10 ^−3. Mole or more is more preferable, and 0.25 × 10 ⁻³ mol or more is particularly preferable. Further, the addition amount of the copper (II) salt is preferably 0.65 × 10 ⁻³ mol or less with respect to 1 g of the solvent (A) from the viewpoint of easy control of the reduction reaction, and 0.6 × 10 ^{− 3} mol or less is more preferable, and 0.5 × 10 ⁻³ mol or less is particularly preferable.

The addition amount of the alkylamine (B) is 0.2 × 10 ^{− with} respect to 1 g of the solvent (A) because the dispersibility of the copper hydride fine particles in the obtained copper hydride fine particle dispersion becomes good. ³ mol or more is preferable, 0.25 × 10 ⁻³ mol or more is more preferable, and 0.3 × 10 ⁻³ mol or more is particularly preferable. In addition, if the amount of alkylamine (B) added is excessive, alkylamine (B) that could not be coordinated to the copper (II) salt may remain at the time of conductor formation and increase the volume resistivity of the conductor. is there. Therefore, the upper limit of the amount of the alkylamine (B) is preferably 0.75 × 10 ⁻³ mol or less, more preferably 0.7 × 10 ⁻³ mol or less, with respect to 1 g of the solvent (A). 6 × 10 ⁻³ mol or less is particularly preferable.

The addition amount of the hydride-based reducing agent is preferably 0.25 × 10 ⁻³ mol or more with respect to 1 g of the solvent (A) from the viewpoint of the yield of copper hydride fine particles, preferably 0.3 × 10 ⁻³ mol. The above is more preferable, and 0.35 × 10 ⁻³ mol or more is particularly preferable. The amount of the hydride reducing agent added is preferably 0.65 × 10 ⁻³ mol or less with respect to 1 g of the solvent (A) from the viewpoint of easy control of the reduction reaction, preferably 0.55 × 10 ^−3. The molar amount is more preferably less than or equal to 0.5 × 10 ⁻³ mol or less.

The molar ratio of the copper (II) salt and the alkylamine (B) added to the solvent (A) (hereinafter referred to as Cu / alkylamine) is that the dispersion stability of the produced copper hydride fine particles is good. Therefore, 1.8 or less is preferable, 1.4 or less is more preferable, and 1.2 or less is particularly preferable. Further, the molar ratio (Cu / alkylamine) is preferably 0.64 or more from the viewpoint of easy desorption and volatilization of the alkylamine (B) from the surface of the fine particles by heating during conductor formation, The above is more preferable.

The molar ratio of the copper (II) salt added to the solvent (A) and the hydride reducing agent (R) (hereinafter referred to as Cu / hydride reducing agent) is 1.42 in that the reduction reaction easily proceeds. The following is preferable, 1.3 or less is more preferable, and 1.2 or less is particularly preferable. The molar ratio (Cu / hydride-based reducing agent) is preferably 0.7 or more, more preferably 0.8 or more, and particularly preferably 0.9 or more, from the viewpoint of easy control of the reduction reaction.

In this way, a copper hydride fine particle dispersion in which copper hydride fine particles (primary particles) having an average primary particle diameter of 5 to 100 nm, more preferably 5 to 70 nm, particularly preferably 5 to 35 nm are dispersed in the solvent (A) is obtained. It is done. The average primary particle diameter of the copper hydride fine particles can be adjusted by the addition amount of the alkylamine (B) and the addition amount of the hydride reducing agent. By increasing the addition amount of the alkylamine (B), the average primary particle diameter of the copper hydride fine particles tends to decrease. Moreover, there exists a tendency for the average primary particle diameter of a copper hydride microparticle to become small by reducing the addition amount of a hydride type | system | group reducing agent.

The concentration of the copper hydride fine particles as a solid content in the obtained copper hydride fine particle dispersion is preferably 1 to 6% by mass, more preferably 2.5 to 4.5% by mass, based on 100% by mass of the entire dispersion. . When the solid content concentration of the copper hydride fine particles in the copper hydride fine particle dispersion is less than 1% by mass, the concentration process takes time, and the productivity may be lowered. If the copper hydride fine particle solid content concentration of the copper hydride fine particle dispersion exceeds 6% by mass, the dispersion stability of the copper hydride fine particles in the dispersion may be lowered.

<Dispersion solvent>
The dispersion solvent of the conductive ink of the embodiment includes a main solvent (S) and an additive solvent (s). As the dispersion solvent, a solvent of the copper hydride fine particle dispersion obtained by the above production method (solvent (A) which is a solvent having an SP value of 8 to 12) may be used, and other solvent ( That is, a solvent having an SP value of less than 8 or more than 12. Hereinafter, the solvent (C) may be used. That is, the conductive ink of the present invention can be obtained by adjusting the solid content concentration and viscosity of the copper hydride fine particle dispersion produced by the production method.

Further, by replacing the solvent of the copper hydride fine particle dispersion obtained by the above production method, that is, for example, replacing the solvent (A) with the solvent (C), and further adjusting the solid content concentration and viscosity, The conductive ink of the invention can be obtained. In this case, the solvent (A) may contain the main solvent (S), and may contain the addition solvent (s). Similarly, the solvent (C) may contain the main solvent (S), and may contain the added solvent (s). In any case, the conductive ink of the present invention directly contains the alkylamine (B) that functions as a dispersant that functions to disperse the copper hydride fine particles in a solvent or as a protective agent.

As a method of replacing the solvent (A) of the copper hydride fine particle dispersion with the solvent (C), a known solvent replacement method can be employed. For example, the solvent (C) is added while concentrating the solvent (A) under reduced pressure. The method of doing is mentioned.

(Main solvent)
As the main solvent (S) of the conductive ink of the embodiment of the present invention, a water-insoluble organic solvent is used. In the present specification, “water-insoluble” means that the amount dissolved in 100 g of water at room temperature (20 ° C.) is 0.5 g or less. The main solvent (S) is preferably an organic solvent having a small polarity from the viewpoint of affinity with the alkylamine (B). In addition, the main solvent (S) is preferably one that does not cause thermal decomposition by heating when forming the conductor.

Examples of the main solvent (S) include decane (insoluble in water), dodecane (insoluble in water), tetradecane (insoluble in water), decene (insoluble in water), dodecene (insoluble in water), and the like. Tetradecene (insoluble in water), dipentene (dissolved in 100 g of water 0.001 g (20 ° C.)), α-terpineol (dissolved in 100 g of water 0.5 g (20 ° C.)), mesitylene (in water) Insoluble.), Non-aromatic solvents for printing inks, and commercially available petroleum hydrocarbon solvents such as mineral spirits. Of these, α-terpineol, decane, dodecane, and tetradecane are preferable because the drying property and the coating property of the conductive ink can be easily controlled.
A main solvent (S) may be used individually by 1 type, and may use 2 or more types together.
The content of the main solvent (S) is preferably 40 to 90% by mass, particularly preferably 50 to 80% by mass, based on 100% by mass of the entire conductive ink, from the viewpoint of dispersibility of each component contained in the conductive ink.

(Addition solvent)
The conductive ink of the present invention contains an additive solvent (s) as a dispersion medium for copper hydride fine particles. The added solvent (s) may be added to the main solvent (S) when replacing the solvent in the course of producing the copper hydride fine particle dispersion, or may be added after replacing the solvent. Moreover, the solvent (A) may contain the addition solvent (s), and in this case, the solvent concentration of the copper hydride fine particle dispersion produced by the production method can be adjusted and obtained.

The added solvent (s) has a boiling point exceeding the boiling point of the main solvent, which is a water-insoluble organic solvent, and has a surface tension of 35 to 73 dyn / cm at 20 ° C.
When the conductive ink of the present invention is heated to form the conductor by adding the solvent (s) to the polymer film having a lyophilic liquid-repellent pattern on the substrate, the main solvent having a relatively low boiling point evaporates. In the process, it remains in the dispersion solvent and concentrates, and functions to impart surface tension to the conductive ink. Therefore, the added solvent (s) has a boiling point exceeding that of the main solvent.

The added solvent (s) has a surface tension of 35 dyn / cm or more at 20 ° C., preferably 40 dyn / cm or more, and more preferably 45 dyn / cm or more. When the surface tension at 20 ° C. is less than 35 dyn / cm, the surface tension of the conductive ink is not sufficient, and there is a possibility that an ink residue may remain. The ink residue causes disconnection, short circuit, and migration of the conductor wiring formed from the conductive ink. From the viewpoint of easy availability, the added solvent (s) has a surface tension at 20 ° C. of 73 dyn / cm or less. The surface tension is a value measured with a surface tension meter (manufactured by Kyowa Interface Science Co., Ltd., device name: DY-500).

Examples of such additional solvent (s) include pyrrolidone, N-methylpyrrolidone, imidazole, 1-methylimidazole, 1,3-dimethylimidazole, butanediol, glycerin, ethylene glycol, diethylene glycol, triethylene glycol, formamide, and triethanol. Examples include amines, triethylene glycol monomethyl ether, and triethylene glycol monoethyl ether. These additive solvents (s) may be used individually by 1 type, and may use 2 or more types together.
As the additive solvent (s), glycerin, ethylene glycol, and diethylene glycol are particularly preferred from the viewpoints of handleability and availability.
The content of the added solvent (s) is preferably 0.2 to 10.0% by mass, particularly preferably 0.5 to 5.0% by mass with respect to the main solvent (S). When the content ratio of the additive solvent (s) is 0.2% by mass or more, sufficient surface tension can be imparted to the conductive ink, and when it is 10.0% by mass or less, the coating property of the conductive ink is excellent.

The conductive ink according to the embodiment of the present invention is a protective agent for dispersing copper hydride fine particles, which are conductive components, in the dispersion solvent in addition to the main solvent (S), the additive solvent (s), and the copper hydride fine particles. And may contain an alkylamine.
When the copper hydride fine particle dispersion produced by the production method is used as it is or by replacing the solvent to obtain the conductive ink of the embodiment, the alkylamine (B) added in the production process is used in the conductive ink. Becomes a protective agent. In the conductive ink of this invention, it is not limited to such an aspect, You may add an alkylamine as a protective agent separately.

The conductive ink of the present invention may contain a silane coupling agent and other additives in addition to the main solvent, additive solvent, copper hydride fine particles, and alkylamine. Examples of other additives include antifoaming agents, wetting and dispersing agents, leveling agents, anti-drying agents, rheology control agents, and adhesion imparting agents.

The concentration of the solid content (copper hydride fine particle solid content) of the conductive ink of the present invention varies depending on the required viscosity, but is preferably 10 to 70% by mass based on 100% by mass of the entire conductive ink. More preferably, it is 15 mass% or more, More preferably, it is 20 mass% or more. More preferably, it is 60 mass% or less, More preferably, it is 50 mass% or less, More preferably, it is 40 mass% or less. When the solid content concentration of the copper hydride fine particles in the conductive ink is 10% by mass or more, it is easy to form a conductor having a sufficient thickness. When the solid content concentration of the copper hydride fine particles in the conductive ink is 70% by mass or less, it is easy to control ink characteristics such as viscosity and surface tension, and it becomes easy to form a conductor.

The viscosity of the conductive ink of the present invention is preferably 5 to 60 mPa · s, more preferably 8 to 40 mPa · s. If the viscosity of the conductive ink is 5 mPa · s or more, the ink can be ejected with high accuracy. If the viscosity of the conductive ink is 60 mPa · s or less, it can be applied to almost all available inkjet heads.

The surface tension of the conductive ink of the present invention at 20 ° C. is preferably 20 to 45 dyn / cm, more preferably 25 to 40 dyn / cm. If the surface tension of the conductive ink is not less than the lower limit of the above range, the ink can be ejected with high accuracy. If the surface tension of the conductive ink is not more than the upper limit of the above range, it can be applied to almost all available inkjet heads.
In this specification, the viscosity of the conductive ink is a value measured at 20 ° C. with a B-type viscometer (manufactured by Toki Sangyo Co., Ltd., apparatus name: TVB35L). The surface tension is a value measured by a surface tension meter (manufactured by Kyowa Interface Science Co., Ltd., device name: DY-500).

In the conductive ink of the present invention, when heated, the alkylamine bonded and coordinated to the surface of the copper hydride fine particles is released. Then, the copper hydride from which the alkylamine has been eliminated from the surface changes to, for example, metallic copper by heating at 60 ° C. or higher. The metallic copper fine particles generated in this way are melted and bonded to form a conductor.

<Manufacturing method of substrate with conductor>
The manufacturing method of the base material with a conductor of this invention has the following processes.
(1) A step of preparing a base material.
(2) A step of forming a polymer film having a pattern of a lyophilic region and a liquid repellent region on the substrate (hereinafter also referred to as a polymer film forming step).
(3) A step of applying the conductive ink of the present invention to the surface of the polymer film to form a coating layer (hereinafter also referred to as a coating step).
(4) A step of heating the coating layer to form a conductor containing copper (hereinafter also referred to as a conductor forming step).
In the step (4), the formed conductor is a conductor mainly composed of copper. Here, “a conductor mainly composed of copper” means that copper is most contained among the elements constituting the conductor.

(Base material)
Examples of the substrate include glass substrates, plastic substrates (PET substrates, PEN substrates, polyimide substrates, polycarbonate substrates, etc.), fiber reinforced composite materials (glass fiber reinforced plastic substrates, etc.), and the like.
The substrate used in the present invention has an acid treatment (treatment using diluted hydrofluoric acid, sulfuric acid, hydrochloric acid, etc.), alkali treatment (treatment using an aqueous sodium hydroxide solution) or the like depending on the purpose. Those subjected to ultrasonic cleaning or the like with pure water or an organic solvent may be used. Moreover, you may perform the passivation process (process which forms films | membranes, such as an oxide, on the base-material surface).
For example, a polymer film having a pattern of a lyophilic region and a liquid repellent region is formed on the surface of the substrate as follows.

(Polymer film forming process)
The polymer film is not particularly limited as long as it can form a lyophilic liquid repellent pattern. As the polymer film, a polyimide, epoxy resin, polyester resin, acrylic resin, fluororesin having a hydrophobic group in the side chain, a coating composition containing a curable composition capable of forming a lyophilic liquid-repellent pattern and a solvent is used. And a polymer film formed.

The thickness of the polymer film can be appropriately set according to the application, and is usually 0.1 to 100.0 μm, preferably 0.2 to 50.0 μm.

(Coating process)
Examples of the method for applying the conductive ink include offset gravure coating, direct gravure coating, roll coating, air doctor coating, blade coating, knife coating, spray coating, inkjet coating, spin coating, and slot die coating. Of these, inkjet coating and slot die coating are particularly preferable from the viewpoints of workability, yield of ink to be used, and positional accuracy of printing.

In the case of inkjet coating, the diameter of the ink ejection hole is set to 0.5 to 100 μm from the viewpoint of easy formation of a conductor having a desired pattern, and the diameter of the conductive ink when adhered on the substrate is set to 1 to 100 μm. It is preferable to make it.

The heating temperature after applying the conductive ink on the substrate is preferably 60 to 300 ° C, more preferably 60 to 150 ° C.
The heating time may be set according to the heating temperature so that the conductor can be formed by volatilizing the dispersion solvent, the acid released from the copper (II) salt, the alkylamine (B) released from the surface of the fine particles, and the like.
Moreover, it is preferable to perform heating in inert atmosphere, such as nitrogen atmosphere, from the point which is easy to suppress the oxidation of the conductor to form.

The thickness of the conductor is preferably 0.3 to 2.0 μm.
The volume resistivity of the conductor is preferably 3 to 35 μΩ · cm. The volume resistivity of the conductor was determined by measuring the surface resistance value of the conductor using a four-probe resistance meter (for example, manufactured by Mitsubishi Yuka Co., Ltd., device name: Loresta GP MCP-T610). It can be determined by multiplying the value by the conductor thickness.

According to the method for manufacturing a substrate with conductor described above, since the conductive ink that expresses sufficient surface tension during the heating process is used, a substrate with conductor having no conductor of ink and a conductor having a small volume resistivity is obtained. It is done.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples. Examples 1 to 3 are examples, and example 4 is a comparative example. Examples of identification of fine particles, measurement of average particle diameter of fine particles, measurement of conductor thickness, measurement of conductor volume resistivity, and method of conductor peelability test in Examples and Comparative Examples are shown below. .

[Identification of fine particles]
The identification of the fine particles was performed using an X-ray diffraction apparatus (manufactured by Rigaku Instruments Co., Ltd., apparatus name: RINT2500).

[Average particle size of fine particles]
The particle size of 100 randomly extracted fine particles was measured with a transmission electron microscope (manufactured by Hitachi, Ltd., device name: H-9000) or a scanning electron microscope (manufactured by Hitachi, Ltd., device name: S-800). The average particle size was determined by averaging the values.

[Conductor thickness]
It measured using the contact-type film thickness measuring apparatus (the product made by Veeco, apparatus name: DEKTAK150).

[Volume resistivity of conductor]
Using a four-probe resistance meter (manufactured by Mitsubishi Yuka Co., Ltd., apparatus name: Loresta GP MCP-T610), the surface resistance value of the conductor was measured. The volume resistivity was determined by multiplying the measured surface resistance value by the thickness of the conductor.

[Formation of polymer film having lyophilic liquid repellent pattern]
A photosensitive fluororesin (trade name: AL-X, manufactured by Asahi Glass Co., Ltd.) is spin-coated at 1,000 rpm for 30 seconds on the surface of a soda lime glass substrate, and heated for 20 minutes using a 150 ° C. hot plate. As a result, a polymer film having a thickness of 1 μm was formed.
The surface of the polymer film was partially irradiated with ultraviolet rays (i-line 365 nm) through a mask pattern to obtain a lyophilic liquid repellent pattern having a length of 5 cm and a width of 20 μm. For UV irradiation, the product name MA-8 manufactured by SUSS was used, and the irradiation condition was 100 J / cm ² .

[Example 1]
(Manufacture of copper hydride particles)
To a glass container, 300 g of toluene, 30 g of copper (II) formate tetrahydrate as a copper (II) salt, and 15 g of n-heptylamine (boiling point 157 ° C.) as an alkylamine were added and stirred. Next, 4.5 g of NaBH ₄ which is a hydride reducing agent was added and stirred to obtain a black dispersion liquid in which fine particles were dispersed in toluene.

When the fine particles in the obtained dispersion were collected and identified by X-ray diffraction, it was confirmed to be copper hydride fine particles. The average primary particle diameter of the copper hydride fine particles (primary particles) was 10 nm. Further, the solid content concentration of the obtained copper hydride fine particle dispersion was 4% by mass.

(Preparation of conductive ink)
The obtained copper hydride fine particle dispersion was subjected to solvent substitution under reduced pressure to prepare a conductive ink. That is, after the copper hydride fine particle dispersion was concentrated under reduced pressure, 2 mass% diethylene glycol (boiling point 244.8 ° C., 20 ° C.) was added to dodecane (boiling point 216.3 ° C., surface tension 25.4 dyn / cm at 20 ° C.). The solvent was replaced by adding a material having a surface tension of 48.5 dyn / cm), so that the solid content concentration of the copper hydride fine particles was 30% by mass.

(Formation of wiring pattern)
Using the conductive ink obtained above, printing was performed on the surface of the polymer film formed on the substrate by an industrial inkjet printer (manufactured by Fuji Film Graphic System Co., Ltd., device name: DMP2813). The substrate after printing was heated at 150 ° C. for 1 hour in a nitrogen atmosphere to obtain a substrate with a conductor. The thickness of the conductor was 0.31 μm, and the volume resistivity was 18 μΩ · cm.
After heating, the wiring width confirmed by SEM (imaging magnification: 5,000 times) was 20.5 μm, and no Cu residue was observed in the liquid repellent part.

[Example 2]
After concentration of the copper hydride fine particle dispersion shown in Example 1 under reduced pressure, 0.5 mass% glycerin (boiling point 290.0 ° C., surface tension 63.3 dyn / cm at 20 ° C.) was added to dodecane. In addition, solvent substitution was performed to prepare a conductive ink having a solid content concentration of copper hydride fine particles of 30% by mass.

Subsequently, using the obtained conductive ink, it printed on the polymer film surface in which the wiring pattern was formed like Example 1, and obtained the base material with a conductor. The thickness of the conductor was 0.35 μm, and the volume resistivity was 16 μΩ · cm.
After heating, the wiring width confirmed by SEM was 20.5 μm, and no Cu residue was observed in the liquid repellent part.

[Example 3]
After the copper hydride fine particle dispersion shown in Example 1 was concentrated under reduced pressure, decane (boiling point: 174.1 ° C., surface tension at 20 ° C .: 23.9 dyn / cm) was added to 2% by mass of ethylene glycol ((boiling point: 197.9). Then, the solvent was replaced by adding a surface tension of 46.5 dyn / cm) at 20 ° C., and a conductive ink having a solid content concentration of copper hydride fine particles of 30% by mass was prepared.

Subsequently, using the obtained conductive ink, it printed on the polymer film surface in which the wiring pattern was formed like Example 1, and obtained the base material with a conductor. The thickness of the conductor was 0.38 μm, and the volume resistivity was 12 μΩ · cm.
After heating, the wiring width confirmed by SEM was 20.5 μm, and no Cu residue was observed in the liquid repellent part.

[Example 4]
After the copper hydride fine particle dispersion shown in Example 1 was concentrated under reduced pressure, dodecane (boiling point 216.3 ° C., surface tension 25.4 dyn / cm at 20 ° C.) was added as a solvent, and the solid content of the copper hydride particles Solvent replacement was performed so that the concentration was 30% by mass.

Subsequently, using the obtained conductive ink, it printed on the polymer film surface in which the wiring pattern was formed like Example 1, and obtained the base material with a conductor. The thickness of the conductor was 0.36 μm, and the volume resistivity was 20 μΩ · cm.
After firing, the wiring width confirmed by SEM was 30.8 μm, and several Cu residues were confirmed in the liquid repellent part.

Table 1 shows the composition, surface tension, volume resistivity, and presence / absence of Cu residue in the liquid repellent portion of Examples 1 to 4.

From Table 1, it can be seen that Examples 1 to 3 use the conductive ink of the present invention, so that there is no residue in the liquid repellent part. Also, the volume resistivity is sufficiently small. On the other hand, in Example 4, since the conductive ink of the present invention was not used, a residue was confirmed in the liquid repellent portion.
Thus, by using the conductive ink of the present invention, it is possible to obtain a conductor wiring having a small volume resistivity and no residue in the liquid repellent part.

Although the invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
This application is based on Japanese Patent Application No. 2012-065119 filed on Mar. 22, 2012, the contents of which are incorporated herein by reference.

According to the conductive ink of the present invention, a conductor having no residue can be formed in the liquid repellent portion. Moreover, according to the manufacturing method of the base material with a conductor of this invention, there is no residue on a base material, a base material with a conductor with small volume resistivity can be manufactured, and it is used suitably as a highly reliable wiring board.

DESCRIPTION OF SYMBOLS 1 ... Base material, 2 ... Liquid repellent part, 3 ... Lipophilic part, 4 ... Conductive ink or the conductor formed with the conductive ink, 5 ... Residue of conductive ink

Claims

A main solvent which is a water-insoluble organic solvent;
A dispersion solvent comprising: an additive solvent having a boiling point exceeding the boiling point of the main solvent and having a surface tension at 20 ° C. of 35 to 73 dyn / cm;
Copper hydride fine particles dispersed in the dispersion solvent;
A conductive ink comprising:
The conductive ink according to claim 1, wherein a content ratio of the additive solvent is 0.2 to 10.0% by mass with respect to the main solvent.
The conductive ink according to claim 1 or 2, wherein a content ratio of the copper hydride fine particles is 10 to 50% by mass of the entire conductive ink.
The conductive ink according to any one of claims 1 to 3, wherein a content ratio of the main solvent is 40 to 90 mass% with respect to the entire conductive ink.
The conductive ink according to any one of claims 1 to 4, wherein the copper hydride fine particles have an average primary particle diameter of 5 to 100 nm.
A conductor formed using the conductive ink according to any one of claims 1 to 5 on a surface of a polymer film having a pattern of a lyophilic region and a liquid repellent region formed on a substrate. A base material with a conductor, comprising:
Preparing a substrate;
Forming a polymer film having a pattern of a lyophilic region and a liquid repellent region on the substrate;
Forming a conductive ink coating layer according to any one of claims 1 to 5 on the surface of the polymer film;
And a step of heating the coating layer to form a conductor containing copper.