JP2013129793A - Metal particle-containing ink and method for forming conductive pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal particle-containing ink having a low volume resistivity value even after having been coated on a substrate or the like and fired.SOLUTION: A metal particle-containing ink includes a metal particle, a metal particle dispersant, and a solvent. The metal particle dispersant is a polymer compound obtained by polymerizing a monomer represented by the following general formula (I). (In the general formula (I), Rrepresents a hydrogen atom or a methyl group, Rrepresents a hydrogen atom or a 1-4 C alkyl group, n represents a natural number, and x represents an integer of 1-3).

Description

  The present invention relates to a metal particle-containing ink and a method for forming a conductive pattern.

  As a pattern forming method of a functional material used for an electronic circuit or the like, a printing method such as an ink jet printing method is known in which a predetermined amount of metal particle-containing ink is supplied to a predetermined position on a substrate to form a pattern.

  The ink jet printing method is superior to the photolithography method in that it does not require large-scale equipment, the number of processes is small, and the material use efficiency is high.

  As an ink used in the inkjet printing method, a nano metal ink in which metal particles having a primary particle size of nano order are dispersed in a solvent is mainly used (for example, Patent Document 1). The nanometal ink is fused at the firing temperature to become a patterned conductor electrode.

  The nanometal ink such as Patent Document 1 contains a dispersion stabilizer containing an organic material so that metal fine particles do not aggregate in the solvent of the ink. The dispersion stabilizer contained is removed by being oxidized and / or decomposed by being heated after being applied to the substrate of the ink and dried. However, in the conventional removal of the dispersion stabilizer by heating, the dispersion stabilizer is not completely removed, and the dispersion stabilizer may remain in the substrate. When the dispersion stabilizer remains, there is a problem in that the fusion between the metal fine particles is inhibited at the time of firing and the voids increase, resulting in an increase in the volume resistance value.

  Accordingly, an object of the present invention is to provide a metal particle-containing ink having a small volume resistance value even after being applied to a substrate or the like and baked.

Metal particles, a metal particle dispersant, and a solvent,
The metal particle dispersant is a polymer compound obtained by polymerizing a monomer represented by the following general formula (I).
A metal particle-containing ink is provided.

（一般式（Ｉ）中、Ｒ_１は水素原子又はメチル基であり、Ｒ_１'は水素原子又は炭素数１〜４のアルキル基であり、ｎは自然数であり、ｘは１〜３の整数を表す。）

(In general formula (I), R ₁ is a hydrogen atom or a methyl group, R _{1 ′} is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, n is a natural number, and x is an integer of 1 to 3) Represents.)

  According to the present invention, it is possible to provide a metal particle-containing ink having a small volume resistivity even after being applied to a substrate or the like and baked.

  The present invention will be described in more detail by way of embodiments.

  The metal particle-containing ink of the present invention contains metal particles, a metal particle dispersant, and a solvent. First, each material will be described.

[Metal particle dispersant]
The metal particle dispersant contained in the metal particle-containing ink of the present invention is a polymer compound obtained by polymerizing a monomer (monomer) represented by the following general formula (1).

（一般式（Ｉ）中、Ｒ_１は水素原子又はメチル基であり、Ｒ_１'は水素原子又は炭素数１〜４のアルキル基であり、ｎは自然数であり、ｘは１〜３の整数を表す）。

(In general formula (I), R ₁ is a hydrogen atom or a methyl group, R _{1 ′} is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, n is a natural number, and x is an integer of 1 to 3) Represents).

  When the polymer compound obtained by polymerizing the monomer represented by the general formula (I) is used as a metal particle dispersant contained in the metal particle-containing ink, the metal particles are present in the state of primary particles in the dispersion. can do. That is, it is possible to obtain a dispersion having a small polydispersity and having metal particles having a particle size of primary particles. This effect can be obtained even when nanometer-sized metal particles that are very easily aggregated are used.

  The polymer compound (polymer) obtained by polymerizing the monomer represented by the general formula (I) has a polysiloxane moiety. Since this polysiloxane site becomes a side chain in the polymer, the polymer has a high steric effect. Therefore, metal particles are less likely to aggregate in the dispersion due to steric hindrance at the polysiloxane site.

  The metal particle-containing ink of the present invention is a copolymer obtained by adding a monomer having an ionic functional group and / or a nitrogen-containing heterocyclic group, which will be described later, in addition to the monomer represented by the general formula (I). It is preferable to use the polymer compound prepared as a metal particle dispersant. A copolymer obtained by copolymerizing the monomer represented by the general formula (I) and a monomer having an ionic functional group and / or a nitrogen-containing heterocyclic group described later is used as a metal particle dispersant. By this, adsorption to the copolymer on the surface of the metal particles is promoted. Further, the steric effect of the polysiloxane moiety due to the inclusion of the monomer represented by the general formula (I) described above is also maintained. As a result, the monomer having an ionic functional group and / or a nitrogen-containing heterocyclic group has a high effect of adsorbing metal fine particles (copper) or metal fine particles on the oxide film, and exhibits the effect when added in a small amount.

  Examples of the ionic functional group include an amino group, a carboxyl group, a sulfonyl group, and a phospho group.

  Examples of the monomer having an amino group include N-methylaminoethyl (meth) acrylate, N-ethylaminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) ) Acrylate, N, N-dibutylaminoethyl acrylate, N, N-di-tert-butylaminoethyl acrylate, N-phenylaminoethyl methacrylate, N, N-diphenylaminoethyl methacrylate, aminostyrene, dimethylaminostyrene, N- Methylaminoethylstyrene, dimethylaminoethoxystyrene, diphenylaminoethylstyrene, N-phenylaminoethylstyrene, 2-N-piperidylethyl (meth) acrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinyl Such as 6-methyl-pyridine.

  Monomers having a carboxyl group include (meth) acrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, fumaric acid, cinnamic acid, crotonic acid, vinyl benzoic acid, 2-methacryloxyethyl succinic acid 2-methacryloxyethyl maleic acid, 2-methacryloxyethyl hexahydrophthalic acid, 2-methacryloxyethyl trimellitic acid, and the like.

  Examples of the monomer having a sulfonyl group include vinyl sulfonic acid, allyl sulfonic acid, styrene sulfonic acid, and 2-acrylamido-2-methylpropane sulfonic acid.

  Examples of the monomer having a phospho group include (meth) acryloxypropylphosphonic acid.

  Moreover, it does not specifically limit as a monomer which has a nitrogen-containing heterocyclic group, For example, vinylpyrrolidone etc. can be used.

  The content ratio of each monomer in the copolymerization can be appropriately determined by those skilled in the art from the viewpoint of the balance between the adsorptivity of the dispersant to the metal particles and the cohesiveness of the metal particles. As a preferable content ratio, “the monomer represented by the general formula (I)”: “monomer having an ionic functional group and / or a nitrogen-containing heterocyclic group” = 90: 10-99.9: 0.1.

  The monomer represented by the general formula (I) is, for example, MCR-M07, M11, M17, M22 (manufactured by Gelest), x-22-2475, 2426 (manufactured by Shin-Etsu Chemical Co., Ltd.), Silaplane FM-0711, 0721, 0725 (manufactured by JNC Corporation) and the like can be used.

[solvent]
As the solvent used in the metal particle-containing ink, it is preferable to use a nonpolar organic solvent from the viewpoint of compatibility with the polysiloxane moiety contained in the monomer represented by formula (I). By using a nonpolar organic solvent as the solvent, the above-mentioned steric effect due to the polysiloxane moiety is increased, and the dispersion stability of the dispersion is increased.

  Nonpolar organic solvents include paraffinic hydrocarbons such as pentane, hexane, heptane, octane, nonane, decane, dodecane, and tetradecane; isoparaffinic hydrocarbons such as isohexane, isooctane, and isododecane; cycloolefin hydrocarbons such as cyclododecene Alkyl naphthenic hydrocarbons such as liquid paraffin; aromatic hydrocarbons such as benzene, toluene, xylene, alkyl benzene and solvent naphtha; dimethyl silicone oil, phenyl methyl silicone oil, dialkyl silicone oil, alkyl phenyl silicone oil, cyclic polydialkyl siloxane Or silicone-based oils such as cyclic polyalkylphenylsiloxanes.

[Metal particles]
Although it does not specifically limit as a metal particle, For example, copper is used from the electrical property of an ink.

[Distribution method]
The method for dispersing the metal particles in the solvent using the metal particle dispersant is not particularly limited, and the metal particles can be dispersed using a conventional dispersing device such as a homogenizer, a ball mill, a sand mill, or an attritor.

[Method of forming conductive pattern]
The method for forming a conductive pattern according to the present invention includes a coating process for applying the ink according to the present invention, and a sintering process for developing conductivity by sintering the ink.

  The application means in the application step is not particularly limited as long as it is a printing method using ink, but it is preferable to use an ink jet printing method from the viewpoint of realizing direct patterning.

  In the firing step, the interface between the particles disappears by sintering the ink and bonding the metal particles together. By this baking process, the conductivity of the ink is developed. The driving force for fusing the metal particles may be thermal energy, but the present invention is not limited to this.

  Specific examples of firing by energy other than thermal energy include firing by light energy (photo firing). The metal particles can be fired in the state of room temperature to low-temperature heating by irradiation with light energy. In addition, the low temperature here refers to a temperature at which the base material is not damaged by the irradiation heat, and is usually about 200 ° C. or lower although it varies depending on the material of the base material. The light source of light energy is not particularly limited, and for example, a xenon lamp can be used. In addition, it is preferable to evaporate by preheating a solvent in the case of light irradiation.

  In addition, the (thermal) firing step is preferably performed in a substantially oxygen-free atmosphere that is replaced with an inert gas such as nitrogen or argon. By performing firing in an oxygen-free atmosphere, it is preferable to oxidize the metal particles during and after firing, and the conductivity of the resulting metal particle-containing ink is improved.

[Example]
The present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples. In the examples, “part” means “part by mass”.

[Example 1-5]
<Synthesis Example of Metal Particle Dispersant>
Table 1 shows the monomers used in each example. In Table 1, monomer 1 and monomer 2 are each a monomer represented by the above general formula (I) and a monomer having an ionic functional group and / or a nitrogen-containing heterocyclic group. , Corresponding to.

撹拌機、温度計及び還流冷却器を備えた反応容器に、溶媒としてトルエン３００部を入れ、７０℃に加熱した。この反応容器内に、表１で示したモノマー１、モノマー２及びアゾビスジメチルバレロニトリル１部（重合開始剤）を含む溶液を、１時間に亘って滴下した。その後、７０℃に維持したまま５時間攪拌して、反応を終了した。得られた溶液から、トルエンをエバポレーターで蒸発させて、各実施例の高分子（金属粒子分散剤）を得た。

In a reaction vessel equipped with a stirrer, a thermometer and a reflux condenser, 300 parts of toluene as a solvent was placed and heated to 70 ° C. A solution containing monomer 1, monomer 2 and 1 part of azobisdimethylvaleronitrile (polymerization initiator) shown in Table 1 was dropped into the reaction vessel over 1 hour. Thereafter, the reaction was terminated by stirring for 5 hours while maintaining the temperature at 70 ° C. From the resulting solution, toluene was evaporated by an evaporator to obtain a polymer (metal particle dispersant) of each example.

<Preparation example of metal particle-containing ink>
The obtained metal particle dispersant and nano copper particles (QSI-Nano Copper Powder; manufactured by QuantumSphere) were added to a solvent and ultrasonically dispersed for 10 minutes as a preliminary dispersion. Thereafter, the mixture was dispersed for 10 minutes using a high-speed mixer (Filmix; manufactured by Primex). The slurry obtained after dispersion was passed through a 1 μm filter to remove coarse particles to obtain a metal particle-containing ink.

  Table 2 shows the solvent and the composition ratio of each material used in the preparation example of the metal particle-containing ink. Table 2 also shows the average particle diameter of the metal particles in the obtained metal particle-containing ink.

＜熱焼成による焼成例＞
得られたインクをガラス基板上にスピンコートし、１２０℃のホットプレートで溶媒を蒸発させた。その後、窒素フローした電気炉で、３００℃、１時間加熱することにより、焼成体を形成した。

<Baking example by thermal baking>
The obtained ink was spin-coated on a glass substrate, and the solvent was evaporated on a hot plate at 120 ° C. Then, the sintered compact was formed by heating at 300 degreeC for 1 hour with the electric furnace which carried out the nitrogen flow.

  The electrical resistance and film thickness of the obtained fired body were measured, and the volume resistivity was calculated. Table 3 shows the calculated volume resistivity.

［実施例６〜１０］
実施例１〜５における＜熱焼成による焼成例＞を、各々、下記の＜光焼成による焼成例＞に変更した以外は、実施例１〜５と同様の方法により、実施例６〜１０の焼成体を形成した。

[Examples 6 to 10]
Baking of Examples 6 to 10 was carried out in the same manner as in Examples 1 to 5, except that <Baking example by thermal baking> in Examples 1 to 5 was changed to <Baking example by light baking> below. Formed body.

<Baking example by light baking>
The obtained ink was spin-coated on a PET film, and the solvent was evaporated on a hot plate at 120 ° C. Then, the fired body was formed by irradiating with a xenon lamp for 1 hour.

  The electrical resistance and film thickness of the obtained fired body were measured, and the volume resistivity was calculated. Table 4 shows the calculated volume resistivity.

以上、詳細かつ具体的な説明から明らかであるように、本発明は一般式（Ｉ）で示した分散剤を使用することにより、体積抵抗率が低い金属粒子含有インクを提供することができる。また、本発明の金属粒子含有インクを使用した、インクジェット印刷法などの印刷法により、電気的特性に優れた導電性パターンを提供することができる。

As described above, as is clear from the detailed and specific description, the present invention can provide a metal particle-containing ink having a low volume resistivity by using the dispersant represented by the general formula (I). Moreover, the electroconductive pattern excellent in the electrical property can be provided by printing methods, such as an inkjet printing method, using the metal particle containing ink of this invention.

JP 2010-528428 A

Claims (6)

Metal particles, a metal particle dispersant, and a solvent,
The metal particle dispersant is a polymer compound obtained by polymerizing a monomer represented by the following general formula (I).
Metal particle-containing ink.

(In general formula (I), R ₁ is a hydrogen atom or a methyl group, R _{1 ′} is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, n is a natural number, and x is an integer of 1 to 3) Represents.) The metal particle dispersant is a polymer compound obtained by copolymerizing the monomer represented by the general formula (I) and a monomer having an ionic functional group.
The metal particle-containing ink according to claim 1.   3. The metal particle-containing ink according to claim 1, wherein the ionic functional group includes at least one functional group selected from the group of an amino group, a carboxyl group, a sulfo group, and a phospho group. An application step of applying the metal particle-containing ink according to any one of claims 1 to 3 to a substrate;
A firing step of firing the metal particle-containing ink in order to develop conductivity in the metal particle-containing ink;
A method for forming a conductive pattern.   The said baking process is a formation method of the electroconductive pattern of Claim 4 including the process of carrying out the light baking of the said metal particle containing ink.   The conductive pattern forming method according to claim 4, wherein the firing step includes a step of thermally firing the metal particle-containing ink in an oxygen-free atmosphere.