Electroconductive paste composition, method for manufacturing electroconductive paste composition, and method for manufacturing electronic component

Abstract

The present invention provides an electroconductive paste composition that has excellent dispersibility of inorganic particles, exhibits sufficient storage stability, and is exceptional in electrode adhesion, blister resistance, and sinterability. The present invention also provides a method for manufacturing the electroconductive paste composition, and a method for manufacturing an electronic component using the electroconductive paste composition. The present invention relates to an electroconductive paste composition containing a (meth)acrylic-resin-based dispersant (A1), inorganic particles (B1), a solvent (C1), and a binder resin (D1). The (meth)acrylic-resin-based dispersant (A1) contains 50 wt% or more of segments derived from a (meth)acryclic acid ester having a branched structure in an ester substituent, and 1-30 wt% of segments derived from a (meth)acrylic acid ester containing oxygen in an ester substituent, the weight ratio of oxygen in the ester substituent within the (meth)acrylic acid ester containing oxygen in the ester substituent being 0.28-0.36, and the weight ratio of oxygen in the ester substituents within all molecules being 0.23-0.33. The inorganic particles (B1) include elctroconductive particles having an average particle diameter of 0.05-10 μm. The solvent (C1) has a boiling point of 200-250°C. The binder resin (D1) is a (meth)acrylic resin.

Description

Conductive paste composition, method for producing conductive paste composition, and method for producing electronic component

[0001] The present invention relates to a conductive paste composition, a method for producing a conductive paste composition, and a method for producing an electronic component.

[0002] Conductive paste compositions have been widely used in the manufacture of solar cells, multilayer ceramic capacitors, etc. Conductive paste compositions are prepared by dispersing conductive metal particles in a binder resin solution, and can be adapted to various printing methods such as screen printing and offset printing by adjusting the composition ratio of the binder and inorganic particles.

[0003] For example, as an example of the application of copper paste to electronic components, Patent Document 1 describes a conductive paste composition for producing external electrodes of multilayer ceramic capacitors, in which ethyl cellulose is used as a binder resin and zinc oxide is added to promote degreasing of the ethyl cellulose. Patent Document 2 also discusses the use of a combination of glass frit having a softening temperature of 500 to 550°C and an acrylic resin having an average molecular weight of 150,000 to 760,000 and a decomposition onset temperature in thermogravimetric analysis of 150 to 250°C. Patent Document 3 also discusses the use of modified copper, in which copper powder is pre-treated with an aliphatic amine, to improve the dispersibility of copper in the paste.

[0004] Patent No. 4670164 Patent No. 4561171 Patent No. 3994439

[0005] When using copper paste, firing under an inert gas atmosphere is desirable to prevent copper oxidation. However, in the case of a configuration using ethyl cellulose, which has excellent copper dispersibility and printability, as in Patent Document 1, degreasing under an inert gas atmosphere is difficult, and debinding is not possible without adding a component that inhibits the electrode's conductivity. Furthermore, in the case of a configuration using acrylic resin, as in Patent Document 2, the binder resin can be decomposed even under an inert gas atmosphere, thereby achieving both copper oxidation prevention and binder removal. However, the copper dispersibility is inferior to that of ethyl cellulose, resulting in problems with the storage stability of the paste composition. Furthermore, copper with a partially oxidized surface is prone to adsorb amines. While treatment with an aliphatic amine, as in Patent Document 3, improves dispersibility, the adsorbed capping agent is likely to remain as a firing residue, which can cause problems such as blisters.

[0006] Problems such as voids and pinholes that occur during firing of conductive paste compositions and problems such as sedimentation of inorganic particles during storage occur due to poor dispersion of inorganic particles. Furthermore, problems such as electrode resistance and electrode adhesion after firing are caused by the decomposition of organic components such as dispersants and binder resins in an inert gas atmosphere. For this reason, there is a demand for conductive paste compositions that have good binder removal properties even in an inert gas atmosphere, good inorganic particle dispersion properties, and are less likely to cause problems such as blisters.

[0007] In view of the above circumstances, an object of the present invention is to provide a conductive paste composition having good dispersibility of inorganic particles, sufficient storage stability, and excellent electrode adhesion, blister resistance, and sinterability, as well as a method for producing the conductive paste composition and a method for producing an electronic component using the conductive paste composition.

[0008] Disclosure 1 provides a conductive paste composition comprising a (meth)acrylic resin-based dispersant (A1), inorganic particles (B1), a solvent (C1), and a binder resin (D1), wherein the (meth)acrylic resin-based dispersant (A1) comprises 50 wt % or more of a segment derived from a (meth)acrylic acid ester having a branched structure in an ester substituent and 1 wt % to 30 wt % of a segment derived from a (meth)acrylic acid ester containing oxygen in the ester substituent, wherein the (meth)acrylic acid ester containing oxygen in the ester substituent has a weight ratio of oxygen in the ester substituent of 0.28 to 0.36 and a weight ratio of oxygen in the ester substituent in the molecule of 0.23 to 0.33, the inorganic particles (B1) comprise conductive particles having an average particle size of 0.05 μm to 10 μm, the solvent (C1) has a boiling point of 200° C. to 250° C., and the binder resin (D1) is a (meth)acrylic resin. Disclosure 2 is the conductive paste composition of Disclosure 1, wherein the (meth)acrylic resin-based dispersant (A1) contains 5% by weight or more and 30% by weight or less of segments derived from a (meth)acrylic acid ester having oxygen in the ester substituent, and the weight-average molecular weight of the (meth)acrylic resin-based dispersant (A1) is 20,000 or more and less than 150,000. Disclosure 3 is the conductive paste composition of Disclosure 1 or 2, wherein the content of the (meth)acrylic resin-based dispersant (A1) is 3% by weight or more and 20% by weight or less. Disclosure 4 is the conductive paste composition of Disclosure 1, 2, or 3, wherein the (meth)acrylic resin-based dispersant (A1) has a weight-average molecular weight of 20,000 or more and 140,000 or less. Disclosure 5 is the conductive paste composition of Disclosure 1, 2, 3, or 4, wherein the (meth)acrylic resin-based dispersant (A1) has a plurality of hydroxyl groups or carboxyl groups at one end of the molecular chain. The present disclosure 6 is the conductive paste composition of the present disclosure 1, 2, 3, 4, or 5, wherein the solvent (C1) is at least one selected from the group consisting of terpineol, dihydroterpineol, and butyl carbitol.Disclosure 7 is the conductive paste composition of Disclosure 1, 2, 3, 4, 5, or 6, wherein in the inorganic fine particles (B1), the conductive particles are copper particles, and in the (meth)acrylic resin-based dispersant (A1), the (meth)acrylic acid ester containing oxygen in the ester substituent has a weight ratio of oxygen in the ester substituent of 0.28 to 0.32 and a weight ratio of oxygen in the ester substituent in the molecule of 0.24 to 0.27. Disclosure 8 is the conductive paste composition of Disclosure 7, wherein in the (meth)acrylic resin-based dispersant (A1), the (meth)acrylic acid ester containing oxygen in the ester substituent includes a segment derived from polypropylene glycol.

[0014] Disclosure 9 is the conductive paste composition of Disclosures 1, 2, 3, 4, 5, or 6, wherein the conductive particles in the inorganic particles (B1) are silver particles, and the (meth)acrylic resin-based dispersant (A1) has a (meth)acrylic acid ester containing oxygen in its ester substituent, and the weight ratio of oxygen in the substituent is 0.34 or more and 0.36 or less, and the weight ratio of oxygen in the ester substituent in the molecule is 0.23 or more and 0.33 or less. Disclosure 10 is the conductive paste composition of Disclosure 9, wherein the (meth)acrylic acid ester containing oxygen in its ester substituent in the (meth)acrylic resin-based dispersant (A1) includes a segment derived from polyethylene glycol. Disclosure 11 is the conductive paste composition of Disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, wherein the weight average molecular weight of the (meth)acrylic resin in the binder resin (D1) is 100,000 or more and 1,000,000 or less, and the (meth)acrylic resin has a segment derived from isobutyl methacrylate and a segment derived from methyl methacrylate. Disclosure 12 is the conductive paste composition of Disclosure 11, wherein in the binder resin (D1), the (meth)acrylic resin contains 50% by weight or more of a segment derived from isobutyl methacrylate.Disclosure 13 is the conductive paste composition of Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, wherein in the binder resin (D1), the (meth)acrylic resin contains 50% by weight or more of segments derived from a (meth)acrylic acid ester having a branched structure in the ester substituent and 1% by weight or more and 30% by weight or less of segments derived from a (meth)acrylic acid ester containing oxygen in the ester substituent, and in the (meth)acrylic acid ester containing oxygen in the ester substituent, the weight ratio of oxygen in the ester substituent is 0.28 or more and 0.36 or less, and the weight ratio of oxygen in the ester substituent in the molecule is 0.23 or more and 0.33 or less. Disclosure 14 is the conductive paste composition of Disclosure 13, wherein the (meth)acrylic resin in the binder resin (D1) is the same (meth)acrylic resin as the (meth)acrylic resin-based dispersant (A1).

[0023] The present disclosure 15 is the conductive paste composition according to disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, or 14, wherein the material of the conductive particles in the inorganic particles (B1) is lithium, magnesium, nickel, dysprosium, terbium, or an alloy of these with copper or silver.

[0024] The present disclosure 16 is a method for producing the conductive paste composition according to disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15, comprising: a step of preparing a (meth)acrylic resin-based dispersant (A1) by a solution polymerization method using an organic peroxide in which the carbon adjacent to a peroxide bond is a primary carbon as a polymerization initiator; and a step of mixing the (meth)acrylic resin-based dispersant (A1) obtained in the step, inorganic fine particles (B1), a solvent (C1), and a binder resin (D1).

[0009] The present disclosure 17 provides a conductive paste composition comprising a (meth)acrylic resin-based dispersant (A2), inorganic particles (B2), and a solvent (C2), wherein the (meth)acrylic resin-based dispersant (A2) comprises 50 wt % or more of segments derived from a (meth)acrylic acid ester having a branched structure in an ester substituent and 1 wt % to 30 wt % of segments derived from a (meth)acrylic acid ester containing oxygen in the ester substituent, wherein the (meth)acrylic acid ester containing oxygen in the ester substituent has a weight ratio of oxygen in the ester substituent of 0.28 to 0.36 and a weight ratio of oxygen in the ester substituent in the molecule of 0.23 to 0.33, the inorganic particles (B2) comprise conductive particles having an average particle size of 0.05 μm to 10 μm, and the solvent (C2) has a boiling point of 200° C. to 250° C. Disclosure 18 is the conductive paste composition of Disclosure 17, wherein the (meth)acrylic resin-based dispersant (A2) has a content of segments derived from a (meth)acrylic acid ester having oxygen in the ester substituent of 5% by weight or more and 30% by weight or less, and the weight-average molecular weight of the (meth)acrylic resin-based dispersant (A2) is 20,000 or more and less than 150,000. Disclosure 19 is the conductive paste composition of Disclosure 17 or 18, wherein the content of the (meth)acrylic resin-based dispersant (A2) is 3% by weight or more and 20% by weight or less. Disclosure 20 is the conductive paste composition of Disclosure 17, 18, or 19, wherein the weight-average molecular weight of the (meth)acrylic resin-based dispersant (A2) is 20,000 or more and 140,000 or less. Disclosure 21 is the conductive paste composition of Disclosure 17, 18, 19, or 20, wherein the (meth)acrylic resin-based dispersant (A2) has a plurality of hydroxyl groups or carboxyl groups at one end of the molecular chain. The present disclosure 22 is the conductive paste composition of the present disclosure 17, 18, 19, 20, or 21, wherein the solvent (C2) is at least one selected from the group consisting of terpineol, dihydroterpineol, and butyl carbitol.Disclosure 23 is the conductive paste composition of Disclosure 17, 18, 19, 20, 21, or 22, wherein, in the inorganic particles (B2), the conductive particles are copper particles, and in the (meth)acrylic resin-based dispersant (A2), the (meth)acrylic acid ester containing oxygen in the ester substituent has a weight ratio of oxygen in the ester substituent of 0.28 to 0.32 and a weight ratio of oxygen in the ester substituent in the molecule of 0.24 to 0.27. Disclosure 24 is the conductive paste composition of Disclosure 23, wherein, in the (meth)acrylic resin-based dispersant (A2), the (meth)acrylic acid ester containing oxygen in the ester substituent includes a segment derived from polypropylene glycol.

[0023] Disclosure 25 is the conductive paste composition of Disclosure 17, 18, 19, 20, 21, or 22, wherein, in the inorganic particles (B2), the conductive particles are silver particles, and in the (meth)acrylic resin-based dispersant (A2), the (meth)acrylic acid ester containing oxygen in its ester substituent has a weight ratio of oxygen in the ester substituent of 0.34 or more and 0.36 or less, and the weight ratio of oxygen in the ester substituent in the molecule is 0.23 or more and 0.33 or less. Disclosure 26 is the conductive paste composition of Disclosure 25, wherein, in the (meth)acrylic resin-based dispersant (A2), the (meth)acrylic acid ester containing oxygen in its ester substituent includes a segment derived from polyethylene glycol.

[0023] Disclosure 27 is the conductive paste composition of Disclosure 17, 18, 19, 20, 21, 22, 23, 24, 25, or 26, further comprising a binder resin (D2), wherein the binder resin (D2) is a (meth)acrylic resin, the (meth)acrylic resin has a weight average molecular weight of 100,000 or more and 1,000,000 or less, and the (meth)acrylic resin has a segment derived from isobutyl methacrylate and a segment derived from methyl methacrylate. Disclosure 28 is the conductive paste composition of Disclosure 27, wherein the (meth)acrylic resin in the binder resin (D2) contains 50% by weight or more of a segment derived from isobutyl methacrylate.Disclosure 29 is a method for producing a conductive paste composition according to Disclosures 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, or 28, comprising the steps of preparing a (meth)acrylic resin-based dispersant (A2) by solution polymerization using an organic peroxide as a polymerization initiator, in which the carbon adjacent to the peroxide bond is a primary carbon, and mixing the (meth)acrylic resin-based dispersant (A2) obtained in the step, inorganic fine particles (B2), and a solvent (C2). Disclosure 30 is a method for producing an electronic component using the conductive paste composition according to Disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, or 28. The present invention is described in detail below.

[0010] The present inventors have noticed that conventional acrylic resin dispersants incorporating amine, phosphate, or carboxylic acid groups can improve the dispersibility of conductive metal particles, but have poor thermal decomposition properties under an inert gas atmosphere. Therefore, they investigated the use of various (meth)acrylic resins. As a result, they have found that (meth)acrylic resins containing a predetermined proportion of segments derived from (meth)acrylic acid esters having a branched structure in the ester substituent, and containing oxygen in the ester substituent, and containing a predetermined proportion of segments derived from (meth)acrylic acid esters in which the oxygen weight ratio in the ester substituent and the oxygen weight ratio in the ester substituent in the molecule are within a predetermined range, exhibit excellent properties. Specifically, they have found that such (meth)acrylic resins can improve the dispersibility of conductive metal particles, particularly copper particles, and also have excellent thermal decomposition properties. Furthermore, they have found that by using such (meth)acrylic resins in combination with predetermined inorganic particles, solvents, and binder resins, a conductive paste composition can be prepared that exhibits good inorganic particle dispersibility, sufficient storage stability, and excellent electrode adhesion, blister resistance, and sinterability. This finding led to the completion of the present invention.

[0011] A conductive paste composition according to one embodiment of the present invention (hereinafter also referred to as conductive paste composition (1)) contains a (meth)acrylic resin-based dispersant (A1), inorganic particles (B1), a solvent (C1), and a binder resin (D1). The (meth)acrylic resin-based dispersant (A1) contains 50% by weight or more of segments derived from a (meth)acrylic acid ester having a branched structure in an ester substituent and 1% by weight to 30% by weight of segments derived from a (meth)acrylic acid ester containing oxygen in the ester substituent. In the (meth)acrylic acid ester containing oxygen in the ester substituent, the weight ratio of oxygen in the ester substituent is 0.28 to 0.36 and the weight ratio of oxygen in the ester substituent in the molecule is 0.23 to 0.33. The inorganic particles (B1) contain conductive particles having an average particle size of 0.05 μm to 10 μm. The solvent (C1) has a boiling point of 200° C. to 250° C. The binder resin (D1) is a (meth)acrylic resin.

[0012] <(Meth)acrylic Resin Dispersant (A1)> The conductive paste composition (1) contains a (meth)acrylic resin dispersant (A1). The (meth)acrylic resin dispersant (A1) contains a segment derived from a (meth)acrylic acid ester containing oxygen in the ester substituent. Here, "(meth)acrylic acid ester" refers to an acrylic acid ester or a methacrylic acid ester. The ester substituent refers to a substituent bonded to an ester bond that is different from a substituent constituting a (meth)acryloyl group, and specifically refers to the X portion of a structure represented by CH2=CR-(C=O)-O-X (R is a hydrogen atom or a methyl group).

[0013] The (meth)acrylic acid ester containing oxygen in the ester substituent preferably consists of carbon, oxygen, and hydrogen and does not contain other elements such as nitrogen, phosphorus, or sulfur. The ester substituent preferably does not contain an epoxy group, a silyl group, or an isocyanate group. The oxygen contained in the ester substituent preferably originates from a hydroxyl group, an ether group, an ester group, a carbonyl group, or a carboxyl group.

[0014] In the (meth)acrylic acid ester containing oxygen in the ester substituent, the oxygen weight ratio in the ester substituent is 0.28 or more and 0.36 or less. Within this range, the storage stability of the resulting conductive paste composition can be improved, and the sinterability can also be excellent. For example, when the conductive particles are copper particles, the oxygen weight ratio in the ester substituent is preferably 0.28 or more and 0.32 or less, and when the conductive particles are silver particles, it is preferably 0.34 or more and 0.36 or less. Within this range, the dispersibility of the conductive particles can be further improved, and the storage stability and blister resistance of the conductive paste composition can be further improved.

[0015] In the (meth)acrylic acid ester containing oxygen in the ester substituent, the weight ratio of oxygen in the ester substituent in the molecule is 0.23 or more and 0.33 or less. Within this range, the storage stability of the resulting conductive paste composition can be improved, and the sinterability can also be excellent. For example, when the conductive particles are copper particles, the weight ratio of oxygen in the ester substituent in the molecule is preferably 0.24 or more and 0.27 or less, and when the conductive particles are silver particles, it is preferably 0.23 or more and 0.33 or less. Within this range, the dispersibility of the conductive particles can be further improved, and the storage stability and blister resistance of the conductive paste composition can be further improved.

[0016] In the (meth)acrylic acid ester containing oxygen in the ester substituent, examples of the ester substituent include alcohols (2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, etc.), carboxylic acids (ethyl (meth)acrylate succinate, (meth)acryloyloxyethyl hexahydrophthalate, etc.), and polyalkylene glycols (polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, polytetramethylene glycol (meth)acrylate, polyethylene glycol (meth)acrylate-polypropylene glycol, polyethylene glycol (meth)acrylate-polytetramethylene glycol, polypropylene glycol (meth)acrylate-polytetramethylene glycol, polyethylene glycol behenyl ether (meth)acrylate, etc.). Among these, polyalkylene glycols are preferred. That is, the (meth)acrylic acid ester containing oxygen in the ester substituent is preferably polyalkylene glycol (meth)acrylate. Furthermore, the polyalkylene glycol (meth)acrylate may have an alkoxy group at its terminal. Examples of the alkoxy group include a methoxy group, an ethoxy group, and a butoxy group.

[0017] In the polyalkylene glycol (meth)acrylate, the number of repeating alkylene glycol units is preferably 4 or more and preferably 30 or less. By setting the number of repeating alkylene glycol units within the above range, the storage stability of the resulting conductive paste composition can be improved and the sinterability can also be excellent. Furthermore, the number of repeating alkylene glycol units is more preferably 10 or more, even more preferably 15 or more, more preferably 25 or less, and even more preferably 23 or less. By setting the number of repeating alkylene glycol units within the above range, the dispersibility of the conductive particles can be further improved, and the storage stability and blister resistance of the conductive paste composition can be further improved.

[0018] In the (meth)acrylic resin-based dispersant (A1), the content of the segment derived from the (meth)acrylic acid ester containing oxygen in the ester substituent is 1% by weight or more and 30% by weight or less. Within this range, the storage stability of the resulting conductive paste composition can be improved, and the sinterability can also be excellent. The content of the segment derived from the (meth)acrylic acid ester containing oxygen in the ester substituent is preferably 5% by weight or more, more preferably 7% by weight or more, and is preferably 25% by weight or less, and more preferably 20% by weight or less. The content can be measured, for example, by pyrolysis GC-MS.

[0019] The (meth)acrylic resin-based dispersant (A1) has a segment derived from a (meth)acrylic acid ester having a branched structure in the ester substituent. Note that the (meth)acrylic acid ester having a branched structure in the ester substituent is different from the (meth)acrylic acid ester containing oxygen in the ester substituent. In other words, the (meth)acrylic acid ester having a branched structure in the ester substituent does not include one containing oxygen in the ester substituent. A (meth)acrylic resin containing as a main component a (meth)acrylic acid ester having a branched structure in the ester substituent is more excellent in decomposition ability under an inert gas atmosphere than a (meth)acrylic acid ester containing as a main component a (meth)acrylic acid ester having a linear ester substituent.

[0020] Examples of the (meth)acrylic acid ester having a branched structure in the ester substituent include a (meth)acrylic acid alkyl ester having a branched alkyl group, etc. The number of carbon atoms in the ester substituent is preferably 3 or more, more preferably 4 or more, and is preferably 20 or less, more preferably 15 or less, even more preferably 12 or less, and still more preferably 10 or less.

[0021] Examples of the (meth)acrylic acid ester having a branched alkyl group include isopropyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, isopentyl (meth)acrylate, isohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate, etc. Among these, isopropyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and isodecyl (meth)acrylate are preferred, isopropyl methacrylate, isobutyl methacrylate, s-butyl methacrylate, 2-ethylhexyl methacrylate, and isodecyl methacrylate are more preferred, and isobutyl methacrylate and 2-ethylhexyl methacrylate are even more preferred.

[0022] The (meth)acrylic resin-based dispersant (A1) preferably has at least one selected from the group consisting of a segment derived from isobutyl methacrylate and a segment derived from 2-ethylhexyl methacrylate as the segment derived from a (meth)acrylic acid ester having a branched structure in the ester substituent. By satisfying the above configuration, a conductive paste composition having excellent decomposability in an inert gas atmosphere can be obtained.

[0023] The content of the segment derived from the (meth)acrylic acid ester having a branched structure in the ester substituent in the (meth)acrylic resin-based dispersant (A1) is 50% by weight or more. Within this range, a conductive paste composition with excellent low-temperature decomposability can be obtained. The content of the segment derived from the (meth)acrylic acid ester having a branched structure in the ester substituent is preferably 55% by weight or more, more preferably 60% by weight or more, and is preferably 99% by weight or less, more preferably 90% by weight or less. The content can be measured, for example, by pyrolysis GC-MS.

[0024] The (meth)acrylic resin dispersant (A1) may further contain other segments such as a segment derived from a (meth)acrylic acid ester having a linear ester substituent, or a segment derived from a (meth)acrylic acid ester having a cyclic ester substituent. Examples of the (meth)acrylic acid ester having a linear ester substituent include a (meth)acrylic acid alkyl ester having a linear alkyl group. The carbon number of the ester substituent is preferably 1 or more, more preferably 2 or more, and is preferably 10 or less, more preferably 6 or less.

[0025] Examples of the (meth)acrylic acid alkyl ester having a linear alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, etc. Among these, methyl (meth)acrylate, ethyl (meth)acrylate, and n-butyl (meth)acrylate are preferred, and methyl methacrylate is more preferred.

[0026] Examples of the (meth)acrylic acid ester in which the ester substituent has a cyclic structure include (meth)acrylic acid esters having a cyclic alkyl group such as cyclohexyl (meth)acrylate and isobornyl (meth)acrylate, and (meth)acrylic acid esters having a glycidyl group such as glycidyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether and 3,4-epoxycyclohexylmethyl (meth)acrylate.

[0027] The content of the segment derived from a (meth)acrylic acid ester in which the ester substituent is linear in the (meth)acrylic resin-based dispersant (A1) is, for example, 0% by weight or more, preferably 1% by weight or more, more preferably 5% by weight or more, and preferably 20% by weight or less, more preferably 10% by weight or less. By setting it within the above range, handleability such as printability is improved. The content can be measured, for example, by pyrolysis GC-MS.

[0028] The (meth)acrylic resin dispersant (A1) preferably has a hydroxyl group or a carboxyl group at one end of the molecular chain, and more preferably has multiple hydroxyl groups or carboxyl groups at one end of the molecular chain. The above structure further improves the dispersibility of the inorganic particles (B1). Furthermore, the viscosity of the conductive paste composition can be made more suitable. For example, when preparing the (meth)acrylic resin dispersant (A1), multiple polar groups can be introduced at one end of the molecular chain by using a mercapto derivative such as mercaptosuccinic acid or mercaptopropanediol as a chain transfer agent. When analyzing the structure of the branched end, the (meth)acrylic resin dispersant (A) is dissolved in deuterated chloroform, and １ Using a H-NMR (manufactured by JEOL Ltd., "ECX-400"), under the conditions of 400 MHz, measurement temperature 80°C, and accumulation number 1024 １ H-NMR spectra can be obtained to identify the structure.

[0029] The weight average molecular weight (Mw) of the (meth)acrylic resin-based dispersant (A1) is preferably 20,000 or more, and preferably less than 150,000. When the Mw is 20,000 or more, the viscosity of the conductive paste composition is not too low, and the dispersibility of the inorganic particles can be improved. When the Mw is less than 150,000, the viscosity of the conductive paste composition is sufficiently high, improving storage stability and resulting in excellent printability. The Mw is more preferably 30,000 or more, even more preferably 50,000 or more, more preferably 140,000 or less, and even more preferably 100,000 or less.

[0030] The ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the (meth)acrylic resin-based dispersant (A1) is usually 1 or more, preferably 1.5 or more, more preferably 2 or more, and preferably 5 or less, more preferably 3 or less. By setting the ratio within the above range, a moderate amount of components with a low degree of polymerization is contained, so that the viscosity of the conductive paste composition falls within a suitable range, thereby improving productivity. The weight average molecular weight (Mw) and number average molecular weight (Mn) are average molecular weights calculated in terms of polystyrene, and can be obtained by GPC measurement using, for example, a column LF-804 (manufactured by Showa Denko KK).

[0031] The glass transition temperature (Tg) of the (meth)acrylic resin-based dispersant (A1) is preferably 20° C. or higher, more preferably 30° C. or higher, and is preferably 60° C. or lower, more preferably 50° C. or lower. The glass transition temperature (Tg) can be measured using, for example, a differential scanning calorimeter (DSC) or the like.

[0032] The content of the (meth)acrylic resin-based dispersant (A) in the conductive paste composition (1) is preferably 3 wt % or more, more preferably 3.5 wt % or more, and even more preferably 4 wt % or more, and is preferably 30 wt % or less, more preferably 20 wt % or less, and even more preferably 12 wt % or less. By setting the content of the (meth)acrylic resin-based dispersant (A1) within the above range, a conductive paste composition that can be fired at a low temperature can be obtained.

[0033] The method for producing the (meth)acrylic resin-based dispersant (A1) is not particularly limited. For example, an organic solvent or the like is added to a raw material monomer mixture containing a (meth)acrylic acid ester having a branched structure in the ester substituent, a (meth)acrylic acid ester containing oxygen in the ester substituent, or the like to prepare a monomer mixture, and then a polymerization initiator is added to the resulting monomer mixture to polymerize the monomer mixture to produce the (meth)acrylic resin-based dispersant (A1). A chain transfer agent may also be added to the monomer mixture. The polymerization method is not particularly limited, and examples include emulsion polymerization, suspension polymerization, bulk polymerization, interfacial polymerization, and solution polymerization. Among these, solution polymerization is preferred.

[0034] Examples of the polymerization initiator include organic peroxides such as dilauryl peroxide, p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroxyperoxide, t-butyl hydroxyperoxide, cyclohexanone peroxide, disuccinic acid peroxide, and bis-3,5,5-trimethylhexanoyl peroxide. Commercially available products of these include Permenta H, Percumyl P, Perocta H, Percumyl H-80, Perloyl 355, Perbutyl H-69, Perhexa H, Perloyl SA, and Perloyl L (all manufactured by NOF Corporation), and Trigonox 27 and Trigonox 421 (all manufactured by Nouryon). Among these, it is preferable to use an initiator with low hydrogen abstraction property, such as dilauryl peroxide, in order to prevent gelation during polymerization of the (meth)acrylic resin dispersant (A1). Examples of initiators that can further suppress gelation include dilauryl peroxide and bis-3,5,5-trimethylhexanoyl peroxide. In these initiators, the carbon adjacent to the peroxide bond is a primary carbon that does not have a branched chain. As the polymerization initiator, it is preferable to use an organic peroxide in which the carbon adjacent to the peroxide bond is a primary carbon. Initiators in which the carbon adjacent to the peroxide bond is a tertiary carbon are not preferred because they have high hydrogen abstraction properties and may cause the acrylic polymer to gel during polymerization.

[0035] Furthermore, by using a mercapto derivative such as mercaptosuccinic acid or mercaptopropanediol as a chain transfer agent during polymerization, a hydroxyl group or a carboxyl group can be introduced into the molecular terminal.

[0036] In addition, some (meth)acrylic acid esters containing oxygen in the ester substituent have no boiling point, and when such esters are used, components having (meth)acryloyl groups at both ends are contained as impurities. Therefore, when producing a (meth)acrylic resin dispersant (A1) using a (meth)acrylic acid polyalkylene glycol having 10 or more repeating alkylene glycol units, it is desirable to set the weight average molecular weight (Mw) of the (meth)acrylic resin dispersant (A1) to 50,000 or less. Gelation can be prevented by using a linear polymerization initiator that does not have a branch in the presence of a chain transfer agent.

[0037] <Inorganic Particles (B1)> The conductive paste composition (1) contains inorganic particles (B1). The inorganic particles (B1) include conductive particles having an average particle diameter of 0.05 μm or more and 10 μm or less. Examples of metals that can be used for the conductive particles include copper, nickel, palladium, platinum, gold, silver, aluminum, tungsten, lithium, magnesium, niobium, lanthanum, dysprosium, terbium, and alloys thereof. Among these, copper, silver, lithium, magnesium, nickel, dysprosium, terbium, and alloys thereof are preferred because they form alloys with silver or copper, enabling a paste coating process that is simpler than conventional film formation by plating or sputtering. Copper, silver, lithium, magnesium, nickel, dysprosium, terbium, or alloys thereof with copper or silver are preferred. The electrical conductivity of the conductive particles is preferably 0.8 MS / m or more and 62 MS / m or less. The thermal conductivity can be measured, for example, at 25°C using an AC two-electrode electrical conductance measuring device. Conductive metal particles containing copper are particularly preferred because they have low resistance and are less likely to cause electromigration problems. The method for producing the copper particles described above is not particularly limited, and a liquid-phase reduction method, a gas-phase method (electrolytic reduction method), a micelle method, or the like can be used.

[0038] The conductive particles have an average particle size of 0.05 μm or more and 10 μm or less. Within this range, excellent low-temperature sintering properties can be achieved. The average particle size is preferably 0.1 μm or more, more preferably 0.2 μm or more, and is preferably 5 μm or less, more preferably 1 μm or less. The average particle size can be measured by the BET method. More specifically, it can be measured based on the description in "The Big Problem of Small Particles: A Comparison of Methods for Determination of Particle Size in Nanocrystalline Anatase Powders Weibel, A. et al. Chem. Mater. 2005, 17, 2378."

[0039] The content of the conductive particles in the conductive paste composition (1) is preferably 50% by weight or more, more preferably 55% by weight or more, even more preferably 60% by weight or more, even more preferably 65% ​​by weight or more, and is preferably 85% by weight or less, more preferably 80% by weight or less, even more preferably 75% by weight or less, and even more preferably 70% by weight or less. By setting the content within the above range, a conductive paste composition with excellent printability can be obtained.

[0040] The inorganic particles (B1) may contain inorganic particles other than the conductive particles. Examples of the other inorganic particles include glass powder. By including the glass powder, the conductive metal particles can be aggregated to form a dense layer when the conductive paste composition is sintered. The glass powder is not particularly limited, and examples thereof include glass powders such as bismuth oxide glass, silicate glass, lead glass, zinc glass, and boron glass, and CaO—Al ２ O ３ -SiO ２ system, MgO-Al ２ O ３ -SiO ２ system, LiO ２ -Al ２ O ３ -SiO ２Examples of the glass powder include glass powders of various silicon oxides such as SnO—B ２ O ３ -P ２ O ５ -Al ２ O ３ mixture, PbO-B ２ O ３ -SiO ２ Mixture, BaO-ZnO-B ２ O ３ -SiO ２ Mixture, ZnO-Bi ２ O ３ -B ２ O ３ -SiO ２ mixture, Bi ２ O ３ -B ２ O ３ -BaO-CuO mixture, Bi ２ O ３ -ZnO-B ２ O ３ -Al ２ O ３ -SrO mixture, ZnO-Bi ２ O ３ -B ２ O ３ mixture, Bi ２ O ３ -SiO ２ mixture, P ２ O ５ -Na ２ O-CaO-BaO-Al ２ O ３ -B ２ O ３ mixture, P ２ O ５ -SnO mixture, P ２ O ５ -SnO-B ２ O ３ mixture, P ２ O ５ -SnO-SiO ２ mixture, CuO-P ２ O ５ -RO mixture, SiO ２ -B ２ O ３ -ZnO-Na ２ O-Li２ O-NaF-V ２ O ５ mixture, P ２ O ５ -ZnO-SnO-R ２ O-RO mixture, B ２ O ３ -SiO ２ -ZnO mixture, B ２ O ３ -SiO ２ -Al ２ O ３ -ZrO ２ mixture, SiO ２ -B ２ O ３ -ZnO-R ２ O-RO mixture, SiO ２ -B ２ O ３ -Al ２ O ３ -RO-R ２ O mixture, SrO-ZnO-P ２ O ５ Mixture, SrO-ZnO-P ２ O ５ Mixture, BaO-ZnO-B ２ O ３ -SiO ２ Glass powders such as mixtures can also be used. R is an element selected from the group consisting of Zn, Ba, Ca, Mg, Sr, Sn, Ni, Fe, and Mn. In particular, PbO—B ２ O ３ -SiO ２ Mixture glass powder and lead-free BaO-ZnO-B ２ O ３ -SiO ２ Mixture or ZnO-Bi ２ O ３ -B ２ O ３ -SiO ２ Lead-free glass powders such as mixtures are preferred.

[0041] The content of inorganic particles other than the conductive particles in the conductive paste composition (1) is preferably 0.1% by weight or more, more preferably 1% by weight or more, and is preferably 5% by weight or less, more preferably 3% by weight or less.

[0042] The content of the inorganic particles (B1) in the conductive paste composition (1) is preferably 50% by weight or more, more preferably 55% by weight or more, and even more preferably 65% ​​by weight or more, and is preferably 85% by weight or less, more preferably 80% by weight or less, and even more preferably 75% by weight or less. By setting the content within the above range, a conductive paste composition with excellent printability can be obtained.

[0043] <Solvent (C1)> The conductive paste composition (1) contains a solvent (C1). The solvent (C1) is an organic solvent having a boiling point of 200° C. or higher and 250° C. or lower. By using the solvent (C1), evaporation does not become too rapid, and the solvent can be removed under drying conditions at or below the decomposition onset temperature of the (meth)acrylic resin, thereby improving the productivity of electronic components.

[0044] The solvent is preferably one that is excellent in coatability, drying properties, and dispersibility of conductive inorganic particles when producing electronic components. Examples include ethylene glycol monoethyl ether acetate (246°C), butyl carbitol (231°C), butyl carbitol acetate (247°C), terpineol (219°C), terpineol acetate (220°C), dihydroterpineol (246°C), dihydroterpineol acetate (246°C), Texanol (244°C), isophorone (215°C), dioctyl phthalate (220°C), dioctyl adipate (214°C), benzyl alcohol (205°C), and phenylpropylene glycol (244°C). Among these, terpineol, terpineol acetate, dihydroterpineol, dihydroterpineol acetate, butyl carbitol, butyl carbitol acetate, and Texanol are preferred. Terpineol, terpineol acetate, dihydroterpineol, dihydroterpineol acetate, and butyl carbitol are more preferred, and terpineol, dihydroterpineol, and butyl carbitol are even more preferred. These organic solvents may be used alone or in combination of two or more. The boiling points are indicated in parentheses.

[0045] The boiling point of the organic solvent is 200°C or higher, preferably 205°C or higher, and 250°C or lower, preferably 230°C or lower.

[0046] The content of the solvent (C1) in the conductive paste composition (1) is preferably 5 wt % or more, more preferably 10 wt % or more, and is preferably 30 wt % or less, more preferably 25 wt % or less. By setting the content within the above range, the coatability and the dispersibility of the conductive metal particles can be improved.

[0047] <Binder Resin (D1)> The conductive paste composition (1) contains a binder resin (D1). The binder resin (D1) is a (meth)acrylic resin. The purpose of adding the binder resin (D1) is to develop the viscosity required for the paste printing process. In order to develop good sinterability and low residue properties of the paste by using the (meth)acrylic resin-based dispersant (A1) with good decomposition properties in the conductive paste composition, the binder resin (D1) must be as decomposable as the dispersant (A1). Therefore, a (meth)acrylic resin must be used as the binder resin (D1). The (meth)acrylic resin may have the same monomer structure as the (meth)acrylic resin-based dispersant (A1), or may have a different structure. To increase the viscosity and thixotropy of the paste, the molecular weight and glass transition temperature (Tg) of the binder resin (D1) are preferably high. That is, as the binder resin (D1) having the same monomer structure as the (meth)acrylic resin-based dispersant (A1), a (meth)acrylic resin can also be used which contains 50% by weight or more of segments derived from a (meth)acrylic acid ester having a branched structure in the ester substituent and 1% by weight to 30% by weight of segments derived from a (meth)acrylic acid ester containing oxygen in the ester substituent, wherein the weight ratio of oxygen in the ester substituent in the (meth)acrylic acid ester containing oxygen in the ester substituent is 0.28 to 0.36 and the weight ratio of oxygen in the ester substituent in the molecule is 0.23 to 0.33.

[0048] The (meth)acrylic resin may have, for example, a segment derived from a (meth)acrylic acid ester having a branched structure in the ester substituent, a segment derived from a (meth)acrylic acid ester having a linear ester substituent, or the like, but not a segment derived from a (meth)acrylic acid ester containing oxygen in the ester substituent. Examples of the (meth)acrylic acid ester having a branched structure in the ester substituent and the (meth)acrylic acid ester having a linear ester substituent include the same as those constituting the (meth)acrylic resin-based dispersant (A). Among these, those having a segment derived from isobutyl methacrylate are preferred, and those having a segment derived from isobutyl methacrylate and a segment derived from methyl methacrylate are preferred.

[0049] In the (meth)acrylic resin, the content of the segment derived from isobutyl methacrylate is preferably 30% by weight or more. Within this range, a conductive paste composition with excellent low-temperature decomposition properties can be obtained. The content of the segment derived from isobutyl methacrylate is preferably 50% by weight or more, even more preferably 55% by weight or more, and even more preferably 60% by weight or more, and is preferably 99% by weight or less, more preferably 90% by weight or less, and even more preferably 80% by weight or less. The content can be measured, for example, by pyrolysis GC-MS.

[0050] In the (meth)acrylic resin, the content of the segment derived from methyl methacrylate is preferably 1% by weight or more, more preferably 5% by weight or more, and is preferably 50% by weight or less, more preferably 30% by weight or less.

[0051] The weight-average molecular weight (Mw) of the (meth)acrylic resin is preferably 100,000 or more, preferably 150,000 or more, more preferably 200,000 or more, and preferably 1,000,000 or less, more preferably 800,000 or less, and even more preferably 700,000 or less. The glass transition temperature (Tg) of the (meth)acrylic resin is preferably 30° C. or more, more preferably 50° C. or more, and preferably 100° C. or less, more preferably 80° C. or less. By setting the temperature within the above range, the viscosity of the conductive paste composition does not become too low, and the dispersibility of the inorganic particles can be improved. Furthermore, the viscosity of the conductive paste composition is sufficiently increased, improving storage stability and resulting in excellent printability.

[0052] The total amount of the (meth)acrylic resin in the conductive paste composition (1) is preferably 1 wt % or more, more preferably 3 wt % or more, and is preferably 15 wt % or less, more preferably 10 wt % or less, where the total amount of the (meth)acrylic resin means the combined amount of the (meth)acrylic resin-based dispersant (A1) and the binder resin (D1).

[0053] It is not particularly preferable for the conductive paste composition (1) to contain other binder resins such as ethyl cellulose, polyvinyl acetal resin, etc. If the conductive paste composition can be fired in an oxygen-containing environment, these other binder resins can be used. However, if an easily oxidizable material such as copper is used as the conductive particles, it is preferable to use a (meth)acrylic resin as the binder resin, which can be fired even in an inert gas atmosphere.

[0054] <Others> The conductive paste composition (1) may further contain additives such as a sintering aid.

[0055] The viscosity of the conductive paste composition (1) is preferably 0.1 Pa s as a lower limit and 100 Pa s as an upper limit when measured at 20°C using a Brookfield viscometer with a probe rotation speed of 5 rpm. By setting the viscosity to 0.1 Pa s or more, the resulting conductive metal particle-dispersed sheet can maintain a predetermined shape after application by a die coating printing method or the like. Furthermore, by setting the viscosity to 100 Pa s or less, dripping when the conductive paste composition is filled into a through via can be prevented, improving printability.

[0056] The method for preparing the conductive paste composition (1) is not particularly limited, and examples thereof include conventionally known stirring methods. Specific examples include a method in which the (meth)acrylic resin-based dispersant (A1), the inorganic particles (B1), the solvent (C1), the binder resin (D1), and other components added as needed are stirred using a three-roll mill or the like. Another example includes a method in which the inorganic particles (B1), the binder resin (D1), and the additional solvent (C1) and other components added as needed are added to the resin solution obtained after the reaction in preparing the (meth)acrylic resin-based dispersant (A1), and the mixture is stirred using a three-roll mill or the like. A preferred method for preparing the conductive paste composition includes a step of preparing the (meth)acrylic resin-based dispersant (A1) by solution polymerization using an organic peroxide in which the carbon adjacent to the peroxide bond is a primary carbon, as a polymerization initiator, and a step of mixing the (meth)acrylic resin-based dispersant (A1), inorganic particles (B1), solvent (C1), and binder resin (D1) obtained in the above step. The present invention also provides a method for producing the conductive paste composition, which includes: a step of preparing a (meth)acrylic resin-based dispersant (A1) by a solution polymerization method using an organic peroxide in which the carbon adjacent to a peroxide bond is a primary carbon, as a polymerization initiator; and a step of mixing the (meth)acrylic resin-based dispersant (A1) obtained in the above step, inorganic fine particles (B1), a solvent (C1), and a binder resin (D1).

[0057] A conductive paste composition according to another embodiment of the present invention (hereinafter also referred to as conductive paste composition (2)) contains a (meth)acrylic resin-based dispersant (A2), inorganic particles (B2), and a solvent (C2), in which the (meth)acrylic resin-based dispersant (A2) contains 50% by weight or more of segments derived from a (meth)acrylic acid ester having a branched structure in an ester substituent and 1% by weight to 30% by weight of segments derived from a (meth)acrylic acid ester containing oxygen in the ester substituent, and in which the (meth)acrylic acid ester containing oxygen in the ester substituent has a weight ratio of oxygen in the ester substituent of 0.28 to 0.36 and a weight ratio of oxygen in the ester substituent in the molecule of 0.23 to 0.33, the inorganic particles (B2) comprise conductive particles having an average particle size of 0.05 μm to 10 μm, and the solvent (C2) has a boiling point of 200° C. to 250° C.

[0058] The (meth)acrylic resin-based dispersant (A2) may have the same structure as the (meth)acrylic resin-based dispersant (A1) described above, and the inorganic particles (B2) and the solvent (C2) may have the same structure as the inorganic particles (B1) and the solvent (C1) described above.

[0059] The conductive paste composition (2) may further contain a binder resin (D2), but when a method that does not require a high viscosity of the paste, such as a dispense method, is used as the paste printing step, or when the molecular weight of the (meth)acrylic resin-based dispersant (A2) is high and contributes greatly to the paste viscosity, the binder resin (D2) does not need to be added. Note that, as the binder resin (D2), a resin component of the above-mentioned binder resin (D1) that is different from the (meth)acrylic resin-based dispersant (A2) can be used.

[0060] In the conductive paste composition (2), the weight ratio of the (meth)acrylic resin-based dispersant (A2) to the binder resin (D2) is preferably 100:0 to 5:95, more preferably 100:0 to 50:50. By setting the weight ratio within this range, a conductive paste composition having a good balance between storage stability and sinterability can be obtained.

[0061] The content of the (meth)acrylic resin-based dispersant (A2) in the conductive paste composition (2) is preferably 3 wt % or more, more preferably 3.5 wt % or more, and even more preferably 4 wt % or more, and is preferably 30 wt % or less, more preferably 20 wt % or less, and even more preferably 12 wt % or less. By setting the content of the (meth)acrylic resin-based dispersant (A2) within the above range, a conductive paste composition that can be fired at a low temperature can be obtained.

[0062] The content of the conductive particles in the conductive paste composition (2) is preferably 50% by weight or more, more preferably 55% by weight or more, even more preferably 60% by weight or more, even more preferably 65% ​​by weight or more, and is preferably 85% by weight or less, more preferably 80% by weight or less, even more preferably 75% by weight or less, and even more preferably 70% by weight or less. By setting the content within the above range, a conductive paste composition with excellent printability can be obtained.

[0063] The content of inorganic particles other than the conductive particles in the conductive paste composition is preferably 0.1 wt % or more, more preferably 1 wt % or more, and is preferably 5 wt % or less, more preferably 3 wt % or less.

[0064] The content of the inorganic particles (B2) in the conductive paste composition (2) is preferably 50% by weight or more, more preferably 55% by weight or more, and even more preferably 65% ​​by weight or more, and is preferably 85% by weight or less, more preferably 80% by weight or less, and even more preferably 75% by weight or less. By setting the content within the above range, a conductive paste composition with excellent printability can be obtained.

[0065] The content of the solvent (C2) in the conductive paste composition (2) is preferably 5 wt % or more, more preferably 10 wt % or more, and is preferably 30 wt % or less, more preferably 25 wt % or less. By setting the content within the above range, coatability and dispersibility of the conductive metal particles can be improved.

[0066] The total amount of the (meth)acrylic resin in the conductive paste composition (2) is preferably 1 wt % or more, more preferably 3 wt % or more, and is preferably 15 wt % or less, more preferably 10 wt % or less, where the total amount of the (meth)acrylic resin means the combined amount of the (meth)acrylic resin-based dispersant (A2) and the binder resin (D2).

[0067] The conductive paste composition (2) may further contain additives such as a sintering aid.

[0068] The viscosity of the conductive paste composition (2) is preferably 0.1 Pa s as a lower limit and 100 Pa s as an upper limit when measured at 20°C using a Brookfield viscometer with a probe rotation speed of 5 rpm. By setting the viscosity to 0.1 Pa s or more, the resulting conductive metal particle-dispersed sheet can maintain a predetermined shape after application by a die coating printing method or the like. Furthermore, by setting the viscosity to 100 Pa s or less, dripping when the conductive paste composition is filled into a through via can be prevented, improving printability.

[0069] The method for preparing the conductive paste composition (2) is not particularly limited, and examples thereof include conventional stirring methods. Specific examples include a method in which the (meth)acrylic resin-based dispersant (A2), the inorganic particles (B2), the solvent (C2), and other components, such as a binder resin (D2), which is added as needed, are stirred using a triple roll or the like. Another example includes a method in which the inorganic particles (B2), and other components, such as an additional solvent (C2) or a binder resin (D2), which are added as needed, are added to the resin solution obtained after the reaction in preparing the (meth)acrylic resin-based dispersant (A2), and the mixture is stirred using a triple roll or the like. A preferred method for preparing the conductive paste composition (2) includes a step of preparing the (meth)acrylic resin-based dispersant (A2) by solution polymerization using an organic peroxide in which the carbon adjacent to the peroxide bond is a primary carbon, as a polymerization initiator, and a step of mixing the (meth)acrylic resin-based dispersant (A2), inorganic particles (B2), and solvent (C2) obtained in the previous step. The present invention also provides a method for producing the conductive paste composition, comprising: a step of preparing a (meth)acrylic resin-based dispersant (A2) by a solution polymerization method using an organic peroxide as a polymerization initiator, in which the carbon adjacent to a peroxide bond is a primary carbon; and a step of mixing the (meth)acrylic resin-based dispersant (A2) obtained in the above step, inorganic fine particles (B2), and a solvent (C2).

[0070] The conductive paste composition is printed on a substrate, dried to remove the solvent (C), and then heated in a firing furnace under an inert gas atmosphere such as nitrogen to degrease the resin components such as the (meth)acrylic resin, and sinter the inorganic particles (B), thereby producing an electronic component exhibiting high conductivity. Examples of such electronic components include die attach paste (ACP), die attach film (ACF), via electrodes for TSV and TGV, touch panels, various circuits for RFID and sensor substrates, various die bonding agents, sealants for MEMS devices, and electrode materials for solar cells, multilayer ceramic capacitors, LTCC, silicon capacitors, and all-solid-state batteries. In addition to the electrode circuit applications, the composition can also be used for antibacterial materials, electromagnetic wave shielding, catalysts, fluorescent materials, and the like. The printing method is not particularly limited, and examples include screen printing, die coating, offset printing, gravure printing, dipping, spray coating, and inkjet printing.

[0071] For example, the conductive paste composition can be applied to ceramic green sheets by a printing process, and a plurality of these sheets can be stacked and heated and pressed to form a laminate. The laminate can then be degreased and fired to form a sintered ceramic body, and external electrodes can be formed on the end faces of the sintered ceramic body to obtain a multilayer ceramic capacitor.

[0072] The drying method is not particularly limited, and for example, a fan oven can be used. The drying temperature is not particularly limited, and for example, is 100°C or higher and 150°C or lower.

[0073] The firing conditions are not particularly limited, but firing is preferably performed at a temperature of 280°C or less, more preferably at a temperature of 250°C or less. The temperature rise rate is preferably 20°C / min or more. Firing is preferably performed in a nitrogen atmosphere. If the surface oxidation of the conductive metal particles is severe, hydrogen may be added to the nitrogen gas introduced into the firing furnace. The firing process is preferably performed in an electric furnace, muffle furnace, plasma furnace, or the like, in an inert gas atmosphere such as nitrogen.

[0074] Furthermore, in the case of planar electronic components, firing can also be performed by hot pressing. The conditions for hot pressing are not particularly limited, but firing is preferably performed at a temperature of 200° C. to 280° C. and a pressure of 1 MPa to 5 MPa.

[0075] Furthermore, the surface of the fired metal electrode or the like may be protected to prevent oxidation. Examples of the surface protection method include a method of coating with a liquid epoxy resin composition and a method of casting a solution containing EVA, styrene, or the like.

[0076] According to the present invention, there is provided a conductive paste composition having good dispersibility of inorganic particles, sufficient storage stability, and excellent electrode adhesion, blister resistance, and sintering properties. Furthermore, there are also provided a method for producing the conductive paste composition and a method for producing an electronic component using the conductive paste composition.

[0077] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0078] (Example 1) (Synthesis Example 1) <Preparation of (meth)acrylic resin-based dispersant (A)> A 2 L separable flask equipped with a stirrer, a condenser, a thermometer, a hot water bath, and a nitrogen gas inlet was prepared. 100 parts by weight of monomers having the blending ratio shown in Table 1 were added to the 2 L separable flask. Furthermore, 100 parts by weight of terpineol as an organic solvent and 1.82 parts by weight of mercaptopropanediol as a chain transfer agent were mixed to obtain a monomer mixture.

[0079] The resulting monomer mixture was bubbled with nitrogen gas for 20 minutes to remove dissolved oxygen and replace it with nitrogen gas. The internal temperature was raised to 80°C while stirring, and a polymerization initiator was added. The polymerization initiator was also added several times during polymerization. Dilauryl peroxide was used as the polymerization initiator. Seven hours after the polymerization initiator, the mixture was cooled to room temperature to terminate the polymerization, yielding a composition containing a (meth)acrylic resin-based dispersant (A). The resulting composition containing a (meth)acrylic resin-based dispersant (A) was dried and dissolved in tetrahydrofuran (THF) at a resin concentration of 0.1 wt %. The weight average molecular weight (Mw) in terms of polystyrene was measured by GPC using a SHODEX LF-804 column, and found to be 50,000. The (meth)acrylic resin-based dispersant (A) was also dissolved in deuterated chloroform, １ Using a H-NMR (JEOL "ECX-400"), the measurement was performed at 400 MHz, at a measurement temperature of 80°C, and with an accumulation count of 1024. １ The structure was identified by H-NMR spectrum, and it was confirmed that the compound had multiple hydroxyl groups at the molecular terminals.

[0080] <Preparation of Conductive Paste Composition> The solid content of the composition containing the (meth)acrylic resin-based dispersant (A) was measured using a fan oven to confirm the resin concentration. To a composition containing the (meth)acrylic resin-based dispersant (A) as resin component (1), conductive metal particles, low-melting glass, additional solvent, and additional resin component (2) were added in the types and compositions shown in Table 3, and the mixture was stirred with a high-speed stirrer, followed by a three-roll mill process to obtain a conductive paste composition. The following metal particles, low-melting glass, and additional resin component (2) were used. Metal particles: copper powder, average particle diameter 10 μm, manufactured by Mitsui Kinzoku Co., Ltd. Low-melting point glass: boric acid glass frit, ASF-1096, Tg: 405°C, average particle diameter 1 μm, manufactured by AGC Resin component (2): (binder resin) isobutyl methacrylate (iBMA)-methyl methacrylate (MMA) copolymer (iMBA-MMA copolymer), blending ratio (weight ratio): iBMA / MMA = 50 / 50, weight average molecular weight 200,000

[0081] (Example 2) (Synthesis Example 2) The compounding ratio of the monomers was as shown in Table 1. In addition, 0.72 parts by weight of mercaptosuccinic acid was used as a chain transfer agent. A composition containing a (meth)acrylic resin-based dispersant (A) was obtained in the same manner as in Synthesis Example 1, except for the above.

[0082] To a composition containing the above-mentioned (meth)acrylic resin-based dispersant (A) as the resin component (1), conductive metal particles, low-melting glass, additional solvent, and additional resin component (2) were added in the types and proportions shown in Table 3, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles used were as follows: Metal particles: copper powder, average particle size 5 μm, manufactured by Mitsui Kinzoku Co., Ltd.

[0083] (Example 3) (Synthesis Example 3) The blending ratios of the monomers were as shown in Table 1. In addition, 0.11 parts by weight of mercaptopropanediol was used as a chain transfer agent, and 100 parts by weight of dihydroterpineol was used as a solvent. A composition containing a (meth)acrylic resin-based dispersant (A) was obtained in the same manner as in Synthesis Example 1, except for the above.

[0084] To a composition containing the (meth)acrylic resin-based dispersant (A) as resin component (1), conductive metal particles, low-melting glass, an additional solvent, and additional resin component (2) were added in the types and proportions shown in Table 3, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles and additional resin component (2) used were as follows: Metal particles: copper powder, average particle size 1 μm, manufactured by Mitsui Kinzoku Co., Ltd. Additional resin component (2): (meth)acrylic resin-based dispersant (A) obtained in the same manner as in Synthesis Example 3. The (meth)acrylic resin-based dispersant (A) can also function as a binder resin.

[0085] (Example 4) (Synthesis Example 4) The blending ratio of the monomers was as shown in Table 1. In addition, 0.6 parts by weight of mercaptosuccinic acid was used as a chain transfer agent, and 100 parts by weight of butyl carbitol was used as a solvent. A composition containing a (meth)acrylic resin-based dispersant (A) was obtained in the same manner as in Synthesis Example 1, except for the above.

[0086] To a composition containing the (meth)acrylic resin-based dispersant (A) as resin component (1), conductive metal particles, low-melting point glass, an additional solvent, and additional resin component (2) were added in the types and proportions shown in Table 3, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles and additional resin component (2) used were as follows: Metal particles: silver powder, average particle size 1 μm, manufactured by AS ONE Corporation Additional resin component (2): (meth)acrylic resin-based dispersant (A) obtained in the same manner as in Synthesis Example 4 The (meth)acrylic resin-based dispersant (A) can also function as a binder resin.

[0087] (Example 5) (Synthesis Example 5) The blending ratio of the monomers was as shown in Table 1. In addition, 0.6 parts by weight of mercaptopropanediol was used as a chain transfer agent, and 100 parts by weight of butyl carbitol was used as a solvent. A composition containing a (meth)acrylic resin-based dispersant (A) was obtained in the same manner as in Synthesis Example 1, except for the above.

[0088] To a composition containing the above-mentioned (meth)acrylic resin-based dispersant (A) as resin component (1), conductive metal particles, low-melting glass, additional solvent, and additional resin component (2) were added in the types and proportions shown in Table 3, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles and additional resin component (2) used were as follows: Metal particles: silver powder, average particle size 10 μm, manufactured by Aldrich; Additional resin component (2): (binder resin) isobutyl methacrylate (iBMA) polymer (iBMA polymer), weight-average molecular weight 200,000.

[0089] (Example 6) (Synthesis Example 6) The blending ratio of the monomers was as shown in Table 1. In addition, 1.34 parts by weight of mercaptosuccinic acid was used as a chain transfer agent, and 100 parts by weight of butyl carbitol was used as a solvent. A composition containing a (meth)acrylic resin-based dispersant (A) was obtained in the same manner as in Synthesis Example 1, except for the above.

[0090] To a composition containing the above-mentioned (meth)acrylic resin-based dispersant (A) as the resin component (1), conductive metal particles, low-melting glass, additional solvent, and additional resin component (2) were added in the types and proportions shown in Table 3, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles used were as follows: Metal particles: silver powder, average particle size 5 μm, manufactured by AS ONE Corporation

[0091] (Example 7) (Synthesis Example 7) The blending ratio of the monomers was as shown in Table 1. In addition, 0.31 parts by weight of mercaptosuccinic acid was used as a chain transfer agent, and 100 parts by weight of butyl carbitol was used as a solvent. A composition containing a (meth)acrylic resin-based dispersant (A) was obtained in the same manner as in Synthesis Example 1, except for the above.

[0092] To a composition containing the above-mentioned (meth)acrylic resin-based dispersant (A) as the resin component (1), conductive metal particles, low-melting glass, additional solvent, and additional resin component (2) were added in the types and proportions shown in Table 3, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles used were as follows: Metal particles: copper powder, average particle size 0.1 μm, manufactured by Filgen

[0093] (Example 8) (Synthesis Example 8) The blending ratio of the monomers was as shown in Table 1. In addition, 0.2 parts by weight of mercaptosuccinic acid was used as a chain transfer agent, and 100 parts by weight of butyl carbitol acetate was used as a solvent. A composition containing a (meth)acrylic resin-based dispersant (A) was obtained in the same manner as in Synthesis Example 1, except for the above.

[0094] To a composition containing the above-mentioned (meth)acrylic resin-based dispersant (A) as the resin component (1), conductive metal particles, low-melting glass, additional solvent, and additional resin component (2) were added in the types and proportions shown in Table 3, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles used were as follows: Metal particles: silver powder, average particle size 0.1 μm, manufactured by Aldrich Chemical Co.

[0095] (Example 9) (Synthesis Example 9) The compounding ratio of the monomers was as shown in Table 1. In addition, 0.5 parts by weight of mercaptosuccinic acid was used as a chain transfer agent. A composition containing a (meth)acrylic resin-based dispersant (A) was obtained in the same manner as in Synthesis Example 1, except for the above.

[0096] To a composition containing the above-mentioned (meth)acrylic resin-based dispersant (A) as the resin component (1), conductive metal particles, low-melting glass, additional solvent, and additional resin component (2) were added in the types and proportions shown in Table 3, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles used were as follows: Metal particles: copper powder, average particle size 0.05 μm, manufactured by Aldrich

[0097] (Example 10) (Synthesis Example 10) The blending ratio of the monomers was as shown in Table 1. In addition, 1.7 parts by weight of mercaptosuccinic acid was used as a chain transfer agent, and 100 parts by weight of butyl carbitol was used as a solvent. A composition containing a (meth)acrylic resin-based dispersant (A) was obtained in the same manner as in Synthesis Example 1, except for the above.

[0098] To a composition containing the (meth)acrylic resin-based dispersant (A) as resin component (1), conductive metal particles, low-melting glass, an additional solvent, and additional resin component (2) were added in the types and proportions shown in Table 3, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles and additional resin component (2) used were as follows: Metal particles: silver powder, average particle size 0.05 μm, manufactured by Aldrich Chemicals Additional resin component (2): (meth)acrylic resin-based dispersant (A) obtained in the same manner as in Synthesis Example 10 The (meth)acrylic resin-based dispersant (A) can also function as a binder resin.

[0099] (Comparative Example 1) (Synthesis Example 11) The compounding ratio of the monomers was as shown in Table 2. In addition, no chain transfer agent was added. A composition containing a (meth)acrylic resin-based dispersant (A) was obtained in the same manner as in Synthesis Example 1, except for the above.

[0100] To a composition containing the (meth)acrylic resin-based dispersant (A) as the resin component (1), conductive metal particles, low-melting glass, and additional solvent were added in the types and proportions shown in Table 3, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles used were as follows: Metal particles: copper powder, average particle size 1 μm, manufactured by Mitsui Kinzoku Co., Ltd.

[0101] (Comparative Example 2) (Synthesis Example 12) The blending ratios of the monomers were as shown in Table 2. 0.3 parts by weight of mercaptoethanol was used as a chain transfer agent, and 100 parts by weight of dihydroterpineol was used as a solvent. A composition containing a (meth)acrylic resin-based dispersant (A) was obtained in the same manner as in Synthesis Example 1, except for the above.

[0102] To a composition containing the above-mentioned (meth)acrylic resin-based dispersant (A) as the resin component (1), conductive metal particles, low-melting glass, additional solvent, and additional resin component (2) were added in the types and proportions shown in Table 3, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles used were as follows: Metal particles: copper powder, average particle size 1 μm, manufactured by Mitsui Kinzoku Co., Ltd.

[0103] (Comparative Example 3) (Synthesis Example 13) The blending ratios of the monomers were as shown in Table 2. 0.2 parts by weight of mercaptopropionic acid was used as a chain transfer agent, and 100 parts by weight of dihydroterpineol was used as a solvent. A composition containing a (meth)acrylic resin-based dispersant (A) was obtained in the same manner as in Synthesis Example 1, except for the above.

[0104] To a composition containing the above-mentioned (meth)acrylic resin-based dispersant (A) as the resin component (1), conductive metal particles, low-melting glass, additional solvent, and additional resin component (2) were added in the types and proportions shown in Table 3, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles used were as follows: Metal particles: copper powder, average particle size 1 μm, manufactured by Mitsui Kinzoku Co., Ltd.

[0105] (Comparative Example 4) (Synthesis Example 14) The blending ratios of the monomers were as shown in Table 2. 0.3 parts by weight of mercaptoethanol was used as a chain transfer agent, and 100 parts by weight of dihydroterpineol was used as a solvent. A composition containing a (meth)acrylic resin-based dispersant (A) was obtained in the same manner as in Synthesis Example 1, except for the above.

[0106] To a composition containing the above-mentioned (meth)acrylic resin-based dispersant (A) as the resin component (1), conductive metal particles, low-melting glass, additional solvent, and additional resin component (2) were added in the types and proportions shown in Table 3, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles used were as follows: Metal particles: copper powder, average particle size 1 μm, manufactured by Mitsui Kinzoku Co., Ltd.

[0107] (Comparative Example 5) (Synthesis Example 15) The blending ratios of the monomers were as shown in Table 2. 0.2 parts by weight of mercaptopropionic acid was used as a chain transfer agent, and 100 parts by weight of dihydroterpineol was used as a solvent. A composition containing a (meth)acrylic resin-based dispersant (A) was obtained in the same manner as in Synthesis Example 1, except for the above.

[0108] To a composition containing the above-mentioned (meth)acrylic resin-based dispersant (A) as the resin component (1), conductive metal particles, low-melting glass, additional solvent, and additional resin component (2) were added in the types and proportions shown in Table 3, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles and binder resin (D) used were as follows: Metal particles: copper powder, average particle diameter 1 μm, manufactured by Mitsui Kinzoku Co., Ltd.

[0109] (Comparative Example 6) (Synthesis Example 16) The blending ratios of the monomers were as shown in Table 2. 0.3 parts by weight of mercaptoethanol was used as a chain transfer agent, and 100 parts by weight of butyl carbitol was used as a solvent. A composition containing a (meth)acrylic resin-based dispersant (A) was obtained in the same manner as in Synthesis Example 1, except for the above.

[0110] To a composition containing the above-mentioned (meth)acrylic resin-based dispersant (A) as the resin component (1), conductive metal particles, low-melting glass, additional solvent, and additional resin component (2) were added in the types and proportions shown in Table 3, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles and binder resin (D) used were as follows: Metal particles: silver powder, average particle diameter 10 μm, manufactured by AS ONE Corporation

[0111] (Comparative Example 7) (Synthesis Example 17) The monomer blending ratios were as shown in Table 2. 1.82 parts by weight of mercaptopropanediol was used as the chain transfer agent, and ditertiary butyl peroxide was used as the polymerization initiator. Polymerization was carried out in the same manner as Synthesis Example 1 except for the above. However, the viscosity increased rapidly after the start of polymerization, and 3 hours after the start of polymerization, the polymerization liquid gelled and lost its fluidity. Therefore, it was not possible to prepare a conductive paste composition. It is believed that gelation occurred because ditertiary butyl peroxide, in which the carbon bonded to the peroxy group is a tertiary carbon, was used as the polymerization initiator.

[0112] (Comparative Example 8) (Synthesis Example 18) The blending ratios of the monomers were as shown in Table 2. 4.8 parts by weight of mercaptopropanediol was used as a chain transfer agent, and 100 parts by weight of butyl carbitol was used as a solvent. A composition containing a (meth)acrylic resin-based dispersant (A) was obtained in the same manner as in Synthesis Example 1, except for the above.

[0113] To a composition containing the above-mentioned (meth)acrylic resin-based dispersant (A) as the resin component (1), conductive metal particles, low-melting glass, additional solvent, and additional resin component (2) were added in the types and proportions shown in Table 3, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles used were as follows: Metal particles: silver powder, average particle size 12 μm, manufactured by AS ONE Corporation

[0114] (Comparative Example 9) (Synthesis Example 19) The blending ratios of the monomers were as shown in Table 2. 2.9 parts by weight of mercaptopropanediol was used as a chain transfer agent, and 100 parts by weight of butyl carbitol was used as a solvent. A composition containing a (meth)acrylic resin-based dispersant (A) was obtained in the same manner as in Synthesis Example 1, except for the above.

[0115] To a composition containing the above-mentioned (meth)acrylic resin-based dispersant (A) as the resin component (1), conductive metal particles, low-melting glass, additional solvent, and additional resin component (2) were added in the types and proportions shown in Table 3, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles used were as follows: Metal particles: silver powder, average particle diameter 1 μm, manufactured by AS ONE Corporation

[0116] (Comparative Example 10) (Synthesis Example 20) The blending ratios of the monomers were as shown in Table 2. 0.4 parts by weight of mercaptosuccinic acid was used as the chain transfer agent, and 100 parts by weight of triethylene glycol monoethyl ether was used as the solvent. A composition containing a (meth)acrylic resin-based dispersant (A) was obtained in the same manner as in Synthesis Example 1, except for the above.

[0117] To a composition containing the above-mentioned (meth)acrylic resin-based dispersant (A) as the resin component (1), conductive metal particles, low-melting glass, additional solvent, and additional resin component (2) were added in the types and proportions shown in Table 3, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles and binder resin (D) used were as follows: Metal particles: silver powder, average particle size 0.04 μm, manufactured by Mitsui Kinzoku Co., Ltd.

[0118] (Comparative Example 11) (Synthesis Example 21) The blending ratios of the monomers were as shown in Table 2. No chain transfer agent was added, and 100 parts by weight of diethylene glycol monomethyl ether was used as the solvent. A composition containing a (meth)acrylic resin-based dispersant (A) was obtained in the same manner as in Synthesis Example 1, except for the above.

[0119] To a composition containing the above-mentioned (meth)acrylic resin-based dispersant (A) as the resin component (1), conductive metal particles, low-melting glass, additional solvent, and additional resin component (2) were added in the types and proportions shown in Table 3, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles and binder resin (D) used were as follows: Metal particles: silver powder, average particle diameter 1 μm, manufactured by Aldrich Chemical Co.

[0120] (Example 11) Conductive metal particles, low-melting glass, an additional solvent, and an additional resin component (2) were added to a composition containing the (meth)acrylic resin-based dispersant (A) obtained in Synthesis Example 1 as the resin component (1) in the types and compositions shown in Table 4, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles used were as follows: Metal particles: Cu-Mg alloy (weight ratio Cu:Mg = 8:3), average particle size 10 μm, manufactured by Hikari Materials Industry Co., Ltd.

[0121] (Example 12) Conductive metal particles, low-melting glass, an additional solvent, and an additional resin component (2) were added to a composition containing the (meth)acrylic resin-based dispersant (A) obtained in Synthesis Example 2 as the resin component (1) in the types and compositions shown in Table 4, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles and binder resin (D) used were as follows: Metal particles: Cu-Dy alloy (weight ratio Cu:Dy = 5:11), average particle size 5 μm, manufactured by Furuuchi Chemical Co., Ltd.

[0122] Example 13 To a composition containing the (meth)acrylic resin-based dispersant (A) obtained in Synthesis Example 3 as the resin component (1), conductive metal particles, low-melting point glass, an additional solvent, and an additional resin component (2) were added in the types and proportions shown in Table 4, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles and additional resin component (2) used were as follows: Metal particles: Cu-Tb alloy (weight ratio Cu:Tb = 5:13), average particle size 1 μm, manufactured by Furuuchi Chemical Co., Ltd. Additional resin component (2): (meth)acrylic resin-based dispersant (A) obtained in the same manner as in Synthesis Example 3. The (meth)acrylic resin-based dispersant (A) can also function as a binder resin.

[0123] Example 14 To a composition containing the (meth)acrylic resin-based dispersant (A) obtained in Synthesis Example 4 as the resin component (1), conductive metal particles, low-melting point glass, an additional solvent, and additional resin component (2) were added in the types and proportions shown in Table 4, to obtain a conductive paste composition in the same manner as in Example 1. The metal particles and additional resin component (2) used were as follows: Metal particles: nickel powder, average particle size 1 μm, manufactured by JFE Mineral Co., Ltd. Additional resin component (2): (meth)acrylic resin-based dispersant (A) obtained in the same manner as in Synthesis Example 4. The (meth)acrylic resin-based dispersant (A) can also function as a binder resin.

[0124] (Example 15) Conductive metal particles, low-melting glass, an additional solvent, and an additional resin component (2) were added to a composition containing the (meth)acrylic resin-based dispersant (A) obtained in Synthesis Example 5 as the resin component (1) in the types and compositions shown in Table 4, and a conductive paste composition was obtained in the same manner as in Example 1. The following metal particles were used. Metal particles: Ag-Li alloy (weight ratio Ag:Li = 15:1), average particle size 10 μm, manufactured by Kojundo Chemical Research Institute Co., Ltd.

[0125] (Comparative Example 12) To a composition containing the (meth)acrylic resin-based dispersant (A) obtained in Synthesis Example 12 as the resin component (1), conductive metal particles, low-melting glass, an additional solvent, and an additional resin component (2) were added in the types and proportions shown in Table 4, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles used were as follows: Metal particles: Cu-Mg alloy (weight ratio Cu:Mg = 8:3), average particle size 10 μm, manufactured by Hikari Materials Industry Co., Ltd.

[0126] (Comparative Example 13) To a composition containing the (meth)acrylic resin-based dispersant (A) obtained in Synthesis Example 13 as the resin component (1), conductive metal particles, low-melting glass, an additional solvent, and an additional resin component (2) were added in the types and proportions shown in Table 4, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles used were as follows: Metal particles: Cu-Dy alloy (weight ratio Cu:Dy=5:11), average particle size 5 μm, manufactured by Furuuchi Chemical Co., Ltd.

[0127] (Comparative Example 14) To a composition containing the (meth)acrylic resin-based dispersant (A) obtained in Synthesis Example 14 as the resin component (1), conductive metal particles, low-melting glass, an additional solvent, and an additional resin component (2) were added in the types and proportions shown in Table 4, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles used were as follows: Metal particles: Cu-Tb alloy (weight ratio Cu:Tb = 5:13), average particle size 1 μm, manufactured by Furuuchi Chemical Co., Ltd.

[0128] (Comparative Example 15) To a composition containing the (meth)acrylic resin-based dispersant (A) obtained in Synthesis Example 15 as the resin component (1), conductive metal particles, low-melting glass, an additional solvent, and an additional resin component (2) were added in the types and proportions shown in Table 4, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles and binder resin (D) used were as follows: Metal particles: nickel powder, average particle size 1 μm, manufactured by JFE Mineral Co., Ltd.

[0129] (Comparative Example 16) To a composition containing the (meth)acrylic resin-based dispersant (A) obtained in Synthesis Example 16 as the resin component (1), conductive metal particles, low-melting glass, an additional solvent, and an additional resin component (2) were added in the types and proportions shown in Table 4, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles used were as follows: Metal particles: Ag-Li alloy (weight ratio Ag:Li = 15:1), average particle size 10 μm, manufactured by Kojundo Chemical Research Institute Co., Ltd.

[0130] (Example 16) (Synthesis Example 22) The blending ratios of the monomers were as shown in Table 1. 1.8 parts by weight of mercaptosuccinic acid was used as the chain transfer agent, and 100 parts by weight of butyl carbitol was used as the solvent. Furthermore, a composition containing a (meth)acrylic resin-based dispersant (A) was obtained in the same manner as in Synthesis Example 1, except that di(3,5,5-trimethylhexanoyl) peroxide was used as the polymerization initiator.

[0131] To a composition containing the (meth)acrylic resin-based dispersant (A) as resin component (1), conductive metal particles, low-melting point glass, an additional solvent, and additional resin component (2) were added in the types and proportions shown in Table 4, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles and additional resin component (2) used were as follows: Metal particles: silver powder, average particle size 0.05 μm, manufactured by Aldrich Chemicals Additional resin component (2): (meth)acrylic resin-based dispersant (A) obtained in the same manner as in Synthesis Example 22 The (meth)acrylic resin-based dispersant (A) can also function as a binder resin.

[0132] (Example 17) (Synthesis Example 23) The blending ratios of the monomers were as shown in Table 1. Furthermore, 0.08 parts by weight of mercaptopropanediol was used as a chain transfer agent, and 100 parts by weight of dihydroterpineol was used as a solvent. Furthermore, a composition containing a (meth)acrylic resin-based dispersant (A) was obtained in the same manner as in Synthesis Example 1, except that di(3,5,5-trimethylhexanoyl) peroxide was used as the polymerization initiator.

[0133] To a composition containing the (meth)acrylic resin-based dispersant (A) as resin component (1), conductive metal particles, low-melting point glass, an additional solvent, and additional resin component (2) were added in the types and proportions shown in Table 4, and a conductive paste composition was obtained in the same manner as in Example 7. The metal particles and additional resin component (2) used were as follows: Metal particles: copper powder, average particle size 1 μm, manufactured by Mitsui Kinzoku Co., Ltd. Additional resin component (2): (meth)acrylic resin-based dispersant (A) obtained in the same manner as in Synthesis Example 23. The (meth)acrylic resin-based dispersant (A) can also function as a binder resin.

[0134] (Example 18) Conductive metal particles, low-melting glass, an additional solvent, and an additional resin component (2) were added to a composition containing the (meth)acrylic resin-based dispersant (A) obtained in Synthesis Example 1 as the resin component (1) in the types and compositions shown in Table 4, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles used were as follows: Metal particles: Cu-Mg alloy (weight ratio Cu:Mg = 8:3), average particle size 10 μm, manufactured by Hikari Materials Industry Co., Ltd.

[0135] (Example 19) Conductive metal particles, low-melting glass, an additional solvent, and an additional resin component (2) were added to a composition containing the (meth)acrylic resin-based dispersant (A) obtained in Synthesis Example 10 as the resin component (1) in the types and compositions shown in Table 4, and a conductive paste composition was obtained in the same manner as in Example 1. The following metal particles were used. Metal particles: silver, average particle size 0.1 μm, manufactured by Aldrich

[0136] (Example 20) (Synthesis Example 24) The blending ratios of the monomers were as shown in Table 1. 1.3 parts by weight of mercaptopropionic acid was used as a chain transfer agent, and 100 parts by weight of butyl carbitol was used as a solvent. Furthermore, a composition containing a (meth)acrylic resin-based dispersant (A) was obtained in the same manner as in Synthesis Example 1, except that di(3,5,5-trimethylhexanoyl) peroxide was used as a polymerization initiator.

[0137] To a composition containing the above-mentioned (meth)acrylic resin-based dispersant (A) as the resin component (1), conductive metal particles, low-melting glass, additional solvent, and additional resin component (2) were added in the types and proportions shown in Table 4, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles used were as follows: Metal particles: silver powder, average particle size 0.1 μm, manufactured by Aldrich Chemical Co.

[0138] Example 21 Synthesis Example 25 The monomer blending ratios were as shown in Table 1. 0.9 parts by weight of mercaptoethanol was used as a chain transfer agent, and 100 parts by weight of terpineol was used as a solvent. Furthermore, a composition containing a (meth)acrylic resin-based dispersant (A) was obtained in the same manner as in Synthesis Example 1, except that di(3,5,5-trimethylhexanoyl) peroxide was used as a polymerization initiator.

[0139] To a composition containing the above-mentioned (meth)acrylic resin-based dispersant (A) as the resin component (1), conductive metal particles, low-melting glass, additional solvent, and additional resin component (2) were added in the types and proportions shown in Table 4, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles used were as follows: Metal particles: copper powder, average particle size 0.1 μm, manufactured by Mitsui Kinzoku Co., Ltd.

[0140] (Comparative Example 17) (Synthesis Example 26) The blending ratios of the monomers were as shown in Table 2. 1.5 parts by weight of mercaptosuccinic acid was used as the chain transfer agent, and 100 parts by weight of butyl carbitol was used as the solvent. Furthermore, a composition containing a (meth)acrylic resin-based dispersant (A) was obtained in the same manner as in Synthesis Example 6, except that t-butyl peroxyneodecanoate was used as the polymerization initiator.

[0141] To a composition containing the above-mentioned (meth)acrylic resin-based dispersant (A) as the resin component (1), conductive metal particles, low-melting glass, additional solvent, and additional resin component (2) were added in the types and proportions shown in Table 4, and a conductive paste composition was obtained in the same manner as in Example 1. The metal particles used were as follows: Metal particles: silver powder, average particle diameter 1 μm, manufactured by AS ONE Corporation

[0142]

[0143]

[0144]

[0145]

[0146] <Evaluation> The conductive paste compositions obtained in the examples and comparative examples were evaluated as follows. The results are shown in Table 5.

[0147] (1) Paste Storage Stability The conductive paste compositions obtained in the Examples and Comparative Examples were aged at room temperature for 10 days, and the dispersion state of the paste composition was checked and evaluated according to the following criteria. A conductive paste composition with excellent paste storage stability can be said to have excellent printability. ◯: No change in dispersion state △: A transparent supernatant layer was observed, and no metal precipitate layer was observed at the bottom of the container ×: A metal precipitate layer was observed at the bottom of the container

[0148] (2) Paste Viscosity Characteristics (Thixotropy) The viscosity of the conductive paste compositions obtained in the Examples and Comparative Examples was evaluated using a rheometer at shear rates varying from 1 (sec) to 100 (sec), and the thixotropy ratio was calculated using the following formula and evaluated according to the following criteria: Thixotropy value = viscosity 1 (sec) / viscosity 100 (sec) Good: Thixotropy value of 6 or more Fair: Thixotropy value of 4 or more but less than 6 Bad: Thixotropy value of less than 4

[0149] (3) Evaluation of Conductive Sheets The conductive paste compositions obtained in the Examples and Comparative Examples were applied to an alumina substrate using an applicator so that the thickness after drying would be 20 μm, and then dried in a blast oven at 150° C. for 1 hour to obtain conductive sheets.

[0150] (3-1) Cross-cut test Cuts were made in the conductive sheet at 1 cm intervals using a cutter knife, and the cuts were visually inspected and evaluated according to the following criteria. If there is no peeling or the like in the cross-cut area, it can be said that the conductive paste composition has excellent electrode adhesion. ◯: No peeling in the cross-cut area △: Roughness in the cross-cut area ×: Peeling occurs from the cross-cut area

[0151] (3-2) Blister Resistance The conductive sheet formed on the alumina substrate was held in an electric furnace in a nitrogen atmosphere at 300°C for 1 hour, and then the internal temperature was raised to 600°C. The state of the sheet was visually observed and evaluated according to the following criteria: ◯: No blistering occurred △: No blistering, but glass lifting ×: Blistering occurred

[0152] (4) Sinterability The conductive paste compositions obtained in the Examples and Comparative Examples were applied to a release PET film using an applicator to a thickness of 50 μm after drying, and then dried in a 100°C air oven for 1 hour to obtain a conductive sheet. The obtained conductive sheet was attached to a 50 μm-thick SiC substrate, the release PET film was peeled off, and the sheet was attached to a copper substrate to obtain a copper substrate-conductive sheet-SiC substrate laminate. The obtained laminate was pressed at 100°C and 3 MPa using a press, and then baked at 300°C for 20 minutes in a baking furnace in a nitrogen atmosphere to thermally decompose the organic matter in the conductive sheet. The oven was then heated to 400°C to sinter the copper. The sample was then cooled to room temperature in a nitrogen atmosphere to obtain a laminate sample. The cross-section of the bonded portion of the obtained laminate sample was observed using a scanning electron microscope and evaluated according to the following criteria: ◯: No large cracks or voids were observed in the cross-section; △: No voids, pinholes present; ×: Large cracks and voids were observed in the cross-section.

[0153]

[0154] All of Examples 1 to 10 had sufficient thixotropy, making the particles less likely to settle, and exhibited excellent storage stability. The electrodes also exhibited good adhesion, blister resistance, and sinterability. On the other hand, Comparative Examples 1 to 6 exhibited poor metal particle dispersibility, and Comparative Examples 8 to 11 exhibited peeling at the crosscut portions and blisters and voids during metal sintering.

[0155] According to the present invention, there is provided a conductive paste composition having good dispersibility of inorganic particles, sufficient storage stability, and excellent electrode adhesion, blister resistance, and sintering properties. Furthermore, there are also provided a method for producing the conductive paste composition and a method for producing an electronic component using the conductive paste composition.

Claims

1. A conductive paste composition comprising a (meth)acrylic resin-based dispersant (A1), inorganic particles (B1), a solvent (C1), and a binder resin (D1), wherein the (meth)acrylic resin-based dispersant (A1) contains 50% by weight or more of segments derived from a (meth)acrylic acid ester having a branched structure in an ester substituent and 1% by weight to 30% by weight or less of segments derived from a (meth)acrylic acid ester containing oxygen in the ester substituent, wherein the (meth)acrylic acid ester containing oxygen in the ester substituent has a weight ratio of oxygen in the ester substituent of 0.28 to 0.36 and a weight ratio of oxygen in the ester substituent in the molecule of 0.23 to 0.33, wherein the inorganic particles (B1) comprise conductive particles having an average particle size of 0.05 μm to 10 μm, wherein the solvent (C1) has a boiling point of 200°C to 250°C, and wherein the binder resin (D1) is a (meth)acrylic resin.

2. The conductive paste composition according to claim 1, wherein the content of segments derived from a (meth)acrylic acid ester having oxygen in the ester substituent in the (meth)acrylic resin-based dispersant (A1) is 5% by weight or more and 30% by weight or less, and the weight average molecular weight of the (meth)acrylic resin-based dispersant (A1) is 20,000 or more and less than 150,000.

3. The conductive paste composition according to claim 1 or 2, wherein the content of the (meth)acrylic resin-based dispersant (A1) is 3% by weight or more and 20% by weight or less.

4. The conductive paste composition according to claim 1, 2 or 3, wherein the (meth)acrylic resin-based dispersant (A1) has a weight average molecular weight of 20,000 or more and 140,000 or less.

5. The conductive paste composition according to claim 1, 2, 3 or 4, wherein the (meth)acrylic resin-based dispersant (A1) has a plurality of hydroxyl groups or carboxyl groups at one end of the molecular chain.

6. The conductive paste composition according to claim 1, 2, 3, 4 or 5, wherein the solvent (C1) is at least one selected from the group consisting of terpineol, dihydroterpineol and butyl carbitol.

7. The conductive paste composition according to claim 1, 2, 3, 4, 5 or 6, wherein the inorganic particles (B1) are conductive particles that are copper particles, and the (meth)acrylic resin-based dispersant (A1) is a (meth)acrylic acid ester containing oxygen in the ester substituent, wherein the weight ratio of oxygen in the ester substituent is 0.28 or more and 0.32 or less, and the weight ratio of oxygen in the ester substituent in the molecule is 0.24 or more and 0.27 or less.

8. The conductive paste composition according to claim 7, wherein in the (meth)acrylic resin-based dispersant (A1), the (meth)acrylic acid ester containing oxygen in the ester substituent contains a segment derived from polypropylene glycol.

9. The conductive paste composition according to claim 1, 2, 3, 4, 5 or 6, wherein the inorganic particles (B1) are conductive particles that are silver particles, and the (meth)acrylic resin-based dispersant (A1) is a (meth)acrylic acid ester containing oxygen in the ester substituent, wherein the weight ratio of oxygen in the ester substituent is 0.34 or more and 0.36 or less, and the weight ratio of oxygen in the ester substituent in the molecule is 0.23 or more and 0.33 or less.

10. The conductive paste composition according to claim 9, wherein in the (meth)acrylic resin-based dispersant (A1), the (meth)acrylic acid ester containing oxygen in the ester substituent contains a segment derived from polyethylene glycol.

11. The conductive paste composition according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, wherein in the binder resin (D1), the weight-average molecular weight of the (meth)acrylic resin is 100,000 or more and 1,000,000 or less, and the (meth)acrylic resin has a segment derived from isobutyl methacrylate and a segment derived from methyl methacrylate.

12. The conductive paste composition according to claim 11, wherein in the binder resin (D1), the (meth)acrylic resin contains 50% by weight or more of a segment derived from isobutyl methacrylate.

13. A conductive paste composition according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, wherein in the binder resin (D1), the (meth)acrylic resin contains 50% by weight or more of segments derived from a (meth)acrylic acid ester having a branched structure in an ester substituent and 1% by weight or more and 30% by weight or less of segments derived from a (meth)acrylic acid ester containing oxygen in the ester substituent, and in the (meth)acrylic acid ester containing oxygen in the ester substituent, the weight ratio of oxygen in the ester substituent is 0.28 to 0.36 and the weight ratio of oxygen in the ester substituent in the molecule is 0.23 to 0.

33.

14. The conductive paste composition according to claim 13, wherein the (meth)acrylic resin in the binder resin (D1) is the same (meth)acrylic resin as that in the (meth)acrylic resin-based dispersant (A1).

15. The conductive paste composition according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 or 14, wherein the material of the conductive particles in the inorganic particles (B1) is lithium, magnesium, nickel, dysprosium, terbium, or an alloy of any of these with copper or silver.

16. A method for producing a conductive paste composition according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15, comprising the steps of: preparing a (meth)acrylic resin-based dispersant (A1) by solution polymerization using an organic peroxide as a polymerization initiator, in which the carbon adjacent to the peroxide bond is a primary carbon; and mixing the (meth)acrylic resin-based dispersant (A1) obtained in the step, inorganic fine particles (B1), a solvent (C1) and a binder resin (D1).

17. A conductive paste composition comprising a (meth)acrylic resin-based dispersant (A2), inorganic particles (B2), and a solvent (C2), wherein the (meth)acrylic resin-based dispersant (A2) contains 50% by weight or more of segments derived from a (meth)acrylic acid ester having a branched structure in the ester substituent and 1% by weight to 30% by weight or less of segments derived from a (meth)acrylic acid ester containing oxygen in the ester substituent, wherein the (meth)acrylic acid ester containing oxygen in the ester substituent has a weight ratio of oxygen in the ester substituent of 0.28 to 0.36 and a weight ratio of oxygen in the ester substituent in the molecule of 0.23 to 0.33, wherein the inorganic particles (B2) comprise conductive particles having an average particle size of 0.05 μm to 10 μm, and wherein the solvent (C2) has a boiling point of 200°C to 250°C.

18. The conductive paste composition according to claim 17, wherein the content of segments derived from a (meth)acrylic acid ester having oxygen in the ester substituent in the (meth)acrylic resin-based dispersant (A2) is 5% by weight or more and 30% by weight or less, and the weight average molecular weight of the (meth)acrylic resin-based dispersant (A2) is 20,000 or more and less than 150,000.

19. The conductive paste composition according to claim 17 or 18, wherein the content of the (meth)acrylic resin-based dispersant (A2) is 3% by weight or more and 20% by weight or less.

20. The conductive paste composition according to claim 17, 18 or 19, wherein the weight-average molecular weight of the (meth)acrylic resin-based dispersant (A2) is 20,000 or more and 140,000 or less.

21. The conductive paste composition according to claim 17, 18, 19 or 20, wherein the (meth)acrylic resin-based dispersant (A2) has a plurality of hydroxyl groups or carboxyl groups at one end of the molecular chain.

22. The conductive paste composition according to claim 17, 18, 19, 20 or 21, wherein the solvent (C2) is at least one selected from the group consisting of terpineol, dihydroterpineol and butyl carbitol.

23. A conductive paste composition according to claim 17, 18, 19, 20, 21 or 22, wherein the inorganic particles (B2) are conductive particles that are copper particles, and the (meth)acrylic resin-based dispersant (A2) is a (meth)acrylic acid ester containing oxygen in the ester substituent, wherein the weight ratio of oxygen in the ester substituent is 0.28 or more and 0.32 or less, and the weight ratio of oxygen in the ester substituent in the molecule is 0.24 or more and 0.27 or less.

24. The conductive paste composition according to claim 23, wherein in the (meth)acrylic resin-based dispersant (A2), the (meth)acrylic acid ester containing oxygen in the ester substituent contains a segment derived from polypropylene glycol.

25. A conductive paste composition according to claim 17, 18, 19, 20, 21 or 22, wherein the inorganic particles (B2) are conductive particles that are silver particles, and the (meth)acrylic resin-based dispersant (A2) is such that the weight ratio of oxygen in the ester substituent of the (meth)acrylic acid ester containing oxygen in the ester substituent is 0.34 or more and 0.36 or less, and the weight ratio of oxygen in the ester substituent in the molecule is 0.23 or more and 0.33 or less.

26. The conductive paste composition according to claim 25, wherein in the (meth)acrylic resin-based dispersant (A2), the (meth)acrylic acid ester containing oxygen in the ester substituent contains a segment derived from polyethylene glycol.

27. The conductive paste composition according to claim 17, 18, 19, 20, 21, 22, 23, 24, 25, or 26, further comprising a binder resin (D2), wherein the binder resin (D2) is a (meth)acrylic resin, the weight-average molecular weight of the (meth)acrylic resin is 100,000 or more and 1,000,000 or less, and the (meth)acrylic resin has a segment derived from isobutyl methacrylate and a segment derived from methyl methacrylate.

28. The conductive paste composition according to claim 27, wherein in the binder resin (D2), the (meth)acrylic resin contains 50% by weight or more of a segment derived from isobutyl methacrylate.

29. A method for producing a conductive paste composition according to claim 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27 or 28, comprising the steps of: preparing a (meth)acrylic resin-based dispersant (A2) by solution polymerization using an organic peroxide as a polymerization initiator, in which the carbon adjacent to the peroxide bond is a primary carbon; and mixing the (meth)acrylic resin-based dispersant (A2) obtained in the step, inorganic fine particles (B2) and a solvent (C2).

30. A method for producing an electronic component, using the conductive paste composition according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27 or 28.