Conductive paste composition and electronic device

Abstract

The present invention relates to a conductive paste composition comprising (meth)acrylic resin (A), inorganic particles (B), and solvent (C), wherein the (meth)acrylic resin (A) has a weight-average molecular weight (Mw) of 20,000 to 600,000, and contains 50% by weight or more of segments derived from alkyl (meth)acrylate ester having an alkyl branched structure in the ester substituent, and 5% by weight or more to 40% by weight of segments derived from (meth)acrylic acid ester having polyalkylene oxide groups with ester substituents distributed along the chain length, wherein the ratio of peak top molecular weight (XP) to molecular weight dispersion width (ML) (XP / ML) of the polyalkylene oxide group as evaluated by LC-MS is 0.5 to 1.5, the inorganic particles (B) contain conductive particles with an average particle diameter of 0.01 μm to 10 μm, and the solvent (C) is an organic solvent with a boiling point of 200°C to 250°C.

Description

Technical Field

[0001] The present invention relates to a conductive paste composition and an electronic device.

Background Art

[0002] Conventionally, conductive paste compositions have been widely used in the manufacture of solar cells, multilayer ceramic capacitors, and the like. A conductive paste composition is a dispersion of 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 ratios of the binder and inorganic particles.

[0003] Examples of conductive particles used in conductive paste compositions include silver, nickel, and copper. Since the sintering temperature can be significantly lowered by making the average particle size of these conductive particles nano-sized, metal pastes using nano-conductive particles have been studied for various applications. For example, in Patent Document 1, silver particles (A), a resin (B) that is solid at 25°C, and an organic cyclic ether compound (C) having a flash point of 50 to 200°C are essential components, and 15 to 30 parts of the organic cyclic ether compound (C) are included per 100 parts of the silver particles (A), and the resin (B) is a vinyl chloride-vinyl acetate copolymer and / or a linear polyester resin. A conductive silver paste has been studied. Further, in Patent Document 2, it has been studied to use an acrylic resin containing units of a (meth)acrylate monomer A having a polyalkylene glycol moiety and units of a (meth)acrylate monomer B having a hydrophobic group, and having a carboxylic acid group or a carboxylate group at at least one terminal as a binder resin.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] Patent Document 1 states that adding a highly flammable organic cyclic ether compound with a flash point of 50-200°C improves the dispersibility of nanoconductive particles, which are difficult to disperse. Furthermore, Patent Document 2 states that, in addition to the polyalkylene glycol moiety, having carboxylic acid groups or the like at the terminal ends allows the carboxylic acid groups or the like to exhibit appropriate interactions with metal particles, thereby improving dispersibility. However, Patent Document 1 uses a flame-retardant vinyl chloride resin as the binder resin, which has the problem of inhibiting the combustion of organic cyclic ether compounds and causing blistering. Furthermore, the binder resin in Patent Document 2 is brittle due to its low molecular weight, and because the ether chain length in the molecular chain is long, it easily forms an intramolecular phase separation structure, which causes problems such as pinholes and blistering during firing.

[0006] In view of the above circumstances, the present invention aims to provide a conductive paste composition that exhibits good dispersibility of inorganic particles, sufficient storage stability, suppression of void and pinhole generation during firing, good dispersibility of organic components, excellent electrode adhesion, and excellent blister resistance. The present invention also aims to provide an electronic device using the conductive paste composition. [Means for solving the problem]

[0007] Disclosure 1 comprises a (meth)acrylic resin (A), inorganic particles (B), and a solvent (C), wherein the (meth)acrylic resin (A) has a weight-average molecular weight (Mw) of 20,000 to 600,000, and contains 50% by weight or more of a segment derived from an alkyl (meth)acrylate ester having an alkyl branched structure in its ester substituent, and 5% by weight or more of a segment derived from a (meth)acrylic acid ester having a polyalkylene oxide group with ester substituents distributed along the chain length, wherein the peak top molecular weight (X) of the polyalkylene oxide group as evaluated by LC-MSP ) and the ratio (X L ) to the molecular weight distribution width (M P / M L ) is 0.5 or more and 1.5 or less, the inorganic particles (B) contain conductive particles having an average particle diameter of 0.01 μm or more and 10 μm or less, and the solvent (C) is an organic solvent having a boiling point of 200°C or more and 250°C or less. It is a conductive paste composition. In the second disclosure, the peak top molecular weight (X P ) of the polyalkylene oxide group and the number average molecular weight (Mn) of the (meth)acrylic resin (A), the ratio (X P / Mn) is 0.002 or more and 0.12 or less, and it is the conductive paste composition of the first disclosure. In the third disclosure, the (meth)acrylic resin (A) has, in the measurement of the decomposition end temperature T by TG-DTA, the decomposition end temperature T under the condition of a heating rate of 100°C / min 100 and the decomposition end temperature T at a heating rate of 10°C / min 10 The difference (T 100 -T 10 ) is 50°C or less, and it is the conductive paste composition of the first or second disclosure. In the fourth disclosure, the (meth)acrylic resin (A) has a plurality of hydroxyl groups or carboxylic acid polar functional groups at one end of the molecular chain, and it is the conductive paste composition of the first, second or third disclosure. In the fifth disclosure, the solvent (C) is any one of terpineol, dihydroterpineol and butyl carbitol, and it is the conductive paste composition of the first, second, third or fourth disclosure. In the sixth disclosure, the material of the conductive particles contains silver or copper, and it is the conductive paste composition of the first, second, third, fourth or fifth disclosure. In the seventh disclosure, it is an electronic device using the conductive paste composition of the first, second, third, fourth, fifth or sixth disclosure. The present invention will be described in detail below.

[0008] The inventors noted that while conventional (meth)acrylic resins having polyalkylene oxide moieties can improve the dispersibility of conductive metal particles, problems such as pinholes and blistering occur. Therefore, they investigated the use of various (meth)acrylic resins. As a result, they discovered that (meth)acrylic resins containing a predetermined proportion of segments derived from alkyl (meth)acrylate esters having an alkyl branched structure and a weight-average molecular weight within a predetermined range, and polyalkylene oxides with ester substituents distributed along the chain length that satisfy predetermined physical properties, exhibit superior characteristics. Specifically, they found that such (meth)acrylic resins can improve the dispersibility of conductive metal particles, particularly silver and copper particles, and suppress voids and pinholes during firing. Furthermore, they discovered that using such (meth)acrylic resins improves the dispersibility of organic components, enabling the production of conductive paste compositions with excellent electrode adhesion and blister resistance, thus completing the present invention.

[0009] <(Meth)acrylic resin (A)> The above conductive paste composition contains (meth)acrylic resin (A). The above (meth)acrylic resin (A) contains segments derived from a (meth)acrylic acid ester, which is a polyalkylene oxide group in which the ester substituents are distributed along the chain length. Here, "(meth)acrylic acid ester" means acrylic acid ester or methacrylic acid ester. Furthermore, the ester substituent mentioned above refers to a substituent bonded to the ester bond that is different from the substituent that constitutes the (meth)acryloyl group, and specifically refers to the X portion of the structure represented by CH2=CR-(C=O)-O―X (where R is a hydrogen atom or a methyl group).

[0010] The (meth)acrylic acid ester containing oxygen in the ester substituent is preferably composed of carbon, oxygen, and hydrogen, and does not contain other elements such as nitrogen, phosphorus, or sulfur. Furthermore, it is preferable that the ester substituent does not have epoxy groups, silyl groups, or isocyanate groups. In addition, it is preferable that the oxygen contained in the ester substituent originates from hydroxyl groups, ether groups, ester groups, carbonyl groups, or carboxyl groups.

[0011] Examples of the polyalkylene oxide group mentioned above include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and copolymers thereof. Among these, polyethylene glycol and polypropylene glycol are preferred. Specifically, examples of polyalkylene oxides such as polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, polytetramethylene glycol (meth)acrylate, polyethylene glycol-polypropylene glycol (meth)acrylate, polyethylene glycol-polytetramethylene glycol (meth)acrylate, and polypropylene glycol-polytetramethylene glycol (meth)acrylate. Furthermore, the polyalkylene glycol (meth)acrylate may have an alkoxy group at its terminus. Examples of such alkoxy groups include methoxy, ethoxy, and butoxy groups.

[0012] While polyalkylene oxides with a single molecular weight or those with a distribution of molecular weights ranging from short to long are manufactured and sold, in the present invention, the polyalkylene oxide has a distribution in molecular weight. That is, the polyalkylene oxide groups have a distribution in chain length. Polyalkylene oxide graft chains with a distribution of ester substituents along the chain length generate combustion heat over a wide range from 200°C to 300°C. Therefore, (meth)acrylic resin (A) having segments derived from (meth)acrylic acid esters, which are polyalkylene oxide groups with a distribution of ester substituents along the chain length, exhibits excellent thermal decomposition properties. On the other hand, polyalkylene oxide graft chains with a single molecular weight have a narrower combustion temperature range, resulting in an insufficient thermal decomposition-promoting effect on (meth)acrylic resin (A).

[0013] Regarding the polyalkylene oxide group mentioned above, the solubility in the solvent changes depending on the molecular weight when measuring the molecular weight of the polyalkylene oxide chain, which may make it impossible to accurately evaluate the molecular weight using GPC (gel permeation chromatography). Therefore, in the present invention, it is preferable to evaluate the molecular weight of the polyalkylene oxide chain using a method more accurate than GPC. Specifically, the polyalkylene oxide or (meth)acrylic acid ester monomer having a polyalkylene oxide group, which is a raw material for (meth)acrylic resin (A), is ionized by adding sodium or ammonia using electrospray (ESI). The weight of the polyalkylene oxide chain can be directly evaluated by analysis using LC-MS. Alternatively, the molecular weight of the polyalkylene oxide chain can be evaluated by saponifying the (meth)acrylic resin (A) to separate and purify the polyalkylene oxide.

[0014] The above polyalkylene oxide group was evaluated by LC-MS (liquid chromatography-mass spectrometry) and its peak top molecular weight (X P ) and molecular weight dispersion width (M L ) ratio (X P / M L ) is between 0.5 and 1.5. By satisfying the above range, the thermal decomposition of (meth)acrylic resin (A) can be further promoted, and the occurrence of pinholes and blisters can be suppressed. The above X P / X LA value between 0.5 and 1.4 is more preferable. Note that the above peak top molecular weight (X P ) refers to the peak top value of molecular weight dispersion when analyzing polyalkylene oxide chains by LC-MS. Also, the above molecular weight dispersion width (M L This refers to the range (width) in which molecular weight can be detected when analyzing polyalkylene oxide chains using LC-MS. The above LC-MS can be performed, for example, using a Waters Xevo-G2-XSQTof, by preparing the sample in a 10 ppm acetonitrile solution and measuring it by Direct ESI. The above LC-MS may be performed with the polyalkylene oxide chain in the (meth)acrylic acid esterified state, or with the ether (polyalkylene oxide) state before esterification. When measured in the (meth)acrylic acid esterified state, the molecular weight of the (meth)acryloyl group can be removed to X P This can be used to determine the polyalkylene oxide. Alternatively, (meth)acrylic resin (A) may be saponified to separate and purify the polyalkylene oxide, and then the polyalkylene oxide may be analyzed. The above X P / X L This can be adjusted by selecting the type of (meth)acrylic acid ester having a polyalkylene oxide group, or the type of polyalkylene oxide used as a raw material for the (meth)acrylic acid ester.

[0015] In the (meth)acrylic acid ester in which the ester substituent is a polyalkylene oxide group distributed along the chain length, the number of repeating alkylene oxide units n is preferably 4 or more, and preferably 30 or less. By setting it within this range, the storage stability of the resulting conductive paste composition can be improved and the sinterability can be excellent. Furthermore, the number of repeating alkylene oxide units n is more preferably 10 or more, even more preferably 15 or more, even more preferably 25 or less, and even more preferably 23 or less. By setting it within this range, the dispersibility of conductive particles can be further improved, and the storage stability and blister resistance of the conductive paste composition can be further improved.

[0016] Peak top molecular weight (X) of the above polyalkylene oxide group as evaluated by LC-MS P The preferred range of X varies depending on the type of polyalkylene oxide group. For example, when the polyalkylene oxide group is a polyethylene oxide group, the X evaluated in ether form is different. P It is preferable that the number of repetitions is 208 or more (n=4) and 1354 or less (n=30). Also, when the polyalkylene oxide group is a polypropylene oxide group, X is evaluated in the ether state. P It is preferable that the number of repetitions is 250 or more (n=4) and 1760 or less (n=30). Furthermore, when the polyalkylene oxide group is a polyethylene oxide group, X is evaluated in the methacrylate esterified state. P It is preferable that the number of repetitions is 276 or more (n=4) and 1421 or less (n=30). Furthermore, when the polyalkylene oxide group is a polypropylene oxide group, X is evaluated in the methacrylate esterified state. P It is preferable that the number is 318 or more (number of repetitions n=4) and 1828 or less (number of repetitions n=30).

[0017] The molecular weight dispersion width (M) of the above polyalkylene oxide group as evaluated by LC-MS. L ) is preferably 300 or more, more preferably 400 or more, preferably 1200 or less, and more preferably 800 or less.

[0018] Peak top molecular weight (X) of the above polyalkylene oxide group P ) and the ratio (X) of the number average molecular weight (Mn) of the above (meth)acrylic resin (A) P The value of / Mn) is preferably between 0.002 and 0.12. (Meth)acrylic resins have a ceiling temperature, and in temperature environments above 200°C, they undergo a depolymerization reaction, causing the polymer to decompose into monomers. This process involves a vigorous endothermic reaction, which seemingly inhibits the depolymerization reaction. Furthermore, conductive metal particles with submicron particle sizes used in conductive paste compositions may oxidize in the temperature range above 350°C, even under an inert gas atmosphere, due to contact with surrounding oxygen-containing organic matter. Therefore, unless a highly decomposable binder that can be removed from the system at temperatures below 350°C is used, the conductive metal particles may oxidize. Oxidized conductive metal particles have a higher melting point than unoxidized ones, making them difficult to sinter and causing problems such as voids and pinholes. For example, the melting point of ordinary bulk copper is 1085°C, and the melting point of copper(II) oxide is 1326°C. The above X P / M L If the value is between 0.5 and 1.5, depolymerization is promoted by the heat of combustion of the polyalkylene oxide chain, and furthermore, X P When the / Mn value is between 0.002 and 0.06, the decomposition rate can be sufficiently increased, preventing problems such as oxidation of conductive metal particles. The above X P / Mn is preferably 0.002 or more and 0.08 or less, and more preferably 0.003 or more and 0.7 or less.

[0019] Furthermore, the number-average molecular weight (Mn) of the (meth)acrylic acid ester, in which the ester substituent is a polyalkylene oxide group distributed along the chain length, is preferably 200 or more, more preferably 250 or more, even more preferably 300 or more, preferably 2000 or less, more preferably 1950 or less, and even more preferably 1900 or less, from the viewpoint of further suppressing the occurrence of pinholes and blisters. The number-average molecular weight (Mn) is the average molecular weight on a polystyrene basis and can be obtained by performing GPC measurement using, for example, column LF-804 (manufactured by Showa Denko Corporation).

[0020] In the above (meth)acrylic resin agent (A), the content of segments derived from (meth)acrylic acid esters, in which the ester substituents are polyalkylene oxide groups distributed along the chain length, is 5% by weight or more and 40% by weight or less. Within the above range, the decomposition rate of (meth)acrylic resin (A) can be increased, and a conductive paste composition with an excellent balance of degreasing properties, blister resistance, etc., can be obtained. The content of segments derived from (meth)acrylic acid esters, in which the ester substituents are polyalkylene oxide groups distributed along the chain length, is preferably 6% by weight or more, more preferably 10% by weight or more, preferably 30% by weight or less, and more preferably 20% by weight or less. The above content can be measured, for example, by pyrolysis GC-MS.

[0021] The above (meth)acrylic resin (A) has segments derived from an alkyl (meth)acrylate ester having an alkyl branched structure in the ester substituent. (Meth)acrylic resins, primarily composed of alkyl (meth)acrylate esters having an alkyl branched structure in the ester substituent, exhibit superior decomposition under an inert gas atmosphere compared to (meth)acrylic resins, primarily composed of (meth)acrylate esters with a linear ester substituent.

[0022] As the alkyl (meth)acrylate ester having an alkyl branched structure in the ester substituent, it is preferable that the ester substituent has 3 or more carbon atoms, more preferably 4 or more, preferably 20 or less, more preferably 15 or less, even more preferably 12 or less, and even more preferably 10 or less.

[0023] Examples of alkyl (meth)acrylate esters having an alkyl branched structure in the ester substituent 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, and isodecyl (meth)acrylate. 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. The (meth)acrylic resin (A) preferably has at least one segment selected from the group consisting of a segment derived from isobutyl methacrylate and a segment derived from 2-ethylhexyl methacrylate, as a segment derived from an alkyl ester (meth)acrylate having an alkyl branched structure in the ester substituent. Having such a configuration can increase the decomposition rate of the (meth)acrylic resin (A).

[0024] The content of segments derived from alkyl esters of (meth)acrylate having an alkyl branched structure in the ester substituent in the above (meth)acrylic resin (A) is 50% by weight or more. Within the above range, a conductive paste composition with excellent low-temperature decomposition properties can be obtained. The content of segments derived from alkyl (meth)acrylate esters having an alkyl branched structure in the ester substituent is preferably 55% by weight or more, more preferably 60% by weight or more, preferably 95% by weight or less, more preferably 90% by weight or less, and even more preferably 85% by weight or less. The above content can be measured, for example, by pyrolysis GC-MS.

[0025] The above (meth)acrylic resin (A) may further contain other segments, such as segments derived from (meth)acrylic acid esters with linear ester substituents, and segments derived from (meth)acrylic acid esters with cyclic ester substituents. Furthermore, from the viewpoint of degradability, it is preferable that it does not contain segments derived from (meth)acrylic acid esters with cyclic ester substituents. Examples of (meth)acrylic acid esters in which the ester substituent is linear include alkyl (meth)acrylic acid esters having a linear alkyl group. The number of carbon atoms in the ester substituent is preferably 1 or more, more preferably 2 or more, preferably 10 or less, and more preferably 6 or less.

[0026] Examples of alkyl (meth)acrylate esters having the linear alkyl group mentioned above include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, and n-hexyl (meth)acrylate. Among these, methyl (meth)acrylate, ethyl (meth)acrylate, and n-butyl (meth)acrylate are preferred, and ethyl methacrylate and n-butyl methacrylate are more preferred.

[0027] Examples of (meth)acrylic acid esters having a cyclic structure in the above-mentioned ester substituent 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.

[0028] The content of segments in the above (meth)acrylic resin (A) that are derived from a linear (meth)acrylic acid ester is, for example, 0% by weight or more, preferably 1% by weight or more, more preferably 5% by weight or more, even more preferably 7% by weight or more, for example 15% by weight or more, preferably 45% by weight or less, more preferably 30% by weight or less, even more preferably 20% by weight or less, and even more preferably 10% by weight or less. By setting the range as described above, handling characteristics such as printability will be improved. The above content can be measured, for example, by pyrolysis GC-MS.

[0029] In the above (meth)acrylic resin (A), the ratio (branched / linear) of the content of segments derived from alkyl (meth)acrylic acid esters having an alkyl branched structure in the ester substituent to the content of segments derived from linear (meth)acrylic acid esters having a linear ester substituent is preferably 1 or more, more preferably 1.1 or more, for example 1.5 or more, preferably 5 or less, preferably 4 or less, for example 3 or less, from the viewpoint of further improving handling properties such as printability and degradability.

[0030] The above (meth)acrylic resin (A) preferably has multiple hydroxyl groups or carboxylic acid polar functional groups (carboxyl groups) at the ends of its molecular chains, and more preferably has multiple hydroxyl groups or carboxylic acid polar functional groups at one end of its molecular chains. Having the above structure improves the dispersibility of the inorganic particles (B). Furthermore, it allows for a more suitable viscosity of the conductive paste composition. These groups can be used, for example, when producing (meth)acrylic resin (A), by using mercapto derivatives such as mercaptosuccinic acid and mercaptopropanediol as chain transfer agents to introduce multiple polar groups to one end of the molecular chain. When analyzing the structure of the above branched ends, the above (meth)acrylic resin (A) is dissolved in deuterated chloroform, 1 Using 1H-NMR (JEOL Ltd. "ECX-400"), under the conditions of 400MHz, measurement temperature 80°C, and 1024 integration cycles: 1 The structure can be identified by obtaining an H-NMR spectrum.

[0031] The weight-average molecular weight (Mw) of the above (meth)acrylic resin (A) is preferably 20,000 or more, and 600,000 or less. If the above Mw is 20,000 or more, the viscosity of the conductive paste composition will not become too low, and the dispersibility of inorganic particles will be good. If the above Mw is 600,000 or less, the viscosity of the conductive paste composition will be sufficiently high, improving storage stability and enabling excellent printability. The above Mw is preferably 50,000 or more, more preferably 100,000 or more, preferably 550,000 or less, and more preferably 400,000 or less.

[0032] The ratio (Mw / Mn) of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) of the above (meth)acrylic resin (A) is usually 1 or more, preferably 1.5 or more, more preferably 2 or more, preferably 5 or less, and most preferably 3 or less. By keeping the composition within the above range, a suitable amount of low-polymerization components are included, resulting in a viscosity within a suitable range for the conductive paste composition and improving productivity. Note that the weight-average molecular weight (Mw) and number-average molecular weight (Mn) are average molecular weights calculated on a polystyrene basis, and can be obtained by performing GPC measurements using, for example, column LF-804 (manufactured by Showa Denko Corporation).

[0033] The above (meth)acrylic resin (A) was found to have a decomposition completion temperature T when measured by TG-DTA under a heating rate of 100°C / min. 100 And the decomposition completion temperature T at a heating rate of 10°C / min 10 The difference (T 100- T 10 It is preferable that the temperature is 50°C or lower. With typical binder resins, increasing the heating rate shifts the decomposition termination temperature to a higher temperature than when the heating rate is low. Typically, the decomposition termination temperature of (meth)acrylic resin is T 100 and T 10 The difference (T 100- T 10 ) is about 80°C to 100°C, but the T of the above (meth)acrylic resin (A) 100- T 10 By adjusting the composition to keep the temperature below 50°C, surface oxidation of conductive metal particles during firing can be prevented, thus preventing structural problems in electronic devices such as pinholes and voids. The above T 100- T 10 The distribution width (X) of the polyalkylene glycol graft chain is P / M L ), as well as the length of the polyalkylene glycol graft chain relative to the acrylic main chain length (XP It can be adjusted by ( / Mn). The above T 100 The temperature is preferably 350°C or higher, and preferably 390°C or lower. The above T 10 The temperature is preferably 330°C or higher, and preferably 380°C or lower. Furthermore, the above-mentioned decomposition completion temperature refers to the temperature at which the resin weight becomes less than 0.1% in the TG-DTA apparatus.

[0034] The glass transition temperature (Tg) of the above (meth)acrylic resin (A) is preferably 20°C or higher, more preferably 30°C or higher, preferably 80°C or lower, and more preferably 60°C or lower. The above Tg can be measured, for example, using a differential scanning calorimetry (DSC) or the like.

[0035] The content of the (meth)acrylic resin (A) in the conductive paste composition described above is not particularly limited, but is preferably 3% by weight or more, more preferably 3.5% by weight or more, even more preferably 4% by weight or more, preferably 30% by weight or less, more preferably 20% by weight or less, and even more preferably 12% by weight or less. By keeping the content of the above-mentioned (meth)acrylic resin (A) within the above range, a conductive paste composition can be obtained even when fired at a low temperature.

[0036] The method for producing the above-mentioned (meth)acrylic resin (A) is not particularly limited. For example, one method involves first preparing a monomer mixture by adding an organic solvent to a raw material monomer mixture containing an alkyl (meth)acrylic acid ester having an alkyl branched structure in the ester substituent, or a (meth)acrylic acid ester containing a polyalkylene oxide group with ester substituents distributed along the chain length, and then further producing the (meth)acrylic resin (A) by adding a polymerization initiator to the obtained monomer mixture and polymerizing it. Alternatively, a chain transfer agent may be added to the monomer mixture. Furthermore, as a (meth)acrylic acid ester containing polyalkylene oxide groups in which the ester substituents are distributed along the chain length, the peak top molecular weight (X) of the polyalkylene oxide group is evaluated by LC-MS.P ) and molecular weight dispersion width (X L ) ratio (X P / X L It is preferable to use a material whose peak top molecular weight (X) is between 0.5 and 1.5. Also, the peak top molecular weight (X) when evaluated by LC-MS should be used. P ) and molecular weight dispersion width (M L ) ratio (X P / M L (Meth)acrylic acid esters may be prepared using polyalkylene oxides having a ratio of 0.5 to 1.5, and the obtained (meth)acrylic acid esters may be used as monomers. The polymerization method is not particularly limited and includes emulsion polymerization, suspension polymerization, bulk polymerization, interfacial polymerization, and solution polymerization. Among these, solution polymerization is preferred.

[0037] Examples of polymerization initiators include organic peroxides such as dilauryl peroxide, p-menthane hydroperoxide, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, t-butyl hydroperoxide, cyclohexanone peroxide, disuccinate peroxide, and bis-3,5,5-trimethylhexanoyl peroxide. Examples of these commercially available products include Permenta H, Permil P, Perocta H, Permil H-80, Perloyle 355, Perbutyl H-69, Perhexa H, Perloyle SA, Perloyle L (all manufactured by NOF Corporation), Trigonox 27, and Trigonox 421 (all manufactured by Nouryon). In particular, it is preferable to use an initiator with low hydrogen abstraction properties, such as dilauryl peroxide, to prevent gelation during polymerization of (meth)acrylic resin (A). 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. By using these initiators, branching of the polymer can be prevented, and the molecular weight distribution (Mw / Mn) can be narrowed.

[0038] Furthermore, by using mercapto derivatives such as mercaptosuccinic acid and mercaptopropanediol as chain transfer agents during polymerization, hydroxyl groups and carboxyl groups can be introduced to the molecular ends.

[0039] <Inorganic particles (B)> The above conductive paste composition contains inorganic particles (B). The inorganic particles (B) described above include conductive particles with an average particle diameter of 0.01 μm or more and 10 μm or less. Examples of metals used as materials for the conductive particles include copper, iron, nickel, palladium, platinum, gold, silver, aluminum, tungsten, lithium, magnesium, niobium, lanthanum, dysprosium, terbium, and alloys thereof. Among these, it is preferable that the material contains copper or silver, and more preferably copper or silver. The electrical conductivity of the above conductive particles is preferably 0.8 MS / m or higher, and preferably 62 MS / m or lower. The electrical conductivity can be measured, for example, at 25°C using an electrical conductivity measuring device with a two-electrode AC system. Among the conductive particles mentioned above, conductive particles containing copper or silver are particularly preferred because they have low resistance and are less prone to electromigration problems, conductive particles containing copper are more preferred, and copper particles are the most preferred. The method for producing copper particles as described above is not particularly limited, and liquid-phase reduction, gas-phase (electrolytic reduction), micelle method, etc., can be used. Conductive particles may be surface-treated from the viewpoint of dispersibility, and examples of surface treatments include surface oxidation treatment.

[0040] The average particle size of the conductive particles described above is between 0.01 μm and 10 μm. Within the above range, excellent low-temperature sintering properties can be achieved. The average particle diameter is preferably 0.05 μm or larger, more preferably 0.1 μm or larger, preferably 5 μm or smaller, and more preferably 2 μm or smaller. The above 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."

[0041] The content of the conductive particles in the conductive paste composition is not particularly limited, but is preferably 50% by weight or more, preferably 65% ​​by weight or more, preferably 85% by weight or less, and more preferably 80% by weight or less. By setting the range as described above, a conductive paste composition with excellent printability can be obtained.

[0042] The inorganic particles (B) described above may contain other inorganic particles other than the conductive particles described above. Other inorganic particles mentioned above include, for example, glass powder. By including glass powder, conductive metal particles can be aggregated and a dense layer formed when the conductive paste composition is sintered. The above-mentioned glass powder is not particularly limited and includes, for example, glass powders such as bismuth oxide glass, silicate glass, lead glass, zinc glass, and boron glass, as well as glass powders of various silicon oxides such as CaO-Al2O3-SiO2 system, MgO-Al2O3-SiO2 system, and LiO2-Al2O3-SiO2 system. Furthermore, the above glass powders include Bi2O3-B2O3 mixture, SnO-B2O3-P2O5-Al2O3 mixture, PbO-B2O3-SiO2 mixture, BaO-ZnO-B2O3-SiO2 mixture, ZnO-Bi2O3-B2O3-SiO2 mixture, Bi2O3-B2O3-BaO-CuO mixture, Bi2O3-ZnO-B2O3-Al2O3-SrO mixture, ZnO-Bi2O3-B2O3 mixture, Bi2O3-SiO2 mixture, P2O5-Na2O-CaO-BaO-Al2O3-B2O3 mixture, P2O5-SnO mixture, and P2O5-SnO-B2O3 mixture. Glass powders such as P2O5-SnO-SiO2 mixture, CuO-P2O5-RO mixture, SiO2-B2O3-ZnO-Na2O-Li2O-NaF-V2O5 mixture, P2O5-ZnO-SnO-R2O-RO mixture, B2O3-SiO2-ZnO mixture, B2O3-SiO2-Al2O3-ZrO2 mixture, SiO2-B2O3-ZnO-R2O-RO mixture, SiO2-B2O3-Al2O3-RO-R2O mixture, SrO-ZnO-P2O5 mixture, SrO-ZnO-P2O5 mixture, and BaO-ZnO-B2O3-SiO2 mixture can also be used. Note that R is an element selected from the group consisting of Zn, Ba, Ca, Mg, Sr, Sn, Ni, Fe, and Mn. In particular, glass powders of Bi2O3-B2O3 mixtures, PbO-B2O3-SiO2 mixtures, and lead-free glass powders such as BaO-ZnO-B2O3-SiO2 mixtures or ZnO-Bi2O3-B2O3-SiO2 mixtures that do not contain lead are preferred.

[0043] The content of inorganic particles other than the conductive particles in the above conductive paste composition is not particularly limited, but is preferably 0.1% by weight or more, more preferably 1% by weight or more, preferably 5% by weight or less, and more preferably 3% by weight or less. Other inorganic particles besides the conductive particles described above have an average particle diameter of preferably 0.1 μm or more, more preferably 0.2 μm or more, even more preferably 0.3 μm or more, for example 0.5 μm or more, preferably 5 μm or less, more preferably 4 μm or less, for example 3 μm or less. Other inorganic particles besides the conductive particles described above have a glass transition temperature of preferably 300°C or higher, more preferably 320°C or higher, even more preferably 340°C or higher, for example 350°C or higher, preferably 600°C or lower, more preferably 550°C or lower, even more preferably 500°C or lower, for example 450°C or lower.

[0044] <Solvent (C)> The above conductive paste composition contains solvent (C). The solvent (C) described above is an organic solvent with a boiling point between 200°C and 250°C. By using the above solvent (C), evaporation does not occur too quickly, and the (meth)acrylic resin (A) can be removed under drying conditions below its decomposition initiation temperature, thereby improving the productivity of electronic devices.

[0045] The solvent is not particularly limited, but it is preferable that it has excellent coating properties, drying properties, and dispersibility of conductive inorganic particles when used to manufacture electronic devices. 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. Furthermore, 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 individually or in combination of two or more. The values ​​in parentheses indicate the boiling point.

[0046] The boiling point of the above organic solvent is 200°C or higher, preferably 205°C or higher, 250°C or lower, and preferably 230°C or lower.

[0047] The content of the solvent (C) in the conductive paste composition is not particularly limited, but is preferably 5% by weight or more, more preferably 10% by weight or more, preferably 30% by weight or less, and more preferably 25% by weight or less. By keeping the above range, coating properties and the dispersibility of conductive metal particles can be improved.

[0048] <Other> The above conductive paste composition may further contain additives such as sintering aids.

[0049] The viscosity of the above conductive paste composition is not particularly limited, but when measured at 20°C using a B-type viscometer with a probe rotation speed of 5 rpm, the preferred lower limit of viscosity is 0.1 Pa·s and the preferred upper limit is 100 Pa·s. By setting the viscosity to 0.1 Pa·s or higher, the conductive metal particle dispersion sheet obtained after coating by die-coating printing or the like can maintain a predetermined shape. Furthermore, by setting the viscosity to 100 Pa·s or lower, sagging when filling through vias with the conductive paste composition can be prevented, thereby improving printability.

[0050] The method for preparing the above conductive paste composition is not particularly limited, and conventionally known stirring methods can be used. Specifically, for example, a method of stirring the (meth)acrylic resin (A), the inorganic particles (B), the solvent (C), and other components added as needed using a three-roll mixer or the like. Another method is to add the inorganic particles (B), additional solvents (C), and other components added as needed to the resin solution obtained after the reaction when preparing the (meth)acrylic resin (A), and then stir using a three-roll mixer or the like.

[0051] By printing the above conductive paste composition onto a substrate, removing the solvent (C) by drying, then heating in a firing furnace under an inert gas atmosphere such as nitrogen to degrease the resin components such as (meth)acrylic resin (A), and sintering the inorganic particles (B), an electronic device exhibiting high conductivity can be manufactured. An electronic device using the conductive paste composition of the present invention is also one of the present inventions. Examples of the above-mentioned electronic devices 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, encapsulants for MEMS devices, electrode materials for solar cells, multilayer ceramic capacitors, LTCC, silicon capacitors, and all-solid-state batteries. In addition to the above-mentioned electrode circuit applications, it can also be used for antibacterial components, electromagnetic shielding, catalysts, fluorescent materials, and the like. The printing method described above is not particularly limited, and for example, screen printing, die-coating, offset printing, gravure printing, dipping, spray coating, inkjet printing, etc., can be used.

[0052] For example, a multilayer ceramic capacitor can be obtained by applying the above conductive paste composition onto a ceramic green sheet using a printing process, stacking multiple sheets and heating and pressing them together to create a laminate, then degreasing it, firing it to form a ceramic sintered body, and finally forming external electrodes on the end faces of the ceramic sintered body.

[0053] The drying method is not particularly limited; for example, a forced-air oven can be used. Furthermore, the drying temperature is not particularly limited; for example, it can be between 100°C and 150°C.

[0054] The temperature for the degreasing process is not particularly limited, but it is preferable to perform it at a temperature of 350°C or lower. Similarly, the firing conditions are not particularly limited, but it is preferable to perform them at a temperature of 600°C or lower. Furthermore, a heating rate of 20°C / minute or higher is preferable. Furthermore, firing under a nitrogen atmosphere is preferable, and if surface oxidation of the conductive metal particles is severe, hydrogen may be added to the nitrogen gas introduced into the firing furnace. The above firing process is preferably carried out in an electric furnace, muffle furnace, plasma furnace, or the like under an inert gas atmosphere such as nitrogen.

[0055] In addition, flat electronic devices can also be fired by hot pressing. The conditions for hot pressing are not particularly limited, but it is preferable to bake at a temperature of 200°C to 350°C with a press pressure of 1 MPa to 5 MPa.

[0056] Furthermore, the metal electrodes and other components may be surface-protected after firing to prevent oxidation. Examples of surface protection methods include coating with a liquid epoxy resin composition or casting a solution containing EVA, styrene, or the like. [Effects of the Invention]

[0057] According to the present invention, it is possible to provide a conductive paste composition that exhibits good dispersibility of inorganic particles, sufficient storage stability, suppression of void and pinhole generation during firing, good dispersibility of organic components, excellent electrode adhesion, and excellent blister resistance. Furthermore, it is possible to provide an electronic device using this conductive paste composition. [Modes for carrying out the invention]

[0058] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0059] (Synthesis Example 1) <Preparation of polyalkylene glycol monomer 1> A 2 L separable flask equipped with a stirrer, Liebig condenser, vacuum recovery device, thermometer, oil bath, and nitrogen gas inlet was prepared. 154 parts by weight of methacrylic anhydride and 700 parts by weight of methoxypolyethylene glycol were mixed in the 2 L separable flask. The mixture was heated to a temperature of 90°C under reduced pressure of -0.6 MPa while stirring for 3 hours. After 3 hours, the mixture temperature was raised to 120°C to remove unreacted methacrylic anhydride and water, thereby obtaining polyalkylene glycol monomer 1 (methoxypolyethylene glycol methacrylate). For methoxypolyethylene glycol, we used Dow's "Carbowax MPEG350" (catalog value of molecular weight: 350 (number of repeating ethylene glycol units (EO units) n: 7.22) and peak top molecular weight (X) as evaluated by LC-MS). P ):208, molecular weight dispersion width (M L (400) was used. LC-MS (liquid chromatography-mass spectrometry) was performed under the following conditions. Measurement device: Waters (Xevo-G2-XS QTof) Solution flow rate: 5μL / min Ionization method: ESI positive mode Measurement temperature: 120℃ Sample preparation concentration: 10 ppm, acetonitrile solution Measurement method: DirectESI

[0060] (Synthesis Example 2) <Preparation of Polyalkylene Glycol Monomer 2> Polyethylene glycol (PEG-1500 manufactured by Sanyo Chemical Industries, Ltd. (catalog value of molecular weight: 1500 (number of repeating EO units n: 33.64))) was used instead of methoxypolyethylene glycol, and the peak top molecular weight (X) was evaluated by LC-MS. P ):1119, molecular weight dispersion width (M L Polyalkylene glycol monomer 2 was obtained in the same manner as in Synthesis Example 1, except that 800)3000 parts by weight were used.

[0061] (Synthesis Example 3) <Preparation of polyalkylene glycol monomer 3> Polypropylene glycol (Sanyo Chemical Industries, Ltd.'s "Sannix PP-1000" (catalog value of molecular weight: 1000 (number of repeating propylene glycol units (PO units) n: 16.90)) was used instead of methoxypolyethylene glycol), and the peak top molecular weight (X) was evaluated by LC-MS. P ) is 425, molecular weight dispersion width (M L Polyalkylene glycol monomer 3 was obtained in the same manner as in Synthesis Example 1, except that 500)2090 parts by weight of ) were used.

[0062] (Synthesis Example 4) <Preparation of polyalkylene glycol monomer 4> Polypropylene glycol (PPG-1500, manufactured by FENGCHENGROUP, with catalog value of molecular weight: 1500 (number of repeating PO units n: 25.51)) was used instead of methoxypolyethylene glycol, and the peak top molecular weight (X) was evaluated by LC-MS. P ):714, molecular weight dispersion width (M L Polyalkylene glycol monomer 4 was obtained in the same manner as in Synthesis Example 1, except that 700)3000 parts by weight were used.

[0063] (Synthesis Example 5) <Preparation of polyalkylene glycol monomer 5> Methoxyethylene glycol was replaced with methoxyethylene glycol (Sigma-Aldrich's "Methoxyethylene Glycol 350" (catalog value of molecular weight: 350 (number of repeating EO units n: 7))), and the peak top molecular weight (X) was evaluated by LC-MS. P ):366, molecular weight dispersion width (M L Polyalkylene glycol monomer 5 was obtained in the same manner as in Synthesis Example 1, except that 100)732 parts by weight were used.

[0064] (Synthesis Example 6) <Preparation of polyalkylene glycol monomer 6> Polypropylene glycol (Sanyo Chemical Industries, Ltd. "Sannix PP-1200" (catalog value of molecular weight: 1200 (number of repeating PO units n: 7)) was used instead of methoxypolyethylene glycol), and the peak top molecular weight (X) was evaluated by LC-MS. P ):492, molecular weight dispersion width (M L Polyalkylene glycol monomer 6 was obtained in the same manner as in Synthesis Example 1, except that 2500 parts by weight of 500 were used.

[0065] (Synthesis Example 7) Methoxyethylene glycol was replaced with methoxyethylene glycol (Dow's "Carbowax MPEG350" (catalog value of molecular weight: 350 (number of repeating ethylene glycol units (EO units) n: 7.22)), and the peak top molecular weight (X) was evaluated by LC-MS. P ):208, molecular weight dispersion width (M L ): 400) 350 parts by weight and polyethylene glycol (Sanyo Chemical Industries, Ltd. "PEG-1500" (catalog value of molecular weight: 1500 (number of repeating EO units n: 33.64)) in place of methoxypolyethylene glycol), peak top molecular weight (X P ):1119, molecular weight dispersion width (M L Polyalkylene glycol monomer 7 was obtained in the same manner as in Synthesis Example 1, except that 800)1500 parts by weight were mixed and used.

[0066] (Example 1) <(Meth)acrylic resin (A) preparation> Isobutyl methacrylate (iBMA) and 2-ethylhexyl methacrylate (2EHMA) were used as alkyl esters of (meth)acrylate having an alkyl branched structure as the ester substituent. Ethyl methacrylate (EMA) and n-butyl methacrylate (nBMA) were used as alkyl esters of (meth)acrylate having a linear alkyl group as the ester substituent.

[0067] A 2L separable flask equipped with a stirrer, condenser, thermometer, water bath, and nitrogen gas inlet was prepared. 100 parts by weight of monomer in the proportions shown in Table 1 were added to the 2L separable flask. Furthermore, 100 parts by weight of butyl carbitol as a solvent and 0.9 parts by weight of mercaptosuccinic acid as a chain transfer agent were mixed to obtain a monomer mixture.

[0068] The resulting monomer mixture was bubbling with nitrogen gas for 20 minutes to remove dissolved oxygen, then replaced with nitrogen gas. The internal temperature was raised to 80°C while stirring, and the 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 was added, the mixture was cooled to room temperature to complete the polymerization, yielding a composition containing (meth)acrylic resin (A). The obtained composition containing (meth)acrylic resin (A) was dried to remove the solvent and the (meth)acrylic resin (A) was recovered. The (meth)acrylic resin (A) was dissolved in tetrahydrofuran (THF) at a resin concentration of 0.1% by weight, and the weight-average molecular weight (Mw) and number-average molecular weight (Mn) in polystyrene equivalent were measured by GPC using a SHODEX LF-804 column. The results were Mw = 20,000 and Mn = 12,000. Furthermore, the above (meth)acrylic resin (A) was dissolved in deuterated chloroform, 1 Using 1H-NMR (JEOL Ltd. "ECX-400"), under the conditions of 400MHz, measurement temperature 80°C, and 1024 integration cycles: 1By obtaining 1H-NMR spectra and identifying the structure, it was confirmed that the molecule has multiple polar carboxylic acid functional groups at its ends.

[0069] <Preparation of conductive paste composition> The composition containing the above-mentioned (meth)acrylic resin (A) was subjected to solid content measurement using a forced-air oven to confirm the resin concentration. Conductive metal particles, low-melting-point glass, and additional solvents were added to the above-mentioned (meth)acrylic resin (A) in the types and formulations shown in Table 2, and the mixture was stirred with a high-speed stirring device to obtain a conductive paste composition. The following materials were used as conductive metal particles and low-melting-point glass. Conductive metal particles: Manufactured by AS ONE Corporation, silver powder, average particle size 0.5 μm, electrical conductivity 62 MS / m Low-melting-point glass: AGC Corporation, boric acid glass frit, ASF-1096, Tg: 405℃, average particle size 1μm The average particle size was measured using the BET method with an Anton Paar Autosorb 6100. Electrical conductivity was measured using an electrical conductivity measuring device (Fischer Sigmascope SMP350) at 25°C using a two-electrode AC method.

[0070] (Example 2) <(Meth)acrylic resin (A) preparation> (Meth)acrylic resin (A) was obtained in the same manner as in Example 1, except that the monomer composition was changed as shown in Table 1 and 110 parts by weight of butyl carbitol was used as the solvent. When measured in the same manner as in Example 1, Mw was 20,000 and Mn was 10,000.

[0071] <Preparation of conductive paste composition> A conductive paste composition was obtained in the same manner as in Example 1, except that silver powder (manufactured by AS ONE Corporation, average particle size 0.3 μm, electrical conductivity 62 MS / m) was used as the conductive metal particles and the formulation was as shown in Table 2.

[0072] (Example 3) <(Meth)acrylic resin (A) preparation> (Meth)acrylic resin (A) was obtained in the same manner as in Example 1, except that the monomer composition was changed as shown in Table 1, 10 parts by weight of dihydroterpineol was used as the solvent, and no chain transfer agent was added. When measured in the same manner as in Example 1, Mw was 600,000 and Mn was 300,000.

[0073] <Preparation of conductive paste composition> A conductive paste composition was obtained in the same manner as in Example 1, except that silver powder (manufactured by AS ONE Corporation, average particle size 0.1 μm, electrical conductivity 62 MS / m) was used as the conductive metal particles, and the formulation was as shown in Table 2.

[0074] (Example 4) <(Meth)acrylic resin (A) preparation> (Meth)acrylic resin (A) was obtained in the same manner as in Example 2, except that the monomer composition was changed as shown in Table 1 and 110 parts by weight of butyl carbitol was used as the solvent. When measured in the same manner as in Example 1, Mw was 20,000 and Mn was 10,000.

[0075] <Preparation of conductive paste composition> A conductive paste composition was obtained in the same manner as in Example 1, except that silver powder (manufactured by AS ONE Corporation, average particle size 1 μm, electrical conductivity 62 MS / m) was used as the conductive metal particles, and the formulation was as shown in Table 2.

[0076] (Example 5) <(Meth)acrylic resin (A) preparation> (Meth)acrylic resin (A) was obtained in the same manner as in Example 2, except that the monomer composition was changed as shown in Table 1 and 10 parts by weight of dihydroterpineol was used as the solvent. When measured in the same manner as in Example 1, Mw was 600,000 and Mn was 200,000.

[0077] <Preparation of conductive paste composition> A conductive paste composition was obtained in the same manner as in Example 1, except that copper powder (manufactured by DOWA Electronics, average particle size 1 μm, electrical conductivity 59 MS / m) was used as the conductive metal particles, and the formulation was as shown in Table 2.

[0078] (Example 6) <(Meth)acrylic resin (A) preparation> (Meth)acrylic resin (A) was obtained in the same manner as in Example 1, except that the monomer composition was changed as shown in Table 1 and 100 parts by weight of terpineol was used as the solvent. When measured in the same manner as in Example 1, Mw was 20,000 and Mn was 10,000.

[0079] <Preparation of conductive paste composition> A conductive paste composition was obtained in the same manner as in Example 1, except that copper powder (manufactured by DOWA Electronics, average particle size 0.5 μm, electrical conductivity 59 MS / m) was used as the conductive metal particles, and the formulation was as shown in Table 2.

[0080] (Example 7) (Meth)acrylic resin (A) was obtained in the same manner as in Example 1, except that the monomer composition was changed as shown in Table 1 and 100 parts by weight of terpineol was used as the solvent. When measured in the same manner as in Example 1, Mw was 200,000 and Mn was 80,000.

[0081] <Preparation of conductive paste composition> A conductive paste composition was obtained in the same manner as in Example 1, except that DyCu alloy powder (average particle size 10 μm, electrical conductivity 2.2 MS / m) was used as the conductive metal particles and the formulation was as shown in Table 2.

[0082] (Example 8) A conductive paste composition was obtained in the same manner as in Example 7, except that TbCu alloy powder (average particle size 5 μm, electrical conductivity 1.6 MS / m) was used as the conductive metal particles, and the formulation was as shown in Table 2.

[0083] (Example 9) A conductive paste composition was obtained in the same manner as in Example 7, except that copper powder (average particle size 0.01 μm, electrical conductivity 59 MS / m) was used as the conductive metal particles, and the formulation was as shown in Table 2.

[0084] (Comparative Example 1) <(Meth)acrylic resin (A) preparation> (Meth)acrylic resin (A) was obtained in the same manner as in Example 1, except that the monomer composition was changed as shown in Table 1 and 100 parts by weight of terpineol was used as the solvent. When measured in the same manner as in Example 1, Mw was 20,000 and Mn was 10,000.

[0085] <Preparation of conductive paste composition> A conductive paste composition was obtained in the same manner as in Example 1, except that silver powder (manufactured by AS ONE Corporation, average particle size 0.5 μm, electrical conductivity 62 MS / m) was used as the conductive metal particles, and the formulation was as shown in Table 2.

[0086] (Comparative Example 2) <(Meth)acrylic resin (A) preparation> (Meth)acrylic resin (A) was obtained in the same manner as in Example 2, except that the monomer composition was changed as shown in Table 1 and 10 parts by weight of butyl carbitol was used as the solvent. When measured in the same manner as in Example 1, Mw was 600,000 and Mn was 200,000.

[0087] <Preparation of conductive paste composition> A conductive paste composition was obtained in the same manner as in Example 1, except that silver powder (manufactured by AS ONE Corporation, average particle size 0.3 μm, electrical conductivity 62 MS / m) was used as the conductive metal particles, and the formulation was as shown in Table 2.

[0088] (Comparative Example 3) <(Meth)acrylic resin (A) preparation> (Meth)acrylic resin (A) was obtained in the same manner as in Example 3, except that the monomer composition was changed as shown in Table 1 and 10 parts by weight of butyl carbitol was used as the solvent. When measured in the same manner as in Example 1, Mw was 600,000 and Mn was 300,000.

[0089] <Preparation of conductive paste composition> A conductive paste composition was obtained in the same manner as in Example 1, except that silver powder (manufactured by AS ONE Corporation, average particle size 1 μm, electrical conductivity 62 MS / m) was used as the conductive metal particles, and the formulation was as shown in Table 2.

[0090] (Comparative Example 4) <(Meth)acrylic resin (A) preparation> (Meth)acrylic resin (A) was obtained in the same manner as in Example 1, except that the monomer composition was changed as shown in Table 1, and 100 parts by weight of dihydroterpineol was used as the solvent and 1.8 parts by weight of 3-mercapto-1,2-propanediol was used as the chain transfer agent. When measured in the same manner as in Example 1, Mw was 10,000 and Mn was 5,000.

[0091] <Preparation of conductive paste composition> A conductive paste composition was obtained in the same manner as in Example 1, except that silver powder (manufactured by AS ONE Corporation, average particle size 0.1 μm, electrical conductivity 62 MS / m) was used as the conductive metal particles, and the formulation was as shown in Table 2.

[0092] (Comparative Example 5) <(Meth)acrylic resin (A) preparation> (Meth)acrylic resin (A) was obtained in the same manner as in Example 2, except that the monomer composition was changed as shown in Table 1 and 10 parts by weight of dihydroterpineol was used as the solvent. When measured in the same manner as in Example 1, Mw was 600,000 and Mn was 300,000.

[0093] <Preparation of conductive paste composition> A conductive paste composition was obtained in the same manner as in Example 1, except that copper powder (manufactured by DOWA Electronics, average particle size 1 μm, electrical conductivity 59 MS / m) was used as the conductive metal particles, and the formulation was as shown in Table 2.

[0094] (Comparative Example 6) <(Meth)acrylic resin (A) preparation> (Meth)acrylic resin (A) was obtained in the same manner as in Example 2, except that the monomer composition was changed as shown in Table 1 and 8 parts by weight of dihydroterpineol was used as the solvent. When measured in the same manner as in Example 1, Mw was 700,000 and Mn was 350,000.

[0095] <Preparation of conductive paste composition> A conductive paste composition was obtained in the same manner as in Example 1, except that copper powder (manufactured by DOWA Electronics, average particle size 0.5 μm, electrical conductivity 59 MS / m) was used as the conductive metal particles, and the formulation was as shown in Table 2.

[0096] (Comparative Example 7) <(Meth)acrylic resin (A) preparation> (Meth)acrylic resin (A) was obtained in the same manner as in Example 1, except that the monomer composition was changed as shown in Table 1 and 100 parts by weight of texanol (boiling point 255°C) was used as the solvent. When measured in the same manner as in Example 1, Mw was 20,000 and Mn was 10,000.

[0097] <Preparation of conductive paste composition> A conductive paste composition was obtained in the same manner as in Example 1, except that copper powder (manufactured by TOKURIKI Co., Ltd., average particle size 15 μm, electrical conductivity 59 MS / m) was used as the conductive metal particles, and the formulation was as shown in Table 2.

[0098] (Comparative Example 8) <(Meth)acrylic resin (A) preparation> (Meth)acrylic resin (A) was obtained in the same manner as in Example 1, except that the monomer composition was changed as shown in Table 1 and 100 parts by weight of propylene glycol monomethyl ether acetate (PEGMEEA, boiling point 146°C) was used as the solvent. When measured in the same manner as in Example 1, Mw was 20,000 and Mn was 10,000.

[0099] <Preparation of conductive paste composition> A conductive paste composition was obtained in the same manner as in Example 1, except that copper powder (manufactured by Sigma-Aldrich, average particle size 0.005 μm, electrical conductivity 59 MS / m) was used as the conductive metal particles, and the formulation was as shown in Table 2. [Table 1]

[0100] [Table 2]

[0101] <Rating> The (meth)acrylic resin (A) and conductive paste compositions obtained in the examples and comparative examples were evaluated as follows. The results are shown in Table 3.

[0102] (1) Resin decomposition rate For the (meth)acrylic resin (A) obtained in the examples and comparative examples, thermal decomposition measurements were performed using a TG-DTA apparatus under a nitrogen atmosphere at heating rates of 10°C / min and 100°C / min. The decomposition completion temperature T at a heating rate of 100°C / min was used as an indicator of the resin decomposition rate. 100 And the decomposition completion temperature T at a heating rate of 10°C / min 10 The difference T 100- T 10 The following criteria were used to evaluate it. A:T 100- T 10 Below 50℃ B:T 100- T 10 over 50°C and under 60°C C:T 100- T 10 above 60℃

[0103] (2) Paste storage stability The conductive paste compositions obtained in the examples and comparative examples were cured at room temperature for 10 days, and the dispersion state of the paste compositions was checked and evaluated according to the following criteria. Furthermore, conductive paste compositions that exhibit excellent paste storage stability can be said to have excellent printability. A: No change in dispersion state B: There is a clear supernatant layer, and no metal sediment layer at the bottom of the container. C: A layer of metal sediment is present at the bottom of the container.

[0104] (3) Blister resistance The conductive paste compositions obtained in the examples and comparative examples were coated onto a glass substrate using an applicator to a thickness of 20 μm after drying, and dried in a 150°C forced-air oven for 1 hour to obtain a conductive sheet. The conductive sheet formed on the glass substrate was held at 300 °C for 1 hour in a nitrogen atmosphere using an electric furnace, then the internal temperature was raised to 600 °C, and the state of the sheet was visually observed and evaluated according to the following criteria. A: No blisters are generated and there is no glass float B: Although no blisters are generated, there is glass float C: Blisters are generated

[0105] (4) Cross-sectional observation The conductive paste compositions obtained in the examples and comparative examples were applied onto a release PET film using an applicator so that the dried thickness became 50 μm, and dried in a hot air oven at 100 °C for 1 hour to obtain a conductive sheet The obtained conductive sheet was bonded to a SiC substrate with a thickness of 50 μm, the release PET film was peeled off and bonded to a copper substrate to obtain a laminate of copper substrate-conductive sheet-SiC substrate. The obtained laminate was pressed at 100 °C and 3 MPa using a press machine, then fired in a firing furnace under a nitrogen atmosphere at 300 °C for 20 minutes to thermally decompose the organic substances in the conductive sheet, and then the temperature of the oven was raised to 400 °C to sinter the conductive metal particles. Thereafter, it was cooled to room temperature under a nitrogen atmosphere to obtain a laminated sample Regarding the obtained laminated sample, the cross-section of the bonding portion was confirmed using a scanning electron microscope and evaluated according to the following criteria A: No large cracks, voids, or oxidation are observed in the cross-section B: No large cracks or voids are observed, but pinholes or slight oxidation are confirmed C: Large cracks or voids are observed in the cross-section

[0106]

Table 3

[0107] Good results were obtained in all of Examples 1 to 9. On the other hand, in Comparative Examples 1 to 8, the dispersibility of the metal particles was poor, and surface oxidation, blisters, glass float, and voids were observed in the sintering of the metal. Also T 100 -T 10In comparative examples 1-5, where the value was greater than 50, EDX analysis using a scanning electron microscope revealed oxidation on the inorganic powder surface near the void. [Industrial applicability]

[0108] According to the present invention, it is possible to provide a conductive paste composition that exhibits good dispersibility of inorganic particles, sufficient storage stability, suppression of void and pinhole generation during firing, good dispersibility of organic components, excellent electrode adhesion, and excellent blister resistance. Furthermore, it is possible to provide an electronic device using this conductive paste composition.

Claims

1. It contains (meth)acrylic resin (A), inorganic particles (B), and solvent (C), The (meth)acrylic resin (A) has a weight-average molecular weight (Mw) of 20,000 or more and 600,000 or less, and contains 50% by weight or more of a segment derived from an alkyl (meth)acrylate ester having an alkyl branched structure in the ester substituent, and 5% by weight or more and 40% by weight of a segment derived from a (meth)acrylic acid ester in which the ester substituent is a polyalkylene oxide group distributed along the chain length. The aforementioned polyalkylene oxide group has a peak top molecular weight (X) as evaluated by LC-MS. Ｐ ) and molecular weight dispersion width (M Ｌ ) ratio (X Ｐ / M Ｌ ) is between 0.5 and 1.5, The inorganic particles (B) include conductive particles with an average particle diameter of 0.01 μm or more and 10 μm or less. The solvent (C) is an organic solvent having a boiling point of 200°C or higher and 250°C or lower, in a conductive paste composition.

2. Peak top molecular weight (X) of the polyalkylene oxide group Ｐ The ratio (X) of the number average molecular weight (Mn) of (meth)acrylic resin (A) Ｐ The conductive paste composition according to claim 1, wherein the ratio of ( / Mn) is 0.002 or more and 0.12 or less.

3. The (meth)acrylic resin (A) has a decomposition end temperature T measured by TG-DTA under the condition of a heating rate of 100 °C / min, the decomposition end temperature T １００ and the difference T １０ between the decomposition end temperature T at a heating rate of 10 °C / min １００－ T １０ is 50 °C or lower. The conductive paste composition according to claim 1 or 2.

4. The conductive paste composition according to claim 1 or 2, wherein the (meth)acrylic resin (A) has a plurality of hydroxyl groups or carboxylic acid polar functional groups at one end of the molecular chain.

5. The conductive paste composition according to claim 1 or 2, wherein the solvent (C) is any one of terpineol, dihydroterpineol, and butyl carbitol.

6. The conductive paste composition according to claim 1 or 2, wherein the material of the conductive particles contains silver or copper.

7. An electronic device comprising the conductive paste composition according to claim 1 or 2.

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