Composition for metal bonding, metal paste, method for producing bonded body, and method for producing sintered body

Abstract

Provided is a composition for metal sintering with which it is possible to obtain a metal paste that can be sintered at a relatively low temperature.　A composition for metal sintering according to the present disclosure contains an acid that is solid at room temperature and a basic compound, and / or salts thereof, where a mixture composed of the acid that is solid at room temperature and the basic compound is in a uniform liquid state at 60°C or lower. The composition for metal sintering according to the present disclosure preferably is such that the weight loss value (TG) in the temperature range of 100-300°C is at least 80% when a simultaneous thermogravimetric / differential thermal analysis (TG-DTA) measurement is performed under the measurement conditions indicated below. Using 10-20 mg of the composition for metal bonding as a measurement sample, a simultaneous thermogravimetric / differential thermal analysis (TG-DTA) measurement is performed on the measurement sample at a temperature increase rate of 10°C / min and within a measurement temperature range of 30-400°C in an in-furnace air atmosphere.

Description

Metal bonding composition, metal paste, method for manufacturing a bonded body, and method for manufacturing a sintered body

[0001] This disclosure relates to a metal bonding composition, a metal paste, a method for manufacturing a bonded body, and a method for manufacturing a sintered body. This application claims priority to Japanese Patent Application No. 2024-015935, filed February 5, 2024, the contents of which are incorporated herein by reference.

[0002] Metal nanoparticles, such as silver nanoparticles, can be sintered even at low temperatures. Taking advantage of this property, metal compositions containing metal nanoparticles are used to form metal coating patterns, such as electrodes and conductive circuit patterns, on substrates in the manufacture of various electronic devices (see, for example, Patent Document 1). The metal composition contains metal particles and an organic solvent for dispersing the metal particles. The metal nanoparticles have an average primary particle size of several nanometers to several tens of nanometers. The metal composition is applied to a substrate to form a pattern, and then sintering volatilizes the organic solvent in the metal composition, sintering and fusing the metal nanoparticles to form a conductive layer, such as an electrode, conductor wiring, or conductive circuit pattern.

[0003] However, metal nanoparticles are more expensive and less easy to handle than submicron-sized metal particles. Therefore, the use of conductive pastes using submicron-sized metal particles instead of metal nanoparticles has been investigated (see, for example, Patent Documents 2 and 3). Furthermore, a technique for bonding submicron-sized metal particles via a contact region containing a base metal is known (see, for example, Patent Document 4). A technique for improving sinterability by blending silver oxide or silver carbonate has also been proposed (see, for example, Patent Document 5).

[0004] Also known is a paste containing sintered powder in which metal particles are coated with a capping agent, and it is known that metal oxides can be removed by blending a dicarboxylic acid therein (see Patent Document 6).

[0005] Japanese Patent Application Laid-Open No. 2013-142173 Japanese Patent Application Laid-Open No. 2009-170277 International Publication No. 2009 / 090915 Japanese Patent Application Laid-Open No. 2013-69687 Japanese Patent Application Laid-Open No. 2017-519897 Japanese Patent Application Laid-Open No. 2022-169512

[0006] However, when submicron-sized metal particles are used, there is a problem in that the sintering temperature is higher than when metal nanoparticles are used. High sintering temperatures make it impossible to form a sintered layer on a resin substrate, for example. Furthermore, the technology of Patent Document 4, which adds an activator, disperses solid malonic acid in a solvent in a slurry state to form a suspension, which serves as a dispersion solvent for the metal particles, resulting in a paste with poor dispersibility of the metal particles. Poor dispersibility of the metal particles makes it difficult to stably promote sintering of the metal particles. Patent Document 6 does not disclose any effect when silver particles are used.

[0007] Accordingly, it is an object of the present disclosure to provide a composition for sintering metal particles at relatively low temperatures.

[0008] Another object of the present disclosure is to provide a metal paste that can be sintered at a relatively low temperature, and a method for producing a joined body and a sintered body that can sinter metal particles at a relatively low temperature.

[0009] The present disclosure provides a composition for metal bonding, which comprises an acid and a basic compound that are solid at room temperature, and / or a salt thereof, and the mixture of the acid that is solid at room temperature and the basic compound is in a homogeneous liquid state at 60°C.

[0010] The metal bonding composition preferably has a weight loss (TG) of 80% or more in the range of 100°C to 300°C when subjected to simultaneous differential thermal analysis (TG-DTA) under the following measurement conditions: (Measurement Conditions) Using 10 mg of the metal bonding composition as a measurement sample, differential thermal analysis (TG-DTA) is performed at a heating rate of 10°C / min, in a measurement temperature range of 30°C to 400°C, and in an air atmosphere in a furnace.

[0011] The basic compound is preferably a compound represented by the following formula (1): [In formula (1), R ａ ~R ｃare the same or different and represent a hydrogen atom or a hydrocarbon group which may have a substituent. The substituent may be the same or different and represent an amino group, an N-substituted amino group, an N,N-substituted amino group, an imino group, an N-substituted imino group, or a hydroxy group. ａ ~R ｃ are not hydrogen atoms at the same time. A double line including a dashed line represents a single bond or a double bond. If it is a double bond, R ｃ does not exist. ａ ~R ｃ Any two of these may be bonded to each other to form a ring together with the adjacent nitrogen atom.]

[0012] The acid that is solid at room temperature is preferably a carboxylic acid.

[0013] The melting point of the acid that is solid at room temperature is preferably 50° C. or higher.

[0014] The molar ratio of the number of basic functional groups in the basic compound to the number of carboxylic acid functional groups in the carboxylic acid [number of basic functional groups / number of carboxylic acid functional groups] is preferably 0.05 to 1.5.

[0015] The metal bonding composition preferably further contains an organic solvent.

[0016] The metal bonding composition is preferably a homogeneous liquid at 25° C. and has a viscosity of 0.1 to 1000 Pa·s.

[0017] The boiling points of the basic compound and the organic solvent are preferably 100° C. or higher and 300° C. or lower, and the organic solvent preferably includes at least one organic solvent having a Hansen solubility parameter SP value of 12 or lower.

[0018] The present disclosure also provides a metal paste containing the above-described composition for metal bonding and metal particles.

[0019] The metal paste may further contain a resin.

[0020] The present disclosure also provides a method for producing a bonded body in which an object to be bonded is bonded to a metal, the method including a coating step of coating the metal bonding composition onto the metal.

[0021] The metal is preferably a dried or sintered body of a metal paste containing metal particles on a substrate.

[0022] The method for producing the bonded body includes, after the coating step, a bonded body arranging step of arranging the bonded body on the coated dried body or the sintered body, and a sintering step of sintering the dried body to form a sintered layer, and it is preferable that the sintering in the sintering step is performed by heating at a temperature of 150°C or higher while applying a pressure of 1 MPa or more from the bonded body side.

[0023] The present disclosure also provides a method for manufacturing a bonded body in which a base material and an object to be bonded are bonded via a metal particle sintered body, the method comprising: a semi-drying step of semi-drying the metal paste on the base material to form a semi-dried body; and a sintering step of sintering the semi-dried body to form the metal particle sintered body.

[0024] Preferably, the method for producing the bonded body further comprises, after the semi-drying step, a step of arranging the bonded bodies on the semi-dried body, wherein the semi-drying step is performed at a temperature of 130°C or less, and the sintering step is performed by heating the bonded bodies at a temperature of 150°C or more while applying a pressure of 1 MPa or more from the bonded body side.

[0025] The present disclosure also provides a method for producing a sintered body, in which the metal paste is heated in an inert atmosphere at a temperature of 100° C. to 300° C. to obtain a metal particle sintered body.

[0026] The present disclosure also provides a method for producing a sintered body, which comprises adhering the metal paste onto a resin film and heating the film at a temperature of 140°C or higher for 1 minute or longer to obtain a metal particle sintered body.

[0027] The present disclosure also provides a method for manufacturing a joined body, comprising: a sintered body arrangement step of arranging a sintered body obtained by the above-described method for manufacturing a sintered body on a base material; a member-to-be-joined arrangement step of arranging a member-to-be-joined on the sintered body; and a re-sintering step of further heating and sintering the sintered body.

[0028] According to the composition for metal bonding of the present disclosure, even when nano-sized as well as submicron-sized metal particles are used, a metal paste that can be sintered at a relatively low temperature can be obtained.

[0029] 1 shows an SEM image of a sintered body of the metal paste produced in Example 3 (Preparation Example 36). 2 shows an SEM image of a sintered body of the metal paste produced in Example 3 (Preparation Example 62). 3 shows an SEM image of a sintered body of the metal paste produced in Example 3 (Preparation Example 63). 4 shows an SEM image of a sintered body of the metal paste produced in Example 3 (Preparation Example 64). 5 shows a graph showing the relationship between the sintering temperature and sintering time and the volume resistivity produced in Example 4. 6 shows a cross-sectional SEM image of a joined body produced in Example 6. 7 shows an SEM image of a sintered body produced in Example 8.

[0030] [Composition for Metal Bonding] The composition for metal bonding of the present disclosure includes at least an acid that is solid at room temperature and a basic compound, or at least an acid that is solid at room temperature and a salt of the basic compound. In this specification, an acid that is solid at room temperature may be referred to as a "solid acid," and a salt formed from the solid acid and the basic compound may be referred to as a "solid acid salt." That is, the composition for metal bonding of the present disclosure may be (i) an embodiment including the solid acid and the basic compound, or (ii) an embodiment including the solid acid salt. Aspect (i) may further include the solid acid salt. Aspect (ii) may further include the solid acid and / or the basic compound.

[0031] The mixture of the solid acid and the basic compound is a homogeneous liquid at 60°C, preferably at 60°C and 50°C, more preferably at 60°C, 50°C, and 40°C, even more preferably at 60°C, 50°C, 40°C, and 30°C, and particularly preferably at 60°C, 50°C, 40°C, 30°C, and 25°C. The mixture is a mixture consisting only of the solid acid and the basic compound. However, this does not exclude the inevitable contamination of other components. "Homogeneous liquid" means that the mixture is stored at a certain temperature (60°C, 50°C, 40°C, 30°C, or 25°C) for one day, and then visually inspected for solid precipitation or liquid phase separation. No solid precipitation, precipitation of the composition at the bottom of the container, or separation of the composition is observed, even when left standing or stirred.

[0032] In the present disclosure, the mixture may be a eutectic mixture that can be formed from the solid acid and the basic compound. Here, a eutectic mixture refers to a mixture in which two or more substances are mixed and the resulting mixture has a melting point lower than the melting points of each of the constituent substances of the mixture. Such a mixture of two or more substances may exhibit the lowest melting point at a specific ratio of the substances, called the eutectic point. When the mixture is a eutectic mixture, the eutectic point is, for example, 60° C. or lower, preferably 30° C. or lower.

[0033] In the present disclosure, the mixture is not limited to being in a homogeneous liquid state only at the eutectic point, but also includes a mixture that is in a homogeneous liquid state at ambient temperature, where the ambient temperature is 60°C.

[0034] The metal bonding composition preferably has a weight loss (TG) of 80% or more in the range of 100°C to 300°C when subjected to simultaneous differential thermal analysis (TG-DTA) under the following measurement conditions. A weight loss of 85% or more is more preferable, and 90% or more is particularly preferable. (Measurement Conditions) 10 mg of the metal bonding composition is used as a measurement sample, and differential thermal analysis (TG-DTA) is performed on the measurement sample at a heating rate of 10°C / min, in a measurement temperature range of 30°C to 400°C, in an air atmosphere in a furnace.

[0035] In this specification, the term "furnace air atmosphere" includes, for example, when the gas controlling the furnace atmosphere in a TG-DTA is air and the protective gas for the apparatus is nitrogen gas, a state in which air is flowing at a flow rate equal to or greater than that of nitrogen gas; the oxygen concentration in the furnace does not necessarily have to be the same as that of air. When the weight loss (TG) is 80% or greater within the above temperature range, i.e., when the metal bonding composition volatilizes by 80% or greater within the above temperature range, the action of the ionic and liquid metal bonding composition promotes metal diffusion on the metal particle surfaces at low temperatures. Since the mixture volatilizes upon heating, sintering between particles is less likely to be inhibited, thereby promoting sintering of the metal particles. Furthermore, the temperature at which the differential value (DTG) of the weight loss (TG) of the metal bonding composition is maximized is preferably 100°C to 300°C, more preferably 120°C to 200°C. When the temperature at which the DTG is maximized is 100°C or greater, the effect of the metal bonding composition described above is exerted at high temperatures, promoting metal diffusion. By setting the temperature at which the DTG reaches a maximum at 300° C. or less, the amount of organic residue is reduced, making it difficult for sintering to be inhibited between metal particles.

[0036] (Solid Acid) The solid acid in the composition for metal bonding of the present disclosure is an acid that is solid at room temperature (25° C.) The melting point of the solid acid is preferably 50° C. or higher, more preferably 100° C. or higher.

[0037] The solid acid is preferably an acid having an -OH group in the molecule, and examples of such acids include acids having a phenolic hydroxyl group and acids having a carboxyl group (carboxylic acids). Examples of acids having a phenolic hydroxyl group include phenol, 4-ethoxyphenol, dibutylhydroxytoluene, o-cresol, m-cresol, p-cresol, 1-naphthol, 2-naphthol, catechol, and hydroquinone. Examples of acids having a carboxyl group (carboxylic acids) include saturated aliphatic monocarboxylic acids such as capric acid, lauric acid, myristic acid, palmitic acid, margaric acid, and stearic acid; aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, and adipic acid; aromatic carboxylic acids such as benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, trimesic acid, hemimellitic acid, and pyromellitic acid; and maleic acid, fumaric acid, cyclopentanecarboxylic acid, and citric acid. Among these, the acid having an —OH group in the molecule is preferably a carboxylic acid, and more preferably malonic acid. The solid acid may be used alone or in combination of two or more kinds.

[0038] The solid acid has a higher boiling point than an acid that is liquid at room temperature, and therefore can promote sintering of metal particles. In particular, when malonic acid is used as the solid acid, it decomposes into acetic acid and carbon dioxide above the melting point of malonic acid (130°C), sufficiently promoting sintering of metal particles. Furthermore, the basic compound dissolves malonic acid, improving its dispersibility in the metal paste, fully demonstrating the effects of malonic acid and preventing sedimentation of metal particles. The same applies when malonic acid and the basic compound are contained as malonates. On the other hand, when acetic acid, which is liquid at room temperature, is used, its low boiling point causes it to volatilize too quickly during heating, leading to volatilization before the sintering temperature is reached, and therefore promoting sintering of metal particles is insufficient.

[0039] (Basic Compound) The basic compound is not particularly limited as long as it functions as a base and realizes the effects of the present disclosure, and specific examples include ammonia, amine compounds, nitrogen-containing compounds such as imidazoles and pyridines, and phosphorus-containing compounds such as phosphines and phosphate esters. Only one type of the basic compound may be used, or two or more types may be used.

[0040] As the basic compound, nitrogen-containing compounds are preferred from the viewpoint of excellent dispersibility and volatility of the solid acid and metal particles, and compounds represented by the following formula (1) are more preferred.

[0041] [In formula (1), R ａ ~R ｃ are the same or different and represent a hydrogen atom or a hydrocarbon group which may have a substituent. The substituent may be the same or different and represent an amino group, an N-substituted amino group, an N,N-substituted amino group, an imino group, an N-substituted imino group, or a hydroxy group. ａ ~R ｃ are not hydrogen atoms at the same time. A double line including a dashed line represents a single bond or a double bond. If it is a double bond, R ｃ does not exist. ａ ~R ｃ Any two of these may be bonded to each other to form a ring together with the adjacent nitrogen atom.]

[0042] R ａ ~R ｃ Among these, the substituent in is preferably an amino group, an N-substituted amino group, an N,N-substituted amino group, an imino group, or an N-substituted imino group.

[0043] R ａ ~R ｃ Examples of the hydrocarbon group in include an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, etc. Among these, an aliphatic hydrocarbon group and an alicyclic hydrocarbon group are preferred, and an aliphatic hydrocarbon group is more preferred.

[0044] Examples of the aliphatic hydrocarbon group include linear or branched alkyl groups, linear or branched alkenyl groups, linear or branched alkynyl groups, linear or branched alkylidene groups, etc. Among these, linear or branched alkyl groups are preferred.

[0045] The linear or branched alkyl group is preferably a linear alkyl group having 1 to 20 carbon atoms, more preferably 1 to 15 carbon atoms, or a branched alkyl group having 3 to 12 carbon atoms, more preferably 3 to 8 carbon atoms, and even more preferably 3 to 6 carbon atoms. Specific examples include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a decyl group, a dodecyl group, a tetradecyl group, an octadecyl group, an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, and a 2-ethylhexyl group.

[0046] The linear or branched alkenyl group is preferably a linear alkenyl group having 2 to 12 carbon atoms, more preferably 2 to 8 carbon atoms, and even more preferably 2 to 4 carbon atoms, or a branched alkenyl group having 3 to 12 carbon atoms, more preferably 3 to 8 carbon atoms, and even more preferably 3 to 6 carbon atoms. Specific examples include vinyl group, 1-propenyl group, 2-propenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group, 4-pentenyl group, 1-hexenyl group, 3-hexenyl group, 5-hexenyl group, 1-heptenyl group, 1-octenyl group, 1-nonenyl group, 1-decenyl group, isopropenyl group, 2-methyl-1-propenyl group, methallyl group, 3-methyl-2-butenyl group, and 4-methyl-3-pentenyl group.

[0047] The linear or branched alkynyl group is preferably a linear alkynyl group having 2 to 12 carbon atoms, more preferably 2 to 8 carbon atoms, and even more preferably 2 to 4 carbon atoms, or a branched alkynyl group having 3 to 12 carbon atoms, more preferably 3 to 8 carbon atoms, and even more preferably 3 to 6 carbon atoms. Specific examples include an ethynyl group, a 1-propynyl group, a 2-propynyl group, a 1-butynyl group, a 2-butynyl group, a 3-butynyl group, a 1-pentynyl group, a 2-pentynyl group, a 3-pentynyl group, a 4-pentynyl group, a 1-hexynyl group, a 2-hexynyl group, a 3-hexynyl group, a 4-hexynyl group, a 5-hexynyl group, a 1-heptynyl group, a 1-octynyl group, a 1-nonynyl group, a 1-decynyl group, a trimethylsilylethynyl group, and a triethylsilylethynyl group.

[0048] The linear or branched alkylidene group is preferably a linear alkylidene group having 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, and even more preferably 2 to 4 carbon atoms, or a branched alkylidene group having 3 to 12 carbon atoms, more preferably 3 to 8 carbon atoms, and even more preferably 3 to 6 carbon atoms. Specific examples include a methylidene group, a propylidene group, an isopropylidene group, a butylidene group, an isobutylidene group, a sec-butylidene group, a pentylidene group, an isopentylidene group, an octylidene group, and an isooctylidene group.

[0049] Examples of the alicyclic hydrocarbon group include a cycloalkyl group and a cycloalkenyl group.

[0050] The cycloalkyl group is preferably a cycloalkyl group having 3 to 12 carbon atoms, more preferably 4 to 10 carbon atoms, and even more preferably 5 to 8 carbon atoms. Specific examples include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, and a cyclodecyl group.

[0051] The cycloalkenyl group is preferably a cycloalkenyl group having 3 to 12 carbon atoms, more preferably 4 to 10 carbon atoms, and even more preferably 5 to 8 carbon atoms. Specific examples include a cyclopentenyl group and a cyclohexenyl group.

[0052] The aromatic hydrocarbon group is preferably an aryl group having 6 to 18 carbon atoms, more preferably 6 to 15 carbon atoms, and even more preferably 6 to 10 carbon atoms. Specific examples include a phenyl group and a naphthyl group.

[0053] In formula (1), the double line including the dashed line represents a single bond or a double bond. When the double line including the dashed line is a double bond, R ｃ does not exist, and R in formula (1) ａ and R ｂ The nitrogen atom to which is bonded represents an imino group or an N-substituted imino group.

[0054] R ａ ~R ｃ The total number of amino groups, N-substituted amino groups, and N,N-substituted amino groups that may be contained in the alkyl group is preferably 0 to 6, more preferably 1 to 4, and even more preferably 1 or 2.

[0055] R ａ ~R ｃ The total number of imino groups and N-substituted imino groups that may be possessed by the alkyl group is preferably 0 to 4, more preferably 1 to 3, and even more preferably 1 or 2.

[0056] R ａ ~R ｃ The total number of hydroxy groups that may be possessed by is preferably 0 to 6, more preferably 1 to 4, and even more preferably 1 or 2.

[0057] The substituents of the N-substituted amino group, N,N-substituted amino group, and N-substituted imino group include the above-mentioned R ａ ~R ｃ Examples of the hydrocarbon group include the hydrocarbon groups exemplified and explained in the above.

[0058] R ａ ~R ｃ Any two of these may be bonded to each other to form a ring together with the adjacent nitrogen atom. Examples of the ring formed include a pyrrolidine ring, a pyrroline ring, a piperidine ring, a pyrrole ring, an imidazolidine ring, an imidazole ring, a piperazine ring, an imidazolidine ring, a pyridine ring, a diazine ring, and a triazine ring.

[0059] R ａ ~R ｃ The hydrocarbon group in may have a substituent other than an amino group, an N-substituted amino group, an N,N-substituted amino group, an imino group, an N-substituted imino group, and a hydroxy group. Examples of the substituent include a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, an iodine atom), an oxo group, a substituted oxy group (an alkoxy group having 1 to 4 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, an aralkyloxy group having 7 to 16 carbon atoms, an acyloxy group having 1 to 4 carbon atoms, etc.), a carboxy group, a substituted oxycarbonyl group (an alkoxycarbonyl group having 1 to 4 carbon atoms, an aryloxycarbonyl group having 6 to 10 carbon atoms, an aralkyloxycarbonyl group having 7 to 16 carbon atoms, etc.), a cyano group, a nitro group, a sulfo group, a mercapto group, a heterocyclic group, etc.

[0060] Specific examples of the compound represented by the formula (1) include, for example, R ａ ~R ｃ an alkylamine in which at least one of R in formula (1) is a linear or branched alkyl group; ａ , R ｂ are independently a hydrogen atom or a linear or branched alkyl group, and R ｃ is a linear or branched alkyl group having one hydroxy group; ａ is a hydrogen atom or a linear or branched alkyl group, and R ｂ and R ｃ are the same or different and are linear or branched alkyl groups each having one hydroxy group; ａ ~R ｃ are the same or different and are a linear or branched alkyl group having one hydroxy group; ａ , R ｂ are the same or different and are a hydrogen atom or a linear or branched alkyl group, and R ｃ an aminoalkanediol in which R in formula (1) is a linear or branched alkyl group having two hydroxy groups;ａ ~R ｃ a diamine having a total of one amino group; ａ ~R ｃ a triamine having a total of two amino groups; R in formula (1) ａ ~R ｃ a diaminoalkanol having a total of one amino group and a total of one hydroxy group; ａ ~R ｃ an imidazole compound in which a ring is formed by incorporating nitrogen atoms of the imino groups, the total number of which is 1; ａ , R ｂ is bonded to an imino group, and a ring is formed containing the imino group (such as a pyridine-based compound, a diazine-based compound, or a triazine-based compound).

[0061] Examples of the alkylamine include methylamine, ethylamine, propylamine, butylamine, pentylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, piperidine, trimethylamine, triethylamine, tripropylamine, tributylamine, triamylamine, tricyclohexylamine, N,N-dimethylaminodecylamine, N,N-dimethylaminododecylamine, N,N-dicyclohexylmethylamine, 4-dimethylaminopyridine, 2-aminopyrazine, 2-aminopyrimidine, 3-aminopyridazine, 2-aminotriazine, diazabicyclononene, and diazabicycloundecene.

[0062] Examples of the monoalkanolamine include 2-aminoethanol, 3-aminopropanol, 1-amino-2-propanol, 1-amino-2-methyl-2-propanol, 1-dimethylamino-2-propanol, 2-amino-2-methyl-1-propanol, 4-amino-1-butanol, 6-amino-1-hexanol, 10-amino-1-decanol, 12-amino-1-dodecanol, N-methyl-2-aminoethanol, N-ethyl-2-aminoethanol, N-propyl-2-aminoethanol, 2-dimethylaminoethanol, 6-diethylaminohexanol, 1-(2-hydroxyethyl)pyrrolidine, 2-(hydroxymethyl)pyrrolidine, 2-(2-hydroxyethyl)-1-methylpyrrolidine, 1-piperidineethanol, and 1-ethanol-4-propanolpiperidine.

[0063] Examples of the dialkanolamine include diethanolamine, di-n-propanolamine, diisopropanolamine, di-n-butanolamine, diisobutanolamine, and N-methyldiethanolamine.

[0064] Examples of the trialkanolamine include triethanolamine (2,2',2"-nitrilotriethanol), tri-n-propanolamine, triisopropanolamine, tri-n-butanolamine, and triisobutanolamine.

[0065] Examples of the aminoalkanediol include 1-amino-2,3-propanediol, 4-amino-1,2-butanediol, 4-amino-1,3-butanediol, 2-amino-1,3-propanediol, 2-amino-2-methyl-1,3-propanediol, 1-methylamino-2,3-propanediol, 1-ethylamino-2,3-propanediol, 1-propylamino-2,3-propanediol, 1-butylamino-2,3-propanediol, 3-dimethylamino-1,2-propanediol, and 2-diethylamino-1,3-propanediol.

[0066] Examples of the diamine include 1,3-propanediamine, 2,2-dimethyl-1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,5-diamino-2-methylpentane, N,N'-dimethylethylenediamine, N,N'-diethylethylenediamine, N,N'-dimethyl-1,3-propanediamine, N,N'-diethyl-1,3-propanediamine, N,N'-dimethyl-1,4-butanediamine, N,N'-diethyl-1,4-butanediamine, and N,N'-dimethyl-1,6 -hexanediamine, N,N,N',N'-tetramethyl-1,6-hexanediamine, N,N-dimethylethylenediamine, N,N-diethylethylenediamine, N,N-dimethyl-1,3-propanediamine, N,N-diethyl-1,3-propanediamine, N,N-dimethyl-1,4-butanediamine, N,N-diethyl-1,4-butanediamine, N,N-dimethyl-1,6-hexanediamine, 1,2-cyclohexanediamine, 1,4-cyclohexanediamine, piperazine, N-methylpiperazine, N-ethylpiperazine, N,N'-dimethylpiperazine, and homopiperazine.

[0067] Examples of the triamine include diethylenetriamine, N,N,N',N",N"-pentamethyldiethylenetriamine, N,N,N',N",N"-pentakis(2-hydroxypropyl)diethylenetriamine, 3,3'-diaminodipropylamine, N-(3-aminopropyl)-N-methyl-1,3-propanediamine, N'-[3-(dimethylamino)propyl]-N,N-dimethyl-1,3-propanediamine, 2,6,10-trimethyl-2,6,10-triazaundecane, N-(2-aminoethyl)piperazine, 1,4,7-triazacyclononane, N,N,N',N",N"-pentakis(2-hydroxypropyl)diethylenetriamine, 1-(2-aminoethyl)-4-methylpiperazine, and 1-(2-dimethylaminoethyl)-4-methylpiperazine.

[0068] Examples of the diaminoalkanol include 1,3-diaminopropan-2-ol, 2-(2-aminoethylamino)ethanol, 2-(2-aminopropylamino)ethanol, 2-(2-aminoethylmethylamino)ethanol, 1-(2-hydroxyethyl)piperazine, 4-methylpiperazine-1-ethanol, and 1,4-bis(2-hydroxyethyl)piperazine.

[0069] Examples of the imidazole compound include imidazole, 2-methylimidazole, 2-propylimidazole, N-methylimidazole, N-propylimidazole, N-butylimidazole, 1-(2-hydroxyethyl)imidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 1-acetylimidazole, and 2-hydroxybenzimidazole.

[0070] Examples of the nitrogen-containing aromatic compound include pyridine, α-picoline, β-picoline, γ-picoline, 2,6-lutidine, 2,3-lutidine, pyrazine, 2-hydroxypyrazine, pyrimidine, 2-hydroxypyrimidine, 4-hydroxypyrimidine, pyridazine, 3-hydroxypyridazine, 4-hydroxypyridazine, triazine, and 2-hydroxytriazine.

[0071] Among the compounds represented by the formula (1), the alkylamines, diamines, imidazole compounds, and nitrogen-containing aromatic compounds are preferred, the alkylamines and diamines are more preferred, and the alkylamines are particularly preferred, from the viewpoints that the viscosity of the metal paste becomes appropriate, making it easy to handle, and that the boiling point is not too high, making it easy to remove during sintering.

[0072] The amine compound preferably has an aliphatic hydrocarbon group (e.g., an alkyl group or an alkylene group) or an alicyclic hydrocarbon group (e.g., a cyclohexyl group) having 5 or more carbon atoms (e.g., 5 to 18), from the viewpoint of being less restricted in molecular movement, becoming a viscous yet fluid liquid, and making it easier to disperse metal particles in an organic solvent. The number of carbon atoms is more preferably 6 or more (e.g., 6 to 18), and even more preferably 8 or more (e.g., 8 to 16). The amino group in the amine compound may be any of primary, secondary, and tertiary amino groups, but a tertiary amino group is preferred.

[0073] Therefore, the compound represented by the formula (1) is preferably an alkylamine having a tertiary amino group and an alkyl group having 5 or more carbon atoms, or a diamine having an alkyl group having 5 or more carbon atoms.

[0074] The composition for metal bonding preferably further contains an organic solvent, which not only makes it possible to adjust the viscosity of the composition for metal bonding, but also makes it easier to prepare the composition for metal bonding and improves the dispersibility of metal particles. As the organic solvent, any known or conventional organic solvent used for dispersing metal particles can be used, and examples thereof include aliphatic hydrocarbons such as pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, and tetradecane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; aromatic hydrocarbons such as toluene, xylene, and mesitylene; alcohols such as methanol, ethanol, propanol, n-butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, n-nonanol, n-decanol, and menthol; diols such as ethylene glycol and 1,3-butylene glycol; diethylene glycol monoethyl ether, diethylene glycol dibutyl ether, diethylene glycol methyl-n-butyl ether, propylene glycol monomethyl ether, and dipropylene glycol methyl-isopentyl Examples of suitable organic solvents include glycol ethers such as ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, dipropylene glycol methyl n-propyl ether, dipropylene glycol methyl n-butyl ether, dipropylene glycol methyl cyclopentyl ether, triethylene glycol dimethyl ether, triethylene glycol methyl n-butyl ether, tripropylene glycol monomethyl ether, tripropylene glycol methyl n-propyl ether, tripropylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether; glycol ether esters such as diethylene glycol n-butyl ether acetate, diethylene glycol ethyl ether acetate, and diethylene glycol butyl ether acetate, and esters such as triethyl citrate. Examples of suitable organic solvents include terpene-based solvents such as terpineol and dihydroterpineol. The type and amount of organic solvent can be determined appropriately depending on the desired concentration and viscosity of the metal bonding composition, particularly depending on the type of basic compound.The organic solvents may be used alone or in combination of two or more.

[0075] The organic solvent preferably contains at least one organic solvent having a Hansen solubility parameter (sometimes referred to as "SP value") of 12 or less. When the SP value is 12 or less, the dispersibility of the metal particles is excellent, and the handleability of the resulting metal paste is also excellent. The SP value is, for example, 5 or more, and may be 8 or more, 9 or more, or 10 or more. In this specification, the unit of SP value is (cal / cm ３ ) （１／２） is.

[0076] The basic compound preferably has an SP value of 7 or more, more preferably 7.7 or more. When the SP value is 7 or more, the dispersibility of the metal particles is excellent and the handling property as a paste is excellent. The SP value is preferably 15 or less, more preferably 14 or less, and even more preferably 11 or less.

[0077] The boiling points of the basic compound and the organic solvent are each preferably 100 to 300°C, more preferably 120 to 290°C, and even more preferably 150 to 280°C. When the boiling point is 100°C or higher, the evaporation rate during drying becomes appropriate, making it difficult for the solid acid to precipitate and also suppressing premature solidification of the metal paste, resulting in excellent handleability. When the boiling point is 300°C or lower, the solvent can be sufficiently removed during sintering, making it easy to obtain a good sintered body.

[0078] When the composition for metal bonding contains the organic solvent, the content of the organic solvent in the composition for metal bonding is preferably 20 to 99 mass %, more preferably 30 to 99 mass %, still more preferably 40 to 98 mass %, and particularly preferably 50 to 95 mass %, relative to 100 mass % of the total amount of the composition for metal bonding. When the content is within the above range, the dispersibility of metal particles is superior.

[0079] When the composition for metal bonding contains the organic solvent, the total content of the solid acid, the basic compound, and the solid acid salt in the composition for metal bonding is preferably 1 to 70 mass%, more preferably 1 to 60 mass%, even more preferably 2 to 55 mass%, and particularly preferably 5 to 30 mass%, relative to 100 mass% of the total amount of the composition for metal bonding.

[0080] When the composition for metal bonding does not contain the organic solvent, the total content of the solid acid, the basic compound, and the solid acid salt in the composition for metal bonding is preferably 90 to 100 mass%, more preferably 95 to 100 mass%, and even more preferably 98 to 100 mass%, relative to 100 mass% of the total amount of the composition for metal bonding.

[0081] The metal bonding composition is, for example, a homogeneous liquid at 60°C, preferably at 60°C and 50°C, more preferably at 60°C, 50°C, and 40°C, even more preferably at 60°C, 50°C, 40°C, and 30°C, and particularly preferably at 60°C, 50°C, 40°C, 30°C, and 25°C. The term "homogeneous liquid" means that the metal sintering composition is stored at a constant temperature (60°C, 50°C, 40°C, 30°C, or 25°C) for one day, and then visually inspected for solid precipitation or liquid phase separation. No solid precipitation or precipitation or separation of the mixture at the bottom of the container is observed, even when left standing or stirred. Furthermore, the viscosity of the metal bonding composition at 25°C (at a rotation speed of 10 s －１ ) is preferably 0.1 to 1000 Pa·s, more preferably 0.2 to 500 Pa·s, and even more preferably 0.5 to 100 Pa·s. In these cases, the metal paste has appropriate fluidity, and a metal paste with excellent dispersibility of metal particles can be obtained.

[0082] The metal bonding composition may contain other components in addition to the above-mentioned components. Examples of the other components include additives such as acids other than the solid acids (acids that are liquid at room temperature), dispersants, surface energy adjusters, plasticizers, leveling agents, antifoaming agents, adhesion promoters, surfactants (fluorine compounds, silicone compounds, etc.), fillers (inorganic and / or organic fillers), colorants (pigments and dyes), coupling agents, and thixotropy-imparting agents. Only one of the other components may be used, or two or more may be used. The content of the other components in the metal bonding composition is, for example, 1% by mass or less (preferably 0.5% by mass or less). The content of the acid other than the solid acids in the metal bonding composition is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, even more preferably 20 parts by mass or less, and particularly preferably 10 parts by mass or less, per 100 parts by mass of the total amount of the solid acids.

[0083] [Metal Paste] The metal paste of the present disclosure contains at least the composition for metal bonding and metal particles. That is, the metal paste contains at least metal particles and an acid and a basic compound that are solid at room temperature, and / or a salt thereof. In this specification, a metal paste containing at least the composition for metal bonding and metal particles may be referred to as "metal paste (X)."

[0084] (Metal Particles) The metal constituting the metal particles can be any known or commonly used metal or semimetal with electrical conductivity, including transition metals such as gold, silver, copper, nickel, palladium, tin, aluminum, bismuth, and indium; Group 13 elements such as boron and aluminum; Group 14 elements such as silicon and germanium; Group 15 elements such as antimony; or alloys thereof. Among these, silver is preferred because it produces sintered bodies with high electrical conductivity. The metal particles may be surface-modified metal particles whose surfaces are coated with an organic protective agent. Surface-modified metal particles ensure spacing between metal particles, suppress aggregation, and provide excellent dispersibility in metal pastes. Only one type of metal particle or two or more types (e.g., metal particles with different organic protective agents or metal particles with different average particle sizes) may be used.

[0085] The organic protective agent is not particularly limited, and examples thereof include known or commonly used organic protective agents used as protective agents (stabilizers) for metal particles. Examples of the organic protective agent include organic protective agents having functional groups such as carboxyl groups, hydroxyl groups, carbonyl groups, amide groups, ether groups, amino groups, sulfo groups, sulfonyl groups, sulfinic acid groups, sulfenic acid groups, mercapto groups, phosphate groups, and phosphite groups. Among the functional groups, carboxyl groups, hydroxyl groups, amino groups, sulfo groups, and mercapto groups are preferred, and carboxyl groups and amino groups are more preferred. The organic protective agents may be used alone or in combination of two or more.

[0086] From the viewpoint of excellent sinterability at low temperatures, the metal particles preferably contain metal particles having an average particle diameter of 1.0 μm or less (preferably 0.9 μm or less, more preferably 0.8 μm or less). When the average particle diameter is 1.0 μm or less, contact points between the metal particles are easily formed, which facilitates sintering between the metal particles and allows for the formation of strong necking, resulting in superior strength, electrical properties, and thermal properties of the sintered body. The average particle diameter is preferably 0.2 μm or more, more preferably 0.5 μm or more, and even more preferably 0.6 μm or more. When the average particle diameter is 0.2 μm or more, it is cost-effective, and even if the metal particles are surface-modified metal particles, it is possible to increase the metal content in the paste, and defects in the sintered body due to volatilization of organic substances are less likely to occur. In this specification, the average particle diameter is the volume-average particle diameter that can be measured by laser diffraction / scattering.

[0087] The shape of the metal particles is not particularly limited, and examples thereof include spherical (including spherical and elliptical), flake (scale-like), dendritic, and lumpy shapes, with spherical shapes being preferred.

[0088] The metal paste (X) may contain metal nanoparticles or metal microparticles (metal particles having an average particle diameter of more than 1.0 μm) in addition to the metal particles having an average particle diameter of 0.2 to 1.0 μm. The content of the metal particles having an average particle diameter of 0.2 to 1.0 μm is preferably more than 50% by mass, more preferably 60% by mass or more, and even more preferably 65% ​​by mass or more, relative to 100% by mass of the total amount of the metal particles.

[0089] From the viewpoint of excellent sinterability of the metal particles, the content of the metal microparticles in the metal paste (X) is preferably 50 mass% or less, more preferably 40 mass% or less, and even more preferably 35 mass% or less, relative to 100 mass% of the total amount of the metal particles.

[0090] Furthermore, in the metal paste (X), the content of metal nanoparticles is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 2% by mass or less, relative to the total amount of metal particles (100% by mass). A content of 10% by mass or less is cost-effective, and even if the metal particles are surface-modified metal particles, it is possible to increase the metal content in the paste, making it less likely for defects in the sintered body to occur due to volatilization of organic matter. The content can be calculated from the particle size distribution obtained by measurement using a laser diffraction / scattering method. The metal nanoparticles have an average particle diameter of 100 nm or less, preferably 80 nm or less, and more preferably 60 nm or less.

[0091] The content of the metal particles in the metal paste (X) is preferably 70 to 99 mass%, more preferably 72 to 97 mass%, and even more preferably 80 to 95 mass%, relative to 100 mass% of the total amount of the metal paste (X).

[0092] The content of the solid acid in the metal paste (X) is preferably 0.01 to 5 mass %, more preferably 0.05 to 4 mass %, and even more preferably 0.1 to 3 mass %, relative to 100 mass % of the total amount of the metal paste (X). The content of the solid acid is the total content of the solid acid and the solid acid in the solid acid salt.

[0093] The content of the basic compound in the metal paste (X) is preferably 0.05 to 5 mass %, more preferably 0.08 to 4 mass %, and even more preferably 0.1 to 3 mass %, relative to 100 mass % of the total amount of the metal paste (X). The content of the basic compound is the total content of the basic compound and the basic compound in the solid acid salt.

[0094] When the solid acid is an acid having a phenolic hydroxyl group or a carboxylic acid, the molar ratio of the number of basic functional groups (preferably the number of amine functional groups) of the basic compound to the number of acid functional groups (the number of phenolic hydroxyl groups in the case of an acid having a phenolic hydroxyl group, or the number of carboxylic acid functional groups in the case of a carboxylic acid) of the solid acid [number of basic functional groups / number of acid functional groups] is preferably 0.05 to 1.5, more preferably 0.08 to 1.0, even more preferably 0.1 to 0.8, and particularly preferably 0.1 to 0.5. When the molar ratio is 0.05 or more (particularly 0.1 or more), the solid acid is easily homogenized (liquefied, uniformly gelled, etc.), the dispersibility of the solid acid is good, and sintering is further promoted. When the molar ratio is 1.5 or less (particularly 0.5 or less), the amount of sintering inhibitors is small, and sintering of the metal particles is further promoted.

[0095] When the solid acid is an acid having a phenolic hydroxyl group or a carboxylic acid, the molar ratio [number of basic functional groups / number of acid functional groups] of the basic compound in the composition for metal bonding to the number of acid functional groups of the solid acid (the number of phenolic hydroxyl groups in the case of an acid having a phenolic hydroxyl group, or the number of carboxylic acid functional groups in the case of a carboxylic acid) is preferably within the range of 0.5a to 2a, where a represents the molar ratio [number of basic functional groups / number of acid functional groups] of the number of basic functional groups of the basic compound (preferably the number of amine functional groups) to the number of acid functional groups of the solid acid at the eutectic point of the basic compound and the solid acid.

[0096] The metal paste (X) may contain an organic solvent. Examples of the organic solvent include those exemplified and explained as the organic solvent that may be contained in the composition for metal bonding described above.

[0097] The metal paste (X) preferably contains an organic solvent in which the solid acid and the basic compound are uniformly dissolved. By including such an organic solvent, the solid acid, the basic compound, and the solid acid salt do not separate, resulting in excellent dispersibility of the metal particles and more sufficient promotion of sintering of the metal particles. The metal paste (X) containing the organic solvent in which the solid acid and the basic compound are uniformly dissolved can be obtained by first mixing the solid acid, the basic compound, and / or the solid acid salt with an organic solvent to form a uniformly dissolved dispersion solvent, and then mixing the metal particles with the organic solvent.

[0098] The content of the organic solvent in the metal paste (X) is preferably 0.5 to 25 mass %, more preferably 2 to 20 mass %, and even more preferably 5 to 15 mass %, relative to 100 mass % of the total amount of the metal paste (X). When the content is within the above range, the dispersibility of the metal particles is superior.

[0099] The metal paste (X) may contain a resin. By containing a resin, the metal paste can be imparted with thixotropy and adhesiveness to a substrate. Only one type of resin may be used, or two or more types may be used.

[0100] Examples of the resin include known or commonly used resins that are blended into metal pastes, such as thermoplastic resins and thermosetting resins. Specific examples of the resin include polycarbonate resins, polyester resins, polyamide resins, polyurethane resins, polyimide resins, polyolefin resins, (meth)acrylic resins, styrene resins, halogen-containing vinyl resins (vinyl chloride-vinyl acetate copolymers, etc.), polyvinyl acetal resins (polyvinyl butyral resins, etc.), cellulose resins (ethyl cellulose resins, alkyl cellulose resins, etc.), thermoplastic silicone resins, and thermosetting resins (epoxy resins, unsaturated polyester resins, diallyl phthalate resins, silicone resins, etc.).

[0101] The resin content in the metal paste (X) is preferably more than 0 mass% and 1 mass% or less, more preferably 0.05 to 1.0 mass%, and even more preferably 0.1 to 0.9 mass%, relative to 100 mass% of the total amount of the metal paste (X).

[0102] The metal paste (X) may contain other components in addition to the above-mentioned components. Examples of the other components include acids other than the solid acids (acids that are liquid at room temperature), dispersants, surface energy adjusters, plasticizers, leveling agents, antifoaming agents, adhesion promoters, surfactants (fluorine compounds, silicone compounds, etc.), fillers (inorganic and / or organic fillers), colorants (pigments and dyes), coupling agents, and additives such as thixotropy-imparting agents. Only one of the other components may be used, or two or more may be used. The content of the other components in the metal paste (X) is, for example, 1% by mass or less (preferably 0.5% by mass or less). The content of the acid other than the solid acid in the metal paste is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, even more preferably 20 parts by mass or less, and particularly preferably 10 parts by mass or less, per 100 parts by mass of the total amount of the solid acids.

[0103] The metal paste (X) can take various forms without any particular limitation. For example, it can be prepared by dispersing metal particles in a solvent (dispersion medium, particularly an organic solvent) in a kneaded state.

[0104] The metal paste (X) preferably has fluidity at 25° C. For example, the viscosity of the metal paste (X) (at 25° C., a rotation speed of 10 s －１ ) is preferably 1 to 1000 Pa·s, more preferably 5 to 800 Pa·s, and even more preferably 10 to 500 Pa·s. The viscosity can be measured using a rheometer (trade name "MCR302", manufactured by Anton Paar) with a measuring jig of PP25 and a gap of 0.2 mm. When the viscosity is within the above range, the metal paste has appropriate fluidity, and it is possible to obtain a metal paste that is excellent in various printability properties.

[0105] The TI value (JIS Z3248-3) of the metal paste (X) at 25° C. is, for example, preferably 0.1 to 1.5, more preferably 0.2 to 1.2, even more preferably 0.3 to 1.0, and particularly preferably 0.5 to 0.8.

[0106] The metal paste (X) can be obtained by mixing the solid acid and the basic compound with an organic solvent, and then mixing metal particles in. More specifically, the metal paste (X) can be produced by mixing the solid acid and the basic compound to obtain a composition for metal bonding, mixing the composition for metal bonding with the organic solvent to prepare a solvent (dispersion solvent) for dispersing the metal particles, and adding this solvent to the remaining components such as the metal particles.

[0107] The present disclosure also provides a metal paste containing at least an additive that decomposes at 130 to 185°C to promote sintering of metal particles, and metal particles. In this specification, a metal paste containing at least the additive and the metal particles may be referred to as "metal paste (Y)." In this specification, the additive that decomposes at 130 to 185°C to promote sintering of metal particles may be referred to as "additive (Z)." Because additive (Z) decomposes at 130 to 185°C, it decomposes at the appropriate temperature to promote sintering of metal particles. On the other hand, if an additive with too low a decomposition temperature is used, it is presumed that it volatilizes too quickly during heating and volatilizes before the sintering temperature is reached, resulting in insufficient promotion of sintering of metal particles. Furthermore, if an additive with too high a decomposition temperature is used, it will not decompose at the sintering temperature and will not promote sintering of metal particles.

[0108] The additive (Z) is preferably a compound that generates a low molecular weight carboxylic acid compound at the decomposition temperature. It is believed that generating a low molecular weight carboxylic acid compound at the decomposition temperature promotes sintering of the metal particles. The low molecular weight carboxylic acid compound preferably has a boiling point and / or decomposition temperature of 170°C or lower, more preferably 150°C or lower, and particularly preferably 130°C or lower. The low molecular weight carboxylic acid compound is preferably a carboxylic acid having 1 to 4 carbon atoms (formic acid, acetic acid, lactic acid, butyric acid, etc.), and particularly preferably acetic acid. It is believed that the low molecular weight carboxylic acid compound generated by decomposition volatilizes too quickly during heating, resulting in the low molecular weight carboxylic acid compound volatilizing before the sintering temperature is reached, thereby preventing insufficient promotion of sintering of the metal particles.

[0109] The metal paste (Y) preferably contains the basic compound (the basic compound contained in the above-mentioned metal paste (X)) and / or the additive (Z) and a salt of the basic compound. The basic compound dissolves the additive (Z) to improve its dispersibility in the metal paste (Y), fully exerting the effect of the additive (Z) in promoting sintering of metal particles and preventing sedimentation of the metal particles. The same applies when the basic compound is contained as a salt of the additive (Z).

[0110] The metal constituting the metal particles includes those exemplified and explained as the metal constituting the metal particles contained in the above-mentioned metal paste (X), and preferred embodiments are also the same as those of the metal particles contained in the above-mentioned metal paste (X). Only one type of the above-mentioned metal particles may be used, or two or more types may be used.

[0111] The additive (Z) is preferably an acid that is solid at room temperature. Examples of the acid that is solid at room temperature include those exemplified and explained as the solid acid for the metal paste (X) described above. The salt of the additive (Z) is preferably the solid acid salt, more preferably a carboxylate, and even more preferably a malonate. The preferred embodiment of the metal paste (Y) is the same as the metal paste (X). Furthermore, the metal paste (Y) is preferably the metal paste (X) described above.

[0112] The content of the metal particles in the metal paste (Y) is preferably 70 to 99 mass %, more preferably 72 to 97 mass %, and even more preferably 80 to 95 mass %, relative to 100 mass % of the total amount of the metal paste (Y).

[0113] The content of additive (Z) in metal paste (Y) is preferably 0.05 to 5 mass%, more preferably 0.08 to 4 mass%, and even more preferably 0.1 to 3 mass%, relative to 100 mass% of the total amount of metal paste (Y). The content of additive (Z) is the total content of additive (Z) and additive (Z) in the salt of additive (Z).

[0114] The content of the basic compound in the metal paste (Y) is preferably 0.05 to 5 mass%, more preferably 0.08 to 4 mass%, and even more preferably 0.1 to 3 mass%, relative to 100 mass% of the total amount of the metal paste (Y). The content of the basic compound is the total content of the basic compound and the basic compound in the salt of the additive (Z).

[0115] When additive (Z) is an acid or carboxylic acid having a phenolic hydroxyl group, the molar ratio of the number of basic functional groups (preferably the number of amine functional groups) of the basic compound to the number of acid functional groups (the number of phenolic hydroxyl groups in the case of an acid having a phenolic hydroxyl group, or the number of carboxylic acid functional groups in the case of a carboxylic acid) of additive (Z) [number of basic functional groups / number of acid functional groups] is preferably 0.05 to 1.5, more preferably 0.08 to 1.0, even more preferably 0.1 to 0.8, and particularly preferably 0.1 to 0.5. When the molar ratio is 0.05 or more (particularly 0.1 or more), additive (Z) is easily homogenized (liquefied, uniformly gelled, etc.), the dispersibility of additive (Z) is good, and sintering is further promoted. When the molar ratio is 1.5 or less (particularly 0.5 or less), the amount of sintering inhibitors is small, and sintering of metal particles is further promoted.

[0116] [Sintered Body] A sintered body (metal particle sintered body) can be formed by sintering (firing) a metal paste such as the metal paste (X) or the metal paste (Y). The sintered body can be produced, for example, by depositing the metal paste on a substrate, drying the metal paste to form a metal particle aggregate, and then sintering the metal particle aggregate. Note that, in this specification, both the metal paste (X) and the metal paste (Y) are referred to as "metal pastes." Also, in this specification, a sheet-like product in which the metal particles contained in the metal paste are partially sintered may be referred to as a "dried body." Also, in this specification, a product in which most of the organic solvent in the metal paste is volatilized at a temperature at which the organic solvent contained in the metal paste volatilizes, leaving behind the solid acid and basic compounds and / or solid acid salts contained in the metal paste, may be referred to as a "semi-dried body." Also, in this specification, the term "metal particle aggregate" is used to encompass both "dried body" and "semi-dried body."

[0117] As the substrate (substrate), for example, a known or commonly used one can be used. The substrate may be a conductive substrate, a non-conductive substrate, or a dielectric substrate. The substrate may be a single layer or a multi-layer structure in which multiple layers are laminated.

[0118] Examples of materials for forming the non-conductive substrate include resins, glass, ceramics, wood, paper, etc. Examples of the resins include heat-resistant plastics such as polyimide resins, polycarbonate resins, isocyanate resins, melamine resins, and glass epoxy resins, as well as polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), resins with low heat resistance such as polyolefin resins such as polyethylene and polypropylene, polychlorinated biphenyl (PCB), liquid crystal polymers (LCP), vinyl chloride, mold resins, epoxy resins, acrylic resins, epoxy resins, phenolic resins, and polyamide resins, and combinations thereof may also be used.

[0119] Examples of the conductive substrate include metal substrates such as metal foils and metal plates formed from metals (copper, iron, alloys thereof, etc.); carbon substrates such as carbon cloth, carbon paper, and graphite; composite substrates such as conductive particle-containing films, conductive fiber-containing films, metal mesh films, metal-plated films, and optical laminates having a transparent conductive layer; resin substrates such as conductive polymer films; metal wire-containing films; and metal film laminates (printed circuit boards, etc.) having a metal (silver, copper, etc.) film on a part or all of a non-conductive substrate, and combinations of these may also be used.

[0120] Examples of the substrate include semiconductor elements such as resin films, IGBTs, diodes, Schottky barrier diodes, MOS-FETs, thyristors, logic circuits, sensors, analog integrated circuits, LEDs, semiconductor lasers, and oscillators; lead frames, metal plate-attached ceramic substrates (for example, DBC), piezoelectric materials (for example, inorganic materials such as quartz, zinc oxide, and lead zirconate titanate, and organic materials such as polylactic acid), transparent conductive films, semiconductor packages, and LED packages; power supply members such as copper ribbons, metal blocks, and terminals; heat sinks; water-cooled plates; lenses for eyeglasses and sunglasses; glass (automotive glass such as windshields, side windows, and rear windows of automobiles); sensor covers; thermal transfer rollers; printed circuit boards; vias in printed circuit boards; displays of personal computers, televisions, and the like; convex mirrors; traffic lights; smartphones; wearable devices such as watches and earphones; writing implements; glass slides; and office automation equipment such as mice.

[0121] A receiving layer may be formed on the side of the substrate to which the metal paste is applied. Examples of the receiving layer include a coating layer such as a primer layer, an easy-adhesion treatment layer, a hard coat layer, and a release layer.

[0122] The thickness of the receptor layer may be appropriately determined depending on the intended use, and is, for example, 1 nm to 50 μm, preferably 10 nm to 10 μm, and more preferably 100 nm to 1 μm.

[0123] The method for applying the metal paste is not particularly limited, and any known or commonly used application method can be used, such as spin coating, inkjet printing, screen printing, spray printing, dispense printing, relief printing (flexographic printing), dye-sublimation printing, offset printing, laser printer printing (toner printing), intaglio printing (gravure printing), contact printing, microcontact printing, ultra precise deposition (UPD), electrohydrodynamic printing (EHD printing), laser induced forward transfer (LIFT), aerosol jet printing, etc. Only one of the above application methods may be used, or two or more may be used in combination.

[0124] The heating for drying the metal paste can be carried out at a temperature ranging from, for example, 50 to 250°C, preferably from 80 to 220°C, and more preferably from 100 to 200°C. The heating time is, for example, from 1 minute to 1 hour, preferably from 2 to 30 minutes, and more preferably from 3 to 15 minutes. The heating can be carried out in the air, in an inert atmosphere (such as a nitrogen, helium, or argon atmosphere), or in a reducing atmosphere (such as a formic acid gas or hydrogen gas atmosphere).

[0125] A sintered body (metal particle sintered body) can be obtained by sintering the metal particle aggregate. The sintering of the metal particle aggregate can be carried out at a temperature range of, for example, 100°C or higher, preferably 120°C or higher, more preferably 140°C or higher, even more preferably 180°C or higher, and particularly preferably 200°C or higher. The temperature is, for example, 300°C or lower, preferably 250°C or lower, and may be 220°C or lower. The heating time is, for example, 10 minutes to 3 hours, preferably 15 minutes to 2 hours, and more preferably 20 minutes to 1 hour. Since the metal paste can be sintered at low temperatures, when a resin film is used as the substrate, a sintered layer can be obtained by heating at a temperature of 140°C or higher for 1 minute or more (preferably 10 minutes or more). The heating can be carried out in air, inert atmosphere (such as nitrogen, helium, or argon), or reducing atmosphere (such as formic acid gas or hydrogen gas).

[0126] The sintering method includes thermal firing (IH, etc.), light firing (UV, IR irradiation, etc.), reduced pressure firing, etc. The firing methods may be used alone or in combination of two or more.

[0127] The metal particle aggregate can be used for semiconductor bonding, wire bonding, clip bonding, forming wiring on wiring boards, forming multilayer printed wiring boards, forming bumps, bonding between bumps, etc., and can be suitably used in the manufacture of electronic devices (printed electronic devices (printed wiring boards, capacitors, inductors, varistors, thermistors, transistors, speakers, actuators, antennas, solid oxide fuel cells, hybrid ICs, etc.)), rotating electric machines, etc. In particular, the metal particle aggregate can be suitably used in the manufacture of semiconductor devices and rotating electric machines that require excellent bonding properties over a large area, and bonding between substrates and heat sinks, for example, bonding between an insulating substrate and a heat sink of a power semiconductor, because the generation of voids due to decomposition gases is suppressed and the metal particle aggregate has suitable strength.

[0128] The volume resistivity of the sintered body obtained by sintering a 25 μm thick film of the metal paste is preferably 80 μΩ cm or less, more preferably 40 μΩ cm or less, even more preferably 30 μΩ cm or less, and particularly preferably 20 μΩ cm or less, from the viewpoint of excellent conductivity.

[0129] [Method for Manufacturing a Bonded Body] The present disclosure also provides a method for manufacturing a bonded body in which the bodies to be bonded are bonded via a metal particle sintered body or a metal.

[0130] The object to be joined is not particularly limited as long as it can be joined by the metal particle sintered body, and examples thereof include electric / electronic components such as semiconductor chips (discrete semiconductors such as capacitors, transistors, diodes (power diodes), MOS FETs, and IGBTs, and integrated circuits such as ICs and LSIs), heat sinks, and bus bars, connectors, and harnesses for in-vehicle components.

[0131] The bonded body can be applied to, for example, electric and electronic devices such as electromagnetic wave control materials, circuit boards, antennas, heat sinks, liquid crystal displays, organic EL displays, field emission displays (FEDs), IC cards, IC tags, solar cells, LED elements, piezoelectric elements, heaters, organic transistors, condensers (capacitors), electronic paper, flexible batteries, flexible sensors, membrane switches, touch panels, electromagnetic wave shields, etc. For example, by using a semiconductor chip as the bonded body, a semiconductor device can be manufactured as the bonded body.

[0132] (1) First Aspect The first aspect of the method for producing a bonded body is a method for producing a bonded body in which a base material and a workpiece are bonded via a metal particle sintered body, and includes at least a semi-drying step of semi-drying a metal paste containing metal particles on the base material to form a semi-dried body, and a sintering step of sintering the semi-dried body to form a sintered layer. According to the first aspect, by placing the workpieces on the semi-dried body and sintering it, the base material and the workpieces can be bonded with high adhesion via the sintered layer. In the first aspect, the bonded body includes a base material, a workpiece, and a sintered body that bonds the base material and the workpiece. The sintered body is in contact with the base material and the workpiece.

[0133] The metal paste contains metal particles. Known or commonly used conductive metals can be used as the metal constituting the metal particles, such as gold, silver, copper, nickel, palladium, tin, aluminum, or alloys thereof. Among these, silver is preferred because it allows for the production of sintered bodies with high conductivity. In other words, the metal particles are preferably silver particles. Only one type of metal particle may be used, or two or more types may be used.

[0134] The metal paste in the first aspect further contains the solid acid and the basic compound, and / or the solid acid salt. A preferred embodiment of the metal paste in the first aspect is the same as the metal paste (X). In addition, the metal paste in the first aspect is preferably the metal paste (X).

[0135] (Adhesion step) The first aspect may include an adhesion step of adhering the metal paste onto a substrate. The substrate may be any of those exemplified and described as the substrate on which the sintered body is formed. The receiving layer may be formed on the side of the substrate to which the metal paste is adhered. The method for adhering the metal paste is not particularly limited, and any of the methods exemplified and described as the method for adhering the metal paste above may be used.

[0136] (Semi-drying step) In the semi-drying step, the metal paste formed on the base material is semi-dried to form a semi-dried body. By semi-drying, for example, an organic solvent is volatilized to obtain a semi-dried body in which the solid acid and basic compound, and / or solid acid salt contained in the metal paste remains. When a bonded body is stacked on the semi-dried body and the semi-dried body is sintered, sintering of the metal particles is promoted.

[0137] The heating during the semi-drying is preferably carried out at a temperature of 130°C or lower, more preferably 125°C or lower, and even more preferably 120°C or lower. The temperature is, for example, 80°C or higher. The heating time is, for example, 30 seconds to 1 hour, preferably 1 minute to 30 minutes, and more preferably 1 minute to 10 minutes. The heating may be carried out in the air or in an inert atmosphere (such as a nitrogen, helium, or argon atmosphere), or in a reducing atmosphere (such as a formic acid gas or hydrogen gas atmosphere).

[0138] (Joined Body Placement Step) It is preferable to include a bonded body placement step of placing the bonded body on the semi-dried body after the semi-drying step. The bonded body may be placed by, for example, applying a load from above the bonded body at room temperature to bring the bonded body and the semi-dried body into close contact with each other, or by applying a load from above the bonded body in a heated state to bring the bonded body and the semi-dried body into close contact with each other. Alternatively, an adhesive organic substance may be applied to the top of the semi-dried body, and the bonded body may be placed on top of the semi-dried body to bring the bonded body and the semi-dried body into close contact with each other.

[0139] (Sintering Step) In the sintering step, the semi-dried body is sintered to form a sintered layer (metal particle sintered body). The sintering is preferably performed by heating at a temperature of 150°C or higher while applying a pressure of 1 MPa or higher from the side of the bonded body. The pressure is more preferably 5 MPa or higher. The pressure is, for example, 20 MPa or lower. The temperature is more preferably 200°C or higher. The temperature is, for example, 300°C or lower. The sintering may be performed in air, in an inert atmosphere (such as nitrogen, helium, or argon), or in a reducing atmosphere (such as formic acid gas or hydrogen gas). The sintering method is not particularly limited, and the methods exemplified and explained above as methods for sintering metal particle aggregates can be used.

[0140] (2) Second Aspect A second aspect of the method for producing a bonded body is a method for producing a bonded body in which a bonded body is bonded to a metal, and includes at least a coating step of coating the metal bonding composition on a substrate. According to the second aspect, the composition functions as a tacking agent, and the substrate and the bonded body can be bonded with high adhesion via a sintered layer. In the second aspect, the bonded body includes a bonded body and a metal. The metal is in contact with the bonded body.

[0141] In the second aspect, the metal is preferably a dried or sintered body of a metal paste containing metal particles on a substrate. The substrate can be any of those exemplified and described as substrates on which the sintered body is formed. The metal particles can be any of those exemplified and described as metal particles in the first aspect.

[0142] The metal paste in the second aspect preferably further contains the solid acid and the basic compound, and / or the solid acid salt. A preferred embodiment of the metal paste in the second aspect is the same as the metal paste (X). In addition, the metal paste in the second aspect is preferably the metal paste (X).

[0143] (Adhesion step) The second aspect may include an adhesion step of adhering the metal paste onto a substrate. The substrate may be any of those exemplified and described as the substrate on which the sintered body is formed. The receiving layer may be formed on the side of the substrate to which the metal paste is adhered. The method for adhering the metal paste is not particularly limited, and any of the methods exemplified and described as the method for adhering the metal paste above may be used.

[0144] (Drying Step) The second aspect may include a drying step of drying the metal paste attached to the substrate to form a dried body. The drying can volatilize, for example, the organic solvent. The drying conditions may be the same as those exemplified and described as the conditions for drying the metal paste.

[0145] (Coating Step) In the coating step, the composition for metal bonding is coated onto the dried body. The composition for metal bonding may contain the solid acid salt.

[0146] The method for applying the composition in the application step is not particularly limited, and any known or commonly used application method can be used, such as spin coating, inkjet printing, screen printing, dispenser printing, relief printing (flexographic printing), dye-sublimation printing, offset printing, laser printer printing (toner printing), intaglio printing (gravure printing), contact printing, and microcontact printing.

[0147] (Bonded Body Arranging Step) After the coating step, it is preferable to include a bonded body arranging step of arranging the bonded body on the coated dried body.

[0148] (Sintering Step) The second aspect preferably includes a sintering step of sintering the dried body to form a sintered layer (metal particle sintered body). The sintering is preferably performed by heating at a temperature of 150°C or higher while applying a pressure of 1 MPa or higher from the side of the bonded body. The pressure is more preferably 5 MPa or higher. The pressure is, for example, 20 MPa or lower. The temperature is more preferably 200°C or higher. The temperature is, for example, 300°C or lower. The sintering may be performed in air, in an inert atmosphere (such as nitrogen, helium, or argon), or in a reducing atmosphere (such as formic acid gas or hydrogen gas). The sintering method is not particularly limited, and the methods exemplified and described above as methods for sintering metal particle aggregates can be used.

[0149] (3) Third Aspect A third aspect of the method for producing the bonded body includes at least a sintered body placement step of placing a sintered body on a base material, a bonded body placement step of placing a bonded body on the sintered body, and a resintering step of further heating and resintering the sintered body. According to the third aspect, the sintered body placement step of placing a previously obtained sintered body is included instead of the metal paste application step, thereby simplifying the process and reducing waste (loss) of metal paste in the application step. In the third aspect, the bonded body includes a base material, a bonded body, and a resintered body (metal particle sintered body) that bonds the base material and the bonded body. The resintered body is in contact with the base material and the bonded body.

[0150] In the third embodiment, the substrate may be any of those exemplified and explained as substrates on which the sintered body can be formed.

[0151] In the third aspect, the sintered body is a metal particle sintered body obtained by heating a metal paste in an air atmosphere or an inert atmosphere at a temperature of 100°C to 300°C, or a metal particle sintered body obtained by adhering a metal paste onto a resin film and heating it at a temperature of 140°C or higher for 1 minute or more.

[0152] The metal paste contains metal particles, and as the metal particles, those exemplified and explained as the metal particles in the first embodiment can be used.

[0153] The metal paste in the third aspect preferably further contains the solid acid and the basic compound, and / or the solid acid salt. A preferred embodiment of the metal paste in the third aspect is the same as the metal paste (X). In addition, the metal paste in the third aspect is preferably the metal paste (X).

[0154] (Peeling process) In the third aspect, when a metal particle sintered body obtained by adhering a metal paste onto a resin film and heating it at a temperature of 140°C or higher for 1 minute or more is used as the sintered body, it is preferable to include a peeling process of peeling the resin film from the sintered body before the sintered body placement process.

[0155] (Sintered Body Arranging Step) In the sintered body arranging step, the sintered body is arranged on the base material.

[0156] (Bonded Body Arranging Step) In the bonded body arranging step, the bonded body is arranged on the sintered body.

[0157] (Resintering Step) In the resintering step, the sintered body is further heated and resintered, thereby bonding the base material and the bonded body via a sintered layer (metal particle sintered body). The resintering is preferably performed by heating at a temperature of 150°C or higher while applying a pressure of 1 MPa or higher from the bonded body side. The resintering is also preferably performed at a temperature higher than the temperature at which the sintered body is produced. The pressure is more preferably 5 MPa or higher. The pressure is, for example, 20 MPa or lower. The temperature is more preferably 200°C or higher. The temperature is, for example, 300°C or lower. The resintering may be performed in air, in an inert atmosphere (such as nitrogen, helium, or argon), or in a reducing atmosphere (such as formic acid gas or hydrogen gas). The resintering method is not particularly limited, and the methods exemplified and described above as methods for sintering metal particle aggregates can be used.

[0158] In this manner, the bonded body of the present disclosure can be produced.

[0159] The metal pastes (metal paste (X) and metal paste (Y)) of the present disclosure enable sintering at relatively low temperatures, even when nano-sized as well as submicron-sized metal particles are used. Furthermore, the method for producing a joined body of the present disclosure enables production by sintering at a relatively low temperature and in a short time (for example, within one minute), even when nano-sized as well as submicron-sized metal particles are used.

[0160] Each aspect disclosed in this specification can be combined with any other feature disclosed in this specification. Each configuration and combination thereof in each embodiment is an example, and addition, omission, substitution, and other modifications of configurations are possible as appropriate within the scope of the spirit of this disclosure. Furthermore, each invention according to this disclosure is not limited by the embodiments or the following examples.

[0161] An embodiment of the present disclosure will be described in more detail below based on examples. The metal particles, basic compounds, solvents, and resins used in the examples are as follows. The average particle size (median size) of the metal particles is the volume average particle size measured by laser diffraction / scattering or the like.

[0162] <Metal particles> Ag-2-8F: trade name "Ag-2-8F", manufactured by DOWA Electronics Co., Ltd., spherical silver particles, average particle diameter 0.9 μm AgC-239: trade name "Silcoat AgC-239", manufactured by Fukuda Metal Foil & Powder Co., Ltd., flake silver particles, average particle diameter 3 μm

[0163] <Acids> Malonic acid: Reagent manufactured by Fujifilm Wako Pure Chemical Corporation, melting point / decomposition temperature 135°C Oxalic acid: Reagent manufactured by Fujifilm Wako Pure Chemical Corporation, melting point / decomposition temperature 190°C DL-Tartaric acid: Reagent manufactured by Fujifilm Wako Pure Chemical Corporation, melting point 210°C Citric acid: Reagent manufactured by Fujifilm Wako Pure Chemical Corporation, melting point 175°C Formic acid: Reagent manufactured by Fujifilm Wako Pure Chemical Corporation Acetic acid: Reagent manufactured by Fujifilm Wako Pure Chemical Corporation n-Octanoic acid: Reagent manufactured by Tokyo Chemical Industry Co., Ltd. Lactic acid: Reagent manufactured by Tokyo Chemical Industry Co., Ltd. 4-Ethoxyphenol: Reagent manufactured by Tokyo Chemical Industry Co., Ltd., melting point 65°C

[0164] <Basic compounds> DMDA: N,N-dimethyldecylamine, reagent manufactured by Tokyo Chemical Industry Co., Ltd., boiling point 235°C PMDTA: N,N,N',N",N"-pentamethyldiethylenetriamine, reagent manufactured by Tokyo Chemical Industry Co., Ltd., boiling point approximately 200°C TMDAH: N,N,N',N'-tetramethyl-1,6-hexanediamine, reagent manufactured by Tokyo Chemical Industry Co., Ltd., boiling point approximately 210°C MDEtA: N-methyldiethanolamine, reagent manufactured by Tokyo Chemical Industry Co., Ltd., boiling point 247°C DMAPOH: 1-dimethylamino-2-propanol, reagent manufactured by Tokyo Chemical Industry Co., Ltd., boiling point 125°C TEtA: 2,2',2"-nitrilotriethanol, reagent manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., boiling point approximately 360°C TEA: Triethylamine, Fujifilm Wako Pure Chemical Industries, Ltd., boiling point 89°C TAmiA: Triamylamine, Tokyo Chemical Industry Co., Ltd., boiling point 240°C DCMA: N,N-dicyclohexylmethylamine, Tokyo Chemical Industry Co., Ltd., boiling point 150°C / 20mmHg

[0165] <Organic solvents> EG: ethylene glycol, reagent manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., boiling point 197°C 1,3-BG: 1,3-butylene glycol, manufactured by Daicel Corporation, boiling point 207°C MMPG: propylene glycol monomethyl ether, manufactured by Daicel Corporation, boiling point 121°C DEE: diethylene glycol monoethyl ether, reagent manufactured by Tokyo Chemical Industry Co., Ltd., boiling point 196°C DPNP: dipropylene glycol monopropyl ether (mixture of isomers), manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., boiling point approximately 210°C α-terpineol: reagent manufactured by Tokyo Chemical Industry Co., Ltd., boiling point 218°C DBC: diethylene glycol dibutyl ether, reagent manufactured by Tokyo Chemical Industry Co., Ltd., boiling point 255°C DHTP: dihydroterpineol, manufactured by Yasuhara Chemical Co., Ltd., boiling point 210°C TECit: triethyl citrate, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., boiling point 294°C TPM: tripropylene glycol monomethyl ether, a reagent manufactured by Tokyo Chemical Industry Co., Ltd., boiling point 243°C

[0166] <Resin> EC: Ethyl cellulose, product name "ETHOCEL STD 300 cps", manufactured by Nisshin Seiki Co., Ltd.

[0167] Example 1 (Preparation of Mixture) 2 g of the solid acid shown in Table 1 and a basic compound in the mass ratio shown in Table 1 were weighed into a 50 cc screw tube, and the mixture was stirred at 60°C on a hot stirrer until homogenized. In addition, for mixtures that precipitated solids and did not become homogenously liquefied, they were treated as solids after approximately 1 hour of heating / stirring. In this manner, the mixtures of Preparation Examples 1 to 17 were prepared.

[0168] (Viscosity) The viscosity was measured using a rheometer (trade name "MCR302", manufactured by Anton Paar) with a PP25 measuring jig, a measuring temperature of 25°C, a gap of 0.1 mm, and a rotation speed of 100 s －１ The viscosity of the mixture was measured by reading the viscosity value after rotating the plate for 10 minutes under the above conditions. The results are shown in Table 1.

[0169]

[0170] In Preparation Example 1, malonic acid was mixed with DMDA, an alkylamine having a long-chain alkyl group, so that the molar ratio of [amine functional group number / acid functional group number] was 0.25. The mixture was rotated at a speed of 100 s －１ The mixture became a homogeneous liquid with a viscosity of 1.5 Pa·s at 60°C, 50°C, 40°C, and 30°C.

[0171] In Preparation Example 2, DMDA was mixed with malonic acid at a molar ratio of 0.28 (amine functionality / acid functionality). The mixture was a homogeneous liquid with a viscosity of 1.3 Pa s, which was expected to be advantageous for dispersing metal particles. The mixture also remained homogeneous at temperatures of 60°C, 50°C, 40°C, and 30°C.

[0172] In Preparation Example 3, DMDA was mixed with malonic acid so that the molar ratio of [number of amine functional groups / number of carboxylic acid functional groups] was 0.30. The mixture became a homogeneous liquid when heated at 60°C, but a white solid precipitated in the liquid during the process of returning to room temperature, and the mixture did not become a homogeneous liquid at room temperature but became a slurry.

[0173] In Preparation Examples 4 and 5, the amount of DMDA was further increased to achieve molar ratios of 0.42 and 0.90. As the amount of amine was increased, significant white solid precipitation occurred in the mixture. This indicates that as the number of moles of amine increased, the mixture became a salt of the amine and carboxylic acid, making it difficult to handle as a liquid. Both mixtures became homogeneous liquids when heated to 60°C.

[0174] In Preparation Example 6, DMDA was mixed with malonic acid at a molar ratio of 0.20 (amine functionality / acid functionality). A small amount of white solid remained in the solution. This is thought to be because the malonic acid, which is solid, remained undissolved and did not liquefy when the amine content was low. Furthermore, the mixture did not become a homogeneous liquid even when heated to 60°C.

[0175] To confirm the results when mixed with amines other than DMDA, TMDAH was used in Preparation Example 8, MDEtA in Preparation Example 10, DMAPOH in Preparation Example 11, and TEtA in Preparation Example 13, each at a molar ratio of 0.28. All of these mixtures were in a homogeneous liquid state, similar to DMDA. Furthermore, all of the mixtures were in a homogeneous liquid state at 60°C, 50°C, 40°C, and 30°C.

[0176] In Preparation Example 7, trifunctional amine PMDTA was mixed at a molar ratio of 0.28. In the case of amines with a large number of functional groups, a white solid precipitated and the mixture did not liquefy, which made the mixture difficult to handle and difficult to blend. Furthermore, the mixture did not become a uniform liquid even when heated to 60°C.

[0177] In Preparation Example 9, TMDAH was mixed to a molar ratio of 0.50. When the amount of TMDAH added was increased, the liquid became a two-phase system and separated, failing to become a homogeneous liquid. Furthermore, the mixture did not become a homogeneous liquid even when heated to 60°C.

[0178] In Preparation Example 12, DMAPOH was mixed in at a molar ratio of 0.90. In the case of an alkanolamine such as DMAPOH, it was possible to handle it in a liquid state even when the molar ratio was increased.

[0179] DCMA was blended in Preparation Example 14, and TAmiA was blended in Preparation Example 15 so that the molar ratio to citric acid was 0.16. The mixture in Preparation Example 14 became a homogeneous liquid at 60°C, 50°C, 40°C, 30°C, and 25°C. The mixture in Preparation Example 15 became a homogeneous liquid at 60°C, 50°C, and 40°C.

[0180] In Preparation Example 16, DCMA was blended at a molar ratio of 0.26 to 4-ethoxyphenol. The mixture became a homogeneous liquid at 60°C, 50°C, 40°C, 30°C, and 25°C.

[0181] In Preparation Example 17, malonic acid and oxalic acid were used as the solid acids in a mixing ratio of 1:1, and DCMA was added to the carboxylic acid in a molar ratio of 0.11. The mixture became a homogeneous liquid at 60°C, 50°C, and 40°C.

[0182] As described above, the solid acid and the basic compound are liquefied at a specific molar ratio, and such a mixture of the solid acid and the basic compound in a liquid state is easy to blend with metal particles and has been evaluated as having superior dispersibility when made into a paste.

[0183] Example 2 (Preparation of Dispersion Solvent) A mixture prepared in the same manner as in Preparation Example 1 was weighed into a 9 cc screw tube so that the solid acid amount was 200 mg. 2 g of organic solvent was then weighed into the screw tube, and the mixture was dissolved in the solvent by heating and stirring on a hot plate at 60 ° C. In this manner, the dispersion solvents of Preparation Examples 18 to 32 were prepared.

[0184] (Uniform solubility) After storing the dispersion solvent at 25°C for one day, the state of solid precipitation and liquid phase separation was visually confirmed, and a case where a mixture of malonic acid and a basic compound was clearly precipitated or separated was rated as ×, a case where the liquid became turbid in a suspended state was rated as △, and a case where no solid precipitation or precipitation or separation of the mixture at the bottom of the container was observed even when left standing or stirred was rated as ◯. The results are shown in Table 2.

[0185] (Method of calculating SP value) The SP values ​​shown in Table 2 were calculated using HSPiP (ver. 5.4) (Hansen Solubility Parameter in Practice) software, and the unit is (cal / cm ３ ) （１／２） The value calculated in was adopted.

[0186]

[0187] In Preparation Examples 18 to 23, malonic acid and DMDA were mixed in the molar ratios shown in Table 2, and solutions were prepared by mixing 1 part malonic acid with 10 parts organic solvent. Table 2 shows the state of the above solutions in the "Uniform Solubility" column. Mixtures of malonic acid and basic compounds using DMDA with a long-chain alkyl group have high affinity with low-polarity organic solvents, and by adjusting the molar ratio, they can be uniformly mixed with terpene-based solvents and ether-based solvents such as α-terpineol and DPNP, which are commonly used as dispersion solvents for metal pastes. Furthermore, DBC, a low-polarity ether-based solvent with alkyl chains at both ends and no hydroxyl groups, could also be made into a uniform solution by mixing it with other solvents such as DPNP. Furthermore, in Preparation Example 23, using an amine with a long-chain alkyl group such as DMDA, even at a molar ratio of 0.90, which solidifies, it can be handled as a solvent in a uniform liquid state by diluting it with a solvent.

[0188] In Preparation Examples 24 to 31, mixtures of malonic acid and basic compounds were prepared in the same manner as in Preparation Examples 18 to 23, using various amines in the respective molar ratios shown in Table 2, and the homogeneous solubility of these mixtures in organic solvents was confirmed. Only Preparation Example 25, which was prepared using PMDTA, was unable to achieve homogeneous dissolution in all organic solvents, but other liquefied mixtures of malonic acid and basic compounds could be homogenized in solvents with moderate polarity, such as MMPG and DEE.

[0189] In Preparation Example 32, a mixture of malonic acid and a basic compound mixed with TEtA at a molar ratio of 0.90 was diluted with a solvent. When mixed with TEtA at a molar ratio of 0.90, the mixture was homogeneously dissolved only in highly polar polyfunctional alcohol solvents such as EG and 1,3-BG, but was unable to be homogenized with solvents having a relatively low SP value, for example, an SP value of 12 or less.

[0190] As a reference example, the solubility of malonic acid alone in organic solvents is also shown. Malonic acid alone has a relatively high solubility in organic solvents and was also soluble in organic solvents such as DPNP. Although a mixture of malonic acid and a basic compound is liquid, due to the association of the acid and base, it is thought that this is because it has stronger ionicity than the single substance and may be inferior in terms of uniform solubility in organic solvents. On the other hand, as will be shown in detail in the examples below, a solvent in which a component that is solid at room temperature, such as malonic acid alone, is dissolved in an organic solvent results in poor dispersibility when used as a dispersion solvent for metal particles, making it unsuitable for use as a dispersion solvent for metal pastes.

[0191] Example 3 (Preparation of Metal Paste) An acid (solid acid or acid other than solid acid) and a basic compound were mixed in the compounding ratios shown in Tables 3 and 4 to prepare metal pastes of Preparation Examples 33 to 70.

[0192] (Viscosity) Using a rheometer (trade name "MCR302", manufactured by Anton Paar), the viscosity was measured at a measurement jig of PP25, a measurement temperature of 25°C, a gap of 0.2 mm, and a rotation speed of 10 s －１ The viscosity of the metal paste was measured by reading the viscosity value after rotating the plate for 10 minutes under the conditions above. The results are shown in Tables 3 and 4. If the viscosity exceeded 500 Pa s or could not be measured, it was marked "X."

[0193] (Conductivity) The prepared metal paste was applied with a squeegee to a glass slide masked on all four sides with masking tape (polyester film adhesive tape, product name "631U #12", manufactured by Teraoka Seisakusho Co., Ltd.) to form a 25 μm-thick film of the metal paste. The film was then placed on a hot plate preheated to 150°C (180°C in Preparation Examples 67-69) and heated in air for 30 minutes to obtain a metal sintered body. The volume resistivity of this sintered body was measured using a resistivity meter (product name "Loresta GP MCP-T610", manufactured by Nitto Seiko Analytech Co., Ltd.) to evaluate its conductivity. The results are shown in Tables 3 and 4. Cases where a measurable sintered body could not be obtained were marked "X."

[0194]

[0195]

[0196] As shown in Table 3, in Preparation Examples 33 to 35, the metal pastes containing malonic acid and a basic compound had viscosities suitable for printing, and the viscosity could be adjusted by changing the amount of organic solvent. Furthermore, the volume resistivity of the sintered body was 20 μΩ cm or less, indicating high conductivity.

[0197] In Preparation Examples 36 to 38, pastes were made using DHTP, a terpene solvent, or DBC, an ether solvent with alkyl chains at both ends. These Preparation Examples also had good viscosity characteristics and high conductivity.

[0198] In Preparation Examples 39 to 41, pastes were made by varying the amount of amine, a basic compound. Pastes could be made from a molar ratio of 0.1 to malonic acid, and excellent conductivity was also obtained. Pastes could also be made from a molar ratio of 1 or more to malonic acid, and excellent conductivity was also obtained. However, from the standpoints of toxicity, sintering inhibition, and organic residues, the incorporation of excessive basic substances is undesirable, and a molar ratio of up to about 1 to malonic acid is considered appropriate.

[0199] In Preparation Example 42, ethyl cellulose was blended as a thixotropy-imparting agent to form a paste. As intended, it was possible to adjust the viscosity of the paste, and even when a resin was blended, it was possible to obtain good conductivity.

[0200] The ratio of silver particles was changed to prepare pastes in Preparation Examples 43 and 44. In all of the pastes, pastes with good viscosity characteristics were obtained, and the sintered bodies also had good electrical conductivity.

[0201] Metal pastes were prepared using DMAPOH as the basic compound instead of DMDA in Preparation Examples 45 and 46. In all of the pastes, pastes with good viscosity characteristics were obtained, and the sintered bodies also had good electrical conductivity.

[0202] As shown in Table 3, pastes were prepared by varying the blending amount of malonic acid from 0.1 to 2 parts by mass in Preparation Examples 47 to 50. In all cases, pastes with good viscosity characteristics were obtained, and the sintered bodies also had good electrical conductivity.

[0203] In Preparation Example 51, a paste was prepared using MMPG, a low-boiling point solvent. There were no problems with the paste properties, but the viscosity was difficult to measure because it dried very quickly and increased during viscosity measurement. The paste dried quickly and had good conductivity as a sintered body.

[0204] A paste was prepared using EG, a highly polar solvent, in Preparation Examples 52 and 53. The paste using EG had high viscosity, and when DMAPOH, which has high polarity, was used as the basic compound, the paste became clayey and was difficult to prepare, but the conductivity of the sintered body was good.

[0205] In Preparation Example 54, a paste was prepared using TEtA as the basic compound. A sintered body having a certain degree of conductivity was formed, but because TEtA has a high boiling point and poor drying properties, the conductivity of the sintered body was inferior to that of the other Preparation Examples.

[0206] In Preparation Example 55, a paste was prepared using TECit as the high-boiling point solvent. Although a sintered body with a certain degree of conductivity was formed, TECit also had a high boiling point and poor drying properties, resulting in a lower conductivity than the other Preparation Examples.

[0207] Pastes were prepared without blending malonic acid in Preparation Examples 56 and 57. Even after heating the paste at 150°C, the film of the sintered body remained in a powdery state, and sintering did not progress, making it impossible to measure the electrical conductivity.

[0208] In Preparation Examples 58 to 64, metal pastes were prepared by blending carboxylic acids other than malonic acid, and sinterability was evaluated. Although samples with measurable resistance were obtained using low-molecular-weight carboxylic acids such as acetic acid and lactic acid, the resistance values ​​were 100 μΩ cm or higher, which was inferior to the results of other preparation examples blended with malonic acid. Furthermore, no samples with measurable resistance were obtained using carboxylic acids other than acetic acid and lactic acid, and conductivity could not be measured.

[0209] In Preparation Examples 65 and 66, no basic compound was added, and only malonic acid was dissolved in an organic solvent, and a metal paste was prepared using that solvent. In Preparation Example 65, the metal paste became clay-like, and in the absence of a basic compound, the dispersibility was poor. In Preparation Example 66, in which the amount of organic solvent was increased to form a paste, a sintered body was prepared in the same manner as in the other Preparation Examples, and the resistance value was measured. However, sintering did not progress as in the other Preparation Examples, and the resistance value was high.

[0210] In Preparation Examples 67 and 68, citric acid was added as a solid acid, and metal pastes were prepared by changing the basic compound and its molar ratio from that in Preparation Example 60. The resulting sintered bodies all had good electrical conductivity.

[0211] In Preparation Example 69, 4-ethoxyphenol was blended as the solid acid to prepare a metal paste. The resulting sintered body had good electrical conductivity.

[0212] In Preparation Example 70, a metal paste was prepared by mixing malonic acid and oxalic acid in a mixing ratio of 1:1. The resulting sintered body had good electrical conductivity.

[0213] Figures 1 to 4 show SEM images of sintered bodies made using the metal pastes of Preparation Example 36, which used malonic acid, and Preparation Examples 62 to 64, which used other acids. As shown in Figure 1, in the sintered body made using the metal paste with malonic acid (Preparation Example 36), necking between metal particles was observed to be progressing well. This resulted in high electrical conductivity. On the other hand, as shown in Figures 2 and 4, in the sintered bodies made using the metal pastes with carboxylic acids such as acetic acid and lactic acid (Preparation Examples 62 and 64), although there was a tendency for the metal particles to aggregate, no clear formation of necking was observed. Furthermore, as shown in Figure 3, in the sintered body made using the metal paste with n-octanoic acid (Preparation Example 63), no tendency for the metal particles to aggregate or necking was observed at all.

[0214] Example 4 The metal paste prepared in Preparation Example 36 was sintered at 140°C, 150°C, and 180°C, and the volume resistivity of the sintered body was measured for each sintering time as described above. The volume resistivity was measured in the same manner as in Example 3. The results are shown in Table 5 and Figure 5. As can be seen from the diagram, the metal paste containing malonic acid can be sintered by heating at or above the thermal decomposition temperature of malonic acid, and sintering progresses even in a short time such as one minute in a sufficiently heated environment such as 180°C.

[0215]

[0216] Example 5 [Example of molding a sintered body on a resin] Using the metal paste of Preparation Example 35, a coating film of 200 μm in thickness was formed on a commonly available PEN film using an applicator. The coating film of the metal paste molded on this PEN film was dried on a hot plate at 150°C for 10 minutes to obtain a sintered body. The sintered body had a thickness of approximately 100 μm and could be handled as a sintered body. Since the metal paste containing malonic acid can be sintered at low temperatures in a short time, it is possible to obtain a sintered body on a resin film, enabling applications such as forming metal wiring on a resin film.

[0217] Example 6 [Bonding Application Example 1] A Si chip was bonded to a substrate using the metal paste of Preparation Example 36. The Si chip was a 5 mm square Ag-sputtered Si chip (Si / Ti (50 nm) / Ag (1 μm)). The substrate was a 1 mm thick Cu plate plated with 1 μm thick Ag. A metal mask with a 5 mm square t = 100 μm opening was used to print the metal paste onto the substrate. The printed metal paste was heated on a hot plate at 100°C for 1 minute to dry the metal paste. A Si chip was placed on top of the dried metal paste and heated from room temperature to 200°C at 200 K / min under a pressure of 10 MPa in air. After reaching 200°C, the sample was held for 1 minute. The sample was then cooled to obtain a bonded assembly of the Si chip and substrate. The bond strength of this bonded assembly was measured using a die shear tester, and was found to be 40 MPa or more, demonstrating excellent bond strength. Figure 6 shows a cross-sectional SEM image of this bonded assembly. As can be seen from FIG. 6, no defects such as voids were found inside the bonded body.

[0218] Example 7 [Bonding Application Example 2] The metal paste of Preparation Example 36 was printed on a substrate in the same manner as in Bonding Application Example 1, and then heated at 100°C for 1 minute to dry the metal paste. Then, a mixture (viscous liquid) prepared from malonic acid and TMDAH in Preparation Example 8 was attached to the top of the dried body, and a Si chip was mounted on top of the dried metal paste body. The mixture of malonic acid and a basic compound provided tackiness, allowing the Si chip to be mounted without misalignment relative to the dried body. A bonded body was then obtained under the same conditions as Bonding Application Example 1. Similar to Bonding Application Example 1, a good bonded body with a bond strength of 40 MPa or more was obtained without any particular organic residue.

[0219] Example 8 [Example of Sintering in Nitrogen Atmosphere] The metal paste of Preparation Example 33 was used to evaluate sinterability in a nitrogen atmosphere. Conductivity evaluation was performed in the same manner as in Example 3. The printed metal paste coating was heated from room temperature to 250°C at a rate of 200 K / min in a nitrogen atmosphere, and then heated at 250°C for 5 minutes to obtain a sintered body. The conductivity of the sintered body at this stage was 10 μΩ·cm, demonstrating good conductivity. An SEM image of the sintered body is shown in Figure 7. As can be seen from Figure 7, good necking between the metal particles was observed. It is known that sintering of Ag particles usually proceeds in an atmosphere containing oxygen, but the metal paste containing malonic acid and a basic compound was able to be sintered even in a nitrogen atmosphere.

[0220] Variations of the invention according to the present disclosure are described below. [Appendix 1] A composition for metal bonding, comprising an acid and a basic compound that are solid at room temperature, and / or a salt thereof, wherein the mixture of the acid that is solid at room temperature and the basic compound is in a homogeneous liquid state at 60°C. [Appendix 2] The composition for metal bonding according to Appendices 1, wherein the weight loss (TG) in the range of 100°C to 300°C is 80% or more when measured by simultaneous differential thermal analysis (TG-DTA) under the following measurement conditions. (Measurement Conditions) Using 10 mg of the composition for metal bonding as a measurement sample, the measurement sample is subjected to simultaneous differential thermal analysis (TG-DTA) at a heating rate of 10°C / min, at a measurement temperature range of 30°C to 400°C, in an air furnace atmosphere. [Appendix 3] The composition for metal bonding according to Appendices 1 or 2, wherein the basic compound is a compound represented by the following formula (1): [In formula (1), R ａ ~R ｃ are the same or different and represent a hydrogen atom or a hydrocarbon group which may have a substituent. The substituent may be the same or different and represent an amino group, an N-substituted amino group, an N,N-substituted amino group, an imino group, an N-substituted imino group, or a hydroxy group. ａ ~R ｃ are not hydrogen atoms at the same time. A double line including a dashed line represents a single bond or a double bond. If it is a double bond, R ｃ does not exist. ａ ~Rｃany two of these may be bonded to each other to form a ring together with the adjacent nitrogen atom.] [Appendix 4] The composition for metal bonding according to any one of Appendices 1 to 3, wherein the acid that is solid at room temperature is a carboxylic acid. [Appendix 5] The composition for metal bonding according to any one of Appendices 1 to 4, wherein the acid that is solid at room temperature has a melting point of 50°C or higher. [Appendix 6] The composition for metal bonding according to Appendices 4 or 5, wherein the molar ratio of the number of basic functional groups in the basic compound to the number of carboxylic acid functional groups in the carboxylic acid [number of basic functional groups / number of carboxylic acid functional groups] is 0.05 to 1.5. [Appendix 7] The composition for metal bonding according to any one of Appendices 1 to 6, further comprising an organic solvent. [Appendix 8] The composition for metal bonding according to any one of Appendices 1 to 7, which is a homogeneous liquid at 25°C and has a viscosity of 0.1 to 1,000 Pa s. [Appendix 9] The composition for metal bonding according to Appendices 7 or 8, wherein the boiling points of the basic compound and the organic solvent are 100°C or higher and 300°C or lower, and the organic solvent includes at least one organic solvent having a Hansen solubility parameter SP value of 12 or lower. [Appendix 10] A metal paste comprising the composition for metal bonding according to any one of Appendices 1 to 9 and metal particles. [Appendix 11] The metal paste according to Appendices 10, further comprising a resin, the resin content being greater than 0 mass% and 1 mass% or lower. [Appendix 12] A method for producing a bonded body in which objects to be bonded are joined to a metal, the method comprising a coating step of coating the metal with the composition for metal bonding according to any one of Appendices 1 to 9. [Appendix 13] The method for producing a bonded body according to Appendices 12, wherein the metal is a dried or sintered body of a metal paste containing metal particles, which is on a substrate. [Appendix 14] A method for manufacturing a bonded body according to Appendix 13, comprising, after the coating step, a bonded body arranging step of arranging the bonded body on the coated dried body or the sintered body, and a sintering step of sintering the dried body to form a sintered layer, wherein the sintering step is performed by heating at a temperature of 150°C or higher while applying a pressure of 1 MPa or more from the bonded body side.[Appendix 15] A method for producing a bonded body in which a base material and objects to be bonded are bonded via a metal particle sintered body, the method comprising: a semi-drying step of semi-drying a metal paste on the base material to form a semi-dried body; and a sintering step of sintering the semi-dried body to form the metal particle sintered body, the metal paste being the metal paste described in Appendix 10 or 11. [Appendix 16] A method for producing a bonded body according to Appendix 15, the method comprising: after the semi-drying step, a bonded body arranging step of arranging the objects to be bonded on the semi-dried body, the semi-drying step being performed at a temperature of 130°C or less, and the sintering step being performed by heating at a temperature of 150°C or higher while applying a pressure of 1 MPa or more from the side of the objects to be bonded. [Appendix 17] A method for producing a sintered body, the method comprising heating the metal paste described in Appendix 10 or 11 at a temperature of 100°C to 300°C in an inert atmosphere to obtain a metal particle sintered body. [Appendix 18] A method for producing a sintered body, comprising: depositing the metal paste according to Appendices 10 or 11 on a resin film, and heating the resulting resin film at a temperature of 140°C or higher for one minute or longer to obtain a metal particle sintered body. [Appendix 19] A method for producing a bonded body, comprising: a sintered body arrangement step of arranging the sintered body obtained by the method for producing a sintered body according to Appendices 17 or 18 on a base material; a bonded body arrangement step of arranging a body to be bonded on the sintered body; and a re-sintering step of further heating and sintering the sintered body.

Claims

1. A metal bonding composition comprising an acid and a basic compound that are solid at room temperature, and / or a salt thereof, wherein the mixture of the acid that is solid at room temperature and the basic compound is in a homogeneous liquid state at 60°C.

2. The metal bonding composition according to claim 1, wherein the weight loss (TG) in the range of 100°C to 300°C is 80% or more when a simultaneous differential thermal analysis (TG-DTA) is performed under the following measurement conditions: (Measurement conditions) 10 mg of the metal bonding composition is used as a measurement sample, and the measurement sample is subjected to a simultaneous differential thermal analysis (TG-DTA) at a heating rate of 10°C / min, in a measurement temperature range of 30°C to 400°C, in an air atmosphere in a furnace.

3. The metal bonding composition according to claim 1, wherein the basic compound is a compound represented by the following formula (1): [In formula (1), R ａ ~R ｃ are the same or different and represent a hydrogen atom or a hydrocarbon group which may have a substituent. The substituent may be the same or different and represent an amino group, an N-substituted amino group, an N,N-substituted amino group, an imino group, an N-substituted imino group, or a hydroxy group. ａ ~R ｃ are not hydrogen atoms at the same time. A double line including a dashed line represents a single bond or a double bond. If it is a double bond, R ｃ does not exist. ａ ~R ｃ Any two of these may be bonded to each other to form a ring together with the adjacent nitrogen atom.] 4. The metal bonding composition according to claim 1, wherein the acid that is solid at room temperature is a carboxylic acid.

5. The metal bonding composition according to claim 1, wherein the acid that is solid at room temperature has a melting point of 50°C or higher.

6. The metal bonding composition according to claim 4, wherein the molar ratio of the number of basic functional groups of the basic compound to the number of carboxylic acid functional groups of the carboxylic acid [number of basic functional groups / number of carboxylic acid functional groups] is 0.05 to 1.

5.

7. The metal bonding composition according to claim 1, further comprising an organic solvent.

8. The metal bonding composition according to claim 1, which is a homogeneous liquid at 25°C and has a viscosity of 0.1 to 1000 Pa·s.

9. The metal bonding composition according to claim 7, wherein the boiling points of the basic compound and the organic solvent are 100°C or higher and 300°C or lower, and the organic solvent includes at least one organic solvent having a Hansen solubility parameter SP value of 12 or lower.

10. A metal paste comprising the metal bonding composition according to any one of claims 1 to 9 and metal particles.

11. The metal paste according to claim 10, further comprising a resin, the content of said resin being greater than 0 mass % and equal to or less than 1 mass %.

12. A method for producing a bonded body in which a bonded body is bonded to a metal, the method comprising a coating step of coating the metal bonding composition according to claim 1 onto the metal.

13. The method for producing a joined body according to claim 12, wherein the metal is a dried or sintered body of a metal paste containing metal particles on a substrate.

14. A method for manufacturing a bonded body according to claim 13, comprising, after the coating step, a bonded body placement step of placing the bonded body on the coated dried body or sintered body, and a sintering step of sintering the dried body to form a sintered layer, wherein the sintering step is performed by heating the bonded body at a temperature of 150°C or higher while applying a pressure of 1 MPa or more from the bonded body side.

15. A method for manufacturing a bonded body in which a base material and an object to be bonded are bonded via a metal particle sintered body, comprising a semi-drying step of semi-drying a metal paste on the base material to form a semi-dried body, and a sintering step of sintering the semi-dried body to form the metal particle sintered body, wherein the metal paste is the metal paste described in claim 10.

16. A method for manufacturing a bonded body according to claim 15, further comprising a step of placing the bonded body on the semi-dried body after the semi-drying step, wherein the semi-drying step is carried out at a temperature of 130°C or less, and wherein the sintering step is carried out by heating the bonded body at a temperature of 150°C or more while applying a pressure of 1 MPa or more from the bonded body side.

17. A method for producing a sintered body, comprising heating the metal paste according to claim 10 in an inert atmosphere at a temperature of 100°C to 300°C to obtain a metal particle sintered body.

18. A method for producing a sintered body, comprising adhering the metal paste according to claim 10 onto a resin film and heating the film at a temperature of 140°C or higher for one minute or more to obtain a metal particle sintered body.

19. A method for manufacturing a bonded body, comprising: a sintered body placement step of placing a sintered body obtained by the method for manufacturing a sintered body described in claim 17 on a base material; a bonded body placement step of placing a bonded body on the sintered body; and a re-sintering step of further heating and sintering the sintered body.

Images