Alloy, particles, alloy ribbon, preform, sintered body, joined body, electronic device, and sintered body production method

Abstract

The present invention provides an alloy that makes it possible to easily form a sintered body which has excellent joining reliability. An alloy according to the present disclosure is characterized by comprising a phase in which a metal element Y is in solid solution in a metal element X, wherein the metal element X is deposited on a surface via heat treatment in a gas, liquid, or solid atmosphere in which a compound is formed with the metal element Y. The metal element X is preferably deposited on the surface via a heat treatment in an oxygen atmosphere. The metal element X is preferably Ag and / or Cu. It is preferable that the metal element X contains Ag and that the metal element Y contains Si and / or Ge.

Description

Alloy, particle, alloy ribbon, preform, sintered body, bonded body, electronic device, and method for manufacturing sintered body

[0001] This disclosure relates to alloys, particles, alloy ribbons, preforms, sintered bodies, joined bodies, electronic devices, and methods for manufacturing sintered bodies. This application claims priority from Japanese Patent Application No. 2023-146497, filed September 8, 2023, the contents of which are incorporated herein by reference.

[0002] Semiconductors used in power devices are required to have high efficiency, low loss, and high-frequency switching, and the use of wide-gap semiconductors such as SiC and GaN semiconductors is expanding. The operating temperatures of such semiconductors can exceed 200°C, so the bonding materials used for bonding must maintain high bonding reliability even when the semiconductors operate in high-temperature ranges or in harsh temperature cycle environments.

[0003] In recent years, the use of silver (Ag) paste has attracted attention due to its high electrical and thermal conductivity, high melting point, and stability. However, because Ag has a high melting point, attempting to bond in bulk can cause thermal damage to the substrate. Therefore, low-temperature sintering technology using nanoparticles has been adopted to reduce the bonding temperature.

[0004] As a material that has high bonding reliability even when operating in such high temperature ranges or in harsh temperature cycle environments, for example, a metal sintered joint described in Patent Document 1 has been known.

[0005] International Publication No. 2018 / 037992

[0006] However, the metal sintered bonded body of Patent Document 1 has the limitation that it needs to be sintered under specific pressure and heating conditions in order to achieve high bonding reliability, and there is also room for improvement in the bonding reliability of the resulting sintered body.

[0007] Furthermore, with conventional metal nanoparticles, the smaller the particle size, the lower the sintering temperature can be, but at the same time, the porosity increases, which is known to cause cracks due to repeated heating. Therefore, in order to achieve sufficient bonding reliability after bonding, it is necessary to carefully set the composition of the metal sintered bond and the heat treatment conditions.

[0008] The present disclosure is intended to solve the above-mentioned problems and to provide an alloy that can easily form a sintered body with excellent bonding reliability. Means to solve the problem

[0009] As a result of earnest efforts to solve the above problems, the present inventors have found that an alloy containing a phase in which a metal element Y is dissolved in a metal element X, and in which the metal element X is precipitated on the surface by a specific treatment, can easily form a sintered body having excellent bonding reliability.

[0010] That is, the present disclosure provides an alloy that includes a phase in which metal element Y is dissolved in metal element X, and in which metal element X precipitates on the surface by heat treatment in a gas, liquid, or solid atmosphere that forms a compound with metal element Y.

[0011] The alloy is heat-treated in a gas, liquid, or solid atmosphere in which a compound is formed with the metal element Y, whereby the metal element Y forms a compound while the metal element X is precipitated on the surface of the alloy. The precipitated metal element X can be firmly bonded to the nearby alloy, resulting in excellent bonding reliability.

[0012] It is preferable that the alloy is heat-treated in an oxygen atmosphere so that the metal element Y is oxidized and the metal element X is precipitated on the alloy surface.

[0013] In the alloy, the metal element X is preferably Ag and / or Cu. With the above structure, operation at high temperatures becomes easier.

[0014] In the alloy, the metal element X is preferably Ag and the metal element Y is preferably Si and / or Ge. With this configuration, the metal element X and the metal element Y are less likely to form a compound, and are more likely to contain a solid solution phase.

[0015] In the alloy, the metal element X is preferably Cu and the metal element Y is preferably W and / or Cr. With this configuration, the metal element X and the metal element Y are less likely to form a compound, and are more likely to contain a solid solution phase.

[0016] The alloy preferably contains the metal element Y, which is a supersaturated solid solution of the metal element X. By having the above-mentioned structure, it is possible to make it easier for the metal element X to precipitate on the surface of the alloy when heat treated.

[0017] The alloy preferably has a molar ratio of the metal element X to the metal element Y [metal element X / metal element Y] of 95 / 5 to 10 / 90. By having the above structure, the alloy is likely to contain a phase in which the metal element Y is dissolved in the metal element X.

[0018] The present disclosure also provides particles comprising the alloy.

[0019] The average particle size of the particles is preferably 0.1 to 100 μm.

[0020] The present disclosure also provides an alloy ribbon comprising the above alloy.

[0021] The present disclosure also provides a paste containing the above particles, an organic substance, and Ag powder and / or Cu powder.

[0022] The present disclosure also provides a preform comprising the alloy.

[0023] The preform is preferably in the form of a sheet or a sphere.

[0024] The present disclosure also provides a sintered body of the above alloy.

[0025] The present disclosure also provides a joined body including the above-mentioned sintered body.

[0026] The present disclosure also provides a substrate comprising the above-described bonded structure.

[0027] The present disclosure also provides an electronic device including the above-described bonded body.

[0028] The present disclosure also provides a method for producing a sintered body, which includes a step of heat treating the sintered body in a gas, liquid, or solid atmosphere that forms a compound with the metal element Y.

[0029] The present disclosure also provides a method for producing a sintered body, which includes a step of heat treating the alloy in an oxygen atmosphere.

[0030] In the method for producing the sintered body, the oxygen concentration during the heat treatment is preferably 0.01 to 30%.

[0031] The alloy of the present disclosure can easily provide a sintered body with excellent bonding reliability, and therefore, electronic devices using the alloy of the present disclosure have excellent bonding reliability.

[0032] 1 is a cross-sectional view showing an embodiment of an electronic device according to the present disclosure.

[0033] [Alloy] An alloy according to one embodiment of the present disclosure includes a phase in which a metal element Y is dissolved in a metal element X, and the metal element X precipitates on the surface by heat treatment in a gas, liquid, or solid atmosphere in which a compound is formed with the metal element Y. When the alloy is heat treated in a gas, liquid, or solid atmosphere in which a compound is formed with the metal element Y, the metal element Y in the dissolved phase forms a compound, and the metal element X precipitates on the alloy surface. The precipitated metal element X can be firmly bonded to nearby alloys or objects to be bonded, resulting in excellent bonding reliability. Furthermore, since the metal element X is bonded while being precipitated, no specific pressure conditions or the like are required, and bonding can be easily performed. The metal element X and the metal element Y in the alloy may each be used alone, or two or more types may be used in combination.

[0034] The element contained in the gas phase, liquid phase, or solid phase that forms a compound with the metal element Y preferably contains, for example, oxygen or sulfur, and particularly includes sulfur dioxide, hydrogen sulfide, etc. That is, it is preferable that the alloy is one in which the metal element Y is oxidized by heat treatment in an oxygen atmosphere, while the metal element X is precipitated on the alloy surface.

[0035] The alloy preferably has a eutectic of the metal element X and the metal element Y. When the alloy has a eutectic, it becomes easier to include a phase in which the metal element X is solid-solved in the metal element Y.

[0036] Furthermore, it is preferable that the solid solution phase of the alloy is present on the surface of the alloy. Specifically, the proportion of the solid solution phase in the entire surface (100%) of the alloy is preferably 10% or more, more preferably 15% or more, and even more preferably 20% or more. By having the proportion of the solid solution phase on the alloy surface be 10% or more, the metal element X can be sufficiently precipitated on the surface when sintered.

[0037] The proportion of the dissolved phase in the total amount (100% by mass) of the alloy is preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more. By having the proportion of the dissolved phase be 3% by mass or more, the metal element X can be sufficiently precipitated on the surface during sintering.

[0038] In the present disclosure, metalloid elements are also considered to be metal elements. Examples of the metalloid elements include Si and Ge.

[0039] It is preferable that Ag and / or Cu is contained as the metal element X. Since Ag and Cu have high melting points, when they are used as the metal element X, the melting point of the alloy can be increased, facilitating operation at high temperatures.

[0040] Specific examples of the metal element Y include Si, Ge, W, and Cr. In particular, when the metal element X contains Ag, the metal element Y preferably contains Si and / or Ge. When the metal element Y contains Cu, the metal element Y preferably contains W and / or Cr. With the above-described configuration, the metal element X and the metal element Y are less likely to form a compound, and a solid solution phase can be more easily formed.

[0041] Furthermore, the alloy preferably contains the metal element Y, which is a supersaturated solid solution of the metal element X. By having the above-mentioned configuration, it is possible to easily precipitate the metal element X on the surface of the alloy when heat-treated in an oxygen atmosphere. In the present disclosure, a supersaturated solid solution can be produced by rapidly cooling a melt of the metal element X and the metal element Y, so that a larger amount of the metal element Y than usual is stably dissolved in the metal element X. In the supersaturated solid solution, the metal element Y is preferably dissolved in a solid solution of 0.5 moles or more in 100 moles of the metal element X, more preferably 1 mole or more, and even more preferably 1.5 moles or more.

[0042] The molar ratio of the metal element X to the metal element Y [metal element X / metal element Y] is preferably 95 / 5 to 10 / 90, more preferably 93 / 7 to 30 / 70, even more preferably 90 / 10 to 50 / 50, and particularly preferably 90 / 10 to 70 / 30. By having the molar ratio be 95 / 5 to 10 / 90, it is possible to easily include a phase in which the metal element Y is solid-dissolved in the metal element X. Furthermore, even when the proportion of the metal element Y is large, it is easy for a portion of the metal element X to include a phase in which the metal element Y is solid-dissolved.

[0043] In 100% by mass of the alloy, the content of the metal element X is preferably 1 to 99% by mass, more preferably 10 to 98% by mass, and even more preferably 50 to 97% by mass. When the content of the metal element X is 1% by mass or more, it is possible to easily include a phase in which the metal element X is solid-solved with the metal element Y. Furthermore, when the content is 99% by mass or less, it is possible to easily exhibit bonding reliability.

[0044] The content of the metal element Y in 100% by mass of the alloy is preferably 1 to 99% by mass, more preferably 2 to 90% by mass, and even more preferably 3 to 50% by mass. By making the content of the metal element Y 1% by mass or more, it is possible to easily exhibit bonding reliability. Furthermore, by making the content 99% by mass or less, it is possible to easily include a phase in which the metal element X is solid-solved with the metal element Y.

[0045] In addition, the total content of the metal element X and the metal element Y in the total amount of the alloy (100% by mass) is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 100% by mass.

[0046] Furthermore, the alloy may contain components other than metal element X and metal element Y, but from the viewpoint of exhibiting connection reliability, it is preferable that the alloy does not contain the other components. Examples of the other components include elements that easily form compounds with metal element X or metal element Y, and compounds containing the above elements. When the alloy contains the other components, the amount of the other components is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 1% by mass or less, relative to the total amount (100% by mass) of the alloy.

[0047] The method for producing the alloy is not particularly limited, but it is preferable to produce the alloy by quenching a melt of the metal element X and the metal element Y. Examples of the quenching method include water atomization, gas atomization, and single roll method.

[0048] The form of the metal element X and the metal element Y to be melted is not particularly limited, but is preferably in powder form for ease of melting. In particular, from the viewpoint of efficient melting, it is preferable that the form of the metal element X and the metal element Y be a eutectic powder of the metal element X and the metal element Y.

[0049] [Particles] One embodiment of the present disclosure can include particles containing the alloy.

[0050] The average particle size (median diameter) of the particles is preferably 0.1 to 100 μm, more preferably 0.3 to 50 μm, even more preferably 0.5 to 30 μm, and particularly preferably 1.0 to 10 μm. An average particle size of 0.1 μm or more makes handling easier, and an average particle size of 100 μm or less ensures sufficient particle surface area, making it easier to bond the particles in a short period of time. The average particle size (median diameter) can be measured by laser diffraction / scattering.

[0051] The shape of the particles is not particularly limited, but examples thereof include spherical, flake (flat) and polyhedral shapes.

[0052] The method for producing the particles is not particularly limited, but for example, the particles can be produced by pulverizing a heated melt of metal element X and metal element Y by gas atomization or water atomization.

[0053] [Alloy Ribbon] One embodiment of the present disclosure can include an alloy ribbon containing the above alloy.

[0054] The thickness of the alloy ribbon is preferably 1 μm to 2 mm, more preferably 10 μm to 1 mm, and even more preferably 50 μm to 0.5 mm. A thickness of 1 μm or more makes it easy to form into a ribbon shape, and a thickness of 2 mm or less makes it easy to rapidly cool.

[0055] The width of the ribbon is preferably 0.1 to 100 mm, more preferably 0.5 to 50 mm, and even more preferably 1 to 10 mm. When the width is 0.1 mm or more, it becomes easy to form the ribbon, and when it is 100 mm or less, it becomes easy to rapidly cool it.

[0056] The method for producing the alloy ribbon is not particularly limited, but for example, it can be produced by a method in which a heated melt of metal element X and metal element Y is quenched by a single roll method.

[0057] Another embodiment of the present disclosure is a particle-containing composition containing the above-described particles. The particle-containing composition is not particularly limited and can take various forms. For example, a particle-containing composition called alloy ink can be prepared by dispersing the particles in a suspended state in an appropriate organic solvent (dispersion medium). Alternatively, a particle-containing composition called paste can be prepared by dispersing the particles in a kneaded state in an organic solvent. Among these, the particle-containing composition is preferably a paste. Note that the particles contained in the particle-containing composition may be of one type or a combination of two or more types.

[0058] [Paste] The paste preferably contains an organic substance in addition to the particles.

[0059] Examples of the organic substance include reducing organic substances, basic compounds, coordinating organic compounds other than the compounds corresponding to the basic compounds, resins, organic solvents, etc. The organic substances may be used alone or in combination of two or more.

[0060] <Reducing Organic Substance> Examples of the reducing organic substance include alcohols (lower alcohols such as ethanol, higher alcohols such as palmitol) other than those exemplified as organic solvents described below, aldehydes (formaldehyde, acetaldehyde, cyclic trimers and tetramers of these aldehydes), amino acids, organic acids (carboxylic acids, etc.), aromatic compounds (polyphenols, phenolic acid compounds, etc.). Among these, organic acids (carboxylic acids, etc.) and aromatic compounds are preferred because they exhibit acidity, and carboxylic acids are more preferred because they are easy to handle at room temperature and not highly toxic. These may be used alone or in combination of two or more.

[0061] Examples of the carboxylic acid include formic acid, acetic acid, lactic acid, propionic acid, acrylic acid, malic acid, n-hexanoic acid, succinic acid, n-octanoic acid, tartaric acid, and oxalic acid. Among these, formic acid and oxalic acid are preferred because they are excellent in reducing properties and can easily produce a sintered body having excellent electrical conductivity.

[0062] The reducing organic substance preferably contains formic acid from the viewpoint of excellent reducibility and void suppression, and further preferably contains a compound having a boiling point higher than that of formic acid (particularly a compound having a boiling point higher than that of the coordinating organic compound) together with formic acid from the viewpoint of being able to exhibit reducing properties over a wide temperature range.

[0063] When formic acid is contained as the reducing organic substance, the content of formic acid is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 80% by mass or more, relative to the total amount (100% by mass) of the reducing organic substances. When another reducing organic substance other than formic acid (e.g., a compound having a boiling point higher than that of formic acid) is contained together with formic acid, the content of the other reducing organic substance is preferably 0.1 molar parts or less, more preferably 0.05 molar parts or less, relative to 1 molar part of formic acid.

[0064] The content of the reducing organic substance is preferably 5% by mass or less (for example, 0.1 to 5% by mass) relative to the total amount (100% by mass) of the paste, more preferably 0.1 to 4.0% by mass, even more preferably 0.2 to 3.7% by mass, and particularly preferably 0.3 to 3.5% by mass.

[0065] <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 nitrogen-containing compounds such as ammonia, amine compounds, and phosphorus-containing compounds such as phosphines and phosphate esters. Among these, nitrogen-containing compounds represented by the following formula (1) are preferred because they make it easier to obtain a sintered body with excellent electrical conductivity. 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 is at least one group selected from an amino group, an N-substituted amino group, an N,N-substituted amino group, an imino group, an N-substituted imino group, and a hydroxyl 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. In the case of a double bond, R ｃ does not exist. ａ ~R ｃ Any two of may be bonded to each other to form a ring together with the adjacent nitrogen atom.

[0066] R ａ ~R ｃExamples of the hydrocarbon group include an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. Among these, an aliphatic hydrocarbon group and an alicyclic hydrocarbon group are preferred, and an aliphatic hydrocarbon group is more preferred.

[0067] Examples of the aliphatic hydrocarbon group include a linear or branched alkyl group, a linear or branched alkenyl group, a linear or branched alkynyl group, and a linear or branched alkylidene group, and among these, a linear or branched alkyl group is preferred.

[0068] 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 preferably 3 to 12 carbon atoms, more preferably 3 to 8 carbon atoms, and even more preferably 3 to 6 carbon atoms. Examples of the linear or branched alkyl group 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.

[0069] 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. Examples thereof include a vinyl group, a 1-propenyl group, a 2-propenyl group, a 1-butenyl group, a 2-butenyl group, a 3-butenyl group, a 1-pentenyl group, a 2-pentenyl group, a 3-pentenyl group, a 4-pentenyl group, a 1-hexenyl group, a 3-hexenyl group, a 5-hexenyl group, a 1-heptenyl group, a 1-octenyl group, a 1-nonenyl group, a 1-decenyl group, an isopropenyl group, a 2-methyl-1-propenyl group, a methallyl group, a 3-methyl-2-butenyl group, and a 4-methyl-3-pentenyl group.

[0070] 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. Examples of the linear or branched alkynyl group 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.

[0071] 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. Examples of the linear or branched alkylidene group 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.

[0072] Examples of the alicyclic hydrocarbon group include a cycloalkyl group and a cycloalkenyl group.

[0073] 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, and examples thereof 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.

[0074] 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, and examples thereof include a cyclopentenyl group and a cyclohexenyl group.

[0075] The aromatic hydrocarbon group is preferably an aryl group having 6 to 18 carbon atoms, more preferably 6 to 14 carbon atoms, and even more preferably 6 to 10 carbon atoms, and examples thereof include a phenyl group and a naphthyl group.

[0076] 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.

[0077] 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.

[0078] R ａ ~R ｃ The total number of imino groups and N-substituted imino groups that may be contained in the alkyl group is preferably 0 to 4, more preferably 1 to 3, and even more preferably 1 or 2.

[0079] R ａ ~R ｃ The total number of hydroxyl groups that may be possessed by is preferably 0 to 6, more preferably 1 to 4, and even more preferably 1 or 2.

[0080] The substituents of the N-substituted amino group, N,N-substituted amino group, and N-substituted imino group are the same as those of the above R ａ ~R ｃ The hydrocarbon groups are the same as those described above.

[0081] 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.

[0082] R ａ ~R ｃThe hydrocarbon group in the formula (I) 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, or a hydroxyl group. Examples of such a substituent include a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, or 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 carboxyl 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, and a heterocyclic group.

[0083] Specific examples of the basic compound represented by 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 hydroxyl 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 hydroxyl group; ａ ~R ｃ are the same or different and are a linear or branched alkyl group having one hydroxyl 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 hydroxyl groups; ａ ~R ｃ a diamine having a total of one amino group; ａ ~R ｃa triamine having a total of two amino groups; ａ ~R ｃ a diaminoalkanol having a total of one amino group and a total of one hydroxyl group; R in formula (1) ａ ~R ｃ an imidazole compound containing one imino group in total, and a ring formed by incorporating the nitrogen atoms of the imino groups; 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).

[0084] Examples of the alkylamine include methylamine, ethylamine, propylamine, butylamine, pentylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, piperidine, trimethylamine, triethylamine, dimethyldecylamine, dimethyldodecylamine, 4-dimethylaminopyridine, 2-aminopyrazine, 2-aminopyrimidine, 3-aminopyridazine, 2-aminotriazine, diazabicyclononene, and diazabicycloundecene.

[0085] Examples of the monoalkanolamine include 2-aminoethanol, 3-aminopropanol, 1-amino-2-propanol, 1-amino-2-methyl-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.

[0086] Examples of the dialkanolamine include diethanolamine, di-n-propanolamine, diisopropanolamine, di-n-butanolamine, diisobutanolamine, and N-methyldiethanolamine.

[0087] Examples of the trialkanolamine include triethanolamine, tri-n-propanolamine, triisopropanolamine, tri-n-butanolamine, and triisobutanolamine.

[0088] 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.

[0089] 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, and N,N'-diethyl-1,4-butanediamine. Examples thereof include hexanediamine, N,N'-dimethyl-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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] The basic compound contained in the paste is preferably a chelating basic compound having an ethylenediamine structure or an ethanolamine structure in its molecular structure, since this facilitates stabilization of the metal ions that have dissolved the metal oxide on the surface of the metal particles by chelating coordination. The amino group in the structure may be any of primary, secondary, and tertiary amino groups, but is preferably a tertiary amino group from the viewpoint of suppressing side reactions between the basic compound and the reducing organic substance.

[0095] The basic compound preferably contains an alkylamine having at least one linear alkyl group having 1 to 20 carbon atoms (preferably 1 to 15 carbon atoms) in addition to the chelating basic compound.

[0096] In the paste, the molar ratio of the basic groups of the basic compound to the acidic groups of the reducing organic substance (basic groups / acidic groups) is 0.4 or more, preferably 0.5 or more, more preferably 0.6 or more, even more preferably 1.0 or more, and particularly preferably 1.6 or more. If the molar ratio is less than 0.4, the reaction between the acidic groups of the reducing organic substance and the metal may progress, causing the metal paste to become a solid aggregate, making it impossible to maintain a paste state. The molar ratio is preferably 2.0 or less, more preferably 1.8 or less, and even more preferably 1.7 or less. If it is 2.0 or less, the surface of the metal particles is easily reduced, resulting in excellent conductivity of the sintered body. The number of moles of acidic groups contained in the reducing organic substance is calculated by multiplying the number of moles of the reducing organic substance by the number of acidic groups contained in the reducing organic substance, and the number of moles of basic groups contained in the basic compound is calculated by multiplying the number of moles of the basic compound by the number of basic groups contained in the basic compound.

[0097] The content of the basic compound in the paste is preferably 0.1 to 10% by mass, more preferably 0.3 to 9% by mass, and even more preferably 0.5 to 8% by mass, relative to the total amount (100% by mass) of the paste.

[0098] <Coordinating Organic Compound> The coordinating organic compound is a compound that coordinates to the metal surface of the metal particles, and is a compound excluding compounds that fall under the category of the basic compounds. The coordinating organic compound preferably has a boiling point higher than that of at least one of the reducing organic compounds. In this case, the coordinating organic compound remains more than the reducing organic compound during firing, which tends to suppress contact between the reducing organic compound and the active metal surface, thereby suppressing decomposition of the reducing organic compound.

[0099] Examples of the coordinating organic compound include at least one compound selected from the group consisting of compounds having a carboxyl group, compounds having a ketone group (e.g., diketones such as acetylacetone, β-ketoesters, etc.), compounds having a hydroxyl group, compounds having a sulfo group, and compounds having a thiol group. Among these, compounds having a carboxyl group are preferred because they facilitate the precipitation of dissolved metal oxides as small metal particles.

[0100] The compound having a carboxyl group is preferably a monovalent or divalent carboxylic acid, and more preferably a monovalent carboxylic acid, in that the metal particle aggregates can be easily sintered in a subsequent step.

[0101] The carboxylic acid may be the same as the carboxylic acid described above for the reducing organic substance. Furthermore, because of their easy availability, low toxicity, and low odor, they may be carboxylic acids having 2 to 15 carbon atoms (preferably 5 to 12, and more preferably 8 to 10). Specific examples include acetic acid (boiling point 118°C), lactic acid (boiling point 122°C), propionic acid (boiling point 141°C), acrylic acid (boiling point 141°C), malic acid (boiling point 167°C), pentanoic acid (boiling point 186°C), n-hexanoic acid (boiling point 205°C), heptanoic acid (boiling point 223°C), 2-ethylhexanoic acid (boiling point 228°C), succinic acid (boiling point 235°C), n-octanoic acid (boiling point 237°C), nonanoic acid (boiling point 254°C), decanoic acid (boiling point 269°C), dodecanoic acid (boiling point 299°C), tartaric acid (boiling point 275°C), and oxalic acid (boiling point 365°C). Since carboxylic acids function as both reducing organic substances and coordinating organic compounds, when using carboxylic acids as coordinating organic compounds, one carboxylic acid having the lowest boiling point may be used in combination with another carboxylic acid having a higher boiling point than the one carboxylic acid. In this case, the carboxylic acid with the relatively high boiling point acts primarily as a protecting agent, and the carboxylic acid with the relatively low boiling point acts as a reducing agent.

[0102] The boiling point of the carboxylic acid at normal pressure is preferably above 110°C, more preferably 150°C or higher, and even more preferably 200°C or higher, because the carboxylic acid is less likely to volatilize than formic acid (boiling point 101°C).

[0103] In the paste, the ratio of the number of moles of the coordinating functional groups contained in the coordinating organic compound to the number of moles of the acidic groups contained in the reducing organic substance (coordinating functional groups / acidic groups) is preferably 0.05 to 1.20, more preferably 0.40 to 1.10, and even more preferably 0.50 to 0.70. When the molar ratio is 0.05 or more, precipitation of small-diameter metal particles is easily obtained, and when it is 1.20 or less, the coordinating organic compound is less likely to remain after firing.

[0104] In the paste, the molar ratio of the number of moles of the coordinating functional group contained in the coordinating organic compound to the basic group of the basic compound (coordinating functional group / basic compound) is preferably 0.10 to 1.00, more preferably 0.15 to 0.75, and even more preferably 0.20 to 0.60. When the molar ratio is 0.10 or more, precipitation of small-diameter metal particles is easily obtained, and when it is 1.00 or less, the coordinating organic compound is less likely to remain after firing.

[0105] The content of the coordinating organic compound in the paste is preferably 0.1 to 10 mass %, more preferably 0.2 to 9 mass %, and even more preferably 0.3 to 8 mass %, relative to the total amount (100 mass %) of the paste.

[0106] <Resin> Examples of the resin include thermoplastic resins (polyester-based resins, polyamide-based resins, polyurethane-based resins, polyimide-based resins, polyolefin-based resins, (meth)acrylic resins, styrene-based resins, halogen-containing vinyl-based resins, polyvinyl acetal-based resins, cellulose-based resins (ethyl cellulose resins, alkyl cellulose resins, etc.), thermoplastic silicone resins, etc.), and thermosetting resins (epoxy resins, unsaturated polyester resins, diallyl phthalate resins, silicone resins, etc.). Among these, thermoplastic resins are preferred from the viewpoint of their ability to relieve internal stress during heating, and (meth)acrylic resins and polyvinyl acetal resins are preferred from the viewpoint of the adhesion and strength of the metal particle aggregate to the substrate.

[0107] Examples of the polyvinyl acetal resin include polyvinyl butyral.

[0108] The content of the resin in the paste is preferably 1.0% by mass or less, more preferably 0.05 to 1.0% by mass, and even more preferably 0.1 to 0.9% by mass, relative to the total amount (100% by mass) of the paste.

[0109] <Organic Solvent> The paste may contain an organic solvent to adjust fluidity (viscosity) and operability. The organic solvent preferably contains at least organic solvent (a), organic solvent (b), and organic solvent (c). The organic solvents (a), (b), and (c) are different compounds and satisfy the following formulas (1) to (6). Only one type of organic solvent (a), organic solvent (b), and organic solvent (c) may be used, or two or more types may be used. 150°C≦Ta≦250°C (1) 150°C≦Tb≦250°C (2) 250°C≦Tc≦350°C (3) δa≧10.0 (4) δc≦9.0 (5) δc≦δb≦δa (6)

[0110] In the formula, Ta to Tc represent the boiling points of the organic solvents (a) to (c), respectively, and δa to δc represent the Hansen solubility parameters of the organic solvents (a) to (c), respectively. In this specification, the Hansen solubility parameter is sometimes referred to as the "SP value" and abbreviated as "δ."

[0111] The organic solvents (a) to (c) may be any solvents that dissolve uniformly and become liquid when mixed in the compounding ratio used in the above-mentioned bondable conductor paste, and each of them may be liquid or solid at room temperature.

[0112] The organic solvent (a) at least satisfies formula (1). That is, the boiling point Ta of the organic solvent (a) satisfies 150° C.≦Ta≦250° C., preferably 150° C.<Ta<250° C., more preferably 155° C.≦Ta≦220° C., and even more preferably 160° C.≦Ta≦200° C. By using an organic solvent (a) having a boiling point within the above range, the organic solvent is easily volatilized during sintering, and a sintered body can be easily formed.

[0113] The organic solvent (a) at least satisfies the formula (4) [δa≧10.0]. The SP value δa of the organic solvent (a) is 10.0 or more, preferably 10.3 or more, more preferably 10.4 or more, within the range satisfying the formula (6). When the δa is 10.0 or more, the dispersibility of the particles and the Ag and / or Cu powder described below is excellent, and separation of the metal particles and the organic solvent can be made less likely to occur. The δa of the organic solvent (a) is, for example, 16.0 or less, and may be 15.0 or less.

[0114] Examples of the organic solvent (a) include alcohol solvents, urea-based solvents, and aprotic polar solvents. Examples of the alcohol solvent include compounds having one or more hydroxy groups, and among these, tertiary alcohols and ether alcohols are preferred. The alcohol solvent may have two or more hydroxy groups. Examples of the ether alcohol include compounds having an ether bond and a hydroxy group, such as (poly)alkylene glycol monoalkyl ethers and alkoxy-substituted alcohols.

[0115] Specific examples of the organic solvent (a) include pinacol (δ 10.7, boiling point 172°C), tetramethylurea (δ 10.6, boiling point 177°C), 3-methoxybutanol (δ 10.6, boiling point 161°C), 1-methylcyclohexanol (δ 10.4, boiling point 155°C), and methyl carbitol (diethylene glycol monomethyl ether) (δ 10.7, boiling point 193°C).

[0116] The organic solvent (b) at least satisfies formula (2). That is, the boiling point Tb of the organic solvent (b) satisfies 150°C ≦ Tb ≦ 250°C, preferably 150°C < Tb < 250°C, more preferably 180°C ≦ Tb ≦ 248°C, and even more preferably 200°C ≦ Tb ≦ 245°C. By using an organic solvent (b) having a boiling point within the above range, the organic solvent is easily volatilized during sintering, making it easy to form a sintered body. Furthermore, by using an organic solvent (b) having a boiling point of 250°C or less, it is possible to suppress the generation of voids during sintering.

[0117] The organic solvent (b) at least satisfies formula (6). The SP value δb of the organic solvent (b) is preferably 8.0 to 12.0, more preferably 8.5 to 11.0, and even more preferably 9.0 to 10.5, within the range satisfying formula (6). When δb is within the above range, the compatibility of the organic solvent (a) and the organic solvent (c) is improved, they are less likely to separate, and the continuous ejection stability and storage stability tend to be more excellent.

[0118] Examples of the organic solvent (b) include alcohol solvents, ester solvents, ketone solvents, and amine-based solvents. Examples of the alcohol solvent include solvent compounds having one or more hydroxy groups, and among these, tertiary alcohols, ether alcohols, and ester alcohols are preferred. Ether alcohols are compounds having an ether bond and a hydroxy group, such as (poly)alkylene glycol monoalkyl ethers and alkoxy group-substituted alcohols. Ester alcohols are compounds having an ester bond and a hydroxy group, such as (poly)alkylene glycol monoalkyl ether monoesters. Examples of ester solvents include diacetates of diols such as (poly)alkylene glycols. Preferred ketone solvents are cyclic ketones. Preferred amine-based solvents are alkylamines.

[0119] The organic solvent (b) is selected on the premise that it satisfies the formula (6) in relation to the organic solvents (a) and (c). Specific examples of the organic solvent (b) include d-camphor (δ 10.4, boiling point 204°C), 1-heptanol (δ 10.0, boiling point 177°C), butyl carbitol (diethylene glycol monobutyl ether) (δ 10.2, boiling point 231°C), ethyl carbitol (diethylene glycol monoethyl ether) (δ 10.5, boiling point 196°C), tripropylene glycol monomethyl ether (δ 9.4, boiling point 243°C), α-terpineol (δ 9 .3, boiling point 220°C), dihydroterpineol (δ 9.0, boiling point 210°C), 1,3-butanediol diacetate (δ 9.2, boiling point 232°C), propylene glycol diacetate (δ 9.3, boiling point 190°C), butyl carbitol acetate (δ 9.0, boiling point 247°C), dipropylene glycol butyl ether (δ 9.2, boiling point 230°C), isophorone (δ 9.5, boiling point 213°C), 1-decanol (δ 9.6, boiling point 230°C), propylene glycol monobutyl ether (δ 9.0, boiling point 170°C), 1-nonanol (δ 9.8, boiling point 214°C), etc. may be used.

[0120] The boiling point Tb of the organic solvent (b) is preferably higher than the boiling point Ta of the organic solvent (a), i.e., Tb > Ta. The temperature difference between Tb and Ta [Tb - Ta] is preferably 2°C or more, more preferably 5°C or more, and even more preferably 10°C or more. When the temperature difference is 2°C or more, the generation of voids during sintering can be further suppressed.

[0121] The organic solvent (c) at least satisfies formula (3). That is, the boiling point Tc of the organic solvent (c) satisfies 250°C ≦ Tc ≦ 350°C, preferably 250°C < Tc < 350°C, more preferably 250°C < Tc ≦ 320°C, and even more preferably 250°C < Tc ≦ 300°C. By using an organic solvent (c) having a boiling point within the above range, rapid evaporation of the organic solvents (a) and (b) during sintering can be suppressed, and the generation of voids can be suppressed.

[0122] The organic solvent (c) at least satisfies formula (5) [δc≦9.0]. The SP value δc of the organic solvent (c) is 9.0 or less, preferably 8.7 or less, and more preferably 8.5 or less. By making the δc 9.0 or less, it is possible to suppress the generation of voids during sintering. The δc of the organic solvent (c) is, for example, 6.0 or more, and may be 7.0 or more.

[0123] Examples of the organic solvent (c) include ether solvents, alkane solvents, and ester solvents. Examples of the ether solvent include (poly)alkylene glycol dialkyl ethers. Examples of the alkane solvent include alkanes having 14 or more carbon atoms (e.g., 14 to 20 carbon atoms). Examples of the ester solvent include esters of (poly)alkylene glycol alkyl ethers and fatty acids.

[0124] Specific examples of the organic solvent (c) include dibutyl carbitol (diethylene glycol dibutyl ether) (δ 8.3, boiling point 255°C), tetradecane (δ 7.9, boiling point 254°C), and hexadecane (δ 8.0, boiling point 287°C).

[0125] The boiling point Tc of the organic solvent (c) is preferably higher than the boiling point Tb of the organic solvent (b), i.e., Tc > Tb. The temperature difference between Tc and Tb [Tc - Tb] is preferably 2°C or more, more preferably 6°C or more, and even more preferably 10°C or more. When the temperature difference is 2°C or more, the generation of voids during sintering can be further suppressed.

[0126] The boiling point Tc of the organic solvent (c) is preferably higher than the boiling point Ta of the organic solvent (a), i.e., Tc > Ta. The temperature difference between Tc and Ta [Tc - Ta] is preferably 30°C or more, more preferably 50°C or more, and even more preferably 60°C or more. When the temperature difference is 30°C or more, the generation of voids during sintering can be further suppressed.

[0127] The SP value δa of organic solvent (a), the SP value δb of organic solvent (b), and the SP value δc of organic solvent (c) satisfy the relationship of the above formula (6) [δc≦δb≦δa]. In particular, it is preferable that δb is higher than δc, i.e., δc<δb is satisfied. It is also preferable that δa is higher than δb, i.e., δb<δa is satisfied.

[0128] The difference between δb and δc [δb - δc] is preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.5 or more. When the difference is 0.1 or more, the dispersibility of the metal particles is superior and the continuous ejection stability is superior. The difference is preferably 2.0 or less, more preferably 1.5 or less, and even more preferably 1.3 or less. When the difference is 2.0 or less, the particles, the Ag and / or Cu powder described below, and the organic solvent are less likely to separate, and the continuous ejection stability and storage stability are superior.

[0129] The difference between δa and δb [δa-δb] is preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.5 or more. When the difference is 0.1 or more, the dispersibility of the metal particles is superior and the continuous ejection stability is superior. The difference is preferably 2.5 or less, more preferably 2.0 or less, and even more preferably 1.8 or less. When the difference is 2.5 or less, the metal particles and the organic solvent are less likely to separate, and the continuous ejection stability and storage stability are superior.

[0130] The difference between δa and δc, [δa - δc], is 1.0 or more, preferably 1.5 or more, and more preferably 2.0 or more, based on formulas (4) and (5). When the difference is 1.0 or more, the generation of voids during sintering can be further suppressed. The difference is preferably 5.0 or less, more preferably 4.0 or less, and even more preferably 3.0 or less. When the difference is 5.0 or less, the particles, the Ag and / or Cu powder described below, and the organic solvent are less likely to separate, resulting in better continuous discharge stability and storage stability.

[0131] The ratio of organic solvent (a) to the total amount of organic solvents (a), (b), and (c) (100% by mass) [organic solvent (a) / {organic solvent (a) + organic solvent (b) + organic solvent (c)}] is preferably 5 to 70% by mass, more preferably 10 to 60% by mass, and even more preferably 15 to 50% by mass. When this ratio is within this range, the organic solvent is easily volatilized during sintering, making it possible to easily form a sintered body, and also improving the dispersibility of the particles with Ag and / or Cu powder described below.

[0132] The ratio of organic solvent (b) to the total amount of organic solvent (a), organic solvent (b), and organic solvent (c) (100% by mass) [organic solvent (b) / {organic solvent (a) + organic solvent (b) + organic solvent (c)}] is preferably 5 to 70% by mass, more preferably 10 to 60% by mass, and even more preferably 15 to 50% by mass. When the ratio is within the above range, the compatibility of the organic solvents is excellent, and the continuous ejection stability and storage stability are further improved.

[0133] The proportion of organic solvent (c) relative to the total mass of organic solvents (a), (b), and (c) (100 mass%) [organic solvent (c) / {organic solvent (a) + organic solvent (b) + organic solvent (c)}] is preferably 5 to 70 mass%, more preferably 10 to 60 mass%, and even more preferably 15 to 50 mass%. When this proportion is within the above range, the generation of voids during sintering can be further suppressed.

[0134] The content of organic solvent (c) relative to 100 parts by mass of organic solvent (a) is preferably 20 to 400 parts by mass, more preferably 30 to 300 parts by mass, and even more preferably 50 to 200 parts by mass. When the content is within the above range, the blending amounts of organic solvent (a) and organic solvent (c) are well balanced, and void suppression during sintering and dispersibility of the particles with Ag and / or Cu powder described below are improved.

[0135] The content of organic solvent (b) relative to 100 parts by mass of the total amount of organic solvent (a) and organic solvent (c) is preferably 10 to 200 parts by mass, more preferably 20 to 150 parts by mass, and even more preferably 40 to 100 parts by mass. When the content is within the above range, the compatibility between organic solvent (a) and organic solvent (c) is further improved, and the continuous ejection stability and low-temperature storage property are further improved.

[0136] The organic solvent may contain other solvents (organic solvents) in addition to organic solvents (a), (b), and (c). The total content of organic solvents (a), (b), and (c) in the organic solvent is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more, relative to 100% by mass of the total amount of the organic solvents. When the content is 50% by mass or more, the dispersibility of the particles with the Ag and / or Cu powder described below and the compatibility with each organic solvent are excellent, and continuous discharge stability, storage stability, and void formation suppression during sintering are excellent.

[0137] When the organic solvents (a), (b), and (c) are mixed in the blending ratio used for the above-mentioned bondable conductor paste, it is preferable that the organic solvents (a), (b), and (c) dissolve uniformly at room temperature and do not undergo phase separation. Furthermore, it is preferable that the organic solvents (a), (b), and (c) dissolve uniformly at room temperature and do not undergo phase separation in the above-mentioned bondable conductor paste. It is particularly preferable that no phase separation occurs at 22 to 28°C (preferably 10 to 30°C, more preferably 0 to 35°C).

[0138] In the paste, the content of the organic solvent is preferably 0.5 to 30 parts by mass or less, more preferably 2 to 20 parts by mass or less, per 100 parts by mass of the total of the particles, organic substances other than the organic solvent, and Ag and / or Cu powder.

[0139] In addition to the particles, the paste preferably contains Ag and / or Cu powder. In particular, when the particles contain Ag as the metal element X, the paste preferably contains Ag powder. When the particles contain Cu as the metal element X, the paste preferably contains Cu powder.

[0140] The average particle size (median diameter) of the Ag and / or Cu powder is preferably 0.1 to 100 μm, more preferably 0.3 to 50 μm, and even more preferably 0.5 to 10 μm. When the average particle size is 0.1 μm or more, handling becomes easy. When the average particle size is 100 μm or less, bonding reliability becomes easy to exhibit.

[0141] The shape of the Ag and / or Cu powder is not particularly limited, but examples thereof include spherical, flake (flat), polyhedral, etc. Particles of the same shape may be used alone, or particles of different shapes may be used in combination. Among these, spherical shapes are preferred for proper dispersion in the paste.

[0142] The content of the Ag and / or Cu powder is preferably 5 to 2000 parts by mass, more preferably 20 to 1500 parts by mass, even more preferably 30 to 1200 parts by mass, and particularly preferably 50 to 1000 parts by mass, relative to 100 parts by mass of the particles. When the content of the Ag and / or Cu powder is 5 parts by mass or more, sufficient bonding with the alloy particles can be achieved during sinter bonding, and when the content is 2000 parts by mass or less, it is easy to reduce the linear expansion coefficient.

[0143] The paste may also contain other components in addition to the above-mentioned components. Examples of the other components include a non-organic surfactant and a non-organic viscosity modifier. The content of the other components is preferably 5% by mass or less, and may be 3% by mass or less, relative to the total amount (100% by mass) of the organic material.

[0144] [Preform] One embodiment of the present disclosure can include a preform containing the alloy, which is formed into a specific shape by molding the alloy, particles, alloy ribbon, or paste.

[0145] The shape of the preform is not particularly limited, but examples thereof include sheet, sphere, ring, cylinder, ribbon, square, disk, washer, chip, and wire shapes, with sheet and sphere shapes being particularly preferred.

[0146] [Sintered body] One embodiment of the present disclosure can include a sintered body of the above alloy. Figure 1 is an enlarged SEM photograph of the sintered body of the above alloy. Precipitation (nodules) of the metal element X can be confirmed on the surface of the sintered body. The precipitation of the metal element X in the sintered body makes it easy to bond to nearby alloys or objects to be bonded.

[0147] [Method for Manufacturing Sintered Body] Another embodiment of the present disclosure can include a method for manufacturing a sintered body of the above alloy. The sintered body can be manufactured by heat treating the alloy in a gas, liquid, or solid atmosphere that forms a compound with the metal element Y. Heat treatment in an oxygen atmosphere is particularly preferable. When heat treatment is performed in an oxygen atmosphere, the oxygen concentration is preferably 0.01 to 30%, more preferably 0.05 to 25%, and even more preferably 0.1 to 21%. By setting the oxygen concentration to 0.01% or higher, the metal element Y can be oxidized while the metal element X is precipitated. Furthermore, by setting the oxygen concentration to 30% or lower, the oxidation rate of the metal element Y can be made moderate.

[0148] The temperature of the heat treatment (sintering temperature) is preferably 150 to 500°C, more preferably 180 to 450°C, and even more preferably 200 to 400°C. The time of the heat treatment (sintering time) is preferably, for example, 10 seconds to 2 hours, and more preferably 3 minutes to 1 hour. Furthermore, the sintered body may be sintered without pressure, or may be sintered with pressure. When pressure is applied, the pressure during pressing is, for example, 0.3 to 40 MPa.

[0149] [Joined Body] The sintered body can be used as a joined body for joining objects to be joined together. For example, the preform is applied or placed between two objects to be joined, and if necessary, the organic matter is volatilized by heating or the like. Then, the preform is sintered by heating, pressurizing, or irradiating with active energy rays in the presence of oxygen, to obtain a joined body for joining the objects to be joined together. Examples of the joined objects include substrates and electronic components. That is, the sintered body may be used to join substrates together, or may be used to join a substrate and an electronic component.

[0150] The thickness of the bonded body is preferably 5 μm to 500 μm, more preferably 20 to 300 μm, and even more preferably 40 to 150 μm.

[0151] [Electronic Device] One embodiment of the present disclosure includes an electronic device including the sintered body and / or the bonded body. In the electronic device, an object to be bonded is bonded to a substrate via the sintered body and / or the bonded body. Figure 2 is a cross-sectional view schematically showing this electronic device. 1 is the electronic device, 10 is the substrate, 20 is the bonded body, and 30 is the object to be bonded.

[0152] Examples of the substrate include metal substrates such as copper substrates, ceramic substrates, metal-clad ceramic substrates, SiC substrates, gallium nitride substrates, glass epoxy substrates, BT resin substrates, glass substrates, and resin substrates. Since the alloys of the present disclosure can be sintered at relatively low temperatures, substrates that are sensitive to heat can also be used. As the substrate, ceramic substrates and metal-clad ceramic substrates are preferred, and copper-clad ceramic substrates and aluminum-clad ceramic substrates are more preferred.

[0153] Examples of the bonded object include electronic components, heat dissipation substrates, etc. Examples of electronic components include electronic elements (chips, dies) such as semiconductor elements and LED elements, and a specific example of the semiconductor element is a power semiconductor element. In addition, it is preferable that the bonding surface of the bonded object with the bonding layer is silver-plated. Examples of the material of the bonded object include Si (silicon), SiC (silicon carbide), GaN, diamond, etc.

[0154] The electronic device can be manufactured by applying the alloy to a substrate by a printing method (specifically, a dispenser printing method, a mask printing method, a screen printing method, an inkjet printing method, or the like), mounting an object to be bonded on the applied layer, and then sintering the resulting material.

[0155] The sintering conditions can be the same as those described in the above-mentioned method for producing a sintered body.

[0156] The sintering step allows the metal element X in the alloy to precipitate, thereby firmly bonding the alloy to the substrate or the object to be bonded. Therefore, an electronic device including the sintered body and / or bonded body can be easily formed and has excellent bonding reliability.

[0157] Each aspect disclosed in this specification can be combined with any other feature disclosed in this specification. Furthermore, each configuration and their combination in each embodiment is merely an example, and additions, omissions, and other modifications of configurations are possible as appropriate within the scope of the gist of this disclosure. The present disclosure is not limited by the embodiments, but is limited only by the scope of the claims.

[0158] Hereinafter, one embodiment of the present disclosure will be described in more detail based on examples.

[0159] Example 1 Silver (Ag) bullion (purity 99.99%) and silicon (Si) bullion (purity 99.9999%) were mixed to a content of 84 mol % (95 mass %) and 16 mol % (5 mass %), respectively, and then heated to 1450°C and melted. The resulting solution was pulverized while quenched using a gas atomizer (product name "RQP-20K", manufactured by Makabe Giken Co., Ltd.), to obtain alloy particles of Example 1 having an average particle size of 5 μm. The alloy particles of Example 1 contained a solid solution of 5 moles of Si per 100 moles of Ag.

[0160] Example 2 Powdering was carried out in the same manner as in Example 1, except that silver (Ag) bullion (purity 99.99%) and silicon (Si) bullion (purity 99.9999%) were mixed to a content of 89 mol % (97 mass %) and 11 mol % (3 mass %), respectively. The mixture was classified using an ultrasonic vibration sieve (trade name "TSK-DGD type", manufactured by Tokyo Screen Co., Ltd.) to have an average particle size of 20 μm or less, to obtain alloy particles of Example 2. It was confirmed that the alloy particles of Example 2 contained Si as a solid solution in Ag.

[0161] Example 3 Silver (Ag) bullion (purity 99.99%) and silicon (Si) bullion (purity 99.9999%) were mixed to a content of 89 mol % (97 mass %) and 11 mol % (3 mass %), respectively, and then heated to 1450°C to melt. The resulting solution was quenched using a liquid quenching and solidification apparatus (product name "RQP-20K", manufactured by Nisshin Giken Co., Ltd.) to produce the alloy ribbon of Example 3. It was confirmed that Si was dissolved in Ag in the alloy ribbon of Example 3.

[0162] Comparative Example 1 Silver (Ag) bullion (purity 99.99%) and silicon (Si) bullion (purity 99.9999%) were mixed to a content of 89 mol % (97 mass %) and 11 mol % (3 mass %), respectively, and heated to 1450°C to melt. The resulting solution was slowly cooled in a test tube to produce an ingot of Comparative Example 1. Note that in the ingot of Comparative Example 1, it was not confirmed that Si was dissolved in Ag.

[0163]

[0164] [Evaluation] Sintered bodies were produced by sintering the raw materials of the examples and comparative examples for 1 hour under the conditions shown in Table 2. When the oxygen concentration was 0%, sintering was carried out under the condition of a nitrogen concentration of 100% to produce sintered bodies.

[0165] Each of the sintered bodies was photographed at 3000x magnification using an SEM. Those in which nodules were observed on the surface were evaluated as ◯, and those in which nodules were observed were evaluated as ×. The results are shown in Table 2.

[0166]

[0167] It was confirmed that the alloys of the examples precipitated metal element X on the surface when heated in the presence of oxygen. On the other hand, when the alloy did not contain a phase in which metal element Y was dissolved in metal element X (Comparative Example 1), it was not confirmed that metal element X precipitated on the surface even when heated in the presence of oxygen.

[0168] Variations of the present disclosure are described below. [Appendix 1] An alloy containing a phase in which metal element Y is dissolved in metal element X, and in which metal element X precipitates on the surface by heat treatment in a gas phase, liquid phase, or solid phase atmosphere in which a compound is formed with metal element Y. [Appendix 2] The alloy according to Appendices 1, in which metal element X precipitates on the surface by heat treatment in a gas phase atmosphere. [Appendix 3] The alloy according to Appendices 1 or 2, in which metal element X precipitates on the surface by heat treatment in an oxygen atmosphere. [Appendix 4] The alloy according to any one of Appendices 1 to 3, in which the dissolved phase exists on the surface of the alloy. [Appendix 5] The alloy according to any one of Appendices 1 to 4, in which the proportion of the dissolved phase in the entire alloy surface (100%) is 10% or more. [Appendix 6] The alloy according to any one of Appendices 1 to 5, in which the proportion of the dissolved phase in the total amount (100% by mass) of the alloy is 3% or more by mass. [Appendix 7] The alloy according to any one of Appendices 1 to 6, wherein the metal element X is Ag and / or Cu. [Appendix 8] The alloy according to Appendices 7, wherein the metal element X includes Ag and the metal element Y includes Si and / or Ge. [Appendix 9] The alloy according to Appendices 7, wherein the metal element X includes Cu and the metal element Y includes W and / or Cr. [Appendix 10] The alloy according to any one of Appendices 1 to 9, wherein the metal element Y is a supersaturated solid solution of the metal element X. [Appendix 11] The alloy according to any one of Appendices 1 to 10, wherein the molar ratio of the metal element X to the metal element Y [metal element X / metal element Y] is 95 / 5 to 10 / 90. [Appendix 12] The alloy according to any one of Appendices 1 to 11, wherein the content of the metal element X in 100% by mass of the alloy is preferably 1 to 99% by mass, more preferably 10 to 98% by mass, and even more preferably 50 to 97% by mass. [Appendix 13] The alloy according to any one of Appendices 1 to 12, wherein the content of the metal element Y is preferably 1 to 99 mass%, more preferably 2 to 90 mass%, and even more preferably 3 to 50 mass%, based on 100 mass% of the alloy. [Appendix 14] Particles comprising the alloy according to any one of Appendices 1 to 13. [Appendix 15] Particles according to Appendices 14, having an average particle size of 0.1 to 100 μm. [Appendix 16] Alloy ribbon comprising the alloy according to any one of Appendices 1 to 13.[Appendix 17] The alloy ribbon according to Appendix 16, having a thickness of 1 μm to 2 mm. [Appendix 18] The alloy ribbon according to Appendix 16 or 17, having a width of 0.1 to 100 mm. [Appendix 19] A paste comprising the particles according to Appendix 14 or 15, an organic substance, and Ag powder and / or Cu powder. [Appendix 20] A preform comprising the alloy according to any one of Appendixes 1 to 13. [Appendix 21] The preform according to Appendix 20, which is in the form of a sheet or sphere. [Appendix 22] A sintered body of the alloy according to any one of Appendixes 1 to 13. [Appendix 23] A joined body comprising the sintered body according to Appendix 22. [Appendix 24] A substrate comprising the joined body according to Appendix 23. [Appendix 25] An electronic device comprising the joined body according to Appendix 23 or 24. [Appendix 26] A method for producing a sintered body, comprising a step of heat-treating the alloy according to any one of Appendices 1 to 13 in a gas, liquid, or solid atmosphere that forms a compound with the metal element Y. [Appendix 27] A method for producing a sintered body according to Appendices 26, comprising a step of heat-treating in an oxygen atmosphere. [Appendix 28] A method for producing a sintered body according to Appendices 27, wherein the oxygen concentration during the heat treatment is 0.01 to 30%.

[0169] REFERENCE SIGNS LIST 1 Electronic device 10 Substrate 20 Bonded body 30 Object to be bonded

Claims

1. An alloy that contains a phase in which metal element Y is dissolved in metal element X, and in which metal element X precipitates on the surface by heat treatment in a gas, liquid, or solid atmosphere that forms a compound with metal element Y.

2. The alloy according to claim 1, wherein said metal element X precipitates on the surface by heat treatment in an oxygen atmosphere.

3. The alloy according to claim 1 or 2, wherein the metal element X is Ag and / or Cu.

4. The alloy of claim 3, wherein said metallic element X comprises Ag and said metallic element Y comprises Si and / or Ge.

5. The alloy of claim 3, wherein said metallic element X comprises Cu and said metallic element Y comprises W and / or Cr.

6. The alloy of claim 1 or 2, comprising said metallic element Y which is a supersaturated solid solution of said metallic element X.

7. The alloy according to claim 1 or 2, wherein the molar ratio of said metal element X to said metal element Y [metal element X / metal element Y] is 95 / 5 to 10 / 90.

8. Particles comprising the alloy according to claim 1 or 2.

9. The particles according to claim 8, having an average particle size of 0.1 to 100 μm.

10. An alloy ribbon comprising the alloy of claim 1 or 2.

11. A paste comprising the particles according to claim 8, an organic substance, and Ag powder and / or Cu powder.

12. A preform comprising the alloy of claim 1 or 2.

13. The preform according to claim 12, which is in the shape of a sheet or a sphere.

14. A sintered body of the alloy according to claim 1 or 2.

15. A joint comprising the sintered body according to claim 14.

16. A substrate comprising the composite of claim 15.

17. An electronic device comprising the junction of claim 15.

18. A method for producing a sintered body, comprising a step of heat treating the alloy according to claim 1 or 2 in a gas, liquid or solid atmosphere in which a compound is formed with the metallic element Y.

19. A method for producing the sintered body according to claim 18, which comprises a step of heat treating in an oxygen atmosphere.

20. The method for producing a sintered body according to claim 19, wherein the oxygen concentration during the heat treatment is 0.01 to 30%.

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