Solvent composition and method for producing sintered object

Abstract

Provided is a solvent composition that does not need to be removed after application and allows easy production of a sintered object having excellent electrical conductivity and bondability. The solvent composition of the present disclosure is a solvent composition for a sintering aid, the solvent composition including a reducing organic substance and a basic compound. The solvent composition of the present disclosure is also a solvent composition containing a reducing organic substance, a basic compound, and a coordination organic compound other than a compound included as the basic compound, and the coordination organic compound has a higher boiling point than the reducing organic substance.

Description

Technical Field

[0001] The invention according to the present disclosure relates to a solvent composition and a method for producing a sintered object. Priority is claimed on Japanese Patent Application No. 2022-174348 filed on Oct. 31, 2022, the content of which is incorporated herein by reference. Background Art

[0002] In recent years, in rotating electric machines installed in electric vehicles, hybrid vehicles, etc., local temperature rises due to higher outputs are more likely to cause failures in control power modules, etc. To prevent such failures, radiators have been attached to the metal housings of rotating electric machines to promote heat dissipation. For example, lead solder is used for attaching the radiator, but problems may occur in the joining using lead solder, such as the base being prone to deformation due to heating.

[0003] As an alternative to joining using lead solder, for example, Patent Document 1 discloses a joining method using a copper sintered object, and in which copper nanoparticles are formed into a sheet and sintered, laminated with the object to be joined, and then joined by applying pressure and heat to prepare a laminate.

[0004] In addition, for example, Patent Document 2 discloses a conductive paste for forming a metal sintered object, and which contains a mixture of formic acid and an alkaline compound combined in a specific molar ratio as a dispersion medium, whereby formic acid gas is generated and favorable sintering can be carried out even without a reducing atmosphere, and corrosion of metal particles due to formic acid can be suppressed.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2022-029194

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2020-025765 Summary of the Invention

[0009] Technical Problem

[0010] However, the bonding method using a copper sintered body in Patent Document 1 has a problem of complex operation: for example, the copper sintered body obtained by sintering a sintering precursor (copper nanoparticle aggregate) in a reducing atmosphere needs to be sintered immediately after removal in order to prevent re-oxidation before bonding to the object to be bonded; and when removing the surface oxide film using a reducing agent (formic acid) or an etching solution (aqueous sulfuric acid solution) after sintering, laborious efforts are necessary to remove these before bonding in order to prevent corrosion. In addition, when using the conductive paste in Patent Document 2, the sintering precursor (metal particle aggregate) can be sintered without removing the dispersion medium containing formic acid and even without a reducing atmosphere, but when molding the metal particle aggregate, voids generated due to formic acid decomposition gas cannot be sufficiently suppressed, and when voids are generated, the bondability may decrease.

[0011] Therefore, an object of the present disclosure is to provide a solvent composition that does not need to be removed after application and allows for easy production of a sintered body having excellent conductivity and bondability.

[0012] Solution to the problem

[0013] The present inventors conducted extensive research to solve the above problems, and as a result, found that when a solvent composition containing a reducing organic substance and a basic compound is applied to a metal member, the metal oxide film on the surface of the metal member can be dissolved, and a sintered body having excellent conductivity can be easily obtained from the solvent-treated metal member thus obtained without removing the solvent after treatment. In addition, the present inventors found that when a solvent composition containing a reducing organic substance, a basic compound, and a coordinating organic compound is applied to a metal member, the metal oxide film on the surface of the metal member can be dissolved, metal fine particles can be deposited on the surface of the metal member, and a sintered body having excellent conductivity and bondability can be easily obtained from such a solvent-treated metal member without removing the solvent after treatment. The present invention according to the present disclosure has been completed based on these findings.

[0014] Specifically, the present disclosure provides a solvent composition for a sintering aid, the solvent composition containing a reducing organic substance and a basic compound.

[0015] The present disclosure also provides a solvent composition containing a reducing organic substance, a basic compound, and a coordinating organic compound other than the compound included as the basic compound, and the coordinating organic compound has a higher boiling point than the reducing organic substance.

[0016] The reducing organic substance is preferably formic acid.

[0017] Preferably, the solvent composition further contains a reducing organic substance other than formic acid.

[0018] Preferably, the basic compound is a nitrogen-containing compound represented by the following formula (1):

[0019]

[0020] (In formula (1), R a to R c are the same as or different from each other and each represents a hydrogen atom or a hydrocarbon group which may have a substituent; these substituents are the same as or different from each other and are at least one group selected from the group consisting of 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; provided that R a to R c are not simultaneously hydrogen atoms; the double line including the dashed line represents a single bond or a double bond, and when the double line represents a double bond, R c does not exist; and any two of R a to R c may be bonded to each other to form a ring together with the adjacent nitrogen atom).

[0021] Preferably, the basic compound has an ethylenediamine structure or an ethanolamine structure in its molecular structure, and the amino group in the structure is a tertiary amino group.

[0022] Preferably, the ratio (basic group / acidity group) of the total number of moles of the basic groups contained in the basic compound to the total number of moles of the acidic groups contained in the reducing organic substance is 0.40 to 2.50.

[0023] Preferably, the coordination organic compound is a compound having a carboxyl group.

[0024] Preferably, the solvent composition further contains a solvent.

[0025] The present disclosure also provides a method for producing a solvent-treated metal member, the method including applying the solvent composition to the metal member.

[0026] Preferably, in the production method, the metal member is an aggregate of metal particles having a number average particle diameter of 600 nm or more before application.

[0027] The present disclosure also provides a method for producing a solvent-treated metal member, the method including dissolving a metal compound in the solvent composition and then applying the solvent composition to the metal member.

[0028] Preferably, the metal member contains copper.

[0029] Preferably, the metal compound is at least one selected from cuprous oxide (I), cupric oxide (II) and cupric hydroxide (II).

[0030] The present disclosure also provides a method for producing a sintered object, the method including heating a solvent-treated metal member obtained by the production method to obtain a sintered object.

[0031] The present disclosure also provides a method for producing a joined object, the method including bringing a solvent-treated metal member obtained by the production method into contact with an object to be joined and heating them to obtain a joined object.

[0032] The present disclosure also provides a method for producing a joined object, the method including applying the solvent composition onto a layer of metal particle aggregates formed on a substrate surface to form a treated aggregate layer, then bringing an object to be joined into contact with the treated aggregate layer, and heating them to join the substrate and the object to be joined.

[0033] The present disclosure also provides a method for producing a metal member having metal nanoparticles on its surface, the method including applying a solvent composition onto the metal member, dissolving at least a part of the surface of the metal member to form a metal complex, and thermally decomposing and / or reductively decomposing the formed metal complex to deposit metal nanoparticles on the surface of the metal member.

[0034] Advantageous effects of the present invention

[0035] When the solvent composition of the present disclosure is applied onto a metal member (such as metal particle aggregates) and used for assisting sintering, it is not necessary to remove the solvent composition after application, and a sintered object having excellent conductivity and joinability can be produced. Description of the drawings

[0036] Figure 1 Figure 1 An electron microscope image of the surface of the solvent-treated copper foil of Example 6 is shown.

[0037] Figure 2 Figure 2 An electron microscope image of the surface of the solvent-treated copper foil of Example 11 is shown.

[0038] Figure 3 Figure 3 An electron microscope image of the surface of the solvent-treated copper foil of Comparative Example 3 is shown.

[0039] Figure 4 Figure 4 An SAT image of the joined object of Example 24 is shown.

[0040] Figure 5 Figure 5 ​​​​​​​​​​An electron microscope image showing the layout pattern of the Si chip with copper bumps used in Example 25 is presented.

[0041] Figure 6 Figure 6 An electron microscope image showing the surface of the copper bump portion of the Si chip with copper bumps used in Example 25 is presented.

[0042] Figure 7 Figure 7 An electron microscope image showing the surface of the copper bump portion of the solvent-treated Si chip in Example 25 is presented. Detailed Description

[0043] [Solvent Composition]

[0044] The solvent composition according to the first aspect of the present disclosure is a solvent composition for a sintering aid, and the solvent composition contains a reducing organic substance and a basic compound. Since the solvent composition contains a reducing organic substance, oxidation of the surface of the metal member can be suppressed by applying the solvent composition to the surface of the metal member, even in the absence of a reducing atmosphere during the sintering process. In addition, since the solvent composition contains a basic compound, the surface of the metal member can be dissolved and the metal oxide film can be removed, and corrosion of the surface of the metal member caused by the reducing organic substance can be suppressed even if it is not removed after applying the solvent composition to the surface of the metal member. For this reason, the solvent composition is suitable as a solvent composition for a sintering aid for sintering a metal member.

[0045] The solvent composition according to the second aspect of the present disclosure contains a reducing organic substance, a basic compound, and a coordinating organic compound other than the compound included as the basic compound, and the coordinating organic compound has a higher boiling point than the reducing organic substance.

[0046] When the solvent composition contains a coordinating organic compound, since a metal complex is easily formed when the surface of the metal member is dissolved, and the formed metal complex is thermally decomposed or reductively decomposed and precipitates on the surface of the metal member, it may become metal nanoparticles. In addition, when metal nanoparticles are present on the surface of the metal member, since the influence of surface diffusion becomes stronger, the metal member is easily sintered even at a lower temperature.

[0047] [Reducing Organic Substance]

[0048] ​​​​Examples of the reducing organic substances contained in the solvent compositions according to the first and second aspects of the present disclosure include alcohols (lower alcohols such as ethanol, higher alcohols such as palmityl alcohol, and aminoalkanols such as ethanolamine), amino acids, organic acids (carboxylic acids, etc.), and 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 liquids at room temperature, easy to handle, and not highly toxic. These can be used alone, or two or more of them can be used in combination.

[0049] Examples of the carboxylic acids include formic acid, acetic acid, lactic acid, propionic acid, acrylic acid, malic acid, n-caproic acid, succinic acid, n-caprylic acid, tartaric acid, and oxalic acid, and among these, formic acid and oxalic acid are preferred because a sintered body having excellent reducibility and excellent conductivity can be easily obtained.

[0050] In addition, the reducing organic substance used in the solvent composition according to the second aspect of the present disclosure is preferably formic acid because it has a low boiling point and can be easily used in combination with a coordinating organic substance having a higher boiling point than the reducing organic substance.

[0051] When two or more including formic acid are used in combination as the reducing organic substance, the content of the reducing organic substance other than formic acid is preferably 1 mole or less relative to 1 mole of formic acid.

[0052] <Basic compound>

[0053] The basic compound contained in the solvent compositions according to the first and second aspects of the present disclosure is not particularly limited as long as it acts as a base and achieves the effects of the present disclosure, and specific examples thereof include hydroxides such as alkali metal and alkaline earth metal hydroxides, nitrogen-containing compounds such as ammonia and amine compounds, and phosphorus-containing compounds such as phosphines and phosphites. Among these, the nitrogen-containing compound represented by the following formula (1) is preferred because a sintered body having excellent conductivity can be easily obtained.

[0054] [C1]

[0055]

[0056] (In formula (1), R a to R c are the same as or different from each other and each represents a hydrogen atom or a hydrocarbon group which may have a substituent; these substituents are the same as or different from each other and are at least one group selected from the group consisting of amino, N-substituted amino, N,N-substituted amino, imino, N-substituted imino, and hydroxyl; provided that R a to R cnot a hydrogen atom at the same time; a double line including a dashed line represents a single bond or a double bond, and when the double line represents a double bond, there is no R c ; and R a to R c Any two of them can be bonded to each other to form a ring together with the adjacent nitrogen atom.)

[0057] R a to R c Examples of the hydrocarbon group of R to R include an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group, and among these, the aliphatic hydrocarbon group and the alicyclic hydrocarbon group are preferred, and the aliphatic hydrocarbon group is more preferred.

[0058] 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 alkylene group, and among these, the linear or branched alkyl group is preferred.

[0059] The linear or branched alkyl group is preferably a linear alkyl group having 1 to 20 carbon atoms, more preferably a linear alkyl group having 1 to 15 carbon atoms, or preferably a branched alkyl group having 3 to 12 carbon atoms, more preferably a branched alkyl group having 3 to 8 carbon atoms, and still more preferably a branched alkyl group having 3 to 6 carbon atoms, and examples thereof include methyl, ethyl, propyl, butyl, pentyl, hexyl, decyl, dodecyl, tetradecyl, octadecyl, isopropyl, isobutyl, sec-butyl, tert-butyl, and 2-ethylhexyl.

[0060] The linear or branched alkenyl group is preferably a linear alkenyl group having 2 to 12 carbon atoms, more preferably a linear alkenyl group having 2 to 8 carbon atoms, and still more preferably a linear alkenyl group having 2 to 4 carbon atoms, or preferably a branched alkenyl group having 3 to 12 carbon atoms, more preferably a branched alkenyl group having 3 to 8 carbon atoms, and still more preferably a branched alkenyl group having 3 to 6 carbon atoms, and examples thereof include vinyl, 1-propenyl, 2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 1-hexenyl, 3-hexenyl, 5-hexenyl, 1-heptenyl, 1-octenyl, 1-nonenyl, 1-decenyl, isopropenyl, 2-methyl-1-propenyl, methallyl, 3-methyl-2-butenyl, and 4-methyl-3-pentenyl.

[0061] The linear or branched alkynyl group is preferably a linear alkynyl group having 2 to 12 carbon atoms, more preferably a linear alkynyl group having 2 to 8 carbon atoms, and still more preferably a linear alkynyl group having 2 to 4 carbon atoms, or preferably a branched alkynyl group having 3 to 12 carbon atoms, more preferably a branched alkynyl group having 3 to 8 carbon atoms, and still more preferably a branched alkynyl group having 3 to 6 carbon atoms, and examples thereof include ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl, 3-butynyl, 1-pentynyl, 2-pentynyl, 3-pentynyl, 4-pentynyl, 1-hexynyl, 2-hexynyl, 3-hexynyl, 4-hexynyl, 5-hexynyl, 1-heptynyl, 1-octynyl, 1-nonynyl, 1-decynyl, trimethylsilylethynyl and triethylsilylethynyl.

[0062] The linear or branched alkylene group is preferably a linear alkylene group having 1 to 12 carbon atoms, more preferably a linear alkylene group having 1 to 8 carbon atoms, and still more preferably a linear alkylene group having 2 to 4 carbon atoms, or preferably a branched alkylene group having 3 to 12 carbon atoms, more preferably a branched alkylene group having 3 to 8 carbon atoms, and still more preferably a branched alkylene group having 3 to 6 carbon atoms, and examples thereof include methylene, propylene, isopropylidene, butylene, isobutylene, sec-butylene, pentylene, isopentylene, octylene and isooctylene.

[0063] Examples of the alicyclic hydrocarbon group include cycloalkyl and cycloalkenyl.

[0064] The cycloalkyl group is preferably a cycloalkyl group having 3 to 12 carbon atoms, more preferably a cycloalkyl group having 4 to 10 carbon atoms, and still more preferably a cycloalkyl group having 5 to 8 carbon atoms, and examples thereof include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl and cyclodecyl.

[0065] The cycloalkenyl group is preferably a cycloalkenyl group having 3 to 12 carbon atoms, more preferably a cycloalkenyl group having 4 to 10 carbon atoms, and still more preferably a cycloalkenyl group having 5 to 8 carbon atoms, and examples thereof include cyclopentenyl and cyclohexenyl.

[0066] The aromatic hydrocarbon group is preferably an aryl group having 6 to 18 carbon atoms, and still more preferably an aryl group having 6 to 10 carbon atoms, and examples thereof include phenyl and naphthyl.

[0067] In formula (1), the double line including a dashed line represents a single bond or a double bond. When the double line including a dashed line represents a double bond, there is no R c , and in formula (1), R a and R b The nitrogen atom to which they are bonded represents an imino group or an N-substituted imino group.

[0068] Ra to R c The total number of amino groups, N-substituted amino groups, and N,N-substituted amino groups that may be present is preferably from 0 to 6, more preferably from 1 to 4, and still more preferably from 1 to 2.

[0069] R a to R c The total number of imino groups and N-substituted imino groups that may be present is preferably from 0 to 4, more preferably from 1 to 3, and still more preferably from 1 to 2.

[0070] R a to R c The total number of hydroxyl groups that may be present is preferably from 0 to 6, more preferably from 1 to 4, and still more preferably from 1 to 2.

[0071] The substituents of the N-substituted amino groups, N,N-substituted amino groups, and N-substituted imino groups are the same as those of the hydrocarbon groups of R a to R c and.

[0072] R a to R c Any two of R

[0073] to R a to R c may be bonded to each other to form a ring together with the adjacent nitrogen atom. Examples of the formed ring include pyrrolidine ring, pyrroline ring, piperidine ring, pyrrole ring, imidazoline ring, imidazole ring, piperazine ring, pyridine ring, diazine ring, and triazine ring.

[0074] Specific examples of the basic compound represented by formula (1) include alkylamines, wherein, in formula (1), at least one of R a to R c is a straight-chain or branched-chain alkyl group; monoalkanolamines, wherein, in formula (1), R a and R b are hydrogen atoms, and R cis a linear or branched alkyl group having one hydroxyl group; a dialkanolamine, wherein, in formula (1), R a is a hydrogen atom, and R b and R c are the same as or different from each other and each represents a linear or branched alkyl group having one hydroxyl group; a trialkanolamine, wherein, in formula (1), R a to R c are the same as or different from each other and each represents a linear or branched alkyl group having one hydroxyl group; an aminoalkanediol, wherein, in formula (1), R a and R b are the same as or different from each other and each represents a hydrogen atom or a linear or branched alkyl group, and R c represents a linear or branched alkyl group having two hydroxyl groups; a diamine, wherein, in formula (1), R a to R c have a total of one amino group; a triamine, wherein, in formula (1), R a to R c have a total of two amino groups; a diaminoalkanol, wherein, in formula (1), R a to R c have a total of one amino group and a total of one hydroxyl group; an imidazole compound, wherein, in formula (1), R a to R c each have a total of one imino group and form a ring through the nitrogen atom incorporating the imino group; and a nitrogen-containing aromatic compound (pyridine compound, diazine compound, triazine compound, etc.), wherein, in formula (1), the nitrogen atom to which R a and R b are bonded is an imino group and forms a ring through incorporating the imino group.

[0075] Examples of alkylamines include methylamine, ethylamine, propylamine, butylamine, pentylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, piperidine, trimethylamine, triethylamine, dimethyldodecylamine, 4-dimethylaminopyridine, 2-aminopyrazine, 2-aminopyrimidine, 3-aminopyridazine, 2-aminotriazine, diazabicyclononene, and diazabicycloundecene.

[0076] Examples of monoalkanolamines 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, 1-dimethylamino-2-propanol, N-propyl-2-aminoethanol, 2-dimethylaminoethanol, 6-diethylaminohexanol, 1-(2-hydroxyethyl)pyrrolidine, 2-(hydroxymethyl)pyrrolidine, 2-(2-hydroxyethyl)-1-methylpyrrolidine, 1-piperidinoethanol, and 1-ethanol-4-propylpiperidine.

[0077] Examples of dialkanolamines include diethanolamine, di-n-propanolamine, diisopropanolamine, di-n-butanolamine, diisobutanolamine, N-methyl-diethanolamine, and N-ethyl-diethanolamine.

[0078] Examples of trialkanolamines include triethanolamine, tri-n-propanolamine, triisopropanolamine, tri-n-butanolamine, and triisobutanolamine.

[0079] Examples of aminoalkanediols 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.

[0080] Examples of diamines 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'-dimethyl-ethylenediamine, N,N'-diethyl-ethylenediamine, 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, N,N-dimethyl-ethylenediamine, N,N-dimethyl-1,3-propanediamine, N,N-dimethyl-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.

[0081] Examples of the triamine include diethylenetriamine, N,N,N’,N”,N”-pentamethyldiethylenetriamine, N,N,N’,N”,N”-penta(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-triazoundecane, N-(2-aminoethyl)piperazine, 1,4,7-triazacyclononane, N,N,N’,N”,N”-penta(2-hydroxypropyl)diethylenetriamine, 1-(2-aminoethyl)-4-methylpiperazine, and 1-(2-dimethylaminoethyl)-4-methylpiperazine.

[0082] 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-methylpiperazin-1-ethanol, and 1,4-bis(2-hydroxyethyl)piperazine.

[0083] 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.

[0084] Examples of the nitrogen-containing aromatic compound include pyridine, α-methylpyridine, β-methylpyridine, γ-methylpyridine, 2,6-dimethylpyridine, 2,3-dimethylpyridine, pyrazine, 2-hydroxypyrazine, pyrimidine, 2-hydroxypyrimidine, 4-hydroxypyrimidine, pyridazine, 3-hydroxypyridazine, 4-hydroxypyridazine, triazine, and 2-hydroxytriazine.

[0085] The basic compound contained in the solvent composition according to the first and second aspects of the present disclosure is preferably a chelating coordination basic compound having an ethylenediamine structure or an ethanolamine structure in its molecular structure, because the metal ions formed when the metal oxide on the surface of the metal member dissolves are easily stabilized by chelating coordination. The amino group in the structure can be any of primary, secondary, and tertiary amino groups, but preferably a tertiary amino group, because it is less likely to cause side reactions such as amidation between the reducing organic matter and the basic compound.

[0086] The content of the basic compound relative to 1 part by weight of the reducing organic substance is preferably 0.25 to 10.0 parts by weight, more preferably 0.50 to 5.0 parts by weight, and still more preferably 0.75 to 3.0 parts by weight, because it is easier to adjust the following molar ratio (basic group / acidic group).

[0087] The basic compound preferably contains, together with the chelating coordination basic compound, an alkylamine having at least one straight-chain alkyl group having 1 to 20 carbon atoms (preferably 1 to 15 carbon atoms), because it has a relatively low polarity and thus it is easy to adjust the viscosity and wettability of the solvent composition. The content of the alkylamine relative to 1 part by weight of the reducing organic substance is preferably 0.01 to 1 part by weight, more preferably 0.05 to 0.75 part by weight, and still more preferably 0.1 to 0.5 part by weight.

[0088] The basic compound can be used alone, or two or more of them can be used in combination.

[0089] In the solution composition of the present disclosure, the ratio (basic group / acidic group) of the total number of moles of the basic groups contained in the basic compound to the total number of moles of the acidic groups contained in the reducing organic substance is preferably 0.40 to 2.50, more preferably 0.45 to 2.40, and still more preferably 0.50 to 2.30. When the molar ratio is 0.40 or more, the reducing agent is thermally stable, the reduction is easy to proceed during heating, and the metal ions eluted from the surface of the metal member are easily stabilized. In addition, when the molar ratio is 2.50 or less, the influence of the organic residue remaining after the solvent is dried on sintering is reduced. Here, the total number of moles of the acidic groups contained in the reducing organic substance is obtained 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 total number of moles of the basic groups contained in the basic compound is obtained by multiplying the number of moles of the basic compound by the number of basic groups contained in the basic compound.

[0090] <Coordination organic compound>

[0091] The coordination organic compound contained in the solution composition according to the second aspect of the present disclosure is a coordination organic compound other than the compound included as the basic compound. Since the coordination organic compound has a higher boiling point than the reducing organic substance, it is more likely to remain compared to the reducing organic substance during the sintering process, and it is easier to limit the contact between the reducing organic substance and the active metal surface, and thus it is easier to limit the decomposition of the reducing organic substance.

[0092] Examples of the coordination organic compound include compounds having a carboxyl group (carboxylic acids, etc.), compounds having a keto group (e.g., diketones such as acetylacetone and β-keto esters), and compounds having a hydroxyl group, a sulfo group, and a thiol group. Among these, the compound having a carboxyl group (carboxylic acids, etc.) is preferred because it allows the dissolved metal oxide to easily precipitate as metal nanoparticles.

[0093] The compound having a carboxyl group is preferably a monovalent or divalent carboxylic acid, and more preferably a monovalent carboxylic acid because the precipitated metal nanoparticles are likely to sinter.

[0094] Examples of the carboxylic acid 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), n-caproic acid (boiling point: 205 °C), succinic acid (boiling point: 235 °C), n-octanoic acid (boiling point: 237 °C), tartaric acid (boiling point: 275 °C), and oxalic acid (boiling point: 365 °C). Since the carboxylic acid can act as a reducing organic compound or a coordination organic compound, when the carboxylic acid is used as a reducing organic compound, other carboxylic acids having a higher boiling point than the carboxylic acid can be used in combination as a coordination organic compound.

[0095] The boiling point of the carboxylic acid at normal pressure is preferably higher than 110 °C, more preferably 150 °C or higher, and still more preferably 200 °C or higher because the carboxylic acid is less likely to volatilize compared with formic acid (boiling point: 101 °C).

[0096] In the solution composition according to the second aspect of the present disclosure, the content of the coordination organic compound relative to 1 part by weight of the reducing organic compound is preferably 0.05 to 1.00 part by weight, more preferably 0.10 to 0.75 part by weight, and still more preferably 0.15 to 0.50 part by weight. When the content is 0.05 part by weight or more, the metal nanoparticles are likely to precipitate, and when the content is 1.00 part by weight or less, the solution composition is less likely to remain during the sintering process.

[0097] In the solution composition according to the second aspect of the present disclosure, the molar ratio of the coordination organic compound to the basic compound (coordination organic compound / basic compound) is preferably 0.01 to 1.00, more preferably 0.05 to 0.50, and still more preferably 0.10 to 0.40. When the molar ratio is 0.01 or more, the metal nanoparticles may precipitate, and when the molar ratio is 1.00 or less, the solution composition is less likely to remain during the sintering process.

[0098] <Solvent>

[0099] The solvent compositions according to the first and second aspects of the present disclosure may further contain solvents such as water or organic solvents in addition to the above-mentioned reducing organic compounds, basic compounds, and coordinating organic compounds in order to adjust fluidity (viscosity) and workability. Examples of organic solvents include ester solvents such as acetate esters (ethyl acetate, butyl acetate, etc.) and ester oils (butyl stearate, hexyl laurate, triethyl citrate, etc.); ether solvents such as dioxane and tetrahydrofuran; ketone solvents such as acetone; aromatic compound solvents such as toluene and xylene; halogen solvents such as dichloromethane and chloroform; alcohol solvents such as methanol, ethanol, isopropanol, and butanol; and nitrile solvents such as acetonitrile and benzonitrile. These may be used alone, or two or more of them may be used in combination.

[0100] The content of the solvent relative to 1 part by weight of the reducing organic compound is preferably 0 to 200 parts by weight, more preferably 0.10 to 100 parts by weight, still more preferably 0.20 to 40 parts by weight, particularly preferably 0.50 to 10 parts by weight, and most preferably 1 to 5 parts by weight.

[0101] The solvent compositions according to the first and second aspects of the present disclosure may contain other components, for example, resin components (for example, high molecular compounds having a number average molecular weight of 10,000 or more, such as ethyl cellulose resin, alkyl cellulose resin, polyvinyl acetal resin, and acrylic resin), additives (surface modifiers, leveling agents, defoaming agents, dispersants, thixotropy imparting agents, etc.), as long as the effects of the present disclosure are not impaired. The content of other components in the solvent composition is, for example, 1% by weight or less (preferably 0.5% by weight or less).

[0102] The solvent compositions according to the first and second aspects of the present disclosure can be produced according to a method of mixing the reducing organic compound, the basic compound, the coordinating organic compound, the solvent, and other components.

[0103] Preferably, the temperature during the mixing process does not exceed 100°C.

[0104] For cooling after mixing, the mixture can be cooled to below room temperature (for example, 25°C), can be gradually cooled to room temperature, or can be rapidly cooled by ice cooling or the like.

[0105] [Method for producing a solvent-treated metal member]

[0106] A solvent-treated metal member can be produced by applying the solvent composition according to the first and second aspects of the present disclosure to a metal member. In the solvent-treated metal member, the solvent composition is used to dissolve and remove the metal oxide film on the surface. Further, when using the solvent-treated metal member, depending on the solvent composition remaining on the surface during the sintering process, a sintered body and a joined body having excellent conductivity can be produced even without a reducing atmosphere.

[0107] In addition, when the solvent composition according to the second aspect of the present disclosure is applied to a metal member, the metal oxide film on the surface is dissolved and removed, and a solvent-treated metal member having the surface of the metal member can be produced, on which metal nanoparticles having a number average particle diameter of less than 600 nm (1 nm or more and less than 600 nm, 5 nm or more and less than 100 nm, or 10 nm or more and less than 60 nm) are precipitated. That is, when the second solvent composition of the present disclosure is used, a metal member having metal nanoparticles on its surface can be produced by applying the solvent composition to the metal member, dissolving at least a part of the surface of the metal member to form a metal complex, and thermally decomposing and / or reductively decomposing the formed metal complex to precipitate metal nanoparticles on the surface of the metal member. The thermal decomposition and / or reductive decomposition is achieved by heating in the presence of a reducing organic substance. Since the metal member has nano metal particles on its surface, it can be sintered at a lower temperature. For example, the number average particle diameter of the metal nanoparticles can be calculated based on the number observed under an electron microscope.

[0108] The metal member can be any member for forming a conductive film, a conductive circuit, or a conductive joint, and is the target to which the solvent composition is applied, and has various forms and shapes, and examples thereof include an aggregate of metal particles and its semi-sintered body, a woven metal fiber fabric, a non-woven metal fiber fabric, and a metal member having a dense internal structure having a surface for joining with an object to be joined.

[0109] Examples of the metal for forming the metal member include gold, silver, copper, nickel, palladium, tin, aluminum, and their alloys. Among these, since copper and silver may form a metal oxide film on the surface, when the solvent composition is used, the improvement effect of obtaining a sintered body and a joined body having excellent conductivity is remarkable.

[0110] The shape of the metal particles contained in the aggregate as the metal member can be various shapes such as a spherical shape, an elliptical flake shape (flat shape), and a short fiber shape, or can be an irregular shape. These can be used alone, or two or more of them can be used in combination.

[0111] The volume average particle diameter (median size, D 50 ) of the metal particles for forming the aggregate as the metal member can be, for example, 1 nm to 100 μm, and when the second solvent composition is applied, since metal nanoparticles are precipitated, the volume average particle diameter can be 600 nm or more (600 nm to 100 μm or 1 to 10 μm). The average particle diameter of the metal particles can be measured, for example, by a laser diffraction / scattering method.

[0112] When producing a solvent-treated metal member, the amount of metal nanoparticles precipitated can be adjusted by separately dissolving a metal compound in the solvent composition according to the first and second aspects of the present disclosure and then applying the solvent composition.

[0113] As the metal compound to be dissolved, a metal compound containing copper is preferred because easily sinterable copper nanoparticles precipitate, and copper(II) oxide, copper(I) oxide, or copper(II) hydroxide is more preferred because it does not require a large amount of time or effort for storage. These can be used alone, or two or more of them can be used in combination.

[0114] A sintered object can be obtained by heating the solvent-treated metal member obtained by the production method, and a joined object can be obtained by bringing the solvent-treated metal member into contact with the object to be joined and heating.

[0115] The joined object can be an object in which the solvent composition according to the first or second aspect of the present disclosure is applied to a metal particle aggregate layer formed on the surface of a substrate to form a treated aggregate layer, and then the object to be joined and the treated aggregate layer are brought into contact with each other and heated to join the substrate and the object to be joined.

[0116] The substrate is not particularly limited as long as it can be joined through the treated aggregate layer, and examples thereof include substrates formed of metals (including alloys), ceramics (metal oxides, metal nitrides, silicon, silicon nitride, aluminum nitride, etc.), glass, polymer materials, etc., substrates formed of the above materials that have been surface-treated by metal plating, and multilayer boards obtained by combining the above materials.

[0117] The object to be joined is not particularly limited as long as it can be joined through the solvent-treated metal member or the treated aggregate layer, and examples thereof include semiconductor chips (capacitors, transistors, diodes, MOS FETs, discrete semiconductors such as IGBTs, and integrated circuits such as ICs and LSIs), compound semiconductor chips (GaN, SiC, etc.), electrical and electronic components such as heat sinks, bus bars for in-vehicle components, connectors, and wire harnesses.

[0118] The heating can be carried out, for example, in a temperature range of 100°C to 400°C (120°C to 300°C or 150°C to 250°C). The heating time can be, for example, 1 to 120 minutes (or 5 to 60 minutes). In addition, for example, the joined object (laminate) can be pressed against the joining surface under a pressure of 10 Mpa or less.

[0119] The solvent-treated metal member and the treated aggregate layer can be used for semiconductor bonding, wire bonding, clip bonding, forming wirings on a wiring board, forming a multilayer printed wiring board, forming bumps, bonding between bumps, etc., and can be suitably used for manufacturing electronic devices (printed wiring boards, capacitors, inductors, varistors, thermistors, transistors, speakers, actuators, antennas, solid oxide fuel cells, hybrid ICs, etc.), rotating electrical machines, etc.

[0120] The configurations and their combinations in the above embodiments are merely examples, and additions, omissions, substitutions, and other modifications can be appropriately made to the configurations without departing from the spirit and scope of the present disclosure. The present disclosure is not limited to the embodiments, but is only limited by the scope of the claims.

[0121] Embodiments

[0122] Hereinafter, the present disclosure will be described in more detail with reference to the embodiments, but the present disclosure is not limited to these embodiments.

[0123] The reducing organic compound, basic compound, coordinating organic compound, solvent, and metal particles (copper particles) used are as follows.

[0124] <Reducing organic compound>

[0125] · Formic acid: a reagent (commercially available from FUJIFILM Wako Pure Chemical Corporation)

[0126] · Oxalic acid: a reagent (commercially available from FUJIFILM Wako Pure Chemical Corporation)

[0127] <Basic compound>

[0128] · MDETA: N-methyldiethanolamine, a reagent (commercially available from FUJIFILM Wako Pure Chemical Corporation)

[0129] · PMDTA: pentamethyldiethylenetriamine, a reagent (commercially available from Tokyo Chemical Industry Co., Ltd.)

[0130] · DMAMPZ: 1-(2-dimethylaminoethyl)-4-methylpiperazine, a reagent (commercially available from Tokyo Chemical Industry Co., Ltd.)

[0131] · DMDA: N,N-dimethyldodecylamine, a reagent (commercially available from Tokyo Chemical Industry Co., Ltd.)

[0132] <Coordinating organic compound>

[0133] · Acetic acid: reagent (commercially available from Fujifilm Wako Pure Chemical Corporation)

[0134] · nHxA: n-Hexanoic acid, reagent (commercially available from Tokyo Chemical Industry Co., Ltd.)

[0135] · nOcA: n-Octanoic acid, reagent (commercially available from Tokyo Chemical Industry Co., Ltd.)

[0136] <Solvent>

[0137] · TEC: Triethyl citrate, reagent (commercially available from Tokyo Chemical Industry Co., Ltd.)

[0138] · EtOH: Ethanol, reagent (commercially available from Fujifilm Wako Pure Chemical Corporation)

[0139] <Copper particles>

[0140] · CH-0200L1: Product name "CH-0200L1", volume average particle diameter of 200 nm, commercially available from Mitsui Mining & Smelting Co., Ltd.

[0141] · CT-0500: Product name "CT-0500", volume average particle diameter of 800 nm, commercially available from Mitsui Mining & Smelting Co., Ltd.

[0142] (Preparation of solvent samples)

[0143] Weigh out the reducing organic compound, basic compound, coordinating organic compound and solvent and mix them in a screw tube to obtain the contents shown in Tables 1 and 2, and then stir for 1 minute at 2,000 rpm using a rotation / revolution mixer (product name "Thinky mixer", commercially available from Thinky Corporation) to prepare solvent samples 1 to 22 for evaluating the oxide film removal performance, precipitation of metal nanoparticles, conductivity and bondability.

[0144] [Table 1]

[0145]

[0146] [Table 2]

[0147]

[0148] <Examples 1 to 4 and Comparative Examples 1 and 2>

[0149] The above solvent samples were used to evaluate the "performance of removing the oxide film from the copper foil surface".

[0150] (Surface treatment of copper foil)

[0151] A copper foil with a thickness of 100 μm (product name “C1020P”) was cut into a square (5 cm × 5 cm) and heated in air at 200 °C for 10 minutes using a hot plate to prepare a test piece of oxidized copper foil having an oxide film on its surface.

[0152] Two drops (about 40 mg) of a solvent sample were added dropwise using a dropper to the center of the oxidized copper foil. The oxidized copper foil test piece was placed on a hot plate in a glove box under a nitrogen atmosphere (oxygen concentration of 100 ppm or less). The temperature was raised from room temperature (25 °C) to 150 °C at a heating rate of 10 °C / min and then held for 5 minutes, and then the temperature was raised to 200 °C at a heating rate of 10 °C / min and then held for 10 minutes. Then, the sample was naturally cooled to room temperature (25 °C), and after cooling, the sample was washed with methanol to prepare a solvent-treated copper foil.

[0153] (Measurement of the thickness of the oxide film on the copper foil surface)

[0154] Using an oxide film / metal film thickness measuring machine (product name “QC-100”, commercially available from ECITECHNOLOGY), the thickness of the oxide film formed by oxides, etc. on the surface of the treated copper foil was measured by a continuous electrochemical method. The measurement conditions are as follows. The value of the total thickness of cuprous oxide (I), cupric oxide (II), and copper sulfide obtained from the measurement results was defined as the thickness of the oxide film. The measurement was performed on the part where the droplet remained until the end when the solvent was evaporated. If the measurement could not be performed within 10 minutes of the measurement time, the thickness was as above. Table 3 shows the solvent samples used and the evaluation results. Here, the thickness of cupric oxide on the copper foil before the oxidation treatment was

[0155] · Measurement range (washer size):

[0156] · Current value: 30 μA / cm 2

[0157] · Measurement time: maximum 10 minutes

[0158] (Evaluation criteria for oxide film removal performance)

[0159] The performance of removing the oxide film from the copper foil surface was evaluated according to the following criteria.

[0160] ○ (Good): Below

[0161] Δ (Fair): Greater than and less than

[0162] ×(difference): and above

[0163] [Table 3]

[0164] Table 3

[0165]

[0166] Examples 1 to 4 were evaluated as ○ or Δ, indicating that the oxide film was successfully removed by treatment with the solvent composition of the present disclosure. On the other hand, Comparative Examples 1 and 2, which did not contain an alkaline compound, were evaluated as ×, indicating poor oxide film removal performance.

[0167] <Examples 5 to 14 and Comparative Example 3>

[0168] "Precipitation of metal nanoparticles on the copper foil surface" was evaluated. For the evaluation, a solvent-treated copper foil prepared in the same manner as in the evaluation of "performance of removing the oxide film from the copper foil surface" was used.

[0169] (copper foil surface)

[0170] It was determined whether metal nanoparticles were precipitated based on observations under an electron microscope. When the precipitation of metal nanoparticles was observed, the particle sizes of 100 metal nanoparticles were measured, and the average value was calculated to obtain the number-average particle size. Table 4 shows the solvent samples used and the evaluation results. In addition, Figures 1 to 3 shows the electron microscope images of Example 6, Example 11, and Comparative Example 3 ( Figure 1 lower right column in: 1 μm, Figure 2 lower right column in: 100 nm, Figure 3 lower right column in: 1 μm).

[0171] [Table 4]

[0172] Table 4

[0173]

[0174] The "-" in the particle size column indicates that no particle deformation was observed on the surface.

[0175] It is shown that copper nanoparticles were precipitated in Examples 8 to 14, and copper particles larger than 1,000 nm were precipitated in Examples 5 to 7 in which no coordinating organic compound was added. On the other hand, it is shown that copper particles were not precipitated in Comparative Example 3 in which no alkaline compound was contained.

[0176] <Examples 15 to 22 and Comparative Examples 4 and 5>

[0177] The above solvent sample was used to evaluate the "electric conductivity" of the sintered body of copper particle aggregates.

[0178] (Preparation of copper particle aggregates)

[0179] 10.5 g of formic acid, 10.5 g of nOcA, 2.6 g of PMDTA, 10.9 g of MDEtA and 13.5 g of DMDA were mixed and then 0.5 g of polyvinyl butyral resin (product name "S-LEC B BL-1", commercially available from Sekisui Chemical Co., Ltd.) was added as an adhesive resin, and the mixture was uniformly mixed to obtain a copper paste dispersion solvent.

[0180] 10 g of copper particles CH-0200L1, 10 g of copper particles CT-0500 and 2.4 g of the copper paste dispersion solvent were stirred and mixed at 2,000 rpm for 3 minutes using a rotation / revolution mixer (product name "ARE-310", commercially available from Nissin Kikai Co., Ltd.) to obtain a copper paste.

[0181] The copper paste was formed and heated in a nitrogen atmosphere at 200 °C for 5 minutes to prepare copper particle aggregates (rectangular shape, length 50 mm, width 10 mm, thickness 20 μm). The copper particle aggregates were not sintered and did not exhibit electric conductivity.

[0182] The solvent sample was applied to the prepared copper particle aggregates, which were sintered in a nitrogen atmosphere at 200 °C for 30 minutes to obtain a sintered body, and the volume resistivity of the sintered body was measured using a resistivity meter (product name "Loresta GP MCP-T610", commercially available from Mitsubishi Chemical Analytech Co., Ltd.). A smaller volume resistivity value indicates better "electric conductivity". Table 5 shows the solvent samples used and the evaluation results.

[0183] (Evaluation criteria for electric conductivity)

[0184] The electric conductivity was evaluated according to the following criteria.

[0185] ○ (Good): Volume resistivity less than 20 μΩ·cm

[0186] Δ (Fair): Volume resistivity of 20 μΩ·cm or more and less than 100 μΩ·cm

[0187] × (Poor): Volume resistivity of 100 μΩ·cm or more

[0188] [Table 5]

[0189] Table 5

[0190]

[0191] The "-" in the particle size column indicates that no current flows and no measured value is obtained.

[0192] Examples 15 to 22 were evaluated as ○ or Δ, indicating low volume resistivity and good conductivity. On the other hand, Comparative Examples 4 and 5, which do not contain reducing organic substances or basic compounds, showed high volume resistivity and poor conductivity.

[0193] <Examples 23 to 25>

[0194] The above solvent sample was used to evaluate "bondability". For the bonding evaluation, the above copper paste used for evaluating conductivity was used.

[0195] (Example 23, Cu-Cu bonding (length 10 mm, width 10 mm))

[0196] Using a metal mask with an opening size of 10 mm × 10 mm and a thickness of 100 μm, the copper paste was printed on a copper plate with a size of 30 mm × 30 mm and a thickness of 1 mm. The copper paste was heated in a nitrogen atmosphere at 200 °C for 5 minutes to obtain an aggregate of copper particles. The solvent sample 19 was added dropwise to the aggregate of copper particles so that the solvent penetrated the entire aggregate, and a copper plate with a size of 10 mm × 10 mm and a thickness of 1 mm was placed on the aggregate of copper particles to which the solvent was applied. Then, the sample was pressed from above at 10 MPa and heated in a nitrogen atmosphere at 200 °C for 30 minutes to obtain a bonded object in which the copper plates were bonded.

[0197] The bonded object was divided into four parts, and the bonding strength was measured using a universal bonding strength tester (product name: "Chip Shear Strength Tester SERIES4000", commercially available from Nordson DAGE). The bonding strength was 40 MPa or more, indicating that the bondability was sufficiently excellent.

[0198] In addition, when the void ratio of the bonded object was measured using an ultrasonic imaging device (SAT, Scanning Acoustic Tomography device) (product name "FineSAT FS300II", commercially available from Hitachi High-Tech Corporation), the void ratio was 1% or less, indicating excellent bondability.

[0199] (Example 24, Cu-Cu bonding (length 20 mm, width 20 mm))

[0200] A metal mask with an opening size of 20 mm × 20 mm and a thickness of 150 μm was used to print copper paste on a copper plate with a size of 30 mm × 30 mm and a thickness of 1 mm, and a bonded object was obtained in the same manner as in Example 23. The porosity of the bonded object was also 1% or less. Figure 4 The SAT image of the bonded object is shown (in the figure, the white part represents voids).

[0201] (Example 25, Bonding between Microelectrodes)

[0202] A Si chip with copper bumps (product name "WALTS-TEG CC40", 10 mm × 10 mm, commercially available from Walters Co., Ltd.) having a pattern in which 28,224 (168 × 168) copper bumps (height 15 μm, ) are arranged at intervals of 40 μm within a range of 10 mm × 10 mm, and a Si interposer (product name "WALTS-TEG IP40", commercially available from Walters Co., Ltd.) having copper pads corresponding to the pattern were used. Figure 5 The electron microscope image of the arrangement pattern of the copper bumps is shown, and Figure 6 The electron microscope image of the surface of the copper bump portion is shown ( Figure 5 lower right column in: 10 μm, Figure 6 lower right column in: 100 nm).

[0203] The Si chip with copper bumps was heated on a hot plate at 200 °C in the atmosphere for 5 minutes, and the surface of the copper bumps was oxidized.

[0204] 5 μL of solvent sample 7 was applied to the oxidized Si chip with copper bumps using a micropipette, and then the sample was placed on a hot plate in a glove box under a nitrogen atmosphere (oxygen concentration 100 ppm or less). The temperature was raised from room temperature (25 °C) to 150 °C at a heating rate of 10 °C / min and then held for 5 minutes, then the temperature was raised to 200 °C at a heating rate of 10 °C / min and then held for 10 minutes, and then the sample was naturally cooled to room temperature (25 °C). After cooling, the sample was washed with methanol to obtain a solvent-treated Si chip. Figure 7 The electron microscope image of the surface of the copper bump portion of the solvent-treated Si chip is shown ( Figure 7 lower right column in: 100 nm). Copper nanoparticles were precipitated on the surface of the copper bumps.

[0205] Using a micropipette, 5 μL of solvent sample 19 was applied to the Si interposer to obtain a solvent-coated Si interposer. The solvent-coated Si interposer and the solvent-treated Si chip were laminated such that the solder pads were positioned corresponding to the copper bumps, and were joined by using a flip chip bonder (product name “T-3000-PRO-HF”, commercially available from Dr. TRESKY Co., Ltd.) by heating at 200 °C for 10 minutes under a load of 5 kgf in a nitrogen atmosphere.

[0206] The bonding strength of the bonded object was measured using a universal bonding strength testing machine (product name: “Chip Shear Strength Tester SERIES4000”, commercially available from Nordson Corporation). The bonding strength was 25 MPa, indicating that the strength was sufficient and the bondability was excellent.

[0207] Hereinafter, variants of the invention according to the present disclosure will be described.

[0208] [Appendix 1] A solvent composition for a sintering aid, the solvent composition comprising a reducing organic substance and a basic compound.

[0209] [Appendix 2] A solvent composition comprising a reducing organic substance, a basic compound, and a coordinating organic compound other than the compound included as the basic compound, wherein the coordinating organic compound has a higher boiling point than the reducing organic substance.

[0210] [Appendix 3] The solvent composition according to Appendix 1 or 2, wherein the reducing organic substance is formic acid.

[0211] [Appendix 4] The solvent composition according to Appendix 3, which further comprises a reducing organic substance other than formic acid.

[0212] [Appendix 5] The solvent composition according to Appendix 4, wherein the reducing organic substance other than formic acid is oxalic acid.

[0213] [Appendix 6] The solvent composition according to Appendix 4 or 5, wherein the content of the reducing organic substance other than formic acid is 1 mole part or less relative to 1 mole of formic acid.

[0214] [Appendix 7] The solvent composition according to any one of Appendices 1 to 6, wherein the basic compound is a nitrogen-containing compound represented by the following formula (1):

[0215] [C1]

[0216]

[0217] (In formula (1), R a to R cidentical to or different from each other and each represents a hydrogen atom or a hydrocarbon group which may have substituents; these substituents are identical to or different from each other and are at least one group selected from the group consisting of 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; provided that R a to R c are not simultaneously hydrogen atoms; the double line including a dashed line represents a single bond or a double bond, and when the double line is a double bond, R c does not exist; and any two of R a to R c can be bonded to each other to form a ring together with the adjacent nitrogen atom).

[0218] [Appendix 8] The solvent composition according to any one of Appendices 1 to 7, wherein the basic compound has an ethylenediamine structure or an ethanolamine structure in its molecular structure, and the amino group in the structure is a tertiary amino group.

[0219] [Appendix 9] The solvent composition according to any one of Appendices 1 to 8, wherein the basic compound is at least one selected from dialkanolamines and triamines.

[0220] [Appendix 10] The solvent composition according to Appendix 9, wherein the basic compound is at least one selected from N-methyldiethanolamine, pentamethyldiethylenetriamine and 1-(2-dimethylaminoethyl)-4-methylpiperazine.

[0221] [Appendix 11] The solvent composition according to any one of Appendices 1 to 10, wherein the basic compound includes, together with a chelating coordination basic compound, an alkylamine having at least one straight-chain alkyl group having 1 to 20 carbon atoms (preferably 1 to 15 carbon atoms).

[0222] [Appendix 12] The solvent composition according to Appendix 11, wherein the alkylamine is N,N-dimethyldodecylamine.

[0223] [Appendix 13] The solvent composition according to Appendix 11 or 12, wherein the content of the alkylamine relative to 1 part by weight of the reducing organic substance is 0.01 to 1 part by weight (preferably 0.05 to 0.75 part by weight, and more preferably 0.1 to 0.5 part by weight).

[0224] [Appendix 14] The solvent composition according to any one of Appendices 1 to 13, wherein the content of the basic compound relative to 1 part by weight of the reducing organic substance is 0.25 to 10.0 parts by weight (preferably 0.50 to 5.0 parts by weight, and more preferably 0.75 to 3.0 parts by weight).

[0225] [Appendix 15] The solvent composition according to any one of Appendices 1 to 14, wherein the ratio (basic group / acidic group) of the total number of moles of the basic groups contained in the basic compound to the total number of moles of the acidic groups contained in the reducing organic substance is 0.40 to 2.50 (preferably 0.45 to 2.40, and more preferably 0.50 to 2.30).

[0226] [Appendix 16] The solvent composition according to any one of Appendices 2 to 15, wherein the coordinating organic compound is a compound having a carboxyl group.

[0227] [Appendix 17] The solvent composition according to Appendix 16, wherein the compound having a carboxyl group is a monovalent or divalent (preferably monovalent) carboxylic acid.

[0228] [Appendix 18] The solvent composition according to Appendix 17, wherein the carboxylic acid has a boiling point higher than 110 °C (preferably 150 °C or higher, and more preferably 200 °C or higher) under normal pressure.

[0229] [Appendix 19] The solvent composition according to any one of Appendices 2 to 18, wherein the content of the coordinating organic compound relative to 1 part by weight of the reducing organic substance is 0.05 to 1.00 part by weight (preferably 0.10 to 0.75 part by weight, and more preferably 0.15 to 0.50 part by weight).

[0230] [Appendix 20] The solvent composition according to any one of Appendices 2 to 19, wherein the molar ratio (coordinating organic compound / basic compound) of the coordinating organic compound to the basic compound is 0.01 to 1.00 (preferably 0.05 to 0.50, and more preferably 0.10 to 0.40).

[0231] [Appendix 21] The solvent composition according to any one of Appendices 1 to 20, which further comprises a solvent.

[0232] [Appendix 22] The solvent composition according to Appendix 21, wherein the solvent is at least one selected from ester solvents and alcohol solvents.

[0233] [Appendix 23] The solvent composition according to Appendix 21, wherein the solvent is at least one selected from triethyl citrate and ethanol.

[0234] [Appendix 24] The solvent composition according to any one of Appendices 1 to 23, wherein the content of the solvent relative to 1 part by weight of the reducing organic substance is 0 to 200 parts by weight (preferably 0.10 to 100 parts by weight, more preferably 0.20 to 40 parts by weight, still more preferably 0.50 to 10 parts by weight, and particularly preferably 1 to 5 parts by weight).

[0235] [Appendix 25] A method for producing a solvent-treated metal member, the method comprising applying a solvent composition according to any one of Appendices 1 to 24 to the metal member.

[0236] [Appendix 26] The method for producing a solvent-treated metal member according to Appendix 25, wherein the metal member is an aggregate of metal particles having a volume average particle diameter of 1 nm to 100 μm before application.

[0237] [Appendix 27] A method for producing a solvent-treated metal member, the method comprising applying a solvent composition according to any one of Appendices 2 and 16 to 24 to the metal member, wherein the solvent-treated metal member has a metal member surface on which metal nanoparticles having a number average particle diameter of less than 600 nm (more than 1 nm and less than 600 nm, more than 5 nm and less than 100 nm, or more than 10 nm and less than 60 nm) are deposited.

[0238] [Appendix 28] The method for producing a solvent-treated metal member according to Appendix 27, wherein the metal member is an aggregate of metal particles having a volume average particle diameter of 600 nm or more (600 nm to 100 μm, or 1 to 10 μm) before application.

[0239] [Appendix 29] The method for producing a solvent-treated metal member according to any one of Appendices 25 to 28, wherein a metal compound is dissolved in a solvent composition according to any one of Appendices 1 to 24 and then the solvent composition is applied to the metal member.

[0240] [Appendix 30] The method for producing a solvent-treated metal member according to any one of Appendices 25 to 29, wherein the metal member contains copper.

[0241] [Appendix 31] The method for producing a solvent-treated metal member according to Appendix 29 or 30, wherein the metal compound is at least one selected from cuprous oxide (I), cupric oxide (II), and cupric hydroxide (II).

[0242] [Appendix 32] A method for producing a sintered body, the method comprising heating a solvent-treated metal member obtained by the production method according to any one of Appendices 25 to 31 to obtain a sintered body.

[0243] [Appendix 33] A method for producing a joined body, the method comprising bringing a solvent-treated metal member obtained by the production method according to any one of Appendices 25 to 31 into contact with an object to be joined and heating it to obtain a joined body.

[0244] [Appendix 34] A method for producing a joined object, the method comprising applying a solvent composition according to any one of Appendices 1 to 24 to a layer of metal particle aggregates formed on a substrate surface to form a treated aggregate layer, then bringing the object to be joined into contact with the treated aggregate layer, and heating the same to join the substrate and the object to be joined.

[0245] [Appendix 35] A method for producing a metal member having metal nanoparticles on its surface, the method comprising applying a solvent composition to the metal member, dissolving at least a part of the surface of the metal member to form a metal complex, and thermally decomposing and / or reductively decomposing the formed metal complex to deposit metal nanoparticles on the surface of the metal member.

Claims

1. A solvent composition for a sintering aid, the solvent composition comprising a reducing organic substance and a basic compound.

2. A solvent composition, the solvent composition comprising a reducing organic substance, a basic compound, and a coordinating organic compound other than the compound included as the basic compound, wherein the coordinating organic compound has a higher boiling point than the reducing organic substance.

3. The solvent composition according to claim 1 or 2, wherein the reducing organic substance is formic acid.

4. The solvent composition according to claim 3, which further comprises a reducing organic substance other than formic acid.

5. The solvent composition according to claim 1 or 2, wherein the basic compound is a nitrogen-containing compound represented by the following formula (1): (In formula (1), R a to R c are the same as or different from one another and each represents a hydrogen atom or a hydrocarbon group which may have substituents; these substituents are the same as or different from one another and are at least one group selected from the group consisting of amino, N-substituted amino, N,N-substituted amino, imino, N-substituted imino and hydroxy; provided that R a to R c are not simultaneously hydrogen atoms; the double line including the dashed line represents a single bond or a double bond, and when the double line represents a double bond, R c does not exist; and any two of R a to R c may be bonded to each other to form a ring together with the adjacent nitrogen atom).

6. The solvent composition according to claim 1 or 2, wherein the basic compound has an ethylenediamine structure or an ethanolamine structure in its molecular structure, and the amino group in the structure is a tertiary amino group.

7. The solvent composition according to claim 1 or 2, wherein the ratio (basic group / acetic group) of the total number of moles of the basic groups contained in the basic compound to the total number of moles of the acidic groups contained in the reducing organic substance is 0.40 to 2.

50.

8. The solvent composition according to claim 2, wherein the coordinating organic compound is a compound having a carboxyl group.

9. The solvent composition according to claim 1 or 2, which further comprises a solvent.

10. A method for producing a solvent-treated metal member, the method comprising applying the solvent composition according to claim 1 or 2 to the metal member.

11. The method for producing a solvent-treated metal member according to claim 10, wherein the metal member is an aggregate of metal particles having a volume average particle diameter of 600 nm or more before application.

12. A method for producing a solvent-treated metal member, the method comprising dissolving a metal compound in the solvent composition according to claim 1 or 2 and then applying the solvent composition to the metal member.

13. The method for producing a solvent-treated metal member according to claim 10, wherein the metal member contains copper.

14. The method for producing a solvent-treated metal member according to claim 12, wherein the metal compound is at least one selected from cuprous oxide (I), cupric oxide (II), and cupric hydroxide (II).

15. A method for producing a sintered object, the method comprising heating the solvent-treated metal member obtained by the production method according to claim 10 to obtain a sintered object.

16. A method for producing a joined object, the method comprising bringing the solvent-treated metal member obtained by the production method according to claim 10 into contact with an object to be joined and heating it to obtain a joined object.

17. A method for producing a joined object, the method comprising applying the solvent composition according to claim 1 or 2 to a layer of metal particle aggregates formed on a substrate surface to form a treated aggregate layer, then bringing the object to be joined into contact with the treated aggregate layer, and heating it to join the substrate and the object to be joined.

18. A method for producing a metal member having metal nanoparticles on its surface, the method comprising applying a solvent composition to the metal member, dissolving at least a part of the surface of the metal member to form a metal complex, and thermally decomposing and / or reductively decomposing the formed metal complex to deposit metal nanoparticles on the surface of the metal member.

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