阅读说明：本技术 助焊剂和焊锡膏 (Soldering flux and solder paste ) 是由 北泽和哉 桥本裕 津田竜一 白鸟正人 高木善范 川崎浩由 于 2019-07-19 设计创作，主要内容包括：本发明的目的在于提供可提高增粘抑制效果的助焊剂和焊锡膏。本发明的助焊剂为含有金属钝化剂的助焊剂,金属钝化剂含有酰肼类氮化合物。(The invention aims to provide a soldering flux and a soldering paste which can improve the thickening inhibition effect. The soldering flux is the soldering flux containing a metal passivator, and the metal passivator contains hydrazide nitrogen compounds.)

1, kinds of scaling powder, the scaling powder is the scaling powder which contains metal passivator, characterized in that, the metal passivator contains hydrazide type nitrogen compound.

2. The flux of claim 1, wherein the content of the hydrazide-type nitrogen compound is more than 0 and 10 mass% or less with respect to the entire flux.

3. The flux according to claim 1, wherein the hydrazide-type nitrogen compound is contained in an amount of 0.01 to 1.00 mass% based on the entire flux.

4. The solder flux of any of claims 1 to 3, wherein the hydrazide-type nitrogen compound is bis [2- (2-hydroxybenzoyl) hydrazide ] dodecanedioic acid.

5. The flux of any , wherein the flux comprises a resin selected from the group consisting of rosin-based resins and acrylic resins of or more.

6. The flux according to claim 5, wherein the resin is contained in an amount of 30 to 60 mass% based on the entire flux.

Solder paste of the kind 7, , characterized in that it consists of solder material and the soldering flux of any of the claims from 1 to 6.

8. Solder paste according to claim 7, wherein the solder material comprises Sn or a Sn-based alloy.

9. Solder paste according to claim 8, wherein the Sn-based alloy is a Sn-based alloy containing more than 0 and 3.5 mass% or less of Ag and/or more than 0 and 1.0 mass% or less of Cu.

10. Solder paste according to of any one of claims 7 to 9, wherein the solder paste further comprises zirconium oxide powder.

11. The solder paste as claimed in claim 10, wherein the content of the zirconia powder is 0.05 to 20.0 mass% based on the entire mass of the solder paste.

Technical Field

The invention relates to a soldering flux and a soldering paste.

Background

In terms of cost and reliability, the electronic components are often joined and assembled to the substrate of the electronic device by soldering using solder paste.

As a method of applying the solder paste to the substrate of the electronic device, for example, a screen printing method using a metal mask is used. In this case, in order to ensure printability of the solder paste, it is necessary to appropriately adjust the viscosity of the solder paste. However, the storage stability of the solder paste is deteriorated, and as a result, the viscosity of the solder paste may increase with time.

Patent document 1 discloses a solder paste composition containing a flux composition containing a rosin resin, an acrylic resin, an activator, a thixotropic agent, an antioxidant and a solvent, and at least of a phenol antioxidant, a triazole antioxidant and a phosphorus antioxidant as antioxidants, and a solder alloy powder, and discloses that the above-mentioned solder paste composition can achieve the effect of suppressing the generation and the development of cracks by suppressing the thermal degradation of flux residues even when used for an electronic circuit board placed in an environment where a difference between cold and warm temperatures is large and a thermal shock is large, and further steps can exhibit good performances such as melting property and wettability.

Patent document 2 discloses a solder paste obtained by mixing a tin-based lead-free solder powder with a rosin-based flux containing 0.01 to 10 mass% of at least salicylamide compounds selected from salicylamide and derivatives thereof, and discloses that the salicylamide compounds are preferentially adsorbed on the surface of the solder powder, whereby the reaction between the solder powder and components of the flux, particularly an activator called an organic amine hydrohalide or an organic acid, can be prevented, and the viscosity of the solder paste can be prevented from being changed by the reaction.

Disclosure of Invention

Accordingly, an object of the present invention is to provide a flux and a solder paste which can improve the effect of suppressing thickening.

The present inventors have made extensive studies to solve the above problems, and as a result, have found that the above problems can be solved by using a flux containing a metal deactivator containing a hydrazide-based nitrogen compound as the metal deactivator, and have completed the present invention.

Namely, the soldering flux of the invention is the soldering flux containing the metal passivator, and the metal passivator contains the hydrazide nitrogen compound.

The solder paste of the present invention is composed of a solder material and the flux of the present invention.

Effects of the invention

The present invention can provide a flux and a solder paste which can improve the effect of suppressing thickening.

Detailed Description

Hereinafter, a mode for carrying out the present invention (hereinafter, referred to as "the present embodiment") will be described. However, the present invention is not limited to this, and various modifications can be made without departing from the scope of the invention.

In the present specification, the "thickening-inhibiting effect" means an effect of inhibiting a viscosity increase of the prepared solder paste with time when preparing the solder paste.

It is worth noting that: in the present specification, the content of each element can be measured by, for example, ICP-AES analysis based on JIS Z3910.

[ flux ]

The flux of the present embodiment contains a metal deactivator. The metal passivator contains a hydrazide type nitrogen compound. The soldering flux can improve the tackifying and inhibiting effects by containing the hydrazide nitrogen compound in the metal passivator. Therefore, the flux is suitable for use as a soldering flux, for example.

(Metal deactivator)

The metal deactivator contains a hydrazide-based nitrogen compound, and examples of the hydrazide-based nitrogen compound include bis [2- (2-hydroxybenzoyl) hydrazide ] dodecanedioate, N '-bis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl ] hydrazine, disalicylhydrazide sebacate, N-salicylidene-N' -salicyloyl hydrazide, m-nitrophenyl hydrazide, 3-aminophthalic hydrazide, phthalic dihydrazide, adipic acid hydrazide, oxalyl bis (2-hydroxy-5-octylbenzylidene hydrazide), N '-benzoylpyrrolidone carboxylic acid hydrazide, N' -bis (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hydrazine, and the like, and among these hydrazide-based nitrogen compounds, are used alone or two or more are used in combination, and among these, bis [2- (2-hydroxybenzoyl) dodecanedioate ] hydrazide is preferable from the viewpoint of excellent adhesion-suppressing effect.

The content of the hydrazide nitrogen compound is preferably more than 0 and 10 mass% or less with respect to the whole flux, the content is more preferably 0.01 mass% or more, further steps are preferably 0.05 mass% or more, particularly preferably 0.10 mass% or more, the content is more preferably 7.5 mass% or less, further steps are preferably 5.0 mass% or less, particularly preferably 1.0 mass% or less, and by making the content 0.01 mass% or more, the flux is excellent in the thickening suppression effect and the fluctuation suppression effect of the thixotropic ratio, and therefore, when printing is performed using a solder paste containing the flux, the filling property into the openings of a screen or a film is excellent, and the filling can be performed even if the openings are minute openings, and in addition , the flux is excellent in the thickening suppression effect and the suppression effect of the reaction with Cu at the time of the temperature cycle test in soldering, by making the content 10 mass% or less.

The metal deactivator may contain other compounds than the hydrazide-type nitrogen compound. Examples of the other compounds include amide-based nitrogen compounds, triazole-based nitrogen compounds, melamine-based nitrogen compounds, hindered phenol-based compounds, and the like.

Examples of the amide-based nitrogen compound include a nitrogen compound having an amide skeleton, such as N, N' -bis {2- [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyloxy ] ethyl } oxamide.

Examples of the triazole-based nitrogen compound include nitrogen compounds having a triazole skeleton, such as N- (2H-1,2, 4-triazol-5-yl) salicylamide, 3-amino-1, 2, 4-triazole, and 3- (N-salicyloyl) amino-1, 2, 4-triazole.

The melamine-based nitrogen compound may be a nitrogen compound having a melamine skeleton, and examples thereof include melamine and melamine derivatives.

Examples of the hindered phenol compound include a compound having a hindered phenol skeleton such as triethylene glycol ether bis (3-t-butyl-4-hydroxy-5-methylphenyl) propionate, N '-hexamethylenebis [3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionamide ], 1, 6-hexanediol bis [3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate ], 2' -methylenebis [6- (1-methylcyclohexyl) p-cresol ], 2 '-methylenebis (6-t-butyl-p-cresol), 2' -methylenebis (6-t-butyl-4-ethylphenol), triethylene glycol bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate ], (ii) ethylene glycol, propylene glycol, and mixtures thereof, 1, 6-hexanediol bis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], 2, 4-bis (N-octylthio) -6- (4-hydroxy-3, 5-di-tert-butylphenylamino) -1,3, 5-triazine, pentaerythrityl tetrakis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], 2-thiodiethylene bis [3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], octadecyl-3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate, N' -hexamethylenebis (3, 5-di-tert-butyl-4-hydroxyhydrocinnamide), Diethyl 3, 5-di-tert-butyl-4-hydroxybenzylphosphonate, 1,3, 5-trimethyl-2, 4, 6-tris (3, 5-di-tert-butyl-4-hydroxybenzyl) benzene, and the like.

The content of the hydrazide nitrogen compound in the metal deactivator may be, for example, 80 mass% or more, preferably 85 mass% or more, more preferably 90 mass% or more, further mass% or more, particularly preferably 100 mass%.

Examples of the resin include rosin-based resins, (meth) acrylic resins, polyurethane-based resins, polyester-based resins, phenoxy resins, vinyl ether-based resins, terpene resins, modified terpene resins (e.g., aromatic modified terpene resins, hydrogenated aromatic modified terpene resins, etc.), terpene phenol resins, modified terpene phenol resins (e.g., hydrogenated terpene phenol resins, etc.), styrene resins, modified styrene resins (e.g., styrene acrylic resins, styrene maleic resins, etc.), xylene resins, modified xylene resins (e.g., phenol-modified xylene resins, alkylphenol-modified xylene resins, phenol-modified toluene-type xylene resins, polyol-modified xylene resins, polyoxyethylene-added xylene resins, etc.), and or two or more of these resins are used alone or in combination.

Examples of the rosin-based resin include raw material rosins such as gum rosin, wood rosin and tall oil rosin, and derivatives obtained from the raw material rosin, examples of the derivatives include purified rosin, hydrogenated rosin, disproportionated rosin, polymerized rosin and α -unsaturated carboxylic acid modified products (acrylated rosin, maleated rosin, fumaric rosin, etc.), as well as purified products of polymerized rosin, hydrogenated products and disproportionated products, and purified products of α -unsaturated carboxylic acid modified products, hydrogenated products and disproportionated products, and these rosin-based resins are used singly in or in combination of two or more.

The content of the rosin resin may be, for example, 30 to 60 mass% with respect to the entire flux.

Examples of the (meth) acrylic resin include homopolymers of (meth) acrylic monomers and copolymers of two or more (meth) acrylic monomers, and examples of the (meth) acrylic monomers include (meth) acrylic acid, itaconic acid, maleic acid, crotonic acid, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, propyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, deca (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, lauryl (meth) acrylate, and stearyl (meth) acrylate, and kinds of these (meth) acrylic resins are used alone or in combination of two or more.

The resin can improve the temperature cycle reliability by containing a (meth) acrylic resin. When a thermal stress is applied to a solid portion or a joint portion, which is repeated at high and low temperatures, a material having high crystallinity such as rosin may crack and absorb moisture from the crack. On the other hand, the inclusion of a soft (meth) acrylic resin in the resin suppresses the above-described cracking, and as a result, the temperature cycle reliability can be improved. The content of the (meth) acrylic resin is, for example, 0 to 40% by mass relative to the entire flux, and is preferably 20 to 30% by mass from the viewpoint of excellent temperature cycle reliability. The content of the (meth) acrylic resin is, for example, 0 to 80% by mass based on the entire resin, and preferably 30 to 80% by mass from the viewpoint of excellent temperature cycle reliability.

The content of the resin is preferably 30 to 60 mass%, more preferably 35 to 55 mass%, and further preferably 40 to 50 mass% in the step , with respect to the entire flux.

To improve solderability, the flux may contain an organic acid activator (organic acid). Examples of the organic acid include adipic acid, azelaic acid, didecanedioic acid, citric acid, glycolic acid, succinic acid, salicylic acid, diglycolic acid, dipicolinic acid, dibutylanilide diglycolic acid, suberic acid, sebacic acid, thioglycolic acid, terephthalic acid, dodecanedioic acid, p-hydroxyphenylacetic acid, picolinic acid, phenylsuccinic acid, phthalic acid, fumaric acid, maleic acid, malonic acid, lauric acid, benzoic acid, tartaric acid, tris (2-carboxyethyl) isocyanurate, glycine, 1, 3-cyclohexanedicarboxylic acid, 2-bis (hydroxymethyl) propionic acid, 2-bis (hydroxymethyl) butyric acid, 2, 3-dihydroxybenzoic acid, 2, 4-diethylglutaric acid, 2-quinolinecarboxylic acid, 3-hydroxybenzoic acid, malic acid, p-anisic acid, stearic acid, and the like, 12-hydroxystearic acid, oleic acid, linoleic acid, linolenic acid, dimer acid, hydrogenated dimer acid, trimer acid, hydrogenated trimer acid, and the like.

The content of the organic acid may be, for example, 0 to 10% by mass based on the entire flux.

The flux may contain an amine activator (amine), such as an aliphatic amine, an aromatic amine, an aminoalcohol, an imidazole, a benzotriazole, an amino acid, a guanidine, a hydrazide, such as an aliphatic amine, an ethylamine, an N-propylamine, an isopropylamine, a trimethylamine, an allylamine, an N-butylamine, a diethylamine, a sec-butylamine, a tert-butylamine, an N, N-dimethylethylamine, an isobutylamine, a cyclohexylamine, such as an aniline, an N-methylaniline, a diphenylamine, an N-isopropylaniline, such as an aminoalcohol, such as a 2-aminoethanol, a 2- (ethylamino) ethanol, a diethanolamine, a diisopropanolamine, a triethanolamine, an N-butyldiethanolamine, a triisopropanolamine, an N, N-bis (2-hydroxyethyl) -N-cyclohexylamine, an N, N '-tetrakis (2-hydroxypropyl) ethylenediamine, an N, N', N "-pentakis (2-hydroxypropyl) diethylenetriamine, such as an imidazole, such as 2-methylimidazolyl, a 2-alkylbenzimidazole, a 2-butylimidazole, a-2-ethylbenzimidazole, a-2-bis (2-ethylhexylimidazole), a) benzimidazole, a-2-ethyltolyltriazole, a-2-ethyltriazole, a-2-ethyltolyltriazole, a-2-ethyltriazole, a-4-2-ethyltriazole, a-2-ethyl2-ethyltriazole, a-ethyl2-ethyltriazole, a-ethyl2-ethyltriazole, a-4-ethyltriazole, a-ethyl2-ethyltriazole, a-4-2-ethyl2-ethyltriazole, a-ethyl2-ethyltriazole, a-ethyl2-ethyltriazole, a-ethyl2-ethyltriazole, a-ethyl2-ethyltriazole, a-ethyl2-ethyltriazole, a-ethyl2-ethyltriazole, a-ethyl2-ethyltriazole, a-ethyl2-ethyltriazole, a-ethyl2-ethyltriazole, a-ethyl2-ethyltriazole, a-2-ethyltriazole, a (2-ethyltriazole, a-ethyl2-ethyltriazole, a-6-ethyl2-ethyltriazole, a-2-6-2-ethyltriazole, a-2-ethyltriazole, a-ethyl.

The content of the amine may be, for example, 0 to 20% by mass based on the entire flux.

To improve solderability, the flux may contain a covalently bound halogen activator (covalently bound halogen (total of ハロゲン)). Examples of the covalently bonded halogen include trans-2, 3-dibromo-2-butene-1, 4-diol, 2, 3-dibromo-1, 4-butanediol, 2, 3-dibromo-1-propanol, 2, 3-dichloro-1-propanol, 1,2, 2-tetrabromoethane, 2,2, 2-tribromoethanol, pentabromoethane, carbon tetrabromide, 2, 2-bis (bromomethyl) -1, 3-propanediol, meso-2, 3-dibromosuccinic acid, chloroalkane, chlorinated fatty acid ester, n-hexadecyltrimethylammonium bromide, tris (2, 3-dibromopropyl) isocyanurate, 2, 2-bis [3, 5-dibromo-4- (2, 3-dibromopropyloxy) phenyl ] propane, Bis [3, 5-dibromo-4- (2, 3-dibromopropyloxy) phenyl ] sulfone, ethylenebis-pentabromobenzene, 2-chloromethyl oxirane, chlorendic acid, chlorendic anhydride, brominated bisphenol a type epoxy resin, and the like.

The content of the covalently bound halogen may be, for example, 0 to 5% by mass based on the entire flux.

The flux may contain an amine hydrohalide activator (amine hydrohalide) as an amine hydrohalide, amine hydrohalide exemplified by amine hydrohalide, for example, stearylamine hydrochloride, diethylaniline hydrochloride, diethanolamine hydrochloride, 2-ethylhexylamine hydrobromide, pyridine hydrobromide, isopropylamine hydrobromide, cyclohexylamine hydrobromide, diethylamine hydrobromide, monoethylamine hydrobromide, 1, 3-diphenylguanidine hydrobromide, dimethylamine hydrochloride, abietylamine hydrobromide, 2-ethylhexylamine hydrochloride, isopropylamine hydrochloride, cyclohexylamine hydrochloride, 2-pipecoline hydrobromide, 1, 3-diphenylguanidine hydrochloride, dimethylbenzylamine hydrochloride, hydrazine hydrate hydrobromide, dimethylcyclohexylamine hydrochloride, trinonylamine hydrobromide, diethylbenzylamine hydrobromide, 2-diethylaminoethanol hydrochloride, ammonium chloride, diallylamine hydrochloride, diallylamine hydrobromide, monoammonium hydrochloride, monoethylamine hydrobromide, diethylamine hydrochloride, triethylammonium hydrobromide, triethylamine hydrobromide, 2-diethylaminoethanol hydrochloride, triethylamine hydrobromide, 2-diethylaminoethylhydrazine hydrobromide, 2-diethylhydrazine hydrobromide hydrochloride, 2-diethylhexylamine hydrobromide hydrochloride, morpholine hydrochloride, 4-cyclohexylamine hydrochloride, triethylamine hydrobromide, 2-ethylhexylamine hydrochloride, morpholine hydrochloride, 4-dihydromorpholine hydrochloride, cyclohexylamine hydrochloride, triethylamine hydrobromide, morpholine hydrochloride, morpholine.

The content of the amine hydrohalide salt may be, for example, 0 to 2 mass% with respect to the entire flux.

A flux may contain a solvent. Examples of the solvent include water, alcohol solvents, glycol ether solvents, and terpene alcohols. Examples of the alcohol solvent include isopropanol, 1, 2-butanediol, isobornyl cyclohexanol, 2, 4-diethyl-1, 5-pentanediol, 2-dimethyl-1, 3-propanediol, 2, 5-dimethyl-2, 5-hexanediol, 2, 5-dimethyl-3-hexyne-2, 5-diol, 2, 3-dimethyl-2, 3-butanediol, 1,1, 1-tris (hydroxymethyl) ethane, 2-ethyl-2-hydroxymethyl-1, 3-propanediol, 2 '-oxybis (methylene) bis (2-ethyl-1, 3-propanediol), 2-bis (hydroxymethyl) -1, 3-propanediol, isobornyl cyclohexanol, 2, 4-diethyl-1, 5-pentanediol, 2-dimethyl-1, 3-propanediol, 2, 1, 1-tris (hydroxymethyl) ethane, 2-ethyl-2-hydroxymethyl-1, 3-propanediol, 2' -oxybis, 1,2, 6-trihydroxyhexane, bis [2,2, 2-tris (hydroxymethyl) ethyl ] ether, 1-ethynyl-1-cyclohexanol, 1, 4-cyclohexanediol, 1, 4-cyclohexanedimethanol, erythritol, threitol, guaiacol glyceryl ether, 3, 6-dimethyl-4-octyne-3, 6-diol, 2,4,7, 9-tetramethyl-5-decyne-4, 7-diol, and the like. Examples of the glycol ether solvents include diethylene glycol mono-2-ethylhexyl ether, ethylene glycol monophenyl ether, 2-methylpentane-2, 4-diol, diethylene glycol monohexyl ether, diethylene glycol dibutyl ether, triethylene glycol monobutyl ether, diethylene glycol monohexyl ether, and tetraethylene glycol dimethyl ether.

The content of the solvent may be, for example, 0 to 80% by mass, preferably 20 to 60% by mass, based on the entire flux.

The flux may contain a thixotropic agent. Examples of the thixotropic agent include wax-based thixotropic agents and amide-based thixotropic agents. Examples of the wax thixotropic agent include hydrogenated castor oil and the like. Examples of the amide thixotropic agent include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide, saturated fatty acid amide, oleic acid amide, erucic acid amide, unsaturated fatty acid amide, p-toluamide, aromatic amide, substituted amide, methylol stearic acid amide, methylol amide, and fatty acid ester amide. The amide-based thixotropic agent may be a bisamide-based thixotropic agent and/or a polyamide-based thixotropic agent, examples of the bisamide-based thixotropic agent include methylenebisstearamide, ethylenebislauramide, ethylenebishydroxystearamide, saturated fatty acid bisamide, methylenebisoleamide, unsaturated fatty acid bisamide, m-xylylenebisstearamide, and aromatic bisamide, and examples of the polyamide-based thixotropic agent include saturated fatty acid polyamide, unsaturated fatty acid polyamide, and aromatic polyamide.

The content of the thixotropic agent may be, for example, 0 to 15 mass% with respect to the entire flux.

[ solder paste ]

The solder paste of the present embodiment is composed of a solder material and the flux of the present embodiment. The solder paste can improve the thickening suppression effect by containing the flux of the present embodiment. It is worth noting that: the term "flux" as used herein refers to all components of the solder paste other than the solder material.

(solder material)

The solder material preferably contains Sn or a Sn-based alloy. Sn or Sn-based alloys may contain inevitable impurities.

The Sn may be, for example, Sn having a purity of 99.9% or more (3N material), Sn having a purity of 99.99% or more (4N material), and Sn having a purity of 99.999% (5N material).

Examples of the Sn-based alloy include alloys having a composition such As Sn-Ag alloy, Sn-Cu alloy, Sn-Ag-Cu-Ni-Co alloy, Sn-In alloy, Sn-Bi alloy, Sn-Sb alloy, and Sn-Pb alloy, and alloys In which As, Bi, Sb, Pb, Ag, Cu, In, Ni, Co, Ge, P, Fe, Zn, Al, Ga, etc. are added to an alloy having the above composition. The Sn content in the Sn-based alloy is not particularly limited, and may be, for example, more than 40 mass%.

From the liquidus temperature (T)_L) Temperature of solidus (T)_S) Difference (Δ T ═ T)_L-T_S) From the viewpoint of reduction, Sn and Sn-based alloys are preferably Sn, Sn-Cu alloys or Sn-Ag-Cu alloys. If the Δ T is made small, the solder paste containing the solder material can maintain the texture uniformity of the solder material even when the solder paste is applied to a substrate of an electronic device and solidified, for example. As a result, the solder paste is excellent in reliability such as cycle characteristics. From the same viewpoint, the Sn — Cu alloy preferably contains more than 0 and 1.0 mass% or less (preferably 0.5 to 1.0 mass%) of Cu, with the balance being Sn. From the same viewpoint, the Sn — Ag — Cu alloy preferably contains Ag in an amount of more than 0 and 3.5 mass% or less (preferably 1.0 to 3.5 mass%), Cu in an amount of more than 0 and 1.0 mass% or less (preferably 0.1 to 1.0 mass%), and the balance of Sn.

From the viewpoint of excellent reliability by reducing Δ T, the content of Ag is preferably 0.05 to 3.5% by mass, more preferably 0.1 to 3% by mass, and further preferably 0.5 to 3% by mass in the step , and from the viewpoint of excellent reliability by reducing Δ T, the content of Cu is preferably 0.01 to 0.9% by mass, more preferably 0.05 to 0.75% by mass, and further preferably 0.1 to 0.7% by mass in the step .

The content of Sn may be, for example, 40 mass% or more, 50 mass% or more, 70 mass% or more, and 90 mass% or more based on the entire solder material, and is a further aspect in which, when Pb is contained in the solder material, the content of Pb may be 90 mass% or more based on the entire solder material, and the content of Sn may be 5 mass% or more, and 10 mass% or more based on the entire solder material.

The solder material may contain, for example, As. of 20 to 300 mass ppm, and the increase in viscosity is suppressed by setting the content of As to 20 mass ppm or more, thereby achieving an excellent effect of suppressing thickening, and the wettability deterioration can be further suppressed by steps by setting the content of As to 300 mass ppm or less, and therefore, the solder paste of the present embodiment can achieve both the effect of suppressing thickening and the reliability in a well-balanced manner by setting the content of As to 20 to 300 mass ppm, and from the same viewpoint, the content of As is preferably 30 to 250 mass ppm, more preferably 50 to 200 mass ppm, and As may form an alloy (e.g., intermetallic compound, solid solution, etc.) with Sn or the Sn-based alloy , or may be present As a simple substance or an oxide independently of the Sn-based alloy, for example.

The solder material preferably contains 50 ppm by mass (0.0050% by mass) to 3.0% by mass of Bi. When the content of Bi is 50 mass ppm or more, the viscosity increase is suppressed, and the thickening suppression effect is excellent. The liquidus temperature (T) can be controlled by setting the Bi content to 3.0 mass% or less_L) Temperature of solidus (T)_S) Difference (Δ T ═ T)_L-T_S) The size is reduced, and the reliability such as cycle characteristics is excellent. Therefore, when the Bi content is 50 mass ppm to 3.0 mass%, the solder paste of the present embodiment can achieve both the thickening suppression effect and the reliability in a well-balanced manner. From the same viewpoint as above, Bi contentThe amount is preferably 50 mass ppm (0.0050 mass%) to 1.0 mass%, and more preferably 100 mass ppm (0.010 mass%) to 1.0 mass%, based on the entire solder material.

The solder material preferably contains 20 ppm by mass (0.0020 mass%) to 0.5 mass% of Sb. When the Sb content is 20 mass ppm or more, the viscosity increase is suppressed, and the thickening suppression effect is excellent. When the Sb content is 0.5 mass% or less, the wettability and the reliability such as the cycle characteristics are excellent. Therefore, when the Sb content is 20 ppm by mass to 0.5 mass%, the solder paste of the present embodiment can achieve both the thickening suppression effect and the reliability in a well-balanced manner. From the same viewpoint, the content of Sb is preferably 50 mass ppm (0.0050 mass%) to 0.3 mass%, and more preferably 100 mass ppm (0.010 mass%) to 0.1 mass% with respect to the entire solder material.

The solder material preferably contains 20 ppm by mass (0.0020 mass%) to 0.7 mass% of Pb. When the Pb content is 20 mass ppm or more, the viscosity increase is suppressed, and the thickening suppression effect is excellent. The liquidus temperature (T) can be controlled by setting the Pb content to 0.7 mass% or less_L) Temperature of solidus (T)_S) Difference (Δ T ═ T)_L-T_S) The size is reduced, and the reliability such as cycle characteristics is excellent. Therefore, when the Pb content is 20 mass ppm to 0.7 mass%, the solder paste of the present embodiment can achieve both the thickening suppression effect and the reliability in a well-balanced manner. From the same viewpoint, the content of Pb is preferably 50 mass ppm (0.0050 mass%) to 0.5 mass%, and more preferably 100 mass ppm (0.010 mass%) to 0.3 mass% with respect to the entire solder material.

Bi may be present as an alloy (e.g., intermetallic compound, solid solution, etc.) with Sn or the Sn-based alloy , or may be present independently of Sn or the Sn-based alloy.

The method for producing the solder material of the present embodiment is not particularly limited, and for example, a method for producing the solder material by melt-mixing raw material metals is exemplified.

In the present embodiment, the form of the solder material is not particularly limited, and may be, for example, a linear form, a spherical form (solder ball), a powder form (solder powder), or other granular forms. From the viewpoint of excellent fluidity, the form of the solder material is preferably a granular form, and more preferably a powdery form.

Examples of the method for producing the granular solder material include a dropping method in which a molten solder material is dropped to obtain particles, a spraying method in which centrifugal spraying is performed, and a method in which a bulk solder material is pulverized. In the dropping method or the spraying method, dropping or spraying is preferably performed in an inert atmosphere or a solvent in order to form particles.

When the solder material is granular, the solder material preferably has a size (particle size distribution) under the reference number 1 to 8 in the powder size classification (table 2) of JIS Z3284-1:2014, more preferably has a size (particle size distribution) under the reference number 4 to 8, and more preferably has a size (particle size distribution) under the reference number 5 to 8. Thereby, it is possible to solder to a fine component.

In the present embodiment, the size (particle size distribution) of the solder material in a granular form can be measured according to the laser diffraction particle size distribution measurement test described in 4.2.3 of JIS Z3284-2: 2014.

In the present embodiment, the mass ratio of the content of the solder material to the content of the flux (solder material: flux) may be, for example, 95 mass% of the solder material, 5 mass% to 5 mass% of the flux, 95 mass% of the flux, and preferably 95 mass% of the solder material, 5 mass% to 85 mass% of the flux, and 15 mass% of the flux.

In the present embodiment, the solder paste may further contain steps of zirconia powder, the content of zirconia powder with respect to the entire mass of the solder paste is preferably 0.05 to 20.0 mass%, more preferably 0.05 to 10.0 mass%, most preferably 0.1 to 3 mass%, and when the content of zirconia powder is within the above range, the activator contained in the flux preferentially reacts with the zirconia powder and is less likely to react with Sn or an Sn oxide on the surface of the solder powder, and the effect of further steps of suppressing the increase in viscosity with the passage of time is exhibited.

The upper limit of the particle size of the zirconia powder added to the solder paste is not limited, but is preferably 5 μm or less. If the particle size is 5 μm or less, the printability of the paste can be maintained. The lower limit is also not particularly limited, but is preferably 0.5 μm or more. The particle size is an average value of diameters equivalent to the projected circle of particles having a diameter equal to or larger than 0.1 μm when the diameter is obtained by taking an SEM photograph of the zirconia powder and obtaining a diameter equivalent to the projected circle for each particle existing in a visual field by image analysis. The shape of the zirconia particles is not particularly limited, and when the zirconia particles are different in shape, the contact area with the flux becomes large, and the thickening suppression effect is exhibited. The spherical shape provides good fluidity, and therefore provides excellent printability as a paste. The shape may be selected as appropriate depending on the desired characteristics.

In the present embodiment, the solder paste can be produced by kneading the solder material (solder powder) and the flux of the present embodiment by a known method.

The solder paste of the present embodiment is used for a circuit board having a fine structure in an electronic device, for example, and specifically can be applied to a solder portion by a printing method using a metal mask, a discharge method using a dispenser, a transfer method using a transfer needle, or the like to perform reflow soldering.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to the contents described in the examples.