JP4788563B2 - Flux composition for soldering and solder paste - Google Patents

Description

  The present invention relates to a soldering flux used for mounting a printed wiring board of an electronic component, and a solder paste using the same.

Conventionally, soldering has been frequently used for mounting electronic components on a printed wiring board. As soldering methods, solder paste consisting of flux and solder powder is printed, electronic components are mounted by heat bonding (reflow soldering), and linear solder with flux in the core (Yani There are a method of soldering (soldered solder) with a soldering iron, a method of applying a liquid flux to a lead wire or an electrode, and then making contact with molten solder and soldering (flow soldering).
The flux for solder paste is based on rosin resin, and a small amount of activator such as amine halogen salt and organic acid, thixotropic agent for improving printability, and various materials depending on the purpose. Is dissolved in a solvent. The flux for the flux cored solder is usually a resinous material composed of a rosin resin and an activator. The liquid flux for flow is a liquid in which a rosin resin, a synthetic resin, an activator, or the like is dissolved in a solvent (organic solvent, water).

In recent years, lead-free solder has been developed from environmental measures. However, lead-free solder has a new performance in the flux for lead-free solder because its metal characteristics are different from conventional lead-containing solder. Is needed.
Since lead-free solder forms a stable oxide film on the metal surface, the wettability of the solder is poor. As a result, the wettability of the molten solder to the soldering land also deteriorates, and the solder does not wet due to the non-wetting of the molten solder. Voids (cavities) are likely to be generated in the bonded portion after being attached. However, if a strong activator component is used to improve the wettability of the solder, the oxide film is reduced and removed, and at the same time, hydrogen, moisture, and other activator components are produced by the reaction between these activator components and the solder metal. As a result, a large amount of decomposition products (organic substances of low volatile components) are generated, and a large amount of voids in the solder is also generated. Therefore, when lead-free solder is used, the generation of voids cannot be suppressed as long as the conventional flux is used.

  When voids occur, the shear strength and tensile strength of the solder joints decrease, and not only the printed circuit board on which the component is mounted and the impact resistance of the electronic equipment using it are reduced, but also reliability such as temperature cycle testing. In the property test, cracks are generated inside the solder, causing problems such as poor conduction. Furthermore, when the void becomes large, the solder bumps become uneven in size and the chip component is inclined. In particular, chip parts such as ceramic capacitors have been downsized in recent years, and the generation of voids immediately leads to a decrease in the mechanical strength of the solder joints, so there is a strong demand for lead-free solder paste that can reduce the voids. Yes.

  As a method for solving this problem, in Patent Documents 1 and 2, a cyclic acid anhydride having a carbon 6-membered ring structure in the hydroxyl group of a compound having two or more hydroxyl groups in one molecule is subjected to a ring-opening half esterification reaction. Furthermore, a low void type soldering flux and a solder paste containing a derivative obtained by blocking with vinyl ether are disclosed. However, this technique does not exhibit the effect when applied to fine solder powder having an average particle size of 1 to 15 μm. This is because when the solder becomes fine powder, the amount of oxide on the surface of the solder increases, and the effect of suppressing voids becomes insufficient.

  In addition, the silicon compound having an alkoxysilyl group is hydrolyzed to produce silane, which easily reacts with the oxide portion on the metal surface of the solder powder, thereby increasing the affinity between the flux component and the solder powder, In order to prevent the oxidation of the solder paste, it is added to the solder paste. For example, in Patent Document 3, a silane coupling agent is used, and in Patent Document 4, a silicon compound having an alkyl group is used by coating the solder powder with a surface. However, even if these silicon compounds are blended into the flux, although there is some antioxidant effect, no effect is seen in reducing voids.

JP 2005-288490 A JP 2006-167802 A JP-A-6-126481 JP-A-7-51892

  An object of the present invention is to provide a soldering flux composition and a solder paste that have excellent solder wettability, can suppress the generation of voids in solder joints, and are excellent in joint reliability and electrical reliability. There is to do.

  As a result of intensive studies in view of the above problems, the present inventors have further added a soldering flux composition in which a specific amount of a half ester compound having a specific structure and a silicon compound are combined, or the soldering flux. Obtaining knowledge that the solder paste blended with solder powder has excellent solder wettability, can suppress the generation of voids in the solder joints, and can achieve both joint reliability and electrical reliability, The present invention has been completed.

That is, the present invention includes the following [1] to [3].
[1] (A) A resin obtained by subjecting a polyhydric alcohol (a1) and a cyclic acid anhydride (a2) having a carbon 6-membered ring structure to a ring-opening half esterification reaction, and (B) the following formula (1) The blending ratio of the resin (A) is 5 to 95 parts by weight per 100 parts by weight of the flux composition, and the blending ratio of the silicon compound (B) is based on the total amount of the flux composition. 0.01 to 5.0% by weight of a soldering flux composition.

(In formula (1), r = 2 or 3. X is a group selected from a hydrogen atom, a bromine atom, a chlorine atom, or a hydroxyl group, and may be the same or different from each other. )
[2] A solder paste containing the soldering flux composition according to the above [1] and solder powder composed of at least two metals selected from Sn, Ag, Cu, Bi, and In.

[3] The solder paste according to [2], wherein the solder powder is a solder powder having an average particle diameter of 1 to 15 μm.

The soldering flux composition and the solder paste of the present invention are excellent in bonding reliability and electrical reliability, while ensuring good solder wettability, generating less voids in the solder bonding portion. Therefore, it can be suitably used as an electronic component material such as a printed wiring board.
The solder paste of the present invention can exhibit the above-mentioned good performance even when using a solder powder having an average particle size of 1 to 15 μm.

Hereinafter, the present invention will be described in detail.
The soldering flux composition and the solder paste of the present invention contain the following components (A) and (B).
(A) a resin obtained by subjecting a polyhydric alcohol (a1) and a cyclic acid anhydride (a2) having a carbon 6-membered ring structure to a ring-opening half esterification reaction, and (B) represented by the following formula (1) Silicon compounds

  In formula (1), r = 2 or 3. X is a group selected from a hydrogen atom, a bromine atom, a chlorine atom, or a hydroxyl group, and may be the same or different from each other.

<Resin (A)>
The resin (A) used in the flux composition of the present invention is obtained by subjecting a polyhydric alcohol (a1) and a cyclic acid anhydride (a2) having a carbon 6-membered ring structure to a ring-opening half esterification reaction. More specifically, the compound shown by following formula (2) is mentioned.

The 6-membered ring in the formula (2) is an alicyclic hydrocarbon. m is an integer of 0 or 1, p is an integer of 0 to 4, and n is an integer of 1 to 8. R ⁴ represents a hydrocarbon group having 2 to 50 carbon atoms. R ⁵ is the same or different, a halogen atom or a hydrocarbon group having 1 to 25 carbon atoms.

  In the reaction of obtaining the resin (A) used in the present invention from the polyhydric alcohol (a1) and the cyclic acid anhydride (a2) having a carbon 6-membered ring structure, 1 mol of the hydroxyl group of the polyhydric alcohol (a1) is an acid. This is a ring-opening half-esterification reaction in which 1-mol of an anhydride group is subjected to ring-opening addition to produce a half ester, and more specifically, is illustrated by the reaction formula of the following formula (3).

R ^4, R ⁵ , n, m, and p in the formula are the same as those in the formula (2).
In the resin (A) used in the present invention, the polyhydric alcohol residue R ^{4 in} the alcohol portion of the half ester is a hydrocarbon group having 2 to 50 carbon atoms which may have a straight chain or a branch. When the number of carbon atoms exceeds 50, the melt viscosity of the resin (A) increases and adversely affects the miscibility with other components of the resin (A).
The degree of branching of the molecular chain of the resin (A) used in the present invention is determined by the valence n of the compound (a1) having two or more hydroxyl groups. n is an integer of 1 to 8, preferably an integer of 2 to 6. When the number of n exceeds 8, the melt viscosity of resin (A) will increase and it will have a bad influence on the miscibility with the other component of resin.
The resin (A) used in the present invention has a carbon 6-membered ring structure that may have a substituent R ⁵ on the ring, as shown in the formula (2). The substituent R ⁵ is the same or different and is a halogen atom or a hydrocarbon group having 1 to 25 carbon atoms. In the case of having the substituent R ⁵ , if the carbon number of R ⁵ exceeds 25, the polarity of the resin (A) changes and the affinity with the silicon compound (B) decreases, so that a good void reduction effect is exhibited. Can not do it.

In the structure of the resin (A) used in the present invention, the substitution number p of the substituent R ⁵ on the carbon 6-membered ring is an integer of 0 to 4, preferably an integer of 0 to 1. If the number of substitutions p exceeds 4, the polarity of the resin (A) changes and the affinity with the silicon compound (B) decreases, so that a good void reduction effect cannot be exhibited.
The resin (A) used in the present invention may have a carboxyl group other than the carboxyl group derived from the acid anhydride group of the cyclic acid anhydride (a2) having a carbon 6-membered ring structure on the carbon 6-membered ring. Good. The number m of the carboxyl groups is an integer of 0 or 1. When m exceeds 1, the polarity of the resin (A) is changed and the affinity with the silicon compound (B) is lowered, so that a favorable void reducing effect cannot be exhibited.

Specific examples of the polyhydric alcohol (a1) used in the present invention include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol having a molecular weight of 440 or less, 1,2-propylene glycol, 1,3-propylene glycol. 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,6-hexanediol, 1,5-pentanediol, 2,3-dimethylbutane-1,4-diol, water Diol compounds such as bisphenol A, neopentyl glycol, 1,8-octanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 2-methyl-1,3-propanediol; glycerin, 1,2 , 4-butanetriol, 1,2,5- Ntantriol, 1,2,6-hexanetriol, 1,2,7-heptanetriol, 1,2,8-octanetriol, 1,2,9-nonanetriol, 1,2,10-decanetriol, 1 , 3,5-cyclohexanetriol, 1,2,4-cyclohexanetriol, triol compounds such as trimethylolpropane and trimethylolethane; and tetraol compounds such as pentaerythritol.
Among these, ethylene glycol and trimethylolpropane are preferable from the viewpoints of availability and reactivity.
Moreover, polyhydric alcohol (a1) can be used individually by 1 type or in mixture of 2 or more types in said 1 molecule.

Specific examples of the cyclic acid anhydride (a2) used in the present invention include hexahydrophthalic anhydride (in formula (3), p = 0, m = 0), 4-methylhexahydrophthalic anhydride (same as above). p = 1, R ⁵ = methyl group, m = 0), and cycloaliphatic carboxylic acid anhydrides such as hydrogenated trimellitic anhydride (same as p = 0, m = 1).
Among these cyclic acid anhydrides (a2), hexahydrophthalic anhydride is preferred because of its availability and the solubility of the resulting resin in solvents and resins.
The cyclic acid anhydride (a2) may be used alone or in combination of two or more.

The 6-membered ring, m, p, n, R ⁴ and R ⁵ in the formula (2) are the same as those in the formula (3).
This ring-opening half esterification reaction can be carried out by a known method, for example, at a temperature of room temperature to 200 ° C. in an organic solvent.
The use ratio of the raw materials (a1) and (a2) in the ring-opening half esterification reaction can be arbitrarily selected according to the purpose, but usually cyclic acid anhydride per mole of hydroxyl group of the polyhydric alcohol (a1). It is suitable to use the component (a2) so that the physical group is usually 0.2 to 2 mol, preferably 0.5 to 1.5 mol, more preferably 0.8 to 1.2 mol.

  In the ring-opening half esterification reaction, a catalyst such as an organic amine compound can be used to accelerate the reaction. Specifically, examples of such a catalyst include methylamine, ethylamine, butylamine, t-butylamine, amylamine, octylamine, cyclohexylamine, s-butylamine, vinylmethylamine, allylamine, ethoxymethylamine and the like. Primary amines; secondary amines such as dimethylamine, diethylamine, dipropylamine, diamylamine, dihexylamine, didodecylamine; tertiary amines such as trimethylamine, triethylamine, tripropylamine; ethanolamine, diethanolamine, Alkanolamines such as triethanolamine; Bennes such as phenylpropylamine, phenylethylamine, methoxybenzylamine, diethylbenzylamine, benzylamine, dimethylbenzylamine Aliphatic amines having an aromatic ring; morpholine derivatives such as morpholine and methylmorpholine; aniline derivatives such as t-butylaniline; aromatic amines such as dimethyltoluidine; 2-hydroxypyrimidine, 2-hydroxypyridine, 3-hydroxypyridine Pyridine derivatives such as 4-hydroxypyridine; piperidine derivatives such as piperidine, methylpiperidine and benzylpyrrolidine; pyrrolidine derivatives such as methylpyrrolidine; pyrrole derivatives such as pyrrole; 2-hydroquinoline, 3-hydroquinoline, 4-hydroquinoline, Quinoline derivatives such as 2-methylquinoline and 4-methyl-8-hydroquinoline; Imidazole derivatives such as benzimidazole, methylimidazole and imidazole; Tetramethylammonium hydroxide, Tetraethyla Quaternary ammonium salts such as mode onium hydroxide and the like. Further, organotin compounds such as dibutyltin dilaurate and butyltin oxyacetate can also be used as a catalyst for promoting the reaction.

  The said catalyst can be used individually by 1 type or in mixture of 2 or more types. The amount of the catalyst used is preferably 0.005 to 10 parts by weight, more preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of the total amount of the compound (a1) and the compound (a2) as raw materials. 5 parts by weight.

  Examples of the organic solvent that makes the reaction system uniform and facilitates the reaction include benzene, toluene, xylene, ethylbenzene, aromatic petroleum naphtha, tetralin, turpentine oil, Solvesso # 100 (Exxon Chemical Co., Ltd. registered trademark), Aromatic hydrocarbons such as Solvesso # 150 (registered trademark of Exxon Chemical Co., Ltd.); ethers such as dioxane and tetrahydrofuran; methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, acetic acid Esters and ether esters such as sec-butyl, amyl acetate, propylene glycol monomethyl ether acetate, methoxybutyl acetate; acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, cyclohexanone, isophorone, mesityl oxide Ketones such as methyl isoamyl ketone, ethyl butyl ketone, ethyl amyl ketone, diisobutyl ketone, diethyl ketone, methyl propyl ketone and diisopropyl ketone; phosphate esters such as trimethyl phosphate, triethyl phosphate and tributyl phosphate; dimethyl sulfoxide, N, N -Aprotic polar solvents such as dimethylformamide. An organic solvent can be used individually or in combination of 2 or more types. Although the usage-amount of the said organic solvent is not specifically limited, It is 5-95 weight part normally with respect to 100 weight part of reaction raw materials, Preferably, it is 20-80 weight part.

In the flux composition of the present invention, the blending ratio of the resin (A) is usually 5 to 95 parts by weight, particularly 10 to 90 parts by weight per 100 parts by weight of the flux composition. If it is less than 5 parts by weight, the solder wettability is deteriorated and the void characteristics are deteriorated. If it exceeds 95 parts by weight, good printability cannot be obtained, which is not preferable.

<Silicon compound (B)>
The silicon compound (B) used in the flux composition of the present invention is a compound represented by the following formula (1).

In formula (1), r = 2 or 3. X is a group selected from a hydrogen atom, a bromine atom, a chlorine atom, or a hydroxyl group, and may be the same or different from each other.
Specific examples of the silicon compound (B) include triphenylsilane (in formula (1), X = hydrogen atom, Y = phenyl group), triphenylsilanol (the same X = hydroxyl group, Y = phenyl group), triphenylsilane. Phenylchlorosilane (same as X = chlorine atom, Y = phenyl group), triphenylbromosilane (same as X = bromine atom, Y = phenyl group), diphenylsilane (in formula (1), X = hydrogen atom, Y = hydrogen atom) ), Diphenyldichlorosilane (in formula (1), X = chlorine atom, Y = chlorine atom), diphenyldibromosilane (in formula (1), X = bromine atom, Y = bromine atom) and the like. These silicon compounds can be used individually by 1 type or in mixture of 2 or more types.

  Generally, in solder joining using a flux, it tends to occur when melting and coalescence of solder particles during heat joining does not proceed well. Particularly in the case of lead-free solder, a metal compound derived from an oxide film reduced by a flux component is interposed between solder particles, and melting and coalescence of solder particles is likely to be hindered. In the present invention, the mechanism for obtaining outstanding void suppression is not strictly proved, but the component (A) having flux ability and 2 or 3 phenyl groups having a very high affinity, It is presumed that the component (B) having both a high silyl atom acts near the interface of the metal compound derived from the oxide film and promotes coalescence of the metal particles even during a short reflow.

The silicon compound (B) is usually blended at a ratio of 0.01 to 5.0% by weight, preferably 0.05 to 3.0% by weight , based on the total amount of the flux composition . When the silicon compound (B) is less than 0.01% by weight, the surface modification of the solder surface or the substrate surface becomes insufficient, and the growth of the oxide film cannot be suppressed, resulting in the generation of voids. Can not be suppressed. On the other hand, at 5.0 wt% or more, the excess silicon compound (B) inhibits the wettability of the solder, and on the contrary, many voids are generated.

<Flux activator>
In the flux composition of the present invention, a commonly used flux activator can be used. Specifically, for example, amine salts of hydrochloric acid and hydrobromic acid, carboxylic acids and amine salts thereof are preferably used. Specifically, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, n-propylamine, di-n-propylamine, tri-n-propylamine, isopropylamine, diisopropylamine, triisopropylamine, butylamine, Hydrochlorate or hydrobromide such as dibutylamine, monoethanolamine, diethanolamine, triethanolamine, oxalic acid, malonic acid, succinic acid, adipic acid, glutaric acid, diethylglutaric acid, pimelic acid, azelaic acid, Aliphatic carboxylic acids such as sebacic acid, maleic acid, fumaric acid, diglycolic acid, capric acid, lauric acid, myristic acid, palmitic acid, linoleic acid, oleic acid, stearic acid, arachidic acid, behenic acid, linolenic acid ; Aromatic acids such as benzoic acid; hydroxypivalic acid, dimethylolpropionic acid, citric acid, malic acid, glyceric acid, hydroxy acids such as lactic acid; or their amine salts.

As the flux activator used in the flux composition of the present invention, when storage stability and colorlessness of the flux residue after reflow are required, a fat having one or more latent carboxyl groups in one molecule Preferred examples thereof include group carboxylic acid derivatives. Specific examples include hemiacetal ester compounds and polyhemiacetal ester compounds.
The aforementioned hemiacetal ester compound and polyhemiacetal ester compound are obtained by reacting a carboxyl compound and a vinyl ether compound to make a carboxyl group in the molecule latent.
Examples of the aliphatic carboxylic acid compound include aliphatic carboxylic acids such as succinic acid, adipic acid, and glutaric acid.

Examples of the vinyl ether include alkyl vinyl ethers such as n-propyl vinyl ether, isopropyl vinyl ether and n-butyl vinyl ether; divinyl ethers such as diethylene glycol divinyl ether, triethylene glycol divinyl ether and butanediol divinyl ether; 2,3-dihydrofuran And unsaturated cyclic ethers such as 3,4-dihydro-2H-pyran.
An aliphatic carboxylic acid compound having one or more latent carboxyl groups in one molecule is usually prepared by using the above-mentioned carboxyl compound and vinyl ether without a catalyst or in the presence of an acid catalyst such as an acidic phosphate compound. It is obtained by reacting at a temperature of room temperature to 150 ° C.
Although the ratio in the case of mix | blending these active agents is not specifically limited, Preferably it is 30 weight% or less with respect to the flux composition whole quantity, More preferably, it is 2 to 6 weight%.

<Acid neutralizer>
When the tackiness and electrical reliability of the reflow residue are required for the flux composition of the present invention, an acid neutralizing agent that reacts with the organic acid residue in the reflow residue is preferably blended. Specific examples of the acid neutralizing agent include compounds having one or more oxetanyl groups in one molecule. For example, 3-methyl-3-methoxymethyloxetane, 3-ethyl-3-phenoxymethyloxetane, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, 3-ethyl-3-cyclohexyloxymethyloxetane, Monooxetanes such as 3-ethyl-3-hydroxymethyloxetane and the following dioxetanes (i) and (ii) can be preferably used.

(I) Etherified product of hydroxyl compound and 3-alkyl-3-hydroxymethyloxetane Specifically, for example, an aliphatic monoalcohol composed of an alkyl group having 1 to 6 carbon atoms, an alkylene group having 2 to 8 carbon atoms An aliphatic glycol comprising 2 to 18 carbon atoms, a phenol novolak resin, a hydroxyl compound such as a polysiloxane having a quaternary structure and a polymerization degree of 2 to 8, and 3-ethyl-3-methoxymethyl Examples include compounds obtained by ether condensation of oxetanes such as oxetane. More specifically, for example, 1,4-bis (((3-ethyl-3-oxetanyl) methoxy) methyl) benzene, 1,4-bis (((3-ethyl-3-oxetanyl) methoxy) methyl) benzene 4,4′-bis (((3-ethyl-3-oxetanyl) methoxy) methyl) biphenyl, 3,3 ′, 5,5′-methyl-4,4′-bis (((3-ethyl-3 -Oxetanyl) methoxy) methyl) biphenyl, 1,4-bis ((3-ethyl-3-oxetanyl) methoxy) benzene, 4,4'-bis ((3-ethyl-3-oxetanyl) methoxy) biphenyl, 3, And 3 ′, 5,5′-methyl-4,4′-bis ((3-ethyl-3-oxetanyl) methyl) biphenyl.

(Ii) Esterified product of carboxyl compound and 3-alkyl-3-hydroxymethyloxetane Specifically, for example, a carboxyl compound such as (meth) acrylic acid, carbonic acid, adipic acid, terephthalic acid, cyclohexanedicarboxylic acid, and 3 Examples include compounds obtained by esterifying oxetanes such as -ethyl-3-methoxymethyloxetane, and more specifically, for example, (3-ethyl-3-oxetanyl) methyl methacrylate, bis ((3-ethyl-3- Oxetanyl) methyl) carbonate, bis ((3-ethyl-3-oxetanyl) methyl) adipate, bis ((3-ethyl-3-oxetanyl) methyl) benzene-1,4-dicarboxylate, bis ((3-ethyl -3-oxetanyl) methyl) cyclohexane-1,4-dicarboxylate Etc. The.

Among these compounds having one or more oxetanyl groups in one molecule, 3-ethyl-3-hydroxymethyloxetane, 1,4-bis {[(3-ethyl-3-oxetanyl) methoxy] methyl} benzene Is preferable from the viewpoint of the physical properties of the flux residue.
The compounds having one or more oxetanyl groups in one molecule can be used singly or in combination of two or more.
In the soldering flux composition of the present invention, when the acid neutralizing agent is blended, the blending ratio is preferably 5 to 60 parts by weight, and 10 to 40 parts by weight per 100 parts by weight of the soldering flux composition. Is more preferable.

  The flux composition of the present invention is selected from the group consisting of a thixotropic agent, an antioxidant, a rust inhibitor, a chelating agent, a leveling agent, an antifoaming agent, a dispersant, and a solvent depending on the required performance. At least one of these can be blended.

  Examples of thixotropy imparting agents used to improve the printability of solder paste include polyolefin waxes such as castor wax (hardened castor oil = hydrogenated castor oil), beeswax, carnauba wax, etc .; stearamide, hydroxystearic acid Bisamide, m-xylylenebisstearic acid amide, N, N′-distearylisophthalic acid amide, N, N′-distearyl sebacic acid amide, N, N′-distearyl adipic acid amide, butylene bishydroxystearic acid amide , Hexamethylene bishydroxy stearamide, hexamethylene bis behenamide, hexamethylene bis stearamide, ethylene bis behenamide, ethylene bishydroxy stearate, ethylene bis stearamide, Fatty acid amides such as tylene bislauric acid amide, ethylene biscapric acid amide, ethylene biscaprylic acid amide, methylene bishydroxystearic acid amide, methylene bislauric acid amide, methylene bis stearic acid amide; N-butyl-N′-stearyl urea N-phenyl-N′-stearyl urea, N-stearyl-N′-stearyl urea, xylylene bisstearyl urea, toluylene bisstearyl urea, hexamethylene bisstearyl urea, diphenylmethane bisstearyl urea, diphenylmethane bislauryl urea, etc. Substituted urea wax; polymer compounds such as polyethylene glycol, polyethylene oxide, methylcellulose, ethylcellulose, and hydroxyethylcellulose; inorganic particles such as silica particles and kaolin particles And the like. Preferably, m-xylylene bis stearamide and hexamethylene bis stearamide are used. The thixotropic agent can be used alone or in combination of two or more. The proportion of the thixotropy imparting agent is usually 0.1 to 30% by weight based on the total amount of flux.

  Examples of the antioxidant include dilauryl-3,3′-thiodipropionate, dimyristyl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, and dilauryl sulfide. 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, 2-mercaptobenzothiazole, dibenzothiazyl disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetrakis (2-ethylhexyl) thiuram disulfide, N, N'- Sulfur compounds such as diphenylthiourea, zinc dithiocarbamate, Nt-butyl-2-benzothiazolylsulfenamide, zinc butylxanthate; triethylene glycol-bis [3- (3-t-butyl-5- Methyl-4 Hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], pentaerythrityltetrakis [3- (3 5-di-t-butyl-5-methyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t-butyl-5-methyl-4-hydroxyphenyl) propionate, 1,3, Hindered phenol compounds such as 5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene; triphenyl phosphite, trisnonylphenyl phosphite, tris (2, 4-di-t-butylphenyl) phosphite, distearyl pentaerythritol diphosphite, diphe Phosphite compounds such as Louis Seo decyl phosphite.

Such antioxidants may be used alone, but are more preferably used in combination of two or more. In particular, a great synergistic effect can be exhibited by using a hindered phenol compound and a phosphite compound or a hindered phenol compound and a sulfur compound in combination. The proportion in the case of blending the antioxidant is usually 0.01 to 10% by weight with respect to the total amount of the flux composition . When a plurality of types of antioxidants are used in combination, the total amount is preferably within the above range.
Examples of the rust inhibitor include triazole compounds such as benzotriazole and methylbenzotriazole; imidazole compounds such as imidazole, methylimidazole and 2,4,5-triphenylimidazole; 1,3-diphenylguanidine. And guanidine compounds such as
Such an antirust agent can be used individually or in combination of 2 or more types. In the case of blending the rust preventive agent, 0.01 to 10% by weight is usually used with respect to the total amount of the flux composition . When a plurality of types of rust inhibitors are used in combination, the total amount is preferably within the above range.

Examples of the chelating agent include acetylacetone, acetonylacetone, 2,2′-bipyridine, 1,10-phenanthroline and the like. Such chelating agents can be used alone or in combination of two or more. Although the ratio in the case of mix | blending the said chelating agent is not specifically limited, Usually, 0-10 weight% is used with respect to the flux composition whole quantity. In the case where a plurality of types of chelating agents are used in combination, the total amount is preferably within the above range.
The total amount of the antioxidant, the rust inhibitor and the chelating agent is usually 0.01 to 30% by weight based on the total amount of the flux composition.

Examples of the leveling agent include “Polyflow No. 7”, “Polyflow No. 50E”, “Polyflow No. 55”, “Polyflow No. 75”, “Polyflow No. 77”, and “Polyflow No. 85” manufactured by Kyoeisha Chemical Co., Ltd. “Polyflow No. S”, “Polyflow No. 90” and trade names “Dispalon L-1980-50”, “Dispalon L-1982-50”, “Dispalon L-1983-50”, “Dispalon L-” manufactured by Enomoto Kasei Co., Ltd. 1984-50 "" Disparon L-1985-50 ", trade names" Surfinol 104 "," Surfinol 420 "," Surfinol 440 "," Surfinol 465 "manufactured by Air Products Japan Ltd.
Examples of the antifoaming agent include trade names “Floren AC-300HF”, “Floren AC-326F”, “Floren AC-901HF”, “Floren AC-903HF”, “Floren AC-1190HF” manufactured by Kyoeisha Chemical Co., Ltd. Trade name “Disparon LAP-10”, “Disparon LAP-20”, “Disparon LAP-30”, etc. manufactured by the same company.

Further, as the solvent, for example, a solvent having a boiling point of 150 ° C. or higher is preferable, for example, triethylene glycol monomethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, Ethylene glycol monophenyl ether, diethylene glycol monophenyl ether, diethylene glycol monobutyl acetate, dipropylene glycol, diethylene glycol-2-ethylhexyl ether, α-terpineol, benzyl alcohol, 2-hexyldecanol, butyl benzoate, diethyl maleate , Diethyl adipate, diethyl sebacate, sebacin Dibutyl, diethyl phthalate, dodecane, tetradecene, dodecylbenzene, ethylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, hexylene glycol, 1,5-pentanediol, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether acetate Propylene glycol monoethyl ether acetate, butyl carbitol acetate, 3-methoxybutyl acetate, triethylene glycol butyl methyl ether, triacetin and the like. Preferably, tetraethylene glycol dimethyl ether, triacetin or the like is used. These solvents are used alone or in combination of two or more.
The proportion in the case of blending these solvents is usually 0.1 to 50% by weight based on the total amount of the flux composition.

  Although the manufacturing method of the flux composition of this invention is not specifically limited, For example, the method of charging the said various materials collectively, the method of taking a solvent into a container, mix | blending and dissolving various materials sequentially, etc. are mentioned. Examples of the blending machine include known devices such as a kneading device, a vacuum stirring device, a homodisper, a three-one motor, and a planetary mixer. In addition, the blending temperature is not particularly limited, but it is preferable that the blending temperature is dissolved at a temperature lower than the boiling point of the solvent used.

The solder paste of this invention contains the said flux composition and solder powder.
Here, the solder powder is a solder powder composed of 75 to 99.5% by weight of tin (Sn), 0.5 to 10.0% by weight of silver (Ag) and 0 to 15.0% by weight of other metals. May be one or more solder powders selected from the group consisting of copper (Cu), indium (In), and bismuth (Bi).
The shape of the solder powder may be either spherical or indefinite.
Moreover, the average particle diameter of solder powder should just be a normal thing, and when it is spherical, 1-60 micrometers in diameter is preferable. In particular, the diameter is preferably 1 to 15 μm.
Solder powder having a diameter of 1 to 15 μm has a large surface area and tends to increase the amount of oxide film. The flux of the present invention exhibits the effect of suppressing voids even when these solder powders are used.

  The method for producing the solder paste of the present invention includes a method in which the solder powder is kneaded and blended into the flux composition by a conventional method. Examples of the machine to be blended include a vacuum stirrer, a kneader, a planetary mixer, and the like. Mixing and kneading at 5 to 25 ° C. is preferable for the temperature and conditions at the time of compounding. The blending ratio is usually 5 to 20:80 to 95 by weight ratio of flux composition: solder powder.

  The solder paste of the present invention is used as a solder for soldering in a reflow process at the time of manufacturing electronic parts, electronic modules, printed wiring boards, etc., using a solder printing machine through a metal mask plate according to a conventional method. be able to. Specifically, for example, the step (L) of providing the flux composition on the electrode part of the printed wiring board, the step (M) of preparing an electronic component on which solder bumps are formed, and the print obtained in the step (L). A method comprising a step (N) of mounting the electronic component prepared in the step (M) on the wiring board, and a step (O1) of reflowing and mounting the printed wiring board including the electronic component obtained in the step (N). The method including the step (L) and the step (O2) of supplying solder to the printed wiring board provided with the flux composition in the step (L) by a flow method or a dipping method, and the solder paste of the present invention. Step (X) for printing on electrode part of printed wiring board, step (Y) for mounting electronic component on printed wiring board obtained in step (X), and printed wiring comprising electronic component obtained in step (Y) Board Which comprises the step (Z) to implement by reflowing the like.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not restrict | limited to these.
In addition, the acid value in an example is based on the method of JIS K 0070-3 (1992). A certain amount of resin is dissolved in a tetrahydrofuran (THF) solution, and phenolphthalein is used as an indicator in a KOH / ethanol solution. And titration was performed.
The viscosity was measured with an EHD viscometer manufactured by Toki Sangyo Co., Ltd. at a temperature of 25 ° C., a rotation speed of 100 rpm, and a measurement time of 3 minutes.

The materials used in the examples and their abbreviations are as follows.
PMA was propylene glycol monomethyl ether acetate, and Kyowa Hakko Kogyo Co., Ltd. product was used.
OXT-121 is 1,4-bis {[(3-ethyl-3-oxetanyl) methoxy] methyl} benzene, and “Aron Oxetane OXT-121” (trade name) manufactured by Toagosei Co., Ltd. was used. .
OXT-101 is 3-ethyl-3-hydroxymethyloxetane, and “Aron oxetane OXT-101” (trade name) manufactured by Toagosei Co., Ltd. was used.
As the “hydrogenated rosin A”, a trade name “Pine Crystal KE-604” manufactured by Arakawa Chemical Industries, Ltd. was used.
XBSA is m-xylylene bis stearamide,
“AP-8” indicates a mixture of mono-2-ethylhexyl phosphate and di-2-ethylhexyl phosphate manufactured by Daihachi Chemical Industry Co., Ltd.
“TSL-9906” indicates a silicone resin manufactured by GE Toshiba Silicone Co., Ltd.

Further, the following three types of solder powder were used as the solder powder. In addition, the numerical value attached | subjected to the metal element name shows the weight ratio of each metal. The metal weight ratio of Sn is the remainder from 100 parts.
Sn-3.0Ag-0.5Cu (average particle size 25 μm, manufactured by Mitsui Mining & Smelting Co., Ltd.)
Sn-3.0Ag-0.5Cu (average particle size 10 μm, manufactured by Mitsui Mining & Smelting Co., Ltd.)
Sn-3.0Ag-0.5Bi-3.0In (average particle size 25 μm, manufactured by Mitsui Mining & Smelting Co., Ltd.)

Synthesis Example 1: Synthesis of Resin (A-1) In a 100 mL four-necked flask equipped with a thermometer, reflux condenser, and stirrer, 31.0 g of hexahydrophthalic anhydride, 6.9 g of ethylene glycol, and 25.0 g of PMA were added. The temperature was raised from room temperature to 140 ° C. over 30 minutes. Thereafter, the reaction was terminated after confirming that the reaction rate was 96% or more. Subsequently, after using a rotary evaporator to distill off the solvent from the mixed solution, it was vacuum dried by a vacuum pump to obtain a colorless and transparent resin (A-1).
Synthesis Example 2: Synthesis of Resin (A-2) In a 100 mL four-necked flask equipped with a thermometer, a reflux condenser, and a stirrer, 31.0 g of hexahydrophthalic anhydride, 9.9 g of trimethylolpropane, and 25.0 g of PMA Was heated from room temperature to 140 ° C. over 30 minutes. Thereafter, the reaction was terminated after confirming that the reaction rate was 96% or more. Subsequently, after using a rotary evaporator to distill off the solvent from the mixed solution, it was vacuum dried by a vacuum pump to obtain a colorless and transparent resin (A-2).

Synthesis Example 3: Synthesis of Resin (A-3) 40.0 g of Resin (A-1) obtained in Synthesis Example 1 was added to a 100 mL four-necked flask equipped with a thermometer, a reflux condenser, and a stirrer. -37.2 g of propyl vinyl ether, 22.8 g of PMA, and 0.05 g of AP-8 were charged, and the temperature was raised from room temperature to 70 ° C over 30 minutes. Then, after making it react at 70 degreeC for 3 hours, it confirmed that the acid value in a system became 1.0 mgKOH / g or less, and complete | finished reaction. Next, using a rotary evaporator, the solvent and unreacted n-propyl vinyl ether were distilled off from the mixed solution, and further vacuum-dried by a vacuum pump to obtain a colorless and transparent resin (A-3).
Synthesis Example 4: Synthesis of Resin (A-4) Into a 100 mL four-necked flask equipped with a thermometer, a reflux condenser, and a stirrer was charged 29.8 g of phthalic anhydride, 6.9 g of ethylene glycol, and 25.0 g of PMA. The temperature was raised from room temperature to 140 ° C. over 30 minutes. Thereafter, the reaction was terminated after confirming that the reaction rate was 96% or more. Subsequently, after using a rotary evaporator to distill off the solvent from the mixed solution, it was vacuum dried by a vacuum pump to obtain a colorless and transparent resin (A-4).

Synthesis Example 5: Synthesis of blocked glutaric acid A 300 mL four-necked flask equipped with a thermometer, a reflux condenser, and a stirrer was charged with 27.2 g of glutaric acid, 72.3 g of n-propyl vinyl ether, and 100.0 g of methyl ethyl ketone. The temperature was raised from room temperature to 80 ° C. over 20 minutes, and the reaction was continued for 5 hours while maintaining the same temperature. Then, after confirming that an acid value is 3.0 mgKOH / g or less, reaction was complete | finished. Subsequently, using a rotary evaporator, unreacted n-propyl vinyl ether and the solvent were distilled off from the mixed solution, followed by vacuum drying with a vacuum pump to obtain a transparent liquid. The acid value of the obtained compound was 4.2 mgKOH / g, and the viscosity was 8.3 mPa · s.
Examples 1-6
A solder paste is prepared by kneading various solder powders into the flux composition at the blending ratio shown in Table 1. For the obtained solder paste, wetting effectiveness, spreading rate, void characteristics, insulation, migration, solder balls The test was evaluated. The results are shown in Table 1.

Comparative Examples 1-6
A solder paste is prepared by kneading various solder powders into the flux composition at the blending ratio shown in Table 2, and the obtained solder paste has a wetting effect, a spreading ratio, a void characteristic, an insulating property, a migration property, and a solder ball. The test was evaluated. The results are shown in Table 2.

[Test method]
With respect to the solder pastes obtained for Examples 1 to 7 and Comparative Examples 1 to 7, wetting effectiveness, spreading rate, void characteristics, insulation, migration, and solder ball test were examined. The test method is as follows.
1. [Wetting effect]
In accordance with Annex 10 of JIS Z 3284.
The evaluation was as follows, and was in accordance with the division display of the following four grades of degree of spread.
1: The solder melted from the solder paste wets the test plate and spreads over the area where the paste is applied,
2; All parts where the solder paste is applied are in a state where the solder is wet.
3; Most of the portion where the solder paste is applied is in a state in which the solder is wet (including dewetting);
4; The test plate does not appear to have wet solder, and the molten solder becomes one or more solder balls (non-wetting)

2. [Spreading rate]
In accordance with JIS Z 3197, the spread rate of solder in soldering of a test piece using a solder paste was measured. A normal copper plate was used for the test piece.
3. [Void characteristics]
Print the solder paste obtained above on a QFP mounting test board (land size 0.35 × 2.3 mm, pitch distance 0.3 mm), place QFP components, and solder by air reflow. This was used as a test piece. The inside of this test piece was observed with an X-ray apparatus (TOSMICRON-6090FP manufactured by Toshiba IT Control System Co., Ltd.), and the void diameter ratio (maximum value) and the area ratio of the void to the area of the soldering land were determined. It calculated | required about the number of junctions 100 pieces. The average values are shown in Tables 1 and 2. In addition, the reflow conditions at the time of test piece preparation are as follows.
-Preheat: 150-160 ° C x 100 seconds-Peak temperature: 237 ° C
・ 200 ° C. or higher temperature (reflow temperature): 40 seconds [Insulation]
The test was conducted under the following two conditions in accordance with Annex 3 of JIS Z 3284.
Condition A: Temperature 40 ° C., relative humidity 90%, 200 hours Condition B: Temperature 85 ° C., relative humidity 85%, 200 hours ○: 10 ¹¹ Ω or more,
Δ: 10 ⁹ Ω or more and less than 10 ¹¹ Ω,
X: Less than -10 < ⁹ > ohm.
5. [Migration]
The test was conducted under the following two conditions in accordance with Annex 14 of JIS Z 3284.
Condition A: Temperature 40 ° C., relative humidity 90%, 1000 hours Condition B: Temperature 85 ° C., relative humidity 85%, 1000 hours [Solder ball test]
In accordance with JIS Z 3284 Annex 11, the test was conducted under the following conditions.
Condition A: Within 1 hour after printing The evaluation is as follows, according to the following classification display of the five-stage solder particle aggregation state of 1-5.
1; the solder (particles) melts and the solder becomes one large sphere, with no solder balls around it,
2; the solder (particles) melts, and the solder becomes one large sphere, and there are 3 or less solder balls with a diameter of 75 μm or less in the periphery.
3; the solder (particles) melts, and the solder becomes one large sphere, and there are four or more solder balls with a diameter of 75 μm or less in the periphery, and they are not arranged in a semi-continuous ring,
4; Solder (particles) melts into one large sphere, and many fine spheres are arranged in a semi-continuous ring around 5; Other than the above

In Examples 1-7, it became clear that generation | occurrence | production of the void of a solder joint part can be suppressed by using the flux for soldering of this invention, and a solder paste. Moreover, the wettability with respect to a copper plate was also favorable, and the solder ball characteristics were also acceptable. Furthermore, when the insulation resistance value after reflow was measured, all were 1 × 10 ¹¹ Ω or more in the A condition, and 1 × 10 ⁹ Ω or more in the B condition. In any migration test, no occurrence of migration could be confirmed.
On the other hand, in Comparative Examples 1 to 3 using a resin other than the component (A) used in the present invention, a large amount of voids are generated in the solder joint portion, and the size is as large as 110 to 125 μm at the maximum. It was a void. Furthermore, the wettability and solder ball characteristics with respect to the copper plate were poor, and the insulation and migration were also rejected. In Comparative Examples 4 to 6 using silicon compounds other than the component (B) used in the present invention, although the insulation resistance value and the migration test were acceptable levels, wetting spreadability on the copper plate and a decrease in the solder ball test were observed. It was. Further, it was found that a large amount of voids are generated in the solder joint portion, and these silicon compounds cannot suppress the generation of voids in the solder joint portion.

Claims (3)

(A) a resin obtained by subjecting a polyhydric alcohol (a1) and a cyclic acid anhydride (a2) having a carbon 6-membered ring structure to a ring-opening half esterification reaction, and (B) represented by the following formula (1) The compounding ratio of the resin (A) is 5 to 95 parts by weight per 100 parts by weight of the flux composition, and the compounding ratio of the silicon compound (B) is 0. A soldering flux composition, characterized in that the content is from 01 to 5.0% by weight .

(In formula (1), r = 2 or 3. X is a group selected from a hydrogen atom, a bromine atom, a chlorine atom, or a hydroxyl group, and may be the same or different from each other. )   A solder paste containing the soldering flux composition according to claim 1 and solder powder composed of at least two metals selected from Sn, Ag, Cu, Bi, and In.   The solder paste according to claim 2, wherein the solder powder is a solder powder having an average particle diameter of 1 to 15 μm.