KR102242412B1 - Flux composition, solder paste composition, and electronic circuit board - Google Patents

Abstract

An object thereof is to provide a flux composition and a solder paste composition capable of suppressing the stickiness of the flux residue after soldering while suppressing the occurrence of voids during reflow soldering. In order to achieve the object, the flux composition of the present invention is a flux composition that forms a solder paste composition by mixing with a solder alloy powder, (A) a base resin, (B) an activator, (C) a thixotropic agent, and ( D) contains a solvent, and as the solvent (D) (D-1) contains an organic acid ester having neither a carboxyl group nor a hydroxyl group, and the reduction rate of the organic acid ester (D-1) (using the TG method The temperature at which the measured) is 100% by mass is 180° C. or higher, and the melting peak temperature of the solder alloy constituting the solder alloy powder is +50° C. or lower, and the amount of the organic acid ester (D-1) is the solvent (D ) It characterized in that it is 10 mass%-100 mass% with respect to the total amount.

Description

Flux composition, solder paste composition, and electronic circuit board

The present invention relates to an electronic circuit board having a flux composition, a solder paste composition, and a solder joint formed by using the same.

Conventionally, in order to bond an electronic component to an electronic circuit formed on a substrate such as a printed wiring board or a silicon wafer, a solder paste composition obtained by mixing a flux and a solder alloy powder is printed on the substrate, and the electronic component is mounted at a predetermined position. A method of forming a solder joint by a heating furnace such as a reflow furnace is generally used (hereinafter, this method is referred to as a "reflow soldering method").

The reflow soldering method has a drawback that voids are liable to occur in the formed solder joints compared to the soldering method using solders molded into a predetermined shape. The main cause of the occurrence of this void is that components contained in the flux composition, particularly volatile solvents, are not discharged from the rapidly agglomerated solder when the solder alloy powder contained in the solder paste composition is melted and agglomerated.

In recent years, due to the increase in the amount of heat generated by the miniaturization of pads accompanying the miniaturization of electronic components and the high functionality of electronic components, voids that have been allowed until then have an effect on the heat dissipation of the components and the reduction of the bonding reliability. For example, in a chip component with a size of 3.2 mm x 1.6 mm, when two voids with a diameter of 200 μm and two voids with a diameter of 300 μm are generated under the electrode, the solder is compared to the case where there is no void. It has been reported that the joint life of the joint is reduced by 0.85 times and 0.63 times, respectively. As described above, the occurrence of voids in the solder joints may significantly impair the reliability of electronic devices and electronic components.

As such a method for reducing voids, conventionally, a method in which an appropriate amount of an activator is added to a flux composition to be used to improve fluidity at the time of melting of the solder to discharge gas generated inside the solder has been used. However, such an activator starts to react from the point when the solder alloy powder and the flux composition are mixed, and the activation force is already consumed to some extent in the use stage of the solder paste composition. Therefore, in this case, it is difficult to ensure sufficient wettability at the time of soldering, particularly in the electronic component having the micronized pad as described above, and it is difficult to discharge the gas from the agglomerated solder.

As a method of solving this, a method of improving the fluidity at the time of melting the solder is mentioned by mixing an activator corresponding to the consumption of the active force due to the reaction with the solder alloy powder in advance in the flux composition to make it highly active. However, if the amount of the activator is increased for high activity, the insulating property of the flux residue remaining on the substrate after soldering decreases, and thus there is a concern that a short circuit between component terminals may occur.

In addition, as another method for reducing the occurrence of voids described above, a method in which a solvent that is completely volatilized at the stage of preheating during heating is blended into the flux composition is exemplified. Usually, the solvent is used to adjust the solder paste composition to an appropriate viscosity and improve its printability. Therefore, when printing of the solder paste composition on the substrate is completed, the solvent becomes an unnecessary component.

However, in the case of using such a volatilizable solvent, since the solder paste composition is easily dried on the metal mask, there is a concern that the solder paste composition is thickened in the process of continuous printing, causing clogging of openings in the metal mask and defects in printing.

In addition, as another method of reducing the occurrence of voids in reflow soldering, the temperature at which the reduction rate becomes 15% by mass by measuring 70% by mass or more of the solvent contained in the flux by the TG method (TG-15 temperature) is A solder paste using a solvent that is 5°C or higher higher than the melting peak temperature of the solder has been proposed (refer to Patent Document 1). The amount of the solvent vaporized until the solder is melted is at most less than 15% by mass. Therefore, after the solder paste is completely melted and the solder exhibits wettability, its vaporization becomes active, so that the solvent is easily discharged from the molten solder, and thus the generation of voids is suppressed.

However, such a solvent can be used as a flux residue together with non-vaporized flux components other than the solvent (e.g., resin, thixotropic agent, activator, etc.) when only part of the solvent is vaporized or is not vaporized at all during reflow heating. It remains around the solder joint. Since the flux residue containing the solvent has a sticky property, dust or dust in the air is easily adhered. Since such a flux residue to which dust or the like adheres is deteriorated in insulation, there is a concern that the reliability thereof is remarkably impaired.

Further, the flux residue may be removed by washing with a detergent after soldering. However, in recent years, a non-clean type solder paste composition is widely used from the viewpoint of cost and environment, and the importance of a solder paste composition capable of suppressing the stickiness of the flux residue while suppressing the occurrence of voids is increasing.

Japanese Patent No. 4458043

It is an object of the present invention to solve the above problems, and in particular, to provide a flux composition and a solder paste composition capable of suppressing the stickiness of the flux residue after soldering while suppressing the occurrence of voids during reflow soldering.

(1) The flux composition of the present invention is mixed with a solder alloy powder to constitute a solder paste composition, and contains (A) a base resin, (B) an activator, (C) a thixotropic agent, and (D) a solvent. And, as the solvent (D), (D-1) an organic acid ester having neither a carboxyl group nor a hydroxyl group is included, and the reduction rate (measured using the TG method) of the organic acid ester (D-1) is 100 The temperature at which the mass% is reached is 180° C. or higher, and the melting peak temperature of the solder alloy constituting the solder alloy powder is +50° C. or lower, and the amount of the organic acid ester (D-1) is 10 with respect to the total amount of the solvent (D). It is characterized in that it is in a mass% to 100 mass%.

(2) In the configuration described in (1) above, the reduction rate (TG) of the organic acid ester (D-1) in the case where the melting peak temperature of the solder alloy constituting the solder alloy powder is 130°C or more and less than 175°C It is characterized in that the temperature at which (measured using the method) is 100% by mass is 180°C or more and less than 225°C.

(3) In the configuration described in the above (1), the reduction rate (TG) of the organic acid ester (D-1) in the case where the melting peak temperature of the solder alloy constituting the solder alloy powder is 175°C or more and less than 200°C It is characterized in that the temperature at which (measured using the method) is 100% by mass is 180°C or higher and less than 250°C.

(4) In the configuration described in (1) above, the reduction rate of the organic acid ester (D-1) in the case where the melting peak temperature of the solder alloy constituting the solder alloy powder is 200°C or higher (using the TG method) It is characterized in that the temperature at which the measured) is 100% by mass is 180°C or higher and the melting peak temperature +50°C or lower.

(5) In the configuration described in the above (2), the organic acid ester (D-1) is characterized in that it is at least one of dimethyl adipate and dibutyl maleate.

(6) In the configuration described in the above (3), the organic acid ester (D-1) is dimethyl adipate, diisopropyl adipate, dibutyl maleate, dimethyl sebacate, diisobutyl adipate and di sebacate. It is characterized in that it is at least one selected from ethyl.

(7) In the configuration described in the above (4), the organic acid ester (D-1) is dimethyl adipate, diisopropyl adipate, dibutyl maleate, dimethyl sebacate, diisobutyl adipate, di sebacate. It is characterized in that it is at least one selected from ethyl, diisopropyl sebacate, dibutyl sebacate, and dioctyl sebacate.

(8) In the configuration described in any one of (1) to (7), the base resin (A) contains at least one of (A-1) rosin-based resin and (A-2) synthetic resin, The synthetic resin (A-2) is an acrylic resin, a styrene-maleic acid resin, an epoxy resin, a urethane resin, a polyester resin, a phenoxy resin, a terpene resin, a polyalkylene carbonate and a rosin resin having a carboxyl group and a dimer. It is characterized in that it is at least one selected from the group consisting of derivative compounds obtained by dehydrating and condensing an acid derivative flexible alcohol compound.

(9) The solder paste composition of the present invention is characterized by containing the flux composition according to any one of the above (1) to (8) and a solder alloy powder.

(10) In the configuration described in the above (9), the solder alloy powder contains Ag from 2% by mass to 3.1% by mass, Cu from 0% by mass to 1% by mass, and Sb from 1% by mass to 5% by mass. And 0.5% by mass or more and 4.5% by mass or less of Bi and 0.01% by mass or more and 0.25% by mass or less of Ni, and the remainder is composed of Sn.

(11) In the configuration described in the above (10), the solder alloy powder further contains 0.001% by mass or more and 0.25% by mass or less of Co.

(12) The electronic circuit board of the present invention is characterized by having a solder joint formed using the solder paste composition according to any one of (9) to (11) above.

According to the present invention, it is possible to provide a flux composition and a solder paste composition capable of suppressing the stickiness of the flux residue after soldering while suppressing the occurrence of voids during reflow soldering.

An embodiment of the flux composition, solder paste composition, and electronic circuit board of the present invention will be described in detail below. In addition, it goes without saying that the present invention is not limited to these embodiments.

(1) flux composition

The flux composition of this embodiment contains (A) a base resin, (B) an activator, (C) a thixotropic agent, and (D) a solvent.

(A) base resin

As said base resin (A), it is preferable to use at least one of (A-1) rosin-type resin and (A-2) synthetic resin, for example.

Examples of the rosin-based resin (A-1) include rosin such as tall oil rosin, gum rosin, and wood rosin; Rosin derivatives subjected to polymerization, hydrogenation, heterogeneity, acrylation, maleation, esterification, or phenol addition reaction of rosin; A modified rosin resin obtained by reacting these rosin or rosin derivatives with unsaturated carboxylic acids (acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, etc.) can be mentioned. Among these, a modified rosin resin is particularly preferably used, and a hydrogenated acrylic acid-modified rosin resin obtained by reacting acrylic acid and hydrogenating it is particularly preferably used. Moreover, these may be used individually by 1 type or in mixture of multiple types.

Further, the acid value of the rosin-based resin (A-1) is preferably 140 mgKOH/g to 350 mgKOH/g, and its weight average molecular weight is preferably 200 Mw to 1,000 Mw.

Examples of the synthetic resin (A-2) include acrylic resin, styrene-maleic acid resin, epoxy resin, urethane resin, polyester resin, phenoxy resin, terpene resin, polyalkylene carbonate, and rosin having a carboxyl group. And a derivative compound obtained by dehydrating and condensing a type resin and a dimer acid derivative flexible alcohol compound. Moreover, these may be used individually by 1 type or in mixture of multiple types.

The acrylic resin is obtained, for example, by homopolymerizing a (meth)acrylate having an alkyl group having 1 to 20 carbon atoms or copolymerizing a monomer containing the acrylate as a main component. Among such acrylic resins, acrylic resins obtained by polymerizing monomers including monomers having methacrylic acid and two saturated alkyl groups having 2 to 20 carbon atoms having a linear carbon chain are preferably used. In addition, the said acrylic resin may be used individually by 1 type or in mixture of multiple types.

As the epoxy resin, any thermosetting resin having a reactive epoxy group at its terminal can be used. For example, bisphenol A type, bisphenol F type, bisphenol S type, biphenyl type, naphthalene type, cresol novolak type, Phenol novolak type, brominated bisphenol A type, hydrogenated bisphenol A type, bisphenol AF type, fluorene type, glycidyl ether type, glycidyl ester type, glycidylamine type, alicyclic epoxy resin, etc. have. Moreover, these may be used individually by 1 type or in mixture of multiple types.

As the urethane resin, for example, any one obtained by reacting a compound having a plurality of isocyanate groups in one molecule and a polyol compound having two or more hydroxyl groups in one molecule can be used. Polyurethane resin containing is preferably used. Moreover, the said urethane resin may be used individually by 1 type or in mixture of multiple types.

Examples of the polyester resin include polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polybutylene naphthalate. Moreover, these may be used individually by 1 type or in mixture of multiple types.

Examples of the phenoxy resin include bisphenol A phenoxy resin and bisphenol F phenoxy resin. Moreover, these may be used individually by 1 type or in mixture of multiple types.

Examples of the polyalkylene carbonate include polyethylene carbonate, polypropylene carbonate, polybutene carbonate, polyisobutene carbonate, polypentene carbonate, polyhexene carbonate, and polycyclo Pentene carbonate, polycyclohexene carbonate, polycycloheptene carbonate, polycyclooctene carbonate, polylimonene carbonate, etc., polypropylene carbonate, polybutylene carbonate, etc. are mentioned. . Moreover, these may be used individually by 1 type or in mixture of multiple types.

With respect to the derivative compound (hereinafter referred to as ``rosin derivative compound'') obtained by dehydrating condensation of the rosin-based resin having a carboxyl group and a flexible alcohol compound of a dimer acid derivative (hereinafter referred to as ``rosin derivative compound''), first, as a rosin-based resin having a carboxyl group, for example, tall oil rosin, Rosin such as gum rosin and wood rosin; Rosin derivatives such as hydrogenated rosin, polymerized rosin, heterogeneous rosin, acrylic acid-modified rosin, and maleic acid-modified rosin, and the like. In addition to these, any rosin having a carboxyl group can be used. Moreover, these may be used individually by 1 type or in mixture of multiple types.

Next, examples of the dimer acid derivative flexible alcohol compound include compounds derived from dimer acids such as dimerdiol, polyester polyol, and polyester dimerdiol, and those having an alcohol group at the terminal thereof. PRIPOL2033, PRIPLAST3197, PRIPLAST1838 (above, Kuroda Japan Co., Ltd. product), etc. can be used.

The rosin derivative compound is obtained by dehydrating condensation of the rosin resin having a carboxyl group and the dimer acid derivative flexible alcohol compound. As a method of this dehydration and condensation, a method generally used can be used. Further, the preferred weight ratio when dehydrating and condensing the rosin-based resin having a carboxyl group and the dimer acid derivative flexible alcohol compound is 25:75 to 75:25, respectively.

The acid value of the synthetic resin (A-2) is preferably 0 mgKOH/g to 150 mgKOH/g, and its weight average molecular weight is preferably 1,000 Mw to 30,000 Mw.

In addition, the blending amount of the base resin (A) is preferably 10% by mass or more and 60% by mass or less, and more preferably 30% by mass or more and 55% by mass or less with respect to the total amount of the flux composition.

When the said rosin-type resin (A-1) is used individually, it is preferable that it is 10 mass% or more and 50 mass% or less with respect to the total amount of a flux composition, and it is more preferable that it is 15 mass% or more and 45 mass% or less. By setting the blending amount of the rosin-based resin (A-1) in this range, it is possible to achieve satisfactory solderability and an appropriate amount of residual flux.

Moreover, when using the said synthetic resin (A-2) alone, it is preferable that it is 10 mass% or more and 60 mass% or less with respect to the total amount of a flux composition, and it is more preferable that it is 15 mass% or more and 50 mass% or less.

In addition, when the rosin-based resin (A-1) and the synthetic resin (A-2) are used in combination, the blending ratio is preferably 20:80 to 50:50, and more preferably 25:75 to 40:60. desirable.

(B) activator

Examples of the activator (B) include compounds containing carboxylic acids and halogens. These may be used alone or in combination of multiple types.

Examples of the carboxylic acids include monocarboxylic acids, dicarboxylic acids, and other organic acids.

Examples of the monocarboxylic acid include propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, capric acid, lauric acid, myristic acid, pentadecyl acid, palmitic acid, margaric acid, stearic acid, And tuberculostearic acid, arachidic acid, behenic acid, lignoceric acid, glycolic acid, and the like.

Examples of the dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, tartaric acid, and diglycolic acid.

Further, examples of the other organic acids include dimer acid, levulinic acid, lactic acid, acrylic acid, benzoic acid, salicylic acid, aniseic acid, citric acid, picolinic acid, and the like.

Moreover, these may be used individually by 1 type or in mixture of multiple types.

Examples of the halogen-containing compound include a non-dissociable halogen compound (non-dissociation type activator) and a dissociable halogen compound (dissociation type activator).

Examples of the non-dissociating activator include non-salt-based organic compounds in which a halogen atom is bonded by a covalent bond. For example, chlorine, bromine, iodine, and fluoride, such as chlorine, bromide, iodide, and fluoride. The compound may be a covalent bond, or a compound which bonds two or more different halogen atoms thereof by a covalent bond. In order to improve the solubility in an aqueous solvent, the compound preferably has a polar group such as a hydroxyl group such as a halogenated alcohol. Examples of the halogenated alcohol include brominated alcohols such as 2,3-dibromopropanol, 2,3-dibromobutanediol, 1,4-dibromo-2-butanol, and tribromoneopentyl alcohol; Chlorinated alcohols such as 1,3-dichloro-2-propanol and 1,4-dichloro-2-butanol; Fluorinated alcohols such as 3-fluorocatechol; Other compounds similar to these may be mentioned.

In addition, examples of the dissociation-type activator include hydrochloric acid salts and hydrobromide salts of bases such as amines and imidazoles. Examples of salts of hydrochloric acid and hydrobromic acid include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, n-propylamine, di-n-propylamine, tri-n-propylamine, iso Amines having a relatively small carbon number such as propylamine, diisopropylamine, butylamine, dibutylamine, tributylamine, cyclohexylamine, monoethanolamine, diethanolamine, and triethanolamine; Imidazole, 2-methylimidazole, 2-ethylimidazole, 2-methyl-4-methylimidazole, 2-methyl-4-ethylimidazole, 2-ethyl-4-ethylimidazole, Hydrochloric acid salts, such as 2-propylimidazole and 2-propyl-4-propylimidazole, and hydrobromide, etc. are mentioned. These may be used alone or in combination of multiple types.

The blending amount of the activator (B) is preferably 0.1% by mass or more and 30% by mass or more, and more preferably 2% by mass or more and 25% by mass or less with respect to the total amount of the flux composition.

The blending amount of the carboxylic acids used in the activator (B) is preferably 1% by mass or more and 25% by mass or less, and more preferably 5% by mass or more and 15% by mass or less with respect to the total amount of the flux composition. By setting the blending amount of carboxylic acids into this range, it is possible to suppress generation of solder balls and exhibit good insulation properties of the flux composition.

Further, the amount of the non-dissociated activator used in the activator (B) is preferably 0.1% by mass or more and 5% by mass or less, and more preferably 0.5% by mass or more and 3% by mass or less with respect to the total amount of the flux composition.

Next, the amount of the dissociating activator used in the activator (B) is preferably 0.1% by mass or more and 3% by mass or less, and more preferably 0.3% by mass or more and 1.5% by mass or less with respect to the total amount of the flux composition.

In addition, when the amine and imidazole are used individually as the dissociating activator, the blending amounts are preferably 0.1% by mass or more and 5% by mass or less, and more preferably 0.5% by mass or more and 3% by mass or less.

(C) thixotropic agent

Examples of the thixotropic agent (C) include hydrogenated castor oil, saturated fatty acid amide, saturated fatty acid bisamide, oxy fatty acid, and dibenzylidenesorbitol. These may be used alone or in combination of multiple types.

In addition, the blending amount of the thickener is preferably 1% by mass or more and 15% by mass or less, and more preferably 3% by mass or more and 10% by mass or less with respect to the total amount of the flux.

(D) solvent

Examples of the solvent (D) include isopropyl alcohol, ethanol, acetone, toluene, xylene, ethyl acetate, ethyl cellosolve, butyl cellosolve, hexyldiglycol, (2-ethylhexyl)diglycol, phenylglycol , Butylcarbitol, octanediol, α terpineol, β terpineol, tetraethylene glycol dimethyl ether, trimellitic acid tris (2-ethylhexyl), bisisopropyl sebacate, and the like can be used. These may be used alone or in combination of multiple types.

In the flux composition of the present embodiment, it is preferable that the solvent (D) contains an organic acid ester having neither a carboxyl group nor a hydroxyl group (D-1).

As the solvent used in the flux composition, it is common to use a component containing either a carboxyl group or a hydroxyl group. Among the components of the flux composition, the active agent is ionized when dissolved in such a solvent, thereby generating negatively charged organic acid ions (RCOO-) or halide ions. The carboxyl groups and hydroxyl groups tend to be oriented around these ions, and as a result, they are solvated, and the reaction of the solder alloy powder and the solvent occurs.

However, since the organic acid ester (D-1) does not have any of the carboxyl group and the hydroxyl group, in the flux composition of the present embodiment, there is no functional group that is liable to be oriented to the ion ionized from the activator (B). It is difficult to become plum. Therefore, the solder paste composition using the flux composition of the present embodiment can suppress the reaction between the solder alloy powder and the activator in a non-heated storage state.

As described above, since the flux composition containing the organic acid ester (D-1) can suppress the reaction between the solder alloy powder and the activator (B) during storage of the solder paste composition, the activity and the amount of the activator (B) can be reduced. Even without adjustment, the active force remains, and good wettability in soldering is ensured, and generation of voids can be suppressed.

In addition, even if the organic acid ester (D-1) remains in the flux residue formed on the substrate, the organic acid ester (D-1) does not have any of a carboxyl group and a hydroxyl group as described above, so the moisture absorption of the flux residue is Since it can be suppressed, it is thought that it is difficult to affect the insulating properties of the flux residue.

In addition, the loss ratio (measured using the TG method) of the organic acid ester (D-1). Specifically, the TG curve was measured using a thermogravimetric-differential thermal analysis device, and the reduction ratio was calculated by this. It is preferable that the temperature at which ha) is 100% by mass is 180° C. or higher, and the melting peak temperature of the solder alloy constituting the solder alloy + 50° C. or lower. Since such organic acid ester (D-1) can suppress the stickiness of the flux residue formed on the substrate, it is possible to impart good insulating properties to the flux residue.

That is, the general reflow heating conditions of the solder paste composition are often set such that the peak temperature of the main heating is 10°C to 50°C higher than the melting peak temperature of the solder.

As a result of intensive research, the present inventors have found that the above organic acid ester in which the loss rate becomes 100% by mass at a temperature higher than 180°C as the solvent (D) in the flux composition and within 50°C above the melting peak temperature of the solder alloy to be used ( By blending D-1), drying on the metal mask at the time of printing becomes difficult to occur, and stable continuous printability can be ensured, and further formed while suppressing the occurrence of voids under the above reflow heating conditions. It was found that stickiness of the flux residue can be suppressed.

For example, when the peak temperature of the solder alloy of the solder alloy powder used for mixing is 130°C or more and less than 175°C, the organic acid ester (D-1) has a temperature at which the loss rate is 100% by mass. It is preferably used at a temperature higher than or equal to or less than 225C. As such an organic acid ester (D-1), dimethyl adipate, dibutyl maleate, etc. are mentioned, for example. These may be used alone or in combination of multiple types.

Further, for example, in the case where the peak temperature of the solder alloy of the solder alloy powder used for mixing is 175°C or more and less than 200°C, the organic acid ester (D-1) has a temperature at which the reduction rate is 100% by mass. What is 180 degreeC or more and also less than 250 degreeC is used preferably. Examples of such organic acid ester (D-1) include dimethyl adipate, diisopropyl adipate, dibutyl maleate, dimethyl sebacate, diisobutyl adipate, and diethyl sebacate. These may be used alone or in combination of multiple types.

Further, for example, when the peak temperature of the solder alloy of the solder alloy powder used for mixing is 205°C or higher, the organic acid ester (D-1) has a temperature at which the loss rate is 100% by mass, 180°C or higher. In addition, those having a melting peak temperature of +50°C or lower of the solder alloy constituting the solder alloy are preferably used. As such an organic acid ester (D-1), for example, dimethyl adipate, diisopropyl adipate, dibutyl maleate, dimethyl sebacate, diisobutyl adipate, diethyl sebacate, diisopropyl sebacate, Dibutyl sebacate, dioctyl sebacate, and the like. These may be used alone or in combination of multiple types.

The blending amount of the solvent (D) is preferably 20% by mass or more and 65% by mass or less with respect to the total amount of the flux composition. A more preferable blending amount is 20% by mass or more and 60% by mass or less, and a particularly preferable blending amount is 25% by mass or more and 50% by mass or less.

In addition, the amount of the organic acid ester (D-1) to be blended is preferably 10% by mass to 100% by mass based on the total amount of the solvent (D).

In addition, additives can be blended into the flux composition of the present embodiment as necessary. Examples of the additives include antioxidants, defoaming agents, surfactants, and matting agents. These may be used alone or in combination of multiple types.

Moreover, it is preferable that it is 0.5 mass% or more and 20 mass% or less, and, as for the blending amount of the said additive, it is more preferable that it is 1 mass% or more and 15 mass% or less with respect to the total amount of the flux.

(2) Solder paste composition

The solder paste composition of this embodiment is obtained by mixing the flux composition and solder alloy powder.

As the solder alloy powder, any solder alloy powder of solder/lead may be used. That is, the solder paste composition of the present embodiment uses the organic acid ester (D-1) suitable for its melting peak temperature regardless of the components of the solder alloy powder to be used, thereby suppressing the occurrence of voids during reflow soldering. The stickiness of the flux residue afterwards can be suppressed.

In addition, examples of alloys that can be used in the solder alloy powder include an alloy containing Sn and Pb, an alloy containing Sn and Pb, and at least one of Ag, Bi and In, an alloy containing Sn and Ag, An alloy containing Sn and Cu, an alloy containing Sn, Ag and Cu, and an alloy containing Sn and Bi. In addition to these, for example, a solder alloy powder obtained by appropriately combining Sn, Pb, Ag, Bi, In, Cu, Zn, Ga, Sb, Au, Pd, Ge, Ni, Cr, Al, P, etc. can be used. . In addition, it is possible to use the elements other than those exemplified above for their combination.

In addition, among these, in particular, solder alloy powder containing Sb, Ag, and Cu, such as Sn-Ag-based solder alloy, Sn-Ag-Cu-based solder alloy, and Sn-Ag-Cu-Bi-Sb-based solder alloy powder. Is preferably used.

In addition, among these, in particular, when a solder alloy powder having an alloy composition exemplified below is used, the effect of suppressing crack propagation of the formed solder joint can be improved.

That is, the solder alloy powder contains Ag from 1% by mass to 3.1% by mass, Cu from 0% by mass to 1% by mass, Sb from 1% by mass to 5% by mass, and Bi from 0.5% by mass to 4.5% by mass. , Ni is preferably 0.01% by mass or more and 0.25% by mass or less, and the remainder is preferably made of Sn.

Further, a more preferable content of Ag is 2% by mass or more and 3.1% by mass or less, a more preferable content of Cu is 0.5% by mass or more and 1% by mass or less, and a more preferable content of Sb is 2% by mass or more and 4% by mass or less, A more preferable content of Bi is 3.1% by mass or more and 4.5% by mass, and a more preferable content of Ni is 0.01% by mass or more and 0.15% by mass or less.

Moreover, it is preferable that the said solder alloy powder further contains 0.001 mass% or more and 0.25 mass% or less of Co. More preferable Co content is 0.001 mass% or more and 0.15 mass% or less.

By using such a solder alloy powder, the solder joint formed by using the solder paste composition according to the present embodiment can suppress the crack propagation of the solder joint even under a severe environment in which the difference in temperature is severe and vibration is loaded. In addition, even in the case of solder bonding using Ni/Pd/Au plating or electronic components that do not have Ni/Au plating, crack propagation in the vicinity of the interface between the solder joint and the lower electrode of the electronic component can be suppressed. .

It is preferable that the blending amount of the solder alloy powder is 65% by mass to 95% by mass based on the total amount of the solder paste composition. A more preferable blending amount is 85% by mass to 93% by mass, and a particularly preferable blending amount is 87% by mass to 92% by mass.

When the blending amount of the solder alloy powder is less than 65% by mass, sufficient solder joints tend to be difficult to form when the resulting solder paste composition is used. On the other hand, when the content of the solder alloy powder exceeds 95% by mass, since the flux composition as a binder is insufficient, it tends to be difficult to mix the flux composition and the solder alloy powder.

Further, the particle diameter of the solder alloy powder is preferably 1 µm or more and 40 µm or less, more preferably 5 µm or more and 35 µm or less, and particularly preferably 10 µm or more and 30 µm or less.

The solder paste composition of the present embodiment uses a flux composition containing the organic acid ester (D-1) suitable for the melting peak temperature of the solder alloy of the solder alloy powder, thereby suppressing the occurrence of voids during reflow soldering and the flux after soldering. It can suppress the stickiness of the residue.

(3) electronic circuit board

It is preferable that the electronic circuit board of this embodiment has a solder joint and a flux residue (in this specification, a solder joint and a flux residue are referred to as a ``solder joint'' together) formed using the above solder paste composition. In the electronic circuit board, for example, an electrode and a solder resist film are formed at a predetermined position on the substrate, and the solder paste composition of the present embodiment is printed using a mask having a predetermined pattern, and an electronic component suitable for the pattern is Is mounted in a predetermined position, and is produced by reflowing it.

In the electronic circuit board thus produced, a solder joint is formed on the electrode, and the solder joint electrically joins the electrode and the electronic component. Further, on the substrate, a flux residue is attached so as to adhere at least to the solder joint.

In the electronic circuit board of the present embodiment, since the solder joint portion and the flux residue are formed using the solder paste composition, voids are less likely to occur in the solder joint portion, and the flux residue can be made difficult to become sticky. Further, by setting the alloy composition of the solder alloy powder to a specific element and content, the effect of suppressing the crack propagation of the solder joint can be improved.

Example

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. In addition, the present invention is not limited to these examples.

<Production of synthetic resin>

200 g of diethylene glycol monohexyl ether was put into a 500 ml 4-neck flask equipped with a stirrer, a reflux tube, and a nitrogen introduction tube, and this was heated to 110°C.

Further, to 300 g of a mixture of 10% by mass of methacrylic acid, 51% by mass of 2-ethylhexyl methacrylate, and 39% by mass of lauryl acrylate, dimethyl2,2′-azobis(2-methylpropane) Cypionate) (product name: V-601, manufactured by Wako Pure Chemical Industries, Ltd.) was added 0.2% by mass to 5% by mass, and this was dissolved to prepare a solution.

Subsequently, the solution was added dropwise to the four-neck flask over 1.5 hours, stirred at 110° C. for 1 hour, and then the reaction was terminated to obtain a synthetic resin (A-2) used in Examples. Moreover, the weight average molecular weight of this synthetic resin (A-2) was 7,800 Mw, the acid value was 40 mgKOH/g, and the glass transition temperature was -47 degreeC.

<Preparation of solder paste composition>

Each component described in Tables 1 to 4 was kneaded to obtain each flux composition according to Examples 1 to 34 and Comparative Examples 1 to 13. Subsequently, 11 mass% of each of the flux compositions and 89 mass% of the following solder alloy powder were kneaded to obtain respective solder paste compositions according to Examples 1 to 34 and Comparative Examples 1 to 13. In addition, unless otherwise specified, the numerical values shown in Tables 1 to 4 shall mean mass%.

In addition, as for the synthetic resin (A-2), a solvent-shaped resin produced by the above-described procedure is used after volatilizing the solvent using an evaporator. Therefore, the numerical value of the synthetic resin (A-2) described in Tables 1 to 4 shows only the solid content obtained by volatilizing the solvent.

In addition, the solder alloy powder used in each Example and a comparative example is as follows.

Examples 1 to 20 and Comparative Examples 1 to 8: Sn-3Ag-0.5Cu solder alloy powder (melting peak temperature: 219°C)

Examples 21 and 22, and Comparative Example 9: Sn-10Sb (melting peak temperature: 248°C)

Examples 23 and 24, and Comparative Examples 10 and 11: Sn-58Bi (melting peak temperature: 139° C.)

Examples 25 to 28 and Comparative Example 12: Sn-3.5Ag-0.5Bi-8In (melting peak temperature: 202°C)

-Examples 29 and 30: Sn-3Ag-0.7Cu-3.5Bi-3Sb-0.04Ni-0.01Co (melting peak temperature: 223° C.)

-Examples 31 and 32: Sn-3Ag-0.5Cu-4.5Bi-3Sb-0.03Ni (melting peak temperature: 222° C.)

-Examples 33 and 34: Sn-3Ag-0.5Cu-3Bi-2Sb-0.03Ni (melting peak temperature: 223° C.)

-Comparative Example 13: Sn-0.5Ag-0.5Cu-3Bi-2Sb-0.04Ni (melting peak temperature: 228°C)

For each organic acid ester (D-1) component, a thermogravimetric measurement-differential thermal analysis device (product name: STA7200RV, manufactured by Hitachi Hi-Tech Science Co., Ltd.) was used, and the temperature at which the loss rate in the TG curve becomes 100% by mass was measured. It measured and described together with the component names of Tables 1-4. In addition, as for the measurement conditions, the temperature increase rate was 10°C/min, the nitrogen gas flow rate was 200 ml/min, and the sample amount was 10 mg.

※1 Hydrogenated acid-modified rosin manufactured by Arakawa Chemical Industry Co., Ltd.

※2 Nippon Kasei Co., Ltd. fatty acid bisamide

※3 BASF Japan's hindered phenolic antioxidant

<Print recovery test>

A glass epoxy substrate having a solder resist having a pattern capable of mounting a 100-pin 0.5 mm pitch BGA and an electrode (0.25 mm in diameter), and a metal mask having a thickness of 120 μm having the same pattern as the above pattern were prepared.

Subsequently, each solder paste composition was printed on the substrate using the metal mask. In addition, this printing was performed by a method of continuously printing one type of solder paste composition using six of the above substrates.

After performing the continuous printing, each solder paste composition on the metal mask was allowed to stand in an environment of 25°C-50% for 1 hour.

Thereafter, each solder paste composition on this metal mask was printed on the substrate. In addition, this printing was performed by a method of continuously printing one type of solder paste composition using 10 of the above substrates.

With respect to the substrate subjected to the continuous printing, the transfer volume ratio in the electrode portion having a diameter of 0.25 mm from the 5th to the 10th printing order was measured using an image inspection machine (product name: aspire2, manufactured by Koyoung Technology Co., Ltd.). It measured and evaluated according to the following criteria. The results are shown in Tables 5 to 8.

◎: The number of transfer volume ratio of 35% or less is 0

○: The number of transfer volume ratio of 35% or less is 1 or more and 10 or less

△: The number of transfer volume ratio of 35% or less is 11 or more and 50 or less

X: 51 or more of the number of transfer volume ratio of 35% or less

<Flux residue adhesion test>

A glass epoxy substrate having a solder resist having a pattern of 6 mm in diameter and a copper land, and a metal mask having a thickness of 150 µm having the same pattern as the pattern were prepared. Subsequently, each solder paste composition was printed on the glass epoxy substrate using the metal mask, and these were heated using a reflow furnace (product name: TNP-538EM, manufactured by Tamura Seisakusho Co., Ltd.) to prepare each test substrate. did. In addition, the reflow conditions differ depending on the composition of the solder alloy powder used for each printed solder paste composition. The conditions are as follows. In addition, in any case, the oxygen concentration in the reflow furnace is 1500±500 ppm.

ㆍ Examples 1 to 20 and Comparative Examples 1 to 8: Pre-heat at 170°C to 180°C for 90 seconds, peak temperature 230°C, 220°C or higher for 30 seconds or less, and cooling rate from peak temperature to 200°C is 3°C To 8°C/sec

-Examples 21 and 22, and Comparative Example 9: Pre-heating at 180°C to 200°C for 90 seconds, peak temperature of 265°C, 250°C or higher for 30 seconds or less, and cooling rate from peak temperature to 235°C of 3°C to 8℃/sec

ㆍ Examples 23 and 24, and Comparative Examples 10 and 11: Pre-heat at 100 ℃ to 110 ℃ for 90 seconds, the peak temperature 160 ℃, 150 ℃ or more is 30 seconds or less, the cooling rate from the peak temperature to 120 ℃ is 3 °C to 8 °C/sec

-Examples 25 to 28 and Comparative Example 12: Pre-heating at 150°C to 170°C for 90 seconds, peak temperature 220°C, 210°C or higher for 30 seconds or less, cooling rate from peak temperature to 190°C is 3°C to 8 ℃/sec

ㆍ Examples 29 to 34: Preheating at 170°C to 180°C for 90 seconds, peak temperature 230°C, 220°C or higher is 30 seconds or less, and cooling rate from peak temperature to 200°C is 3°C to 8°C/second

ㆍ Comparative Example 13: Preheating at 170°C to 180°C for 90 seconds, peak temperature of 240°C, 230°C or higher for 30 seconds or less, cooling rate from peak temperature to 200°C is 3°C to 8°C/second

Then, after leaving each test board at room temperature for 2 hours, a solder ball having a diameter of 300 μm was sprinkled on the flux residue formed on each test board soldered in a 6 mm diameter pattern, and the side of each test board was parallel to the ground. I threw it on my desk and shocked me. Thereafter, the number of solder balls adhered to the flux residue on each test board was counted, and the following criteria were evaluated. The results are shown in Tables 5 to 8.

◎: The number of solder balls attached is 0

○: The number of solder balls attached is 1 or more and 10 or less

△: The number of solder balls attached is 11 or more and 30 or less

×: The number of solder balls attached is 31 or more

<Production of continuous rolling paste>

For each solder paste composition, using a polyurethane rubber squeegee (hardness 90), a squeegee angle of 60°, a printing tact of 30 seconds and a stroke of 300 mm, an environment of 25°C-50% RH for 4 hours, continuously Quizing was performed.

In addition, the sample input amount was 500 g. Each solder paste composition after continuous squeezing obtained in this way is hereinafter referred to as "continuous rolling paste".

<Solder Ball Test>

A glass epoxy substrate and a chip component having a size of 2.0 mm x 1.2 mm were prepared. Each solder paste composition on the glass epoxy substrate by forming a solder resist and an electrode (1.25 mm×1.0 mm) corresponding to the chip component on the glass epoxy substrate, and using a metal mask having a thickness of 150 μm having the same pattern as this And each continuous rolling paste were printed, respectively, and chip parts were mounted. Subsequently, each glass epoxy substrate was heated in a reflow furnace (product name: TNP-538EM, Tamura Seisakusho Co., Ltd.) to prepare each test substrate. In addition, the reflow conditions differ depending on the composition of each printed solder paste composition and the solder alloy powder used for each continuous rolling paste. The conditions are as follows. In addition, in any case, the oxygen concentration in the reflow furnace is 1500±500 ppm.

ㆍ Examples 1 to 20 and Comparative Examples 1 to 8: Preheating at 170°C to 190°C for 110 seconds, peak temperature of 260°C, 200°C or higher for 70 seconds and 220°C or higher for 60 seconds, from peak temperature to 200°C The cooling rate of 3 ℃ to 8 ℃ / second

ㆍ Examples 21 and 22, and Comparative Example 9: Pre-heating at 180°C to 210°C for 110 seconds, peak temperature of 290°C, 230°C or higher for 70 seconds, and 250°C or higher for 60 seconds, from peak temperature to 235°C The cooling rate is 3°C to 8°C/sec

ㆍExamples 23 and 24, and Comparative Example 10 and Comparative Example 11: Preheat at 100°C to 120°C for 110 seconds, peak temperature 210°C, 130°C or higher for 70 seconds and 150°C or higher for 60 seconds, from the peak temperature Cooling rate up to 150°C is 3°C to 8°C/sec

ㆍ Examples 25 to 28 and Comparative Example 12: Preheat cooling from 150°C to 180°C for 110 seconds, peak temperature 250°C, 190°C or higher for 70 seconds and 210°C or higher for 60 seconds, and from peak temperature to 190°C The speed is 3°C to 8°C/sec

-Examples 29 to 34: Preheating at 170°C to 190°C for 110 seconds, peak temperature of 260°C, 200°C or higher for 70 seconds and 220°C or higher for 60 seconds, and cooling rate from peak temperature to 200°C for 3°C To 8°C/sec

ㆍComparative Example 13: Pre-heating at 170°C to 190°C for 110 seconds, peak temperature of 260°C, 200°C or higher for 70 seconds, and 220°C or higher for 60 seconds, and the cooling rate from peak temperature to 200°C is 3°C to 8 ℃/sec

Each of the above test boards was observed using an X-ray transmission device (product name: SMX-160E, manufactured by Shimadzu Corporation), and the number of solder balls generated on the periphery of the chip component and its lower surface and its diameter were counted. Evaluated as. The results are shown in Tables 5 to 8.

◎: 0 balls per 10 2.0mm×1.2mm chip resistors

○: The number of balls generated per 10 2.0mm×1.2mm chip resistors is 1 or more and 5 or less

△: The number of balls generated per 10 2.0mm×1.2mm chip resistors is 6 or more and 10 or less

×: The number of balls generated per 10 2.0 mm×1.2 mm chip resistors is 11 or more

<Void test>

Each test board was prepared under the same conditions as the solder ball test, and the surface condition was observed with an X-ray transmission device (product name: SMX-160E, manufactured by Shimadzu Corporation), and occupied the area where the solder joint was formed. The ratio of the total area of the voids (area ratio of the voids) was measured. In addition, the occurrence state of voids was evaluated by obtaining the maximum value of the area ratio of voids in lands at 20 locations among each test board. The results are shown in Tables 5 to 8.

◎: The maximum value of the area ratio of voids is 10% or less

○: The maximum value of the void area ratio is more than 10% and 13% or less

△: The maximum value of the void area ratio is more than 13% and 20% or less

X: The maximum value of the area ratio of voids exceeds 20%

<Crack propagation inhibition test>

A chip component having a size of 3.2 mm x 1.6 mm (Ni/Sn plating), a solder resist having a pattern for mounting the chip component of the size, and an electrode (1.6 mm x 1.2 mm) connecting the chip component A glass epoxy substrate and a 150 µm-thick metal mask having the same pattern were prepared.

Each solder paste composition was printed on the glass epoxy substrate using the metal mask, and each of the chip components was mounted.

Thereafter, the respective glass epoxy substrates are heated using a reflow furnace (product name: TNP-538EM, manufactured by Tamura Seisakusho Co., Ltd.), and a solder joint for electrically bonding the glass epoxy substrate and the chip component to each of them. Formed, and the chip component was mounted. Reflow conditions at this time are preheating at 170°C to 190°C for 110 seconds, peak temperature at 245°C, 200°C or higher for 65 seconds, 220°C or higher for 45 seconds, and cooling from peak temperature to 200°C. The rate was set at 3°C to 8°C/sec, and the oxygen concentration was set at 1500±500 ppm.

Subsequently, using a cold and thermal shock test apparatus (product name: ES-76LMS, manufactured by Hitachi Appliance Co., Ltd.) set in the conditions of -40°C (30 minutes) to 125°C (30 minutes), the cold and thermal shock cycle was 1,000 , 1,500, 2,000, 2,500, and 3,000 cycles, each of the above glass epoxy substrates was exposed, and then taken out, and each test substrate was prepared.

Subsequently, the target portion of each test board was cut out, and this was sealed using an epoxy resin (product name: Epomount (main and curing agent), manufactured by Refinetech Co., Ltd.). In addition, using a wet grinder (product name: TegraPol-25, manufactured by Marumoto Struus Co., Ltd.), the central cross section of the chip component mounted on each test board is known, and cracks occurring in the formed solder joint are soldered. Whether or not completely crossing the junction and reaching fracture was observed using a scanning electron microscope (product name: TM-1000, manufactured by Hitachi High-Technologies Co., Ltd.), and evaluated according to the following criteria. The results are shown in Tables 5 to 8. In addition, the number of evaluation chips in each cooling and heat shock cycle was set to ten.

◎◎: No cracks that cross the solder joint completely up to 3,000 cycles

◎: Between 2,501 and 3,000 cycles, cracks completely cross the solder joint

○: Between 2,001 and 2,500 cycles, cracks completely transverse the solder joints.

△: Cracks that completely traverse the solder joints occur in less than 2,000 cycles.

As shown above, the solder paste compositions according to Examples 1 to 34 have stable continuous printability by using the organic acid ester (D-1) adjusted to the melting peak temperature of the solder alloy constituting the solder alloy powder to be used. It was found that it can be secured, and the stickiness of the flux residue after soldering can be suppressed while suppressing the occurrence of voids during reflow soldering. Further, since these have good wettability during reflow, generation of solder balls can also be suppressed. Furthermore, since these can suppress the reaction between the activator (B) and the solder alloy powder even when continuous squeezing is performed, it has been found that even the continuous rolling paste can suppress the generation of voids and solder balls.

Examples 25 to 28 using the solder alloy powder containing In can exhibit a good crack propagation suppression effect by the effect of the addition of In.

Further, in Examples 29 to 34 in which the alloy composition of the solder alloy powder was a specific element and content, the generation of solder balls and voids can be sufficiently suppressed, and even without In addition, the case of using the In-containing solder alloy powder. It was found that an equal or higher crack propagation suppression effect could be exhibited. In particular, such a solder paste composition can be suitably used for electronic circuit boards, such as vehicle-mounted electronic circuit boards, which are subject to severe heat dissipation and require high reliability.

In addition, for dioctyl sebacate among the organic acid esters (D-1) in Tables 1 to 4, since the melting peak temperature of the solder alloy powder used for this was less than 295° C., good results were not obtained, but the melting peak temperature was 295. In the case of using a solder alloy powder of at least °C, the temperature at which the loss rate (measured using the TG method) becomes 100% by mass is the melting peak temperature +50 °C or less, stable continuous printability, and during reflow soldering. It is possible to exhibit the effect of suppressing the occurrence of voids and suppressing stickiness of the flux residue.

Claims (20)

As a flux composition that forms a solder paste composition by mixing with a solder alloy powder,
(A) a base resin, (B) an activator, (C) a thixotropic agent, and (D) a solvent,
As the solvent (D) (D-1) contains an organic acid ester having neither a carboxyl group nor a hydroxyl group,
The temperature at which the loss ratio (measured using the TG method) of the organic acid ester (D-1) becomes 100% by mass is 180°C or higher, and the melting peak temperature of the solder alloy constituting the solder alloy powder +50°C or lower. ,
The flux composition, wherein the amount of the organic acid ester (D-1) is 10% by mass to 100% by mass based on the total amount of the solvent (D). The reduction rate (measured using the TG method) of the organic acid ester (D-1) according to claim 1, wherein the melting peak temperature of the solder alloy constituting the solder alloy powder is 130°C or more and less than 175°C. A flux composition characterized in that the temperature at 100% by mass is 180°C or more and less than 225°C. The reduction rate (measured using the TG method) of the organic acid ester (D-1) according to claim 1, in the case where the melting peak temperature of the solder alloy constituting the solder alloy powder is 175°C or more and less than 205°C. A flux composition characterized in that the temperature at 100% by mass is 180°C or more and less than 255°C. The reduction rate (measured using the TG method) of the organic acid ester (D-1) in the case where the melting peak temperature of the solder alloy constituting the solder alloy powder is 205°C or higher is 100% by mass. A flux composition, characterized in that the temperature at which it is equal to or higher than 180° C. and equal to or lower than the melting peak temperature of +50° C. The flux composition according to claim 2, wherein the organic acid ester (D-1) is at least one of dimethyl adipate and dibutyl maleate. The method of claim 3, wherein the organic acid ester (D-1) is at least one selected from dimethyl adipate, diisopropyl adipate, dibutyl maleate, dimethyl sebacate, diisobutyl adipate, and diethyl sebacate. Flux composition, characterized in that. The method of claim 4, wherein the organic acid ester (D-1) is dimethyl adipate, diisopropyl adipate, dibutyl maleate, dimethyl sebacate, diisobutyl adipate, diethyl sebacate, diisopropyl sebacate , Flux composition, characterized in that at least one selected from dibutyl sebacate and dioctyl sebacate. The method according to any one of claims 1 to 7, wherein the base resin (A) contains at least one of (A-1) rosin-based resin and (A-2) synthetic resin,
The synthetic resin (A-2) is an acrylic resin, a styrene-maleic acid resin, an epoxy resin, a urethane resin, a polyester resin, a phenoxy resin, a terpene resin, a polyalkylene carbonate, and a rosin resin having a carboxyl group and a dimer. A flux composition, characterized in that it is at least one selected from the group consisting of derivative compounds obtained by dehydrating condensation of an acid derivative flexible alcohol compound. A solder paste composition comprising the flux composition according to any one of claims 1 to 7, and a solder alloy powder. A solder paste composition comprising the flux composition according to claim 8 and a solder alloy powder. The method according to claim 9, wherein the solder alloy powder contains Ag of 2% by mass or more and 3.1% by mass or less, Cu of 0% by mass or more and 1% by mass or less, Sb of 1% by mass or more and 5% by mass or less, and Bi is 0.5% by mass or more. A solder paste composition characterized in that it contains 4.5% by mass or less, 0.01% by mass or more and 0.25% by mass or less of Ni, and the remainder is made of Sn. The method according to claim 10, wherein the solder alloy powder contains Ag of 2% by mass or more and 3.1% by mass or less, Cu of 0% by mass or more and 1% by mass or less, Sb of 1% by mass or more and 5% by mass or less, and Bi is 0.5% by mass or more. A solder paste composition comprising 4.5% by mass or less, 0.01% by mass or more and 0.25% by mass or less of Ni, and the remainder is made of Sn. The solder paste composition according to claim 11, wherein the solder alloy powder further contains 0.001% by mass or more and 0.25% by mass or less of Co. The solder paste composition according to claim 12, wherein the solder alloy powder further contains 0.001% by mass or more and 0.25% by mass or less of Co. An electronic circuit board comprising a solder joint formed using the solder paste composition according to claim 9. An electronic circuit board comprising a solder joint formed using the solder paste composition according to claim 10. An electronic circuit board comprising a solder joint formed using the solder paste composition according to claim 11. An electronic circuit board comprising a solder joint formed using the solder paste composition according to claim 12. An electronic circuit board comprising a solder joint formed using the solder paste composition according to claim 13. An electronic circuit board comprising a solder joint formed using the solder paste composition according to claim 14.