WO2018003760A1 - Flux composition, solder paste composition, and electronic circuit board - Google Patents

Abstract

The purpose of the invention is to provide a flux composition and a solder paste composition with which it is possible to suppress the stickiness of flux residue after soldering while suppressing the creation of voids during reflow soldering. To achieve this purpose, this flux composition is a flux composition that constitutes a solder paste composition by being mixed with a solder alloy powder, the flux composition comprising (A) a base resin, (B) an activator, (C) a thixotropic agent, and (D) a solvent, and being characterized in that: the solvent (D) includes (D-1) an organic acid ester that neither includes a carboxyl group nor a hydroxyl group; the temperature at which the weight reduction rate (measured by employing the TG method) of the organic acid ester (D-1) becomes 100 mass% is at least 180°C and at most 50°C above the melting peak temperature of the solder alloy constituting the solder alloy powder; and the amount of the organic acid ester (D-1) blended is from 10 mass% to 100 mass% with respect to the total amount of the solvent (D).

Description

Flux composition, solder paste composition, and electronic circuit board

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

Conventionally, in order to join 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 in which a flux and a solder alloy powder are mixed is printed on the substrate and is placed at a predetermined position. A method of mounting an electronic component and forming a solder joint by heating it in a reflow furnace or the like is used for general purposes (hereinafter, this method is referred to as “reflow soldering method”).
The reflow soldering method has a drawback in that voids are likely to occur in the formed solder joints, compared to a soldering method using solder formed in a predetermined shape. The main cause of this void is that when the solder alloy powder contained in the solder paste composition melts and agglomerates, the components contained in the flux composition, especially the volatile solvent, are not discharged from the agglomerated solder quickly. It is in.

Due to the miniaturization of pads due to the recent miniaturization of electronic components and the increase in heat generation due to the higher functionality of electronic components, previously allowed voids have an effect on the heat dissipation inhibition of components and the deterioration of bonding reliability. It is like that. For example, in a chip component having a size of 3.2 mm × 1.6 mm, when two voids having a diameter of 200 μm are generated under the electrode and when two voids having a diameter of 300 μm are generated, the solder is compared with the case where there is no void. It has been reported that the joint life of the joint is reduced by 0.85 and 0.63 times, respectively. As described above, the generation of voids in the solder joints may significantly impair the reliability of electronic devices and electronic components.

As a method for reducing such voids, conventionally, a method of adding an appropriate amount of an activator to the flux composition to be used and improving the fluidity at the time of melting the solder to discharge the gas generated inside the solder has been used. It was. However, such an activator starts to react at the time when the solder alloy powder and the flux composition are mixed, and the active power has already been consumed to some extent at the use stage of the solder paste composition. Accordingly, in this case, particularly in an electronic component having the above-described miniaturized pad, it is difficult to ensure sufficient wettability during soldering, and it is difficult to discharge gas from the agglomerated solder.

As a method for solving this problem, there is a method in which an activator corresponding to the amount of activity consumed due to the reaction with the solder alloy powder is pre-mixed in the flux composition to increase the activity and improve the fluidity at the time of melting the solder. . However, if the amount of the activator is increased for high activity, the insulation of the flux residue remaining on the substrate after soldering is lowered, which may cause a short circuit between the component terminals.

Further, as another method for reducing the generation of the above-mentioned voids, there is a method of blending a flux composition with a solvent that completely volatilizes at the stage of preheating during heating. Usually, the solvent is used to adjust the solder paste composition to an appropriate viscosity and enhance its printability. Therefore, if the printing of the solder paste composition on the substrate is completed, the solvent becomes an unnecessary component.
However, when such a volatile solvent is used, the solder paste composition is easily dried on the metal mask, so that the viscosity of the solder paste composition increases during continuous printing, which may cause clogging of the metal mask opening and defective printing. There is.

Furthermore, as another method for reducing the generation of voids in reflow soldering, a temperature (TG-15 temperature) at which a weight loss rate of 15% by mass is measured by the TG method when 70% by mass or more of the solvent contained in the flux is measured. A solder paste using a solvent that is higher by 5 ° C. or more than the melting peak temperature of solder has been proposed (see Patent Document 1). The amount of the solvent vaporized before the solder melts is less than 15% by mass at the maximum. Therefore, after the solder paste is completely melted and the solder shows wettability, the vaporization thereof becomes active. Therefore, the solvent is easily discharged from the molten solder, and thus generation of voids is suppressed.
However, such a solvent may be used together with a flux component (eg, resin, thixotropic agent, activator, etc.) other than the solvent when only a part of the solvent is vaporized during reflow heating or when it is not substantially vaporized at all. As a flux residue, it remains around the solder joint. Since the flux residue containing the solvent has a sticky property, dust and dust in the atmosphere are likely to adhere. Such a residue of flux adhered with dust or the like is deteriorated in insulation, so that its reliability may be significantly impaired.
The flux residue can also be removed by cleaning with a cleaning agent after soldering. However, in recent years, non-cleaning type solder paste compositions have been widely used from the viewpoint of cost, environment, etc., and the importance of solder paste compositions that can suppress the stickiness of flux residue while suppressing the generation of voids is increasing. Increasingly.

Japanese Patent No. 4458043

The present invention solves the above problems, and in particular, provides a flux composition and a solder paste composition capable of suppressing the stickiness of the flux residue after soldering while suppressing the generation of voids during reflow soldering. Objective.

(1) The flux composition of the present invention constitutes a solder paste composition by mixing with a solder alloy powder, and (A) a base resin, (B) an activator, (C) a thixotropic agent, (D) a solvent, and the solvent (D) includes (D-1) an organic acid ester having neither a carboxyl group nor a hydroxyl group, and the weight loss rate of the organic acid ester (D-1) ( The temperature at which 100% by mass (measured using the TG method) 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 blending amount of the organic acid ester (D-1) Is characterized in that it is 10% by mass to 100% by mass with respect to the total amount of the solvent (D).

(2) The weight loss rate of the organic acid ester (D-1) when the melting peak temperature of the solder alloy constituting the solder alloy powder is 130 ° C. or higher and lower than 175 ° C. The temperature at which 100% by mass (measured using the TG method) is 180 ° C. or higher and lower than 225 ° C. is a feature thereof.

(3) The weight loss rate of the organic acid ester (D-1) when the melting peak temperature of the solder alloy constituting the solder alloy powder is 175 ° C. or higher and lower than 200 ° C. The temperature at which 100% by mass (measured using the TG method) is 180 ° C. or more and less than 250 ° C. is a feature thereof.

(4) The weight loss rate of the organic acid ester (D-1) when the melting peak temperature of the solder alloy constituting the solder alloy powder is 200 ° C. or higher (TG method) The temperature at which the measurement becomes 100% by mass is 180 ° C. or higher and the melting peak temperature + 50 ° C. or lower.

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

(6) In the constitution described in (3) above, the organic acid ester (D-1) is selected from dimethyl adipate, diisopropyl adipate, dibutyl maleate, dimethyl sebacate, diisobutyl adipate and diethyl sebacate It is characterized by being at least one kind.

(7) In the constitution described in (4) above, the organic acid ester (D-1) is dimethyl adipate, diisopropyl adipate, dibutyl maleate, dimethyl sebacate, diisobutyl adipate, diethyl sebacate, sebacin It is characterized by being at least one selected from diisopropyl acid, dibutyl sebacate and dioctyl sebacate.

(8) In the constitution described in any one of (1) to (7) above, the base resin (A) comprises at least one of (A-1) rosin resin and (A-2) synthetic resin. The synthetic resin (A-2) is acrylic resin, styrene-maleic acid resin, epoxy resin, urethane resin, polyester resin, phenoxy resin, terpene resin, polyalkylene carbonate, rosin resin having carboxyl group and dimer acid derivative It is characterized by being at least one selected from the group consisting of derivative compounds obtained by dehydration condensation with a flexible alcohol compound.

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

(10) In the configuration described in (9) above, the solder alloy powder has an Ag content of 2% by mass to 3.1% by mass, Cu of more than 0% by mass and 1% by mass or less, and Sb of 1% by mass. % To 5% by mass, Bi from 0.5% to 4.5% by mass, Ni from 0.01% to 0.25% by mass, with the balance being Sn. To do.

(11) In the configuration described in (10) above, the solder alloy powder further includes Co in an amount of 0.001% by mass to 0.25% by mass.

(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 that can suppress the stickiness of the flux residue after soldering while suppressing the generation of voids particularly during reflow soldering.

Embodiments of the flux composition, solder paste composition and electronic circuit board of the present invention are described in detail below. Of course, the present invention is not limited to these embodiments.

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

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

Examples of the rosin resin (A-1) include rosins such as tall oil rosin, gum rosin, and wood rosin; polymerization, hydrogenation, heterogeneity, acrylation, maleation, esterification, or phenol addition reaction of rosin. And a modified rosin resin obtained by subjecting these rosin or rosin derivative and an unsaturated carboxylic acid (acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, etc.) to a Diels-Alder reaction. Among these, a modified rosin resin is particularly preferably used, and a hydrogenated acrylic acid-modified rosin resin hydrogenated by reacting acrylic acid is particularly preferably used. In addition, you may use these individually by 1 type or in mixture of multiple types.

The acid value of the rosin 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, rosin resin having a carboxyl group, and dimer acid. Derivative compounds formed by dehydration condensation with a derivative flexible alcohol compound are exemplified. In addition, you may use these individually by 1 type or in mixture of multiple types.

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

As the epoxy resin, any thermosetting resin having a reactive epoxy group at its end 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, glycidyl amine type, alicyclic epoxy resin and the like. In addition, you may use these individually by 1 type or in mixture of multiple types.

Any urethane resin can be used as long as it is obtained by reacting a compound having a plurality of isocyanate groups in one molecule with a polyol compound having two or more hydroxyl groups in one molecule. Of these, polyurethane resins containing an aliphatic component and an aromatic component are particularly preferred. The urethane resin may be used alone or in combination of two or more.

Examples of the polyester resin include polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polybutylene naphthalate. In addition, you may use these individually by 1 type or in mixture of multiple types.

Examples of the phenoxy resin include bisphenol A type phenoxy resin and bisphenol F type phenoxy resin. In addition, you may use these 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, polycyclopentene carbonate, polycyclohexene carbonate, polycycloheptene carbonate, polycyclooctene carbonate, and polylimonene. Examples of the carbonate include polypropylene carbonate and polybutylene carbonate. In addition, you may use these individually by 1 type or in mixture of multiple types.

Regarding a derivative compound obtained by dehydrating and condensing the rosin resin having a carboxyl group and a dimer acid derivative flexible alcohol compound (hereinafter referred to as “rosin derivative compound”), as the rosin resin having a carboxyl group, for example, Rosin such as tall oil rosin, gum rosin, wood rosin; hydrogenated rosin, polymerized rosin, heterogeneous rosin, acrylic acid modified rosin, rosin derivatives such as maleic acid modified rosin, etc. Can be used. These may be used alone or in combination of two or more.
Next, examples of the dimer acid derivative flexible alcohol compound include compounds derived from dimer acid such as dimer diol, polyester polyol, and polyester dimer diol, and those having an alcohol group at the terminal thereof. For example, PRIPOL 2033, PRIPLAST 3197, PRIPLAST 1838 (manufactured by Croda Japan Co., Ltd.) and the like can be used.
The rosin derivative compound is obtained by dehydrating and condensing the rosin resin having a carboxyl group and the dimer acid derivative flexible alcohol compound. As the dehydration condensation method, a generally used method can be used. In addition, a preferred weight ratio when dehydrating and condensing the rosin 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 the weight average molecular weight is preferably 1,000 Mw to 30,000 Mw.

Further, 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 rosin resin (A-1) is used alone, the blending amount is preferably 10% by mass or more and 50% by mass or less, and 15% by mass or more and 45% by mass or less with respect to the total amount of the flux composition. More preferably. By setting the blending amount of the rosin resin (A-1) within this range, it is possible to obtain good solderability and an appropriate flux residual amount.
When the synthetic resin (A-2) is used alone, the blending amount is preferably 10% by mass or more and 60% by mass or less, and more preferably 15% by mass or more and 50% by mass or less with respect to the total amount of the flux composition. It is more preferable.

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

(B) Activator Examples of the activator (B) include carboxylic acids and halogen-containing compounds. You may use these individually by 1 type or in mixture 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, pentadecylic acid, palmitic acid, margaric acid, stearic acid, 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, diglycolic acid and the like.
Examples of the other organic acids include dimer acid, levulinic acid, lactic acid, acrylic acid, benzoic acid, salicylic acid, anisic acid, citric acid, and picolinic acid.
In addition, you may use these individually by 1 type or in mixture of multiple types.

Examples of the halogen-containing compound include a non-dissociative halogen compound (non-dissociative activator) and a dissociative halogen compound (dissociative activator).
Examples of the non-dissociative activator include non-salt organic compounds in which halogen atoms are covalently bonded. For example, chlorine, bromine, iodine, fluorine such as chlorinated compounds, brominated compounds, iodinated compounds, and fluorides. The compound may be a compound by covalent bonding of each single element, or a compound in which two or more different halogen atoms are bonded 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; 1,3-dichloro- Examples include chlorinated alcohols such as 2-propanol and 1,4-dichloro-2-butanol; fluorinated alcohols such as 3-fluorocatechol; and other similar compounds.

Examples of the dissociative activator include base hydrochlorides and hydrobromides such as amines and imidazoles. Examples of hydrochloric acid and hydrobromic acid salts include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, n-propylamine, di-n-propylamine, tri-n-propylamine, isopropylamine , Diisopropylamine, butylamine, dibutylamine, tributylamine, cyclohexylamine, monoethanolamine, diethanolamine, triethanolamine and other amines with relatively small carbon numbers; imidazole, 2-methylimidazole, 2-ethylimidazole, 2-methyl- Hydrochloric acid salts such as 4-methylimidazole, 2-methyl-4-ethylimidazole, 2-ethyl-4-ethylimidazole, 2-propylimidazole, 2-propyl-4-propylimidazole Fine hydrobromic acid salts, and the like. You may use these individually by 1 type or in mixture 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 preferably 5% by mass or more and 15% by mass or less based on the total amount of the flux composition. Is more preferable. By making the compounding quantity of carboxylic acid into this range, solder ball generation | occurrence | production suppression and the insulation of a favorable flux composition can be exhibited.

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

Next, the blending amount of the dissociative activator used in the activator (B) is preferably 0.1% by mass or more and 3% by mass or less based on the total amount of the flux composition, and is 0.3% by mass. More preferably, it is 1.5 mass% or less.

Further, when the amine and imidazole are each used alone as the dissociative activator, the blending amount is preferably 0.1% by mass or more and 5% by mass or less, and 0.5% by mass or more and 3% by mass or less. More preferably.

(C) Thixotropic agent Examples of the thixotropic agent (C) include hydrogenated castor oil, saturated fatty acid amides, saturated fatty acid bisamides, oxy fatty acids, dibenzylidene sorbitols, and the like. You may use these individually by 1 type or in mixture of multiple types.
Further, 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, hexyl diglycol, (2-ethylhexyl) diglycol, phenyl glycol, butyl carbitol. , Octanediol, α-terpineol, β-terpineol, tetraethylene glycol dimethyl ether, trimellitic acid tris (2-ethylhexyl), bisisopropyl sebacate and the like can be used. You may use these individually by 1 type or in mixture of multiple types.

In the flux composition of this embodiment, the solvent (D) preferably contains (D-1) an organic acid ester having neither a carboxyl group nor a hydroxyl group.
As a solvent used for the flux composition, a component containing either a carboxyl group or a hydroxyl group is generally used. Among the components of the flux composition, the activator is ionized when dissolved in such a solvent, thereby generating negatively charged organic acid ions (RCOO-) and halide ions. The carboxyl group and hydroxyl group are easily oriented around this ion, and as a result, they are solvated and a reaction between the solder alloy powder and the solvent occurs.
However, since the organic acid ester (D-1) does not have any of the above carboxyl group and hydroxyl group, in the flux composition of this embodiment, a functional group that is easily oriented to ions ionized from the activator (B). Therefore, they are difficult to solvate. 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 an unheated storage state.
Thus, 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 activator (B) The activity remains without adjusting the activity and blending amount, ensuring good wettability during soldering and suppressing the generation of voids.
Even if the organic acid ester (D-1) remains in the flux residue formed on the substrate, the organic acid ester (D-1) has both a carboxyl group and a hydroxyl group as described above. Therefore, the hygroscopicity of the flux residue can be suppressed, and it is considered that the insulation of the flux residue is hardly affected.

The weight loss rate of the organic acid ester (D-1) (measured using the TG method. Specifically, the TG curve was measured using a thermogravimetric-suggested thermal analyzer, and the weight loss rate was calculated thereby. The same applies hereinafter) is preferably at least 180 ° C. and the melting peak temperature of the solder alloy constituting the solder alloy + 50 ° C. or less. Since such an organic acid ester (D-1) can suppress stickiness of the flux residue formed on the substrate, it is possible to impart good insulation to the flux residue.
That is, the general reflow heating conditions of the solder paste composition are often set so that the peak temperature of the main heating is higher by 10 to 50 ° C. than the melting peak temperature of the solder.
As a result of diligent research, the present inventors have found that the organic material has a weight loss rate of 100% by mass at a temperature higher than 180 ° C. and higher than the melting peak temperature of the solder alloy used as the solvent (D) in the flux composition. By blending the acid ester (D-1), drying on the metal mask during printing becomes difficult to occur, stable continuous printability can be secured, and generation of voids under the above reflow heating conditions is suppressed. Further, it was found that stickiness of the formed flux residue can be suppressed.

For example, when the peak temperature of the solder alloy powder of the solder alloy powder used for mixing is 130 ° C. or higher and lower than 175 ° C., the temperature at which the organic acid ester (D-1) becomes 100% by mass of the weight loss rate is 180 ° C. or higher And what is less than 225 degreeC is used preferably. Examples of such organic acid ester (D-1) include dimethyl adipate and dibutyl maleate. You may use these individually by 1 type or in mixture of multiple types.

For example, when 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 temperature at which the organic acid ester (D-1) becomes 100% by mass of the weight loss rate is 180 ° C. Those having a temperature of less than 250 ° C. are preferably used. Examples of such organic acid ester (D-1) include dimethyl adipate, diisopropyl adipate, dibutyl maleate, dimethyl sebacate, diisobutyl adipate, diethyl sebacate and the like. You may use these individually by 1 type or in mixture 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 temperature at which the organic acid ester (D-1) becomes 100% by mass of the weight loss rate is 180 ° C. or higher. In addition, a solder alloy having a melting peak temperature of + 50 ° C. or lower is preferably used. Examples of such organic acid ester (D-1) include dimethyl adipate, diisopropyl adipate, dibutyl maleate, dimethyl sebacate, diisobutyl adipate, diethyl sebacate, diisopropyl sebacate, dibutyl sebacate, thiooctyl sebacate. Etc. You may use these individually by 1 type or in mixture of multiple types.

The blending amount of the solvent (D) is preferably 20% by mass to 65% by mass with respect to the total amount of the flux composition. The blending amount is more preferably 20% by mass or more and 60% by mass or less, and the particularly preferable blending amount is 25% by mass or more and 50% by mass or less.
The blending amount of the organic acid ester (D-1) is preferably 10% by mass to 100% by mass with respect to the total amount of the solvent (D).

Furthermore, an additive can be mix | blended with the flux composition of this embodiment as needed. Examples of the additive include an antioxidant, an antifoaming agent, a surfactant, and a matting agent. You may use these individually by 1 type or in mixture of multiple types.
In addition, it is preferable that the compounding quantity of the said additive is 0.5 mass% or more and 20 mass% or less with respect to the flux whole quantity, and it is more preferable that it is 1 mass% or more and 15 mass% or less.

(2) Solder paste composition The solder paste composition of this embodiment is obtained by mixing the flux composition and the solder alloy powder.
As the solder alloy powder, any of leaded / lead-free solder alloy powder can be used. That is, the solder paste composition of this embodiment uses the organic acid ester (D-1) suitable for the melting peak temperature regardless of the component of the solder alloy powder to be used. The stickiness of the flux residue after soldering can be suppressed while suppressing the generation.

Examples of alloys that can be used for 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, Sn and Pb. Examples include alloys containing Cu, alloys containing Sn, Ag and Cu, alloys containing Sn and Bi, and the like. Besides these, for example, Sn, Pb, Ag, Bi, In, Cu, Zn, Ga, Sb, Au, Pd, Ge, Ni, Cr, Al, P, etc. should be used as appropriate. Can do. Note that elements other than those listed above can be used in combination.
Of these, solder alloy powders containing Sb, Ag and Cu, for example, Sn—Ag alloy solder, Sn—Ag—Cu solder alloy and Sn—Ag—Cu—Bi—Sb solder alloy powder are particularly preferable. Used.

Of these, the use of a solder alloy powder having the following alloy composition can improve the effect of suppressing the crack propagation of the solder joint formed.
That is, the solder alloy powder has an Ag of 1% by mass to 3.1% by mass, Cu of more than 0% by mass to 1% by mass, Sb of 1% by mass to 5% by mass, and Bi of 0.0%. It is preferable that 5 mass% or more and 4.5 mass% or less, 0.01 mass% or more and 0.25 mass% or less of Ni are included, and the remainder consists of Sn.

The more preferable content of Ag is 2% by mass or more and 3.1% by mass or less, the more preferable content of Cu is 0.5% by mass or more and 1% by mass or less, and the more preferable content of Sb is 2%. More preferably, the content of Bi is 3.1% to 4.5% by mass, and the more preferable content of Ni is 0.01% to 0.15% by mass. It is.

The solder alloy powder preferably further contains Co in an amount of 0.001% by mass to 0.25% by mass. 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 using the solder paste composition according to the present embodiment can be used in a harsh environment where the difference in temperature is intense and vibration is applied. Also, the crack progress of the solder joint can be suppressed. Furthermore, even when solder bonding is performed using an electronic component that has not been subjected to Ni / Pd / Au plating or Ni / Au plating, crack propagation near the interface between the solder bonding portion and the lower surface electrode of the electronic component can be suppressed. it can.

The amount of the solder alloy powder is preferably 65% by mass to 95% by mass with respect to the total amount of the solder paste composition. More preferably, the blending amount is 85% by weight to 93% by weight, and a particularly preferable blending amount is 87% by weight to 92% by weight.
When the blending amount of the solder alloy powder is less than 65% by mass, a sufficient solder joint tends to be hardly formed when the obtained solder paste composition is used. On the other hand, when the content of the solder alloy powder exceeds 95% by mass, the flux composition as a binder is insufficient, and therefore, it tends to be difficult to mix the flux composition and the solder alloy powder.

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 the flux composition containing the organic acid ester (D-1) suitable for the melting peak temperature of the solder alloy powder of the solder alloy powder, so that the void at the time of reflow soldering is used. The stickiness of the flux residue after soldering can be suppressed while suppressing the generation.

(3) Electronic circuit board The electronic circuit board according to the present embodiment includes a solder joint portion and a flux residue formed by using the solder paste composition (in this specification, the solder joint portion and the flux residue are combined together. It is preferable to have a solder joint ”. The electronic circuit board is, for example, an electrode and a solder resist film formed at a predetermined position on the substrate, printed with the solder paste composition of the present embodiment using a mask having a predetermined pattern, and adapted to the pattern. It is manufactured by mounting parts at predetermined positions and reflowing them.
In the electronic circuit board thus manufactured, a solder joint is formed on the electrode, and the solder joint electrically joins the electrode and the electronic component. And on the said board | substrate, the flux residue has adhered so that it may adhere | attach to a solder joint part at least.

In the electronic circuit board of the present embodiment, since the solder joint and the flux residue are formed using the solder paste composition, voids are hardly generated in the solder joint and the flux residue is difficult to stick. be able to. Moreover, the crack progress inhibitory effect of a solder joint part can also be improved by making the alloy composition of solder alloy powder into a specific element and content.

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

<Creation of synthetic resin>
200 g of diethylene glycol monohexyl ether was charged into a 500 ml four-necked flask equipped with a stirrer, a reflux tube, and a nitrogen introduction tube, and this was heated to 110 ° C.
Also, dimethyl 2,2′-azobis (2-methylpropionate) (product name) as an azo radical initiator in 300 g of 10% by weight of methacrylic acid, 51% by weight of 2-ethylhexyl methacrylate and 39% by weight of lauryl acrylate : V-601, manufactured by Wako Pure Chemical Industries, Ltd.) was added in an amount of 0.2% to 5% by mass to dissolve the solution to prepare a solution.
Then, the solution was added dropwise to the above four-necked flask over 1.5 hours and stirred at 110 ° C. for 1 hour, and then the reaction was terminated to obtain a synthetic resin (A-2) used in the examples. The synthetic resin (A-2) had a weight average molecular weight of 7,800 Mw, an acid value of 40 mgKOH / g, and a glass transition temperature of −47 ° C.

<Preparation of solder paste composition>
Each component described in Table 1 to Table 4 was kneaded to obtain each flux composition according to Examples 1 to 34 and Comparative Examples 1 to 13. Next, 11% by mass of each flux composition and 89% by mass of the solder alloy powder listed below were kneaded to obtain solder paste compositions according to Examples 1 to 34 and Comparative Examples 1 to 13. Unless otherwise specified, the numerical values shown in Tables 1 to 4 mean mass%.
As for the synthetic resin (A-2), the solvent-like resin produced by the above-described procedure is used after the solvent is volatilized using an evaporator. Therefore, the numerical value of the synthetic resin (A-2) described in Tables 1 to 4 represents only the solid content in which the solvent is volatilized.
In addition, the solder alloy powder used in each Example and the 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, thermogravimetric-suggestion thermal analyzer (product name: STA7200RV, manufactured by Hitachi High-Tech Science Co., Ltd.) was used to determine the temperature at which the weight loss rate on the TG curve was 100% by mass. Measured and listed with the component names in Tables 1-4. The measurement conditions were a temperature rising rate of 10 ° C./min, a nitrogen gas flow rate of 200 ml / min, and a sample amount of 10 mg.

* 1 Hydrogenated acid-modified rosin manufactured by Arakawa Chemical Co., Ltd. * 2 Fatty acid bisamide manufactured by Nippon Kasei Co., Ltd. * 3 Hindered phenol antioxidant manufactured by BASF Japan

<Print recovery test>
A glass epoxy substrate provided with a solder resist having a pattern capable of mounting a 100-pin 0.5 mm pitch BGA and an electrode (diameter: 0.25 mm), and a metal mask having a thickness of 120 μm having the same pattern as the above pattern were prepared.
Next, each solder paste composition was printed on the substrate using the metal mask. In addition, this printing was performed by the method of printing continuously using 6 said board | substrates about 1 type of solder paste compositions.
After the continuous printing, each solder paste composition on the metal mask was left for 1 hour in an environment of 25 ° C.-50%.
Thereafter, each solder paste composition on the metal mask was printed on the substrate. In addition, this printing was performed by the method of printing continuously using 10 said board | substrates about 1 type of solder paste compositions.
About the said board | substrate which performed the said continuous printing, the image volume inspection machine (product name: aspire2, Co., Ltd. product made from Koyon Technology) shows the transfer volume ratio in the electrode part of diameter 0.25mm from the 5th to 10th printing order. And measured according to the following criteria. The results are shown in Tables 5 to 8.
A: Number of transfer volume ratio 35% or less is zero 0: Number of transfer volume ratio 35% or less is 1 or more and 10 or less Δ: Number of transfer volume ratio 35% or less is 11 or more and 50 or less ×: Transfer 51 or more with a volume ratio of 35% or less

<Flux residue adhesion test>
A solder resist having a 6 mm diameter pattern, a glass epoxy substrate having a copper land, and a 150 μm thick metal mask having the same pattern as the above pattern were prepared. Next, each solder paste composition is printed on the glass epoxy substrate using the metal mask, and these are heated using a reflow furnace (product name: TNP-538EM, manufactured by Tamura Seisakusho Co., Ltd.), Produced. 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 any case, the oxygen concentration in the reflow furnace is 1500 ± 500 ppm.
Examples 1 to 20 and Comparative Examples 1 to 8: Preheating is performed at 170 to 180 ° C. for 90 seconds, peak temperature 230 ° C., 220 ° C. or more is 30 seconds or less, and the cooling rate from peak temperature to 200 ° C. is 3 ° C. 8 ° C./sec. Examples 21 and 22 and Comparative Example 9: Preheating is performed from 180 ° C. to 200 ° C. for 90 seconds, peak temperature of 265 ° C., 250 ° C. or more is 30 seconds or less, and the cooling rate from the peak temperature to 235 ° C. is 3 C to 8 ° C./second Examples 23 and 24 and Comparative Examples 10 and 11: Preheating from 100 ° C. to 110 ° C. for 90 seconds, peak temperature 160 ° C., 150 ° C. or higher to 30 seconds or shorter, peak temperature to 120 ° C. Cooling rate is 3 ° C. to 8 ° C./second. Examples 25 to 28 and Comparative Example 12: Preheating is performed at 150 to 170 ° C. for 90 seconds, peak temperatures of 220 ° C. and 210 ° C. or more. 0 seconds or less, cooling rate from peak temperature to 190 ° C. is 3 ° C. to 8 ° C./second. Examples 29 to 34: Preheating is performed from 170 ° C. to 180 ° C. for 90 seconds, peak temperature is 230 ° C., 220 ° C. or more is 30 seconds. Hereinafter, the cooling rate from the peak temperature to 200 ° C. is 3 ° C. to 8 ° C./second. Comparative Example 13: Preheating is performed at 170 ° C. to 180 ° C. for 90 seconds, peak temperature 240 ° C., 230 ° C. or higher is 30 seconds or shorter, peak temperature The cooling rate from 1 to 200 ° C. is from 3 ° C. to 8 ° C./sec. After leaving each test board at room temperature for 2 hours, the flux residue formed on each test board soldered to a 6 mm diameter pattern has a diameter of 300 μm. The solder balls were sprinkled and hit against a desk so that the side of each test board was parallel to the ground to give an impact. Thereafter, the number of solder balls attached to the flux residue on each test substrate was counted and evaluated according to the following criteria. The results are shown in Tables 5 to 8.
◎: Solder ball adherence number 0: Solder ball adherence number 1 or more and 10 or less △: Solder ball adherence number 11 or more and 30 or less ×: Solder ball adherence number 31 or more

<Preparation of continuous rolling paste>
For each solder paste composition, using a polyurethane rubber squeegee (hardness 90), a squeegee angle of 60 °, a printing tact time of 30 seconds, a stroke of 300 mm, and an environment of 25 ° C.-50% R.P. H. The squeezing was continuously performed for 4 hours under the above conditions.
Note that the amount of sample input was 500 g. Each solder paste composition after continuous squeezing thus obtained 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 × 1.2 mm were prepared. A solder resist and an electrode (1.25 mm × 1.0 mm) corresponding to the chip component are formed on the glass epoxy substrate, and a 150 μm thick metal mask having the same pattern is used on the glass epoxy substrate. Each solder paste composition and each continuous rolling paste were printed, and chip parts were mounted. Next, each glass epoxy substrate was heated in a reflow furnace (product name: TNP-538EM, manufactured by Tamura Corporation) to prepare each test substrate. The reflow conditions differ depending on the composition of the solder alloy powder used in each printed solder paste composition and each continuous rolling paste. The conditions are as follows. In any case, the oxygen concentration in the reflow furnace is 1500 ± 500 ppm.
Examples 1 to 20 and Comparative Examples 1 to 8: Preheating from 170 ° C. to 190 ° C. for 110 seconds, peak temperature 260 ° C., 200 ° C. or higher for 70 seconds and 220 ° C. or higher for 60 seconds, peak temperature to 200 ° C. Cooling rate from 3 ° C. to 8 ° C./sec. Examples 21 and 22 and Comparative Example 9: Preheating at 180 ° C. to 210 ° C. for 110 seconds, peak temperature 290 ° C., 230 ° C. or higher for 70 seconds and 250 ° C. or higher for 60 seconds The cooling rate from the peak temperature to 235 ° C. is 3 ° C. to 8 ° C./second. Examples 23 and 24 and Comparative Example 10 and Comparative Example 11: Preheating at 100 ° C. to 120 ° C. for 110 seconds, peak temperature 210 ° C., 130 The cooling rate from the peak temperature to 150 ° C. is from 3 ° C. to 8 ° C./sec. Examples 25 to 28 and Comparative Example 2: Preheating at 150 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, cooling rate from peak temperature to 190 ° C. from 3 ° C. to 8 ° C./second Examples 29 to 34: Preheating at 170 to 190 ° C. for 110 seconds, peak temperature 260 ° C., 200 ° C. or higher for 70 seconds and 220 ° C. or higher for 60 seconds, cooling rate from peak temperature to 200 ° C. from 3 ° C. to 8 ° C. C / sec. Comparative Example 13: Preheating at 170 ° C. to 190 ° C. for 110 seconds, peak temperature 260 ° C., 200 ° C. or higher for 70 seconds and 220 ° C. or higher for 60 seconds, cooling rate from peak temperature to 200 ° C. is 3 ° C. 8 ° C./second Each of the test substrates was observed using an X-ray transmission device (product name: SMX-160E, manufactured by Shimadzu Corporation), and the periphery of the chip component and Counting the number of solder balls and the diameter generated on the lower surface was evaluated as follows. The results are shown in Tables 5 to 8.
A: No. of balls generated per 10 pieces of 2.0 mm × 1.2 mm chip resistors B: No. of balls generated per 10 pieces of 2.0 mm × 1.2 mm chip resistors Δ: The number of balls generated per 10 2.0 mm × 1.2 mm 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 is manufactured under the same conditions as the solder ball test, and the surface state is observed with an X-ray transmission device (product name: SMX-160E, manufactured by Shimadzu Corporation), and a solder joint is formed. The ratio of the total area of voids in the region (void area ratio) was measured. In addition, the generation | occurrence | production situation of the void calculated | required the maximum value of the area ratio of the void in 20 lands in each test board | substrate, and evaluated it as follows. The results are shown in Tables 5 to 8.
◎: Maximum value of void area ratio is 10% or less ○: Maximum value of void area ratio is more than 10% and 13% or less △: Maximum value of void area ratio is more than 13% and 20% or less ×: Void area The maximum rate is over 20%

<Crack growth inhibition test>
A chip component (Ni / Sn plating) having a size of 3.2 mm × 1.6 mm, a solder resist having a pattern capable of mounting the chip component of the size, and an electrode (1.6 mm × 1.2 mm) connecting the chip component 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 the chip component was mounted on each of the solder paste compositions.
Thereafter, using a reflow furnace (product name: TNP-538EM, manufactured by Tamura Seisakusho Co., Ltd.), each glass epoxy substrate is heated to solder the glass epoxy substrate and the chip component to each other electrically. A part was formed, and the chip component was mounted. The reflow conditions at this time are: preheating from 170 ° C. to 190 ° C. for 110 seconds, peak temperature of 245 ° C., time of 200 ° C. or higher for 65 seconds, time of 220 ° C. or higher for 45 seconds, peak temperature to 200 ° C. The cooling rate was 3 ° C. to 8 ° C./second, and the oxygen concentration was set to 1500 ± 500 ppm.
Next, using a thermal shock test apparatus (product name: ES-76LMS, manufactured by Hitachi Appliances Co., Ltd.) set to -40 ° C (30 minutes) to 125 ° C (30 minutes), Each glass epoxy substrate was exposed to each other in an environment where 000, 1,500, 2,000, 2,500, and 3,000 cycles were repeated, and then taken out to prepare each test substrate.
Subsequently, the target part of each test board | substrate was cut out, and this was sealed using the epoxy resin (Product name: Epomount (main agent and hardening | curing agent), the refine tech Co., Ltd. product). Further, using a wet polishing machine (product name: TegraPol-25, manufactured by Marumoto Struers Co., Ltd.), the solder joints are formed so that the center cross section of the chip component mounted on each test substrate can be seen. Using a scanning electron microscope (Product name: TM-1000, manufactured by Hitachi High-Technologies Corporation) And evaluated. The results are shown in Tables 5 to 8. The number of evaluation chips in each thermal shock cycle was 10.
◎: No crack that completely crosses the solder joint until 3,000 cycles ◎: Crack that completely crosses the solder joint occurs between 2,501 and 3,000 cycles O: From 2,001 A crack that completely traverses the solder joint between 2,500 cycles occurred △: A crack that completely traverses the solder joint occurred after 2,000 cycles or less

As described above, the solder paste compositions according to Examples 1 to 34 are stabilized by using the organic acid ester (D-1) that matches the melting peak temperature of the solder alloy constituting the solder alloy powder to be used. It can be seen that continuous printability can be ensured, and stickiness of the flux residue after soldering can be suppressed while suppressing the generation of voids during reflow soldering. Moreover, since these have good wettability during reflow, the generation of solder balls can also be suppressed. Furthermore, since they can suppress the reaction between the activator (B) and the solder alloy powder even if continuous squeezing is performed, it can be seen 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 growth suppressing effect due to the effect of adding In.
In Examples 29 to 34 in which the alloy composition of the solder alloy powder is a specific element and content, the generation of solder balls and voids can be sufficiently suppressed, and the In-containing solder alloy powder can be obtained without adding In. It can be seen that the crack growth suppressing effect equivalent to or higher than that in the case of using can be exhibited. Such a solder paste composition can be suitably used especially for an electronic circuit board that has a severe temperature difference and requires high reliability, such as an in-vehicle electronic circuit board.
Of the organic acid esters (D-1) in Tables 1 to 4, dioctyl sebacate did not give good results because the melting peak temperature of the solder alloy powder used was less than 295 ° C. When a solder alloy powder having a melting peak temperature of 295 ° C. or higher is used, the temperature at which the weight loss rate (measured using the TG method) is 100% by mass is the melting peak temperature + 50 ° C. or lower, and stable continuous printing , The effect of suppressing the generation of voids during reflow soldering and the effect of suppressing the stickiness of the flux residue.

Claims (12)

1. A flux composition that is mixed with solder alloy powder to constitute a solder paste composition,
   (A) a base resin, (B) an activator, (C) a thixotropic agent, and (D) a solvent,
   The solvent (D) includes (D-1) an organic acid ester having neither a carboxyl group nor a hydroxyl group,
   The temperature at which the weight loss rate (measured using the TG method) of the organic acid ester (D-1) is 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 characterized in that the organic acid ester (D-1) is blended in an amount of 10% by mass to 100% by mass with respect to the total amount of the solvent (D).
2. Temperature at which the weight loss rate (measured using the TG method) of the organic acid ester (D-1) becomes 100% by mass when the melting peak temperature of the solder alloy constituting the solder alloy powder is 130 ° C. or higher and lower than 175 ° C. It is 180 degreeC or more and less than 225 degreeC, The flux composition of Claim 1 characterized by the above-mentioned.
3. Temperature at which the weight loss rate (measured using the TG method) of the organic acid ester (D-1) becomes 100% by mass when the melting peak temperature of the solder alloy constituting the solder alloy powder is 175 ° C. or higher and lower than 205 ° C. It is 180 degreeC or more and less than 255 degreeC, The flux composition of Claim 1 characterized by the above-mentioned.
4. When the melting peak temperature of the solder alloy constituting the solder alloy powder is 205 ° C. or higher, the temperature at which the weight loss rate of the organic acid ester (D-1) (measured using the TG method) is 100% by mass is 180 ° C. The flux composition according to claim 1, wherein the flux peak temperature is + 50 ° C. or less.
5. 3. The flux composition according to claim 2, wherein the organic acid ester (D-1) is at least one of dimethyl adipate and dibutyl maleate.
6. 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. The flux composition as described.
7. The organic acid ester (D-1) is at least one selected from dimethyl adipate, diisopropyl adipate, dibutyl maleate, dimethyl sebacate, diisobutyl adipate, diethyl sebacate, diisopropyl sebacate, dibutyl sebacate and dioctyl sebacate. The flux composition according to claim 4, which is a seed.
8. The base resin (A) includes at least one of (A-1) rosin resin and (A-2) synthetic resin,
   The synthetic resin (A-2) is an acrylic resin, styrene-maleic acid resin, epoxy resin, urethane resin, polyester resin, phenoxy resin, terpene resin, polyalkylene carbonate, rosin resin having a carboxyl group, and dimer acid derivative flexibility. The flux composition according to any one of claims 1 to 7, wherein the flux composition is at least one selected from the group consisting of derivative compounds obtained by dehydration condensation with an alcohol compound.
9. A solder paste composition comprising the flux composition according to any one of claims 1 to 8 and a solder alloy powder.
10. The solder alloy powder contains 2% by mass to 3.1% by mass of Ag, more than 0% by mass and 1% by mass or less of Cu, 1% by mass to 5% by mass of Sb, and 0.5% by mass of Bi. The solder paste composition according to claim 9, wherein the solder paste composition contains not less than 4.5% by mass and not more than 0.01% by mass and not more than 0.01% by mass and not more than 0.25% by mass with the balance being Sn.
11. The solder paste composition according to claim 10, wherein the solder alloy powder further contains Co in an amount of 0.001 mass% to 0.25 mass%.
12. An electronic circuit board comprising a solder joint formed using the solder paste composition according to any one of claims 9 to 11.