JP2022011522A - Flux composition, solder composition and electronic board - Google Patents

Abstract

To provide a flux composition that has excellent temporal stability and can prevent the occurrence of voids and migration.SOLUTION: A flux composition has (A) a resin and (B) an activator. The (B) component has (B1) an iodine compound having, in one molecule, an iodine atom, but having no carboxyl group. Preferably, the (B1) component should include an aromatic ring in order for prevention of voids, and two or more iodine atoms should be included in one molecule. The content of the (B1) component in the flux composition is 0.01-5 mass%.SELECTED DRAWING: None

Description

The present invention relates to flux compositions, solder compositions and electronic substrates.

The solder composition (solder paste) is a mixture in which a flux composition (rosin-based resin, activator, solvent, etc.) is kneaded with solder powder to form a paste. The solder powder is required to be made of a lead-free solder alloy. As the solder alloy, a Sn—Ag—Cu-based solder alloy is used from the viewpoint of high connection reliability among lead-free solder alloys (for example, Patent Document 1).
On the other hand, there is a demand for highly reliable solder alloys that can withstand environments with severe temperature differences, such as in-vehicle applications. Therefore, it has been proposed to improve the reliability of the solder alloy by adding antimony, bismuth, nickel and the like as additive elements to the conventional Sn—Ag—Cu based solder alloy.

Japanese Patent No. 5756067

However, it has been found that when a solder alloy obtained by adding an additive element to a Sn—Ag—Cu based solder alloy is used, voids also called blow holes are likely to occur. This void can be improved by increasing the amount of the activator in the flux composition, but if a large amount of the activator is added, there is a problem that migration is likely to occur and a problem that the stability over time becomes unstable.

An object of the present invention is to provide a flux composition having excellent stability over time and capable of suppressing the occurrence of voids and migration, and a solder composition and an electronic substrate using the flux composition.

The flux composition according to one aspect of the present invention contains (A) a resin and (B) an activator, and the component (B) has iodine in one molecule (B1) and has a carboxyl group. It is characterized by containing an iodine compound which does not have.

In the flux composition according to one aspect of the present invention, it is preferable that the component (B1) is an iodine compound represented by the following general formula (1).
In the following general formula (1), X ¹ to X ¹⁰ are independently hydrogen, a hydroxyl group, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, bromine, or iodine, and X. At least one of ¹ to X ¹⁰ is iodine.

In the flux composition according to one aspect of the present invention, the component (B1) is preferably 4,4'-diiodobiphenyl.

The solder composition according to one aspect of the present invention is characterized by containing the flux composition according to the one aspect of the present invention and solder powder.
In the solder composition according to one aspect of the present invention, the solder powder is at least one selected from the group consisting of tin, copper, zinc, silver, antimony, lead, indium, bismuth, nickel, cobalt and germanium. It is preferable to contain it.

The electronic substrate according to one aspect of the present invention is characterized by comprising a soldering portion using the solder composition according to the one aspect of the present invention.

According to the present invention, it is possible to provide a flux composition having excellent stability over time and capable of suppressing the occurrence of voids and migration, and a solder composition and an electronic substrate using the flux composition.

[Flux composition]
First, the flux composition of the present embodiment will be described. The flux composition of the present embodiment is a component other than the solder powder in the solder composition, and contains (A) a resin and (B) an activator.
Although it is not always clear why the flux composition of the present embodiment is excellent in stability over time and can suppress the occurrence of voids and migration, the present inventors presume as follows.
First, the present inventors presume that the mechanism by which voids, which are also called blow holes, are likely to occur when a solder alloy in which an additive element is added to a Sn-Ag-Cu based solder alloy is used is as follows. do. That is, the additive elements such as antimony, bismuth and nickel are more easily oxidized than tin, silver and copper. Then, the present inventors presume that these additive elements are oxidized during the reflow treatment to form an oxide film, and voids are generated by this oxide film.
On the other hand, in the flux composition of the present embodiment, as the (B) activator, (B1) an iodine compound having iodine in one molecule and no carboxyl group is used. The component (B1) can impart fluidity to the flux composition accumulated on the upper part of the solder when the solder melts. Since the flux composition has fluidity, it does not prevent the gas from coming out of the solder, and the reoxidized portion can be reactivated. On the other hand, unlike other halogen compounds such as bromide, the component (B1) has little adverse effect on stability over time and migration. As described above, the present inventors presume that the above-mentioned effect of the present invention is achieved.

[(A) component]
Examples of the resin (A) used in the present embodiment include rosin-based resin, epoxy resin, acrylic resin, urethane resin, and polyimide resin. Among these, a rosin-based resin is preferable from the viewpoint of preventing reoxidation.
Examples of the rosin-based resin include rosins and rosin-based modified resins. Examples of rosins include gum rosin, wood rosin and tall oil rosin. Examples of the rosin-based modified resin include disproportionated rosin, polymerized rosin, hydrogenated rosin and derivatives thereof. Hydrogenated rosins include fully hydrogenated rosins, partially hydrogenated rosins, and aliphatic unsaturated monobasic acids such as unsaturated organic acids ((meth) acrylic acid, and α, β- such as fumaric acid and maleic acid. Hydrogenated additive of unsaturated organic acid-modified rosin, which is a modified rosin of aliphatic unsaturated dibasic acid such as unsaturated carboxylic acid, unsaturated carboxylic acid having an aromatic ring such as cinnamic acid, etc.) Also known as "rosin"). One of these rosin-based resins may be used alone, or two or more thereof may be mixed and used.
As the rosin-based resin, epoxy resin, acrylic resin, urethane resin, and polyimide resin, known ones can be used as appropriate.

The blending amount of the component (A) is preferably 20% by mass or more and 70% by mass or less, and more preferably 30% by mass or more and 60% by mass or less with respect to 100% by mass of the flux composition. When the blending amount of the component (A) is equal to or higher than the above lower limit, it is possible to improve the so-called solderability, which prevents oxidation of the copper foil surface of the soldered land and makes it easier for the molten solder to get wet on the surface thereof, and the solder ball is sufficiently used. Can be suppressed. Further, when the blending amount of the component (A) is not more than the upper limit, the amount of flux residue can be sufficiently suppressed.

[(B) component]
The (B) activator used in this embodiment needs to contain an iodine compound having iodine and no carboxyl group in one molecule (B1). With this (B1) component, it is possible to suppress the generation of voids while suppressing the occurrence of migration and the deterioration of stability over time. When a halogen compound (chlorinated compound, brominated compound, etc.) other than the iodine compound is used, migration tends to occur easily. Further, when a compound having a carboxyl group is used, migration tends to occur easily.
The component (B1) is not particularly limited, but preferably contains an aromatic ring from the viewpoint of suppressing voids. Further, the component (B1) preferably has two or more iodines in one molecule. Further, the component (B1) is more preferably an iodine compound represented by the following general formula (1).

In the general formula (1), X ¹ to X ¹⁰ are independently hydrogen, a hydroxyl group, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, bromine, or iodine. Further, X ¹ to X ¹⁰ are preferably hydrogen, a methyl group, a methoxy group, or iodine, and more preferably hydrogen or iodine.
At least one of X ¹ to X ¹⁰ is iodine. It is preferable that at least two of X ¹ to X ¹⁰ are iodine. Further, it is more preferable that at ^least one of X3 and ^X8 is iodine.

The components (B1) include 4,4'-diiodobiphenyl, 3,3'-diiodobiphenyl, 2,2'-diiodobiphenyl, 2-iodobiphenyl, 4-iodobiphenyl, 2,2'-diiodine. -4,4', 6,6'-tetramethyl-1,1'-biphenyl, 4,4'-diiodine-2,2', 6,6'-tetramethyl-1,1'-biphenyl, 3- Bromo-3'-iodine-1,1'-biphenyl, 4-bromo-4'-iodine-1,1'-biphenyl, and 2,2'-iodine-5,5'-dimethoxy-1,1'- Biphenyl and the like can be mentioned. Among these, 4,4'-diiodobiphenyl, 3,3'-diiodobiphenyl, 2,2'-diiodobiphenyl, 2-iodobiphenyl, 4-iodobiphenyl, or 4,4'-diiodo-2 , 2', 6,6'-tetramethyl-1,1'-biphenyl is preferred, and 4,4'-diiodobiphenyl is particularly preferred.

From the viewpoint of suppressing voids, the blending amount of the component (B1) is preferably 0.01% by mass or more and 5% by mass or less, and 0.05% by mass or more and 3% by mass with respect to 100% by mass of the flux composition. It is more preferably 0.1% by mass or more, and particularly preferably 2% by mass or less.

The component (B) is a halogen-based activity other than the component (B1), other active agents (organic acid (hereinafter, also referred to as the component (B2)), and the component (B1), as long as the subject of the present invention can be achieved. An agent (hereinafter, also referred to as (B3) component) and an amine-based activator (hereinafter, also referred to as (B4) component) may be further contained. From the viewpoint of a well-balanced active agent composition, it is preferable to use the combination of the component (B1), the component (B2) and the component (B3).

Examples of the component (B2) include other organic acids in addition to monocarboxylic acids and dicarboxylic acids.
Monocarboxylic acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, tubercrostearic acid. , Arakidic acid, behenic acid, lignoseric 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, tartrate acid, diglycolic acid and the like. Among these, glutaric acid or adipic acid is preferable from the viewpoint of active action.
Examples of other organic acids include dimer acid, levulinic acid, lactic acid, acrylic acid, benzoic acid, salicylic acid, anis acid, citric acid, picolin acid and the like.

When the component (B2) is used, the blending amount thereof is preferably 1% by mass or more and 16% by mass or less with respect to 100% by mass of the flux composition, and 3% by mass or more and 14% by mass. % Or less, more preferably 5% by mass or more and 12% by mass or less.

The component (B3) may be a compound formed by covalent bonding of each single element of chlorine, bromine, and fluorine, such as chlorinated, bromine, and fluoride, but any two or all of chlorine, bromine, and fluorine can be used. It may be a compound having a covalent bond of. These compounds preferably have a polar group such as a hydroxyl group or a carboxyl group, such as a halogenated alcohol or a halogenated carboxyl compound, in order to improve the solubility in an aqueous solvent. Examples of the halogenated alcohol include brominated alcohols (2,3-dibromopropanol, 2,3-dibromobutandiol, trans-2,3-dibromo-2-butene-1,4-diol, 1,4-dibromo). -2-Butanol and tribromoneopentyl alcohol, etc.), chlorinated alcohol (1,3-dichloro-2-propanol, and 1,4-dichloro-2-butanol, etc.), fluorinated alcohol (3-fluorocatechol, etc.) ), And other similar compounds. Halogenated carboxyl compounds include carboxyl chloride compounds (such as 2-chlorobenzoic acid and 3-chloropropionic acid), brominated carboxyl compounds (2,3-dibromopropionic acid, 2,3-dibromosuccinic acid, and 2-). Bromobenzoic acid, etc.), as well as other similar compounds. It should be noted that one of these may be used alone, or two or more thereof may be mixed and used.

When the component (B3) is used, the blending amount thereof is preferably 0.01% by mass or more and 0.5% by mass or less with respect to 100% by mass of the flux composition from the viewpoint of suppressing migration. It is more preferably 02% by mass or more and 0.2% by mass or less, and particularly preferably 0.05% by mass or more and 0.1% by mass or less.

The components (B4) include amines (polyamines such as ethylenediamine), amine salts (amines such as trimethylolamine, cyclohexylamine, and diethylamine, organic acid salts such as aminoalcohol, and inorganic acid salts (hydrochloride, sulfuric acid, and). Hydrobromic acid, etc.)), amino acids (glycine, alanine, aspartic acid, glutamate, and valine, etc.), amide compounds, imidazole compounds, and the like. Specifically, diphenylguanidine hydrobromide, cyclohexylamine hydrobromide, diethylamine salts (such as hydrochlorides, succinates, adipates, and sevacinates), triethanolamine, monoethanolamine, In addition, hydrobromide salts of these amines and the like can be mentioned.

The blending amount of the component (B) is preferably 1% by mass or more and 25% by mass or less, and more preferably 2% by mass or more and 20% by mass or less with respect to 100% by mass of the flux composition. It is particularly preferable that the mass is 1% by mass or more and 15% by mass or less. When the blending amount of the component (B) is not less than the lower limit, the generation of solder balls tends to be suppressed, while when the amount is not more than the upper limit, the insulating property of the flux composition tends to be maintained.

[(C) component]
The flux composition of the present embodiment preferably further contains (C) a solvent from the viewpoint of printability and the like. As the solvent (C) used here, a known solvent can be appropriately used. As such a solvent, it is preferable to use a solvent having a boiling point of 170 ° C. or higher.
Examples of such a solvent include diethylene glycol, dipropylene glycol, triethylene glycol, hexylene glycol, hexyldiglycol, 1,5-pentanediol, methylcarbitol, butylcarbitol, 2-ethylhexyldiglycol, and octanediol. , Phenylglycol, diethylene glycol monohexyl ether (DEH), tetraethylene glycol dimethyl ether (MTEM), dibutylmaleic acid and the like. One of these solvents may be used alone, or two or more of these solvents may be mixed and used.

When the component (C) is used, the blending amount thereof is preferably 10% by mass or more and 60% by mass or less, and more preferably 20% by mass or more and 40% by mass or less with respect to 100% by mass of the flux composition. preferable. When the blending amount of the solvent is within the above range, the viscosity of the obtained solder composition can be appropriately adjusted within an appropriate range.

[(D) component]
The flux composition of the present embodiment may further contain (D) a thixotropic agent from the viewpoint of printability and the like. Examples of the (D) thixo agent used here include cured castor oil, polyamines, polyamides, bisamides, dibenzylideneacetone sorbitol, kaolin, colloidal silica, organic bentonite, and glass frit. One of these thixogens may be used alone, or two or more thereof may be mixed and used.

When the component (D) is used, the blending amount thereof 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 100% by mass of the flux composition. preferable. When the blending amount is at least the above lower limit, sufficient thixo property can be obtained and sagging can be sufficiently suppressed. Further, if the blending amount is not more than the upper limit, the ticking property is too high and printing failure does not occur.

[Other ingredients]
In the flux composition used in this embodiment, in addition to the component (A), the component (B), the component (C) and the component (D), if necessary, other additives and further resins Can be added. Examples of other additives include defoaming agents, antioxidants, modifiers, matting agents, foaming agents, curing accelerators and the like.

[Solder composition]
Next, the solder composition of this embodiment will be described. The solder composition of the present embodiment contains the flux composition of the present embodiment and the solder powder (E) described below.
The blending amount of the flux composition is preferably 5% by mass or more and 40% by mass or less, more preferably 7% by mass or more and 15% by mass or less, and 8% by mass with respect to 100% by mass of the solder composition. It is particularly preferable that it is% or more and 12% by mass or less. When the blending amount of the flux composition is 5% by mass or more (the blending amount of the solder powder is 95% by mass or less), the flux composition as a binder is sufficient, so that the flux composition and the solder powder can be easily mixed. Further, when the blending amount of the flux composition is 40% by mass or less (the blending amount of the solder powder is 60% by mass or more), a sufficient solder bond can be formed when the obtained solder composition is used.

[(E) component]
The (E) solder powder used in the present invention is preferably composed only of lead-free solder powder, but may be leaded solder powder. The solder alloys in this solder powder include tin (Sn), copper (Cu), zinc (Zn), silver (Ag), antimony (Sb), lead (Pb), indium (In), and bismuth (Bi). It preferably contains at least one selected from the group consisting of nickel (Ni), cobalt (Co) and germanium (Ge).
As the solder alloy in this solder powder, an alloy containing tin as a main component is preferable. Further, it is more preferable that the solder alloy contains tin, silver and copper. Further, the solder alloy may contain at least one of antimony, bismuth and nickel as an additive element. According to the flux composition of the present embodiment, the generation of voids can be suppressed even when a solder alloy containing an easily oxidizable additive element such as antimony, bismuth and nickel is used.
Here, the lead-free solder powder refers to a solder metal or alloy powder to which lead is not added. However, although lead is allowed to be present as an unavoidable impurity in the lead-free solder powder, in this case, the amount of lead is preferably 100 mass ppm or less.

Specific examples of the lead-free solder powder include Sn-Ag-Cu series, Sn-Cu series, Sn-Ag series, Sn-Ag-Bi series, Sn-Ag-Cu-Bi series, and Sn-Ag-. Examples thereof include Cu-Ni system, Sn-Ag-Cu-Bi-Sb system, Sn-Ag-Bi-In system, Sn-Ag-Cu-Bi-In-Sb system and the like.

The average particle size of the component (E) is usually 1 μm or more and 40 μm or less, but is more preferably 1 μm or more and 35 μm or less, more preferably 2 μm or more and 35 μm, from the viewpoint of supporting an electronic substrate having a narrow solder pad pitch. It is even more preferably 3 μm or more and 32 μm or less. The average particle size can be measured by a dynamic light scattering type particle size measuring device.

[Manufacturing method of solder composition]
The solder composition of the present embodiment can be produced by blending the flux composition described above and the solder powder (E) described above in the above-mentioned predetermined ratios and stirring and mixing them.

[Electronic substrate]
Next, the electronic substrate of this embodiment will be described. The electronic substrate of the present embodiment is characterized by including a soldering portion using the solder composition described above. The electronic board of the present invention can be manufactured by mounting electronic components on an electronic board (printed wiring board or the like) using the solder composition.
Examples of the coating device used here include a screen printing machine, a metal mask printing machine, a dispenser, and a jet dispenser.
Further, the electronic components are placed on the solder composition coated by the coating device, heated by a reflow furnace under predetermined conditions, and the electronic components are mounted on the printed wiring board by the reflow process. Can be implemented in.

In the reflow step, the electronic component is placed on the solder composition and heated by a reflow oven under predetermined conditions. By this reflow process, sufficient solder bonding can be performed between the electronic component and the printed wiring board. As a result, the electronic component can be mounted on the printed wiring board.
The reflow conditions may be appropriately set according to the melting point of the solder. For example, the preheat temperature is preferably 140 ° C. or higher and 200 ° C. or lower, and more preferably 150 ° C. or higher and 190 ° C. or lower. The preheat time is preferably 60 seconds or more and 120 seconds or less. The peak temperature is preferably 230 ° C. or higher and 270 ° C. or lower, and more preferably 240 ° C. or higher and 255 ° C. or lower. Further, the holding time of the temperature of 220 ° C. or higher is preferably 20 seconds or longer and 60 seconds or shorter.

Further, the solder composition and the electronic substrate of the present embodiment are not limited to the above-described embodiment, and modifications and improvements within the range in which the object of the present invention can be achieved are included in the present invention.
For example, in the electronic board, the printed wiring board and the electronic component are bonded by the reflow process, but the present invention is not limited to this. For example, instead of the reflow step, the printed wiring board and the electronic component may be adhered by a step of heating the solder composition using a laser beam (laser heating step). In this case, the laser light source is not particularly limited, and can be appropriately adopted depending on the wavelength matched to the absorption band of the metal. Laser sources include, for example, solid-state lasers (rubies, glass, YAG, etc.), semiconductor lasers (GaAs, and InGaAsP, etc.), liquid lasers (dye, etc.), and gas lasers (He-Ne, Ar, CO ₂ , and). Eximer etc.).

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these examples. The materials used in Examples and Comparative Examples are shown below.
((A) component)
Rosin-based resin A: Hydrogenated acid-modified rosin, trade name "Pine Crystal KE-604", Rosin-based resin B manufactured by Arakawa Chemical Industry Co., Ltd .: Complete hydrogenated rosin, trade name "Foral AX-E", Eastman Chemical Japan Co., Ltd. Made ((B1) component)
Iodine compound A: 4,4'-diiodobiphenyl ((B2) component)
Organic acid A: Suberic acid Organic acid B: Glutaric acid Organic acid C: Dimer acid, trade name "UNIDYME14", manufactured by Maruzen Yuka Shoji Co., Ltd. ((B3) component)
Halogen-based activator: trans-2,3-dibromo-2-butene-1,4-diol (TDBD)
((C) component)
Solvent A: Diethylene glycol monohexyl ether (DEH)
Solvent B: Tetraethylene glycol dimethyl ether, trade name "Highsolve MTEM", manufactured by Toho Chemical Industry Co., Ltd. (component (D))
Chixo agent: Brand name "Tarren VA-79", manufactured by Kyoeisha Chemical Co., Ltd. ((E) ingredient)
Solder powder: Alloy composition is Sn-Ag-Cu-Bi-Sb, particle size distribution is 15 to 25 μm, solder melting point is 209 to 226 ° C.
(Other ingredients)
Iodine compound B: 2-iodobenzoic acid, Tokyo Chemical Industry Co., Ltd. Antioxidant: Bis [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionic acid] [Ethylene bis (oxyethylene)] , Product name "Irganox 245", manufactured by Ciba Specialty Chemicals

[Example 1]
Login-based resin A 27% by mass, rosin-based resin B 15% by mass, organic acid A 2.5% by mass, organic acid B 0.5% by mass, organic acid C 8% by mass, halogen-based activator 0.1% by mass, iodine compound A0. 1% by mass, 23.4% by mass of solvent A, 10% by mass of solvent B, 9% by mass of tinx agent and 4.4% by mass of antioxidant are put into a container and mixed using a planetary mixer to obtain a flux composition. rice field.
Then, 12% by mass of the obtained flux composition and 88% by mass of the solder powder (100% by mass in total) were put into a container and mixed with a planetary mixer to prepare a solder composition.

[Examples 2 to 6]
A solder composition was obtained in the same manner as in Example 1 except that the materials were blended according to the composition shown in Table 1.
[Comparative Examples 1 to 3]
A solder composition was obtained in the same manner as in Example 1 except that the materials were blended according to the composition shown in Table 1.

<Evaluation of solder composition>
Evaluation of the solder composition (void underchip, migration, stability over time, blowhole) was performed by the following method. The results obtained are shown in Table 1.
(1) Void under the chip FR-4 substrate (thickness) including a chip component with a size of 3.2 mm × 1.6 mm, a solder resist having a pattern on which this chip component can be mounted, and an electrode for connecting this chip component. : 1.6 mm) and a metal mask having the same pattern and a thickness of 150 μm were prepared, and the solder composition was printed. After that, this chip component was mounted on the solder composition and reflowed under the conditions of preheating 150 to 200 ° C. for 95 seconds, peak temperature 250 ° C., and melting time of 220 ° C. or higher for 50 seconds (nitrogen atmosphere: oxygen concentration). 1500 ppm) was carried out to prepare a test substrate. The solder joint portion of the obtained test substrate was observed using an X-ray inspection device (“NLX-5000”, manufactured by NAGOYA ELECTRIC WORKS). Then, the void ratio [(void area / land area) × 100] in the power transistor and QFN after reflow was measured. Then, the subchip void was evaluated according to the following criteria.
◯: The void area ratio is 5% or less.
Δ: The void area ratio is more than 5% and 10% or less.
X: The void area ratio is more than 10%.
(2) For the migration solder composition, each test piece was prepared according to the conditions specified in the standard number IEC 61189-5 / 10.1. However, for each test piece, a comb tooth substrate (size: 50 mm × 50 mm) having a conductor width and a conductor spacing of 0.318 mm was used, and the temperature was 85 ° C. and 85% R. H. In an environment of (relative humidity) and an applied voltage of 32 V, migration between the electrodes after 1000 hours was observed and evaluated according to the following criteria.
○: No migration.
X: Migration occurred slightly.
XX: Migration has occurred.
(3) Stability over time First, the viscosity of the solder composition is measured using the solder composition as a sample. Then, the sample is placed in a sealed container, placed in a constant temperature bath at a temperature of 10 ° C., stored for 6 months, and the viscosity of the stored sample is measured. Then, from the difference (η2-η1) from the viscosity value (η1) before storage and the viscosity value (η2) after storage at a temperature of 10 ° C. for 6 months, the rate of change [(η2-η1) / (η1)). ] Is asked. The viscosity is measured by a spiral type viscosity measurement (measurement temperature: 25 ° C., rotation speed: 10 rpm). Then, the stability over time was evaluated according to the following criteria.
◯: The rate of change is 3.5% or less.
X: The rate of change is more than 3.5% and 5% or less.
XX: The rate of change is more than 5%.
(4) Blow hole A FR-4 substrate (thickness:) including a chip component having a size of 3.2 mm × 1.6 mm, a solder resist having a pattern on which this chip component can be mounted, and an electrode for connecting this chip component. A metal mask having the same pattern and a thickness of 150 μm was prepared (1.6 mm), and the solder composition was printed. After that, 20 of these chip components were placed on the solder composition, and reflow treatment was performed under the conditions of preheating 150 to 200 ° C. for 95 seconds, peak temperature 250 ° C., and melting time of 220 ° C. or higher for 50 seconds (nitrogen atmosphere: An oxygen concentration of 1500 ppm) was carried out to prepare a test substrate. The chip fillet on the obtained test substrate was observed with an optical microscope, and the cavity (blow hole) in the fillet portion was evaluated according to the following criteria.
○: No blow hole.
Δ: Slight blow holes were generated.
X: A large amount of blow holes were generated.

As is clear from the results shown in Table 1, the solder compositions of the present invention (Examples 1 to 6) have good results in all of the subchip voids, migration, stability over time, and blowholes. confirmed.
On the other hand, when the component (B1) was not contained (Comparative Examples 1 to 3), it was found that any one of the subchip void, migration, stability over time, and blow hole was inferior.
Therefore, it has been confirmed that the solder composition of the present invention can be used for narrow pitch parts, can sufficiently suppress voids, and has excellent solder meltability.

The solder composition of the present invention can be suitably used as a technique for mounting an electronic component on an electronic board such as a printed wiring board of an electronic device.

Claims (6)

Contains (A) resin and (B) activator,
The component (B) contains an iodine compound having iodine and no carboxyl group in one molecule (B1).
Flux composition. In the flux composition according to claim 1,
The component (B1) is an iodine compound represented by the following general formula (1).
Flux composition.

(In the general formula (1), X ¹ to X ¹⁰ are independently hydrogen, a hydroxyl group, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, bromine, or iodine, and X 1 to X ¹ to At least one of X ¹⁰ is iodine.) In the flux composition according to claim 2,
The component (B1) is 4,4'-diiodobiphenyl.
Flux composition. The flux composition according to any one of claims 1 to 3 and a solder powder are contained.
Solder composition. In the solder composition according to claim 4,
The solder powder contains at least one selected from the group consisting of tin, copper, zinc, silver, antimony, lead, indium, bismuth, nickel, cobalt and germanium.
Solder composition. A soldering portion using the solder composition according to claim 4 or 5.
Electronic substrate.