JP2021154389A - Solder composition and electronic substrate - Google Patents

Abstract

To provide a solder composition which can sufficiently suppress voids.SOLUTION: A solder composition contains a flux composition containing (A) a rosin-based resin, (B) an activator and (C) a solvent, and (D) solder powder having a melting point of 200°C or higher and 250°C or lower, in which the component (B) contains (B1) a dicarboxylic acid having a substituted or unsubstituted alkylene group and 3 to 10 carbon atoms, and the component (C) contains (C1) diol or diacetate of diol having a boiling point of 220°C or higher and 250°C or lower.SELECTED DRAWING: None

Description

The present invention relates to solder compositions and electronic substrates.

The solder composition is a mixture obtained by kneading a flux composition (rosin-based resin, activator, solvent, etc.) with solder powder to form a paste (for example, Patent Document 1). In this solder composition, in addition to solderability such as solder meltability and the property that the solder easily wets and spreads (solder wet spread), void suppression and printability are required.
On the other hand, due to the diversification of the functions of electronic devices, large electronic components are being mounted on electronic boards. Further, among the large electronic components, there are electronic components having a large area of electrode terminals (for example, QFN (Quad Flatpack No Lead), power transistor). In such an electronic component, since the printed area of the solder composition is large, voids tend to occur easily.

Japanese Patent No. 5756067

In solder compositions, the use of high boiling point, high viscosity solvents such as isobornylcyclohexanol has been studied to reduce voids. However, it has been found that even if such a solvent having a high boiling point and a high viscosity is used, the effect of reducing voids is insufficient for electronic components having a large area of electrode terminals such as QFN.

Therefore, an object of the present invention is to provide a solder composition capable of sufficiently suppressing voids and an electronic substrate using the same.

The solder composition according to one aspect of the present invention is a flux composition containing (A) a rosin-based resin, (B) an activator and (C) a solvent, and (D) has a melting point of 200 ° C. or higher and 250 ° C. or lower. The component (B) contains a solder powder, the component (B) has a (B1) substituted or unsubstituted alkylene group, and contains a dicarboxylic acid having 3 to 10 carbon atoms, and the component (C) contains (C1). ) It is characterized by containing a diol having a boiling point of 220 ° C. or higher and 250 ° C. or lower, or a diacetate of the diol.

In the solder composition according to one aspect of the present invention, the component (B1) is malonic acid, succinic acid, glutaric acid, adipic acid, pimelli acid, suberic acid, azelaic acid, sebacic acid, phenylmalonic acid, phenyl. It is preferably at least one selected from the group consisting of succinic acid, cyclopentanedicarboxylic acid, cyclohexanedicarboxylic acid, and cyclohexendicarboxylic acid.
In the solder composition according to one aspect of the present invention, the component (C1) is 1,4-butanediol, 1,5-pentanediol, 2-ethyl-1,3-hexanediol, 1,2-. It is preferably at least one selected from the group consisting of hexanediol, dipropylene glycol, 1,4-butanediol diacetate, and 1,3-butylenediol diacetate.
In the solder composition according to one aspect of the present invention, the boiling point of the component (C1) is preferably 230 ° C. or higher and 250 ° C. or lower.
In the solder composition according to one aspect of the present invention, it is preferable that the component (B) further contains (B2) dimer acid.
In the solder composition according to one aspect of the present invention, it is preferable that the component (B) further contains at least one selected from the group consisting of alanine, L-histidine, and a phosphonitrile acid phenyl ester. ..

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

According to the solder composition of the present invention, the reason why voids can be sufficiently suppressed is not always clear, but the present inventors presume as follows.
That is, in the solder composition of the present invention, diol or diol diacetate having a boiling point (C1) of 220 ° C. or higher and 250 ° C. or lower is used as the (C) solvent. A part of the component (C1) volatilizes before the solder melts or when the solder melts to become a gas, and this gas has an action of pushing the gas in the solder composition to the outside. Since the solder composition containing the non-volatile (C1) component has a certain degree of fluidity even when the solder is melted, the gas in the solder composition is gradually collected and released to the outside. In this way, voids can be sufficiently suppressed. Further, the organic acid, which is one of the activators (B), is an essential component from the viewpoint of solderability, but it can be a factor of generating voids depending on the type of the organic acid. On the other hand, in the present invention, an organic acid ((B1) component) that is unlikely to cause voids is selected and used. As described above, the present inventors presume that the above-mentioned effect of the present invention is achieved.

According to the present invention, it is possible to provide a solder composition capable of sufficiently suppressing voids, and an electronic substrate using the same.

The solder composition of the present embodiment contains the flux composition described below and the solder powder (D) described below.

[Flux composition]
First, the flux composition used in this embodiment will be described. The flux composition used in this embodiment is a component other than the solder powder in the solder composition, and contains (A) a rosin-based resin, (B) an activator, and (C) a solvent.

[(A) component]
Examples of the (A) rosin-based resin used in the present embodiment 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 rosins, polymerized rosins, hydrogenated rosins 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 called "rosin"). One of these rosin-based resins may be used alone, or two or more thereof may be mixed and used.

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, and the solder ball is sufficiently used. Can be suppressed. Further, when the blending amount of the component (A) is not more than the above upper limit, the amount of flux residue can be sufficiently suppressed.

[(B) component]
The (B) activator used in this embodiment has a (B1) substituted or unsubstituted alkylene group and contains a dicarboxylic acid having 3 to 10 carbon atoms. This (B1) component is unlikely to be a factor in generating voids. On the other hand, when the number of carbon atoms in one molecule exceeds 11, the organic acid itself becomes a factor for generating voids.
In the component (B1), the substituent of the alkylene group is preferably a hydrocarbon group, more preferably an alkyl group or a phenyl group. Further, a cyclic structure may be formed by the substituent and the alkylene group. Examples of the cyclic structure include a cyclopentane ring, a cyclohexane ring, and a cyclohexene ring.

The components (B1) include malonic acid, succinic acid, glutaric acid, adipic acid, pimelli acid, suberic acid, azelaic acid, sebacic acid, phenylmalonic acid, phenylsuccinic acid, cyclopentanedicarboxylic acid, cyclohexanedicarboxylic acid, and cyclohexene. Examples include dicarboxylic acid. One of these may be used alone, or two or more thereof may be mixed and used.
The blending amount of the component (B1) is preferably 0.5% by mass or more and 7% by mass or less with respect to 100% by mass of the flux composition from the viewpoint of voids and active action, and is 1% by mass or more and 5% by mass or less. It is more preferably 1.5% by mass or more and 3% by mass or less.

In the present embodiment, the component (B) may further contain (B2) dimer acid. Since this component (B2) tends to prevent the reoxidation of the solder powder, the action of other activators can be synergistically enhanced. In addition, the component (B2) is unlikely to be a factor in generating voids.
The component (B2) is preferably a dimer acid produced by the polymerization of unsaturated fatty acids. The carbon number of this unsaturated fatty acid is not particularly limited, but is preferably 8 or more and 22 or less, more preferably 12 or more and 18 or less, and particularly preferably 18. Further, the dimer acid may be any as long as it contains a dibasic acid as a main component (50% by mass or more), and may contain a monobasic acid or a tribasic acid.
In the present embodiment, it is preferable not to use an organic acid other than the component (B1) and the component (B2) from the viewpoint of suppressing the ball and voids on the side of the chip.
The blending amount of the component (B2) is preferably 1% by mass or more and 20% by mass or less, preferably 3% by mass or more and 15% by mass or less, based on 100% by mass of the flux composition from the viewpoint of voids and active action. It is more preferable that there is, and it is particularly preferable that it is 5% by mass or more and 10% by mass or less.

In addition to the components (B1) and (B2), the component (B) contains other activators ((B3) halogen-based activator, (B4) amine-based activator, and so on, as long as the object of the present invention can be achieved. (B5) Phenylnitrile acid phenyl ester, etc.) may be further contained. The total amount of the component (B1) and the component (B2) to be blended is preferably 90% by mass or more, preferably 95% by mass or more, based on 100% by mass of the component (B) from the viewpoint of voids and active action. Is more preferable.

The component (B3) may be a compound formed by covalent bonds 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 alcohol (2,3-dibromopropanol,
2,3-Dibromobutanediol, trans-2,3-dibromo-2-butene-1,4-diol, 1,4-dibromo-2-butanol, tribromoneopentyl alcohol, etc.), chlorinated alcohol (1) , 3-Dichloro-2-propanol, and 1,4-dichloro-2-butanol, etc.), fluorinated alcohols (3-fluorocatechol, etc.), and other similar compounds. The carboxylated carboxyl compounds include carboxyl compounds iodide (2-iodobenzoic acid, 3-iodobenzoic acid, 2-iodopropionic acid, 5-iodosalicylic acid, and 5-iodoanthranyl acid, etc.), and carboxyl chloride compounds (2-). Chlorobenzoic acid and 3-chloropropionic acid, etc.), brominated carboxyl compounds (2,3-dibromopropionic acid, 2,3-dibromosuccinic acid, and 2-bromobenzoic acid, etc.), and other similar compounds. Can be mentioned. In addition, these may be used individually by 1 type, and may use 2 or more types in mixture.

The components (B4) include amines (polyamines such as ethylenediamine), amine salts (amines such as trimethylolamine, cyclohexylamine, and diethylamine, and organic acid salts and inorganic acid salts such as aminoalcohol (hydrochloride, sulfuric acid, and). Hydrobromic acid, etc.)), amino acids (L-histidine, glycine, alanine, aspartic acid, glutamate, and valine, etc.), amide compounds, imidazole compounds, and the like. Specifically, diphenylguanidine hydrobromide, cyclohexylamine hydrobromide, diethylamine salts (such as hydrochloride, succinate, adipate, and sebasinate), triethanolamine, monoethanolamine, In addition, hydrobromide salts of these amines and the like can be mentioned. Among these, it is preferable to use alanine or L-histidine from the viewpoint that it is unlikely to cause voids. Further, it is more preferable to use these in combination with the component (B1).
Examples of the component (B5) include "Ravitor FP-110" manufactured by Fushimi Pharmaceutical Co., Ltd. The component (B5) is unlikely to be a factor in generating voids. Further, it is more preferable to use the component (B5) and the component (B1) in combination.

The blending amount of the component (B) is preferably 1% by mass or more and 25% by mass or less, more preferably 2% by mass or more and 20% by mass or less, based on 100% by mass of the flux composition. It is particularly preferable that it is by mass% or more and 15% by mass or less. If the blending amount of the component (B) is less than the lower limit, solder balls tend to be generated, while if it exceeds the upper limit, the insulating property of the flux composition tends to decrease.

[(C) component]
The solvent (C) used in the present embodiment needs to contain diol or diacetate of diol having a boiling point (C1) of 220 ° C. or higher and 250 ° C. or lower. The component (C1) can suppress the generation of voids.
When the boiling point of the component (C1) is less than 220 ° C. and when the boiling point of the component (C1) is more than 250 ° C., the generation of voids cannot be sufficiently suppressed. In the present specification, the boiling point means the boiling point at 1013 hPa. From the viewpoint of voids, the boiling point of the component (C1) is preferably 220 ° C. or higher and 240 ° C. or lower, more preferably 225 ° C. or higher and 235 ° C. or lower, and preferably 230 ° C. or higher and 235 ° C. or lower. Especially preferable.

As the component (C1), 1,4-butanediol (boiling point: 230 ° C.), 1,5-pentanediol (boiling point: 240 ° C.), 2-ethyl-1,3-hexanediol (boiling point: 242 ° C.), 1,2-Hexanediol (boiling point: 223 ° C), dipropylene glycol (boiling point: 230 ° C), 1,4-butanediol diacetate (boiling point: 232 ° C), and 1,3-butylenediol diacetate (boiling point: 230 ° C). 232 ° C.) and the like. Among these, 1,4-butanediol and 1,3-butylenediol diacetate are more preferable from the viewpoint of the melting point of the solvent. One of these may be used alone, or two or more thereof may be mixed and used.

The component (C) may contain a solvent (component (C2)) other than the component (C1) as long as the object of the present invention can be achieved.
As the component (C2), diethylene glycol monohexyl ether (DEH), diethylene glycol monobutyl ether, α, β, γ-turpineol, benzyl glycol, diethylene glycol mono2-ethylhexyl ether, tripropylene glycol, diethylene glycol monobenzyl ether, diethylene glycol dibutyl ether, Examples thereof include tripropylene glycol monomethyl ether, dipropylene glycol monobutyl ether, ethylene glycol mono2-ethylhexyl ether, diethylene glycol monoethyl ether acetate and 2,2-dimethyl-1,3-propanediol. One of these may be used alone, or two or more thereof may be mixed and used.

When the component (C2) is used, the mass ratio of the component (C2) to the component (C) ((C2) / (C)) is 1/15 or more 1 / from the viewpoint of the balance between void suppression and printability. It is preferably 1 or less, more preferably 1/10 or more and 1/2 or less, and particularly preferably 1/5 or more and 1/3 or less.

The blending amount of the component (C) is preferably 20% by mass or more and 60% by mass or less, more preferably 25% by mass or more and 50% by mass or less, and 30% by mass with respect to 100% by mass of the flux composition. It is particularly preferable that it is% or more and 40% by mass or less. 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.

In the present embodiment, a thixo agent may be further contained from the viewpoint of printability and the like. Examples of the thixo agent used in the present embodiment include cured castor oil, amides, 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 a thixo agent is used, the blending amount thereof is preferably 2% by mass or more and 20% by mass or less, and more preferably 4% by mass or more and 12% by mass or less with respect to 100% by mass of the flux composition. If the blending amount is less than the lower limit, the thixo property is not obtained and dripping tends to occur. On the other hand, if the blending amount exceeds the upper limit, the tix property is too high and printing defects tend to occur.

[Other ingredients]
In addition to the component (A), the component (B), the component (C) and the thixo agent, other additives and other resins are added to the flux composition used in the present embodiment, if necessary. be able to. Other additives include antifoaming agents, antioxidants, modifiers, matting agents, foaming agents and the like. The blending amount of these additives is preferably 0.01% by mass or more and 5% by mass or less with respect to 100% by mass of the flux composition. Examples of other resins include acrylic resins.

[Solder composition]
Next, the solder composition of the present embodiment will be described. The solder composition of the present embodiment contains the flux composition of the present embodiment described above and the solder powder (D) described below.
The blending amount of the flux composition is preferably 5% by mass or more and 35% 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 the content is 12% by mass or less. When the blending amount of the flux composition is less than 5% by mass (when the blending amount of the solder powder exceeds 95% by mass), the flux composition as a binder is insufficient, so the flux composition and the solder powder are mixed. On the other hand, when the blending amount of the flux composition exceeds 35% by mass (when the blending amount of the solder powder is less than 65% by mass), when the obtained solder composition is used, It tends to be difficult to form a sufficient solder joint.

[(D) component]
The solder powder (D) used in this embodiment is a solder powder having a melting point of 200 ° C. or higher and 250 ° C. or lower. In this embodiment, the boiling point of the component (C1) is defined on the premise that a solder powder having a melting point of 200 ° C. or higher and 250 ° C. or lower is used.
As the solder alloy in this solder powder, an alloy containing tin (Sn) as a main component is preferable. Examples of the second element of this alloy include silver (Ag), copper (Cu), zinc (Zn), bismuth (Bi), indium (In) and antimony (Sb). Further, other elements (third element and later) may be added to this alloy as needed. Other elements include copper, silver, bismuth, indium, antimony, aluminum (Al) and the like.
Here, the lead-free solder powder refers to a solder metal or alloy powder to which lead is not added. However, it is permissible for lead to be present as an unavoidable impurity in the lead-free solder powder, but in this case, the amount of lead is preferably 300 mass ppm or less.

Specific examples of the solder alloy in the lead-free solder powder include Sn-Ag type and Sn-Ag-Cu type. Among these, Sn-Ag-Cu based solder alloys are preferably used from the viewpoint of the strength of the solder joint. The melting point of the Sn—Ag—Cu-based solder is usually 200 ° C. or higher and 250 ° C. or lower (preferably 200 ° C. or higher and 240 ° C. or lower). Among the Sn—Ag—Cu type solders, the solder having a low silver content has a melting point of 210 ° C. or higher and 250 ° C. or lower (preferably 220 ° C. or higher and 240 ° C. or lower).

The average particle size of the component (D) is usually 1 μm or more and 40 μm or less, but it is more preferably 1 μm or more and 35 μm or less from the viewpoint of supporting an electronic substrate having a narrow solder pad pitch, and 2 μm or more and 30 μm. It is even more preferably 3 μm or more and 20 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 (D) 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, etc.) using the solder composition.
The solder composition of the present embodiment described above can sufficiently suppress voids having a large diameter even when the printed area of the solder composition is large. Therefore, as the electronic component, an electronic component having a large electrode terminal area (for example, QFN, power transistor) may be used. The printed area of the solder composition may be, for example, 20 mm ² or more, 30 mm ² or more, ^{or 40 mm 2} or more. The printed area corresponds to the area of the electrode terminals of the electronic component.
Examples of the coating apparatus 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 a reflow process. Can be implemented in.

In the reflow step, the electronic component is placed on the solder composition and heated by a reflow furnace 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 160 ° 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. 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 a 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 laser light (laser heating step). In this case, the laser light source is not particularly limited, and can be appropriately adopted according to the wavelength matched to the absorption band of the metal. Laser light sources include, for example, solid-state lasers (ruby, glass, YAG, etc.), semiconductor lasers (GaAs, and InGaAsP, etc.), liquid lasers (dye, etc.), and gas lasers (He-Ne, Ar, CO ₂ , and so on). 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.
(Ingredient (A))
Rosin-based resin: Hydrogenated acid-modified rosin, trade name "Pine Crystal KE-604", manufactured by Arakawa Chemical Industry Co., Ltd. ((B1) component)
Organic Acid A: Adipic Acid, Tokyo Kasei Co., Ltd. Organic Acid B: Succinic Acid, Tokyo Kasei Co., Ltd. Organic Acid C: Phenylsuccinic Acid, Tokyo Kasei Co., Ltd. Organic Acid D: Suberic Acid, Tokyo Kasei Co., Ltd. Organic Acid E: Azeline Acid, Tokyo Kasei's organic acid F: sebacic acid, Tokyo Kasei's organic acid G: malonic acid, Tokyo Kasei's organic acid H: 1,4-cyclohexanedicarboxylic acid, Tokyo Kasei's organic acid I: cis- 4-Cyclohexene-1,2-dicarboxylic acid, manufactured by Tokyo Kasei Co., Ltd. ((B2) component)
Organic acid J: Dimer acid, trade name "UNIDYME14", manufactured by Air Brown ((B3) component)
Halogen activator: trans-2,3-dibromo-2-butene-1,4-diol (TDBD)
((B4) component)
Amine-based activator A: Alanine, manufactured by Tokyo Kasei Co., Ltd. Amine-based activator B: L-histidine, manufactured by Tokyo Kasei Co., Ltd. ((B5) component)
Phenyl nitrile acid phenyl ester: trade name "Ravitor FP-110", manufactured by Fushimi Pharmaceutical Co., Ltd. ((C1) component)
Solvent A: Dipropylene glycol (boiling point: 230 ° C), Tokyo Kasei Co., Ltd. Solvent B: 1,2-hexanediol (boiling point: 223 ° C.), Osaka Organic Chemical Industry Co., Ltd. Solvent C: 1,4-butanediol (boiling point) : 230 ° C), Tokyo Kasei Co., Ltd. solvent D: 1,5-pentanediol (boiling point: 240 ° C.), Tokyo Kasei Co., Ltd. solvent E: 2-ethyl-1,3-hexanediol (boiling point: 242 ° C.), Japan Solvent F: 1,3-butylenediol diacetate (boiling point: 232 ° C.) manufactured by Emulsifier, solvent G: 1,4-butanediol diacetate (boiling point: 232 ° C.) manufactured by Daicel Chemical Co., Ltd., trade name "CELTOL 1,4" -BDDA ", manufactured by Daicel Chemical Co., Ltd. ((C2) component)
Solvent H: 1,3-butanediol (boiling point: 203 ° C)
Solvent I: 2,4-diethyl-1,5-pentanediol (boiling point: 300 ° C.), trade name "Kyowadiol PD-9", KH Neochem solvent J: propylene glycol diacetate (boiling point: 190 ° C.)
Solvent K: 1,6-hexanediol diacetate (boiling point: 260 ° C)
Solvent L: 1- (2-butoxy-1-methylethoxy) propan-2-ol (boiling point: 230 ° C.), Dow Chemicals solvent M: diethylene glycol monohexyl ether (DEH) (boiling point: 258 ° C.)
(Component (D))
Solder powder: Alloy composition is Sn-3.0Ag-0.5Cu, particle size distribution is 20 to 38 μm, solder melting point is 217 to 220 ° C.
(Other ingredients)
Organic Acid K: Eikosan Diacid, Tixed Agent manufactured by Tokyo Kasei Co., Ltd .: Product name "Slipax H", Antioxidant manufactured by Nippon Kasei Co., Ltd .: Product name "Irganox 245", manufactured by BASF

[Example 1]
A container containing 46% by mass of rosin-based resin, 2% by mass of organic acid A, 8.5% by mass of organic acid J, 0.5% by mass of halogen-based activator, 35% by mass of solvent A, 6% by mass of tinx agent and 2% by mass of antioxidant. And mixed using a planetary mixer to obtain a flux composition.
Then, 11% by mass of the obtained flux composition and 89% 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 10]
A solder composition was obtained in the same manner as in Example 1 except that each material was blended according to the composition shown in Table 1.

[Examples 11 to 20]
A solder composition was obtained in the same manner as in Example 1 except that each material was blended according to the composition shown in Table 2.

[Comparative Examples 1 to 7]
A solder composition was obtained in the same manner as in Example 1 except that each material was blended according to the composition shown in Table 3.

<Evaluation of solder composition>
The evaluation of the solder composition (QFN void, power transistor component void, print volatility) was carried out by the following method. The obtained results are shown in Tables 1 to 3.
In the following method, the evaluation substrate was prepared by the following method.
That is, a substrate (Tamura) on which chip parts (1608 chips (size: 1.6 mm × 0.8 mm) and 1005 chips (size: 1.6 mm × 0.8 mm), QFP parts, QFN parts, BGA parts) can be mounted. A 120 μm thick metal mask is used to print a solder composition on a “SP-TDC” manufactured by Mfg. Co., Ltd., and a QFN component and a power transistor component are mounted. Under the conditions, the solder composition was melted and soldered in a reflow furnace (manufactured by Tamura Manufacturing Co., Ltd.) to obtain an evaluation substrate.
The reflow conditions A and B are as follows.
(I) Reflow condition A
The preheat temperature is 150 to 180 ° C. (about 80 seconds), the time at which the temperature is 220 ° C. or higher is about 50 seconds, and the peak temperature is 250 ° C.
(Ii) Reflow condition B
The preheat temperature is 150 to 180 ° C. (about 80 seconds), the time at which the temperature is 220 ° C. or higher is about 50 seconds, and the peak temperature is 235 ° C.
(Iii) Reflow condition C
The preheat temperature is 150 to 180 ° C. (about 80 seconds), the time at which the temperature is 220 ° C. or higher is about 50 seconds, and the peak temperature is 245 ° C.
(1) For each of the evaluation boards obtained under the QFN void reflow conditions A and B, the mounting portion of the QFN component (size: 8 mm × 8 mm, thickness: 0.75 mm) is mounted on an X-ray inspection device (“NLX-5000”). , NAGOYA ELECTRIC WORKS). From the obtained image, the void ratio [(void area / electrode area) × 100] was calculated, and the average value (n = 4) was taken. Then, based on the void ratio, the QFN void was evaluated according to the following criteria.
⊚: The void rate is less than 15%.
◯: The void rate is 15% or more and less than 20%.
Δ: The void rate is 20% or more and less than 25%.
X: The void rate is 25% or more.
(2) Power transistor parts Void power transistor (size: 5.5 mm x 6.5 mm, thickness: 2.3 mm, land: tin plating, land area: 30 mm ² ) can be mounted on a substrate having electrodes. The solder composition was printed using a metal mask having a pattern to be used. Then, a power transistor was mounted on the solder composition, and reflow was performed under the reflow condition C to prepare a test substrate. The solder joint portion of the obtained test substrate was observed using an X-ray inspection apparatus (“NLX-5000”, manufactured by NAGOYA ELECTRIC WORKS). Then, the voids in the power transistor after reflow were observed, the void ratio (void area / electrode area × 100) was calculated from the obtained image, and the average value (N = 4) was taken. Then, based on the void ratio, the power transistor component void was evaluated according to the following criteria.
◯: The void rate is less than 10%.
Δ: The void rate is 10% or more and less than 13%.
X: The void rate is 13% or more.
(3) Printing Volatility Place the obtained solder composition on a metal mask (thickness: 0.2 mm) on a square of 8 mm x 8 mm, perform hand-print printing, and leave it for 12 hours in an atmosphere at a temperature of 25 ° C. , Checked for stickiness. Then, the print volatility was evaluated according to the following criteria.
〇: The solder composition is sticky.
X: The solder composition is not sticky.

As is clear from the results shown in Table 1, it was confirmed that the solder compositions of the present invention (Examples 1 to 20) had good results in all of the QFN voids, the power transistor component voids, and the print volatility. Was done. Therefore, it was confirmed that the solder composition of the present invention can sufficiently suppress voids.

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 (7)

A flux composition containing (A) a rosin resin, (B) an activator and (C) a solvent, and (D) a solder powder having a melting point of 200 ° C. or higher and 250 ° C. or lower are contained.
The component (B) has a (B1) substituted or unsubstituted alkylene group and contains a dicarboxylic acid having 3 to 10 carbon atoms.
A solder composition, wherein the component (C) contains a diol or a diacetate of a diol having a boiling point (C1) of 220 ° C. or higher and 250 ° C. or lower. In the solder composition according to claim 1,
The components (B1) are malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, phenylmalonic acid, phenylsuccinic acid, cyclopentanedicarboxylic acid, cyclohexanedicarboxylic acid, and cyclohexene. A solder composition, which is at least one selected from the group consisting of dicarboxylic acids. In the solder composition according to claim 1 or 2.
The component (C1) is 1,4-butanediol, 1,5-pentanediol, 2-ethyl-1,3-hexanediol, 1,2-hexanediol, dipropylene glycol, 1,4-butanediol di. A solder composition comprising at least one selected from the group consisting of acetate and 1,3-butylenediol diacetate. In the solder composition according to claim 1 or 2.
A solder composition having a boiling point of the component (C1) of 230 ° C. or higher and 250 ° C. or lower. The solder composition according to any one of claims 1 to 4.
A solder composition, wherein the component (B) further contains (B2) dimer acid. The solder composition according to any one of claims 1 to 5.
A solder composition, wherein the component (B) further contains at least one selected from the group consisting of alanine, L-histidine, and a phosphonitrile acid phenyl ester. An electronic substrate comprising a soldering portion using the solder composition according to any one of claims 1 to 6.