JP6913064B2 - Method for manufacturing solder composition and electronic board - Google Patents

Description

The present invention relates to a method for manufacturing a solder composition and an electronic substrate.

The solder composition is a mixture in which a flux composition (rosin-based resin, activator, solvent, etc.) is kneaded with solder powder to form a paste (see Patent Document 1). In recent years, lead-free solder containing no lead (Pb) has been widely used as a solder in consideration of environmental problems. Further, as the flux composition, in consideration of environmental problems, halogen-free with reduced halogen and non-halogen containing no halogen are required.

Japanese Patent No. 5887330

The halogen compound in the conventional flux composition is used as an activator having excellent performance. Further, although the reason is not clear, it was found that this halogen compound suppresses the phenomenon that the solder composition before melting drips from the through holes (hereinafter, also referred to as “dripping”). This sagging becomes a problem when mounting electronic components with leads, such as discrete components (eg, transistors, diodes and resistor components, etc.). Therefore, there is a demand for a method of suppressing dripping without using a halogen compound.

An object of the present invention is to provide a solder composition which is halogen-free or non-halogen and can sufficiently suppress dripping, and a method for producing an electronic substrate using these.

As a result of intensive studies to achieve the above object, the present inventors have found the following findings. That is, when a low molecular weight dicarboxylic acid, which is an activator, and two kinds of amide-based thixogens having different melting points or softening points are used in combination, surprisingly, dripping is suppressed without using a halogen compound. We have found what we can do and have completed the present invention.
That is, the solder composition of the present invention contains (A) a rosin-based resin, (B) an activator, (C) a solvent and (D) a flux composition containing a thixo agent, and (E) a solder powder. The component (B) contains a dicarboxylic acid having a molecular weight of (B1) of 133 or less, and the component (D1) is an amide-based solder having a melting point or softening point of 200 ° C. or higher, and (D2). ) It is characterized by containing an amide-based tinxant having a melting point or a softening point of 150 ° C. or lower.

In the solder composition of the present invention, the component (D1) is formed by reacting a carboxylic acid with a diamine, and the carboxylic acid is an aliphatic monocarboxylic acid having 16 or more carbon atoms and a polybasic acid. Is preferably contained.
In the solder composition of the present invention, the component (D2) is preferably ethylene bisstearic acid amide.
In the solder composition of the present invention, the chlorine concentration in the solder composition is 900 mass ppm or less, the bromine concentration is 900 mass ppm or less, the iodine concentration is 900 mass ppm or less, and the halogen concentration is It is preferably 1500 mass ppm or less.

The method for manufacturing an electronic substrate of the present invention is a method for manufacturing an electronic substrate using the solder composition, which comprises a coating step of applying the solder composition on a wiring board and an electronic component on the solder composition. The method is characterized by including a mounting process for mounting and a reflow step for heating the wiring board on which the electronic component is mounted.

According to the present invention, it is possible to provide a solder composition which is halogen-free or non-halogen and can sufficiently suppress dripping, and a method for producing an electronic substrate using these.

The solder composition of the present embodiment contains the flux composition described below and the solder powder (E) 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, (C) a solvent, and (D) a thixo agent. be.

[(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 component (A) preferably contains a rosin-based resin having an acid value of 200 mgKOH / g or more and a rosin ester having an acid value of 50 mgKOH / g or less. Examples of such component (A1) include rosin-based resins having an acid value of 200 mgKOH / g or more (excluding rosin esters) among the components (A). Further, from the viewpoint of active action, the acid value of the component (A1) is preferably 220 mgKOH / g or more.
The component (A2) is a rosin ester. Examples of this rosin ester include those obtained by esterifying rosins and rosin-based modified resins. From the viewpoint of suppressing cracks in the flux residue, the acid value of the component (A2) is preferably 30 mgKOH / g or less, more preferably 20 mgKOH / g or less, and particularly preferably 15 mgKOH / g or less. ..
The acid value (average acid value) can be measured by determining potassium hydroxide necessary for neutralizing the free fatty acid contained in 1 g of the sample.

The blending amount of the component (A) is preferably 20% by mass or more and 60% by mass or less, and more preferably 25% by mass or more and 50% 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 needs to contain (B1) a dicarboxylic acid having a molecular weight of 133 or less. By combining this component (B1) with the components (D1) and (D2) described later, it is possible to suppress dripping, although the reason is not clear. The molecular weight of the component (B1) is preferably 90 or more and 133 or less, and more preferably 104 or more and 133 or less.
Examples of the component (B1) include oxalic acid (molecular weight 90), malonic acid (molecular weight 104), succinic acid (molecular weight 118), and glutaric acid (molecular weight 132).

The blending amount of the component (B1) is preferably 0.1% by mass or more and 5% by mass or less, and preferably 0.2% by mass or more and 4% by mass or less with respect to 100% by mass of the flux composition. More preferably, it is 0.5% by mass or more and 3.5% by mass or less. When the blending amount is at least the above lower limit, the solder wettability can be further improved. Further, when the blending amount is not more than the above upper limit, the storage stability of the flux composition can be further improved.

The component (B) may further contain an organic acid (component (B2)) other than the component (B1) as long as the subject of the present invention can be achieved.
Examples of the component (B2) include monocarboxylic acids, dicarboxylic acids other than the component (B1), and other organic acids. One of these may be used alone, or two or more thereof may be mixed and used.
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, and glycolic acid.
Examples of the dicarboxylic acid include adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, tartaric acid, and diglycolic acid.
Other organic acids include dimer acid, trimer acid, levulinic acid, lactic acid, acrylic acid, benzoic acid, salicylic acid, anis acid, citric acid, picolin acid and the like. Among these, it is more preferable to use dimer acid from the viewpoint of improving solder wettability.

In addition to the components (B1) and (B2), the component (B) includes other activators ((B3) halogen-based activators, (B4) amine-based activators, etc., as long as the problems of the present invention can be achieved. ) May be further contained. However, from the viewpoint of halogen-free, the component (B) is preferably composed of only the component (B1) and the component (B2). The total amount of the (B1) component and the (B2) component is preferably 85% by mass or more, more preferably 90% by mass or more, based on 100% by mass of the (B) component. It is particularly preferably 95% by mass or more.

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 2,3-dibromopropanol, 2,3-dibromobutanediol, trans-2,3-dibromo-2-butene-1,4-diol, 1,4-dibromo-2-butanol, and the like. And brominated alcohols such as tribromoneopentyl alcohols, chlorinated alcohols such as 1,3-dichloro-2-propanol and 1,4-dichloro-2-butanol, fluorinated alcohols such as 3-fluorocatechol, and Other compounds similar to these can be mentioned. The carboxylated carboxyl compounds include carboxyl compounds iodide such as 2-iodobenzoic acid, 3-iodobenzoic acid, 2-iodopropionic acid, 5-iodosalicylic acid, and 5-iodoanthranic acid, 2-chlorobenzoic acid, and Examples thereof include carboxyl chloride compounds such as 3-chloropropionic acid, brominated carboxyl compounds such as 2,3-dibromopropionic acid, 2,3-dibromosuccinic acid, and 2-bromobenzoic acid, and other similar compounds. .. In addition, these may be used individually by 1 type, and may use 2 or more types in mixture.

As the component (B4), 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 sebacates), triethanolamine, monoethanolamine, In addition, hydrobromide of these amines and the like can be mentioned.

The blending amount of the component (B) is preferably 1% by mass or more and 20% by mass or less, more preferably 3% by mass or more and 15% 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 12% by mass or less. When the blending amount is at least the above lower limit, the solder balls can be suppressed more reliably. Further, when the blending amount is not more than the above upper limit, the insulation reliability of the flux composition can be ensured.

[(C) component]
As the solvent (C) used in this embodiment, 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, 1,5-pentanediol, methylcarbitol, butylcarbitol, octanediol, phenylglycol, diethylene glycol monohexyl ether, and diethylene glycol. Examples include mono2-ethylhexyl ether (EHDG), 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.

The blending amount of the component (C) is preferably 10% by mass or more and 60% by mass or less, and more preferably 20% by mass or more and 50% by mass or less with respect to 100% by mass of the flux composition. 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 (D) tyxo agent used in the present embodiment contains (D1) an amide-based thiox agent having a melting point or softening point of 200 ° C. or higher, and (D2) an amide-based tyxo agent having a melting point or softening point of 150 ° C. or lower. It is necessary. The softening point of the thixogen can be measured by the dry-bulb method. Further, the melting point of the thixogen can be measured by the method described in JIS-K-0064.
Examples of the component (D1) include those produced by reacting a carboxylic acid with a diamine. Here, the carboxylic acid is preferably a mixture of an aliphatic monocarboxylic acid having 16 or more carbon atoms and a polybasic acid from the viewpoint of increasing the melting point.
As the aliphatic monocarboxylic acid, saturated aliphatic monocarboxylic acid and hydroxycarboxylic acid are preferable. Examples of the aliphatic monocarboxylic acid having 16 or more carbon atoms include palmitic acid, stearic acid, behenic acid, montanic acid, and hydroxystearic acid.
As the polybasic acid, a carboxylic acid having a dibasic acid or more is preferable. Polybasic acids include, for example, aliphatic dicarboxylic acids (such as malonic acid, succinic acid, adipic acid, pimelic acid, azelaic acid, and sebacic acid), aromatic dicarboxylic acids (such as phthalic acid and terephthalic acid), and fats. Cyclic dicarboxylic acids (such as cyclohexanedicarboxylic acid, cyclohexanedicarboxylic acid, and cyclohexylsuccinic acid) can be mentioned.
Examples of the diamine include ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, hexamethylenediamine, m-xylylenediamine, tolylenediamine, paraxylylenediamine, phenylenediamine, and isophoronediamine. ..
Specific examples of the component (D1) include ethylenediamine / stearic acid / sebacic acid polycondensate.

Examples of the component (D2) include those produced by reacting a carboxylic acid with a diamine. Here, as the carboxylic acid, it is preferable that the monocarboxylic acid is the main component from the viewpoint of not raising the melting point too much.
As the component (D2), ethylene bisstearic acid amide (melting point 145 ° C.), ethylene bishydroxystearic acid amide (melting point 145 ° C.), methylene bisstearic acid amide (melting point 142 ° C.), hexamethylene bisstearic acid amide (melting point 142 ° C.). 135 ° C), ethylene bisoleic acid amide (melting point 119 ° C), ethylene bisermic acid amide (melting point 120 ° C), hexamethylene bisoleic acid amide (melting point 110 ° C), N, N'-diorail adipate amide (melting point) 118 ° C.), N, N'-diorail sebacic acid amide (melting point 113 ° C.), stearic acid amide (melting point 101 ° C.), hydroxystearic acid amide (melting point 107 ° C.), and the like. Among these, ethylene bisstearic acid amide and methylene bisstearic acid amide can be mentioned from the viewpoint of further suppressing dripping. One of these may be used alone, or two or more thereof may be mixed and used.

In the present embodiment, the blending ratio of the component (D1) and the component (D2) is not particularly limited. The blending amount of the component (D1) is preferably 35% by mass or more and 90% by mass or less, and 40% by mass or more and 85% by mass, based on 100% by mass of the total blending amount of the component (D1) and the component (D2). It is more preferably 50% by mass or more and 80% by mass or less. When the blending amount of the component (D1) is at least the above lower limit, dripping can be suppressed more reliably. Further, when the blending amount of the component (D1) is not more than the above upper limit, the continuous printability can be further improved.

The component (D) may contain a chixo agent (component (D3)) other than the component (D1) and the component (D2) as long as it does not affect the object of the present invention. However, when this component (D3) is used, the blending amount thereof is preferably 30% by mass or less, more preferably 20% by mass or less, and 10% by mass with respect to 100% by mass of the component (D). It is particularly preferable that it is% or less.
Examples of the component (D3) include amides other than the components (D1) and (D2), hardened castor oil, kaolin, colloidal silica, organic bentonite, and glass frit. One of these may be used alone, or two or more thereof may be mixed and used.

The blending amount of the component (D) is preferably 1% by mass or more and 20% by mass or less, more preferably 3% by mass or more and 15% by mass or less, based on 100% by mass of the flux composition. It is particularly preferable that it is% or more and 12% by mass or less. When the blending amount is at least the above lower limit, sufficient thixophilicity can be obtained and sagging can be sufficiently suppressed. Further, if the blending amount is not more than the above upper limit, the tincture property is too high and printing failure does not occur.

[Other ingredients]
In addition to the components (A), (B), (C) and (D), the flux composition used in the present embodiment includes, if necessary, other additives and further resins. Can be added. Other additives include antifoaming agents, antioxidants, modifiers, matting agents, foaming agents and the like. 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 and the solder powder (E) 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 18% 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 15% 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), the obtained solder composition is used. It tends to be difficult to form a sufficient solder joint.

The solder composition of the present embodiment can sufficiently suppress dripping. Even if the solder composition is compatible with halogen-free printed wiring boards, it can be suppressed from dripping in the same manner as when a halogen-based activator is used. Therefore, it is particularly preferably used as a halogen-free solder composition. Can be done.
The halogen-free solder composition has a chlorine concentration of 900 mass ppm or less, a bromine concentration of 900 mass ppm or less, an iodine concentration of 900 mass ppm or less, and a halogen concentration of 1500 mass ppm or less. Is preferable. Examples of the halogen include fluorine, chlorine, bromine and iodine.
The chlorine concentration, bromine concentration and halogen concentration in the solder composition can be measured according to the method described in JEITA ET-7304A. Further, simply, it can be calculated from the compounding components of the solder composition and the compounding amount thereof.

[(E) component]
The (E) solder powder used in this embodiment is preferably composed of only lead-free solder powder, but may be leaded solder powder. 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, Sn-Ag-Cu, Sn-Cu, Sn-Ag-Bi, Sn-Bi, Sn-Ag-Cu-Bi, and Sn-Sb. , Sn-Zn-Bi, Sn-Zn, Sn-Zn-Al, Sn-Ag-Bi-In, Sn-Ag-Cu-Bi-In-Sb, In-Ag and the like. 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. Among the Sn—Ag—Cu-based solders, the solder having a low silver content has a melting point of 210 ° C. or higher and 250 ° C. or lower (more preferably 220 ° C. or higher and 240 ° C. or lower).

The average particle size of the component (E) 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. The following is even more preferable. 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.

[Manufacturing method of electronic board]
Next, the electronic substrate of this embodiment will be described.
The method for manufacturing an electronic substrate of the present embodiment is a method using the solder composition of the present embodiment described above, and includes a coating step, a mounting step, and a reflow step described below. According to the method for manufacturing an electronic circuit board of the present embodiment, electronic components can be mounted on an electronic circuit board (printed wiring board or the like) using the solder composition described above.

In the coating process, the solder composition is coated on the wiring board.
Examples of the coating apparatus used here include a screen printing machine, a metal mask printing machine, a dispenser, and a jet dispenser.
The thickness of the coating film (coating film thickness) can be appropriately set.

In the mounting process, electronic components are mounted on the solder composition.
Electronic components include discrete components (eg, transistors, diodes and resistors, etc.), chip components, BGA packages, chip size packages, and the like. Since the solder composition of the present embodiment can sufficiently suppress dripping, it is suitable for mounting a discrete component having a lead in which dripping is particularly problematic.
As an apparatus used in the mounting process, a known chip mount apparatus can be appropriately used.

In the reflow process, the solder powder is melted by heating the wiring board on which the electronic component is mounted, and the electronic component is joined to the electrode terminal.
As the apparatus used here, a known reflow furnace can be appropriately used.
The reflow conditions may be appropriately set according to the melting point of the solder. For example, when a Sn—Au—Cu based solder alloy is used, preheating is performed at a temperature of 150 to 180 ° C. (preferably 150 to 160 ° C.) for 60 to 120 seconds, and the peak temperature is 220 to 260 ° C. (preferably). , 230 to 250 ° C.).

[Modification example]
Further, the method for producing the solder composition and the electronic substrate of the present invention is 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 method for manufacturing an electronic board, the printed wiring board and the electronic component are bonded by a reflow process, but the method 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 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 resin A: hydrogenated acid-modified rosin, trade name "Pine Crystal KE-604", rosin resin B manufactured by Arakawa Chemical Industry Co., Ltd .: rosin ester, acid value 4-12 mgKOH / g, trade name "Haritac F85", Made by Harima Kasei Co., Ltd. ((B1) component)
Organic acid A: Malonic acid Organic acid B: Succinic acid Organic acid C: Glutaric acid ((B2) component)
Organic acid D: Dodecanedioic acid, manufactured by Ube Kosan Co., Ltd. Organic acid E: Adipic acid Organic acid F: Dimeric 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 ((B4) component)
Amine-based activator: 2-phenyl-4-methylimidazole, manufactured by Shikoku Kasei Kogyo Co., Ltd. (component (C))
Solvent A: Diethylene glycol mono2-ethylhexyl ether (EHDG), Nippon Emulsor Co., Ltd. Solvent B: Tetraethylene glycol dimethyl ether (MTEM), Toho Chemical Industry Co., Ltd. ((D1) component)
Chixo agent A: Polyamide (softening point 215 ° C), trade name "Light Amide WH-215", manufactured by Kyoeisha Chemical Co., Ltd. ((D2) component)
Tixo agent B: ethylene bisstearic acid amide (melting point 145 ° C.), trade name "Slipax E", manufactured by Nikka Trading Co., Ltd. ((D3) component)
Chixo agent C: Amide (softening point 130-190 ° C), product name "Tarren VA-79", Kyoeisha Chemical Co., Ltd. Chixo agent D: Hardened castor oil (softening point 85 ° C), product name "Himakou", manufactured by KF Trading Co., Ltd. (Ingredient (E))
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.

[Example 1]
Login-based resin A36.2% by mass, rosin-based resin B10% by mass, organic acid A2.3% by mass, organic acid D3% by mass, organic acid F5.6% by mass, halogen-based activator 0.2% by mass, amine-based Put 0.3% by mass of activator, 17.9% by mass of solvent A, 15.7% by mass of solvent B, 5.9% by mass of thixo agent A, and 2.9% by mass of thixo agent into a container, and use a planetary mixer. The mixture was mixed to obtain a flux composition.
Then, 12.4% by mass of the obtained flux composition and 87.6% 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 4]
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.
[Comparative Examples 1 to 5]
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.

<Evaluation of solder composition>
Evaluation of the solder composition (drop rate, printability (average filling volume ratio), viscosity change rate during continuous printing, total BGA void rate, wetting rate to dissimilar metals) was carried out by the following methods. The results obtained are shown in Table 1.
(1) Occurrence rate of sagging A substrate having a through hole (opening diameter: φ1.0 mm) was prepared. The solder composition was printed on this substrate by hand printing. Then, two lead parts (15 pins × 2) were inserted into the through holes and placed in an oven set at 180 ° C. for 60 seconds to heat them. At this time, a metal plate was placed under the substrate, and the number of solders that fell on the metal plate was counted.
Then, the dripping occurrence rate (unit:%) was calculated by the following formula.
(Dripping rate) = (Number of solders dropped on the metal plate) / (Total number of leads (pins)) x 100%
The dripping occurrence rate is preferably 10% or less, and more preferably 7% or less.
(2) Printability (average filling volume ratio)
The solder composition was continuously printed on 10 substrates using a printing machine (stencil printing, mask thickness: 120 μm). Then, the volume of the solder transferred through the opening having an opening diameter of φ0.24 mm was measured.
Then, the filling volume ratio (unit:%) was calculated by the following formula, and the average value was taken as the average filling volume ratio (unit:%).
(Filling volume ratio) = (Volume of solder transferred at an opening with an opening diameter of φ0.24 mm) / (Volume of an opening with an opening diameter of φ0.24 mm) x 100%
The average filling volume ratio is preferably 70% or more, and more preferably 73% or more.
(3) Viscosity change rate during continuous printing 500 g of the solder composition was placed on a stencil without openings and rolled with a squeegee for 8 hours. Rolling was performed under the conditions of a squeegee speed of 70 mm / s, a squeegee length of 350 mm, and a squeegee moving distance (one way) of 240 mm in an environment of a temperature of 25 ° C. and a humidity of 50%. At this time, the solder viscosities (unit: Pa · s) before and after rolling were measured according to the method described in JIS Z 3284-3 (2014).
Then, the viscosity change rate (unit:%) during continuous printing was calculated by the following formula.
(Viscosity change rate during continuous printing) = {(Solder viscosity after rolling)-(Solder viscosity before rolling)} / (Solder viscosity before rolling) x 100%
The viscosity change rate during continuous printing is preferably −20% or more and 20% or less.
(4) Total void ratio of BGA The solder composition was printed on the substrate using a printing machine (stencil printing, mask thickness: 120 μm). Then, a plurality of BGAs (number of pins: 228, pitch: 0.5 mm) were mounted on the substrate and heated in a reflow oven (oxygen concentration: 8000 ppm ± 500 ppm) to obtain an evaluation substrate. Next, X-rays were irradiated perpendicularly to the evaluation substrate, and the total area of the hollow portion in the soldered portion of the BGA was measured from the projected image.
Then, the total BGA void rate (unit:%) was calculated by the following formula, and the average value was expressed.
(Total void ratio of BGA) = (total area of hollow parts in the soldered part of BGA) / (area of soldered part of BGA) x 100%
The total BGA void ratio is preferably 5% or less, and more preferably 3% or less.
(5) Wetting rate on dissimilar metals Using a printing machine (stencil printing, mask thickness: 200 μm, opening diameter: φ6.5 mm) on a brass plate (size: 50 mm × 50 mm, thickness: 0.5 mm), The solder composition was printed. Then, it was heated in a reflow oven (oxygen concentration: 8000 ppm ± 500 ppm) to obtain an evaluation substrate. Next, the area where the solder was wet on the metal plate (no non-wetting or dewetting) was measured on the evaluation substrate.
Then, the wetting rate (unit:%) on dissimilar metals was calculated by the following formula.
(Wetting rate on dissimilar metals) = (Area where solder is wet on the metal plate) / (Printed area of solder composition) x 100%
The wetting rate to dissimilar metals is preferably 50% or more, and more preferably 60% or more.

As is clear from the results shown in Table 1, when the solder composition of the present invention (Examples 1 to 4) is used, the dripping occurrence rate, printability (average filling volume fraction), and viscosity during continuous printing are used. It was confirmed that the evaluation results of the rate of change, the total BGA void rate, and the wetting rate to dissimilar metals were all good. The amount of the halogen-based activator compounded in the solder composition is 248 mass ppm, which satisfies the halogen-free standard. Therefore, it was confirmed that the solder composition of the present invention is halogen-free and can sufficiently suppress dripping.

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 (4)

A flux composition containing (A) a rosin-based resin, (B) an activator, (C) a solvent and (D) a thixo agent, and (E) a solder powder are contained.
The component (B) contains a dicarboxylic acid (B1) having a molecular weight of 133 or less.
The component (D) contains (D1) an amide-based thiox agent having a melting point or softening point of 200 ° C. or higher, and (D2) an amide-based thiox agent having a melting point or softening point of 150 ° C. or lower.
The blending amount of the component (B1) is 0.1% by mass or more and 5% by mass or less with respect to 100% by mass of the flux composition.
The blending amount of the component (D) is 1% by mass or more and 20% by mass or less with respect to 100% by mass of the flux composition.
The total blending amount of the component (D1) and the component (D2) is more than 70% by mass with respect to 100% by mass of the component (D).
The blending amount of the component (D1) is 35% by mass or more and 90% by mass or less with respect to 100% by mass of the total blending amount of the component (D1) and the component (D2).
The chlorine concentration in the solder composition is 900 mass ppm or less, the bromine concentration is 900 mass ppm or less, the iodine concentration is 900 mass ppm or less, and the halogen concentration is 1500 mass ppm or less. A solder composition characterized by that. In the solder composition according to claim 1,
The component (D1) is formed by reacting a carboxylic acid with a diamine.
A solder composition, wherein the carboxylic acid contains an aliphatic monocarboxylic acid having 16 or more carbon atoms and a polybasic acid. In the solder composition according to claim 1 or 2.
A solder composition, wherein the component (D2) is ethylene bisstearic acid amide. A method for manufacturing an electronic substrate using the solder composition according to any one of claims 1 to 3.
The coating process of applying the solder composition onto the wiring board, and
The mounting process for mounting electronic components on the solder composition and
A method for manufacturing an electronic board, which comprises a reflow process for heating the wiring board on which the electronic component is mounted.