JP7634044B2 - Solder composition and electronic board - Google Patents

Description

The present invention relates to a flux composition, a solder composition, and an electronic substrate.

The solder composition is a mixture of solder powder and a flux composition (rosin-based resin, activator, solvent, etc.) kneaded into a paste (see Patent Document 1). In recent years, with consideration for environmental issues, there has been a demand for solder compositions that are halogen-free, with reduced halogen content, or that contain no halogen at all.

Patent No. 5887330

However, when using a halogen-free solder composition, it becomes difficult to remove the oxide film from the solder powder, which can result in the formation of solder balls.

The present invention aims to provide a flux composition, a solder composition, and an electronic substrate that can sufficiently suppress the occurrence of solder balls, even though they are halogen-free or non-halogen type.

According to the present invention, there are provided a flux composition, a solder composition, and an electronic board as described below.
[1] A composition comprising (A) a resin and (B) an activator,
The component (B) contains (B1) a compound having a quinoline skeleton.
Flux composition.
[2] The flux composition according to [1],
The component (B1) is a compound represented by the following general formula (1):
Flux composition.

(In general formula (1), X ¹ to X ⁷ are independently hydrogen, a hydroxyl group, an alkyl group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms, and any two of X ² to X ⁷ may form a ring.)

[3] The flux composition according to [1] or [2],
The component (B) further contains an azole (B2).
Flux composition.
[4] The flux composition according to any one of [1] to [3],
The component (B) further contains an organic acid (B3).
Flux composition.
[5] The flux composition according to any one of [1] to [4],
Further containing (C) a thixotropic agent,
Flux composition.
[6] A flux composition according to any one of [1] to [5] and (D) a solder powder,
Solder composition.
[7] The solder composition according to [6],
The alloy system of the (D) component is any one of a Sn-Bi system, a Sn-Ag-Bi system, a Sn-Ag-Sb-Bi system, a Sn-Bi-Sb-In system, a Sn-Bi-Sb-In-Ni-Co system, and a Sn-Bi-Sb-Cu-In-Ni-Co system;
Solder composition.
[8] The solder composition according to [6] or [7],
The alloy composition of the (D) component is any one of Sn-57Bi-1Ag, Sn-58Bi, Sn-35Bi-1Ag, Sn-45Bi-1.5Sb-0.5Ag, Sn-50Bi-1Sb-0.5In, Sn-50Bi-1Sb-0.5In-0.05Ni-0.1Co, and Sn-50Bi-1Sb-2Cu-0.5In-0.05Ni-0.1Co;
Solder composition.
[9] A soldered portion using the solder composition according to any one of [6] to [8].
Electronic board.

According to one aspect of the present invention, it is possible to provide a flux composition, a solder composition, and an electronic substrate that can sufficiently suppress the occurrence of solder balls, even though they are halogen-free or non-halogen type.

[Flux composition]
First, the flux composition according to the present embodiment will be described. The flux composition according to the present embodiment contains the components other than the solder powder in the solder composition, namely (A) a resin and (B) an activator, which will be described below. The (B) component contains (B1) a compound having a quinoline skeleton.

The reason why the flux composition according to the present embodiment can sufficiently suppress the occurrence of solder balls despite being a halogen-free or non-halogen type is not necessarily clear, but the inventors speculate as follows.
That is, among solder alloys, Sn-Bi solder alloys and the like have a tendency for Bi to oxidize, so that it is difficult to remove the oxide film of the solder powder, and it is also difficult to suppress reoxidation. For this reason, in the past, a halogen-based activator was added to the flux composition in addition to an organic acid and an amine-based activator. This promotes the removal of the oxide film and suppresses reoxidation, thereby suppressing the generation of solder balls. In addition, when a halogen-based activator is not used, it is not possible to remove the oxide film of Bi or suppress reoxidation, but the compound having a quinoline skeleton (B1) can remove the oxide film of Bi and suppress reoxidation. Although the reason for this is not necessarily clear, the present inventors speculate that the (B1) component forms a chelate on the metal surface after the solder oxide film is removed, thereby suppressing reoxidation. In addition, the (B1) component has the advantage of having less adverse effects on the stability and reliability of the solder composition compared to organic acids and other amine-based activators. The present inventors speculate that the above-mentioned effects of the present invention are achieved in the above manner.

[Component (A)]
Examples of the resin (A) used in this embodiment include rosin resins, acrylic resins, epoxy resins, and phenolic resins. These may be used alone or in combination of two or more. Among these, rosin resins or acrylic resins are preferred from the viewpoint of viscosity stability and the like.
Examples of the rosin-based resin include rosins and rosin-based modified resins. Examples of the 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. Examples of the hydrogenated rosin include fully hydrogenated rosin, partially hydrogenated rosin, and hydrogenated products of unsaturated organic acid-modified rosins (also called "hydrogenated acid-modified rosin"), which are modified rosins of unsaturated organic acids (aliphatic unsaturated monobasic acids such as (meth)acrylic acid, aliphatic unsaturated dibasic acids such as α,β-unsaturated carboxylic acids such as fumaric acid and maleic acid, and unsaturated carboxylic acids having aromatic rings such as cinnamic acid). These rosin-based resins may be used alone or in combination of two or more. Among these rosin-based resins, it is preferable to use fully hydrogenated rosin and hydrogenated acid-modified rosin, and it is more preferable to use fully hydrogenated rosin and hydrogenated acid-modified rosin in combination.
The acrylic resin is obtained by polymerizing at least one monomer such as acrylic acid, methacrylic acid, various esters of acrylic acid, various esters of methacrylic acid, crotonic acid, itaconic acid, maleic acid, maleic anhydride, esters of maleic acid, esters of maleic anhydride, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, vinyl chloride, and vinyl acetate. Acrylic resins are useful in that they can prevent cracks from occurring in the flux residue even in an environment with large temperature differences and large thermal shocks. Among these acrylic resins, acrylic resins obtained by polymerizing monomers containing methacrylic acid and a monomer having an alkyl group with 2 to 6 carbon atoms, and further acrylic resins obtained by polymerizing monomers containing methacrylic acid and a monomer having an alkyl group with 2 carbon atoms are preferred. Such acrylic resins are preferred in that they suppress the stickiness of the flux residue (flux solidified product) formed and have a good crack suppression effect.

The amount of component (A) is preferably 30% by mass or more and 70% by mass or less, more preferably 35% by mass or more and 60% by mass or less, and particularly preferably 40% by mass or more and 50% by mass or less, based on 100% by mass of the flux composition. If the amount of component (A) is equal to or more than the lower limit, oxidation of the copper foil surface of the soldering land can be prevented, making the surface more easily wetted by molten solder, improving so-called solderability, and sufficiently suppressing solder balls. Also, if the amount of component (A) is equal to or less than the upper limit, the amount of flux residue can be sufficiently suppressed.

[Component (B)]
The activator (B) used in this embodiment must contain a compound having a quinoline skeleton (B1). This component (B1) has the effect of suppressing the generation of solder balls. This component (B1) preferably has one or more hydroxyl groups in one molecule.
The component (B1) is preferably a compound represented by the following general formula (1).

In general formula (1), X ¹ to X ⁷ are independently hydrogen, a hydroxyl group, an alkyl group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms, and any two of X ² to X ⁷ may form a ring.
It is particularly preferred that X ¹ is hydrogen.
X ² to X ⁷ are preferably hydrogen, a hydroxyl group, a methyl group, or a methoxy group, and more preferably hydrogen or a methyl group.

(B1) Component includes 8-quinolinol, 2-methyl-8-quinolinol, and 5-methyl-8-quinolinol. These may be used alone or in combination of two or more.

The amount of the (B1) component is preferably 0.1% by mass or more and 10% by mass or less, more preferably 0.2% by mass or more and 8% by mass or less, even more preferably 0.8% by mass or more and 5% by mass or less, and particularly preferably 1.5% by mass or more and 2.5% by mass or less, based on 100% by mass of the flux composition. If the amount of the (B1) component is equal to or more than the lower limit, the effect of suppressing solder balls tends to be further improved, while if the amount is equal to or less than the upper limit, the insulating properties of the flux composition tend to be maintained.

It is preferable that the component (B) further contains an azole (B2), which acts to supplement the action of the component (B1) and improve the effect of suppressing the formation of solder balls.
Examples of the (B2) component include pyrrole compounds, imidazole compounds, pyrazole compounds, and triazole compounds. These may be used alone or in combination of two or more. Among these, from the viewpoint of solder melting property, imidazole compounds or triazole compounds are preferred. It is particularly preferred to use imidazole compounds and triazole compounds in combination.
Examples of the imidazole compound include 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, and 1,2-dimethylimidazole. Among these, 2-ethyl-4-methylimidazole is preferred.
Examples of the triazole compound include benzotriazole, 1,2,3-triazole, and 1,2,4-triazole. Among these, benzotriazole is preferred.

The amount of the (B2) component is preferably 0.1% by mass or more and 8% by mass or less, more preferably 0.5% by mass or more and 5% by mass or less, and particularly preferably 1% by mass or more and 3% by mass or less, relative to 100% by mass of the flux composition. If the amount of the (B2) component is equal to or more than the lower limit, the effect of suppressing solder balls tends to be further improved, while if the amount is equal to or less than the upper limit, the insulating properties of the flux composition tend to be maintained.

It is preferable that the component (B) further contains an organic acid (B3), which acts to supplement the action of the component (B1) and improve the effect of suppressing solder ball formation.
Examples of the component (B3) include other organic acids in addition to monocarboxylic acids and dicarboxylic acids. These may be used alone or in combination of two or more.
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, tuberculostearic acid, arachidic acid, behenic acid, lignoceric acid, and glycolic acid.
Examples of dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, fumaric acid, maleic acid, tartaric acid, and diglycolic acid. Among these, adipic acid or suberic acid is preferred from the viewpoint of activity, and suberic acid is particularly preferred.
Other organic acids include dimer acid, trimer acid, levulinic acid, lactic acid, acrylic acid, benzoic acid, salicylic acid, anisic acid, citric acid, and picolinic acid, etc. Among these, it is more preferable to use picolinic acid.
As the component (B3), it is preferable to use a plurality of organic acids in combination, and it is particularly preferable to use suberic acid and picolinic acid in combination.

The amount of the (B3) component is preferably 0.1% by mass or more and 12% by mass or less, more preferably 0.5% by mass or more and 8% by mass or less, and particularly preferably 1% by mass or more and 5% by mass or less, relative to 100% by mass of the flux composition. If the amount of the (B3) component is equal to or more than the lower limit, the effect of suppressing solder balls tends to be further improved, while if the amount is equal to or less than the upper limit, the insulating properties of the flux composition tend to be maintained.

The (B) component may further contain other activators (hereinafter also referred to as (B4) component) in addition to the (B1) to (B3) components, to the extent that the object of the present invention can be achieved. Examples of the (B4) component include halogen-based activators and amine-based activators other than the (B1) and (B2) components. However, the total amount of the (B1) to (B3) components is preferably 50% by mass or more, more preferably 70% by mass or more, and particularly preferably 90% by mass or more, relative to 100% by mass of the (B) component.

The amount of component (B) is preferably 0.5% by mass or more and 20% by mass or less, more preferably 1% by mass or more and 15% by mass or less, and particularly preferably 1.5% by mass or more and 10% by mass or less, relative to 100% by mass of the flux composition. If the amount of component (B) is equal to or more than the lower limit, the activation action tends to be improved, while if the amount is equal to or less than the upper limit, the insulating properties of the flux composition tend to be maintained.

[Component (C)]
From the viewpoint of printability, etc., the flux composition according to the present embodiment preferably further contains (C) a thixotropic agent. Examples of the thixotropic agent used here include hardened castor oil, amides, kaolin, colloidal silica, organic bentonite, and glass frit. These may be used alone or in combination of two or more.

The amount of component (C) is preferably 1% by mass or more and 20% by mass or less, and more preferably 2% by mass or more and 12% by mass or less, relative to 100% by mass of the flux composition. If the amount is less than the lower limit, thixotropy is not obtained and sagging tends to occur easily, while if the amount is more than the upper limit, the thixotropy is too high and printing defects tend to occur.

[solvent]
From the viewpoint of printability, the flux composition according to the present embodiment preferably further contains a solvent. As the solvent 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 more. Moreover, a glycol-based solvent is preferable.
Examples of such solvents include diethylene glycol, dipropylene glycol, triethylene glycol, hexylene glycol, hexyl diglycol, 1,5-pentanediol, methyl carbitol, butyl carbitol, 2-ethylhexyl diglycol (EHDG), octanediol, phenyl glycol, diethylene glycol monohexyl ether, tetraethylene glycol dimethyl ether, dibutyl maleic acid, etc. These solvents may be used alone or in combination of two or more.

When a solvent is used, the amount of the solvent is preferably 10% by mass or more and 75% by mass or less, and more preferably 20% by mass or more and 65% by mass or less, relative to 100% by mass of the flux composition. If the amount of the solvent is within the above range, the viscosity of the resulting solder composition can be appropriately adjusted to an appropriate range.

[Antioxidants]
From the viewpoint of solder melting property, the flux composition according to the present embodiment preferably further contains an antioxidant. As the antioxidant used here, a known antioxidant can be appropriately used. Examples of the antioxidant include sulfur compounds, hindered phenol compounds, and phosphite compounds. Among these, hindered phenol compounds are preferred.

Examples of hindered phenol compounds include pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionic acid][ethylene bis(oxyethylene)], N,N'-bis[2-[2-(3,5-di-tert-butyl-4-hydroxyphenyl)ethylcarbonyloxy]ethyl]oxamide, N,N'-bis{3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl}hydrazine, and 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate. Among these, it is preferable to use 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate from the viewpoint of further suppressing the formation of solder balls.

When an antioxidant is used, the amount of the antioxidant is preferably 0.1% by mass or more and 5% by mass or less, and more preferably 0.5% by mass or more and 3% by mass or less, relative to 100% by mass of the flux composition. If the amount of the antioxidant is equal to or more than the lower limit, the solder melting property tends to be improved, while if the amount is equal to or less than the upper limit, the insulating properties of the flux composition tend to be maintained.

[Other ingredients]
In addition to the (A), (B), and (C) components, the solvent, and the antioxidant, other additives and even other resins can be added to the flux composition used in this embodiment as necessary. Examples of other additives include antifoaming agents, modifiers, matting agents, and foaming agents. The 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.

[Solder Composition]
Next, the solder composition according to the present embodiment will be described. The solder composition according to the present embodiment contains the flux composition according to the present embodiment described above and the solder powder (D) described below.
The 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 particularly preferably 8% by mass or more and 12% by mass or less, relative to 100% by mass of the solder composition. When the amount of the flux composition is less than 5% by mass (when the amount of the solder powder exceeds 95% by mass), the flux composition as a binder is insufficient, so that it tends to be difficult to mix the flux composition and the solder powder. On the other hand, when the amount of the flux composition is more than 35% by mass (when the 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.

The solder composition according to the present embodiment can sufficiently suppress the occurrence of solder balls, even though it is a halogen-free or non-halogen type. Furthermore, even if the solder composition is compatible with halogen-free printed wiring boards, it can suppress the occurrence of solder balls at the same level as when a halogen-based activator is used, so it can be particularly preferably used as a halogen-free or non-halogen type solder composition.
The halogen-free solder composition preferably has a chlorine concentration of 900 ppm by mass or less (more preferably 100 ppm by mass or less, particularly preferably 0 ppm by mass), a bromine concentration of 900 ppm by mass or less (more preferably 100 ppm by mass or less, particularly preferably 0 ppm by mass), an iodine concentration of 900 ppm by mass or less (more preferably 100 ppm by mass or less, particularly preferably 0 ppm by mass), and a halogen concentration of 1500 ppm by mass or less (more preferably 300 ppm by mass or less, particularly preferably 0 ppm by mass). Examples of 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, or simply calculated from the components and their amounts in the solder composition.

[Component (D)]
The solder powder (D) used in this embodiment is preferably made of only lead-free solder powder, but may be lead-containing solder powder. The solder alloy in this solder powder preferably contains at least one selected from the group consisting of tin (Sn), copper (Cu), zinc (Zn), silver (Ag), antimony (Sb), lead (Pb), indium (In), bismuth (Bi), nickel (Ni), cobalt (Co) and germanium (Ge).
The solder alloy in the solder powder is preferably an alloy mainly composed of tin. More preferably, the solder alloy contains tin, silver and copper. Furthermore, 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, even when a solder alloy containing an additive element that is easily oxidized, such as antimony, bismuth and nickel, is used, the generation of voids can be suppressed.
Here, lead-free solder powder refers to a powder of a solder metal or alloy to which no lead is added. However, the presence of lead as an unavoidable impurity in the lead-free solder powder is permitted, but in this case, the amount of lead is preferably 300 ppm by mass or less.

Specific examples of alloy systems for lead-free solder powder include Sn-Ag-Cu systems, Sn-Cu systems, Sn-Ag systems, Sn-Bi systems, Sn-Ag-Bi systems, Sn-Ag-Sb-Bi systems, Sn-Ag-Cu-Bi systems, Sn-Ag-Cu-Ni systems, Sn-Ag-Cu-Bi-Sb systems, Sn-Ag-Bi-In systems, and Sn-Ag-Cu-Bi-In-Sb systems.
The flux composition according to the present embodiment can sufficiently suppress the occurrence of solder balls even in solder alloys such as Sn-Bi. Therefore, when using the component (D) of a solder alloy containing Bi, the effect of the flux composition according to the present embodiment can be particularly exhibited. Specific solder alloys include Sn-Bi, Sn-Ag-Bi, Sn-Ag-Sb-Bi, Sn-Bi-Sb-In, Sn-Bi-Sb-In-Ni-Co, and Sn-Bi-Sb-Cu-In-Ni-Co. Among these alloys, Sn-Bi, Sn-Ag-Bi, or Sn-Ag-Sb-Bi are preferred. Specific solder alloy compositions include Sn-57Bi-1Ag, Sn-58Bi, Sn-35Bi-1Ag, Sn-45Bi-1.5Sb-0.5Ag, Sn-50Bi-1Sb-0.5In, Sn-50Bi-1Sb-0.5In-0.05Ni-0.1Co, and Sn-50Bi-1Sb-2Cu-0.5In-0.05Ni-0.1Co. Among these alloy compositions, Sn-57Bi-1Ag, Sn-58Bi, Sn-35Bi-1Ag, and Sn-45Bi-1.5Sb-0.5Ag are preferred.

The average particle diameter of component (D) is usually 1 μm or more and 40 μm or less, but from the viewpoint of being compatible with electronic boards with narrow pitches of solder pads, it is more preferably 1 μm or more and 35 μm or less, even more preferably 2 μm or more and 35 μm or less, and particularly preferably 3 μm or more and 32 μm or less. The average particle diameter can be measured by a dynamic light scattering type particle size measuring device.

[Method of manufacturing solder composition]
The solder composition of the present embodiment can be produced by blending the above-described flux composition and the above-described (D) solder powder in the above-described predetermined ratio, and stirring and mixing them.

[Electronic board]
Next, the electronic board according to the present embodiment will be described. The electronic board according to the present embodiment is characterized by having a soldered portion using the solder composition according to the present embodiment. The electronic board according to the present embodiment can be manufactured by mounting electronic components on an electronic board (such as a printed wiring board) using the solder composition.
Examples of the coating device used here include a screen printer, a metal mask printer, a dispenser, and a jet dispenser.
In addition, electronic components can be mounted on an electronic board by a reflow process in which electronic components are placed on the solder composition applied by an application device and heated under specified conditions in a reflow furnace to mount the electronic components on a printed wiring board.

In the reflow process, an electronic component is placed on the solder composition and heated in a reflow furnace under predetermined conditions. This reflow process allows a sufficient solder joint to be formed 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 90°C or more and 130°C or less, more preferably 100°C or more and 120°C or less. The preheat time is preferably 40 seconds or more and 120 seconds or less, more preferably 60 seconds or more and 100 seconds or less. The peak temperature is preferably 160°C or more and 190°C or less, more preferably 180°C or more and 190°C or less. The holding time of the temperature of 140°C or more is preferably 30 seconds or more and 120 seconds or less, more preferably 80 seconds or more and 120 seconds or less.

Furthermore, the flux composition, the solder composition, and the electronic board according to the present embodiment are not limited to the above-described embodiment, and modifications and improvements within the scope of the present invention that can achieve the object of the present invention 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 thereto. For example, instead of the reflow process, the printed wiring board and the electronic component may be bonded by a process (laser heating process) of heating the solder composition using laser light. In this case, the laser light source is not particularly limited and can be appropriately adopted according to the wavelength that matches the absorption band of the metal. Examples of the laser light source include solid lasers (ruby, glass, YAG, etc.), semiconductor lasers (GaAs, InGaAsP, etc.), liquid lasers (dye, etc.), and gas lasers (He-Ne, Ar, CO ₂ , and excimer, etc.).

The present invention will now 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 the examples and comparative examples are shown below.
(Component (A))
Rosin-based resin A: acrylic acid modified hydrogenated rosin, product name "Pine Crystal KE-604", manufactured by Arakawa Chemical Industries, Ltd. Rosin-based resin B: fully hydrogenated rosin, product name "Foral AX", manufactured by Rika Finetech Co., Ltd. (component (B1))
Quinoline compound A: 8-quinolinol Quinoline compound B: 2-methyl-8-quinolinol (component (B2))
Azole A: Benzotriazole Azole B: 2-ethyl-4-methylimidazole, trade name "2E4MZ", Shikoku Chemical Industry Co., Ltd. (component (B3))
Organic acid A: Picolinic acid Organic acid B: Suberic acid (component (C))
Thixotropic agent A: Trade name "Slipax ZHH", manufactured by Nippon Kasei Co., Ltd. Thixotropic agent B: Trade name "Himako", manufactured by KF Trading Co., Ltd. (other ingredients)
Solvent: diethylene glycol mono-2-ethylhexyl ether (2-ethylhexyl diglycol (EHDG), boiling point: 272°C), antioxidant A manufactured by Nippon Nyukazai Co., Ltd.: N,N'-bis{3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl}hydrazine, trade name "Irganox MD-1024", antioxidant B manufactured by BASF: 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate, trade name "Sumilizer GS", manufactured by Sumitomo Chemical Co., Ltd. (component (D))
Solder powder A: alloy composition is Sn-57Bi-1Ag, particle size distribution is 20 to 38 μm
Solder powder B: alloy composition is Sn-45Bi-1.5Sb-0.5Ag, particle size distribution is 20 to 38 μm
Solder powder C: alloy composition is Sn-58Bi, particle size distribution is 20 to 38 μm
Solder powder D: alloy composition is Sn-50Bi-1Sb-0.5In, particle size distribution is 20 to 38 μm
Solder powder E: Alloy composition is Sn-50Bi-1Sb-0.5In-0.05Ni-0.1Co, particle size distribution is 20 to 38 μm
Solder powder F: alloy composition is Sn-50Bi-1Sb-2Cu-0.5In-0.05Ni-0.1Co, particle size distribution is 20 to 38 μm

[Example 1]
25 mass % of rosin-based resin A, 21 mass % of rosin-based resin B, 2 mass % of quinoline compound A, 0.5 mass % of azole A, 1 mass % of azole B, 1 mass % of organic acid A, 3 mass % of organic acid B, 37 mass % of solvent, 2 mass % of antioxidant A, 5 mass % of thixotropic agent A, and 2.5 mass % of thixotropic agent B were charged into a container and mixed using a planetary mixer to obtain a flux composition.
Thereafter, 10.6% by mass of the obtained flux composition, 0.6% by mass of the solvent, and 88.8% by mass of the solder powder A (total of 100% by mass) were placed in a container and mixed with a planetary mixer to prepare a solder composition.

[Examples 2 to 15]
A solder composition was obtained in the same manner as in Example 1, except that the materials were mixed according to the composition shown in Table 1.
[Comparative Example 1]
A solder composition was obtained in the same manner as in Example 1, except that the materials were mixed according to the composition shown in Table 1.

<Evaluation of Solder Composition>
The solder compositions were evaluated (solder ball test, pin-to-pin ball test) by the following method. The results are shown in Table 1.
(1) Solder ball test The solder ball test was performed with reference to the description in IPC TM-650 2.4.43. Specifically, a solder composition was printed in a circular shape with a diameter of 6.5 mm on a ceramic substrate with a thickness of 0.6 mm to 0.8 mm using a metal screen to prepare a sample. The above sample was placed on a hot plate set at 180°C, melted, and then removed 5 seconds later, held horizontally, and cooled. The number and size of solder balls in the solder were observed using a 20x microscope, and judged according to the following criteria. Note that "Preferred", "Acceptable", "Unacceptable;Clusters", and "Unacceptable" are in accordance with the evaluation criteria described in IPC TM-650 2.4.43.
◎: "Preferred", flux residue or almost no solder balls in the vicinity (only a few).
◯: "Acceptable", solder balls are scattered in or around the flux residue. However, the solder balls are not densely packed.
×: "Unacceptable;Clusters", solder balls are densely formed in the flux residue.
XX: "Unacceptable", solder balls were continuously generated all around the flux residue.
(2) Ball between pins On a board having 80 copper pads of 0.4 mm x 3.0 mm at 0.8 mm intervals, a metal mask having a corresponding pattern was used to print the solder composition at a printing speed of 50 mm/sec and a printing pressure of 0.2 N. The solder composition was then melted in a reflow furnace (manufactured by Tamura Manufacturing Co., Ltd.) and soldered to prepare a test board. The test board was observed with a magnifying glass to measure the number of solder balls between the pins (number of balls between pins, unit: pieces/pin), and the ball between pins was evaluated according to the following criteria. The reflow conditions were a preheat temperature of 100 to 120°C (about 80 seconds), a time at a temperature of 140°C or higher for about 100 seconds, and a peak temperature of about 185°C.
⊚: The number of balls between pins is less than 4.
◯: The number of balls between the pins is 4 or more and less than 10.
Δ: The number of balls between the pins is 10 or more and less than 15.
×: The number of balls between the pins is 15 or more.

As is clear from the results shown in Table 1, it was confirmed that the solder compositions of the present invention (Examples 1 to 15) gave good results in all of the solder ball tests and inter-pin ball tests. Note that the solder compositions of Examples 1 to 15 do not contain a halogen-based activator, and are therefore non-halogen type solder compositions.
Therefore, it was confirmed that the solder composition of the present invention can sufficiently suppress the occurrence of solder balls, even though it is a halogen-free or non-halogen type.

The flux composition and solder composition of the present invention can be suitably used as a technique for mounting electronic components on electronic substrates such as printed wiring boards for electronic devices.

Claims (7)

A solder composition comprising a flux composition and (D) a solder powder,
The flux composition comprises: (A) a resin; and (B) an activator;
The component (B) contains (B1) a compound having a quinoline skeleton ,
The alloy system of the (D) component is any one of a Sn-Bi system, a Sn-Ag-Bi system, a Sn-Ag-Sb-Bi system, a Sn-Bi-Sb-In system, a Sn-Bi-Sb-In-Ni-Co system, and a Sn-Bi-Sb-Cu-In-Ni-Co system;
Solder composition . The solder composition according to claim 1,
The component (B1) is a compound represented by the following general formula (1):
Solder composition .

(In general formula (1), X ¹ to X ⁷ are independently hydrogen, a hydroxyl group, an alkyl group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms, and any two of X ² to X ⁷ may form a ring.) The solder composition according to claim 1 or 2,
The component (B) further contains an azole (B2).
Solder composition . The solder composition according to claim 1 or 2,
The component (B) further contains an organic acid (B3).
Solder composition . The solder composition according to claim 1 or 2,
The flux composition further contains (C) a thixotropic agent.
Solder composition . The solder composition according to claim 1 or 2 ,
The alloy composition of the component (D) is Sn-57Bi-1Ag, Sn-58Bi, Sn-35Bi-1Ag, Sn-45Bi-1.5Sb-0.5Ag, Sn-50Bi-1Sb-0.5Ag,
.5In, Sn-50Bi-1Sb-0.5In-0.05Ni-0.1Co, and Sn-50Bi-1Sb-2Cu-0.5In-0.05Ni-0.1Co;
Solder composition. A soldered portion comprising the solder composition according to claim 1 or 2 .
Electronic board.