Flux composition, solder composition, and electronic substrate

Abstract

To provide a flux composition that exhibits excellent removability of flux residues with an aqueous cleaning agent, prevents copper foil corrosion, and demonstrates superior printability.SOLUTION: A flux composition comprising (A) a nonionic surfactant, (B) an activator, and (C) a solvent, wherein the component (A) is a nonionic surfactant having an HLB value of more than 11 and a solidification point of less than 45°C, and the component (C) comprises (C1) triethylene glycol monobutyl ether.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a flux composition, a solder composition, and an electronic substrate. [Background technology]

[0002] The solder composition is a paste-like mixture obtained by kneading a solder powder with a flux composition (rosin-based resin, an activator, a solvent, etc.) (see Patent Document 1). When soldering is performed using a solder composition, flux residue remains around the joint after soldering. This residue contains activator components, etc., and there is a concern that moisture may penetrate into the residue distributed across the electrodes due to condensation, which may cause ion migration. Furthermore, the presence of flux residue on the surface may cause defects in the molding or coating process or poor bonding in wire bonding. Therefore, it is desirable to remove this residue by cleaning after joining.

[0003] Conventionally, cleaning has been carried out using cleaning agents whose main component is organic solvents with high cleaning power. However, because these agents contain a large amount of solvent, regulations have been strengthened from the viewpoints of preventing water pollution, fires, and air pollution, as well as from the viewpoint of occupational health. Therefore, in recent years, the amount of solvent used has been reduced and water-based cleaning chemicals, which are primarily composed of water, have come to be used. Also, the use of water as a cleaning chemical has become more and more required. Therefore, the cleaning performance of flux residues has tended to deteriorate due to the change in cleaning chemical components, which has become a problem. Furthermore, if a water-soluble component is used as a component of the flux composition, the paste properties tend to deteriorate due to moisture absorption, precipitation of some components, etc., and the printability of the solder composition tends to deteriorate. Furthermore, depending on the type of water-soluble component, copper foil corrosion tends to occur more easily. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5887330 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a flux composition, a solder composition, and an electronic substrate that have excellent cleaning properties for flux residues with an aqueous cleaner, can prevent copper foil corrosion, and have excellent printability. [Means for solving the problem]

[0006] According to the present invention, there are provided the following flux composition, solder composition, and electronic substrate. [1] A flux composition comprising (A) a nonionic surfactant, (B) an activator, and (C) a solvent, The component (A) is a nonionic surfactant having an HLB value of more than 11 and a freezing point of less than 45°C, The component (C) contains (C1) triethylene glycol monobutyl ether. Flux composition. [2] In the flux composition according to [1], The component (C) further contains (C2) triethylene glycol monoethyl ether. Flux composition. [3] The flux composition according to [1] or [2], The component (B) contains an organic acid (B1) and an amine surfactant (B3). Flux composition. [4] A flux composition according to any one of [1] to [3] and (D) a solder powder. Solder composition. [5] A soldered portion using the solder composition according to [4] is provided. Electronic board. [Effects of the Invention]

[0007] According to one aspect of the present invention, it is possible to provide a flux composition, a solder composition, and an electronic substrate that have excellent cleaning properties for flux residues with an aqueous cleaner, can prevent copper foil corrosion, and have excellent printability. DETAILED DESCRIPTION OF THE INVENTION

[0008] [Flux composition] First, the flux composition according to this embodiment will be described. The flux composition according to this embodiment contains the components other than the solder powder in the solder composition: (A) a nonionic surfactant, (B) an activator, and (C) a solvent, which will be described below. Furthermore, component (A) is a nonionic surfactant with an HLB value of greater than 11 and a freezing point of less than 45°C. Furthermore, component (C) contains (C1) triethylene glycol monobutyl ether.

[0009] According to this embodiment, a flux composition having excellent cleaning properties for flux residues with an aqueous cleaner and excellent printability can be obtained. The reason for this is not entirely clear, but the inventors speculate as follows. That is, in this embodiment, the nonionic surfactant (A) used is a nonionic surfactant with an HLB value of more than 11 and a freezing point of less than 45°C. This component (A) is easily soluble in water, which improves the cleaning performance of flux residues with aqueous cleaners. Furthermore, this component (A) is less likely to cause problems such as copper foil corrosion. On the other hand, component (A) is prone to problems such as moisture absorption, which may adversely affect printability. However, by using this component (A) in combination with (C1) triethylene glycol monobutyl ether, surprisingly, adverse effects on printability can be suppressed. The inventors believe that the effects of the present invention are achieved in this way.

[0010] [Component (A)] The nonionic surfactant (A) used in this embodiment is a nonionic surfactant having an HLB value of more than 11 and a freezing point of less than 45° C. These surfactants may be used alone or in combination of two or more. If the HLB value of component (A) is 11 or less, the cleaning ability for flux residue will be insufficient. Furthermore, in some cases, there is a risk of copper foil corrosion. From the same viewpoint, the HLB value of component (A) is preferably 11.2 or more and 18 or less, and more preferably 11.4 or more and 17 or less. If the freezing point of component (A) is 45° C. or higher, the cleaning ability for flux residue will be insufficient. From the same viewpoint, the freezing point of component (A) is preferably 42° C. or lower, more preferably 40° C. or lower, and particularly preferably 35° C. or lower. The freezing point can be measured, for example, by the method described in JIS K0065.

[0011] Examples of component (A) include ester-type nonionic surfactants and ether-type nonionic surfactants. Among these, ether-type nonionic surfactants are preferred from the viewpoint of cleaning properties. Examples of component (A) include polyoxyethylene monostearate (HLB value 11.6, freezing point 35°C), polyoxyethylene cetyl ether (HLB value 14.1, freezing point 33°C), and polyoxyethylene lauryl ether (HLB value 16.8, freezing point 40°C).

[0012] The blending amount of component (A) is preferably 20% by mass or more and 50% by mass or less, and more preferably 28% by mass or more and 40% by mass or less, based on 100% by mass of the flux composition. When the blending amount of component (A) is equal to or more than the lower limit, the function as a binder component can be ensured. Furthermore, when the blending amount of component (A) is equal to or less than the upper limit, adverse effects on printability are sufficiently small.

[0013] [(B) Component] Examples of the (B) activator used in this embodiment include (B1) organic acids, (B2) halogen-based activators, and (B3) amine-based activators. These may be used alone or in combination of two or more. From the viewpoint of activation, it is preferable to use (B1) organic acids and (B3) amine-based activators in combination. Note that (B2) halogen-based activators may also be used in combination.

[0014] Examples of the component (B1) include monocarboxylic acids, dicarboxylic acids, and other organic acids. Monocarboxylic acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, 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, fumaric acid, maleic acid, tartaric acid, and diglycolic acid. Of these, glutaric acid or adipic acid is 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.

[0015] The blending amount of component (B1) is preferably 0.1% by mass or more and 5% by mass or less, and more preferably 0.5% by mass or more and 4% by mass or less, based on 100% by mass of the flux composition. If the blending amount of component (B1) is equal to or more than the lower limit, solderability tends to be improved, while if it is equal to or less than the upper limit, the insulating properties of the flux composition tend to be maintained.

[0016] Examples of the component (B2) include halogenated alcohols and halogenated carboxyl compounds. Examples of halogenated alcohols include brominated alcohols such as 2,3-dibromopropanol, 2,3-dibromobutanediol, trans-2,3-dibromo-2-butene-1,4-diol, 1,4-dibromo-2-butanol, and tribromoneopentyl alcohol, chlorinated alcohols such as 1,3-dichloro-2-propanol and 1,4-dichloro-2-butanol, fluorinated alcohols such as 3-fluorocatechol, and other similar compounds. Examples of halogenated carboxyl compounds include iodinated carboxyl compounds such as 2-iodobenzoic acid, 3-iodobenzoic acid, 2-iodopropionic acid, 5-iodosalicylic acid, and 5-iodoanthranilic acid, chlorinated carboxyl compounds such as 2-chlorobenzoic acid and 3-chloropropionic acid, brominated carboxyl compounds such as 2,3-dibromopropionic acid, 2,3-dibromosuccinic acid, and 2-bromobenzoic acid, and other similar compounds.

[0017] When component (B2) is used, its amount is preferably 0.1 to 5% by mass, and more preferably 0.5 to 4% by mass, based on 100% by mass of the flux composition. If the amount of component (B2) is equal to or greater than the lower limit, solderability tends to be improved, while if it is equal to or less than the upper limit, it is preferable from the viewpoint of making the solder composition halogen-free.

[0018] Examples of component (B3) include N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine and N,N,N',N'-tetrakis(2-hydroxyethyl)ethylenediamine. Of these, N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine is preferred from the viewpoint of improving solder wettability.

[0019] The blending amount of component (B3) is preferably 0.1% by mass to 20% by mass, more preferably 1% by mass to 15% by mass, and particularly preferably 5% by mass to 12% by mass, based on 100% by mass of the flux composition. If the blending amount of component (B3) is equal to or greater than the lower limit, solderability tends to be improved, while if it is equal to or less than the upper limit, the storage stability of the flux composition tends to be maintained.

[0020] The blending amount of component (B) is preferably 1% by mass or more and 25% by mass or less, more preferably 3% by mass or more and 20% by mass or less, and particularly preferably 5% by mass or more and 18% by mass or less, based on 100% by mass of the flux composition. If the blending amount of component (B) is equal to or more than the lower limit, the activation effect tends to be improved, while if it is equal to or less than the upper limit, the insulating properties of the flux composition tend to be maintained.

[0021] [(C) component] The solvent (C) used in this embodiment must contain triethylene glycol monobutyl ether (C1) (melting point -48°C, boiling point 271°C). Component (C1) ensures the printability of the solder composition even when component (A) is used. In this specification, the boiling point refers to the boiling point at 1013 hPa.

[0022] The blending amount of component (C1) is preferably 10% by mass or more and 50% by mass or less, more preferably 15% by mass or more and 45% by mass or less, and particularly preferably 20% by mass or more and 40% by mass or less, based on 100% by mass of the flux composition. When the blending amount of component (C1) is equal to or greater than the lower limit, the printability of the solder composition can be further improved. On the other hand, when the blending amount of component (C1) is equal to or less than the upper limit, adverse effects on other properties are minimized.

[0023] Preferably, component (C) further contains (C2) triethylene glycol monoethyl ether (melting point -44°C or lower, boiling point 249°C), which further improves the printability of the solder composition. When component (C2) is used, its amount is preferably 5% by mass to 30% by mass, more preferably 7% by mass to 25% by mass, and particularly preferably 8% by mass to 20% by mass, based on 100% by mass of the flux composition. When the amount of component (C2) is within the above range, the printability of the solder composition can be further improved without deteriorating other physical properties.

[0024] The component (C) may contain a solvent (component (C3)) other than the components (C1) and (C2) as long as the object of the present invention can be achieved. Examples of component (C3) include diethylene glycol monohexyl ether (hexyl diglycol, DEH, melting point -40°C, boiling point 259°C), 1,4-butanediol (melting point 19°C, boiling point 228°C), 1,6-hexanediol (melting point 42°C, boiling point 250°C), 2,2-dimethyl-1,3-propanediol (melting point 128°C, boiling point 210°C), and 2,5-dimethyl-2,5-hexanediol (melting point 89°C, boiling point 214°C). These may be used alone or in combination of two or more.

[0025] The total amount of the components (C1) and (C2) is preferably 70% by mass or more, more preferably 80% by mass or more, and particularly preferably 90% by mass or more, based on 100% by mass of the component (C).

[0026] The blending amount of component (C) is preferably 10% by mass to 70% by mass, more preferably 20% by mass to 65% by mass, and particularly preferably 30% by mass to 60% by mass, based on 100% by mass of the flux composition. If the blending amount of the solvent is within the above range, the viscosity of the resulting solder composition can be appropriately adjusted to an appropriate range.

[0027] [Thixotropic agent] The flux composition according to this embodiment may further contain a thixotropic agent to suppress sagging during printing or heating. Known thixotropic agents can be used as appropriate. Examples of thixotropic agents include hydrogenated castor oil, amides, kaolin, colloidal silica, organic bentonite, and glass frit. Among these, amides are preferred from the viewpoint of suppressing sagging. These agents may be used alone or in combination of two or more.

[0028] When a thixotropic agent is used, its blending amount is preferably 2% by mass or more and 20% by mass or less, and more preferably 3% by mass or more and 15% by mass or less, relative to 100% by mass of the flux composition. If the blending amount is above the lower limit, sufficient thixotropy is obtained and sagging tends to be suppressed. On the other hand, if the blending amount is below the upper limit, the thixotropy is not too high and printing defects tend to be less likely to occur.

[0029] [Antioxidants] The flux composition according to the present embodiment may further contain an antioxidant from the viewpoint of solder melting property, etc. 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.

[0030] Examples of hindered phenol compounds include pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], ethylene bis(oxyethylene)(3-tert-butyl-4-hydroxy-5-methylbenzenepropanoate), N,N'-bis[2-[2-(3,5-di-tert-butyl-4-hydroxyphenyl)ethylcarbonyloxy]ethyl]oxamide, and N,N'-bis{3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl}hydrazine.

[0031] When an antioxidant is used, the blending amount thereof is preferably 0.1% by mass or more and 5% by mass or less relative to 100% by mass of the flux composition. If the blending amount of the antioxidant is equal to or more than the lower limit, the solder melting property tends to be improved, while if it is equal to or less than the upper limit, the insulating property of the flux composition tends to be maintained.

[0032] [Other ingredients] In addition to the components (A), (B), and (C), the thixotropic agent, and the antioxidant, other additives may be added to the flux composition used in this embodiment as needed. Examples of such additives include imidazole compounds, antifoaming agents, modifiers, matting agents, and foaming agents. The amount of these additives added is preferably 0.01% by mass or more and 5% by mass or less based on 100% by mass of the flux composition.

[0033] [Solder composition] Next, the solder composition according to this embodiment will be described. The solder composition according to this embodiment contains the flux composition according to this 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 20% by mass or less, and particularly preferably 8% by mass or more and 15% by mass or less, relative to 100% by mass of the solder composition. If the amount of the flux composition is less than 5% by mass (if the amount of the solder powder exceeds 95% by mass), there will be an insufficient amount of flux composition as a binder, making it difficult to mix the flux composition and the solder powder. On the other hand, if the amount of the flux composition is more than 35% by mass (if the amount of the solder powder is less than 65% by mass), it will be difficult to form a satisfactory solder joint when using the resulting solder composition.

[0034] [(D) component] The solder powder (D) used in this embodiment is preferably made of lead-free solder powder alone, but may also 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 this solder powder is preferably an alloy containing tin as a main component, and more preferably contains tin, silver, and copper. Furthermore, this solder alloy may contain at least one of antimony, bismuth, and nickel as an additive element. Here, lead-free solder powder refers to a powder of solder metal or alloy to which no lead is added. Although the presence of lead as an unavoidable impurity in lead-free solder powder is permitted, in this case, the amount of lead is preferably 300 ppm by mass or less.

[0035] 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-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.

[0036] The average particle size of component (D) is usually 1 μm or more and 40 μm or less, but from the viewpoint of compatibility with electronic boards with narrow solder pad pitches, 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 size can be measured using a dynamic light scattering particle size analyzer.

[0037] [Method for manufacturing solder composition] The solder composition of this embodiment can be produced by blending the above-described flux composition and the above-described (D) solder powder in the predetermined ratio, and stirring and mixing them.

[0038] [Electronic board] Next, the electronic substrate according to this embodiment will be described. The electronic substrate according to this embodiment is characterized by having a soldered portion using the solder composition according to this embodiment. The electronic substrate according to this embodiment can be manufactured by mounting electronic components on an electronic substrate (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. Furthermore, electronic components can be mounted on an electronic board by a reflow process in which an electronic component is placed on the solder composition applied by an application device and heated under predetermined conditions in a reflow furnace to mount the electronic component on a printed wiring board.

[0039] 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 for a sufficient solder bond 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 set appropriately depending on 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 higher and 120 seconds or lower. 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. Furthermore, the holding time at a temperature of 220°C or higher is preferably 20 seconds or higher and 60 seconds or lower.

[0040] After the reflow process, it is preferable to carry out a cleaning process in which flux residue on the electronic substrate is cleaned using a water-based cleaner. As the cleaning method, a dipping method, a jet method, etc. can be used. For example, in the immersion method, the electronic substrate is immersed in a water-based cleaning agent, and ultrasonic waves may be applied at this time. Known water-based cleaning agents for flux residue can be used. Here, "water-based" refers to those whose main component is water (50% by mass or more). Commercially available products include "VIGON US" manufactured by Zestron Japan Co., Ltd. and "Pine Alpha ST-180K" manufactured by Arakawa Chemical Industries Co., Ltd. From the environmental viewpoint, the aqueous cleaner is preferably water. The temperature of the aqueous cleaner during cleaning is, for example, 20°C or higher and 70°C or lower. The cleaning time is, for example, 1 minute or more and 10 minutes or less. After cleaning with an aqueous cleaner, rinsing may be performed. The rinsing conditions are not particularly limited, and the rinsing should be performed with water at a temperature of 20°C to 50°C for 0.5 to 5 minutes. Rinsing may be performed two or more times.

[0041] Furthermore, the flux composition, solder composition, and electronic substrate according to the present embodiment are not limited to the above-described embodiment, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention. For example, in the electronic substrate, the printed wiring board and electronic components are bonded by a reflow process, but this is not limiting. For example, instead of the reflow process, the printed wiring board and electronic components may be bonded by a process of heating the solder composition using laser light (laser heating process). In this case, the laser light source is not particularly limited and can be appropriately selected depending on the wavelength that matches the absorption band of the metal. Examples of laser light sources include solid-state lasers (ruby, glass, YAG, etc.), semiconductor lasers (GaAs, InGaAsP, etc.), liquid lasers (dye, etc.), and gas lasers (He-Ne, Ar, CO2, excimer, etc.). [Example]

[0042] 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 listed below. (Component (A)) Nonionic surfactant A: Polyoxyethylene monostearate (ester type, HLB value 11.6, freezing point 35°C), product name "Nonion S-4", manufactured by NOF Corporation Nonionic surfactant B: Polyoxyethylene cetyl ether (ether type, HLB value 14.1, freezing point 33°C), product name "Nonion P-213", manufactured by NOF Corporation Nonionic surfactant C: Polyoxyethylene lauryl ether (ether type, HLB value 16.8, freezing point 40°C), product name "Nonion K-220", manufactured by NOF Corporation (Other ingredients) Nonionic surfactant D: Polyoxyethylene stearyl ether (ether type, HLB value 4.9, freezing point 40°C), product name "Nonion S-202", manufactured by NOF Corporation Nonionic surfactant E: Polyoxyethylene-tallow alkylamine (ether amine type, HLB value 5, freezing point 25°C), product name "Nymeen T2-202", manufactured by NOF Corporation Nonionic surfactant F: Polyoxyethylene-stearylamine (ether amine type, HLB value 5, freezing point 45°C), product name "Nymeen S-202", manufactured by NOF Corporation Nonionic surfactant G: Sorbitan monopalmitate (ester type, HLB value 6.7, freezing point 45°C or higher), product name "Nonion PP-40R", manufactured by NOF Corporation Nonionic surfactant H: Polyoxyethylene stearyl ether (ether type, HLB value 10.7, freezing point 33°C), product name "Nonion S-207", manufactured by NOF Corporation Nonionic surfactant I: Polyoxyethylene stearyl ether (ether type, HLB value 15.3, freezing point 45°C), product name "Nonion S-220", manufactured by NOF Corporation Nonionic surfactant J: Polyethylene glycol distearate (diester type, HLB value 19, freezing point 60°C), product name "Nonion DS-60NH", manufactured by NOF Corporation ((B1) component) Organic acid A: Glutaric acid Organic acid B: Adipic acid ((B2) component) Halogen-based activator: trans-2,3-dibromo-2-butene-1,4-diol (Component (B3)) Amine surfactant: N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine ((C1) component) Solvent A: Triethylene glycol monobutyl ether (BTG, melting point -48°C, boiling point 271°C) ((C2) component) Solvent B: Triethylene glycol monoethyl ether (melting point -44°C or less, boiling point 249°C), trade name "Himol™", manufactured by Toho Chemical Industry Co., Ltd. ((C3) component) Solvent C: Diethylene glycol monohexyl ether (hexyl diglycol, DEH, melting point -40°C, boiling point 259°C) Solvent D: 1,4-butanediol (melting point 19°C, boiling point 228°C) Solvent E: 1,6-hexanediol (melting point 42°C, boiling point 250°C) Solvent F: 2,2-dimethyl-1,3-propanediol (melting point 128°C, boiling point 210°C) Solvent G: 2,5-dimethyl-2,5-hexanediol (melting point 89°C, boiling point 214°C) ((D) component) Solder powder A: Alloy composition is Sn-3.0Ag-0.5Cu, particle size distribution is 20 to 38 μm (equivalent to Type 4 of IPC-J-STD-005A), and the solder melting point is 217 to 220°C. Solder powder B: Alloy composition is Sn-3.0Ag-0.5Cu, particle size distribution is 1 to 12 μm (equivalent to Type 7 of IPC-J-STD-005A), and solder melting point is 217 to 220°C.

[0043] [Example 1] 33 mass% of nonionic surfactant A, 2.5 mass% of organic acid, 2.5 mass% of halogen-based activator, 10 mass% of amine-based activator, 38 mass% of solvent A, and 14 mass% of solvent B were charged into a container and mixed using a planetary mixer to obtain a flux composition. Thereafter, 12% by mass of the obtained flux composition and 88% by mass of solder powder (total of 100% by mass) were placed in a container and mixed with a planetary mixer to prepare a solder composition.

[0044] [Examples 2 to 12] 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 Examples 1 to 11] 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 2.

[0045] <Evaluation of solder composition> The solder compositions were evaluated (flux cleaning property, printability, copper foil corrosion) by the following methods. The results are shown in Tables 1 and 2. (1) Flux cleaning performance (liquid temperatures 20°C and 60°C) The solder composition was printed using a 0.2 mm thick metal mask having circular pattern holes with a diameter of 6.5 mm, and then heated and melted at 270°C to obtain a test plate. Next, the obtained test plate was immersed in a container containing ion-exchanged water (liquid temperature 20°C) and cleaned by applying ultrasonic waves (40 kHz) for 5 minutes. After that, the water was changed and the plate was rinsed for another 5 minutes under the same conditions. After that, excess liquid was removed with an air gun and the plate was dried at room temperature, and a cleaning test was performed. In addition, a cleaning test was conducted in the same manner as above, except that the liquid temperature was changed to 60°C. The proportion of the area where the flux components remained relative to the area where the residues were present before cleaning was evaluated, and the defluxability was evaluated based on this proportion of the remaining flux components in accordance with the following criteria. ○: The residual ratio is less than 30%. △: The residual ratio is 30% or more and less than 80%. ×: The residual ratio is 80% or more. (2) Printability Copper plates (copper, size: 50 mm × 50 mm, thickness: 0.5 mm) were prepared and polished with an abrasive. A solder composition was printed onto the copper plate using a 0.1 mm thick metal mask with a circular pattern of holes with a diameter of 2.0 mm to obtain a test plate. The shape printed on the test plate was observed under a microscope, and the printability was evaluated according to the following criteria. ◯: There was no missing or faded print. △: Print defects or faint marks occurred, but the defects were present in 1 / 3 or less of the pattern. x: Missing or faint printing occurred, and the occurrence occurred in more than one-third of the pattern. (3) Copper foil corrosion Copper plates (copper, size: 50 mm × 50 mm, thickness: 0.5 mm) were prepared and polished with an abrasive. A solder composition was printed on the copper plate using a 0.2 mm thick metal mask with a circular pattern of holes with a diameter of 6.5 mm to obtain a test plate. The test plate was heated in a solder bath maintained at 270°C and melted for 5 seconds. The test plate was left standing in a 40°C / 90% humidity environment for 48 hours, and the presence or absence of changes was observed under a microscope. The copper foil corrosion was evaluated according to the following criteria. ○: No discoloration. △: Discoloration was observed, but the discolored area was less than 1 / 3 of the total area. ×: Discoloration was observed, and the discolored area was more than 1 / 3 of the total area.

[0046] [Table 1]

[0047] [Table 2]

[0048] As is clear from the results shown in Tables 1 and 2, it was confirmed that the solder compositions of the present invention (Examples 1 to 12) were excellent in all respects of flux cleaning properties, printability, and copper foil corrosion. Therefore, it was confirmed that the solder composition of the present invention has excellent cleaning properties for flux residues with aqueous cleaners, can prevent copper foil corrosion, and has excellent printability. [Industrial Applicability]

[0049] 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 of electronic devices.

Claims

1. A flux composition comprising (A) a nonionic surfactant, (B) an activator, and (C) a solvent, The component (A) is a nonionic surfactant having an HLB value of more than 11 and a freezing point of less than 45°C, The component (C) contains (C1) triethylene glycol monobutyl ether. Flux composition.

2. 2. The flux composition according to claim 1, The component (C) further contains (C2) triethylene glycol monoethyl ether. Flux composition.

3. The flux composition according to claim 1 or 2, The component (B) contains an organic acid (B1) and an amine surfactant (B3). Flux composition.

4. A flux composition according to claim 1 or 2, and (D) a solder powder, Solder composition.

5. A soldered portion using the solder composition according to claim 4. Electronic board.

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