Lead-free solder flux

Abstract

[Technical Problem] This invention provides a lead-free solder flux, which exhibits excellent wettability, forms bumps with minimal depressions during installation, and effectively removes flux residue during subsequent cleaning. [Technical Means] A lead-free solder flux, comprising a rosin-based resin (A), an activator (B), a branched alkoxy-containing alkylene glycol monoalkyl ether (C), and a thixotropic agent (D). Component (B) comprises hydrogenated dimer acid (B1).

Description

Technical Field

[0001] This invention relates to lead-free solder flux. Background Technology

[0002] Lead-free solder flux is a material used when mounting electronic components such as ICs, capacitors, and resistors onto printed circuit boards. One application method includes TAB (Tape Automated Bonding) and FC (Flip Chip) methods, which utilize bumps. Bumps are metal protrusions used to connect semiconductor chip electrodes to substrate electrodes, connecting the package to the substrate and providing electrical connections.

[0003] Examples of methods for forming bumps include applying flux or solder paste mixed with flux and solder powder to the substrate electrode via screen printing, and using solder balls with real spheres. Furthermore, as an example of such technology, fluxes composed of rosin, activator, solvent, and thickener are known (Patent Document 1). Existing technical documents Patent documents

[0004] Patent Document 1: Japanese Patent Application Publication No. 2009-088431

[0005] For bonding methods like TAB and FC that rely on bumps, in order to ensure electrical properties, it is required to form bumps with few depressions to achieve flatness, and to be able to remove residues from the self-generated flux after formation. However, no flux has yet been found that can achieve all of these. Summary of the Invention The technical problem that the invention aims to solve

[0006] The present invention provides a lead-free solder flux that forms bumps with few depressions during installation and that flux residues are well removed during subsequent cleaning. Technical means to solve technical problems

[0007] Through in-depth research, the inventors have solved the aforementioned technical problems and completed this invention. Specifically, this invention provides the following content.

[0008] (project) 1. A lead-free solder flux, wherein the lead-free solder flux comprises a rosin-based resin (A), an activator (B), a branched alkoxy group-containing alkylene glycol monoalkyl ether (C), and a thixotropic agent (D). (B) Component contains hydrogenated dimer acid (B1). 2. The lead-free solder flux as described in item 1 above, wherein component (B) further comprises a halogenated activator (B2) and / or a non-halogenated acid activator other than hydrogenated dimer acid (B3). Beneficial effects

[0009] The solder flux according to the present invention forms bumps with minimal depressions during installation, and flux residues are effectively removed during subsequent cleaning. Furthermore, the lead-free solder flux also exhibits excellent wettability. Attached Figure Description

[0010] Figure 1 This is a graph showing the reflow soldering temperature profiles under high-temperature conditions in the embodiments and comparative examples. Figure 2 This is a graph showing the reflow soldering temperature profiles under standard conditions in the embodiments and comparative examples. Detailed Implementation

[0011] The lead-free solder flux of the present invention comprises rosin-based resin (A) (hereinafter referred to as component (A), organic acid (B) (hereinafter referred to as component (B), alkylene glycol monoalkyl ether with branched alkoxy groups (C) (hereinafter referred to as component (C)) and thixotropic agent (D) (hereinafter referred to as component (D)).

[0012] (A) The components are rosin-based resins, which are divided into natural rosin and modified rosin. They can be used alone or in combination of two or more.

[0013] Natural rosin refers to a mixture of resinous acids collected from pine trees. Based on the production method, it is classified into: resin rosin, tall oil rosin, and wood rosin. The main resinous acid includes abietic acid, with others including neopiperidine, longipole abietic acid, dehydropiperidine, L-piperidine, piratic acid, isopiratic acid, and sandapicopic acid. Furthermore, natural rosin containing dihydrokaurinic acid and comunic acid can also be used. These can be used alone or in combination.

[0014] In addition, refined rosin, which is a natural rosin, can also be used.

[0015] Examples of modified rosin include: hydrides of the aforementioned natural rosin (hydrogenated rosin); α,β-unsaturated carboxylic acid-modified rosin such as maleated rosin, fumarate rosin, and acrylic rosin; hydrides of the aforementioned carboxylic acid-modified rosin; rosin derivatives such as disproportionated rosin, rosin esters, and polymerized rosin; and hydrides of the aforementioned derivatives. These can be used alone or in combination of two or more. Examples of polyols used to manufacture the aforementioned rosin esters include triols such as glycerol, glycerol, 1,2,3-propanetriol, 1,2,4-butanetriol, 3-methylpentane-1,3,5-triol, and 1,2,6-hexanetriol glycerol; and tetraols such as pentaerythritol, diglycerol, and bis-trimethylolpropane. These can be used alone or in combination of two or more. Among these components (A), modified rosin is preferred, and acrylic rosin, hydrides of acrylic rosin, and polymerized rosin are more preferred.

[0016] From the viewpoint that lead-free solder flux easily exhibits excellent wettability and easily forms bumps with fewer depressions during installation, the content of component (A) is preferably 35% to 70% by weight of non-volatile components relative to 100% by weight of all flux components, more preferably 40% to 60% by weight, and even more preferably 45% to 52.5% by weight.

[0017] (B) is an activator. In the lead-free solder flux of the present invention, it must contain hydrogenated dimer acid (B1) (hereinafter referred to as (B1) component).

[0018] Hydrogenated dimer acid refers to the hydrogenated double bond of dimer acids such as oleic acid, linoleic acid, linolenic acid and other 18-carbon unsaturated fatty acids, and erucic acid and other 22-carbon unsaturated fatty acids, after dimerization. Lead-free solder flux containing this hydrogenated dimer acid is more likely to form bumps with fewer depressions.

[0019] Commercially available hydrogenated dimeric acids include "PRIPOL1009" and "PRIPOL1010" (manufactured by Kuroda Japan Co., Ltd.).

[0020] From the viewpoint that it is easy to form bumps with fewer depressions when installing lead-free solder flux, the content of component (B1) is preferably 2.5% to 25% by weight, more preferably 7.5% to 20% by weight, and even more preferably 12% to 15.5% by weight, relative to 100% by weight of all flux components, based on the weight of non-volatile components.

[0021] From the viewpoint that lead-free solder flux easily exhibits excellent wettability and easily forms bumps with less depression during installation, component (B) preferably further includes a halogenated activator (B2) (hereinafter also referred to as component (B2)) and a non-halogenated acid activator other than hydrogenated dimer acid (B3) (hereinafter also referred to as component (B3)).

[0022] As a component of (B2), examples include: Bromocarboxylic acids such as 3-bromopropionic acid, 2-bromopentanic acid, 2-bromopentanic acid, 5-bromopentanic acid, 2-bromoisopentanic acid, 2,3-dibromosuccinic acid, 2-bromosuccinic acid, and 2,2-dibromohexamic acid; Bromools such as trans-2,3-dibromo-1,4-butenediol, cis-2,3-dibromo-1,4-butenediol, 1-bromo-2-butanol, 1-bromo-2-propanol, 3-bromo-1-propanol, 3-bromo-1,2-propanediol, 1,4-dibromo-2-butanol, 1,3-dibromo-2-propanol, 2,2-bis(bromomethyl)-1,3-propanediol, and 2,3-dibromo-1-propanol; Dibromosalicylic acid and other bromohydroxycarboxylic acids; Amine halogen compounds such as methylamine bromate, ethylamine bromate, diethylamine bromate, and diethylamine hydrochloride; Halogen compounds that do not contain active hydrogen, such as 1-bromo-3-methyl-1-butene, 1,4-dibromobutene, 1-bromo-1-propene, 2,3-dibromopropene, 1,2-dibromo-1-phenylethane, 1,2-dibromostyrene, 1,2,3,4-tetrabromobutane, 1,2-dibromo-1-phenylethane, 4-stearoyloxybenzyl bromide, 4-stearoyloxybenzyl bromide, 4-stearoylbenzyl bromide, 4-bromomethylbenzyl stearate, 4-stearoylaminobenzyl bromide, 2,4-dibromomethylbenzyl stearate, 4-palmitoyloxybenzyl bromide, 4-myristoyloxybenzyl bromide, 4-lauroyloxybenzyl bromide, and 4-undecyloxybenzyl bromide. These can be used alone or in combination of two or more. From the viewpoint that the bumps are less likely to be recessed when applying lead-free solder flux, it is preferable to contain bromocarboxylic acid and bromoethanol, and more preferably to contain 2,3-bromosuccinic acid and trans-2,3-dibromo-1,4-butenediol.

[0023] From the viewpoint that lead-free solder flux easily exhibits excellent wettability, easily forms bumps with few depressions during installation, and is easy to remove flux residues during subsequent cleaning, the content of component (B2) is preferably 20% by weight or less, more preferably 1% to 15% by weight, and even more preferably 2% to 7.5% by weight, relative to 100% by weight of all flux components, based on the weight of non-volatile components.

[0024] As a component of (B3), for example: Decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, and other alkane monocarboxylic acids; Oleic acid, linoleic acid, and other alkenyl monocarboxylic acids; Succinic acid, glutaric acid, adipic acid, oxalic acid, octanoic acid, azelaic acid, sebacic acid, dodecanoic acid, and other alkane dicarboxylic acids; Dimeric acids, itaconic acid, fumaric acid, maleic acid, maleic anhydride, and other alkenyl dicarboxylic acids; 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, and other cycloalkane dicarboxylic acids; Pyrrole 2-carboxylic acid, pyrrole 2,5-dicarboxylic acid, 2-furan carboxylic acid, 2,5-furan dicarboxylic acid, 2-thiophene carboxylic acid, 2,5-thiophene dicarboxylic acid, pyridine-2-carboxylic acid (picolinic acid), pyridine 2,6-dicarboxylic acid, and other heterocyclic carboxylic acids containing heteroatoms. These can be used alone or in combination of two or more. From the viewpoint of easily forming bumps with fewer depressions when applying lead-free solder flux, alkane dicarboxylic acids are preferred, and glutaric acid and adipic acid are more preferred.

[0025] From the viewpoint that it is easy to form bumps with fewer depressions when installing lead-free solder flux, the content of component (B3) is preferably 15% by weight or less, more preferably 0.1% to 10% by weight, and even more preferably 0.5% to 7.5% by weight, relative to 100% by weight of all flux components, based on the weight of non-volatile components.

[0026] In the lead-free solder flux of the present invention, as component (B), an amine activator (B4) (hereinafter also referred to as component (B4)) may be further included.

[0027] As a component of (B4), examples include: Monoalkylamines such as n-hexylamine, n-heptylamine, and n-octylamine; Dialkylamines such as di-n-hexylamine, di-n-heptylamine, di-n-octylamine, di-n-nonylamine, di-n-decylamine, di(1-ethylhexyl)amine, and di(2-ethylhexyl)amine; Trialkylamines such as tri-n-hexylamine, tri-n-heptylamine, tri-n-octylamine, and N,N-diethylmethylamine; Alkanolamines such as monoethanolamine, diethanolamine, and triethanolamine; Cycloalkylamines such as cyclopentylamine and cyclohexylamine; Dicyclopentylamine, dicyclohexylamine, and other dicycloalkylamines; Aromatic amines such as diphenylamine and triphenylamine can be used alone or in combination of two or more.

[0028] The content of (B4) component is preferably 10% by weight or less, more preferably 5% by weight or less, and even more preferably 3% by weight or less, relative to 100% by weight of all flux components, based on the weight of non-volatile components.

[0029] (C) The component is a branched alkoxy alkylene glycol monoalkyl ether. If this component is present, the residue from the self-soldering flux can be easily and effectively removed during cleaning after bump formation.

[0030] As a component (C), it is represented by any of the structures in general formula (1), general formula (2) or general formula (3).

[0031] [Chemistry 1] (In formula (1), X) 1 R represents an oxonide. 1 R 2 (Each alkyl group independently represents a carbon group with 1 to 30 carbon atoms)

[0032] [Chemistry 2] (In formula (2), X) 2 R represents an oxonide. 3 R 4 (Each alkyl group independently represents a carbon group with 1 to 30 carbon atoms)

[0033] [Chemistry 3] (In formula (3), X) 3 R represents an oxonide. 5 R 6 R 7 (Each alkyl group independently represents a carbon group with 1 to 30 carbon atoms)

[0034] Examples of oxoalkylene groups in general formulas (1), (2), and (3) include: Monoalkyl oxonides, such as oxoethylidene (-OCH2CH2-), oxopropylidene (-OCH2CH(CH3)-), oxotrimethylene (-OCH2CH2CH2-), and oxotetramethylene (-OCH2CH2CH2CH2-); Polyoxyethylene (-(OCH2)) a -), Polyoxypropylene (-(OCH2CH(CH3)) a -), Polyoxytrimethylene (-(OCH2CH2CH2) a -), Polyoxytetramethylene (-(OCH2CH2CH2CH2) a -), Polyoxyethylene-polyoxypropylene (-(OCH2)a -(OCH2CH(CH3)) b -) and other polyoxyalkylene compounds. Furthermore, in the structure of polyoxyalkylene compounds, a and b independently represent integers greater than 2.

[0035] Examples of alkyl groups in general formulas (1), (2) and (3) include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecanyl, n-hexadecyl, n-heptadecyl, n-heptadecyl, n-octadecyl, etc. Branched alkyl groups such as isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, 2-ethylhexyl, isohexyl, isoheptyl, isooctyl, and isostearyl are used. Furthermore, the position of the carbon atoms bonded to the alkyl groups is not particularly limited.

[0036] These (C) components can be used alone or in combination of two or more. From the viewpoint that flux residue can be easily removed during cleaning after bump formation, polyalkylene glycol monoalkyl ethers with branched alkoxy groups as shown in general formula (2) are preferred, and polyethylene glycol monoalkyl ethers with branched alkoxy groups as shown in general formula (2) and (polyethylene glycol-polypropylene glycol) monoalkyl ethers with branched alkoxy groups as shown in general formula (2) are more preferred.

[0037] Commercially available products that are part of component (C) include, for example, “SOFTANOL 30”, “SOFTANOL 50”, “SOFTANOL 70”, “SOFTANOL 90”, “SOFTANOL 120”, “SOFTANOL 150”, “SOFTANOL 200”, “SOFTANOL 300”, “SOFTANOL 400”, “SOFTANOL 500”, “SOFTANOL EP 5035”, “SOFTANOL EP7025”, “SOFTANOL EP 7045”, “SOFTANOL EP 7085”, “SOFTANOL EP 9050”, “SOFTANOL EP90150”, and “SOFTANOL EP 12030” (all manufactured by Nippon Shokubai Co., Ltd.).

[0038] In addition, the SOFTANOL series is represented by equation (4), and the SOFTANOL EP series is represented by equation (5).

[0039] [Chemistry 4] (In equation (4), m+n=9~11, and x represents an integer greater than 1)

[0040] [Chemistry 5] (In equation (5), m+n=9~11, and x and y independently represent integers greater than 1.)

[0041] From the viewpoint that the residue of self-reinforcing flux can be easily removed during cleaning after bump formation, the content of component (C) is preferably 1% to 40% by weight of non-volatile components relative to 100% by weight of all flux components, more preferably 7% to 35% by weight, and even more preferably 12% to 30% by weight.

[0042] For the lead-free solder flux of the present invention, in addition to component (C), alkylene glycol monoalkyl ethers (C') other than component (C) can also be used (hereinafter referred to as component (C')).

[0043] As a component of (C'), for example, the following can be cited: Ethylene glycol monomethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monopentyl ether, ethylene glycol monohexyl ether, ethylene glycol monoheptyl ether, ethylene glycol monooctyl ether, and other ethylene glycol monoalkyl ethers; Diethylene glycol monomethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monopentyl ether, diethylene glycol monohexyl ether, diethylene glycol monoheptyl ether, diethylene glycol monooctyl ether, and other diethylene glycol monoalkyl ethers; Triethylene glycol monomethyl ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, triethylene glycol monopentyl ether, triethylene glycol monohexyl ether, triethylene glycol monoheptyl ether, triethylene glycol monooctyl ether, and other triethylene glycol monoalkyl ethers; Propylene glycol monomethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol monopentyl ether, propylene glycol monohexyl ether, propylene glycol monoheptyl ether, propylene glycol monooctyl ether, and other propylene glycol monoalkyl ethers; Dipropylene glycol monomethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-n-butyl ether, dipropylene glycol mono-n-pentyl ether, dipropylene glycol mono-n-hexyl ether, dipropylene glycol mono-n-heptyl ether, dipropylene glycol mono-n-octyl ether, and other dipropylene glycol mono-n-alkyl ethers; Tripropylene glycol monomethyl ether, tripropylene glycol mono-n-propyl ether, tripropylene glycol mono-n-butyl ether, tripropylene glycol mono-n-pentyl ether, tripropylene glycol mono-n-hexyl ether, tripropylene glycol mono-n-heptyl ether, tripropylene glycol mono-n-octyl ether, and other tripropylene glycol mono-n-alkyl ethers; Tetraethylene glycol monomethyl ether and other tetraethylene glycol mono-n-alkyl ethers; Ethylene glycol monophenyl ether, propylene glycol monophenyl ether, diethylene glycol monophenyl ether, dipropylene glycol monophenyl ether, and other alkylene monophenyl ethers can be used alone or in combination of two or more.

[0044] From the viewpoint that it is easy to form bumps with fewer depressions when installing lead-free solder flux, the content of (C') component is preferably 25% by weight or less, more preferably 18.5% by weight or less, and even more preferably 15% by weight or less, based on the weight of non-volatile components relative to 100% by weight of all flux components.

[0045] (D) The component is a thixotropic agent. If this component is present, it will exhibit moderate thixotropy, and the screen printability of lead-free solder flux will be easily improved.

[0046] Examples of ingredients (D) include plant and animal-based thixotropic agents such as hardened castor oil, beeswax, and carnauba wax; and amide-based thixotropic agents such as stearamide and 12-hydroxystearic acid ethylenediamide. These can be used alone or in combination of two or more.

[0047] From the viewpoint of improving the screen printability of lead-free solder flux, the content of component (D) is preferably 0.5% to 15% by weight, more preferably 1% to 10% by weight, and even more preferably 2% to 5% by weight, relative to 100% by weight of all flux components, based on the weight of non-volatile components.

[0048] The lead-free solder flux of the present invention may further contain an organic component (E) (hereinafter referred to as component (E)), said organic component (E) being an organic component (E) other than component (A), component (B), component (C), component (C'), and component (D).

[0049] As a component of (E), examples include: Alcohols such as ethanol, n-propanol, isopropanol, n-butanol, isobutanol, benzyl alcohol, 1,3-butanediol, 1,4-butanediol, and octanediol; Esters such as isopropyl acetate, ethyl propionate, butyl benzoate, diethyl adipate, and ethyl 2-(2-n-butoxyethoxy)acetate; Alkanes such as n-hexane, dodecane, and tetradecene; Terpenes such as α-terpinene, myrcene, allocimene, limonene, dipentene, α-pinene, β-pinene, carvone, ocimene, and phellandrene; Terpineols such as α-terpineol (α-terpineol) and terpineol (ターピネオール); Pyrrolidones such as N-methyl-2-pyrrolidone can be used alone or in combination of two or more.

[0050] The content of component (E) is preferably 10% by weight or less, more preferably 5% by weight or less, relative to 100% by weight of all flux components, based on the weight of non-volatile components.

[0051] The lead-free solder flux of the present invention may further contain non-rosin resin.

[0052] Examples of non-rosin-based resins include epoxy resins, acrylic resins, polyimide resins, polyamide resins (nylon resins), polyester resins, polyacrylonitrile resins, vinyl chloride resins, vinyl acetate resins, polyolefin resins, fluorinated resins, ABS resins, and other synthetic resins. These can be used individually or in combination of two or more.

[0053] The content of non-rosin-based resin, based on the weight of non-volatile components, is preferably 20% by weight or less, more preferably 10% by weight or less, relative to 100% by weight of all flux components.

[0054] The lead-free solder flux of the present invention may further contain additives, which are components (A), (B), (C), (C'), (D), and (E) and are additives other than non-rosin resins.

[0055] Examples of additives include surfactants (nonionic surfactants, cationic surfactants, and anionic surfactants other than components (C) and (C'), antioxidants, rust inhibitors, mildew inhibitors, and matting agents. Additionally, examples of rust inhibitors include benzotriazole. These can be used alone or in combination of two or more.

[0056] The content of the non-volatile components as additives is preferably 10% by weight or less, more preferably 5% by weight or less, relative to 100% by weight of all flux components.

[0057] The method for manufacturing the lead-free solder flux of the present invention can employ various known methods, such as mixing components (A), (B), (C), and (D), as well as components (C') and (E) as needed, a non-rosin-based base resin, and additives under heating until fully melted. The mixing method and order are not particularly limited. Furthermore, the heating temperature is preferably 80°C to 230°C, more preferably 100°C to 200°C.

[0058] The lead-free solder flux of the present invention is typically used in a state without solder powder, but it can also be mixed with the powder and used as a lead-free solder paste. Example

[0059] The present invention will be described in more detail below through embodiments. However, the technical scope of the present invention is not limited to these embodiments. Furthermore, unless otherwise specified, "parts" and "%" in the embodiments are based on weight.

[0060] Example 1 A lead-free solder flux was prepared by mixing 48g of hydride of acrylic rosin (trade name: "KE-604", manufactured by Arakawa Chemical Industry Co., Ltd.), 15g of hydrogenated dimer acid (trade name: "PRIPOL1010", manufactured by Croda Japan Co., Ltd.), 5g of dibromosuccinic acid, 1g of glutaric acid, 15g of a branched alkoxy alkylene glycol monoalkyl ether of general formula (4) (trade name: "SOFTANOL150", manufactured by Nippon Shokubai Co., Ltd.), 12g of diethylene glycol monohexyl ether, and 4g of hardened castor oil and melting the mixture under heat. The composition is shown in Table 1.

[0061] Examples 2-22, Comparative Examples 1-4 Except for changing the composition to that shown in Table 1 or Table 2, lead-free solder fluxes were prepared in the same manner as in Example 1.

[0062] <Wetting properties> 0.025g of flux and solder rings (solder alloy composition: Sn96.5 Ag3.5) were placed on a copper plate (40mm long, 40mm wide, 0.3mm thick). The solder was melted on a hot plate at 270°C and heated for 30 seconds to create test samples. Wetting properties were evaluated according to JIS Z 3197 (solder diffusion test). A diffusion rate of 65% or higher was considered good; higher values ​​indicated better wetting properties. The results are shown in Tables 1 and 2 (and below).

[0063] <Bump depression> Each lead-free solder flux was screen-printed onto an OSP-treated copper substrate (50mm x 50mm x 1.6mm). Then, 100μm solder balls (SAC-305, Sn96.5 Ag3 Cu0.5) were mounted on top. The soldering process was carried out under a nitrogen atmosphere. Figure 1 Reflow soldering was performed using the temperature profile shown under the high-temperature conditions. The surface of the copper substrate after reflow soldering was observed using a microscope to confirm the presence of bump depressions. This process was repeated 5 times, and the evaluation was based on the number of times depressions occurred, according to the following criteria. (Evaluation Criteria) 4: Depressions without bumps 3: The bump depression occurred once. 2: The bumps dented 2 to 3 times. 1: The bumps dented 4 to 5 times.

[0064] <Removal> Next, the copper substrate was placed in a beaker containing 150 ml of cleaning agent (trade name: "PINE ALPHA ST-180K", manufactured by Arakawa Chemical Industry Co., Ltd.), and cleaned using an ultrasonic cleaner (device name: "W-13", manufactured by Honda Electronics Co., Ltd.) at a temperature of 60°C. The time until flux residue on the copper substrate was removed was measured and evaluated according to the following criteria. (Evaluation Criteria) 4: Can remove in less than 5 minutes 3: Able to remove in 5 minutes but less than 10 minutes 2: Able to remove in 10 minutes but less than 15 minutes 1: Able to remove in more than 15 minutes, or unable to completely remove

[0065] In the above evaluation method, reflow soldering is changed to Figure 2 The curves under the standard conditions shown are applied in the same way to evaluate the bump's concavity and cleanliness.

[0066] [Table 1]

[0067] [Table 2]

[0068] The product names, abbreviations, etc. shown in Tables 1 and 2 represent the following ingredients. <Rosin-based resins> • KE-604 - Trade name: "KE-604", a hydride of acrylic rosin, manufactured by Arakawa Chemical Industry Co., Ltd. <Active Agent> •PRIPOL1010 - Trade name: "PRIPOL1010", hydrogenated dimeric acid, manufactured by Croda Japan Co., Ltd. DBSA: 2,3-Dibromosuccinic acid DBBO: trans-2,3-dibromo-2-buten-1,4-diol <alkylene glycol monoalkyl ether> ·SOFTANOL 150 - Trade name: "SOFTANOL 150", which is a polyethylene glycol monoalkyl ether having a branched alkoxy group represented by general formula (4), manufactured by Nippon Shokubai Co., Ltd. ·SOFTANOL 90 - Trade name: "SOFTANOL 90", which is a polyethylene glycol monoalkyl ether having a branched alkoxy group represented by general formula (4), manufactured by Nippon Shokubai Co., Ltd. ·SOFTANOL 70 - Trade name: "SOFTANOL 70", which is a polyethylene glycol monoalkyl ether having a branched alkoxy group represented by general formula (4), manufactured by Nippon Shokubai Co., Ltd. ·HeDG - diethylene glycol monohexyl ether ·MFTG - tripropylene glycol monomethyl ether <Thixotropic agent> ·Hardened castor oil - Trade name: "Hardened Castor Oil HCO-P (硬化ひまし油 HCO-P)", manufactured by Toyokuni Seiyu Co., Ltd. (豊国製油(株)) <Others> SURFYNOL 104 - Trade name: "SURFYNOL 104 (サーフィノール104)", which is a nonionic surfactant, manufactured by Nissin Chemical Industry Co., Ltd. (日信化学工業(株)).

Claims

1. A lead-free solder flux, wherein, The lead-free solder flux comprises rosin-based resin (A), activator (B), branched alkoxyalkylene glycol monoalkyl ether (C), and thixotropic agent (D). (B) Component contains hydrogenated dimer acid (B1).

2. The lead-free solder flux according to claim 1, wherein, (B) The ingredients further include halogenated surfactants (B2) and / or non-halogenated acid surfactants other than hydrogenated dimer acids (B3).

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