solder composition

Abstract

To provide a solder composition excellent in storage stability and solder meltability.SOLUTION: A solder composition contains a flux including resin, an activator, a solvent, and a thixotropic agent and an Sn-Bi type solder alloy. The activator includes a dihydrazide compound. The dihydrazide compound is aliphatic carboxylic acid hydrazide and is selected from sebacic acid dihydrazide, dodecanedioic acid dihydrazide, and their derivatives.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a solder composition. [Background technology]

[0002] A solder composition made by mixing a solder alloy and flux is used in mounting technology for mounting electronic components such as chip components and package substrates on electronic circuit boards such as printed wiring boards. Specifically, the solder composition is screen-printed onto pads on the surface of the electronic circuit board using a metal mask, and then the electronic components are mounted and heated (reflowed) to bond the electronic components to the electronic circuit board.

[0003]

[0003] Solder compositions are required to have excellent storage stability because they may be stored and reused if not used all at once. However, conventionally, when organic acids and amines are used as activators in flux, there has been a problem in that the activators react and the viscosity of the solder composition increases when the solder composition is stored at room temperature for a long period of time. Therefore, for example, Patent Document 1 discloses a solder composition that uses a carboxylic acid compound having a blocked carboxyl group as an activator in the flux in order to improve the storage stability of the solder composition. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2003 / 026835 Summary of the Invention [Problem to be solved by the invention]

[0005] However, carboxylic acid compounds with blocked carboxyl groups have weaker activity than carboxylic acids, which are organic acids. Therefore, using such carboxylic acid compounds as activators in flux may reduce the solder melting properties of the solder composition. While increasing the content of the activator may improve the solder melting properties, this is not desirable because the activator may remain in the flux residue after reflow, which may reduce electrical reliability, such as migration.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a solder composition that is excellent in storage stability and solder melting property. [Means for solving the problem]

[0007] The solder composition according to the present invention is a solder composition containing a flux including a resin, an activator, a solvent, and a thixotropic agent, and a Sn—Bi-based solder alloy, wherein the activator includes a dihydrazide compound.

[0008] The solder composition has excellent storage stability and solder melting properties because the activator contains a dihydrazide compound.

[0009] In the solder composition according to the present invention, the dihydrazide compound may be an aliphatic carboxylic acid hydrazide.

[0010] Due to this constitution, the solder composition has excellent storage stability and solder melting properties.

[0011] In the solder composition according to the present invention, the aliphatic carboxylic acid hydrazide may be at least one selected from the group consisting of sebacic acid dihydrazide, dodecanedioic acid dihydrazide, and derivatives thereof.

[0012] Due to this constitution, the solder composition has excellent storage stability and solder melting properties.

[0013] In the solder composition according to the present invention, the content of the dihydrazide compound may be 1.3 mass % or more and 6.3 mass % or less with respect to the total mass of the flux.

[0014] Due to this constitution, the solder composition has excellent storage stability and solder melting properties. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a solder composition having excellent storage stability and solder melting properties. DETAILED DESCRIPTION OF THE INVENTION

[0016] A solder composition according to an embodiment of the present invention will be described below.

[0017] The solder composition according to this embodiment contains a flux containing a resin, an activator, a solvent, and a thixotropic agent, and an Sn—Bi solder alloy.

[0018] <Flux> (resin) The flux according to this embodiment contains a resin. Examples of the resin include a rosin-based resin and a synthetic resin. The rosin-based resin is not particularly limited, and for example, one or more rosin-based resins selected from rosin and rosin derivatives (e.g., hydrogenated rosin, polymerized rosin, disproportionated rosin, acrylic acid-modified rosin, etc.) can be used. Furthermore, the synthetic resin can be a known synthetic resin such as a terpene phenol resin. Among these, the resin is preferably a rosin-based resin. Note that one type of resin may be used alone, or two or more types may be used in combination.

[0019] The resin content is preferably 30.0% by mass or more, and more preferably 40.0% by mass or more, based on the total weight of the flux. The resin content is preferably 70.0% by mass or less, and more preferably 50.0% by mass or less, based on the total weight of the flux. When two or more types of resins are contained, the above content is the total resin content.

[0020] (activator) The flux according to the present embodiment contains an activator. The activator according to the present embodiment contains a dihydrazide compound.

[0021] Examples of dihydrazide compounds include aliphatic carboxylic acid hydrazides and aromatic carboxylic acid hydrazides. Examples of aliphatic carboxylic acid hydrazides include adipic acid dihydrazide, sebacic acid dihydrazide, and dodecanedioic acid dihydrazide. Among these, from the viewpoint of further improving storage stability and solder melting property, at least one selected from sebacic acid dihydrazide, dodecanedioic acid dihydrazide, and derivatives thereof is preferred. Examples of aromatic carboxylic acid hydrazides include isophthalic acid dihydrazide.

[0022] The content of the dihydrazide compound is preferably 1.3 mass% or more, more preferably 2.2 mass% or more, based on the total weight of the flux. The content of the dihydrazide compound is preferably 6.3 mass% or less, more preferably 4.3 mass% or less, based on the total weight of the flux. When two or more dihydrazide compounds are contained, the above content is the total content of the dihydrazide compounds.

[0023] The flux according to this embodiment may contain an activator other than the dihydrazide compound. Examples of the other activator include organic acid activators, amine compounds, amino acids, and complex salts thereof. The other activators may be used alone or in combination of two or more.

[0024] The organic acid surfactant is not particularly limited, and examples thereof include monocarboxylic acids such as lauric acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, tuberculostearic acid, arachidic acid, behenic acid, lignoceric acid, and glycolic acid; dicarboxylic acids such as 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; tricarboxylic acids such as citric acid and tris(2-carboxyethyl) isocyanurate; and other organic acids such as dimer acid, levulinic acid, lactic acid, acrylic acid, benzoic acid, salicylic acid, anisic acid, citric acid, and picolinic acid.

[0025] The amine-based compound is not particularly limited, and examples thereof include imidazole-based compounds and triazole-based compounds. Examples of the imidazole-based compounds include benzimidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole (2E4MZ), 2-heptadecylimidazole, 2-undecylimidazole, 1-(4,6-diamino-s-triazin-2-yl)ethyl-2-undecylimidazole, 1-butylimidazole, 2-phenylimidazole, and 4-methyl-2-phenylimidazole. Examples of the triazole-based compounds include benzotriazole, 1H-benzotriazole-1-methanol, and 1-methyl-1H-benzotriazole. Other amine compounds include, for example, cetylamine, erucic acid amide, 3-(dimethylamino)-1,2-propanediol, 3,5-dimethylpyrazole, dimethylurea, hexahydro-1,3,5-triphenyl-1,3,5-triazine, pyrazinamide, N-phenylglycine, 3-methyl-5-pyrazolone, N-lauroylsarcosine, and 1,3-diphenylguanidine.

[0026] The amino acid is not particularly limited, and examples thereof include N-acetylphenylalanine (N-acetyl-L-phenylalanine, N-acetyl-DL-phenylalanine, N-acetyl-D-phenylalanine), N-acetylglutamic acid (N-acetyl-L-glutamic acid), N-acetylglycine, N-acetylleucine (N-acetyl-L-leucine, N-acetyl-DL-leucine, N-acetyl-D-leucine), and N-acetylphenylglycine (N-acetyl-N-phenylglycine, N-acetyl-L-phenylglycine, N-acetyl-DL-phenylglycine).

[0027] Other activators may include halogen-based activators such as amine halogen salts and halogen compounds, provided they do not impose an environmental burden. Examples of amines in amine halogen salts include diethylamine, dibutylamine, tributylamine, diphenylguanidine, and cyclohexylamine. Examples of halogens in amine halogen salts include fluorine, chlorine, bromine, and iodine. Examples of halogen compounds include tris(2,3-dibromopropyl)isocyanurate, 2,3-dibromo-2-butene-1,4-diol, 2-bromo-3-iodo-2-butene-1,4-diol, TBA-bis(2,3-dibromopropyl ether), and 4,4'-diiodobiphenyl. These halogen-based activators may be used alone or in combination. When the flux contains a halogen-based activator, its content is preferably 0.4% by mass or less, and more preferably 0.05% by mass or less. When two or more halogen-based activators are contained, the content is the total content of the halogen-based activators.

[0028] The content of the other activators is preferably 1.0% by mass or more, more preferably 3.0% by mass or more, based on the total flux. The content of the activators is preferably 30.0% by mass or less, more preferably 20.0% by mass or less, based on the total flux. By having the activator content within the above range, excellent solder melting properties are achieved, and the activator is less likely to remain in the flux residue. As a result, electrical reliability can be achieved. When two or more activators are included, the above content is the total content of the activators.

[0029] (thixotropic agent) The flux according to this embodiment includes a thixotropic agent. Examples of thixotropic agents include castor oil, fatty acid amides, fatty acid bisamides, polyamide compounds, kaolin, colloidal silica, organic bentonite, and glass frit. Among these, fatty acid bisamides (fatty acid bisamides) or polyamide compounds are preferred from the viewpoint of heat resistance. Examples of fatty acid bisamides include methylene bisstearamide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearamide, ethylene bishydroxystearamide, hexamethylene bishydroxystearamide, ethylene bisbehenic acid amide, hexamethylene bisstearamide, hexamethylene bisbehenic acid amide, hexamethylene bis-12-hydroxystearamide, N,N'-distearyl adipamide, and N,N'-xylylene bis-12-hydroxystearylamide. Examples of polyamide compounds include aliphatic polyamide compounds such as Talen VA-79, AMX-6096A, WH-215, and WH-255 (all manufactured by Kyoeisha Chemical Co., Ltd.), SP-10 and SP-500 (all manufactured by Toray Industries, Inc.), Grilamid L20G and Grilamid TR55 (all manufactured by MSC Japan), and aromatic polyamide compounds (semi-aromatic polyamide compounds or fully aromatic polyamide compounds) containing cyclic compounds such as benzene rings and naphthalene rings in the main chain, such as JH-180 (manufactured by Ito Oil Mills).The thixotropic agents may be used alone or in combination of two or more.

[0030] The content of the thixotropic agent is preferably 3.0 mass% or more, and more preferably 5.0 mass% or more, based on the total weight of the flux. The content of the thixotropic agent is preferably 10.0 mass% or less, and more preferably 8.0 mass% or less, based on the total weight of the flux. When two or more thixotropic agents are contained, the above content is the total content of the thixotropic agents.

[0031] (solvent) The flux according to this embodiment contains a solvent. Examples of the solvent include glycol ethers such as diethylene glycol monohexyl ether (hexyl diglycol), diethylene glycol dibutyl ether (dibutyl diglycol), diethylene glycol mono 2-ethylhexyl ether (2-ethylhexyl diglycol), diethylene glycol monobutyl ether (butyl diglycol), triethylene glycol monobutyl ether (butyl triglycol), polyethylene glycol dimethyl ether, and tripropylene glycol n-butyl ether; aliphatic compounds such as n-hexane, isohexane, and n-heptane; esters such as isopropyl acetate, methyl propionate, and ethyl propionate; ketones such as methyl ethyl ketone, methyl n-propyl ketone, and diethyl ketone; and alcohols such as ethanol, n-propanol, isopropanol, and isobutanol. These solvents may be used alone or in combination.

[0032] The content of the solvent is preferably 10.0 mass% or more, more preferably 20.0 mass% or more, based on the total weight of the flux. The content of the solvent is preferably 60.0 mass% or less, more preferably 45.0 mass% or less, based on the total weight of the flux. When two or more solvents are contained, the content is the total content of the solvents.

[0033] The flux according to the present embodiment may further contain at least one additive selected from the group consisting of a stabilizer, a surfactant, an antifoaming agent, and a corrosion inhibitor (antioxidant). The total content of the additives is not particularly limited and may be, for example, 1.0 mass % or less with respect to the total amount of the flux.

[0034] The content of the flux is preferably 5.0% by mass or more, more preferably 10.0% by mass or more, based on the solder composition, and is preferably 20.0% by mass or less, more preferably 15.0% by mass or less, based on the solder composition.

[0035] <Solder alloy> Examples of Sn-Bi based solder alloys include alloys such as Sn-Bi, Sn-Ag-Bi, Sn-Ag-Cu-Bi, Sn-Zn-Bi, Sn-Ag-Bi-In, and Sn-Ag-Cu-Bi-In-Sb. Among these, the solder alloy is preferably an Sn-Bi-Ag alloy. Furthermore, the alloy contains unavoidable impurities. "Avoidable impurities" refers to components that are inevitably mixed in during the manufacturing process and are acceptable within a range that does not affect the effects of the present invention.

[0036] The content of the solder alloy is preferably 80.0 mass % or more, more preferably 85.0 mass % or more, based on the solder composition, and is preferably 95.0 mass % or less, more preferably 90.0 mass % or less, based on the solder composition.

[0037] The solder composition is configured as a known solder composition such as a solder paste or flux-cored solder. When the solder composition is a solder paste obtained by mixing a flux and a solder alloy powder, the flux content is preferably 5.0 mass % or more and 20.0 mass % or less with respect to the entire solder composition. The solder alloy content is preferably 80.0 mass % or more and 95.0 mass % or less with respect to the entire solder composition. The particle diameter of the solder alloy powder is preferably 1 μm or more and 50 μm or less.

[0038] When the solder composition is a flux-cored solder having a linear solder alloy filled with flux, the content of the flux is preferably 0.1% by mass to 10.0% by mass of the entire solder composition, and the content of the solder alloy is preferably 90.0% by mass to 99.9% by mass of the entire solder composition.

[0039] The solder composition according to this embodiment is a solder composition containing a flux including a resin, an activator, a solvent, and a thixotropic agent, and a Sn—Bi-based solder alloy, and since the activator contains a dihydrazide compound, the solder composition has excellent storage stability and solder melting properties.

[0040] The solder composition according to this embodiment has excellent storage stability and solder melting properties because the dihydrazide compound is an aliphatic carboxylic acid hydrazide.

[0041] The solder composition according to this embodiment has excellent storage stability and solder melting properties because the aliphatic carboxylic acid hydrazide is at least one selected from the group consisting of sebacic acid dihydrazide, dodecanedioic acid dihydrazide, and derivatives thereof.

[0042] The solder composition according to this embodiment has a dihydrazide compound content of 1.3 mass % or more and 6.3 mass % or less relative to the total amount of the flux, and therefore has better storage stability and solder melting properties. [Example]

[0043] Examples of the present invention will be described below, but the present invention is not limited to the following examples.

[0044] The materials contained in the solder composition are detailed below. <Flux> (resin) CP-140: Polymerized rosin, manufactured by Arakawa Chemical Industries, Ltd. (solvent) HeDG: hexyl diglycol, manufactured by Nippon Nyukazai Co., Ltd. (thixotropic agent) SP-ZHH: Product name "Slipax ZHH", hexamethylene bishydroxystearic acid amide, manufactured by Nippon Kasei Co., Ltd. (activator) Adipic acid dihydrazide: Tokyo Chemical Industry Co., Ltd. Sebacic acid dihydrazide: Tokyo Chemical Industry Co., Ltd. Dodecanedioic acid dihydrazide: manufactured by Tokyo Chemical Industry Co., Ltd. Isophthalic dihydrazide: manufactured by Tokyo Chemical Industry Co., Ltd. Glutaric acid: Tokyo Chemical Industry Co., Ltd. 2-Phenylimidazole: Tokyo Chemical Industry Co., Ltd. 4-Methyl-2-phenylimidazole: Tokyo Chemical Industry Co., Ltd. 2-Ethylimidazole: Tokyo Chemical Industry Co., Ltd. 1,3-Diphenylguanidine: Tokyo Chemical Industry Co., Ltd. trans-2,3-dibromo-2-butene-1,4-diol: manufactured by Tokyo Chemical Industry Co., Ltd. 4,4'-Diiodobiphenyl: Tokyo Chemical Industry Co., Ltd. (antioxidant) SEENOX224M: Product name "SEENOX 224M", 2,2'-methylenebis(6-tert-butyl-4-methylphenol), manufactured by Shipro Chemical Co., Ltd. <Solder alloy> Solder alloy: 42Sn-57.6Bi-0.4Ag solder alloy powder, particle size 20-38μm, manufactured by Kokisha

[0045] <Preparation of solder composition> The above resins, solvents, thixotropic agents, and activators were placed in a container in the formulations shown in Table 1 and mixed at room temperature until all materials were uniformly dissolved, thereby obtaining fluxes for each Example and Comparative Example. The amounts of each formulation shown in Table 1 are equal to the content of each component contained in the flux. Next, each flux was mixed to 10 mass % and the above solder alloy to 90 mass %, thereby obtaining solder compositions (solder pastes) for each Example and Comparative Example.

[0046] [Table 1]

[0047] <Evaluation of storage stability> After measuring the viscosity of the solder composition of each Example and Comparative Example, the composition was placed in a thermostatic chamber at 40°C and stored. The viscosity of the solder composition of each Example and Comparative Example stored for 3 days and the viscosity of the solder composition of each Example and Comparative Example stored for 7 days were measured. The viscosity was measured using a coaxial double cylinder rotational viscometer (PCU-205, manufactured by Malcom).

[0048] The storage stability was evaluated as "Good (pass)" if the viscosity change rate after 3 days and 7 days of storage was less than ±12.5% ​​and no hardened product larger than the solder alloy powder was observed in the solder composition stored for 7 days. Otherwise, the evaluation was "Poor (fail)." The viscosity change rate was calculated based on formula (1). A viscosity change rate of less than ±12.5% ​​after 3 days or 7 days of storage compared to the viscosity of the solder composition before storage at 40°C was evaluated as "Good (pass)." Otherwise, the evaluation was "Poor (fail)." The presence or absence of hardened product was confirmed visually. The results are shown in Table 1.

[0049] Viscosity change rate (%) = {(viscosity of solder composition after storage at 40°C for 3 days or 7 days) ÷ (viscosity of solder composition)} × 100 (1)

[0050] <Evaluation of solder melting properties> (Test board) The solder paste printing thickness was adjusted using a 120 μm metal mask, and the solder paste of each example and comparative example was printed on a test board. Then, a component (a 0603 size (0.6 mm × 0.3 mm) chip resistor (Sn plated)) was mounted on the printed solder paste location, and heated under the following temperature conditions to obtain a test board.

[0051] (Temperature conditions) Heating rate: 3.0℃ / sec Heating temperature: 140°C or higher for 30 seconds Peak temperature: 170℃

[0052] The solder melting property was evaluated by observing the obtained test board with an optical microscope, and if a uniform gloss was observed on the fillet and no stray balls larger than the solder alloy powder were observed, it was judged as "Good (pass)", otherwise it was judged as "Poor (fail)". The results are shown in Table 1.

[0053] As can be seen from the results in Table 1, the solder compositions of each Example, which satisfy all the requirements of the present invention, contain a dihydrazide compound and therefore have excellent storage stability and solder melting properties. On the other hand, the solder compositions of Comparative Examples 1, 2, and 5, which do not contain a dihydrazide compound, are inferior in storage stability and solder melting properties. Furthermore, the solder compositions of Comparative Examples 3, 4, and 6, which do not contain a dihydrazide compound, are inferior in storage stability.

Claims

1. A solder composition containing a flux including a resin, an activator, a solvent, and a thixotropic agent, and a Sn—Bi solder alloy, the activator comprises a dihydrazide compound; the content of the dihydrazide compound is 1.3 mass% or more and 6.3 mass% or less with respect to the entire flux, A solder composition, wherein the content of the activator is 20.0 mass % or less with respect to the total amount of the flux.

2. 2. The solder composition of claim 1, wherein the dihydrazide compound is an aliphatic carboxylic acid hydrazide.

3. 3. The solder composition according to claim 2, wherein the aliphatic carboxylic acid hydrazide is at least one selected from the group consisting of sebacic acid dihydrazide, dodecanedioic acid dihydrazide, and derivatives thereof.

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