Flux for soldering and soldering material

Abstract

The present invention provides a flux for soldering and a soldering material that are capable of suppressing a reduction in bondability and electrical reliability of a soldered joint. The flux and the soldering material contain a solvent component, a resin component, an isocyanuric acid derivative, and cellulose fibers.

Description

Soldering flux and soldering materials

[0001] The present invention relates to a soldering flux and a solder material using the same.

[0002] Solder used for joining electronic components, etc., is composed of solder materials containing a solder alloy and flux. Flux is formulated to improve solderability and contains various components such as a resin component, an activator component, a solvent component, an antioxidant component, and a thixotropic component (also called a thixotropic agent component). The inclusion of an activator component in the flux suppresses the occurrence of oxidation and migration on the metal surface. Various activators have been investigated in the past to obtain fluxes with improved oxide film removability.

[0003] For example, Patent Documents 1 and 2 disclose fluxes that contain an isocyanuric acid derivative as an activator component and thereby have high oxide film removal properties. That is, Patent Document 1 discloses a flux that can maintain high oxide film removal properties even when a solder ball and a solder paste are once separated due to deformation of the substrate during heating and then rejoined. Patent Document 2 discloses a flux that does not easily lose solder melting properties even for fine pads on the surface of an electronic circuit board.

[0004] Furthermore, when soldering components such as electronic components to an electronic circuit board, solder materials are heated at high temperatures (reflow) to melt the solder. The components in the flux contain compounds that generate gases when heated, and these gases can cause voids in the solder joint. Furthermore, the components in the flux can volatilize, generating gases that can cause the flux and solder balls in the solder material to scatter. Patent Documents 3 and 4 disclose fluxes containing specific cellulose as a technique for preventing voids and scattering due to gas volatilization.

[0005] Meanwhile, in recent years, in order to improve the durability of solder, indium (In), antimony (Sb), bismuth (Bi), and the like have been added to solder alloys in addition to conventional elements such as tin (Sn), silver (Ag), and copper (Cu). However, the addition of these metals broadens the liquidus-solidus line width of the solder alloy, which can lead to problems such as the occurrence of small solder lumps called side balls on the sides of chips after soldering using a solder material such as solder paste, or the occurrence of holes called blowholes in the solder fillets, which can lead to soldering defects. The occurrence of side balls can lead to short circuits. Blowholes can distort the shape of the solder fillets, potentially reducing the durability of the solder. Therefore, these soldering defects can reduce the bondability and electrical reliability of the solder joint.

[0006] Japanese Patent No. 6528102 Japanese Patent No. 6899173 International Publication No. WO2022 / 138755 International Publication No. WO2022 / 138756

[0007] The present invention has been made in view of the above-mentioned problems of the conventional art, and an object of the present invention is to provide a soldering flux and a solder material that can suppress deterioration in the bondability and electrical reliability of solder joints.

[0008] The flux of the present invention contains a solvent component, a resin component, an isocyanuric acid derivative, and cellulose fibers.

[0009] The present invention may further comprise a hydroiodide salt of at least one amine compound selected from the group consisting of aliphatic amines, alicyclic amines, aromatic amines, heterocyclic amines, and aromatic guanidines.

[0010] The present invention may contain the isocyanuric acid derivative in an amount of 0.1% by mass or more and 10.0% by mass or less.

[0011] The present invention may contain the cellulose fibers in an amount of 0.1% by mass or more and 10.0% by mass or less.

[0012] In the present invention, the cellulose fibers may contain lump cellulose in which fibrous cellulose having a length of 1 μm or more and less than 1 mm and fibrous cellulose having a length of 1 nm or more and less than 1 μm are mixed.

[0013] The present invention, which relates to a solder material, includes any of the soldering fluxes described above and a solder alloy.

[0014] In the present invention relating to the solder material, the solder alloy may contain at least one metal selected from the group consisting of tin (Sn), silver (Ag), copper (Cu), antimony (Sb), indium (In), cobalt (Co), and nickel (Ni).

[0015] According to the present invention, it is possible to provide a soldering flux and a solder material that can suppress deterioration in the bondability and electrical reliability of solder joints.

[0016] Figure 1 shows a photograph of a fillet where a blow hole occurred, and Figure 2 shows a photograph of the side of a part where a side chip ball occurred.

[0017] The soldering flux (hereinafter also simply referred to as flux) and solder material according to the present invention will be described below.

[0018] (First embodiment: flux) The flux of this embodiment is a solder flux containing a solvent component, a resin component, an isocyanuric acid derivative, and cellulose fibers.

[0019] <Solvent Component> The solvent component contained in the flux of this embodiment is not particularly limited as long as it is a known component used as a solvent component in a flux. For example, glycol ethers such as diethylene glycol monohexyl ether, diethylene glycol dibutyl ether, diethylene glycol mono-2-ethylhexyl ether, diethylene glycol monobutyl ether, tripropylene glycol monobutyl ether, polypropylene glycol monobutyl ether, butyl triglycol (triethylene glycol monobutyl ether), and polyethylene glycol dimethyl ether; aliphatic compounds such as n-hexane, isohexane, n-heptane, octane, and decane; esters such as isopropyl acetate, methyl propionate, ethyl propionate, tris(2-ethylhexyl) trimellitate, acetyl tributyl citrate, and diethylene glycol dibenzoate; ketones such as methyl ethyl ketone, methyl-n-propyl ketone, and diethyl ketone; alcohols such as ethanol, n-propanol, isopropanol, isobutanol, octanediol, and 3-methyl-1,5-pentanediol; and carboxylic acids such as hexanoic acid, heptanoic acid, octanoic acid, 2-ethylhexanoic acid, nonanoic acid, and decanoic acid. The solvents may be used alone or in combination.

[0020] The content of the solvent component in the flux is not particularly limited, but may be, for example, 20% by mass to 70% by mass, or 30% by mass to 60% by mass, based on the total amount of the flux. By using the solvent in this range, each component can be uniformly distributed in the liquid. Furthermore, when used in a solder material such as a solder paste, the viscosity can be easily adjusted to an appropriate range for ease of handling.

[0021] <Resin Component> The resin component contained in the flux of the present embodiment is not particularly limited as long as it is a known component used as a resin component of a flux, such as a liquid polymer compound, rosin, or a rosin-based resin that is a derivative of rosin.

[0022] Examples of liquid polymerizable compounds include liquid resins and liquid polymerized fatty acids. The liquid resins are not particularly limited, but include, for example, dimer diol, hydrogenated polybutadiene having hydroxyl groups at both ends (hydroxyl-terminated liquid polybutadiene), liquid polybutadiene having hydroxyl groups at both ends (hydroxyl-terminated liquid polybutadiene), liquid polyisoprene having hydroxyl groups at both ends (hydroxyl-terminated liquid polyisoprene), polybutene, acrylic resin, polyester polyol resin, and the like. Among these, the liquid resin may be at least one selected from the group consisting of hydrogenated polybutadiene having hydroxyl groups at both ends, liquid polyisoprene having hydroxyl groups at both ends, and polybutene. Commercially available liquid resins include, for example, Pripol 2033 (manufactured by Croda Japan), GI-1000, GI-2000, GI-3000, G-1000, G-2000, and G-3000 (manufactured by Nippon Soda Co., Ltd.), Poly-bd R-15HT, and Poly-bd R-45HT, Poly-ip, EPOL (all manufactured by Idemitsu Kosan Co., Ltd.), NOF Polybutene O-15N, NOF Polybutene 3N, NOF Polybutene 10N, NOF Polybutene 30N (all manufactured by NOF Corporation), Nisseki Polybutene Grade LV-7, Grade LV-50, Grade LV-100, Grade HV-15, Grade 35, Grade HV-50, Grade HV-100, Grade HV-300 (all manufactured by ENEOS Corporation), Acrylic O (manufactured by Arakawa Chemical Industries, Ltd.), Outflow UMM-1001, UT-1001, CB-3060, CBB-3098 (all manufactured by Soken Chemical Co., Ltd.), Pro Examples of polyols include Replast 1900, Priplast 1901, Priplast 1838, Priplast 3186, Priplast 3196, Priplast 3197, and Priplast 3199 (all manufactured by Croda Japan Co., Ltd.), Kuraray Polyol P-510, P-1010, P-2010, P-3010, P-4010, P-5010, P-6010, F-510, F-1010, F-2010, F-3010, P-2011, P-520, P-1020, P-2020, P-1012, P-2012, P-530, P-2030, and P-2050 (all manufactured by Kuraray Co., Ltd.).

[0023] The liquid polymerized fatty acid is not particularly limited, but examples thereof include dimer acid, hydrogenated dimer acid, 5 (or 6)-carboxy-4-hexylcyclohex-2-ene-1-octanoic acid, trimer acid, etc. Among these, from the viewpoint of improving solder melting properties, the liquid polymerized fatty acid is preferably 5 (or 6)-carboxy-4-hexylcyclohex-2-ene-1-octanoic acid. Commercially available liquid polymerized fatty acids include, for example, Tsunodyme 205, Tsunodyme 216, Tsunodyme 228, Tsunodyme 395, and Tsunodyme 346 (all manufactured by Tsuno Foods Co., Ltd.), Pripol 1004, Pripol 1009, Pripol 1006, Pripol 1010, Pripol 1013, Pripol 1017, Pripol 1025, and Pripol 1040 (all manufactured by Croda Japan), Haridimer 200, Haridimer 250, Haridimer 300, and Diacid 1550 (all manufactured by Harima Chemicals Co., Ltd.).

[0024] The liquid polymerized compounds can be used alone or in combination. When a plurality of liquid polymerized compounds are used in combination, a single or multiple liquid resins and a single or multiple liquid polymerized fatty acids may be combined, or multiple liquid resins and multiple liquid polymerized fatty acids may be combined separately.

[0025] The content of the liquid polymer compound is not particularly limited, but may be, for example, 1.0% by mass or more and 15.0% by mass or less, or 3.5% by mass or more and 10.0% by mass or less, based on the total amount of the flux. By having the content of the liquid polymer compound within the above range, the solder melting property of the soldering flux and the viscosity stability of the solder paste can be improved.

[0026] The rosin-based resin is not particularly limited as long as it is a known rosin-based resin used as a resin component of flux. Examples include rosin, hydrogenated rosin, polymerized rosin, disproportionated rosin, maleic acid-modified rosin, maleic acid-modified hydrogenated rosin, acrylic acid-modified rosin, acrylic acid-modified hydrogenated rosin, pentaerythritol ester, terpene phenol, and other rosin derivative resins. The rosin-based resins can be used alone or in combination.

[0027] The content of the rosin resin is not particularly limited, but may be, for example, 20% by mass or more and 50% by mass or less, or 25% by mass or more and 45% by mass or less, based on the total amount of the flux. By using a rosin resin content within the above range, the solder melting property of the soldering flux and the viscosity stability of the solder paste can be improved.

[0028] As the resin component, a liquid polymerizable compound and a rosin-based resin may be used in combination, or either one may be used alone. When used alone, it is preferable to use a rosin resin alone from the viewpoint of ease of adjusting the viscosity.

[0029] The total content of the resin components is not particularly limited, but may be, for example, 15% by mass or more and 60% by mass or less, or 20% by mass or more and 55% by mass or less, of the total amount of the flux. By ensuring that the resin component content falls within the above range, the solder melting property of the soldering flux and the viscosity stability of the solder paste can be improved.

[0030] <Isocyanuric Acid Derivative> The flux of this embodiment contains an isocyanuric acid derivative. Examples of the isocyanuric acid derivative include compounds having an isocyanuric skeleton represented by the following general formula 1. Such isocyanuric acid derivatives may be used alone or in combination.

[0031] (In the formula, R １ , R ２ , R ３ are the same or different and represent a hydrogen atom, a carboxyl group, an alkyl group having 1 to 8 carbon atoms, or an organic group represented by -Y-X (wherein Y is an alkylene group, phenylene group, or cycloalkylene group having 1 to 6 carbon atoms, and X is a carboxyl group, a hydroxyl group, an amino group, a halogen atom, a phenyl group, or an organic group containing a phosphorus atom).

[0032] The isocyanuric acid derivatives include bis(2-carboxyethyl)isocyanuric acid (i.e., R １ is a hydrogen atom, R ２ , R ３are the same organic group represented by -Y-X, where Y is an ethylene group and X is a carboxyl group), tris(2-carboxyethyl)isocyanuric acid (i.e., R in general formula (1) １ , R ２ , R ３ are the same organic group represented by -Y-X, where Y is an ethylene group and X is a carboxyl group), tris(2-carboxypropyl)isocyanuric acid (i.e., R in general formula (1) １ , R ２ , R ３ are the same organic groups represented by -Y-X, where Y is a propylene group and X is a carboxyl group), isocyanuric acid (i.e., R in general formula (1) １ , R ２ , R ３ are the same hydrogen atom), tris(2-hydroxyethyl)isocyanuric acid (i.e., R １ , R ２ , R ３ are the same organic group represented by -Y-X, where Y is an ethylene group and X is a hydroxyl group), tris(2,3-dibromopropyl)isocyanuric acid (i.e., R in general formula (1) １ , R ２ , R ３ are the same organic group represented by -Y-X, where Y is a methyl group and X is a dibromoethyl group. The isocyanuric acid derivatives can be used alone or in combination.

[0033] The content of the isocyanuric acid derivative in the flux is not particularly limited, and examples thereof include 0.1% by mass to 10.0% by mass, or 0.5% by mass to 10.0% by mass, or 0.8% by mass to 10.0% by mass, etc. When the resin component is present in the flux together with the cellulose fibers at a content within the above range, the occurrence of blowholes and side balls can be suppressed when the flux is used as a solder material.

[0034] <Cellulose Fibers> The flux of this embodiment contains cellulose fibers. The cellulose fibers are fibrous celluloses made from various types of cellulose, such as methyl cellulose, ethyl cellulose, and hydroxyethyl cellulose. The cellulose fibers are not particularly limited, but examples include cellulose fibers called "microfibrillated cellulose (MFC)." Microfibrillated cellulose, also known as "cellulose microfiber (CMF)," is a cellulose aggregate composed of a mixture of fibrous cellulose with a length of 1 μm or more and less than 1 mm and fibrous cellulose with a length of 1 nm or more and less than 1 μm. Cellulose microfibers are obtained by subjecting various cellulose raw materials to mechanical and chemical treatments to increase the specific surface area and adjust the diameter and length of the fibers. The raw material for the cellulose microfibers is any cellulose material, including, but not limited to, natural materials such as wood and chemically synthesized cellulose fibers. The cellulose aggregates in the flux of this embodiment include powdered cellulose aggregates composed of entangled fine fibers of different lengths.

[0035] The cellulose fibers contained in the flux of this embodiment may be commercially available, such as Exilva P01-V, P01-L, F01-V, and F01-L (all manufactured by Borregaard) and BiNFi-s (manufactured by Sugino Machine Ltd.).

[0036] The flux of this embodiment may contain the cellulose fibers in an amount of 0.1% by mass to 10.0% by mass, or 0.1% by mass to 8.0% by mass, or 0.5% by mass to 8.0% by mass, etc., relative to the entire flux. When the cellulose fibers are present in the flux together with the isocyanuric acid derivative in the above-mentioned range, the occurrence of blowholes and side balls can be suppressed when the flux is used as a solder material.

[0037] The flux of this embodiment contains both the isocyanuric acid derivative and the cellulose fiber. The presence of the cellulose fiber facilitates flux aggregation, while the isocyanuric acid derivative improves solder fluidity. As a result, the occurrence of side balls and blowholes is more easily suppressed. In other words, the flux's tendency to aggregate facilitates the flux's expulsion (ejection) from the solder material during heating, thereby suppressing the formation of blowholes. At the same time, the shape of the solder fillet is improved, making it easier to suppress the formation of side balls. In addition, the improved solder fluidity facilitates solder aggregation during heating, resulting in a more favorable shape of the solder fillet, making it easier to suppress the formation of side balls. In particular, metals such as indium (In), antimony (Sb), and bismuth (Bi) are known as metals added to high-durability solder alloys because they improve the durability of the solder. However, solder materials using such solder alloys have the drawback of easily reducing the solder fluidity. Even when the flux of the present embodiment is used for a solder material that uses such a highly durable solder alloy, the above-described action enables the formation of a good fillet with few or no blowholes and the suppression of side ball formation.

[0038] <Hydroiodide Salt> The flux of this embodiment may further contain a hydroiodide salt (hereinafter simply referred to as hydroiodide salt) of an amine compound selected from the group consisting of aliphatic amines, alicyclic amines, aromatic amines, heterocyclic amines, and aromatic guanidines. The inclusion of these hydroiodide salts in the flux of this embodiment makes it easier to suppress the occurrence of voids during soldering. Examples of amine compounds for the hydroiodide salt include aliphatic amines (e.g., diethanolamine, triethanolamine, ethylhexylamine), alicyclic amines (e.g., cyclohexylamine, dicyclohexylmethylamine), aromatic amines (e.g., aniline, diethylaniline, diphenylguanidine), heterocyclic amines (e.g., pyridine, picoline, lutidine, piperidine), and aromatic guanidines (e.g., 1,3-di-o-tolylguanidine).

[0039] Specific examples of hydroiodides of amine compounds include, but are not limited to, 2-ethylhexyl hydroiodide, ethylenediamine dihydroiodide, diethanolamine hydroiodide, triethanolamine hydroiodide, cyclohexylamine hydroiodide, aniline hydroiodide, diethylaniline hydroiodic acid, pyridine hydroiodide, diphenylpyridine hydroiodide, guanidine hydroiodide, and o-tolylguanidine hydroiodide.

[0040] The flux of the present embodiment may contain, for example, the hydroiodide in an amount of 0.05 mass % or more and 5.0 mass % or less, or 0.1 mass % or more and 3.0 mass % or less. When the content of the hydroiodide is within the above range, the occurrence of side balls and blowholes can be more easily suppressed.

[0041] <Activator> The flux of the present embodiment may contain an activator (other than the above-mentioned isocyanuric acid derivatives and hydroiodides) as an optional component. The activator is not particularly limited, but examples thereof include organic acid activators, amine compounds, amino acids, and complex salts thereof, and halogen-based activators.

[0042] The organic acid surfactant is not particularly limited, but 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, phenylsuccinic 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.

[0043] The amine compound is not particularly limited, but examples thereof include imidazole compounds, triazole compounds, etc. Examples of the imidazole 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, 2,4-diamino-6-(2'-undecyl-imidazolyl)-ethyl-s-triazine, 1-butylimidazole, 2-phenylimidazole, and 4-methyl-2-phenylimidazole.

[0044] Examples of the triazole compounds include benzotriazole, 1H-benzotriazole-1-methanol, 1-methyl-1H-benzotriazole, etc. Examples of other amine compounds include 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, 1,3-diphenylguanidine, etc.

[0045] The amino acid is not particularly limited, and examples thereof include N-acetylphenylalanines such as N-acetyl-L-phenylalanine, N-acetyl-DL-phenylalanine, and N-acetyl-D-phenylalanine; N-acetylglutamic acids such as N-acetyl-L-glutamic acid; N-acetylglycine; N-acetylleucines such as N-acetyl-L-leucine, N-acetyl-DL-leucine, and N-acetyl-D-leucine; and N-acetylphenylglycines such as N-acetyl-N-phenylglycine, N-acetyl-L-phenylglycine, and N-acetyl-DL-phenylglycine.

[0046] The halogen-based activator is not particularly limited, and examples thereof include amine halogen salts and halogen compounds. Examples of amines in the amine halogen salts include diethylamine, dibutylamine, tributylamine, diphenylguanidine, and cyclohexylamine. Examples of halogens in the 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.

[0047] The activator may be used alone or in combination. The content of the solvent in the flux is not particularly limited, but may be, for example, 0.5% by mass to 10% by mass, 1.0% by mass to 7.0% by mass, or 2.0% by mass to 5.0% by mass, based on the total mass of the flux.

[0048] The flux of this embodiment may contain a thixotropic component as an optional component. The thixotropic component is not particularly limited, but examples include components used as thixotropic components in fluxes, such as fatty acid amides, aromatic ring-containing polyamide compounds, hydrogenated castor oil, oxyfatty acids, and wax. The thixotropic component may be used alone or in combination. The content of the thixotropic component in the flux is not particularly limited, but examples include 1.0% by mass to 10.0% by mass, or 2.0% by mass to 7.0% by mass, based on the total flux.

[0049] <Antioxidant> The flux of this embodiment may contain an antioxidant as an optional component. The antioxidant is not particularly limited, but examples include phenolic antioxidants such as hindered phenolic antioxidants, triazole antioxidants such as aminotriazole antioxidants, benzotriazole antioxidants, and mercaptotriazole antioxidants, and phosphorus-based antioxidants such as triphenyl phosphite, triethyl phosphite, trilauryl trithiophosphate, and tris(tridecyl) phosphite. The antioxidants may be used alone or in combination. The content of the antioxidant in the flux is not particularly limited, but examples include 0.05% by mass to 3.0% by mass, or 0.1% by mass to 1.5% by mass, based on the total flux.

[0050] The flux of this embodiment may further contain other additives. Examples of other additives include a thickener and an antifoaming agent. These components can be blended into the flux as needed, and any of the components may or may not be included.

[0051] Second Embodiment: Solder Material The solder material of this embodiment is a solder material containing the flux of the first embodiment and a solder alloy.

[0052] The solder material of this embodiment may be a solder material such as solder paste or solder flux.

[0053] <Solder Alloy> The solder material of this embodiment includes a solder alloy. The solder alloy is not particularly limited as long as it is an alloy used for soldering, and examples thereof include lead-free solder alloys and lead-containing solder alloys. Lead-free solder alloys are preferred from the viewpoint of environmental impact.

[0054] Specific examples of lead-free solder alloys include alloys containing tin (Sn), silver (Ag), copper (Cu), antimony (Sb), indium (In), cobalt (Co), nickel (Ni), zinc (Zn), bismuth (Bi), etc. More specific examples include alloys such as Sn / Ag, Sn / Ag / Cu, Sn / Ag / Cu / Sb / In / Co, Sn / Ag / Cu / In / Ni, Sn / Ag / Cu / Bi / Ni, Sn / Cu, Sn / Ag / Bi, Sn / Ag / Bi / Ni, Sn / Ag / Bi / In, Sn / Ag / Cu / Bi / In, Sn / Bi, Sn / Sb, Sn / Zn / Bi, Sn / Zn, Sn / Zn / Al, Sn / Ag / Cu / Bi / In / Sb, and In / Sn. The alloy may also contain unavoidable impurities. "Avoidable impurities" refers to components that are inevitably mixed in during the manufacturing process and are acceptable as long as they do not affect the effects of the flux and solder material of this embodiment. Adding indium (In), antimony (Sb), bismuth (Bi), etc. to the solder alloy improves the durability of the solder. On the other hand, the addition of these metals widens the liquidus-solidus line width of the solder alloy, making it more likely that soldering defects, such as small solder lumps called "side balls" on the sides of the chip or holes called "blowholes" at the solder fillet, will occur after soldering using a solder material such as solder paste. The flux of this embodiment has the advantage of being particularly effective in suppressing the occurrence of side balls and blowholes when used with a solder material containing a solder alloy containing indium (In), antimony (Sb), or bismuth (Bi). Therefore, solder materials containing these metals as solder alloys are suitable examples of the solder material of this embodiment.

[0055] The content of the solder alloy in the solder material is not particularly limited, but may be, for example, 80% by mass or more and 95% by mass or less, and preferably 85% by mass or more and 90% by mass or less.

[0056] When the solder material in this embodiment is a solder paste obtained by mixing a solder alloy with the flux of this embodiment, it is preferable that the solder alloy and the flux be mixed in an amount of 80% by mass or more and 95% by mass or less, and 5% by mass or more and 20% by mass or less, for example.

[0057] The conditions for using the solder material of this embodiment can be set appropriately depending on the objects to be soldered, etc., and are not particularly limited. For example, the conditions include a temperature rise rate during preheating of 1.0 to 3.0°C / second, a preheat temperature of 130 to 170°C for 60 to 100 seconds, a temperature rise rate during solder melting of 1.0 to 2.0°C / second, a melting temperature of 219°C or higher for 30 seconds or more, and a reflow peak temperature of 230 to 250°C.

[0058] The solder material of this embodiment is suitable for electrical connection of all electronic components, particularly in-vehicle and outdoor displays, mobile phones, etc. In particular, this solder material is likely to suppress the occurrence of side balls and blowholes that tend to occur in solder materials containing solder alloys with enhanced durability, such as those described above, that contain indium (In), antimony (Sb), bismuth (Bi), etc., and is therefore likely to suppress various soldering defects.

[0059] The flux and solder material according to the present embodiment are as described above, but the embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims rather than the above description, and it is intended to include all modifications within the meaning and scope of the claims.

[0060] Next, examples of the present invention will be described together with comparative examples, but the present invention should not be construed as being limited to the following examples.

[0061] (Preparation of Flux) The fluxes used in the Examples and Comparative Examples were prepared using the materials shown in Table 1 and the compositions shown in Tables 2 to 5. Each flux was prepared by placing each material in an appropriate container, heating it to around 180°C, and mixing and dispersing it until all the materials were uniformly dissolved. The numerical values ​​for the components in the tables are in weight percent.

[0062]

[0063]

[0064]

[0065]

[0066]

[0067] (Preparation of Solder Paste) Each flux was mixed with a solder alloy powder shown in Table 6 to prepare a paste-like solder material (solder paste). Each flux and each solder alloy powder were mixed in a ratio of 12.0 mass % flux and 88.0 mass % solder alloy.

[0068]

[0069] (Test Piece) A copper-clad laminate measuring 100 mm x 100 mm and 1.6 mm thick was prepared as the test piece. The pad portion (a rectangular shape measuring 1.0 mm x 1.5 mm) was surface-treated with a water-soluble preflux (product name: Tough Ace F2, manufactured by Shikoku Chemical Industry Co., Ltd.). The solder paste of each Example and Comparative Example was applied to this board. The application method involved first placing 300 g of each solder paste on a metal mask (metal mask thickness: 120 μm, print opening shape: rectangular, print opening size: 1.0 mm x 1.5 mm) set in a printing machine, and rolling four times to ensure the solder paste was absorbed into the metal mask. After dry-cleaning the back of the metal mask, the solder paste was printed. Using a mounter, a chip component (3216R, 3.2 mm x 1.6 mm) was placed on the pad portion and heated in a reflow furnace. The printing and heating conditions are shown below.

[0070] [Printing conditions] Printer: YSP (Yamaha Motor Co., Ltd.) Printing squeegee: Metal squeegee Squeegee angle: 55° Metal mask thickness: 120 μm Printing speed: 40 mm / sec Printing pressure: 50 N Environment: 24°C to 26°C, 50% to 60% RH [Heating conditions] Mounter: YSP YAMAHA Motor (YAMAHA Motor Co., Ltd.) Reflow oven: NJ0611M-102-LRF (Atec Techtron Co., Ltd.) - Preheating Heating rate: 1.0 to 3.0°C / sec Preheating temperature: 130 to 170°C / 60 to 100 seconds Heating environment: Air - Solder melting Heating rate: 1.0 to 2.0°C / sec Solder melting time: 219°C or higher, 30 seconds Peak temperature: 230 to 250°C Heating environment: Air

[0071] (Blowholes) Ten randomly selected locations on the part where each test piece manufactured using the above-mentioned Examples and Comparative Examples was mounted were photographed using X-rays. The number of voids appearing in the fillet of the chip was counted. Figure 1 shows a photograph of the fillet where blowholes occurred. The areas circled in the figure are blowholes.

[0072] (Side-chip balls) The part of each test piece prepared using the above-mentioned Examples and Comparative Examples where a component was mounted was visually observed using a stereomicroscope (magnification: 1.5x), and the number of side-chip balls that had occurred beside the component was counted. Figure 2 shows a photograph of the part beside where a side-chip ball had occurred. The area circled in the figure is the side-chip ball.

[0073] (Evaluation) For blowholes, the number of parts with blowholes (number out of 10) was counted. For side balls, the total number of side balls that occurred around all parts (N number 10) was counted. Based on the counting results, evaluation was performed according to the criteria shown in Table 7.

[0074]

[0075] As shown in Tables 2 to 4, in each of the Examples, the occurrence of both blow holes and side chip balls was suppressed, and there were no C ratings (failure). On the other hand, as shown in Table 5, in each of the Comparative Examples, either or both of blow holes and side chip balls were rated C (failure).

Claims

1. A soldering flux comprising a solvent component, a resin component, an isocyanuric acid derivative, and cellulose fibers.

2. The soldering flux according to claim 1, further comprising a hydroiodide salt of at least one amine compound selected from the group consisting of aliphatic amines, alicyclic amines, aromatic amines, heterocyclic amines, and aromatic guanidines.

3. The soldering flux according to claim 1 or 2, containing 0.1 mass % or more and 10.0 mass % or less of the isocyanuric acid derivative.

4. The soldering flux according to claim 1 or 2, containing 0.1% by mass or more and 10.0% by mass or less of the cellulose fibers.

5. A soldering flux according to claim 1 or 2, wherein the cellulose fibers comprise a lump of cellulose in which fibrous cellulose having a length of 1 μm or more but less than 1 mm and fibrous cellulose having a length of 1 nm or more but less than 1 μm are mixed.

6. A solder material comprising the soldering flux according to claim 1 or 2 and a solder alloy.

7. The solder material of claim 6, wherein the solder alloy comprises at least one metal selected from the group consisting of tin (Sn), silver (Ag), copper (Cu), antimony (Sb), indium (In), cobalt (Co), and nickel (Ni).

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