Soldering flux and soldering materials

Abstract

To provide a solder flux and a solder material that are able to prevent deterioration in the bondability and electrical reliability of solder bonding.SOLUTION: A solder flux includes a solvent component, a resin component, an isocyanuric acid derivative and a cellulose fiber.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to solder flux and solder material using the same. [Background technology]

[0002] Solder used for joining electronic components consists of solder material including solder alloy and flux. Flux is added to improve solderability and contains various components such as resin components, activators, solvents, antioxidants, and thixotropic components (also called thixotropic agents). Including activators in the flux suppresses oxidation and migration of metal surfaces. Various activators have been investigated to obtain flux with improved oxide film removal capabilities.

[0003] For example, Patent Documents 1 and 2 disclose fluxes that have high oxide film removal properties by containing an isocyanuric acid derivative as an activating agent component. Specifically, Patent Document 1 discloses a flux that can maintain high oxide film removal properties even when solder balls and solder paste are rejoined after being separated once due to deformation of the substrate during heating. Patent Document 2 discloses a flux that does not easily reduce solder meltability even for fine pads on the surface of an electronic circuit board.

[0004] Furthermore, when soldering electronic components and other joining parts to an electronic circuit board, the solder material is heated to a high temperature (reflow) to melt the solder. Some of the components in the flux contain compounds that generate gas when heated, and voids due to such gases may occur at the solder joint. In addition, some components in the flux may volatilize and generate gas, causing the flux and solder balls in the solder material to scatter. As a technique to prevent voids and scattering due to such gas volatilization, a flux containing a specific cellulose is disclosed in Patent Documents 3 and 4.

[0005] On the other hand, in recent years, in order to improve the durability of solder, indium (In), antimony (Sb), bismuth (Bi), etc. have been added to solder alloys in addition to conventional tin (Sn), silver (Ag), copper (Cu), etc. However, the addition of these metals widens the liquidus-solidus line width of the solder alloy, which can lead to problems such as soldering defects. These defects include the formation of small solder clumps called side balls next to the tip after soldering using solder paste or other soldering materials, or the formation of holes called blowholes at the solder fillet. Side balls can lead to short circuits. Blowholes can distort the shape of the solder fillet, potentially leading to a decrease in solder durability. Consequently, these soldering defects can reduce the bondability and electrical reliability of the solder joint. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Patent No. 6528102 [Patent Document 2] Patent No. 6899173 [Patent Document 3] International Public Gazette WO2022 / 138755 [Patent Document 4] International Public Gazette WO2022 / 138756 [Overview of the project] [Problems that the invention aims to solve]

[0007] This invention has been made in view of the problems of the prior art described above, and aims to provide a soldering flux and soldering material that can suppress the deterioration of solder joint properties and electrical reliability. [Means for solving the problem]

[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 contain 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 mass% or more and 10.0 mass% or less.

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

[0012] In the present invention, the cellulose fibers may include aggregated 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 solder material according to the present invention includes any one of the above soldering fluxes and a solder alloy.

[0014] In the solder material according to the present invention, 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). [Advantageous Effects of Invention]

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

[0016] [Figure 1] Figure 1 shows a photograph of a fillet portion where blowholes have occurred. [Figure 2] Figure 2 shows a photograph of the side of a component where side chip balls have occurred. [Modes for carrying out the invention]

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

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

[0019] <Solvent components> The solvent component included in the flux of this embodiment is not particularly limited as long as it is a known component used as a solvent component of flux. Examples include 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, tributyl acetyl 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 aforementioned solvents can be used individually or in combination of multiple types.

[0020] The content of the solvent component in the flux is not particularly limited, but examples include 20% to 70% by mass or 30% to 60% by mass of the total flux amount. Having the solvent content within the above range allows each component to be uniformly present in the liquid. Furthermore, when used in soldering materials such as solder paste, it becomes easier to adjust the viscosity to a suitable range that is easy to handle.

[0021] <Resin components> The resin component included in the flux of this embodiment is not particularly limited as long as it is a known component used as a resin component of flux. Examples include liquid polymerization compounds, rosin, and rosin-based resins which are derivatives of rosin.

[0022] Examples of liquid polymerization compounds include liquid resins and liquid polymerization fatty acids. The liquid resin is not particularly limited, but examples include dimer ol, hydrogenated polybutadiene with hydroxyl groups at both ends (hydroxyl-terminated liquid polybutadiene), liquid polybutadiene with hydroxyl groups at both ends (hydroxyl-terminated liquid polybutadiene), liquid polyisoprene with hydroxyl groups at both ends (hydroxyl-terminated liquid polyisoprene), polybutene, acrylic resin, polyester polyol resin, etc. Among these, the liquid resin may be at least one selected from the group consisting of hydrogenated polybutadiene with hydroxyl groups at both ends, liquid polyisoprene with hydroxyl groups at both ends, and polybutene. Examples of commercially available liquid resins include, for example, Prepol 2033 (manufactured by Croda Japan Co., Ltd.), GI-1000, GI-2000, GI-3000, G-1000, G-2000, G-3000 (manufactured by Nippon Soda Co., Ltd.), Poly-bd R-15HT, 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), Nippon Oil 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.), P Examples include Replast 1900, Preplast 1901, Preplast 1838, Preplast 3186, Preplast 3196, Preplast 3197, Preplast 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, P-2050 (all manufactured by Kuraray Co., Ltd.).

[0023] The aforementioned liquid polymerized fatty acid is not particularly limited, but examples include dimer acid, hydrogenated dimer acid, 5(or 6)-carboxy-4-hexylcyclohexa-2-ene-1-octanoic acid, trimer acid, etc. Among these, 5(or 6)-carboxy-4-hexylcyclohexa-2-ene-1-octanoic acid is preferred as the liquid polymerized fatty acid from the viewpoint of improving solder meltability. Examples of commercially available liquid polymerized fatty acids include TsunoDyme 205, TsunoDyme 216, TsunoDyme 228, TsunoDyme 395, TsunoDyme 346 (all manufactured by Tsukuno Foods Co., Ltd.), Pripol 1004, Pripol 1009, Pripol 1006, Pripol 1010, Pripol 1013, Pripol 1017, Pripol 1025, Pripol 1040 (all manufactured by Croda Japan Co., Ltd.), Halidamer 200, Halidamer 250, Halidamer 300, and Diacid 1550 (all manufactured by Harima Chemicals Co., Ltd.).

[0024] The liquid polymerization compounds can be used alone or in combination of multiple compounds. When combining multiple compounds, one or more liquid resins and one or more liquid polymerization fatty acids may be combined, or multiple liquid resins and multiple liquid polymerization fatty acids may be combined separately.

[0025] The content of the liquid polymerization compound is not particularly limited, but examples include 1.0% to 15.0% by mass of the total flux, or 3.5% to 10.0% by mass. By having a liquid polymerization compound content within the above range, the solder meltability of the solder 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, and rosin derivative resins such as pentaerythritol ester. The rosin-based resin can be used alone or in combination of several types.

[0027] The content of the rosin-based resin is not particularly limited, but examples include 20% to 50% by mass or 25% to 45% by mass of the total flux. By having a rosin-based resin content within the above range, the solder meltability of the solder flux and the viscosity stability of the solder paste can be improved.

[0028] The resin component may be a combination of a liquid polymerization compound and a rosin-based resin, or either one may be used. When used alone, using rosin resin alone is preferable from the viewpoint of ease of viscosity adjustment.

[0029] The total content of resin components is not particularly limited, but examples include 15% to 60% by mass or 20% to 55% by mass of the total flux. Having resin component content within the above range allows for good solder meltability of the solder flux and viscosity stability of the solder paste.

[0030] <Isocyanuric acid derivatives> 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 individually or in combination of multiple types.

[0031] [ka] (In the formula, R 1 , R2 , R 3 are identical or different, and each represents 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 an organic group containing a carboxyl group, a hydroxyl group, an amino group, a halogen atom, a phenyl group or a phosphorus atom.).)

[0032] Examples of the isocyanuric acid derivative include bis(2-carboxyethyl)isocyanuric acid (that is, R in the general formula (1) 1 is a hydrogen atom, R 2 , R 3 are the same organic group represented by -Y-X, Y is an ethylene group, and X is a carboxyl group), tris(2-carboxyethyl)isocyanuric acid (that is, R in the general formula (1) 1 , R 2 , R 3 are the same organic group represented by -Y-X, Y is an ethylene group, and X is a carboxyl group), tris(2-carboxypropyl)isocyanuric acid (that is, R in the general formula (1) 1 , R 2 , R 3 are the same organic group represented by -Y-X, Y is a propylene group, and X is a carboxyl group), isocyanuric acid (that is, R in the general formula (1) 1 , R 2 , R 3 are the same hydrogen atom), tris(2-hydroxyethyl)isocyanuric acid (that is, R in the general formula (1) 1 , R 2 , R 3 are the same organic group represented by -Y-X, Y is an ethylene group, and X is a hydroxyl group), tris(2,3-dibromopropyl)isocyanuric acid (that is, R in the general formula (1) 1 , R 2 , R 3 are the same organic group represented by -Y-X, Y is a methyl group, and X is a dibromoethyl group), and the like. The aforementioned isocyanuric acid derivatives may be used alone or as a mixture of two or more types.

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

[0034] <Cellulose fiber> The flux in this embodiment contains cellulose fibers. The cellulose fibers are fibrous cellulose composed of various types of cellulose, such as methylcellulose, ethylcellulose, and hydroxyethylcellulose. While there are no particular limitations on the cellulose fibers used, one example is a cellulose fiber called "microfibrillated cellulose (MFC)." Microfibrillated cellulose, also known as "cellulose microfiber (CMF)," is a lump of cellulose in which fibrous cellulose with a length of 1 μm to less than 1 mm and fibrous cellulose with a length of 1 nm to less than 1 μm are mixed. Cellulose microfibers can be obtained by increasing the specific surface area and adjusting the diameter and length of the fibers by applying mechanical and chemical treatments to various cellulose raw materials. The raw materials for cellulose microfibers are any cellulose material, and are not particularly limited, such as natural materials like wood or chemically synthesized cellulose fibers. Examples of lump cellulose in the flux of this embodiment include powdered lump cellulose in which fine fibers of different lengths are intertwined.

[0035] The cellulose fibers contained in the flux of this embodiment may be obtained from commercially available sources. Examples include Exilva P01-V, P01-L, F01-V, F01-L (all manufactured by Borregard), and BiNFi-s (manufactured by Sugino Machine Co., Ltd.).

[0036] The flux of this embodiment may contain cellulose fibers in an amount of 0.1% to 10.0% by mass, or 0.1% to 8.0% by mass, or 0.5% to 8.0% by mass, relative to the total flux. The presence of cellulose fibers within the above ranges, together with the isocyanuric acid derivative in the flux, can suppress the generation of blowholes and side balls when used as a soldering material.

[0037] The flux of this embodiment contains both the isocyanuric acid derivative and the cellulose fibers. The presence of the cellulose fibers makes the flux more likely to aggregate, while the action of the isocyanuric acid derivative improves the fluidity of the solder. As a result, it becomes easier to suppress the formation of side balls and blowholes. In other words, when the flux aggregates easily, it helps to expel (leak) the flux from the solder material during heating, which suppresses the formation of blowholes and at the same time improves the shape of the solder fillet, making it easier to suppress the formation of side balls. Furthermore, the improved fluidity of the solder makes it easier for the solder to aggregate during heating, resulting in a better shape of the solder fillet and making it easier to suppress the formation of side balls. In particular, metals such as indium (In), antimony (Sb), and bismuth (Bi) are known to be added to highly durable solder alloys because they improve the durability of the solder. However, solder materials using such solder alloys have the drawback that the fluidity of the solder tends to decrease. Even when the flux of this embodiment is used with solder materials using such highly durable solder alloys, the above-described effects enable the formation of good fillets with few or no blowholes, and suppression of side ball formation.

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

[0039] Specifically, examples of amine compound hydroiodides include, but are not limited to, 2-ethylhexyl hydroiodide, ethylenediamine hydroiodide, diethanolamine hydroiodide, triethanolamine hydroiodide, cyclohexylamine hydroiodide, aniline hydroiodide, diethylaniline hydroiodide, diphenylgpyridine hydroiodide, anidine hydroiodide, and o-tolylguanidine hydroiodide.

[0040] The flux of this embodiment may contain, for example, 0.05% to 5.0% by mass of the hydroiodide salt, or 0.1% to 3.0% by mass. Having the hydroiodide salt content within this range makes it easier to suppress the occurrence of side balls and blowholes.

[0041] <Activating agent> The flux of this embodiment may contain an activator (other than the isocyanuric acid derivative and hydroiodide salts mentioned above) as an optional component. The activator is not particularly limited, but examples include organic acid-based activators, amine-based compounds, amino acids and their complex salts, halogen-based activators, and the like.

[0042] Examples of organic acid-based surfactants are not limited to these, but include monocarboxylic acids such as lauric acid, myristic acid, pentadecyl acid, palmitic acid, margaric acid, stearic acid, tubercurostearic 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 compounds are not particularly limited, but examples include imidazole compounds and triazole compounds. 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-triazine-2-yl)ethyl-2-undecylimidazole, 2,4-diamino-6-(2'-undecylimidazolyl)-ethyl-s-triazine, 1-butylimidazole, 2-phenylimidazole, and 4-methyl-2-phenylimidazole.

[0044] Examples of the aforementioned triazole 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, pyrazineamide, N-phenylglycine, 3-methyl-5-pyrazolone, N-lauroyl sarcosine, and 1,3-diphenylguanidine.

[0045] The amino acids are not particularly limited, but examples 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), or N-acetylphenylglycine (N-acetyl-N-phenylglycine, N-acetyl-L-phenylglycine, N-acetyl-DL-phenylglycine), etc.

[0046] The halogenated activators are not particularly limited and include, for example, amine halogen salts and halogen compounds. 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.

[0047] The activator can be used alone or in a mixture of several types. The content of the solvent in the flux is not particularly limited, but examples include 0.5% by mass or more and 10% by mass or 1.0% by mass or more and 7.0% by mass or 2.0% by mass or more and 5.0% by mass or less relative to the total 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 fatty acid amides, aromatic ring-containing polyamide compounds, hydrogenated castor oil, oxy fatty acids, waxes, and other components used as thixotropic components in flux. The thixotropic component can be used alone or in a mixture of several types. The content of the thixotropic component in the flux is not particularly limited, but examples include 1.0% to 10.0% by mass or 2.0% to 7.0% by mass relative to 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 phenol antioxidants, triazole antioxidants such as aminotriazole antioxidants, benzotriazole antioxidants, and mercaptotriazole antioxidants, and phosphorus antioxidants such as triphenylphosphite, triethylphosphite, trilauryltrithiophosphae, and tris(tridecyl)phosphite. The antioxidant can be used alone or in combination of multiple types. The content of the antioxidant in the flux is not particularly limited, but examples include 0.05% to 3.0% by mass, or 0.1% to 1.5% by mass, relative to the total flux.

[0050] The flux of this embodiment may further contain other additives. Examples of other additives include thickeners and defoamers. Furthermore, these components can be incorporated into the flux as needed, and the presence or absence of any of these components is optional.

[0051] (Second embodiment: Solder material) The solder material of this embodiment is a solder material comprising the flux and solder alloy of the first embodiment described above.

[0052] Examples of soldering materials in this embodiment include solder paste and rosin-cored solder.

[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 include lead-free solder alloys and leaded solder alloys. Lead-free solder alloys are preferred from the viewpoint of environmental impact.

[0054] Specifically, 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 specifically, 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. Furthermore, these alloys may contain unavoidable impurities. Unavoidable impurities are components that are inevitably mixed in during the manufacturing process and are acceptable to the extent that 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 soldering defects more likely to occur, such as small solder clumps called side balls next to the tip or holes called blowholes at the solder fillet after soldering with solder paste or other soldering materials. The flux of this embodiment has the advantage of being particularly effective in suppressing the occurrence of side balls and blowholes when used with solder materials containing solder alloys containing indium (In), antimony (Sb), and bismuth (Bi). Therefore, solder materials containing these metals as solder alloys are suitable examples of solder materials in this embodiment.

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

[0056] In this embodiment, if the solder material is a solder paste obtained by mixing a solder alloy and the flux of this embodiment, it is preferable that the mixture consists of, for example, 80% to 95% by mass of the solder alloy and 5% to 20% by mass of the flux.

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

[0058] The solder material of this embodiment is suitable for electrical connections of all electronic components, particularly automotive, outdoor displays, mobile phones, and the like. In particular, it is a solder material that easily suppresses the occurrence of side balls and blowholes, which tend to occur in solder materials containing durable solder alloys such as indium (In), antimony (Sb), and bismuth (Bi), and thus easily suppresses various soldering defects.

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

[0060] Next, embodiments of the present invention will be described together with comparative examples. However, the present invention is not limited to the embodiments described below.

[0061] (Preparation of flux) Fluxes for each example and comparative example were prepared using the materials shown in Table 1 and the formulations shown in Tables 2-5. The preparation method involved placing each material in a suitable container, heating to approximately 180°C, and mixing and dispersing until all materials were uniformly dissolved to obtain each flux. Note that the numerical values ​​for the components in the tables are in weight percent.

[0062] [Table 1]

[0063] [Table 2]

[0064] [Table 3]

[0065] [Table 4]

[0066] [Table 5]

[0067] (Preparing solder paste) Each flux was mixed with the solder alloy powder listed in Table 6 to prepare a paste-like solder material (solder paste). The flux and solder alloy powder were mixed in a ratio of 12.0% by mass of flux to 88.0% by mass of solder alloy.

[0068] [Table 6]

[0069] (Test piece) For the test pieces, we prepared copper-clad laminate measuring 100mm x 100mm with a thickness of 1.6mm, and used pieces in which the pad portion (a rectangle measuring 1.0mm x 1.5mm) was surface-treated with water-soluble preflux (product name ToughAce F2, manufactured by Shikoku Chemicals Co., Ltd.). Solder paste for each example and comparative example was applied to this substrate. The application method involved first placing 300g of each solder paste onto a metal mask (metal mask thickness 120μm, printing area opening shape: rectangular, printing area opening size: 1.0mm x 1.5mm) set up on the printing press, and rolling it four times to allow the solder paste to adhere to the metal mask. After dry cleaning the back of the metal mask, the solder paste was printed. Using a mounter, a chip component (3216R, 3.2mm x 1.6mm) was placed on the pad area and heated in a reflow oven. The printing and heating conditions are shown below.

[0070] [Printing conditions] Printing machine: YSP (manufactured by Yamaha Motor Co., Ltd.) Printing squeegee: Metal squeegee Squeegee angle: 55° Metal mask thickness: 120 μm Printing speed: 40mm / sec Printing pressure: 50N Environment: 24℃~26℃, 50%~60%RH [Heating conditions] Mounter: YSP YAMAHA Motor (manufactured by Yamaha Motor Co., Ltd.) Reflow oven: NJ0611M-102-LRF (manufactured by Aitech Tectron Co., Ltd.) • During preheating Heating rate: 1.0~3.0℃ / second Preheat temperature: 130-170°C / 60-100 seconds Heating environment: atmospheric atmosphere • When solder melts Heating rate: 1.0~2.0℃ / second Solder melting time: 219° or higher, 30 seconds Peak temperature: 230~250℃ Heating environment: atmospheric atmosphere

[0071] (Blowhole) Ten arbitrary locations on the parts mounted on each test piece prepared using the above-described examples and comparative examples were photographed with X-rays. The number of voids appearing in the fillet portion of the tip was counted. Figure 1 shows a photograph of the fillet portion where blowholes occurred. The areas circled in the figure are blowholes.

[0072] (Side tip ball) The parts mounted on each test piece prepared using the above-described examples and comparative examples were visually observed using a stereomicroscope (magnification: 1.5x), and the number of side chip balls that had formed next to the parts was counted. Figure 2 shows a photograph of the area next to the parts where side chip balls had formed. The areas circled in the figure are the side chip balls.

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

[0074] [Table 7]

[0075] As shown in Tables 2 to 4, in each embodiment, the occurrence of both blowholes and side chip balls was suppressed, and there were no C (unacceptable) ratings. On the other hand, as shown in Table 5, in each comparative example, either blowholes or side chip balls, or both, received a C (unacceptable) rating.

Claims

1. It contains a solvent component, a resin component, an isocyanuric acid derivative, and cellulose fibers. The isocyanuric acid derivative is contained in an amount of 0.1% by mass or more and 10.0% by mass or less. A soldering flux containing 0.1% by mass or more and 10.0% by mass or less of the aforementioned cellulose fibers, A soldering flux used with soldering materials that include a solder alloy containing tin (Sn) and at least one metal selected from the group consisting of silver (Ag), copper (Cu), antimony (Sb), indium (In), cobalt (Co), and nickel (Ni).

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, wherein the cellulose fibers include fibrous cellulose with a length of 1 μm or more and less than 1 mm and lump cellulose in which fibrous cellulose with a length of 1 nm or more and less than 1 μm are mixed.

4. A solder material comprising the soldering flux and solder alloy according to claim 1 or 2, wherein the solder alloy comprises tin (Sn) and at least one metal selected from the group consisting of silver (Ag), copper (Cu), antimony (Sb), indium (In), cobalt (Co), and nickel (Ni).

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