TW202308838A - Solder paste and method for manufacturing electronic device - Google Patents

Abstract

A solder paste according to the present invention contains a flux composition and a solder powder and is configured such that, with respect to a flux residue that is obtained from this solder paste in accordance with a specific production procedure, if G'100 is the storage elastic modulus thereof at 100 DEG C and G"100 is the loss elastic modulus thereof at 100 DEG C as determined under specific measurement conditions with use of a rheometer, G'100 and G"100 satisfy G'100 > G"100.

Description

Solder paste and manufacturing method of electronic device

The invention relates to a manufacturing method of a solder paste and an electronic device.

Heretofore, various developments have been made on solder pastes. As such a technique, the technique described in patent document 1 is known, for example. Patent Document 1 describes a solder paste containing a rosin-based resin having a softening point of 90° C. or lower. prior art literature patent documents

Patent Document 1: Japanese Patent Application Laid-Open No. 2018-140429

[Problem to be Solved by the Invention]

However, as a result of the inventor's research, it has been found that the solder paste described in Patent Document 1 has room for improvement in terms of high-temperature migration. [Technical means to solve the problem]

In recent years, as the output of devices has increased, the temperature during device operation has also reached a high temperature of 100°C or higher. The inventors of the present invention conducted research in view of the above-mentioned development situation, and found that: if the heat history of the high temperature generated during the operation of the device is applied for a long time to the flux residue remaining after the solder paste is reflowed, the flux residue in the flux residue The eluted tin ions move to the cathode and precipitate, and high-temperature migration occurs, which may result in poor insulation. Based on this insight, they conducted further intensive research and found that high-temperature migration can be suppressed by properly controlling the viscoelastic properties of flux residue in solder paste, thereby completing the present invention.

According to the present invention, a solder paste is provided, which includes a flux composition and solder powder, and is constituted as follows: For the flux residue obtained from the solder paste according to the following preparation procedure, based on the following measurement conditions and using flow Measured by a variable instrument, when the measured storage elastic modulus at 100°C is set as G' ₁₀₀ and the loss elastic modulus is set as G'' ₁₀₀ , G' ₁₀₀ and G'' ₁₀₀ satisfy G' ₁₀₀ >G'' ₁₀₀ . <Sequence of making flux residue> 1. Prepare 2 copper trays with a bottom surface of 45 mm x 45 mm, a height of 5 mm, and a thickness of 0.3 mm. 2. On the bottom surface of the above-mentioned one copper tray, overlap the opening with the opening of the above-mentioned another copper tray, and fix it with adhesive tape to prepare a copper box with a height of about 10 mm. 3. Collect 5 g of the solder paste as a sample. Spread the sample on the inner bottom surface of the above-mentioned copper tray to cover 80% of the bottom surface. 4. For the above-mentioned copper box containing the above-mentioned samples, use a reflow furnace to perform the reflow treatment of the following temperature profiles A to E under the atmosphere. (Temperature distribution A-E) A. Heat from room temperature 25°C to 150°C at a rate of 1.9°C/sec. B. Keep it in the temperature range of 150℃～180℃ for 80 sec. C. Heating to 220°C at a heating rate of 1.2°C/sec. D. Heating in such a way as to keep the temperature above 220°C for 40 sec and the peak temperature is 240°C. E. Thereafter cooled to room temperature 25°C. 5. After the reflow process, collect the flux residue remaining on the inner bottom surface of the above-mentioned copper tray. <Measurement conditions> Measuring device: Rheometer Measuring temperature: 20°C to 180°C Geometry (upper side): 25 mmϕ, made of stainless steel, parallel plate Plate (lower side): 60 mmϕ Mode: 5°C/min Strain: 1% Frequency: 10 Hz Gap: 0.2 mm

Also, according to the present invention, A method of manufacturing an electronic device is provided, which includes the following steps: Print the above solder paste on the soldering part of the electronic circuit board; Constructing electronic components at the above-mentioned soldering locations; and A step of joining the above-mentioned electronic component and the above-mentioned electronic circuit board by heating the above-mentioned soldered portion to a temperature at which solder powder in the above-mentioned solder paste melts in a state where a sealed structure exists around the above-mentioned soldered portion. [Effect of Invention]

According to the present invention, there are provided a solder paste excellent in high temperature resistance and mobility, and a method of manufacturing an electronic device using the same.

Embodiments of the present invention will be described below using the drawings. In addition, in all drawings, the same code|symbol is attached|subjected to the same component, and description is abbreviate|omitted suitably. In addition, the figure is a schematic view, and the actual size ratio does not match.

The outline of the solder paste of this embodiment is demonstrated.

The solder paste of this embodiment includes a flux composition and solder powder, and is configured as follows: For the flux residue obtained from the solder paste according to the following preparation procedure, it is measured using a rheometer based on the following measurement conditions, When the measured storage elastic modulus at 100°C is set as G' ₁₀₀ and the loss elastic modulus is set as G'' ₁₀₀ , G' ₁₀₀ and G'' ₁₀₀ satisfy G' ₁₀₀ >G'' ₁₀₀ .

＜Sequence of making flux residue＞ 1. Prepare two copper trays with a bottom surface of 43-45 mm×43-45 mm, a height of 5-7 mm, and a thickness of 0.2-0.4 mm. 2. On the bottom surface of a copper tray, overlap the opening with the opening of another copper tray, and fix it with adhesive tape to prepare a copper box with a height of 10-14 mm. 3. Collect about 5 g of the solder paste as a sample. Spread the sample on the inner bottom surface of a copper tray to cover about 80% of the bottom surface. 4. For the copper box containing the above samples, use a reflow furnace (manufactured by Senju Metal Industry Co., Ltd., SNR-825) to perform reflow treatment with the following temperature profiles A to E in the atmosphere. (Temperature distribution A～E) A. Heating from room temperature 25°C to 150°C at a heating rate of 1.9°C/sec. B. Keep it in the temperature range of 150℃～180℃ for 80 sec. C. Heating to 220°C at a heating rate of 1.2°C/sec. D. Heating in such a way as to keep the temperature above 220°C for 40 sec and the peak temperature is 240°C. E. Thereafter cooled to room temperature 25°C. 5. After the reflow process, collect the flux residue remaining on the inner bottom surface of the above-mentioned copper tray.

＜Measurement conditions＞ Measuring device: Rheometer (manufactured by Malvern Panalytical, KINEXUS 1b+) Measuring temperature: 20℃～180℃ Geometry (upper side): 25 mmϕ, stainless steel, parallel plate Plate (lower side): 60 mmϕ Mode: 5°C/min Strain: 1% Frequency: 10Hz Clearance: 0.2 mm

In recent high output devices, the temperature around the heat generating parts sometimes reaches 100°C or higher. Generally, the surrounding humidity of heat-generating parts above 100°C becomes lower than normal humidity, so it is considered to be an environmental condition in which ion migration is difficult to occur, but the inventors have confirmed that even in a low-humidity environment, it is possible to Ion migration occurs in the output device. However, since the usual ion migration test is carried out at a temperature of 85°C and a humidity of 85%, it is difficult to say that it corresponds to the above-mentioned actual situation. Therefore, the present inventors newly invented a high-temperature migration test for evaluating the migration of metal ions in a temperature environment of 100° C. or higher. In the high temperature migration test, environmental conditions such as low humidity environment with humidity below 20% or high humidity environment with humidity above 85% can be used. According to the knowledge of the present inventors, it was found that high temperature migration can be suppressed by properly controlling the viscoelastic properties of the flux residue in the solder paste. In addition, it was also found that high-temperature migration can be suppressed even in a further severe high-humidity environment. The viscoelastic properties of flux residues are measured by using a rheometer based on the above measurement conditions for the flux residues obtained by the above-mentioned production procedures, and the measured storage elastic modulus at 100°C is set as G' ₁₀₀ and the loss elastic modulus are set to G'' ₁₀₀ , and these are used as indicators, so that stable evaluation can be performed. This point was confirmed based on the relationship between the viscoelastic properties of the flux residue and the evaluation results of the high-temperature migration test using the same flux residue. Furthermore, it was found that high-temperature migration can be suppressed by constituting the solder paste so that G' ₁₀₀ and G'' ₁₀₀ of the flux residue satisfy G' ₁₀₀ >G'' ₁₀₀ .

Although the detailed mechanism is not clear, it is believed that the reason is that by making the storage elastic modulus at 100°C larger than the loss elastic modulus, the deformation at high temperature can be suppressed, and the flux residue in a low fluidity state can be successfully obtained, so it can be Inhibit the high-temperature migration of metal ions such as tin ions.

In the production sequence of the above-mentioned flux residue, the temperature distribution adopts the above (temperature distribution A-E), but it can also be set according to the standard reflow distribution in Figure 3 if necessary. The temperature in the temperature distribution refers to the working temperature. The reflow process can be carried out by means of hot air circulation through the heater.

In addition, in the preparation procedure of the above-mentioned flux residue, the sample amount only needs to be about 5 g, and 4.5 to 5.5 g is acceptable. The area to be wiped on the copper tray can be set to about 80%, but as long as it is more than about 60%, the amount that can collect flux residue can be obtained. Furthermore, the copper tray can also be made by bending a copper plate with a thickness of 0.2-0.4 mm.

Set the phase angle at 100°C obtained based on the storage elastic modulus and loss elastic modulus at 100°C measured with a rheometer based on the above measurement conditions as δ ₁₀₀ , and based on the storage elasticity at 140°C The phase angle at 140°C obtained from the modulus and loss elastic modulus was set to δ ₁₄₀ .

The lower limit of δ ₁₄₀ is, for example, above 1°, preferably above 2°, more preferably above 3°. On the other hand, the upper limit of δ ₁₄₀ is, for example, less than 45°, preferably not more than 44°, more preferably not more than 30°. In this way, the high temperature migration resistance in the high temperature operating environment exceeding 100°C can be improved.

δ ₁₄₀ and δ ₁₀₀ can also be configured so that 0.1≦δ ₁₄₀ /δ ₁₀₀ ≦3.0 is satisfied. The lower limit of δ ₁₄₀ /δ ₁₀₀ is, for example, 0.1 or more, preferably 0.15 or more, more preferably 0.2 or more. On the other hand, the upper limit of δ ₁₄₀ /δ ₁₀₀ is, for example, 3.0 or less, preferably 2.5 or less, more preferably 2.0 or less. By setting it within the above numerical range, the high-temperature migration resistance in a high-temperature operating environment exceeding 100° C. can be improved.

Use the rheometer above to measure the viscosity of the solder paste at 25°C. Set the viscosity at a shear rate of 6 sec ^-1 as η1, the viscosity at a shear rate of 1.8 sec ^-1 as η2, and the shear rate The viscosity at 18 sec ^-1 is set as η3.

The lower limit of the viscosity η1 is, for example, 5 Pa·s or more, preferably 20 Pa·s or more, more preferably 50 Pa·s or more. On the other hand, the upper limit of the viscosity η1 is, for example, 400 Pa·s or less, preferably 300 Pa·s or less, more preferably 280 Pa·s or less. By setting it as the said numerical value range, the printing characteristic of a solder paste can be improved.

The lower limit of the thixotropic ratio calculated by Log(η2/η3) is, for example, 0.3 or more, preferably 0.4 or more, more preferably 0.5 or more. On the other hand, the upper limit of the thixotropic ratio is, for example, 1.8 or less, preferably 1.5 or less, more preferably 1.0 or less. By setting it as the said numerical value range, the printing characteristic of a solder paste can be improved.

In this embodiment, for example, by appropriately selecting the type or blending amount of each component contained in the solder paste, the preparation method of the solder paste, etc., the above-mentioned storage elastic modulus and loss elastic modulus at 100°C or 140°C can be controlled. Number, phase angle, viscosity η1 and thixotropic ratio. Among them, as the elements for making the storage elastic modulus at 100°C or 140°C, the loss elastic modulus, the phase angle, the viscosity η1, and the thixotropic ratio in the desired numerical range, for example, use The first rosin-based resin with high softening point; properly adjust the content of the first rosin-based resin with high softening point; do not use the third rosin-based resin with low softening point; properly adjust the content of solvent and/or active agent, etc.

The solder paste of the present embodiment can be used for joining an electronic circuit board and electronic parts, and particularly can be used for joining an electronic circuit board and electronic parts around a sealed structure composed of the electronic circuit board and electronic parts. Even when flux residues remain in the sealed structure, high-temperature migration can be suppressed. In addition, this solder paste can be suitably used in the manufacture of devices in which the temperature of heat generated during device operation reaches 100° C. or higher at the junction of an electronic circuit board and an electronic component.

Hereinafter, the structure of the solder paste of this embodiment is described in detail.

The solder paste contains a flux composition and solder powder.

The flux composition may contain one or two or more selected from the group consisting of an activator, a base resin, a thixotropic agent, and a solvent.

(active agent) The flux composition may contain an activator having metal oxide removal properties. By including the activator, the solder wettability during the solder joint process can be improved.

Specific examples of the activating agent include, for example, organic acids, amines, halogen-based activating agents, phosphorus-based activating agents, and the like. These may be used individually or in combination of 2 or more types. Although the detailed mechanism of these activators is not clear, it is believed that the reason is that by reducing the metal oxide to form a salt with the metal, the metal oxide film on the surface of the solder and the metal to be soldered can be removed.

In 100% by weight of the flux composition, the content of the activator may be, for example, 0 to 30% by weight, or 1 to 20% by weight. In addition, in this specification, unless otherwise indicated, "-" means that an upper limit and a lower limit are included.

As an organic acid, a monocarboxylic acid, a dicarboxylic acid, an anhydride of a dicarboxylic acid, an oxyacid, etc. are mentioned. These may be used individually or in combination of 2 or more types.

Examples of specific examples of organic acids include glutaric acid, adipic acid, azelaic acid, eicosanedioic acid, citric acid, glycolic acid, succinic acid, salicylic acid, diglycolic acid, 2,6-pyridinedicarboxylic acid, dibutylaniline diglycolic acid, suberic acid, sebacic acid, thioglycolic acid, terephthalic acid, dodecanedioic acid, p-hydroxyphenylacetic acid, 2-pyridinecarboxylic acid , phenylsuccinic acid, phthalic acid, fumaric acid, maleic acid, malonic acid, lauric acid, benzoic acid, tartaric acid, tris(2-carboxyethyl) isocyanurate, glycine, 1,3-cyclohexanedicarboxylic acid, 2,2-bis(hydroxymethyl)propionic acid, 2,2-bis(hydroxymethyl)butyric acid, 2,3-dihydroxybenzoic acid, 2,4- Diethylglutaric acid, 2-quinolinic acid, 3-hydroxybenzoic acid, malic acid, p-anisic acid, stearic acid, 12-hydroxystearic acid, oleic acid, linolenic acid, linolenic acid, etc. .

Among them, the organic acid may contain organic acids having 11 or less carbon atoms from the viewpoint of low residue property. Examples of organic acids having 11 or less carbon atoms include glycolic acid (2 carbon atoms), thioglycolic acid (2 carbon atoms), glycine (2 carbon atoms), malonic acid (3 carbon atoms), Fumaric acid (4 carbons), maleic acid (4 carbons), succinic acid (4 carbons), glycolic acid (4 carbons), tartaric acid (4 carbons), malic acid (4 carbons) , glutaric acid (carbon number 5), 2,2-bis(hydroxymethyl)propionic acid (carbon number 5), adipic acid (carbon number 6), citric acid (carbon number 6), 2-picolinic acid ( Carbon number 6), benzoic acid (carbon number 7), 2,2-bis(hydroxymethyl)butanoic acid (carbon number 6), salicylic acid (carbon number 7), 2,6-pyridinedicarboxylic acid (carbon number 7), 2,3-dihydroxybenzoic acid (carbon number 7), 3-hydroxybenzoic acid (carbon number 7), suberic acid (carbon number 8), phthalic acid (carbon number 8), isophthalic acid Formic acid (carbon number 8), terephthalic acid (carbon number 8), p-hydroxyphenylacetic acid (carbon number 8), 1,3-cyclohexanedicarboxylic acid (carbon number 8), p-anisic acid (carbon number 8), azelaic acid (9 carbons), 2,4-diethylglutaric acid (9 carbons), sebacic acid (10 carbons), phenylsuccinic acid (10 carbons), 2-quinone Phynoformic acid (10 carbons), 4-tert-butylbenzoic acid (11 carbons), etc.

Further, examples of organic acids include dimer acid, trimer acid, hydrogenated dimer acid obtained by adding hydrogen to dimer acid, and hydrogenated dimer acid obtained by adding hydrogen to trimer acid. Hydrogenated trimer acid.

In 100% by weight of the flux composition, the content of the organic acid may be, for example, 0 to 25% by weight, or 1 to 20% by weight. By setting it as below the said upper limit, the viscoelastic property of a flux residue can be made suitable.

、2,4-二胺基-6-[2'-十一烷基咪唑基-(1')]-乙基對稱三

、2,4-二胺基-6-[2'-乙基-4'-甲基咪唑基-(1')]-乙基對稱三

、2,4-二胺基-6-[2'-甲基咪唑基-(1')]-乙基對稱三

異三聚氰酸加成物、2-苯基咪唑異三聚氰酸加成物、2-苯基-4,5-二羥基甲基咪唑、2-苯基-4-甲基-5-羥甲基咪唑、2,3-二氫-1H-吡咯并[1,2-a]苯并咪唑、1-十二烷基-2-甲基-3-苄基咪唑鎓氯化物、2-甲基咪唑啉、2-苯基咪唑啉、2,4-二胺基-6-乙烯基對稱三

、2,4-二胺基-6-乙烯基對稱三

異三聚氰酸加成物、2,4-二胺基-6-甲基丙烯醯氧基乙基對稱三

、環氧咪唑加成物、2-甲基苯并咪唑、2-辛基苯并咪唑、2-戊基苯并咪唑、2-(1-乙基戊基)苯并咪唑、2-壬基苯并咪唑、2-(4-噻唑基)苯并咪唑、苯并咪唑、2-(2'-羥基-5'-甲基苯基)苯并三唑、2-(2'-羥基-3'-第三丁基-5'-甲基苯基)-5-氯苯并三唑、2-(2'-羥基-3',5'-二第三戊基苯基)苯并三唑、2-(2'-羥基-5'-第三辛基苯基)苯并三唑、2,2'-亞甲基雙[6-(2H-苯并三唑-2-基)-4-第三辛基苯酚]、6-(2-苯并三唑基)-4-第三辛基-6'-第三丁基-4'-甲基-2,2'-亞甲基雙酚、1,2,3-苯并三唑、1-[N,N-雙(2-乙基己基)胺基甲基]苯并三唑、羧基苯并三唑、1-[N,N-雙(2-乙基己基)胺基甲基]甲基苯并三唑、2,2'-[[(甲基-1H-苯并三唑-1-基)甲基]亞胺基]雙乙醇、1-(1',2'-二羧基乙基)苯并三唑、1-(2,3-二羧基丙基)苯并三唑、1-[(2-乙基己基胺基)甲基]苯并三唑、2,6-雙[(1H-苯并三唑-1-基)甲基]-4-甲基苯酚、5-甲基苯并三唑、5-苯基四唑等。As the amines, for example, monoethanolamine, diphenylguanidine, ethylamine, triethylamine, ethylenediamine, triethylenetetramine, 2-methylimidazole, 2-undecylimidazole, 2- Heptadecyl imidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2- Methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl Base-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenyl Imidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl symmetrical tris

, 2,4-diamino-6-[2'-undecyl imidazolyl-(1')]-ethyl symmetrical three

, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl symmetrical three

, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl symmetrical three

Isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5- Hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2- Methylimidazoline, 2-phenylimidazoline, 2,4-diamino-6-vinyl symmetrical tri

, 2,4-diamino-6-vinyl symmetrical three

Isocyanuric acid adduct, 2,4-diamino-6-methacryloxyethyl symmetrical tri

, epoxy imidazole adduct, 2-methylbenzimidazole, 2-octylbenzimidazole, 2-pentylbenzimidazole, 2-(1-ethylpentyl)benzimidazole, 2-nonyl Benzimidazole, 2-(4-thiazolyl)benzimidazole, benzimidazole, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3 '-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-tert-pentylphenyl)benzotriazole , 2-(2'-hydroxy-5'-tertoctylphenyl)benzotriazole, 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4 -tertiary octylphenol], 6-(2-benzotriazolyl)-4-tertiary octyl-6'-tertiary butyl-4'-methyl-2,2'-methylenebis Phenol, 1,2,3-benzotriazole, 1-[N,N-bis(2-ethylhexyl)aminomethyl]benzotriazole, carboxybenzotriazole, 1-[N,N -Bis(2-ethylhexyl)aminomethyl]methylbenzotriazole, 2,2'-[[(methyl-1H-benzotriazol-1-yl)methyl]imino] Diethanol, 1-(1',2'-dicarboxyethyl)benzotriazole, 1-(2,3-dicarboxypropyl)benzotriazole, 1-[(2-ethylhexylamino )methyl]benzotriazole, 2,6-bis[(1H-benzotriazol-1-yl)methyl]-4-methylphenol, 5-methylbenzotriazole, 5-phenyl tetrazole, etc.

In 100% by weight of the flux composition, the content of the amines may be, for example, 0 to 15% by weight, or 0.1 to 10% by weight.

As the halogen-based activator, organic halogen compounds, amine hydrohalides, and the like may, for example, be mentioned.

Examples of organic halogen compounds include: trans-2,3-dibromo-1,4-butanediol, triallyl isocyanurate hexabromide, 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 , 2,3-dibromo-1-propanol, 2,3-dibromo-1,4-butanediol, 2,3-dibromo-2-butene-1,4-diol, etc. As other organic halogen compounds, for example, chlorinated alkanes, chlorinated fatty acid esters, chloracids, chloracid anhydrides, etc., which are organochlorine compounds, may, for example, be mentioned. Furthermore, a fluorine-based surfactant which is an organic fluorine compound, a surfactant having a perfluoroalkyl group, polytetrafluoroethylene, and the like may be mentioned.

Examples of amine hydrohalides include hydrohalic acids such as hydroiodic acid (HI), hydrobromic acid (HBr), hydrochloric acid (HCl), and hydrofluoric acid (HF), mixed with aniline, diphenyl A salt obtained by combining amine compounds such as guanidine, diethylamine, and isopropylamine. In addition, as the equivalent of amine hydrohalide salts, salts obtained by combining tetrafluoroboric acid (HBF ₄ ) and amine compounds can also be used.

啉鹽酸鹽、甜菜鹼鹽酸鹽、2-甲基哌啶氫碘酸鹽、環己基胺氫碘酸鹽、1,3-二苯胍氫氟酸鹽、二乙基胺氫氟酸鹽、2-乙基己基胺氫氟酸鹽、環己基胺氫氟酸鹽、乙基胺氫氟酸鹽、松香胺氫氟酸鹽、環己基胺四氟硼酸鹽、及二環己基胺四氟硼酸鹽等。Examples of amine hydrohalides include: stearylamine hydrochloride, diethylaniline hydrochloride, diethanolamine hydrochloride, 2-ethylhexylamine hydrobromide, pyridine hydrobromide salt, isopropylamine hydrobromide, cyclohexylamine hydrobromide, diethylamine hydrobromide, monoethylamine hydrobromide, 1,3-diphenylguanidine hydrobromide, di Methylamine hydrobromide, dimethylamine hydrobromide, rosinamine hydrobromide, 2-ethylhexylamine hydrochloride, isopropylamine hydrochloride, cyclohexylamine hydrochloride, 2- Methylpiperidine Hydrobromide, 1,3-Diphenylguanidine Hydrochloride, Dimethylbenzylamine Hydrochloride, Hydrazine Hydrate Hydrobromide, Dimethylcyclohexylamine Hydrochloride, Trinonylamine Hydrobromide, Diethylaniline Hydrobromide, 2-Diethylaminoethanol Hydrobromide, 2-Diethylaminoethanol Hydrochloride, Ammonium Chloride, Diallylamine Hydrochloride Salt, Diallylamine Hydrobromide, Monoethylamine Hydrochloride, Monoethylamine Hydrobromide, Diethylamine Hydrochloride, Triethylamine Hydrobromide, Triethylamine Hydrochloride, hydrazine monohydrochloride, hydrazine dihydrochloride, hydrazine monohydrobromide, hydrazine dihydrobromide, pyridine hydrochloride, aniline hydrobromide, butylamine hydrochloride, hexylamine hydrochloride, n-octylamine hydrochloride Ammonium Hydrochloride, Dodecylamine Hydrochloride, Dimethylcyclohexylamine Hydrobromide, Ethylenediamine Dihydrobromide, Rosinamine Hydrobromide, 2-Phenylimidazole Hydrobromide salt, 4-benzylpyridine hydrobromide, L-glutamine hydrochloride, N-methyl

Phenoline hydrochloride, betaine hydrochloride, 2-methylpiperidine hydroiodide, cyclohexylamine hydroiodide, 1,3-diphenylguanidine hydrofluoride, diethylamine hydrofluoride , 2-Ethylhexylamine Hydrofluoride, Cyclohexylamine Hydrofluoride, Ethylamine Hydrofluoride, Rosinamine Hydrofluoride, Cyclohexylamine Tetrafluoroborate, and Dicyclohexylamine Tetrafluoro Borate etc.

In 100% by weight of the flux composition, the content of the halogen-based activator may be, for example, 0 to 10% by weight, or 0.1 to 5% by weight. In 100% by weight of the flux composition, the content of the organic halogen compounds may be, for example, 0 to 10% by weight, or 0.1 to 5% by weight. In 100% by weight of the flux composition, the content of amine hydrohalide salts may be, for example, 0 to 5% by weight, or 0.1 to 3% by weight.

As a phosphorus-based active agent, a phosphonate, a phenyl-substituted phosphinic acid, phosphoric acid ester, etc. are mentioned, for example.

As the phosphonate, for example, 2-ethylhexyl (2-ethylhexyl) phosphonate, n-octyl (n-octyl) phosphonate, n-decyl (n-decyl) phosphonate, and ( n-butyl) n-butyl phosphonate. As a phenyl substituted phosphinic acid, a phenyl phosphinic acid and a diphenyl phosphinic acid are mentioned, for example.

In 100% by weight of the flux composition, the content of the phosphorus-based activator may be, for example, 0 to 10% by weight, or 0.1 to 5% by weight.

(base resin) The flux composition may also include a base resin. Examples of base resins include rosin-based resins, (meth)acrylic resins, urethane-based resins, polyester-based resins, phenoxy resins, vinyl ether-based resins, terpene resins, and modified terpene resins. olefin resins (such as aromatic modified terpene resins, hydrogenated terpene resins, hydrogenated aromatic modified terpene resins, etc.), terpene phenol resins, modified terpene phenol resins (such as hydrogenated terpene phenol resins, etc.), styrene resins, Modified styrene resin (such as styrene acrylic resin, styrene maleic acid resin, etc.), xylene resin, modified xylene resin (such as phenol modified xylene resin, alkylphenol modified xylene resin, phenol modified Resole phenolic xylene resin, polyol modified xylene resin, polyoxyethylene added xylene resin, etc.), etc. These may be used individually or in combination of 2 or more types. In addition, in this specification, "(meth)acrylic resin" means the concept including a methacrylic resin and an acrylic resin.

Among these, the base resin may contain a rosin-based resin. Examples of the rosin-based resin include raw material rosins such as gum rosin, wood rosin, and tall oil rosin, and derivatives obtained from raw material rosins. Examples of derivatives include: purified rosin, hydrogenated rosin, disproportionated rosin, polymerized rosin, and modified α,β-unsaturated carboxylic acid (acrylized rosin), maleated rosin, and fumalated rosin etc., as well as the purified, hydrogenated and disproportionated products of polymerized rosin, and the purified, hydrogenated and disproportionated products of α, β-unsaturated carboxylic acid modified products. These rosin-based resins may be used alone or in combination of two or more.

In 100% by weight of the flux composition, the content of the base resin may be, for example, 0 to 50% by weight, 10 to 49% by weight, or 15 to 48% by weight. The viscoelastic property of a flux residue can be made suitable by making content of a base resin into the said 15 weight% or more.

The flux composition preferably includes the first rosin-based resin having a softening point of 135° C. or higher. The softening point of the first rosin-based resin is preferably at least 138°C, more preferably at least 140°C. If necessary, the flux composition may contain a second rosin-based resin having a softening point of not less than 120° C. and less than 135° C. Furthermore, the flux composition preferably does not contain the third rosin-based resin whose softening point is 90° C. or lower. The viscoelastic property of a flux residue can be made suitable by setting it as a structure which contains a 1st rosin-type resin, and/or contains a 2nd rosin-type resin, or does not contain a 3rd rosin-type resin. In addition, the softening point can be measured according to the softening point test method (ring and ball method) of JIS K 2207:1996.

The content of the first rosin-based resin in 100% by weight of the flux composition may be, for example, 1 to 50% by weight, 3 to 30% by weight, or 5 to 30% by weight. By setting it as more than the said lower limit, the viscoelastic property of a flux residue can be made suitable. By setting it as below the said upper limit, the fall of the printing characteristic of a solder paste can be suppressed. In 100% by weight of all rosin-based resins, the content of the first rosin-based resin may be, for example, 3 to 100% by weight, 10 to 90% by weight, or 12 to 80% by weight. By setting it as more than the said lower limit, the viscoelastic property of a flux residue can be made suitable.

(solvent) The flux composition may also contain solvents. The solvent can be solid or liquid at 25°C. These may be used alone or in combination of two or more.

As the solid solvent, for example, an alcohol-based solid solvent, a phenol-based solid solvent, or the like can be used. These may be used alone or in combination of two or more.

The alcohol-based solid solvent may be a solid solvent having one or more hydroxyl groups in the molecule, and is preferably a polyol-based solid solvent having two or more hydroxyl groups.

As a specific example of a polyol type solid solvent, neopentyl glycol, trimethylolpropane, 2, 5- dimethyl- 2, 5- hexanediol, neopentyl glycol, etc. are mentioned, for example.

The phenolic solid solvent may be a solid solvent as long as it has one or two or more phenolic groups in the molecule, and one or two or more hydroxyl groups may be bonded to the benzene ring of the phenolic group.

As the liquid solvent, for example, alcohol solvents, glycol ether solvents, terpineols, hydrocarbons, esters, water and the like can be used. These may be used alone or in combination of two or more. However, at least one of alcohol-based solvents and glycol ether-based solvents may be used as the liquid solvent.

Examples of alcohol-based solvents include isopropanol, 1,2-butanediol, isobornylcyclohexanol, 2,4-diethyl-1,5-pentanediol, 2,2-di Methyl-1,3-propanediol, 2,5-dimethyl-2,5-hexanediol, 2,5-dimethyl-3-hexyne-2,5-diol, 2,3-diol Methyl-2,3-butanediol, 1,1,1-tris(hydroxymethyl)ethane, 2-ethyl-2-hydroxymethyl-1,3-propanediol, 2,2'-oxybis (Methylene)bis(2-ethyl-1,3-propanediol), 2,2-bis(hydroxymethyl)-1,3-propanediol, 1,2,6-trihydroxyhexane, bis[2 ,2,2-tris(hydroxymethyl)ethyl]ether, 1-ethynyl-1-cyclohexanol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, erythritol, Threitol, guaiacol glycerol ether, 3,6-dimethyl-4-octyne-3,6-diol, 2,4,7,9-tetramethyl-5- Decyne-4,7-diol, etc.

Examples of glycol ether solvents include diethylene glycol hexyl ether, diethylene glycol mono-2-ethylhexyl ether, ethylene glycol monophenyl ether, 2-methylpentane-2,4- Diol, diethylene glycol monohexyl ether, diethylene glycol dibutyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, etc.

The content of the solvent in 100% by weight of the flux composition is, for example, 0 to 65% by weight, 1 to 50% by weight, or 5 to 40% by weight. By setting it as below the said upper limit, the viscoelastic property of a flux residue can be made suitable. The content of the liquid solvent in 100% by weight of the flux composition is, for example, 0 to 65% by weight, 1 to 50% by weight, or 5 to 40% by weight.

(thixotropic agent) The flux composition may also contain a thixotropic agent. As a thixotropic agent, a wax type thixotropic agent, an amide type thixotropic agent, a sorbitol type thixotropic agent, etc. are mentioned, for example. As a wax-type thixotropic agent, hydrogenated castor oil etc. are mentioned, for example. The amide-based thixotropic agent may, for example, be monoamide, bisamide or polyamide. For example, lauric acid amide, palmitic acid amide, stearic acid amide, behenyl amide, hydroxystearic acid amide, saturated fatty acid amide, oleic acid amide, erucamide, Saturated fatty acid amide, p-toluene amide, aromatic amide, methylenebisstearamide, ethylenylbislauric acid amide, ethylenylbishydroxystearamide, saturated fatty acid bisamide Amine, methylenebisoleic acid amide, unsaturated fatty acid bisamide, m-xylene bisstearyl amide, aromatic bisamide, aliphatic polyamide (saturated fatty acid polyamide, unsaturated fatty acid polyamide amide), aromatic polyamide, substituted amide, hydroxymethylstearamide, hydroxymethylamide, fatty acid ester amide, cyclic amide oligomer, acyclic amide oligomers etc.

In 100% by weight of the flux composition, the content of the thixotropic agent may be, for example, 0 to 20% by weight, or 1 to 15% by weight.

(additive) As long as the effects of the present invention are not impaired, the flux composition may also contain additives usually added to fluxes. As an additive, an antioxidant, an antirust agent, an antifoaming agent, a matting agent, a surfactant, a coloring agent, etc. are mentioned, for example. These may be used alone or in combination of two or more. For example, as an antioxidant, a hindered phenolic antioxidant, a phosphorus antioxidant, etc. are mentioned.

Solder powder can be composed of the following components: Sn simple substance; or Sn-Ag system, Sn-Cu system, Sn-Ag-Cu system, Sn-Bi system, Sn-In system, etc.; or add Pb, Sb, Solder powder obtained from Bi, In, Cu, Zn, As, Ag, Cd, Fe, Ni, Co, Au, Ge, P, etc.

The solder powder may have a specific particle size distribution measured by a particle size distribution test according to JIS Z 3284:2014. The solder powder can be composed, for example, such that the mass fraction of powder with a particle size in the range of 2 to 150 μm reaches 80% or more, preferably more than 80% of the powder with a particle size in the range of 5 to 75 μm, More preferably, the mass fraction of the powder with a particle size in the range of 5-45 μm is more than 80%.

According to JIS Z 3284:2017 and through the particle size distribution measurement test, solder powder can be classified into types 1 to 8 according to the particle size distribution. In this embodiment, among them, solder powders of types 2 to 7 are preferable, and solder powders of types 3 to 6 are more preferable. In type 3 solder powder, the mass fraction of powder with a particle size in the range of 25 to 45 μm satisfies 80% or more. In type 4 solder powder, the mass fraction of powder with a particle size in the range of 20 to 38 μm satisfies 80% or more. In the type 5 solder powder, the mass fraction of the powder with a particle size in the range of 15-25 μm shall satisfy 80% or more. In Type 6 solder powder, the mass fraction of powder with a particle size in the range of 5 to 15 μm should be at least 80%.

The content of the flux composition is, for example, 7-30% by weight, preferably 8-25% by weight, and more preferably 10-20% by weight in 100% by weight of the solder paste including solder powder and the flux composition.

The manufacturing method of a flux composition and a solder paste is not limited, It can manufacture by mixing raw materials simultaneously or sequentially by arbitrary methods.

The manufacture of the flux composition only needs to finally mix all the components of the flux composition. Other components can be mixed in the solvent in order, and the mixed components can be added to the solvent, or the solvent and all other components can be mixed. The ingredients are mixed simultaneously. In addition, the manufacture of solder paste does not need to prepare the flux composition in advance, and then mix it with the solder powder, as long as all the components of the flux composition, solder powder and additives added to the solder paste are mixed at last. , regardless of the order of mixing, it is also possible to mix a part of the components of the flux composition with the solder powder, and then add the rest of the components of the flux composition.

About the solder paste of this embodiment, it can be used for the manufacturing method of electronic devices, such as a semiconductor device, as an example. The manufacturing method of an electronic device may include: a step of applying the above-mentioned solder paste to electrodes; for example, a step of heat-treating substrates such as lead frames or printed wiring boards and semiconductor elements, and joining them with molten solder.

An example of the method of manufacturing an electronic device may include: a step of printing the above-mentioned solder paste on the soldered part of the electronic circuit board; a step of assembling electronic parts on the soldered part; Heating the soldering part to the temperature at which the solder powder in the solder paste melts, so as to join the electronic parts and the electronic circuit board. Electronic components can use high output devices such as power semiconductors.

As a printing method of solder paste, screen printing, film printing, etc. are mentioned, and printing by the method other than jet dispensing (jet dispense) is also possible.

As mentioned above, although embodiment of this invention was described, these are illustrations of this invention, and various structures other than the above-mentioned can be employ|adopted. In addition, the present invention is not limited to the above-described embodiments, and changes, improvements, and the like within the scope of attaining the object of the present invention are included in the present invention. Below, an example of the reference form is appended. 1. A solder paste, which comprises a flux composition and solder powder, and is constituted in the following manner: For the flux residue obtained from the solder paste according to the following production procedure, it is measured based on the following measurement conditions and using a rheometer For measurement, when the measured storage elastic modulus at 100°C is set as G' ₁₀₀ and the loss elastic modulus is set as G'' ₁₀₀ , G' ₁₀₀ and G'' ₁₀₀ satisfy G' ₁₀₀ >G'' ₁₀₀ . <Sequence of making flux residue> 1. Prepare 2 copper trays with a bottom surface of 45 mm x 45 mm, a height of 5 mm, and a thickness of 0.3 mm. 2. On the bottom surface of the above-mentioned one copper tray, overlap the opening with the opening of the above-mentioned another copper tray, and fix it with adhesive tape to prepare a copper box with a height of about 10 mm. 3. Collect 5 g of the solder paste as a sample. Spread the sample on the inner bottom surface of the aforementioned copper tray to cover 80% of the bottom surface. 4. For the above-mentioned copper box containing the above-mentioned samples, use a reflow furnace to perform the reflow treatment of the following temperature profiles A to E under the atmosphere. (Temperature distribution A-E) A. Heat from room temperature 25°C to 150°C at a rate of 1.9°C/sec. B. Keep it in the temperature range of 150℃～180℃ for 80 sec. C. Heating to 220°C at a heating rate of 1.2°C/sec. D. Heating in such a way as to keep the temperature above 220°C for 40 sec and the peak temperature is 240°C. E. Thereafter cooled to room temperature 25°C. 5. After the reflow process, collect the flux residue remaining on the inner bottom surface of the above-mentioned copper tray. <Measurement conditions> Measuring device: Rheometer Measuring temperature: 20°C to 180°C Geometry (upper side): 25 mmϕ, made of stainless steel, parallel plate Plate (lower side): 60 mmϕ Mode: 5°C/min Strain: 1% Frequency: 10 Hz Gap: 0.2 mm 2. For the solder paste as described in 1., it will be calculated based on the storage elastic modulus and loss elastic modulus measured at 140°C based on the above measurement conditions and using a rheometer When the phase angle at 140°C is set to δ ₁₄₀ , δ ₁₄₀ is more than 1° and less than 45°. 3. The solder paste as described in 2. is constituted in the following way: The storage elastic modulus and loss elastic modulus at 100 °C measured based on the above measurement conditions and using a rheometer are calculated at 100 °C When the phase angle is δ ₁₀₀ , δ ₁₄₀ and δ ₁₀₀ satisfy 0.1≦δ ₁₄₀ /δ ₁₀₀ ≦3.0. 4. The solder paste according to any one of 1. to 3., wherein the flux composition contains a rosin-based resin having a softening point of 135° C. or higher. 5. The solder paste according to any one of 1. to 4., wherein the content of the flux composition is 7% by weight or more and 20% by weight or less in 100% by weight of the solder paste. 6. The solder paste according to any one of 1. to 5., wherein the viscosity η1 when measured using the above-mentioned rheometer at a shear rate of 6 sec ^-1 and 25°C is 5 Pa·s Above and below 400 Pa・s. 7. The solder paste according to any one of 1. to 6., wherein the viscosity of the solder paste at 25° C. is measured using the above-mentioned rheometer, and the viscosity at a shear rate of 1.8 sec ^-1 is defined as η2 , When the viscosity at a shear rate of 18 sec ^-1 is set to η3, the thixotropic ratio calculated by Log (η2/η3) is not less than 0.3 and not more than 1.8. 8. The solder paste according to any one of 1. to 7., which is used for bonding an electronic circuit board and electronic parts around a sealed structure composed of the electronic circuit board and electronic parts. 9. The solder paste according to any one of 1. to 8., wherein the flux composition includes one or two or more selected from the group consisting of activators, base resins, thixotropic agents, and solvents . 10. The solder paste according to 9., wherein the activating agent contains one or two or more selected from the group consisting of organic acids, amines, halogen-based activating agents, and phosphorus-based activating agents. 11. The solder paste according to any one of 1. to 10., wherein the mass fraction of the solder powder having a particle diameter in the range of 2 to 150 μm is 80% or more. 12. A method of manufacturing an electronic device, comprising the following steps: printing the solder paste described in any one of 1. to 11. on the soldering part of the electronic circuit board; constructing electronic components on the above-mentioned soldering part; There is a sealed structure around the soldered portion, and the soldered portion is heated to a temperature at which solder powder in the solder paste melts to join the electronic component and the electronic circuit board. [Example]

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited by the description of these examples.

Information on the raw material components in Table 1 is shown below. (base resin) ・Rosin-based resin 1: Acrylic modified hydrogenated rosin (softening point: 131°C, manufactured by Arakawa Chemical Industry Co., Ltd., KE-604) ・Rosin-based resin 2: Hydrogenated rosin (softening point: 74°C, manufactured by EASTMAN CHEMICAL, FORAL AX-E) ・Rosin-based resin 3: polymerized rosin (softening point: 141°C, manufactured by Arakawa Chemical Industry Co., Ltd., KR-140) Furthermore, the softening point of rosin-based resins is measured in accordance with the softening point test method (ring and ball method) of JIS K 2207:1996, and is set as the average value of the two measured values (the first decimal place is rounded off). ・Acrylic resin 1: Acrylic resin (active agent) ・Organic acid 1: dimer acid ・Organic acid 2: Adipic acid ・Organic acid 3: Azelaic acid ・Amines 1: 2-phenyl-4-methylimidazole (abbreviation: 2P4MZ) ・Amine hydrohalides 1: Diphenylguanidine hydrobromide ・Organohalogen compound 1: 2,3-dibromo-2-butene-1,4-diol (solvent) ・Solvent 1: Glycol ether solvent (diethylene glycol monohexyl ether) (thixotropic agent) ・Thixotropic agent 1: Polyamide (additive) ・Antioxidant 1: Hindered phenolic antioxidant (solder powder) ・Solder powder 1: Solder powder (SEC305: Sn-3.0Ag-0.5Cu, type 4, manufactured by Senju Metal Industry Co., Ltd.)

＜Preparation of solder paste＞ The raw material components were mixed in the blending ratio shown in Table 1 below to obtain a flux composition. Thereafter, 11.5% by weight of the obtained flux composition and 88.5% by weight of the solder powder were mixed to obtain a solder paste.

[Table 1] unit Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 solder paste Flux composition base resin Rosin-based resin 1 quality% 33.0 34.6 35.0 33.5 34.5 33.3 33.0 33.0 37.6 20.0 20.0 19.6 Rosin-based resin 2 7.0 30.0 Rosin-based resin 3 7.0 10.0 5.0 7.0 7.0 7.0 7.0 7.0 10.0 25.0 5.0 Acrylic resin 1 5.0 active agent Organic acid 1 8.0 8.0 8.0 8.0 8.0 8.0 Organic acid 2 2.0 1.0 2.0 2.0 2.0 2.0 2.0 2.0 1.0 2.0 2.0 5.0 2.0 Organic acid 3 8.0 3.5 8.0 8.0 8.0 8.0 10.0 8.0 3.5 8.0 8.0 17.0 8.0 Amines 1 0.5 Amine Hydrohalides 1 0.2 Organohalogen compound 1 1.5 solvent Solvent 1 39.7 36.7 39.7 38.7 36.7 39.2 29.7 37.7 36.7 44.9 51.9 21.4 36.9 Thixotropic agent Thixotropic agent 1 10.3 6.2 10.3 10.3 10.3 10.3 10.3 10.3 6.2 10.1 10.1 4.0 10.1 additive Antioxidant 1 2.0 total 100 100 100 100 100 100 100 100 100 100 100 100 100 Solder powder Solder powder 1 Content in solder paste (mass%) 85 85 85 85 85 85 85 85 85 85 85 85 85 The relationship between storage elastic modulus G' ₁₀₀ and loss elastic modulus G'' _{1 00} (100°C) G' ₁₀₀ >G'' ₁₀₀ G' ₁₀₀ >G'' ₁₀₀ G' ₁₀₀ >G'' ₁₀₀ G' ₁₀₀ >G'' ₁₀₀ G' ₁₀₀ >G'' ₁₀₀ G' ₁₀₀ >G'' ₁₀₀ G' ₁₀₀ >G'' ₁₀₀ G' ₁₀₀ >G'' ₁₀₀ G' ₁₀₀ >G'' ₁₀₀ G' ₁₀₀ <G'' ₁₀₀ G' ₁₀₀ <G'' ₁₀₀ G' ₁₀₀ <G'' ₁₀₀ G' ₁₀₀ <G'' ₁₀₀ Phase angle δ _{1 00} (100°C) ° 32.49 25.99 11.87 30.16 18.41 13.32 11.19 12.9 28.61 58.90 47.90 56.80 52.90 Phase angle δ _{14 0} (140°C) ° 13.82 27.79 14.13 6.49 43.83 25.54 19.55 12.92 4.99 50.14 47.19 84.42 52.90 Paste viscosity η1 Pa·s 173.9 108 154 68 284 180 42 208 84 64 88 159 111 Thixotropic ratio Log (η2/η3) 0.87 0.89 0.76 0.95 1.00 1.03 1.11 0.70 0.81 1.21 0.86 1.22 1.11 High temperature migration test excellent excellent excellent excellent excellent excellent excellent excellent excellent inferior inferior inferior inferior

The following evaluation items were evaluated about the obtained solder paste.

＜Determination of storage elastic modulus and loss elastic modulus＞ Follow the fabrication sequence below to collect flux residue from the solder paste. (Sequence of making flux residue) 1. As shown in Figure 1, prepare two copper trays 12 and 14 with a bottom surface of 45 mm×45 mm, a height of 5 mm, and a thickness of 0.3 mm. 2. On the bottom surface of one copper tray 12, overlap it so that its opening faces the opening of another copper tray 14, and fix it with adhesive tape to prepare a copper box 10 with a height of 10 mm. 3. Take 5 g of the obtained solder paste as a sample. Spread the sample on the inner bottom surface of a copper tray 12 to cover 80% of the bottom surface. 4. With respect to the copper box 10 containing the sample, the reflow process of the following temperature profiles A to E was performed in the atmosphere using a reflow furnace (manufactured by Senju Metal Industry Co., Ltd., SNR-825). (Temperature distribution A～E) A. Heating from room temperature 25°C to 150°C at a heating rate of 1.9°C/sec. B. Keep it in the temperature range of 150℃～180℃ for 80 sec. C. Heating to 220°C at a heating rate of 1.2°C/sec. D. Heating in such a way as to keep the temperature above 220°C for 40 sec and the peak temperature is 240°C. E. Thereafter, cool to room temperature 25°C. 5. After the reflow process, collect the flux residue remaining on the inner bottom surface of a copper tray 12 .

The storage elastic modulus at 25° C. to 180° C. was measured for the obtained flux residue using a rheometer based on the following measurement conditions. (measurement conditions) Measuring device: Rheometer (manufactured by Malvern Panalytical, KINEXUS 1b+) Measuring temperature: 20℃～180℃ Geometry (upper side): 25 mmϕ, stainless steel, parallel plate Plate (lower side): 60 mmϕ Mode: 5°C/min Strain: 1% Frequency: 10Hz Clearance: 0.2mm

Set the storage elastic modulus at 100°C as G' ₁₀₀ , the loss elastic modulus as G'' ₁₀₀ , the storage elastic modulus at 140°C as G' ₁₄₀ , and the loss The modulus of elasticity is set to G'' ₁₄₀ . Based on the relational expression of tanδ=G'/G'', set the phase angle at 100°C obtained from G' ₁₀₀ and G'' ₁₀₀ as δ ₁₀₀ , and obtain it from G' ₁₄₀ and G'' ₁₄₀ The phase angle at 140°C is set to δ ₁₄₀ . The results are shown in Table 1.

<Measurement of Viscosity> Using the rheometer above, measure the viscosity of the solder paste at 25°C. Set the viscosity at a shear rate of 6 sec ^-1 as η1 and the viscosity at a shear rate of 1.8 sec ^-1 as Set η2 and the viscosity when the shear rate is 18 sec ^-1 as η3, and calculate η1, η2, and η3. Also, the thixotropic ratio obtained by Log(η2/η3) was calculated. The results are shown in Table 1.

＜High temperature migration test＞ The obtained solder paste was printed on the "copper electrode 30 on the printed circuit board" in a manner simulating the actual process, and a reflow process at 240° C. was performed to join the solder 50 to the copper electrode 30 . Next, wash and remove the flux residue remaining on the periphery of the printed part. Thereby, the evaluation device (the structure which consists of a printed circuit board, the copper electrode 30, and the solder 50) shown in FIG. 2 was produced. Next, using the evaluation apparatus shown in FIG. 2, a high-temperature migration test was performed as follows. The evaluation device shown in FIG. 2 includes a substrate, a copper electrode 30 provided on the substrate, and a tin-containing solder 50 provided on the copper electrode 30 . Using 0.002 to 0.005 g of the flux residue 22 collected above (procedure of making flux residue), fill without gaps between the copper electrodes 30 arranged adjacently at fine intervals, and the filled flux residue 22 is covered by the substrate. The glass cover 60 is arranged in such a way that it is sealed with the solder 50 . A constant voltage of 10 V was applied between the copper electrodes 30, and the evaluation device was stored in a temperature environment of 105°C. Thereafter, the metal migration of the flux residue 22 in the partition portion of the copper electrode 30 was observed (high temperature migration test). When gray tree-like precipitation is observed in the flux residue 22 in the partition, it is judged that the tin contained in the solder has migrated. The high-temperature migration test was carried out three times, and the presence or absence of precipitation was confirmed in each test. In Table 1, the case where precipitation was not confirmed three times out of three was marked as "excellent", the case where precipitation was confirmed once out of three times was marked "good", and the case where precipitation was confirmed two or more times out of three The case of precipitation was marked as "poor".

Compared with the solder pastes of the comparative examples, the solder pastes of the respective examples showed that precipitation in the high temperature migration test was suppressed, and thus showed excellent results in the high temperature migration resistance.

This application claims priority based on Japanese application Japanese Patent Application No. 2021-105629 filed on June 25, 2021, and the entire content of the invention is incorporated herein.

10: Copper box 12: copper tray 14: copper tray 20: solder paste 22: Flux residue 30: copper electrode 50: Solder 60: glass cover

[Fig. 1] is a diagram illustrating how to make flux residue. [Fig. 2] is a diagram for explaining the high temperature migration test. [Fig. 3] shows the standard reflow distribution when the flux residue is produced.

22: Flux residue

30: copper electrode

50: Solder

60: glass cover

Claims (9)

A solder paste, which includes a flux composition and solder powder, and is constituted as follows: The flux composition includes a base resin, an activator, a solvent, and a thixotropic agent, and the base resin includes a rosin-based resin. The flux residues obtained from the solder paste in the following production procedures were measured using a rheometer based on the following measurement conditions. The measured storage elastic modulus at 100°C was set as G' 100 , and the loss elastic modulus was set as G' ₁₀₀ . G'' ₁₀₀ , set the phase angle at 140°C calculated based on the storage elastic modulus and loss elastic modulus at 140°C as δ ₁₄₀ , and set the phase angle based on the storage elastic modulus and loss elastic modulus at 100°C When the calculated phase angle at 100°C is set to δ ₁₀₀ , G' ₁₀₀ and G'' ₁₀₀ satisfy G' ₁₀₀ >G'' ₁₀₀ , δ ₁₄₀ satisfies more than 1° and less than 45°, and δ ₁₄₀ and δ ₁₀₀ satisfies 0.1≦δ ₁₄₀ /δ ₁₀₀ ≦3.0; <Sequence of making flux residues> 1. Prepare 2 copper trays with a bottom surface of 45 mm×45 mm, a height of 5 mm, and a thickness of 0.3 mm; 2. On the above On the bottom surface of a copper tray, overlap the opening with the opening of the other copper tray above, and fix it with adhesive tape, so as to prepare a copper box with a height of about 10 mm; 3. Collect 5 g of the solder paste as a sample , spread the sample on the inner bottom surface of the above-mentioned copper tray in such a way as to cover 80% of the above-mentioned bottom surface; 4. For the above-mentioned copper box containing the above-mentioned sample, use a reflow furnace to implement Reflow treatment of the following temperature distribution A～E; (Temperature distribution A～E) A. Heating from room temperature 25℃ to 150℃ at a heating rate of 1.9℃/sec; sec; C. Heating to 220°C at a heating rate of 1.2°C/sec; D. Heating to maintain a temperature above 220°C for 40 sec with a peak temperature of 240°C; E. Cooling to room temperature 25°C; 5 .After the reflow process, collect the flux residue remaining on the bottom surface of the inner side of the above-mentioned copper tray; mmϕ, made of stainless steel, parallel plate, plate (lower side): 60 mmϕ, mode: 5°C/min, strain: 1%, frequency: 10 Hz, gap: 0.2 mm. Such as the solder paste of claim 1, wherein, The above-mentioned flux composition contains a rosin-based resin having a softening point of 135° C. or higher. Such as the solder paste of claim 1 or 2, wherein, In 100% by weight of the solder paste, the content of the above flux composition is not less than 7% by weight and not more than 20% by weight. The solder paste according to claim 1 or 2, wherein, using the above-mentioned rheometer, the viscosity η1 of the solder paste when measured at a shear rate of 6 sec ^-1 and 25°C is 5 Pa·s or more and 400 Below Pa・s. The solder paste according to claim 1 or 2, wherein the viscosity of the solder paste at 25°C is measured using the above-mentioned rheometer, and the viscosity when the shear rate is 1.8 sec ^-1 is set as η2, and the shear rate is 18 sec When the viscosity at ^-1 is η3, the thixotropic ratio calculated by Log (η2/η3) is 0.3 or more and 1.8 or less. The solder paste according to claim 1 or 2, which is used for bonding the electronic circuit board and the electronic parts around the airtight structure formed by the electronic circuit board and the electronic parts. Such as the solder paste of claim 1 or 2, wherein, The above-mentioned activating agent includes one or more than two selected from the group consisting of organic acids, amines, halogen-based activating agents, and phosphorus-based activating agents. Such as the solder paste of claim 1 or 2, wherein, The mass fraction of the solder powder having a particle size in the range of 2 to 150 μm is 80% or more. A method of manufacturing an electronic device, comprising the steps of: Print the solder paste of any one of claims 1 to 8 on the soldering part of the electronic circuit board; Constructing electronic components at the above-mentioned soldering locations; and In a state where a sealed structure exists around the soldered portion, the soldered portion is heated to a temperature at which solder powder in the solder paste melts, thereby bonding the electronic component and the electronic circuit board.

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