WO2013084683A1 - Silver powder for sintered electrically conductive paste - Google Patents

Silver powder for sintered electrically conductive paste Download PDF

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Publication number
WO2013084683A1
WO2013084683A1 PCT/JP2012/079626 JP2012079626W WO2013084683A1 WO 2013084683 A1 WO2013084683 A1 WO 2013084683A1 JP 2012079626 W JP2012079626 W JP 2012079626W WO 2013084683 A1 WO2013084683 A1 WO 2013084683A1
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WIPO (PCT)
Prior art keywords
silver powder
silver
conductive paste
silicon
sintered
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PCT/JP2012/079626
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French (fr)
Japanese (ja)
Inventor
松山　敏和
啓祐 宮之原
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三井金属鉱業株式会社
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Application filed by 三井金属鉱業株式会社 filed Critical 三井金属鉱業株式会社
Priority to KR1020147008900A priority Critical patent/KR20140060340A/en
Priority to CN201280048196.0A priority patent/CN103842115B/en
Publication of WO2013084683A1 publication Critical patent/WO2013084683A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/02—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of metals or alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C5/00—Alloys based on noble metals
    • C22C5/06—Alloys based on silver
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/06—Metallic powder characterised by the shape of the particles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/16—Making metallic powder or suspensions thereof using chemical processes
    • B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
    • B22F9/24—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from liquid metal compounds, e.g. solutions
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/04—Making non-ferrous alloys by powder metallurgy
    • C22C1/0466—Alloys based on noble metals
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/10—Alloys containing non-metals
    • C22C1/1026—Alloys containing non-metals starting from a solution or a suspension of (a) compound(s) of at least one of the alloy constituents
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/20—Conductive material dispersed in non-conductive organic material
    • H01B1/22—Conductive material dispersed in non-conductive organic material the conductive material comprising metals or alloys

Definitions

  • the present invention relates to a silver powder that can be suitably used for a sintered conductive paste, and particularly to a silver powder that can be suitably used as a sintered conductive paste for a solar cell electrode.
  • the conductive paste is a fluid composition in which a conductive filler is dispersed in a vehicle composed of a resin binder and a solvent, and is widely used for forming an electric circuit, an external electrode of a ceramic capacitor, and the like.
  • This type of conductive paste includes a resin-curing type in which conductive fillers are pressure-bonded by hardening of the resin to ensure conduction, and a sintered type in which organic components are volatilized by high-temperature sintering and the conductive filler is sintered to ensure conduction. There is a type.
  • the sintered conductive paste is generally a paste-like composition in which a conductive filler (metal powder) and glass frit are dispersed in an organic vehicle, and is sintered at 400 to 800 ° C.
  • the organic vehicle is volatilized and the conductive filler is sintered to ensure conduction.
  • the glass frit has a function of adhering the conductive film to the substrate, and the organic vehicle functions as an organic liquid medium for enabling printing of the metal powder and the glass frit.
  • a reducing agent-containing aqueous solution is added to an aqueous reaction system containing silver ions to reduce and precipitate silver particles at 500 ° C.
  • Spherical shape having a heat shrinkage rate of 5 to 15%, a heat shrinkage rate at 600 ° C. of 10 to 20%, an average particle diameter D 50 of 5 ⁇ m or less, a tap density of 2 g / cm 3 or more, and a BET specific surface area of 5 m 2 / g or less.
  • Silver powder is disclosed.
  • a silver powder having a heat shrinkage rate at 410 ° C. of 5 to 15%, preferably 10 to 20% at 500 ° C., specifically an average particle diameter D 50 Discloses silver powder having a particle size of 2 ⁇ m or less.
  • silver powder used in sintered conductive pastes in recent years, silver powder having a fine particle size and sharp particle size distribution is generally required in order to cope with the fine lines of electrodes and circuits. Has been proposed.
  • Patent Document 3 Japanese Patent Laid-Open No. 2005-48237
  • an alkali or complexing agent is added to a silver salt-containing aqueous solution to form a silver complex-containing aqueous solution, and then a polyhydric phenol such as hydroquinone is used as a reducing agent.
  • a polyhydric phenol such as hydroquinone
  • a method for obtaining fine silver powder has been proposed.
  • Patent Document 4 Japanese Patent Laid-Open No. 2010-70793 discloses a silver ammine complex aqueous solution obtained by mixing and reacting an aqueous silver nitrate solution and aqueous ammonia, and in the presence of seed particles and an imine compound, By mixing a silver ammine complex aqueous solution and a reducing agent aqueous solution to reduce and precipitate silver particles, an average particle size of 0.1 ⁇ m or more and less than 1 ⁇ m, a sharp particle size distribution and a highly dispersible spherical silver powder are obtained. A method of obtaining has been proposed.
  • the conductive paste is baked at various temperatures depending on the substrate to be applied and the application to be used.
  • the thermal contraction rate of the conductive filler at the baking temperature that is, the silver powder
  • the substrate (substrate) and silver Problems such as peeling between the film, warping, deformation, and cracking may occur.
  • the thermal shrinkage tends to increase, so the difference in heat shrinkage between the substrate (substrate) and the silver powder increases, and the substrate (substrate) and the silver film peel, warp or deform. , Cracks and the like are more likely to occur.
  • an n-type diffusion layer is generally formed on a silicon substrate (p-type) to form a pn junction, and a back electrode is laminated on the back side of the silicon substrate (p-type) via an oxide film.
  • an antireflection film is laminated on the light-receiving surface side (surface side) of the n-type diffusion layer, and a silver electrode is generally formed by printing and baking a silver paste. In general, an electrode is formed by baking a silver paste at around 500 ° C. in consideration of thermal damage.
  • the present invention is a silver powder that can be suitably used as a conductive filler in a sintered conductive paste, and in particular, a silver powder that can be suitably used as a conductive filler in a sintered conductive paste for solar cell electrodes.
  • a new silver powder that can handle fine lines of electrodes and circuits, has a low heat shrinkage rate at 500 ° C, and can suppress the difference in heat shrinkage between the substrate (substrate) and silver powder. It is to be provided.
  • the present invention proposes a silver powder for sintered conductive paste characterized by containing 30 ppm to 1000 ppm of silicon (Si).
  • the silver powder for sintered conductive paste proposed by the present invention can not only produce fine silver powder but also shrink at 500 ° C. by adding silicon (Si) compound so that silicon is contained at 30 ppm to 1000 ppm.
  • the rate can be 15.0% or less. Therefore, since the difference in heat shrinkage behavior between the substrate (substrate) and the silver powder can be suppressed, it can be suitably used as a conductive filler used in a sintered conductive paste. Especially, since the shrinkage rate at 500 ° C. can be suppressed, it can be particularly suitably used as a conductive filler used in a sintered conductive paste for solar cell electrodes.
  • the use of the silver powder for sintered conductive paste proposed by the present invention is not limited to the use for solar cell electrodes.
  • the silver powder for sintered conductive paste according to the present embodiment (hereinafter referred to as “main silver powder”) is a silver powder containing silicon (Si).
  • main silver powder is a silver powder containing silicon (Si).
  • the silver powder preferably has a silicon (Si) content of 30 ppm to 1000 ppm. If containing silicon in such a range, the BET specific surface area not only can be controlled in the range of 0.8m 2 /g ⁇ 3.0m 2 / g, the shrinkage at 500 ° C. below 15.0% can do. From such a viewpoint, the silicon (Si) content of the present silver powder is more preferably 40 ppm or more and 700 ppm or less, and more preferably 50 ppm or more and 600 ppm or less.
  • Examples of a method for adjusting the silicon (Si) content of the present silver powder include a method for adjusting the type and amount of the silicon compound added in the production process.
  • the silicon (Si) content of the present silver powder is the content of silicon (Si) contained inside the silver powder particles or physically or chemically adsorbed on the surface of the particles. More specifically, this is the amount of silicon (Si) remaining when the silver powder is thoroughly washed until the conductivity of the filtrate obtained by washing with pure water is 40 ⁇ S / cm or less. Since silicon (Si) removed by such washing does not function as a sintering inhibitor and does not contribute to the thermal shrinkage rate of silver powder, it is necessary to exclude it from the silicon (Si) content of the silver powder.
  • the silicon (Si) content of the present silver powder is the silicon (Si) content measured with a measuring device after the silver powder is thoroughly washed until the conductivity of the filtrate obtained by washing with pure water is 40 ⁇ S / cm or less. It is.
  • BET specific surface area of the silver powder is preferably a 0.8m 2 /g ⁇ 3.0m 2 / g. If the BET specific surface area of 0.8m 2 /g ⁇ 3.0m 2 / g of the silver powder, silver powder can be suitably used as the conductive filler of the sintered conductive paste, among others baked for a solar cell electrode It is a fine silver powder that can be suitably used as a conductive filler of a binder-type conductive paste, and can cope with fine lines of electrodes and circuits.
  • the BET specific surface area of the present silver powder is preferably 0.8 m 2 / g or more or 3.0 m 2 / g or less, particularly 1.0 m 2 / g or more or 2.8 m 2 / g or less. More preferably, it is particularly preferably 2.65 m 2 / g or less.
  • the kind and amount of the silicon compound to be added in the production process the concentration and amount of the silver nitrate aqueous solution, the concentration and amount of the reducing agent solution are adjusted.
  • the method of doing can be mentioned.
  • this silver powder does not specifically limit particle shape, it is preferable that it is spherical shape or substantially spherical shape.
  • the conductive paste it is also preferable to use flaky particles obtained by processing the spherical particles or substantially spherical particles, and the spherical or substantially spherical particles and the flaky particles. The mixed product is also preferable.
  • the D50 of the present silver powder that is, the D50 based on the volume-based particle size distribution obtained by measuring by the laser diffraction / scattering particle size distribution measuring method is preferably 0.50 ⁇ m to 1.50 ⁇ m. If the D50 of the present silver powder is 0.50 ⁇ m to 1.50 ⁇ m, it is possible to easily form fine lines when printing the paste. Therefore, from this viewpoint, the D50 of the present silver powder is preferably 0.50 ⁇ m or more or 1.50 ⁇ m or less, more preferably 0.70 ⁇ m or more or 1.20 ⁇ m or less, and more preferably 0.90 ⁇ m or more. It is particularly preferred.
  • the present silver powder has an adhesive property with a silicon substrate used in a solar cell, more specifically, an adhesive property that does not cause peeling of the silicon substrate due to shrinkage of the silver powder that occurs when fired at 500 ° C.
  • the heat shrinkage rate of the present silver powder at 500 ° C. is preferably 15.0% or less, more preferably 4.0% or more or 14.0% or less, and more preferably 12.0%. It is particularly preferred that In the present silver powder, the heat shrinkage rate of the silver powder at 500 ° C. can be adjusted by adjusting the kind and amount of the silicon compound added in the production process.
  • a reducing agent is added to a silver solution such as silver nitrate before or at the same time as a silicon compound is added.
  • a complexing agent to a silver aqueous solution such as silver nitrate
  • a silicon compound to be added
  • a dispersing agent as necessary.
  • the silver particles can be produced by reducing and precipitating silver particles by stirring and then filtering, washing and drying.
  • examples of the silicon compound include silicates such as sodium silicate and potassium silicate, and silicon compounds such as a silane coupling agent.
  • silicates such as sodium silicate and potassium silicate are preferable instead of silicon dioxide (SiO 2 ) from the viewpoint of the effect of atomization and reduction of the heat shrinkage rate.
  • silver solution such as silver nitrate
  • aqueous solution or slurry containing either silver nitrate, a silver salt complex, and a silver intermediate.
  • complexing agents include ammonia water, ammonium salts, chelate compounds and the like.
  • Examples of the reducing agent include ascorbic acid, sulfite, alkanolamine, aqueous hydrogen peroxide, formic acid, ammonium formate, sodium formate, glyoxal, tartaric acid, sodium hypophosphite, metal borohydride, dimethylamine borane, hydrazine, hydrazine
  • Examples thereof include an aqueous solution containing a compound, hydroquinone, pyrogallol, glucose, gallic acid, formalin, anhydrous sodium sulfite, Rongalite and the like.
  • Examples of the dispersant include fatty acids, fatty acid salts, surfactants, organic metals, chelating agents, protective colloids and the like.
  • the silver powder is suitable as a silver powder for a conductive paste, particularly for a sintered conductive paste.
  • the sintered conductive paste can be prepared, for example, by mixing the present silver powder together with glass frit in an organic vehicle.
  • the glass frit include lead-free glass such as lead borosilicate glass and zinc borosilicate.
  • a resin binder arbitrary resin binders can be used, for example. For example, it is desirable to employ a composition containing at least one selected from an epoxy resin, a polyester resin, a silicon resin, a urea resin, an acrylic resin, and a cellulose resin.
  • this silver powder has a thermal shrinkage of 15.0% or less at 500 ° C. and is extremely compatible with a silicon substrate in a solar cell
  • the conductive paste using this silver powder is used for an electrode of a solar cell. Is particularly preferred. However, it is not limited to such a use.
  • BET specific surface area Using a specific surface area measuring device (Monosorb MS-18) manufactured by QUANTACHROME, JIS R 1626: 1996 (Method for measuring specific surface area of fine ceramic powder by gas adsorption BET method), .5) Single point method ", BET specific surface area (SSA) was measured. At that time, a mixed gas of helium as a carrier gas and nitrogen as an adsorbate gas was used.
  • a silver nitrate aqueous solution was obtained by dissolving 50 mL of a silver nitrate aqueous solution having a silver concentration of 400 g / L in 1 L of pure water, adding 60 mL of ammonia water having a concentration of 25% by mass, and stirring. Next, 8 mL of an aqueous gelatin solution having a concentration of 5 g / L is added to an aqueous silver ammine complex solution at 30 ° C. and stirred, and a sodium silicate solution (52-57%) (manufactured by Wako Pure Chemical Industries, Ltd.) is added to the silver.
  • Example 2 Silver powder (sample) was obtained in the same manner as in Example 1 except that the addition amount of the sodium silicate solution was changed to 0.50% by mass with respect to silver.
  • Example 3 Example 1 except that the sodium silicate solution was changed to a potassium silicate solution (27 to 29%) (manufactured by Wako Pure Chemical Industries, Ltd.) and the addition amount was changed to 0.10% by mass with respect to silver. In the same manner, silver powder (sample) was obtained.
  • Example 4 A silver powder (sample) was obtained in the same manner as in Example 3 except that the addition amount of the potassium silicate solution was changed to 0.25% by mass with respect to silver.
  • Example 5 A silver powder (sample) was obtained in the same manner as in Example 3 except that the addition amount of the potassium silicate solution was changed to 0.50% by mass with respect to silver.
  • Example 6 Silver powder (sample) was obtained in the same manner as in Example 3 except that the addition amount of the potassium silicate solution was changed to 0.60% by mass with respect to silver.
  • Example 7 The same as in Example 1 except that the sodium silicate solution was changed to a silane coupling agent (organosilane, KBM-603 manufactured by Shin-Etsu Chemical Co., Ltd.) and the addition amount was changed to 0.25% by mass with respect to silver. Thus, silver powder (sample) was obtained.
  • a silane coupling agent organicsilane, KBM-603 manufactured by Shin-Etsu Chemical Co., Ltd.
  • Example 1 A silver powder (sample) was obtained in the same manner as in Example 1 except that the sodium silicate solution was not added.
  • Example 3 Silver powder (sample) was obtained in the same manner as in Comparative Example 2 except that the addition amount of copper nitrate (II) trihydrate (manufactured by Wako Pure Chemical Industries, Ltd.) was changed to 0.04% by mass with respect to silver. .
  • Example 4 Silver powder (sample) was obtained in the same manner as in Comparative Example 2 except that the addition amount of copper (II) nitrate trihydrate (manufactured by Wako Pure Chemical Industries, Ltd.) was changed to 0.08% by mass with respect to silver. .
  • Example 5 Silver powder (sample) as in Example 1, except that the sodium silicate solution was changed to sodium hydrogen carbonate (manufactured by Wako Pure Chemical Industries, Ltd.) and the addition amount was changed to 0.10% by mass with respect to silver. )
  • the silver powders (samples) obtained in the examples and comparative examples were all spherical. From the examples and test results conducted so far, it was found that the silver powder particles can be atomized when a silicon compound is added to the silver complex salt solution. Although the detailed mechanism has not been elucidated, since the silicon compound becomes the nucleus of silver particle growth and the reduction precipitation reaction proceeds, the particle size can be controlled by controlling the number of nuclei, and the silver powder particles are atomized It can be considered that it can be achieved. In addition, it was found that when silicon is incorporated into or on the surface of silver powder particles, the thermal shrinkage at 500 ° C. is reduced as compared with the case where silicon is not incorporated or copper is incorporated.

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Abstract

Provided is a novel microparticlulate silver powder which can cope with the formation of a fine-line electrode or circuit and has a low thermal shrinkage ratio at 500ºC. Proposed is a silver powder for a sintered electrically conductive paste, characterized by containing 30 to 1000 ppm of silicon (Si).

Description

焼結型導電性ペースト用銀粉Silver powder for sintered conductive paste
　本発明は、焼結型導電性ペーストに好適に用いることができる銀粉、中でも太陽電池電極用の焼結型導電性ペーストとして好適に用いることができる銀粉に関する。 The present invention relates to a silver powder that can be suitably used for a sintered conductive paste, and particularly to a silver powder that can be suitably used as a sintered conductive paste for a solar cell electrode.
　導電性ペーストは、樹脂系バインダーと溶媒からなるビヒクル中に導電性フィラーを分散させた流動性組成物であり、電気回路の形成や、セラミックコンデンサの外部電極の形成などに広く用いられている。
　この種の導電性ペーストには、樹脂の硬化によって導電性フィラーが圧着され導通を確保する樹脂硬化型と、高温焼結によって有機成分が揮発し導電性フィラーが焼結して導通を確保する焼結型とがある。 The conductive paste is a fluid composition in which a conductive filler is dispersed in a vehicle composed of a resin binder and a solvent, and is widely used for forming an electric circuit, an external electrode of a ceramic capacitor, and the like.
This type of conductive paste includes a resin-curing type in which conductive fillers are pressure-bonded by hardening of the resin to ensure conduction, and a sintered type in which organic components are volatilized by high-temperature sintering and the conductive filler is sintered to ensure conduction. There is a type.
　このうちの焼結型導電性ペーストは、一般に導電性フィラー（金属粉末）とガラスフリットとを有機ビヒクル中に分散させてなるペースト状組成物であり、４００～８００℃にて焼結することにより、有機ビヒクルが揮発し、さらに導電性フィラーが焼結することによって導通を確保するものである。この際、ガラスフリットは、この導電膜を基板に接着させる作用を有し、有機ビヒクルは、金属粉末およびガラスフリットを印刷可能にするための有機液体媒体として作用する。 Of these, the sintered conductive paste is generally a paste-like composition in which a conductive filler (metal powder) and glass frit are dispersed in an organic vehicle, and is sintered at 400 to 800 ° C. The organic vehicle is volatilized and the conductive filler is sintered to ensure conduction. At this time, the glass frit has a function of adhering the conductive film to the substrate, and the organic vehicle functions as an organic liquid medium for enabling printing of the metal powder and the glass frit.
　このような焼結型導電性ペーストに用いる銀粉として、例えば特許文献１には、銀イオンを含有する水性反応系に還元剤含有水溶液を添加して銀粒子を還元析出させることにより、５００℃における熱収縮率が５～１５％、６００℃における熱収縮率が１０～２０％、平均粒径Ｄ５０が５μｍ以下、タップ密度が２ｇ／ｃｍ３以上、ＢＥＴ比表面積が５ｍ２／ｇ以下の球状銀粉が開示されている。 As silver powder used for such a sintered conductive paste, for example, in Patent Document 1, a reducing agent-containing aqueous solution is added to an aqueous reaction system containing silver ions to reduce and precipitate silver particles at 500 ° C. Spherical shape having a heat shrinkage rate of 5 to 15%, a heat shrinkage rate at 600 ° C. of 10 to 20%, an average particle diameter D 50 of 5 μm or less, a tap density of 2 g / cm 3 or more, and a BET specific surface area of 5 m 2 / g or less. Silver powder is disclosed.
　特許文献２には、４１０℃での熱収縮率が５～１５％であり、好ましくは、さらに５００℃での熱収縮率が１０～２０％である銀粉、具体的には平均粒径Ｄ５０が２μｍ以下である銀粉が開示されている。 In Patent Document 2, a silver powder having a heat shrinkage rate at 410 ° C. of 5 to 15%, preferably 10 to 20% at 500 ° C., specifically an average particle diameter D 50 Discloses silver powder having a particle size of 2 μm or less.
　焼結型導電性ペーストに用いる銀粉については、近年、電極や回路のファインライン化に対応すべく、微粒で且つシャープな粒度分布を有する銀粉が一般的に求められるため、それに対応した新たな技術が提案されている。 With regard to silver powder used in sintered conductive pastes, in recent years, silver powder having a fine particle size and sharp particle size distribution is generally required in order to cope with the fine lines of electrodes and circuits. Has been proposed.
　例えば特許文献３（特開２００５－４８２３７号公報）において、銀塩含有水溶液へ、アルカリまたは錯化剤を添加して、銀錯体含有水溶液を生成させた後、還元剤としてヒドロキノン等の多価フェノールを添加することで、０．６μｍ以下の微粒子化した高分散性の球状の銀粉を還元析出させることにより、微粒の銀粉であって、しかも粉粒の凝集の少ない単分散により近い分散性を備える微粒銀粉を得る方法が提案されている。 For example, in Patent Document 3 (Japanese Patent Laid-Open No. 2005-48237), an alkali or complexing agent is added to a silver salt-containing aqueous solution to form a silver complex-containing aqueous solution, and then a polyhydric phenol such as hydroquinone is used as a reducing agent. Is added to reduce the amount of finely dispersed spherical silver powder having a particle size of 0.6 μm or less, thereby reducing and precipitating fine silver powder, which has a dispersibility closer to monodispersion with less aggregation of the powder particles. A method for obtaining fine silver powder has been proposed.
　また、特許文献４（特開２０１０－７０７９３号公報）には、硝酸銀水溶液とアンモニア水とを混合して反応させて銀アンミン錯体水溶液を得、種になる粒子およびイミン化合物の存在下において、当該銀アンミン錯体水溶液と還元剤水溶液とを混合して、銀粒子を還元析出させることで、平均粒径が０．１μｍ以上、１μｍ未満であり、粒度分布がシャープでかつ高分散性の球状銀粉を得る方法が提案されている。 Patent Document 4 (Japanese Patent Laid-Open No. 2010-70793) discloses a silver ammine complex aqueous solution obtained by mixing and reacting an aqueous silver nitrate solution and aqueous ammonia, and in the presence of seed particles and an imine compound, By mixing a silver ammine complex aqueous solution and a reducing agent aqueous solution to reduce and precipitate silver particles, an average particle size of 0.1 μm or more and less than 1 μm, a sharp particle size distribution and a highly dispersible spherical silver powder are obtained. A method of obtaining has been proposed.
特開２００６－２２２８号公報JP 2006-2228 A 特開２００７－２７０３３４号公報JP 2007-270334 A 特開２００５－４８２３７号公報JP 2005-48237 A 特開２０１０－７０７９３号公報JP 2010-70793 A
　導電性ペーストは、塗布する素地や用いる用途によって様々な温度で焼成されるが、焼成温度での導電性フィラー、すなわち銀粉の熱収縮率と素地との相性が悪いと、素地（基板）と銀膜との間に剥離が生じたり、反りや変形、クラックが発生したりするなどの不具合が生じることになる。特に銀粉が微粒になるほど熱収縮率が大きくなる傾向があるため、素地（基板）と銀粉との熱収縮挙動の差が大きくなり、素地（基板）と銀膜との間の剥離、反りや変形、クラックなどがより一層生じやすくなる。 The conductive paste is baked at various temperatures depending on the substrate to be applied and the application to be used. However, if the thermal contraction rate of the conductive filler at the baking temperature, that is, the silver powder, is not compatible with the substrate, the substrate (substrate) and silver Problems such as peeling between the film, warping, deformation, and cracking may occur. In particular, as the silver powder becomes finer, the thermal shrinkage tends to increase, so the difference in heat shrinkage between the substrate (substrate) and the silver powder increases, and the substrate (substrate) and the silver film peel, warp or deform. , Cracks and the like are more likely to occur.
　結晶シリコン型太陽電池は、一般的にシリコン基板（ｐ型）にｎ型拡散層を形成してｐｎ接合を形成し、シリコン基板（ｐ型）の裏面側に酸化膜を介して裏面電極を積層する一方、ｎ型拡散層の受光面側（表面側）には、反射防止膜を積層すると共に、銀ペーストを印刷及び焼成して銀電極を形成する構成のものが一般的であり、シリコン基板の熱ダメージを考慮して５００℃付近で銀ペーストを焼成して電極を形成するのが一般的である。 In a crystalline silicon solar cell, an n-type diffusion layer is generally formed on a silicon substrate (p-type) to form a pn junction, and a back electrode is laminated on the back side of the silicon substrate (p-type) via an oxide film. On the other hand, an antireflection film is laminated on the light-receiving surface side (surface side) of the n-type diffusion layer, and a silver electrode is generally formed by printing and baking a silver paste. In general, an electrode is formed by baking a silver paste at around 500 ° C. in consideration of thermal damage.
　そこで本発明は、焼結型導電性ペーストに導電性フィラーとして好適に用いることができる銀粉、中でも太陽電池電極用の焼結型導電性ペーストに導電性フィラーとして好適に用いることができる銀粉として、電極や回路のファインライン化に対応可能な微粒銀粉であって、しかも、５００℃での熱収縮率が低く、素地（基板）と銀粉の熱収縮挙動の差を抑えることができる新たな銀粉を提供せんとするものである。 Therefore, the present invention is a silver powder that can be suitably used as a conductive filler in a sintered conductive paste, and in particular, a silver powder that can be suitably used as a conductive filler in a sintered conductive paste for solar cell electrodes. A new silver powder that can handle fine lines of electrodes and circuits, has a low heat shrinkage rate at 500 ° C, and can suppress the difference in heat shrinkage between the substrate (substrate) and silver powder. It is to be provided.
　本発明は、ケイ素（Ｓｉ）を３０ｐｐｍ～１０００ｐｐｍ含有することを特徴とする焼結型導電性ペースト用銀粉を提案する。 The present invention proposes a silver powder for sintered conductive paste characterized by containing 30 ppm to 1000 ppm of silicon (Si).
　本発明が提案する焼結型導電性ペースト用銀粉は、ケイ素（Ｓｉ）化合物を添加してケイ素を３０ｐｐｍ～１０００ｐｐｍ含ませるようにすることにより、微粒銀粉を作製できるだけでなく、５００℃での収縮率を１５．０％以下とすることができる。よって、素地（基板）と銀粉の熱収縮挙動の差を抑えることができるから、焼結型導電性ペーストに用いる導電性フィラーとして好適に用いることができる。中でも、５００℃での収縮率を抑えることができるから、太陽電池電極用の焼結型導電性ペーストに用いる導電性フィラーとして特に好適に用いることができる。但し、本発明が提案する焼結型導電性ペースト用銀粉の用途を太陽電池電極用に限定するものではない。 The silver powder for sintered conductive paste proposed by the present invention can not only produce fine silver powder but also shrink at 500 ° C. by adding silicon (Si) compound so that silicon is contained at 30 ppm to 1000 ppm. The rate can be 15.0% or less. Therefore, since the difference in heat shrinkage behavior between the substrate (substrate) and the silver powder can be suppressed, it can be suitably used as a conductive filler used in a sintered conductive paste. Especially, since the shrinkage rate at 500 ° C. can be suppressed, it can be particularly suitably used as a conductive filler used in a sintered conductive paste for solar cell electrodes. However, the use of the silver powder for sintered conductive paste proposed by the present invention is not limited to the use for solar cell electrodes.
　次に、本発明を実施するための形態例に基づいて本発明を説明するが、本発明が次に説明する実施形態に限定されるものではない。 Next, the present invention will be described based on an embodiment for carrying out the present invention, but the present invention is not limited to the embodiment described below.
＜本銀粉＞
　本実施形態に係る焼結型導電性ペースト用銀粉（以下、「本銀粉」と称する）は、ケイ素（Ｓｉ）を含有することを特徴とする銀粉である。
　以下、本銀粉の特徴についてさらに説明する。 <Silver powder>
The silver powder for sintered conductive paste according to the present embodiment (hereinafter referred to as “main silver powder”) is a silver powder containing silicon (Si).
Hereinafter, the characteristics of the present silver powder will be further described.
（ケイ素含有量）
　本銀粉は、ケイ素（Ｓｉ）含有量が３０ｐｐｍ～１０００ｐｐｍであることが好ましい。かかる範囲でケイ素を含有すれば、ＢＥＴ比表面積を０．８ｍ２/ｇ～３．０ｍ２/ｇの範囲に制御することができるばかりか、５００℃での収縮率を１５．０％以下にすることができる。
　かかる観点から、本銀粉のケイ素（Ｓｉ）含有量は４０ｐｐｍ以上或いは７００ｐｐｍ以下であるのがさらに好ましく、中でも５０ｐｐｍ以上或いは６００ｐｐｍ以下であるのがさらに好ましい。 (Silicon content)
The silver powder preferably has a silicon (Si) content of 30 ppm to 1000 ppm. If containing silicon in such a range, the BET specific surface area not only can be controlled in the range of 0.8m 2 /g~3.0m 2 / g, the shrinkage at 500 ° C. below 15.0% can do.
From such a viewpoint, the silicon (Si) content of the present silver powder is more preferably 40 ppm or more and 700 ppm or less, and more preferably 50 ppm or more and 600 ppm or less.
　本銀粉のケイ素（Ｓｉ）含有量を調整する方法として、製造過程で添加するケイ素化合物の種類と量を調整する方法を挙げることができる。 Examples of a method for adjusting the silicon (Si) content of the present silver powder include a method for adjusting the type and amount of the silicon compound added in the production process.
　なお、本銀粉のケイ素（Ｓｉ）含有量は、銀粉粒子の内部に含有されるか、或いは、粒子の表面に物理的或いは化学的に吸着されているケイ素（Ｓｉ）の含有量である。より具体的には、銀粉を純水で洗浄したろ液の伝導率が４０μＳ／ｃｍ以下になるまで十分に洗浄した際に残存するケイ素（Ｓｉ）の量である。このような洗浄によって除去されるケイ素（Ｓｉ）は、焼結抑制剤として機能せず、銀粉の熱収縮率に寄与しないため、本銀粉のケイ素（Ｓｉ）含有量からは除外する必要がある。
　したがって、本銀粉のケイ素（Ｓｉ）含有量は、銀粉を純水で洗浄したろ液の伝導率が４０μＳ／ｃｍ以下になるまで十分に洗浄した後に測定装置で測定されるケイ素（Ｓｉ）含有量である。 The silicon (Si) content of the present silver powder is the content of silicon (Si) contained inside the silver powder particles or physically or chemically adsorbed on the surface of the particles. More specifically, this is the amount of silicon (Si) remaining when the silver powder is thoroughly washed until the conductivity of the filtrate obtained by washing with pure water is 40 μS / cm or less. Since silicon (Si) removed by such washing does not function as a sintering inhibitor and does not contribute to the thermal shrinkage rate of silver powder, it is necessary to exclude it from the silicon (Si) content of the silver powder.
Therefore, the silicon (Si) content of the present silver powder is the silicon (Si) content measured with a measuring device after the silver powder is thoroughly washed until the conductivity of the filtrate obtained by washing with pure water is 40 μS / cm or less. It is.
（比表面積）
　本銀粉のＢＥＴ比表面積（ＳＳＡ）は、０．８ｍ２/ｇ～３．０ｍ２/ｇであるのが好ましい。
　本銀粉のＢＥＴ比表面積が０．８ｍ２/ｇ～３．０ｍ２/ｇであれば、焼結型導電性ペーストの導電性フィラーとして好適に用いることができる銀粉、中でも太陽電池電極用の焼結型導電性ペーストの導電性フィラーとして好適に用いることができる微粒な銀粉であり、電極や回路のファインライン化に対応可能となる。
　よって、かかる観点から、本銀粉のＢＥＴ比表面積は０．８ｍ２/ｇ以上或いは３．０ｍ２/ｇ以下であるのが好ましく、中でも１．０ｍ２/ｇ以上或いは２．８ｍ２/ｇ以下であるのがさらに好ましく、その中でも２．６５ｍ２/ｇ以下であるのが特に好ましい。 (Specific surface area)
BET specific surface area of the silver powder (SSA) is preferably a 0.8m 2 /g~3.0m 2 / g.
If the BET specific surface area of 0.8m 2 /g~3.0m 2 / g of the silver powder, silver powder can be suitably used as the conductive filler of the sintered conductive paste, among others baked for a solar cell electrode It is a fine silver powder that can be suitably used as a conductive filler of a binder-type conductive paste, and can cope with fine lines of electrodes and circuits.
Therefore, from this point of view, the BET specific surface area of the present silver powder is preferably 0.8 m 2 / g or more or 3.0 m 2 / g or less, particularly 1.0 m 2 / g or more or 2.8 m 2 / g or less. More preferably, it is particularly preferably 2.65 m 2 / g or less.
　なお、ＢＥＴ比表面積を調整する方法としては、製造過程で添加するケイ素化合物の種類と量を調整したり、硝酸銀水溶液の濃度や液量を調整したり、還元剤溶液の濃度や液量を調整したりする方法を挙げることができる。 In addition, as a method of adjusting the BET specific surface area, the kind and amount of the silicon compound to be added in the production process, the concentration and amount of the silver nitrate aqueous solution, the concentration and amount of the reducing agent solution are adjusted. The method of doing can be mentioned.
（粒子形状）
　本銀粉は、粒子形状を特に限定するものではないが、球形状或いは略球形状であるのが好ましい。また、導電性ペースト用としては、当該球形状粒子或いは略球形状の粒子を加工してなるフレーク状粒子であるのも好ましいし、また、前記球形状或いは略球形状の粒子と該フレーク状粒子の混合品も好ましい。 (Particle shape)
Although this silver powder does not specifically limit particle shape, it is preferable that it is spherical shape or substantially spherical shape. In addition, for the conductive paste, it is also preferable to use flaky particles obtained by processing the spherical particles or substantially spherical particles, and the spherical or substantially spherical particles and the flaky particles. The mixed product is also preferable.
（Ｄ５０）
　本銀粉のＤ５０、すなわちレーザー回折散乱式粒度分布測定法により測定して得られる体積基準粒度分布によるＤ５０は０．５０μｍ～１．５０μｍであるのが好ましい。
　本銀粉のＤ５０が０．５０μｍ～１．５０μｍであれば、ペーストを印刷する際に細線を容易に形成することが可能である。
　よって、かかる観点から、本銀粉のＤ５０は０．５０μｍ以上或いは１．５０μｍ以下であるのが好ましく、中でも０．７０μｍ以上或いは１．２０μｍ以下であるのがさらに好ましく、その中でも０．９０μｍ以上であるのが特に好ましい。 (D50)
The D50 of the present silver powder, that is, the D50 based on the volume-based particle size distribution obtained by measuring by the laser diffraction / scattering particle size distribution measuring method is preferably 0.50 μm to 1.50 μm.
If the D50 of the present silver powder is 0.50 μm to 1.50 μm, it is possible to easily form fine lines when printing the paste.
Therefore, from this viewpoint, the D50 of the present silver powder is preferably 0.50 μm or more or 1.50 μm or less, more preferably 0.70 μm or more or 1.20 μm or less, and more preferably 0.90 μm or more. It is particularly preferred.
　Ｄ５０を調整するには、製造過程で添加するケイ素化合物の種類と量を調整したり、硝酸銀水溶液の濃度や液量を調整したり、還元剤溶液の濃度や液量を調整したりする方法を挙げることができる。 To adjust D50, adjust the type and amount of silicon compound added in the manufacturing process, adjust the concentration and volume of the silver nitrate aqueous solution, and adjust the concentration and volume of the reducing agent solution. Can be mentioned.
（熱収縮率）
　本銀粉は、前述したように、太陽電池に使用するシリコン基板との接着性、より具体的に言えば、５００℃で焼成した際に生じる銀粉の収縮によるシリコン基板の剥離などを生じない接着性の観点から、本銀粉の５００℃における熱収縮率が１５．０％以下であるのが好ましく、中でも４．０％以上或いは１４．０％以下であるのがさらに好ましく、その中でも１２．０％以下であるのが特に好ましい。
　本銀粉では、製造過程で添加するケイ素化合物の種類と量を調整することにより、５００℃における銀粉の熱収縮率を調整することができる。 (Heat shrinkage)
As described above, the present silver powder has an adhesive property with a silicon substrate used in a solar cell, more specifically, an adhesive property that does not cause peeling of the silicon substrate due to shrinkage of the silver powder that occurs when fired at 500 ° C. In view of the above, the heat shrinkage rate of the present silver powder at 500 ° C. is preferably 15.0% or less, more preferably 4.0% or more or 14.0% or less, and more preferably 12.0%. It is particularly preferred that
In the present silver powder, the heat shrinkage rate of the silver powder at 500 ° C. can be adjusted by adjusting the kind and amount of the silicon compound added in the production process.
＜製法＞
　次に、本銀粉の好ましい製造方法について説明する。 <Production method>
Next, the preferable manufacturing method of this silver powder is demonstrated.
　本銀粉の製造方法の一例として、硝酸銀などの銀溶液に還元剤を加える前或いは加えると共に、ケイ素化合物を加えて還元する方法を挙げることができる。 As an example of the method for producing the present silver powder, there can be mentioned a method in which a reducing agent is added to a silver solution such as silver nitrate before or at the same time as a silicon compound is added.
　より具体的に言えば、硝酸銀などの銀水溶液に錯化剤を加えた後、還元剤を添加する前或いは加えると共に、ケイ素化合物を加えて撹拌し、次いで必要に応じて分散剤を添加して撹拌させながら反応させて銀粒子を還元析出させ、その後、ろ過、洗浄、乾燥させて本銀粉を製造することができる。 More specifically, after adding a complexing agent to a silver aqueous solution such as silver nitrate, before or after adding a reducing agent, add a silicon compound and stir, and then add a dispersing agent as necessary. The silver particles can be produced by reducing and precipitating silver particles by stirring and then filtering, washing and drying.
　ここで、ケイ素化合物としては、ケイ酸ナトリウムやケイ酸カリウムなどのケイ酸塩のほか、シランカップリング剤などのケイ素化合物を挙げることができる。中でも、微粒化及び熱収縮率低下の効果の観点から、二酸化ケイ素（ＳｉＯ2）ではなく、ケイ酸ナトリウムやケイ酸カリウムなどのケイ酸塩が好ましい。 Here, examples of the silicon compound include silicates such as sodium silicate and potassium silicate, and silicon compounds such as a silane coupling agent. Among these, silicates such as sodium silicate and potassium silicate are preferable instead of silicon dioxide (SiO 2 ) from the viewpoint of the effect of atomization and reduction of the heat shrinkage rate.
　なお、硝酸銀などの銀水溶液は、硝酸銀、銀塩錯体、及び銀中間体のいずれかを含有する水溶液、又はスラリーを使用することができる。
　また、錯化剤としては、例えばアンモニア水、アンモニウム塩、キレート化合物等を挙げることができる。
　還元剤としては、例えばアスコルビン酸、亜硫酸塩、アルカノールアミン、過酸化水素水、ギ酸、ギ酸アンモニウム、ギ酸ナトリウム、グリオキサール、酒石酸、次亜燐酸ナトリウム、水素化ホウ素金属塩、ジメチルアミンボラン、ヒドラジン、ヒドラジン化合物、ヒドロキノン、ピロガロール、ぶどう糖、没食子酸、ホルマリン、無水亜硫酸ナトリウム、ロンガリットなどを含む水溶液を挙げることができる。
　分散剤としては、例えば脂肪酸、脂肪酸塩、界面活性剤、有機金属、キレート剤、保護コロイド等を挙げることができる。 In addition, silver solution, such as silver nitrate, can use the aqueous solution or slurry containing either silver nitrate, a silver salt complex, and a silver intermediate.
Examples of complexing agents include ammonia water, ammonium salts, chelate compounds and the like.
Examples of the reducing agent include ascorbic acid, sulfite, alkanolamine, aqueous hydrogen peroxide, formic acid, ammonium formate, sodium formate, glyoxal, tartaric acid, sodium hypophosphite, metal borohydride, dimethylamine borane, hydrazine, hydrazine Examples thereof include an aqueous solution containing a compound, hydroquinone, pyrogallol, glucose, gallic acid, formalin, anhydrous sodium sulfite, Rongalite and the like.
Examples of the dispersant include fatty acids, fatty acid salts, surfactants, organic metals, chelating agents, protective colloids and the like.
＜用途＞
　本銀粉は、導電ペースト用、特に焼結型導電性ペースト用の銀粉として好適である。 <Application>
The silver powder is suitable as a silver powder for a conductive paste, particularly for a sintered conductive paste.
　焼結型導電性ペーストは、例えば有機ビヒクル中に、本銀粉をガラスフリットと共に混合することで調製することができる。
　この際、ガラスフリットとしては、例えば、鉛ボロシリケートガラスや、ジンクボロシリケート等の無鉛ガラスも挙げることができる。
　また、樹脂バインダーとしては、例えば任意の樹脂バインダーを使用することができる。例えばエポキシ樹脂、ポリエステル樹脂、ケイ素樹脂、ユリア樹脂、アクリル樹脂、セルロース樹脂から選ばれる１種以上を含む組成を採用するのが望ましい。 The sintered conductive paste can be prepared, for example, by mixing the present silver powder together with glass frit in an organic vehicle.
In this case, examples of the glass frit include lead-free glass such as lead borosilicate glass and zinc borosilicate.
Moreover, as a resin binder, arbitrary resin binders can be used, for example. For example, it is desirable to employ a composition containing at least one selected from an epoxy resin, a polyester resin, a silicon resin, a urea resin, an acrylic resin, and a cellulose resin.
　本銀粉は、５００℃における銀粉の熱収縮率が１５．０％以下であり、太陽電池におけるシリコン基板との相性が極めてよいから、本銀粉を用いた導電ペーストは、太陽電池の電極に用いるのが特に好ましい。但し、かかる用途に限定されるものではない。 Since this silver powder has a thermal shrinkage of 15.0% or less at 500 ° C. and is extremely compatible with a silicon substrate in a solar cell, the conductive paste using this silver powder is used for an electrode of a solar cell. Is particularly preferred. However, it is not limited to such a use.
＜語句の説明＞
　本明細書において「Ｘ～Ｙ」（Ｘ，Ｙは任意の数字）と表現する場合、特にことわらない限り「Ｘ以上Ｙ以下」の意と共に、「好ましくはＸより大きい」或いは「好ましくはＹより小さい」の意も包含する。
　また、「Ｘ以上」（Ｘは任意の数字）或いは「Ｙ以下」（Ｙは任意の数字）と表現した場合、「Ｘより大きいことが好ましい」或いは「Ｙ未満であることが好ましい」旨の意図も包含する。 <Explanation of words>
In the present specification, when expressed as “X to Y” (X and Y are arbitrary numbers), “X is preferably greater than X” or “preferably Y”, with the meaning of “X to Y” unless otherwise specified. It also includes the meaning of “smaller”.
In addition, when expressed as “X or more” (X is an arbitrary number) or “Y or less” (Y is an arbitrary number), it is “preferably greater than X” or “preferably less than Y”. Includes intentions.
　以下、本発明を下記実施例及び比較例に基づいてさらに詳述する。
　実施例および比較例で得られた銀粉に関して、以下に示す方法で諸特性を評価した。 Hereinafter, the present invention will be further described in detail based on the following examples and comparative examples.
With respect to the silver powder obtained in Examples and Comparative Examples, various characteristics were evaluated by the following methods.
（１）ケイ素（Ｓｉ）含有量
　伝導率４０μＳ／ｃｍ以下になるまで純水を用いて洗浄し、このように洗浄して得られた銀粉（サンプル）を、サーモフィッシャーサイエンティフィック社製のＩＣＰ発光分光分析装置（ｉＣＡＰ６３００ＤＵＯ）を用いて、ＪＩＳ　Ｈ　１０６１：１９９８（銅及び銅合金中のけい素定量方法）の「８．ＩＣＰ発光分光法」に準拠して、ケイ素含有量を測定した。 (1) Silicon (Si) content Washed with pure water until the conductivity is 40 μS / cm or less, and the silver powder (sample) obtained by washing in this way is ICP manufactured by Thermo Fisher Scientific Co., Ltd. Using an emission spectroscopic analyzer (iCAP6300DUO), the silicon content was measured in accordance with “8. ICP emission spectroscopy” of JIS H 1061: 1998 (silicon determination method in copper and copper alloys).
（２）ＢＥＴ比表面積（ＳＳＡ）
　ＱＵＡＮＴＡＣＨＲＯＭＥ社製の比表面積測定装置（モノソーブＭＳ－１８）を用いて、ＪＩＳ　Ｒ　１６２６：１９９６（ファインセラミックス粉体の気体吸着ＢＥＴ法による比表面積の測定方法）の「６．２流動法の（３．５）一点法」に準拠して、ＢＥＴ比表面積（ＳＳＡ）の測定を行った。その際、キャリアガスであるヘリウムと、吸着質ガスである窒素の混合ガスを使用した。 (2) BET specific surface area (SSA)
Using a specific surface area measuring device (Monosorb MS-18) manufactured by QUANTACHROME, JIS R 1626: 1996 (Method for measuring specific surface area of fine ceramic powder by gas adsorption BET method), .5) Single point method ", BET specific surface area (SSA) was measured. At that time, a mixed gas of helium as a carrier gas and nitrogen as an adsorbate gas was used.
（３）Ｄ５０
　銀粉(サンプル)０．２ｇをＩＰＡ５０ｍＬ中に入れて超音波を照射して（３分間）分散させた後、日機装社製の粒度分布測定装置（マイクロトラックＭＴ－３０００ＥＸII）により、体積基準粒度分布によるＤ５０を測定した。 (3) D50
After putting 0.2 g of silver powder (sample) into 50 mL of IPA and irradiating with ultrasonic waves (for 3 minutes), the particle size distribution measuring device (Microtrac MT-3000EXII) manufactured by Nikkiso Co., Ltd. is used. D50 was measured.
（４）熱収縮率
　銀粉（サンプル）０．２ｇを用い、４９３ｋｇの加重をかけてφ３．８ｍｍの円柱状に成形した。この成形体の縦方向の線収縮率（％）を、セイコーインスツルメンツ社製の熱機械分析装置（ＴＭＡ）（ＥＸＳＴＡＲ６０００ＴＭＡ／ＳＳ６２００）を用い、９８ｍＮの加重をかけながらＡｉｒ雰囲気中５℃／分の昇温速度で測定し、５００℃における熱収縮率（％）を求めた。 (4) Thermal shrinkage rate Using 0.2 g of silver powder (sample), a weight of 493 kg was applied and molded into a cylindrical shape of φ3.8 mm. Using a thermomechanical analyzer (TMA) manufactured by Seiko Instruments Inc. (EXSTAR6000TMA / SS6200), the linear shrinkage rate (%) of this molded body was increased by 5 ° C./min in an Air atmosphere while applying a load of 98 mN. The heat shrinkage rate (%) at 500.degree.
＜実施例１＞
　銀濃度４００ｇ／Ｌの硝酸銀水溶液５０ｍＬを純水１Ｌに溶解させて硝酸銀水溶液を調製し、濃度２５質量％のアンモニア水６０ｍＬを添加して攪拌することにより、銀アンミン錯体水溶液を得た。
　次いで、３０℃の銀アンミン錯体水溶液に、濃度５ｇ／Ｌのゼラチン水溶液８ｍＬを添加して攪拌し、さらに、ケイ酸ナトリウム溶液（５２～５７％）（和光純薬工業社製）を銀に対して０．１０質量％添加して攪拌し、濃度１１．９ｇ／Ｌのヒドラジン水溶液１Ｌを混合することにより銀粒子を還元析出させた。
　次いで、還元後のスラリーに、濃度５ｇ／Ｌのゼラチン水溶液８ｍＬを添加して攪拌した後、この銀粒子をろ過し、ろ液の伝導率が４０μＳ／ｃｍ以下となるまで水洗後、乾燥させることにより銀粉（サンプル）を得た。 <Example 1>
A silver nitrate aqueous solution was obtained by dissolving 50 mL of a silver nitrate aqueous solution having a silver concentration of 400 g / L in 1 L of pure water, adding 60 mL of ammonia water having a concentration of 25% by mass, and stirring.
Next, 8 mL of an aqueous gelatin solution having a concentration of 5 g / L is added to an aqueous silver ammine complex solution at 30 ° C. and stirred, and a sodium silicate solution (52-57%) (manufactured by Wako Pure Chemical Industries, Ltd.) is added to the silver. Then, 0.10% by mass was added and stirred, and 1 L of a hydrazine aqueous solution having a concentration of 11.9 g / L was mixed to reduce and precipitate silver particles.
Next, 8 mL of an aqueous gelatin solution having a concentration of 5 g / L is added to the reduced slurry and stirred, and then the silver particles are filtered, washed with water until the filtrate has a conductivity of 40 μS / cm or less, and then dried. Thus, silver powder (sample) was obtained.
＜実施例２＞
　ケイ酸ナトリウム溶液の添加量を、銀に対して０．５０質量％に変更した以外、実施例１と同様にして銀粉（サンプル）を得た。 <Example 2>
Silver powder (sample) was obtained in the same manner as in Example 1 except that the addition amount of the sodium silicate solution was changed to 0.50% by mass with respect to silver.
＜実施例３＞
　ケイ酸ナトリウム溶液を、ケイ酸カリウム溶液（２７～２９％）（和光純薬工業社製）に変更すると共に、その添加量を銀に対して０．１０質量％に変更した以外、実施例１と同様にして銀粉（サンプル）を得た。 <Example 3>
Example 1 except that the sodium silicate solution was changed to a potassium silicate solution (27 to 29%) (manufactured by Wako Pure Chemical Industries, Ltd.) and the addition amount was changed to 0.10% by mass with respect to silver. In the same manner, silver powder (sample) was obtained.
＜実施例４＞
　ケイ酸カリウム溶液の添加量を、銀に対して０．２５質量％に変更した以外、実施例３と同様にして銀粉（サンプル）を得た。 <Example 4>
A silver powder (sample) was obtained in the same manner as in Example 3 except that the addition amount of the potassium silicate solution was changed to 0.25% by mass with respect to silver.
＜実施例５＞
　ケイ酸カリウム溶液の添加量を、銀に対して０．５０質量％に変更した以外、実施例３と同様にして銀粉（サンプル）を得た。 <Example 5>
A silver powder (sample) was obtained in the same manner as in Example 3 except that the addition amount of the potassium silicate solution was changed to 0.50% by mass with respect to silver.
＜実施例６＞
　ケイ酸カリウム溶液の添加量を、銀に対して０．６０質量％に変更した以外、実施例３と同様にして銀粉（サンプル）を得た。 <Example 6>
Silver powder (sample) was obtained in the same manner as in Example 3 except that the addition amount of the potassium silicate solution was changed to 0.60% by mass with respect to silver.
＜実施例７＞
　ケイ酸ナトリウム溶液をシランカップリング剤（オルガノシラン、信越化学工業社製ＫＢＭ－６０３）に変更すると共に、その添加量を銀に対して０．２５質量％に変更した以外、実施例１と同様にして銀粉（サンプル）を得た。 <Example 7>
The same as in Example 1 except that the sodium silicate solution was changed to a silane coupling agent (organosilane, KBM-603 manufactured by Shin-Etsu Chemical Co., Ltd.) and the addition amount was changed to 0.25% by mass with respect to silver. Thus, silver powder (sample) was obtained.
＜比較例１＞
　ケイ酸ナトリウム溶液を添加しない以外、実施例１と同様にして銀粉（サンプル）を得た。 <Comparative Example 1>
A silver powder (sample) was obtained in the same manner as in Example 1 except that the sodium silicate solution was not added.
＜比較例２＞
　ケイ酸ナトリウム溶液を、硝酸銅（II）三水和物（和光純薬工業社製）に変更すると共に、その添加量を銀に対して０．０２質量％に変更した以外、実施例１と同様にして銀粉（サンプル）を得た。 <Comparative example 2>
The sodium silicate solution was changed to copper nitrate (II) trihydrate (manufactured by Wako Pure Chemical Industries, Ltd.) and the addition amount thereof was changed to 0.02% by mass with respect to silver. Similarly, silver powder (sample) was obtained.
＜比較例３＞
　硝酸銅（II）三水和物（和光純薬工業社製）の添加量を、銀に対して０．０４質量％に変更した以外、比較例２と同様にして銀粉（サンプル）を得た。 <Comparative Example 3>
Silver powder (sample) was obtained in the same manner as in Comparative Example 2 except that the addition amount of copper nitrate (II) trihydrate (manufactured by Wako Pure Chemical Industries, Ltd.) was changed to 0.04% by mass with respect to silver. .
＜比較例４＞
　硝酸銅（II）三水和物（和光純薬工業社製）の添加量を、銀に対して０．０８質量％に変更した以外、比較例２と同様にして銀粉（サンプル）を得た。 <Comparative Example 4>
Silver powder (sample) was obtained in the same manner as in Comparative Example 2 except that the addition amount of copper (II) nitrate trihydrate (manufactured by Wako Pure Chemical Industries, Ltd.) was changed to 0.08% by mass with respect to silver. .
＜比較例５＞
　ケイ酸ナトリウム溶液を、炭酸水素ナトリウム（和光純薬工業社製）に変更すると共に、その添加量を銀に対して０．１０質量％に変更した以外、実施例１と同様にして銀粉（サンプル）を得た。 <Comparative Example 5>
Silver powder (sample) as in Example 1, except that the sodium silicate solution was changed to sodium hydrogen carbonate (manufactured by Wako Pure Chemical Industries, Ltd.) and the addition amount was changed to 0.10% by mass with respect to silver. )
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　実施例及び比較例で得た銀粉（サンプル）は、いずれも球形状であった。
　実施例及びこれまで行った試験結果から、ケイ素化合物を銀錯塩溶液に添加すると、銀粉粒子は微粒化させることができることが分かった。詳細なメカニズムは解明できていないが、ケイ素化合物が銀粒子成長の核となって還元析出反応が進むため、核の数を制御することで粒径を制御することができ、銀粉粒子の微粒化を図ることができるものと考えることができる。
　また、銀粉粒子内部又は表面にケイ素が取り込まれると、ケイ素なしの場合や銅が取り込まれた場合に比べて、５００℃での熱収縮率が低減することが分かった。

  The silver powders (samples) obtained in the examples and comparative examples were all spherical.
From the examples and test results conducted so far, it was found that the silver powder particles can be atomized when a silicon compound is added to the silver complex salt solution. Although the detailed mechanism has not been elucidated, since the silicon compound becomes the nucleus of silver particle growth and the reduction precipitation reaction proceeds, the particle size can be controlled by controlling the number of nuclei, and the silver powder particles are atomized It can be considered that it can be achieved.
In addition, it was found that when silicon is incorporated into or on the surface of silver powder particles, the thermal shrinkage at 500 ° C. is reduced as compared with the case where silicon is not incorporated or copper is incorporated.

Claims (4)

  1. 　ケイ素（Ｓｉ）を３０ｐｐｍ～１０００ｐｐｍ含有する焼結型導電性ペースト用銀粉。 Silver powder for sintered conductive paste containing 30 ppm to 1000 ppm of silicon (Si).
  2. 　ＢＥＴ法により測定される比表面積が０．８ｍ２/ｇ～３．０ｍ２/ｇであることを特徴とする請求項１記載の焼結型導電性ペースト用銀粉。 2. The silver powder for sintered conductive paste according to claim 1, wherein the specific surface area measured by BET method is 0.8 m 2 / g to 3.0 m 2 / g.
  3. 　レーザー回折散乱式粒度分布測定法により測定して得られる体積基準粒度分布によるＤ５０が０．５０μｍ～１．５０μｍであることを特徴とする請求項１又は２に記載の焼結型導電性ペースト用銀粉。 3. The sintered conductive paste according to claim 1, wherein D50 based on a volume-based particle size distribution obtained by measuring by a laser diffraction / scattering particle size distribution measuring method is 0.50 μm to 1.50 μm. Silver powder.
  4. 　５００℃での収縮率が１５．０％以下であることを特徴とする請求項１～３の何れかに記載の焼結型導電性ペースト用銀粉。

          The silver powder for sintered conductive paste according to any one of claims 1 to 3, wherein the shrinkage at 500 ° C is 15.0% or less.

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EP3357608A4 (en) * 2015-10-30 2019-05-01 Dowa Electronics Materials Co., Ltd. Silver powder and method for producing same
CN114713838A (en) * 2022-04-25 2022-07-08 金川集团股份有限公司 Preparation method of high-tap small-particle-size sphere-like silver powder for LTCC inner electrode

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CN114713838A (en) * 2022-04-25 2022-07-08 金川集团股份有限公司 Preparation method of high-tap small-particle-size sphere-like silver powder for LTCC inner electrode

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