JP5239191B2 - Silver fine particles and method for producing the same - Google Patents

Silver fine particles and method for producing the same Download PDF

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JP5239191B2
JP5239191B2 JP2007089511A JP2007089511A JP5239191B2 JP 5239191 B2 JP5239191 B2 JP 5239191B2 JP 2007089511 A JP2007089511 A JP 2007089511A JP 2007089511 A JP2007089511 A JP 2007089511A JP 5239191 B2 JP5239191 B2 JP 5239191B2
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康男 柿原
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Toda Kogyo Corp
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Description

本発明は、低温焼成が可能な導電性ペースト、導電性接着剤又は接合材等の原料用に好適な平均粒子径20〜100nmの銀微粒子に関する。   The present invention relates to silver fine particles having an average particle diameter of 20 to 100 nm suitable for raw materials such as conductive pastes, conductive adhesives or bonding materials that can be fired at low temperature.

近年、銀微粒子は電子部品の電極や電子回路パターンを形成するための導電性ペーストの原料として多用されている。例えば、電子回路パターンは、通常、基板に銀微粒子を含有する導電性ペーストを使用して、スクリーン印刷で配線幅50μm程度のパターンを印刷した後、500℃以上の高温で焼成して形成される。   In recent years, silver fine particles have been widely used as a raw material for conductive paste for forming electrodes of electronic parts and electronic circuit patterns. For example, an electronic circuit pattern is usually formed by printing a pattern having a wiring width of about 50 μm by screen printing using a conductive paste containing silver fine particles on a substrate and then baking at a high temperature of 500 ° C. or higher. .

最近では、携帯電話に使われる電子部品の実装基板としてポリイミド製フレキシブル基板の他、より安価なPET(ポリエチレンテレフタレート)フィルムやPEN(ポリエチレンナフタレート)フィルムを使用する傾向にある。これらの基板の中ではポリイミド製フレキシブル基板がより耐熱性が高く、300℃程度まで加熱に耐えうるものもあるが高価である。そこで、将来はより安価なPETやPENが基板として主に使用されることが考えられるが、これらのフィルムはポリイミド製フレキシブル基板に比較して耐熱性が低く、200℃以下での使用が必要である。そこで、これらの基板との組み合わせでは、導電性ペーストは、200℃以下の低温で焼成可能であることが要求される。
このような低温焼成が可能な導電性ペーストの銀微粒子原料としてナノメートルサイズの銀微粒子が期待されている。これは粒子の大きさをナノメートルサイズにすることで、銀微粒子の表面活性が高くなり、銀のバルクの融点よりはるかに低い温度で焼結を生じるためである。
また、ナノメートルサイズの銀微粒子は低温で焼結するとともに、一度焼結すると耐熱性が維持されるという、従来のはんだにはない性質を利用した鉛フリーのはんだ代替材料としても期待されている。
Recently, there is a tendency to use a cheaper PET (polyethylene terephthalate) film or PEN (polyethylene naphthalate) film in addition to a polyimide flexible substrate as a mounting substrate for electronic components used in mobile phones. Among these substrates, polyimide flexible substrates have higher heat resistance and can withstand heating up to about 300 ° C., but are expensive. Therefore, in the future, cheaper PET and PEN may be used mainly as substrates, but these films have lower heat resistance than polyimide flexible substrates and need to be used at 200 ° C or lower. is there. Therefore, in combination with these substrates, the conductive paste is required to be baked at a low temperature of 200 ° C. or lower.
Nanometer-sized silver fine particles are expected as a silver fine particle raw material for such conductive paste capable of low-temperature firing. This is because by making the size of the particles nanometer, the surface activity of the silver fine particles is increased and sintering occurs at a temperature much lower than the melting point of the bulk of silver.
In addition, nanometer-sized silver fine particles are sintered at low temperatures, and once sintered, heat resistance is maintained, which is also expected as a lead-free solder replacement material that uses a property not found in conventional solders. .

ところで、低温焼成が可能な銀微粒子として、サブミクロン以下の銀微粒子の製造方法が提案されており、ガス中蒸発法や液相法である化学的還元法、熱分解還元法などが知られている。しかし、これらの方法による銀微粒子を低温焼成用の導電性ペーストの原料とするにはそれぞれ問題があった。   By the way, as a silver fine particle that can be fired at a low temperature, a production method of submicron or smaller silver fine particles has been proposed, and a chemical reduction method such as a gas evaporation method or a liquid phase method, a thermal decomposition reduction method, etc. are known. Yes. However, there are problems in using silver fine particles by these methods as raw materials for conductive pastes for low-temperature firing.

ガス中蒸発法によれば、粒子径が10nm以下の単分散微粒子が得られるが、そのままでは凝集しやすく不安定であるため、アミン等の分散剤を加えることで、分散安定化した分散溶液として取り出されている(特許文献1:特開2002−121606)。アルキルアミンの量は実施例を引用すると銀微粒子に対して5質量%以上であり、用いるアルキルアミンもドデシルアミンなど沸点が240℃以上の有機物成分である。この分散溶液を用いて電子回路を形成する場合、加熱などにより分散液中の分散剤の除去が必要であるが、用いているアミンの除去には200℃以上の加熱が必要であり、低温焼成が可能な導電性ペーストの銀微粒子原料として好適とは言い難い。また、製造するためには特別な真空装置が必要であり、簡便に銀微粒子を得る製造方法とは言い難い。   According to the gas evaporation method, monodispersed fine particles having a particle diameter of 10 nm or less can be obtained. However, since they are easily aggregated and unstable as they are, by adding a dispersant such as amine, a dispersion-stabilized dispersion solution can be obtained. (Patent Document 1: Japanese Patent Laid-Open No. 2002-121606). The amount of the alkylamine is 5% by mass or more based on the silver fine particles when referring to the examples, and the alkylamine used is an organic component having a boiling point of 240 ° C. or higher such as dodecylamine. When an electronic circuit is formed using this dispersion solution, it is necessary to remove the dispersant in the dispersion liquid by heating or the like. However, heating of 200 ° C. or more is necessary for removing the amine used, and low temperature baking is performed. It is difficult to say that it is suitable as a raw material for silver fine particles of a conductive paste that can be used. In addition, a special vacuum apparatus is necessary for the production, and it is difficult to say that the production method simply obtains silver fine particles.

また、銀微粒子を原料に用いた導電性ペーストも調製され、230℃の低温焼成において銀のバルクに近い3.0μΩcmの比抵抗値が得られている(特許文献2:特開2004−273205)。しかしながら、前記の導電性ペーストは銀微粒子に付着しているアルキルアミンをより低温で分解・飛散させる工夫が提案されているのであって、低温焼成が可能な導電性ペーストの原料の銀微粒子としては十分とは言い難い。上述したようにこの平均粒子径が10nm以下の銀微粒子にはその凝集と焼結を防止するために銀に対して5質量%以上の沸点240℃以上の有機物成分が含まれており、例えば、より低温の200℃以下で焼成を行った場合には、有機物成分を十分に飛散することが困難である。   A conductive paste using silver fine particles as a raw material is also prepared, and a specific resistance value of 3.0 μΩcm close to the bulk of silver is obtained in low-temperature firing at 230 ° C. (Patent Document 2: JP-A-2004-273205). . However, the conductive paste has been proposed to decompose and disperse the alkylamine adhering to the silver fine particles at a lower temperature, and as the silver fine particles of the conductive paste that can be fired at a low temperature, Not enough. As described above, the silver fine particles having an average particle diameter of 10 nm or less contain an organic component having a boiling point of 240 ° C. or higher of 5% by mass or more with respect to silver in order to prevent the aggregation and sintering. When firing at a lower temperature of 200 ° C. or lower, it is difficult to sufficiently disperse the organic component.

また、金属塩の熱分解法により複合金属微粒子が調製されている(特許文献3:特開2005−298921)。本方法の実施例を引用すると、平均粒子径が64.3nmのスズ、銀、銅の複合金属粒子が得られており、有機成分は2−エチルヘキサン酸でありその含有量は2.2%であった。しかし、焼結には260℃の加熱が必要であり、低温焼結が可能な導電性ペーストの好適な原料とは言い難いものである。   Further, composite metal fine particles are prepared by a thermal decomposition method of a metal salt (Patent Document 3: Japanese Patent Laid-Open No. 2005-289821). When citing an example of this method, composite metal particles of tin, silver, and copper having an average particle diameter of 64.3 nm are obtained, the organic component is 2-ethylhexanoic acid, and the content is 2.2%. Met. However, sintering requires heating at 260 ° C., and it is difficult to say that it is a suitable raw material for a conductive paste that can be sintered at a low temperature.

一方、液相還元法においては高分子顔料分散剤を用いることで含有する有機物成分がより少ない銀微粒子を調製することができる。例えば、高分子顔料分散剤の存在下、硝酸銀を水反応系でアミノアルコールにより加熱還元し平均粒子径20nm程度の銀粒子を得ることが出来る。この時の高分子顔料分散剤の量は銀に対して4質量%以上である(特許文献4:特開2003−103158)。しかしながら、高分子分散剤は一般的に分解温度が高く、例えば200℃の低温焼成を行った場合には、十分に有機物成分が飛散することが難しく、同時に低い比抵抗値を得ることは難しい。   On the other hand, in the liquid phase reduction method, silver fine particles containing fewer organic components can be prepared by using a polymer pigment dispersant. For example, silver particles having an average particle size of about 20 nm can be obtained by heating and reducing silver nitrate with amino alcohol in a water reaction system in the presence of a polymer pigment dispersant. The amount of the polymer pigment dispersant at this time is 4% by mass or more with respect to silver (Patent Document 4: JP-A-2003-103158). However, polymer dispersants generally have a high decomposition temperature. For example, when low-temperature baking at 200 ° C. is performed, it is difficult to sufficiently disperse organic components, and at the same time, it is difficult to obtain a low specific resistance value.

また、液相還元法において銀微粒子を得る手法として、カルボン酸の銀塩と脂肪族第一級アミンを混合し、還元剤により析出還元して得る手法が提案されている(特許文献5:特開2006−183072)。本提案では実施例において平均粒子径が30〜60nmの銀微粒子が得られている。しかしながら、一般的にナノメートルサイズの銀微粒子の低温焼結性は、銀微粒子そのものの特性とともに含有あるいは付着する有機物成分の特性に強く左右される。然るに前記特許文献には有機物成分の特性や含有量などは考慮されておらず、低温焼成が可能な導電性ペーストおよび導電性接着剤、接合材の原料に好適であるとは言い難いものである。   Further, as a technique for obtaining silver fine particles in the liquid phase reduction method, a technique is proposed in which a silver salt of a carboxylic acid and an aliphatic primary amine are mixed and precipitated and reduced with a reducing agent (Patent Document 5: Special). Open 2006-183072). In this proposal, silver fine particles having an average particle size of 30 to 60 nm are obtained in the examples. However, in general, the low-temperature sinterability of nanometer-sized silver fine particles strongly depends on the characteristics of the organic component contained or adhered together with the characteristics of the silver fine particles themselves. However, the patent document does not consider the characteristics and content of the organic component, and it is difficult to say that it is suitable as a raw material for conductive paste, conductive adhesive, and bonding material that can be fired at low temperature. .

ガス中蒸発法のような特別な真空装置を用いないで、化学的還元法により簡便に銀微粒子を得る方法として、硝酸銀とアミンを出発原料にアスコルビン酸で還元する方法が提案されており、平均粒子径10nm以下の銀微粒子を得ている(特許文献6:特開2005−36309)。該特許文献にはガス中蒸発法のような特別な装置が不要であり、簡便に銀微粒子を得る方法ではあるが、得られた銀微粒子に付着しているアミンを加熱により除去するためにはやはり200℃以上の加熱が必要であった。   As a method for easily obtaining silver fine particles by a chemical reduction method without using a special vacuum apparatus such as a gas evaporation method, a method of reducing silver nitrate and amine with ascorbic acid as starting materials has been proposed. Silver fine particles having a particle diameter of 10 nm or less are obtained (Patent Document 6: JP-A-2005-36309). The patent document does not require a special apparatus such as a gas evaporation method, and is a method for easily obtaining silver fine particles. However, in order to remove amine adhering to the obtained silver fine particles by heating, Again, heating at 200 ° C. or higher was necessary.

特開2002−121606号公報JP 2002-121606 A 特開2004−273205号公報JP 2004-273205 A 特開2005−298921号公報JP 2005-298922 A 特開2003−103158号公報JP 2003-103158 A 特開2006−183072号公報JP 2006-183072 A 特開2005−36309号公報JP 2005-36309 A

このように、低温焼成が可能な導電性ペーストおよび導電性接着剤、接合材の原料に好適な銀微粒子は知られていない。換言すれば200℃程度の低温焼成において分解・飛散する有機成分をできるだけ少量含有あるいは付着し、しかも室温下で焼結や凝集を生じないほど安定であり、200℃程度の低温で焼結可能な大きさの銀微粒子は知られていなかった。
本発明の目的は、上記のような状況に対応して、低温焼成が可能な導電性ペーストの原料として好適な平均粒子径20〜100nmであり、低温焼成が可能な有機物成分を含有あるいは付着し、しかも室温下で焼結や凝集を生じないほど安定であり、200℃程度の低温で焼結可能な大きさの銀微粒子とその製造法を提供する。
Thus, the silver fine particle suitable for the raw material of the electrically conductive paste which can be baked at low temperature, an electrically conductive adhesive, and a joining material is not known. In other words, it contains or adheres as little organic components as possible in a low temperature firing of about 200 ° C. and is stable enough not to cause sintering or aggregation at room temperature, and can be sintered at a low temperature of about 200 ° C. The size of the silver particles was not known.
The object of the present invention is to cope with the situation as described above, and has an average particle diameter of 20 to 100 nm suitable as a raw material for a conductive paste capable of low-temperature baking, and contains or adheres an organic component capable of low-temperature baking. Moreover, the present invention provides a silver fine particle having a size that is stable so as not to cause sintering or aggregation at room temperature and that can be sintered at a low temperature of about 200 ° C.

前記技術的課題は、次の通りの本発明によって達成できる。   The technical problem can be achieved by the present invention as follows.

即ち、本発明は、平均粒子径が20〜100nmであり、含有または付着している有機物の低温度有機物成分飛散定数((低温度有機物成分飛散定数=有機物成分の分子量×有機物成分の沸点または分解温度×銀微粒子に対する含有比率)が56以上180以下である銀微粒子である。
また、本発明は、硝酸銀と水溶性あるいは水可溶性であって沸点が200℃以下のアミンの1種類以上とを用いて調製した硝酸銀のアミン錯体のメタノール溶液を、アスコルビン酸またはエリソルビン酸を溶解させた水−メタノール混合溶媒中に添加して還元析出させて平均粒子径20〜100nmの銀微粒子を得、さらに含有または付着有機物を低温度有機物成分飛散定数((低温度有機物成分飛散定数=有機物成分の分子量×有機物成分の沸点または分解温度×銀微粒子に対する含有比率)が56以上180以下になるように調製することを特徴とする銀微粒子の製造方法である。
また、本発明は、前記有機物がプロピルアミン、ブチルアミン、モノエタノールアミンである銀微粒子である。
また、本発明の含有または付着する有機成分を低温度有機物成分飛散定数が56以上180以下範囲に調整する際に、沸点200℃以下のアルコールを1種以上加えて調製することを特徴とする銀微粒子とその製造方法である。
That is, the present invention has an average particle size of 20 to 100 nm, and contains or adheres to the low temperature organic component scattering constant of the organic matter ((low temperature organic component scattering constant = molecular weight of the organic component × boiling point or decomposition of the organic component). Silver fine particles having a temperature x a content ratio of silver fine particles of 56 to 180.
The present invention also provides a methanol solution of a silver nitrate amine complex prepared using silver nitrate and one or more amines having a water-soluble or water-soluble boiling point of 200 ° C. or less, and dissolving ascorbic acid or erythorbic acid. In addition, a silver fine particle having an average particle size of 20 to 100 nm is obtained by adding it to a water-methanol mixed solvent and reducing precipitation, and further containing or adhering organic matter is a low temperature organic component scattering constant ((low temperature organic component scattering constant = organic component). The molecular weight x the boiling point or decomposition temperature of the organic component x the content ratio with respect to the silver fine particles) is prepared so as to be 56 or more and 180 or less.
The present invention also provides silver fine particles in which the organic substance is propylamine, butylamine, or monoethanolamine.
The silver component is characterized by being prepared by adding one or more alcohols having a boiling point of 200 ° C. or lower when the organic component contained or adhering to the present invention is adjusted to have a low temperature organic component scattering constant of 56 or more and 180 or less. It is a fine particle and its manufacturing method.

本発明に係る銀微粒子は、低温で分解・飛散し、焼成時に飛散量が出来るだけ少ない有機成分を含有あるいは付着しており、しかも室温下で焼結や凝集を生じないほど安定であり、200℃程度の焼成で粒子間の焼結を生じる、低温焼成が可能な導電性ペーストおよび導電性接着剤、接合材の原料に好適な銀微粒子である。   The silver fine particles according to the present invention are decomposed and scattered at a low temperature, contain or adhere with as little organic components as possible at the time of firing, and are stable enough not to cause sintering or aggregation at room temperature. Silver fine particles suitable for raw materials for conductive pastes, conductive adhesives, and bonding materials capable of low-temperature firing, which cause sintering between particles upon firing at about 0 ° C.

さらに、本発明に係る銀微粒子の製造方法は、操作が簡便で特別な装置も不要なため、ナノメートルサイズの銀微粒子の製造で課題となる量産性への寄与も大きい。   Furthermore, since the method for producing silver fine particles according to the present invention is simple in operation and does not require a special apparatus, it greatly contributes to mass productivity, which is a problem in the production of nanometer-sized silver fine particles.

本発明の構成をより詳しく説明すれば次の通りである。   The configuration of the present invention will be described in more detail as follows.

発明者は低温で分解・飛散し、焼成時に飛散量が出来るだけ少ない有機成分を含有あるいは付着しており、しかも室温下で焼結や凝集を生じないほど安定であり、低温焼成が可能な導電性ペーストおよび導電性接着剤、接合材の原料に好適な銀微粒子を得るために誠心誠意検討した結果、数1のように定義した低温度有機物成分飛散定数が規定範囲内にあてはまる有機物成分を含有あるいは付着した銀微粒子が課題を解決することを見出した。
また、同時に数1のように定義した低温度有機物成分飛散定数が規定範囲内にあてはまる有機物成分を含有あるいは付着した銀微粒子であり、低温焼結性という特長を有してかつ室温において焼結や凝集が生じない銀微粒子の大きさは平均粒子径20〜100nmの銀微粒子であることを見出した。
The inventor decomposes and scatters at a low temperature, contains or adheres as little organic components as possible during firing, and is stable enough not to sinter or agglomerate at room temperature. As a result of sincere investigation to obtain silver fine particles suitable as a raw material for conductive pastes, conductive adhesives, and bonding materials, it contains organic components that fall within the specified range for the low-temperature organic component scattering constant defined as in Equation 1 Alternatively, it was found that the attached silver fine particles solve the problem.
At the same time, silver fine particles containing or adhering an organic component whose low-temperature organic component scattering constant defined in Equation 1 falls within the specified range, has the feature of low-temperature sinterability, and can be sintered at room temperature. It has been found that the size of silver fine particles that do not cause aggregation is silver fine particles having an average particle size of 20 to 100 nm.

<数1>
低温度有機物成分飛散定数 =(有機物成分の分子量)×(有機物成分の沸点または分解温度)×(銀微粒子に対する含有比率(重量比))
<Equation 1>
Low temperature organic component scattering constant = (molecular weight of organic component) x (boiling point or decomposition temperature of organic component) x (content ratio to silver fine particles (weight ratio))

前記数1の各数値の意味は次のとおりである。   The meanings of the numerical values in Equation 1 are as follows.

低温焼成時に分解・飛散するためには有機物成分の分子量はより小さい方が好ましい。また、分子間力を反映する有機物の沸点あるいは分解温度は出来るだけ低い方が好ましい。またさらには、含有または付着している有機物成分の量が多いと焼成後の収縮率が高くなったり、膜質を悪化させるためできるだけ量が少ない方が好ましい。特に接合材として用いた場合には、接合部のボイドを低減する目的でガス化する有機物成分を極力抑える必要がある。また、含有あるいは付着している有機成分が多い場合には、導電性ペーストや導電性接着剤、接合材を調製する場合、溶剤や樹脂の選択時に自由度が減少してしまうので好ましくない。   In order to decompose and scatter during low-temperature firing, the molecular weight of the organic component is preferably smaller. Moreover, it is preferable that the boiling point or decomposition temperature of the organic substance reflecting the intermolecular force is as low as possible. Furthermore, when the amount of the organic component contained or adhered is large, it is preferable that the amount is as small as possible in order to increase the shrinkage ratio after baking or deteriorate the film quality. In particular, when used as a bonding material, it is necessary to suppress as much as possible an organic component that is gasified for the purpose of reducing voids in the bonded portion. Moreover, when there are many organic components contained or adhering, when preparing an electrically conductive paste, an electrically conductive adhesive, and a joining material, since a freedom degree will reduce at the time of selection of a solvent and resin, it is unpreferable.

数1において低温度有機物成分飛散定数の上限値は180である。前記数値が180を超える場合には、有機物成分が低温焼成時に分解・飛散しにくいか、あるいは有機物成分が分解・飛散する際に発生するガスの量が多く、導電性膜の緻密性が損なわれたり、収縮率が高くなってしまう。さらに導電性ペーストや導電性接着剤、接合材に用いた場合、溶剤や樹脂の選択時に自由度が減少してしまう。好ましい上限値は172である。   In Equation 1, the upper limit value of the low temperature organic component scattering constant is 180. If the numerical value exceeds 180, the organic component is difficult to decompose or scatter during low-temperature firing, or the amount of gas generated when the organic component decomposes or scatters is large, and the denseness of the conductive film is impaired. Or shrinkage rate will be high. Furthermore, when it is used for a conductive paste, a conductive adhesive, or a bonding material, the degree of freedom is reduced when selecting a solvent or resin. A preferred upper limit is 172.

また、数1の低温度有機物成分飛散定数の下限値は56である。数値が56より小さすぎる場合には銀微粒子の凝集または焼結を室温下において十分に防ぐことが出来なくなり、結果、銀微粒子そのものの低温焼結性という特性を損なってしまう。好ましい下限値は57である。   In addition, the lower limit value of the low temperature organic component scattering constant of Equation 1 is 56. When the numerical value is too small, aggregation or sintering of the silver fine particles cannot be sufficiently prevented at room temperature, and as a result, the low temperature sintering property of the silver fine particles themselves is impaired. A preferred lower limit is 57.

なお、有機物成分が2種以上の場合は各有機物成分に対する低温度有機物成分飛散定数を算出し、その合計値が上述した規定範囲内に入るように調製する。   In addition, when there are two or more organic components, the low temperature organic component scattering constant for each organic component is calculated, and the total value is adjusted so as to fall within the specified range.

銀微粒子の平均粒子径は20〜100nmである。平均粒子径が20nmより小さい場合には、その粒子径を安定に維持するための凝集防止剤の分子量が大きくなったり、含有あるいは付着量が多くなったり、沸点あるいは分解温度が高くなるなどして、結果、低温度有機物成分飛散定数が180を越えてしまう。平均粒子径が100nmより大きい場合、銀微粒子の低温焼結性という特長が低下するので好ましくない。好ましくは50〜80nmである。   The average particle diameter of the silver fine particles is 20 to 100 nm. When the average particle size is smaller than 20 nm, the molecular weight of the aggregation inhibitor for maintaining the particle size stably increases, the content or adhesion amount increases, the boiling point or the decomposition temperature increases, etc. As a result, the low temperature organic component scattering constant exceeds 180. When the average particle diameter is larger than 100 nm, the feature of low-temperature sinterability of the silver fine particles is not preferable. Preferably it is 50-80 nm.

本発明に係る銀微粒子は以下のように製造することが出来る。   The silver fine particles according to the present invention can be produced as follows.

すなわち、硝酸銀と水溶性あるいは水可溶性であり沸点が200℃以下のアミンを1種類以上用いて調製した硝酸銀のアミン錯体を、水−メタノール混合溶媒中においてアスコルビン酸またはエリソルビン酸により還元することで粒子径20〜100nmの銀微粒子を得、さらに含有または付着有機物成分を低温度有機物成分飛散定数((低温度有機物成分飛散定数=有機物成分の分子量×有機物成分の沸点または分解温度×銀微粒子に対する含有比率)が56以上180以下になるように、精製、乾燥させる製造法である。
また、精製後の銀微粒子に沸点200℃以下のアルコールを1種以上加えた後、有機物成分を低温度有機物成分飛散定数((低温度有機物成分飛散定数=有機物成分の分子量×有機物成分の沸点または分解温度×銀微粒子に対する含有比率)が56以上180以下になるように、乾燥させる製造法である。
That is, particles are obtained by reducing a silver nitrate amine complex prepared by using silver nitrate and one or more water-soluble or water-soluble amines having a boiling point of 200 ° C. or less with ascorbic acid or erythorbic acid in a water-methanol mixed solvent. Silver fine particles having a diameter of 20 to 100 nm are obtained, and further containing or adhering organic components are dispersed at low temperature organic component scattering constants ((low temperature organic component scattering constant = molecular weight of organic components × boiling point or decomposition temperature of organic components × content ratio to silver fine particles) ) Is refined and dried so that it becomes 56 or more and 180 or less.
In addition, after adding one or more kinds of alcohol having a boiling point of 200 ° C. or less to the refined silver fine particles, the organic component is converted into a low temperature organic component scattering constant ((low temperature organic component scattering constant = molecular weight of organic component × boiling point of organic component or This is a production method of drying so that the decomposition temperature x the content ratio with respect to the silver fine particles is 56 or more and 180 or less.

以下、水溶性あるいは水可溶性であり沸点が200℃以下のアミンの代表としてブチルアミンを用いた例について記述するが、プロピルアミン、モノエタノールアミンなどのアミンでも同様に調製が可能である。
また、上述した硝酸銀と水溶性あるいは水可溶性であり沸点が200℃以下のアミンを1種類以上用いて調製した硝酸銀のアミン錯体を、水−メタノール混合溶媒中においてアスコルビン酸またはエリソルビン酸により還元することを特徴とする基本的な概念が同様であれば、以下の条件に限定されるものではない。例えば、メタノールの量や水の量は、用いるアミンの溶液への溶解性、反応容器と攪拌機構によりその最適な体積比率は変化する。
Hereinafter, an example using butylamine as a representative of an amine having a water solubility or a water solubility and a boiling point of 200 ° C. or less will be described, but an amine such as propylamine and monoethanolamine can be similarly prepared.
In addition, the silver nitrate amine complex prepared using one or more of the above-described silver nitrate and water-soluble or water-soluble amine having a boiling point of 200 ° C. or lower is reduced with ascorbic acid or erythorbic acid in a water-methanol mixed solvent. If the basic concept characterized by is the same, it is not limited to the following conditions. For example, the optimal volume ratio of the amount of methanol and the amount of water varies depending on the solubility of the amine used in the solution, the reaction vessel and the stirring mechanism.

はじめに、硝酸銀とブチルアミンにより銀アミン錯体を発熱に注意しながらメタノール溶媒中で形成させる。発熱量が多いと、硝酸銀がアミンで還元されて好ましくないので、水浴などで溶液の温度が上昇しすぎないように配慮する。硝酸銀とブチルアミンのモル比率は1:2〜1:2.5が好ましい。より好ましくは1:2〜1:2.2である。ブチルアミンの量がこの比率より多い場合には生成する銀微粒子同士が凝集する傾向にあり、少ない場合には大きな粒子が生成しやすい傾向がある。   First, a silver amine complex is formed in a methanol solvent with attention to heat generation by silver nitrate and butylamine. If the calorific value is large, silver nitrate is reduced with an amine, which is not preferable. Therefore, care should be taken so that the temperature of the solution does not rise too much in a water bath or the like. The molar ratio of silver nitrate to butylamine is preferably 1: 2 to 1: 2.5. More preferably, it is 1: 2 to 1: 2.2. When the amount of butylamine is larger than this ratio, the silver fine particles to be produced tend to aggregate, and when it is small, large particles tend to be produced.

次に、還元剤であるアスコルビン酸またはエリソルビン酸を水中に溶解させる。アスコルビン酸またはエリソルビン酸は硝酸銀に対して1.0〜2.0当量が好ましく、より好ましくは1.0〜1.5当量である。アスコルビン酸またはエリソルビン酸が2当量より多い場合には、生成した銀微粒子同士が凝集した銀粉が得られる傾向がある。   Next, ascorbic acid or erythorbic acid as a reducing agent is dissolved in water. Ascorbic acid or erythorbic acid is preferably 1.0 to 2.0 equivalents, more preferably 1.0 to 1.5 equivalents, relative to silver nitrate. When the amount of ascorbic acid or erythorbic acid is more than 2 equivalents, a silver powder in which the generated silver fine particles are aggregated tends to be obtained.

還元剤を水に溶解させた後にメタノールを添加しよく混合する。   After dissolving the reducing agent in water, methanol is added and mixed well.

銀アミン錯体を形成させた溶液のメタノールの体積量をA、アスコルビン酸またはエリソルビン酸を溶解させた溶液中のメタノールの体積量をA、アスコルビン酸またはエリソルビン酸を溶解させた溶液中の水の体積量をBとした場合、A:A:Bの比率は1:0〜1:1〜3に近くなるように調製することが好ましい。この体積比率から大きくずれていたとしても低温焼成が可能な大きさの銀微粒子を得ることはできるが、大きな粒子が生成する場合や、その後の粉砕が困難と考えられる2次凝集体が得られるなど、低温焼成が可能な銀微粒子の収率が悪化する傾向にある。 The volume of methanol in the solution in which the silver amine complex is formed is A, the volume of methanol in the solution in which ascorbic acid or erythorbic acid is dissolved is A * , and the water in the solution in which ascorbic acid or erythorbic acid is dissolved When the volume is B, it is preferable to prepare such that the ratio of A: A * : B is close to 1: 0 to 1: 1-3. Even if there is a large deviation from this volume ratio, it is possible to obtain silver fine particles of a size that can be fired at low temperature, but when large particles are produced or secondary aggregates that are considered to be difficult to pulverize thereafter are obtained. For example, the yield of silver fine particles that can be fired at a low temperature tends to deteriorate.

続いて、硝酸銀とブチルアミンを溶解させたメタノール溶液を、アスコルビン酸またはエリソルビン酸を溶解させた水−メタノール溶液中に滴下する。水−メタノール溶液はできるだけよく攪拌した方が好ましい。攪拌が不十分であると、大きな粒子が生成しやすい傾向にある。   Subsequently, a methanol solution in which silver nitrate and butylamine are dissolved is dropped into a water-methanol solution in which ascorbic acid or erythorbic acid is dissolved. The water-methanol solution is preferably stirred as well as possible. If the stirring is insufficient, large particles tend to be generated.

滴下するときの溶液の温度は15℃〜30℃が好ましい。より好ましくは18℃〜25℃である。この範囲より低温であるとその後の粉砕が困難な2次凝集体が得られ、この範囲より高温であると大きな粒子が生成する傾向にある。   The temperature of the solution when dropping is preferably 15 ° C to 30 ° C. More preferably, it is 18 degreeC-25 degreeC. When the temperature is lower than this range, secondary aggregates that are difficult to pulverize thereafter are obtained, and when the temperature is higher than this range, large particles tend to be generated.

A液とB液の滴下の方向を反対にした場合、すなわち、硝酸銀とブチルアミンを溶解させたメタノール溶液に、アスコルビン酸またはエリソルビン酸を溶解させた水−メタノール溶液中を滴下した場合には、銀微粒子の大きさは微細なものになるが、銀微粒子同士が房状に凝集した銀粉が得られてしまう傾向にある。   When the direction of dropping liquid A and liquid B is reversed, that is, when a water-methanol solution in which ascorbic acid or erythorbic acid is dissolved in a methanol solution in which silver nitrate and butylamine are dissolved, silver Although the size of the fine particles becomes fine, silver powder in which the silver fine particles are aggregated in a tuft shape tends to be obtained.

滴下終了後、1時間以上攪拌を続けたのち静置すると銀微粒子が沈降してくる。上澄み液をデカンテーションにより取り除く。続いて、水を添加、静置、デカンテーションを繰り返して、余分な還元剤、ブチルアミン、硝酸銀などを取り除く。メタノールを用いて、余分な還元剤、ブチルアミン又は硝酸銀等を除去すると有機物が過剰に除去されてしまい、本発明の効果が得られない。   When the stirring is continued for 1 hour or more after completion of the dropping, the silver fine particles are settled when allowed to stand. The supernatant is removed by decantation. Subsequently, water is added, allowed to stand, and decantation is repeated to remove excess reducing agent, butylamine, silver nitrate, and the like. When excess reducing agent, butylamine, silver nitrate, or the like is removed using methanol, organic substances are excessively removed, and the effects of the present invention cannot be obtained.

生成した銀微粒子を、例えば、40℃の乾燥機で乾燥させ水分を取り除くと、平均粒子径20〜100nmであり、含有あるいは付着している有機物成分が銀に対して0.5質量%〜3質量%である銀微粒子を得ることができる。   When the produced silver fine particles are dried by, for example, a dryer at 40 ° C. to remove moisture, the average particle diameter is 20 to 100 nm, and the organic component contained or adhered is 0.5% by mass to 3% with respect to silver. Silver fine particles having a mass% can be obtained.

このときの低温度有機物成分飛散定数は28〜180の範囲になる。低温度有機物成分飛散定数が56未満の銀微粒子は、乾燥前に沸点が200℃以下のアルコールを混合させた後に乾燥させて、低温度有機物成分飛散定数が56〜180の範囲になるように調製することが出来る。
用いる沸点が200℃以下のアルコールとしては、エタノール、プロパノール、ブタノール、ペンタノール、ヘキサノール、ヘプタノール、オクタノール、エチレングリコール等を1種以上用いることが出来る。アルコールの中でも特にエチレングリコールが好ましい。
At this time, the low temperature organic component scattering constant is in the range of 28 to 180. Silver fine particles having a low temperature organic component scattering constant of less than 56 are prepared by mixing alcohol having a boiling point of 200 ° C. or less before drying, and drying so that the low temperature organic component scattering constant is in the range of 56 to 180. I can do it.
As the alcohol having a boiling point of 200 ° C. or lower, one or more of ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, ethylene glycol and the like can be used. Among alcohols, ethylene glycol is particularly preferable.

上記の方法で得られた銀微粒子を大気中、200℃で30分焼成すると、銀微粒子同士が低温加熱にもかかわらず焼結している状態が確認できる。   When the silver fine particles obtained by the above method are baked at 200 ° C. for 30 minutes in the air, it can be confirmed that the silver fine particles are sintered despite low-temperature heating.

本発明の代表的な実施の形態は次の通りである。本発明は、これらの実施例に限定されるものではない。   A typical embodiment of the present invention is as follows. The present invention is not limited to these examples.

銀微粒子の平均粒子径は,調製した銀粒子の走査型電子顕微鏡写真(×10万倍、HITACHI製 S−4800)を撮影し、写真上100個の銀粒子の粒径を測定し、その平均値を算出し、平均粒径とした。   The average particle size of the silver fine particles was obtained by taking a scanning electron micrograph (× 100,000 times, S-4800 manufactured by HITACHI) of the prepared silver particles, measuring the particle size of 100 silver particles on the photograph, and calculating the average The value was calculated and taken as the average particle size.

含有あるいは付着している有機成分の量は熱分析装置(Seiko Instruments Inc. 製 EXSTAR 6000 TG/DTA6300)を用い、乾燥空気を300ml/minフローした条件下、室温から550℃まで10℃/minで昇温加熱し、加熱前のサンプル量から加熱終了後のサンプル量を差し引いた量を含有有機成分として測定した。   The amount of the organic component contained or adhered was 10 ° C./min from room temperature to 550 ° C. under a condition of flowing dry air at 300 ml / min using a thermal analyzer (EXSTAR 6000 TG / DTA 6300 manufactured by Seiko Instruments Inc.). The sample was heated at an elevated temperature, and the amount obtained by subtracting the sample amount after completion of heating from the sample amount before heating was measured as the contained organic component.

実施例1
500mLのビーカーに硝酸銀40g、ブチルアミン(分子量:73.14、沸点:78℃)37.9g、メタノール200mLを加え、1時間攪拌しA液を調製した。別に2Lのビーカーにアスコルビン酸62.2gを取り、水400mLを加え攪拌して溶解し、続いてメタノール200mLを加えB液を調製した。
B液をよく攪拌しA液をB液に1時間20分かけて滴下した。滴下終了後、3時間30分攪拌を継続した。攪拌終了後、30分間静置し固形物を沈降させた。
上澄みをデカンテーションにより取り除いた後、新たに水500mLを加え、攪拌、静置、デカンテーションにより上澄み液を取り除いた。この精製操作を3回繰り返した。
沈降した固形物を40℃の乾燥機中で乾燥し、水分を除去して銀微粒子を得た。銀微粒子は電子顕微鏡による観察から一次粒子の平均粒子径が60nmであった(図1)。
熱分析により有機物成分であるブチルアミンが銀に対して1.2質量%含まれていることが分かった(図2)。低温度有機物成分飛散定数が68(=73.14×78×0.012)であった。
得られた銀微粒子の一部を大気中、150℃で30分間加熱し、電子顕微鏡で観察したところ、低温加熱にもかかわらず銀微粒子同士が焼結構造をとっているのが確認できた(図3)。
Example 1
In a 500 mL beaker, 40 g of silver nitrate, 37.9 g of butylamine (molecular weight: 73.14, boiling point: 78 ° C.) and 200 mL of methanol were added and stirred for 1 hour to prepare solution A. Separately, 62.2 g of ascorbic acid was taken in a 2 L beaker, 400 mL of water was added and dissolved by stirring, and then 200 mL of methanol was added to prepare solution B.
B liquid was stirred well and A liquid was dripped at B liquid over 1 hour and 20 minutes. After completion of the dropwise addition, stirring was continued for 3 hours and 30 minutes. After completion of stirring, the mixture was allowed to stand for 30 minutes to precipitate the solid.
After removing the supernatant by decantation, 500 mL of water was newly added, and the supernatant was removed by stirring, standing, and decantation. This purification operation was repeated three times.
The precipitated solid was dried in a dryer at 40 ° C. to remove moisture and obtain silver fine particles. Silver fine particles had an average primary particle diameter of 60 nm as observed with an electron microscope (FIG. 1).
Thermal analysis revealed that 1.2% by mass of butylamine, an organic component, was contained with respect to silver (FIG. 2). The low temperature organic component scattering constant was 68 (= 73.14 × 78 × 0.012).
Part of the obtained silver fine particles was heated in the atmosphere at 150 ° C. for 30 minutes and observed with an electron microscope, and it was confirmed that the silver fine particles had a sintered structure despite the low temperature heating ( FIG. 3).

実施例2
1Lのビーカーに硝酸銀160g、ブチルアミン(分子量:73.14、沸点:78℃)151.2g、メタノール800mLを加え、2時間攪拌しA液を調製した。別に、10Lのビーカーにエリソルビン酸248.8gを取り、水2000mLを加え攪拌して溶解し、続いてメタノール800mLを加えB液を調製した。
B液をよく攪拌しA液をB液に5時間かけて滴下した。滴下終了後、3時間30分攪拌を継続した。攪拌終了後、30分間静置し固形物を沈降させた。
上澄みをデカンテーションにより取り除いた後、新たに水1000mLを加え、攪拌、静置、デカンテーションにより上澄み液を取り除いた。この精製操作を3回繰り返した。
沈降した固形物にエチレングリコール1gを溶かした水200mLを加えてスラリーに調製した後、40℃の乾燥機中で乾燥し、銀微粒子を得た。銀微粒子は電子顕微鏡による観察から、一次粒子の平均粒子径は80nmであった(図4)。
熱分析の結果、有機物成分が銀微粒子に対して1.5質量%含まれていることが分かった。エチレングリコールを混合する前の銀微粒子の熱分析の結果よりブチルアミンを0.8%含んでいることが算出されたので、エチレングリコールは残りの0.7%含有されていると分かった。各々の低温度有機物成分飛散定数を加算すると130であった。
得られた銀微粒子の一部を大気中、200℃で30分間加熱し、電子顕微鏡で観察したところ、低温加熱にもかかわらず銀微粒子同士が焼結構造をとっているのが確認できた(図5)。
Example 2
To a 1 L beaker, 160 g of silver nitrate, 151.2 g of butylamine (molecular weight: 73.14, boiling point: 78 ° C.) and 800 mL of methanol were added and stirred for 2 hours to prepare solution A. Separately, 248.8 g of erythorbic acid was taken in a 10 L beaker, 2000 mL of water was added and dissolved by stirring, and then 800 mL of methanol was added to prepare solution B.
B liquid was stirred well and A liquid was dripped at B liquid over 5 hours. After completion of the dropwise addition, stirring was continued for 3 hours and 30 minutes. After completion of stirring, the mixture was allowed to stand for 30 minutes to precipitate the solid.
After removing the supernatant by decantation, 1000 mL of water was newly added, and the supernatant was removed by stirring, standing, and decantation. This purification operation was repeated three times.
200 mL of water in which 1 g of ethylene glycol was dissolved was added to the settled solid to prepare a slurry, and then dried in a dryer at 40 ° C. to obtain silver fine particles. Silver fine particles were observed with an electron microscope, and the average primary particle diameter was 80 nm (FIG. 4).
As a result of thermal analysis, it was found that the organic component was contained in an amount of 1.5% by mass with respect to the silver fine particles. From the result of thermal analysis of the silver fine particles before mixing with ethylene glycol, it was calculated that 0.8% of butylamine was contained. Therefore, it was found that the remaining 0.7% of ethylene glycol was contained. The total of the low-temperature organic component scattering constants was 130.
When some of the obtained silver fine particles were heated in the atmosphere at 200 ° C. for 30 minutes and observed with an electron microscope, it was confirmed that the silver fine particles had a sintered structure despite low-temperature heating ( FIG. 5).

実施例3
1Lのビーカーに硝酸銀160g、ブチルアミン151.2g、メタノール800mLを加え、2時間攪拌しA液を調製した。別に10Lのビーカーにアスコルビン酸248.8gを取り、水1600mLを加え攪拌して溶解し、続いてメタノール800mLを加えB液を調製した。
B液をよく攪拌しA液をB液に5時間かけて滴下した。滴下終了後、3時間30分攪拌を継続した。攪拌終了後、30分間静置し固形物を沈降させた。
上澄みをデカンテーションにより取り除いた後、新たに水2000mLを加え、攪拌、静置、デカンテーションにより上澄み液を取り除いた。この精製操作を3回繰り返した。
沈降した固形物を乾燥機中で乾燥し、水分を除去して銀微粒子を得た。銀微粒子は電子顕微鏡による観察から、一次粒子の平均粒子径は80nmであった(図6)。
熱分析により有機物成分であるブチルアミンが銀に対して2.3質量%含まれていることが分かった。低温度有機物成分飛散定数が114であった。
得られた銀微粒子の一部を大気中、150℃で30分間加熱し、電子顕微鏡で観察したところ、低温加熱にもかかわらず銀微粒子同士が焼結構造をとっているのが確認できた(図7)。
Example 3
To a 1 L beaker, 160 g of silver nitrate, 151.2 g of butylamine and 800 mL of methanol were added and stirred for 2 hours to prepare solution A. Separately, 248.8 g of ascorbic acid was taken in a 10 L beaker, 1600 mL of water was added and dissolved by stirring, and then 800 mL of methanol was added to prepare a solution B.
B liquid was stirred well and A liquid was dripped at B liquid over 5 hours. After completion of the dropwise addition, stirring was continued for 3 hours and 30 minutes. After completion of stirring, the mixture was allowed to stand for 30 minutes to precipitate the solid.
After removing the supernatant by decantation, 2000 mL of water was newly added, and the supernatant was removed by stirring, standing, and decantation. This purification operation was repeated three times.
The precipitated solid was dried in a drier to remove moisture and obtain silver fine particles. Silver fine particles were observed with an electron microscope, and the average primary particle diameter was 80 nm (FIG. 6).
Thermal analysis revealed that 2.3% by mass of butylamine, which is an organic component, was contained in silver. The low temperature organic component scattering constant was 114.
Part of the obtained silver fine particles was heated in the atmosphere at 150 ° C. for 30 minutes and observed with an electron microscope, and it was confirmed that the silver fine particles had a sintered structure despite the low temperature heating ( FIG. 7).

比較例1
500mLのビーカーに硝酸銀40g、ブチルアミン(分子量:73.14、沸点:78℃)37.9g、メタノール200mLを加え、1時間攪拌しA液を調製した。
別に、2Lのビーカーにアスコルビン酸62.2gを取り、水400mLを加え攪拌して溶解し、続いてメタノール200mLを加えB液を調製した。
B液をよく攪拌しA液をB液に1時間20分かけて滴下した。滴下終了後、3時間30分攪拌を継続した。攪拌終了後、30分間静置し固形物を沈降させた。
上澄みをデカンテーションにより取り除いた後、新たにメタノール500mLを加え、攪拌、静置、デカンテーションにより上澄み液を取り除いた。この精製操作を3回繰り返した。
沈降した固形物を乾燥機中で20時間乾燥し、水分を除去して銀微粒子を得た。銀微粒子は電子顕微鏡による観察から平均粒子径60nmの粒子径であった。
熱分析により有機物成分であるブチルアミンが銀に対して0.6質量%含まれていることが分かった。低温度有機物成分飛散定数が34であった。
室温下で放置したところ、1ヵ月後には粒子同士が焼結凝集し、導電性ペーストなどに用いることが出来ない状態であった。
Comparative Example 1
In a 500 mL beaker, 40 g of silver nitrate, 37.9 g of butylamine (molecular weight: 73.14, boiling point: 78 ° C.) and 200 mL of methanol were added and stirred for 1 hour to prepare solution A.
Separately, 62.2 g of ascorbic acid was taken in a 2 L beaker, 400 mL of water was added and dissolved by stirring, and then 200 mL of methanol was added to prepare solution B.
B liquid was stirred well and A liquid was dripped at B liquid over 1 hour and 20 minutes. After completion of the dropwise addition, stirring was continued for 3 hours and 30 minutes. After completion of stirring, the mixture was allowed to stand for 30 minutes to precipitate the solid.
After removing the supernatant by decantation, 500 mL of methanol was newly added, and the supernatant was removed by stirring, standing, and decantation. This purification operation was repeated three times.
The precipitated solid was dried in a dryer for 20 hours to remove moisture and obtain silver fine particles. The silver fine particles had a particle diameter of 60 nm in average particle diameter as observed with an electron microscope.
Thermal analysis revealed that 0.6% by mass of butylamine, which is an organic component, was contained with respect to silver. The low temperature organic component scattering constant was 34.
When allowed to stand at room temperature, the particles were sintered and aggregated after one month and could not be used as a conductive paste.

比較例2
特開2004−43892公報の第3実施形態を実施して、銀微粒子を得た。この銀微粒子の平均粒子径は70nmであり、表面処理剤としてポリビニルピロリドンが銀に対して3.5質量%含まれていることが分かった。用いたポリビニルピロリドンの平均分子量は35000であり、熱分析より明らかに減量を始める点が200℃であったので分解温度を200℃とした場合、低温度有機物成分飛散定数が1225であった。
得られた銀微粒子の一部を大気中、200℃で1時間加熱し、電子顕微鏡で観察したところ、銀微粒子同士の焼結は確認できなかった。よって、低温焼成が可能な導電性ペーストおよび導電性接着剤、接合材の原料に不向きな銀微粒子であることが分かった。
Comparative Example 2
The third embodiment of Japanese Patent Application Laid-Open No. 2004-43892 was implemented to obtain silver fine particles. The average particle diameter of the silver fine particles was 70 nm, and it was found that polyvinyl pyrrolidone as a surface treatment agent was contained in an amount of 3.5% by mass with respect to silver. The average molecular weight of the polyvinylpyrrolidone used was 35000, and the point at which weight loss clearly started from thermal analysis was 200 ° C. Therefore, when the decomposition temperature was 200 ° C., the low temperature organic component scattering constant was 1225.
When a part of the obtained silver fine particles was heated in the atmosphere at 200 ° C. for 1 hour and observed with an electron microscope, sintering of the silver fine particles could not be confirmed. Therefore, it turned out that it is a silver fine particle unsuitable for the raw material of the electrically conductive paste which can be baked at low temperature, an electrically conductive adhesive, and a joining material.

比較例3
500mLのビーカーに硝酸銀20gと水200mLを加え、続いてモノエタノールアミン15.8g(分子量:61.08、沸点:170℃)を少しずつ加え、硝酸銀のアミン錯体水溶液であるA液を調製した。別に、1Lのビーカーにアスコルビン酸31.1gと水300mLに溶かしB液を調製した。
B液をよく攪拌しA液をB液に1時間かけて滴下した。滴下終了後、3時間30分攪拌を継続した。攪拌終了後、30分間静置し固形物を沈降させた。上澄みをデカンテーションにより取り除いた後、新たに水300mLを加え、攪拌、静置、デカンテーションにより上澄み液を取り除いた。この精製操作を3回繰り返した。沈降した固形物を乾燥機中で乾燥し、水分を除去して銀微粒子を得た。
銀微粒子は電子顕微鏡による観察から、一次粒子の平均粒子径が25μmであった。
熱分析により有機物成分であるモノエタノールアミンが銀に対して2.5質量%含まれていることが分かった。低温度有機物成分飛散定数が260であった。
得られた銀微粒子の一部を大気中、200℃で1時間加熱し、電子顕微鏡で観察したところ、銀微粒子同士の焼結は確認できなかった。
Comparative Example 3
Into a 500 mL beaker, 20 g of silver nitrate and 200 mL of water were added, and then 15.8 g of monoethanolamine (molecular weight: 61.08, boiling point: 170 ° C.) was added little by little to prepare a solution A which is an aqueous silver nitrate amine complex solution. Separately, solution B was prepared by dissolving 31.1 g of ascorbic acid and 300 mL of water in a 1 L beaker.
B liquid was stirred well and A liquid was dripped at B liquid over 1 hour. After completion of the dropwise addition, stirring was continued for 3 hours and 30 minutes. After completion of stirring, the mixture was allowed to stand for 30 minutes to precipitate the solid. After removing the supernatant by decantation, 300 mL of water was newly added, and the supernatant was removed by stirring, standing, and decantation. This purification operation was repeated three times. The precipitated solid was dried in a drier to remove moisture and obtain silver fine particles.
The silver fine particles had an average primary particle diameter of 25 μm as observed with an electron microscope.
Thermal analysis revealed that monoethanolamine, which is an organic component, was contained at 2.5% by mass with respect to silver. The low temperature organic component scattering constant was 260.
When a part of the obtained silver fine particles was heated in the atmosphere at 200 ° C. for 1 hour and observed with an electron microscope, sintering of the silver fine particles could not be confirmed.

比較例4
500mLのビーカーに硝酸銀20gとメタノール200mLを加え、続いてブチルアミン18.9gを加え、硝酸銀のアミン錯体溶液であるA液を調製した。1Lのビーカーにアスコルビン酸31.1gとメタノール300mLを混合しB液を調製した。
B液をよく攪拌しA液をB液に1時間かけて滴下した。滴下終了後、3時間30分攪拌を継続した。攪拌終了後、30分間静置し固形物を沈降させた。上澄みをデカンテーションにより取り除いた後、新たに水300mLを加え、攪拌、静置、デカンテーションにより上澄み液を取り除いた。この精製操作を3回繰り返した。沈降した固形物を乾燥機中で乾燥し、水分を除去して銀微粒子を得た。
熱分析より有機物成分であるブチルアミンが銀に対して1.6質量%含まれていることが分かった。低温度有機物成分飛散定数が91であった。
銀微粒子は電子顕微鏡による観察から平均一次粒子径は30nmであったが、300〜500のnmの粉砕困難な凝集粒子であった(図8)。
Comparative Example 4
Into a 500 mL beaker, 20 g of silver nitrate and 200 mL of methanol were added, and then 18.9 g of butylamine was added to prepare a solution A that is an amine complex solution of silver nitrate. Liquid B was prepared by mixing 31.1 g of ascorbic acid and 300 mL of methanol in a 1 L beaker.
B liquid was stirred well and A liquid was dripped at B liquid over 1 hour. After completion of the dropwise addition, stirring was continued for 3 hours and 30 minutes. After completion of stirring, the mixture was allowed to stand for 30 minutes to precipitate the solid. After removing the supernatant by decantation, 300 mL of water was newly added, and the supernatant was removed by stirring, standing, and decantation. This purification operation was repeated three times. The precipitated solid was dried in a drier to remove moisture and obtain silver fine particles.
It was found from thermal analysis that 1.6% by mass of butylamine, which is an organic component, was contained with respect to silver. The low temperature organic component scattering constant was 91.
The silver fine particles had an average primary particle diameter of 30 nm from observation with an electron microscope, but were aggregated particles of 300 to 500 nm that were difficult to grind (FIG. 8).

比較例5
500mLのビーカーに硝酸銀20gと水200mLを加え、続いて28%アンモニア水を少しずつ加え、硝酸銀のアミン錯体水溶液であるA液を調製した。1Lのビーカーにアスコルビン酸31.1gと水300mLに溶かしB液を調製した。
B液をよく攪拌しA液をB液に1時間かけて滴下した。滴下終了後、3時間30分攪拌を継続した。攪拌終了後、30分間静置し固形物を沈降させた。
上澄みをデカンテーションにより取り除いた後、新たに水300mLを加え、攪拌、静置、デカンテーションにより上澄み液を取り除いた。この精製操作を3回繰り返した。沈降した固形物を乾燥機中で乾燥し、水分を除去して銀微粒子を得た。
銀微粒子は電子顕微鏡による観察から、一次粒子の平均粒子径が5μmの粒子であった。
Comparative Example 5
To a 500 mL beaker, 20 g of silver nitrate and 200 mL of water were added, followed by 28% ammonia water little by little to prepare a solution A which is an aqueous silver nitrate amine complex solution. Solution B was prepared by dissolving 31.1 g of ascorbic acid and 300 mL of water in a 1 L beaker.
B liquid was stirred well and A liquid was dripped at B liquid over 1 hour. After completion of the dropwise addition, stirring was continued for 3 hours and 30 minutes. After completion of stirring, the mixture was allowed to stand for 30 minutes to precipitate the solid.
After removing the supernatant by decantation, 300 mL of water was newly added, and the supernatant was removed by stirring, standing, and decantation. This purification operation was repeated three times. The precipitated solid was dried in a drier to remove moisture and obtain silver fine particles.
The silver fine particles were particles having an average primary particle diameter of 5 μm, as observed with an electron microscope.

本発明の銀微粒子は、低温焼成が可能な導電性ペースト、導電性接着剤又は接合材等の銀微粒子原料として好適であり、さらに簡便に製造することが可能であるため産業上極めて有用である。   The silver fine particles of the present invention are suitable as a raw material for silver fine particles such as conductive pastes, conductive adhesives or bonding materials that can be fired at a low temperature, and are extremely useful industrially because they can be easily manufactured. .

実施例1で得られた銀微粒子について、倍率50,000倍で撮影したSEM写真SEM photograph taken at a magnification of 50,000 times for the silver fine particles obtained in Example 1 実施例1で得られた銀微粒子について、熱重量分析を行った結果Results of thermogravimetric analysis on the silver fine particles obtained in Example 1 実施例1で得られた銀微粒子を加熱して得られた銀粉について、倍率50,000倍で撮影したSEM写真SEM photograph taken at a magnification of 50,000 times for the silver powder obtained by heating the silver fine particles obtained in Example 1. 実施例2で得られた銀微粒子について、倍率50,000倍で撮影したSEM写真SEM photograph taken at a magnification of 50,000 times for the silver fine particles obtained in Example 2 実施例2で得られた銀微粒子を加熱して得られた銀粉について、倍率50,000倍で撮影したSEM写真SEM photograph taken at a magnification of 50,000 times for the silver powder obtained by heating the silver fine particles obtained in Example 2 実施例3で得られた銀微粒子について、倍率50,000倍で撮影したSEM写真SEM photograph taken at a magnification of 50,000 times for the silver fine particles obtained in Example 3 実施例3で得られた銀微粒子を加熱して得られた銀粉について、倍率50,000倍で撮影したSEM写真SEM photograph taken at a magnification of 50,000 times for the silver powder obtained by heating the silver fine particles obtained in Example 3 比較例4で得られた銀微粒子について、倍率50,000倍で撮影したSEM写真SEM photograph taken at a magnification of 50,000 times for the silver fine particles obtained in Comparative Example 4.

Claims (5)

平均粒子径が20〜100nmであり、含有または付着している有機物の低温度有機物成分飛散定数(低温度有機物成分飛散定数=有機物成分の分子量×有機物成分の沸点または分解温度×銀微粒子に対する含有比率)が56以上180以下であり、前記含有または付着している有機物がプロピルアミン、ブチルアミン、モノエタノールアミンから選ばれる少なくとも1種であることを特徴とする銀微粒子 The average particle size is 20 to 100 nm, and the low-temperature organic component scattering constant of the organic matter contained or adhered (low-temperature organic component scattering constant = molecular weight of organic component × boiling point or decomposition temperature of organic component × content ratio to silver fine particles ) is Ri der 56 to 180, the content or deposited to have organic substances propylamine, butylamine, silver particles, characterized in that at least one selected from monoethanolamine. 平均粒子径が20〜100nmであり、含有または付着している有機物の低温度有機物成分飛散定数(低温度有機物成分飛散定数=有機物成分の分子量×有機物成分の沸点または分解温度×銀微粒子に対する含有比率)が56以上180以下であり、前記含有または付着する有機物として、沸点200℃以下のアルコールを1種以上含むことを特徴とする銀微粒子。The average particle size is 20 to 100 nm, and the low-temperature organic component scattering constant of the organic matter contained or adhered (low-temperature organic component scattering constant = molecular weight of organic component × boiling point or decomposition temperature of organic component × content ratio to silver fine particles ) Is 56 or more and 180 or less, and contains at least one alcohol having a boiling point of 200 ° C. or less as the organic substance to be contained or adhered. 沸点200℃以下のアルコールがエチレングリコールである請求項記載の銀微粒子 The silver fine particles according to claim 2 , wherein the alcohol having a boiling point of 200 ° C or lower is ethylene glycol . 硝酸銀と、水溶性あるいは水可溶性であって沸点が200℃以下のアミンの1種類以上とを用いて調製した硝酸銀のアミン錯体のメタノール溶液を、アスコルビン酸またはエリソルビン酸を溶解させた水−メタノール混合溶媒中に添加して還元析出させて平均粒子径20〜100nmの銀微粒子を得ることを特徴とする銀微粒子の製造方法。 A water-methanol mixture in which ascorbic acid or erythorbic acid is dissolved in a methanol solution of a silver nitrate amine complex prepared using silver nitrate and one or more amines having a water-soluble or water-soluble boiling point of 200 ° C. or less A method for producing silver fine particles, characterized in that silver fine particles having an average particle size of 20 to 100 nm are obtained by addition in a solvent and reduction precipitation. 硝酸銀と、水溶性あるいは水可溶性であって沸点が200℃以下のアミンの1種類以上とを用いて調製した硝酸銀のアミン錯体のメタノール溶液を、アスコルビン酸またはエリソルビン酸を溶解させた水−メタノール混合溶媒中に添加して還元析出させて平均粒子径20〜100nmの銀微粒子を得、さらに含有または付着有機物を低温度有機物成分飛散定数((低温度有機物成分飛散定数=有機物成分の分子量×有機物成分の沸点または分解温度×銀微粒子に対する含有比率)が56以上180以下に調整することを特徴とする銀微粒子の製造方法。

A water-methanol mixture in which ascorbic acid or erythorbic acid is dissolved in a methanol solution of a silver nitrate amine complex prepared using silver nitrate and one or more amines having a water-soluble or water-soluble boiling point of 200 ° C. or less Silver fine particles having an average particle diameter of 20 to 100 nm are obtained by adding to a solvent and reducing precipitation, and further containing or adhering organic matter is a low temperature organic component scattering constant ((low temperature organic component scattering constant = molecular weight of organic component × organic component) The boiling point or decomposition temperature x content ratio of silver fine particles) is adjusted to 56 or more and 180 or less.

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