JP5005362B2 - Silver particle dispersion and method for producing the same - Google Patents
Silver particle dispersion and method for producing the same Download PDFInfo
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本発明は、銀粒子分散液およびその製造方法に関し、特に、銀微粒子が液状有機媒体中に分散した銀粒子分散液およびその製造方法に関する。 The present invention relates to a silver particle dispersion and a method for producing the same, and more particularly to a silver particle dispersion in which silver fine particles are dispersed in a liquid organic medium and a method for producing the same.
従来、電子部品などの電極や回路を形成する方法として、銀粉などの金属粉末をガラスフリットや無機酸化物とともに有機ビヒクル中に分散させたペーストを印刷やディッピングなどによって基板上に所定のパターンに形成した後、５００℃以上の温度で加熱することによって、有機成分を除去し、銀粒子などの金属粒子同士を焼結させて導体（配線）を形成する所謂厚膜ペースト法が広く用いられている。このような厚膜ペースト法によって形成された配線と基板との密着性は、焼成工程において軟化して流動したガラスフリットが基板を濡らすことによって、また、配線を形成する金属の焼結膜中にも軟化して流動したガラスフリットが浸透すること（ガラスボンド）によって確保される。また、アルミナ基板を使用する場合には、酸化銅や酸化カドミウムなどの無機酸化物がアルミナ基板と反応性酸化物を形成すること（ケミカルボンド）によって、配線と基板との密着性が確保される。 Conventionally, as a method for forming electrodes and circuits for electronic components, etc., a paste in which metal powder such as silver powder is dispersed in an organic vehicle together with glass frit or inorganic oxide is formed in a predetermined pattern on a substrate by printing or dipping. After that, a so-called thick film paste method is widely used in which the organic component is removed by heating at a temperature of 500 ° C. or higher and metal particles such as silver particles are sintered together to form a conductor (wiring). . The adhesion between the wiring formed by such a thick film paste method and the substrate is that the glass frit that has been softened and flowed in the baking process wets the substrate, and also in the sintered metal film that forms the wiring. It is ensured by the permeation of the softened and fluidized glass frit (glass bond). When an alumina substrate is used, the adhesion between the wiring and the substrate is ensured by forming an inorganic oxide such as copper oxide or cadmium oxide with a reactive oxide (chemical bond). .
また、金属粒子の粒径が数ｎｍ程度になると、比表面積が非常に大きくなって、融点が劇的に低下する。そのため、数μｍ程度の粒径の金属粒子を使用して配線を形成する場合と比べて、微細な配線の描画が可能になるだけでなく、低温で焼成することによって金属粒子同士を焼結させることもできる。特に、金属粒子の中でも銀粒子は、低抵抗で且つ高い耐候性を有し、他の貴金属と比べて安価であることから、微細な幅の配線材料として期待されている。 Further, when the particle size of the metal particles is about several nm, the specific surface area becomes very large and the melting point is drastically lowered. Therefore, compared to the case where wiring is formed using metal particles having a particle size of about several μm, not only fine wiring can be drawn, but also the metal particles are sintered by firing at a low temperature. You can also. In particular, among metal particles, silver particles are expected as a wiring material having a fine width because they have low resistance and high weather resistance and are less expensive than other noble metals.
従来の厚膜ペースト法で数μｍ程度の粒径の銀粒子を使用した場合と比べて、数ｎｍ程度の粒径の銀粒子を使用した場合には、３００℃以下の低温で焼結することができる。３００℃より高い温度で焼成することもできるが、高温で焼成する場合には、電極や回路を形成する基板の耐熱性による制約により、使用可能な基板の種類が限定されるだけでなく、数ｎｍ程度の粒径の銀粒子を使用することによる利点（低温で焼結させることができるという利点）が得られなくなる。特に、焼成温度を低くすることができる程、使用可能な基板の種類を増やすことができる。 When using silver particles with a particle size of a few nanometers compared with the case of using silver particles with a particle size of a few μm in the conventional thick film paste method, sintering should be performed at a low temperature of 300 ° C. or lower. Can do. Although it can be fired at a temperature higher than 300 ° C., in the case of firing at a high temperature, not only the types of substrates that can be used are limited by the heat resistance of the substrate on which the electrodes and circuits are formed, but also several Advantages (advantages of being able to sinter at a low temperature) by using silver particles having a particle size of about nm cannot be obtained. In particular, the types of substrates that can be used can be increased as the firing temperature can be lowered.
また、３００℃以下の低い温度で焼成する場合には、従来の厚膜ペースト法と同様にガラスフリットを添加しても、ガラスフリットが軟化・流動しないので、基板を濡らすことがなく、その結果、基板に対する金属薄膜（配線）の密着性が悪くなるという問題がある。特に、ガラス基板やポリイミドフィルムなどの樹脂基板との金属薄膜の密着性が悪くなる。 In addition, when firing at a low temperature of 300 ° C. or lower, even if glass frit is added as in the conventional thick film paste method, the glass frit does not soften or flow, so that the substrate is not wetted. There is a problem that the adhesion of the metal thin film (wiring) to the substrate is deteriorated. In particular, the adhesion of the metal thin film to a resin substrate such as a glass substrate or a polyimide film is deteriorated.
３００℃以下の比較的低温で焼結した場合の金属薄膜と基板との密着性を向上させる方法として、有機溶剤に金属微粒子が分散した金属微粒子分散液およびシランカップリング剤を含むペーストをガラス基板上に塗布して、２５０〜３００℃の温度で焼成することによってガラス基板上に金属薄膜を形成する方法（例えば、特許文献１参照）、平均粒子径０．５〜２０μｍの金属フィラーと平均粒子径１〜１００ｎｍの金属微粒子を熱硬化性樹脂中に分散させて導電性金属ペーストを形成する方法（例えば、特許文献２参照）、金属元素とこの金属元素より酸化性の高い酸化性金属元素との合金または複合体からなる金属微粒子を含む塗膜を酸化性雰囲気中で熱処理した後に還元性雰囲気で再度熱処理する方法（例えば、特許文献３参照）などが提案されている。 As a method for improving the adhesion between a metal thin film and a substrate when sintered at a relatively low temperature of 300 ° C. or lower, a paste containing a metal fine particle dispersion in which metal fine particles are dispersed in an organic solvent and a silane coupling agent is used as a glass substrate A method of forming a metal thin film on a glass substrate by coating on and baking at a temperature of 250 to 300 ° C. (see, for example, Patent Document 1), a metal filler having an average particle diameter of 0.5 to 20 μm and an average particle A method of forming a conductive metal paste by dispersing fine metal particles having a diameter of 1 to 100 nm in a thermosetting resin (see, for example, Patent Document 2), a metal element and an oxidizing metal element having a higher oxidizing property than the metal element A method of heat-treating a coating film containing metal fine particles made of an alloy or composite of the above in an oxidizing atmosphere and then heat-treating it again in a reducing atmosphere (see, for example, Patent Document 3). There has been proposed.
しかし、特許文献１の方法では、ペーストにシランカップリング剤を添加しているので、ペーストの粘度が経時変化するという問題がある。また、特許文献２の方法では、ペーストに熱硬化性樹脂を使用しているので、このペーストを使用して形成した配線上に有機物が残存して誘電体層を形成すると、この配線を真空雰囲気中に配置した場合に、有機成分の脱離による誘電体層の膨れや真空雰囲気の環境汚染などによる回路の信頼性が低下することが懸念され、また、ペーストが樹脂を含んでいるために、ペーストの粘度を低くするのが困難であるという問題がある。さらに、特許文献３の方法では、塗膜を酸化性雰囲気中で熱処理した後に還元性雰囲気中で再度熱処理する必要があるので、操作が煩雑で、生産性が悪いという問題がある。 However, the method of Patent Document 1 has a problem that the viscosity of the paste changes with time because a silane coupling agent is added to the paste. Further, in the method of Patent Document 2, since a thermosetting resin is used for the paste, when the organic substance remains on the wiring formed using this paste to form a dielectric layer, the wiring is formed in a vacuum atmosphere. When placed inside, there is concern that the reliability of the circuit may decrease due to the swelling of the dielectric layer due to the desorption of organic components and environmental pollution of the vacuum atmosphere, and because the paste contains a resin, There is a problem that it is difficult to reduce the viscosity of the paste. Furthermore, in the method of Patent Document 3, since it is necessary to heat-treat the coating film in an oxidizing atmosphere and then heat-treat it again in a reducing atmosphere, there is a problem that the operation is complicated and the productivity is poor.
したがって、本発明は、このような従来の問題点に鑑み、シランカップリング剤や熱硬化性樹脂を加えることなく、煩雑な熱処理工程を必要とせず、３００℃以下の比較的低温で焼成しても、ガラス基板や樹脂基板などの基板との密着性が良好な塗膜を形成することができる銀粒子分散液およびその製造方法を提供することを目的とする。 Therefore, in view of such conventional problems, the present invention does not require a complicated heat treatment step without adding a silane coupling agent or a thermosetting resin, and is fired at a relatively low temperature of 300 ° C. or lower. Another object of the present invention is to provide a silver particle dispersion capable of forming a coating film having good adhesion to a substrate such as a glass substrate or a resin substrate, and a method for producing the same.
本発明者らは、上記課題を解決するために鋭意研究した結果、アルコールまたはポリオール中において、沸点が３００℃以上の脂肪酸化合物と沸点が１５０〜３５０℃のアミン化合物の共存下で、８０〜２００℃の温度で銀化合物を還元処理して生成した銀粒子を液状有機媒体中に分散させることによって、シランカップリング剤や熱硬化性樹脂を加えることなく、煩雑な熱処理工程を必要とせず、３００℃以下の比較的低温で焼成しても、ガラス基板や樹脂基板などの基板との密着性が良好な塗膜を形成することができる銀粒子分散液を製造することができることを見出し、本発明を完成するに至った。 As a result of diligent research to solve the above problems, the present inventors have found that in an alcohol or polyol, a fatty acid compound having a boiling point of 300 ° C. or higher and an amine compound having a boiling point of 150 to 350 ° C. in the presence of 80 to 200 By dispersing silver particles produced by reducing a silver compound at a temperature of 0 ° C. in a liquid organic medium, a complicated heat treatment step is not required without adding a silane coupling agent or a thermosetting resin. The present invention has found that a silver particle dispersion capable of forming a coating film having good adhesion to a substrate such as a glass substrate or a resin substrate can be produced even when fired at a relatively low temperature of ℃ or less, and the present invention. It came to complete.
すなわち、本発明による銀粒子分散液の製造方法は、アルコールまたはポリオール中において、沸点が３００℃以上の脂肪酸化合物と沸点が１５０〜３５０℃のアミン化合物の共存下で、８０〜２００℃の温度で銀化合物を還元処理して生成した銀粒子を液状有機媒体中に分散させることを特徴とする。この銀粒子分散液の製造方法において、アルコールの沸点が８０〜２００℃であり、ポリオールの沸点が１５０〜３００℃であるのが好ましい。また、脂肪酸化合物およびアミン化合物の少なくとも一方が１分子中に１個以上の不飽和結合を有するのが好ましく、脂肪酸化合物およびアミン化合物が分子量１００〜１０００の化合物であるのが好ましい。さらに、還元処理の際に還元補助剤として第２級アミンおよび第３級アミンの少なくとも一方を添加するのが好ましい。 That is, the method for producing a silver particle dispersion according to the present invention comprises a fatty acid compound having a boiling point of 300 ° C. or higher and an amine compound having a boiling point of 150 to 350 ° C. in an alcohol or polyol at a temperature of 80 to 200 ° C. Silver particles produced by reducing a silver compound are dispersed in a liquid organic medium. In this method for producing a silver particle dispersion, the boiling point of the alcohol is preferably 80 to 200 ° C, and the boiling point of the polyol is preferably 150 to 300 ° C. In addition, at least one of the fatty acid compound and the amine compound preferably has one or more unsaturated bonds in one molecule, and the fatty acid compound and the amine compound are preferably compounds having a molecular weight of 100 to 1,000. Furthermore, it is preferable to add at least one of a secondary amine and a tertiary amine as a reduction aid during the reduction treatment.
また、本発明による銀粒子分散液は、沸点が３００℃以上の脂肪酸化合物と沸点が１５０〜３５０℃のアミン化合物とからなる有機保護剤を含む銀粒子が液状有機媒体中に分散していることを特徴とする。この銀粒子分散液において、脂肪酸化合物およびアミン化合物の少なくとも一方が、１分子中に１個以上の不飽和結合を有するのが好ましい。また、脂肪酸化合物およびアミン化合物が分子量１００〜１０００の化合物であるのが好ましい。また、銀粒子中の有機保護剤の割合が５〜４０質量％であるのが好ましい。さらに、銀粒子の平均粒径（ＤＴＥＭ）が２０ｎｍ以下であるのが好ましい。 Further, the silver particle dispersion according to the present invention has silver particles containing an organic protective agent composed of a fatty acid compound having a boiling point of 300 ° C. or higher and an amine compound having a boiling point of 150 to 350 ° C. dispersed in a liquid organic medium. It is characterized by. In this silver particle dispersion, at least one of the fatty acid compound and the amine compound preferably has one or more unsaturated bonds in one molecule. The fatty acid compound and the amine compound are preferably compounds having a molecular weight of 100 to 1,000. Moreover, it is preferable that the ratio of the organic protective agent in silver particles is 5-40 mass%. Furthermore, it is preferable that the average particle diameter ( DTEM ) of silver particle is 20 nm or less.
本発明によれば、シランカップリング剤や熱硬化性樹脂を加えることなく、煩雑な熱処理工程を必要とせず、３００℃以下の比較的低温で焼成しても、ガラス基板や樹脂基板などの基板との密着性が良好な塗膜を形成することができる銀粒子分散液を製造することができる。 According to the present invention, a substrate such as a glass substrate or a resin substrate can be used without adding a silane coupling agent or a thermosetting resin, without requiring a complicated heat treatment step, and firing at a relatively low temperature of 300 ° C. or lower. The silver particle dispersion liquid which can form a coating film with favorable adhesiveness can be manufactured.
本発明による銀粒子分散液の製造方法の実施の形態では、反応媒体および還元剤としての沸点が８０〜２００℃、好ましくは８５〜１５０℃のアルコールまたは沸点が１５０〜３００℃のポリオール中において、有機保護剤としての沸点が３００℃以上の脂肪酸化合物と沸点が１５０〜３５０℃のアミン化合物との共存下で、８０〜２００℃、好ましくは８５〜１５０℃の温度で銀化合物を還元処理することにより、粒成長が抑制されて、粒径が小さく揃った球状の銀粒子を得ることができる。なお、有機保護剤としてアミン化合物だけを使用すると、銀焼成膜を形成するために焼成する際に有機保護剤が脱離するため、低抵抗の銀焼成膜を得ることはできるが、焼結粒子間や基板との界面にボイドが発生して、銀焼成膜と基板との密着性が良好ではなくなる。しかし、有機保護剤として脂肪酸化合物とアミン化合物の両方を使用することにより、還元反応において粒成長が抑制されて、粒径の小さい銀粒子が生成し、焼成によって形成される銀焼成膜中のボイドが少なくなり、焼成時に有機保護剤が脱離して、低抵抗で基板との密着性が良好な銀焼成膜を得ることができる。 In an embodiment of the method for producing a silver particle dispersion according to the present invention, the reaction medium and the reducing agent have a boiling point of 80 to 200 ° C., preferably 85 to 150 ° C. in alcohol or a boiling point of 150 to 300 ° C. in polyol. The silver compound is reduced at a temperature of 80 to 200 ° C., preferably 85 to 150 ° C. in the presence of a fatty acid compound having a boiling point of 300 ° C. or more as an organic protective agent and an amine compound having a boiling point of 150 to 350 ° C. Thus, grain growth is suppressed, and spherical silver particles having a uniform particle size can be obtained. In addition, when only an amine compound is used as the organic protective agent, the organic protective agent is detached when firing to form a silver fired film, so that a low resistance silver fired film can be obtained. Voids are generated between and the interface with the substrate, and the adhesion between the fired silver film and the substrate is not good. However, by using both a fatty acid compound and an amine compound as an organic protective agent, grain growth is suppressed in the reduction reaction, and silver particles having a small particle diameter are generated. The organic protective agent is eliminated during firing, and a silver fired film having low resistance and good adhesion to the substrate can be obtained.
アルコールまたはポリオールは、銀化合物の還元剤として機能するとともに、反応系の液状有機媒体としても機能する。アルコールとしては、プロピルアルコール、イソプロピルアルコール、ｎ−ブタノール、イソブタノール、ｓｅｃ−ブチルアルコール、ｔｅｒｔ−ブチルアルコール、アリルアルコール、クロチルアルコール、シクロペンタノールなどを使用することができ、ポリオールとしては、ジエチレングリコール、トリエチレングリコール、テトラエチレングリコールなどを使用することができる。 The alcohol or polyol functions as a reducing agent for the silver compound and also functions as a liquid organic medium for the reaction system. As the alcohol, propyl alcohol, isopropyl alcohol, n-butanol, isobutanol, sec-butyl alcohol, tert-butyl alcohol, allyl alcohol, crotyl alcohol, cyclopentanol and the like can be used, and as the polyol, diethylene glycol , Triethylene glycol, tetraethylene glycol and the like can be used.
有機保護剤として使用する脂肪酸化合物およびアミン化合物の少なくとも一方は、１分子中に１個以上の不飽和結合を有するのが好ましく、また、脂肪酸化合物およびアミン化合物は、分子量１００〜１０００の化合物であるのが好ましく、分子量が１００〜４００であるのがさらに好ましい。このような不飽和結合を有するアミン化合物や脂肪酸化合物を有機保護剤として使用することによって、還元反応において銀核を一斉に発生させるとともに、析出した銀核の成長を素早く抑制する現象が起こると考えられる。分子量が１００未満では、粒子の凝集抑制効果が低く、分子量が１０００を超えると、凝集抑制効果が高くても、銀粒子分散液を塗布して焼成するときに、粒子間の焼結を阻害して配線の抵抗が高くなってしまい、導電性がなくなる場合もある。脂肪酸化合物としては、オレイン酸、リノール酸、リノレン酸、パルミトレイン酸、ミリストレイン酸などを使用することができる。また、アミン化合物としては、トリアリルアミン、オレイルアミン、ジオレイルアミン、オレイルプロピレンジアミン、オクチルアミン、ノニルアミン、デシルアミン、ウンデシルアミン、ラウリルアミン、トリデシルアミン、テトラデシルアミン、ペンタデシルアミン、セチルアミンなどを使用することができる。 At least one of the fatty acid compound and the amine compound used as the organic protective agent preferably has one or more unsaturated bonds in one molecule, and the fatty acid compound and the amine compound are compounds having a molecular weight of 100 to 1,000. It is preferable that the molecular weight is 100 to 400. The use of amine compounds and fatty acid compounds having such unsaturated bonds as organic protective agents may cause a phenomenon in which silver nuclei are generated simultaneously in the reduction reaction and the growth of precipitated silver nuclei is rapidly suppressed. It is done. When the molecular weight is less than 100, the effect of suppressing aggregation of particles is low, and when the molecular weight exceeds 1000, even when the effect of suppressing aggregation is high, sintering between particles is inhibited when the silver particle dispersion is applied and fired. As a result, the resistance of the wiring becomes high and the conductivity may be lost. As the fatty acid compound, oleic acid, linoleic acid, linolenic acid, palmitoleic acid, myristoleic acid and the like can be used. As the amine compound, triallylamine, oleylamine, dioleylamine, oleylpropylenediamine, octylamine, nonylamine, decylamine, undecylamine, laurylamine, tridecylamine, tetradecylamine, pentadecylamine, cetylamine, etc. are used. be able to.
銀化合物の還元反応は、加熱によって反応媒体および還元剤としてのアルコールまたはポリオールの蒸発と凝縮を繰り返す還流条件下で（蒸発したアルコールまたはポリオールを液相に還流させながら）行われるのが好ましい。銀化合物としては、銀塩または銀酸化物を使用することができ、硝酸銀、酸化銀、炭酸銀などを使用するのが好ましく、工業的観点から硝酸銀を使用するのが好ましい。還元反応時の液中のＡｇイオン濃度は、５０ミリモル／Ｌ以上であればよい。 The reduction reaction of the silver compound is preferably carried out under reflux conditions in which the reaction medium and the alcohol or polyol as the reducing agent are repeatedly evaporated and condensed by heating (while the evaporated alcohol or polyol is refluxed to the liquid phase). As the silver compound, a silver salt or a silver oxide can be used, and silver nitrate, silver oxide, silver carbonate or the like is preferably used, and silver nitrate is preferably used from an industrial viewpoint. The concentration of Ag ions in the solution during the reduction reaction may be 50 mmol / L or more.
また、還元処理は、還元補助剤の共存下で行うのが好ましい。この還元補助剤は、還元反応の終了近くで添加するのが好ましく、還元補助剤の添加量は、Ａｇに対するモル比を０．１〜２０にするのが好ましい。還元補助剤として、分子量１００〜１０００のアミン化合物を使用するのが好ましく、第２級アミンおよび第３級アミンの少なくとも一方を使用するのがさらに好ましく、ジエタノールアミン、トリエタノールアミンなどを使用することができる。 The reduction treatment is preferably performed in the presence of a reducing aid. This reduction aid is preferably added near the end of the reduction reaction, and the addition amount of the reduction aid is preferably 0.1 to 20 in molar ratio to Ag. As the reduction aid, it is preferable to use an amine compound having a molecular weight of 100 to 1000, more preferably at least one of a secondary amine and a tertiary amine, and use of diethanolamine, triethanolamine or the like. it can.
還元反応後の銀微粒子の懸濁液（反応直後のスラリー）は、以下のように洗浄、分散、分級などの工程を経て、銀粒子分散液とすることができる。 The silver fine particle suspension after the reduction reaction (slurry immediately after the reaction) can be made into a silver particle dispersion through processes such as washing, dispersion, and classification as described below.
反応終了後のスラリーを遠心分離器によって固液分離し、上澄みを廃棄し、沈殿物に極性の大きい液状有機媒体を加えて超音波分散機で分散させ、この操作を３回繰り返した後、さらに上記の固液分離を行い、上澄み廃棄して沈殿物を得る（洗浄工程）。次に、得られた沈殿物に非極性または極性の小さい液状有機媒体を添加した後、超音波分散機で分散させる（分散工程）。次に、得られた銀粒子を非極性または極性の小さい液状有機媒体に添加し、上記と同様の遠心分離器によって固液分離した後、上澄み液を銀粒子分散液として回収する（分級工程）。 The slurry after the reaction is solid-liquid separated by a centrifuge, the supernatant is discarded, a liquid organic medium having a large polarity is added to the precipitate and dispersed with an ultrasonic disperser, and this operation is repeated three times. The solid-liquid separation is performed, and the supernatant is discarded to obtain a precipitate (washing step). Next, after adding a nonpolar or small polar liquid organic medium to the obtained precipitate, it is dispersed with an ultrasonic disperser (dispersing step). Next, the obtained silver particles are added to a non-polar or small-polar liquid organic medium and subjected to solid-liquid separation by a centrifuge similar to the above, and then the supernatant is recovered as a silver particle dispersion (classification step) .
本明細書中において、「極性の大きい」とは、２５℃における比誘電率が１５より大きいことをいう。比誘電率が１５以下の場合、銀粒子の分散性が良過ぎるため、洗浄工程における洗浄効率が悪化する。極性の大きい液状有機媒体としては、アルコールまたはケトンを使用することができ、アルコールとしては、メタノール、エタノール、プロピルアルコール、イソプロピルアルコールなどを使用することができ、ケトンとしては、アセトン、アセチルアセトンなどを使用することができる。極性の大きい液状有機媒体として、上記の１種または２種以上の媒体を使用することができ、これらの混合物を使用してもよい。また、本明細書中において、「非極性または極性の小さい」とは、２５℃における比誘電率が１５以下、好ましく５以下であることをいう。非極性または極性の小さい液状有機媒体として、イソオクタン、ｎ−デカン、イソドデカン、イソヘキサン、ｎ−ウンデカン、ｎ−テトラデカン、ｎ−ドデカン、トリデカン、ヘキサン、ヘプタンなどの脂肪族炭化水素や、ベンゼン、トルエン、キシレン、エチルベンゼン、デカリン、テトラリンなどの芳香族炭化水素などを使用することができる。 In the present specification, “large polarity” means that the relative dielectric constant at 25 ° C. is larger than 15. When the relative dielectric constant is 15 or less, the dispersibility of the silver particles is too good, so that the cleaning efficiency in the cleaning process is deteriorated. Alcohol or ketone can be used as the highly polar liquid organic medium, methanol, ethanol, propyl alcohol, isopropyl alcohol, etc. can be used as the alcohol, and acetone, acetylacetone, etc. can be used as the ketone. can do. As the liquid organic medium having a large polarity, one or more of the above-mentioned media can be used, and a mixture thereof may be used. Further, in the present specification, “nonpolar or low polarity” means that the relative dielectric constant at 25 ° C. is 15 or less, preferably 5 or less. Non-polar or low-polar liquid organic media include aliphatic hydrocarbons such as isooctane, n-decane, isododecane, isohexane, n-undecane, n-tetradecane, n-dodecane, tridecane, hexane, heptane, benzene, toluene, Aromatic hydrocarbons such as xylene, ethylbenzene, decalin, and tetralin can be used.
このように、銀粒子を非極性または極性の小さな液状有機媒体に分散させることによって得られた銀粒子分散液から遠心分離などで粗粒子を除くと、粒径のばらつきが少ない銀粒子が単分散した分散液を得ることができ、この銀粒子分散液を基板に塗布して焼成を行なうことによって銀焼成膜を得ることができる。 In this way, when coarse particles are removed from a silver particle dispersion obtained by dispersing silver particles in a nonpolar or small polar liquid organic medium by centrifugation or the like, silver particles with little variation in particle size are monodispersed. The silver dispersion film can be obtained, and a silver fired film can be obtained by applying the silver particle dispersion liquid to a substrate and firing it.
このようにして製造された銀粒子分散液中の銀粒子は、沸点が３００℃以上の脂肪酸化合物と沸点が１５０〜３５０℃のアミン化合物とからなる有機保護剤を含み、脂肪酸化合物およびアミン化合物の少なくとも一方は、１分子中に１個以上の不飽和結合を有する。 Silver particles in the silver particle dispersion thus produced contain an organic protective agent composed of a fatty acid compound having a boiling point of 300 ° C. or higher and an amine compound having a boiling point of 150 to 350 ° C. At least one has one or more unsaturated bonds in one molecule.
透過電子顕微鏡（ＴＥＭ）観察により測定される銀粒子の平均粒径（ＤＴＥＭ）は、好ましくは２０ｎｍ以下であり、さらに好ましくは１０ｎｍ以下である。 The average particle diameter (D TEM ) of the silver particles measured by observation with a transmission electron microscope (TEM) is preferably 20 nm or less, more preferably 10 nm or less.
また、銀粒子中の有機保護剤の割合は５〜４０質量％であるのが好ましく、１０〜２０質量％であるのがさらに好ましい。５質量％より低いと、銀焼成膜を作製した際に基板との良好な密着性を得ることができず、４０質量％より高いと、銀焼成膜を作製した際に有機保護剤や液状有機媒体に由来する膜中のカーボン残渣が導通を妨げるため、低抵抗にするのが難しくなる。 Moreover, it is preferable that the ratio of the organic protective agent in silver particle is 5-40 mass%, and it is more preferable that it is 10-20 mass%. If it is lower than 5% by mass, good adhesion to the substrate cannot be obtained when a silver fired film is produced, and if it is higher than 40% by mass, an organic protective agent or liquid organic is produced when a silver fired film is produced. Since the carbon residue in the film derived from the medium prevents conduction, it is difficult to reduce the resistance.
この銀粒子を含む銀焼成膜を形成する基板として、例えば、ガラス基板、フィルム状の有機高分子基板、シリコン基板、セラミックス基板などを使用することができる。ガラス基板は、二酸化ケイ素を主成分とする基板であれば特に限定しない。フィルム状の有機高分子基板としては、厚さは特に限定しないが、ロール・ツー・ロール方式に対応できるだけの可撓性を有し、高耐熱性を有するものが好ましく、ポリエチレンテレフタレート、ポリエチレンナフタレート、ポリイミド、アラミド、ポリカーボネートなどの基板を使用することができる。シリコン基板としては、アモルファスシリコン基板、多結晶シリコン基板、単結晶シリコン基板のいずれも使用することができる。セラミックス基板としては、アルミナ基板、窒化珪素基板の他、グリーンシートも使用することができる。 As a substrate for forming the silver fired film containing silver particles, for example, a glass substrate, a film-like organic polymer substrate, a silicon substrate, a ceramic substrate, or the like can be used. The glass substrate is not particularly limited as long as it is a substrate mainly composed of silicon dioxide. The thickness of the film-like organic polymer substrate is not particularly limited, but is preferably flexible enough to be compatible with a roll-to-roll system and has high heat resistance, such as polyethylene terephthalate and polyethylene naphthalate. Substrates such as polyimide, aramid, and polycarbonate can be used. As the silicon substrate, any of an amorphous silicon substrate, a polycrystalline silicon substrate, and a single crystal silicon substrate can be used. As the ceramic substrate, an alumina substrate and a silicon nitride substrate, as well as a green sheet can be used.
この銀焼成膜を形成するために使用する焼成装置は、酸化雰囲気中（常圧の大気雰囲気や、減圧雰囲気または不活性ガス雰囲気にわずかに酸素を導入した雰囲気も含む）、１００〜３００℃の温度で焼成することができれば、特に限定されず、例えば、熱風循環式乾燥器、ベルト式焼成炉、ＩＲ焼成炉などを使用することができる。ポリイミドフィルム基板などのフィルム基板上に配線や電極を形成する場合、生産性を考慮すると、バッチ式でなく、大量生産に適したロール・ツー・ロール方式に対応して連続焼成可能な装置を使用するのが好ましい。塗膜を形成した基板を上記の温度域で保持する焼成時間は、１０分間以上であるのが好ましい。但し、焼成時間が長過ぎると生産性が悪くなるので、一般には３００分間以下であるのが好ましい。 The baking apparatus used to form this silver fired film is in an oxidizing atmosphere (including an atmospheric atmosphere of atmospheric pressure, an atmosphere in which a slight amount of oxygen is introduced into a reduced pressure atmosphere or an inert gas atmosphere), and a temperature of 100 to 300 ° C. If it can bak at temperature, it will not specifically limit, For example, a hot-air circulation type dryer, a belt-type baking furnace, IR baking furnace etc. can be used. When forming wirings and electrodes on a film substrate such as a polyimide film substrate, considering productivity, use a device that can be continuously fired in response to a roll-to-roll method suitable for mass production, not a batch method. It is preferable to do this. The firing time for holding the substrate on which the coating film is formed in the above temperature range is preferably 10 minutes or more. However, if the firing time is too long, the productivity will deteriorate, so generally it is preferably 300 minutes or less.
また、銀焼成膜の膜厚は０．１〜３．０μｍであるのが好ましい。膜厚が０．１μｍより薄くなると、大電流を流すには不向きであり、膜厚が３．０μｍより厚くなると、銀焼成膜の厚さのばらつきが非常に大きくなる。また、銀焼成膜の体積抵抗は１０μΩ・ｃｍ以下であるのが好ましい。 Moreover, it is preferable that the film thickness of a silver baking film | membrane is 0.1-3.0 micrometers. When the film thickness is thinner than 0.1 μm, it is unsuitable for flowing a large current, and when the film thickness is thicker than 3.0 μm, the variation in the thickness of the silver fired film becomes very large. The volume resistance of the silver fired film is preferably 10 μΩ · cm or less.
また、基板上に形成された銀焼成膜の密着性の良否は、カッターナイフにより（基板を切らないように注意して）銀焼成膜上に１ｍｍ角の升目１００個を作製し、その上にセロハン粘着テープ（ＪＩＳ Ｚ１５２２の規定による幅２５ｍｍ当たりの粘着量が約８Ｎのセロハン粘着テープ）を手の指により圧着した後に剥離し、残存する升目の数ｘを数え、（ｘ個／１００個）×１００から算出される残存率（％）によって評価することができる。このようにして算出された残存率が９０％以上であれば、基板上に形成された銀導電膜が実用上十分な耐久性を備え、銀導電膜の基板とは反対側の面に接触する上層との間の十分な密着性も確保することができると考えられるが、残存率が９５％以上であるのがさらに好ましく、１００％であるのが最も好ましい。一方、残存率が９０％を下回ると、基板上に形成された銀焼成膜を長期間使用した後や加速試験を行った際に抵抗値の低下などが起こり、信頼性が低くなる場合がある。 In addition, the quality of the adhesion of the fired silver film formed on the substrate was determined by preparing 100 squares of 1 mm square on the silver fired film with a cutter knife (be careful not to cut the substrate), Cellophane adhesive tape (cellophane adhesive tape with an adhesive amount of about 8N per 25 mm width according to JIS Z1522) is peeled after being pressed with fingers, and the number of remaining squares x is counted. (X / 100) It can be evaluated by the residual ratio (%) calculated from x100. If the residual ratio calculated in this way is 90% or more, the silver conductive film formed on the substrate has sufficient practical durability and contacts the surface of the silver conductive film opposite to the substrate. Although it is considered that sufficient adhesion with the upper layer can be ensured, the residual rate is more preferably 95% or more, and most preferably 100%. On the other hand, if the residual ratio is less than 90%, the resistance value may be lowered after the silver fired film formed on the substrate is used for a long time or when an accelerated test is performed, and the reliability may be lowered. .
以下、本発明による銀粒子分散液およびその製造方法の実施例について詳細に説明する。 Examples of the silver particle dispersion and the method for producing the same according to the present invention will be described in detail below.
［実施例１］
反応媒体および還元剤としてのイソブチルアルコール（和光純薬株式会社製の特級）９６．２ｇに、有機保護剤としてのアミン化合物および脂肪酸化合物としてオクチルアミン（和光純薬株式会社製、沸点１７０℃、分子量１２９）７９．９ｇおよびオレイン酸（和光純薬株式会社製、沸点３６０℃、分子量２８２）３５．０ｇを添加するとともに、銀化合物として硝酸銀結晶（関東化学株式会社製）２０．６ｇを添加し、マグネットスターラーで攪拌して硝酸銀を溶解させた。
[Example 1]
96.2 g of isobutyl alcohol (special grade manufactured by Wako Pure Chemical Industries, Ltd.) as a reaction medium and a reducing agent, octylamine (manufactured by Wako Pure Chemical Industries, Ltd., boiling point 170 ° C., molecular weight) as an organic protective agent and fatty acid compound 129) 79.9 g and oleic acid (manufactured by Wako Pure Chemical Industries, Ltd., boiling point 360 ° C., molecular weight 282) 35.0 g were added, and silver nitrate crystals (manufactured by Kanto Chemical Co., Ltd.) 20.6 g were added as a silver compound The silver nitrate was dissolved by stirring with a magnetic stirrer.
次に、この溶液を還流器付の容器に移し、この容器をマントルヒーターに載せ、容器内に不活性ガスとして窒素ガスを４００ｍＬ／分の流量で吹込みながら、溶液をスターラーにより１００ｒｐｍの回転速度で撹拌しながら、昇温速度２℃／分で１０８℃まで加熱した。 Next, this solution is transferred to a container equipped with a reflux device, this container is placed on a mantle heater, and nitrogen gas is blown into the container as an inert gas at a flow rate of 400 mL / min. The mixture was heated to 108 ° C. at a rate of temperature rise of 2 ° C./min with stirring.
１０８℃で５時間還流を行なった後、還元補助剤として２級アミンであるジエタノールアミン（和光純薬株式会社、分子量１０６）３８．６ｇ（Ａｇに対するモル比１．０）を添加し、１時間保持して反応を終了した。 After refluxing at 108 ° C. for 5 hours, 38.6 g (molar ratio of 1.0 to Ag) of diethanolamine (Wako Pure Chemical Industries, Ltd., molecular weight 106), which is a secondary amine, was added as a reducing auxiliary agent and held for 1 hour. The reaction was terminated.
反応終了後のスラリー４０ｍＬを遠心分離器（日立工機株式会社製のＣＦ７Ｄ２）によって３０００ｒｐｍで３０分間固液分離し、上澄みを廃棄し、沈殿物に極性の大きい液状有機媒体としてメタノール４０ｍＬを加えて超音波分散機で分散させた。この操作を３回繰り返した後、さらに上記の固液分離を行い、上澄み廃棄して沈殿物を得た。次に、得られた沈殿物に非極性または極性の小さい液状有機媒体としてテトラデカン４．０ｇを添加し、超音波分散機で分散させた後、上記と同様の遠心分離器によって３０００ｒｐｍで３０分間固液分離し、上澄み液を銀粒子分散液として回収した。 After completion of the reaction, 40 mL of the slurry was solid-liquid separated at 3000 rpm for 30 minutes using a centrifuge (CF7D2 manufactured by Hitachi Koki Co., Ltd.), the supernatant was discarded, and 40 mL of methanol was added to the precipitate as a liquid organic medium having a large polarity. Dispersed with an ultrasonic disperser. After repeating this operation three times, the solid-liquid separation was further performed, and the supernatant was discarded to obtain a precipitate. Next, 4.0 g of tetradecane as a non-polar or low-polar liquid organic medium is added to the resulting precipitate and dispersed with an ultrasonic disperser, and then solidified at 3000 rpm for 30 minutes using the same centrifugal separator as described above. Liquid separation was performed, and the supernatant was recovered as a silver particle dispersion.
なお、カルボニル基、アミノ基、長鎖アルキル基、不飽和結合を確認可能な１Ｈおよび１３Ｃ−ＮＭＲ測定と、分子量を同定可能な熱分解ガスクロマトグラフ質量分析測定によって、本実施例および後述する実施例２〜４で得られた銀粒子分散液中の銀粒子が有機保護剤を含むことを確認した。 Incidentally, a carbonyl group, an amino group, a long chain alkyl group, and identifiable 1 H and 13 C-NMR measurement of unsaturated bonds, with identifiable pyrolysis gas chromatography mass spectrometry determination of molecular weight, for this example and later It confirmed that the silver particle in the silver particle dispersion liquid obtained in Examples 2-4 contains an organic protective agent.
得られた銀粒子分散液中の銀粒子の平均粒径（ＤＴＥＭ）および銀粒子中の有機保護剤の割合を求めたところ、銀粒子の平均粒径（ＤＴＥＭ）は６．１ｎｍ、銀粒子中の有機保護剤の割合は１９．８質量％であり、分散性が良好で凝集はなかった。 When the average particle diameter (D TEM ) of the silver particles in the obtained silver particle dispersion and the ratio of the organic protective agent in the silver particles were determined, the average particle diameter (D TEM ) of the silver particles was 6.1 nm, silver The ratio of the organic protective agent in the particles was 19.8% by mass, and the dispersibility was good and there was no aggregation.
なお、透過電子顕微鏡（ＴＥＭ）観察により測定される銀粒子の平均粒径（ＤＴＥＭ）は、６０万倍に拡大した画像から、重なっていない独立した粒子３００個の直径を測定し、平均値を求めることによって算出した。また、銀粒子中の有機保護剤の割合は、熱重量分析装置（マックサイエンス社製のＴＧ−ＤＴＡ２０００）によって銀粒子分散液を１０℃／分で２００℃まで昇温した後に１時間保持し、さらに１０℃／分で７００℃まで昇温し、２００℃までに減少した重量を溶媒の重量とし、２００〜７００℃までに減少した重量を有機保護剤の重量とし、７００℃で残っていた重量を銀の重量として、以下の式によって算出した。
有機保護剤の割合（質量％）
＝｛有機保護剤の重量／（有機保護剤の重量＋銀の重量）｝×１００
In addition, the average particle diameter ( DTEM ) of the silver particle measured by transmission electron microscope (TEM) observation measured the diameter of 300 independent particle | grains which have not overlapped from the image expanded 600,000 times, and average value Was calculated by calculating. Further, the ratio of the organic protective agent in the silver particles is maintained for 1 hour after the silver particle dispersion is heated to 200 ° C. at 10 ° C./min with a thermogravimetric analyzer (TG-DTA2000 manufactured by Mac Science). Further, the temperature was raised to 700 ° C. at 10 ° C./min, the weight reduced to 200 ° C. was taken as the weight of the solvent, the weight reduced to 200-700 ° C. was taken as the weight of the organic protective agent, and the weight remaining at 700 ° C. Was calculated by the following formula as the weight of silver.
Ratio of organic protective agent (% by mass)
= {Weight of organic protective agent / (weight of organic protective agent + weight of silver)} × 100
また、得られた銀粒子分散液を、エキシマレーザー（ウシオ電機株式会社製のＨ００１型エキシマレーザー）によって、洗浄したガラス基板にスピンコートで塗布して塗膜を形成し、その後、大気雰囲気中でホットプレートにより２００℃で６０分間焼成して銀焼成膜を得た。 Further, the obtained silver particle dispersion was applied by spin coating to a cleaned glass substrate with an excimer laser (H001 type excimer laser manufactured by Ushio Electric Co., Ltd.) to form a coating film. A silver fired film was obtained by firing at 200 ° C. for 60 minutes using a hot plate.
得られた銀焼成膜について、膜厚、体積抵抗および密着性を評価した。膜厚は、蛍光Ｘ線膜厚測定器（ＳＩＩ社製の蛍光Ｘ線膜厚測定器ＳＦＴ９２００）で測定した。体積抵抗は、四端子法による抵抗測定器（三菱化学製のロレスタＨＰ）で測定した表面抵抗と膜厚測定器で得られた膜厚から計算により求めた。銀焼成膜の密着性の良否は、上述したように、カッターナイフにより（基板を切らないように注意して）銀焼成膜上に１ｍｍ角の升目１００個を作製し、その上にセロハン粘着テープ（ＪＩＳ Ｚ１５２２の規定による幅２５ｍｍ当たりの粘着量が約８Ｎのセロハン粘着テープ）を手の指により圧着した後に剥離し、残存する升目の数ｘを数え、（ｘ個／１００個）×１００から算出される残存率（％）によって評価した。その結果、銀焼成膜の膜厚は０．４５μｍ、体積抵抗は３．９μΩ・ｃｍ、密着性は１００％であった。 The obtained silver fired film was evaluated for film thickness, volume resistance and adhesion. The film thickness was measured with a fluorescent X-ray film thickness measuring instrument (fluorescent X-ray film thickness measuring instrument SFT9200 manufactured by SII). The volume resistance was obtained by calculation from the surface resistance measured with a four-terminal resistance meter (Loresta HP manufactured by Mitsubishi Chemical) and the film thickness obtained with the film thickness meter. As described above, the adhesiveness of the silver fired film is determined by preparing 100 squares of 1 mm square on the silver fired film with a cutter knife (be careful not to cut the substrate), and on the cellophane adhesive tape. (Cellophane adhesive tape having an adhesive amount of about 8N per 25 mm width according to JIS Z1522) is peeled after being pressed with fingers of the hand, and the number of remaining squares x is counted, (x pieces / 100 pieces) × 100 Evaluation was based on the calculated residual rate (%). As a result, the film thickness of the fired silver film was 0.45 μm, the volume resistance was 3.9 μΩ · cm, and the adhesion was 100%.
［実施例２］
アミン化合物としてラウリルアミン（和光純薬株式会社製、沸点２４７℃、分子量１９５）１２０．８ｇを使用した以外は、実施例１と同様の方法によって銀粒子分散液および銀焼成膜を得た。得られた銀粒子の平均粒径（ＤＴＥＭ）および銀粒子中の有機保護剤の割合を実施例１と同様の方法によって求めるとともに、銀焼成膜の膜厚、体積抵抗および密着性を実施例１と同様の方法によって評価した。その結果、平均粒径（ＤＴＥＭ）は３．９ｎｍ、銀粒子中の有機保護剤の割合は２８．４質量％であり、分散性が良好で凝集はなかった。また、得られた銀焼成膜の膜厚は０．３８μｍ、体積抵抗は５．９μΩ・ｃｍ、密着性は１００％であった。
[Example 2]
A silver particle dispersion and a silver fired film were obtained in the same manner as in Example 1 except that 120.8 g of laurylamine (manufactured by Wako Pure Chemical Industries, Ltd., boiling point 247 ° C., molecular weight 195) was used as the amine compound. The average particle diameter (D TEM ) of the obtained silver particles and the ratio of the organic protective agent in the silver particles were determined by the same method as in Example 1, and the film thickness, volume resistance and adhesion of the silver fired film were determined in Examples. Evaluation was performed in the same manner as in 1. As a result, the average particle diameter (D TEM ) was 3.9 nm, the ratio of the organic protective agent in the silver particles was 28.4% by mass, the dispersibility was good, and there was no aggregation. Moreover, the film thickness of the obtained silver fired film was 0.38 μm, the volume resistance was 5.9 μΩ · cm, and the adhesion was 100%.
［実施例３］
アミン化合物としてテトラデシルアミン（和光純薬株式会社製、沸点２９１℃、分子量２１３）１３２．０ｇを使用した以外は、実施例１と同様の方法によって銀粒子分散液および銀焼成膜を得た。得られた銀粒子の平均粒径（ＤＴＥＭ）および銀粒子中の有機保護剤の割合を実施例１と同様の方法によって求めるとともに、銀焼成膜の膜厚、体積抵抗および密着性を実施例１と同様の方法によって評価した。その結果、平均粒径（ＤＴＥＭ）は７．２ｎｍ、銀粒子中の有機保護剤の割合は２９．０質量％であり、分散性が良好で凝集はなかった。また、得られた銀焼成膜の膜厚は０．６８μｍ、体積抵抗は９．７μΩ・ｃｍ、密着性は１００％であった。
[Example 3]
A silver particle dispersion and a silver fired film were obtained in the same manner as in Example 1 except that 132.0 g of tetradecylamine (manufactured by Wako Pure Chemical Industries, Ltd., boiling point 291 ° C., molecular weight 213) was used as the amine compound. The average particle diameter (D TEM ) of the obtained silver particles and the ratio of the organic protective agent in the silver particles were determined by the same method as in Example 1, and the film thickness, volume resistance and adhesion of the silver fired film were determined in Examples. Evaluation was performed in the same manner as in 1. As a result, the average particle diameter (D TEM ) was 7.2 nm, the ratio of the organic protective agent in the silver particles was 29.0% by mass, the dispersibility was good, and there was no aggregation. The obtained fired silver film had a thickness of 0.68 μm, a volume resistance of 9.7 μΩ · cm, and an adhesiveness of 100%.
［実施例４］
アミン化合物としてオレイルアミン（和光純薬株式会社製、沸点３４８℃、分子量２６７．５）１６５．５ｇを使用した以外は、実施例１と同様の方法によって銀粒子分散液および銀焼成膜を得た。得られた銀粒子の平均粒径（ＤＴＥＭ）および銀粒子中の有機保護剤の割合を実施例１と同様の方法によって求めるとともに、銀焼成膜の膜厚、体積抵抗および密着性を実施例１と同様の方法によって評価した。その結果、平均粒径（ＤＴＥＭ）は４．１ｎｍ、銀粒子中の有機保護剤の割合は３１．１質量％であり、分散性が良好で凝集はなかった。また、得られた銀焼成膜の膜厚は０．３２μｍ、体積抵抗は９．５μΩ・ｃｍ、密着性は１００％であった。
[Example 4]
A silver particle dispersion and a silver fired film were obtained in the same manner as in Example 1 except that 165.5 g of oleylamine (manufactured by Wako Pure Chemical Industries, Ltd., boiling point 348 ° C., molecular weight 267.5) was used as the amine compound. The average particle diameter (D TEM ) of the obtained silver particles and the ratio of the organic protective agent in the silver particles were determined by the same method as in Example 1, and the film thickness, volume resistance and adhesion of the silver fired film were determined in Examples. Evaluation was performed in the same manner as in 1. As a result, the average particle diameter (D TEM ) was 4.1 nm, the ratio of the organic protective agent in the silver particles was 31.1% by mass, the dispersibility was good, and there was no aggregation. Moreover, the film thickness of the obtained silver fired film was 0.32 μm, the volume resistance was 9.5 μΩ · cm, and the adhesion was 100%.
［比較例１］
有機保護膜として、脂肪酸化合物を使用せず、アミン化合物としてオレイルアミン１６５．５ｇを使用した以外は、実施例１と同様の方法によって銀粒子分散液および銀焼成膜を得た。得られた銀粒子の平均粒径（ＤＴＥＭ）および銀粒子中の有機保護剤の割合を実施例１と同様の方法によって求めるとともに、銀焼成膜の膜厚、体積抵抗および密着性を実施例１と同様の方法によって評価した。その結果、平均粒径（ＤＴＥＭ）は８．９ｎｍ、銀粒子中の有機保護剤の割合は３．６質量％であり、分散性が良好で凝集はなかった。また、得られた銀焼成膜の膜厚は０．４５μｍ、体積抵抗は１．９μΩ・ｃｍ、密着性は３％であった。
[Comparative Example 1]
A silver particle dispersion and a silver fired film were obtained by the same method as in Example 1 except that the fatty acid compound was not used as the organic protective film and 165.5 g of oleylamine was used as the amine compound. The average particle diameter (D TEM ) of the obtained silver particles and the ratio of the organic protective agent in the silver particles were determined by the same method as in Example 1, and the film thickness, volume resistance and adhesion of the silver fired film were determined in Examples. Evaluation was performed in the same manner as in 1. As a result, the average particle diameter (D TEM ) was 8.9 nm, the ratio of the organic protective agent in the silver particles was 3.6% by mass, the dispersibility was good, and there was no aggregation. The obtained fired silver film had a thickness of 0.45 μm, a volume resistance of 1.9 μΩ · cm, and an adhesion of 3%.
［比較例２］
アミン化合物としてヘキシルアミン（和光純薬株式会社製、沸点１２８℃、分子量１０１．２）６２．６ｇを使用した以外は、実施例１と同様の方法によって銀粒子分散液および銀焼成膜を得た。得られた銀粒子の平均粒径（ＤＴＥＭ）および銀粒子中の有機保護剤の割合を実施例１と同様の方法によって求めるとともに、銀焼成膜の膜厚、体積抵抗および密着性を実施例１と同様の方法によって評価した。その結果、平均粒径（ＤＴＥＭ）は３．７ｎｍ、銀粒子中の有機保護剤の割合は１８．９質量％であり、分散性が良好で凝集はなかった。また、得られた銀焼成膜の膜厚は０．３６μｍ、体積抵抗は４．１μΩ・ｃｍ、密着性は５％であった。
[Comparative Example 2]
A silver particle dispersion and a silver fired film were obtained by the same method as in Example 1 except that 62.6 g of hexylamine (manufactured by Wako Pure Chemical Industries, Ltd., boiling point 128 ° C., molecular weight 101.2) was used as the amine compound. . The average particle diameter (D TEM ) of the obtained silver particles and the ratio of the organic protective agent in the silver particles were determined by the same method as in Example 1, and the film thickness, volume resistance and adhesion of the silver fired film were determined in Examples. Evaluation was performed in the same manner as in 1. As a result, the average particle diameter (D TEM ) was 3.7 nm, the ratio of the organic protective agent in the silver particles was 18.9% by mass, the dispersibility was good, and there was no aggregation. Moreover, the film thickness of the obtained silver fired film was 0.36 μm, the volume resistance was 4.1 μΩ · cm, and the adhesion was 5%.
［比較例３］
有機保護剤として、脂肪酸化合物を使用せず、アミン化合物としてラウリルアミン１２０．８ｇを使用した以外は、実施例１と同様の方法によって銀粒子分散液を得た。その結果、得られた銀粒子は凝集し、分散した銀粒子が得られなかった。
[Comparative Example 3]
A silver particle dispersion was obtained in the same manner as in Example 1 except that no fatty acid compound was used as the organic protective agent and 120.8 g of laurylamine was used as the amine compound. As a result, the obtained silver particles were aggregated, and dispersed silver particles were not obtained.
このように、実施例１〜４で得られた銀粒子分散液を使用すれば、シランカップリング剤や熱硬化性樹脂を加えることなく、煩雑な熱処理工程を必要とせず、３００℃以下の比較的低温で焼成しても、基板との密着性が良好な銀焼成膜を形成することができるのがわかった。特に、実施例１〜４で得られた銀粒子分散液を使用すれば、膜厚が比較的薄くても基板との密着性が良好な銀焼成膜を形成することができるのがわかった。 Thus, if the silver particle dispersion liquid obtained in Examples 1 to 4 is used, a complicated heat treatment step is not required without adding a silane coupling agent or a thermosetting resin, and a comparison of 300 ° C. or lower is performed. It was found that a fired silver film having good adhesion to the substrate can be formed even when fired at a low temperature. In particular, it was found that if the silver particle dispersions obtained in Examples 1 to 4 were used, a silver fired film having good adhesion to the substrate could be formed even if the film thickness was relatively thin.
本発明による銀粒子分散液は、微細な回路パターンを形成するための配線形成用材料、例えば、インクジェット法による配線形成用材料や、真空成膜プロセスであるスパッタリングによる成膜の代替としての成膜に使用する膜形成用材料、湿式プロセスであるめっきによる成膜の代替としての成膜に使用する成膜材料などに利用することができる。また、ＬＳＩ基板の配線、ＦＰＤ（フラットパネルディスプレイ）の電極や配線、微細なトレンチ、ビアホール、コンタクトホールの埋め込みなどの配線形成材料としても利用することができる。さらに、車の塗装などの色材としても利用することができ、医療、診断、バイオテクノロジーなどの分野において生化学物質などを吸着させるキャリアにも利用することができる。 The silver particle dispersion according to the present invention is a wiring forming material for forming a fine circuit pattern, for example, a wiring forming material by an ink jet method, or a film forming as an alternative to a film forming by sputtering which is a vacuum film forming process. It can be used as a film forming material used for the film formation, a film formation material used for film formation as an alternative to film formation by plating, which is a wet process. Further, it can also be used as a wiring forming material for LSI substrate wiring, FPD (flat panel display) electrodes and wiring, fine trenches, via holes, contact hole filling, and the like. Furthermore, it can also be used as a coloring material for car paints, and can also be used as a carrier for adsorbing biochemical substances and the like in fields such as medical treatment, diagnosis, and biotechnology.
また、本発明による銀粒子分散液は、低温焼成が可能であるため、フレキシブルなフィルム上への電極形成材料として利用することができ、エレクトロニクス実装においては、接合材として利用することもできる。また、導電性皮膜として電磁波シールド膜や、透明導電膜などの分野における光学特性を利用した赤外線反射シールドなどにも利用することができる。さらに、ガラス基板上に印刷して焼成し、自動車ウインドウの防曇用熱線などにも利用することができる。 In addition, since the silver particle dispersion according to the present invention can be fired at a low temperature, it can be used as an electrode forming material on a flexible film, and can also be used as a bonding material in electronic packaging. Moreover, it can utilize also for the infrared rays reflective shield etc. which utilized the optical characteristic in field | areas, such as an electromagnetic wave shielding film and a transparent conductive film, as an electroconductive film. Furthermore, it can be printed on a glass substrate and baked, and can also be used for antifogging heat rays for automobile windows.
また、本発明による銀粒子分散液は、スピンコート、ディッピング、ブレードコートなど各種の塗布方法にも適用することができ、スクリーン印刷などにも適用することができる。
Further, the silver particle dispersion according to the present invention can be applied to various coating methods such as spin coating, dipping, and blade coating, and can also be applied to screen printing and the like.
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