JP2012243655A - Copper particulate for paste for firing and method for forming fired copper film - Google Patents
Copper particulate for paste for firing and method for forming fired copper film Download PDFInfo
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本発明は、銅微粒子を分散した焼成ペーストおよびそれを利用した配線パターン形成の分野に関するものである。詳しくは、銅微粒子を分散したペーストを用いて、スクリーン印刷で配線パターンを基板上に塗布し、その後、３００℃以下の焼成温度で導電性焼成膜を形成する低温焼成ペースト用銅微粒子、銅微粒子分散ペーストおよびそれを利用した配線パターン形成方法に関するものである。 The present invention relates to the field of fired paste in which copper fine particles are dispersed and the formation of a wiring pattern using the same. Specifically, using a paste in which copper fine particles are dispersed, a wiring pattern is applied on a substrate by screen printing, and then a conductive fired film is formed at a firing temperature of 300 ° C. or lower. The present invention relates to a dispersion paste and a wiring pattern forming method using the same.
電子機器関連分野では、常に生産性向上と低コスト化が要求されている。そのなかで、樹脂バインダーを用いたポリマー型導電ペーストは印刷するだけで導電性を付与できるため、使用量を伸ばしている。現在、その用途には銀微粒子が優れた導電性と環境信頼性から、最も多く使用されている。しかし、銀微粒子はファインパターン回路では、エレクトロマイグレーションの問題がある。一方、銅微粒子はエレクトロマイグレーション問題も少なく、銀より安価であるが、ポリマー型導電ペーストでは銀微粒子分散ペーストより導電性や信頼性で劣っていた。 In the field of electronic equipment, productivity improvement and cost reduction are always required. Among them, the polymer-type conductive paste using a resin binder can be imparted with conductivity only by printing, and therefore the amount of use is increased. Currently, silver fine particles are most frequently used for such applications because of their excellent conductivity and environmental reliability. However, silver fine particles have a problem of electromigration in a fine pattern circuit. On the other hand, copper fine particles have less electromigration problems and are cheaper than silver. However, polymer type conductive pastes are inferior in conductivity and reliability to silver fine particle dispersed pastes.
近年、粒子径が１００ｎｍ以下の銅微粒子の製造技術や低温焼成膜形成方法が開発され、焼成温度３００℃以下でも低抵抗導電膜が形成できるようになった（例えば、特許文献１〜２）。特許文献１においては、平均粒子径１〜１００ｎｍの銅微粒子分散塗膜を３００℃以下の温度で、還元性気体存在下にてプラズマ処理する方法が記載されている。特許文献２においては、平均粒子径１〜１００ｎｍの銅微粒子分散塗膜を、１．１気圧以上の加圧条件下で水素分子を含む雰囲気にて、２００〜３００℃で加熱還元する方法が記載されている。これらの方法には、平均粒子径が１００ｎｍ以下の銅微粒子を分散したペーストが使用されるが、銅微粒子は粒子径が細かくなると酸化しやすく、粒子同士の凝集力が強くなり、緻密な導電膜形成が難しかった。さらに、平均粒子径が１００ｎｍ以下の銅微粒子は生産性が悪く、コストも高くなり、実用化の大きな障害となっている。低温焼成で安定した低抵抗導電膜が形成できる焼成ペースト用銅微粒子が望まれていた。 In recent years, a technique for producing copper fine particles having a particle diameter of 100 nm or less and a low-temperature fired film formation method have been developed, and a low-resistance conductive film can be formed even at a firing temperature of 300 ° C. or less (for example, Patent Documents 1 and 2). Patent Document 1 describes a method in which a copper fine particle-dispersed coating film having an average particle diameter of 1 to 100 nm is subjected to plasma treatment at a temperature of 300 ° C. or less in the presence of a reducing gas. Patent Document 2 describes a method in which a copper fine particle-dispersed coating film having an average particle diameter of 1 to 100 nm is heated and reduced at 200 to 300 ° C. in an atmosphere containing hydrogen molecules under a pressurized condition of 1.1 atm or more. Has been. In these methods, a paste in which copper fine particles having an average particle diameter of 100 nm or less are dispersed is used. However, copper fine particles are likely to be oxidized when the particle diameter is small, and the cohesive force between the particles becomes strong, and the conductive film is dense. Formation was difficult. Furthermore, copper fine particles having an average particle diameter of 100 nm or less are poor in productivity, increase in cost, and are a major obstacle to practical use. There has been a demand for copper fine particles for firing paste that can form a stable low-resistance conductive film by low-temperature firing.
以上に述べたように、平均粒子径１００ｎｍ以下の銅微粒子を分散した焼成ペーストは、銀微粒子分散ペーストに比べると素材が安価で、ファインパターン回路形成が可能でエレクトロマイグレーション問題も回避でき、電極やプリント配線基板の導体層への応用が検討されている。しかし、銅微粒子の粒子径が１００ｎｍ以下になると、比表面積が非常に大きくなるので、銅の酸化や粒子の凝集が激しく、緻密な焼成膜を形成するのが難しく焼成膜の導電性やペーストの貯蔵安定性にも問題を有していた。さらに、さまざまな用途に使用する汎用材料としては、より安価で使いやすい低温焼成ペースト用銅微粒子が望まれている。 As described above, the calcined paste in which copper fine particles having an average particle diameter of 100 nm or less are dispersed is less expensive than silver fine particle dispersed paste, can form a fine pattern circuit, and can avoid electromigration problems. Application to a conductor layer of a printed wiring board is being studied. However, when the particle diameter of the copper fine particles is 100 nm or less, the specific surface area becomes very large, so copper oxidation and particle aggregation are severe, making it difficult to form a dense fired film, and the conductivity of the fired film and the paste There was also a problem with storage stability. Furthermore, as a general-purpose material used for various applications, copper fine particles for low-temperature fired paste that are cheaper and easier to use are desired.
本発明者等は、さまざまな粒子径の銅微粒子を分散した塗膜で、焼成膜の焼結過程を誠意研究した結果、完成したもので、焼成温度２５０℃以下でも緻密な低抵抗銅焼成膜が形成できる焼成ペースト用銅微粒子、低温焼成ペーストを提供するものである。 The inventors of the present invention have completed the sintering process of the fired film with a coating film in which copper fine particles having various particle diameters are dispersed. As a result, the present invention has been completed. The present invention provides a copper fine particle for firing paste, a low-temperature firing paste that can be formed.
本発明は、スクリーン印刷で配線パターンを樹脂基板上に塗布し、その後２５０℃以下の焼成温度、水素含有窒素ガス雰囲気の焼成工程で導電性焼成膜を形成する銅微粒子分散焼成ペーストにおいて、その構成成分の１つである銅微粒子が、平均粒子径４０ｎｍ以下の銅微粒子が３０〜７０質量％と、該銅微粒子質量の少なくとも１００倍以上の平均粒子径２００〜８００ｎｍの銅微粒子が７０〜３０質量％であることを特徴とする、低温焼成ペースト用銅微粒子および、それを分散した低温焼成ペースト、導電性銅焼成膜の形成方法である。 The present invention relates to a copper fine particle-dispersed fired paste in which a wiring pattern is applied onto a resin substrate by screen printing, and then a conductive fired film is formed by a firing process at a firing temperature of 250 ° C. or lower and a hydrogen-containing nitrogen gas atmosphere. The copper fine particles as one of the components are 30 to 70% by mass of copper fine particles having an average particle size of 40 nm or less, and 70 to 30 masses of copper fine particles having an average particle size of 200 to 800 nm that is at least 100 times the copper fine particle mass. %, A method for forming a copper fine particle for low-temperature fired paste, a low-temperature fired paste in which the fine particles are dispersed, and a conductive copper fired film.
本発明において、平均粒子径４０ｎｍ以下の銅微粒子と平均粒子径２００〜８００ｎｍの銅微粒子が、本発明の比率範囲内でペースト中に分散し、焼成膜が形成されることが最も重要である。本発明の平均粒子径４０ｎｍ以下の銅微粒子は、ガス中蒸発法に代表される物理的気相法あるいは銅化合物を還元する液相還元法で製造したものが使用できる。好ましくは５〜４０ｎｍの銅微粒子が良い。平均粒子径が５ｎｍより細かいと凝集力が非常に強く、均一分散するのが難しい。また、平均粒子径が４０ｎｍより大きくなると本発明の比率でも緻密な低抵抗焼成膜が形成されなく、焼成温度も高くなり好ましくない。 In the present invention, it is most important that copper fine particles having an average particle diameter of 40 nm or less and copper fine particles having an average particle diameter of 200 to 800 nm are dispersed in the paste within the ratio range of the present invention to form a fired film. As the copper fine particles having an average particle diameter of 40 nm or less of the present invention, those produced by a physical gas phase method represented by a gas evaporation method or a liquid phase reduction method of reducing a copper compound can be used. Preferably, copper fine particles of 5 to 40 nm are good. When the average particle diameter is smaller than 5 nm, the cohesive force is very strong and it is difficult to uniformly disperse. On the other hand, if the average particle diameter is larger than 40 nm, a dense low-resistance fired film is not formed even in the ratio of the present invention, and the firing temperature becomes high.
フェノール樹脂やエポキシ樹脂などの樹脂基板に焼成膜を形成する場合、樹脂物性を劣化させない２２０℃以下の焼成温度が好ましく、平均粒子径４０ｎｍ以下の銅微粒子が良い。平均粒子径４０ｎｍ以下の銅微粒子に加える粒子径の大きい銅微粒子は、細かい銅微粒子質量の１００倍以上であり、平均粒子径２００〜８００ｎｍであることが必要である。 When a fired film is formed on a resin substrate such as a phenol resin or an epoxy resin, a firing temperature of 220 ° C. or less that does not deteriorate the resin physical properties is preferable, and copper fine particles having an average particle diameter of 40 nm or less are preferable. The copper fine particles having a large particle diameter added to the copper fine particles having an average particle diameter of 40 nm or less must be 100 times or more the fine copper fine particle mass and have an average particle diameter of 200 to 800 nm.
平均粒子径２００〜８００ｎｍの銅微粒子は液相法で銅化合物を還元析出する方法で量産されている。平均粒子径が２００ｎｍより大きい銅微粒子は、粒子間凝集が少ないので約３０％の空隙率であるが、平均粒子径が１００ｎｍより細かい銅微粒子は、粒子同士の結合力が強く、ネットワーク状に凝集しているので、その空隙率は６０％以上にもなっている。したがって、平均粒子径１００ｎｍ以下の銅微粒子だけで焼成膜を形成すると、空隙率が大きいので、焼結工程で大きな焼結収縮が生じ、焼成膜に焼結収縮によるワレが生じ、緻密な膜とならず低抵抗焼成膜が形成されない。 Copper fine particles having an average particle diameter of 200 to 800 nm are mass-produced by a method of reducing and precipitating a copper compound by a liquid phase method. Copper fine particles with an average particle diameter of more than 200 nm have a porosity of about 30% because there is little aggregation between particles, but copper fine particles with an average particle diameter of less than 100 nm have a strong bonding force between particles and aggregate in a network. Therefore, the porosity is 60% or more. Therefore, when a fired film is formed only with copper fine particles having an average particle diameter of 100 nm or less, since the porosity is large, large sintering shrinkage occurs in the sintering process, cracking due to sintering shrinkage occurs in the fired film, In other words, a low resistance fired film is not formed.
平均粒子径４０ｎｍ以下の銅微粒子３０〜７０質量％と、平均粒子径２００〜８００ｎｍの銅微粒子７０〜３０質量％に配合分散することによって、塗膜中の銅微粒子の空隙率が改善され、緻密な焼成膜形成が可能となる。平均粒子径４０ｎｍの銅微粒子と質量差の少ない銅微粒子を配合しても、焼結収縮による塗膜面の亀裂が生じ、優れた導電性が得られない。細かい銅微粒子に対して大きい銅微粒子の質量が１００倍以上であることは、塗膜空隙率の減少、焼成工程中の焼成膜温度分布、スクリーン印刷での流動特性なども改善され、低抵抗焼成膜が形成されると考えられる。質量が１００倍以上の銅微粒子の平均粒子径は２００〜８００ｎｍが良い。２００ｎｍ未満であると緻密な焼成膜の形成が難しい。８００ｎｍを超える微粒子だと焼成温度が高くなると共に平滑な焼成膜面が得られず、ファインパターン回路形成においても微細な配線印刷が難しくなる。
平均粒子径４０ｎｍ以下の銅微粒子が７０質量％より多いと、焼成膜に焼結収縮による亀裂が多くなり、緻密な低抵抗焼成膜が形成できない。また、平均粒子径４０ｎｍ以下の銅微粒子が３０質量％より少ないと、焼成温度が高くなり樹脂基板への対応が難しくなり、焼成膜も凹凸が多くなり低抵抗焼成膜が形成できない。
By mixing and dispersing in 30 to 70% by mass of copper fine particles having an average particle size of 40 nm or less and 70 to 30% by mass of copper fine particles having an average particle size of 200 to 800 nm, the porosity of the copper fine particles in the coating film is improved, and the fine particles are dense. Can form a fired film. Even if copper fine particles having an average particle diameter of 40 nm and copper fine particles having a small mass difference are blended, cracks in the coating film surface due to sintering shrinkage occur, and excellent conductivity cannot be obtained. The fact that the mass of the large copper fine particles is 100 times or more than the fine copper fine particles means that the porosity of the coating film is reduced, the temperature distribution of the fired film during the firing process, the flow characteristics in screen printing, etc. are improved, and low resistance firing. It is thought that a film is formed. The average particle diameter of copper fine particles having a mass of 100 times or more is preferably 200 to 800 nm. If the thickness is less than 200 nm, it is difficult to form a dense fired film. If the fine particle exceeds 800 nm, the firing temperature becomes high and a smooth fired film surface cannot be obtained, and fine wiring printing becomes difficult even in fine pattern circuit formation.
When there are more than 70% by mass of copper fine particles having an average particle size of 40 nm or less, cracks due to sintering shrinkage increase in the fired film, and a dense low resistance fired film cannot be formed. On the other hand, if the amount of copper fine particles having an average particle diameter of 40 nm or less is less than 30% by mass, the firing temperature becomes high and it becomes difficult to cope with the resin substrate, and the fired film also has unevenness, and a low resistance fired film cannot be formed.
本発明の配合比率に銅微粒子を調整する方法としては、それぞれの銅微粒子を計量し、ペースト作成時に加えても良い。しかし、銅微粒子の酸化防止や、粒子径が大きく異なる銅微粒子同士を均一分散するためには、あらかじめ銅微粒子を粘性液で湿潤、分散してペースト作成時に加える方法が良い。粘性液は銅微粒子の酸化や凝集を防止し、焼成膜がより低温で形成されやすい有機溶媒が好ましい。最適な粘性液としてはアルコールの一種のポリオールであるグリコールが良い。グリコールは加熱すると金属酸化物を還元する溶媒として良く知られている有機溶媒で、エチレングリコール、プロピレングリコール、ジエチレングリコールなどを挙げることができる。グリコール量は銅微粒子を湿潤被覆する量が好ましく、銅微粒子１００質量部に対して５〜５０質量部が良い。 As a method for adjusting the copper fine particles to the blending ratio of the present invention, each copper fine particle may be weighed and added at the time of preparing the paste. However, in order to prevent oxidation of copper fine particles and to uniformly disperse copper fine particles having greatly different particle diameters, a method of adding and dispersing copper fine particles in a viscous liquid in advance during paste preparation is preferable. The viscous liquid is preferably an organic solvent that prevents oxidation and aggregation of the copper fine particles and allows the fired film to be easily formed at a lower temperature. As an optimal viscous liquid, glycol which is a kind of alcohol is good. Glycol is an organic solvent well known as a solvent that reduces metal oxides when heated. Examples thereof include ethylene glycol, propylene glycol, and diethylene glycol. The amount of glycol is preferably an amount for wet-coating the copper fine particles, and is preferably 5 to 50 parts by mass with respect to 100 parts by mass of the copper fine particles.
本発明の低温焼成ペースト用銅微粒子を有機溶媒中に混練、分散して印刷用ペーストにして、スクリーン印刷で配線パターンを樹脂基板上に塗布し、その後２５０℃以下の焼成温度、水素含有窒素ガス雰囲気で加熱焼成すると、２００ｎｍ〜８００ｎｍの銅微粒子が核となり、４０ｎｍ以下の銅微粒子が融着しながら焼結しネットワークを構成し、焼結収縮ワレのない、均一な低抵抗焼成膜が得られている。本発明の銅微粒子を分散した低温焼成ペーストを用いて、フェノールあるいはエポキシ樹脂基板上に緻密な低抵抗焼成膜を形成する場合、樹脂の耐熱性から焼成温度は２００〜２２０℃が良く、水素含有量５０％以下の窒素ガス雰囲気で作製するのが良い。このように、焼成温度は樹脂基板の耐熱性にもよるが、２５０℃以下の低温でも緻密な銅焼成膜が形成できるようになった。低温焼成銅微粒子分散ペーストの組成としては、沸点の高いグリコール、鉱物油、合成油、植物油、流動パラフィンなどを粘度調整有機溶剤として用い、少量の有機ビヒクルを添加することで目的とする焼成膜物性にすることが可能である。この場合の有機ビヒクルとしてはエチルセルローズ、メチルセルローズ、アクリル樹脂、アルキッド樹脂、ブチラール樹脂、エポキシ樹脂、フェノール樹脂、ロジン、ワックスなどを挙げることができる。 The copper fine particles for low-temperature firing paste of the present invention are kneaded and dispersed in an organic solvent to obtain a printing paste, and a wiring pattern is applied on a resin substrate by screen printing, and then a firing temperature of 250 ° C. or less, hydrogen-containing nitrogen gas When heated and fired in an atmosphere, copper fine particles of 200 nm to 800 nm become cores, and copper fine particles of 40 nm or less are sintered while fusing to form a network, and a uniform low-resistance fired film having no sintering shrinkage is obtained. ing. When a dense low-resistance fired film is formed on a phenol or epoxy resin substrate using the low-temperature fired paste in which the copper fine particles of the present invention are dispersed, the firing temperature is preferably 200 to 220 ° C. from the heat resistance of the resin, and contains hydrogen. It is good to produce it in nitrogen gas atmosphere of the quantity 50% or less. Thus, although the firing temperature depends on the heat resistance of the resin substrate, a dense copper fired film can be formed even at a low temperature of 250 ° C. or lower. The composition of the low-temperature calcined copper fine particle dispersion paste uses glycol, mineral oil, synthetic oil, vegetable oil, liquid paraffin, etc. with a high boiling point as the viscosity-adjusting organic solvent, and the desired calcined film properties by adding a small amount of organic vehicle It is possible to Examples of the organic vehicle in this case include ethyl cellulose, methyl cellulose, acrylic resin, alkyd resin, butyral resin, epoxy resin, phenol resin, rosin, and wax.
本発明の銅微粒子を分散した低温焼成ペーストは、２５０℃以下の焼成温度で緻密な低抵抗焼成膜が容易に形成でき、樹脂基板への対応も可能となった。また、平均粒子径が２００ｎｍ以上の銅微粒子が使用できるので、ペーストの貯蔵安定性も向上し、より安価な低温焼成ペースが提供できるようになり、銀微粒子の代替だけでなく、様々な用途に使用できるようになった。 The low-temperature firing paste in which the copper fine particles of the present invention are dispersed can easily form a dense low-resistance fired film at a firing temperature of 250 ° C. or less, and can be applied to a resin substrate. In addition, since copper fine particles having an average particle size of 200 nm or more can be used, the storage stability of the paste is improved, and a cheaper low-temperature firing pace can be provided. It can be used now.
以下、本発明の実施の形態である実施例を説明する。 Examples of the present invention will be described below.
（実施例１）
液相還元法で製造した平均粒子径８ｎｍの銅微粒子３０質量部に、液相還元法で製造した平均粒子径２１０ｎｍの銅微粒子７０質量部を加え、湿潤剤としてエチレングリコール２０質量部添加し、ミキサーで６０ｒｐｍ、２０分間攪拌し、２種類の銅微粒子が均一分散した本発明の低温焼成ペースト用銅微粒子を作製した。このようにして作製した本発明の銅微粒子を分散した焼成ペーストの焼成膜特性評価を以下の方法で行った。作製した銅微粒子にエチレングリコール２５質量部加えて混練、スクリーン印刷インキ用粘度に調整する。その後、エポキシ樹脂基板上にスクリーン印刷で配線パターンを塗布し、水素０．２L/min＋窒素１L/min混合ガス雰囲気の焼成炉で、２００℃で９０分間加熱し、銅焼成膜を形成した。その結果、比抵抗４×１０−５Ω・ｃｍの緻密で平滑な低抵抗焼成膜が得られた。
Example 1
To 70 parts by mass of copper fine particles having an average particle diameter of 8 nm produced by the liquid phase reduction method, 70 parts by mass of copper fine particles having an average particle diameter of 210 nm produced by the liquid phase reduction method are added, and 20 parts by mass of ethylene glycol is added as a wetting agent. The mixture was stirred with a mixer at 60 rpm for 20 minutes to prepare copper fine particles for low-temperature firing paste of the present invention in which two types of copper fine particles were uniformly dispersed. The fired film characteristics of the fired paste in which the copper fine particles of the present invention thus prepared were dispersed were evaluated by the following methods. 25 parts by mass of ethylene glycol is added to the prepared copper fine particles and kneaded to adjust the viscosity for screen printing ink. Thereafter, a wiring pattern was applied on the epoxy resin substrate by screen printing, and heated at 200 ° C. for 90 minutes in a baking furnace in a mixed gas atmosphere of hydrogen 0.2 L / min + nitrogen 1 L / min to form a copper fired film. As a result, a dense and smooth low-resistance fired film having a specific resistance of 4 × 10 −5 Ω · cm was obtained.
（実施例２）
液相還元法で製造した平均粒子径８ｎｍの銅微粒子５０質量部に、液相還元法で製造した平均粒子径２１０ｎｍの銅微粒子５０質量部を加え、湿潤剤としてエチレングリコール２０質量部添加し、ミキサーで６０ｒｐｍ、２０分間攪拌し、２種類の銅微粒子が均一分散した本発明の低温焼成ペースト用銅微粒子を作製した。このようにして作製した本発明の銅微粒子を分散した焼成ペーストの焼成膜特性評価を以下の方法で行った。作製した銅微粒子にエチレングリコール３０質量部加えて混練、スクリーン印刷インキ用粘度に調整する。その後、エポキシ樹脂基板上にスクリーン印刷で配線パターンを塗布し、水素０．２L/min＋窒素１L/min混合ガス雰囲気の焼成炉で、２００℃で９０分間加熱し、銅焼成膜を形成した。その結果、比抵抗３×１０−５Ω・ｃｍの緻密で平滑な低抵抗焼成膜が得られた。
(Example 2)
To 50 parts by mass of copper fine particles having an average particle diameter of 8 nm produced by the liquid phase reduction method, 50 parts by mass of copper fine particles having an average particle diameter of 210 nm produced by the liquid phase reduction method are added, and 20 parts by mass of ethylene glycol is added as a wetting agent. The mixture was stirred with a mixer at 60 rpm for 20 minutes to prepare copper fine particles for low-temperature firing paste of the present invention in which two types of copper fine particles were uniformly dispersed. The fired film characteristics of the fired paste in which the copper fine particles of the present invention thus prepared were dispersed were evaluated by the following methods. 30 parts by mass of ethylene glycol is added to the prepared copper fine particles and kneaded to adjust the viscosity for screen printing ink. Thereafter, a wiring pattern was applied on the epoxy resin substrate by screen printing, and heated at 200 ° C. for 90 minutes in a baking furnace in a mixed gas atmosphere of hydrogen 0.2 L / min + nitrogen 1 L / min to form a copper fired film. As a result, a dense and smooth low-resistance fired film having a specific resistance of 3 × 10 −5 Ω · cm was obtained.
（実施例３）
液相還元法で製造した平均粒子径８ｎｍの銅微粒子５０質量部、液相還元法で製造した平均粒子径２１０ｎｍの銅微粒子５０質量部、エチレングリコール５０質量部を加え、ミキサーで６０ｒｐｍ、９０分間攪拌し本発明の銅微粒子分散ペーストを作製した。このようにして作製した本発明の銅微粒子分散ペーストの焼成膜特性評価を以下の方法で行った。エポキシ樹脂基板上にスクリーン印刷で配線パターンを塗布し、水素０．２L/min＋窒素１L/min混合ガス雰囲気の焼成炉で、２００℃で９０分間加熱し、銅焼成膜を形成した。その結果、比抵抗６×１０−５Ω・ｃｍの緻密で平滑な低抵抗焼成膜が得られた。
(Example 3)
Add 50 parts by mass of copper fine particles with an average particle diameter of 8 nm produced by the liquid phase reduction method, 50 parts by mass of copper fine particles with an average particle diameter of 210 nm produced by the liquid phase reduction method, and 50 parts by mass of ethylene glycol, and add 60 rpm at the mixer for 90 minutes. The copper fine particle dispersed paste of the present invention was prepared by stirring. The fired film characteristics of the copper fine particle dispersed paste of the present invention thus produced were evaluated by the following method. A wiring pattern was applied on an epoxy resin substrate by screen printing, and heated at 200 ° C. for 90 minutes in a baking furnace in a mixed gas atmosphere of hydrogen 0.2 L / min + nitrogen 1 L / min to form a copper fired film. As a result, a dense and smooth low-resistance fired film having a specific resistance of 6 × 10 −5 Ω · cm was obtained.
（実施例４）
液相還元法で製造した平均粒子径８ｎｍの銅微粒子７０質量部に、液相還元法で製造した平均粒子径２１０ｎｍの銅微粒子３０質量部を加え、湿潤剤としてエチレングリコール２０質量部添加し、ミキサーで６０ｒｐｍ、２０分間攪拌し、２種類の銅微粒子が均一分散した本発明の低温焼成ペースト用銅微粒子を作製した。このようにして作製した本発明の銅微粒子を分散した焼成ペーストの焼成膜特性評価を以下の方法で行った。作製した銅微粒子にエチレングリコール３５質量部加えて混練、スクリーン印刷インキ用粘度に調整する。その後、エポキシ樹脂基板上にスクリーン印刷で配線パターンを塗布し、水素０．２L/min＋窒素１L/min混合ガス雰囲気の焼成炉で、２００℃で９０分間加熱し、銅焼成膜を形成した。その結果、小さい焼結収縮ワレが認められるが、比抵抗６×１０−５Ω・ｃｍの緻密な低抵抗焼成膜が得られた。エチレングリコールで湿潤した本発明の銅微粒子は凝集や酸化が少なく、１０日間放置後も同じ比抵抗の焼成膜が形成できた。
Example 4
To 70 parts by mass of copper fine particles having an average particle diameter of 8 nm produced by the liquid phase reduction method, 30 parts by mass of copper fine particles having an average particle diameter of 210 nm produced by the liquid phase reduction method are added, and 20 parts by mass of ethylene glycol is added as a wetting agent. The mixture was stirred with a mixer at 60 rpm for 20 minutes to prepare copper fine particles for low-temperature firing paste of the present invention in which two types of copper fine particles were uniformly dispersed. The fired film characteristics of the fired paste in which the copper fine particles of the present invention thus prepared were dispersed were evaluated by the following methods. 35 parts by mass of ethylene glycol is added to the prepared copper fine particles and kneaded to adjust the viscosity for screen printing ink. Thereafter, a wiring pattern was applied on the epoxy resin substrate by screen printing, and heated at 200 ° C. for 90 minutes in a baking furnace in a mixed gas atmosphere of hydrogen 0.2 L / min + nitrogen 1 L / min to form a copper fired film. As a result, a small sintered shrinkage crack was observed, but a dense low-resistance fired film having a specific resistance of 6 × 10 −5 Ω · cm was obtained. The copper fine particles of the present invention wetted with ethylene glycol had little aggregation and oxidation, and a fired film having the same specific resistance could be formed even after standing for 10 days.
（実施例５）
液相還元法で製造した平均粒子径１３ｎｍの銅微粒子３０質量部に、液相還元法で製造した平均粒子径４２０ｎｍの銅微粒子７０質量部を加え、湿潤剤としてプロピレングリコール１５質量部添加し、ミキサーで６０ｒｐｍ、２０分間攪拌し、２種類の銅微粒子が均一分散した本発明の低温焼成ペースト用銅微粒子を作製した。このようにして作製した本発明の銅微粒子を分散した焼成ペーストの焼成膜特性評価を以下の方法で行った。作製した銅微粒子にプロピレングリコール３０質量部加えて混練、スクリーン印刷インキ用粘度に調整する。その後、エポキシ樹脂基板上にスクリーン印刷で配線パターンを塗布し、水素０．５L/min＋窒素１L/min混合ガス雰囲気の焼成炉で、２００℃で９０分間加熱し、銅焼成膜を形成した。その結果、比抵抗３．５×１０−５Ω・ｃｍの緻密で平滑な低抵抗焼成膜が得られた。
(Example 5)
To 30 parts by mass of copper fine particles having an average particle diameter of 13 nm produced by the liquid phase reduction method, 70 parts by mass of copper fine particles having an average particle diameter of 420 nm produced by the liquid phase reduction method are added, and 15 parts by mass of propylene glycol is added as a wetting agent. The mixture was stirred with a mixer at 60 rpm for 20 minutes to prepare copper fine particles for low-temperature firing paste of the present invention in which two types of copper fine particles were uniformly dispersed. The fired film characteristics of the fired paste in which the copper fine particles of the present invention thus prepared were dispersed were evaluated by the following methods. 30 parts by mass of propylene glycol is added to the prepared copper fine particles and kneaded to adjust the viscosity for screen printing ink. Thereafter, a wiring pattern was applied on the epoxy resin substrate by screen printing, and heated at 200 ° C. for 90 minutes in a baking furnace in a mixed gas atmosphere of hydrogen 0.5 L / min + nitrogen 1 L / min to form a copper fired film. As a result, a dense and smooth low-resistance fired film having a specific resistance of 3.5 × 10 −5 Ω · cm was obtained.
（実施例６）
液相還元法で製造した平均粒子径１３ｎｍの銅微粒子５０質量部に、液相還元法で製造した平均粒子径４２０ｎｍの銅微粒子５０質量部を加え、湿潤剤としてプロピレングリコール１５質量部添加し、ミキサーで６０ｒｐｍ、２０分間攪拌し、２種類の銅微粒子が均一分散した本発明の低温焼成ペースト用銅微粒子を作製した。このようにして作製した本発明の銅微粒子を分散した焼成ペーストの焼成膜特性評価を以下の方法で行った。作製した銅微粒子にプロピレングリコール３５質量部加えて混練、スクリーン印刷インキ用粘度に調整する。その後、エポキシ樹脂基板上にスクリーン印刷で配線パターンを塗布し、水素０．５L/min＋窒素１L/min混合ガス雰囲気の焼成炉で、２００℃で９０分間加熱し、銅焼成膜を形成した。その結果、比抵抗２．５×１０−５Ω・ｃｍの緻密で平滑な低抵抗焼成膜が得られた。
(Example 6)
To 50 parts by mass of copper fine particles having an average particle diameter of 13 nm produced by the liquid phase reduction method, 50 parts by mass of copper fine particles having an average particle diameter of 420 nm produced by the liquid phase reduction method are added, and 15 parts by mass of propylene glycol is added as a wetting agent. The mixture was stirred with a mixer at 60 rpm for 20 minutes to prepare copper fine particles for low-temperature firing paste of the present invention in which two types of copper fine particles were uniformly dispersed. The fired film characteristics of the fired paste in which the copper fine particles of the present invention thus prepared were dispersed were evaluated by the following methods. 35 parts by mass of propylene glycol is added to the prepared copper fine particles and kneaded to adjust the viscosity for screen printing ink. Thereafter, a wiring pattern was applied on the epoxy resin substrate by screen printing, and heated at 200 ° C. for 90 minutes in a baking furnace in a mixed gas atmosphere of hydrogen 0.5 L / min + nitrogen 1 L / min to form a copper fired film. As a result, a dense and smooth low-resistance fired film having a specific resistance of 2.5 × 10 −5 Ω · cm was obtained.
（実施例７）
液相還元法で製造した平均粒子径１３ｎｍの銅微粒子７０質量部に、液相還元法で製造した平均粒子径４２０ｎｍの銅微粒子３０質量部を加え、湿潤剤としてプロピレングリコール１５質量部添加し、ミキサーで６０ｒｐｍ、２０分間攪拌し、２種類の銅微粒子が均一分散した本発明の低温焼成ペースト用銅微粒子を作製した。このようにして作製した本発明の銅微粒子を分散した焼成ペーストの焼成膜特性評価を以下の方法で行った。作製した銅微粒子にプロピレングリコール４０質量部加えて混練、スクリーン印刷インキ用粘度に調整する。その後、エポキシ樹脂基板上にスクリーン印刷で配線パターンを塗布し、水素０．５L/min＋窒素１L/min混合ガス雰囲気の焼成炉で、２００℃で９０分間加熱し、銅焼成膜を形成した。その結果、小さい焼結収縮ワレが認められるが、比抵抗５×１０−５Ω・ｃｍの緻密な低抵抗焼成膜が得られた。プロピレングリコールで湿潤した本発明の銅微粒子は凝集や酸化が少なく、１０日間放置後も同じ比抵抗の焼成膜が形成できた。
(Example 7)
To 70 parts by mass of copper fine particles having an average particle diameter of 13 nm produced by the liquid phase reduction method, 30 parts by mass of copper fine particles having an average particle diameter of 420 nm produced by the liquid phase reduction method are added, and 15 parts by mass of propylene glycol is added as a wetting agent. The mixture was stirred with a mixer at 60 rpm for 20 minutes to prepare copper fine particles for low-temperature firing paste of the present invention in which two types of copper fine particles were uniformly dispersed. The fired film characteristics of the fired paste in which the copper fine particles of the present invention thus prepared were dispersed were evaluated by the following methods. 40 parts by mass of propylene glycol is added to the prepared copper fine particles and kneaded to adjust the viscosity for screen printing ink. Thereafter, a wiring pattern was applied on the epoxy resin substrate by screen printing, and heated at 200 ° C. for 90 minutes in a baking furnace in a mixed gas atmosphere of hydrogen 0.5 L / min + nitrogen 1 L / min to form a copper fired film. As a result, a small sintered shrinkage crack was observed, but a dense low-resistance fired film having a specific resistance of 5 × 10 −5 Ω · cm was obtained. The copper fine particles of the present invention wetted with propylene glycol had little aggregation and oxidation, and a fired film having the same specific resistance could be formed even after standing for 10 days.
（実施例８）
液相還元法で製造した平均粒子径３８ｎｍの銅微粒子３０質量部に、液相還元法で製造した平均粒子径２１０ｎｍの銅微粒子７０質量部を加え、湿潤剤としてプロピレングリコール１５質量部添加し、ミキサーで６０ｒｐｍ、２０分間攪拌し、２種類の銅微粒子が均一分散した本発明の低温焼成ペースト用銅微粒子を作製した。このようにして作製した本発明の銅微粒子を分散した焼成ペーストの焼成膜特性評価を以下の方法で行った。作製した銅微粒子にエチレングリコール２５質量部加えて混練、スクリーン印刷インキ用粘度に調整する。その後、エポキシ樹脂基板上にスクリーン印刷で配線パターンを塗布し、水素０．５L/min＋窒素１L/min混合ガス雰囲気の焼成炉で、２００℃で９０分間加熱し、銅焼成膜を形成した。その結果、比抵抗６×１０−５Ω・ｃｍの緻密で平滑な低抵抗焼成膜が得られた。
(Example 8)
To 70 parts by mass of copper fine particles having an average particle diameter of 38 nm produced by the liquid phase reduction method, 70 parts by mass of copper fine particles having an average particle diameter of 210 nm produced by the liquid phase reduction method are added, and 15 parts by mass of propylene glycol is added as a wetting agent. The mixture was stirred with a mixer at 60 rpm for 20 minutes to prepare copper fine particles for low-temperature firing paste of the present invention in which two types of copper fine particles were uniformly dispersed. The fired film characteristics of the fired paste in which the copper fine particles of the present invention thus prepared were dispersed were evaluated by the following methods. 25 parts by mass of ethylene glycol is added to the prepared copper fine particles and kneaded to adjust the viscosity for screen printing ink. Thereafter, a wiring pattern was applied on the epoxy resin substrate by screen printing, and heated at 200 ° C. for 90 minutes in a baking furnace in a mixed gas atmosphere of hydrogen 0.5 L / min + nitrogen 1 L / min to form a copper fired film. As a result, a dense and smooth low-resistance fired film having a specific resistance of 6 × 10 −5 Ω · cm was obtained.
（実施例９）
液相還元法で製造した平均粒子径３８ｎｍの銅微粒子５０質量部に、液相還元法で製造した平均粒子径２１０ｎｍの銅微粒子５０質量部を加え、湿潤剤としてプロピレングリコール１５質量部添加し、ミキサーで６０ｒｐｍ、２０分間攪拌し、２種類の銅微粒子が均一分散した本発明の低温焼成ペースト用銅微粒子を作製した。このようにして作製した本発明の銅微粒子を分散した焼成ペーストの焼成膜特性評価を以下の方法で行った。作製した銅微粒子にエチレングリコール３０質量部加えて混練、スクリーン印刷インキ用粘度に調整する。その後、エポキシ樹脂基板上にスクリーン印刷で配線パターンを塗布し、水素０．５L/min＋窒素１L/min混合ガス雰囲気の焼成炉で、２００℃で９０分間加熱し、銅焼成膜を形成した。その結果、比抵抗４．５×１０−５Ω・ｃｍの緻密で平滑な低抵抗焼成膜が得られた。
Example 9
To 50 parts by mass of copper fine particles having an average particle diameter of 38 nm produced by the liquid phase reduction method, 50 parts by mass of copper fine particles having an average particle diameter of 210 nm produced by the liquid phase reduction method are added, and 15 parts by mass of propylene glycol is added as a wetting agent. The mixture was stirred with a mixer at 60 rpm for 20 minutes to prepare copper fine particles for low-temperature firing paste of the present invention in which two types of copper fine particles were uniformly dispersed. The fired film characteristics of the fired paste in which the copper fine particles of the present invention thus prepared were dispersed were evaluated by the following methods. 30 parts by mass of ethylene glycol is added to the prepared copper fine particles and kneaded to adjust the viscosity for screen printing ink. Thereafter, a wiring pattern was applied on the epoxy resin substrate by screen printing, and heated at 200 ° C. for 90 minutes in a baking furnace in a mixed gas atmosphere of hydrogen 0.5 L / min + nitrogen 1 L / min to form a copper fired film. As a result, a dense and smooth low-resistance fired film having a specific resistance of 4.5 × 10 −5 Ω · cm was obtained.
（実施例１０）
液相還元法で製造した平均粒子径３８ｎｍの銅微粒子７０質量部に、液相還元法で製造した平均粒子径２１０ｎｍの銅微粒子３０質量部を加え、湿潤剤としてプロピレングリコール１５質量部添加し、ミキサーで６０ｒｐｍ、２０分間攪拌し、２種類の銅微粒子が均一分散した本発明の低温焼成ペースト用銅微粒子を作製した。このようにして作製した本発明の銅微粒子を分散した焼成ペーストの焼成膜特性評価を以下の方法で行った。作製した銅微粒子にエチレングリコール３０質量部加えて混練、スクリーン印刷インキ用粘度に調整する。その後、エポキシ樹脂基板上にスクリーン印刷で配線パターンを塗布し、水素０．５L/min＋窒素１L/min混合ガス雰囲気の焼成炉で、２００℃で９０分間加熱し、銅焼成膜を形成した。その結果、小さい焼結収縮ワレが認められるが、比抵抗５×１０−５Ω・ｃｍの緻密な低抵抗焼成膜が得られた。
(Example 10)
To 70 parts by mass of copper fine particles having an average particle diameter of 38 nm produced by the liquid phase reduction method, 30 parts by mass of copper fine particles having an average particle diameter of 210 nm produced by the liquid phase reduction method are added, and 15 parts by mass of propylene glycol is added as a wetting agent. The mixture was stirred with a mixer at 60 rpm for 20 minutes to prepare copper fine particles for low-temperature firing paste of the present invention in which two types of copper fine particles were uniformly dispersed. The fired film characteristics of the fired paste in which the copper fine particles of the present invention thus prepared were dispersed were evaluated by the following methods. 30 parts by mass of ethylene glycol is added to the prepared copper fine particles and kneaded to adjust the viscosity for screen printing ink. Thereafter, a wiring pattern was applied on the epoxy resin substrate by screen printing, and heated at 200 ° C. for 90 minutes in a baking furnace in a mixed gas atmosphere of hydrogen 0.5 L / min + nitrogen 1 L / min to form a copper fired film. As a result, a small sintered shrinkage crack was observed, but a dense low-resistance fired film having a specific resistance of 5 × 10 −5 Ω · cm was obtained.
（実施例１１）
液相還元法で製造した平均粒子径８ｎｍの銅微粒子３０質量部に、液相還元法で製造した平均粒子径７５０ｎｍの銅微粒子７０質量部を加え、湿潤剤としてエチレングリコール５質量部添加し、ミキサーで６０ｒｐｍ、２０分間攪拌し、７５０ｎｍ銅微粒子に８ｎｍ銅微粒子を均一に被覆分散した本発明の低温焼成ペースト用銅微粒子を作製した。このようにして作製した本発明の銅微粒子を分散した焼成ペーストの焼成膜特性評価を以下の方法で行った。作製した銅微粒子にエチレングリコール３０質量部加えて混練、スクリーン印刷インキ用粘度に調整する。その後、エポキシ樹脂基板上にスクリーン印刷で配線パターンを塗布し、水素０．５L/min＋窒素１L/min混合ガス雰囲気の焼成炉で、２００℃で９０分間加熱し、銅焼成膜を形成した。その結果、比抵抗３．５×１０−５Ω・ｃｍの緻密で平滑な低抵抗焼成膜が得られた。
(Example 11)
To 70 parts by mass of copper fine particles having an average particle diameter of 8 nm produced by the liquid phase reduction method, 70 parts by mass of copper fine particles having an average particle diameter of 750 nm produced by the liquid phase reduction method are added, and 5 parts by mass of ethylene glycol is added as a wetting agent. The mixture was stirred for 20 minutes at 60 rpm with a mixer to prepare copper fine particles for low-temperature firing paste of the present invention in which 8 nm copper fine particles were uniformly coated and dispersed on 750 nm copper fine particles. The fired film characteristics of the fired paste in which the copper fine particles of the present invention thus prepared were dispersed were evaluated by the following methods. 30 parts by mass of ethylene glycol is added to the prepared copper fine particles and kneaded to adjust the viscosity for screen printing ink. Thereafter, a wiring pattern was applied on the epoxy resin substrate by screen printing, and heated at 200 ° C. for 90 minutes in a baking furnace in a mixed gas atmosphere of hydrogen 0.5 L / min + nitrogen 1 L / min to form a copper fired film. As a result, a dense and smooth low-resistance fired film having a specific resistance of 3.5 × 10 −5 Ω · cm was obtained.
（実施例１２）
液相還元法で製造した平均粒子径８ｎｍの銅微粒子５０質量部に、液相還元法で製造した平均粒子径７５０ｎｍの銅微粒子５０質量部を加え、湿潤剤としてエチレングリコール５質量部添加し、ミキサーで６０ｒｐｍ、２０分間攪拌し、７５０ｎｍ銅微粒子に８ｎｍ銅微粒子を均一に被覆分散した本発明の低温焼成ペースト用銅微粒子を作製した。このようにして作製した本発明の銅微粒子を分散した焼成ペーストの焼成膜特性評価を以下の方法で行った。作製した銅微粒子にエチレングリコール３５質量部加えて混練、スクリーン印刷インキ用粘度に調整する。その後、エポキシ樹脂基板上にスクリーン印刷で配線パターンを塗布し、水素０．５L/min＋窒素１L/min混合ガス雰囲気の焼成炉で、２００℃で９０分間加熱し、銅焼成膜を形成した。その結果、比抵抗３×１０−５Ω・ｃｍの緻密で平滑な低抵抗焼成膜が得られた。
(Example 12)
To 50 parts by mass of copper fine particles having an average particle diameter of 8 nm produced by the liquid phase reduction method, 50 parts by mass of copper fine particles having an average particle diameter of 750 nm produced by the liquid phase reduction method are added, and 5 parts by mass of ethylene glycol is added as a wetting agent. The mixture was stirred for 20 minutes at 60 rpm with a mixer to prepare copper fine particles for low-temperature firing paste of the present invention in which 8 nm copper fine particles were uniformly coated and dispersed on 750 nm copper fine particles. The fired film characteristics of the fired paste in which the copper fine particles of the present invention thus prepared were dispersed were evaluated by the following methods. 35 parts by mass of ethylene glycol is added to the prepared copper fine particles and kneaded to adjust the viscosity for screen printing ink. Thereafter, a wiring pattern was applied on the epoxy resin substrate by screen printing, and heated at 200 ° C. for 90 minutes in a baking furnace in a mixed gas atmosphere of hydrogen 0.5 L / min + nitrogen 1 L / min to form a copper fired film. As a result, a dense and smooth low-resistance fired film having a specific resistance of 3 × 10 −5 Ω · cm was obtained.
（実施例１３）
液相還元法で製造した平均粒子径８ｎｍの銅微粒子７０質量部に、液相還元法で製造した平均粒子径７５０ｎｍの銅微粒子３０質量部を加え、湿潤剤としてエチレングリコール１０質量部添加し、ミキサーで６０ｒｐｍ、２０分間攪拌し、７５０ｎｍ銅微粒子に８ｎｍ銅微粒子を均一に被覆分散した本発明の低温焼成ペースト用銅微粒子を作製した。このようにして作製した本発明の銅微粒子を分散した焼成ペーストの焼成膜特性評価を以下の方法で行った。作製した銅微粒子にエチレングリコール３５質量部加えて混練、スクリーン印刷インキ用粘度に調整する。その後、エポキシ樹脂基板上にスクリーン印刷で配線パターンを塗布し、水素０．５L/min＋窒素１L/min混合ガス雰囲気の焼成炉で、２００℃で９０分間加熱し、銅焼成膜を形成した。その結果、小さい焼結収縮ワレが認められるが、比抵抗５×１０−５Ω・ｃｍの緻密な低抵抗焼成膜が得られた。
(Example 13)
To 70 parts by mass of copper fine particles having an average particle diameter of 8 nm produced by the liquid phase reduction method, 30 parts by mass of copper fine particles having an average particle diameter of 750 nm produced by the liquid phase reduction method are added, and 10 parts by mass of ethylene glycol is added as a wetting agent. The mixture was stirred for 20 minutes at 60 rpm with a mixer to prepare copper fine particles for low-temperature firing paste of the present invention in which 8 nm copper fine particles were uniformly coated and dispersed on 750 nm copper fine particles. The fired film characteristics of the fired paste in which the copper fine particles of the present invention thus prepared were dispersed were evaluated by the following methods. 35 parts by mass of ethylene glycol is added to the prepared copper fine particles and kneaded to adjust the viscosity for screen printing ink. Thereafter, a wiring pattern was applied on the epoxy resin substrate by screen printing, and heated at 200 ° C. for 90 minutes in a baking furnace in a mixed gas atmosphere of hydrogen 0.5 L / min + nitrogen 1 L / min to form a copper fired film. As a result, a small sintered shrinkage crack was observed, but a dense low-resistance fired film having a specific resistance of 5 × 10 −5 Ω · cm was obtained.
（実施例１４）
液相還元法で製造した平均粒子径１３ｎｍの銅微粒子５０質量部に、液相還元法で製造した平均粒子径４２０ｎｍの銅微粒子５０質量部を加え、湿潤剤としてプロピレングリコール１５質量部添加し、ミキサーで６０ｒｐｍ、２０分間攪拌し、２種類の銅微粒子が均一分散した本発明の低温焼成ペースト用銅微粒子を作製した。このようにして作製した本発明の銅微粒子を分散した焼成ペーストの焼成膜特性評価を以下の方法で行った。作製した銅微粒子にエチレングリコール３５質量部とワックス１質量部加えて混練、スクリーン印刷用インキに調整する。その後、エポキシ樹脂基板上にスクリーン印刷で配線パターンを塗布し、水素０．５L/min＋窒素１L/min混合ガス雰囲気の焼成炉で、２００℃で９０分間加熱し、銅焼成膜を形成した。その結果、比抵抗４×１０−５Ω・ｃｍの緻密で平滑な低抵抗焼成膜が得られた。
(Example 14)
To 50 parts by mass of copper fine particles having an average particle diameter of 13 nm produced by the liquid phase reduction method, 50 parts by mass of copper fine particles having an average particle diameter of 420 nm produced by the liquid phase reduction method are added, and 15 parts by mass of propylene glycol is added as a wetting agent. The mixture was stirred with a mixer at 60 rpm for 20 minutes to prepare copper fine particles for low-temperature firing paste of the present invention in which two types of copper fine particles were uniformly dispersed. The fired film characteristics of the fired paste in which the copper fine particles of the present invention thus prepared were dispersed were evaluated by the following methods. To the prepared copper fine particles, 35 parts by mass of ethylene glycol and 1 part by mass of wax are added, kneaded and adjusted to screen printing ink. Thereafter, a wiring pattern was applied on the epoxy resin substrate by screen printing, and heated at 200 ° C. for 90 minutes in a baking furnace in a mixed gas atmosphere of hydrogen 0.5 L / min + nitrogen 1 L / min to form a copper fired film. As a result, a dense and smooth low-resistance fired film having a specific resistance of 4 × 10 −5 Ω · cm was obtained.
（比較例１）
実施例１で使用した平均粒子径８ｎｍの銅微粒子１００質量部をエチレングリコール６０質量部に混合分散したペーストを作製し、実施例１と同じ方法で性能評価を行なった。エポキシ樹脂基板上にスクリーン印刷で配線パターンを塗布し、水素０．２L/min＋窒素１L/min混合ガス雰囲気の焼成炉で、２００℃で９０分間加熱し、銅焼成膜を形成した結果、焼成膜面に多くの亀裂が認められ、比抵抗も９×１０−４Ω・ｃｍと悪いものであった。焼成条件が２００℃で９０分、水素０．５L/min＋窒素１L/min混合ガス雰囲気では比抵抗５×１０−３Ω・ｃｍの焼成膜、焼成条件が２２０℃で９０分、水素０．５L/min＋窒素１L/min混合ガス雰囲気では比抵抗３×１０−２Ω・ｃｍと悪いものであり、焼成膜面は亀裂が長く、亀裂の幅もより広いものになっていた。
(Comparative Example 1)
A paste was prepared by mixing and dispersing 100 parts by mass of copper fine particles having an average particle diameter of 8 nm used in Example 1 in 60 parts by mass of ethylene glycol, and performance evaluation was performed in the same manner as in Example 1. As a result of applying a wiring pattern on the epoxy resin substrate by screen printing and heating at 200 ° C. for 90 minutes in a firing furnace with a mixed gas atmosphere of hydrogen 0.2 L / min + nitrogen 1 L / min to form a copper fired film. Many cracks were observed on the surface, and the specific resistance was as bad as 9 × 10 −4 Ω · cm. Firing conditions are 200 ° C. for 90 minutes, hydrogen 0.5 L / min + nitrogen 1 L / min in a mixed gas atmosphere, a fired film having a specific resistance of 5 × 10 −3 Ω · cm, firing conditions of 220 ° C. for 90 minutes, and hydrogen 0.5 L In a mixed gas atmosphere of / min + nitrogen 1 L / min, the resistivity was 3 × 10 −2 Ω · cm, which was bad, and the fired film surface had long cracks and wider cracks.
（比較例２）
実施例１１で使用した平均粒子径７５０ｎｍの銅微粒子１００質量部をエチレングリコール２５質量部に混合分散したペーストを作製し、実施例１１と同じ方法で性能評価を行なった。エポキシ樹脂基板上にスクリーン印刷で配線パターンを塗布し、水素０．５L/min＋窒素１L/min混合ガス雰囲気の焼成炉で、２００℃で９０分間加熱し、銅焼成膜を形成した結果、焼成膜が形成されず、比抵抗も１０６Ω・ｃｍより悪いものであった。焼成条件が２６０℃で９０分、水素１L/min＋窒素１L/min混合ガス雰囲気では比抵抗８×１０−３Ω・ｃｍの焼成膜となるが、エポキシ樹脂の物性が劣化し電子機器配線用途には使用できないものであった。
(Comparative Example 2)
A paste was prepared by mixing and dispersing 100 parts by mass of copper fine particles having an average particle diameter of 750 nm used in Example 11 in 25 parts by mass of ethylene glycol, and performance evaluation was performed in the same manner as in Example 11. As a result of applying a wiring pattern on the epoxy resin substrate by screen printing and heating at 200 ° C. for 90 minutes in a baking furnace with a mixed gas atmosphere of hydrogen 0.5 L / min + nitrogen 1 L / min to form a copper fired film. The specific resistance was worse than 10 6 Ω · cm. The firing condition is 260 ° C. for 90 minutes, hydrogen 1 L / min + nitrogen 1 L / min mixed gas atmosphere, but it becomes a fired film with a specific resistance of 8 × 10 −3 Ω · cm. Was unusable.
（比較例３）
実施例５で使用した平均粒子径１３ｎｍの銅微粒子１５質量部と、平均粒子径４２０ｎｍの銅微粒子８５質量部を、エチレングリコール４０質量部に混合分散してスクリーン印刷用ペーストを作製し、実施例５と同じ方法で性能評価を行った。エポキシ樹脂基板上にスクリーン印刷で配線パターンを塗布し、水素０．５L/min＋窒素１L/min混合ガス雰囲気の焼成炉で、２００℃で９０分間加熱し、銅焼成膜を形成した。その結果、焼結ムラの多い焼成膜となり、気孔の多い焼成となり、比抵抗も６×１０−４Ω・ｃｍと悪いものであった。
(Comparative Example 3)
A paste for screen printing was prepared by mixing and dispersing 15 parts by mass of copper fine particles having an average particle diameter of 13 nm and 85 parts by mass of copper fine particles having an average particle diameter of 420 nm used in Example 5 in 40 parts by mass of ethylene glycol. The performance was evaluated by the same method as in No. 5. A wiring pattern was applied on an epoxy resin substrate by screen printing, and heated at 200 ° C. for 90 minutes in a firing furnace in a mixed gas atmosphere of hydrogen 0.5 L / min + nitrogen 1 L / min to form a copper fired film. As a result, a fired film with many sintering unevennesses, a fired with many pores, and a specific resistance of 6 × 10 −4 Ω · cm was bad.
（比較例４）
実施例５で使用した平均粒子径１３ｎｍの銅微粒子８５質量部と、平均粒子径４２０ｎｍの銅微粒子１５質量部を、エチレングリコール６０質量部に混合分散してスクリーン印刷用ペーストを作製し、実施例５と同じ方法で性能評価を行った。エポキシ樹脂基板上にスクリーン印刷で配線パターンを塗布し、水素０．５L/min＋窒素１L/min混合ガス雰囲気の焼成炉で、２００℃で９０分間加熱し、銅焼成膜を形成した。その結果、焼成膜に細かい亀裂が非常に多く認められ、比抵抗も８×１０−４Ω・ｃｍと悪いものであった。
(Comparative Example 4)
A paste for screen printing was prepared by mixing and dispersing 85 parts by mass of copper fine particles having an average particle diameter of 13 nm and 15 parts by mass of copper fine particles having an average particle diameter of 420 nm used in Example 5 in 60 parts by mass of ethylene glycol. The performance was evaluated by the same method as in No. 5. A wiring pattern was applied on an epoxy resin substrate by screen printing, and heated at 200 ° C. for 90 minutes in a firing furnace in a mixed gas atmosphere of hydrogen 0.5 L / min + nitrogen 1 L / min to form a copper fired film. As a result, very many fine cracks were observed in the fired film, and the specific resistance was as bad as 8 × 10 −4 Ω · cm.
本発明の銅微粒子を分散したペーストは、２５０℃以下の焼成温度でも緻密な低抵抗銅焼成膜が得られる。しかも、従来までの１００ｎｍ以下の銅微粒子を分散したペーストより大きな銅微粒子が使用可能となり、より安価で、しかも酸化や凝集の少ない焼成用ペーストとなった。本発明の銅微粒子分散ペーストを利用してスクリーン印刷で樹脂基板上に厚膜低抵抗焼成回路を形成することで、銅箔エッチングによる回路形成より製造プロセスが簡素化でき、大幅なコストダウンと共に、優れた導電性を示すことから印刷プロセスだけで全ての電子回路形成も可能となった。 The paste in which the copper fine particles of the present invention are dispersed can provide a dense low resistance copper fired film even at a firing temperature of 250 ° C. or lower. In addition, larger copper fine particles can be used than the conventional paste in which copper fine particles of 100 nm or less are dispersed, so that the baking paste is cheaper and has less oxidation and aggregation. By forming a thick film low resistance fired circuit on a resin substrate by screen printing using the copper fine particle dispersion paste of the present invention, the manufacturing process can be simplified than circuit formation by copper foil etching, along with a significant cost reduction, Due to the excellent conductivity, all electronic circuits can be formed by only the printing process.
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| JP2015049992A (en) * | 2013-08-30 | 2015-03-16 | 富士フイルム株式会社 | Composition for forming conductive film and method for producing conductive film using the same |
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