JP3697401B2 - Conductor paste and method for producing the same - Google Patents
Conductor paste and method for producing the same Download PDFInfo
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- JP3697401B2 JP3697401B2 JP2001046220A JP2001046220A JP3697401B2 JP 3697401 B2 JP3697401 B2 JP 3697401B2 JP 2001046220 A JP2001046220 A JP 2001046220A JP 2001046220 A JP2001046220 A JP 2001046220A JP 3697401 B2 JP3697401 B2 JP 3697401B2
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G4/00—Fixed capacitors; Processes of their manufacture
- H01G4/002—Details
- H01G4/018—Dielectrics
- H01G4/06—Solid dielectrics
- H01G4/08—Inorganic dielectrics
- H01G4/12—Ceramic dielectrics
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
- H01B1/20—Conductive material dispersed in non-conductive organic material
- H01B1/22—Conductive material dispersed in non-conductive organic material the conductive material comprising metals or alloys
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G13/00—Apparatus specially adapted for manufacturing capacitors; Processes specially adapted for manufacturing capacitors not provided for in groups H01G4/00 - H01G11/00
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Ceramic Engineering (AREA)
- Inorganic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Physics & Mathematics (AREA)
- Dispersion Chemistry (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Conductive Materials (AREA)
- Ceramic Capacitors (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、積層セラミックコンデンサその他のセラミック電子部品（種々の回路素子を包含する。）に導体（内部電極等）を形成する用途に用いられる導体ペースト及びその製造方法に関する。また、当該導体ペーストを使用したセラミック電子部品の製造に関する。
【０００２】
【従来の技術】
近年の電子機器の小型化・精密化に伴い、それに使用される積層セラミックコンデンサセラミック（以下「ＭＬＣＣ」という）等のセラミック電子部品の小型化、高容量化および高性能化が望まれている。
このことを実現するための一つの条件は、そのようなセラミック電子部品に形成される電極や配線等の膜状導体（薄い層状に形成された導体一般をいう。以下同じ。）を、電気的特性や機械的特性を損なうことなく従来よりもさらに薄くセラミック基材（誘電体層）上に形成することである。そして、かかる条件を満足させるための一方策として、そのような膜状導体を形成するための材料である導体ペースト自体の物性及び組成の改良・変更が挙げられる。
【０００３】
例えば、特開平６−２９０９８５号公報や特公平６−５０７０２号公報には、ニッケルを導体形成の主成分とするＭＬＣＣ内部電極形成用途の導体ペーストであって、当該ニッケル粉末に所定の割合で種々の金属酸化物を添加したことを特徴とする導体ペーストが開示されている。かかる導体ペーストによると、焼成後のセラミック電子部品にクラックやデラミネーションといわれる剥離破壊の発生を防止し得ることがこれら公報に記載されている。
また、特開平１１−２１４２４２号公報には、セラミック基材上に形成された薄膜導体のデラミネーションの発生防止及び耐熱衝撃特性（即ち３００℃程度の高温処理（半田付け等）後にも膜状導体にクラックを発生させ難い耐熱特性）の向上を図るべく、導体形成の主成分たるニッケル粉末に、Ｔｉ、Ｚｒ、Ｔａ、Ｈｆ、Ｎｂ又は希土類元素の金属粉末あるいはそれらの炭化物、窒化物、ホウ化物、ケイ化物等から成る粉末を添加したことを特徴とする導体ペーストが開示されている。
また、特開平１０−１４４５６１号公報には、ニッケルを導体形成の主成分とするＭＬＣＣ外部電極（端子電極）形成用途の導体ペーストであって、当該ニッケル粉末に所定の割合で種々の共生地（即ちセラミック基材と同じ無機成分から成る粉末）を添加したことを特徴とする導体ペーストが開示されている。かかる導体ペーストによると、内部電極と外部電極との良好な導電性を確保するとともに、当該外部電極とセラミック基材との密着性に優れたＭＬＣＣが製造し得ることが当該公報に記載されている。
【０００４】
【発明が解決しようとする課題】
しかしながら、上記各公報に記載の導体ペーストはいずれも膜状導体そのものの薄層化に着目して開発されたものではない。このため、これら公報に記載の導体ペーストによって従来よりも比較的薄い膜状導体を形成した場合、従来の比較的厚い膜状導体と同様の電気的特性や機械的特性が保障されるものではない。
すなわち、膜状導体をより一層薄層化する一方で電気的特性（導電性）や機械的特性（接着強度）を実用上充分なレベルに保持するためには、膜状導体を形成する無機・金属系粉末材料（以下「導体形成用粉末材料」という）の充填率（密度）を向上させる必要がある。充分な充填率即ち緻密さが具備されないと、膜状導体の内部構造が粗となり、結果、焼成（焼き付け）時の収縮によって導体内部に電気的断線又は導電率低下の原因となる微小クラックやポアが発生し易くなるからである。さらにはセラミック基材との密着性（接着強度）が低下し、機械的特性を低下させる虞もある。そして、かかる電気的及び機械的特性に関する不具合は、形成する膜状導体の厚みが薄いほどより顕在化するものである。然るに上述の各公報に記載の発明はいずれもかかる導体形成用粉末材料の充填率向上について考慮していない。
【０００５】
そこで、本発明は、上述したような従来の導体ペーストに関する問題点を解決すべく創出されたものであり、その目的とするところは、セラミック基材に導体を形成するための導体ペーストであって、実用上充分なレベルの電気的特性及び／又は機械的特性を維持しつつ従来よりも薄く且つ緻密な膜状導体を形成し得る導体ペーストを提供することである。また、本発明の他の目的は、そのような導体ペーストを製造する方法を提供することである。また、本発明の他の目的は、そのような導体ペーストを用いてセラミック電子部品を製造する方法を提供することである。
【０００６】
【課題を解決するための手段】
本発明者は、ペーストを構成する導体形成用粉末材料の粒度分布を適切化すること即ち導体形成用粉末材料を調製する際の好適な粒度配合の実現によって上記充填率の向上を果たし得ることを見出し、本発明を創出するに至った。
そして、上記目的を達成するべく本発明は、以下のように特定される導体ペースト製造方法を提供する。
すなわち、本発明によって提供される一つの好ましい方法は、導体形成用粉末材料を主成分とする導体ペーストの製造方法であって、その導体形成用粉末材料を調製する工程と、当該粉末材料をビヒクルに分散する工程とを包含する。そして、その導体形成用粉末材料の調製は、当該粉末材料の主体を成す所定の粒度分布を有し且つ平均粒径が０．２〜１．０μｍである略球状のニッケル粉末に対して、導体ペーストをセラミック基材に塗布したときの乾燥塗膜における当該粉末材料の充填率が上記主体を成すニッケル粉末のみから成る場合の導体形成用粉末材料の充填率よりも高くなる分量で、当該ニッケル粉末とは粒度分布が異なり且つその平均粒径が当該ニッケル粉末の平均粒径の１／４〜１／８である一種又は二種以上の略球状の金属粉末及び／又はセラミック粉末を添加することによって行われる。
【０００７】
なお、本発明の特定に関して「平均粒径」というときは、粉末（粉体）を構成する一次粒子の粒子径に基づいて導き出された概算値をいう。典型的には、ＳＥＭ等の電子顕微鏡観察に基づいて概算された平均粒径をいう。
また、本明細書において「略球状の粉末」とは、当該粉末を構成する粒子（一次粒子）の７０wt％以上が球又はそれに類似する形状を有していることをいう。典型的には当該粉末を構成する粒子の７０wt％以上がアスペクト比（即ち粒子の長径に対する短径の比率）８０％以上である場合をいう。また、本明細書において「粒度分布が異なる」とは、比較する二つの粉末（二成分）間において構成粒子の大部分（典型的には粉末の７０wt％以上）の粒子径が相互に異なっている（重複しない）ことをいう。具体的には、当該二つの粉末各々の粒度分布曲線（一般に横軸が粒子径を示し縦軸が粒子存在割合を示す座標平面上に表される）が横軸方向に実質的に重ならないか又はその一端部のみが重なる場合をいう。従って、本明細書において定義される相互に粒度分布が異なる二つの粉末を混合した場合には、典型的には、その粒度分布曲線において二つのピークが相互に離隔した所定の部位（典型的には混合前の各粉末の平均粒径に対応する部位）にみられる。
【０００８】
かかる導体ペースト製造方法では、導体形成用粉末材料の主体を成す略球状の導電性金属粉末（以下「主金属粉末」という）として所定の粒度分布を有し且つ平均粒径が０．２〜１．０μｍである略球状のニッケル粉末を採用し、当該ニッケル粉末に対して、異なる粒度分布を有し且つその平均粒径が主金属粉末（ニッケル粉末）の１／４〜１／８である金属粉末及び／又はセラミック粉末（以下これら微細な粉末を「充填補助微細粉末」と総称する）を添加することによって、導体形成用粉末材料から成る上記塗膜中における充填率を向上することができる。このことにより、本製造方法によって得られた導体ペーストによると、セラミック基材上に充填性の高い塗膜すなわち緻密な構造の膜状導体を形成することができる。このため、本製造方法によって得られた導体ペーストは、従来よりも薄い膜状導体の形成を電気的特性及び／又は機械的特性を損なうことなく実現することができる。
【０００９】
また、上記製造方法を基礎として、本発明の他の側面として以下のような導体ペーストが提供される。すなわち、本発明によって提供される導体ペーストの一つは、導体形成用粉末材料を主成分とする導体ペーストであって、その導体形成用粉末材料は、所定の粒度分布を有し且つ平均粒径が０．２〜１．０μｍである略球状のニッケル粉末を主体とするものである。そして、本導体ペーストをセラミック基材に塗布して得られた乾燥塗膜における当該導体形成用粉末材料の充填率が当該ニッケル粉末のみから成る導体形成用粉末材料の充填率よりも高くなる分量で、当該ニッケル粉末とは粒度分布が異なり且つその平均粒径が当該ニッケル粉末の平均粒径の１／４〜１／８である一種又は二種以上の略球状の金属粉末及び／又はセラミック粉末が当該主体たるニッケル粉末に添加されて構成されている。
【００１０】
かかる構成の本発明の導体ペーストでは、主金属粉末（ニッケル粉末）に対して充填補助微細粉末が充填率向上に寄与する限度を越えない量添加されている。このことにより、従来の主金属粉末単独あるいは当該粉末とその他の金属又はセラミック粉末（本発明のように粒度配合や平均粒径の最適化を施していない）との混合物から成る膜状導体と比較して、電気的特性や機械的特性を維持しつつ、より薄い膜状導体をセラミック基材上に形成することができる。従って、本発明の導体ペーストによると、ＭＬＣＣその他のセラミック電子部品の小型化、高容量化および高性能化といった要求を高いレベルで充足し得る薄膜状導体をコスト面で優れる卑金属（Ｎｉ）で形成することができる。このため、セラミック電子部品の小型（スリム）化及び低価格化を図ることができる。
【００１１】
また、本発明によって提供される導体ペーストの他の一つは、導体形成用粉末材料を主成分とする導体ペーストであって、その導体形成用粉末材料は、所定の粒度分布を有し且つ平均粒径が０．２〜１．０μｍである略球状のニッケル粉末を主体とするものであり、そのニッケル粉末とは粒度分布が異なり且つその平均粒径が上記ニッケル粉末の平均粒径の１／４〜１／８である略球状のニッケル粉末が上記平均粒径０．２〜１．０μｍのニッケル粉末に添加されて構成されている。そして、上記平均粒径０．２〜１．０μｍのニッケル粉末の含有率は導体形成用粉末材料全体の７５wt％以上であり、上記１／４〜１／８の平均粒径のニッケル粉末の含有率は導体形成用粉末材料全体の２５wt％以下であることを特徴とする。
かかる構成の導体ペーストでは、主金属粉末（ニッケル粉末）と実質的に同一組成（従って微量成分の有無やその質的相違等を許容する趣旨である）の微細金属粉末（ニッケル粉末）が充填補助微細粉末として適量含まれている。このことによって、本構成の導体ペーストによると、高い電気的特性（導電性）を有する薄膜状の導体を形成することができる。
【００１２】
また、本発明によって提供される導体ペーストとして好ましい他のものは、導体形成用粉末材料を主成分とする導体ペーストであって、その導体形成用粉末材料は、所定の粒度分布及び平均粒径を有する略球状のニッケル粉末を主体とするものである（以下「Ｎｉペースト」という）。そして、本Ｎｉペーストは、当該ニッケル粉末とは粒度分布が異なり且つその平均粒径が当該ニッケル粉末の平均粒径の略４分の１以下である一種又は二種以上の略球状の金属粉末及び／又はセラミック粉末が当該ニッケル粉末に添加されている。而して、上記ニッケル粉末に対して添加された上記金属粉末及び／又はセラミック粉末の容積（分量）は、チタン酸バリウム粉末換算で示される。すなわち、当該ニッケル粉末の平均粒径の略４分の１以下の平均粒径を有するチタン酸バリウム粉末であって当該ニッケル粉末の３０wt％以下となる重量（質量）に相当するチタン酸バリウム粉末の容積として規定される。
【００１３】
上記構成のＮｉペーストでは、主金属粉末たるＮｉ粉末に対して、チタン酸バリウム粉末換算で上記分量となるように充填補助微細粉末としての金属粉末及び／又はセラミック粉末（即ちチタン酸バリウムはその典型）を添加する。かかる容積比に基づく粒度配合によってＮｉ粉末を主体とする導体形成用材料の充填率を向上させ得、延いてはセラミック基材に形成されるＮｉ導体の緻密化を実現することができる。このため、本発明のＮｉペーストによると、ＭＬＣＣその他のセラミック電子部品の小型化、高容量化および高性能化に係る要求を高いレベルで充足し得る薄膜状の導体をコスト面で優れる卑金属（Ｎｉ）で形成することができる。このため、セラミック電子部品の小型（スリム）化及び低価格化を図ることができる。
【００１４】
また、本発明のＮｉペーストとして好ましいものでは、上記導体形成用粉末材料の主体を成す略球状のニッケル粉末の平均粒径は０．２〜１．０μｍであり、上記金属粉末及びセラミック粉末として、当該ニッケル粉末の平均粒径の略４分の１以下の平均粒径を有する導電性金属粉末及びチタン酸バリウム系の誘電体粉末を含有することを特徴とする。
かかる構成のＮｉペーストによると、セラミック基材（特にチタン酸バリウムを含有するもの）に対する接着強度が高い機械的強度に優れる薄膜状のＮｉ導体を形成することができる。また、本構成のＮｉペーストによると、Ｎｉ粉末と導電性金属粉末（典型的には微細なＮｉ粉末）との組み合わせによって導電性等の電気的特性に優れる高密度薄膜状Ｎｉ導体を形成することができる。
【００１５】
また、本発明の他の側面として、上記ペースト製造方法によって得られた導体ペースト（典型例は上述の各導体ペースト）を使用することを特徴とする、ＭＬＣＣその他のセラミック電子部品の製造方法を提供する。典型的には、本製造方法では、上記本発明に係る導体ペーストをセラミック基材に塗布する工程及び当該塗布されたペースト主成分（即ち高充填された導体形成用粉末材料）を焼成する工程とを包含する。この製造方法によると、小型化、高容量化および高性能化に対応した電気的特性や機械的特性に優れる薄膜状導体が形成されたＭＬＣＣその他のセラミック電子部品を製造・提供することができる。
また、本発明の他の側面として、本発明の導体ペーストを調製するための導体形成用粉末材料及びその製造方法が提供される。その典型例は、上述した導体ペースト製造方法に使用される導体形成用粉末材料であり、さらには上述した各導体ペーストの主要構成要素たる導体形成用粉末材料であって各請求項に記載のように特定される導体形成用粉末材料及びその製造方法である。
【００１６】
【発明の実施の形態】
以下、本発明の好適な実施形態を説明する。
【００１７】
本発明の導体ペーストの主成分たる導体形成用粉末材料としては、スクリーン印刷法その他の手法によってセラミック基材（アルミナ基板、ガラス基板等）に塗布されたペースト由来の乾燥塗膜又はその焼成体における導体形成用粉末材料の充填率（最大充填率）を向上させるべく、所定の粒度分布及び平均粒径を有する主金属粉末に対し、異なる粒度分布であり且つ平均粒径が当該主金属粉末の４分の１以下（好ましくは４分の１〜８分の１、特には６分の１〜８分の１程度）である略球状の充填補助微細粉末が所定量添加されたものである。
【００１８】
例えば、製造されるＭＬＣＣ等のセラミック電子部品の低コスト化を図るうえで本発明をＮｉ等の卑金属を主成分とする導体ペースト及びその調製に適用する意義は大きい。
また、電気的特性（導電性等）や機械的特性（接着強度等）を損なうことなく従来よりも比較的薄い膜状導体を形成するという観点からは、サブミクロンオーダー（好ましくは０．１〜１．０μｍ）の平均粒径を有する導電性金属粉末が主金属粉末として特に好適である。例えば、本発明のＮｉペーストをＭＬＣＣの内部電極形成等の用途に使用する場合、主金属粉末たるＮｉ粉末の平均粒径は０．２〜１．０μｍであることが好ましく、０．４〜０．６μｍ（例えば０．５μｍ）であることが特に好ましい。また、ニッケル粉末の比表面積（ＢＥＴに基づく）は、１〜１０ｍ２／ｇであることが好ましい。
【００１９】
一方、そのような主金属粉末に添加される充填補助微細粉末としては、使用する主金属粉末（導体形成用粉末材料）の充填率向上に寄与し得る、当該主金属粉末と粒度分布が異なり且つ平均粒径が当該主金属粉末のそれの４分の１以下（好ましくは１／４〜１／８、特には１／６〜１／８）程度である略球状の微細粉末であればよく、特定の金属粉末やセラミック粉末に限定されるものではない。使用する用途に応じて異なり得るが、例えばかかる充填補助微細粉末として種々の誘電体粉末や金属酸化物の球状微細粉末を用いることができる。なお、かかる充填補助微細粉末としては、本発明の導体ペーストの導電性（低抵抗率）、半田濡れ性、半田耐熱性、接着強度等を著しく損なわないものが好ましい。例えば、セラミック粉末としては、ガラス粉末、無機酸化物（金属酸化物）等が挙げられる。例えば、金属酸化物としては、Ａｌ、Ｚｒ、Ｔｉ、Ｓｉ、Ｐｂ、Ｆｅ、Ｗ、Ｍｎ、Ｂｉ、Ｎｂ、Ｔａ、Ｍｏ、Ｃａ、Ｓｒ、Ｂａ、Ｍｇ等の酸化物あるいは高融点の希土類（即ちＳｃ、Ｙ、Ｌａ、Ｃｅ、Ｐｒ、Ｎｄ、Ｐｍ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｙｂ、Ｌｕ）酸化物が挙げられる。また、誘電体粉末としては、使用するセラミック基材との共通材料、例えばチタン酸バリウム系の酸化物、窒化珪素、窒化アルミニウム等の窒化物、及び炭化珪素、炭化チタン等の炭化物、並びにこれらの混合物等が挙げられる。上述のようなセラミック粉末（上記金属酸化物を包含する）を添加することにより、本発明の導体ペーストから形成された膜状導体の耐熱性や接着強度等をさらに向上させることができる。
【００２０】
また、充填補助微細粉末として使用し得る金属粉末には、主金属粉末と実質的に同一組成である金属粉末（典型的には同一又は類似の原料から構成され、比重が主金属粉末と同一又は近似する微細な金属粉末であって粒度分布及び平均粒径が主金属粉末とは異なる球状粉末）が包含される。かかる平均粒径及び粒度分布の相違する実質同一組成の金属粉末を組み合わせる（混合する）ことによって、当該金属粉末が有する電気的特性その他の物性を損なうことなく、主金属粉末単独から成る粉末材料と比較して、より緻密で機械的強度や導電性に優れる膜状導体を形成することができる。
なお、使用する充填補助微細粉末の粒度分布及び平均粒径は、対象となる主金属粉末の粒度分布及び平均粒径に従って規定される。例えば、平均粒径が０．５μｍの金属粉末を主金属粉末とする場合には、０．１２５μｍ以下の平均粒径のものを充填補助微細粉末として使用することができる。
【００２１】
ところで、充填性向上の観点からは、主金属粉末及び充填補助微細粉末として使用する粉末材料は粒度分布のシャープなものが好ましい。シャープな（狭い）粒度分布のものほど適正な粒度配合をより正確に行うことができるからである。特に限定するものではないが、例えば平均粒径が０．５μｍ程度の金属粉末を主金属粉末とする場合には、全体の略７０％又はそれ以上の粒子が当該平均粒径の６０〜１４０％の粒径範囲（好ましくは当該平均粒径の８０〜１２０％の粒径範囲）、具体的には全体の略７０％又はそれ以上の粒子が粒径０．３〜０．７μｍ（好ましくは粒径０．４〜０．６μｍ）の範囲に属するようなシャープな粒度分布のものが望ましい。また、平均粒径が１．０μｍ程度の金属粉末を主金属粉末とする場合には、全体の略７０％又はそれ以上の粒子が粒径０．６〜１．４μｍ（好ましくは粒径０．８〜１．２μｍ）の範囲に属するようなシャープな粒度分布のものが望ましい。
一方、上記平均粒径が０．５μｍ程度の主金属粉末を用いる場合の充填補助微細粉末としては０．１２５μｍ以下（好ましくは０．１２５〜０．０６２５μｍ、より好ましくは０．０８３〜０．０６２μｍ）の平均粒径のものを使用することができるが、全体の略７０％又はそれ以上の粒子が当該平均粒径の６０〜１４０％程度の粒径範囲（好ましくは８０〜１２０％程度の粒径範囲）、具体的には平均粒径が略０．１２５μｍであって、全体の略７０％又はそれ以上の粒子が粒径０．０７５〜０．１５μｍ（好ましくは粒径０．１〜０．１５μｍ）の範囲に属するようなシャープな粒度分布のものが望ましい。同様に、上記平均粒径が１．０μｍ程度の主金属粉末を用いる場合の充填補助微細粉末としては０．２５μｍ以下（好ましくは０．２５〜０．１２５μｍ、より好ましくは０．２５〜０．１６７μｍ）の平均粒径のものを使用することができるが、当該平均粒径の６０〜１４０％程度の粒径範囲（好ましくは当該平均粒径の８０〜１２０％程度の粒径範囲）、具体的には全体の略７０％又はそれ以上の粒子が粒径０．０７５〜０．１７５μｍ（好ましくは粒径０．１〜０．１５μｍ）の範囲に属するようなシャープな粒度分布のものが望ましい。
【００２２】
なお、本発明の実施にあたっては、主金属粉末及び充填補助微細粉末のいずれも略球状である限り、それらの製造方法を制限するものではない。例えば、Ｎｉその他の球状金属粉末やシリカ、アルミナ等の球状セラミック粉末は、従来知られた方法により製造されたものを適宜入手して用いればよい。例えば、球状シリカその他のセラミック微粒子を製造する周知方法の一つとしていわゆる噴霧乾燥法が挙げられる。また、Ｎｉ粉末等の金属粉末は、噴霧熱分解法やいわゆるＣＶＤ法によって製造することができる。本発明の実施にあたっては、これら既知の方法によって製造された球状粉末を適宜入手（製造又は購買）して用いることができる。
【００２３】
次に、本発明の導体ペーストの主成分である導体形成用粉末材料の調製について説明する。この粉末材料は、その主成分たる主金属粉末に上述したような性状の充填補助微細粉末を添加することによって構成される粉末材料である。而して、かかる充填補助微細粉末の添加量については次の条件を満たす範囲内で設定されればよい。すなわち、本発明の導体ペーストをセラミック基材に塗布した際に得られる乾燥塗膜における当該粉末材料の充填率（延いては焼成後の膜状導体の緻密さ）が、主金属粉末のみから成る導体形成用粉末材料のペーストをセラミック基材に塗布した際に得られる乾燥塗膜における当該粉末材料の充填率よりも高くなるような範囲で添加量を設定すればよい。概して、使用する主金属粉末と充填補助微細粉末との間に上述したよう好適な平均粒径及び粒度分布の差異がある場合には、所定の添加量に達するまでは当該充填補助微細粉末の添加量に応じて上記充填率が向上する。従って、本発明の実施にあたっての充填補助微細粉末の添加量（含有量）は、当該所定の添加量に至るまでの間であればよく（勿論、当該所定の添加量を越える添加量でも、上述したように主金属粉末のみから成る導体形成用粉末材料のペーストを使用した場合より乾燥塗膜における粉末材料の充填率が高くなる範囲であればよい。）、過度な実験を要することなく決定することができる。
特に限定するものではないが、充填補助微細粉末として主金属粉末と実質的に同一組成の略球状の金属粉末を使用する場合には、その含有率が導体形成用粉末材料全体の２５wt％以下となる量、好ましくは導体形成用粉末材料全体の５〜２０wt％（特に好ましくは１５〜２０wt％）となる量を添加するとよい。導体形成用粉末材料全体の２５wt％よりも多すぎる添加量の場合には、主金属粉末の粒子相互の間隙を上回る容積量の充填補助微細粉末が添加される虞があり好ましくない。当該間隙に入りきれない充填補助微細粉末の存在によって充填率が逆に低下する場合があるからである（後述の実施例参照）。
なお、上記好適な添加量の上限は、相互に粒径の異なる二成分系の最大充填率に係る理論値よりも高く、当該理論値よりも比較的多めの添加量が本発明の実施にあたって好ましいことを示すものである。なお、ここで二成分系の最大充填率に係る理論値（理論添加量）は以下のように求められる。
すなわち、面心立方格子の各格子点に半径ｒ１の球（一次球）を配置した立方最密充填構造においては、充填率が７４．０５％であり空隙率が２５．９５％となる。一方、当該立方最密充填構造を構成する一次球の隙間（即ち相互に隣接する一次球から成る正四面体の重心位置）に、当該隙間に配置し得る最大級の微粒子、即ち当該重心位置を中心にして隣接する各一次球に接する径の微粒子（充填補助微粒子）を配置した場合、その充填率は８１．００％となり、空隙率は１９．００％となる。つまり、当該充填率（８１．００％）から立方最密充填構造の充填率（７４．０５％）を差し引いた分（６．９５％）が上記充填補助微粒子の容積となる。このことより、主金属粉末（上記一次球に相当）１００ｃｍ3に対する充填補助微細粉末（上記充填補助微粒子に相当）の理論添加量は、７４．０５：６．９５≒１００：９．３９に基づき９．３９ｃｍ3と導き出される。
【００２４】
また、本発明をＮｉペーストに適用する場合、主金属粉末たるＮｉ粉末（好ましくは平均粒径が０．２〜１．０μｍのＮｉ粉末、特に好ましくは平均粒径が略０．５μｍのＮｉ粉末）に対する充填補助微細粉末の添加量は、好ましくは、当該Ｎｉ粉末の平均粒径の略４分の１以下となるサイズの平均粒径を有するチタン酸バリウム粉末換算での容積として規定することができる。例えば常温常圧下において平均粒径が０．５μｍのＮｉ粉末１００ｇ（１ｃｍ3≒８．９ｇ、従って１００ｇ≒１１．２ｃｍ3）に対して添加される充填補助微細粉末の好適な添加量は、当該Ｎｉ粉末の３０wt％以下に相当する重量（即ち３０ｇ以下）のチタン酸バリウム粉末（１ｃｍ3≒６．０ｇ）が占める容量（例えば３０ｇのチタン酸バリウム粉末換算の場合で５．０ｃｍ３）として一般化することができる。このチタン酸バリウム換算によって、本発明のＮｉペーストに用いられる導体形成用粉末材料では、充填補助微細粉末の種類に拘わらず（即ち当該粉末の比重の大小に拘わらず）適切な添加量（容積）を過大な実験を繰返し行うことなく決定することができる。
【００２５】
而して、本発明に係る導体形成用粉末材料は、所定量の主金属粉末と適切な添加量の充填補助微細粉末とを混合することによって容易に得ることができる。なお、かかる混合処理はビヒクルに粉末材料を分散する前に独立して行ってもよいし、あるいは、当該ビヒクルへの分散と併せて行ってもよい（即ちこの場合は導体形成用粉末材料の調製工程と当該粉末材料のビヒクルへの分散工程が同時に行われる）。
なお、かかる混合方法としては従来から通常用いられている粉末混合手段を特に制限なく利用することができる。例えば、種々のミキサーやミル等（例えばプラネタリーミル）を使用してこれら粉末を撹拌・混合するとよい。このようにして調製された導体形成用粉末材料では、典型的には、その粒度分布曲線に二つ又はそれ以上のピークが認められる。このことは、本発明に係る導体形成用粉末材料が相互に粒度分布が異なる二つ又はそれ以上の粉末を混合した多成分系材料であることを示す一つの指標となり得る。
【００２６】
次に、本発明の導体ペーストを構成する副成分について説明する。本発明の導体ペーストは、充填率向上に寄与する上記導体形成用粉末材料の他に、従来の導体ペーストと同様の物質を副成分として含有し得る。
例えば、本発明の導体ペーストの必須的副成分として、上記導体形成用粉末材料を分散させておく有機媒質（ビヒクル）が挙げられる。本発明の実施にあたっては、かかる有機ビヒクルは導体形成用粉末材料を分散させておくものであればよく、従来の導体ペーストに用いられているものを特に制限なく使用することができる。例えば、エチルセルロース等のセルロース系高分子、エチレングリコール及びジエチレングリコール誘導体、トルエン、キシレン、ミネラルスピリット、ブチルカルビトール、ターピネオール等の高沸点有機溶媒が挙げられる。
【００２７】
また、本発明の導体ペーストには、当該ペーストの導電性（低抵抗率）、半田濡れ性、半田耐熱性、接着強度等を著しく損なわない限りにおいて種々の有機添加剤を副成分として含ませることができる。例えば、かかる有機添加剤としては各種の有機バインダー（上記ビヒクルと重複しても良いし別途異なるバインダーを添加しても良い）やセラミック基材との密着性向上を目的としたシリコン系、チタネート系及びアルミニウム系等の各種カップリング剤等が挙げられる。
有機バインダーとしては、例えば、アクリル樹脂、エポキシ樹脂、フェノール樹脂、アルキド樹脂、セルロース系高分子、ポリビニルアルコール等をベースとするものが挙げられる。本発明の導体ペーストに良好な粘性及び塗膜（基材に対する付着膜）形成能を付与し得るものが好適である。また、本発明の導体ペーストに光硬化性（感光性）を付与したい場合には、種々の光重合性化合物及び光重合開始剤を適宜添加してもよい。
【００２８】
なお、上記の他にも本発明の導体ペーストには、必要に応じて界面活性剤、消泡剤、可塑剤、増粘剤、酸化防止剤、分散剤、重合禁止剤等を適宜添加することができる。これら添加剤は、従来の導体ペーストの調製に用いられ得るものであればよく、詳細な説明は省略する。
【００２９】
次に、本発明の導体ペーストの調製について説明する。本発明の導体ペーストは従来の導体ペーストと同様、典型的には上記導体形成用粉末材料と有機媒質（ビヒクル）を混和することによって容易に調製することができる。なお、主金属粉末と充填補助微細粉末は、別々にビヒクルに添加してもよいし、予めこれらを混合して得たものを添加してもよい。このとき、必要に応じて上述したような添加剤を添加・混合するとよい。例えば、三本ロールミルその他の混練機を用いて、導体形成用粉末材料及び各種添加剤を有機ビヒクルとともに所定の配合比で直接混合し、相互に練り合わせる（混練する）ことにより、本発明の導体ペーストが調製され得る。
【００３０】
次に、本発明の導体ペーストを用いた膜状導体形成（即ちセラミック電子部品の製造）に係る好適例について説明する。本発明の導体ペーストは、セラミック製の基材（基板）上に配線、電極等の膜状導体を形成するのに従来用いられてきた導体ペーストと同様に取り扱うことができ、従来公知の方法を特に制限なく採用することができる。典型的には、スクリーン印刷法やディスペンサー塗布法等によって、所望する形状・厚みとなるようにして導体ペーストをセラミック基材（基板）に塗りつける。次いで、好ましくは乾燥後、加熱器中で適当な加熱条件（最高焼成温度が概ね６００〜１３００℃、典型的には７００〜１０００℃であるが、Ｎｉペーストでは好ましくは１１００〜１３００℃）で所定時間加熱することによって、その塗りつけられたペースト成分を焼成（焼き付け）・硬化させる。この一連の処理を行うことによって、目的とする薄い膜状の導体（配線、電極等）が形成されたセラミック電子部品（例えばＭＬＣＣの電極やハイブリッドＩＣ、マルチチップモジュールの構築用セラミック配線基板）が得られる。而して、当該セラミック電子部品を組み立て材料として用いつつ従来公知の構築方法を適用することによってさらに高度なセラミック電子部品（例えばハイブリッドＩＣやマルチチップモジュール）を得ることができる。なお、かかる構築方法自体は、特に本発明を特徴付けるものではないため、詳細な説明は省略する。
なお、用途限定を意図するものではないが、上述のとおり、本発明の導体ペーストによると従来のものよりも緻密性に優れる膜状導体を形成することができる。このため、本発明の導体ペーストは、膜厚が１０〜３０μｍ程度の導体の形成のみならず、１０μｍ以下の比較的薄い膜厚の導体を形成する用途にも好適である。例えば、ＭＬＣＣ用Ｎｉ内部電極として好ましい１．５〜３μｍ厚の緻密性に優れる膜状導体を形成することができる。
【００３１】
【実施例】
以下、本発明に関するいくつかの実施例を説明するが、本発明をかかる実施例に示すものに限定することを意図したものではない。
【００３２】
＜実施例１＞
実施例１としてチタン酸バリウム粉末を充填補助微細粉末とするＮｉペーストを調製した。すなわち、平均粒径が約０．４μｍのＮｉ粉末１００ｇに、平均粒径が約０．１μｍのチタン酸バリウム粉末を当該Ｎｉ粉末の１０wt％に相当する量（１０ｇ）添加し、撹拌・混合することによって本実施例に係る導体形成用粉末材料を調製した。
次に、上記得られた導体形成用粉末材料を使用してＮｉペーストを調製した。すなわち、最終的なペースト濃度（重量比）が導体形成用粉末材料５５wt％（Ｎｉ粉末５０wt％、チタン酸バリウム粉末５wt％）および残部が溶剤（４２wt％）とバインダー（樹脂：３wt％）となるようにこれら材料を秤量し、三本ロールミルを用いて混練した。このことによって、本実施例に係るＮｉペーストを調製した。
【００３３】
＜比較例１＞
使用したチタン酸バリウム粉末の平均粒径が約０．２μｍであることを除いて、上記実施例１と同様の処理を行い、本比較例に係るＮｉペーストを調製した。
【００３４】
＜比較例２＞
チタン酸バリウム粉末を添加することなく上記Ｎｉ粉末をそのまま導体形成用粉末材料として使用して本比較例に係るＮｉペーストを調製した。なお、最終的なペースト固形分濃度は、実施例１と同じである。
【００３５】
＜試験例１：塗膜密度の評価（その１）＞
次に、実施例１並びに比較例１及び２に係るＮｉペーストを用いてガラス基材上に塗膜をそれぞれ形成し、その塗膜密度（ｇ／ｃｍ３）を測定した。すなわちガラス基材（厚みが約１．３ｍｍのソーダライム製基板）の表面に一般的なスクリーン印刷法に基づいて各導体ペーストを塗布し、所定の膜厚の塗膜を形成した。続いて、遠赤外線乾燥機を用いて１００℃で１５分間の乾燥処理を施した。この乾燥処理によって塗膜から溶剤が揮発し、導体形成用粉末材料から成る乾燥塗膜が得られた。次いで、得られた乾燥塗膜について塗膜重量と塗膜厚みを測定して塗膜密度を算出した。結果を表１に示す。
【００３６】
【表１】
表１から明らかなように、実施例１に係る導体ペーストから得られた乾燥塗膜の密度は、比較例１及び比較例２の各導体ペーストから得られた乾燥塗膜の密度を大幅に上回った。この結果は、主金属粉末たるＮｉ粉末に対して平均粒径が当該粉末の４分の１以下であるチタン酸バリウム粉末を適量添加・混合することによって、乾燥塗膜を構成する導体形成用粉末材料の充填率を向上し得、延いては膜状導体の構造を緻密化し得ることを示すものである。これに対し、平均粒径が上記Ｎｉ粉末の４分の１を上回るような比較的粒径の大きいチタン酸バリウム粉末を添加・混合して得た導体ペースト（比較例１）では、かかる充填率の向上即ち乾燥塗膜の高密度化を実現することができないばかりでなく、チタン酸バリウム粉末未添加のもの（比較例２）よりも却って充填率を減少させてしまうことが確認された（表１参照）。
【００３８】
＜実施例２＞
実施例２として実質的に同一組成のＮｉ粉末を充填補助微細粉末とするＮｉペーストを調製した。すなわち、平均粒径が約０．５μｍのＮｉ粉末（以下「主Ｎｉ粉末」という。）１００ｇに対し、平均粒径が約０．１μｍのＮｉ粉末（以下「副Ｎｉ粉末」という。）を９．４ｇ添加し、撹拌・混合することによって本実施例に係る導体形成用粉末材料を調製した。すなわち、本実施例に係る導体形成用粉末材料の副Ｎｉ粉末（即ち上記充填補助微細粉末に相当する金属粉末）の含有率は導体形成用粉末材料全体の８．６wt％である。次に、この導体形成用粉末材料を使用して、上記実施例１と同様の混練処理を行い、本実施例に係るＮｉペーストを調製した。
【００３９】
＜実施例３＞
主Ｎｉ粉末１００ｇに対し副Ｎｉ粉末を１４．８ｇ添加し、撹拌・混合することによって本実施例に係る導体形成用粉末材料を調製した。すなわち、本実施例に係る導体形成用粉末材料の副Ｎｉ粉末の含有率は導体形成用粉末材料全体の１２．９wt％である。次に、この導体形成用粉末材料を使用して、上記実施例１と同様の混練処理を行い、本実施例に係るＮｉペーストを調製した。
【００４０】
＜実施例４＞
主Ｎｉ粉末１００ｇに対し副Ｎｉ粉末を２０．８ｇ添加し、撹拌・混合することによって本実施例に係る導体形成用粉末材料を調製した。すなわち、本実施例に係る導体形成用粉末材料の副Ｎｉ粉末の含有率は導体形成用粉末材料全体の１７．２wt％である。次に、この導体形成用粉末材料を使用して、上記実施例１と同様の混練処理を行い、本実施例に係るＮｉペーストを調製した。
【００４１】
＜比較例３＞
主Ｎｉ粉末１００ｇに対し副Ｎｉ粉末を１００ｇ添加し、撹拌・混合することによって本比較例に係る導体形成用粉末材料を調製した。すなわち、本比較例に係る導体形成用粉末材料の副Ｎｉ粉末の含有率は導体形成用粉末材料全体の５０wt％である。次に、この導体形成用粉末材料を使用して、上記実施例１と同様の混練処理を行い、本比較例に係るＮｉペーストを調製した。
【００４２】
＜比較例４＞
副Ｎｉ粉末を添加することなく主Ｎｉ粉末（比較例２で使用したものとは異なる）をそのまま導体形成用粉末材料として使用し、上記実施例１と同様の混練処理を行い、本比較例に係るＮｉペーストを調製した。
【００４３】
＜試験例２：塗膜密度の評価（その２）＞
次に、実施例２〜４並びに比較例３及び４に係るＮｉペーストを用いて、上記試験例１と同様の条件で塗膜密度評価試験を行った。結果を表２に示す。
【００４４】
【表２】
表２から明らかなように、実施例２〜４に係るＮｉペーストそれぞれから得られた各乾燥塗膜の密度は、いずれも比較例３及び比較例４の各Ｎｉペーストから得られた乾燥塗膜の密度を上回った。この結果は、主Ｎｉ粉末に対して平均粒径が当該粉末の４分の１以下である副Ｎｉ粉末を適量添加・混合することによって、乾燥塗膜を構成する導体形成用粉末材料（即ちＮｉ粉末）の充填率を向上し得、延いては膜状Ｎｉ導体の構造を緻密化し得ることを示すものである。これに対し、主Ｎｉ粉末に対して過剰量の副Ｎｉ粉末を添加・混合して得たＮｉペースト（比較例３）では、かかる充填率の向上即ち乾燥塗膜の高密度化を実現することができないばかりでなく、副Ｎｉ粉末未添加のもの（比較例４）よりも却って充填率を減少させてしまうことが確認された（表２参照）。
【００４６】
＜試験例３：塗膜密度の評価（その３）＞
チタン酸バリウム粉末（平均粒径約０．１μｍ）をセラミック添加材（即ち本発明に係る充填補助微細粉末）として使用し、その添加量が相互に異なるＮｉペーストをいくつか調製し、その添加量と塗膜密度との関係を調べた。すなわち、平均粒径が約０．４μｍのＮｉ粉末１００ｇに対して、上記チタン酸バリウム粉末を０ｇ、７．５ｇ、１０ｇ、１２．５ｇ、１５ｇ、１７．５ｇ、２０ｇまたは３０ｇ添加し撹拌・混合することによって、チタン酸バリウム粉末添加量が異なる計８種類の導体形成用粉末材料を調製した。次いで、上記実施例１と同様の混練処理を行い、これら導体形成用粉末材料からそれぞれＮｉペーストを調製した。次いで、上記試験例１と同様の条件で各Ｎｉペーストの塗膜密度評価試験を行った。結果を表３及び図１に示す。
【００４７】
【表３】
表３及び図１に示すように、本試験例で作成したセラミック添加材入りＮｉペーストから形成された乾燥塗膜は、セラミック添加材（チタン酸バリウム粉末）を全く添加していないＮｉペーストから形成された乾燥塗膜よりも高密度であった。特に、Ｎｉ１００ｇに対してセラミック添加材を１０〜２０ｇ添加して得たＮｉペーストでは、乾燥塗膜の高密度化が顕著であった。
【００４９】
【発明の効果】
以上の実施例からも明らかなように、本発明の導体形成用粉末材料及びそれを主成分とする導体ペーストによると、セラミック基材上の乾燥塗膜を構成する導体形成用粉末材料の充填率を従来よりも向上させることができる。このため、本発明の導体ペーストをＭＬＣＣ等のセラミック電子部品の膜状導体の形成に適用することによって、導電性等の電気的特性ならびに接着強度等の機械的特性に優れる緻密構造の薄い膜状導体の形成されたセラミック電子部品を製造することができる。
【図面の簡単な説明】
【図１】 セラミック添加材量と乾燥塗膜密度との関係を示すグラフである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a conductor paste used for forming a conductor (such as an internal electrode) on a multilayer ceramic capacitor or other ceramic electronic component (including various circuit elements) and a method for manufacturing the same. Moreover, it is related with manufacture of the ceramic electronic component using the said conductor paste.
[0002]
[Prior art]
With the recent miniaturization and refinement of electronic equipment, there is a demand for miniaturization, high capacity and high performance of ceramic electronic components such as multilayer ceramic capacitor ceramic (hereinafter referred to as “MLCC”) used therein.
One condition for realizing this is that a film-like conductor (such as a conductor generally formed in a thin layer; the same shall apply hereinafter) such as an electrode or a wiring formed in such a ceramic electronic component is electrically used. It is to form on a ceramic substrate (dielectric layer) thinner than before without impairing characteristics and mechanical properties. As one measure for satisfying such conditions, improvement and change of physical properties and composition of the conductor paste itself, which is a material for forming such a film conductor, can be mentioned.
[0003]
For example, Japanese Patent Application Laid-Open No. 6-290985 and Japanese Patent Publication No. 6-50702 are conductor pastes for MLCC internal electrode formation using nickel as a main component for conductor formation, and various kinds of nickel paste at a predetermined ratio. A conductor paste characterized by adding a metal oxide is disclosed. It is described in these publications that according to such a conductor paste, it is possible to prevent the occurrence of peeling failure called cracks and delamination in the fired ceramic electronic component.
Japanese Patent Application Laid-Open No. 11-214242 discloses that a thin film conductor formed on a ceramic substrate is prevented from delamination and has a thermal shock resistance (that is, after a high temperature treatment (soldering, etc.) of about 300 ° C. In order to improve the heat resistance characteristics, which are difficult to generate cracks), Ti, Zr, Ta, Hf, Nb or rare earth metal powders or their carbides, nitrides, borides are used as nickel powder as the main component of conductor formation. A conductor paste characterized by adding a powder made of silicide or the like is disclosed.
Japanese Patent Application Laid-Open No. 10-144561 discloses a conductor paste for forming an MLCC external electrode (terminal electrode) having nickel as a main component for conductor formation, and various kinds of co-fabrics (predetermined proportions) on the nickel powder. That is, there is disclosed a conductor paste characterized in that a powder comprising the same inorganic component as the ceramic substrate is added. It is described in the publication that an MLCC excellent in the adhesion between the external electrode and the ceramic substrate can be produced with such a conductive paste while ensuring good electrical conductivity between the internal electrode and the external electrode. .
[0004]
[Problems to be solved by the invention]
However, none of the conductor pastes described in the above publications has been developed with a focus on thinning the film conductor itself. For this reason, when a relatively thin film conductor is formed by using the conductor paste described in these publications, the same electrical characteristics and mechanical characteristics as the conventional relatively thick film conductor are not guaranteed. .
In other words, in order to further reduce the thickness of the membranous conductor while maintaining electrical properties (conductivity) and mechanical properties (adhesive strength) at a practically sufficient level, the inorganic / It is necessary to improve the filling rate (density) of a metal-based powder material (hereinafter referred to as “conductor forming powder material”). If the filling rate, ie, the density is not sufficient, the internal structure of the film-like conductor becomes rough, and as a result, the micro-cracks and pores that cause electrical disconnection or decrease in conductivity due to shrinkage during firing (baking). It is because it becomes easy to generate | occur | produce. Furthermore, the adhesiveness (adhesive strength) with the ceramic substrate is lowered, and the mechanical properties may be lowered. And the malfunction regarding this electrical and mechanical characteristic becomes more remarkable, so that the thickness of the film-form conductor to form is thin. However, none of the inventions described in the above-mentioned publications consider the improvement of the filling rate of the powder material for conductor formation.
[0005]
Therefore, the present invention was created to solve the problems associated with the conventional conductor paste as described above, and its object is a conductor paste for forming a conductor on a ceramic substrate. Another object of the present invention is to provide a conductor paste capable of forming a thin and dense film-like conductor as compared with the prior art while maintaining a practically sufficient level of electrical characteristics and / or mechanical characteristics. Another object of the present invention is to provide a method for producing such a conductive paste. Another object of the present invention is to provide a method of manufacturing a ceramic electronic component using such a conductive paste.
[0006]
[Means for Solving the Problems]
The present inventor has found that the above-mentioned filling rate can be improved by optimizing the particle size distribution of the conductor forming powder material constituting the paste, that is, by realizing a suitable particle size blending when preparing the conductor forming powder material. The headline and the present invention were created.
And in order to achieve the said objective, this invention provides the conductor paste manufacturing method specified as follows.
That is, provided by the present inventionOne preferredThe method is a method for producing a conductor paste containing a conductor forming powder material as a main component, and includes a step of preparing the conductor forming powder material and a step of dispersing the powder material in a vehicle. Then, the preparation of the powder material for forming the conductor is carried out with a predetermined particle size distribution which is the main component of the powder materialAndAverage particle sizeIs 0.2 to 1.0 μmNearly sphericalnickelThe filling ratio of the powder material in the dry coating film when the conductive paste is applied to the ceramic substrate with respect to the powder constitutes the main body.nickelIn an amount that is higher than the filling rate of the powder material for conductor formation in the case of consisting only of powder,nickelThe particle size distribution is different from the powder and the average particle size isnickelOf the average particle size of the powder1/4 to 1/8It is carried out by adding one or more kinds of substantially spherical metal powders and / or ceramic powders.
[0007]
In addition, regarding the specification of the present invention, “average particle diameter” refers to an approximate value derived based on the particle diameter of the primary particles constituting the powder (powder). Typically, it means an average particle diameter estimated based on observation with an electron microscope such as SEM.
Further, in this specification, “substantially spherical powder” means that 70% by weight or more of particles (primary particles) constituting the powder have a sphere or a similar shape. Typically, 70% by weight or more of the particles constituting the powder has an aspect ratio (that is, the ratio of the short diameter to the long diameter of the particles) of 80% or more. In the present specification, “the particle size distribution is different” means that the particle diameters of most of the constituent particles (typically 70 wt% or more of the powder) are different between the two powders (two components) to be compared. It means that it does not overlap. Specifically, the particle size distribution curves of each of the two powders (generally represented on a coordinate plane in which the horizontal axis indicates the particle diameter and the vertical axis indicates the particle existence ratio) do not substantially overlap in the horizontal axis direction. Or the case where only the one end part overlaps. Therefore, when two powders having different particle size distributions as defined in the present specification are mixed, typically, a predetermined site (typically, two peaks are separated from each other in the particle size distribution curve). Is observed at a portion corresponding to the average particle diameter of each powder before mixing).
[0008]
In such a method for producing a conductor paste, a substantially spherical conductive metal powder (hereinafter referred to as “main metal powder”) which is a main component of the powder material for forming a conductor.As the nickel powder, a substantially spherical nickel powder having a predetermined particle size distribution and an average particle size of 0.2 to 1.0 μm is employed.In contrast, the main metal powder having a different particle size distribution and an average particle size (nickelPowder)1/4 to 1/8By adding metal powder and / or ceramic powder (hereinafter, these fine powders are collectively referred to as “filling auxiliary fine powder”), the filling rate in the coating film made of the powder material for conductor formation is improved. Can do. As a result, according to the conductor paste obtained by the present production method, it is possible to form a highly filled coating film, that is, a film-like conductor having a dense structure, on the ceramic substrate. For this reason, the conductor paste obtained by this manufacturing method can implement | achieve formation of a film-like conductor thinner than before, without impairing an electrical property and / or a mechanical characteristic.
[0009]
Moreover, based on the said manufacturing method, the following conductor pastes are provided as another aspect of this invention. That is, one of the conductor pastes provided by the present invention is a conductor paste mainly composed of a conductor forming powder material, and the conductor forming powder material has a predetermined particle size distribution.AndAverage particle sizeIs 0.2 to 1.0 μmNearly sphericalnickelIt is mainly composed of powder. And the filling rate of the said powder material for conductor formation in the dry coating film obtained by apply | coating this conductor paste to a ceramic base material is the saidnickelIn an amount that is higher than the filling rate of the powder material for conductor formation consisting of powder alone,nickelThe particle size distribution is different from the powder and the average particle size isnickelOf the average particle size of the powder1/4 to 1/8One or two or more substantially spherical metal powders and / or ceramic powders that arenickelIt is composed by adding to the powder.
[0010]
In the conductor paste of the present invention having such a structure, the main metal powder(Nickel powder)On the other hand, the filling auxiliary fine powder is added in an amount not exceeding the limit contributing to the improvement of the filling rate. Compared with the conventional film-like conductor composed of the main metal powder alone or a mixture of the powder and other metal or ceramic powder (the particle size is not mixed and the average particle size is not optimized as in the present invention). Thus, a thinner film conductor can be formed on the ceramic substrate while maintaining electrical characteristics and mechanical characteristics. Therefore, according to the conductor paste of the present invention, a thin film conductor capable of satisfying the requirements such as miniaturization, higher capacity and higher performance of MLCC and other ceramic electronic components at a high level.In base metal (Ni) which is superior in costCan be formed.For this reason, the ceramic electronic component can be reduced in size (slim) and reduced in price.
[0011]
Another one of the conductor pastes provided by the present invention is a conductor paste mainly composed of a conductor forming powder material, and the conductor forming powder material has a predetermined particle size distribution.AndAverage particle sizeIs 0.2 to 1.0 μmNearly sphericalnickelThe main component is powder.Nickel powder having a particle size distribution different from that of nickel powder and having an average particle diameter of ¼ to の of the average particle diameter of the nickel powder is nickel having an average particle diameter of 0.2 to 1.0 μm. PowderIt is configured to be added to. And aboveNickel powder with an average particle size of 0.2 to 1.0 μmThe content of is 75 wt% or more of the entire powder material for conductor formation,Nickel with an average particle size of 1/4 to 1/8The content ratio of the powder is 25 wt% or less of the entire powder material for forming a conductor.
In the conductor paste having such a configuration, the main metal powder(Nickel powder)And fine metal powders with substantially the same composition (thus, the presence or absence of trace components and their qualitative differences)(Nickel powder)Is contained in an appropriate amount as a filling auxiliary fine powder. Thus, according to the conductor paste of this configuration, a thin-film conductor having high electrical characteristics (conductivity) can be formed.
[0012]
In addition, another preferable conductor paste provided by the present invention is a conductor paste mainly composed of a conductor forming powder material, and the conductor forming powder material has a predetermined particle size distribution and average particle size. It has a substantially spherical nickel powder as a main component (hereinafter referred to as “Ni paste”). The present Ni paste has a particle size distribution different from that of the nickel powder and has an average particle size of one or two or more types of substantially spherical metal powders having an average particle size of about one quarter or less of the average particle size of the nickel powder. A ceramic powder is added to the nickel powder. Thus, the volume (amount) of the metal powder and / or ceramic powder added to the nickel powder is expressed in terms of barium titanate powder. That is, a barium titanate powder having an average particle size of approximately one quarter or less of the average particle size of the nickel powder and corresponding to a weight (mass) of 30 wt% or less of the nickel powder. Defined as volume.
[0013]
In the Ni paste having the above-described configuration, the metal powder and / or ceramic powder (ie, barium titanate is a typical example) as a filling auxiliary fine powder so as to have the above amount in terms of barium titanate powder with respect to the Ni powder as the main metal powder. ) Is added. The filling ratio of the conductor-forming material mainly composed of Ni powder can be improved by the particle size blending based on such a volume ratio, and as a result, densification of the Ni conductor formed on the ceramic substrate can be realized. For this reason, according to the Ni paste of the present invention, a thin-film conductor that can satisfy the requirements for miniaturization, higher capacity, and higher performance of MLCC and other ceramic electronic components at a high level is obtained with a base metal (Ni ). For this reason, the ceramic electronic component can be reduced in size (slim) and reduced in price.
[0014]
Further, in the preferred Ni paste of the present invention, the average particle diameter of the substantially spherical nickel powder constituting the main body of the powder material for conductor formation is 0.2 to 1.0 μm, and as the metal powder and ceramic powder, It is characterized by containing a conductive metal powder having an average particle size of approximately one quarter or less of the average particle size of the nickel powder and a barium titanate-based dielectric powder.
According to the Ni paste having such a configuration, it is possible to form a thin-film Ni conductor having high mechanical strength and high adhesive strength to a ceramic substrate (particularly, containing barium titanate). Further, according to the Ni paste of this configuration, a high density thin film Ni conductor excellent in electrical characteristics such as conductivity is formed by a combination of Ni powder and conductive metal powder (typically fine Ni powder). Can do.
[0015]
Further, as another aspect of the present invention, there is provided a method for producing MLCC and other ceramic electronic components, characterized in that the conductor paste obtained by the paste production method (typically each of the above-mentioned conductor pastes) is used. To do. Typically, in the present manufacturing method, a step of applying the conductor paste according to the present invention to a ceramic substrate and a step of firing the applied paste main component (that is, a highly filled powder material for forming a conductor); Is included. According to this manufacturing method, it is possible to manufacture and provide MLCC and other ceramic electronic components in which a thin film conductor having excellent electrical characteristics and mechanical characteristics corresponding to miniaturization, high capacity, and high performance is formed.
As another aspect of the present invention, a powder material for forming a conductor for preparing the conductor paste of the present invention and a method for producing the same are provided. Typical examples thereof are conductor-forming powder materials used in the above-described conductor paste manufacturing method, and further, conductor-forming powder materials which are the main constituent elements of each of the above-described conductor pastes. The conductor-forming powder material specified in 1) and a method for producing the same.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described.
[0017]
As a powder material for forming a conductor, which is the main component of the conductor paste of the present invention, in a dry coating film derived from a paste applied to a ceramic base material (alumina substrate, glass substrate, etc.) by a screen printing method or other technique or a fired body thereof In order to improve the filling rate (maximum filling rate) of the conductor-forming powder material, the main metal powder having a predetermined particle size distribution and average particle size has a different particle size distribution and an average particle size of 4 of the main metal powder. A predetermined amount of a substantially spherical auxiliary filling fine powder that is less than one-quarter (preferably about 1/8 to 1/8, especially about 1/6 to 1/8) is added.The
[0018]
For example, MadeIn order to reduce the cost of manufactured ceramic electronic parts such as MLCC, it is significant to apply the present invention to a conductor paste mainly composed of a base metal such as Ni and its preparation.
In addition, from the viewpoint of forming a film conductor that is relatively thinner than conventional without impairing electrical characteristics (conductivity, etc.) and mechanical characteristics (adhesion strength, etc.), it is submicron order (preferably 0.1 to 0.1). A conductive metal powder having an average particle size of 1.0 μm is particularly suitable as the main metal powder. For example, when the Ni paste of the present invention is used for applications such as MLCC internal electrode formation, the average particle diameter of Ni powder as the main metal powder is preferably 0.2 to 1.0 μm, and 0.4 to 0 It is particularly preferable that the thickness is 6 μm (for example, 0.5 μm). The specific surface area (based on BET) of the nickel powder is 1 to 10 m.2/ G is preferable.
[0019]
On the other hand, the filling auxiliary fine powder added to such a main metal powder has a particle size distribution different from that of the main metal powder, which can contribute to improving the filling rate of the main metal powder to be used (conductor forming powder material) and It may be a substantially spherical fine powder having an average particle size of about 1/4 or less (preferably 1/4 to 1/8, particularly 1/6 to 1/8) of that of the main metal powder, It is not limited to a specific metal powder or ceramic powder. For example, various dielectric powders and spherical fine powders of metal oxides can be used as the filling auxiliary fine powder. The filling auxiliary fine powder preferably does not significantly impair the conductivity (low resistivity), solder wettability, solder heat resistance, adhesive strength, etc. of the conductor paste of the present invention. For example, examples of the ceramic powder include glass powder and inorganic oxide (metal oxide). For example, the metal oxide may be an oxide such as Al, Zr, Ti, Si, Pb, Fe, W, Mn, Bi, Nb, Ta, Mo, Ca, Sr, Ba, Mg, or a high melting point rare earth (ie, (Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) oxides. In addition, as the dielectric powder, common materials with the ceramic substrate to be used, for example, barium titanate oxides, nitrides such as silicon nitride and aluminum nitride, carbides such as silicon carbide and titanium carbide, and these A mixture etc. are mentioned. By adding the ceramic powder as described above (including the above metal oxide), the heat resistance, adhesive strength and the like of the film conductor formed from the conductor paste of the present invention can be further improved.
[0020]
In addition, the metal powder that can be used as a filling auxiliary fine powder is a metal powder having substantially the same composition as the main metal powder (typically composed of the same or similar raw materials and having the same specific gravity as the main metal powder or Approximate fine metal powders and spherical powders whose particle size distribution and average particle size are different from those of the main metal powder). By combining (mixing) metal powders having substantially the same composition with different average particle diameters and particle size distributions, a powder material composed of the main metal powder alone can be obtained without impairing the electrical properties and other physical properties of the metal powders. In comparison, it is possible to form a denser film conductor having excellent mechanical strength and conductivity.
In addition, the particle size distribution and average particle diameter of the filling auxiliary fine powder to be used are defined according to the particle size distribution and average particle diameter of the target main metal powder. For example, when a metal powder having an average particle size of 0.5 μm is used as the main metal powder, one having an average particle size of 0.125 μm or less can be used as the filling auxiliary fine powder.
[0021]
By the way, from the viewpoint of improving the filling property, the powder material used as the main metal powder and the filling auxiliary fine powder preferably has a sharp particle size distribution. This is because a sharper (narrower) particle size distribution can be more accurately blended with an appropriate particle size. Although not particularly limited, for example, when a metal powder having an average particle size of about 0.5 μm is used as the main metal powder, approximately 70% or more of the total particle is 60 to 140% of the average particle size. Particle size range (preferably a particle size range of 80 to 120% of the average particle size), specifically, approximately 70% or more of the total particle size is 0.3 to 0.7 μm (preferably a particle size) A sharp particle size distribution that falls within the range of 0.4 to 0.6 μm in diameter is desirable. When the metal powder having an average particle size of about 1.0 μm is used as the main metal powder, approximately 70% or more of the total particle size is 0.6 to 1.4 μm (preferably a particle size of 0.1 μm). A sharp particle size distribution that falls within the range of 8 to 1.2 μm is desirable.
On the other hand, the filling auxiliary fine powder when the main metal powder having an average particle size of about 0.5 μm is used is 0.125 μm or less (preferably 0.125 to 0.0625 μm, more preferably 0.083 to 0.062 μm). ) Having an average particle size of about 70% or more of the total particle size is about 60 to 140% of the average particle size (preferably about 80 to 120% of the particles). Diameter range), specifically, the average particle size is approximately 0.125 μm, and approximately 70% or more of the total particle size is 0.075 to 0.15 μm (preferably 0.1 to 0 particle size). A sharp particle size distribution belonging to the range of .15 μm) is desirable. Similarly, the filling auxiliary fine powder in the case of using the main metal powder having an average particle diameter of about 1.0 μm is 0.25 μm or less (preferably 0.25 to 0.125 μm, more preferably 0.25 to 0.001). 167 μm) having an average particle diameter of 60 to 140% of the average particle diameter (preferably a particle diameter range of about 80 to 120% of the average particle diameter), specifically Specifically, it is desirable to have a sharp particle size distribution such that approximately 70% or more of the total particles belong to a particle size range of 0.075 to 0.175 μm (preferably a particle size of 0.1 to 0.15 μm). .
[0022]
In carrying out the present invention, as long as both the main metal powder and the filling auxiliary fine powder are substantially spherical, their production methods are not limited. For example, Ni and other spherical metal powders and spherical ceramic powders such as silica and alumina may be appropriately obtained and used by those conventionally known methods. For example, one of known methods for producing spherical silica and other ceramic fine particles includes a so-called spray drying method. Moreover, metal powders, such as Ni powder, can be manufactured by the spray pyrolysis method or what is called CVD method. In carrying out the present invention, spherical powders produced by these known methods can be appropriately obtained (manufactured or purchased) and used.
[0023]
Next, preparation of the powder material for conductor formation which is the main component of the conductor paste of the present invention will be described. This powder material is a powder material constituted by adding the filling auxiliary fine powder having the above-described properties to the main metal powder as the main component. Thus, the addition amount of the filling auxiliary fine powder may be set within a range satisfying the following conditions. That is, the filling ratio of the powder material in the dry coating film obtained when the conductor paste of the present invention is applied to the ceramic substrate (and thus the denseness of the film-shaped conductor after firing) consists only of the main metal powder. What is necessary is just to set addition amount in the range which becomes higher than the filling rate of the said powder material in the dry coating film obtained when the paste of the powder material for conductor formation is apply | coated to the ceramic base material. In general, when there is a difference in suitable average particle size and particle size distribution between the main metal powder used and the filling auxiliary fine powder as described above, the addition of the filling auxiliary fine powder until the predetermined addition amount is reached. The filling rate is improved according to the amount. Therefore, the amount (content) of the filling auxiliary fine powder in the practice of the present invention may be in the range up to the predetermined addition amount (of course, even if the addition amount exceeds the predetermined addition amount, As long as the filling rate of the powder material in the dry coating film is higher than when using the paste of the powder material for forming a conductor made of only the main metal powder as described above, it is determined without requiring excessive experimentation. be able to.
Although not particularly limited, when a substantially spherical metal powder having substantially the same composition as the main metal powder is used as the filling auxiliary fine powder, the content is 25 wt% or less of the entire powder material for conductor formation. An amount of 5 to 20 wt% (particularly preferably 15 to 20 wt%) of the entire conductor-forming powder material may be added. When the addition amount is more than 25 wt% of the entire conductor-forming powder material, there is a possibility that the filling auxiliary fine powder having a volume exceeding the gap between the particles of the main metal powder may be added. This is because the filling rate may be reduced due to the presence of the filling auxiliary fine powder that cannot be fully accommodated in the gap (see Examples described later).
Note that the upper limit of the preferable addition amount is higher than the theoretical value related to the maximum filling rate of the two-component system having different particle diameters, and a relatively larger addition amount is preferable in the practice of the present invention. It shows that. In addition, the theoretical value (theoretical addition amount) relating to the maximum filling rate of the two-component system is obtained as follows.
That is, the radius r at each lattice point of the face-centered cubic lattice1In the close-packed cubic structure in which the spheres (primary spheres) are arranged, the filling rate is 74.05% and the porosity is 25.95%. On the other hand, the largest fine particles that can be placed in the gap, that is, the position of the center of gravity, in the gap between the primary spheres constituting the cubic close-packed structure (that is, the position of the center of gravity of a regular tetrahedron composed of adjacent primary spheres). When fine particles (filling auxiliary fine particles) having a diameter in contact with each primary sphere adjacent to the center are arranged, the filling rate is 81.00% and the porosity is 19.00%. That is, the volume (6.95%) obtained by subtracting the filling rate (74.05%) of the cubic close-packed structure from the filling rate (81.00%) is the volume of the filling auxiliary fine particles. From this, the main metal powder (corresponding to the primary sphere) 100 cmThreeThe theoretical addition amount of the filling auxiliary fine powder (corresponding to the above filling auxiliary fine particles) with respect to is 9.39 cm based on 74.05: 6.95≈100: 9.39.ThreeIt is derived.
[0024]
When the present invention is applied to Ni paste, Ni powder as a main metal powder (preferably Ni powder having an average particle size of 0.2 to 1.0 μm, particularly preferably Ni powder having an average particle size of about 0.5 μm) The addition amount of the filling auxiliary fine powder is preferably defined as the volume in terms of barium titanate powder having an average particle size of approximately one-fourth or less of the average particle size of the Ni powder. it can. For example, 100 g (1 cm) of Ni powder having an average particle size of 0.5 μm under normal temperature and normal pressureThree≒ 8.9g, therefore 100g ≒ 11.2cmThreeThe preferred addition amount of the filling auxiliary fine powder added to the above is a weight equivalent to 30 wt% or less of the Ni powder (that is, 30 g or less) of barium titanate powder (1 cmThree≒ 6.0g) occupied capacity (for example, 30cm when converted to 30g barium titanate powder)3). According to this barium titanate conversion, in the powder material for forming a conductor used in the Ni paste of the present invention, an appropriate addition amount (volume) regardless of the type of the filling auxiliary fine powder (that is, regardless of the specific gravity of the powder). Can be determined without repeating excessive experiments.
[0025]
Thus, the powder material for conductor formation according to the present invention can be easily obtained by mixing a predetermined amount of main metal powder and an appropriate amount of filling auxiliary fine powder. Such mixing treatment may be performed independently before the powder material is dispersed in the vehicle, or may be performed in combination with the dispersion in the vehicle (that is, preparation of the powder material for forming a conductor in this case). The process and the process of dispersing the powdered material in the vehicle are performed simultaneously).
In addition, as this mixing method, the powder mixing means conventionally used normally can be utilized without a restriction | limiting in particular. For example, these powders may be stirred and mixed using various mixers, mills, etc. (for example, planetary mills). The conductor-forming powder material thus prepared typically has two or more peaks in its particle size distribution curve. This can be an index indicating that the conductor-forming powder material according to the present invention is a multi-component material in which two or more powders having different particle size distributions are mixed.
[0026]
Next, the subcomponent which comprises the conductor paste of this invention is demonstrated. The conductor paste of the present invention can contain the same substance as the conventional conductor paste as a subcomponent in addition to the above-mentioned powder material for forming a conductor that contributes to an improvement in filling rate.
For example, as an essential subcomponent of the conductor paste of the present invention, an organic medium (vehicle) in which the above-mentioned conductor-forming powder material is dispersed can be mentioned. In the practice of the present invention, any organic vehicle may be used as long as the conductive powder material is dispersed in the organic vehicle, and those used in conventional conductor pastes can be used without particular limitation. Examples thereof include cellulose polymers such as ethyl cellulose, high-boiling organic solvents such as ethylene glycol and diethylene glycol derivatives, toluene, xylene, mineral spirits, butyl carbitol, and terpineol.
[0027]
In addition, the conductive paste of the present invention contains various organic additives as subcomponents as long as the conductivity (low resistivity), solder wettability, solder heat resistance, adhesive strength, etc. of the paste are not significantly impaired. Can do. For example, as such organic additives, various organic binders (may overlap with the above-mentioned vehicle or different binders may be added separately) or silicon-based or titanate-based for the purpose of improving adhesion to a ceramic substrate. And various coupling agents such as aluminum.
Examples of the organic binder include those based on acrylic resin, epoxy resin, phenol resin, alkyd resin, cellulosic polymer, polyvinyl alcohol and the like. What can give the favorable viscosity and the coating-film (adhesion film with respect to a base material) formation ability to the conductor paste of this invention is suitable. Moreover, when it is desired to impart photocurability (photosensitivity) to the conductor paste of the present invention, various photopolymerizable compounds and photopolymerization initiators may be added as appropriate.
[0028]
In addition to the above, a surfactant, an antifoaming agent, a plasticizer, a thickener, an antioxidant, a dispersant, a polymerization inhibitor, etc. may be appropriately added to the conductor paste of the present invention as necessary. Can do. These additives may be any additives that can be used for the preparation of conventional conductor pastes, and will not be described in detail.
[0029]
Next, preparation of the conductor paste of this invention is demonstrated. The conductor paste of the present invention can be easily prepared by mixing the above-mentioned powder material for forming a conductor and an organic medium (vehicle), as in the case of the conventional conductor paste. The main metal powder and the filling auxiliary fine powder may be added separately to the vehicle, or those obtained by mixing them in advance may be added. At this time, the additives as described above may be added and mixed as necessary. For example, by using a three-roll mill or other kneader, the conductor-forming powder material and various additives are directly mixed together with the organic vehicle at a predetermined blending ratio, and are kneaded (kneaded) with each other. A paste can be prepared.
[0030]
Next, a preferred example relating to the formation of a film conductor using the conductor paste of the present invention (that is, production of a ceramic electronic component) will be described. The conductor paste of the present invention can be handled in the same manner as the conductor paste conventionally used for forming film conductors such as wirings and electrodes on a ceramic substrate (substrate). It can be employed without any particular limitation. Typically, the conductive paste is applied to the ceramic substrate (substrate) by a screen printing method, a dispenser coating method, or the like so as to have a desired shape and thickness. Then, preferably after drying, predetermined under appropriate heating conditions in a heater (maximum firing temperature is generally 600 to 1300 ° C, typically 700 to 1000 ° C, but Ni paste preferably 1100 to 1300 ° C). By heating for a period of time, the applied paste component is baked (baked) and cured. By performing this series of processing, a ceramic electronic component (for example, an MLCC electrode, a hybrid IC, or a ceramic wiring board for constructing a multichip module) on which a target thin film conductor (wiring, electrode, etc.) is formed can be obtained. can get. Thus, a more advanced ceramic electronic component (for example, a hybrid IC or a multichip module) can be obtained by applying a conventionally known construction method while using the ceramic electronic component as an assembly material. Note that the construction method itself does not particularly characterize the present invention, and a detailed description thereof will be omitted.
Although not intended to limit the application, as described above, the conductor paste of the present invention can form a film-like conductor that is more dense than the conventional one. For this reason, the conductor paste of the present invention is suitable not only for forming a conductor having a film thickness of about 10 to 30 μm, but also for use for forming a conductor having a relatively thin film thickness of 10 μm or less. For example, a film conductor having a thickness of 1.5 to 3 μm, which is preferable as a Ni internal electrode for MLCC, can be formed.
[0031]
【Example】
Several examples relating to the present invention will be described below, but the present invention is not intended to be limited to those shown in the examples.
[0032]
<Example 1>
As Example 1, a Ni paste was prepared using a barium titanate powder as a filling auxiliary fine powder. That is, to 100 g of Ni powder having an average particle diameter of about 0.4 μm, barium titanate powder having an average particle diameter of about 0.1 μm is added in an amount (10 g) corresponding to 10 wt% of the Ni powder, and stirred and mixed. Thus, a powder material for forming a conductor according to this example was prepared.
Next, Ni paste was prepared using the obtained powder material for conductor formation. That is, the final paste concentration (weight ratio) is 55 wt% (Ni powder 50 wt%,
[0033]
<Comparative Example 1>
A Ni paste according to this comparative example was prepared by performing the same treatment as in Example 1 except that the barium titanate powder used had an average particle size of about 0.2 μm.
[0034]
<Comparative Example 2>
The Ni paste according to this comparative example was prepared using the Ni powder as it is as a powder material for conductor formation without adding the barium titanate powder. The final paste solid content concentration is the same as in Example 1.
[0035]
<Test Example 1: Evaluation of coating film density (1)>
Next, a coating film was formed on the glass substrate using the Ni paste according to Example 1 and Comparative Examples 1 and 2, respectively, and the coating film density (g / cm3) Was measured. That is, each conductive paste was applied to the surface of a glass substrate (a soda lime substrate having a thickness of about 1.3 mm) based on a general screen printing method to form a coating film having a predetermined film thickness. Then, the drying process for 15 minutes was performed at 100 degreeC using the far-infrared dryer. By this drying treatment, the solvent was volatilized from the coating film, and a dry coating film made of a powder material for forming a conductor was obtained. Subsequently, about the obtained dried coating film, the coating-film weight and coating-film thickness were measured, and the coating-film density was computed. The results are shown in Table 1.
[0036]
[Table 1]
As is clear from Table 1, the density of the dried coating film obtained from the conductor paste according to Example 1 significantly exceeds the density of the dried coating film obtained from each of the conductor pastes of Comparative Example 1 and Comparative Example 2. It was. This result shows that the powder for forming a conductor that forms a dry coating film is obtained by adding and mixing an appropriate amount of barium titanate powder having an average particle size of 1/4 or less of that powder to Ni powder as the main metal powder. This shows that the filling rate of the material can be improved, and that the structure of the film conductor can be densified. On the other hand, in a conductor paste (Comparative Example 1) obtained by adding and mixing a barium titanate powder having a relatively large particle size such that the average particle size exceeds a quarter of the Ni powder, the filling rate is as follows. In other words, it was confirmed that the density of the dried coating film could not be increased, and the filling rate was decreased as compared with the case where the barium titanate powder was not added (Comparative Example 2) (Table). 1).
[0038]
<Example 2>
As Example 2, a Ni paste having substantially the same composition of Ni powder as a filling auxiliary fine powder was prepared. That is, for 100 g of Ni powder (hereinafter referred to as “main Ni powder”) having an average particle diameter of about 0.5 μm, 9 Ni powder (hereinafter referred to as “sub Ni powder”) having an average particle diameter of about 0.1 μm is used. .4g was added, and the powder material for conductor formation which concerns on a present Example was prepared by stirring and mixing. That is, the content rate of the sub Ni powder (that is, the metal powder corresponding to the filling auxiliary fine powder) of the conductor forming powder material according to this example is 8.6 wt% of the entire conductor forming powder material. Next, using this powder material for forming a conductor, the same kneading treatment as in Example 1 was performed to prepare a Ni paste according to this example.
[0039]
<Example 3>
The powder material for conductor formation which concerns on a present Example was prepared by adding 14.8g of sub Ni powder with respect to 100g of main Ni powder, and stirring and mixing. That is, the content rate of the sub Ni powder of the conductor forming powder material according to the present example is 12.9 wt% of the entire conductor forming powder material. Next, using this powder material for forming a conductor, the same kneading treatment as in Example 1 was performed to prepare a Ni paste according to this example.
[0040]
<Example 4>
A powder material for forming a conductor according to this example was prepared by adding 20.8 g of sub Ni powder to 100 g of main Ni powder, and stirring and mixing. That is, the content rate of the sub Ni powder of the conductor forming powder material according to this example is 17.2 wt% of the entire conductor forming powder material. Next, using this powder material for forming a conductor, the same kneading treatment as in Example 1 was performed to prepare a Ni paste according to this example.
[0041]
<Comparative Example 3>
A conductor forming powder material according to this comparative example was prepared by adding 100 g of sub Ni powder to 100 g of main Ni powder, and stirring and mixing. That is, the content of the sub-Ni powder in the conductor forming powder material according to this comparative example is 50 wt% of the entire conductor forming powder material. Next, using this powder material for forming a conductor, the same kneading treatment as in Example 1 was performed to prepare a Ni paste according to this comparative example.
[0042]
<Comparative example 4>
The main Ni powder (different from that used in Comparative Example 2) was used as it was as the conductor-forming powder material without adding the secondary Ni powder, and the same kneading treatment as in Example 1 was performed. Such Ni paste was prepared.
[0043]
<Test Example 2: Evaluation of coating film density (2)>
Next, using the Ni pastes according to Examples 2 to 4 and Comparative Examples 3 and 4, a coating film density evaluation test was performed under the same conditions as in Test Example 1. The results are shown in Table 2.
[0044]
[Table 2]
As is clear from Table 2, the density of each dry coating film obtained from each of the Ni pastes according to Examples 2 to 4 is the dry coating film obtained from each Ni paste of Comparative Example 3 and Comparative Example 4 Exceeded the density. This result is obtained by adding and mixing an appropriate amount of sub-Ni powder having an average particle size of ¼ or less of the main Ni powder to the conductor-forming powder material (that is, Ni This indicates that the filling ratio of the powder) can be improved, and the structure of the film-like Ni conductor can be densified. In contrast, the Ni paste (Comparative Example 3) obtained by adding and mixing an excessive amount of the secondary Ni powder with respect to the main Ni powder realizes an improvement in the filling rate, that is, a higher density of the dried coating film. In addition to this, it was confirmed that the filling rate was decreased as compared with the case where the secondary Ni powder was not added (Comparative Example 4) (see Table 2).
[0046]
<Test Example 3: Evaluation of coating film density (No. 3)>
Barium titanate powder (average particle size of about 0.1 μm) was used as a ceramic additive (ie, filling auxiliary fine powder according to the present invention), and several Ni pastes with different addition amounts were prepared. The relationship between the coating density and the coating density was investigated. That is, 0 g, 7.5 g, 10 g, 12.5 g, 15 g, 17.5 g, 20 g, or 30 g of the barium titanate powder is added to 100 g of Ni powder having an average particle diameter of about 0.4 μm, and stirred and mixed. By doing so, a total of 8 types of conductor forming powder materials with different barium titanate powder addition amounts were prepared. Next, the same kneading treatment as in Example 1 was performed, and Ni pastes were prepared from these conductor-forming powder materials, respectively. Next, a coating density evaluation test of each Ni paste was performed under the same conditions as in Test Example 1. The results are shown in Table 3 and FIG.
[0047]
[Table 3]
As shown in Table 3 and FIG. 1, the dried coating film formed from the Ni paste containing the ceramic additive prepared in this test example is formed from the Ni paste to which no ceramic additive (barium titanate powder) is added. It was denser than the dried coating film. In particular, in the Ni paste obtained by adding 10 to 20 g of ceramic additive to 100 g of Ni, the density of the dried coating film was remarkable.
[0049]
【The invention's effect】
As is clear from the above examples, according to the conductor-forming powder material of the present invention and the conductor paste comprising the same as the main component, the filling rate of the conductor-forming powder material constituting the dry coating on the ceramic substrate Can be improved as compared with the prior art. For this reason, by applying the conductor paste of the present invention to the formation of a film-like conductor of ceramic electronic parts such as MLCC, the thin film-like shape of a dense structure excellent in electrical characteristics such as conductivity and mechanical characteristics such as adhesive strength A ceramic electronic component on which a conductor is formed can be manufactured.
[Brief description of the drawings]
FIG. 1 is a graph showing the relationship between the amount of a ceramic additive and the density of a dry coating film.
Claims (4)
その導体形成用粉末材料を調製する工程と、該粉末材料をビヒクルに分散する工程とを包含し、
その導体形成用粉末材料の調製は、該粉末材料の主体を成す所定の粒度分布を有し且つ平均粒径が０．２〜１．０μｍである略球状のニッケル粉末に対し、導体ペーストをセラミック基材に塗布したときの乾燥塗膜における該粉末材料の充填率が該ニッケル粉末のみから成る場合の導体形成用粉末材料の充填率よりも高くなる分量で、該ニッケル粉末とは粒度分布が異なり且つその平均粒径が該ニッケル粉末の平均粒径の１／４〜１／８である一種又は二種以上の略球状の金属粉末及び／又はセラミック粉末を添加することによって行われる、導体ペースト製造方法。A method for producing a conductor paste comprising a conductor-forming powder material as a main component,
Including a step of preparing the conductor-forming powder material and a step of dispersing the powder material in a vehicle,
The powder material for conductor formation is prepared by applying a conductor paste to a substantially spherical nickel powder having a predetermined particle size distribution which is the main component of the powder material and having an average particle size of 0.2 to 1.0 μm. in an amount of filling factor of the powder material in the dry coating film when applied to a substrate is higher than the filling factor of the conductor forming powder material when composed of only the nickel powder, different particle size distribution and the nickel powder The conductor paste is produced by adding one or more kinds of substantially spherical metal powder and / or ceramic powder whose average particle diameter is 1/4 to 1/8 of the average particle diameter of the nickel powder. Method.
その導体形成用粉末材料は、所定の粒度分布を有し且つ平均粒径が０．２〜１．０μｍである略球状のニッケル粉末を主体とするものであり、本導体ペーストをセラミック基材に塗布して得られた乾燥塗膜における該導体形成用粉末材料の充填率が該ニッケル粉末のみから成る導体形成用粉末材料の充填率よりも高くなる分量で、該ニッケル粉末とは粒度分布が異なり且つその平均粒径が該ニッケル粉末の平均粒径の１／４〜１／８である一種又は二種以上の略球状の金属粉末及び／又はセラミック粉末が該ニッケル粉末に添加されて構成されている、導体ペースト。A conductor paste mainly composed of a powder material for forming a conductor,
The conductor forming powder material is mainly composed of substantially spherical nickel powder having a predetermined particle size distribution and an average particle diameter of 0.2 to 1.0 μm. in an amount of filling factor of the powder material for the conductor forming the dried coating film obtained by coating and is higher than the filling factor of the conductor forming powder material consisting of only the nickel powder, different particle size distribution and the nickel powder and the average particle size is configured metal powder and / or ceramic powders of one or two or more substantially spherical is 1/4 to 1/8 of the average particle diameter of the nickel powder is added to the nickel powder There is a conductor paste.
その導体形成用粉末材料は、所定の粒度分布を有し且つ平均粒径が０．２〜１．０μｍである略球状のニッケル粉末を主体とするものであり、前記ニッケル粉末とは粒度分布が異なり且つその平均粒径が前記ニッケル粉末の平均粒径の１／４〜１／８である略球状のニッケル粉末が前記平均粒径０．２〜１．０μｍのニッケル粉末に添加されて構成されており、
ここで前記平均粒径が０．２〜１．０μｍのニッケル粉末の含有率は導体形成用粉末材料全体の７５ wt ％以上であり、前記１／４〜１／８の平均粒径のニッケル粉末の含有率は導体形成用粉末材料全体の２５ wt ％以下である、導体ペースト。A conductor paste mainly composed of a powder material for forming a conductor,
Its conductor forming powder material is intended and an average particle diameter has a predetermined particle size distribution is mainly composed of nickel powder of substantially spherical is 0.2 to 1.0 [mu] m, the particle size distribution and the nickel powder different and configuration that the average particle size is added to the nickel powder having an average particle diameter of 1 / 4-1 / 8 der Ru substantially spherical nickel powder is the average particle diameter 0.2~1.0μm of the nickel powder Has been
Here, the content of the nickel powder having an average particle diameter of 0.2 to 1.0 μm is 75 wt % or more of the entire powder material for conductor formation , and the nickel powder having the average particle diameter of 1/4 to 1/8. Is a conductor paste whose content is 25 wt % or less of the entire powder material for conductor formation .
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| EP1594146A4 (en) * | 2003-02-05 | 2010-01-06 | Tdk Corp | Electronic parts and method for manufacture thereof |
| JP4223848B2 (en) | 2003-03-24 | 2009-02-12 | Ｔｄｋ株式会社 | Method for producing conductive composition, and method for producing conductive paste |
| JP2005117004A (en) * | 2003-10-08 | 2005-04-28 | Ngk Spark Plug Co Ltd | Multilayer ceramic capacitor, multilayer capacitor, and manufacturing method of the multilayer capacitor |
| JP2005203304A (en) * | 2004-01-19 | 2005-07-28 | Hitachi Chem Co Ltd | Mixed conductive powder |
| JP5096659B2 (en) * | 2004-02-27 | 2012-12-12 | 京セラ株式会社 | Piezoelectric actuator and print head |
| JP2005286014A (en) * | 2004-03-29 | 2005-10-13 | Denso Corp | Conductive paste |
| JP4628718B2 (en) * | 2004-07-23 | 2011-02-09 | 株式会社フジクラ | Method for forming conductive film |
| JP4765321B2 (en) * | 2005-01-21 | 2011-09-07 | 株式会社村田製作所 | Conductive paste |
| JP2006310022A (en) * | 2005-04-27 | 2006-11-09 | Mitsui Mining & Smelting Co Ltd | Electrically conductive paste, and flexible printed wiring board obtained using the same |
| JP5058839B2 (en) * | 2008-02-01 | 2012-10-24 | 株式会社ノリタケカンパニーリミテド | Photosensitive conductive paste for transfer and photosensitive transfer sheet |
| KR101033233B1 (en) * | 2009-09-25 | 2011-05-06 | (주)한메가 | Apparatus for credit card module of atm |
| KR20120073636A (en) * | 2010-12-27 | 2012-07-05 | 삼성전기주식회사 | Paste compound for termination electrode and multilayer ceramic capacitor comprising the same and manufacturing method thereof |
| JP5458085B2 (en) * | 2011-12-20 | 2014-04-02 | 京セラ株式会社 | Multilayer piezoelectric body, piezoelectric actuator and print head |
| JP6042736B2 (en) * | 2013-01-30 | 2016-12-14 | 新日鉄住金化学株式会社 | Nickel fine particle-containing composition and method for producing the same |
| JP6996867B2 (en) * | 2017-05-16 | 2022-01-17 | 太陽誘電株式会社 | Multilayer ceramic capacitors and their manufacturing methods |
| JP7186014B2 (en) * | 2017-08-10 | 2022-12-08 | 太陽誘電株式会社 | Multilayer ceramic capacitor and manufacturing method thereof |
| KR102587765B1 (en) * | 2017-08-10 | 2023-10-12 | 다이요 유덴 가부시키가이샤 | Multilayer ceramic capacitor and manufacturing method of multilayer ceramic capacitor |
| JP7290914B2 (en) * | 2018-02-26 | 2023-06-14 | 太陽誘電株式会社 | Manufacturing method of multilayer ceramic capacitor |
| WO2023218991A1 (en) * | 2022-05-11 | 2023-11-16 | 昭栄化学工業株式会社 | Baking type conductive paste |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0817241A (en) * | 1994-06-30 | 1996-01-19 | Mitsuboshi Belting Ltd | Copper conductive paste and manufacture of copper conductive film |
| JP3467873B2 (en) * | 1994-12-02 | 2003-11-17 | 株式会社村田製作所 | Method for manufacturing multilayer ceramic substrate |
| JPH10144559A (en) * | 1996-11-05 | 1998-05-29 | Matsushita Electric Ind Co Ltd | Terminal electrode paste, laminated electronic component and its manufacture |
-
2001
- 2001-02-22 JP JP2001046220A patent/JP3697401B2/en not_active Expired - Lifetime
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2002
- 2002-02-21 KR KR1020020009335A patent/KR100867288B1/en active IP Right Grant
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| Publication number | Publication date |
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| TW594795B (en) | 2004-06-21 |
| JP2002245874A (en) | 2002-08-30 |
| KR100867288B1 (en) | 2008-11-06 |
| KR20020069139A (en) | 2002-08-29 |
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