JP2004335149A - Conductive paste, manufacturing method of wiring board, and wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive paste with conductivity, strong adhesive (close contacting) property and durability thereof, and provide a manufacturing method of a printed board using the same, and the printed board manufactured by the above method. <P>SOLUTION: The conductive paste contains metal powder (A), resin (B), and curing agent (C). The resin (B) is a resin (b1) containing at least not less than one -COOH group in one molecule, or a resin (b2) of a latent -COOH group generating compound. The curing agent (C) is a compound containing at least not less than two vinyl thioether bonding in one molecule. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００９】
［式中のＲは水素原子又はメチル基、Ｒ^１、Ｒ^２及びＲ^３はそれぞれ水素原子又は炭素数１〜１８の有機基、Ｒ^４は炭素数１〜１８の有機基であって、Ｒ^３とＲ^４はたがいに結合してＹをヘテロ原子とする複素環を形成していてもよく、Ｙは酸素原子又はイオウ原子、ｎは１〜１０の整数である。］
〔６〕 さらにジチオカルバミン酸基、ジスルフィド基、メルカプト基、およびチオウレア基からなる群より選択される基を有する硫黄化合物（Ｄ）の１種または２種以上を含む前記の〔１〕〜〔５〕に記載の導電性ペースト。
【００１０】
〔７〕 前記の〔１〕〜〔６〕のいずれかに記載の導電性ペーストを用いて、次の工程を行うプリント配線板の製造方法。
Ａ工程；プリント配線板やフレキシブルプリント基板の上に前記の〔１〕〜〔６〕のいずれかに記載の導電性ペーストをパターン塗布し加熱処理して回路や電極を形成する工程（Ａ）、
Ｂ工程；多層基板のスルーホールに前記の〔１〕〜〔６〕のいずれかに記載の導電性ペーストを充填し加熱処理して層間の電気的導通を得る工程（Ｂ）、
Ｃ工程；プリント基板上にディスペンス、スクリーン印刷ないしステンシル印刷で前記の〔１〕〜〔６〕のいずれかに記載の導電性ペーストを塗布した上に、半導体素子やチップ部品を搭載し加熱処理して接合する工程（Ｃ）。
【００１１】
〔８〕 前記の〔１〕〜〔６〕のいずれかに記載の導電性ペーストを用いて、次の工程を行って得られたプリント配線板。
Ａ工程；プリント配線板やフレキシブルプリント基板の上に前記の〔１〕〜〔６〕のいずれかに記載の導電性ペーストをパターン塗布し加熱処理して回路や電極を形成する工程（Ａ）、
Ｂ工程；多層基板のスルーホールに前記の〔１〕〜〔６〕のいずれかに記載の導電性ペーストを充填し加熱処理して層間の電気的導通を得る工程（Ｂ）、
Ｃ工程；プリント基板上にディスペンス、スクリーン印刷ないしステンシル印刷で前記の〔１〕〜〔６〕のいずれかに記載の導電性ペーストを塗布した上に、半導体素子やチップ部品を搭載し加熱処理して接合する工程（Ｃ）。
【００１２】
【発明の実施の形態】
以下本発明を詳細に説明する。
本発明の導電性ペーストは、金属粉末（Ａ）と樹脂（Ｂ）と硬化剤（Ｃ）を有効成分として含有する導電性ペーストであって、前記の樹脂（Ｂ）が、１分子中に少なくとも１個以上の−ＣＯＯＨ基を有する樹脂（ｂ１）、または潜在性−ＣＯＯＨ基発生化合物（ｂ２）であり、硬化剤（Ｃ）が１分子中に少なくとも２個以上のビニル（チオ）エーテル結合を有する化合物であることを特徴とする。
ここで、本発明に用いる前記の金属粉末（Ａ）は、通常の導電性ペーストに用いられる高電気伝導度を有する金属粉末が原料として使用できる。前記の金属粉末を構成する金属元素種としては、具体的には例えば、Ａｇ（銀）、Ａｕ（金）、Ｃｕ（銅）、Ａｌ（アルミニウム）、Ｎｉ（ニッケル）、Ｐｔ（白金）、およびＰｄ（パラジウム）が挙げられ、さらにそれらの合金が好ましく挙げられる。さらに、本発明の効果を損なわない範囲において、前記の金属や合金よりも電気伝導度の低い金属元素種と、その合金を含有していても差し支えない。
合金としては、具体的には例えば、Ａｇ−Ｐｄ、Ａｕ−Ｐｄ、Ａｕ−Ｐｔ、Ｐｔ−Ｐｄ、Ａｇ−Ｎｉ、Ａｕ−Ａｇ、Ａｇ−Ｃｕ、Ｃｕ−Ｓｎ（錫）、Ｃｕ−Ｚｎ（亜鉛）等の合金が挙げられる。異種の金属を表面に被覆した金属粉末、例えばＡｇ被覆Ｃｕ、Ｓｎ被覆Ｃｕ等を用いても差し支えない。
また、異種の金属からなる複数の金属粉末を混合して使用して差し支えない。特に、少量のＰｄ粉末やＺｎ（亜鉛）粉末のＡｇ粉末への添加は、必要に応じてマイグレーション防止や酸化防止の観点から好適に用いることができる。
前記の金属粉末（Ａ）としては、化学還元粉、アトマイズ粉、粉砕粉、電解粉等、各種の調製法によって製造された金属粉末を用いることができる。また、金属粉の形状は、鱗片状粉、粒状粉、球形粉、樹枝状粉、角状粉等の形状の金属粉末を単独または混合して用いることができる。電気的抵抗を減じるためには、鱗片状粉、樹枝状粉の使用が好ましいが、電気抵抗性能の極端な低下を避けながら得られる導電性ペーストの粘度を減じるためには、球状粉の部分配合が好ましい。
前記の金属粉末（Ａ）の粒径は、好ましくは０．２〜５０μｍであり、さらに好ましくは０．５〜２０μｍである。
【００１３】
本発明で用いる樹脂（Ｂ）は、次の（１）１分子中に少なくとも１個以上の−ＣＯＯＨ基を有する樹脂（ｂ１）、または（２）潜在性−ＣＯＯＨ基発生化合物（ｂ２）の型の樹脂が挙げられる。
ここで、前記の１分子中に少なくとも１個以上の−ＣＯＯＨ基（カルボキシル基という場合もある）を有する樹脂（ｂ１）としては、カルボキシル基を有していればよく、特に限定されない。入手性等から、カルボキシル基含有の（メタ）アクリル系樹脂が好適に用いられる。（メタ）アクリル系樹脂としては、エチレン性不飽和カルボン酸を機能成分として、これに（メタ）アクリル酸エステル等の共重合可能な単量体を共重合したアクリル系共重合体を用いてもよい。
ここで、エチレン性不飽和カルボン酸としては、例えば、アクリル酸、メタクリル酸、クロトン酸等のモノカルボン酸が好適に用いられ、さらにそのほか、マレイン酸、フマル酸、イタコン酸等のジカルボン酸、あるいはそれらの無水物やハーフエステルも用いることができる。これらの単量体は、１種単独で又は２種以上混合して使用できる。これらの中では、アクリル酸とメタクリル酸が共重合反応の設計容易性の点から好適である。
【００１４】
（メタ）アクリル酸エステルとしては、メチル（メタ）アクリレート、エチル（メタ）アクリレート、プロピル（メタ）アクリレート、ブチル（メタ）アクリレート、ヘキシル（メタ）アクリレート等の直鎖アルキル（メタ）アクリレート；２−エチルヘキシル（メタ）アクリレート等の分岐アルキル（メタ）アクリレート；シクロヘキシル（メタ）アクリレート等の脂環式（メタ）アクリレート；ベンジル（メタ）アクリレート等の芳香族基含有（メタ）アクリレート；ヒドロキシエチル（メタ）アクリレート、ヒドロキシプロピル（メタ）アクリレート等の水酸基含有（メタ）アクリレート；ジメチルアミノエチル（メタ）アクリレート等の含窒素（メタ）アクリレート；グリシジル（メタ）アクリレート等の反応性基含有（メタ）アクリレートが挙げられる。なおここで「（メタ）アクリレート」はアクリレートおよび／またはメタアクリレートを意味する。
【００１５】
さらに前記の（メタ）アクリル酸エステル以外の共重合可能な単量体としては、具体的には例えば、（メタ）アクリルアミド、ジアセトンアクリルアミド等のアミド系単量体；スチレン、α−メチルスチレン等のスチレン系単量体；酢酸ビニル、アルキルビニル（チオ）エーテル等のビニルエステルあるいはエーテル系単量体；（メタ）アクリロニトリル等の単量体が挙げられる。
これらの単量体は、１種単独で、または２種以上混合して使用することができる。
これらの中では、メチルメタクリレートおよびブチルアクリレートが共重合体の機械物性の点から、また、ヒドロキシエチルメタクリレートが共重合体の基材との密着性の点から好適である。
エチレン性不飽和カルボン酸とこれに（メタ）アクリル酸エステル等の共重合可能な単量体を共重合したものを、前記の１分子中に少なくとも１個以上のカルボキシル基を有する樹脂（ｂ１）とする場合には、１分子中に少なくとも１個以上のカルボキシル基を有する樹脂共重合体を共重合によって生成させるために、｛単量体単位の平均カルボキシル基数×生成樹脂の重合度｝が１以上になるように、｛エチレン性不飽和カルボン酸のモル数／全単量体のモル数｝の比率と、樹脂共重合体の分子量を考慮して調整すればよい。
前記の｛エチレン性不飽和カルボン酸のモル数／全単量体のモル数｝の比率は、これに限定されないが、本発明の導電性ペーストの組成に用いる、前記の１分子中に少なくとも１個以上のビニル（チオ）エーテル基を有する化合物（Ｃ）との混和性や、導電性ペースト用として通常用いられる有機溶媒への溶解度を考慮すると、０．４５を越えないことが好ましい。
前記の１分子中に少なくとも１個以上のカルボキシル基を有する樹脂（ｂ１）としては、前記のカルボキシル基含有の（メタ）アクリル系樹脂以外に、さらに、カルボキシル変成ポリエステル樹脂、カルボキシル変成ポリアミド樹脂、カルボキシル変成ポリウレタン樹脂、カルボキシル変成エポキシ樹脂等のカルボキシル基を有する樹脂を用いることもできる。
前記の１分子中に少なくとも１個以上のカルボキシル基を有する樹脂（ｂ１）は、１種単独で、または２種以上混合して使用することができる。
【００１６】
前記のＢ成分の樹脂のもう１つの潜在性−ＣＯＯＨ基発生化合物（ｂ２）としては、前記の１分子中に少なくとも１個以上のカルボキシル基を有する樹脂（ｂ２）のカルボキシル基にビニル（チオ）エーテル化合物を付加させた構造を有する化合物が挙げられる。
この潜在性カルボキシル基の構造としては、次の式（２）で表される。
【００１７】
【化３】

【００１８】
［式中のＲ^１、Ｒ^２及びＲ^３は、それぞれ水素原子又は炭素数１〜１８の有機基、Ｒ^４は炭素数１〜１８の有機基であって、Ｒ^３とＲ^４はたがいに結合してＹをヘテロ原子とする複素環を形成していてもよく、Ｙは酸素原子又はイオウ原子である。］
【００１９】
前記の構造を有する潜在性−ＣＯＯＨ基発生化合物（ｂ２）としては、次の（ｉ）と（ｉｉ）の２つの考え方がある。
（ｉ）前記の１分子中に少なくとも１個以上のカルボキシル基を有する樹脂（ｂ１）に対して、ビニル（チオ）エーテル化合物を付加させて潜在性−ＣＯＯＨ基発生化合物の樹脂を得る。
（ｉｉ）予めカルボキシル基を有する単量体とビニル（チオ）エーテル化合物を付加反応させて潜在性−ＣＯＯＨ基として得た後、前記の単量体を重合することによって潜在性−ＣＯＯＨ基発生化合物の樹脂を得る。
前記の（ｉ）と（ｉｉ）の方法では、樹脂のカルボキシル基に対するビニル（チオ）エーテルの付加よりも単量体のカルボキシル基に対するビニル（チオ）エーテル付加の方が、反応速度が高いので、カルボキシル基を有する単量体化合物に対して、ビニル（チオ）エーテル化合物を付加させて得る（ｉｉ）の場合の方が、反応時間の観点からはより好適である。
前記の反応は、例えば、下記式（３）で示される。（なお、ここでＲ^１，Ｒ^２，Ｒ^３、Ｒ^４およびＹは前記と同じである。）
【００２０】
【化４】

【００２１】
潜在性−ＣＯＯＨ基発生化合物（ｂ２）を得るために使用するビニル（チオ）エーテル化合物としては、例えば、脂肪族ビニルエーテル化合物、脂肪族ビニルチオエーテル化合物、環状ビニルエーテル化合物、または環状ビニルチオエーテル化合物脂肪族が挙げられる。
前記の脂肪族ビニルエーテル化合物としては、具体的には例えば、メチルビニルエーテル、エチルビニルエーテル、イソプロピルビニルエーテル、ｎ−プロピルビニルエーテル、ｎ−ブチルビニルエーテル、イソブチルビニルエーテル、２−エチルヘキシルビニルエーテル、シクロヘキシルビニルエーテル、ジエチレングリコールモノビニルエーテル等のモノビニルエーテル化合物；ブタンジオールジビニルエーテル、シクロヘキサンジオールジビニルエーテル、シクロヘキサンジメタノールジビニルエーテル、ジエチレングリコールジビニルエーテル、トリエチレングリコールジビニルエーテル、テトラエチレングリコールジビニルエーテル、エチレングリコールジビニルエーテル、ヘキサンジオールジビニルエーテル、等のジビニルエーテル化合物；トリメチロールプロパントリビニルエーテル等のトリビニルエーテル化合物；ペンタエリスリトールテトラビニルエーテル等テトラビニルエーテル化合物；ヒドロキシエチルビニルエーテル、ヒドロキシブチルビニルエーテル等ヒドロキシアルキルビニルエーテル化合物等の脂肪族ビニルエーテル化合物が挙げられ、さらに前記の脂肪族ビニルエーテル化合物に対応する脂肪族ビニルチオエーテル化合物が挙げられる。
さらには、環状ビニルエーテル化合物として、例えば、２，３−ジヒドロフラン、３，４−ジヒドロフラン、２，３−ジヒドロ−２Ｈ−ピラン、３，４−ジヒドロ−２Ｈ−ピラン、３，４−ジヒドロ−２−メトキシ−２Ｈ−ピラン、３，４−ジヒドロ−４，４−ジメチル−２Ｈ−ピラン−２−オン、３，４−ジヒドロ−２−エトキシ−２Ｈ−ピラン、３，４−ジヒドロ−２Ｈ−ピラン−２−カルボン酸ナトリウム等の環状ビニルエーテル化合物が挙げられ、さらに前記の環状ビニルエーテル化合物に対応する環状ビニルチオエーテル化合物等が挙げられる。
これらのなかでも、硬化剤（Ｃ）とのヘミアセタールエステル交換反応の平衡をずらせて良好な硬化物を得るためには、イソプロピルビニルエーテル、ｎ−プロピルビニルエーテル、ｎ−ブチルビニルエーテルが好ましく挙げられる。
前記の（ｉ）および（ｉｉ）の方法においては、多官能ビニルエーテルを多量に
使用すると、通常架橋してゲル化するので、ゲル化しない程度の少量を用いることが望ましい。
【００２２】
前記の１分子中に少なくとも１個以上のカルボキシル基を有する樹脂（ｂ１）の酸価は、導電性ペーストの硬化物の物性および導電性の点から、好ましくは１０ｍｇＫＯＨ／ｇ以上であり、さらに好ましくは２５ｍｇＫＯＨ／ｇ以上である。
同じく、前記の構造を有する潜在性−ＣＯＯＨ基発生化合物（Ｂ２）の潜在的カルボキシル基は、ビニル（チオ）エーテル化合物とのヘミアセタール結合を形成しているカルボキシル基を定量する酸当量として、導電性ペーストの硬化物の物性および導電性の点から、好ましくは１０ｍｇＫＯＨ／ｇ以上であり、さらに好ましくは２５ｍｇＫＯＨ／ｇ以上である。
【００２３】
本発明で用いるＢ成分の樹脂としては、前記の１分子中に少なくとも１個以上の−ＣＯＯＨ基を有する樹脂（Ｂ１）、または潜在性−ＣＯＯＨ基発生化合物（Ｂ２）のいずれかである樹脂（Ｂ）の分子量は、本発明の導電性ペーストの硬化物の電気伝導度と物性の観点からは、重量平均分子量値で３００〜１０００００が好ましい。さらに非曳糸性等の導電性ペーストの塗工性を考慮すると重量平均分子量値で８０００〜４００００が好適である。
【００２４】
本発明で用いるＣ成分の硬化剤としては、前記の１分子中に少なくとも２個以上のビニル（チオ）エーテル結合を有する化合物であり、硬化剤（Ｃ）としては、例えば、前記のｂ２成分の例示で示した脂肪族ビニルエーテル化合物、脂肪族ビニルチオエーテル化合物、環状ビニルエーテル化合物、または環状ビニルチオエーテル化合物脂肪族が同様に挙げられる。
【００２５】
これらのなかでも、前記の樹脂（Ｂ）とヘミアセタールエステル化反応またはヘミアセタールエステル交換反応の平衡を移動させ良好な硬化物を得るためには、ブタンジオールジビニルエーテル、シクロヘキサンジメタノールジビニルエーテル、トリエチレングリコールジビニルエーテルが好ましく挙げられる。
【００２６】
本発明の導電性ペーストにおいて、前記の金属（Ａ）の配合量は、導電性ペースト全体から溶剤のみを差し引いたもの１００重量部に対して、好ましくは７７〜９７重量部、さらに好ましくは８２〜９２重量部である。本発明の導電性ペーストの抵抗値は、極小値から離れるにつれて増加性を増すので、前記範囲の外での金属（Ａ）の配合は、実用上好ましくない。
導電性ペースト中の前記の樹脂（Ｂ）と硬化剤（Ｃ）の配合比は、｛硬化剤（Ｃ）のビニル基のモル当量／樹脂（Ｂ）の酸モル当量｝の比で０．１〜１０の比率が好ましい。この比率が０．１未満であると、前記の樹脂（Ｂ）と硬化剤（Ｃ）の作用分子の絶対数が少なく、導電性ペーストを硬化した場合に、十分な硬化物性が得られない。また、作用上モル比で過剰となる硬化剤（Ｃ）は溶剤として働き、その大部分が揮散するが、この比率が１０を越える場合には、硬化剤（Ｃ）の可塑化作用および硬化剤（Ｃ）自身の重合反応が硬化物の物性および導電性能へ悪影響を及ぼす場合があり、好ましくない。
【００２７】
本発明の導電性ペーストに用いる溶剤としては、特に限定されない。通常の汎用溶媒の中から適宜選択して使用することができる。溶媒としては、具体的には例えば、ドデカン、テトラデセン、ドデシルベンゼン等の脂肪族炭化水素；トルエン、キシレン等の芳香族炭化水素；メタノール、エタノール、２−プロパノール（イソプロパノール）、α−テルピネオール、ベンジルアルコール、２−ヘキシルデカノール等のアルコール；酢酸エチル、乳酸エチル、酢酸ブチル、安息香酸ブチル、アジピン酸ジエチル、フタル酸ジエチル等のエステル類；１，４−ジオキサン、テトラヒドロフラン等のエーテル類；メチルエチルケトン、メチルイソブチルケトン等のケトン類；トリエチレングリコールモノメチルエーテル、ジエチレングリコールモノメチルエーテル、ジエチレングリコールモノブチルエーテル、ジエチレングリコールモノヘキシルエーテル、プロピレングリコールモノエチルエーテルアセテート、エチレングリコールモノフェニルエーテル、ジエチレングリコールモノフェニルエーテル、ジプロピレングリコール、ジエチレングリコール−２−エチルヘキシルエーテル、テトラエチレングリコールジメチルエーテル等のグリコール誘導体；シクロヘキサノン、シクロヘキサノール等の脂環式炭化水素類；石油エーテル、ナフサ等の石油系溶剤が挙げられる。
好ましくは、プロピレングリコールモノエチルエーテルアセテート、テトラエチレングリコールジメチルエーテル等が挙げられる。
前記の溶剤の使用量は、特に制限されないが、電気伝導度に影響を及ぼす塗布性の点から、前記の金属粉末（Ａ）と樹脂（Ｂ）と硬化剤（Ｃ）を含む導電性ペーストの溶剤以外の合計１００重量部に対して、５０〜３００重量部の溶剤の添加が好ましい。
なお、前記のようにビニルエーテル化合物が過剰に配合された場合には、ビニルエーテル化合物が溶剤としても作用する。
【００２８】
本発明の導電性ペーストには、さらに導電性を向上させるために、さらにジチオカルバミン酸基、ジスルフィド基、メルカプト基、およびチオウレア基からなる群より選択される基を有する硫黄化合物（Ｄ）を配合することが望ましい。
前記の硫黄化合物（Ｄ）としては、次の（ｉ）〜（ｉｖ）の硫黄化合物（Ｄ）を挙げることができる。
（ｉ）ジチオカルバミン酸基を有する硫黄化合物（Ｄ）としては、ジベンジルジチオカルバミン酸亜鉛、ペンタメチレンジチオカルバミン酸ピペリジン塩、ジブチルジチオカルバミン酸亜鉛、Ｎ−エチル−Ｎ−フェニルジチオカルバミン酸亜鉛、Ｎ−ペンタメチレンジチオカルバミン酸亜鉛等のジチオカルバミン酸基を有する化合物、
（ｉｉ）ジスルフィド基を有する硫黄化合物（Ｄ）としては、ジスルフィド基を有する硫黄化合物（Ｄ）としては、テトラメチルチウラムジスルフィド、テトラエチルチウラムジスルフィド、テトラブチルチウラムジスルフィド、テトラキス（２−エチルヘキシル）チウラムジスルフィド等のジスルフィド基を有する化合物、
（ｉｉｉ）メルカプト基を有する硫黄化合物（Ｄ）としては、ジ−２−ベンゾチアゾリルジスルフィド、２−メルカプトイミダゾリン、メルカプトベンゾチアゾール、２−メルカプトベンゾチアゾールの亜鉛塩、２−メルカプトベンゾチアゾールのシクロヘキシルアミン塩等のメルカプト基を有する化合物、
（ｉｖ）チオウレア基を有する硫黄化合物（Ｄ）としては、Ｎ，Ｎ´−ジフェニルチオ尿素、Ｎ，Ｎ´−ジエチルチオ尿素、トリメチルチオ尿素、Ｎ，Ｎ´−ジブチルチオ尿素、Ｎ，Ｎ´−ジラウリルチオ尿素等のチオウレアを有する化合物、
前記の硫黄化合物（Ｄ）は、１種単独で、または、２種以上を混合して用いることができる。
前記の硫黄化合物（Ｄ）は、バインダー重量｛金属粉末以外の導電性ペースト成分の総重量をいう｝１００重量部に対して、好ましくは０．１〜５．０重量部を、さらに好ましくは０．５〜０．２５重量部を使用することができる。前記の硫黄化合物（Ｄ）が、０．１重量部未満の配合では、導電性ペースト硬化物の導電性能に対する好ましい効果が小さすぎ、５．０重量部を越えると導電性ペースト硬化物の機械的物性に悪影響を及ぼすので好ましくない。
【００２９】
本発明の導電性ペーストには、本発明の効果を損なわない範囲で必要に応じてさらに添加物として、チクソ性付与剤、キレート剤、カップリング剤、分散安定剤、レベリング剤、粘着性付与剤、顔料、消泡剤、腐食防止剤、難燃剤等の各種添加剤を用いることができる。
【００３０】
本導電性ペーストの製造は、一括ないし逐次で前記の成分を投入して、羽根型撹拌機、デソルバー、ニーダー、らいかい機、ボールミル混和機、ロール分散機等を用いて、通常の方法で混合を行えばよい。混合の温度は、配合成分にもよるが、通常、結露や溶剤の揮散をさけるため、１０〜３０℃が好ましい。
【００３１】
本発明の導電性ペーストにおいて、前記の１分子中に少なくとも１個以上のカルボキシル基を有する樹脂（Ｂ）と、１分子中に少なくとも１個以上のビニルエーテル基を有する化合物（Ｃ）とを加熱処理してペースト硬化物を形成させる。その際には、加熱処理条件下で、さらに反応速度を上げるために触媒を用いてもよい。その触媒としては、具体的に例えば、Ｎ，Ｎ−ジメチルホルムアミド、Ｎ，Ｎ−ジメチルアセトアミド、Ｎ−メチルピロリドン等の含窒素化合物；ヘキサメチルリン酸トリアミド、またはリン酸トリメチルやリン酸トリエチルのようなリン酸トリアルキル等の化合物やさらにジメチルスルホキシドを用いることができる。これら触媒の添加量は、前記の樹脂（Ｂ）と硬化剤（Ｃ）の総量１００重量部に対して０〜３重量部が好ましい。
十分な加熱処理時間が許容され、作用速度を上げる必要が無い場合は、前記の触媒の配合量は、必要に応じて導電性ペースト硬化物の信頼性をさらに向上させるため、前記の樹脂（Ｂ）と硬化剤（Ｃ）の総量１００重量部に対して０．２重量部以下にするのが好ましい。
【００３２】
本発明の導電性ペーストの使用方法としては、前記の導電性ペーストを用いて、プリント配線板に導通部分を形成することができる。本発明の配線板は、次の工程の少なくとも１つの工程を行うことにより得られる。
Ａ工程；プリント配線板やフレキシブルプリント基板の上にパターン塗布し加熱処理して回路や電極を形成する工程（Ａ）、
Ｂ工程；多層基板のスルーホールに充填し加熱処理して層間の電気的導通を得る工程（Ｂ）、
Ｃ工程；プリント基板上にディスペンス、スクリーン印刷ないしステンシル印刷で塗布した上に、あるいは、半導体素子やチップ部品を搭載し加熱処理して接合する工程（Ｃ）
本発明の導電性ペーストの使用方法は、導電性ペーストとして、本発明の導電性ペーストを用いる以外、各工程を公知の方法及び条件で行うことができる。
【００３３】
また、本発明のプリント配線板は、前記の導電性ペーストを用いて、次の工程を行って得られたプリント配線板である。
Ａ工程；プリント配線板やフレキシブルプリント基板の上に前記の〔１〕〜〔６〕のいずれかに記載の導電性ペーストをパターン塗布し加熱処理して回路や電極を形成する工程（Ａ）、
Ｂ工程；多層基板のスルーホールに前記の〔１〕〜〔６〕のいずれかに記載の導電性ペーストを充填し加熱処理して層間の電気的導通を得る工程（Ｂ）、
Ｃ工程；プリント基板上にディスペンス、スクリーン印刷ないしステンシル印刷で前記の〔１〕〜〔６〕のいずれかに記載の導電性ペーストを塗布した上に、半導体素子やチップ部品を搭載し加熱処理して接合する工程（Ｃ）。
このようにして、本発明の導電性ペーストを、一般的な方法で、例えば配線基板上にパターン塗布し加熱処理したり、多層基板のスルーホールに充填したり、あるいはプリント基板上にディスペンス、スクリーン印刷ないしステンシル印刷して、加熱処理することにより、配線基板上の導電性の必要な箇所に導通部分を作成することができるので、産業上有用である。特にその導電性能に優れ、塗布後、溶剤の除去・硬化等の容易な方法で処理できるので、汎用に使用できる。
【００３４】
【実施例】
次に実施例に基づいて本発明をより詳細に説明する。次に本発明で用いた測定方法を示す。
［測定方法］
１．＜粘度＞ 硬化前のペースト粘度は、循環式恒温水浴を装備した（株）トキメック製Ｅ型粘度計ビスコニックＥＨＤを用いて温度２５℃で測定した。
【００３５】
２．＜体積抵抗率＞ ペーストの体積抵抗率は、ＪＩＳ Ｋ７１９４「導電性プラスチックの４探針法による低抵抗試験方法」に準じて、４端子４探針法によって抵抗率の測定を行う。試料は、ガラス板上にセロハンテープのガイドラインを用いて、１×５ｃｍのペーストのラインを塗布形成し、１５０℃で３０分間熱処理した後、三菱化学（株）製ロレスタＧＰ ＭＣＰ−Ｔ６００型にＡＳＰプローブを接続し、得られたバルク抵抗値を、マイクロメータによって測定した試料厚みで除し、体積抵抗率を得た。
体積抵抗率の高温耐性および高温高湿耐性は、初期性能に対する抵抗率の増加をもって判定を行った。
◎…優れた耐性を有する（初期性能に対して１０％未満の抵抗率増加）
○…十分な耐性を有する（１０％以上、１５％未満）
△…実用上やや問題あり（１５％以上、２０％未満）
×…実用上問題あり（２０％以上）
【００３６】
３．＜碁盤目剥離試験＞
ガラス基材に対する密着性を、ＪＩＳ Ｋ ５６００−５−６：１９９９「塗料一般試験方法−第５部：塗膜の機械的性質−第６節：付着性（クロスカット法）」の碁盤目剥離試験によって調べた。カッターガイドのすきま間隔は２ｍｍとした。判定方法は次の通りとした。
◎…優れた密着性を有する（剥がれない碁盤目数／全碁盤目数（１００）＝１００／１００）
○…十分な密着性を有する（９０〜９９／１００）
△…実用上やや問題あり（８０〜８９／１００）
×…実用上問題あり（７９以下／１００）
【００３７】
４．＜固着強度試験＞ 固着強度は、１６０８チップ部品搭載を模し、縦０．８ｍｍ×横０．８ｍｍのランド、ランド間隔０．４ｍｍのレジスト抜きしたガラスエポキシ基板上の銅箔ランドパターンの上に、縦０．８ｍｍ×横０．４ｍｍのランド、ランド間隔０．４ｍｍのランドパターンを形成した５０μｍ厚メタルマスクを用いて、導電性ペーストをステンシル印刷し、その上に１６０８ダミーチップ部品を搭載した後、前記の条件で加熱処理を行った。この基板上に導電性ペーストで接合されたダミー部品に対して、ＤＡＧＥ社製万能ボンドテスター４０００を用いて、日本電子機械工業会暫定規格ＲＣＸ−０４１４／１０２「表面実装部品の機械的強度試験方法」に準じて、部品の横押し試験を行い、測定した。ただし、クリープモードではなく破壊モードを採り、降伏点をもって固着強度とした。判定方法は次の通りとした。
◎…優れた固着性を有する（固着強度＝１０Ｎ以上〜）
○…十分な固着性を有する（９Ｎ以上〜１０Ｎ未満）
△…実用上やや問題あり（８Ｎ以上〜９Ｎ未満）
×…実用上問題あり（〜８Ｎ未満）
【００３８】
５．＜高温耐性＞ １２５℃の恒温槽中に前述の固着強度試験試料および体積抵抗率試験試料を設置し、５００時間後の固着強度および体積抵抗率の変化を測定した。
６．＜高温高湿耐性＞ １２１℃／９７％ＲＨ／２．３ａｔｍに保ったＰＣＴ試験装置内に前述の前述の固着強度試験試料および体積抵抗率試験試料を設置し、２４時間後の固着強度および体積抵抗率の変化を測定した。
【００３９】
［合成例１］アクリル系樹脂の重合
滴下漏斗、攪拌機、窒素ガス導入管、還流冷却器を備えた５００ｍＬの四つ口フラスコ内を窒素ガスで置換した後、キシレン５０ｇとプロピレングリコールモノメチルエーテルアセテート（ＰＭＡ）１００ｇを入れ、滴下漏斗から、メタクリル酸（ＭＡＡ）７ｇ、メタクリル酸メチル（ＭＭＡ）３５ｇ、アクリル酸ブチル（ＢＡ）５５ｇ、メタクリル酸２−ヒドロキシエチル（ＨＥＭＡ）３ｇ、およびｔ−ブチルペルオキシイソプロピルカーボネート（商品名：パーブチルＩ、日本油脂（株）製、純度９５％）１ｇの混合物１０１ｇを１３０℃で５時間かけて均一速度で滴下した。その後、ｔ−ブチルペルオキシイソプロピルカーボネート１ｇを添加し、１３０℃で２時間未反応単量体の転化を行い、粘性溶液２５０ｇを得た。得られた樹脂（Ｂ−１）は、固形分３９％、固形分換算酸価４２ｍｇＫＯＨ／ｇ、重量平均分子量４２，１００であった。これらの値を換算すると、この樹脂樹脂１分子中には平均で３２個のカルボキシル基が存在することになる。
【００４０】
［比較合成例２］アクリル系樹脂の重合
合成例１と同じ反応装置を用い、フラスコ内を窒素ガスで置換した後、キシレン１５０ｇを入れ、滴下漏斗から、ＭＡＡ０．７ｇ、ＭＭＡ４１．３ｇ、ＢＡ５５ｇ、ＨＥＭＡ３ｇ、およびｔ−ブチルペルオキシ２−エチルヘキサノエート（商品名：パーブチルＯ、日本油脂（株）製、純度９５％）１４ｇの混合物１１４ｇ、１３０℃で５時間かけて均一速度で滴下した。その後、ｔ−ブチルペルオキシイソプロピルカーボネート１ｇを添加し、１３０℃で２時間未反応単量体の転化を行い、粘性溶液２６５ｇを得た。得られた樹脂（Ｂ′−１）は、固形分４０％、固形分換算酸価４．１ｍｇＫＯＨ／ｇ、重量平均分子量９，４００であった。これらの値を換算すると、この樹脂樹脂１分子中には平均で０．７個のカルボキシル基が存在することになる。
【００４１】
［合成例３］潜在性カルボキシル基含有単量体の合成
温度計、還流冷却器、キャピラリ導入管、攪拌機を備えた５００ｍＬの四ツ口フラスコに、メタクリル酸（ＭＡＡ）１７２．２ｇ、ｎ−プロピルビニルエーテル（ｎＰＶＥ）２２３．９ｇ、酸性りん酸エステル触媒（モノ−２−エチルヘキシルホスフェート、ジ−２−エチルヘキシルホスフェート、トリス−２−エチルヘキシルホスフェートの混合物、商品名：ＡＰ−８、大八化学工業（株）製）２．０ｇ、ヒドロキノンモノメチルエーテル（和光純薬工業（株）製）０．５ｇを仕込み、キャピラリ導入管から２０ｍＬ／ｍｉｎの導入量で空気を導入しながら、常温から６０℃まで昇温させた後、６０℃で６時間反応させた。混合液の酸価が５以下であることを確認し、反応を停止させた。この混合溶液３９９．６ｇに分液ろうと中で１０％炭酸ナトリウム水溶液５０ｍＬを用いて洗浄を行い、有機層に合成けい酸マグネシウム（商品名：キョーワード６００、協和化学工業（株）製）２．０ｇを加え撹拌した後、濾過し、ロータリーエバポレータを用い、濾液から未反応物を留去し、潜在性カルボキシル基含有単量体（Ｍ−１）３４０．２ｇを得た。ＧＣ分析を行ったところ、ＭＡＡのｎＰＶＥヘミアセタールエステル純度は９８．７％であった。
【００４２】
［合成例４］アクリル系樹脂の重合
合成例１と同じ反応装置を用い、合成例１で用いたＭＡＡ７ｇとＢＡ５５ｇに代えて、合成例３で合成した潜在性カルボキシル基含有単量体（Ｍ−１）１４ｇとＢＡ４１ｇを用いた以外は、合成例１と全く同じ条件で合成操作を行った。粘性溶液２５０ｇを得た。得られた樹脂（Ｂ−２）は、固形分３９％、固形分換算加水分解酸価４０ｍｇＫＯＨ／ｇ、重量平均分子量４３，５００であった。これらの値を換算すると、この樹脂樹脂１分子中には平均で３１個のカルボキシル基が存在することになる。
【００４３】
実施例１
フレーク状銀粉（商品名：シルベストＴＣＧ−１、徳力化研（株）製、平均粒径１．９μｍ、タップ密度３．１ｇ／ｃｍ^３）（Ａ−１）３．８４ｇと、合成例１で得られたカルボキシル基含有樹脂の溶液（Ｂ−１）１．１３ｇと、トリエチレングリコールジビニルエーテル（ＴＥＧＤＶＥ、日本カーバイド工業（株）製）０．２３ｇと、プロピレングリコールモノメチルエーテルアセテート（ＰＭＡ、（株）クラレ製）０．４５ｇと、カスターワックス０．０３ｇ（予め、Ｂ−１溶液に８０℃に加熱下で溶解しておく）と、キレート剤としての亜鉛アセチルアセトナート一水和物（同仁化学研究所（株）製）０．０２ｇを合わせ、（株）シンキー製ペースト混練器ＡＲＶ−２００を用いて、１７秒間を２サイクル自転公転混合し、粘度３８０ｄＰａ・ｓｅｃの導電性ペーストを得た。組成を表−１に示す。また前記の組成物を用いて前記の試験方法、評価方法で評価した。塗布または印刷したペーストは、７０℃で１０分間予備乾燥した後、１５０℃で３０分間の条件で加熱処理を行った。結果を表−１に示す。
【００４４】
実施例２
実施例１において用いた銀粉に替えて、フレーク状銀粉（商品名：シルコートＡｇＣ−Ａ、福田金属箔粉鉱業（株）製、平均粒径３．５μｍ、タップ密度３．３ｇ／ｃｍ^３）（Ａ−２）を同量用いた以外は、実施例１と全く同じ操作を行った。前記の操作により粘度２３０ｄＰａ・ｓｅｃの導電性ペーストを得た。また、前記の組成物を用いて前記の試験方法、評価方法で評価した。加熱処理の条件も実施例１と全く同じにして行った。組成と結果を表−１に示す。
【００４５】
実施例３
実施例１において用いた樹脂溶液（Ｂ−１）に替えて、市販のポリエステル系カルボキシル基含有樹脂（商品名：ファインディックＭ８９６２、大日本インキ化学工業（株）製、酸価３５ｍｇＫＯＨ／ｇ）をＰＭＡに溶解し、３９％濃度としたもの（Ｂ´−２）を実施例１の（Ｂ−１）と同量用いた以外は、実施例１と全く同じ操作および評価を行った。この樹脂１分子中には平均で６個のカルボキシル基が存在することになる。組成と結果を表−１に示す。導電性ペーストの粘度は３４０ｄＰａ・ｓｅｃであった。
【００４６】
比較例１
実施例１において用いた樹脂溶液（Ｂ−１）に替えて、合成例２で得られた樹脂溶液（Ｂ´−１）を同量用いた以外は、実施例１と全く同じ操作を行った。前記の操作により粘度３５０ｄＰａ・ｓｅｃの導電性ペーストを得た。また、前記の組成物を用いて前記の試験方法、評価方法で評価した。加熱処理の条件も実施例１と全く同じにして行った。組成と結果を表−１に示す。
【００４７】
比較例２
実施例２において用いた樹脂溶液（Ｂ−１）に替えて、合成例２で得られた樹脂溶液（Ｂ´−２）を同量用いた以外は、実施例２と全く同じ操作を行った。前記の操作により粘度１８０ｄＰａ・ｓｅｃの導電性ペーストを得た。また、前記の組成物を用いて前記の試験方法、評価方法で評価した。加熱処理の条件も実施例１と全く同じにして行った。組成と結果を表−１に示す。
【００４８】
比較例３
実施例３において用いた樹脂溶液（Ｂ−２）に替えて、市販のポリエステル系カルボキシル基含有樹脂（商品名：ＧＫ７８０、東洋紡（株）製、酸価５ｍｇＫＯＨ／ｇ）をＰＭＡに溶解し、３９％濃度としたもの（Ｂ´−２）を実施例１の（Ｂ−１）と同量用いた以外は、実施例３と全く同じ操作を行った。この樹脂１分子中には平均で０．５個のカルボキシル基が存在することになる。前記の操作により粘度３８０ｄＰａ・ｓｅｃの導電性ペーストを得た。また、前記の組成物を用いて前記の試験方法、評価方法で評価した。加熱処理の条件も実施例１と全く同じにして行った。組成と結果を表−１に示す。
【００４９】
【表１】

【００５０】
実施例４
フレーク状銅粉（商品名：１３００ＹＰ、三井金属鉱業（株）製、平均粒径５．７μｍ、タップ密度３．９ｇ／ｃｍ^３）（Ａ−３）８．５１ｇと、合成例４で得られた樹脂溶液（Ｂ−２）１．５８ｇと、シクロヘキサンメタノールジビニルエーテル（ＣＨＤＶＥ、日本カーバイド工業（株）製）０．３３ｇと、プロピレングリコールモノメチルエーテルアセテート（ＰＭＡ、（株）クラレ製）０．４７ｇと、酸性りん酸エステル触媒（モノ−２−エチルヘキシルホスフェート、ジ−２−エチルヘキシルホスフェート、トリス−２−エチルヘキシルホスフェートの混合物、商品名：ＡＰ−８、大八化学工業（株）製）０．００８ｇを合わせ、（株）シンキー製ペースト混練器ＡＲＶ−２００を用いて、１７秒間を２サイクル自転公転混合し、粘度２２０ｄＰａ・ｓｅｃの導電性ペーストを得た。組成を表−２に示す。また前記の組成物を用いて前記の試験方法、評価方法で評価した。ただし、塗布または印刷したペーストは、７０℃で１０分間予備乾燥した後、１５０℃で３０分間の条件で加熱処理を行った。結果を表−２に示す。
【００５１】
比較例４
実施例４において用いた樹脂溶液（Ｂ−１）に替えて、合成例２で得られた樹脂溶液（Ｂ´−１）を同量用いた以外は、実施例３と全く同じ操作を行った。前記の操作により粘度２４０ｄＰａ・ｓｅｃの導電性ペーストを得た。組成を表−２に示す。また前記の組成物を用いて前記の試験方法、評価方法で評価した。加熱処理の条件も実施例１と全く同じにして行った。結果を表−２に示す。
【００５２】
比較例５
実施例４において、ＴＥＧＤＶＥ０．３３ｇとＰＭＡ０．４７ｇを用いているところを、ＴＥＧＤＶＥを全く用いずにＰＭＡ０．８０ｇ用いた以外は、実施例４と全く同じ操作を行った。前記の操作により粘度２００ｄＰａ・ｓｅｃの導電性ペーストを得た。組成を表−２に示す。また前記の組成物を用いて前記の試験方法、評価方法で評価した。加熱処理の条件も実施例３と全く同じにして行った。組成と結果を表−２に示す。
【００５３】
【表２】

【００５４】
以上の結果より、本発明の実施例１〜４では、優れた体積抵抗率でかつ、優れた密着性が、高温条件および高温高湿条件においても維持持続されていることが判る。また、本発明の範囲外である樹脂（Ｂ′）を用いている比較例１〜４、硬化剤（Ｃ）が本発明の範囲外である比較例５から明らかなように、本発明の要件を満たさない導電性ペーストの配合系では、この優れた性能が得られないことが分かる。
【００５５】
【発明の効果】
本発明の導電性ペーストは、金属粉末（Ａ）と、１分子中に少なくとも１個以上の−ＣＯＯＨ基を有する樹脂（ｂ１）、または潜在性−ＣＯＯＨ基発生化合物（ｂ２）のいずれかである樹脂（Ｂ）と、１分子中に少なくとも２個以上のビニル（チオ）エーテル結合を有する化合物である硬化剤（Ｃ）を含有するので、優れた導電性能、および接着（密着）強度特性とその持続性の２つの性能を両立しうる。したがって、その導電性ペーストを用いたプリント配線板は、優れた密着性を示すので、信頼性に優れ産業上有益である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is used for forming circuits and electrodes on a printed wiring board or a flexible printed board, for joining semiconductor elements and chip components, and for filling through holes and obtaining electrical continuity between layers. The present invention relates to a conductive paste suitable for the method, a method for manufacturing a wiring board using the conductive paste, and a wiring board obtained by the method.
[0002]
[Prior art]
Conductive paste is applied on printed wiring boards and flexible printed boards by pattern application to form circuits and electrodes, or to fill through holes in multilayer boards, or to place semiconductor elements and chip components on them. Used when joining to. In recent years, as electronic devices have become smaller and more sophisticated, the application range of polymer-based conductive pastes has been expanding, but at the same time, the required performance thereof has also been increasing. In particular, there is a demand for the enhancement of two basic performances: basic conductive performance and adhesion (adhesion) strength characteristics and their sustainability, but these performances are highly reciprocal and it is increasingly difficult to achieve both performances. It has become.
Regarding the adhesiveness of the polymer conductive paste, various binder components have been studied to improve the adhesiveness.
For example, JP-A-62-253675 (Patent Document 1) discloses a resin system in which a melamine resin, a polyol and a polyester resin and / or an alkyd resin are mixed at a specific ratio, and JP-A-63-83178. (Patent Document 2) discloses a mixed resin of a melamine resin and an acrylic resin.
Further, JP-A-5-325634 (Patent Document 3) discloses a mixture of a hydroxystyrene-based polymer having a specific molecular weight and a benzoic acid derivative.
Japanese Patent Application Laid-Open No. 7-316474 (Patent Document 4) discloses a polyvinyl butyral resin softened with an ester plasticizer.
Furthermore, Japanese Patent Application Laid-Open No. 2002-161123 (Patent Document 5) discloses a urethane / epoxy combined curable resin.
However, in the above-mentioned technology, in the improvement of the adhesion by these resin systems, the blended resins are not always good in compatibility, and additives such as a low molecular weight plasticizer and a curing agent are added to the surface. Because of the ease of migration, sufficient satisfactory performance has not always been obtained in both the maintenance of adhesion performance and high conductivity.
[0003]
[Patent Document 1] JP-A-62-253675
[Patent Document 2] JP-A-63-83178
[Patent Document 3] JP-A-5-325634
[Patent Document 4] JP-A-7-316474
[Patent Document 5] JP-A-2002-161123
[0004]
[Problems to be solved by the invention]
A first object of the present invention is to provide a conductive paste having both conductive performance and adhesive (adhesion) strength characteristics and sustainability of the performance.
A second object of the present invention is to provide a method for manufacturing a printed wiring board using the conductive paste and a printed wiring board obtained by the method.
[0005]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, (A) a metal powder, (B) a resin having a carboxyl group or a latent carboxyl group-generating compound, and (C) a specific polyvinyl (thio) The use of a conductive paste in which an ether compound is combined and used has led to the achievement of excellent conductive performance and improved adhesion (adhesion) strength characteristics, and the finding that the performance is maintained, thereby completing the present invention.
That is, the present invention provides the following [1] to [7].
[1] A conductive paste containing a metal powder (A), a resin (B), and a curing agent (C) as active ingredients, wherein the resin (B) has at least one-in one molecule. A resin (b1) having a COOH group or a compound having a latent -COOH group (b2), wherein the curing agent (C) is a compound having at least two or more vinyl (thio) ether bonds in one molecule. A conductive paste, characterized in that:
[0006]
[2] The metal powder (A) is a metal element group consisting of Ag (silver), Au (gold), Cu (copper), Al (aluminum), Ni (nickel), Pt (platinum) and Pd (palladium). The conductive paste according to the above [1], which is selected from one kind of metal powder or a metal powder of an alloy of two or more of the above metal elements.
[3] The resin (b1) having at least one or more -COOH groups in one molecule of the resin (B) is a resin (b1) of (meth) acrylic acid, crotonic acid, fumaric acid, maleic acid, itaconic acid or mesaconic acid. The conductive paste according to the above [1] or [2], which is a resin having a structural unit based on a monomer.
[0007]
[4] The latent-COOH group-generating compound (b2) of the resin (B) comprises a monomer of (meth) acrylic acid, crotonic acid, fumaric acid, maleic acid, itaconic acid or mesaconic acid and vinyl (thio) The conductive paste according to any one of the above [1] or [2], which is a resin having a structural unit based on a reaction product with ether.
[5] The conductive material according to any of [1], [2] or [4], wherein the latent-COOH group-generating compound (b2) is a compound having a group represented by the following formula (1). Paste.
[0008]
Embedded image

[0009]
[Wherein R is a hydrogen atom or a methyl group; ¹ , R ² And R ³ Is a hydrogen atom or an organic group having 1 to 18 carbon atoms, ⁴ Is an organic group having 1 to 18 carbon atoms, and R ³ And R ⁴ It may combine with each other to form a heterocyclic ring having Y as a hetero atom, wherein Y is an oxygen atom or a sulfur atom, and n is an integer of 1 to 10. ]
[6] The above-mentioned [1] to [5] further including one or more sulfur compounds (D) having a group selected from the group consisting of a dithiocarbamic acid group, a disulfide group, a mercapto group, and a thiourea group. 4. The conductive paste according to claim 1.
[0010]
[7] A method for manufacturing a printed wiring board, comprising performing the following steps using the conductive paste according to any one of [1] to [6].
Step A: a step of forming a circuit or an electrode by applying a pattern of the conductive paste according to any one of the above [1] to [6] on a printed wiring board or a flexible printed board, and performing a heat treatment to form a circuit or an electrode;
Step B: a step of filling the through-hole of the multilayer substrate with the conductive paste according to any one of the above [1] to [6] and subjecting the paste to heat treatment to obtain electrical continuity between the layers (B).
Step C: After applying the conductive paste according to any one of the above [1] to [6] on the printed circuit board by dispensing, screen printing or stencil printing, a semiconductor element or a chip component is mounted thereon and heated. (C).
[0011]
[8] A printed wiring board obtained by performing the following steps using the conductive paste according to any of the above [1] to [6].
Step A: a step of forming a circuit or an electrode by applying a pattern of the conductive paste according to any one of the above [1] to [6] on a printed wiring board or a flexible printed board, and performing a heat treatment to form a circuit or an electrode;
Step B: a step of filling the through-hole of the multilayer substrate with the conductive paste according to any one of the above [1] to [6] and subjecting the paste to heat treatment to obtain electrical continuity between the layers (B).
Step C: After applying the conductive paste according to any one of the above [1] to [6] on the printed circuit board by dispensing, screen printing or stencil printing, a semiconductor element or a chip component is mounted thereon and heated. (C).
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
The conductive paste of the present invention is a conductive paste containing a metal powder (A), a resin (B), and a curing agent (C) as active ingredients, and the resin (B) has at least one molecule in one molecule. A resin (b1) having one or more -COOH groups or a latent -COOH group-generating compound (b2), wherein the curing agent (C) has at least two or more vinyl (thio) ether bonds in one molecule. Is a compound having
Here, as the metal powder (A) used in the present invention, a metal powder having a high electric conductivity used for a normal conductive paste can be used as a raw material. As the metal element species constituting the metal powder, specifically, for example, Ag (silver), Au (gold), Cu (copper), Al (aluminum), Ni (nickel), Pt (platinum), and Pd (palladium) is preferable, and further preferably, an alloy thereof is preferable. Further, as long as the effects of the present invention are not impaired, a metal element species having lower electric conductivity than the above-mentioned metals and alloys and an alloy thereof may be contained.
As the alloy, specifically, for example, Ag-Pd, Au-Pd, Au-Pt, Pt-Pd, Ag-Ni, Au-Ag, Ag-Cu, Cu-Sn (tin), Cu-Zn (zinc And the like. Metal powder having a surface coated with a different kind of metal, for example, Ag-coated Cu, Sn-coated Cu or the like may be used.
Further, a plurality of metal powders composed of different kinds of metals may be used in combination. In particular, the addition of a small amount of Pd powder or Zn (zinc) powder to Ag powder can be suitably used from the viewpoint of preventing migration and oxidation as required.
As the metal powder (A), metal powders manufactured by various preparation methods such as chemically reduced powder, atomized powder, pulverized powder, and electrolytic powder can be used. Further, as the shape of the metal powder, a metal powder having a shape such as a flaky powder, a granular powder, a spherical powder, a dendritic powder, and a horn-like powder can be used alone or in combination. In order to reduce the electric resistance, it is preferable to use scaly powder or dendritic powder.However, in order to reduce the viscosity of the conductive paste obtained while avoiding an extreme decrease in electric resistance performance, it is necessary to partially mix spherical powder. Is preferred.
The particle size of the metal powder (A) is preferably from 0.2 to 50 μm, more preferably from 0.5 to 20 μm.
[0013]
The resin (B) used in the present invention includes the following (1) a resin (b1) having at least one or more -COOH group in one molecule, or (2) a type of a latent -COOH group generating compound (b2). Resins.
Here, the resin (b1) having at least one or more -COOH group (also referred to as a carboxyl group) in one molecule is not particularly limited as long as it has a carboxyl group. From the viewpoint of availability and the like, a (meth) acrylic resin containing a carboxyl group is preferably used. As the (meth) acrylic resin, an acrylic copolymer obtained by copolymerizing an ethylenically unsaturated carboxylic acid as a functional component with a copolymerizable monomer such as a (meth) acrylic acid ester may be used. Good.
Here, as the ethylenically unsaturated carboxylic acid, for example, monocarboxylic acids such as acrylic acid, methacrylic acid and crotonic acid are suitably used, and further, maleic acid, fumaric acid, dicarboxylic acids such as itaconic acid, or Their anhydrides and half esters can also be used. These monomers can be used alone or in combination of two or more. Among these, acrylic acid and methacrylic acid are preferred from the viewpoint of easy design of the copolymerization reaction.
[0014]
Examples of the (meth) acrylate include linear alkyl (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and hexyl (meth) acrylate; Branched alkyl (meth) acrylates such as ethylhexyl (meth) acrylate; alicyclic (meth) acrylates such as cyclohexyl (meth) acrylate; aromatic group-containing (meth) acrylates such as benzyl (meth) acrylate; hydroxyethyl (meth) Hydroxyl-containing (meth) acrylates such as acrylate and hydroxypropyl (meth) acrylate; nitrogen-containing (meth) acrylates such as dimethylaminoethyl (meth) acrylate; and reactive group-containing (meth) acrylates such as glycidyl (meth) acrylate Rate, and the like. Here, “(meth) acrylate” means acrylate and / or methacrylate.
[0015]
Further, specific examples of the copolymerizable monomer other than the (meth) acrylic acid ester include amide monomers such as (meth) acrylamide and diacetone acrylamide; styrene, α-methylstyrene, and the like. Styrene-based monomers; vinyl esters such as vinyl acetate and alkyl vinyl (thio) ether or ether-based monomers; and monomers such as (meth) acrylonitrile.
These monomers can be used alone or in combination of two or more.
Of these, methyl methacrylate and butyl acrylate are preferred from the viewpoint of the mechanical properties of the copolymer, and hydroxyethyl methacrylate is preferred from the viewpoint of the adhesion of the copolymer to the substrate.
Resin having at least one carboxyl group in one molecule (b1) obtained by copolymerizing an ethylenically unsaturated carboxylic acid and a copolymerizable monomer such as (meth) acrylate ester In order to form a resin copolymer having at least one or more carboxyl groups in one molecule by copolymerization, {average number of carboxyl groups in monomer unit × degree of polymerization of formed resin} is 1 As described above, it may be adjusted in consideration of the ratio of {moles of ethylenically unsaturated carboxylic acid / moles of all monomers} and the molecular weight of the resin copolymer.
The ratio of {the number of moles of ethylenically unsaturated carboxylic acid / the number of moles of all monomers} is not limited to this, but at least 1 in one molecule used in the composition of the conductive paste of the present invention. In consideration of the miscibility with the compound (C) having two or more vinyl (thio) ether groups and the solubility in an organic solvent generally used for a conductive paste, it is preferable that the ratio does not exceed 0.45.
Examples of the resin (b1) having at least one carboxyl group in one molecule include a carboxyl-modified polyester resin, a carboxyl-modified polyamide resin, and a carboxyl-modified polyamide resin in addition to the carboxyl group-containing (meth) acrylic resin. A resin having a carboxyl group such as a modified polyurethane resin and a carboxyl-modified epoxy resin can also be used.
The resin (b1) having at least one carboxyl group in one molecule can be used alone or in combination of two or more.
[0016]
As another latent-COOH group-generating compound (b2) of the resin of the component B, vinyl (thio) is added to the carboxyl group of the resin (b2) having at least one carboxyl group in one molecule. Compounds having a structure to which an ether compound has been added may be mentioned.
The structure of this latent carboxyl group is represented by the following formula (2).
[0017]
Embedded image

[0018]
[R in the formula ¹ , R ² And R ³ Is a hydrogen atom or an organic group having 1 to 18 carbon atoms, ⁴ Is an organic group having 1 to 18 carbon atoms, and R ³ And R ⁴ It may combine with each other to form a heterocyclic ring having Y as a hetero atom, and Y is an oxygen atom or a sulfur atom. ]
[0019]
As the latent-COOH group-generating compound (b2) having the above structure, there are the following two concepts (i) and (ii).
(I) A vinyl (thio) ether compound is added to the resin (b1) having at least one carboxyl group in one molecule to obtain a resin of a latent-COOH group generating compound.
(Ii) A compound having a carboxyl group and a vinyl (thio) ether compound are subjected to an addition reaction to obtain a latent -COOH group, and then the compound is polymerized to produce a latent -COOH group-generating compound. To obtain the resin.
In the above methods (i) and (ii), the addition of vinyl (thio) ether to the carboxyl group of the monomer has a higher reaction rate than the addition of vinyl (thio) ether to the carboxyl group of the resin. The case (ii) obtained by adding a vinyl (thio) ether compound to the monomer compound having a carboxyl group is more preferable from the viewpoint of the reaction time.
The above reaction is represented, for example, by the following formula (3). (Where R ¹ , R ² , R ³ , R ⁴ And Y are the same as described above. )
[0020]
Embedded image

[0021]
Examples of the vinyl (thio) ether compound used to obtain the latent-COOH group-generating compound (b2) include aliphatic vinyl ether compounds, aliphatic vinyl thioether compounds, cyclic vinyl ether compounds, and cyclic vinyl thioether compounds. No.
As the aliphatic vinyl ether compound, specifically, for example, methyl vinyl ether, ethyl vinyl ether, isopropyl vinyl ether, n-propyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexyl vinyl ether, diethylene glycol monovinyl ether, and the like Monovinyl ether compounds; divinyl ethers such as butanediol divinyl ether, cyclohexanediol divinyl ether, cyclohexane dimethanol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, tetraethylene glycol divinyl ether, ethylene glycol divinyl ether, hexanediol divinyl ether, etc. Trivinyl ether compounds such as trimethylolpropane trivinyl ether; tetravinyl ether compounds such as pentaerythritol tetravinyl ether; aliphatic vinyl ether compounds such as hydroxyethyl vinyl ether and hydroxyalkyl vinyl ether compounds such as hydroxyalkyl vinyl ether compounds; An aliphatic vinyl thioether compound corresponding to the vinyl ether compound is exemplified.
Further, as the cyclic vinyl ether compound, for example, 2,3-dihydrofuran, 3,4-dihydrofuran, 2,3-dihydro-2H-pyran, 3,4-dihydro-2H-pyran, 3,4-dihydro- 2-methoxy-2H-pyran, 3,4-dihydro-4,4-dimethyl-2H-pyran-2-one, 3,4-dihydro-2-ethoxy-2H-pyran, 3,4-dihydro-2H- Examples thereof include cyclic vinyl ether compounds such as sodium pyran-2-carboxylate, and cyclic vinyl thioether compounds corresponding to the above-mentioned cyclic vinyl ether compounds.
Among these, isopropyl vinyl ether, n-propyl vinyl ether, and n-butyl vinyl ether are preferably used in order to shift the equilibrium of the hemiacetal transesterification reaction with the curing agent (C) to obtain a good cured product.
In the methods (i) and (ii), the polyfunctional vinyl ether is used in a large amount.
When used, it is usually crosslinked and gelled, so it is desirable to use a small amount that does not cause gelation.
[0022]
The acid value of the resin (b1) having at least one carboxyl group in one molecule is preferably 10 mgKOH / g or more, more preferably 10 mgKOH / g, from the viewpoint of the physical properties and conductivity of the cured product of the conductive paste. Is 25 mgKOH / g or more.
Similarly, the latent carboxyl group of the latent-COOH group-generating compound (B2) having the above-mentioned structure is expressed as an acid equivalent for quantifying a carboxyl group forming a hemiacetal bond with a vinyl (thio) ether compound. It is preferably 10 mgKOH / g or more, more preferably 25 mgKOH / g or more, from the viewpoint of the physical properties and conductivity of the cured product of the conductive paste.
[0023]
As the resin of the component B used in the present invention, the resin (B1) having at least one or more —COOH group in one molecule or the resin that is a latent —COOH group generating compound (B2) ( The molecular weight of B) is preferably from 300 to 100,000 in terms of weight average molecular weight from the viewpoint of the electrical conductivity and physical properties of the cured product of the conductive paste of the present invention. Further, in consideration of coatability of the conductive paste such as non-spinning property, the weight average molecular weight is preferably 8,000 to 40,000.
[0024]
The curing agent of the component C used in the present invention is a compound having at least two vinyl (thio) ether bonds in one molecule, and the curing agent (C) is, for example, a compound of the aforementioned b2 component. The aliphatic vinyl ether compound, the aliphatic vinyl thioether compound, the cyclic vinyl ether compound, or the cyclic vinyl thioether compound aliphatic shown by way of example is also mentioned.
[0025]
Among these, in order to shift the equilibrium between the resin (B) and the hemiacetal esterification reaction or the hemiacetal transesterification reaction to obtain a good cured product, butanediol divinyl ether, cyclohexane dimethanol divinyl ether, Preference is given to ethylene glycol divinyl ether.
[0026]
In the conductive paste of the present invention, the amount of the metal (A) is preferably 77 to 97 parts by weight, and more preferably 82 to 97 parts by weight, based on 100 parts by weight of the entire conductive paste minus the solvent alone. 92 parts by weight. Since the resistance value of the conductive paste of the present invention increases as it goes away from the minimum value, it is not practically preferable to mix the metal (A) outside the above range.
The compounding ratio of the resin (B) and the curing agent (C) in the conductive paste was 0.1 ratio in the ratio of {molar equivalent of vinyl group of curing agent (C) / acid molar equivalent of resin (B)}. A ratio of 10 to 10 is preferred. If this ratio is less than 0.1, the absolute number of working molecules of the resin (B) and the curing agent (C) is small, and sufficient cured physical properties cannot be obtained when the conductive paste is cured. In addition, the curing agent (C), which has an excessive molar ratio in its operation, functions as a solvent and most of it is volatilized. If this ratio exceeds 10, the plasticizing action of the curing agent (C) and the curing agent (C) The polymerization reaction of itself may adversely affect the physical properties and conductive properties of the cured product, which is not preferable.
[0027]
The solvent used for the conductive paste of the present invention is not particularly limited. It can be appropriately selected and used from ordinary general-purpose solvents. Specific examples of the solvent include aliphatic hydrocarbons such as dodecane, tetradecene and dodecylbenzene; aromatic hydrocarbons such as toluene and xylene; methanol, ethanol, 2-propanol (isopropanol), α-terpineol, benzyl alcohol Alcohols such as ethyl acetate, 2-hexyldecanol; esters such as ethyl acetate, ethyl lactate, butyl acetate, butyl benzoate, diethyl adipate and diethyl phthalate; ethers such as 1,4-dioxane and tetrahydrofuran; methyl ethyl ketone, methyl isobutyl ketone Ketones such as triethylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, propylene glycol Glycol derivatives such as monoethyl ether acetate, ethylene glycol monophenyl ether, diethylene glycol monophenyl ether, dipropylene glycol, diethylene glycol-2-ethylhexyl ether, and tetraethylene glycol dimethyl ether; alicyclic hydrocarbons such as cyclohexanone and cyclohexanol; petroleum Petroleum-based solvents such as ether and naphtha.
Preferably, propylene glycol monoethyl ether acetate, tetraethylene glycol dimethyl ether and the like are mentioned.
The amount of the solvent used is not particularly limited, but from the viewpoint of applicability affecting electric conductivity, the conductive paste containing the metal powder (A), the resin (B), and the curing agent (C) is used. It is preferable to add 50 to 300 parts by weight of the solvent with respect to 100 parts by weight in total other than the solvent.
When the vinyl ether compound is excessively mixed as described above, the vinyl ether compound also functions as a solvent.
[0028]
The conductive paste of the present invention further contains a sulfur compound (D) having a group selected from the group consisting of a dithiocarbamic acid group, a disulfide group, a mercapto group, and a thiourea group in order to further improve the conductivity. It is desirable.
Examples of the sulfur compound (D) include the following sulfur compounds (D) (D) to (IV).
(I) Examples of the sulfur compound having a dithiocarbamate group (D) include zinc dibenzyldithiocarbamate, pentamethylenedithiocarbamate piperidine salt, zinc dibutyldithiocarbamate, zinc N-ethyl-N-phenyldithiocarbamate, and N-pentamethylenedithiocarbamine. Compounds having a dithiocarbamic acid group such as zinc acid,
(Ii) Examples of the sulfur compound having a disulfide group (D) include, as the sulfur compound having a disulfide group (D), tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetrakis (2-ethylhexyl) thiuram disulfide, and the like. A compound having a disulfide group of
(Iii) Examples of the sulfur compound (D) having a mercapto group include di-2-benzothiazolyl disulfide, 2-mercaptoimidazoline, mercaptobenzothiazole, zinc salt of 2-mercaptobenzothiazole, and cyclohexyl of 2-mercaptobenzothiazole. A compound having a mercapto group such as an amine salt,
(Iv) Examples of the sulfur compound having a thiourea group (D) include N, N'-diphenylthiourea, N, N'-diethylthiourea, trimethylthiourea, N, N'-dibutylthiourea, and N, N'-dilaurylthio. Compounds having thiourea such as urea,
The sulfur compounds (D) can be used alone or in combination of two or more.
The sulfur compound (D) is used in an amount of preferably 0.1 to 5.0 parts by weight, more preferably 0 to 100 parts by weight based on the binder weight / the total weight of the conductive paste components other than the metal powder. 0.5 to 0.25 parts by weight can be used. When the amount of the sulfur compound (D) is less than 0.1 part by weight, the favorable effect on the conductive performance of the cured conductive paste is too small. It is not preferable because it adversely affects physical properties.
[0029]
In the conductive paste of the present invention, a thixotropy-imparting agent, a chelating agent, a coupling agent, a dispersion stabilizer, a leveling agent, and a tackifier are further added as necessary as long as the effects of the present invention are not impaired. And various additives such as pigments, defoamers, corrosion inhibitors, and flame retardants.
[0030]
In the production of the present conductive paste, the above-mentioned components are charged at once or sequentially, and mixed by a usual method using a blade-type stirrer, a desolver, a kneader, a raker, a ball mill mixer, a roll disperser, or the like. Should be performed. The mixing temperature is preferably from 10 to 30 ° C. in order to avoid dew condensation and evaporation of the solvent, although it depends on the ingredients.
[0031]
In the conductive paste of the present invention, the resin (B) having at least one carboxyl group in one molecule and the compound (C) having at least one vinyl ether group in one molecule are heat-treated. To form a cured paste. In that case, a catalyst may be used to further increase the reaction rate under heat treatment conditions. Specific examples of the catalyst include nitrogen-containing compounds such as N, N-dimethylformamide, N, N-dimethylacetamide, and N-methylpyrrolidone; hexamethylphosphoric triamide, and trimethyl phosphate and triethyl phosphate. For example, a compound such as trialkyl phosphate or dimethyl sulfoxide can be used. The addition amount of these catalysts is preferably 0 to 3 parts by weight based on 100 parts by weight of the total of the resin (B) and the curing agent (C).
When a sufficient heat treatment time is allowed and it is not necessary to increase the action speed, the compounding amount of the above-described catalyst may be adjusted to further improve the reliability of the cured conductive paste as necessary. ) And the curing agent (C) are preferably 0.2 parts by weight or less based on 100 parts by weight in total.
[0032]
As a method of using the conductive paste of the present invention, a conductive portion can be formed on a printed wiring board using the conductive paste. The wiring board of the present invention is obtained by performing at least one of the following steps.
A step: a step of applying a pattern on a printed wiring board or a flexible printed board and performing a heat treatment to form a circuit or an electrode (A);
Step B: a step of filling the through-holes of the multilayer substrate and performing a heat treatment to obtain electrical continuity between the layers (B);
Step C: Step of applying by dispensing, screen printing or stencil printing on a printed circuit board, or mounting and mounting a semiconductor element or chip component and heating and bonding (C)
As for the method of using the conductive paste of the present invention, each step can be performed by known methods and conditions except that the conductive paste of the present invention is used as the conductive paste.
[0033]
The printed wiring board of the present invention is a printed wiring board obtained by performing the following steps using the conductive paste.
Step A: a step of forming a circuit or an electrode by applying a pattern of the conductive paste according to any one of the above [1] to [6] on a printed wiring board or a flexible printed board, and performing a heat treatment to form a circuit or an electrode;
Step B: a step of filling the through-hole of the multilayer substrate with the conductive paste according to any one of the above [1] to [6] and subjecting the paste to heat treatment to obtain electrical continuity between the layers (B).
Step C: After applying the conductive paste according to any one of the above [1] to [6] on the printed circuit board by dispensing, screen printing or stencil printing, a semiconductor element or a chip component is mounted thereon and heated. (C).
In this way, the conductive paste of the present invention can be applied in a general manner, for example, by applying a pattern on a wiring board and subjecting it to heat treatment, filling a through-hole in a multilayer board, or dispensing and printing on a printed board. By conducting printing or stencil printing and performing a heat treatment, a conductive portion can be formed at a place where conductivity is required on the wiring board, which is industrially useful. In particular, since it is excellent in its conductive properties and can be treated by an easy method such as removal and curing of a solvent after coating, it can be used for general purposes.
[0034]
【Example】
Next, the present invention will be described in more detail based on examples. Next, the measuring method used in the present invention will be described.
[Measuring method]
1. <Viscosity> The paste viscosity before curing was measured at a temperature of 25 ° C. using an E-type viscometer Visconic EHD manufactured by Tokimec Co., Ltd. equipped with a circulating thermostatic water bath.
[0035]
2. <Volume Resistivity> The volume resistivity of the paste is measured by a four-terminal four-probe method according to JIS K7194 “Low-resistance test method for conductive plastic by a four-probe method”. The sample was formed by applying a paste line of 1 × 5 cm on a glass plate using a guideline of cellophane tape, heat-treating at 150 ° C. for 30 minutes, and then applying ASP to Loresta GP MCP-T600 type manufactured by Mitsubishi Chemical Corporation. A probe was connected, and the obtained bulk resistance value was divided by the sample thickness measured by a micrometer to obtain a volume resistivity.
The high-temperature resistance and the high-temperature high-humidity resistance of the volume resistivity were determined by increasing the resistivity with respect to the initial performance.
…: Excellent resistance (resistivity increase of less than 10% with respect to initial performance)
○: Sufficient resistance (10% or more, less than 15%)
△: Practically somewhat problematic (15% or more, less than 20%)
×: There is a problem in practical use (20% or more)
[0036]
3. <Cleaning test>
Adhesion to the glass substrate was measured by JIS K 5600-5-6: 1999 "Coating general test method-Part 5: Mechanical properties of coating film-Section 6: Adhesion (cross-cut method)" Investigated by testing. The clearance between the cutter guides was 2 mm. The determination method was as follows.
…: Excellent adhesion (number of grids that cannot be peeled / number of grids (100) = 100/100)
…: Sufficient adhesion (90 to 99/100)
Δ: There is some problem in practical use (80 to 89/100)
X: Practical problem (79 or less / 100)
[0037]
4. <Adhesion strength test> The adhesion strength was measured on a copper foil land pattern on a glass epoxy substrate from which a resist of 0.8 mm in length x 0.8 mm in width and a land interval of 0.4 mm was simulated by mounting a 1608 chip component. A conductive paste was stencil-printed using a 50 μm-thick metal mask on which a land pattern of 0.8 mm length × 0.4 mm width and land spacing of 0.4 mm was formed, and a 1608 dummy chip component was mounted thereon. Thereafter, a heat treatment was performed under the above conditions. Using a universal bond tester 4000 manufactured by DAGE, a dummy component bonded to the substrate with a conductive paste is used to test the mechanical strength of a surface mount component using the provisional standard RCX-0414 / 102 of the Japan Electronics and Machinery Industries Association. According to "", a lateral push test of the part was performed and measured. However, instead of the creep mode, the fracture mode was adopted, and the yield point was used as the bonding strength. The determination method was as follows.
◎… Excellent adhesion (adhesion strength = 10N or more)
…: Sufficient adhesion (more than 9N and less than 10N)
△: Some problem in practical use (8N or more to less than 9N)
×: There is a problem in practical use (up to 8 N)
[0038]
5. <High Temperature Resistance> The above-mentioned adhesion strength test sample and volume resistivity test sample were placed in a 125 ° C. constant temperature bath, and changes in adhesion strength and volume resistivity after 500 hours were measured.
6. <High-temperature and high-humidity resistance> The aforementioned bond strength test sample and volume resistivity test sample were placed in a PCT test apparatus kept at 121 ° C / 97% RH / 2.3 atm, and the bond strength and volume after 24 hours. The change in resistivity was measured.
[0039]
[Synthesis Example 1] Polymerization of acrylic resin
After replacing the inside of a 500 mL four-necked flask equipped with a dropping funnel, a stirrer, a nitrogen gas inlet tube, and a reflux condenser with nitrogen gas, 50 g of xylene and 100 g of propylene glycol monomethyl ether acetate (PMA) were put thereinto, 7 g of methacrylic acid (MAA), 35 g of methyl methacrylate (MMA), 55 g of butyl acrylate (BA), 3 g of 2-hydroxyethyl methacrylate (HEMA), and t-butyl peroxyisopropyl carbonate (trade name: Perbutyl I, Nippon Oil & Fats) 101 g of a mixture (1 g, manufactured by Co., Ltd.) was added dropwise at 130 ° C. over 5 hours at a uniform rate. Thereafter, 1 g of t-butyl peroxyisopropyl carbonate was added, and the unreacted monomer was converted at 130 ° C. for 2 hours to obtain 250 g of a viscous solution. The obtained resin (B-1) had a solid content of 39%, an acid value in terms of solid content of 42 mgKOH / g, and a weight average molecular weight of 42,100. When these values are converted, 32 carboxyl groups are present on average in one molecule of the resin resin.
[0040]
[Comparative Synthesis Example 2] Polymerization of acrylic resin
After replacing the inside of the flask with nitrogen gas using the same reaction apparatus as in Synthesis Example 1, 150 g of xylene was charged, and 0.7 g of MAA, 41.3 g of MMA, 55 g of BA, 3 g of HEMA, and 3 g of t-butylperoxy 2-ethylhexa were added through a dropping funnel. 114 g of a mixture of 14 g of noate (trade name: Perbutyl O, manufactured by NOF Corporation, purity: 95%) was dropped at 130 ° C. over 5 hours at a uniform rate. Thereafter, 1 g of t-butyl peroxyisopropyl carbonate was added, and the unreacted monomer was converted at 130 ° C. for 2 hours to obtain 265 g of a viscous solution. The obtained resin (B'-1) had a solid content of 40%, an acid value in terms of solid content of 4.1 mgKOH / g, and a weight average molecular weight of 9,400. When these values are converted, one carboxyl group is present on average in one molecule of the resin resin.
[0041]
[Synthesis Example 3] Synthesis of monomer having latent carboxyl group
172.2 g of methacrylic acid (MAA), 223.9 g of n-propylvinyl ether (nPVE), and a catalyst of acidic phosphate ester (mono) were placed in a 500 mL four-necked flask equipped with a thermometer, a reflux condenser, a capillary inlet tube, and a stirrer. A mixture of -2-ethylhexyl phosphate, di-2-ethylhexyl phosphate and tris-2-ethylhexyl phosphate, trade name: AP-8, 2.0 g, manufactured by Daihachi Chemical Industry Co., Ltd., 2.0 g, hydroquinone monomethyl ether (Wako Pure Chemical Industries, Ltd.) 0.5 g was charged, and the temperature was raised from room temperature to 60 ° C. while introducing air at a rate of 20 mL / min from the capillary inlet tube, followed by a reaction at 60 ° C. for 6 hours. After confirming that the acid value of the mixed solution was 5 or less, the reaction was stopped. The mixed solution was washed with 399.6 g of the mixed solution in a funnel using 50 mL of a 10% aqueous sodium carbonate solution, and the organic layer was formed of synthetic magnesium silicate (trade name: Kyoward 600, manufactured by Kyowa Chemical Industry Co., Ltd.). After adding 0 g and stirring, the mixture was filtered and unreacted substances were distilled off from the filtrate using a rotary evaporator to obtain 340.2 g of a latent carboxyl group-containing monomer (M-1). GC analysis revealed that the purity of the nPVE hemiacetal ester of MAA was 98.7%.
[0042]
[Synthesis Example 4] Polymerization of acrylic resin
Using the same reaction apparatus as in Synthesis Example 1, except that 14 g of the latent carboxyl group-containing monomer (M-1) synthesized in Synthesis Example 3 and 41 g of BA were used instead of 7 g of MAA and 55 g of BA used in Synthesis Example 1. The synthesis operation was performed under exactly the same conditions as in Synthesis Example 1. 250 g of a viscous solution were obtained. The obtained resin (B-2) had a solid content of 39%, a hydrolyzed acid value in terms of solid content of 40 mgKOH / g, and a weight average molecular weight of 43,500. When these values are converted, one resin molecule has 31 carboxyl groups on average.
[0043]
Example 1
Flaky silver powder (trade name: Silvest TCG-1, manufactured by Tokurika Kaken Co., Ltd., average particle size 1.9 μm, tap density 3.1 g / cm) ³ ) (A-1) 3.84 g, the carboxyl group-containing resin solution (B-1) 1.13 g obtained in Synthesis Example 1, and triethylene glycol divinyl ether (TEGDVE, manufactured by Nippon Carbide Industry Co., Ltd.) 0.23 g, propylene glycol monomethyl ether acetate (PMA, manufactured by Kuraray Co., Ltd.) 0.45 g, and caster wax 0.03 g (dissolved in a B-1 solution in advance at 80 ° C. while heating) Combine 0.02 g of zinc acetylacetonate monohydrate (manufactured by Dojindo Laboratories) as a chelating agent, and use a paste kneader ARV-200 manufactured by Shinky Co., Ltd. for 2 cycles of rotation for 17 seconds. After mixing, a conductive paste having a viscosity of 380 dPa · sec was obtained. The composition is shown in Table 1. In addition, the above compositions were evaluated by the test methods and evaluation methods described above. The applied or printed paste was pre-dried at 70 ° C. for 10 minutes, and then heat-treated at 150 ° C. for 30 minutes. The results are shown in Table 1.
[0044]
Example 2
Instead of the silver powder used in Example 1, flake silver powder (trade name: Silcoat AgCA, manufactured by Fukuda Metal Foil Mining Co., Ltd., average particle size 3.5 μm, tap density 3.3 g / cm) ³ Except that the same amount of (A-2) was used, the same operation as in Example 1 was performed. By the above operation, a conductive paste having a viscosity of 230 dPa · sec was obtained. In addition, the above compositions were evaluated by the above-described test methods and evaluation methods. The conditions for the heat treatment were exactly the same as in Example 1. Table 1 shows the composition and the results.
[0045]
Example 3
In place of the resin solution (B-1) used in Example 1, a commercially available polyester-based carboxyl group-containing resin (trade name: Finedick M8962, manufactured by Dainippon Ink and Chemicals, Inc., acid value 35 mg KOH / g) was used. The same operations and evaluations as in Example 1 were carried out except that the same amount as that of (B-1) in Example 1 was used (B′-2) dissolved in PMA and adjusted to a concentration of 39%. On average, six carboxyl groups exist in one molecule of this resin. Table 1 shows the composition and the results. The viscosity of the conductive paste was 340 dPa · sec.
[0046]
Comparative Example 1
The same operation as in Example 1 was performed except that the same amount of the resin solution (B′-1) obtained in Synthesis Example 2 was used instead of the resin solution (B-1) used in Example 1. . By the above operation, a conductive paste having a viscosity of 350 dPa · sec was obtained. In addition, the above compositions were evaluated by the above-described test methods and evaluation methods. The conditions for the heat treatment were exactly the same as in Example 1. Table 1 shows the composition and the results.
[0047]
Comparative Example 2
Except that the same amount of the resin solution (B′-2) obtained in Synthesis Example 2 was used instead of the resin solution (B-1) used in Example 2, the same operation as in Example 2 was performed. . Through the above operation, a conductive paste having a viscosity of 180 dPa · sec was obtained. In addition, the above compositions were evaluated by the above-described test methods and evaluation methods. The conditions for the heat treatment were exactly the same as in Example 1. Table 1 shows the composition and the results.
[0048]
Comparative Example 3
Instead of the resin solution (B-2) used in Example 3, a commercially available polyester-based carboxyl group-containing resin (trade name: GK780, manufactured by Toyobo Co., Ltd., acid value: 5 mgKOH / g) was dissolved in PMA, and 39 The same operation as in Example 3 was carried out except that the same amount (B'-2) as that in Example 1 was used in the same amount as (B-1) in Example 1. One resin molecule has 0.5 carboxyl groups on average. By the above operation, a conductive paste having a viscosity of 380 dPa · sec was obtained. In addition, the above compositions were evaluated by the above-described test methods and evaluation methods. The conditions for the heat treatment were exactly the same as in Example 1. Table 1 shows the composition and the results.
[0049]
[Table 1]

[0050]
Example 4
Flaky copper powder (trade name: 1300YP, manufactured by Mitsui Kinzoku Mining Co., Ltd., average particle size: 5.7 μm, tap density: 3.9 g / cm) ³ 8.51 g of (A-3), 1.58 g of the resin solution (B-2) obtained in Synthesis Example 4, and 0.33 g of cyclohexanemethanol divinyl ether (CHDVE, manufactured by Nippon Carbide Industry Co., Ltd.). A mixture of 0.47 g of propylene glycol monomethyl ether acetate (PMA, manufactured by Kuraray Co., Ltd.) and an acidic phosphate ester catalyst (mono-2-ethylhexyl phosphate, di-2-ethylhexyl phosphate, tris-2-ethylhexyl phosphate, trade name) : AP-8, manufactured by Daihachi Chemical Industry Co., Ltd.), and the mixture was spin-revolved and mixed for 17 seconds for 2 cycles using a paste kneader ARV-200 manufactured by Shinky Co., Ltd. to obtain a viscosity of 220 dPa · sec. A conductive paste was obtained. The composition is shown in Table-2. In addition, the above compositions were evaluated by the test methods and evaluation methods described above. However, the applied or printed paste was pre-dried at 70 ° C. for 10 minutes, and then heat-treated at 150 ° C. for 30 minutes. The results are shown in Table-2.
[0051]
Comparative Example 4
The same operation as in Example 3 was performed, except that the same amount of the resin solution (B′-1) obtained in Synthesis Example 2 was used instead of the resin solution (B-1) used in Example 4. . By the above operation, a conductive paste having a viscosity of 240 dPa · sec was obtained. The composition is shown in Table-2. In addition, the above compositions were evaluated by the test methods and evaluation methods described above. The conditions for the heat treatment were exactly the same as in Example 1. The results are shown in Table-2.
[0052]
Comparative Example 5
In Example 4, the same operation as in Example 4 was performed except that 0.33 g of TEGDVE and 0.47 g of PMA were used, but 0.80 g of PMA was used without using any TEGDVE. By the above operation, a conductive paste having a viscosity of 200 dPa · sec was obtained. The composition is shown in Table-2. In addition, the above compositions were evaluated by the test methods and evaluation methods described above. The heat treatment was performed under the same conditions as in Example 3. Table 2 shows the composition and the results.
[0053]
[Table 2]

[0054]
From the above results, it can be seen that in Examples 1 to 4 of the present invention, excellent volume resistivity and excellent adhesiveness are maintained and maintained under high temperature conditions and high temperature and high humidity conditions. Further, as is apparent from Comparative Examples 1 to 4 using the resin (B ′) outside the scope of the present invention and Comparative Example 5 using the curing agent (C) outside the scope of the present invention, the requirements of the present invention were satisfied. It can be seen that this excellent performance cannot be obtained with a conductive paste compounding system that does not satisfy the above.
[0055]
【The invention's effect】
The conductive paste of the present invention is either a metal powder (A), a resin (b1) having at least one or more -COOH group in one molecule, or a latent -COOH group generating compound (b2). Since it contains the resin (B) and the curing agent (C), which is a compound having at least two or more vinyl (thio) ether bonds in one molecule, excellent conductive performance and adhesive (adhesion) strength properties and Two types of sustainability can be compatible. Therefore, a printed wiring board using the conductive paste exhibits excellent adhesiveness, and has excellent reliability and is industrially useful.

Claims (8)

A conductive paste containing metal powder (A), resin (B) and curing agent (C) as active ingredients, wherein said resin (B) has at least one or more -COOH groups in one molecule. Resin (b1) or a latent-COOH group-generating compound (b2), wherein the curing agent (C) is a compound having at least two or more vinyl (thio) ether bonds in one molecule. Conductive paste. The metal powder (A) is selected from a metal element group consisting of Ag (silver), Au (gold), Cu (copper), Al (aluminum), Ni (nickel), Pt (platinum), and Pd (palladium). The conductive paste according to claim 1, wherein the conductive paste is a kind of metal powder or a metal powder of an alloy of two or more kinds of the metal elements. The resin (b1) having at least one or more -COOH groups in one molecule of the resin (B) is a structural unit based on (meth) acrylic acid, crotonic acid, fumaric acid, maleic acid, itaconic acid, or mesaconic acid The conductive paste according to claim 1, which is a resin having: The latent-COOH group-generating compound (b2) of the resin (B) is obtained by reacting (meth) acrylic acid, crotonic acid, fumaric acid, maleic acid, itaconic acid or mesaconic acid with vinyl (thio) ether. The conductive paste according to claim 1, wherein the resin is a resin having a structural unit based on a block acid-type monomer whose group is blocked with vinyl ether. 5. The conductive paste according to claim 1, wherein the latent-COOH group-generating compound (b2) is a compound having a structural unit represented by the following formula (1).

Wherein R is a hydrogen atom or a methyl group, R ¹ , R ² and R ³ are each a hydrogen atom or an organic group having 1 to 18 carbon atoms, and R ⁴ is an organic group having 1 to 18 carbon atoms; ³ and R ⁴ may combine with each other to form a heterocyclic ring having Y as a hetero atom, wherein Y is an oxygen atom or a sulfur atom, and n is an integer of 1 to 10. ] 6. The composition according to claim 1, further comprising one or more sulfur compounds (D) having a group selected from the group consisting of a dithiocarbamic acid group, a disulfide group, a mercapto group, and a thiourea group. 7. Conductive paste. A method for manufacturing a printed wiring board, comprising performing the following steps using the conductive paste according to claim 1.
A step: a step of forming a circuit or an electrode by applying a pattern of the conductive paste according to any one of claims 1 to 6 on a printed wiring board or a flexible printed board and performing a heat treatment on the printed circuit board or the flexible printed board;
Step B: a step of filling the through-hole of the multilayer substrate with the conductive paste according to any one of claims 1 to 6, and performing heat treatment to obtain electrical continuity between the layers (B);
C: applying the conductive paste according to any one of claims 1 to 6 on a printed circuit board by dispensing, screen printing, or stencil printing, mounting a semiconductor element or a chip component, and performing heat treatment and joining. (C). A printed wiring board obtained by performing the following steps using the conductive paste according to claim 1.
A step: a step of forming a circuit or an electrode by applying a pattern of the conductive paste according to any one of claims 1 to 6 on a printed wiring board or a flexible printed board and performing a heat treatment on the printed circuit board or the flexible printed board;
Step B: a step of filling the through-hole of the multilayer substrate with the conductive paste according to any one of claims 1 to 6, and performing heat treatment to obtain electrical continuity between the layers (B);
C: applying the conductive paste according to any one of claims 1 to 6 on a printed circuit board by dispensing, screen printing, or stencil printing, mounting a semiconductor element or a chip component, and performing heat treatment and joining. (C).