JP4018933B2

JP4018933B2 - Ceramic substrate and manufacturing method thereof

Info

Publication number: JP4018933B2
Application number: JP2002149244A
Authority: JP
Inventors: 徹郎中元
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2002-05-23
Filing date: 2002-05-23
Publication date: 2007-12-05
Anticipated expiration: 2022-05-23
Also published as: JP2003347684A

Description

【０００１】
【発明の属する技術分野】
本発明は、貫通孔に導体形成したのち貫通孔間で分割する電子部品用セラミックス基板に関するものである。
【０００２】
【従来の技術】
図８（ａ）は複数の分割溝１３が貫通孔１２と重なるように形成された一般的な電子部品用セラミックス基板１１の平面図である。本形状のセラミックス基板１１の貫通孔１２の主な用途は端面電極であって、シート状のセラミックス基板１１の貫通孔１２にセラミックス基板１１の表裏の導通をとるための導体を形成後、分割溝１３，１４を分割することにより、図８（ｂ）の斜視図に示すような複数の半円状凹部１５を有するセラミックス基板１１ａが得られる。
【０００３】
上記の半円状凹部１５にはセラミックス基板１１ａの表裏を電気的に接続するための端面電極１６が形成されていて、図示省略するが回路基板上に上記セラミックス基板１１ａを搭載し、セラミックス基板１１ａの表面に搭載された電子部品回路チップやまたは抵抗体膜と回路基板ランド間を上記端面電極１６により電気的に接続するためのものである。
【０００４】
これらの導体形成を目的とした貫通孔１２は、導体となるペーストの吸引がスムーズになされるように、図８（ｃ）に示すセラミックス基板１１の断面図のように貫通孔１２の表面側にＣ面部１７を形成することがよく行われている。
【０００５】
この分割溝１３がＣ面部１７を有する貫通孔１２と重なる形状のセラミックス基板１１を金型で製造する方法として、図９（ａ）の断面図に示すように、Ｃ面部１８ｂを有するポンチ１８とその左右に分割溝形成用の刃１９を各々金型に装着し、セラミックスグリーンシートに押し当てることにより、図９（ｂ）のセラミックス基板１１の平面図に示すような貫通孔１２と分割溝１３が形成され、所定の温度で焼成することによりセラミックス基板１１が得られる。
【０００６】
しかしながら、上記の分割溝１３と貫通孔１２は、図９（ｃ）に示すセラミックス基板１１の断面図で解るように分割溝１３は貫通孔１２の近傍で途切れる形状となり、その結果、分割溝１３を分割する際に分割バリが発生するという問題があった。
【０００７】
特開平４−２０６８０２号公報によると、図１０（ａ）のセラミックス基板１１１の平面図に示す貫通孔１１２と分割溝１１３は、この分割バリの問題を解決するとともに貫通孔１１２へのペースト吸引時に分割溝１１３への流れ込みを防止する目的で、図１０（ｂ）の断面図に示すように、セラミックス基板１１１の表面側に径の大きな孔１１２ａと裏面側に径の小さな孔１１２ｂを設け、上記貫通孔１１２と重なる分割溝１１３は、前述した径の大きな孔１１２ａ側に形成するとともに、径の大きな孔１１２ａより浅く形成すると記載されている。
【０００８】
その製造方法については、図１０（ｃ）に示すように、刃（成形刃）１１９で分割溝１１３を、ポンチ（スルーホール打ち抜きピン）１１８で貫通孔１１２を、同時にセラミックスグリーンシートに押し当てて成型し、次の工程で上記分割溝１１３に直交する分割溝と外辺切断を行うと記載されているが、径の大きな孔１１２ａの成型は図示では刃１１９と一体である突出部１１９ａで行うとなっているがその詳細な構造は記載されていない。
【０００９】
【発明が解決しようとする課題】
前述した図９（ａ）に示すＣ面部１８ｂを有するポンチ１８と刃１９で、分割溝１３と重なる貫通孔１２を形成すると、図９（ｃ）に示すように、貫通孔１２のＣ面部１７で分割溝１３が途切れ、上記分割溝１３を分割すると分割バリが発生するということと、端面電極導体にも分割時に大きな応力がかかり、破断面が突出或いは凹み状になったり、極端な場合には部分的に導体剥離が発生するという課題があった。
【００１０】
また、前述した特開平４−２０６８０２号公報によると、図１０（ｂ）に示す貫通孔１１２の径の大きな孔１１２ａの深さに対し、分割溝１１３の深さを浅くするようになっているが、セラミックスグリーンシートに押し当てて矩形状凹部を形成するとセラミックス基板表面に応力の逃げによる盛り上がりが発生し、これは後で形成する回路印刷に悪影響を及ぼすという問題があった。また、この孔周辺の盛り上がりを抑えるために、径の大きな孔１１２ａの深さを浅く設定すると、分割溝１１３の深さが更に浅くなり、ペーストの分割溝流れ込みの問題は解決されても、本来の分割溝としての目的を達せず分割不良が発生し、この場合も前述と同様に、破断面が突出或いは凹み状になったり、極端な場合には部分的に導体剥離が発生するという課題があった。
【００１１】
さらに、貫通孔１１２の断面は径の大きな孔１１２ａが矩形状を呈しているために導体形成した場合、貫通孔１１２，１１２ａのエッジ部にかかる導体膜厚みが極端に薄い場所が発生し導体切れ等の信頼性の課題もあった。
【００１２】
【課題を解決するための手段】
そこで、本発明のセラミックス基板は上記課題に鑑み、表面に複数の分割溝と該分割溝に重なるように端面電極用導体が形成される複数の貫通孔が形成されたセラミックス基板において、上記貫通孔は平面形状が円形状で表面側開孔部にＣ面部を有し、上記分割溝が上記貫通孔のＣ面部まで連続して形成され、かつ上記分割溝の深さが上記貫通孔のＣ面部の深さと同一、もしくはこれよりも深いことを特徴とする。
また、本発明の電子部品用セラミックス基板は、表面に複数の分割溝と該分割溝に重なるように端面電極用導体が形成された複数の貫通孔が形成された電子部品用セラミックス基板において、上記貫通孔は平面形状が円形状で表面側開孔部にＣ面部を有し、上記分割溝が上記貫通孔のＣ面部まで連続して形成され、かつ上記分割溝のＣ面部の深さと同一、もしくはこれよりも深いことを特徴とする。
【００１３】
また、表面に複数の分割溝と該分割溝に重なるように複数のＣ面部を有する貫通孔が形成されたセラミックス基板の製造方法は、上記貫通孔の穿孔用のポンチは、先端のストレート部とその途中より該ストレート部径より大きな径のＣ面部を有し、該Ｃ面部若しくは上記ストレート部に左右一対の刃を備えてなり、複数本の上記ポンチの刃と刃の間に上記ポンチの刃と同等の深さとなるように分割溝形成用の刃を装着して金型を構成し、該金型でセラミックスグリーンシートを打ち抜く工程と、打ち抜かれたセラミックスグリーンシートを所定の温度で焼成する工程とからなることを特徴とする。
【００１４】
【発明の実施の形態】
以下、本発明の実施形態について説明する。
【００１５】
図１（ａ）は本発明のセラミックス基板の一例を示す平面図である。
【００１６】
上記セラミックス基板１は、表面に複数の分割溝３，４と該分割溝３と重なるように端面電極用導体が形成される複数の貫通孔２を有する。上記貫通孔２は平面形状が円形状で表面側開孔部にＣ面部２ａを有し、上記分割溝２を分割した断面図を図１（ｂ）に示すように、上記分割溝３が上記貫通孔２のＣ面部２ａまで連続して形成され、かつ上記分割溝３の深さＤ１が上記貫通孔２のＣ面部２ａの深さＤ２と同一、もしくはこれよりも深く形成していることを特徴とする。
【００１７】
次に、本発明のセラミックス基板１の製造方法を説明する。
【００１８】
図２（ａ）に、本発明の一例である貫通孔２の穿孔用のポンチ５の斜視図を示し、上記穿孔用のポンチ５は、先端のストレート部５ａとその途中よりストレート部５ａ径より大きな径のＣ面部５ｂとを有し、該Ｃ面部５ｂ若しくは上記ストレート部５ａに左右一対の刃５ｃを備えている。
【００１９】
次に図２（ｂ）の断面図に示すように、複数本の上記ポンチ５の刃５ｃと刃５ｃの間に上記ポンチ５の刃５ｃと同等の深さとなるように分割溝形成用の刃６を装着して金型を構成し、該金型でセラミックスグリーンシートを打ち抜き生製品を得る。
【００２０】
次に、得られた生製品である上記の打ち抜かれたセラミックスグリーンシートを所定の温度で焼成することにより、図２（ｃ）に示すＣ面部２ａを有する貫通孔２とそのＣ面部２ａまで分割溝３が連続して形成されたセラミックス基板１が得られる。
【００２１】
本発明のセラミックス基板１の材質は特に限定するものではなく、アルミナ、ジルコニア、ムライト、窒化珪素、窒化アルミニウム等を主成分とするセラミックス焼結体を用いることができる。また本発明のセラミックス基板１の貫通孔２と重なる分割溝３は一方向のみで説明したが、いずれの方向の分割溝３，４共、その分割溝３，４上に貫通孔２が形成されていても良い。さらに上記分割溝断面形状はＶ字状、Ｕ字状、多段Ｖ字状を含む略Ｖ字状であって、また、貫通孔２の平面形状は円形で断面形状は表面開孔部をＣ面としたが、これに限らず曲面状を含む略Ｃ面形状であれば良い。
【００２２】
また、本発明のセラミックス基板１は、前述した材質を主成分とするセラミックス粉末に、結合剤、焼結助剤等を添加したものを公知のドクターブレード法またはロールコンパクション法等によりシート状に成形したセラミックスグリーンシートに前述した穿孔用のポンチ５並びに分割溝形成用の刃６を金型に備え、セラミックスグリーンシートに押し当てることにより同時成型するものであり、ポンチ５並びに刃６の材質は強度上超硬合金が好ましい。
【００２３】
さらに、上記により得られた生製品であるセラミックスグリーンシートを所定の温度で焼成することにより本発明のセラミックス基板１を製造することが出来る。
【００２４】
このようにして得られた本発明のセラミックス基板１は、例えば図３の単体のセラミックス基板１ａの斜視図に示すように、前述したシート状のセラミックス基板１の貫通孔２が分割後の単体のセラミックス基板１ａにおいては半円凹部８となり、この半円凹部８は端面電極７として利用されることが多い。その製造過程において、貫通孔２にＣ面部２ａが形成されている為に、ペーストがスムーズに吸引され、また貫通孔２の表面が極端な矩形をなしていないために、エッジ部での導体切れ等が発生せず貫通孔２の各部にわたり均一な膜厚で形成出来る。さらに分割溝３がＣ面部２ａ迄達しているために分割性が良く、単体に分割したセラミックス基板１ａの端面電極７の箇所にバリ状の突出部或いは凹み状となったり、また端面電極７が部分的にセラミックスから剥離するという問題が発生しない。
【００２５】
またこれらの効果を奏するためには、図４に示す貫通孔２のＣ面部２ａの深さＤ２はセラミックス基板１の厚みｔに対し、８〜２０％が好ましく、分割溝３の深さＤ１はＣ面部２ａの深さＤ２と同一或いは、これよりも深く形成し、その好ましい範囲はセラミックス基板１の厚みｔの８〜４０％である。また貫通孔２のＣ面部２ａの幅Ｗは導体形成用ペーストの吸引をスムーズにするためのものであるが、隣り合う電極間クリアランス等のパターン設計上から決めれば良く、少なくともセラミックス基板１の厚みｔの５〜２０％程度の範囲にあれば良い。尚、分割溝３の深さＤ１とは、図１（ｃ）に示す、貫通孔２間の分割溝３並びに貫通孔２のＣ面部２ａ域の分割溝３ａを総称しており、上記のそれぞれの分割溝３，３ａの深さＤ１は良好な分割性を得るために同一深さに形成する。
【００２６】
ここで、貫通孔２間の分割溝３の深さＤ１を貫通孔２のＣ面部２ａの深さＤ２と同一或いは、これよりも深くする理由は、貫通孔２のＣ面部２ａはセラミックスグリーンシートへ金型により押圧成型するために、貫通孔２のＣ面部２ａの深さＤ２を深く成型するとその圧縮応力により貫通孔２の周縁表面に盛り上がりを呈し、これは後の回路印刷に支障を来たすことになる。この盛り上がりを少なくともセラミックス基板１の厚みｔの０．８％程度以内に抑えるためには、そのＣ面部２ａの深さＤ２は最大で厚みｔの２０％が実験的に限度であることが解っている。
【００２７】
また、分割溝３の深さＤ１は、経験上セラミックス基板１の厚みｔに対し８〜４０％の範囲内であれば分割性並びに分割工程前での割れ防止の両面から適当であることが解っているが、貫通孔２のＣ面部２ａの箇所は押圧により密度が高くなっているために、Ｃ面部２ａの深さＤ２より分割溝３ａの深さＤ１が浅いと、Ｃ面部２ａの分割溝３ａで分割不良が発生する可能性があり、良好な分割性を得るためには、Ｄ１≧Ｄ２の深さに形成すれば良い。
【００２８】
【実施例】
ここで、図５（ａ）に示す本発明実施例のセラミックス基板１と、図６（ａ）に示す比較例１のセラミックス基板２１、並びに図７（ａ）に示す比較例２のセラミックス基板３１を各々２０シートずつ製作した。尚、比較例１の製造方法は前述した図９（ａ）に示すＣ面１８ｂを有するポンチ１８と刃１９を金型に装着してセラミックスグリーンシートに押し当てる方法、比較例２は図１０（ｃ）に示した刃（成形刃）１１９とポンチ（スルーホール打ち抜きピン）１１８を金型に装着してセラミックスグリーンシートに押し当てて成型した。
【００２９】
尚、セラミックスグリーンシートはアルミナ９６％でドクターブレード法により成形したシート状のものを用い焼成後の厚みｔが０．６３５ｍｍとなるものを用いた。
【００３０】
焼成後におけるセラミックス基板１，２１，３１の各寸法が表１に示す値となるように金型を設定し上記セラミックスグリーンシートを成型し、その後、このセラミックスグリーンシートを酸化雰囲気連続焼成炉にて最高温度約１６００℃で焼成し各各のセラミックス基板１，２１，３１を得た。
【００３１】
尚、セラミックス基板１，２１，３１の貫通孔２，２２，３２は、単体のセラミックス基板１ａ，２１ａ，３１ａの長辺側左右に各４個形成し、図５（ｂ）、図６（ｂ）、図７（ｂ）に示す、表面側の大きな孔径φ１は０．６ｍｍ、裏面側の小さな孔径φ２は０．４ｍｍとし、従って、本発明実施例並びに比較例１のＣ面部２ａ，２２ａの幅Ｗ及び比較例２の大きな孔３２ａの矩形状段差部の幅Ｗはいずれも０．１ｍｍ（基板厚みｔの１５．７％）で、図５（ｃ）、図６（ｃ）、図７（ｃ）に示す、本発明並びに比較例１のＣ面部２２ａの深さＤ２と比較例２の大きな孔３２ａの深さＤ２は０．１ｍｍ（基板厚みｔの１５．７％）で、上記貫通孔２，２２，３２と重なる分割溝３．２３．３３の深さＤ１は、いずれも０．１ｍｍ（基板厚みｔの１５．７％）とした。
【００３２】
本発明実施例、比較例１，２の上記各寸法値を表１に示す。
【００３３】
【表１】

【００３４】
上記の本発明実施例、比較例１，２の各セラミックス基板１，２１，３１について、貫通孔２，２２，３２が形成されていない縦方向の分割溝４，２４，３４を各々先に分割し、次に貫通孔２，２２，３２と重なる分割溝３，２３，３３をハンドブレイクにより分割し、本発明実施例、比較例１，２各々１６０枚の製品部である単体のセラミックス基板１ａ，２１ａ，３１ａを作成した。
【００３５】
次に図６（ｂ）、図７（ｂ）、図８（ｂ）の分割後のセラミックス基板１ａ，２１ａ，３１ａに示すように、バリの高さｈ１或いはその逆の凹みの大きさｃを各々金属顕微鏡で測定し、いずれの値も０．１ｍｍ以上あるものは不良とし、その不良数を各々の製品部であるセラミックス基板単体数の１６０枚で除し、分割不良率を算出した。
【００３６】
更に、上記セラミックス基板１ａ，２１ａ，３１ａについて、図６（ｃ）、図７（ｃ）、図８（ｃ）に示す、孔周縁の盛り上がりの高さｈ２について、金属顕微鏡にて各々５枚測定しその平均値を算出した。また盛り上がりの高さｈ２の良否判定は、厚膜導体印刷のシビアなレベルである５μｍ以上を否とする基準を適用した。
【００３７】
以上の結果を表２に示す。
【００３８】
【表２】

【００３９】
この結果から解るように、本発明実施例は、貫通孔２のＣ面部２ａまで分割溝３が形成されているために、分割不良の発生は皆無であった。これに対し、比較例１は貫通孔２２のＣ面部２２ａの箇所には分割溝２３が形成されていないために分割不良が３．７５％と多発した。比較例２は、孔周辺の盛り上がりより分割性を優先し、分割溝３３の深さＤ２を本発明実施例と同じにしたものであるが、しかしながら分割不良が１．２５％発生した。この原因は推測であるが、貫通孔３２の大きな孔３２ａが矩形状段差であり、分割溝３３の分割進行方向応力を貫通孔３２の大きな孔３２の矩形状段差部で分散させるためと見られる。
【００４０】
次に、貫通孔２，２２，３２周縁の盛り上がりの高さｈ２については、良否判定値５μｍに対し本発明実施例は平均値２．７μｍ、比較例１は平均２．５μｍと十分満足している。しかし、比較例２は孔周縁の盛り上がりの高さｈ２の平均値は５．７μｍと大きく規格外となった。これは矩形状の大きな孔３２ａの成型体積がＣ面形成に比較し多い分、孔周縁の盛り上がりとなって表れたたものである。
【００４１】
【発明の効果】
以上のように、本発明の製造方法により得られたセラミックス基板は、分割溝が貫通孔のＣ面部まで連続して形成され、かつ上記分割溝の深さが上記貫通孔のＣ面部の深さと同一、もしくはこれより深く形成されているために、貫通孔間の分割溝の分割性が良好であって、かつ貫通孔周縁への盛り上がりも低く抑えられる。
【００４２】
従って、本発明のセラミックス基板を用いて分割溝と重なる貫通孔に端面電極用導体を形成し分割したとすると、分割時の導体へ及ぼす応力を抑えられ導体剥離等の不良発生を防止出来る。
【図面の簡単な説明】
【図１】（ａ）は本発明のセラミックス基板の一例を示す平面図で、（ｂ）はその断面図である。
【図２】（ａ）は本発明のセラミックス基板の製造方法に用いる穿孔用ポンチの斜視図で、（ｂ）はこの穿孔用刃ポンチを用いた金型の断面図、（ｃ）は本発明のセラミックス基板の部分拡大した平面図である。
【図３】分割後の本発明のセラミックス基板の一例を示す斜視図である。
【図４】本発明のセラミックス基板における分割溝と貫通孔の部分的な断面図である。
【図５】（ａ）は本発明のセラミックス基板の平面図で、（ｂ）は分割後のセラミックス基板の平面図、（ｃ）はその貫通孔の断面図である。
【図６】（ａ）は従来のセラミックス基板の平面図で、（ｂ）は分割後のセラミックス基板の平面図、（ｃ）はその貫通孔の断面図である。
【図７】（ａ）は他の従来のセラミックス基板の平面図で、（ｂ）は分割後のセラミックス基板の平面図、（ｃ）はその貫通孔の断面図である。
【図８】（ａ）は従来のセラミックス基板の平面図で、（ｂ）は分割後のセラミックス基板の斜視図、（ｃ）は貫通孔の断面図である。
【図９】（ａ）は従来のセラミックス基板の製造装置の断面図で、（ｂ）はそれにより形成されたセラミックス基板の部分平面図、（ｃ）はその断面図である。
【図１０】（ａ）は他の従来例のセラミックス基板の部分的な平面図で、（ｂ）はその断面図、（ｃ）はその製造装置の断面図である。
【符号の説明】
１：セラミックス基板
１ａ：単体のセラミックス基板
２：貫通孔
２ａ：Ｃ面部
３：分割溝
３ａ：Ｃ面部分割溝
４：分割溝
５：ポンチ
５ａ：ストレート部
５ｂ：Ｃ面部
５ｃ：刃
６：刃
７：端面電極
８：半円凹部
ｔ：厚み
Ｄ１：深さ
Ｄ２：深さ
Ｗ：幅
ｈ１：バリの高さ
ｈ２：盛り上がりの高さ
ｃ：凹みの大きさ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ceramic substrate for electronic parts that is formed between a through hole after a conductor is formed in the through hole.
[0002]
[Prior art]
FIG. 8A is a plan view of a general ceramic substrate 11 for electronic components formed such that a plurality of dividing grooves 13 overlap with the through holes 12. The main application of the through-hole 12 of the ceramic substrate 11 of this shape is an end face electrode, and after forming a conductor for conducting conduction between the front and back of the ceramic substrate 11 in the through-hole 12 of the sheet-like ceramic substrate 11, the divided grooves are formed. By dividing 13 and 14, a ceramic substrate 11a having a plurality of semicircular recesses 15 as shown in the perspective view of FIG.
[0003]
The semicircular recess 15 is provided with end face electrodes 16 for electrically connecting the front and back of the ceramic substrate 11a. Although not shown, the ceramic substrate 11a is mounted on a circuit board, and the ceramic substrate 11a is mounted. The end face electrode 16 is used to electrically connect the electronic component circuit chip or resistor film mounted on the surface of the substrate and the circuit board land.
[0004]
The through-holes 12 for the purpose of forming these conductors are formed on the surface side of the through-holes 12 as shown in the sectional view of the ceramic substrate 11 shown in FIG. 8C so that the conductor paste can be sucked smoothly. It has been a good Ku carried out to form a C surface portion 17.
[0005]
As a method of manufacturing the ceramic substrate 11 in a shape in which the dividing groove 13 overlaps the through hole 12 having the C surface portion 17, as shown in the cross-sectional view of FIG. 9A, the punch 18 having the C surface portion 18 b and By installing the split groove forming blades 19 on the right and left sides of the mold and pressing the blades against the ceramic green sheet, the through holes 12 and the split grooves 13 as shown in the plan view of the ceramic substrate 11 in FIG. Is formed, and the ceramic substrate 11 is obtained by firing at a predetermined temperature.
[0006]
However, the dividing groove 13 and the through hole 12 have a shape in which the dividing groove 13 is interrupted in the vicinity of the through hole 12 as shown in the sectional view of the ceramic substrate 11 shown in FIG. There was a problem that splitting burrs occurred when splitting.
[0007]
According to Japanese Patent Laid-Open No. 4-206802, the through hole 112 and the division groove 113 shown in the plan view of the ceramic substrate 111 in FIG. 10A solve the problem of this division burr and at the time of sucking the paste into the through hole 112. For the purpose of preventing the flow into the dividing groove 113, as shown in the cross-sectional view of FIG. 10B, a hole 112a having a large diameter is provided on the front surface side of the ceramic substrate 111 and a hole 112b having a small diameter on the back surface side. It is described that the dividing groove 113 overlapping the through hole 112 is formed on the side of the large diameter hole 112a described above and shallower than the large diameter hole 112a.
[0008]
As for the manufacturing method, as shown in FIG. 10 (c), the dividing groove 113 is pressed with a blade (forming blade) 119, the through hole 112 is pressed with a punch (through hole punching pin) 118, and the ceramic green sheet is simultaneously pressed. Although it is described that the outer periphery is cut with the dividing groove orthogonal to the dividing groove 113 in the next step, the large-diameter hole 112a is formed by the protruding portion 119a that is integral with the blade 119 in the drawing. However, the detailed structure is not described.
[0009]
[Problems to be solved by the invention]
When the through-hole 12 overlapping the dividing groove 13 is formed by the punch 18 having the C-surface portion 18b shown in FIG. 9A and the blade 19, the C-surface portion 17 of the through-hole 12 is formed as shown in FIG. 9C. When the dividing groove 13 is interrupted and the dividing groove 13 is divided, a dividing burr is generated, and a large stress is applied to the end face electrode conductor at the time of the dividing, and the fracture surface is projected or recessed, or in an extreme case However, there was a problem that the conductor peeling partially occurred.
[0010]
Further, according to the aforementioned Japanese Patent Laid-Open No. 4-206802, the depth of the dividing groove 113 is made smaller than the depth of the hole 112a having a large diameter of the through hole 112 shown in FIG. However, when the rectangular recess is formed by pressing against the ceramic green sheet, the surface of the ceramic substrate is swelled due to stress escape, which has a problem of adversely affecting circuit printing to be formed later. Further, if the depth of the large-diameter hole 112a is set to be shallow in order to suppress the bulge around the hole, the depth of the dividing groove 113 is further reduced, and even though the problem of paste flowing into the dividing groove is solved, In this case, as in the case described above, the fracture surface is projected or recessed, and in the extreme case, the conductor is partially separated. there were.
[0011]
Further, when the conductor is formed because the hole 112a having a large diameter has a rectangular shape in the cross section of the through hole 112, a place where the thickness of the conductor film applied to the edge portion of the through

hole

112, 112a is extremely thin is generated and the conductor is cut. There was also a problem of reliability.
[0012]
[Means for Solving the Problems]
In view of the above problems, the ceramic substrate of the present invention is a ceramic substrate in which a plurality of divided grooves and a plurality of through holes in which end surface electrode conductors are formed so as to overlap the divided grooves are formed on the surface. The planar shape is circular and has a C-surface portion on the surface side opening, the dividing groove is continuously formed up to the C-surface portion of the through-hole, and the depth of the dividing groove is the C-surface portion of the through-hole. It is characterized by being equal to or deeper than the depth of .
Moreover , the ceramic substrate for electronic components of the present invention is a ceramic substrate for electronic components in which a plurality of divided grooves and a plurality of through holes in which end surface electrode conductors are formed so as to overlap the divided grooves are formed on the surface. The through-hole has a circular planar shape and has a C-surface portion on the surface-side opening, the divided groove is continuously formed up to the C-surface portion of the through-hole, and has the same depth as the C-surface portion of the divided groove. Or it is deeper than this .
[0013]
Further, in the method of manufacturing a ceramic substrate in which a plurality of divided grooves and a through-hole having a plurality of C-surface portions so as to overlap the divided grooves are formed on the surface, the punch for punching the through-hole has a straight portion at the tip. the way from having a C surface of larger diameter than said straight portion diameter, it includes a left right pair of blades in the C face or the straight portion, of the punch between the blade and blade plurality of said punch A die is formed by attaching a blade for forming a dividing groove so that the depth is the same as the blade, and a ceramic green sheet is punched with the die, and the punched ceramic green sheet is fired at a predetermined temperature. It consists of a process.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0015]
Fig.1 (a) is a top view which shows an example of the ceramic substrate of this invention.
[0016]
The ceramic substrate 1 has a plurality of divided grooves 3 and 4 and a plurality of through holes 2 in which end surface electrode conductors are formed so as to overlap the divided grooves 3 on the surface. The through-hole 2 has a circular planar shape and has a C-surface portion 2a in the front side opening portion. As shown in FIG. 1B, a sectional view of the divided groove 2 is formed. It is formed continuously up to the C surface portion 2a of the through hole 2, and the depth D1 of the dividing groove 3 is the same as or deeper than the depth D2 of the C surface portion 2a of the through hole 2. Features.
[0017]
Next, the manufacturing method of the ceramic substrate 1 of this invention is demonstrated.
[0018]
FIG. 2A shows a perspective view of a punch 5 for punching a through-hole 2 which is an example of the present invention. The punch 5 for punching has a straight portion 5a at the tip and a diameter of the straight portion 5a from the middle thereof. and a C face 5b of the larger diameter, and a left right pair of blades 5c on the C surface 5b or the straight portion 5a.
[0019]
Next, as shown in the cross-sectional view of FIG. 2 (b), a blade for forming a split groove is formed between the blades 5c of the punch 5 and the blade 5c so as to have a depth equivalent to the blade 5c of the punch 5. 6 is mounted to form a mold, and a ceramic green sheet is punched with the mold to obtain a raw product.
[0020]
Next, the punched ceramic green sheet that is the obtained raw product is fired at a predetermined temperature to divide the through hole 2 having the C surface portion 2a shown in FIG. 2C and the C surface portion 2a. A ceramic substrate 1 in which the grooves 3 are continuously formed is obtained.
[0021]
The material of the ceramic substrate 1 of the present invention is not particularly limited, and a ceramic sintered body mainly composed of alumina, zirconia, mullite, silicon nitride, aluminum nitride, or the like can be used. Further, the dividing groove 3 overlapping with the through hole 2 of the ceramic substrate 1 of the present invention has been described in only one direction. However, the through hole 2 is formed on the dividing grooves 3 and 4 in both directions. May be. Furthermore, the sectional shape of the dividing groove is a V shape including a V shape, a U shape, and a multi-stage V shape, and the planar shape of the through-hole 2 is a circle, and the cross-sectional shape is a C-plane with a surface opening portion. However, the present invention is not limited to this, and may be any substantially C-plane shape including a curved surface shape.
[0022]
Further, the ceramic substrate 1 of the present invention is formed into a sheet shape by a known doctor blade method or roll compaction method, etc., in which a binder, a sintering aid, and the like are added to the ceramic powder having the above-mentioned material as a main component. The punch 5 for punching and the blade 6 for forming the dividing groove are provided in the mold on the ceramic green sheet, and are simultaneously molded by pressing against the ceramic green sheet. The material of the punch 5 and the blade 6 is strength. Upper cemented carbide is preferred.
[0023]
Furthermore, the ceramic substrate 1 of this invention can be manufactured by baking the ceramic green sheet which is the raw product obtained by the above at a predetermined temperature.
[0024]
The ceramic substrate 1 of the present invention thus obtained is, for example, as shown in a perspective view of a single ceramic substrate 1a in FIG. The ceramic substrate 1 a has a semicircular recess 8, and this semicircular recess 8 is often used as the end face electrode 7. In the manufacturing process, since the C-surface part 2a is formed in the through hole 2, the paste is sucked smoothly, and the surface of the through hole 2 does not form an extreme rectangle, so the conductor breaks at the edge part. And the like can be formed with a uniform film thickness over each part of the through-hole 2. Further, since the dividing groove 3 reaches the C surface portion 2a, the dividing property is good, and a burr-like protruding portion or a concave shape is formed at the position of the end surface electrode 7 of the ceramic substrate 1a divided into a single piece. The problem of partial peeling from the ceramic does not occur.
[0025]
Also in order to response rates of these effects, with respect to the depth D2 is the thickness t of the ceramic substrate 1 of the C-surface portion 2a of the through hole 2 shown in FIG. 4, is preferably 8-20%, the depth of the dividing groove 3 D1 Is formed to be equal to or deeper than the depth D2 of the C-plane portion 2a, and a preferable range thereof is 8 to 40% of the thickness t of the ceramic substrate 1. The width W of the C surface 2a of the through hole 2 but intended for a smooth aspiration of the conductor forming paste, may be determined from the pattern design such as between adjacent electrodes clear lance, at least a ceramic substrate 1 It suffices if it is in the range of about 5 to 20% of the thickness t. The depth D1 of the dividing groove 3 is a generic term for the dividing groove 3 between the through holes 2 and the dividing groove 3a in the C surface portion 2a region of the through hole 2 shown in FIG. The depths D1 of the dividing grooves 3 and 3a are formed at the same depth in order to obtain a good dividing property.
[0026]
Here, the reason why the depth D1 of the dividing groove 3 between the through holes 2 is the same as or deeper than the depth D2 of the C surface portion 2a of the through holes 2 is that the C surface portion 2a of the through holes 2 is a ceramic green sheet. If the depth D2 of the C-surface portion 2a of the through hole 2 is deeply formed by press molding with a metal mold, the peripheral surface of the through hole 2 is raised due to the compressive stress, which hinders subsequent circuit printing. It will be. In order to suppress this rise to at least about 0.8% of the thickness t of the ceramic substrate 1, it is understood that the maximum depth D2 of the C-surface portion 2a is experimentally 20% of the thickness t. Yes.
[0027]
Further, from experience, it is understood that the depth D1 of the dividing groove 3 is appropriate in terms of both dividing property and prevention of cracking before the dividing step if it is within a range of 8 to 40% with respect to the thickness t of the ceramic substrate 1. However, since the density of the portion of the C surface portion 2a of the through hole 2 is increased by pressing, if the depth D1 of the dividing groove 3a is shallower than the depth D2 of the C surface portion 2a, the dividing groove of the C surface portion 2a There is a possibility that a division failure may occur at 3a, and in order to obtain a good division property, it may be formed to a depth of D1 ≧ D2.
[0028]
【Example】
Here, the ceramic substrate 1 of the embodiment of the present invention shown in FIG. 5 (a), the ceramic substrate 21 of Comparative Example 1 shown in FIG. 6 (a), and the ceramic substrate 31 of Comparative Example 2 shown in FIG. 7 (a). 20 sheets each were manufactured. The manufacturing method of Comparative Example 1 is a method in which the punch 18 having the C surface 18b and the blade 19 shown in FIG. 9A described above are mounted on a mold and pressed against a ceramic green sheet, and Comparative Example 2 is shown in FIG. The blade (molding blade) 119 and punch (through hole punching pin) 118 shown in c) were mounted on a mold and pressed against a ceramic green sheet for molding.
[0029]
In addition, the ceramic green sheet used the sheet-like thing shape | molded by 96% of alumina by the doctor blade method, and used the thickness t after baking to be 0.635 mm.
[0030]
The mold is set so that the dimensions of the

ceramic substrates

1, 21, 31 after firing become the values shown in Table 1, and the ceramic green sheet is molded. Thereafter, the ceramic green sheet is subjected to an oxidizing atmosphere continuous firing furnace. Each

ceramic substrate

1, 21, 31 was obtained by firing at a maximum temperature of about 1600 ° C.
[0031]
In addition, four through

holes

2, 22, and 32 of the

ceramic substrates

1, 21, and 31 are formed on each of the left and right sides of the long side of the single

ceramic substrate

1a, 21a, and 31a, and FIG. 5 (b) and FIG. 6 (b). 7), the large hole diameter φ1 on the front surface side is 0.6 mm, and the small hole diameter φ2 on the back surface side is 0.4 mm. Therefore, the

C surface portions

2a and 22a of the embodiment of the present invention and the comparative example 1 The width W and the width W of the rectangular step portion of the large hole 32a of Comparative Example 2 are both 0.1 mm (15.7% of the substrate thickness t), and are shown in FIGS. 5 (c), 6 (c), 7 The depth D2 of the C surface portion 22a of the present invention and Comparative Example 1 shown in (c) and the depth D2 of the large hole 32a of Comparative Example 2 are 0.1 mm (15.7% of the substrate thickness t), and the above penetration The depth D1 of the dividing groove 3.23.33 that overlaps the

holes

2, 22, and 32 is 0.1 mm (of the substrate thickness t). 15.7%).
[0032]
Table 1 shows the respective dimension values of the inventive examples and comparative examples 1 and 2.
[0033]
[Table 1]

[0034]
For the

ceramic substrates

1, 21 and 31 of the above-described inventive examples and comparative examples 1 and 2, the vertical dividing grooves 4, 24 and 34 in which the through

holes

2, 22, and 32 are not formed are divided first. Then, the divided

grooves

3, 23, 33 that overlap with the through

holes

2, 22, 32 are divided by hand break, and a single ceramic substrate 1a that is 160 product parts of the embodiment of the present invention and the comparative examples 1 and 2 each. , 21a, 31a were created.
[0035]
Next, as shown in the divided

ceramic substrates

1a, 21a, 31a in FIGS. 6B, 7B, and 8B, the height b1 of the burr or the size c of the recess is reversed. Measured with a metal microscope, each value of 0.1 mm or more was regarded as defective, and the number of defects was divided by the number of single ceramic substrates, which are each product part, to calculate the division defect rate.
[0036]
Further, with respect to the

ceramic substrates

1a, 21a, 31a, the height h2 of the rising edge of the hole periphery shown in FIGS. 6 (c), 7 (c), and 8 (c) is measured with a metal microscope. The average value was calculated. In addition, for the quality determination of the height h2, the standard for rejecting 5 μm or more, which is a severe level of thick film conductor printing, was applied.
[0037]
The results are shown in Table 2.
[0038]
[Table 2]

[0039]
As can be seen from this result, in the embodiment of the present invention, since the dividing groove 3 was formed up to the C surface portion 2a of the through hole 2, there was no occurrence of division failure. On the other hand, since the division groove 23 was not formed in the location of the C surface part 22a of the through hole 22 in the comparative example 1, the division failure occurred frequently at 3.75%. In Comparative Example 2, the splitting property is given priority over the rise around the hole, and the depth D2 of the dividing groove 33 is made the same as that of the embodiment of the present invention. Although this is speculated, the large hole 32a of the through hole 32 is a rectangular step, and it is considered that the stress in the dividing direction of the dividing groove 33 is dispersed in the rectangular step portion of the large hole 32 of the through hole 32. .
[0040]
Next, with respect to the height h2 of the swell of the peripheral edges of the through

holes

2, 22, 32, the example of the present invention was sufficiently satisfied with an average value of 2.7 μm and a comparative example 1 with an average of 2.5 μm with respect to a pass / fail judgment value of 5 μm Yes. However, in Comparative Example 2, the average value of the height h2 of the rising edge of the hole periphery was as large as 5.7 μm, which was out of specification. This is because the molding volume of the rectangular large hole 32a is larger than that of the C-plane formation, and appears as a swell of the hole periphery.
[0041]
【The invention's effect】
As described above, in the ceramic substrate obtained by the manufacturing method of the present invention, the dividing groove is continuously formed up to the C surface portion of the through hole, and the depth of the dividing groove is equal to the depth of the C surface portion of the through hole. Since they are formed to be the same or deeper than this, the splitting ability of the split grooves between the through holes is good, and the rise to the periphery of the through holes is suppressed to a low level.
[0042]
Accordingly, a penetrating hole which overlaps with the dividing grooves to form a conductor edge electrode resolved using ceramic substrate of the present invention result, suppresses stress on the time division of the conductor can be prevented occurrence of defects of the conductor peeling.
[Brief description of the drawings]
FIG. 1A is a plan view showing an example of a ceramic substrate of the present invention, and FIG. 1B is a cross-sectional view thereof.
2A is a perspective view of a punch for punching used in the method for manufacturing a ceramic substrate of the present invention, FIG. 2B is a cross-sectional view of a mold using the punch for punching, and FIG. It is the top view to which the ceramic substrate of this was expanded.
FIG. 3 is a perspective view showing an example of the ceramic substrate of the present invention after division.
FIG. 4 is a partial cross-sectional view of a dividing groove and a through hole in the ceramic substrate of the present invention.
5A is a plan view of the ceramic substrate of the present invention, FIG. 5B is a plan view of the ceramic substrate after division, and FIG. 5C is a cross-sectional view of the through hole.
6A is a plan view of a conventional ceramic substrate, FIG. 6B is a plan view of the divided ceramic substrate, and FIG. 6C is a cross-sectional view of the through hole.
7A is a plan view of another conventional ceramic substrate, FIG. 7B is a plan view of the divided ceramic substrate, and FIG. 7C is a sectional view of the through hole.
8A is a plan view of a conventional ceramic substrate, FIG. 8B is a perspective view of the divided ceramic substrate, and FIG. 8C is a cross-sectional view of the through hole.
9A is a cross-sectional view of a conventional ceramic substrate manufacturing apparatus, FIG. 9B is a partial plan view of a ceramic substrate formed thereby, and FIG. 9C is a cross-sectional view thereof.
10A is a partial plan view of another conventional ceramic substrate, FIG. 10B is a cross-sectional view thereof, and FIG. 10C is a cross-sectional view of the manufacturing apparatus thereof.
[Explanation of symbols]
1: Ceramic substrate 1a: Single ceramic substrate 2: Through hole 2a: C surface portion 3: Dividing groove 3a: C surface portion dividing groove 4: Dividing groove 5: Punch 5a: Straight portion 5b: C surface portion 5c: Blade 6: Blade 7 : End face electrode 8: Semicircular recess t: Thickness D1: Depth D2: Depth W: Width h1: Burr height h2: Swelling height c: Depression size

Claims

In the ceramic substrate having a plurality of divided grooves formed on the surface and a plurality of through holes in which end face electrode conductors are formed so as to overlap the divided grooves, the through holes have a circular planar shape and have a surface-side opening. It has a C surface portion, the dividing groove is continuously formed up to the C surface portion of the through hole, and the depth of the dividing groove is the same as or deeper than the depth of the C surface portion of the through hole. A ceramic substrate.

In a ceramic substrate for electronic parts having a plurality of through holes on the surface and a plurality of through holes in which end surface electrode conductors are formed so as to overlap the divided grooves, the through holes have a circular planar shape and are open on the surface side. An electronic component having a C-surface portion in a hole, wherein the dividing groove is continuously formed up to the C-surface portion of the through-hole, and having the same depth as or deeper than the depth of the C-surface portion of the dividing groove use a ceramic substrate.

In the method of manufacturing a ceramic substrate in which a plurality of divided grooves and a through-hole having a plurality of C-surface portions are formed so as to overlap the divided grooves on the surface, the punch for punching the through-hole includes a straight portion at a tip and a middle portion thereof more has a C surface of larger diameter than said straight portion diameter, it includes a left right pair of blades in the C face or the straight portion, and the punch blades between the blade and blade plurality of said punch A step of forming a mold by attaching a blade for forming a dividing groove to have an equivalent depth, a step of punching out the ceramic green sheet with the die, and a step of firing the punched ceramic green sheet at a predetermined temperature; A method for producing a ceramic substrate comprising: