JP3838940B2 - Wiring board - Google Patents

Wiring board Download PDF

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Publication number
JP3838940B2
JP3838940B2 JP2002147927A JP2002147927A JP3838940B2 JP 3838940 B2 JP3838940 B2 JP 3838940B2 JP 2002147927 A JP2002147927 A JP 2002147927A JP 2002147927 A JP2002147927 A JP 2002147927A JP 3838940 B2 JP3838940 B2 JP 3838940B2
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brazing material
pad
external electric
electric circuit
wiring board
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JP2003338585A (en
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浩一 平山
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Kyocera Corp
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Kyocera Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/26—Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
    • H01L2224/31—Structure, shape, material or disposition of the layer connectors after the connecting process
    • H01L2224/32—Structure, shape, material or disposition of the layer connectors after the connecting process of an individual layer connector
    • H01L2224/321—Disposition
    • H01L2224/32151—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
    • H01L2224/32221—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
    • H01L2224/32225—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being non-metallic, e.g. insulating substrate with or without metallisation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/4805—Shape
    • H01L2224/4809—Loop shape
    • H01L2224/48091—Arched
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/481—Disposition
    • H01L2224/48151—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
    • H01L2224/48221—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
    • H01L2224/48225—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being non-metallic, e.g. insulating substrate with or without metallisation
    • H01L2224/48227—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being non-metallic, e.g. insulating substrate with or without metallisation connecting the wire to a bond pad of the item
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/73—Means for bonding being of different types provided for in two or more of groups H01L2224/10, H01L2224/18, H01L2224/26, H01L2224/34, H01L2224/42, H01L2224/50, H01L2224/63, H01L2224/71
    • H01L2224/732—Location after the connecting process
    • H01L2224/73251—Location after the connecting process on different surfaces
    • H01L2224/73265—Layer and wire connectors

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  • Wire Bonding (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は半導体素子収納用パッケージ等に用いられる配線基板に関し、詳しくは実装した半導体素子の各電極を所定の外部電気回路に長期間にわたり安定して電気的に接続させることができる配線基板に関するものである。
【０００２】
【従来の技術】
従来、半導体素子が搭載される配線基板は、酸化アルミニウム質焼結体やガラスセラミック焼結体、窒化アルミニウム質焼結体、ムライト質焼結体、炭化珪素質焼結体等の電気絶縁材料から成り、その表面に半導体素子が搭載される搭載部を有する絶縁基体と、絶縁基体の半導体素子搭載部またはその周辺から下面にかけて導出される、例えばタングステンやモリブデン等の金属粉末から成る複数個の配線導体と、絶縁基体の下面に形成され、前記配線導体と電気的に接続された複数個の平面四角形状をなす接続パッドとから構成されており、絶縁基体の搭載部に半導体素子をガラス、樹脂、ロウ材等から成る接着剤を介して接着固定させるとともに半導体素子の各電極と配線導体とをボンディングワイヤ等の電気的接続手段を介して電気的に接続し、しかる後、必要に応じて前記半導体素子を蓋体や封止樹脂で気密封止させることによって半導体装置となる。
【０００３】
かかる半導体装置は、外部電気回路基板上に、該外部電気回路基板の回路配線と絶縁基体下面の接続パッドとが、間に錫−鉛半田等の低融点ロウ材を挟んで対向するよう載置させ、しかる後、前記低融点ロウ材を約２００℃〜３００℃の温度で加熱溶融させ、外部電気回路基板の回路配線と絶縁基体下面の接続パッドとを接合させることにより外部電気回路基板に実装され、同時に配線基板に搭載されている半導体素子の各電極が配線導体および低融点ロウ材を介して外部電気回路基板に電気的に接続されることとなる。
【０００４】
【発明が解決しようとする課題】
しかしながら、上記従来の半導体素子が搭載される配線基板は絶縁基体が酸化アルミニウム質焼結体やガラスセラミック焼結体等のセラミックス材料で形成されており、その熱膨張係数が約３×１０-6／℃〜７．５×１０-6／℃であるのに対し、外部電気回路基板は一般にガラスエポキシ樹脂等の樹脂材で形成されており、その熱膨張係数が３０×１０-6／℃〜５０×１０-6／℃であり、両者、大きく相異することから配線基板の接続パッドと外部電気回路基板の回路配線とを低融点ロウ材を介して接合させて外部電気回路基板上に半導体装置を実装した後、半導体素子の作動時に発する熱が配線基板の絶縁基体と外部電気回路基板に繰り返し作用した場合、配線基板の絶縁基体と外部電気回路基板との間に大きな熱応力が繰り返し発生し、これが配線基板の接続パッドと低融点ロウ材との接合界面に作用して低融点ロウ材に破断が発生してしまい、その結果、半導体素子と外部電気回路との電気的接続が短期間で破れてしまうという欠点があった。
【０００５】
そこで、上記欠点を解消するために絶縁基体のコーナー部に前記接続パッドと同じ材料、同じ方法によって四角形状の補助パッドを設けておき、この補助パッドを外部電気回路基板に設けたダミーのパッド等に低融点ロウ材を介し接続することによって接続パッドと低融点ロウ材との間に熱応力が作用するのを防止し、接続パッドと低融点ロウ材との接合を強固として半導体素子と外部電気回路との電気的接続の信頼性を向上させるという手段が考えられる。
【０００６】
しかしながら、配線基板の絶縁基体のコーナー部に四角形状の補助パッドを設けた場合、外部電気回路基板上に配線基板を実装した直後は、補助パッドと外部電気回路基板に設けたダミーのパッド等との接合が接続パッドと低融点ロウ材との間に作用する熱応力を除去し、接続パッドと低融点ロウ材との接合界面付近に破断が生じるのを有効に防止することができるものの続けて使用し、配線基板の絶縁基体と外部電気回路基板との間に発生する熱応力が補助パッドと低融点ロウ材に繰り返し作用した場合、補助パッドと低融点ロウ材との接合界面（特に外縁部）に破断が発生して接続パッドと低融点ロウ材との間に熱応力が発生するのを有効に防止することができなくなり、その結果、配線基板の絶縁基体と外部電気回路基板との間に発生する熱応力によって接続パッドと低融点ロウ材との接合界面付近の低融点ロウ材に破断が発生し、半導体素子と外部電気回路との電気的接続の信頼性を長期間にわたり維持することができないという欠点を有する。
【０００７】
特に、近時、配線基板の小型化が著しく、また、半導体素子等の電極数の増加に対応して接続パッドの数も多くなり、絶縁基体の下面に高密度で形成されるようになりつつあるため、補助パッドの面積をあまり大きくすることできず、配線基板と外部電気回路基板との接続信頼性の向上は、さらに難しくなってきている。
【０００８】
【課題を解決するための手段】
本発明の配線基板は、電気絶縁材料から成り、表面に半導体素子搭載部を有する四角形状の絶縁基体と、該絶縁基体の下面に外周から中央に向けて形成された多数の接続パッドと、前記絶縁基体の前記搭載部から側面を介し前記接続パッドにかけて導出される複数個の配線導体とから成る配線基板であって、前記絶縁基体下面のコーナーに外周から中央に向けて、中央側の外辺が円弧状の波形をなす四角形状の補助パッドを形成したことを特徴とするものである。
【０００９】
本発明の配線基板によれば、絶縁基体下面のコーナーに外周から中央に向けて、中央側の外辺が円弧状の波形をなす四角形状の補助パッドを形成したことから、補助パッドを外部電気回路基板に設けたダミーのパッド等に低融点ロウ材を介し接合することによって接続パッドと低融点ロウ材との間に熱応力が作用するのを有効に防止し、接続パッドと低融点ロウ材との接合を強固として半導体素子と外部電気回路との電気的接続の信頼性を向上させることができる。
【００１０】
また、補助パッドはその外縁部が円弧状の波形となっていることから、四角形状の補助パッドを外部電気回路基板に設けたダミーのパッド等に低融点ロウ材を介し接合した後、補助パッドと低融点ロウ材との接合界面に配線基板の絶縁基体と外部電気回路基板との間に発生する熱応力が繰り返し、特に接合界面の外縁部に集中して作用したとしても、その熱応力は円弧状の波形の接合界面外縁部に沿って分散されて小さなものとなり、その結果、補助パッドと低融点ロウ材との接合界面に破断を生じることは有効に防止され、補助パッドと低融点ロウ材との接合を強固として同時に接続パッドと低融点ロウ材との間に熱応力が作用するのを長期間にわたり有効に防止することが可能となって、半導体素子と外部電気回路との電気的接続の信頼性をより一層、長期間にわたり維持することができる。
【００１１】
【発明の実施の形態】
次に本発明を添付の図面を基にして詳細に説明する。
図１は、本発明の配線基板を使用した半導体素子収納用パッケージの一実施例を示す断面図、図２はその底面図、図３は要部拡大底面図であり、１は絶縁基体、２は配線導体である。この絶縁基体１と配線導体２とで半導体素子３を搭載する配線基板４が構成される。
【００１２】
前記絶縁基体１は、例えば酸化アルミニウム質焼結体、ガラスセラミック焼結体、窒化アルミニウム質焼結体、ムライト質焼結体、炭化珪素質焼結体等の電気絶縁材料から成り、その上面に半導体素子３が搭載収容される凹部１ａを有し、該凹部１ａ底面には半導体素子３がガラスや樹脂、ロウ材等の接着材を介して接着固定される。
【００１３】
前記絶縁基体１は、例えば酸化アルミニウム質焼結体から成る場合、酸化アルミニウム、酸化珪素、酸化カルシウム、酸化マグネシウム等の原料粉末に適当な有機バインダー、溶剤を添加混合して泥漿状のセラミックスラリーとなすとともに該セラミックスラリーを従来周知のドクターブレード法やカレンダーロール法等のシート成型技術を採用してシート状のセラミックグリーンシート（セラミック生シート）を得、しかる後、前記セラミックグリーンシートを切断加工や打ち抜き加工により適当な形状とするとともにこれを複数枚積層し、最後に前記積層されたセラミックグリーンシートを還元雰囲気中、約１６００℃の温度で焼成することによって製作される。
【００１４】
また前記絶縁基体１は、その凹部１ａ周辺から側面を介し下面にかけて多数の配線導体２が被着形成されており、該配線導体２の凹部１ａ周辺部位には半導体素子３の各電極がボンディングワイヤ５を介して電気的に接続され、また絶縁基体１下面に導出された部位には配線導体２と電気的に接続する複数の平面四角形状をなす接続パッド６が形成されている。
【００１５】
前記配線導体２および接続パッド６は、半導体素子３の電極を外部電気回路に接続する作用をなし、例えば、タングステン、モリブデン、マンガン等の高融点金属からなり、タングステン等の高融点金属粉末に有機溶剤、溶媒を添加混合して得た金属ペーストを絶縁基体１となるセラミックグリーンシートに予め従来周知のスクリーン印刷法により所定パターンに印刷塗布しておくことによって、絶縁基体１の凹部１ａ周辺から下面にかけて被着形成される。
【００１６】
また前記接続パッド６は、配線基板４を外部電気回路基板に実装する外部端子として作用し、低融点ロウ材７を介して外部電気回路基板８の回路配線８ａに接合され、これにより半導体素子３の電極が外部電気回路基板８の回路配線８ａと電気的に接続される。
【００１７】
更に前記絶縁基体１は、図２及び図３に示すように、下面の各コーナーに外周から中央に向けて、中央側の外辺が円弧状の波形をなす四角形状の補助パッド９が形成されており、該補助パッド９は外部電気回路基板８に設けたダミーのパッド等に低融点ロウ材７を介して接合され、絶縁基体１と外部電気回路基板８との間に生じる熱応力が接続パッド６と低融点ロウ材７との接合界面に作用するのを有効に防止する。
【００１８】
本発明においては、図３に示すように、絶縁基体１の中央側における補助パッド９の外辺を円弧状の波形としておくことが重要である。
【００１９】
前記補助パッド９の外辺を円弧状の波形としておくと、補助パッド９を外部電気回路基板８に設けたダミーのパッド等に低融点ロウ材７を介し接合した後、補助パッド９と低融点ロウ材７との接合界面に配線基板４の絶縁基体１と外部電気回路基板８との間に発生する熱応力が繰り返し、特に接合界面の外縁部に集中して作用したとしても、その熱応力は円弧状の波形の接合界面外縁部に沿って分散されて小さなものとなり、その結果、補助パッド９と低融点ロウ材７との接合界面に破断を生じることは有効に防止され、補助パッド９と低融点ロウ材７との接合を強固として同時に接続パッド６と低融点ロウ材７との間に熱応力が作用するのを長期間にわたり有効に防止することが可能となって、半導体素子３と外部電気回路との電気的接続の信頼性をより一層、長期間にわたり維持することができる。
【００２０】
なお、前記外辺が円弧状の波形をなす補助パッド９は、隣接する接続パッド６との電気絶縁性を確保するために、波高部の位置は波形の中心線Ａ−Ａと隣接する接続パッド６との間隔の１／２以下の位置となるようにしておくことが好ましく、また補助パッド９と低融点ロウ材７との接合強度を確保するため、波底部の位置は補助パッドの幅の１／３以下の位置としておくことが好ましい。
【００２１】
また、前記補助パッド９はその外辺の波形の部分が図３に示すような円弧状である。
【００２２】
更に前記補助パッド９は、前述の配線導体２や接続パッド６と同一材料、同一方法によって絶縁基体１の下面コーナーに形成され、具体的には例えば、タングステン、モリブデン、マンガン等の高融点金属からなり、タングステン等の高融点金属粉末に有機溶剤、溶媒を添加混合して得た金属ペーストを複数回に分けて絶縁基体１となるセラミックグリーンシートに予め従来周知のスクリーン印刷法により所定パターンに印刷塗布しておくことによって、絶縁基体１の各コーナーに被着形成される。
【００２３】
かくして本発明の配線基板によれば、絶縁基体１の凹部１ａ底面に半導体素子３をガラスや樹脂、ロウ材等の接着材を介して接着固定するとともにこの半導体素子３の各電極を配線導体２にボンディングワイヤ５を介して電気的に接続し、しかる後、絶縁基体１の上面に金属やセラミックスから成る蓋体１０をガラスや樹脂、ロウ材等の封止材を介して接合させ、絶縁基体１と蓋体１０とから成る容器内部に半導体素子３を気密に封止することによって製品としての半導体装置が完成する。
【００２４】
なお、本発明の配線基板は上述の実施の形態に限定されるものではなく、本発明の要旨を逸脱しない範囲であれば種々の変更は可能であり、例えば、前記配線導体２、接続パッド６および補助パッド９の露出する領域にニッケルまたは銅を１μｍ〜１０μｍ、金を０．０５μｍ〜５μｍの厚さで順次、被着させておくと、配線導体２、接続パッド６および補助パッド９の酸化腐食を効果的に防ぐことができるとともに、接続パッド６および補助パッド９に対し低融点ロウ材７を、配線導体２に対しボンディングワイヤ５を強固に接合、接続させることができる。
【００２５】
【発明の効果】
本発明の配線基板によれば、絶縁基体下面のコーナーに外周から中央に向けて、中央側の外辺が円弧状の波形をなす四角形状の補助パッドを形成したことから、補助パッドを外部電気回路基板に設けたダミーのパッド等に低融点ロウ材を介し接合することによって接続パッドと低融点ロウ材との間に熱応力が作用するのを有効に防止し、接続パッドと低融点ロウ材との接合を強固として半導体素子と外部電気回路との電気的接続の信頼性を向上させることができる。
【００２６】
また、補助パッドはその外縁部が円弧状の波形となっていることから、四角形状の補助パッドを外部電気回路基板に設けたダミーのパッド等に低融点ロウ材を介し接合した後、補助パッドと低融点ロウ材との接合界面に配線基板の絶縁基体と外部電気回路基板との間に発生する熱応力が繰り返し、特に接合界面の外縁部に集中して作用したとしても、その熱応力は円弧状の波形の接合界面外縁部に沿って分散されて小さなものとなり、その結果、補助パッドと低融点ロウ材との接合界面に破断を生じることは有効に防止され、補助パッドと低融点ロウ材との接合を強固として同時に接続パッドと低融点ロウ材との間に熱応力が作用するのを長期間にわたり有効に防止することが可能となって、半導体素子と外部電気回路との電気的接続の信頼性をより一層、長期間にわたり維持することができる。
【図面の簡単な説明】
【図１】本発明の配線基板の一実施例を示す断面図である。
【図２】図１に示す配線基板の底面図である。
【図３】図１に示す配線基板の要部拡大底面図である。
【符号の説明】
１・・・・絶縁基体
１ａ・・・凹部
２・・・・配線導体
３・・・・半導体素子
４・・・・配線基板
５・・・・ボンディングワイヤ
６・・・・接続パッド
７・・・・低融点ロウ材
８・・・・外部電気回路基板
８ａ・・・回路配線
９・・・・補助パッド
１０・・・蓋体[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wiring board used for a package for housing a semiconductor element, and more particularly to a wiring board capable of stably and electrically connecting each electrode of a mounted semiconductor element to a predetermined external electric circuit for a long period of time. It is.
[0002]
[Prior art]
Conventionally, wiring boards on which semiconductor elements are mounted are made of electrically insulating materials such as an aluminum oxide sintered body, a glass ceramic sintered body, an aluminum nitride sintered body, a mullite sintered body, and a silicon carbide sintered body. And a plurality of wirings made of a metal powder such as tungsten or molybdenum derived from an insulating base having a mounting portion on which the semiconductor element is mounted and a semiconductor element mounting portion of the insulating base or its periphery to the lower surface. It is composed of a conductor and a plurality of planar quadrangular connection pads formed on the lower surface of the insulating base and electrically connected to the wiring conductor. In addition, each electrode of the semiconductor element and the wiring conductor are electrically connected to each other through an electrical connection means such as a bonding wire. Connect, thereafter, the semiconductor device by causing hermetically sealed with a lid and a sealing resin the semiconductor device as required.
[0003]
Such a semiconductor device is placed on an external electric circuit board such that the circuit wiring of the external electric circuit board and the connection pads on the lower surface of the insulating base are opposed to each other with a low melting point solder such as tin-lead solder interposed therebetween. After that, the low melting point brazing material is heated and melted at a temperature of about 200 ° C. to 300 ° C., and the circuit wiring of the external electric circuit board and the connection pads on the lower surface of the insulating base are joined to each other to be mounted on the external electric circuit board. At the same time, each electrode of the semiconductor element mounted on the wiring board is electrically connected to the external electric circuit board through the wiring conductor and the low melting point brazing material.
[0004]
[Problems to be solved by the invention]
However, the wiring substrate on which the conventional semiconductor element is mounted has an insulating base made of a ceramic material such as an aluminum oxide sintered body or a glass ceramic sintered body, and has a thermal expansion coefficient of about 3 × 10 −6. to /℃~7.5×10 -6 / in the range of ° C., external electric circuit board is generally formed of a resin material such as glass epoxy resin, the thermal expansion coefficient of 30 × 10 -6 / ℃ ~ 50 × 10 −6 / ° C. Since both are greatly different from each other, the connection pad of the wiring board and the circuit wiring of the external electric circuit board are joined via a low melting point brazing material, and the semiconductor is formed on the external electric circuit board. After mounting the device, if the heat generated during the operation of the semiconductor element repeatedly acts on the insulating base of the wiring board and the external electric circuit board, a large thermal stress is repeatedly generated between the insulating base of the wiring board and the external electric circuit board. And This acts on the bonding interface between the connection pad of the wiring board and the low melting point brazing material, and the low melting point brazing material breaks. As a result, the electrical connection between the semiconductor element and the external electric circuit can be achieved in a short period of time. There was a drawback that it was torn.
[0005]
Therefore, in order to eliminate the above drawbacks, a rectangular auxiliary pad is provided at the corner portion of the insulating base by the same material and the same method as the connection pad, and this auxiliary pad is provided as a dummy pad provided on the external electric circuit board. The connection between the connection pad and the low-melting-point brazing material is prevented by connecting the low-melting-point brazing material to the semiconductor element, and the connection between the connection pad and the low-melting-point brazing material is strengthened. A means for improving the reliability of the electrical connection with the circuit is conceivable.
[0006]
However, when a rectangular auxiliary pad is provided at the corner of the insulating base of the wiring board, immediately after the wiring board is mounted on the external electric circuit board, the auxiliary pad and a dummy pad provided on the external electric circuit board Although it is possible to remove the thermal stress acting between the connection pad and the low melting point brazing material and effectively prevent the breakage near the bonding interface between the connection pad and the low melting point brazing material. When the thermal stress generated between the insulating substrate of the wiring board and the external electric circuit board is repeatedly applied to the auxiliary pad and the low melting point brazing material, the bonding interface between the auxiliary pad and the low melting point brazing material (especially the outer edge portion) ) To prevent thermal stress from being generated between the connection pad and the low melting point brazing material. As a result, the insulation between the wiring board and the external electric circuit board cannot be effectively prevented. Occurs in The low-melting-point brazing material near the bonding interface between the connection pad and the low-melting-point brazing material is broken by the thermal stress, and the reliability of the electrical connection between the semiconductor element and the external electric circuit cannot be maintained for a long time. Has the disadvantages.
[0007]
In particular, recently, the size of the wiring board has been remarkably reduced, and the number of connection pads has increased in response to the increase in the number of electrodes of semiconductor elements and the like, and is being formed at a high density on the lower surface of the insulating substrate. For this reason, the area of the auxiliary pad cannot be increased so much, and it has become more difficult to improve the connection reliability between the wiring board and the external electric circuit board.
[0008]
[Means for Solving the Problems]
The wiring board of the present invention comprises a rectangular insulating base made of an electrically insulating material and having a semiconductor element mounting portion on the surface, a number of connection pads formed on the lower surface of the insulating base from the outer periphery toward the center, A wiring board comprising a plurality of wiring conductors led out from the mounting portion of the insulating base through the side surface to the connection pad , the outer periphery on the center side from the outer periphery toward the center at the corner of the lower surface of the insulating base Is formed with a quadrangular auxiliary pad having an arcuate waveform.
[0009]
According to the wiring board of the present invention, the auxiliary pad is connected to the external electric field by forming the rectangular auxiliary pad in the corner on the lower surface of the insulating base from the outer periphery toward the center, and the outer edge on the center side has an arcuate waveform. By joining a dummy pad or the like provided on a circuit board via a low melting point brazing material, it is possible to effectively prevent thermal stress from acting between the connection pad and the low melting point brazing material. And the reliability of the electrical connection between the semiconductor element and the external electric circuit can be improved.
[0010]
Further, since the auxiliary pad has an arcuate outer peripheral portion, the auxiliary pad having a rectangular shape is joined to a dummy pad or the like provided on the external electric circuit board through a low melting point brazing material, and then the auxiliary pad. a thermal stress generated between the insulating substrate and the external electric circuit board wiring board at the junction interface between the low-melting-point brazing material is repeated, even act in particular concentrated on the outer edge of the joint interface, the thermal stress small things and will be distributed along the joint interface outer edge of the arc-shaped waveform, as a result, the auxiliary pad and to cause rupture at the bonding interface between the low-melting brazing material is effectively prevented, the auxiliary pad and a low melting wax it is possible to effectively prevent from acting thermal stress between the time the connection pads and a low melting brazing material as firmly bond the wood over a long period of time, electrical of the semiconductor element and the external electric circuit Connection trust Even more, it can be maintained over a long period of time.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will now be described in detail with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view showing an embodiment of a package for housing a semiconductor element using the wiring board of the present invention, FIG. 2 is a bottom view thereof, FIG. 3 is an enlarged bottom view of an essential part, 1 is an insulating substrate, 2 Is a wiring conductor. The insulating substrate 1 and the wiring conductor 2 constitute a wiring board 4 on which the semiconductor element 3 is mounted.
[0012]
The insulating base 1 is made of an electrically insulating material such as an aluminum oxide sintered body, a glass ceramic sintered body, an aluminum nitride sintered body, a mullite sintered body, a silicon carbide sintered body, and the like on its upper surface. The semiconductor element 3 has a recess 1a in which the semiconductor element 3 is mounted and accommodated, and the semiconductor element 3 is bonded and fixed to the bottom surface of the recess 1a via an adhesive such as glass, resin, or brazing material.
[0013]
When the insulating substrate 1 is made of, for example, an aluminum oxide sintered body, an appropriate organic binder and solvent are added to and mixed with raw material powders such as aluminum oxide, silicon oxide, calcium oxide, and magnesium oxide to form a slurry ceramic slurry. At the same time, the ceramic slurry is made into a sheet-like ceramic green sheet (ceramic green sheet) by employing a conventionally known sheet molding technique such as a doctor blade method or a calender roll method, and then the ceramic green sheet is cut and processed. It is manufactured by forming a suitable shape by punching and laminating a plurality of them, and finally firing the laminated ceramic green sheets at a temperature of about 1600 ° C. in a reducing atmosphere.
[0014]
The insulating base 1 has a large number of wiring conductors 2 deposited from the periphery of the recess 1a to the lower surface via the side surface. Each electrode of the semiconductor element 3 is bonded to a bonding wire around the recess 1a. A plurality of connection pads 6 having a planar rectangular shape that are electrically connected to the wiring conductor 2 and are electrically connected to the wiring conductor 2 are formed at portions that are electrically connected to each other through the insulating substrate 1.
[0015]
The wiring conductor 2 and the connection pad 6 serve to connect the electrode of the semiconductor element 3 to an external electric circuit. For example, the wiring conductor 2 and the connection pad 6 are made of a refractory metal such as tungsten, molybdenum, or manganese. A metal paste obtained by adding and mixing a solvent and a solvent is preliminarily printed in a predetermined pattern on a ceramic green sheet serving as the insulating substrate 1 by a well-known screen printing method. It is formed by deposition.
[0016]
The connection pad 6 acts as an external terminal for mounting the wiring board 4 on the external electric circuit board, and is joined to the circuit wiring 8a of the external electric circuit board 8 via the low melting point brazing material 7, whereby the semiconductor element 3 Are electrically connected to the circuit wiring 8 a of the external electric circuit board 8.
[0017]
Further, as shown in FIGS. 2 and 3, the insulating base 1 is formed with rectangular auxiliary pads 9 whose outer sides on the center side form an arc-shaped waveform from the outer periphery toward the center at each corner of the lower surface. The auxiliary pad 9 is bonded to a dummy pad or the like provided on the external electric circuit board 8 through a low melting point brazing material 7, and thermal stress generated between the insulating base 1 and the external electric circuit board 8 is connected. It effectively prevents acting on the bonding interface between the pad 6 and the low melting point brazing material 7.
[0018]
In the present invention, as shown in FIG. 3, it is important that the outer side of the auxiliary pad 9 on the center side of the insulating base 1 has an arcuate waveform.
[0019]
If the outer side of the auxiliary pad 9 has an arcuate waveform, the auxiliary pad 9 is joined to a dummy pad or the like provided on the external electric circuit board 8 via the low melting point brazing material 7, and then the auxiliary pad 9 and the low melting point are joined. thermal stress generated between the insulating substrate 1 and the external electric circuit board 8 of the wiring board 4 at the bonding interface between the brazing material 7 is repeated, even act in particular concentrated on the outer edge of the joint interface, the thermal stress Are dispersed along the outer peripheral edge of the arc-shaped corrugated joint interface, and as a result, it is effectively prevented that the joint interface between the auxiliary pad 9 and the low melting point brazing material 7 breaks. it is possible to heat stress can effectively be prevented from acting for a long period of time between the time the connection pads 6 and the low-melting brazing material 7 as strong bonding between the low-melting brazing material 7, the semiconductor device 3 Electrical connection with external electrical circuit Further the reliability can be maintained over a long period of time.
[0020]
The connection pads the perimeter auxiliary pad 9 which forms an arcuate waveform, in order to ensure electrical insulation between the connection pad 6 adjacent the position of the crest portion is adjacent to the center line A-A of the waveform Preferably, the position of the wave bottom portion is equal to the width of the auxiliary pad in order to secure the bonding strength between the auxiliary pad 9 and the low melting point brazing material 7. It is preferable to set the position to 1/3 or less.
[0021]
In addition, the auxiliary pad 9 portion of the waveform of the perimeter is arc-shaped as shown in FIG.
[0022]
Further, the auxiliary pad 9, the above-mentioned wiring conductors 2 and the same material as the connection pads 6, by the same method are formed on the lower surface Corner insulating substrate 1, specifically, for example, tungsten, molybdenum, a refractory metal such as manganese A metal paste obtained by adding and mixing an organic solvent and a solvent to a refractory metal powder such as tungsten is divided into a plurality of times and applied to a ceramic green sheet to be an insulating base 1 in a predetermined pattern in advance by a well-known screen printing method. by our ku printed coating is deposited and formed at each corner over the insulating substrate 1.
[0023]
Thus, according to the wiring board of the present invention, the semiconductor element 3 is bonded and fixed to the bottom surface of the recess 1a of the insulating base 1 through an adhesive such as glass, resin, or brazing material, and each electrode of the semiconductor element 3 is connected to the wiring conductor 2. Are electrically connected to each other via a bonding wire 5, and then a lid 10 made of metal or ceramic is joined to the upper surface of the insulating base 1 via a sealing material such as glass, resin, brazing material, etc. A semiconductor device as a product is completed by hermetically sealing the semiconductor element 3 in a container composed of 1 and the lid 10.
[0024]
The wiring board of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. For example, the wiring conductor 2 and the connection pad 6 If the nickel or copper is sequentially deposited in the exposed region of the auxiliary pad 9 in a thickness of 1 μm to 10 μm and gold in a thickness of 0.05 μm to 5 μm, the wiring conductor 2, the connection pad 6 and the auxiliary pad 9 are oxidized. Corrosion can be effectively prevented, and the low melting point brazing material 7 can be firmly bonded to the connection pad 6 and the auxiliary pad 9, and the bonding wire 5 can be firmly bonded and connected to the wiring conductor 2.
[0025]
【The invention's effect】
According to the wiring board of the present invention, the auxiliary pad is connected to the external electric field by forming the rectangular auxiliary pad in the corner on the lower surface of the insulating base from the outer periphery toward the center, and the outer edge on the center side has an arcuate waveform. By joining a dummy pad or the like provided on a circuit board via a low melting point brazing material, it is possible to effectively prevent thermal stress from acting between the connection pad and the low melting point brazing material. And the reliability of the electrical connection between the semiconductor element and the external electric circuit can be improved.
[0026]
Further, since the auxiliary pad has an arcuate outer peripheral portion, the auxiliary pad having a rectangular shape is joined to a dummy pad or the like provided on the external electric circuit board through a low melting point brazing material, and then the auxiliary pad. a thermal stress generated between the insulating substrate and the external electric circuit board wiring board at the junction interface between the low-melting-point brazing material is repeated, even act in particular concentrated on the outer edge of the joint interface, the thermal stress small things and will be distributed along the joint interface outer edge of the arc-shaped waveform, as a result, the auxiliary pad and to cause rupture at the bonding interface between the low-melting brazing material is effectively prevented, the auxiliary pad and a low melting wax it is possible to effectively prevent from acting thermal stress between the time the connection pads and a low melting brazing material as firmly bond the wood over a long period of time, electrical of the semiconductor element and the external electric circuit Connection trust Even more, it can be maintained over a long period of time.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of a wiring board according to the present invention.
2 is a bottom view of the wiring board shown in FIG. 1. FIG.
3 is an enlarged bottom view of the main part of the wiring board shown in FIG. 1. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Insulating base | substrate 1a ... Recess 2 ... Wiring conductor 3 ... Semiconductor element 4 ... Wiring board 5 ... Bonding wire 6 ... Connection pad 7 ... ..Low melting point brazing material 8 ... External electric circuit board 8a ... Circuit wiring 9 ... Auxiliary pad 10 ... Cover body

Claims (1)

電気絶縁材料から成り、表面に半導体素子搭載部を有する四角形状の絶縁基体と、該絶縁基体の下面に外周から中央に向けて形成された多数の接続パッドと、前記絶縁基体の前記搭載部から側面を介し前記接続パッドにかけて導出される複数個の配線導体とから成る配線基板であって、
前記絶縁基体下面のコーナーに外周から中央に向けて、中央側の外辺が円弧状の波形をなす四角形状の補助パッドを形成したことを特徴とする配線基板。A rectangular insulating base made of an electrically insulating material and having a semiconductor element mounting portion on its surface, a large number of connection pads formed on the lower surface of the insulating base from the outer periphery toward the center, and the mounting portion of the insulating base A wiring board comprising a plurality of wiring conductors led out through the side surface to the connection pad,
A wiring board, wherein a rectangular auxiliary pad having an arcuate corrugated outer side is formed at the corner of the lower surface of the insulating base from the outer periphery toward the center .
JP2002147927A 2002-05-22 2002-05-22 Wiring board Expired - Fee Related JP3838940B2 (en)

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WO2006114971A2 (en) 2005-04-18 2006-11-02 Murata Manufacturing Co Electronic component module
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