JP2004179547A - Wiring board - Google Patents

Wiring board Download PDF

Info

Publication number
JP2004179547A
JP2004179547A JP2002346368A JP2002346368A JP2004179547A JP 2004179547 A JP2004179547 A JP 2004179547A JP 2002346368 A JP2002346368 A JP 2002346368A JP 2002346368 A JP2002346368 A JP 2002346368A JP 2004179547 A JP2004179547 A JP 2004179547A
Authority
JP
Japan
Prior art keywords
external
insulating base
convex portion
external electrode
insulating
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
JP2002346368A
Other languages
Japanese (ja)
Other versions
JP3909285B2 (en
Inventor
Yukio Shigeta
幸男 重田
Kazuhiro Matsuo
一博 松尾
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kyocera Corp
Original Assignee
Kyocera Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kyocera Corp filed Critical Kyocera Corp
Priority to JP2002346368A priority Critical patent/JP3909285B2/en
Publication of JP2004179547A publication Critical patent/JP2004179547A/en
Application granted granted Critical
Publication of JP3909285B2 publication Critical patent/JP3909285B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Images

Landscapes

  • Production Of Multi-Layered Print Wiring Board (AREA)
  • Printing Elements For Providing Electric Connections Between Printed Circuits (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that it is difficult to effectively enlarge the area of external electrode to withstand a large thermal stress because external size of the insulating base material and size of the external electrode are very small and a metallized conductive layer is formed only on the internal wall surface of the concave part of the external electrode. <P>SOLUTION: In the wiring board 4, a convex portion is provided at the lower surface of an insulating base material 1, including a plurality of wiring conductors 3, on which a plurality of almost square insulating layers are laminated with smaller interval between two sides facing with each other of the insulating layer than that of the insulating layer just above such insulating layer, and a plurality of external electrodes 2 which are electrically connected to a plurality of wiring conductors 3 are formed, via the side surface, on the lower surface of the external insulating base material 1 from the lower surface of the convex portion at the part of two sides facing each other of such convex portion. For connection by soldering with the external circuit substrate, sufficient area can be secured for the external electrode 2 for which a connection terminal can form a large meniscus. <P>COPYRIGHT: (C)2004,JPO

Description

【0001】
【発明の属する技術分野】
本発明は、絶縁基体の下面から側面にかけて外部電極が配置され、この外部電極が外部回路基板に接続される配線基板に関するものであり、詳細には、外部電極の外部回路基板に対する接続信頼性が良好な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、特にLSI等の半導体素子や圧電振動子・容量素子等の電子部品を収容するための配線基板は、一般にアルミナセラミックス等のセラミックスから成る絶縁基体の上面に半導体素子搭載部を有し、半導体素子搭載部の周辺から側面にかけて、タングステン・モリブデン等の高融点金属粉末から成る複数個の配線導体が設けられた構造である。その配線導体は、絶縁基体の下面から側面にかけて形成された複数個の外部電極と電気的に接続されている。そして、外部電極は錫−鉛半田等の接続端子を介してマザーボード等の外部回路基板と接続され、これにより配線基板は外部回路基板と機械的・電気的に接続される。
【0003】
最近では、半導体素子等の電子部品は高集積化・小型化に伴い電極数が増大しており、これに伴い、配線基板における配線導体や外部電極の高密度配線化が求められている。
【0004】
そのような要求に対して、最近では、配線基板の外部電極として、絶縁基体の下面から側面の厚み方向の途中まで凹部を形成するとともに、絶縁基体の下面から凹部の内側壁面にかけてメタライズ導体層を形成した構造の外部電極を有する配線基板が多用されるようになっている。
【0005】
【特許文献1】
特開平8−37251号公報
【0006】
【発明が解決しようとする課題】
しかしながら、このように絶縁基体の下面から側面の厚み方向の途中まで凹部を形成するとともに、その内側壁面にメタライズ導体層を形成した外部電極を有するものとしても、特に、絶縁基体の材料としてホウ珪酸系ガラスセラミックスやムライトセラミックスのように熱膨張係数が約5×10−6/℃以下と非常に小さく、外部回路基板との間で非常に大きな熱応力が生じるものを用いた場合や、絶縁基体の外寸が例えば約5mm×5mm以下と非常に小さいものとなり、外部電極の寸法も小さなものとなってきた場合には、凹部の内側壁面にのみメタライズ導体層が形成されていることから、外部電極の面積を、このような大きな熱応力に対応するように、また小さな外部電極の面積に対応させつつ効果的に大きくすることが困難であるという問題点があった。
【0007】
また、このような凹部の内側壁面のメタライズ導体層と接続端子との接合面が、接続端子に生じるせん断歪みの方向に対して主として平行な方向であることから、配線基板の外部回路基板に対する接続信頼性を効果的に向上させることができないという問題点があった。
【0008】
このため、外部電極と外部回路基板との接続強度を十分に確保することができず、配線基板の外部回路基板に対する接続の信頼性が不十分なものとなってしまうという問題点があった。
【0009】
本発明は以上のような従来の技術における問題点を解決すべく案出されたものであり、その目的は、配線基板と外部回路基板との熱膨張差に起因する応力によって発生する、外部電極に接続された接続端子に対するせん断歪みを緩和することができ、外部回路基板との接続の信頼性を極めて優れたものとすることができる配線基板を提供することにある。
【0010】
【課題を解決するための手段】
本発明の配線基板は、複数の略四角形の絶縁層が積層された、内部に複数の配線導体を有する絶縁基体の下面に、前記絶縁層の対向する2辺の間隔を直上の前記絶縁層よりも小さくすることによって凸部を設け、この凸部の前記対向する2辺の部位の前記凸部の下面から側面を介してその外側の前記絶縁基体の下面にかけて、前記複数の配線導体とそれぞれ電気的に接続された複数の外部電極を形成したことを特徴とするものである。
【0011】
本発明の配線基板によれば、絶縁層の対向する2辺の間隔を直上の絶縁層よりも小さくすることによって凸部を設け、この凸部の対向する2辺の部位の凸部の下面から側面を介してその外側の絶縁基体の下面にかけて、複数の配線導体とそれぞれ電気的に接続された複数の外部電極を形成したことから、この外部電極について外部回路基板との半田接続を実施する場合に、半田が凸部の下面から側面を介してその外側の絶縁基体の下面にかけて大きなメニスカスを形成するため、外部電極について十分な大きさの面積を確保できるものとなり、配線基板と外部回路基板との熱膨張差に起因する応力によって発生する接続端子に対するせん断歪みを緩和することができる、熱疲労破壊の発生がない実装の長期信頼性に優れた配線基板となる。
【0012】
【発明の実施の形態】
次に、本発明を添付図面に基づき詳細に説明する。
【0013】
図1は、本発明の配線基板の実施の形態の一例を示す下面図である。また、図2は、本発明の配線基板の実施の形態の一例を示す断面図である。これらの図において、1は複数の略四角形の絶縁層を積層して成る絶縁基体、2は外部電極、3は配線導体である。これら絶縁基体1・外部電極2および配線導体3により配線基板4が形成される。
【0014】
絶縁基体1は、上面に半導体素子(図示せず)の搭載部を有し、例えば、酸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・窒化アルミニウム質焼結体・窒化珪素質焼結体・ガラスセラミックス焼結体等の電気絶縁性セラミックスから成る略四角形の絶縁層を複数上下に積層して形成されている。
【0015】
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であれば、酸化アルミニウムの粉末に酸化珪素・酸化マグネシウム・酸化カルシウム等の焼結助剤を添加し、さらに適当な有機バインダ・溶剤等を添加混合して泥漿物を作るとともに、この泥漿物をドクターブレード法やカレンダーロール法を採用することによってグリーンシート(生シート)とし、しかる後、このグリーンシートに適当な打ち抜き加工を施して略四角形状に加工するとともにこれを複数枚積層し、約1600℃の温度で焼成することによって製作される。
【0016】
この絶縁基体1の下面から側面にかけて複数の外部電極2が被着形成されており、また半導体素子が搭載される上面から側面の外部電極2にかけてビアホール導体やスルーホール導体等の貫通導体を含む配線導体3が被着形成されている。
【0017】
本発明の配線基板4においては、この複数の略四角形の絶縁層が積層された、内部に複数の配線導体3を有する絶縁基体1の下面に、絶縁層の対向する2辺の間隔を直上の絶縁層よりも小さくすることによって凸部を設け、この凸部の対向する2辺の部位の、凸部の下面から側面を介してその外側の絶縁基体1の下面にかけて、複数の配線導体3とそれぞれ電気的に接続された複数の外部電極2を形成することが重要である。
【0018】
このように、絶縁層の対向する2辺の間隔を直上の絶縁層よりも小さくすることによって凸部を設け、この凸部の対向する2辺の部位の凸部の下面から側面を介してその外側の絶縁基体1の下面にかけて、複数の配線導体3とそれぞれ電気的に接続された複数の外部電極2を形成することにより、この外部電極2について外部回路基板との半田接続を実施する場合に、接続端子(図示せず)としての半田が、凸部の対向する2辺の部位の凸部の下面から側面を介してその外側の絶縁基体1の下面にかけて形成された外部電極2に対して大きなメニスカスを形成することができるように、外部電極2について十分な大きさの面積を確保できるものとなるので、配線基板4と外部回路基板との熱膨張差に起因する応力によって発生する接続端子に対するせん断歪みを十分に緩和することができる、熱疲労破壊の発生がない実装の長期信頼性に優れた配線基板4となる。
【0019】
これらの外部電極2および配線導体3は、半導体素子の電極を外部の電気回路と導通する導電路として機能する。
【0020】
絶縁基体1の搭載部に搭載された半導体素子は、その電極が半田やボンディングワイヤ等を介して配線導体3のうち搭載部に露出している部位に接続され、外部電極2を後述する接続端子を介して外部回路基板に接続することにより、半導体素子と外部の電気回路とが配線導体3・外部電極2および接続端子を介して電気的に接続される。
【0021】
外部電極2および配線導体3は、タングステン・モリブデン・マンガン等の高融点金属や、銅・銀・アルミニウム等の低抵抗金属等のメタライズ導体層によって形成される。これら外部電極2および配線導体3と絶縁基体1との同時焼成を図る場合であれば、用いるセラミックス材料に応じて焼成温度がマッチングする金属材料が適宜選択され、選択された金属材料の粉末に適当な有機バインダ・可塑剤・溶剤を添加混合して得た金属ペーストを、絶縁基体1となるグリーンシートの焼成前にグリーンシートに貫通孔を形成してこの貫通孔内に金属ペーストを充填したり、グリーンシートにスクリーン印刷法等により所定パターンに印刷塗布したりして、絶縁基体1と同時焼成することにより、絶縁基体1の所定位置に被着形成される。
【0022】
なお、このような外部電極2のうち、凸部の側面に被着されるものは、あらかじめ凸部の側面に上下方向に横断面が略半円状の溝状部を形成しておくとともに、この溝状部の側壁面に形成することが好ましい。このように凸部の側面に溝状部を形成し、その側壁面に外部電極2を形成すると、この溝状部内に半田が入り込んで大きな接合面で接合されるようになるため、半田による接合をより一層強固なものとすることができる。
【0023】
また、このような外部電極2としては、例えば、絶縁基体1の下面の凸部の側面に断面形状の直径が0.3mm乃至0.7mmの半円状の溝状部を設け、この溝状部の内壁面の全面に外部電極2を被着させるとともに、凸部の下面および凸部側面を介しその外側の絶縁基体の下面に、四角形状、例えば、辺の長さが0.3mm乃至1mm程度の長方形や正方形状に外部電極2を被着させることにより形成されたものが、配線基板4の小型化および外部回路基板に対する十分な接続強度を確保する上で、好適に用いることができる。
【0024】
また、外部電極2は、通常、凸部の下面から側面およびその外側の絶縁基体1の下面にかけて、一定の幅および隣接間隔で形成される。例えば、凸部の1辺の長さを10等分し、この各等分の中に、凸部の1辺の長さの20分の1程度の幅の外部電極2が、隣接間隔がほぼ同じになるように形成される。
【0025】
さらに、上記のような大きさで外部電極2を形成する場合は、例えば、隣接する外部電極2同士の間隔が0.5mm以上となるようにしておくと、絶縁基体1の下面の凸部の外縁部で機械的強度の低下を生じることがなく、同時に、絶縁基体1の外形寸法を大きくすることなく外部電極2を多数個、高密度で形成することが可能となるとともに、配線基板4の外部回路基板に対する良好な接続信頼性を確保することができる。
【0026】
この場合、絶縁基体1を形成する各絶縁層となるグリーンシートのうち、絶縁基体1の下面を形成するものは、その直上の絶縁層よりも対向する2辺の間隔を小さくしておく必要がある。これにより、下面を形成するグリーンシートとその直上のグリーンシートとの間で対向する2辺の部分が段状となり、下面を形成するグリーンシートが絶縁基体1の下面の凸部となる。なお、この場合の凸部は1層のグリーンシートで形成するものに限らず、複数の、ほぼ同じ寸法のグリーンシートを積層することにより形成してもよい。
【0027】
また、絶縁基体1の下面の凸部は、その直上に位置する絶縁層に対して、対向する2辺に直交する側の1辺の長さが約80〜95%の範囲となって小さくなるように(0.1mm〜1.5mmの長さ分短くなるように)しておくことが好ましい。
【0028】
この対向する2辺に直交する側の1辺の長さ(対向する2辺間の距離)がその直上に位置する絶縁層の同じ側の1辺の長さ(同じ側で対向する2辺間の距離)の95%未満では、凸部の側面を介してその外側の絶縁基体1の下面に設ける外部電極2の面積を広く設けることが困難なため、外部電極2の接続信頼性を効果的に向上させることが難しい傾向がある。
【0029】
また、この絶縁基体1の下面の凸部の高さは、絶縁基体1の厚みに対して3分の1乃至3分の2の長さとなるようにしておくことが好ましい。
【0030】
この凸部の高さが絶縁基体1の厚みに対して3分の1未満では、接続端子と凸部の側壁面に形成される外部電極2との接合面を効果的に大きくして接合強度を大きくすることが困難となる傾向があり、他方、3分の2を超えると、凸部の側壁面に形成される外部電極2の容積が大きくなりすぎて、接続端子を形成する半田の量が不足することとなって良好なメニスカスを形成することが困難となり、十分な接続強度が得られなくなる傾向がある。
【0031】
また、外部電極2と外部回路基板との接続には、Sn−PbやSn−Pb−Bi等の半田が使用され、この半田を接続端子とすることにより配線基板4の外部電極2が外部回路基板の配線層と接続される。
【0032】
この場合、外部電極2および配線導体3は、その露出表面にニッケル・金等の耐食性が良好で、半田ボール等から成る接続端子の接続性やボンディングワイヤのボンディング性に優れた金属から成るめっき層を被着させておくと、外部電極2や配線導体3の酸化腐食を効果的に防止することができるとともに、外部電極2に対する接続端子の接続の信頼性や、配線導体3に対する半田やボンディングワイヤの接続強度をより一層良好とすることができ、配線基板4の信頼性をより一層優れたものとすることができる。
【0033】
したがって、外部電極2および配線導体3は、その露出表面にニッケル・金等のめっき層を、例えば、厚さ2μm〜10μmのニッケル層/厚さ0.05〜2μmの金層の順に被着させておくことが好ましい。
【0034】
なお、この外部回路基板は、通常、配線基板4の絶縁基体1よりも熱膨張係数が大きいものであって、例えば、エポキシ樹脂等の有機樹脂や、有機樹脂とガラス繊維等の無機質フィラーとの複合材料から成り、配線層は、銅・銀・アルミニウム等の金属材料の箔やめっき層等によって形成される。
【0035】
なお、本発明は上述の実施の形態の例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る。
【0036】
例えば、上述の実施の形態の例では、絶縁基体1の下面の凸部の側面を1つの垂直な面としたが、これを絶縁基体1の下面に向かって階段状とし、半田と外部電極との接続の面積を外部電極2の形状が絶縁基体1の下面の凸部の形状に沿って階段状になることで、より増加させるようにしてもよい。
【0037】
【発明の効果】
本発明の配線基板によれば、絶縁層の対向する2辺の間隔を直上の絶縁層よりも小さくすることによって凸部を設け、この凸部の対向する2辺の部位の凸部の下面から側面を介してその外側の絶縁基体の下面にかけて、複数の配線導体とそれぞれ電気的に接続された複数の外部電極を形成したことから、この外部電極について外部回路基板との半田接続を実施する場合に、半田から成る接続端子が凸部の対向する2辺の部位の凸部の下面から側面を介してその外側の絶縁基体の下面にかけてメニスカスを形成するため、外部電極について十分な大きさの面積を確保できるものとなり、配線基板と外部回路基板との熱膨張差に起因する応力によって発生する接続端子に対するせん断歪みを緩和することができる、熱疲労破壊の発生がない実装の長期信頼性に優れた配線基板となる。
【図面の簡単な説明】
【図1】本発明の配線基板の実施の形態の一例を示す下面図である。
【図2】本発明の配線基板の実施の形態の一例を示す断面図である。
【符号の説明】
1・・・・・絶縁基体
2・・・・・外部電極
3・・・・・配線導体
4・・・・・配線基板
[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a wiring board in which external electrodes are arranged from a lower surface to a side surface of an insulating base, and the external electrodes are connected to an external circuit board. More specifically, the present invention relates to a connection reliability of the external electrodes to the external circuit board. It relates to a good wiring board.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a wiring board for accommodating a semiconductor element, particularly a semiconductor element such as an LSI or an electronic component such as a piezoelectric vibrator or a capacitor has a semiconductor element mounting portion on an upper surface of an insulating base generally made of ceramics such as alumina ceramics. Further, a plurality of wiring conductors made of a high melting point metal powder such as tungsten and molybdenum are provided from the periphery to the side surface of the semiconductor element mounting portion. The wiring conductor is electrically connected to a plurality of external electrodes formed from the lower surface to the side surface of the insulating base. The external electrode is connected to an external circuit board such as a motherboard via a connection terminal such as tin-lead solder, whereby the wiring board is mechanically and electrically connected to the external circuit board.
[0003]
In recent years, the number of electrodes of electronic components such as semiconductor elements has been increasing along with high integration and miniaturization, and accordingly, high density wiring of wiring conductors and external electrodes on a wiring board is required.
[0004]
In response to such demands, recently, as an external electrode of a wiring board, a concave portion is formed from the lower surface of the insulating base to the middle in the thickness direction of the side surface, and a metallized conductor layer is formed from the lower surface of the insulating base to the inner wall surface of the concave portion. Wiring boards having external electrodes of the formed structure are often used.
[0005]
[Patent Document 1]
JP-A-8-37251
[Problems to be solved by the invention]
However, even when the concave portion is formed from the lower surface of the insulating base to the middle of the side surface in the thickness direction and the external electrode having the metallized conductor layer formed on the inner wall surface thereof, particularly, the borosilicate When a material such as glass-based ceramics or mullite ceramics having a very small thermal expansion coefficient of about 5 × 10 −6 / ° C. or less and causing a very large thermal stress with an external circuit board is used, Is extremely small, for example, about 5 mm × 5 mm or less, and when the dimensions of the external electrodes are becoming small, the metallized conductor layer is formed only on the inner wall surface of the concave portion. It is difficult to effectively increase the electrode area to accommodate such a large thermal stress and to accommodate the small external electrode area. There is a problem in that.
[0007]
In addition, since the joint surface between the metallized conductor layer on the inner wall surface of the recess and the connection terminal is mainly parallel to the direction of the shear strain generated in the connection terminal, the connection of the wiring board to the external circuit board is performed. There was a problem that the reliability could not be improved effectively.
[0008]
Therefore, the connection strength between the external electrode and the external circuit board cannot be sufficiently secured, and the reliability of the connection of the wiring board to the external circuit board becomes insufficient.
[0009]
The present invention has been devised to solve the problems in the conventional technology as described above, and its object is to provide an external electrode which is generated by a stress caused by a difference in thermal expansion between a wiring board and an external circuit board. It is an object of the present invention to provide a wiring board which can alleviate the shear strain on the connection terminal connected to the external circuit board and can make the reliability of connection with an external circuit board extremely excellent.
[0010]
[Means for Solving the Problems]
The wiring board according to the present invention is arranged such that, on a lower surface of an insulating base having a plurality of substantially rectangular insulating layers stacked thereon and having a plurality of wiring conductors therein, a distance between two opposing sides of the insulating layer is greater than that of the insulating layer immediately above the insulating layer. The protrusions are also provided by reducing the size of the protrusions, and the plurality of wiring conductors are electrically connected to the lower surface of the insulating base from the lower surface of the protrusions on the two opposite sides of the protrusions to the lower surface of the insulating base outside the side surfaces. A plurality of external electrodes which are electrically connected are formed.
[0011]
According to the wiring board of the present invention, the interval between the two opposing sides of the insulating layer is made smaller than that of the insulating layer immediately above, so that the convex portion is provided. When a plurality of external electrodes electrically connected to the plurality of wiring conductors are formed over the lower surface of the insulating base on the outer side through the side surface, when the external electrodes are to be soldered to an external circuit board. In addition, since the solder forms a large meniscus from the lower surface of the convex portion to the lower surface of the insulating substrate outside through the side surface, a sufficient area can be secured for the external electrodes, and the wiring board and the external circuit board are This can reduce the shear strain on the connection terminals caused by the stress caused by the difference in thermal expansion of the wiring board, and is excellent in long-term reliability of mounting without occurrence of thermal fatigue failure.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the present invention will be described in detail with reference to the accompanying drawings.
[0013]
FIG. 1 is a bottom view showing an example of an embodiment of a wiring board of the present invention. FIG. 2 is a sectional view showing an example of an embodiment of a wiring board of the present invention. In these figures, 1 is an insulating base formed by laminating a plurality of substantially square insulating layers, 2 is an external electrode, and 3 is a wiring conductor. A wiring board 4 is formed by the insulating base 1, the external electrodes 2 and the wiring conductors 3.
[0014]
The insulating substrate 1 has a mounting portion for a semiconductor element (not shown) on the upper surface, and includes, for example, an aluminum oxide sintered body, a mullite sintered body, a silicon carbide sintered body, an aluminum nitride sintered body, It is formed by vertically laminating a plurality of substantially square insulating layers made of electrically insulating ceramics such as a silicon nitride sintered body and a glass ceramic sintered body.
[0015]
When the insulating substrate 1 is made of, for example, an aluminum oxide sintered body, a sintering aid such as silicon oxide, magnesium oxide, or calcium oxide is added to aluminum oxide powder, and an appropriate organic binder, solvent, or the like is further added. To form a green sheet (green sheet) by employing a doctor blade method or a calender roll method, and then subjecting the green sheet to a suitable punching process to obtain a green sheet. It is manufactured by processing into a square shape, laminating a plurality of them, and firing at a temperature of about 1600 ° C.
[0016]
A plurality of external electrodes 2 are formed from the lower surface to the side surface of the insulating base 1, and wiring including a through conductor such as a via-hole conductor or a through-hole conductor extends from the upper surface on which the semiconductor element is mounted to the external electrode 2 on the side surface. A conductor 3 is formed.
[0017]
In the wiring board 4 of the present invention, the interval between two opposing sides of the insulating layer is directly above the lower surface of the insulating base 1 having the plurality of substantially rectangular insulating layers stacked and having the plurality of wiring conductors 3 therein. Protrusions are provided by making the protrusions smaller than the insulating layer, and a plurality of wiring conductors 3 are formed on two opposing sides of the protrusions from the lower surface of the protrusion to the lower surface of the insulating base 1 outside through the side surface. It is important to form a plurality of external electrodes 2 electrically connected to each other.
[0018]
In this way, the convex portion is provided by making the interval between the two opposing sides of the insulating layer smaller than that of the insulating layer immediately above, and the lower surface of the convex portion of the opposing two sides of the convex portion is interposed through the side surface. By forming a plurality of external electrodes 2 electrically connected to the plurality of wiring conductors 3 over the lower surface of the outer insulating base 1, the external electrodes 2 can be soldered to an external circuit board. The solder as a connection terminal (not shown) is applied to the external electrode 2 formed from the lower surface of the convex portion on the two opposite sides of the convex portion to the lower surface of the insulating base 1 outside through the side surface. Since a sufficiently large area can be secured for the external electrode 2 so that a large meniscus can be formed, the connection terminal generated by the stress caused by the difference in thermal expansion between the wiring board 4 and the external circuit board is obtained. To The shear strain that it is possible to reduce sufficiently, a wiring board 4 having excellent long-term reliability of the occurrence of thermal fatigue fracture is not implemented.
[0019]
These external electrodes 2 and wiring conductors 3 function as conductive paths that conduct the electrodes of the semiconductor element to an external electric circuit.
[0020]
The semiconductor element mounted on the mounting portion of the insulating base 1 is connected to a portion of the wiring conductor 3 exposed through the mounting portion of the wiring conductor 3 via solder, bonding wire, or the like, and connects the external electrode 2 to a connection terminal described later. The semiconductor element and the external electric circuit are electrically connected to each other through the wiring conductor 3, the external electrode 2, and the connection terminal.
[0021]
The external electrode 2 and the wiring conductor 3 are formed of a metallized conductor layer such as a high melting point metal such as tungsten, molybdenum, and manganese, and a low resistance metal such as copper, silver, and aluminum. If simultaneous firing of the external electrodes 2 and the wiring conductors 3 and the insulating base 1 is to be performed, a metal material having a matching firing temperature is appropriately selected according to the ceramic material to be used. A metal paste obtained by adding and mixing an organic binder, a plasticizer, and a solvent is formed into a through-hole in the green sheet before firing the green sheet as the insulating substrate 1 and the metal paste is filled in the through-hole. The green sheet is printed and applied in a predetermined pattern by a screen printing method or the like, and is baked at the same time as the insulating substrate 1, so that the green sheet is adhered to a predetermined position of the insulating substrate 1.
[0022]
Among such external electrodes 2, those that are to be attached to the side surfaces of the projections are formed in advance with groove-shaped portions having a substantially semicircular cross section in the vertical direction on the side surfaces of the projections. It is preferable to form the groove on the side wall surface. When the groove-like portion is formed on the side surface of the convex portion and the external electrode 2 is formed on the side wall surface, the solder enters into the groove-like portion and is joined at a large joint surface. Can be further strengthened.
[0023]
As such an external electrode 2, for example, a semicircular groove having a cross-sectional diameter of 0.3 mm to 0.7 mm is provided on the side surface of the convex portion on the lower surface of the insulating base 1. The external electrode 2 is adhered to the entire inner wall surface of the portion, and a rectangular shape, for example, 0.3 mm to 1 mm in side length is formed on the lower surface of the insulating base through the lower surface of the convex portion and the side surface of the convex portion. What is formed by attaching the external electrode 2 in a rectangular or square shape of a degree can be suitably used in miniaturizing the wiring board 4 and securing sufficient connection strength to the external circuit board.
[0024]
Further, the external electrodes 2 are usually formed with a constant width and an adjacent interval from the lower surface of the projection to the side surface and the lower surface of the insulating base 1 outside the side surface. For example, the length of one side of the convex portion is divided into ten equal parts, and in each of the equal parts, the external electrode 2 having a width of about 1/20 of the length of one side of the convex portion is substantially adjacent to each other. It is formed to be the same.
[0025]
Further, in the case where the external electrodes 2 are formed in the above-described size, for example, if the interval between the adjacent external electrodes 2 is set to 0.5 mm or more, the protrusion of the lower surface of the insulating base 1 may be reduced. It is possible to form a large number of external electrodes 2 at high density without increasing the outer dimensions of the insulating base 1 without reducing the mechanical strength at the outer edge, and at the same time, Good connection reliability to the external circuit board can be ensured.
[0026]
In this case, among the green sheets serving as the respective insulating layers forming the insulating base 1, the green sheet forming the lower surface of the insulating base 1 needs to have a smaller interval between two sides facing each other than the insulating layer immediately above the green sheet. is there. As a result, the two sides facing each other between the green sheet forming the lower surface and the green sheet immediately above it become stepped, and the green sheet forming the lower surface becomes a projection on the lower surface of the insulating base 1. In this case, the projections are not limited to those formed of a single layer of green sheets, and may be formed by laminating a plurality of green sheets having substantially the same dimensions.
[0027]
Further, the length of one side orthogonal to the two opposing sides of the convex portion on the lower surface of the insulating base 1 with respect to the insulating layer located immediately above is reduced to a range of about 80 to 95%. (To be shorter by a length of 0.1 mm to 1.5 mm).
[0028]
The length of one side on the side orthogonal to the two opposite sides (the distance between the two opposite sides) is the length of one side on the same side of the insulating layer located immediately above (between the two opposite sides on the same side). Is less than 95%), it is difficult to increase the area of the external electrode 2 provided on the lower surface of the insulating base 1 outside the side surface of the convex portion, so that the connection reliability of the external electrode 2 is effectively improved. Tend to be difficult to improve.
[0029]
Further, it is preferable that the height of the convex portion on the lower surface of the insulating base 1 be one third to two thirds of the thickness of the insulating base 1.
[0030]
When the height of the protrusion is less than one third of the thickness of the insulating base 1, the bonding surface between the connection terminal and the external electrode 2 formed on the side wall surface of the protrusion is effectively increased to increase the bonding strength. However, if it exceeds two-thirds, the volume of the external electrode 2 formed on the side wall surface of the projection becomes too large, and the amount of solder forming the connection terminal becomes large. Is insufficient, it becomes difficult to form a good meniscus, and there is a tendency that sufficient connection strength cannot be obtained.
[0031]
The external electrode 2 is connected to the external circuit board using solder such as Sn-Pb or Sn-Pb-Bi. The external electrode 2 of the wiring board 4 is connected to the external circuit by using the solder as a connection terminal. Connected to the wiring layer of the substrate.
[0032]
In this case, the external electrode 2 and the wiring conductor 3 have a plating layer made of a metal having good corrosion resistance such as nickel and gold on the exposed surfaces, and excellent in the connectivity of connection terminals formed of solder balls and the like and the bonding property of bonding wires. Is attached, the oxidative corrosion of the external electrode 2 and the wiring conductor 3 can be effectively prevented, and the reliability of connection of the connection terminal to the external electrode 2 and the solder or bonding wire to the wiring conductor 3 Can be further improved, and the reliability of the wiring board 4 can be further improved.
[0033]
Therefore, the external electrode 2 and the wiring conductor 3 are formed by depositing a plating layer of nickel, gold, or the like on the exposed surface in the order of, for example, a nickel layer having a thickness of 2 μm to 10 μm / a gold layer having a thickness of 0.05 to 2 μm. It is preferable to keep it.
[0034]
The external circuit board usually has a larger coefficient of thermal expansion than the insulating substrate 1 of the wiring board 4 and, for example, includes an organic resin such as an epoxy resin or a mixture of an organic resin and an inorganic filler such as glass fiber. The wiring layer is made of a composite material, and the wiring layer is formed of a foil or a plating layer of a metal material such as copper, silver, or aluminum.
[0035]
The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
[0036]
For example, in the example of the above-described embodiment, the side surface of the convex portion on the lower surface of the insulating base 1 is a single vertical surface. May be further increased by making the shape of the external electrode 2 stepwise along the shape of the convex portion on the lower surface of the insulating base 1.
[0037]
【The invention's effect】
According to the wiring board of the present invention, the interval between the two opposing sides of the insulating layer is made smaller than that of the insulating layer immediately above, so that the convex portion is provided. When a plurality of external electrodes electrically connected to the plurality of wiring conductors are formed over the lower surface of the insulating base on the outer side through the side surface, when the external electrodes are to be soldered to an external circuit board. In addition, since the connection terminal made of solder forms a meniscus from the lower surface of the convex portion of the two opposite sides of the convex portion to the lower surface of the outer insulating base via the side surface, the area of the external electrode is sufficiently large. And can reduce the shear strain on the connection terminals caused by the stress caused by the difference in thermal expansion between the wiring board and the external circuit board. A wiring board which is excellent in the period reliability.
[Brief description of the drawings]
FIG. 1 is a bottom view showing an example of an embodiment of a wiring board of the present invention.
FIG. 2 is a cross-sectional view illustrating an example of an embodiment of a wiring board according to the present invention.
[Explanation of symbols]
1 ... insulating base 2 ... external electrode 3 ... wiring conductor 4 ... wiring board

Claims (1)

複数の略四角形の絶縁層が積層された、内部に複数の配線導体を有する絶縁基体の下面に、前記絶縁層の対向する2辺の間隔を直上の前記絶縁層よりも小さくすることによって凸部を設け、該凸部の前記対向する2辺の部位の前記凸部の下面から側面を介してその外側の前記絶縁基体の下面にかけて、前記複数の配線導体とそれぞれ電気的に接続された複数の外部電極を形成したことを特徴とする配線基板。A convex portion is formed on the lower surface of an insulating base having a plurality of substantially rectangular insulating layers laminated thereon and having a plurality of wiring conductors therein by making a distance between two opposite sides of the insulating layer smaller than that of the insulating layer immediately above. And a plurality of the plurality of wiring conductors electrically connected to the plurality of wiring conductors, respectively, from a lower surface of the convex portion of the two opposite sides of the convex portion to a lower surface of the insulating base outside the side surface via a side surface. A wiring board having external electrodes formed thereon.
JP2002346368A 2002-11-28 2002-11-28 Wiring board Expired - Fee Related JP3909285B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2002346368A JP3909285B2 (en) 2002-11-28 2002-11-28 Wiring board

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2002346368A JP3909285B2 (en) 2002-11-28 2002-11-28 Wiring board

Publications (2)

Publication Number Publication Date
JP2004179547A true JP2004179547A (en) 2004-06-24
JP3909285B2 JP3909285B2 (en) 2007-04-25

Family

ID=32707298

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2002346368A Expired - Fee Related JP3909285B2 (en) 2002-11-28 2002-11-28 Wiring board

Country Status (1)

Country Link
JP (1) JP3909285B2 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2016006846A (en) * 2014-05-27 2016-01-14 京セラ株式会社 Wiring board and electronic apparatus
JP2018166161A (en) * 2017-03-28 2018-10-25 京セラ株式会社 Wiring base and imaging apparatus

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2016006846A (en) * 2014-05-27 2016-01-14 京セラ株式会社 Wiring board and electronic apparatus
JP2018166161A (en) * 2017-03-28 2018-10-25 京セラ株式会社 Wiring base and imaging apparatus

Also Published As

Publication number Publication date
JP3909285B2 (en) 2007-04-25

Similar Documents

Publication Publication Date Title
JP4111222B2 (en) Surface mount parts
JP2009170706A (en) Multilayer electronic component
JP3909285B2 (en) Wiring board
JP7145739B2 (en) Wiring boards, electronic devices and electronic modules
JP6826185B2 (en) Wiring boards, electronics and electronic modules
JP5743779B2 (en) Multi-circuit board and electronic device
JP6959785B2 (en) Circuit boards, electronic components and electronic modules
JPWO2020137152A1 (en) Wiring boards, electronics and electronic modules
JP2001274280A (en) Multipiece ceramic wiring substrate
JP3872402B2 (en) Wiring board
CN107431047B (en) Wiring substrate, electronic device, and electronic module
JP2008034782A (en) Electronic component housing package, and electronic device
JPH11345734A (en) Laminated ceramic capacitor
JP4986500B2 (en) Laminated substrate, electronic device and manufacturing method thereof.
JP2004281470A (en) Wiring board
JP4025655B2 (en) Wiring board
JP2004288661A (en) Wiring board
JP2004288659A (en) Wiring board
JP2004247699A (en) Wiring board
JP4409383B2 (en) Wiring board
JP2004259802A (en) Wiring board
JP2004281471A (en) Wiring board
JP2005260124A (en) Ceramic package for electronic component
JP2006185977A (en) Wiring board
JP4423053B2 (en) Wiring board

Legal Events

Date Code Title Description
A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20050614

A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20051209

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20061024

A521 Written amendment

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20061218

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20070116

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20070122

R150 Certificate of patent (=grant) or registration of utility model

Free format text: JAPANESE INTERMEDIATE CODE: R150

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20110126

Year of fee payment: 4

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20110126

Year of fee payment: 4

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20120126

Year of fee payment: 5

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20120126

Year of fee payment: 5

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20130126

Year of fee payment: 6

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20140126

Year of fee payment: 7

LAPS Cancellation because of no payment of annual fees