JP4518664B2

JP4518664B2 - Wiring board mounting structure and semiconductor device

Info

Publication number: JP4518664B2
Application number: JP2000378934A
Authority: JP
Inventors: 慎吾佐藤; 義博芭蕉
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2000-12-13
Filing date: 2000-12-13
Publication date: 2010-08-04
Anticipated expiration: 2020-12-13
Also published as: JP2002185112A

Description

【０００１】
【発明の属する技術分野】
本発明は、マイクロ波またはミリ波等の高周波の電気信号を処理する半導体素子を搭載する配線基板の実装構造および半導体装置に関し、特に外部電気回路基板との接続部における高周波の電気信号の伝送特性を改善した配線基板の実装構造および半導体装置に関するものである。
【０００２】
【従来の技術】
従来、マイクロ波やミリ波の電気信号を処理する半導体素子を配線基板に搭載して成る半導体装置は、外部電気回路基板との電気的接続をリード線で行なうタイプが主流であったが、伝送信号のさらなる高周波化に対し接続部での信号伝送ロスを少なくするために、外部電気回路基板との接続部の長さをより短くすることが必要になり、そのためリード線に代えて配線基板の下面に接続パッドを設け、これを半田を用いて外部電気回路基板と接続する表面実装型のチップスケールパッケージ（ＣＳＰ）やボールグリッドアレイタイプの採用が進められている。
【０００３】
これら表面実装型の半導体装置に用いられる配線基板は、例えば酸化アルミニウム質焼結体やガラスセラミックス焼結体等から成る絶縁基板とタングステンや銅等の金属材料から成る配線導体から構成され、その配線基板の上面に高周波半導体素子をワイヤーボンディング実装法やフリップチップ実装法等を用いて搭載し、配線基板と高周波半導体素子を電気的に接続させることにより半導体装置と成る。この配線基板は内部に配線導体を有し、その配線導体は、配線基板上面に形成された電極パッドから配線基板の下面に形成された接続パッドまで配設される。そして、この半導体装置は配線基板の接続パッドが低融点ろう材を用いて外部電気回路基板と物理的および電気的に接合され、外部電気回路基板に実装される。
【０００４】
一般に、伝送信号は高周波化するにつれ直進性が強くなり、ＣＳＰやボールグリッドアレイタイプ等の半導体装置に用いられる配線基板と外部電気回路基板との接続部のような信号伝送経路がほぼ直角に屈曲している部分では、伝送信号の一部が配線導体の壁面で反射や放射を起こし、その結果、電気信号特性の劣化が発生するが、その対策としては、その接続部を傾斜させることによって配線導体の壁面での反射や放射を抑制できることが知られている。
【０００５】
このような接続部を傾斜させる方法として特公平６−16521号公報には、図５に断面図で示すように、半導体素子11の電極12と配線基板14の電極パッド13の位置をずらして形成することにより電気信号伝送経路の垂直方向の屈曲部が鈍角を成すことを特徴とする半導体装置が提案されている。なお、15は電極12と電極パッド13とを接続する低融点ろう材としての半田である。
【０００６】
【発明が解決しようとする課題】
しかしながら、この特公平６−16521号公報に提案された半導体装置においては、対向する電極12と電極パッド13それぞれの位置をずらすことによって、両者の重なり部分が小さくなってしまうため、半田15を介して対向する半導体素子11を配線基板14へ実装する際のわずかな実装ズレにより導通不良が発生するという問題点があった。また同様に、配線基板14を外部電気回路基板へ実装する場合においても同様な問題点が発生するというものであった。
【０００７】
本発明は上記従来技術における問題点を解決すべく完成されたものであり、その目的は、配線基板を半田を介して外部電気回路基板上へ実装する際、配線基板と外部電気回路基板との接続部において高周波の電気信号を良好な伝送特性で伝送できる配線基板の実装構造を提供することにある。
【０００８】
また本発明の目的は、配線基板を半田を介して外部電気回路基板上へ実装した際、実装ズレに影響されず、確実に配線基板と外部電気回路基板との導通を確保でき、高い接続信頼性を得られると同時に、高周波の電気信号を良好な伝送特性で配線基板と外部電気回路基板間において伝送できる半導体装置を提供することにある。
【０００９】
【課題を解決するための手段】
本発明の配線基板の実装構造は、絶縁基板の上面に半導体素子が搭載され、下面に前記半導体素子が電気的に接続されるとともに外部電気回路基板との間で電気信号を入出力するための接続パッドを有する配線基板を、前記接続パッドと前記外部電気回路基板上面の導通パッドとを対向させて半田を介して接合することにより前記外部電気回路基板上に実装する配線基板の実装構造であって、前記接続パッドは前記絶縁基板の中央方向に向けて突出した半田引出部が形成され、かつ前記導通パッドは対向する前記接続パッドの前記半田引出部と反対方向に突出した半田引出部が形成されており、前記接続パッドおよび前記導通パッドのそれぞれの前記半田引出部によって互いに逆方向の半田によるメニスカステールが形成されていることを特徴とするものである。
【００１０】
また、本発明の配線基板の実装構造は、上記構成において、前記接続パッドの半田引出部および前記導通パッドの半田引出部が、長さが0.1ｍｍ以上0.8ｍｍ以下であり、各パッドとの接続部の幅が0.04ｍｍ以上0.2ｍｍ以下であることを特徴とするものである。
【００１１】
また、本発明の半導体装置は、絶縁基板の上面に半導体素子が搭載され、下面に前記半導体素子が電気的に接続されるとともに外部電気回路基板との間で電気信号を入出力するための接続パッドを有する配線基板を、前記接続パッドと前記外部電気回路基板上面の導通パッドとを対向させて半田を介して接合して成る半導体装置であって、前記接続パッドは前記絶縁基板の中央方向に向けて突出した半田引出部が形成され、かつ前記導通パッドは対向する前記接続パッドの前記半田引出部と反対方向に突出した半田引出部が形成されており、前記接続パッドおよび前記導通パッドのそれぞれの前記半田引出部によって互いに逆方向の半田によるメニスカステールが形成されていることを特徴とするものである。
【００１２】
また、本発明の半導体装置は、上記構成において、前記接続パッドの半田引出部および前記導通パッドの半田引出部が、長さが0.1ｍｍ以上0.8ｍｍ以下であり、各パッドとの接続部の幅が0.04ｍｍ以上0.2ｍｍ以下であることを特徴とするものである。
【００１３】
本発明の配線基板の実装構造によれば、絶縁基板の上面に半導体素子が搭載され、下面に半導体素子が電気的に接続されるとともに外部電気回路基板との間で電気信号を入出力するための接続パッドを有する配線基板を、接続パッドと外部電気回路基板上面の導通パッドとを対向させて半田を介して接合することにより外部電気回路基板上に実装する配線基板の実装構造であって、接続パッドは絶縁基板の中央方向に向けて突出した半田引出部が形成され、かつ導通パッドは対向する接続パッドの半田引出部と反対方向に突出した半田引出部が形成されており、接続パッドおよび導通パッドのそれぞれの半田引出部によって互いに逆方向の半田によるメニスカステールが形成されていることから、互いに逆方向の半田によるメニスカステールが形成されていることによって、配線基板と外部電気回路基板の接続部の形状が傾斜構造と成るので、その接続部における高周波の電気信号の反射・放射損失を低減することができ、高周波の電気信号を良好な伝送特性で伝送できると同時に、接続パッドおよび導通パッドを対向させてこれらの重なり部分の面積を十分に確保することができるため、半田による配線基板と外部電気回路基板との接続強度が増加し、その結果、高い接続信頼性を得ることができる。
【００１４】
また、接続パッドの半田引出部および導通パッドの半田引出部を、長さが0.1ｍｍ以上0.8ｍｍ以下であり、各パッドとの接続部の幅が0.04ｍｍ以上0.2ｍｍ以下としたときには、配線基板と外部電気回路基板の接続部の形状を傾斜構造と成すことができる十分なメニスカステールを形成できるとともに、その接続部における高周波の電気信号の反射・放射損失を低減することができ、高周波の電気信号を良好な伝送特性で伝送できる。
【００１５】
本発明の半導体装置によれば、絶縁基板の上面に半導体素子が搭載され、下面に半導体素子が電気的に接続されるとともに外部電気回路基板との間で電気信号を入出力するための接続パッドを有する配線基板を、接続パッドと外部電気回路基板上面の導通パッドとを対向させて半田を介して接合して成る半導体装置であって、接続パッドは絶縁基板の中央方向に向けて突出した半田引出部が形成され、かつ導通パッドは対向する接続パッドの半田引出部と反対方向に突出した半田引出部が形成されており、接続パッドおよび導通パッドのそれぞれの半田引出部によって互いに逆方向の半田によるメニスカステールが形成されていることから、互いに逆方向の半田によるメニスカステールが形成されていることによって、配線基板と外部電気回路基板の接続部の形状が傾斜構造と成るので、高周波の電気信号の反射・放射損失を低減できる接続部を有すると同時に、接続パッドおよび導通パッドを対向させてこれらの重なり部分の面積を十分に確保することができるため、半田による配線基板と外部電気回路基板との接続強度が増加し、その結果、高い接続信頼性を有する半導体装置を得ることができる。
【００１６】
また、本発明の半導体装置によれば、接続パッドの半田引出部および導通パッドの半田引出部を、長さが0.1ｍｍ以上0.8ｍｍ以下であり、各パッドとの接続部の幅が0.04ｍｍ以上0.2ｍｍ以下としたときには、配線基板と外部電気回路基板の接続部の形状を傾斜構造と成すことができる十分なメニスカステールを形成できると同時に、実装ズレに影響されず確実に配線基板と外部電気回路基板との接続部で高周波の電気信号に対する良好な導通を確保できることから接続信頼性の高い半導体装置を得ることができる。
【００１７】
【発明の実施の形態】
以下、本発明を図面に基づいて詳細に説明する。
【００１８】
図１は、本発明の配線基板の実装構造およびこの実装構造を有する本発明の半導体装置の実施の形態の一例を示す断面図である。図１において、１は配線基板、２は半導体素子、３は半田、４は接続パッド、５は導通パッド、６は外部電気回路基板を示す。
【００１９】
配線基板１を構成する絶縁基板１ａは、酸化アルミニウム質焼結体・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・ガラスセラミックス焼結体等の電気絶縁材料から成る略四角形状の板体であり、その内部に配線導体１ｂを有しており、またその上面中央部には、半導体素子２を搭載するための半導体素子搭載部１ｃを有している。
【００２０】
この半導体素子搭載部１ｃ上にエポキシ樹脂や銀エポキシ樹脂等を用いて半導体素子２を搭載し、この半導体素子２上の電極と配線基板１上の電極パッド１ｄとを金・銅・アルミニウム等の金属細線９で電気的に接続した後、銅やアルミニウム等から成る金属または酸化アルミニウム質焼結体等から成るセラミック製の蓋体をエポキシ等の樹脂や金属ロウ材等による封着、または溶接によって封止することによって半導体装置と成る。
【００２１】
そして、絶縁基板１ａの下面に形成された配線導体１ｂの導出部である接続パッド４と外部電気回路基板６上の導通パッド５とを半田３で接続することにより、半導体素子２と外部電気回路基板６とが金属細線９、電極パッド１ｄ、配線導体１ｂおよび接続パッド４を介して電気的に接続される。
【００２２】
この配線基板１は、例えば絶縁基板１ａが酸化アルミニウム質焼結体から成る場合は、酸化アルミニウム・酸化珪素・酸化マグネシウム・酸化カルシウム等の原料粉末に適当な有機バインダ・溶剤・可塑剤・分散材等を添加混合して泥漿状となすとともに、これを従来周知のドクターブレード法を採用してシート状となすことにより、複数枚のセラミックグリーンシートを得、しかる後、このセラミックグリーンシートに適当な打ち抜き加工を施すとともに、タングステン・モリブデン・マンガン・銅・銀・ニッケル・パラジウム・金等の金属材料粉末に適当な有機バインダ・溶剤を混合して成る導電ペーストを前記グリーンシートに予めスクリーン印刷法等により所定パターンに印刷塗布することによって接続パッド４および配線導体１ｂ・電極パッド１ｄを形成後、このグリーンシートを必要に応じて上下に積層し、これを約1600℃の温度で焼成することによって製作される。
【００２３】
半田３は、配線基板１を構成する絶縁基板１ａ下面の接続パッド４と外部電気回路基板６の導通パッド５とを電気的・物理的に接続する働きを持つ。その材料としては、鉛錫共晶半田や鉛高含有の鉛錫半田または鉛フリー半田を用いることができる。
【００２４】
外部電気回路基板６は、半田３を介して配線基板１と物理的に接続されるだけでなく、高周波の電気信号を配線基板に半田３を介して伝送する役割を持つ。そのため、外部電気回路基板６は、半田３を介して配線基板１と物理的・電気的接続を行なうための導通パッド５と配線導体６ａを有する。
【００２５】
外部電気回路基板６は、例えばガラス−エポキシ樹脂・ガラス−フッ素樹脂・フッ素樹脂単体等から成る複数の絶縁層を積層して成る絶縁基体の各絶縁層間および表面に銅箔から成る配線導体６ａが被着されて構成されている。このような絶縁基体を構成する絶縁層は、樹脂単体による板状、またはガラス繊維を縦横に編んで形成されたガラスクロスにエポキシ樹脂またはフッ素樹脂を含浸させて板状にしたものであり、その上面に銅箔が予め被着されており、その銅箔を所定のパターンにエッチングすることにより配線導体６ａが形成される。そしてこれらの各絶縁層を間に未硬化のエポキシ樹脂またはフッ素樹脂から成る接着剤を挟んで重ね合わせるとともに、加熱装置を備えたプレス装置により加熱しながらプレスし接着剤を硬化させることにより積層一体化される。
【００２６】
次に、この基板にルータービット等の機械的研削により貫通孔を形成した後、メッキ法によりこの貫通孔に銅等の金属メッキを行なう。その後、表層をエポキシ樹脂やフッ素樹脂等の絶縁材料でコーティングすることにより外部電気回路基板６を形成する。
【００２７】
図２は本発明の半導体装置を構成する配線基板１の実施の形態の一例における下面の接続パッド４とこの配線基板１が実装される外部電気回路基板６の導通パッド５を示す図である。
【００２８】
接続パッド４は、タングステン・モリブデン・マンガン・銅・銀・ニッケル・パラジウム・金等の金属材料粉末に適当な有機バインダ・溶剤を混合して成る導電ペーストを、前記グリーンシートに予めスクリーン印刷法等により所定パターンに印刷塗布し、これを焼成することによって形成される。
【００２９】
接続パッド４は、配線基板１を外部電気回路基板６に半田３を用いることによって物理的に接続するだけでなく、高周波の電気信号を伝送し配線基板１と外部電気回路基板６とを電気的に接続させる役割を持つ。また、その表面にニッケルや金等の良導電性で耐蝕性および半田３との濡れ性が良好な金属をメッキ法により0.01〜20μｍの厚みに被着させておくと、接続パッド４の酸化腐食を有効に防止することができるとともに半田３による配線基板１と外部電気回路基板６との接続を強固となすことができる。
【００３０】
接続パッド４の内、電気信号を入出力する接続パッド４には、高周波の電気信号を良好な伝送特性で伝送させるために半田引出部７が形成される。通常、絶縁基板１ａ内の配線導体１ｂは、配線基板１を外部電気回路基板６へ実装する際の配線基板１と外部電気回路基板６との接続部間での電気的短絡を防止するために隣接する接続パッド４間の距離を大きくし、かつ高周波の電気信号の伝送特性を劣化させないために、半導体素子２を搭載する半導体素子搭載部１ｃを中心に外側へ向け絶縁基板１ａ内で展開される。よって、半田引出部７も配線導体１ｂの展開にあわせ、かつ高周波の電気信号の伝送特性を劣化させないようにするために、半導体素子２が搭載される絶縁基板１ａ上の半導体素子搭載部１ｃに向けて突出するよう形成される。よって、半田引出部７は、絶縁基板１ａ内の配線導体１ｂの展開にあわせ、かつ高周波の電気信号の伝送特性を劣化させなければ、絶縁基板１ａの外周に対し直角でもあってもよく、絶縁基板１ａ上の半導体素子搭載部１ｃを中心とする放射状に形成してもかまわない。
【００３１】
また、半田引出部７は、高周波の電気信号を良好な特性で伝送するために電気信号を入出力する全ての接続パッド４に形成することが望ましい。
【００３２】
半田引出部７の大きさとしては、接続パッド４と半田引出部７との接続部の幅が0.04ｍｍ未満の場合には、接続パッド４からの半田３を半田引出部７へ引出すことが難しくなる。また0.2ｍｍを超える場合には、半田引出部７への半田３の流れ出し量が多くなり、接続パッド４に接合される半田端子の中心の位置ズレが大きくなることによって外部電気回路６の導通パッド５に対して半田端子がズレて正確な接続ができなくなり、その結果、配線基板１と外部電気回路基板６との導通不良が発生する問題点が生じやすくなる。加えて、半田引出部７を大きくすることは、接続パッド４の面積が大きくなり配線基板１のグランド層との間に高い浮遊容量が発生し、インピーダンスが急激に変化することによって、高周波の電気信号の伝送特性の劣化が発生する恐れがある。そのため接続パッド４と半田引出部７との接続部の幅は0.04ｍｍ以上0.2ｍｍ以下であることが好ましい。
【００３３】
また、半田引出部７の長さは、0.1ｍｍ未満の場合には、半田引出部７での半田メニスカステール形成が十分でなく、配線基板１を外部電気回路基板６に搭載する際の実装ズレにより接続部の形状が十分な傾斜構造とならず、その結果、その接続部における高周波の電気信号の反射・放射損失を低減できなくなる。また半田引出部７の長さが0.8ｍｍを超えると、半田引出部７の先端まで半田３を引出すことが困難になるばかりでなく、高密度に配設された隣接の接続パッド４と電気的短絡しやすくなる。そのため、半田引出部７の長さは0.1ｍｍ以上0.8ｍｍ以下であることが好ましい。
【００３４】
導通パッド５は、配線基板１を外部電気回路基板６に半田３を用いることによって物理的に接続するだけでなく、高周波の電気信号を伝送し配線基板１と外部電気回路基板６とを電気的に接続させる役割を持つ。また、導通パッド５の材質として、半田３が濡れ易く、また導通抵抗値の低い材料が必要であり、一般には銅が用いられる。また、半田３との濡れ性を改善するために導通パッド５表面に半田３との濡れ性が良好な厚み0.01〜20μｍの金属をメッキ法により被着させてもよい。
【００３５】
導通パッド５には、対向する接続パッド４に形成された半田引出部７と反対方向に突出した半田引出部８が形成される。
【００３６】
この半田引出部８の突出方向は、対向する半田引出部７と反対の方向とすることが重要である。電気信号は、高周波が進むにつれ直進性が強くなり信号伝送経路が90度、あるいは90度より小さい角度で屈曲している部分では伝送信号の一部が反射や放射を起こし、その結果、信号特性の劣化が発生する。そのために、半田引出部８は半田引出部７に対して90度を超える角度を有することが必要であり、伝送信号の反射や放射を抑え、信号特性の劣化を最小に低減させるために望ましくは180度異なる方向であることが望ましい。
【００３７】
半田引出部８は、高周波の電気信号を良好な特性で伝送するために電気信号を入出力する全ての導通パッド５に形成することが望ましい。
【００３８】
この半田引出部８の大きさについても、導通パッド５と半田引出部８との接続部の幅が0.04ｍｍ未満の場合には、導通パッド５からの半田３を半田引出部８へ引出すことが難しくなる。また0.2ｍｍを超える場合には、半田引出部８への半田３の流れ出し量が大きくなり、その結果、配線基板１の実装高さが低くなることによる接続信頼性の低下を招く問題が発生しやすくなる。したがって、半田引出部８の長さは、接続パッド４に形成された半田引出部７と同様の理由により、0.1ｍｍ以上0.8ｍｍ以下であることが好ましい。
【００３９】
なお、半田引出部７および半田引出部８の長さおよび幅は、全てが同じ寸法でなくともかまわない。例えば応力が集中する外周コーナー部の接続パッドおよび導通パッドに形成される半田引出部７および半田引出部８は、高い接続信頼性を得るためにできるだけ長さは長く、かつ幅は広くすることが望ましい。
【００４０】
【実施例】
以下に本発明の具体例を示す。
【００４１】
配線基板１の絶縁基板１ａとして、外寸法が13ｍｍ×13ｍｍ、厚みが0.4ｍｍであり、材質がガラスセラミックス（誘電率ε＝５）のものを準備した。
【００４２】
これら絶縁基板１ａを用いた配線基板１は、印刷法により形成した配線導体１ｂ、電極パッド１ｄ、接続パッド４および半田引出部７を有するグリーンシートを積層し焼成を行なうことによって得た。
【００４３】
接続パッド４は、これらの配線基板１の下面に、直径が0.4ｍｍの接続パッド４が0.8ｍｍピッチで図３ａに示すような配列で165個形成した。そして、半田引出部７の高周波の電気信号の伝送特性に与える影響を調べるため、高周波の電気信号を伝送する接続パッド４のみ半田引出部７を形成し、接続パッド４群の最外周の各辺の中央部に１箇所ずつ、合計４箇所配置した。
【００４４】
また、外部電気回路基板６として、ガラスクロスにフッ素樹脂を含浸させて形成した絶縁層の上面に銅の配線導体６ａを形成し、それらの絶縁層を積層したのちプレスし積層一体化したものを形成した。外部電気回路基板６上面には直径が0.4ｍｍの導通パッド５を0.8ｍｍピッチで図３ｂに示すように165個形成した。そして、半田引出部８の高周波の電気信号の伝送特性に与える影響を調べるため、高周波の電気信号を伝送する導通パッド５のみ半田引出部８を形成し、導通パッド５群の最外周の各辺の中央部に１箇所ずつ、合計４箇所配置した。
【００４５】
なお、半田引出部７および半田引出部８は、高周波の電気信号の伝送特性に対する影響を調査するためそれぞれ長さが０から0.8ｍｍ、幅が０ｍｍから0.4ｍｍの間で種々設定した。
【００４６】
配線基板１の配線導体１ｂは、配線基板１上面の電極パッド１ｄと下面の接続パッド４とを電気的に接続している。この例では、配線基板１上面での配線導体１ｂの幅は0.18ｍｍ、長さは3.0ｍｍとした。また配線基板１上面の配線導体１ｂから0.1ｍｍの間隔をおいて同一面接地導体を配線基板１上面のほぼ全面に形成した。
【００４７】
また、外部電気回路基板６の配線導体６ａは、フッ素系樹脂基板上に銅配線を形成しており、銅配線の幅は0.26ｍｍ、長さは4.70ｍｍとし、銅配線から0.1ｍｍの間隔をおいて同一面接地導体を形成した。
【００４８】
配線導体１ｂおよび６ａ、電極パッド１ｄならびに配線基板１下面の接続パッド４および半田引出部７には、その表面に無電解Ｎｉメッキおよび無電解Ａｕメッキ処理を施した。それぞれのメッキ厚みは、２μｍおよび0.1μｍである。
【００４９】
配線基板１は、錫37重量％鉛63重量％である半田ペーストを用いて外部電気回路基板６と接続を行ない試料を得た。
【００５０】
そして、高周波の電気信号の伝送特性を評価するため配線基板１上面の配線導体１ｂの先端部分および外部電気回路基板６の銅配線の先端部分を、接続媒体としてウエハープローブを用いてネットワークアナライザーに接続し、各試料について高周波の電気信号に対する反射損失Ｓ11および透過損失Ｓ21の測定を行なった。
【００５１】
伝送が良好かどうかの判定は、高周波の電気信号伝送のために必要とされる係数値である電圧反射係数Γ＝0.18および電圧透過係数Ｔ＝0.90を下記式に導入し得られた値、すなわち反射損失Ｓ11が−15ｄＢ以下および透過損失Ｓ21が−1.0ｄＢ以上である電気信号の周波数値が高いほど良好とした。なお、反射損失Ｓ11＝−20ｌｏｇ│Γ│、透過損失Ｓ21＝−20ｌｏｇ│Ｔ│である。
【００５２】
表１に測定結果を示す。
【００５３】
【表１】

【００５４】
表１から明らかなように、高周波の電気信号の伝送特性を劣化させず、より高い周波数の電気信号を伝送させるためには、半田引出部７および半田引出部８の長さを0.1ｍｍ以上0.8ｍｍ以下にする必要があること、また半田引出部の幅を0.04ｍｍ以上0.2ｍｍ以下にする必要があることわかった。
【００５５】
すなわち、サンプルNo.１からサンプルNo.５において判るように、半田引出部７および半田引出部８を形成されていない場合４６ＧＨｚの電気信号を伝送することができたが、半田引出部７および半田引出部８の長さを0.1ｍｍ以上にすることによって46ＧＨｚを超える周波数の電気信号を伝送することができ、特に半田引出部７および半田引出部８の長さが0.8ｍｍの場合において62ＧＨｚの周波数の電気信号を伝送することができた。
【００５６】
しかしながら、サンプルNo.６に示すように半田引出部７および半田引出部８の長さが1.0ｍｍを超えた場合、半田引出部７および半田引出部８への半田の流れ出しが十分でなかったため、62ＧＨｚを超える周波数の電気信号を伝送させることは困難であったが、それ以下の周波数の電気信号については良好な伝送が可能であった。
【００５７】
また、サンプルNo.４およびサンプルNo.７からサンプルNo.９において判るように半田引出部７および半田引出部８の幅を0.04ｍｍ以上0.2ｍｍ以下にすることによって、半田引出部７および半田引出部８を設けていない場合に伝送が可能だった周波数値である46ＧＨｚを超える周波数の電気信号を伝送することができた。
【００５８】
しかしながら、サンプルNo.10およびサンプルNo.11に示すように半田引出部７および半田引出部８の幅が0.2ｍｍを超えた場合、46ＧＨｚを超える周波数の電気信号を伝送させることは困難であったが、それ以下の周波数の電気信号については良好な伝送が可能であった。これは、接続パッド４および導通パッド５の面積が大きくなり、配線基板１および外部電気回路基板６のグランド層との間に高い浮遊容量が発生し、インピーダンスが急激に変化したことにより、電気信号の伝送特性が劣化したためである。
【００５９】
なお、本発明は上記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。例えば、上記の実施の形態の例において、半田引出部７および８の形状は、図２に示すように略四角形状であったが、図４に示すような三角形状、楕円状等であってもかまわない。この場合も、接続パッド４および導通パッド５との接続部の幅は0.04ｍｍ以上0.2ｍｍ以下としておくことが好ましい。
【００６０】
また、上記の実施の形態の例において配線基板１への半導体素子２への実装法はワイヤーボンディング法であったが、フリップチップ実装法でもかまわない。
【００６１】
【発明の効果】
以上のように本発明の配線基板の実装構造によれば、絶縁基板の上面に半導体素子が搭載され、下面に半導体素子が電気的に接続されるとともに外部電気回路基板との間で電気信号を入出力するための接続パッドを有する配線基板を、接続パッドと外部電気回路基板上面の導通パッドとを対向させて半田を介して接合することにより外部電気回路基板上に実装する配線基板の実装構造であって、接続パッドは絶縁基板の中央方向に向けて突出した半田引出部が形成され、かつ導通パッドは対向する接続パッドの半田引出部と反対方向に突出した半田引出部が形成されており、接続パッドおよび導通パッドのそれぞれの半田引出部によって互いに逆方向の半田によるメニスカステールが形成されていることから、互いに逆方向の半田によるメニスカステールが形成されていることによって配線基板と外部電気回路基板の接続部の形状が傾斜構造と成るので、その接続部における高周波の電気信号の反射・放射損失を低減することができ、高周波の電気信号を良好な伝送特性で伝送できると同時に、接続パッドおよび導通パッドを対向させてこれらの重なり部分の面積を十分に確保することができるため、半田による配線基板と外部電気回路基板との接続強度が増加し、その結果、高い接続信頼性を得ることができる。
【００６２】
また、接続パッドの半田引出部および導通パッドの半田引出部を、長さが0.1ｍｍ以上0.8ｍｍ以下であり、各パッドとの接続部の幅が0.04ｍｍ以上0.2ｍｍ以下としたときには、配線基板と外部電気回路基板の接続部の形状を傾斜構造と成すことができる十分なメニスカステールを形成でき、その結果、その接続部における高周波の電気信号の反射・放射損失を低減することができ、高周波の電気信号を良好な伝送特性で伝送できる。
【００６３】
本発明の半導体装置によれば、絶縁基板の上面に半導体素子が搭載され、下面に半導体素子が電気的に接続されるとともに外部電気回路基板との間で電気信号を入出力するための接続パッドを有する配線基板を、接続パッドと外部電気回路基板上面の導通パッドとを対向させて半田を介して接合して成る半導体装置であって、接続パッドは絶縁基板の中央方向に向けて突出した半田引出部が形成され、かつ導通パッドは対向する接続パッドの半田引出部と反対方向に突出した半田引出部が形成されており、接続パッドおよび導通パッドのそれぞれの半田引出部によって互いに逆方向の半田によるメニスカステールが形成されていることから、互いに逆方向の半田によるメニスカステールが形成されていることによって配線基板と外部電気回路基板の接続部の形状が傾斜構造と成るので、高周波の電気信号の反射・放射損失を低減できる接続部を有すると同時に、接続パッドおよび導通パッドを対向させてこれらの重なり部分の面積を十分に確保することができるため、半田による配線基板と外部電気回路基板との接続強度が増加し、その結果、高い接続信頼性を有する半導体装置を得ることができる。
【００６４】
また、本発明の半導体装置によれば、接続パッドの半田引出部および導通パッドの半田引出部は、長さが0.1ｍｍ以上0.8ｍｍ以下であり、各パッドとの接続部の幅が0.04ｍｍ以上0.2ｍｍ以下であるときには、配線基板と外部電気回路基板の接続部の形状を傾斜構造と成すことができる十分なメニスカステールを形成できると同時に、実装ズレに影響されず確実に配線基板と外部電気回路基板との接続部で高周波の電気信号に対する良好な導通を確保できることから接続信頼性の高い半導体装置を得ることができる。
【図面の簡単な説明】
【図１】本発明の配線基板の実装構造の実施の形態の一例を示す断面図である。
【図２】（ａ）〜（ｃ）は、それぞれ本発明の半導体装置を構成する配線基板の接続パッドおよび外部電気回路基板の導通パッドの一例を示し、（ａ）は配線基板の下面の平面図、（ｂ）は外部電気回路基板の上面の平面図、（ｃ）は接続パッドおよび導通パッドの平面図である。
【図３】（ａ）および（ｂ）は、それぞれ本発明の実施例での配線基板と外部電気回路基板を示す平面図である。
【図４】（ａ）〜（ｃ）は、それぞれ本発明の半導体装置を構成する配線基板の接続パッドおよび外部電気回路基板の導通パッドの他の例を示す平面図である。
【図５】従来の配線基板の実装構造の例を示す断面図である。
【符号の説明】
１・・・配線基板
１ａ・・絶縁基板
１ｂ・・配線基板の配線導体
１ｃ・・半導体素子搭載部
１ｄ・・電極パッド
２・・・半導体素子
３・・・半田
４・・・接続パッド
５・・・導通パッド
６・・・外部電気回路基板
６ａ・・外部電気回路基板の配線導体
７・・接続パッドの半田引出部
８・・導通パッドの半田引出部
９・・金属細線[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mounting structure of a wiring board on which a semiconductor element for processing a high-frequency electric signal such as a microwave or a millimeter wave is mounted, and a semiconductor device, and more particularly to transmission characteristics of a high-frequency electric signal at a connection portion with an external electric circuit board. The present invention relates to a wiring board mounting structure and a semiconductor device that are improved.
[0002]
[Prior art]
Conventionally, a semiconductor device in which a semiconductor element for processing an electric signal of microwave or millimeter wave is mounted on a wiring board has been mainly used for the electrical connection with an external electric circuit board by a lead wire. In order to reduce the signal transmission loss at the connection part for further higher frequency of the signal, it is necessary to shorten the length of the connection part with the external electric circuit board. Adoption of a surface mount type chip scale package (CSP) or a ball grid array type in which a connection pad is provided on the lower surface and this is connected to an external electric circuit board using solder is being promoted.
[0003]
The wiring board used in these surface-mount type semiconductor devices is composed of an insulating substrate made of, for example, an aluminum oxide sintered body or a glass ceramic sintered body, and a wiring conductor made of a metal material such as tungsten or copper. A high-frequency semiconductor element is mounted on the upper surface of the substrate using a wire bonding mounting method, a flip-chip mounting method, or the like, and a wiring board and the high-frequency semiconductor element are electrically connected to form a semiconductor device. The wiring board has a wiring conductor therein, and the wiring conductor is disposed from the electrode pad formed on the upper surface of the wiring board to the connection pad formed on the lower surface of the wiring board. In this semiconductor device, the connection pads of the wiring board are physically and electrically joined to the external electric circuit board using a low melting point brazing material, and are mounted on the external electric circuit board.
[0004]
In general, as the transmission signal becomes higher in frequency, the straightness becomes stronger, and the signal transmission path such as the connection part between the wiring board and the external electric circuit board used in a semiconductor device such as a CSP or a ball grid array type is bent at a substantially right angle. In the area where the signal is transmitted, part of the transmission signal is reflected or radiated on the wall surface of the wiring conductor, resulting in deterioration of the electrical signal characteristics. It is known that reflection and radiation on the wall surface of a conductor can be suppressed.
[0005]
Japanese Patent Publication No. 6-16521 discloses a method for inclining such a connecting portion by shifting the positions of the electrode 12 of the semiconductor element 11 and the electrode pad 13 of the wiring board 14 as shown in a sectional view in FIG. Thus, there has been proposed a semiconductor device characterized in that the bent portion in the vertical direction of the electric signal transmission path forms an obtuse angle. Reference numeral 15 denotes solder as a low melting point brazing material for connecting the electrode 12 and the electrode pad 13.
[0006]
[Problems to be solved by the invention]
However, in the semiconductor device proposed in Japanese Examined Patent Publication No. 6-16521, since the positions of the opposing electrode 12 and electrode pad 13 are shifted, the overlapping portion between the two becomes small. Thus, there is a problem in that a conduction failure occurs due to a slight mounting deviation when mounting the semiconductor element 11 facing each other on the wiring board 14. Similarly, when the wiring board 14 is mounted on the external electric circuit board, the same problem occurs.
[0007]
The present invention has been completed to solve the above-described problems in the prior art, and an object of the present invention is to connect the wiring board and the external electric circuit board when the wiring board is mounted on the external electric circuit board via solder. It is an object of the present invention to provide a wiring board mounting structure capable of transmitting high-frequency electrical signals with good transmission characteristics at a connecting portion.
[0008]
Further, the object of the present invention is that when the wiring board is mounted on the external electric circuit board via solder, it is possible to ensure the continuity between the wiring board and the external electric circuit board without being affected by mounting displacement, and high connection reliability. It is an object of the present invention to provide a semiconductor device capable of obtaining high performance and transmitting high-frequency electric signals between a wiring board and an external electric circuit board with good transmission characteristics.
[0009]
[Means for Solving the Problems]
The mounting structure of the wiring board according to the present invention has a semiconductor element mounted on the upper surface of the insulating substrate, the semiconductor element is electrically connected to the lower surface, and an electric signal is inputted / outputted to / from an external electric circuit board. A wiring board mounting structure in which a wiring board having a connection pad is mounted on the external electric circuit board by bonding the connection pad and a conductive pad on the upper surface of the external electric circuit board facing each other via solder. The connection pad is formed with a solder lead-out portion protruding toward the center of the insulating substrate, and the conductive pad is formed with a solder lead-out portion protruding in the opposite direction to the solder lead-out portion of the opposing connection pad. Been And a meniscus tail made of solder in opposite directions is formed by the solder lead portions of the connection pads and the conductive pads. It is characterized by being.
[0010]
In the wiring board mounting structure of the present invention, in the above configuration, the length of the solder lead-out portion of the connection pad and the solder lead-out portion of the conductive pad is 0.1 mm or more and 0.8 mm or less, and the connection with each pad The width of the part is 0.04 mm or more and 0.2 mm or less.
[0011]
In the semiconductor device of the present invention, a semiconductor element is mounted on the upper surface of the insulating substrate, the semiconductor element is electrically connected to the lower surface, and a connection for inputting / outputting an electric signal to / from an external electric circuit substrate is performed. A wiring board having a pad is bonded via solder with the connection pad and the conductive pad on the upper surface of the external electric circuit board facing each other. Completion The connection pad is formed with a solder lead-out portion protruding toward the center of the insulating substrate, and the conductive pad protrudes in the opposite direction to the solder lead-out portion of the opposing connection pad. Solder extraction part is formed And a meniscus tail made of solder in opposite directions is formed by the solder lead portions of the connection pads and the conductive pads. It is characterized by being.
[0012]
In the semiconductor device according to the present invention, in the above configuration, the solder lead-out portion of the connection pad and the solder lead-out portion of the conductive pad have a length of 0.1 mm to 0.8 mm, and the width of the connection portion with each pad Is 0.04 mm or more and 0.2 mm or less.
[0013]
According to the mounting structure of the wiring board of the present invention , Absolutely Edge board A semiconductor element is mounted on the top surface, On the bottom A wiring board having a connection pad for electrically connecting a semiconductor element and inputting / outputting an electric signal to / from an external electric circuit board is disposed with the connection pad and the conductive pad on the upper surface of the external electric circuit board facing each other. A wiring board mounting structure for mounting on an external electric circuit board by joining via solder, The connection pad has a solder lead-out that protrudes toward the center of the insulating substrate. Guidance The through-pad is formed with a solder lead-out portion protruding in the opposite direction to the solder lead-out portion of the opposing connection pad A meniscus tail made of solder in opposite directions is formed by the respective solder lead portions of the connection pad and the conduction pad. Because , Mutual In the opposite direction Half of Meniscus tail by rice field was formed Have By , The connection part between the wiring board and the external electric circuit board has an inclined structure. Completion Ru Because In addition, it is possible to reduce the reflection / radiation loss of high-frequency electrical signals at the connection part, and to transmit high-frequency electrical signals with good transmission characteristics. Since a sufficient area can be secured, the connection strength between the wiring board and the external electric circuit board by solder increases, and as a result, high connection reliability can be obtained.
[0014]
In addition, when the length of the lead-out portion of the connection pad and the lead-out portion of the conductive pad is 0.1 mm to 0.8 mm and the width of the connection portion with each pad is 0.04 mm to 0.2 mm, the wiring board A sufficient meniscus tail that can be formed into an inclined structure in the shape of the connection portion between the external electric circuit board and the external electric circuit board can be formed, and reflection / radiation loss of a high-frequency electric signal at the connection portion can be reduced. Signals can be transmitted with good transmission characteristics.
[0015]
According to the semiconductor device of the present invention , Absolutely A semiconductor element is mounted on the upper surface of the edge substrate, and the lower surface Half A wiring board having a connection pad for electrically connecting a conductor element and inputting / outputting an electric signal to / from an external electric circuit board is disposed with the connection pad and the conductive pad on the upper surface of the external electric circuit board facing each other. Join through solder Completion The connection pad is formed with a solder lead-out portion protruding toward the center of the insulating substrate, and the conductive pad is formed with a solder lead-out portion protruding in the opposite direction to the solder lead-out portion of the opposing connection pad Been A meniscus tail made of solder in opposite directions is formed by the respective solder lead portions of the connection pad and the conduction pad. Because , Mutual A meniscus tail is formed by soldering in the opposite direction. Have By , The connection part between the wiring board and the external electric circuit board has an inclined structure. Completion Ru Because Since it has a connection part that can reduce the reflection / radiation loss of high-frequency electric signals, and at the same time, the connection pad and the conductive pad can be opposed to ensure a sufficient area of these overlapping parts, The connection strength with the external electric circuit board is increased, and as a result, a semiconductor device having high connection reliability can be obtained.
[0016]
Further, according to the semiconductor device of the present invention, the length of the solder lead-out portion of the connection pad and the solder lead-out portion of the conductive pad is 0.1 mm or more and 0.8 mm or less, and the width of the connection portion with each pad is 0.04 mm or more. When the thickness is 0.2 mm or less, it is possible to form a sufficient meniscus tail that can form an inclined structure in the connection part between the wiring board and the external electric circuit board. A semiconductor device with high connection reliability can be obtained because good conduction to a high-frequency electric signal can be ensured at a connection portion with the circuit board.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings.
[0018]
FIG. 1 is a cross-sectional view showing an example of an embodiment of a wiring board mounting structure according to the present invention and a semiconductor device according to the present invention having the mounting structure. In FIG. 1, 1 is a wiring board, 2 is a semiconductor element, 3 is solder, 4 is a connection pad, 5 is a conduction pad, and 6 is an external electric circuit board.
[0019]
The insulating substrate 1a constituting the wiring substrate 1 is made of an electrically insulating material such as an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body, a silicon carbide sintered body, or a glass ceramic sintered body. It is a substantially rectangular plate body having a wiring conductor 1b therein and a semiconductor element mounting portion 1c for mounting the semiconductor element 2 at the center of the upper surface thereof.
[0020]
A semiconductor element 2 is mounted on the semiconductor element mounting portion 1c using an epoxy resin, a silver epoxy resin, or the like, and an electrode on the semiconductor element 2 and an electrode pad 1d on the wiring board 1 are made of gold, copper, aluminum, or the like. After being electrically connected with the thin metal wire 9, from copper or aluminum Completion From metal or aluminum oxide sintered body Completion A ceramic lid body is sealed by sealing with a resin such as epoxy, a metal brazing material, or the like, or by welding.
[0021]
Then, by connecting the connection pad 4, which is a lead-out portion of the wiring conductor 1 b formed on the lower surface of the insulating substrate 1 a, and the conduction pad 5 on the external electric circuit substrate 6 with the solder 3, the semiconductor element 2 and the external electric circuit are connected. The substrate 6 is electrically connected through the fine metal wire 9, the electrode pad 1 d, the wiring conductor 1 b and the connection pad 4.
[0022]
For example, when the insulating substrate 1a is made of an aluminum oxide sintered body, the wiring substrate 1 is made of an organic binder, solvent, plasticizer, or dispersion material suitable for raw material powders such as aluminum oxide, silicon oxide, magnesium oxide, and calcium oxide. Etc. are added and mixed to make a mud, and this is made into a sheet by adopting a conventionally known doctor blade method to obtain a plurality of ceramic green sheets, and then suitable for this ceramic green sheet. Punching is performed, and an appropriate organic binder and solvent are mixed with tungsten, molybdenum, manganese, copper, silver, nickel, palladium, gold, and other metal material powders. Completion After forming the connection pad 4 and the wiring conductor 1b / electrode pad 1d by printing and applying a conductive paste to the green sheet in advance by a screen printing method or the like, the green sheet is laminated up and down as necessary. It is manufactured by firing at a temperature of about 1600 ° C.
[0023]
The solder 3 has a function of electrically and physically connecting the connection pads 4 on the lower surface of the insulating substrate 1 a constituting the wiring substrate 1 and the conduction pads 5 of the external electric circuit substrate 6. As the material, lead-tin eutectic solder, lead-tin solder containing a high amount of lead, or lead-free solder can be used.
[0024]
The external electric circuit board 6 is not only physically connected to the wiring board 1 via the solder 3 but also has a role of transmitting a high-frequency electric signal to the wiring board via the solder 3. Therefore, the external electric circuit board 6 has a conductive pad 5 and a wiring conductor 6 a for performing physical and electrical connection with the wiring board 1 via the solder 3.
[0025]
The external electric circuit board 6 is made of, for example, glass-epoxy resin, glass-fluorine resin, fluorine resin alone, etc. Completion A wiring conductor 6a made of copper foil is deposited on each insulating layer and on the surface of an insulating substrate formed by laminating a plurality of insulating layers. The insulating layer constituting such an insulating substrate is a plate formed by impregnating an epoxy resin or a fluororesin into a glass cloth formed by knitting glass fibers longitudinally and laterally with a single resin, Copper foil is previously deposited on the upper surface, and the wiring conductor 6a is formed by etching the copper foil into a predetermined pattern. These insulating layers are laminated with an adhesive made of uncured epoxy resin or fluororesin sandwiched between them, and the adhesive is cured by pressing while heating with a pressing device equipped with a heating device, thereby integrating the layers. It becomes.
[0026]
Next, a through hole is formed in the substrate by mechanical grinding such as a router bit, and then metal plating such as copper is performed on the through hole by a plating method. Thereafter, the external electric circuit board 6 is formed by coating the surface layer with an insulating material such as epoxy resin or fluorine resin.
[0027]
FIG. 2 is a view showing the connection pads 4 on the lower surface and the conduction pads 5 of the external electric circuit board 6 on which the wiring board 1 is mounted in an example of the embodiment of the wiring board 1 constituting the semiconductor device of the present invention.
[0028]
The connection pad 4 is made by mixing an appropriate organic binder / solvent with metal powder such as tungsten / molybdenum / manganese / copper / silver / nickel / palladium / gold. Completion The conductive paste is formed by printing and applying a predetermined pattern on the green sheet in advance by a screen printing method or the like, and baking the applied pattern.
[0029]
The connection pad 4 not only physically connects the wiring board 1 to the external electric circuit board 6 by using the solder 3 but also transmits a high-frequency electric signal to electrically connect the wiring board 1 and the external electric circuit board 6. Have a role to connect to. Further, if a metal having good conductivity, corrosion resistance and good wettability with the solder 3 such as nickel or gold is deposited on the surface to a thickness of 0.01 to 20 μm by a plating method, the oxidative corrosion of the connection pad 4 Can be effectively prevented, and the connection between the wiring board 1 and the external electric circuit board 6 by the solder 3 can be strengthened.
[0030]
Among the connection pads 4, solder lead-out portions 7 are formed in the connection pads 4 for inputting / outputting electric signals in order to transmit high-frequency electric signals with good transmission characteristics. Usually, the wiring conductor 1b in the insulating substrate 1a is used to prevent an electrical short circuit between the connection portions of the wiring substrate 1 and the external electric circuit substrate 6 when the wiring substrate 1 is mounted on the external electric circuit substrate 6. In order to increase the distance between adjacent connection pads 4 and not to deteriorate the transmission characteristics of high-frequency electric signals, the semiconductor element mounting portion 1c on which the semiconductor element 2 is mounted is developed in the insulating substrate 1a outward. The Therefore, in order for the solder lead-out portion 7 to match the development of the wiring conductor 1b and not to deteriorate the transmission characteristics of the high-frequency electrical signal, the solder lead-out portion 7 is provided on the semiconductor element mounting portion 1c on the insulating substrate 1a on which the semiconductor element 2 is mounted. It is formed so as to protrude. Therefore, the solder lead-out portion 7 may be perpendicular to the outer periphery of the insulating substrate 1a as long as the wiring conductor 1b in the insulating substrate 1a is developed and the transmission characteristics of high-frequency electrical signals are not deteriorated. You may form radially centering on the semiconductor element mounting part 1c on the board | substrate 1a.
[0031]
Further, it is desirable that the solder lead-out portions 7 are formed on all the connection pads 4 that input / output electric signals in order to transmit high-frequency electric signals with good characteristics.
[0032]
As for the size of the solder drawing portion 7, it is difficult to draw the solder 3 from the connection pad 4 to the solder drawing portion 7 when the width of the connection portion between the connection pad 4 and the solder drawing portion 7 is less than 0.04 mm. Become. On the other hand, when the thickness exceeds 0.2 mm, the amount of the solder 3 flowing out to the solder lead-out portion 7 increases, and the misalignment of the center of the solder terminal joined to the connection pad 4 increases, whereby the conduction pad of the external electric circuit 6 is increased. As a result, the solder terminal is misaligned with respect to 5 and accurate connection cannot be made. In addition, enlarging the solder lead-out portion 7 increases the area of the connection pad 4 and generates a high stray capacitance with the ground layer of the wiring board 1, causing the impedance to change abruptly. There is a risk of deterioration of signal transmission characteristics. Therefore, the width of the connection portion between the connection pad 4 and the solder lead-out portion 7 is preferably 0.04 mm or more and 0.2 mm or less.
[0033]
Further, when the length of the solder lead-out portion 7 is less than 0.1 mm, the solder meniscus tail is not sufficiently formed in the solder lead-out portion 7, and mounting misalignment when the wiring board 1 is mounted on the external electric circuit board 6 is not achieved. As a result, the connecting portion does not have a sufficiently inclined structure, and as a result, the reflection / radiation loss of high-frequency electrical signals at the connecting portion cannot be reduced. If the length of the solder lead-out portion 7 exceeds 0.8 mm, not only will it be difficult to pull out the solder 3 to the tip of the solder lead-out portion 7, but it will be electrically connected to the adjacent connection pads 4 arranged at high density. It becomes easy to short-circuit. Therefore, it is preferable that the length of the solder extraction part 7 is 0.1 mm or more and 0.8 mm or less.
[0034]
The conductive pad 5 not only physically connects the wiring board 1 to the external electric circuit board 6 by using the solder 3 but also transmits a high-frequency electric signal to electrically connect the wiring board 1 and the external electric circuit board 6. Have a role to connect to. Further, as the material of the conductive pad 5, a material that easily wets the solder 3 and has a low conductive resistance value is required, and copper is generally used. Further, in order to improve the wettability with the solder 3, a metal having a thickness of 0.01 to 20 μm having a good wettability with the solder 3 may be deposited on the surface of the conductive pad 5 by a plating method.
[0035]
The conductive pad 5 is formed with a solder lead portion 8 that protrudes in the opposite direction to the solder lead portion 7 formed on the opposing connection pad 4.
[0036]
It is important that the protruding direction of the solder drawing portion 8 is opposite to the facing solder drawing portion 7. The electrical signal becomes straighter as the high frequency advances, and part of the transmitted signal is reflected or radiated at the part where the signal transmission path is bent at an angle of 90 degrees or less than 90 degrees, resulting in signal characteristics. Degradation occurs. Therefore, it is necessary that the solder lead-out portion 8 has an angle exceeding 90 degrees with respect to the solder lead-out portion 7, which is desirable in order to suppress transmission signal reflection and radiation and to minimize degradation of signal characteristics. It is desirable that the direction is 180 degrees different.
[0037]
The solder lead-out portion 8 is desirably formed on all the conductive pads 5 that input / output electric signals in order to transmit high-frequency electric signals with good characteristics.
[0038]
Regarding the size of the solder lead-out portion 8, when the width of the connection portion between the conductive pad 5 and the solder lead-out portion 8 is less than 0.04 mm, the solder 3 from the conductive pad 5 can be drawn out to the solder lead-out portion 8. It becomes difficult. On the other hand, when the thickness exceeds 0.2 mm, the amount of the solder 3 flowing out to the solder lead-out portion 8 is increased, and as a result, there is a problem in that the connection reliability is lowered due to the reduced mounting height of the wiring board 1. It becomes easy. Therefore, the length of the solder drawing portion 8 is preferably 0.1 mm or more and 0.8 mm or less for the same reason as the solder drawing portion 7 formed on the connection pad 4.
[0039]
The lengths and widths of the solder drawing portion 7 and the solder drawing portion 8 do not have to be the same. For example, the solder lead portion 7 and the solder lead portion 8 formed on the connection pad and the conduction pad in the outer peripheral corner portion where stress is concentrated should be as long and wide as possible in order to obtain high connection reliability. desirable.
[0040]
【Example】
Specific examples of the present invention are shown below.
[0041]
As the insulating substrate 1 a of the wiring substrate 1, one having an outer dimension of 13 mm × 13 mm, a thickness of 0.4 mm, and a material made of glass ceramics (dielectric constant ε = 5) was prepared.
[0042]
A wiring substrate 1 using these insulating substrates 1a was obtained by laminating and firing a green sheet having a wiring conductor 1b, an electrode pad 1d, a connection pad 4 and a solder lead-out portion 7 formed by a printing method.
[0043]
165 connection pads 4 having a diameter of 0.4 mm were formed on the lower surfaces of these wiring boards 1 in an arrangement as shown in FIG. In order to investigate the influence of the solder lead-out portion 7 on the transmission characteristics of the high-frequency electric signal, the solder lead-out portion 7 is formed only on the connection pad 4 that transmits the high-frequency electric signal, and each side of the outermost periphery of the connection pad 4 group. A total of four locations were placed, one at the center of each.
[0044]
Further, as the external electric circuit board 6, a copper wiring conductor 6a is formed on the upper surface of an insulating layer formed by impregnating a glass cloth with a fluororesin, and these insulating layers are laminated and then pressed and integrated. Formed. On the upper surface of the external electric circuit board 6, 165 conductive pads 5 having a diameter of 0.4 mm were formed at a pitch of 0.8 mm as shown in FIG. In order to investigate the influence of the solder lead-out portion 8 on the transmission characteristics of the high-frequency electric signal, the solder lead-out portion 8 is formed only on the conductive pad 5 that transmits the high-frequency electric signal, and each side of the outermost periphery of the conductive pad 5 group. A total of four locations were placed, one at the center of each.
[0045]
The solder lead-out part 7 and the solder lead-out part 8 were variously set between a length of 0 to 0.8 mm and a width of 0 mm to 0.4 mm in order to investigate the influence on the transmission characteristics of high-frequency electric signals.
[0046]
The wiring conductor 1b of the wiring substrate 1 electrically connects the electrode pad 1d on the upper surface of the wiring substrate 1 and the connection pad 4 on the lower surface. In this example, the width of the wiring conductor 1b on the upper surface of the wiring board 1 is 0.18 mm and the length is 3.0 mm. Further, the same-surface grounding conductor was formed on almost the entire upper surface of the wiring board 1 at a distance of 0.1 mm from the wiring conductor 1 b on the upper surface of the wiring board 1.
[0047]
Moreover, the wiring conductor 6a of the external electric circuit board 6 forms a copper wiring on a fluorine resin substrate, the width of the copper wiring is 0.26 mm, the length is 4.70 mm, and the distance from the copper wiring is 0.1 mm. The same surface ground conductor was formed.
[0048]
The surfaces of the wiring conductors 1b and 6a, the electrode pad 1d, the connection pad 4 on the lower surface of the wiring substrate 1 and the solder lead-out portion 7 were subjected to electroless Ni plating and electroless Au plating. The plating thicknesses are 2 μm and 0.1 μm, respectively.
[0049]
The wiring board 1 was connected to the external electric circuit board 6 using a solder paste of 37% by weight of tin and 63% by weight of lead to obtain a sample.
[0050]
Then, in order to evaluate the transmission characteristics of high-frequency electrical signals, the tip of the wiring conductor 1b on the top surface of the wiring board 1 and the tip of the copper wiring of the external electric circuit board 6 are connected to a network analyzer using a wafer probe as a connection medium. Then, the reflection loss S11 and the transmission loss S21 with respect to the high frequency electric signal were measured for each sample.
[0051]
Whether the transmission is good or not is determined by introducing a voltage reflection coefficient Γ = 0.18 and a voltage transmission coefficient T = 0.90, which are coefficient values required for high-frequency electrical signal transmission, into the following equation: The higher the frequency value of the electrical signal having the reflection loss S11 of −15 dB or less and the transmission loss S21 of −1.0 dB or more, the better. Note that the reflection loss S11 = −20log | Γ | and the transmission loss S21 = −20log | T |.
[0052]
Table 1 shows the measurement results.
[0053]
[Table 1]

[0054]
As apparent from Table 1, in order to transmit a higher frequency electrical signal without deteriorating the transmission characteristics of the high frequency electrical signal, the lengths of the solder lead portion 7 and the solder lead portion 8 are 0.1 mm or more and 0.8. It has been found that it is necessary to make the width less than mm, and that the width of the solder lead-out portion needs to be made 0.04 mm to 0.2 mm.
[0055]
That is, as can be seen from Sample No. 1 to Sample No. 5, an electrical signal of 46 GHz could be transmitted when the solder lead-out portion 7 and the solder lead-out portion 8 were not formed. An electrical signal having a frequency exceeding 46 GHz can be transmitted by setting the length of the lead-out portion 8 to 0.1 mm or more. In particular, when the length of the solder lead-out portion 7 and the solder lead-out portion 8 is 0.8 mm, the frequency is 62 GHz. It was possible to transmit the electrical signal.
[0056]
However, as shown in sample No. 6, when the length of the solder drawing portion 7 and the solder drawing portion 8 exceeded 1.0 mm, the solder flow out to the solder drawing portion 7 and the solder drawing portion 8 was not sufficient. Although it was difficult to transmit an electric signal having a frequency exceeding 62 GHz, it was possible to transmit an electric signal having a frequency lower than 62 GHz.
[0057]
Further, as can be seen from Sample No. 4 and Sample No. 7 to Sample No. 9, the width of the solder lead portion 7 and the solder lead portion 8 is set to 0.04 mm or more and 0.2 mm or less, so that the solder lead portion 7 and the solder lead portion are reduced. An electric signal having a frequency exceeding 46 GHz, which was a frequency value that could be transmitted when the section 8 was not provided, could be transmitted.
[0058]
However, as shown in Sample No. 10 and Sample No. 11, when the widths of the solder extraction portion 7 and the solder extraction portion 8 exceed 0.2 mm, it is difficult to transmit an electric signal having a frequency exceeding 46 GHz. However, good transmission was possible for electrical signals of lower frequency. This is because the area of the connection pad 4 and the conductive pad 5 is increased, a high stray capacitance is generated between the wiring board 1 and the ground layer of the external electric circuit board 6, and the impedance is rapidly changed. This is because the transmission characteristics have deteriorated.
[0059]
In addition, this invention is not limited to the example of said embodiment, A various change is possible if it is the range which does not deviate from the summary of this invention. For example, in the example of the embodiment described above, the shape of the solder lead-out

portions

7 and 8 is a substantially rectangular shape as shown in FIG. 2, but is a triangular shape, an elliptical shape or the like as shown in FIG. It doesn't matter. Also in this case, the width of the connection portion between the connection pad 4 and the conductive pad 5 is preferably set to 0.04 mm or more and 0.2 mm or less.
[0060]
In the example of the above embodiment, the method of mounting the wiring substrate 1 on the semiconductor element 2 is the wire bonding method, but a flip chip mounting method may also be used.
[0061]
【The invention's effect】
As described above, according to the mounting structure of the wiring board of the present invention, , Absolutely Edge board A semiconductor element is mounted on the top surface, On the bottom A wiring board having a connection pad for electrically connecting a semiconductor element and inputting / outputting an electric signal to / from an external electric circuit board is disposed with the connection pad and the conductive pad on the upper surface of the external electric circuit board facing each other. A wiring board mounting structure for mounting on an external electric circuit board by joining via solder, The connection pad has a solder lead-out that protrudes toward the center of the insulating substrate. Guidance Through pad is opposite Contact A solder lead-out part protruding in the opposite direction to the solder lead-out part of the connecting pad is formed A meniscus tail made of solder in opposite directions is formed by the respective solder lead portions of the connection pad and the conduction pad. Because , Mutual A meniscus tail is formed by soldering in the opposite direction. Have As a result, the connection part between the wiring board and the external electric circuit board has an inclined structure. Completion Ru Because In addition, it is possible to reduce the reflection / radiation loss of high-frequency electrical signals at the connection part, and to transmit high-frequency electrical signals with good transmission characteristics. Since the area can be secured sufficiently, the connection strength between the wiring board and the external electric circuit board by solder increases, and as a result, high connection reliability can be obtained. Can The
[0062]
In addition, when the length of the lead-out portion of the connection pad and the lead-out portion of the conductive pad is 0.1 mm or more and 0.8 mm or less and the width of the connection portion with each pad is 0.04 mm or more and 0.2 mm or less, the wiring board And a sufficient meniscus tail that can be formed into an inclined structure in the connection part of the external electric circuit board, and as a result, the reflection / radiation loss of high-frequency electrical signals at the connection part can be reduced, Can be transmitted with good transmission characteristics.
[0063]
According to the semiconductor device of the present invention , Absolutely A semiconductor element is mounted on the upper surface of the edge substrate, and the lower surface Half A wiring board having a connection pad for electrically connecting a conductor element and inputting / outputting an electric signal to / from an external electric circuit board is disposed with the connection pad and the conductive pad on the upper surface of the external electric circuit board facing each other. Join through solder Completion The connection pad is formed with a solder lead-out portion protruding toward the center of the insulating substrate, and the conductive pad is formed with a solder lead-out portion protruding in the opposite direction to the solder lead-out portion of the opposing connection pad Been A meniscus tail made of solder in opposite directions is formed by the respective solder lead portions of the connection pad and the conduction pad. Because , Mutual A meniscus tail is formed by soldering in the opposite direction. Have As a result, the connection part between the wiring board and the external electric circuit board has an inclined structure. Completion Ru Because Since it has a connection part that can reduce the reflection / radiation loss of high-frequency electric signals, and at the same time, the connection pad and the conductive pad can be opposed to ensure a sufficient area of these overlapping parts, The connection strength with the external electric circuit board is increased, and as a result, a semiconductor device having high connection reliability can be obtained.
[0064]
Further, according to the semiconductor device of the present invention, the length of the solder lead-out portion of the connection pad and the lead-out portion of the conductive pad is 0.1 mm or more and 0.8 mm or less, and the width of the connection portion with each pad is 0.04 mm or more. When the thickness is 0.2 mm or less, a sufficient meniscus tail that can form an inclined structure can be formed at the connection portion between the wiring board and the external electric circuit board, and at the same time, the wiring board and the external electric circuit can be reliably connected without being affected by mounting displacement. A semiconductor device with high connection reliability can be obtained because good conduction to a high-frequency electric signal can be ensured at a connection portion with the circuit board.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of an embodiment of a wiring board mounting structure according to the present invention.
FIGS. 2A to 2C show examples of connection pads of a wiring board and conduction pads of an external electric circuit board, respectively, constituting the semiconductor device of the present invention, and FIG. FIG. 4B is a plan view of the upper surface of the external electric circuit board, and FIG. 4C is a plan view of connection pads and conductive pads.
FIGS. 3A and 3B are plan views showing a wiring board and an external electric circuit board, respectively, in an embodiment of the present invention. FIGS.
FIGS. 4A to 4C are plan views showing other examples of connection pads of a wiring board and conduction pads of an external electric circuit board, respectively, constituting the semiconductor device of the present invention. FIGS.
FIG. 5 is a cross-sectional view showing an example of a conventional wiring board mounting structure;
[Explanation of symbols]
1 ... Wiring board
1a ・・ Insulating substrate
1b ... Wiring conductor of wiring board
1c ・・ Semiconductor element mounting part
1d ... Electrode pad
2 ... Semiconductor element
3 ... Solder
4. Connection pad
5 ... Conductive pad
6 ... External electric circuit board
6a ... Wiring conductor of external electric circuit board
7. Solder lead-out part of connection pad
8. Solder lead-out part of conductive pad
9. Metal thin wire

Claims

A wiring board having a semiconductor element mounted on an upper surface of an insulating substrate, and having a connection pad for inputting / outputting an electric signal to / from an external electric circuit board while the semiconductor element is electrically connected to a lower surface A mounting structure of a wiring board that is mounted on the external electric circuit board by bonding a pad and a conductive pad on the upper surface of the external electric circuit board facing each other via solder, wherein the connection pad is formed on the insulating board. central semi Tabiki unloading portion protruding toward the direction are formed, and the conductive pad is semi Tabiki unloading portion projecting in a direction opposite to the half Tabiki unloading portion of the connection pad that faces is formed, the connecting pad and the conductive A mounting structure of a wiring board, wherein a meniscus tail made of solder in opposite directions is formed by each of the solder drawing portions of the pad .

The solder lead-out part of the connection pad and the solder lead-out part of the conductive pad have a length of 0.1 mm or more and 0.8 mm or less, and the width of the connection part with each pad is 0.04 mm or more and 0.2 mm or less, The mounting structure of a wiring board according to claim 1 .

A wiring board having a semiconductor element mounted on an upper surface of an insulating substrate, and having a connection pad for inputting / outputting an electric signal to / from an external electric circuit board while the semiconductor element is electrically connected to a lower surface A semiconductor device comprising a pad and a conductive pad on the upper surface of the external electric circuit board facing each other and bonded via solder, wherein the connection pad is formed with a solder lead-out portion protruding toward the center of the insulating substrate And the conductive pad is formed with a solder lead portion that protrudes in a direction opposite to the solder lead portion of the connection pad facing each other, and the solder lead portions of the connection pad and the conductive pad are opposite to each other. A semiconductor device, characterized in that a meniscus tail is formed by solder .

The solder lead-out part of the connection pad and the solder lead-out part of the conductive pad have a length of 0.1 mm or more and 0.8 mm or less, and the width of the connection part with each pad is 0.04 mm or more and 0.2 mm or less, The semiconductor device according to claim 3.