JP2004259959A

JP2004259959A - Wiring board

Info

Publication number: JP2004259959A
Application number: JP2003049343A
Authority: JP
Inventors: Yoshihiro Nabe; 義博鍋
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2003-02-26
Filing date: 2003-02-26
Publication date: 2004-09-16

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that a high frequency signal cannot propagate through a signal wiring conductor and a signal through conductor correctly and thereby a mounted electronic component cannot operate normally. <P>SOLUTION: The wiring board is arranged such that the characteristic impedance between the signal through conductor 7 and a ground through conductor 11 is higher than the characteristic impedance between the first and third ground conductor layers 8 and 10 of a first signal wiring conductor 5 and the characteristic impedance between the second and third ground conductor layers 9 and 10 of a second signal wiring conductor 6. Furthermore, the characteristic impedance between the signal through conductor 7 and the third ground conductor 10 is lower than the characteristic impedance between the first and third ground conductor layers 8 and 10 of the first signal wiring conductor 5 and the characteristic impedance between the second and third ground conductor layers 9 and 10 of the second signal wiring conductor 6. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、高速作動の半導体素子等の電子部品を搭載するための配線基板に関する。
【０００２】
【従来の技術】
従来、半導体素子等の電子部品を搭載するための配線基板は、上面および／または下面に配線導体が配設された酸化アルミニウム質焼結体等の電気絶縁材料から成る多数の絶縁層を上下に積層することにより形成されている。そして、各絶縁層を挟んで上下に位置する配線導体同士を、絶縁層を貫通する貫通導体を介して接続することにより３次元配線を可能とし、これにより小型で高密度の配線基板を得るようになっている。
【０００３】
このような多層配線基板の例を図３に部分断面図で示す。
この例においては、中央の絶縁層２１の上下面にそれぞれ絶縁層２２・２３が積層されている。そして、中央の絶縁層２１の上下面には帯状の信号用配線導体２４・２５がそれぞれ互いの一端部を対向させるようにして配設されている。これらの信号用配線導体２４・２５は、絶縁層２１を貫通して設けられた信号用貫通導体２６により互いに電気的に接続されている。また、絶縁層２２の上面、絶縁層２３の下面にはそれぞれ広面積の接地用導体層２７・２８が配設されている。これらの接地用導体層２７・２８は絶縁層２１・２２・２３を貫通して信号用貫通導体２６に隣接するような配置で設けられた接地用貫通導体２９を介して互いに接続されている。
【０００４】
このような配線基板において、信号用配線導体２４・２５は、接地用導体層２７・２８との間の電磁カップリングにより、例えば５０Ωの特性インピーダンスとなるように設計されている。また、信号用貫通導体２６は、接地用貫通導体２９との間の電磁カップリングにより５０Ωの特性インピーダンスとなるように設計されている。
【０００５】
【特許文献１】
特開２０００−７７８０８号公報
【０００６】
【発明が解決しようとする課題】
しかしながら、近時は配線基板の高密度化に伴って、信号用貫通導体で互いに接続される上下の信号用配線導体間に複数の絶縁層が使用され、信号用貫通導体が複数の絶縁層を連続して貫通するように形成されるとともにそれらの絶縁層間に信号用貫通導体を取り囲む開口を有する接地用導体層が設けられることが多くなってきた。そのため、信号用貫通導体とこの信号用貫通導体を取り囲むように形成された接地用導体層との間において形成される大きな電磁カップリングにより、信号用貫通導体に局部的な特性インピーダンスの不整合部が発生するという問題点が発生してきた。このような特性インピーダンスの不整合は、信号用配線導体および信号用貫通導体に伝播される信号の周波数がそれほど高くない場合には、その影響を無視できるためにほとんど問題となることはないが、信号用配線導体および信号用貫通導体を伝播する信号の周波数が例えば１０ＧＨｚ以上の高周波になると、この特性インピーダンスの不整合部において信号が大きく反射するようになって問題となる。そのため、信号用配線導体および信号用貫通導体に所定の高周波信号を正確に伝播させることができず、配線基板に搭載される半導体素子等の電子部品を正常に作動させることができなくなるという問題を誘発していた。
【０００７】
本発明は、かかる従来技術の問題点に鑑み完成されたものであり、その目的は、信号用貫通導体とこの信号用貫通導体を取り囲むように開口が形成された接地用導体層との間に生じる電磁カップリングによる特性インピーダンスの不整合の影響を軽減することによって、信号用配線導体および信号用貫通導体に所定の高周波信号を正確に伝播させることができ、搭載する電子部品を正常に作動させることが可能な配線基板を提供することにある。
【０００８】
【課題を解決するための手段】
本発明の多層配線基板は、第１の絶縁層およびこの第１の絶縁層の下面に積層された第２の絶縁層と、前記第１の絶縁層の上面に配設された第１の信号用配線導体および前記第２の絶縁層の下面に配設された第２の信号用配線導体と、前記第１の絶縁層および前記第２の絶縁層を貫通して前記第１の信号用配線導体および前記第２の信号用配線導体を接続する信号用貫通導体と、前記第１の絶縁層の上面に積層された第３の絶縁層および前記第２の絶縁層の下面に積層された第４の絶縁層と、前記第３の絶縁層の上面に配設された第１の接地用導体層および前記第４の絶縁層の下面に配設された第２の接地用導体層ならびに前記第１および第２の絶縁層の間に配設され、前記信号用貫通導体を取り囲むように開口が形成された第３の接地用導体層と、前記信号用貫通導体に隣接して配置され、前記第１乃至第４の絶縁層を貫通して前記第１乃至第３の接地用導体層に接続された接地用貫通導体とを具備して成る配線基板であって、前記信号用貫通導体の前記接地用貫通導体との間の特性インピーダンスが前記第１の信号用配線導体の前記第１および第３の接地用導体層との間の特性インピーダンスならびに前記第２の信号用配線導体の前記第２および第３の接地用導体層との間の特性インピーダンスよりも大きく、かつ前記信号用貫通導体の前記第３の接地用導体層との間の特性インピーダンスが前記第１の信号用配線導体の前記第１および第３の接地用導体層との間の特性インピーダンスならびに第２の信号用配線導体の前記第２および第３の接地用導体層との間の特性インピーダンスよりも小さいことを特徴とするものである。
【０００９】
本発明の配線基板によれば、信号用貫通導体のこれと隣接して配設された接地用貫通導体との間の特性インピーダンスを、第１の信号用配線導体の第１および第３の接地用導体層との間の特性インピーダンスならびに第２の信号用配線導体の第２および第３の接地用導体層との間の特性インピーダンスよりも大きなものとし、かつ信号用貫通導体の第３の接地用導体層との間の特性インピーダンスを、第１の信号用配線導体の第１および第３の接地用導体層との間の特性インピーダンスならびに第２の信号用配線導体の第２および第３の接地用導体層との間の特性インピーダンスよりも小さいものとしたことから、第１の絶縁層と第２の絶縁層との間に信号用貫通導体を取り囲む開口を有する第３の接地用導体層を設けたにも拘わらず、信号用貫通導体の全体としてはその特性インピーダンスを信号用配線導体の特性インピーダンスに近似させることができ、信号用配線導体および信号用貫通導体を伝播する信号が例えば１０ＧＨｚ以上の高周波信号であったとしても信号用配線導体および信号用貫通導体を伝播する信号に大きな反射を起すことがなく、信号用配線導体および信号用貫通導体に所定の信号を正確に伝播させることができる。
【００１０】
【発明の実施の形態】
以下、本発明の多層配線基板について添付図面に基づき詳細に説明する。
図１（ａ）は本発明の配線基板の実施の形態の一例を示す部分断面図、図１（ｂ）は図１（ａ）に対応した部分上面図または部分下面図である。
図１（ａ）および（ｂ）に示す実施の形態の一例においては、第１の絶縁層１の下面に第２の絶縁層２を、第１の絶縁層の上面に第３の絶縁層３を、第２の絶縁層２の下面に第４の絶縁層４をそれぞれ積層一体化している。
【００１１】
第１の絶縁層１および第２の絶縁層２・第３の絶縁層３・第４の絶縁層４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等の無機材料またはエポキシ樹脂・ポリフェニレンエーテル（ＰＰＥ）・ビスマレイドトリアジン（ＢＴ）樹脂等の有機材料等の電気絶縁材料から形成されている。これら第１〜第４の絶縁層１〜４は、酸化アルミニウム質焼結体から成る場合であれば、酸化アルミニウム質焼結体等のセラミックスとなる原料粉末に適当なバインダおよび溶剤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に形成してそれぞれ第１の絶縁層１および第２の絶縁層２・第３の絶縁層３・第４の絶縁層４となるセラミックグリーンシートを得て、しかる後に、これら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所定の順に積層してセラミックグリーンシート積層体となし、最後にこのセラミックグリーンシート積層体を高温で焼成することによって上下に積層一体化される。
【００１２】
また、第１の絶縁層１の上面と第２の絶縁層２の下面にそれぞれ帯状の第１の信号用配線導体５および第２の信号用配線導体６が互いの一端部同士を対向させるようにして配設されている。
そして、これらの第１の信号用配線導体５と第２の信号用配線導体６とは、互いに対向する一端部間において第１の絶縁層１および第２の絶縁層２を貫通する信号用貫通導体７により互いに電気的に接続されている。
【００１３】
第１および第２の信号用配線導体５・６ならびに信号用貫通導体７は、配線基板に搭載される半導体素子等の電子部品に信号を入出力するための伝送路として機能し、これらにより例えば１０ＧＨｚ以上の高周波信号が伝播される。
【００１４】
また、第３の絶縁層３の上面および第４の絶縁層４の下面には、それぞれ広面積の第１の接地用導体層８および第２の接地用導体層９が配設されており、さらに第１の絶縁層１と第２の絶縁層２との間には第３の接地用導体層１０が配設されている。
これら第１の接地用導体層８と第２の接地用導体層９と第３の接地用導体層１０は、第１の絶縁層乃至第４の絶縁層１・２・３・４を貫通して信号用貫通導体７に隣接するような配置で設けられた接地用貫通導体１１でもって互いに電気的に接続されている。
【００１５】
第１乃至第３の接地用導体層８・９・１０ならびに接地用貫通導体１１は、配線基板に搭載される半導体素子等の電子部品に接地電位を提供するための導電路として機能し、外部の接地電位に電気的に接続される。
【００１６】
これら第１の信号配線導体５および第２の信号用配線導体６・信号用貫通導体７・第１の接地用導体層８・第２の接地用導体層９・第３の接地用導体１０・接地用貫通導体１１は、例えばタングステン粉末やモリブデン粉末・銀粉末・銅粉末・半田粉末等の金属粉末を焼結させた金属粉末メタライズや銅めっき・ニッケルめっき・金めっき等のめっき導体、あるいは銅粉末・銀粉末・半田粉末等の金属粉末と熱硬化性樹脂とを含有する導電性樹脂から成り、これらを金属粉末メタライズから形成する場合、信号用配線導体５・６あるいは接地用導体層８・９・１０であれば、タングステン粉末や銅粉末等の金属粉末に適当な有機バインダおよび溶剤を添加混合して得た導体ペーストを各絶縁層１・２・３・４となるセラミックグリーンシートの上面および／または下面に必要に応じて所定のパターンに印刷塗布しておき、また、信号用貫通導体７や接地用貫通導体１１であれば、各絶縁層１〜４となるセラミックグリーンシートの所定位置に予め貫通孔を設けておくとともに、この貫通孔内に前出の導体ペーストを充填し、これらの導体ペーストを各絶縁層１・２・３・４となるセラミックグリーンシートとともに焼成することによって所定の位置に所定のパターンに形成される。
【００１７】
そして、第１の信号用配線導体５は第１の接地用導体層８および第３の接地導体層１０との間の電磁カップリングにより、また第２の信号用配線導体６は第２の接地用導体層９および第３の接地用導体層１０との間の電磁カップリングによりその特性インピーダンスがそれぞれ例えば５０Ωとなるように設計されている。このような第１の信号用配線導体５および第２の信号用配線導体６の特性インピーダンスは、第１乃至第４の絶縁層１・２・３・４の厚みおよび誘電率、さらには第１および第２の信号用配線導体５・６の線路幅等により決定される。なお、第１の信号用配線導体５および第２の信号用配線導体６は、これらに信号を効率よく伝播させるためにその特性インピーダンスを４５〜５５Ωの範囲としておくことが好ましい。
【００１８】
また、第１の接地用導体層８および第２の接地用導体層９に対して、信号用貫通導体７と対向する領域に、信号用貫通導体７の断面積以上の面積の開口８ａ・９ａが形成されているとともに、第３の接地用導体層１０に対して信号用貫通導体７との絶縁を保つための開口１０ａが形成される。なお、開口８ａ・９ａ・１０ａは、例えば円柱状の信号用貫通導体７に対してその中心が信号用貫通導体７の中心軸と一致した円形である。
【００１９】
このように第１の接地用導体層８および第２の接地用導体層９に、信号用貫通導体７と対向する領域に開口８ａ・９ａを形成しておくと、第１の信号用配線導体５と信号用貫通導体７との接続部においては、第１の接地用導体層８との間の電磁カップリングが大きく減少する。同じく、第２の信号用配線導体６と信号用貫通導体７との接続部においては、第２の接地導体層９との間の電磁カップリングが大きく減少する。従って、これらの接続部においては殆どが接地用貫通導体７のみとの電磁カップリングとなり、電磁カップリングが大きくなり過ぎて過多となることがなく特性インピーダンスの不整合が大きく低減されるので、第１の接地用導体層８および第２の接地用導体層９には、信号用貫通導体７と対向する領域に開口８ａ・９ａを形成しておくことが好ましい。
【００２０】
なお、第１の接地用導体層８および第２の接地用導体層９に形成される開口８ａおよび９ａの大きさは、開口８ａ・９ａの直径をそれぞれＤ１およびＤ２とし、信号用貫通導体７の直径をＤ３・第３の絶縁層３の厚みをＴ１・第４の絶縁層４の厚みをＴ２としたとき、Ｄ１がＤ３より小さいものとなると、第１の信号用配線導体５と信号用貫通導体７との接続部と第１の接地用導体層８とが対向してしまうため、接続部での大きな電磁カップリングが発生し、これが接地用貫通導体１１との電磁カップリングと重畳してこの部分における特性インピーダンスの不整合が顕著となる傾向にある。また、Ｄ１がＤ３＋０．５Ｔ１より大きなものとなると、第１の信号用配線導体５と第１の接地用導体層８との電磁カップリングが小さいものとなるため、この部分で信号用配線導体５の特性インピーダンスが大きくなり、特性インピーダンスの不整合が発生し易くなってしまう傾向にある。
【００２１】
また同様に、Ｄ２がＤ３より小さいものとなると、第２の信号用配線導体６と信号用貫通導体７との接続部における第２の接地用導体層９とが対向してしまうため、接続部での大きな電磁カップリングが発生し、これが接地用貫通導体１１との電磁カップリングが重畳してこの部分において特性インピーダンスの不整合が顕著となる傾向にある。また、Ｄ２がＤ３＋０．５Ｔ２より大きなものとなると、第２の信号用配線導体６と第２の接地用導体層９との電磁カップリングが小さいものとなるため、この部分で信号用配線導体６の特性インピーダンスが大きくなり、特性インピーダンスの不整合が発生し易くなってしまう傾向にある。
【００２２】
従って、第１の接地用導体層８および第２の接地用導体層９に形成される開口８ａ・９ａの大きさは、開口８ａ・９ａの直径をそれぞれＤ１およびＤ２とし、信号用貫通導体７の直径をＤ３・第２の絶縁層３の厚みをＴ１・第４の絶縁層の厚みをＴ２としたとき、Ｄ３≦Ｄ１≦Ｄ３＋０．５Ｔ１、Ｄ３≦Ｄ２≦Ｄ３＋０．５Ｔ２の範囲であることが好ましい。
【００２３】
さらに、第１の絶縁層１と第２の絶縁層２との間に第３の接地用導体１０を設けることにより、第１の信号用配線導体５と第２の信号用配線導体６との間でのノイズ干渉を防ぐことができ、更に高周波特性を向上させることが可能となる。
【００２４】
なお、この場合、信号用貫通導体７は、第３の接地用導体層１０に形成された開口１０ａを貫通していることから信号用貫通導体７と第３の接地用導体層１０との間において電磁カップリングが大きくなる。したがって信号用貫通導体７の特性インピーダンスは第３の接地用導体層１０に形成された開口１０ａを貫通する領域において他の領域よりも小さなものとなる。この電磁カップリングは、第３の接地用導体層１０に形成された開口１０ａを大きくすることによって低減させることが可能であるが、配線スペースの関係から開口１０ａをあまり大きくすることはできない。
【００２５】
そこで本発明においては、信号用貫通導体７における接地用貫通導体１１との電磁カップリングによる特性インピーダンスを、第１の信号用配線導体５における第１および第３の接地用導体層８・１０との電磁カップリングによる特性インピーダンスならびに第２の信号用配線導体６における第２および第３の接地用導体層９・１０との電磁カップリングによる特性インピーダンスよりも大きくするとともに、信号用貫通導体７における第３の接地用導体層１０との電磁カップリングによる特性インピーダンスを、第１の信号用配線導体５における第１および第３の接地用導体層８・１０との電磁カップリングによる特性インピーダンスならびに第２の信号用配線導体６における第２および第３の接地用導体層９・１０との電磁カップリングによる特性インピーダンスよりも小さくしている。
【００２６】
このように、信号用貫通導体７における接地用貫通導体１１との電磁カップリングによる特性インピーダンスを、第１の信号用配線導体５における第１および第３の接地用導体層８・１０との電磁カップリングによる特性インピーダンスならびに第２の信号用配線導体６における第２および第３の接地用導体層９・１０との電磁カップリングによる特性インピーダンスよりも大きくするとともに、信号用貫通導体７における第３の接地用導体層１０との電磁カップリングによる特性インピーダンスを、第１の信号用配線導体５における第１および第３の接地用導体層８・１０との電磁カップリングによる特性インピーダンスならびに第２の信号用配線導体６における第２および第３の接地用導体層９・１０との電磁カップリングによる特性インピーダンスよりも小さくしていることから、第１の絶縁層１と第２の絶縁層２との間に信号用貫通導体７を取り囲む開口１０ａを有する第３の接地用導体層１０を設けたにも拘わらず、信号用貫通導体７の全体としてはその特性インピーダンスを第１および第２の信号用配線導体５・６の特性インピーダンスに近似させることができる。したがって、第１および第２の信号用配線導体５・６および信号用貫通導体７を伝播する信号が例えば１０ＧＨｚ以上の高周波信号であったとしても第１および第２の信号用配線導体５・６および信号用貫通導体７を伝播する信号に大きな反射を起すことがなく、第１および第２の信号用配線導体５・６および信号用貫通導体７に所定の信号を正確に伝播させることができる。
【００２７】
なお、信号用貫通導体７における接地用貫通導体１１との電磁カップリングによる特性インピーダンスが、第１の信号用配線導体５における第１および第３の接地用導体層８・１０との電磁カップリングによる特性インピーダンスならびに第２の信号用配線導体６における第２および第３の接地用導体層９・１０との電磁カップリングによる特性インピーダンス以下である場合、信号用貫通導体７の全体として特性インピーダンスが極めて小さいものとなり信号用貫通導体７の特性インピーダンスを第１および第２の信号用配線導体５・６の特性インピーダンスに近似させることができず、第１および第２の信号用配線導体５・６および信号用貫通導体７を伝播する信号が例えば１０ＧＨｚ以上の高周波信号であった場合に第１および第２の信号用配線導体５・６および信号用貫通導体７を伝播する信号に大きな反射が起こり、第１および第２の信号用配線導体５・６および信号用貫通導体７に所定の信号を正確に伝播させることができなくなる。したがって、信号用貫通導体７における接地用貫通導体１１との電磁カップリングによる特性インピーダンスは、第１の信号用配線導体５における第１および第３の接地用導体層８・１０との電磁カップリングによる特性インピーダンスならびに第２の信号用配線導体６における第２および第３の接地用導体層９・１０との電磁カップリングによる特性インピーダンスよりも大きくする必要がある。
【００２８】
また、信号用貫通導体７における接地用貫通導体１１との電磁カップリングによる特性インピーダンスが７５Ωを超えると、第１および第２の信号用配線導体５・６および信号用貫通導体７を伝播する信号が例えば３０ＧＨｚ以上の周波数帯域である場合に第１および第２の信号用配線導体５・６および信号用貫通導体７を伝播する信号の反射が大きくなり信号を良好に伝播させることが困難となる傾向にある。したがって、信号用貫通導体７における接地用貫通導体１１との電磁カップリングによる特性インピーダンスは７５Ω以下であることが好ましい。
【００２９】
他方、信号用貫通導体７における第３の接地用導体層１０との電磁カップリングによる特性インピーダンスが、第１の信号用配線導体５における第１および第３の接地用導体層８・１０との電磁カップリングによる特性インピーダンスならびに第２の信号用配線導体６における第２および第３の接地用導体層９・１０との電磁カップリングによる特性インピーダンス以上である場合、信号用貫通導体７の全体としての特性インピーダンスが極めて大きなものとなり信号用貫通導体７の特性インピーダンスを第１および第２の信号用配線導体５・６の特性インピーダンスに近似させることができなくなり、第１および第２の信号用配線導体５・６および信号用貫通導体７を伝播する信号が例えば１０ＧＨｚ以上の高周波信号であった場合に第１および第２の信号用配線導体５・６および信号用貫通導体７を伝播する信号に大きな反射が起こり、第１および第２の信号用配線導体５・６および信号用貫通導体７に所定の信号を正確に伝播させることができなくなる。したがって信号用貫通導体７における第３の接地用導体層１０との電磁カップリングによる特性インピーダンスは、第１の信号用配線導体５における第１および第３の接地用導体層８・１０との電磁カップリングによる特性インピーダンスならびに第２の信号用配線導体６における第２および第３の接地用導体層９・１０との電磁カップリングによる特性インピーダンスよりも小さい必要がある。
【００３０】
また、信号用貫通導体７における第３の接地用導体層１０との電磁カップリングによる特性インピーダンスが２５Ω未満であると、第１および第２の信号用配線導体５・６および信号用貫通導体７を伝播する信号が、例えば１０〜３０ＧＨｚの周波数帯域である場合に第１および第２の信号用配線導体５・６および信号用貫通導体７を伝播する信号の反射が大きくなり信号を良好に伝播させることが困難となる傾向にある。したがって、信号用貫通導体７における第３の接地用導体層１０との電磁カップリングによる特性インピーダンスは２５Ω以上であることが好ましい。
【００３１】
さらに、信号用貫通導体７に信号を効率よく伝達させるためには、信号用貫通導体７における接地用貫通導体１１との電磁カップリングによる特性インピーダンスをＺ１、信号用貫通導体７における第３の接地用導体層１０との電磁カップリングによる特性インピーダンスをＺ２とした場合に、両者の相加平均（Ｚ１＋Ｚ２）／２が４５Ω≦（Ｚ１＋Ｚ２）／２≦５５Ωの範囲であることが好ましい。
【００３２】
またさらに、第１の絶縁層１および第２の絶縁層２を貫通する信号用貫通導体７の長さＴ３は、信号用貫通導体７に伝送される高周波信号の波長の１／４未満であることが望ましい。Ｔ３が、波長の１／４以上となると、信号用貫通導体７において高周波信号の共振現象が発生し、高周波信号の伝送特性を劣化させる可能性がある。
【００３３】
なお、信号用貫通導体７と接地用貫通導体１１との間の特性インピーダンスは信号用貫通導体７や接地用貫通導体１１の径、信号用貫通導体７と接地用貫通導体１１との距離、接地用貫通導体１１の数等により調整することができ、信号用貫通導体７と第３の接地用導体層１０との間の特性インピーダンスは、信号用貫通導体の直径や接地用導体層１０の開口１０ａの大きさ等により調整することができる。
【００３４】
ところで、高周波信号には、伝達される信号の周波数以外にも多数の高調波成分が含まれているため、高周波信号の伝送特性を向上させるためには、広い周波数帯域で伝送損失を抑える必要がある。一般的には、伝播される高周波信号の３倍〜５倍の周波数帯域を考慮することが望ましい。
【００３５】
【実施例】
（実験例）上述の実施の形態例と同様の構造において、第１および第２の信号用配線導体５・６における第１乃至第３の接地用導体層８・９・１０との電磁カップリングによる特性インピーダンスを５０Ωとし、信号用貫通導体７における接地用貫通導体１１との電磁カップリングによる特性インピーダンスをＺ１、第３の接地用導体層１０との電磁カップリングによる特性インピーダンスをＺ２としたときの、第１および第２の信号用配線導体５・６間における信号の透過率の周波数特性を測定した。なお、絶縁層１・２・３・４としてはそれぞれ比誘電率が４．２（３．３ＧＨｚ）、誘電正接が０．００６１（３．３ＧＨｚ）で、厚みが９５μｍのものを用いた。また、信号用配線導体５・６および接地用導体８〜９としては、導電率が３．０×１０^７Ｓ／ｍで、厚みが１０μｍのものを用いた。また、信号用貫通導体７および接地用貫通導体１１としては、導電率が３．０×１０^７Ｓ／ｍで直径が１００μｍのものを使用した。なお、接地用貫通導体１１の数は４本とし、信号用貫通導体７に対して均等な間隔となるように配置した。また、第１と第２の接地用導体層８・９には、信号用貫通導体７に対向する領域に直径が１５０μｍの開口８ａ・１０ａを形成した。その結果を図２に示す。
【００３６】
図２に示すように、Ｚ１が信号用配線導体の特性インピーダンス以下の試料ＡおよびＺ２が信号用配線導体の特性インピーダンス以上の試料Ｃでは、１０ＧＨｚ以上の周波数帯域における信号の透過率が極めて悪いものとなった。それに対して、本発明の範囲内の試料であるＢおよびＤにおいては、１０ＧＨｚ以上の周波数帯域における信号の透過率が高く、特にＺ１が７５Ω以下、Ｚ２が２５Ω以上で、４５≦（Ｚ１＋Ｚ２）／２≦５５である試料Ｄおいては極めて優れることが分かった。
【００３７】
かくして本発明の配線基板によれば、第１の信号用配線導体５および第２の信号用配線導体６ならびに信号用貫通導体７に例えば周波数が１０ＧＨｚ以上の高周波信号を伝播させてもこの信号が大きく反射するようなことはなくなり、信号を正確に伝播させ、配線基板に搭載される半導体素子等の電子部品を正常に作動させることが可能となる。
【００３８】
なお、本発明は上述の実施の形態の一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、上述の実施の形態の一例では第１の接地導体層８および第２の接地用導体層９に形成された開口８ａ・９ａは円形であったが、開口８ａ・９ａは円形に限らず、例えば正方形、長方形状、菱形状、六角形状または八角形状等の形状などの多角形であってもよい。
【００３９】
また、第１乃至第４の絶縁層１・２・３・４は、それぞれ複数の絶縁層により形成されていてもよい。
あるいは、チップ抵抗，薄膜抵抗，コイルインダクタ，クロスインダクタ，チップコンデンサまたは電解コンデンサ等といったものを取着して多層配線基板を構成してもよい。
【００４０】
そして、このような本発明の配線基板は、半導体素子収納用パッケージ等の電子部品収納用パッケージや電子部品搭載用基板、多数の半導体素子が搭載されるいわゆるマルチチップモジュールやマルチチップパッケージ、あるいはマザーボード等として使用される。
【００４１】
【発明の効果】
本発明の配線基板によれば、信号用貫通導体のこれと隣接して配設された接地用貫通導体との間の特性インピーダンスを、第１の信号用配線導体の第１および第３の接地用導体層との間の特性インピーダンスならびに第２の信号用配線導体の第２および第３の接地用導体層との間の特性インピーダンスよりも大きなものとし、かつ信号用貫通導体の第３の接地用導体層との間の特性インピーダンスを、第１の信号用配線導体の第１および第３の接地用導体層との間の特性インピーダンスならびに第２の信号用配線導体の第２および第３の接地用導体層との間の特性インピーダンスよりも小さいものとしたことから、第１の絶縁層と第２の絶縁層との間に信号用貫通導体を取り囲む開口を有する第３の接地用導体層を設けたにも拘わらず、信号用貫通導体の全体としてはその特性インピーダンスを信号用配線導体の特性インピーダンスに近似させることができ、信号用配線導体および信号用貫通導体を伝播する信号が例えば１０ＧＨｚ以上の高周波信号であったとしても信号用配線導体および信号用貫通導体を伝播する信号に大きな反射を起すことがなく、信号用配線導体および信号用貫通導体に所定の信号を正確に伝播させることができる。
【図面の簡単な説明】
【図１】（ａ）は本発明の配線基板の実施の形態の一例を示す部分断面図であり、（ｂ）は（ａ）に対応する部分上面図または下面図である。
【図２】本発明における実験結果の一例である。
【図３】（ａ）は従来の配線基板を示す部分断面図であり、（ｂ）は対応する部分上面図または下面図である。
【符号の説明】
１・・・・・・第１の絶縁層
２・・・・・・第２の絶縁層
３・・・・・・第３の絶縁層
４・・・・・・第４の絶縁層
５・・・・・・第１の信号用配線導体
６・・・・・・第２の信号用配線導体
７・・・・・・信号用貫通導体
８・・・・・・第１の接地用導体層
９・・・・・・第２の接地用導体層
１０・・・・・・第３の接地用導体層
１１・・・・・・接地用貫通導体
８ａ、９ａ、１０ａ・・開口[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a wiring board for mounting an electronic component such as a semiconductor element that operates at a high speed.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a wiring board for mounting an electronic component such as a semiconductor element has a large number of insulating layers made of an electrically insulating material such as an aluminum oxide sintered body having a wiring conductor disposed on an upper surface and / or a lower surface. It is formed by stacking. Then, by connecting the wiring conductors located above and below each insulating layer via a through conductor penetrating the insulating layer, three-dimensional wiring is made possible, thereby obtaining a small and high-density wiring board. It has become.
[0003]
An example of such a multilayer wiring board is shown in FIG.
In this example, insulating layers 22 and 23 are respectively laminated on the upper and lower surfaces of the central insulating layer 21. Band-shaped signal wiring conductors 24 and 25 are disposed on the upper and lower surfaces of the central insulating layer 21 such that one ends of the signal wiring conductors 24 and 25 are opposed to each other. These signal wiring conductors 24 and 25 are electrically connected to each other by a signal through conductor 26 provided through the insulating layer 21. On the upper surface of the insulating layer 22 and on the lower surface of the insulating layer 23, ground conductor layers 27 and 28 having a large area are provided, respectively. These ground conductor layers 27 and 28 are connected to each other via a ground through conductor 29 provided so as to penetrate the insulating layers 21, 22 and 23 and to be adjacent to the signal through conductor 26.
[0004]
In such a wiring board, the signal wiring conductors 24 and 25 are designed to have a characteristic impedance of, for example, 50Ω by electromagnetic coupling between the signal wiring conductors 24 and 25 and the grounding conductor layers 27 and 28. The signal through conductor 26 is designed so as to have a characteristic impedance of 50Ω by electromagnetic coupling between the signal through conductor 26 and the ground through conductor 29.
[0005]
[Patent Document 1]
JP 2000-77808 A
[0006]
[Problems to be solved by the invention]
However, recently, as the density of the wiring board has increased, a plurality of insulating layers have been used between upper and lower signal wiring conductors connected to each other by signal through conductors, and the signal through conductor has a plurality of insulating layers. In many cases, a grounding conductor layer formed so as to continuously penetrate and having an opening surrounding the signal through conductor between the insulating layers has been provided. Therefore, due to the large electromagnetic coupling formed between the signal through conductor and the ground conductor layer formed so as to surround the signal through conductor, a local characteristic impedance mismatching portion is formed in the signal through conductor. A problem has arisen that a problem occurs. Such a characteristic impedance mismatch is not a problem since the effect can be ignored when the frequency of the signal propagated to the signal wiring conductor and the signal through conductor is not so high, If the frequency of a signal propagating through the signal wiring conductor and the signal through conductor becomes a high frequency of, for example, 10 GHz or more, the signal is largely reflected at the mismatched portion of the characteristic impedance, causing a problem. Therefore, a predetermined high-frequency signal cannot be accurately transmitted to the signal wiring conductor and the signal through conductor, and the electronic components such as semiconductor elements mounted on the wiring board cannot be normally operated. Was triggering.
[0007]
The present invention has been completed in view of the problems of the related art, and an object thereof is to provide a method between a signal through conductor and a grounding conductor layer having an opening formed to surround the signal through conductor. By reducing the influence of the characteristic impedance mismatch caused by the electromagnetic coupling, a predetermined high-frequency signal can be accurately propagated to the signal wiring conductor and the signal through conductor, and the mounted electronic components operate normally. It is to provide a wiring board capable of performing the above.
[0008]
[Means for Solving the Problems]
The multilayer wiring board according to the present invention includes a first insulating layer, a second insulating layer laminated on the lower surface of the first insulating layer, and a first signal disposed on the upper surface of the first insulating layer. A second signal wiring conductor disposed on the lower surface of the second wiring layer and the second signal line, and the first signal line penetrating the first and second insulating layers. A signal through conductor for connecting the conductor and the second signal wiring conductor; a third insulating layer laminated on the upper surface of the first insulating layer; and a third through layer laminated on the lower surface of the second insulating layer. 4th insulating layer, a first grounding conductor layer disposed on the upper surface of the third insulating layer, a second grounding conductor layer disposed on the lower surface of the fourth insulating layer, and A third grounding conductor disposed between the first and second insulating layers and having an opening formed to surround the signal through conductor; And a ground penetrating conductor disposed adjacent to the signal penetrating conductor and penetrating the first to fourth insulating layers and connected to the first to third ground conductor layers. Wherein the characteristic impedance between the signal penetrating conductor and the ground penetrating conductor is between the signal penetrating conductor and the first and third ground conductor layers of the first signal wiring conductor. And the characteristic impedance of the second signal wiring conductor between the second and third grounding conductor layers and the third grounding conductor layer of the signal through conductor. Characteristic impedance between the first signal wiring conductor and the first and third grounding conductor layers and the second signal wiring conductor for the second and third grounding. Characteristic impedance between conductor layer It is characterized in that less than Nsu.
[0009]
According to the wiring board of the present invention, the characteristic impedance between the signal penetrating conductor and the ground penetrating conductor arranged adjacent to the signal penetrating conductor is set to the first and third grounds of the first signal wiring conductor. Characteristic impedance between the second signal wiring conductor and the second and third grounding conductor layers, and the third grounding of the signal through conductor. The characteristic impedance between the first signal wiring conductor and the first and third grounding conductor layers and the second and third signal wiring conductors of the second signal wiring conductor. The third grounding conductor layer having an opening surrounding the signal through conductor between the first insulating layer and the second insulating layer because the characteristic impedance is smaller than the characteristic impedance between the third grounding conductor layer and the grounding conductor layer. Despite having provided the signal The characteristic impedance of the through conductor as a whole can be approximated to the characteristic impedance of the signal wiring conductor, and even if the signal propagating through the signal wiring conductor and the signal through conductor is a high-frequency signal of, for example, 10 GHz or more, The signal propagating through the wiring conductor for signal and the through conductor for signal does not cause large reflection, and a predetermined signal can be accurately propagated to the wiring conductor for signal and the through conductor for signal.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a multilayer wiring board of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1A is a partial sectional view showing an example of an embodiment of a wiring board according to the present invention, and FIG. 1B is a partial top view or a partial bottom view corresponding to FIG. 1A.
In the example of the embodiment shown in FIGS. 1A and 1B, the second insulating layer 2 is provided on the lower surface of the first insulating layer 1, and the third insulating layer 3 is provided on the upper surface of the first insulating layer. And the fourth insulating layer 4 is laminated and integrated on the lower surface of the second insulating layer 2 respectively.
[0011]
The first insulating layer 1, the second insulating layer 2, the third insulating layer 3, and the fourth insulating layer 4 are made of, for example, an inorganic material such as a sintered body of aluminum oxide or glass ceramic, or an epoxy resin or polyphenylene ether ( It is made of an electrically insulating material such as an organic material such as (PPE) and bismaleidotriazine (BT) resin. If the first to fourth insulating layers 1 to 4 are made of an aluminum oxide sintered body, a suitable binder and a solvent are added to and mixed with a raw material powder to be a ceramic such as an aluminum oxide sintered body. The first insulating layer 1 and the second insulating layer 2, the third insulating layer 3, and the fourth insulating layer 3 are formed in a sheet shape by employing a well-known doctor blade method. A ceramic green sheet to be an insulating layer 4 is obtained. Thereafter, these ceramic green sheets are subjected to appropriate punching and laminated in a predetermined order to form a ceramic green sheet laminate. Are fired at a high temperature to be vertically integrated.
[0012]
Further, strip-shaped first signal wiring conductors 5 and second signal wiring conductors 6 are formed on the upper surface of the first insulating layer 1 and the lower surface of the second insulating layer 2 so that one ends of the first and second signal wiring conductors face each other. It is arranged in.
The first signal wiring conductor 5 and the second signal wiring conductor 6 are arranged so that the signal penetrating through the first insulating layer 1 and the second insulating layer 2 between one end portions facing each other. They are electrically connected to each other by the conductor 7.
[0013]
The first and second signal wiring conductors 5 and 6 and the signal through conductor 7 function as transmission lines for inputting and outputting signals to and from electronic components such as semiconductor elements mounted on the wiring board. A high frequency signal of 10 GHz or more is propagated.
[0014]
On the upper surface of the third insulating layer 3 and on the lower surface of the fourth insulating layer 4, a first grounding conductor layer 8 and a second grounding conductor layer 9 having a large area are provided, respectively. Further, a third grounding conductor layer 10 is provided between the first insulating layer 1 and the second insulating layer 2.
The first grounding conductor layer 8, the second grounding conductor layer 9, and the third grounding conductor layer 10 penetrate the first to fourth insulating layers 1, 2, 3, and 4. Are electrically connected to each other by grounding through-conductors 11 provided so as to be adjacent to the signal through-conductors 7.
[0015]
The first to third conductor layers 8, 9, and 10 for grounding and the through conductor 11 for grounding function as a conductive path for providing a ground potential to an electronic component such as a semiconductor element mounted on the wiring board. Is electrically connected to the ground potential.
[0016]
These first signal wiring conductor 5 and second signal wiring conductor 6, signal through conductor 7, first grounding conductor layer 8, second grounding conductor layer 9, third grounding conductor 10, The grounding through conductor 11 is made of, for example, a metal powder metalized by sintering a metal powder such as tungsten powder, molybdenum powder, silver powder, copper powder, solder powder, or a plated conductor such as copper plating, nickel plating, gold plating, or copper. It is made of conductive resin containing metal powder such as powder, silver powder, solder powder and the like and thermosetting resin. When these are formed by metal powder metallization, signal wiring conductors 5 and 6 or grounding conductor layer 8. In the case of 9/10, a ceramic green sheet for forming each of the insulating layers 1, 2, 3, 4 is obtained by adding a suitable organic binder and a solvent to a metal powder such as a tungsten powder or a copper powder and mixing the resulting conductive paste. The upper surface and / or the lower surface may be printed and applied in a predetermined pattern as necessary. If the signal through conductor 7 or the ground through conductor 11 is used, the ceramic green sheet to be the insulating layers 1 to 4 may be used. A through-hole is provided in advance at a position, and the above-mentioned conductive paste is filled into the through-hole, and the conductive paste is fired together with the ceramic green sheets to be the insulating layers 1, 2, 3, and 4. A predetermined pattern is formed at a predetermined position.
[0017]
The first signal wiring conductor 5 is connected to the first ground conductor layer 8 and the third ground conductor layer 10 by electromagnetic coupling, and the second signal wiring conductor 6 is connected to the second ground conductor layer. The characteristic impedance is designed to be, for example, 50Ω by electromagnetic coupling between the conductor layer 9 for grounding and the third conductor layer 10 for grounding. The characteristic impedance of the first signal wiring conductor 5 and the second signal wiring conductor 6 depends on the thickness and the dielectric constant of the first to fourth insulating layers 1, 2, 3, and 4, and further, the first impedance. And the line width of the second signal wiring conductors 5 and 6. It is preferable that the characteristic impedance of the first signal wiring conductor 5 and the second signal wiring conductor 6 be set in a range of 45 to 55Ω in order to efficiently propagate a signal to the first signal wiring conductor 5 and the second signal wiring conductor 6.
[0018]
Also, with respect to the first grounding conductor layer 8 and the second grounding conductor layer 9, openings 8 a and 9 a having an area equal to or larger than the cross-sectional area of the signal through conductor 7 are provided in a region facing the signal through conductor 7. Are formed, and an opening 10a is formed for the third grounding conductor layer 10 to keep the signal through conductor 7 insulated. The openings 8a, 9a, and 10a are, for example, circular with the center of the cylindrical signal through conductor 7 coinciding with the central axis of the signal through conductor 7.
[0019]
When the openings 8a and 9a are formed in the first grounding conductor layer 8 and the second grounding conductor layer 9 in a region facing the signal through conductor 7, the first signal wiring conductor At the connection between the signal conductor 5 and the signal through conductor 7, the electromagnetic coupling between the first conductor layer 8 and the first ground conductor layer 8 is greatly reduced. Similarly, at the connection between the second signal wiring conductor 6 and the signal through conductor 7, the electromagnetic coupling between the second signal conductor 6 and the second ground conductor layer 9 is greatly reduced. Therefore, most of these connection portions are electromagnetic couplings with only the through conductor 7 for grounding, so that the electromagnetic coupling does not become too large to be excessive and characteristic impedance mismatch is greatly reduced. It is preferable that openings 8a and 9a are formed in the first grounding conductor layer 8 and the second grounding conductor layer 9 in a region facing the signal through conductor 7.
[0020]
The size of the openings 8a and 9a formed in the first grounding conductor layer 8 and the second grounding conductor layer 9 is such that the diameters of the openings 8a and 9a are D1 and D2, respectively, and the signal through conductor 7 When D1 is smaller than D3, where D3 is the diameter of D3, the thickness of the third insulating layer 3 is T1, and the thickness of the fourth insulating layer 4 is T2, the first signal wiring conductor 5 and the signal Since the connection part with the through conductor 7 and the first grounding conductor layer 8 face each other, large electromagnetic coupling occurs at the connection part, and this is superimposed on the electromagnetic coupling with the grounding conductor 11. The characteristic impedance mismatch at the lever tends to be significant. When D1 is larger than D3 + 0.5T1, the electromagnetic coupling between the first signal wiring conductor 5 and the first grounding conductor layer 8 becomes small, and thus the signal wiring conductor 5 Characteristic impedance increases, and the characteristic impedance tends to be easily mismatched.
[0021]
Similarly, if D2 is smaller than D3, the second grounding conductor layer 9 in the connection portion between the second signal wiring conductor 6 and the signal through conductor 7 will face each other. Large electromagnetic coupling occurs, which is superimposed on the electromagnetic coupling with the through conductor 11 for grounding, and the characteristic impedance mismatch tends to be remarkable in this portion. If D2 is larger than D3 + 0.5T2, the electromagnetic coupling between the second signal wiring conductor 6 and the second grounding conductor layer 9 becomes small, so that the signal wiring conductor 6 Characteristic impedance increases, and the characteristic impedance tends to be easily mismatched.
[0022]
Therefore, the size of the openings 8a, 9a formed in the first grounding conductor layer 8 and the second grounding conductor layer 9 is such that the diameters of the openings 8a, 9a are D1 and D2, respectively, and the signal through conductor 7 Where D3 is the diameter of D3, the thickness of the second insulating layer 3 is T1, and the thickness of the fourth insulating layer is T2, the range may be D3 ≦ D1 ≦ D3 + 0.5T1, and D3 ≦ D2 ≦ D3 + 0.5T2. preferable.
[0023]
Further, by providing a third grounding conductor 10 between the first insulating layer 1 and the second insulating layer 2, the first signal wiring conductor 5 and the second signal wiring conductor 6 Noise interference between them can be prevented, and high-frequency characteristics can be further improved.
[0024]
In this case, since the signal through conductor 7 penetrates through the opening 10a formed in the third grounding conductor layer 10, the signal through conductor 7 and the third grounding conductor layer 10 , The electromagnetic coupling increases. Therefore, the characteristic impedance of the signal through conductor 7 is smaller in a region penetrating the opening 10a formed in the third grounding conductor layer 10 than in other regions. This electromagnetic coupling can be reduced by enlarging the opening 10a formed in the third grounding conductor layer 10, but the opening 10a cannot be made too large due to the wiring space.
[0025]
Therefore, in the present invention, the characteristic impedance of the signal through conductor 7 due to the electromagnetic coupling with the ground through conductor 11 is compared with the first and third ground conductor layers 8 and 10 in the first signal wiring conductor 5. And the characteristic impedance of the second signal wiring conductor 6 due to the electromagnetic coupling with the second and third grounding conductor layers 9 and 10, and the characteristic impedance of the signal through conductor 7 The characteristic impedance of the first signal wiring conductor 5 due to the electromagnetic coupling with the first and third grounding conductor layers 8 and 10 and the characteristic impedance of the first signal wiring conductor 5 due to the electromagnetic coupling with the third grounding conductor layer 10 are determined. Coupling between the second signal wiring conductor 6 and the second and third grounding conductor layers 9 and 10 It is smaller than with the characteristic impedance.
[0026]
As described above, the characteristic impedance of the signal through conductor 7 due to the electromagnetic coupling with the ground through conductor 11 is changed by the electromagnetic coupling between the first and third ground conductor layers 8 and 10 of the first signal wiring conductor 5. The characteristic impedance due to the coupling and the characteristic impedance due to the electromagnetic coupling between the second signal wiring conductor 6 and the second and third grounding conductor layers 9 and 10 are set to be larger than the characteristic impedance due to the coupling. The characteristic impedance of the first signal wiring conductor 5 due to the electromagnetic coupling with the first and third grounding conductor layers 8 and 10 and the characteristic impedance due to the electromagnetic coupling with the grounding conductor layer 10 and the second Characteristics of the signal wiring conductor 6 due to electromagnetic coupling with the second and third grounding conductor layers 9 and 10 Since the impedance is smaller than the impedance, the third grounding conductor layer 10 having the opening 10a surrounding the signal through conductor 7 is provided between the first insulating layer 1 and the second insulating layer 2. Nevertheless, the characteristic impedance of the signal through conductor 7 as a whole can be approximated to the characteristic impedance of the first and second signal wiring conductors 5 and 6. Therefore, even if the signal propagating through the first and second signal wiring conductors 5 and 6 and the signal through conductor 7 is a high-frequency signal of, for example, 10 GHz or more, the first and second signal wiring conductors 5.6 In addition, a predetermined signal can be accurately propagated to the first and second signal wiring conductors 5 and 6 and the signal through conductor 7 without causing large reflection on the signal propagating through the signal through conductor 7. .
[0027]
Note that the characteristic impedance of the signal through conductor 7 due to the electromagnetic coupling with the ground through conductor 11 is different from the electromagnetic coupling between the first signal wiring conductor 5 and the first and third ground conductor layers 8 and 10. And the characteristic impedance due to the electromagnetic coupling of the second signal wiring conductor 6 with the second and third grounding conductor layers 9 and 10 is equal to or less than the characteristic impedance of the signal through conductor 7 as a whole. It becomes extremely small, and the characteristic impedance of the signal through conductor 7 cannot be approximated to the characteristic impedance of the first and second signal wiring conductors 5, 6, and the first and second signal wiring conductors 5, 6 When the signal propagating through the signal through conductor 7 is a high-frequency signal of, for example, 10 GHz or more, the first and second A large reflection occurs in the signal propagating through the signal wiring conductors 5.6 and the signal through conductor 7, and a predetermined signal is accurately transmitted to the first and second signal wiring conductors 5.6 and the signal through conductor 7. You can not let it. Therefore, the characteristic impedance of the signal through conductor 7 due to the electromagnetic coupling with the ground through conductor 11 is equal to the electromagnetic coupling between the first signal wiring conductor 5 and the first and third ground conductor layers 8 and 10. And the characteristic impedance due to electromagnetic coupling between the second signal wiring conductor 6 and the second and third grounding conductor layers 9 and 10.
[0028]
When the characteristic impedance of the signal through conductor 7 due to the electromagnetic coupling with the ground through conductor 11 exceeds 75Ω, the signal propagating through the first and second signal wiring conductors 5.6 and the signal through conductor 7. Is in a frequency band of, for example, 30 GHz or more, the reflection of a signal propagating through the first and second signal wiring conductors 5.6 and the signal through conductor 7 becomes large, and it becomes difficult to propagate the signal well. There is a tendency. Therefore, the characteristic impedance of the signal through conductor 7 due to the electromagnetic coupling with the ground through conductor 11 is preferably 75Ω or less.
[0029]
On the other hand, the characteristic impedance of the signal through conductor 7 due to the electromagnetic coupling with the third grounding conductor layer 10 is different from that of the first and third grounding conductor layers 8 and 10 in the first signal wiring conductor 5. If the characteristic impedance due to the electromagnetic coupling and the characteristic impedance due to the electromagnetic coupling between the second signal wiring conductor 6 and the second and third grounding conductor layers 9 and 10 are equal to or higher than the characteristic impedance, the signal through conductor 7 as a whole Becomes very large, and the characteristic impedance of the signal through conductor 7 cannot be approximated to the characteristic impedance of the first and second signal wiring conductors 5 and 6, so that the first and second signal wiring When the signal propagating through the conductors 5 and 6 and the signal through conductor 7 is a high frequency signal of, for example, 10 GHz or more, the first A large reflection occurs in the signals propagating through the first and second signal wiring conductors 5 and 6 and the signal through conductor 7, and a predetermined signal is applied to the first and second signal wiring conductors 5 and 6 and the signal through conductor 7. Cannot be propagated accurately. Therefore, the characteristic impedance of the signal through conductor 7 due to the electromagnetic coupling with the third grounding conductor layer 10 depends on the electromagnetic coupling between the first and third grounding conductor layers 8 and 10 of the first signal wiring conductor 5. It must be smaller than the characteristic impedance due to the coupling and the characteristic impedance due to the electromagnetic coupling between the second signal wiring conductor 6 and the second and third grounding conductor layers 9 and 10.
[0030]
If the characteristic impedance of the signal through conductor 7 due to the electromagnetic coupling with the third grounding conductor layer 10 is less than 25Ω, the first and second signal wiring conductors 5 and 6 and the signal through conductor 7 When the signal propagating through the signal is in a frequency band of, for example, 10 to 30 GHz, the reflection of the signal propagating through the first and second signal wiring conductors 5 and 6 and the signal penetrating conductor 7 increases, and the signal propagates favorably. Tends to be difficult. Therefore, the characteristic impedance of the signal through conductor 7 due to the electromagnetic coupling with the third grounding conductor layer 10 is preferably 25Ω or more.
[0031]
Further, in order to efficiently transmit a signal to the signal through conductor 7, the characteristic impedance of the signal through conductor 7 due to the electromagnetic coupling with the ground through conductor 11 is set to Z1, and the third ground of the signal through conductor 7 is set to Z1. When the characteristic impedance due to the electromagnetic coupling with the conductor layer 10 is Z2, it is preferable that the arithmetic mean (Z1 + Z2) / 2 of both is in the range of 45Ω ≦ (Z1 + Z2) / 2 ≦ 55Ω.
[0032]
Furthermore, the length T3 of the signal through conductor 7 penetrating the first insulating layer 1 and the second insulating layer 2 is less than １／ of the wavelength of the high frequency signal transmitted to the signal through conductor 7. It is desirable. When T3 is １／ or more of the wavelength, a resonance phenomenon of a high-frequency signal occurs in the signal penetrating conductor 7, and there is a possibility that the transmission characteristic of the high-frequency signal is deteriorated.
[0033]
The characteristic impedance between the signal penetrating conductor 7 and the ground penetrating conductor 11 depends on the diameter of the signal penetrating conductor 7 and the ground penetrating conductor 11, the distance between the signal penetrating conductor 7 and the ground penetrating conductor 11, the grounding. The characteristic impedance between the signal through conductor 7 and the third grounding conductor layer 10 can be adjusted by the number of the through conductors 11 for signal transmission and the like. It can be adjusted by the size of 10a or the like.
[0034]
By the way, since a high-frequency signal contains many harmonic components in addition to the frequency of the transmitted signal, it is necessary to suppress transmission loss in a wide frequency band in order to improve the transmission characteristics of the high-frequency signal. is there. In general, it is desirable to consider a frequency band that is three to five times the frequency of the propagated high-frequency signal.
[0035]
【Example】
(Experimental Example) In the same structure as the above-described embodiment, electromagnetic coupling between the first and third grounding conductor layers 8, 9, and 10 in the first and second signal wiring conductors 5, 6 is performed. Is 50Ω, the characteristic impedance of the signal through conductor 7 due to electromagnetic coupling with the grounding through conductor 11 is Z1, and the characteristic impedance due to electromagnetic coupling with the third grounding conductor layer 10 is Z2. The frequency characteristics of the signal transmittance between the first and second signal wiring conductors 5 and 6 were measured. The insulating layers 1, 2, 3, and 4 each had a relative dielectric constant of 4.2 (3.3 GHz), a dielectric loss tangent of 0.0061 (3.3 GHz), and a thickness of 95 μm. The signal wiring conductors 5 and 6 and the grounding conductors 8 to 9 have a conductivity of 3.0 × 10 ⁷ S / m having a thickness of 10 μm was used. The signal through conductor 7 and the ground through conductor 11 have a conductivity of 3.0 × 10 ⁷ S / m having a diameter of 100 μm was used. The number of the through conductors 11 for grounding was set to four, and they were arranged so as to be evenly spaced from the through conductors 7 for signal. In the first and second grounding conductor layers 8 and 9, openings 8 a and 10 a having a diameter of 150 μm were formed in regions facing the signal through conductors 7. The result is shown in FIG.
[0036]
As shown in FIG. 2, in samples A and Z in which Z1 is equal to or lower than the characteristic impedance of the signal wiring conductor and Z2 is equal to or higher than the characteristic impedance of the signal wiring conductor, the signal transmittance in a frequency band of 10 GHz or more is extremely poor. It became. On the other hand, in the samples B and D within the scope of the present invention, the signal transmittance in the frequency band of 10 GHz or more is high, particularly when Z1 is 75Ω or less, Z2 is 25Ω or more, and 45 ≦ (Z1 + Z2) / It was found that Sample D where 2 ≦ 55 was extremely excellent.
[0037]
Thus, according to the wiring board of the present invention, even when a high-frequency signal having a frequency of, for example, 10 GHz or more is propagated to the first signal wiring conductor 5, the second signal wiring conductor 6, and the signal through conductor 7, There is no large reflection, so that signals can be accurately propagated, and electronic components such as semiconductor elements mounted on the wiring board can be normally operated.
[0038]
The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.
For example, in the example of the above-described embodiment, the openings 8a and 9a formed in the first grounding conductor layer 8 and the second grounding conductor layer 9 are circular, but the openings 8a and 9a are not limited to circular. For example, the shape may be a polygon such as a square, a rectangle, a diamond, a hexagon, or an octagon.
[0039]
Further, each of the first to fourth insulating layers 1, 2, 3, 4 may be formed of a plurality of insulating layers.
Alternatively, a multilayered wiring board may be configured by attaching a chip resistor, a thin film resistor, a coil inductor, a cross inductor, a chip capacitor, an electrolytic capacitor, or the like.
[0040]
Such a wiring board according to the present invention includes a package for storing electronic components such as a package for storing semiconductor elements, a substrate for mounting electronic components, a so-called multi-chip module or multi-chip package on which a large number of semiconductor elements are mounted, or a motherboard. Used as etc.
[0041]
【The invention's effect】
According to the wiring board of the present invention, the characteristic impedance between the signal penetrating conductor and the ground penetrating conductor arranged adjacent to the signal penetrating conductor is set to the first and third grounds of the first signal wiring conductor. Characteristic impedance between the second signal wiring conductor and the second and third grounding conductor layers, and the third grounding of the signal through conductor. The characteristic impedance between the first signal wiring conductor and the first and third grounding conductor layers and the second and third signal wiring conductors of the second signal wiring conductor. The third grounding conductor layer having an opening surrounding the signal through conductor between the first insulating layer and the second insulating layer because the characteristic impedance is smaller than the characteristic impedance between the third grounding conductor layer and the grounding conductor layer. Despite having provided the signal The characteristic impedance of the entire through conductor can be approximated to the characteristic impedance of the signal wiring conductor. Even if the signal propagating through the signal wiring conductor and the signal through conductor is a high-frequency signal of, for example, 10 GHz or more, The signal propagating through the wiring conductor for signal and the through conductor for signal does not cause large reflection, and a predetermined signal can be accurately propagated to the wiring conductor for signal and the through conductor for signal.
[Brief description of the drawings]
FIG. 1A is a partial cross-sectional view illustrating an example of an embodiment of a wiring board according to the present invention, and FIG. 1B is a partial top view or a bottom view corresponding to FIG.
FIG. 2 is an example of an experimental result in the present invention.
3A is a partial cross-sectional view showing a conventional wiring board, and FIG. 3B is a corresponding partial top view or bottom view.
[Explanation of symbols]
1... First insulating layer
2 Second insulating layer
3... Third insulating layer
4... Fourth insulating layer
5... First signal wiring conductor
6... Second signal wiring conductor
7 ... Through conductor for signal
8 First grounding conductor layer
9 second conductive layer for grounding
10... Third grounding conductor layer
11 ... Through conductor for grounding
8a, 9a, 10a ... opening

Claims

A first insulating layer, a second insulating layer laminated on a lower surface of the first insulating layer, a first signal wiring conductor disposed on an upper surface of the first insulating layer, and the second insulating layer. A second signal wiring conductor disposed on a lower surface of the insulating layer; and a first signal wiring conductor and the second signal wiring penetrating the first insulating layer and the second insulating layer. A signal through conductor for connecting a wiring conductor, a third insulating layer laminated on an upper surface of the first insulating layer, a fourth insulating layer laminated on a lower surface of the second insulating layer, A first grounding conductor layer disposed on the upper surface of the third insulating layer, a second grounding conductor layer disposed on the lower surface of the fourth insulating layer, and the first and second insulating layers. A third grounding conductor layer disposed between and having an opening formed to surround the signal through conductor; and the signal through conductor. A wiring substrate comprising: a grounding penetrating conductor disposed adjacent to and penetrating the first to fourth insulating layers and connected to the first to third grounding conductor layers, The characteristic impedance between the signal penetrating conductor and the ground penetrating conductor is the characteristic impedance between the first signal wiring conductor and the first and third ground conductor layers and the second signal. The characteristic impedance between the signal wiring conductor and the third grounding conductor layer is greater than the characteristic impedance between the second and third grounding conductor layers, and Characteristic impedance between the first signal wiring conductor and the first and third grounding conductor layers and the characteristic impedance between the second signal wiring conductor and the second and third grounding conductor layers. It is especially small Wiring board to be.