【０００１】
【発明の属する技術分野】
本発明は、半導体素子等の電子部品を搭載するための配線基板およびその配線基板に電子部品を搭載して成る電子装置に関するものである。
【０００２】
【従来の技術】
一般に、移動体通信機器に代表されるような電子機器の小型化や薄型化の要求に伴い、このような電子機器に使用される半導体素子等の電子部品を搭載するための配線基板にも小型化や薄型化、多端子化が求められてきている。そして、そのような小型化や薄型化、多端子化を実現するための配線基板として、外部電気回路基板上に半田バンプを介して表面実装可能としたボールグリッドアレイパッケージ用の配線基板が実用化されている。
【０００３】
このボールグリッドアレイパッケージ用の配線基板は、複数の絶縁層を積層して成る絶縁基板の上面に電子部品の電極が半田を介して接続される直径が５０〜１００μｍ程度の数百から数千個の電子部品接続用の電極パッドが格子状の並びに配列形成されるとともに、この絶縁基板の下面に外部電気回路基板の配線導体に半田を介して接続される直径が２００〜５００μｍ程度の数百〜数千個の外部接続用の電極パッドが格子状の並びの配列形成されている。そして、各絶縁層の間に配線導体用の複数の導体層が配設されるとともに、各絶縁層を挟んで上下に位置する導体層同士の間および導体層と電極パッドとの間が絶縁層を貫通して設けられた直径が３０〜２００μｍ程度の貫通導体により接続されることにより電子部品接続用の電極パッドと外部接続用の電極パッドとが互いに電気的に接続されている。
【０００４】
なお、このような配線基板は、例えばガラスクロスに未硬化の熱硬化性樹脂を含浸させた絶縁層用の絶縁シートにレーザ加工により貫通導体形成用の貫通孔を穿孔し、次にこの貫通孔内に未硬化の熱硬化性樹脂と金属粉末とを混合した貫通導体用の金属ペーストを充填するとともに絶縁シートの表面に所定パターンに形成された配線導体用の導体層を被着させ、次に導体層が被着された複数の絶縁シートを上下に積層するとともに上下から加圧しながら加熱することにより絶縁シートおよび金属ペースト中の熱硬化性樹脂を熱硬化させることにより製作される。
【０００５】
そして、この配線基板は、電子部品接続用の電極パッドと電子部品の電極とが半田を介して接続されるようにして電子部品が搭載されることにより電子装置となり、この電子装置は、その外部接続用の電極パッドと外部電気回路基板の配線導体とが半田を介して接続されることにより外部電気回路基板上に実装されるとともに搭載された電子部品が外部電気回路に電気的に接続されることとなる。
【０００６】
なお、このような配線基板における配線導体は、用途によって信号用と接地用と電源用の配線導体に機能化されている。
【０００７】
このうち信号用の配線導体は、半導体素子等の電子部品と外部電気回路基板との間で電気信号を伝播させるための導電路として機能し、一般的に細い帯状であり、複数の絶縁層を貫通する貫通導体によりこれに対応する電子部品接続用の電極パッドおよび外部接続用の電極パッドに接続されている。
【０００８】
また、接地用の配線導体や電源用の配線導体は、配線基板に搭載される電子部品にそれぞれ接地電位や電源電位を供給する供給路としての機能を有しているとともに信号用の配線導体に対する電磁シールド機能や特性インピーダンスの調整機能を有しており、信号用の配線導体に対向する広面積の導体層を絶縁層間に有するとともに、絶縁層を貫通する貫通導体によりそれぞれこれらに対応する電子部品接続用の電極パッドおよび外部接続用の電極パッドに接続されている。
【０００９】
しかしながら、このような配線基板においては、絶縁基板の絶縁層間に広面積の接地用または電源用の導体層が設けられていることから、この広面積の接地用または電源用の導体層と信号用の外部接続用の電極パッドとの間に大きなキャパシタンスが発生し、それにより、信号用の配線導体に反射ノイズが発生して、配線基板に搭載した電子部品に誤動作が発生してしまうという問題点を有していた。そこで、このような問題点を解決するために特許文献１には、信号用の外部接続用の電極パッドに対応する領域の接地用または電源用の導体層に信号用の外部接続用の電極パッドより大きな円形の開口部を設けることが提案されている。このような開口部を設けることにより信号用の外部接続用の電極パッドと接地用または電源用の導体層との間に形成されるキャパシタンスを低減させている。
【００１０】
【特許文献１】
特開２００３−７８０６５号公報
【００１１】
【発明が解決しようとする課題】
しかしながら、特許文献１に提案されているように、信号用の外部接続用の電極パッドに対応する領域の接地用または電源用の導体層に信号用の外部接続用の電極パッドよりも大きな開口部を設けると、開口部内における樹脂の占める比率が大きくなってしまう。このように開口部内における樹脂の占める比率が大きくなると、この配線基板を製作するために絶縁層用の絶縁シートを積層して上下から加圧しながら加熱する際に、開口部内の剛性が低下して開口部内の樹脂が上下からの加圧および加熱により大きく変形してしまい、その結果、開口部に対応する絶縁基板の表面に大きな凹みが発生してしまう。そして、このような凹みが発生すると、配線基板に電子部品を搭載する際に電子部品を良好に搭載することができなくなったり、あるいは配線基板に電子部品が搭載された電子装置を外部電気回路基板に実装する際に電子装置を良好に実装することができなくなったりするという問題点を有していた。
【００１２】
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、信号用の外部接続用の電極パッドに対応する領域の接地用または電源用の導体層に信号用の外部接続用の電極パッドよりも大きな開口部を設けたとしても、その開口部に対応する絶縁基板の表面に大きな凹みが発生することがなく、それにより電子部品を良好に搭載することができる配線基板を提供するとともに外部電気回路基板に良好に実装することが可能な電子装置を提供することにある。
【００１３】
【課題を解決するための手段】
本発明の配線基板は、複数の絶縁層が積層されて成る絶縁基板と、複数の前記絶縁層を貫通して設けられた貫通導体と、該貫通導体が貫通する前記複数の絶縁層の間に配設されているとともに前記貫通導体を取り囲む開口部を有する導体層とを具備して成る配線基板であって、前記開口部内に前記貫通導体および前記導体層から電気的に独立した導体パターンが前記貫通導体を取り囲むようにして配設されていることを特徴とするものである。
【００１４】
本発明の配線基板によれば、上記構成としたことから、貫通導体を取り囲む開口部内における樹脂の占める比率が導体パターンにより小さくなり、配線基板を製作するために絶縁層用の絶縁シートを積層して上下から加圧しながら加熱しても開口部内の剛性が大きく低下することはなく、開口部内の樹脂が上下からの加圧および加熱により大きく変形して開口部に対応する絶縁基板の表面に大きな凹みが発生することはない。
【００１５】
また、本発明の配線基板によれば、前記導体パターンが前記貫通導体を取り囲む環状であると、貫通導体の周囲の全周にわたり均一に導体パターンが配置され、それにより貫通導体を取り囲む開口部に対応する絶縁基板表面の凹みが極めて良好に防止される。
【００１６】
また、本発明の配線基板によれば、前記貫通導体を伝播する信号が周波数１０ＧＨｚ以上の高周波信号である場合に、前記導体パターンが前記高周波信号の波長の４分の１未満の長さの互いに電気的に独立した複数の導体片を前記貫通導体を取り囲む環状の並びに配列したものであると、前記導体パターン内で高周波信号の共振が発生することが有効に防止され、それにより１０ＧＨｚ以上の高周波信号を極めて効率良く伝播させることができる。
【００１７】
さらに、本発明の配線基板によれば、上記のように前記導体パターンが高周波信号の波長の４分の１未満の長さの互いに電気的に独立した複数の導体片を貫通導体を取り囲む環状の並びに配列したものであり、かつ前記導体層および前記導体パターンが前記貫通導体に対して前記絶縁層を挟んで上下に複数層配設されている場合に、前記導体片の位置が上下の導体パターン同士で環状の並びの周方向に互いにずれていると、貫通導体の周囲に導体片が満遍なく配置されて開口部内の樹脂の変形がより効果的に防止される。
【００１８】
また、本発明の配線基板によれば、前記貫通導体の一端に帯状の配線導体が接続されている場合に、該配線導体が前記絶縁層を挟んで前記導体パターンと対向する領域を横切るように前記絶縁層の表面に延びていると、開口部内に対応する領域における配線導体の特性インピーダンスの不整合が導体パターンとの電磁カップリングにより低減され、配線導体に信号を効率良く伝播させることができる。
【００１９】
また、本発明の配線基板によれば、前記貫通導体が前記絶縁基体の表面まで達しているとともに前記絶縁層を挟んで前記開口部に対向する領域の前記絶縁基体の表面に外部接続用の電極パッドが前記貫通導体に接続するように被着されている場合に、前記開口部が前記電極パッドよりも大きく形成されていると、その電極パッドと開口部を有する導体層との間のキャパシタンスが低減され、貫通導体から電極パッドに信号を良好に伝播させることができる。
【００２０】
また、本発明の電子装置は、上記の配線基板に電子部品が搭載されるとともに該電子部品の電極と前記貫通導体とが電気的に接続されていることを特徴とするものである。
【００２１】
本発明の電子装置によれば、上記の配線基板に電子部品が搭載されるとともに該電子部品の電極と前記貫通導体とが電気的に接続されていることから、平坦な絶縁基板上に電子部品が良好に搭載されており、かつ外部電気回路基板に良好に実装されることが可能である。また、搭載する電子部品を信号の反射なく良好に作動させることができる。
【００２２】
【発明の実施の形態】
次に、本発明の配線基板を添付の図面に基づき詳細に説明する。図１は、本発明の配線基板を半導体素子を搭載するための配線基板に適用した場合の実施の形態の一例を示す断面図であり、図中、１は複数の絶縁層２を積層して成る絶縁基板、３は信号用の配線導体３ａや接地または電源用の配線導体３ｂを形成する導体層、４は貫通導体、５は導体パターンであり、主にこれらで本発明の配線基板が構成される。また、６は電子部品であり、本発明の配線基板に電子部品６を搭載することにより本発明の電子装置が構成される。
【００２３】
絶縁基板１は、例えばガラスクロス等の繊維基材にアリル変性ポリフェニレンエーテル樹脂やエポキシ樹脂等の熱硬化性樹脂を含浸させて成り、導体層３や貫通導体４、導体パターン５、電子部品６を支持するための支持基板として機能する。なお、本例では８層の絶縁層２が積層されており、さらにその上下面にソルダーレジスト層７が被着された例を示している。
【００２４】
絶縁基板１は、ガラスクロス等の繊維基材に未硬化の熱硬化性樹脂を含浸させた絶縁シートを複数枚重ねるとともに上下から加圧しながら加熱することにより絶縁シート中の熱硬化性樹脂を熱硬化させることにより得られる。
【００２５】
絶縁基板１の表面および各絶縁層２の間には厚みが５〜５０μｍ程度の銅箔から成る導体層３が配設されており、さらに各絶縁層２には金属ペーストを硬化させた導電性材料から成る複数の貫通導体４が配設されている。そして、これらの貫通導体４により上下の導体層３同士が電気的に接続されている。
【００２６】
導体層３は、半導体素子等の電子部品６の各電極を外部電気回路基板に電気的に接続するための導電路の一部として機能し、信号用の配線導体３ａと接地または電源用の配線導体３ｂとを含んでいる。また、絶縁基板１の上面中央部においては、電子部品６の電極が接続される電子部品接続用の電極パッド８ａを形成しており、絶縁基板１の下面においては、外部電気回路基板の配線導体に接続される外部接続用の電極パッド８ｂを形成している。
【００２７】
信号用の配線導体３ａは幅が１０〜１００μｍ程度の細長い帯状であり、数百ＭＨｚ〜数十ＧＨｚの高速の信号が伝播する。他方、接地または電源用の配線導体３ｂは、信号用の配線導体３ａを取り囲むか、あるいは信号用の配線導体３ａと対向するように配置された広面積のパターンであり、電子部品６に接地または電源電位を提供するための外部電位に接続されるとともに信号用の配線導体３ａに対する電磁シールド機能や特性インピーダンスの調整機能を有している。また、電子部品接続用の電極パッド８ａは直径が５０〜１００μｍ程度の円形状、外部接続用の電極パッド８ｂは直径が２００〜５００μｍ程度の円形状であり、それぞれ対応する配線導体３ａ、３ｂに貫通導体４を介して接続されている。なお、接地または電源用の配線導体３ｂには信号用の配線導体３ａに接続された貫通導体４や電位の異なる接地または電源用の配線導体３ｂに接続された貫通導体４が貫通する位置にそれらの貫通導体４との電気的な絶縁を確保するために円形状の開口部Ａが設けられており、この開口部Ａの中央部を貫通導体４が貫通している。開口部Ａは信号用の貫通導体４が接続された外部接続用の電極パッド８ｂに対応する領域では外部接続用の電極パッド８ｂよりも大きな面積で設けられており、それにより信号用の外部接続用のパッド８ｂと接地または電源用の配線導体３ｂとの間に形成されるキャパシタンスを小さいものとして信号用の配線導体３ａに信号の反射が発生することを防止している。
【００２８】
そして、電子部品接続用の電極パッド８ａには電子部品６の電極が半田バンプ９ａを介して接続され、外部接続用の電極パッド８ｂは外部電気回路基板の配線導体に半田バンプ９ｂを介して接続される。なお、導体層３は、絶縁層２用の絶縁シートの表面に所定パターンの銅箔を予め埋設しておくことによって絶縁基板１の表面や各絶縁層２の間に配設される。
【００２９】
また、貫通導体４は、各絶縁層２を貫通して設けられた錫および熱硬化性樹脂を含有する導電性材料から成る円柱状の導体柱４ａと、絶縁層２の間に導体柱４ａに接続されるように設けられた銅箔から成る円板状の接続ランド４ｂとから成り、上下の導体柱４ａを接続ランド４ｂを介して接続することにより複数の絶縁層２を貫通する長い貫通導体４が形成される。なお、本例では上下の導体柱４ａ同士を接続ランド４ｂを介して接続した例を示したが、上下の導体柱４ａの間には必ずしも接続ランド４ｂを設ける必要はなく、上下の導体柱４ａ同士を直接接続して貫通導体４を形成してもよい。
【００３０】
導体柱４ａは、絶縁層２用の絶縁シートにレーザ加工により直径が３０〜２００μｍ程度の貫通孔を穿孔するとともに、その貫通孔内に例えば錫と銀とビスマスと銅とを含有する合金粉末および熱硬化性樹脂の前駆体を含有する未硬化の金属ペーストを充填しておき、その金属ペーストの熱硬化性樹脂の前駆体を絶縁層２用の絶縁シート中の熱硬化性樹脂の前駆体とともに熱硬化させることにより形成される。また、接続ランド４ｂは、絶縁層２用の絶縁シートの表面に導体層３用の銅箔を埋設するのと同時に接続ランド４ｂ用の所定パターンの銅箔を絶縁シート表面に埋設しておくことにより形成される。なお、接続ランド４ｂの直径が導体柱４ａの直径よりも３０μｍ未満大きい場合、絶縁層２用の絶縁シートを積層する際に、製造誤差により上下の絶縁シートがずれて積層された場合に上下の導体柱４ａ同士を接続ランド４ｂを介して良好に接続することが困難となる。他方、接続ランド４ｂの直径が導体柱４ａの直径よりも２００μｍを超えて大きい場合、接続ランド４ｂが大きな面積を占めるため貫通導体４を高密度に配列することが困難となる。したがって、接続ランド４ｂの直径は、導体柱４ａの直径よりも３０〜２００μｍ大きいものとしておくことが好ましい。
【００３１】
さらに、信号用の配線導体３ａに接続された貫通導体４が貫通する絶縁層２の間には、接地または電源用の配線導体３ｂに設けられた開口部Ａ内に貫通導体４および配線導体３ｂから電気的に独立した銅箔から成る導体パターン５が配設されている。
【００３２】
この導体パターン５は、絶縁層２用の絶縁シートを積層するとともに上下から加圧しながら加熱する際に、開口部Ａ内の樹脂が加圧および加熱により大きく変形して開口部Ａに対応する絶縁基板１の表面に大きな凹みが形成されるのを防止するための変形防止部材として機能し、図２に導体層３および貫通導体４および導体パターン５の要部上面図で示すように、例えば、貫通導体４を取り囲む円環状であり、図３に図２のＸ−Ｘ切断面における部分断面斜視図で示すように上下に配設された各導体層３毎にそれぞれ設けられている。このように開口部Ａ内の貫通導体４の周囲に貫通導体４および配線導体３ｂから電気的に独立した導体パターン５を設けることにより、開口部Ａ内における樹脂の占める比率が小さなものとなり、絶縁層２用の絶縁シートを積層するとともに上下から加圧しながら加熱する際に開口部Ａ内の樹脂が変形しにくくなる。したがって、開口部Ａに対応する絶縁基板１の表面に大きな凹みが発生することを有効に防止することができる。
【００３３】
なお、導体パターン５と貫通導体４との間隔Ｇ１が５０μｍ未満の場合、貫通導体４と導体パターン５との間に大きな浮遊容量が形成され、信号用の配線導体３ａに接続された貫通導体４に周波数が例えば５ＧＨｚ以上の信号を効率良く伝播させることが困難となる。他方、導体パターン５と貫通導体４との間隔Ｇ１が１５０μｍを超えると、絶縁層２用の絶縁シートを積層するとともに上下から加圧しながら加熱する際に開口部Ａ内における導体パターン５と貫通導体４との間で樹脂が変形し、開口部Ａに対応する絶縁基板１の表面に大きな凹みが発生しやすくなる。したがって、導体パターン５と貫通導体４との間隔Ｇ１は５０〜１５０μｍの範囲が好ましい。
【００３４】
さらに、導体パターン５から開口部Ａの縁までの間隔Ｇ２が１０μｍ未満の場合、導体パターン５と接地または電源用の配線導体層３ｂとの間の電気的な絶縁信頼性が低下する危険性が大きくなる。他方、導体パターン５から開口部Ａの縁までの間隔Ｇ２が１５０μｍを超えると、絶縁層２用の絶縁シートを積層するとともに上下から加圧しながら加熱する際に開口部Ａ内における導体パターン５と開口部Ａの縁との間で樹脂が変形し、開口部Ａに対応する絶縁基板１の表面に大きな凹みが発生しやすくなる。したがって、導体パターン５から開口部Ａの縁まで間隔Ｇ２は１０〜１５０μｍの範囲が好ましい。
【００３５】
また、導体パターン５の幅Ｗが５０μｍ未満の場合、絶縁層２用の絶縁シートを積層するとともに上下から加圧しながら加熱する際に、開口部Ａ内の樹脂が加圧および加熱により大きく変形するのを防止するための障壁部材としての機能を十分に発揮することが困難となる。他方、導体パターン５の幅Ｗが５００μｍを超える場合、開口部Ａの径をその分、大きくする必要があり、接地または電源用の配線導体３ｂを信号用の配線導体３ａに対する電磁シールド機能や特性インピーダンスの調整機能を有するに十分な面積で設けることが困難となる。したがって、導体パターン５の幅Ｗは５０〜５００μｍの範囲が好ましい。
【００３６】
なお、導体パターン５を貫通導体４を貫通導体４の断面に対して同心円状に取り囲む環状としておくと、開口部Ａ内の貫通導体４の周囲に均一に導体パターン５を配置することができ、それにより貫通導体４を取り囲む開口部Ａに対応する絶縁基板１の表面の凹みを極めて良好に防止することができる。
【００３７】
さらに、貫通導体４に伝播される信号が周波数１０ＧＨｚ以上の高周波信号である場合、図４に導体層３および貫通導体４および導体パターン５の要部上面図で示すように、開口部Ａ内に設ける導体パターン５を、貫通導体４を伝播する高周波信号の波長の４分の１未満の長さの複数の導体片を互いに電気的に独立した状態で貫通導体４を取り囲む環状の並びに配列したものとすると、導体パターン５における共振が防止され、貫通導体４に周波数が１０ＧＨｚ以上の高周波信号を効率よく伝播させることができる。したがって、貫通導体４に伝播される信号が周波数１０ＧＨｚ以上の高周波信号である場合、開口部Ａ内に設ける導体パターン５を、貫通導体４を伝播する信号の波長の４分の１未満の長さの複数の導体片を互いに電気的に独立した状態で貫通導体４を取り囲む環状の並びに配列したものとすることが好ましい。
【００３８】
なお、この場合、導体片同士の間隔Ｇ３が１０μｍ未満であると、導体片同士の間の電気的な絶縁性が低下してしまい、１０ＧＨｚ以上の信号を伝播する際に、導体パターン５における共振現象が発生する可能性が高くなって、１０ＧＨｚ以上の高速の信号を効率よく伝播させることが難しくなる。他方、導体片同士の間隔Ｇ３が２００μｍを超えると、絶縁層２用の絶縁シートを積層するとともに上下から加圧しながら加熱する際に開口部Ａ内における導体片同士の間で樹脂が変形し、開口部Ａに対応する絶縁基板１の表面に大きな凹みが発生しやすくなる。したがって、導体片同士の間隔Ｇ３は１０〜２００μｍの範囲が好ましい。
【００３９】
さらに、導体片の長さＬが５００μｍ未満の場合、絶縁層２用の絶縁シートを積層するとともに上下から加圧しながら加熱する際に、開口部Ａ内の樹脂が加圧および加熱により大きく変形するのを防止するための障壁部材としての機能を十分に発揮することが困難となる。したがって、導体片の長さＬは５００μｍ以上であることが好ましい。
【００４０】
またこの場合、貫通導体４に接続された信号用の配線導体３ａを導体パターン５と対向する領域を横切って絶縁層２の表面に延びるように配設すると、信号用の配線導体３ａと導体パターン５との電磁カップリングにより信号用の配線導体３ａの特性インピーダンスが開口部Ａと対向する領域で大きく変化することが防止されて信号用の配線導体３ａに信号を効率良く伝播させることができる。したがって、貫通導体４に接続された信号用の配線導体３ａは、導体パターン５と対向する領域を横切って絶縁層２の表面に延びるように配設することが好ましい。
【００４１】
さらにまた、複数の導体片が貫通導体４を取り囲む環状の並びに配列された導体パターン５を絶縁層２を挟んで上下に複数層配設した場合、図５に図４のＸ−Ｘ線断面における部分断面斜視図で示すように、上下の導体パターン５同士の間で導体片の位置を貫通導体４を取り囲む並びの周方向に互いにずらして配置すると、絶縁層２用の絶縁シートを積層するとともに上下から加圧しながら加熱する際に、導体片５ａ同士の間隔Ｇ３部における局部的な樹脂の変形を効果的に防止することが可能となる。したがって、複数の導体片が貫通導体４を取り囲む環状の並びに配列された導体パターン５を絶縁層２を挟んで上下に複数層配設した場合、上下の導体パターン５同士の間で導体片の位置を導体片の並びの周方向に互いにずらして配置することが好ましい。
【００４２】
かくして、本発明の配線基板によれば、絶縁基板１の上面に電子部品をその電極が半田９ａを介して各電子部品接続用の電極パッド８ａに接続されるようにして搭載することにより本発明の電子装置となり、この電子装置における外部接続用の電極パッド８ｂを外部電気回路基板の配線導体に半田９ｂを介して接続することにより本発明の電子装置が外部電気回路基板に実装されるとともに搭載する電子部品の各電極が外部電気回路に電気的に接続されることとなる。
【００４３】
このとき、本発明の配線基板は、開口部Ａ内に導体パターン５が配設されており、それにより開口部Ａに対応する絶縁基板１の表面に大きな凹みが形成されていないので、電子部品６を良好に搭載することができる。また、本発明の電子装置によれば、開口部Ａ内に導体パターン５が配設されており、それにより開口部Ａに対応する絶縁基板１の表面に大きな凹みが形成されていないので、外部の電気回路基板に良好に実装することができる。
【００４４】
なお、本発明は上述の実施の形態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ことはいうまでもない。
【００４５】
【実施例】ガラスクロスに未硬化のアリル変性ポリフェニレンエーテル樹脂を含浸させて成る厚みが９５μｍの絶縁シートを４枚準備するとともに、それらの絶縁シートにレーザ加工により直径が１００μｍの貫通孔を穿孔した。次に、それらの絶縁シートに穿孔した貫通孔内に錫と銀とビスマスと銅とを含有する合金粉末および未硬化のトリアジン系樹脂を含有する金属ペーストをスクリーン印刷法により充填した。次にそれぞれ厚みが１０μｍの銅箔から成る、直径が１８０μｍの接続ランドと内径が３３０μｍで外径が６５０μｍの円環状の導体パターンと直径が８００μｍの円形の開口部を有する導体層とを、絶縁シートの貫通孔内に充填した金属ペーストと接続ランドと導体パターンと導体層の開口部とが同心円状の配置となるように、絶縁シートの主面に転写法を採用して転写した。なお、４枚の絶縁シートのうち、１枚には接続ランドと導体パターンと導体層とを両方の主面に転写し、残りの３枚には片側の主面のみに転写した。次にこれらの絶縁シートを各絶縁シートの貫通孔内に充填した金属ペーストの上下両端に接続ランドが接続されるようにして積層するとともに上下から５ＭＰａの圧力を印加しながら２００℃の温度で５時間加熱することにより絶縁シートおよび金属ペーストを硬化させて図２に示した例と対応する本発明による第１の試料を得た。また、導体パターンの内径を３８０μｍとした以外は第１の試料と同様にして製作することにより本発明による第２の試料を得た。さらに導体パターンの内径を４８０μｍとした以外は第１および第２の試料と同様にして製作することにより本発明による第３の試料を得た。
【００４６】
また、上記第１〜第３の試料における導体パターンの内周から外周にかけて幅が５０μｍの４つの切り込みを、それぞれ隣接する切り込み同士が貫通導体を中心にして互いに９０度の角度で延びるように入れるとともに上下の導体パターン同士で切り込みが互いに重なり合うようにして配置した以外は上記第１〜第３の試料と同様にして製作することにより、図４に示した例と対応する本発明による第４〜第６の試料を得た。
【００４７】
さらに、上記第４〜第６の試料における切り込みの幅を１００μｍとした以外は上記第４〜第６の試料と同様にして製作することにより、図４に示した例と対応する本発明による第７〜第９の試料を得た。
【００４８】
さらにまた、上記第７〜第９の試料における上下の導体パターン同士を交互に４５度ずつずらして配置した以外は上記第７〜第９の試料と同様にして製作することにより、図４に示した例と対応する本発明による第１０〜第１２の試料を得た。
【００４９】
また、上記導体パターンを有しない以外は上記本発明による試料と同様にして製作することにより、比較のための第１３の試料を得た。さらに、第１３の試料における開口部の直径を３３０μｍとした以外は第１３の試料と同様にして製作することにより比較のための第１４の試料を得た。
【００５０】
このようにして得られた本発明による第１〜第１２の試料および比較のための第１３の試料について、それぞれの表面における上記開口部に対応する領域の凹みの深さをレーザ光を用いた三次元反り測定装置により測定した。その結果を表１に示す。
【００５１】
【表１】
【００５２】
表１から分かるように、開口部内に導体パターンを有していない比較のための第１３の試料では凹みが１５μｍと大きかった。それに対して、本発明による第１〜第１２の試料においては、凹みの深さはいずれも１０μｍ以下と小さかった。
【００５３】
また、本発明による第１〜第１２の試料および比較のための第１４試料の上下面に厚みが３５μｍのエポキシ樹脂から成り、上下面の接続パッドの中央部を露出させる直径が５０μｍの貫通孔を有する樹脂層を積層するとともにその貫通孔内および樹脂層の表面に無電解銅めっきおよび電解銅めっきをセミアディティブ法を用いて１５μｍの厚みの所定パターンに施すことにより、樹脂層の貫通孔内を充填するとともに貫通孔から樹脂層の表面に延びる幅が２５μｍの信号用の配線導体およびその信号用の配線導体を７０μｍの間隔を空けて取り囲む接地用の配線導体層を形成し、さらにその上に厚みが３５μｍのエポキシ樹脂から成る樹脂層および厚みが１５μｍの銅めっき層からなる接地導体層を積層した。なお、第４〜第５の試料においては、信号用の配線導体が導体パターンの切り込み上を延びるようにし、その他の試料においては信号用の配線導体が最表層の導体パターン上を延びるようにして配置した。
【００５４】
次にこれらの試料について上下の信号用の配線導体間に高周波の信号を入力し、その反射損が−２０ｄＢとなる周波数を測定した。その結果を表２に示す。
【００５５】
【表２】
【００５６】
表２から分かるように、比較のための第１４の試料では反射損が−２０ｄＢとなる周波数が６．５ＧＨｚと低いのに対して、本発明による第１から第１２の試料では反射損が−２０ｄＢとなる周波数がいずれも９．５ＧＨｚ以上であり、高周波信号を良好に伝達できることが分かる。
【００５７】
【発明の効果】
本発明の配線基板によれば、貫通導体を取り囲む導体層の開口部内に貫通導体および導体層から電気的に独立した導体パターンを貫通導体を取り囲むようにして配設したことから、貫通導体を取り囲む開口部内における樹脂の占める比率が導体パターンにより小さくなり、配線基板を製作するために絶縁層用の絶縁シートを積層して上下から加圧しながら加熱しても開口部内の剛性が低下することはなく、開口部内の樹脂が上下からの加圧および加熱により大きく変形して開口部に対応する絶縁基板の表面に大きな凹みが発生することはない。したがって電子部品を良好に搭載することができるとともに外部電気回路基板に良好に実装することが可能な配線基板を提供することができる。
【００５８】
また、本発明の配線基板によれば、前記導体パターンが前記貫通導体を取り囲む環状であると、貫通導体の周囲の全周にわたり均一に導体パターンが配置され、それにより貫通導体を取り囲む開口部に対応する絶縁基板表面の凹みが極めて良好に防止される。
【００５９】
また、本発明の配線基板によれば、前記貫通導体を伝播する信号が周波数１０ＧＨｚ以上の高周波信号である場合に、前記導体パターンが前記高周波信号の波長の４分の１未満の長さの互いに電気的に独立した複数の導体片を前記貫通導体を取り囲む環状の並びに配列したものであると、前記導体パターン内で高周波信号の共振が発生することが有効に防止され、それにより１０ＧＨｚ以上の高周波信号を極めて効率良く伝播させることができる。
【００６０】
さらに、本発明の配線基板によれば、上記のように前記導体パターンが高周波信号の波長の４分の１未満の長さの互いに電気的に独立した複数の導体片を貫通導体を取り囲む環状の並びに配列したものであり、かつ前記導体層および前記導体パターンが前記貫通導体に対して前記絶縁層を挟んで上下に複数層配設されている場合に、前記導体片の位置が上下の導体パターン同士で環状の並びの周方向に互いにずれていると、貫通導体の周囲に導体片が満遍なく配置されて開口部内の樹脂の変形がより効果的に防止される。
【００６１】
また、本発明の配線基板によれば、前記貫通導体の一端に帯状の配線導体が接続されている場合に、該配線導体が前記絶縁層を挟んで前記導体パターンと対向する領域を横切るように前記絶縁層の表面に延びていると、開口部内に対応する領域における配線導体の特性インピーダンスの不整合が導体パターンとの電磁カップリングにより低減され、配線導体に信号を効率良く伝播させることができる。
【００６２】
また、本発明の配線基板によれば、前記貫通導体が前記絶縁基体の表面まで達しているとともに前記絶縁層を挟んで前記開口部に対向する領域の前記絶縁基体の表面に外部接続用の電極パッドが前記貫通導体に接続するように被着されている場合に、前記開口部が前記電極パッドよりも大きく形成されていると、その電極パッドと開口部を有する導体層との間のキャパシタンスが低減され、貫通導体から電極パッドに信号を良好に伝播させることができる。
【００６３】
本発明の電子装置によれば、上記の配線基板に電子部品が搭載されるとともに該電子部品の電極と前記貫通導体とが電気的に接続されていることから、平坦な絶縁基板上に電子部品が良好に搭載されており、かつ外部電気回路基板に良好に実装されることが可能である。また、搭載する電子部品を信号の反射なく良好に作動させることができる。
【図面の簡単な説明】
【図１】本発明の配線基板の実施の形態の一例を示す断面図である。
【図２】図１に示す配線基板における導体層３および貫通導体４および導体パターン５の要部上面図である。
【図３】図２のＸ−Ｘ切断線における部分断面斜視図である。
【図４】図２に示した例とは別の例を示す図２に対応する要部上面図である。
【図５】図４のＸ−Ｘ切断線における部分断面斜視図である。
【符号の説明】
１：絶縁基板
２：絶縁層
３：導体層
３ａ：信号用の配線導体
３ｂ：接地または電源用の配線導体
４：貫通導体
５：導体パターン
６：電子部品[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wiring board for mounting an electronic component such as a semiconductor element and an electronic device in which the electronic component is mounted on the wiring board.
[0002]
[Prior art]
In general, in response to the demand for downsizing and thinning of electronic devices such as mobile communication devices, wiring boards for mounting electronic components such as semiconductor elements used in such electronic devices are also small. There has been a demand for downsizing, thinning, and multiple terminals. As a wiring board for realizing such miniaturization, thinning, and multi-terminal, a wiring board for a ball grid array package that can be surface-mounted on the external electric circuit board via solder bumps is put into practical use. Has been.
[0003]
The wiring substrate for this ball grid array package has hundreds to thousands of diameters of about 50 to 100 μm, in which electrodes of electronic components are connected to the upper surface of an insulating substrate formed by laminating a plurality of insulating layers via solder. The electrode pads for connecting the electronic components are arranged in a grid pattern, and the diameter of the electrode pads connected to the wiring conductor of the external electric circuit board via solder on the lower surface of the insulating substrate is about several hundreds of about 200 to 500 μm. Thousands of electrode pads for external connection are arranged in a grid. A plurality of conductor layers for wiring conductors are disposed between the insulating layers, and between the conductor layers positioned above and below between each insulating layer and between the conductor layer and the electrode pad are insulating layers. The electrode pads for connecting electronic components and the electrode pads for external connection are electrically connected to each other by being connected by a through conductor having a diameter of about 30 to 200 μm provided through the connector.
[0004]
Note that such a wiring board is formed by, for example, drilling a through-hole for forming a through-conductor by laser processing on an insulating sheet for an insulating layer in which a glass cloth is impregnated with an uncured thermosetting resin, and then this through-hole. Filled with a metal paste for through conductor mixed with uncured thermosetting resin and metal powder inside, and adhered a conductor layer for wiring conductor formed in a predetermined pattern on the surface of the insulating sheet, then It is manufactured by laminating a plurality of insulating sheets to which a conductor layer is applied and heating the thermosetting resin in the insulating sheet and the metal paste by heating while pressing from above and below.
[0005]
The wiring board becomes an electronic device by mounting the electronic component so that the electrode pad for connecting the electronic component and the electrode of the electronic component are connected via solder, and the electronic device The connecting electrode pad and the wiring conductor of the external electric circuit board are connected via solder to be mounted on the external electric circuit board and the mounted electronic component is electrically connected to the external electric circuit. It will be.
[0006]
In addition, the wiring conductor in such a wiring board is functionalized as a wiring conductor for signal, grounding, and power supply depending on the application.
[0007]
Among these, the signal wiring conductor functions as a conductive path for propagating an electric signal between an electronic component such as a semiconductor element and an external electric circuit board, and is generally a thin strip, and includes a plurality of insulating layers. The penetrating through conductor is connected to the corresponding electrode pad for connecting an electronic component and the electrode pad for external connection.
[0008]
In addition, the wiring conductor for grounding and the wiring conductor for power supply have a function as a supply path for supplying a ground potential and a power supply potential to the electronic components mounted on the wiring board, respectively. An electronic component that has an electromagnetic shielding function and a characteristic impedance adjustment function, and has a large-area conductor layer facing the wiring conductor for signals between the insulating layers, and a corresponding through-hole conductor that penetrates the insulating layer. It is connected to the electrode pad for connection and the electrode pad for external connection.
[0009]
However, in such a wiring board, a large-area grounding or power supply conductor layer is provided between the insulating layers of the insulating substrate. A large capacitance is generated between the external connection electrode pads, which causes reflection noise in the signal wiring conductor and malfunctions in the electronic components mounted on the wiring board. Had. Therefore, in order to solve such problems, Patent Document 1 discloses that an electrode pad for external connection for signals is provided on a conductor layer for grounding or power supply corresponding to an electrode pad for external connection for signals. It has been proposed to provide a larger circular opening. By providing such an opening, the capacitance formed between the signal external connection electrode pad and the grounding or power supply conductor layer is reduced.
[0010]
[Patent Document 1]
JP 2003-78065 A
[0011]
[Problems to be solved by the invention]
However, as proposed in Patent Document 1, a larger opening than the signal external connection electrode pad is formed in the grounding or power supply conductor layer in the region corresponding to the signal external connection electrode pad. If provided, the ratio of the resin in the opening becomes large. When the ratio of the resin in the opening increases as described above, the rigidity in the opening decreases when the insulating sheet for the insulating layer is laminated and heated while pressing from above and below to produce this wiring board. The resin in the opening is greatly deformed by pressing and heating from above and below, and as a result, a large dent is generated on the surface of the insulating substrate corresponding to the opening. If such a dent occurs, it becomes impossible to mount the electronic component satisfactorily when mounting the electronic component on the wiring board, or the electronic device having the electronic component mounted on the wiring board is connected to the external electric circuit board. However, there is a problem that the electronic device cannot be mounted satisfactorily.
[0012]
The present invention has been completed in view of the problems of the prior art, and an object of the present invention is to provide a signal external layer on a conductor layer for grounding or power supply corresponding to an electrode pad for external connection for signals. Even if an opening larger than the electrode pad for connection is provided, a large dent does not occur on the surface of the insulating substrate corresponding to the opening, thereby enabling a good mounting of electronic components. And providing an electronic device that can be satisfactorily mounted on an external electric circuit board.
[0013]
[Means for Solving the Problems]
The wiring board according to the present invention includes an insulating substrate formed by laminating a plurality of insulating layers, a through conductor provided through the plurality of insulating layers, and the plurality of insulating layers through which the through conductor passes. And a conductor layer having an opening surrounding the through conductor and having a conductor pattern electrically independent from the through conductor and the conductor layer in the opening. It is characterized by being disposed so as to surround the through conductor.
[0014]
According to the wiring board of the present invention, because of the above configuration, the ratio of the resin in the opening surrounding the through conductor is reduced by the conductor pattern, and an insulating sheet for the insulating layer is laminated to manufacture the wiring board. Even if heated while pressing from above and below, the rigidity in the opening is not greatly reduced, and the resin in the opening is greatly deformed by pressing and heating from above and below, and the surface of the insulating substrate corresponding to the opening is large. There will be no dents.
[0015]
Further, according to the wiring board of the present invention, when the conductor pattern is an annular shape surrounding the through conductor, the conductor pattern is uniformly arranged over the entire circumference of the through conductor, thereby opening the opening surrounding the through conductor. Corresponding dents on the insulating substrate surface are prevented very well.
[0016]
Further, according to the wiring board of the present invention, when the signal propagating through the through conductor is a high-frequency signal having a frequency of 10 GHz or more, the conductor pattern has a length less than a quarter of the wavelength of the high-frequency signal. When a plurality of electrically independent conductor pieces are arranged in an annular arrangement surrounding the through conductor, it is possible to effectively prevent the resonance of a high frequency signal in the conductor pattern, and thereby a high frequency of 10 GHz or more. Signals can be propagated very efficiently.
[0017]
Furthermore, according to the wiring board of the present invention, as described above, the conductor pattern has an annular shape surrounding a through conductor with a plurality of electrically independent conductor pieces having a length less than a quarter of the wavelength of a high-frequency signal. When the conductor layer and the conductor pattern are arranged in a plurality of layers above and below the insulating layer with respect to the through conductor, the positions of the conductor pieces are the upper and lower conductor patterns. If they are shifted from each other in the circumferential direction of the annular arrangement, the conductor pieces are uniformly arranged around the through conductors, and the deformation of the resin in the opening is more effectively prevented.
[0018]
Further, according to the wiring board of the present invention, when a strip-like wiring conductor is connected to one end of the through conductor, the wiring conductor crosses the region facing the conductor pattern with the insulating layer interposed therebetween. When extending to the surface of the insulating layer, the mismatch of the characteristic impedance of the wiring conductor in the region corresponding to the opening is reduced by electromagnetic coupling with the conductor pattern, and the signal can be efficiently propagated to the wiring conductor. .
[0019]
Further, according to the wiring board of the present invention, the through conductors reach the surface of the insulating base, and the electrodes for external connection are formed on the surface of the insulating base in a region facing the opening with the insulating layer interposed therebetween. When the pad is attached so as to be connected to the through conductor, and the opening is formed larger than the electrode pad, the capacitance between the electrode pad and the conductor layer having the opening is increased. The signal can be satisfactorily propagated from the through conductor to the electrode pad.
[0020]
The electronic device according to the present invention is characterized in that an electronic component is mounted on the wiring board, and an electrode of the electronic component and the through conductor are electrically connected.
[0021]
According to the electronic device of the present invention, since the electronic component is mounted on the wiring board and the electrode of the electronic component and the through conductor are electrically connected, the electronic component is placed on the flat insulating substrate. Can be mounted on the external electric circuit board well. In addition, the mounted electronic component can be operated satisfactorily without signal reflection.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Next, the wiring board of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing an example of an embodiment in which the wiring board of the present invention is applied to a wiring board for mounting a semiconductor element. In the figure, reference numeral 1 denotes a plurality of insulating layers 2 stacked. An insulating substrate 3 is a conductor layer for forming a signal wiring conductor 3a and a grounding or power supply wiring conductor 3b, 4 is a through conductor, and 5 is a conductor pattern, which mainly constitute the wiring board of the present invention. Is done. Reference numeral 6 denotes an electronic component, and the electronic device of the present invention is configured by mounting the electronic component 6 on the wiring board of the present invention.
[0023]
The insulating substrate 1 is formed by impregnating a fiber base material such as glass cloth with a thermosetting resin such as allyl-modified polyphenylene ether resin or epoxy resin, and includes the conductor layer 3, the through conductor 4, the conductor pattern 5, and the electronic component 6. It functions as a support substrate for supporting. In this example, eight insulating layers 2 are laminated, and solder resist layers 7 are further deposited on the upper and lower surfaces.
[0024]
The insulating substrate 1 heats the thermosetting resin in the insulating sheet by stacking a plurality of insulating sheets impregnated with an uncured thermosetting resin on a fiber base such as glass cloth and heating while pressing from above and below. It is obtained by curing.
[0025]
A conductor layer 3 made of copper foil having a thickness of about 5 to 50 μm is disposed between the surface of the insulating substrate 1 and each insulating layer 2, and each insulating layer 2 is made of a conductive material obtained by curing a metal paste. A plurality of through conductors 4 made of a material are provided. The upper and lower conductor layers 3 are electrically connected by these through conductors 4.
[0026]
The conductor layer 3 functions as a part of a conductive path for electrically connecting each electrode of the electronic component 6 such as a semiconductor element to an external electric circuit board, and is connected to a signal wiring conductor 3a and a ground or power supply wiring. And a conductor 3b. Further, an electrode pad 8a for connecting an electronic component to which an electrode of the electronic component 6 is connected is formed at the center of the upper surface of the insulating substrate 1, and a wiring conductor of an external electric circuit substrate is formed on the lower surface of the insulating substrate 1. The electrode pad 8b for external connection connected to is formed.
[0027]
The signal wiring conductor 3a has an elongated strip shape with a width of about 10 to 100 μm, and a high-speed signal of several hundred MHz to several tens GHz propagates. On the other hand, the wiring conductor 3b for grounding or power supply is a wide area pattern that surrounds the signal wiring conductor 3a or is opposed to the signal wiring conductor 3a. It is connected to an external potential for providing a power supply potential, and has an electromagnetic shielding function and a characteristic impedance adjustment function for the signal wiring conductor 3a. The electrode pad 8a for connecting an electronic component has a circular shape with a diameter of about 50 to 100 μm, and the electrode pad 8b for external connection has a circular shape with a diameter of about 200 to 500 μm. They are connected via the through conductor 4. The grounding or power supply wiring conductor 3b has a through conductor 4 connected to the signal wiring conductor 3a or a through conductor 4 connected to the grounding or power supply wiring conductor 3b having a different potential at a position where they penetrate. A circular opening A is provided to ensure electrical insulation from the through conductor 4, and the through conductor 4 passes through the center of the opening A. The opening A is provided in a larger area than the electrode pad 8b for external connection in a region corresponding to the electrode pad 8b for external connection to which the signal through conductor 4 is connected. Signal reflection is prevented from occurring in the signal wiring conductor 3a by reducing the capacitance formed between the wiring pad 8b for grounding and the wiring conductor 3b for grounding or power supply.
[0028]
The electrode of the electronic component 6 is connected to the electrode pad 8a for connecting the electronic component via the solder bump 9a, and the electrode pad 8b for external connection is connected to the wiring conductor of the external electric circuit board via the solder bump 9b. Is done. The conductor layer 3 is disposed between the surface of the insulating substrate 1 and between the insulating layers 2 by previously embedding a predetermined pattern of copper foil on the surface of the insulating sheet for the insulating layer 2.
[0029]
Further, the through conductor 4 is formed between the columnar conductor column 4 a made of a conductive material containing tin and a thermosetting resin provided through each insulating layer 2 and the conductor column 4 a between the insulating layer 2. A long penetrating conductor that includes a disk-shaped connection land 4b made of copper foil provided so as to be connected and penetrates the plurality of insulating layers 2 by connecting the upper and lower conductor columns 4a via the connection land 4b. 4 is formed. In this example, the upper and lower conductor columns 4a are connected via the connection lands 4b. However, the connection lands 4b are not necessarily provided between the upper and lower conductor columns 4a, and the upper and lower conductor columns 4a are not necessarily provided. The through conductors 4 may be formed by directly connecting each other.
[0030]
The conductor pillar 4a is formed by drilling a through hole having a diameter of about 30 to 200 μm by laser processing on the insulating sheet for the insulating layer 2, and containing, for example, tin, silver, bismuth and copper in the through hole. An uncured metal paste containing a thermosetting resin precursor is filled, and the thermosetting resin precursor of the metal paste is combined with the thermosetting resin precursor in the insulating sheet for the insulating layer 2. It is formed by thermosetting. In the connection land 4b, the copper foil for the conductor layer 3 is embedded on the surface of the insulating sheet for the insulating layer 2, and at the same time, the copper foil having a predetermined pattern for the connection land 4b is embedded on the surface of the insulating sheet. It is formed by. In addition, when the diameter of the connection land 4b is larger than the diameter of the conductor pillar 4a by less than 30 μm, when the insulating sheets for the insulating layer 2 are stacked, the upper and lower insulating sheets are shifted when the upper and lower insulating sheets are shifted due to a manufacturing error. It becomes difficult to connect the conductor columns 4a to each other through the connection lands 4b. On the other hand, when the diameter of the connection land 4b is larger than the diameter of the conductor column 4a by more than 200 μm, the connection land 4b occupies a large area, so that it is difficult to arrange the through conductors 4 at a high density. Therefore, it is preferable that the diameter of the connection land 4b be 30 to 200 μm larger than the diameter of the conductor column 4a.
[0031]
Further, between the insulating layer 2 through which the through conductor 4 connected to the signal wiring conductor 3a passes, the through conductor 4 and the wiring conductor 3b are provided in an opening A provided in the ground or power wiring conductor 3b. A conductor pattern 5 made of a copper foil electrically independent of the above is disposed.
[0032]
When the conductor pattern 5 is laminated while the insulating sheet for the insulating layer 2 is laminated and heated while being pressed from above and below, the resin in the opening A is greatly deformed by pressurization and heating, and the insulation corresponding to the opening A As a deformation preventing member for preventing the formation of a large dent on the surface of the substrate 1, as shown in the top view of the main part of the conductor layer 3, the through conductor 4, and the conductor pattern 5 in FIG. It is an annular shape surrounding the through conductor 4, and is provided for each conductor layer 3 arranged vertically as shown in the partial cross-sectional perspective view of FIG. Thus, by providing the conductor pattern 5 that is electrically independent from the through conductor 4 and the wiring conductor 3b around the through conductor 4 in the opening A, the ratio of the resin in the opening A becomes small, and insulation is achieved. When the insulating sheet for the layer 2 is laminated and heated while pressing from above and below, the resin in the opening A is hardly deformed. Therefore, it is possible to effectively prevent a large dent from occurring on the surface of the insulating substrate 1 corresponding to the opening A.
[0033]
When the gap G1 between the conductor pattern 5 and the through conductor 4 is less than 50 μm, a large stray capacitance is formed between the through conductor 4 and the conductor pattern 5, and the through conductor 4 connected to the signal wiring conductor 3a. In addition, it is difficult to efficiently propagate a signal having a frequency of, for example, 5 GHz or more. On the other hand, when the gap G1 between the conductor pattern 5 and the through conductor 4 exceeds 150 μm, the conductor pattern 5 and the through conductor in the opening A are stacked when the insulating sheet for the insulating layer 2 is laminated and heated while pressing from above and below. The resin is deformed with respect to 4 and the surface of the insulating substrate 1 corresponding to the opening A is likely to have a large dent. Therefore, the distance G1 between the conductor pattern 5 and the through conductor 4 is preferably in the range of 50 to 150 μm.
[0034]
Furthermore, when the gap G2 from the conductor pattern 5 to the edge of the opening A is less than 10 μm, there is a risk that the electrical insulation reliability between the conductor pattern 5 and the wiring conductor layer 3b for grounding or power supply is lowered. growing. On the other hand, when the gap G2 from the conductor pattern 5 to the edge of the opening A exceeds 150 μm, when the insulating sheet for the insulating layer 2 is laminated and heated while pressing from above and below, the conductor pattern 5 in the opening A The resin is deformed between the edges of the opening A, and a large dent tends to occur on the surface of the insulating substrate 1 corresponding to the opening A. Therefore, the distance G2 from the conductor pattern 5 to the edge of the opening A is preferably in the range of 10 to 150 μm.
[0035]
Further, when the width W of the conductor pattern 5 is less than 50 μm, when the insulating sheet for the insulating layer 2 is laminated and heated while pressing from above and below, the resin in the opening A is greatly deformed by pressurization and heating. It is difficult to sufficiently exhibit the function as a barrier member for preventing the above. On the other hand, when the width W of the conductor pattern 5 exceeds 500 μm, it is necessary to increase the diameter of the opening A accordingly, and the grounding or power supply wiring conductor 3b can be used as an electromagnetic shield function or characteristic for the signal wiring conductor 3a. It is difficult to provide an area sufficient to have an impedance adjustment function. Therefore, the width W of the conductor pattern 5 is preferably in the range of 50 to 500 μm.
[0036]
If the conductor pattern 5 is formed in an annular shape surrounding the through conductor 4 concentrically with respect to the cross section of the through conductor 4, the conductor pattern 5 can be uniformly arranged around the through conductor 4 in the opening A. Thereby, the dent of the surface of the insulating substrate 1 corresponding to the opening A surrounding the through conductor 4 can be prevented very well.
[0037]
Further, when the signal propagated to the through conductor 4 is a high-frequency signal having a frequency of 10 GHz or more, as shown in the top view of the main parts of the conductor layer 3, the through conductor 4, and the conductor pattern 5 in FIG. A conductor pattern 5 to be provided in which a plurality of conductor pieces having a length less than a quarter of the wavelength of a high-frequency signal propagating through the through conductor 4 are arranged in an annular arrangement surrounding the through conductor 4 in a state of being electrically independent from each other. Then, resonance in the conductor pattern 5 is prevented, and a high-frequency signal having a frequency of 10 GHz or more can be efficiently propagated to the through conductor 4. Therefore, when the signal propagated to the through conductor 4 is a high-frequency signal having a frequency of 10 GHz or more, the conductor pattern 5 provided in the opening A has a length less than a quarter of the wavelength of the signal propagating through the through conductor 4. The plurality of conductor pieces are preferably arranged in an annular arrangement surrounding the through conductor 4 in a state of being electrically independent from each other.
[0038]
In this case, if the gap G3 between the conductor pieces is less than 10 μm, the electrical insulation between the conductor pieces decreases, and the resonance in the conductor pattern 5 occurs when a signal of 10 GHz or more is propagated. The possibility of occurrence of the phenomenon increases, and it becomes difficult to efficiently propagate a high-speed signal of 10 GHz or higher. On the other hand, when the gap G3 between the conductor pieces exceeds 200 μm, the resin is deformed between the conductor pieces in the opening A when the insulating sheet for the insulating layer 2 is laminated and heated while pressing from above and below, A large dent tends to occur on the surface of the insulating substrate 1 corresponding to the opening A. Therefore, the gap G3 between the conductor pieces is preferably in the range of 10 to 200 μm.
[0039]
Furthermore, when the length L of the conductor piece is less than 500 μm, the resin in the opening A is greatly deformed by pressurization and heating when the insulating sheet for the insulating layer 2 is laminated and heated while pressing from above and below. It is difficult to sufficiently exhibit the function as a barrier member for preventing the above. Therefore, the length L of the conductor piece is preferably 500 μm or more.
[0040]
In this case, if the signal wiring conductor 3a connected to the through conductor 4 is disposed so as to extend across the region facing the conductor pattern 5 and on the surface of the insulating layer 2, the signal wiring conductor 3a and the conductor pattern are arranged. 5, the characteristic impedance of the signal wiring conductor 3 a is prevented from greatly changing in the region facing the opening A, and the signal can be efficiently propagated to the signal wiring conductor 3 a. Therefore, the signal wiring conductor 3 a connected to the through conductor 4 is preferably disposed so as to extend to the surface of the insulating layer 2 across a region facing the conductor pattern 5.
[0041]
Furthermore, when a plurality of conductor patterns 5 in which a plurality of conductor pieces surround the through conductors 4 are arranged above and below the insulating layer 2, FIG. 5 is a cross-sectional view taken along the line XX of FIG. As shown in the partial cross-sectional perspective view, when the positions of the conductor pieces are shifted from each other in the circumferential direction of the row surrounding the through conductors 4 between the upper and lower conductor patterns 5, an insulating sheet for the insulating layer 2 is laminated. When heating while pressing from above and below, it is possible to effectively prevent local deformation of the resin at the gap G3 between the conductor pieces 5a. Accordingly, when a plurality of conductor patterns 5 in which a plurality of conductor pieces surround the through conductors 4 are arranged above and below the insulating layer 2, the positions of the conductor pieces between the upper and lower conductor patterns 5 are arranged. Are preferably shifted from each other in the circumferential direction of the conductor pieces.
[0042]
Thus, according to the wiring board of the present invention, the electronic component is mounted on the upper surface of the insulating substrate 1 so that the electrode is connected to the electrode pad 8a for connecting each electronic component via the solder 9a. By connecting the electrode pad 8b for external connection in the electronic device to the wiring conductor of the external electric circuit board via the solder 9b, the electronic device of the present invention is mounted on the external electric circuit board and mounted. Each electrode of the electronic component to be connected is electrically connected to an external electric circuit.
[0043]
At this time, in the wiring board of the present invention, the conductor pattern 5 is disposed in the opening A, and thereby no large dent is formed on the surface of the insulating substrate 1 corresponding to the opening A. 6 can be mounted satisfactorily. Also, according to the electronic device of the present invention, the conductor pattern 5 is disposed in the opening A, so that no large dent is formed on the surface of the insulating substrate 1 corresponding to the opening A. It can be satisfactorily mounted on the electric circuit board.
[0044]
It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.
[0045]
EXAMPLE Four insulating sheets each having a thickness of 95 μm prepared by impregnating an uncured allyl-modified polyphenylene ether resin into a glass cloth were prepared, and through holes having a diameter of 100 μm were drilled in the insulating sheets by laser processing. . Next, the through-holes drilled in these insulating sheets were filled with an alloy powder containing tin, silver, bismuth and copper and a metal paste containing an uncured triazine resin by screen printing. Next, a connection land having a diameter of 180 μm, an annular conductor pattern having an inner diameter of 330 μm and an outer diameter of 650 μm, and a conductor layer having a circular opening having a diameter of 800 μm, each made of copper foil having a thickness of 10 μm, are insulated. The transfer was performed on the main surface of the insulating sheet so that the metal paste filled in the through holes of the sheet, the connection lands, the conductor pattern, and the openings of the conductor layer were arranged concentrically. Of the four insulating sheets, one connection land, conductor pattern, and conductor layer were transferred to both main surfaces, and the remaining three sheets were transferred to only one main surface. Next, these insulating sheets are laminated so that the connecting lands are connected to the upper and lower ends of the metal paste filled in the through holes of each insulating sheet, and at a temperature of 200 ° C. while applying a pressure of 5 MPa from above and below. The insulating sheet and the metal paste were cured by heating for a time to obtain a first sample according to the present invention corresponding to the example shown in FIG. Moreover, the 2nd sample by this invention was obtained by manufacturing similarly to a 1st sample except the internal diameter of the conductor pattern having been 380 micrometers. Further, a third sample according to the present invention was obtained by manufacturing in the same manner as the first and second samples except that the inner diameter of the conductor pattern was 480 μm.
[0046]
Further, four cuts having a width of 50 μm from the inner periphery to the outer periphery of the conductor pattern in the first to third samples are inserted so that the adjacent cuts extend at an angle of 90 degrees with respect to the through conductor. In addition, the upper and lower conductor patterns are manufactured in the same manner as the first to third samples except that the cuts are overlapped with each other, so that the fourth to fourth embodiments of the present invention corresponding to the example shown in FIG. A sixth sample was obtained.
[0047]
Further, the fourth to sixth samples are manufactured in the same manner as the fourth to sixth samples except that the cut width is set to 100 μm, so that the present invention corresponding to the example shown in FIG. Seven to ninth samples were obtained.
[0048]
Furthermore, as shown in FIG. 4, the upper and lower conductor patterns in the seventh to ninth samples are manufactured in the same manner as the seventh to ninth samples except that the upper and lower conductor patterns are alternately shifted by 45 degrees. Tenth to twelfth samples according to the present invention corresponding to the above examples were obtained.
[0049]
A thirteenth sample for comparison was obtained by manufacturing in the same manner as the sample according to the present invention except that the conductor pattern was not provided. Furthermore, a fourteenth sample for comparison was obtained by manufacturing in the same manner as the thirteenth sample except that the diameter of the opening in the thirteenth sample was 330 μm.
[0050]
About the 1st-12th sample by this invention obtained in this way, and the 13th sample for a comparison, the laser beam was used for the depth of the dent of the area | region corresponding to the said opening part in each surface. Measurement was performed with a three-dimensional warpage measuring device. The results are shown in Table 1.
[0051]
[Table 1]
[0052]
As can be seen from Table 1, the dent of the thirteenth sample for comparison without the conductor pattern in the opening was as large as 15 μm. On the other hand, in the first to twelfth samples according to the present invention, the depth of the dent was as small as 10 μm or less.
[0053]
Further, the first to twelfth samples according to the present invention and the fourteenth sample for comparison are made of epoxy resin having a thickness of 35 μm on the upper and lower surfaces, and a through-hole having a diameter of 50 μm exposing the central portion of the upper and lower connection pads In the through hole of the resin layer, the electroless copper plating and the electrolytic copper plating are applied in a predetermined pattern having a thickness of 15 μm using a semi-additive method in the through hole and on the surface of the resin layer. And a signal wiring conductor having a width of 25 μm extending from the through hole to the surface of the resin layer, and a grounding wiring conductor layer surrounding the signal wiring conductor with a spacing of 70 μm therebetween, and A resin layer made of an epoxy resin having a thickness of 35 μm and a ground conductor layer made of a copper plating layer having a thickness of 15 μm were laminated. In the fourth to fifth samples, the signal wiring conductor extends on the cut of the conductor pattern, and in other samples, the signal wiring conductor extends on the outermost conductor pattern. Arranged.
[0054]
Next, a high-frequency signal was input between the upper and lower signal wiring conductors for these samples, and the frequency at which the reflection loss was −20 dB was measured. The results are shown in Table 2.
[0055]
[Table 2]
[0056]
As can be seen from Table 2, the 14th sample for comparison has a reflection loss of −20 dB as low as 6.5 GHz, whereas the 1st to 12th samples of the present invention have a reflection loss of −20 dB. It can be seen that the frequency of 20 dB is 9.5 GHz or more, and a high-frequency signal can be transmitted satisfactorily.
[0057]
【The invention's effect】
According to the wiring board of the present invention, since the through conductor and the conductor pattern electrically independent from the conductor layer are disposed so as to surround the through conductor in the opening of the conductor layer surrounding the through conductor, the through conductor is surrounded. The ratio of the resin in the opening is reduced by the conductor pattern, and the rigidity in the opening does not decrease even if the insulating sheet for the insulating layer is laminated and heated while pressing from above and below to produce a wiring board. The resin in the opening is not greatly deformed by pressing and heating from above and below, and a large dent is not generated on the surface of the insulating substrate corresponding to the opening. Therefore, it is possible to provide a wiring board that can mount electronic components satisfactorily and can be favorably mounted on an external electric circuit board.
[0058]
Further, according to the wiring board of the present invention, when the conductor pattern is an annular shape surrounding the through conductor, the conductor pattern is uniformly arranged over the entire circumference of the through conductor, thereby opening the opening surrounding the through conductor. Corresponding dents on the insulating substrate surface are prevented very well.
[0059]
Further, according to the wiring board of the present invention, when the signal propagating through the through conductor is a high-frequency signal having a frequency of 10 GHz or more, the conductor pattern has a length less than a quarter of the wavelength of the high-frequency signal. When a plurality of electrically independent conductor pieces are arranged in an annular arrangement surrounding the through conductor, it is possible to effectively prevent the resonance of a high frequency signal in the conductor pattern, and thereby a high frequency of 10 GHz or more. Signals can be propagated very efficiently.
[0060]
Furthermore, according to the wiring board of the present invention, as described above, the conductor pattern has an annular shape surrounding a through conductor with a plurality of electrically independent conductor pieces having a length less than a quarter of the wavelength of a high-frequency signal. When the conductor layer and the conductor pattern are arranged in a plurality of layers above and below the insulating layer with respect to the through conductor, the positions of the conductor pieces are the upper and lower conductor patterns. If they are shifted from each other in the circumferential direction of the annular arrangement, the conductor pieces are uniformly arranged around the through conductors, and the deformation of the resin in the opening is more effectively prevented.
[0061]
Further, according to the wiring board of the present invention, when a strip-like wiring conductor is connected to one end of the through conductor, the wiring conductor crosses the region facing the conductor pattern with the insulating layer interposed therebetween. When extending to the surface of the insulating layer, the mismatch of the characteristic impedance of the wiring conductor in the region corresponding to the opening is reduced by electromagnetic coupling with the conductor pattern, and the signal can be efficiently propagated to the wiring conductor. .
[0062]
Further, according to the wiring board of the present invention, the through conductors reach the surface of the insulating base, and the electrodes for external connection are formed on the surface of the insulating base in a region facing the opening with the insulating layer interposed therebetween. When the pad is attached so as to be connected to the through conductor, and the opening is formed larger than the electrode pad, the capacitance between the electrode pad and the conductor layer having the opening is increased. The signal can be satisfactorily propagated from the through conductor to the electrode pad.
[0063]
According to the electronic device of the present invention, since the electronic component is mounted on the wiring board and the electrode of the electronic component and the through conductor are electrically connected, the electronic component is placed on the flat insulating substrate. Can be mounted on the external electric circuit board well. In addition, the mounted electronic component can be operated satisfactorily without signal reflection.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of an embodiment of a wiring board according to the present invention.
2 is a top view of essential parts of a conductor layer 3, a through conductor 4, and a conductor pattern 5 in the wiring board shown in FIG.
FIG. 3 is a partial cross-sectional perspective view taken along the line XX in FIG. 2;
4 is a top view of relevant parts corresponding to FIG. 2 showing an example different from the example shown in FIG. 2;
FIG. 5 is a partial cross-sectional perspective view taken along the line XX in FIG.
[Explanation of symbols]
1: Insulated substrate
2: Insulating layer
3: Conductor layer
3a: wiring conductor for signals
3b: Wiring conductor for grounding or power supply
4: Through conductor
5: Conductor pattern
6: Electronic components
