JP3881523B2

JP3881523B2 - Wiring board and manufacturing method thereof

Info

Publication number: JP3881523B2
Application number: JP2001132726A
Authority: JP
Inventors: 英敏湯川
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2001-04-27
Filing date: 2001-04-27
Publication date: 2007-02-14
Anticipated expiration: 2021-04-27
Also published as: JP2002329973A

Description

【０００１】
【発明の属する技術分野】
本発明は、有機材料系の多層配線基板およびその製造方法に関するものである。
【０００２】
【従来の技術】
従来、半導体素子を搭載するための有機材料系の配線基板として、例えば両面または片面に銅箔から成る配線導体を有するガラス−エポキシ板から成る複数の絶縁層を同じくガラス−エポキシ板から成る接着層を介して積層して成る多層配線基板が用いられている。この有機材料系の多層配線基板においては、その上面から下面にかけて複数の貫通孔が設けられており、貫通孔内壁には各絶縁層を挟んで上下に位置する配線導体同士を電気的に接続するための銅めっき膜から成る貫通導体が被着形成されており、それにより立体的な高密度配線が可能となっている。
【０００３】
なお、このような有機材料系の多層配線基板は、両面または片面に厚みが15〜50μｍ程度の銅箔から成る配線導体が被着形成された厚みが0.1〜0.5ｍｍ程度のガラス−エポキシ板から成る複数の絶縁板を厚みが0.1〜0.2ｍｍ程度のガラス−エポキシ板から成る接着層を介して積層した後、その上面から下面にかけて直径が200〜500μｍ程度の貫通孔をドリル加工により穿孔し、しかる後、貫通孔内壁に厚みが15〜50μｍ程度の銅めっき膜から成る貫通導体を無電解めっき法および電解めっき法により被着させることによって製作されている。
【０００４】
【発明が解決しようとする課題】
ところで、このような有機材料系の多層配線基板においては、その配線密度を更に高めるために貫通孔の直径を例えば75〜130μｍ程度の小さなものとする試みがなされている。このような直径が75〜130μｍ程度の小さな貫通孔を形成するためには例えばレーザーによる穿孔方法が採用される。
【０００５】
しかしながら、従来の有機材料系の多層配線基板においては、各絶縁板および接着層の厚みが0.1〜0.5ｍｍ程度と厚いことから、各絶縁板および接着層を貫通する貫通孔の直径を例えば75〜130μｍ程度の小さなものとすると、この貫通孔の内壁に銅めっき膜から成る貫通導体を被着させる際、貫通導体を被着させるためのめっき液が貫通孔内に良好に入り込みにくくなり、そのため貫通導体が良好に被着されずに貫通導体に断線が発生してしまいやすいという問題点を有していた。
【０００６】
本発明は、かかる従来の問題点に鑑み案出されたものであり、その目的は、貫通孔の直径を例えば75〜130μｍ程度の小さいものとしても貫通導体に断線が発生することがない極めて高密度な配線が可能な配線基板およびその製造方法を提供することにある。
【０００７】
【課題を解決するための手段】
本発明の配線基板は、厚みが０．３５〜０．４５ｍｍの絶縁樹脂板の上下両面に厚みが７〜１２μｍの銅箔から成り、内層配線導体パターンおよび該内層配線導体パターンから電気的に独立したダミー導体パターンを有する内層導体が被着された両面銅張板の前記上下両面に厚みが前記内層導体上で２５〜４５μｍの絶縁樹脂層が被着されているとともに前記絶縁樹脂板、前記内層導体および前記絶縁樹脂層を上下に貫通し、かつ前記絶縁樹脂板においては直径が７５〜１１５μｍでその内壁が略垂直であり、かつ前記絶縁樹脂層においてはその内壁が垂直方向から１０〜３０度の角度で外側に向けて拡がる形状の複数の貫通孔が形成され、該貫通孔の内壁に前記内層導体に接続された貫通導体および前記絶縁樹脂層の表面に前記貫通導体に接続された表層導体がそれぞれめっきにより被着形成されて成ることを特徴とするものである。
【０００８】
また、本発明の配線基板の製造方法は、厚みが０．３５〜０．４５ｍｍの絶縁樹脂板の上下両面に厚みが７〜１２μｍの銅箔から成り、内層配線導体パターンおよび該内層配線導体パターンから電気的に独立したダミー導体パターンを有する内層導体が被着された両面銅張板の前記上下両面に厚みが前記内層導体上で２５〜４５μｍの絶縁樹脂層を被着させるとともに前記絶縁樹脂板、前記内層導体および前記絶縁樹脂層を上下に貫通し、かつ前記絶縁樹脂板においては直径が７５〜１１５μｍでその内壁が略垂直であり、かつ前記絶縁樹脂層においてはその内壁が垂直方向から１０〜３０度の角度で外側に向けて拡がる形状の複数の貫通孔を形成し、次に前記貫通孔の内壁に前記内層導体に接続された貫通導体および前記絶縁樹脂層の表面に前記貫通導体に接続された表層導体をそれぞれめっきにより被着させる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、上述の構成としたことから、貫通孔の内壁に貫通導体を被着させる際、貫通導体を被着させるためのめっき液が貫通孔内に良好に入り込み、その結果、貫通孔の内壁に貫通導体が良好に形成される。
【００１０】
また、本発明の配線基板の製造方法によれば、上述の構成としたことから、貫通孔の内壁に貫通導体を被着させる際、貫通導体を被着させるためのめっき液が貫通孔内に良好に入り込み、その結果、貫通孔の内壁に貫通導体が良好に形成された配線基板を得ることができる。
【００１１】
【発明の実施の形態】
次に、本発明の配線基板について詳細に説明する。
【００１２】
図１は、本発明の配線基板の実施形態の一例を示す部分断面図である。図１において、１は絶縁樹脂板、２Ａ・２Ｂは内層導体、３Ａ・３Ｂは絶縁樹脂層、４は貫通孔、５は貫通導体、６Ａ・６Ｂは表層導体であり、主として絶縁樹脂板１の上下両面に内層導体２Ａ・２Ｂおよび絶縁樹脂層３Ａ・３Ｂが被着されるとともに絶縁樹脂板１および内層導体２Ａ・２Ｂおよび絶縁樹脂層３Ａ・３Ｂを貫通して複数の貫通孔４が設けられ、さらに貫通孔４の内壁に貫通導体５が被着形成されるとともに絶縁樹脂層３Ａ・３Ｂの表面に表層導体６Ａ・６Ｂが被着形成されることにより本発明の配線基板が構成されている。なお、本実施形態例においては、貫通孔４内および絶縁樹脂層３Ａ・３Ｂ上にソルダーレジスト７が設けられている。
【００１３】
絶縁樹脂板１は、本発明の配線基板のコア部材として機能し、例えばガラスクロスやアラミドクロスにエポキシ樹脂やビスマレイミドトリアジン樹脂・ポリフェニレンエーテル樹脂等の樹脂を含浸させた有機系絶縁材料から成る厚みが0.35〜0.45ｍｍの平板であり、その上下両面に厚みが７〜12μｍの銅箔から成る内層導体２Ａ・２Ｂが被着された、いわゆる両面銅張り板を構成している。この絶縁樹脂板１は、その厚みが0.35ｍｍ未満ではその上下面に絶縁樹脂層３Ａ・３Ｂを被着させたり、あるいは絶縁樹脂板１および内層導体２Ａ・２Ｂおよび絶縁樹脂層３Ａ・３Ｂを貫通して複数の貫通孔４を形成したりする際等に熱や外力等の影響で配線基板に反りや変形が発生して配線基板に要求される平坦度を確保できなくなってしまう危険性が大きなものとなり、他方、0.45ｍｍを超えると、後述するように貫通孔４内壁に貫通導体５を形成するとき、貫通孔４内にめっき液が浸入しにくくなり、貫通導体５を良好に形成することが困難となる。したがって、絶縁樹脂板１の厚みは0.35〜0.45ｍｍの範囲に特定される。
【００１４】
なお、絶縁樹脂板１は、ガラスクロスやアラミドクロスに含浸させるエポキシ樹脂やビスマレイミドトリアジン樹脂・ポリフェニレンエーテル樹脂等の樹脂中にシリカやアルミナあるいはアラミド樹脂等から成るフィラーをガラスクロスやアラミドクロス等の繊維部分と樹脂部分とでレーザー光の透過度が略同等となる程度に含有させておけば、後述するように絶縁樹脂板１にレーザー光で貫通孔４を穿孔する際に、貫通孔４を絶縁樹脂板１に略均一な大きさで良好に形成することが可能となる。したがって、絶縁樹脂板１のガラスクロスやアラミドクロスに含浸させるエポキシ樹脂やビスマレイミドトリアジン樹脂・ポリフェニレンエーテル樹脂等の樹脂中にはシリカやアルミナあるいはアラミド樹脂等から成るフィラーをガラスクロスやアラミドクロス等の繊維部分と樹脂部分とでレーザー光の透過度が略同等となるように含有させておくことが好ましい。
【００１５】
また、絶縁樹脂板１の上下面に被着された内層導体２Ａ・２Ｂは、銅箔から成り、主として電源層やグランド層として機能する内層配線導体パターンＷとこの内層配線導体パターンＷから電気的に独立したダミー導体パターンＤとを有し、その厚みが７〜12μｍ、その表面の中心線平均粗さＲａが0.2〜２μｍ程度である。内層導体２Ａ・２Ｂは、その厚みが７μｍ未満の場合、電源層やグランド層としての内層配線導体パターンＷに対して十分な電気特性を付与することができず、他方、12μｍを超える場合、後述するように絶縁樹脂板１と内層導体２Ａ・２Ｂおよび絶縁樹脂層３Ａ・３Ｂとを貫通する貫通孔４をレーザー加工により穿孔する場合に、貫通孔４を安定して形成することが困難となる。したがって、内層導体２Ａ・２Ｂの厚みは、７〜12μｍの範囲に特定される。
【００１６】
なお、内層導体２Ａ・２Ｂは、貫通孔４により貫通されるとともに後述する貫通導体５に接する内層配線導体パターンＷまたはダミー導体パターンＤを全ての貫通孔４に対応して有するように形成しておくと、貫通孔４をレーザー加工により穿孔する際に全ての貫通孔４においてレーザー光の吸収反射を略同じとして全ての貫通孔４を略均一な大きさおよび形状に形成することができる。したがって、内層導体２Ａ・２Ｂは、貫通孔４により貫通される内層配線導体パターンＷまたはダミー導体パターンＤを全ての貫通孔４に対応して有するように形成しておくことが好ましい。この場合、ダミー導体パターンＤは、その直径が貫通孔４の直径よりも40〜100μｍ程度大きな略円形のパターンとすればよく、内層配線導体パターンＷとの間に30〜60μｍ程度の幅の間隔を設ければよい。ダミー導体パターンＤの直径が貫通孔４の直径よりも40μｍ未満大きな場合には、レーザー加工により貫通孔４を穿孔する際にダミー導体パターンＤを正確に貫通することが困難となり、他方、100μｍを超えて大きな場合には、内層配線導体パターンＷの面積を広く採ることが困難となる。また、ダミー導体パターンＤと内層配線導体パターンＷとの間隔が30μｍ未満の場合には、ダミー導体パターンＤと内層配線導体パターンＷとの間の電気的絶縁が良好に保てなくなる傾向にあり、他方、60μｍを超えると、内層配線導体パターンＷの面積を広く採ることが困難となる。
【００１７】
また、内層導体２Ａ・２Ｂは、その表面の中心線平均粗さＲａが0.2μｍ未満の場合、内層導体２Ａ・２Ｂと絶縁樹脂層３Ａ・３Ｂとが強固に密着せずに内層導体２Ａ・２Ｂと絶縁樹脂層３Ａ・３Ｂとの間で剥離が発生しやすくなる傾向にあり、他方２μｍを超えると、そのような粗い面を安定かつ効率良く形成することが困難となる傾向にある。したがって、内層導体２Ａ・２Ｂ表面の中心線平均粗さＲａは0.2〜２μｍの範囲が好ましい。
【００１８】
また、絶縁樹脂板１の上下面に被着された絶縁樹脂層３Ａ・３Ｂはエポキシ樹脂やビスマレイミドトリアジン樹脂・ポリフェニレンエーテル樹脂等の熱硬化性樹脂から成り、レーザー光に対する分解度合いが絶縁樹脂板１よりも大きく、その表面に表層導体６Ａ・６Ｂが被着されている。絶縁樹脂層３Ａ・３Ｂは、互いに絶縁すべき内層導体２Ａ・２Ｂと表層導体６Ａ・６Ｂとを電気的に絶縁するための絶縁間隔を提供するためのものであり、その厚みが内層導体２Ａ・２Ｂ上で25〜45μｍである。この絶縁樹脂層３Ａ・３Ｂは、その厚みが内層導体２Ａ・２Ｂ上で25μｍ未満の場合、互いに絶縁すべき内層導体２Ａ・２Ｂと表層導体６Ａ・６Ｂとを電気的に良好に絶縁することができなくなり、他方、45μｍを超えると、絶縁樹脂板１および内層導体２Ａ・２Ｂならびに絶縁樹脂層３Ａ・３Ｂを貫通する貫通孔４をレーザー加工により穿孔する際に貫通孔４を良好に形成することが困難となる。したがって、絶縁層３Ａ・３Ｂの厚みは内層導体２Ａ・２Ｂ上で25〜45μｍの範囲に特定される。
【００１９】
表層導体６Ａ・６Ｂは、厚みが８〜30μｍの銅めっき膜から成り、電源配線およびグランド配線および信号配線を具備する表層配線パターンを形成している。そして、例えば上面側の表層導体６Ａの露出する一部に図示しない電子部品の電極が半田を介して接続されるとともに、下面側の表層導体６Ｂの露出する一部が図示しない他の配線基板等に半田を介して接続される。
【００２０】
これらの表層導体６Ａ・６Ｂは、その厚みが８μｍ未満であると、表層配線パターンの電気抵抗が高いものとなり、他方、30μｍを超えると、表層配線パターンを高密度に形成することが困難となる。したがって、表層導体６Ａ・６Ｂの厚みは、8〜30μｍの範囲が好ましい。
【００２１】
さらに、本発明の配線基板においては、絶縁樹脂板１および内層導体２Ａ・２Ｂおよび絶縁樹脂層３Ａ・３Ｂを貫通して貫通孔４が形成されており、この貫通孔４の内壁に貫通導体５が被着形成されている。貫通孔４は、貫通導体５を絶縁樹脂層３Ａの上面から絶縁樹脂層３Ｂの下面にかけて導出させるための導出路を提供するためのものであり、例えばレーザー加工により穿孔されている。この貫通孔４は、絶縁樹脂板１においては直径が75〜115μｍでその内壁が略垂直であり、絶縁樹脂層３Ａ・３Ｂにおいてはその内壁が垂直方向から10〜30の角度で外側に向けて拡がる形状となっている。
【００２２】
このように、本発明の配線基板によれば、貫通孔４はその直径が絶縁樹脂板１において75〜115μｍと小さく、かつその内壁が絶縁樹脂層３Ａ・３Ｂにおいて垂直方向から10〜30の角度で外側に向けて拡がる形状となっているいことから、貫通導体５および表層導体６Ａ・６Ｂを高密度で配置することができ、それにより極めて高密度な配線を有する配線基板を得ることができる。
【００２３】
また、貫通孔４はその直径が絶縁樹脂板１において75〜115μｍと小さいものの、その内壁が絶縁樹脂板１においては略垂直でかつ絶縁樹脂層３Ａ・３Ｂにおいては垂直方向から10〜30の角度で外側に向けて拡がる形状となっているいことから、後述するように貫通孔４内壁に貫通導体５を被着形成する際に、貫通導体５を形成するためのめっき液が貫通孔４の内部に良好に入り込み、その結果、貫通孔４内に貫通導体５を良好に形成することができる。
【００２４】
なお、絶縁樹脂板１における貫通孔４の直径が75μｍ未満の場合、貫通孔４内壁に貫通導体５を被着形成する際に、貫通導体５を形成するためのめっき液が貫通孔４の内部に良好に入り込まずに貫通孔４内壁に貫通導体５を良好に形成することが困難となり、他方、115μｍを超えると、貫通導体５および表層導体６Ａ・６Ｂを高密度で配置することが困難となる。したがって、絶縁樹脂板１における貫通孔４の直径は、75〜115μｍの範囲に特定される。
【００２５】
また、絶縁樹脂板１における貫通孔４の内壁が略垂直でない場合、貫通孔４内壁に貫通導体５を被着形成する際に貫通孔４の内部に気泡が取り残されやすく、そのため貫通導体５を形成するためのめっき液が気泡が取り残された部分に良好に届かずに貫通孔４内壁に貫通導体５を良好に形成することが困難となる。したがって、絶縁樹脂板１における貫通孔４の内壁は略垂直であることに特定される。
【００２６】
また、貫通孔４の内壁が絶縁樹脂層３Ａ・３Ｂにおいて外側に向けて拡がる角度が垂直方向から10度未満の場合、貫通孔４内壁に貫通導体５を被着形成する際に、貫通導体５を形成するためのめっき液が貫通孔４の内部に良好に入り込まずに貫通孔４内壁に貫通導体５を良好に形成することが困難となり、他方、30度を超えるとそのような角度で内壁が拡がる貫通孔４を安定して効率よく形成することが困難となる。したがって、貫通孔４の内壁が絶縁樹脂層３Ａ・３Ｂにおいて外側に向けて拡がる角度は、垂直方向から10〜30度の範囲に特定される。
【００２７】
貫通孔４の内壁に被着形成された貫通導体５は、厚みが８〜25μｍ程度の銅めっき膜から成り、絶縁樹脂板１および絶縁樹脂層３Ａ・３Ｂを挟んで上下に位置する内層導体２Ａ・２Ｂおよび表層導体６Ａ・６Ｂ同士を互いに電気的に接続する接続導体として機能する。
【００２８】
貫通導体５は、その厚みが８μｍ未満では、貫通導体５の電気抵抗が高いものとなりすぎる傾向にあり、他方、25μｍを超えると、この貫通導体５が被着された貫通孔４の内部に後述するソルダーレジスト７を良好に充填することが困難となる。したがって、貫通導体５の厚みは、８〜25μｍの範囲であることが好ましい。
【００２９】
さらに、絶縁樹脂層３Ａ・３Ｂの表面および貫通孔４の内部には、エポキシ樹脂やビスマレイミドトリアジン樹脂・ポリフェニレンエーテル樹脂等の熱硬化性樹脂から成るソルダーレジスト７が被着および充填されている。ソルダーレジスト７は、貫通導体５および表層導体６Ａ・６Ｂを保護するとともに表層導体６Ａ・６Ｂにおける表層配線パターン同士を電気的に良好に絶縁するための保護層として機能し、表層導体６Ａ・６Ｂの一部を露出させる所定のパターンに被着形成されている。
【００３０】
なお、ソルダーレジスト７は、その表層導体６Ａ・６Ｂ上における厚みが10μｍ未満であると、表層導体６を良好に保護することができなくなるとともに表層導体６Ａ・６Ｂにおける表層配線パターン同士を電気的に良好に絶縁することができなくなる傾向にあり、他方、40μｍを超えると、ソルダーレジスト７を所定のパターンに形成することが困難となる傾向にある。したがって、ソルダーレジストの表層導体６Ａ・６Ｂ上における厚みは、10〜40μｍの範囲が好ましい。
【００３１】
かくして、本発明の配線基板によれば、貫通孔４内に貫通導体５を良好に形成することができ、それにより貫通導体５に断線が発生することのない極めて高密度な配線の配線基板を提供することができる。
【００３２】
次に、図１に示した配線基板を本発明の製造方法により製造する方法について図２（ａ）〜（ｆ）を参照して説明する。
【００３３】
まず、図２（ａ）に部分断面図で示すように、例えばガラスクロスやアラミドクロスにエポキシ樹脂やビスマレイミドトリアジン樹脂・ポリフェニレンエーテル樹脂等の樹脂を含浸させた有機系絶縁材料から成る厚みが0.35〜0.45ｍｍの絶縁樹脂板１の上下面に厚みが７〜12μｍの銅箔から成る内層導体２Ａ・２Ｂが被着形成された両面銅張板を準備する。なお、内層導体２Ａ・２Ｂはその表面の中心線平均粗さＲａが0.2〜２μｍ程度となるように、その表面を粗化しておく。
【００３４】
絶縁樹脂板１は、その厚みが0.35ｍｍ未満ではその上下面に絶縁樹脂層３Ａ・３Ｂを被着させたり、あるいは絶縁樹脂板１および内層導体２Ａ・２Ｂおよび絶縁樹脂層３Ａ・３Ｂを貫通して複数の貫通孔４を形成する際等に熱や外力等の影響で配線基板に反りや変形が発生して配線基板に要求される平坦度を確保できなくなってしまう危険性が大きなものとなり、他方、0.45ｍｍを超えると、後述するように貫通孔４内壁に貫通導体５を形成するとき、貫通孔４内にめっき液が浸入しにくくなり、貫通導体５に断線が発生しやすくなる。したがって、絶縁樹脂板１の厚みは0.35〜0.45ｍｍの範囲に特定される。
【００３５】
また、内層導体２Ａ・２Ｂは、その厚みが７μｍ未満の場合、内層導体２Ａ・２Ｂの導体パターンに電源層やグランド層としての十分な電気特性を付与することができず、他方、12μｍを超える場合、後述するように絶縁樹脂板１と内層導体２Ａ・２Ｂおよび絶縁樹脂層３Ａ・３Ｂとを貫通する貫通孔４をレーザー加工により穿孔する場合に、貫通孔４を安定して形成することが困難となる。したがって、内層導体２Ａ・２Ｂの厚みは、７〜12μｍの範囲に特定される。
【００３６】
また、内層導体２Ａ・２Ｂは、その表面の中心線平均粗さＲａが0.2μｍ未満の場合、後述するように、絶縁樹脂板１の上下面に絶縁樹脂層３Ａ・３Ｂを被着させる際に内層導体２Ａ・２Ｂと絶縁樹脂層３Ａ・３Ｂとが強固に密着せずに内層導体２Ａ・２Ｂと絶縁樹脂層３Ａ・３Ｂとの間で剥離が発生しやすくなる傾向にあり、他方２μｍを超えると、そのような粗い面を安定かつ効率良く形成することが困難となる傾向にある。したがって、内層導体２Ａ・２Ｂ表面の中心線平均粗さＲａは0.2〜２μｍの範囲が好ましい。
【００３７】
さらに、内層導体２Ａ・２Ｂは貫通孔４が形成される位置に貫通孔４により貫通されるとともに後述する貫通導体５に接する導体パターンを全ての貫通孔４に対応して設けておくと、レーザー加工により貫通孔４を形成する際に全ての貫通孔４においてレーザー光の吸収反射が均一となり、全ての貫通孔４を略均一に形成することができる。したがって、内層導体２Ａ・２Ｂは貫通孔４が形成される位置に貫通孔４により貫通される導体パターンを全ての貫通孔４に対応して設けておくことが好ましい。
【００３８】
このような内層導体２Ａ・２Ｂは、絶縁樹脂板１の上下全面に厚みが８〜16μｍ程度の銅箔を貼着するとともに、この銅箔上に感光性のドライフィルムレジストを被着させ、次にこの感光性ドライフィルムレジストを従来周知のフォトリソグラフィー技術により露光・現像して導体パターン形成位置にドライフィルムレジストを有するエッチングマスクを形成し、次にエッチングマスクから露出した銅箔を塩化第２銅水溶液もしくは塩化第２鉄水溶液から成るエッチング液を用いてエッチング除去し、最後にエッチングマスクを剥離した後、塩化第２銅水溶液に蟻酸が含有された粗化液を用いてその表面をエッチングして粗化することによって形成される。
【００３９】
次に、図２（ｂ）に部分断面図で示すように、両面銅張板11の上下面にその厚みが内層導体２Ａ・２Ｂ上で25〜45μｍの絶縁樹脂層３Ａ・３Ｂを被着形成する。この絶縁樹脂層３Ａ・３Ｂはエポキシ樹脂やビスマレイミドトリアジン樹脂・ポリフェニレンエーテル樹脂等の熱硬化型の樹脂から成り、炭酸ガスレーザー等のレーザー光に対する分解度合いが絶縁樹脂板１よりも大きい。
【００４０】
この絶縁樹脂層３Ａ・３Ｂは、その厚みが内層導体２Ａ・２Ｂ上で25μｍ未満の場合、互いに絶縁すべき内層導体２Ａ・２Ｂと表層導体６Ａ・６Ｂとを電気的に良好に絶縁することができなくなり、他方、45μｍを超えると、絶縁樹脂板１および内層導体２Ａ・２Ｂならびに絶縁樹脂層３Ａ・３Ｂを貫通する貫通孔４をレーザー加工により穿孔する際に貫通孔４を良好に形成することが困難となる。したがって、絶縁層３Ａ・３Ｂの厚みは内層導体２Ａ・２Ｂ上で25〜45μｍの範囲に特定される。
【００４１】
なお、絶縁樹脂板１の上下面に内層導体２Ａ・２Ｂが被着されて成る両面銅張板の上下面に絶縁樹脂層３Ａ・３Ｂを被着形成するには、半硬化状態の熱硬化性樹脂のフィルムを両面銅張板の上下両面に真空ラミネーターで仮圧着した後、これを熱処理して硬化させる方法が採用される。
【００４２】
次に図２（ｃ）に部分断面図で示すように、レーザー加工により絶縁樹脂層３Ａ・３Ｂおよび内層導体２Ａ・２Ｂおよび絶縁樹脂板１を貫通する複数の貫通孔４を穿孔する。貫通孔４は絶縁樹脂板１においは直径が75〜115μｍでその内壁が略垂直であり、絶縁樹脂層３Ａ・３Ｂにおいてはその内壁が垂直方向から10〜30度の角度で外側に向けて拡がった形状とする。この場合、絶縁樹脂層３Ａ・３Ｂのレーザー光に対する分解度合いを絶縁樹脂板１よりも大きくしておくことで、貫通孔４の内壁を絶縁樹脂板１においては略垂直で絶縁樹脂層３Ａ・３Ｂにおいては垂直方向から10〜30度の角度で外側に向けて拡がった形状とすることができる。
【００４３】
このように、貫通孔４の直径を絶縁樹脂板１において75〜115μｍと小さいものとするとともに貫通孔４の内壁を絶縁樹脂層３Ａ・３Ｂにおいて垂直方向から10〜30度の角度で外側に向けて拡がった形状とすることから、後述するように貫通導体５および表層導体６Ａ・６Ｂを形成する際に貫通導体５および表層導体６Ａ・６Ｂを高密度で配置することができ、それにより高密度な配線基板を得ることができる。また、貫通孔４はその直径が絶縁樹脂板１において75〜115μｍと小さいものの、その内壁が絶縁樹脂板１においては略垂直でかつ絶縁樹脂層３Ａ・３Ｂにおいては垂直方向から10〜30度の角度で外側に向けて拡がる形状となっているいことから、後述するように貫通孔４内壁に貫通導体５を被着形成する際に、貫通導体５を形成するためのめっき液が貫通孔４の内部に良好に入り込み、その結果、貫通孔４内に貫通導体５を良好に形成することができる。
【００４４】
なお、絶縁樹脂板１における貫通孔４の直径が75μｍ未満の場合、貫通孔４内壁に貫通導体５を被着形成する際に、貫通導体５を形成するためのめっき液が貫通孔４の内部に良好に入り込まず、貫通孔４内壁に貫通導体５を良好に形成することが困難となり、他方、115μｍを超えると、貫通導体５および表層導体６Ａ・６Ｂを高密度で配置することが困難となる。したがって、絶縁樹脂板１における貫通孔４の直径は、75〜115μｍの範囲に特定される。
【００４５】
また、絶縁樹脂板１における貫通孔４の内壁が略垂直でない場合、貫通孔４内壁に貫通導体５を被着形成する際に貫通孔４の内部に気泡が取り残されやすく、そのため貫通導体５を形成するためのめっき液が気泡が取り残された部分に良好に届かずに貫通孔４内壁に貫通導体５を良好に形成することが困難となる。したがって、絶縁樹脂板１における貫通孔４の内壁は略垂直であることに特定される。
【００４６】
また、貫通孔４の内壁が絶縁樹脂層３Ａ・３Ｂにおいて外側に向けて拡がる角度が垂直方向から10度未満の場合、貫通孔４内壁に貫通導体５を被着形成する際に、貫通導体５を形成するためのめっき液が貫通孔４の内部に良好に入り込まずに貫通孔４内壁に貫通導体５を良好に形成することが困難となり、他方、30度を超えるとそのような角度で内壁が拡がる貫通孔４を安定して効率よく形成することが困難となる。したがって、貫通孔４の内壁が絶縁樹脂層３Ａ・３Ｂにおいて外側に向けて拡がる角度は、垂直方向から10〜30度の範囲に特定される。
【００４７】
なお、絶縁樹脂層３Ａ・３Ｂおよび内層導体２Ａ・２Ｂおよび絶縁樹脂板１に貫通孔４を形成するには、絶縁樹脂層３Ａ・３Ｂ上に例えばレーザー光のエネルギーを良好に吸収する黒色もしくは黒色に近い色を有する樹脂から成るレーザー加工用シートを貼着し、このレーザー加工用シートの上から７〜12ｍＪの出力の炭酸ガスレーザー光を50〜500μ秒のパルス幅で所定の位置に照射して貫通孔４を穿孔する方法が採用される。このとき、炭酸ガスレーザー光の出力が７ｍＪ未満だと貫通孔４を十分な大きさに穿孔することが困難となる傾向にあり、他方、12ｍＪを超えると絶縁樹脂層３Ａ・３Ｂにおける貫通孔４の孔径が大きくなりすぎてしまう傾向にある。したがって、照射する炭酸ガスレーザー光は、その出力が７〜12ｍＪでパルス幅が50〜500μ秒の範囲であることが好ましい。なお、レーザー加工用シートは、貫通孔４を穿孔した後に剥離する。このように貫通孔４をレーザー加工により形成することにより、絶縁樹脂板１においては直径が75〜115μｍでその内壁が略垂直であり、かつ絶縁樹脂層３Ａ・３Ｂにおいてその内壁が垂直方向から10〜30度の角度で外側に向けて拡がる形状の貫通孔４を容易に形成することができる。
【００４８】
次に、図２（ｄ）に部分断面図で示すように、貫通孔４内壁および絶縁樹脂層３Ａ・３Ｂの表面に厚みが１〜３μｍの無電解銅めっき膜から成るめっき膜13Ａを被着させる。なお、無電解めっき膜から成るめっき膜13Ａを被着させるには、例えば塩化アンモニウム系酢酸パラジウムを含有するパラジウム活性液を使用して貫通孔４内壁および絶縁樹脂層３Ａ・３Ｂの表面にパラジウム触媒を付着させるとともに、その上に硫酸銅系の無電解銅めっき液を用いて無電解銅めっき膜を被着させればよい。貫通孔４はその直径が絶縁樹脂板１において75〜115μｍと小さいものの、その内壁が絶縁樹脂板１においては略垂直でかつ絶縁樹脂層３Ａ・３Ｂにおいては垂直方向から10〜30度の角度で外側に向けて拡がる形状となっているいことから、貫通孔４内に無電解銅めっき液が良好に浸入し、その結果、貫通孔４内壁および絶縁樹脂層３Ａ・３Ｂの表面に無電解銅めっき膜を略均一な厚みに良好に被着させることができる。なお、無電解銅めっき膜から成るめっき膜13Ａを被着させる前に絶縁樹脂層３Ａ・３Ｂ表面および貫通孔４内壁を例えば過マンガン酸カリウム溶液や過マンガン酸ナトリウム溶液から成る粗化液を用いてその中心線平均粗さＲａが0.2〜２μｍ程度になるように粗化しておくと無電解銅めっき膜から成るめっき膜13Ａを強固に被着させることができる。したがって、無電解銅めっき膜から成るめっき膜13Ａを被着させる前に絶縁樹脂層３Ａ・３Ｂ表面および貫通孔４内壁を例えば過マンガン酸カリウム溶液や過マンガン酸ナトリウム溶液から成る粗化液を用いてその中心線平均粗さＲａが0.2〜２μｍ程度になるように粗化しておくことが好ましい。
【００４９】
次に、図２（ｅ）に部分断面図で示すように、絶縁層３Ａ・３Ｂ上の無電解銅めっき膜上にめっき用マスク14を被着させるとともに、めっき用マスク14から露出した無電解銅めっき膜上に厚みが10〜35μｍ程度の電解銅めっき膜を被着させ、貫通孔４の内壁および絶縁樹脂層３Ａ・３Ｂ表面の導体パターン形成部位が選択的に厚く被着された無電解めっき膜と電解銅めっき膜とから成るめっき膜13Ｂを形成する。
【００５０】
なお、めっき用マスク14は、例えば感光性ドライフィルムレジストを絶縁樹脂層３Ａ・３Ｂ上の無電解銅めっき膜上に被着させるとともに、このドライフィルムレジストをフォトリソグラフィー技術により露光・現像して所定のパターンに加工することによって形成する。
【００５１】
また、電解銅めっき膜を被着させるための電解銅めっき液としては、例えば、硫酸銅系から成る電解銅めっき液を用いればよい。このとき、貫通孔４はその直径が絶縁樹脂板１において75〜115μｍと小さいものの、その内壁が絶縁樹脂板１においては略垂直でかつ絶縁樹脂層３Ａ・３Ｂにおいては垂直方向から10〜30の角度で外側に向けて拡がる形状となっているいことから、貫通孔４内に電解銅めっき液が良好に浸入し、その結果、貫通孔４内壁および絶縁樹脂層３Ａ・３Ｂの表面に電解銅めっき膜が略均一な厚みに良好に被着される。
【００５２】
次に、図２（ｆ）に部分断面図で示すように、めっきマスク14を剥離するとともにめっきマスク14の下にあった無電解銅めっき膜が消滅するまで無電解銅めっき膜および電解銅めっき膜をエッチングし、貫通孔４内壁に貫通導体５を形成するとともに絶縁樹脂層３Ａ・３Ｂの表面に表層導体６Ａ・６Ｂを形成する。
【００５３】
なお、無電解銅めっき膜および電解銅めっき膜をエッチングするには、塩化第２銅水溶液または塩化第２鉄水溶液から成るエッチング液を用いればよい。
【００５４】
最後に、絶縁樹脂層３Ａ・３Ｂの表面および貫通孔４の内部にエポキシ樹脂やビスマレイミドトリアジン樹脂・ポリフェニレンエーテル等の熱硬化性樹脂から成るソルダーレジスト７を被着および充填させることにより図１に示す本発明の配線基板が完成する。
【００５５】
なお、ソルダーレジスト７は、ソルダーレジスト７用の感光性の樹脂ペーストを従来周知のスクリーン印刷法を採用して絶縁層３Ａ側および３Ｂ側から貫通孔４を埋めるように印刷塗布し、これを従来周知のフォトリソグラフィー技術を採用して所定のパターンに露光・現像することによって形成される。このとき、貫通孔４は、絶縁樹脂層３Ａ・３Ｂにおいてその内壁が垂直方向から10〜30度の角度で外側に向けて拡がる形状であることから、貫通孔４内にソルダーレジスト７用の樹脂ペーストが良好に浸入し、その結果、貫通孔４内をソルダーレジスト７で良好に充填することができる。
【００５６】
かくして、本発明の配線基板の製造方法によれば、貫通導体５に断線が発生することがなく、極めて高密度な配線が可能な配線基板を得ることができる。
【００５７】
【発明の効果】
本発明の配線基板によれば、厚みが０．３５〜０．４５ｍｍの絶縁樹脂板の上下両面に厚みが７〜１２μｍの銅箔から成り、内層配線導体パターンおよび該内層配線導体パターンから電気的に独立したダミー導体パターンを有する内層導体が被着された両面銅張板の前記上下両面に厚みが前記内層導体上で２５〜４５μｍの絶縁樹脂層が被着されているとともに前記絶縁樹脂板、前記内層導体および前記絶縁樹脂層を上下に貫通し、かつ前記絶縁樹脂板においては直径が７５〜１１５μｍでその内壁が略垂直であり、かつ前記絶縁樹脂層においてはその内壁が垂直方向から１０〜３０度の角度で外側に向けて拡がる形状の複数の貫通孔が形成され、該貫通孔の内壁に前記内層導体に接続された貫通導体および前記絶縁樹脂層の表面に前記貫通導体に接続された表層導体がそれぞれめっきにより被着形成されて成ることから、貫通孔内壁に貫通導体を被着させる際、貫通導体を被着させるためのめっき液が貫通孔内に良好に入り込み、その結果、貫通孔の内壁に貫通導体が良好に形成され、貫通導体に断線が発生することのない高密度配線の配線基板を提供することができる。
【００５８】
また、本発明の配線基板の製造方法によれば、厚みが０．３５〜０．４５ｍｍの絶縁樹脂板の上下両面に厚みが７〜１２μｍの銅箔から成り、内層配線導体パターンおよび該内層配線導体パターンから電気的に独立したダミー導体パターンを有する内層導体が被着された両面銅張板の前記上下両面に厚みが前記内層導体上で２５〜４５μｍの絶縁樹脂層を被着させるとともに前記絶縁樹脂板、前記内層導体および前記絶縁樹脂層を上下に貫通し、かつ前記絶縁樹脂板においては直径が７５〜１１５μｍでその内壁が略垂直であり、かつ前記絶縁樹脂層においてはその内壁が垂直方向から１０〜３０度の角度で外側に向けて拡がる形状の複数の貫通孔を形成し、次に前記貫通孔の内壁に前記内層導体に接続された貫通導体および前記絶縁樹脂層の表面に前記貫通導体に接続された表層導体をそれぞれめっきにより被着させることから、貫通孔の内壁に貫通導体を被着させる際、貫通導体を被着させるためのめっき液が貫通孔内に良好に入り込み、その結果、貫通孔の内壁に貫通導体が良好に形成され、貫通導体に断線が発生することのない高密度配線の配線基板を得ることができる。
【図面の簡単な説明】
【図１】本発明の配線基板の実施形態の一例を示す部分断面図である。
【図２】（ａ）〜（ｆ）は、本発明の配線基板の製造方法を説明するための工程毎の部分断面図である。
【符号の説明】
１・・・・・・・絶縁樹脂板
２Ａ・２Ｂ・・・内層導体
３Ａ・３Ｂ・・・絶縁樹脂層
４・・・・・・・貫通孔
５・・・・・・・貫通導体
６Ａ・６Ｂ・・・表層導体[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an organic material-based multilayer wiring board and a method for manufacturing the same.
[0002]
[Prior art]
Conventionally, as an organic material-based wiring board for mounting a semiconductor element, for example, a plurality of insulating layers made of glass-epoxy plates having wiring conductors made of copper foil on both sides or one side are also adhesive layers made of glass-epoxy plates. A multilayer wiring board is used which is laminated through the two. In this organic material-based multilayer wiring board, a plurality of through holes are provided from the upper surface to the lower surface, and the wiring conductors positioned above and below are electrically connected to the inner wall of the through hole with each insulating layer interposed therebetween. For this reason, a through conductor made of a copper plating film is deposited to enable three-dimensional high-density wiring.
[0003]
In addition, such an organic material-based multilayer wiring board is formed from a glass-epoxy plate having a thickness of about 0.1 to 0.5 mm in which wiring conductors made of copper foil having a thickness of about 15 to 50 μm are deposited on both sides or one side. After laminating a plurality of insulating plates through an adhesive layer made of a glass-epoxy plate having a thickness of about 0.1 to 0.2 mm, a through hole having a diameter of about 200 to 500 μm is drilled from the upper surface to the lower surface by drilling, Thereafter, a through conductor made of a copper plating film having a thickness of about 15 to 50 μm is deposited on the inner wall of the through hole by an electroless plating method and an electrolytic plating method.
[0004]
[Problems to be solved by the invention]
By the way, in such an organic material-based multilayer wiring board, an attempt has been made to make the diameter of the through hole as small as about 75 to 130 μm in order to further increase the wiring density. In order to form such a small through hole having a diameter of about 75 to 130 μm, for example, a laser drilling method is employed.
[0005]
However, in the conventional organic material-based multilayer wiring board, since the thickness of each insulating plate and the adhesive layer is as thick as about 0.1 to 0.5 mm, the diameter of the through-hole penetrating each insulating plate and the adhesive layer is, for example, 75 to If it is as small as about 130 μm, when depositing a through conductor made of a copper plating film on the inner wall of this through hole, the plating solution for depositing the through conductor is less likely to penetrate into the through hole. There has been a problem that the conductor is not satisfactorily deposited and breakage of the through conductor is likely to occur.
[0006]
The present invention has been devised in view of such conventional problems, and an object of the present invention is extremely high in that no breakage occurs in the through conductor even when the diameter of the through hole is small, for example, about 75 to 130 μm. It is an object of the present invention to provide a wiring board capable of high-density wiring and a manufacturing method thereof.
[0007]
[Means for Solving the Problems]
The wiring board of the present invention is made of copper foil having a thickness of 7 to 12 μm on both upper and lower surfaces of an insulating resin plate having a thickness of 0.35 to 0.45 mm, and is electrically independent from the inner layer wiring conductor pattern and the inner layer wiring conductor pattern. An insulating resin layer having a thickness of 25 to 45 μm is deposited on the upper and lower surfaces of the double-sided copper clad plate on which the inner layer conductor having the dummy conductor pattern is deposited, and the insulating resin plate and the inner layer The conductor and the insulating resin layer are vertically penetrated, the insulating resin plate has a diameter of 75 to 115 μm and its inner wall is substantially vertical, and the insulating resin layer has an inner wall of 10 to 30 degrees from the vertical direction. A plurality of through-holes having a shape extending outward at an angle of about 5 mm are formed. A through-conductor connected to the inner-layer conductor on the inner wall of the through-hole and a surface of the insulating resin layer in contact with the through-conductor. Is characterized in that has been surface conductor is formed by deposited and formed by plating, respectively.
[0008]
In addition, the method for manufacturing a wiring board according to the present invention comprises a copper foil having a thickness of 7 to 12 μm on both upper and lower surfaces of an insulating resin plate having a thickness of 0.35 to 0.45 mm, and an inner layer wiring conductor pattern and the inner layer wiring conductor pattern. An insulating resin layer having a thickness of 25 to 45 μm is deposited on the upper and lower surfaces of the double-sided copper-clad plate on which the inner layer conductor having a dummy conductor pattern electrically independent from the upper surface is applied, and the insulating resin plate The inner conductor and the insulating resin layer penetrate vertically, and the insulating resin plate has a diameter of 75 to 115 μm and the inner wall thereof is substantially vertical, and the inner wall of the insulating resin layer is 10 from the vertical direction. A plurality of through-holes having a shape extending outward at an angle of ˜30 degrees are formed, and then on the inner wall of the through-hole, the through-conductor connected to the inner-layer conductor and the surface of the insulating resin layer Respectively by plating the connected surface conductor serial through conductor is characterized in that the depositing.
[0009]
According to the wiring board of the present invention, since the above-described configuration is adopted, when the through conductor is deposited on the inner wall of the through hole, the plating solution for depositing the through conductor enters the through hole satisfactorily. As a result, the through conductor is favorably formed on the inner wall of the through hole.
[0010]
Further, according to the method for manufacturing a wiring board of the present invention, since the above-described configuration is adopted, when the through conductor is deposited on the inner wall of the through hole, the plating solution for depositing the through conductor is placed in the through hole. As a result, it is possible to obtain a wiring board in which through conductors are well formed on the inner wall of the through hole.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Next, the wiring board of the present invention will be described in detail.
[0012]
FIG. 1 is a partial cross-sectional view showing an example of an embodiment of a wiring board according to the present invention. In FIG. 1, 1 is an insulating resin plate, 2A and 2B are inner layer conductors, 3A and 3B are insulating resin layers, 4 is a through hole, 5 is a through conductor, and 6A and 6B are surface layer conductors. Inner layer conductors 2A and 2B and insulating resin layers 3A and 3B are attached to both upper and lower surfaces, and a plurality of through holes 4 are provided through insulating resin plate 1, inner layer conductors 2A and 2B, and insulating resin layers 3A and 3B. Furthermore, the through conductor 5 is formed on the inner wall of the through hole 4, and the surface layer conductors 6A and 6B are formed on the surfaces of the insulating resin layers 3A and 3B, whereby the wiring board of the present invention is configured. . In this embodiment, a solder resist 7 is provided in the through hole 4 and on the insulating resin layers 3A and 3B.
[0013]
The insulating resin plate 1 functions as a core member of the wiring board of the present invention. For example, a thickness made of an organic insulating material in which a glass cloth or an aramid cloth is impregnated with a resin such as an epoxy resin, a bismaleimide triazine resin, or a polyphenylene ether resin. Is a flat plate having a thickness of 0.35 to 0.45 mm, and constitutes a so-called double-sided copper-clad plate in which inner layer conductors 2A and 2B made of copper foil having a thickness of 7 to 12 μm are deposited on both upper and lower surfaces. If the thickness of the insulating resin plate 1 is less than 0.35 mm, the insulating resin layers 3A and 3B are attached to the upper and lower surfaces thereof, or the insulating resin plate 1, the inner layer conductors 2A and 2B, and the insulating resin layers 3A and 3B are penetrated. When the plurality of through holes 4 are formed, the wiring board is warped or deformed due to the influence of heat, external force, etc., and the flatness required for the wiring board cannot be secured. On the other hand, if the thickness exceeds 0.45 mm, when the through conductor 5 is formed on the inner wall of the through hole 4 as will be described later, the plating solution is less likely to enter the through hole 4 and the through conductor 5 is formed well. It becomes difficult. Therefore, the thickness of the insulating resin plate 1 is specified in the range of 0.35 to 0.45 mm.
[0014]
The insulating resin plate 1 is made of a glass cloth, an aramid cloth, or the like made of silica, alumina, an aramid resin or the like in an epoxy resin, bismaleimide triazine resin, polyphenylene ether resin, or the like impregnated into a glass cloth or an aramid cloth. If the fiber portion and the resin portion are contained so that the laser beam transmittance is substantially equal, the through-hole 4 is formed when the through-hole 4 is drilled in the insulating resin plate 1 with the laser beam as described later. It is possible to satisfactorily form the insulating resin plate 1 with a substantially uniform size. Therefore, a filler made of silica, alumina, aramid resin, or the like is added to a glass cloth, aramid cloth, or the like in an epoxy resin, bismaleimide triazine resin, or polyphenylene ether resin impregnated in the glass cloth or aramid cloth of the insulating resin plate 1. It is preferable that the fiber portion and the resin portion are contained so that the transmittance of the laser beam is substantially equal.
[0015]
The inner layer conductors 2A and 2B attached to the upper and lower surfaces of the insulating resin plate 1 are made of copper foil, and are electrically connected to the inner layer wiring conductor pattern W mainly functioning as a power supply layer and a ground layer and the inner layer wiring conductor pattern W. And an independent dummy conductor pattern D, having a thickness of 7 to 12 μm and a center line average roughness Ra of the surface of about 0.2 to 2 μm. When the thickness of the inner layer conductors 2A and 2B is less than 7 μm, sufficient electrical characteristics cannot be imparted to the inner layer wiring conductor pattern W as the power supply layer or the ground layer, and when the thickness exceeds 12 μm, As described above, when the through hole 4 penetrating the insulating resin plate 1 and the inner layer conductors 2A and 2B and the insulating resin layers 3A and 3B is drilled by laser processing, it is difficult to stably form the through hole 4. . Therefore, the thickness of the inner layer conductors 2A and 2B is specified in the range of 7 to 12 μm.
[0016]
The inner layer conductors 2A and 2B are formed so as to have inner layer wiring conductor patterns W or dummy conductor patterns D penetrating through the through holes 4 and in contact with the later described through conductors 5 corresponding to all the through holes 4. In other words, when the through holes 4 are drilled by laser processing, the absorption and reflection of the laser light can be made substantially the same in all the through holes 4 so that all the through holes 4 can be formed in a substantially uniform size and shape. Therefore, the inner layer conductors 2 </ b> A and 2 </ b> B are preferably formed so as to have the inner layer wiring conductor pattern W or the dummy conductor pattern D penetrating through the through holes 4 corresponding to all the through holes 4. In this case, the dummy conductor pattern D may be a substantially circular pattern whose diameter is approximately 40-100 μm larger than the diameter of the through-hole 4, and an interval with a width of approximately 30-60 μm between the inner conductor pattern W. May be provided. When the diameter of the dummy conductor pattern D is larger than the diameter of the through-hole 4 by less than 40 μm, it is difficult to accurately penetrate the dummy conductor pattern D when the through-hole 4 is drilled by laser processing. If it is too large, it is difficult to increase the area of the inner layer wiring conductor pattern W. In addition, when the distance between the dummy conductor pattern D and the inner layer wiring conductor pattern W is less than 30 μm, there is a tendency that electrical insulation between the dummy conductor pattern D and the inner layer wiring conductor pattern W cannot be maintained well. On the other hand, if it exceeds 60 μm, it is difficult to increase the area of the inner layer wiring conductor pattern W.
[0017]
Further, when the inner-layer conductors 2A and 2B have a center line average roughness Ra of less than 0.2 μm, the inner-layer conductors 2A and 2B do not firmly adhere to the inner-layer conductors 2A and 2B and the inner-layer conductors 2A and 2B. And the insulating resin layers 3A and 3B tend to be peeled off. On the other hand, when the thickness exceeds 2 μm, it tends to be difficult to form such a rough surface stably and efficiently. Accordingly, the center line average roughness Ra of the inner layer conductors 2A and 2B is preferably in the range of 0.2 to 2 μm.
[0018]
The insulating resin layers 3A and 3B attached to the upper and lower surfaces of the insulating resin plate 1 are made of a thermosetting resin such as epoxy resin, bismaleimide triazine resin or polyphenylene ether resin, and the degree of decomposition with respect to laser light is the insulating resin plate. The surface conductors 6A and 6B are deposited on the surface thereof. The insulating resin layers 3A and 3B are provided to provide an insulating interval for electrically insulating the inner layer conductors 2A and 2B and the surface layer conductors 6A and 6B to be insulated from each other. 25-45 μm on 2B. When the thickness of the insulating resin layers 3A and 3B is less than 25 μm on the inner layer conductors 2A and 2B, the inner layer conductors 2A and 2B and the surface layer conductors 6A and 6B to be insulated from each other can be electrically well insulated. On the other hand, if the thickness exceeds 45 μm, the through-hole 4 can be satisfactorily formed when the through-hole 4 penetrating the insulating resin plate 1 and the inner layer conductors 2A and 2B and the insulating resin layers 3A and 3B is drilled by laser processing. It becomes difficult. Therefore, the thickness of the insulating layers 3A and 3B is specified in the range of 25 to 45 μm on the inner layer conductors 2A and 2B.
[0019]
The surface conductors 6A and 6B are made of a copper plating film having a thickness of 8 to 30 μm, and form a surface layer wiring pattern including a power supply wiring, a ground wiring, and a signal wiring. For example, an electrode of an electronic component (not shown) is connected to an exposed part of the surface layer conductor 6A on the upper surface side via solder, and an exposed part of the surface layer conductor 6B on the lower surface side is connected to another wiring board (not shown). Connected via solder.
[0020]
If the thickness of the surface conductors 6A and 6B is less than 8 μm, the electrical resistance of the surface layer wiring pattern is high. On the other hand, if the thickness exceeds 30 μm, it is difficult to form the surface layer wiring pattern at a high density. . Therefore, the thickness of the surface conductors 6A and 6B is preferably in the range of 8 to 30 μm.
[0021]
Further, in the wiring board of the present invention, a through hole 4 is formed through the insulating resin plate 1, the inner layer conductors 2 A and 2 B and the insulating resin layers 3 A and 3 B, and the through conductor 5 is formed on the inner wall of the through hole 4. Is deposited. The through hole 4 is for providing a lead-out path for leading the through conductor 5 from the upper surface of the insulating resin layer 3A to the lower surface of the insulating resin layer 3B, and is drilled by, for example, laser processing. The through hole 4 has a diameter of 75 to 115 μm in the insulating resin plate 1 and an inner wall that is substantially vertical. In the insulating resin layers 3A and 3B, the inner wall faces outward at an angle of 10 to 30 from the vertical direction. It has an expanding shape.
[0022]
Thus, according to the wiring board of the present invention, the diameter of the through hole 4 is as small as 75 to 115 μm in the insulating resin plate 1 and the inner wall has an angle of 10 to 30 from the vertical direction in the insulating resin layers 3A and 3B. Therefore, the through conductors 5 and the surface layer conductors 6A and 6B can be arranged with high density, thereby obtaining a wiring board having extremely high density wiring.
[0023]
The through-hole 4 has a small diameter of 75 to 115 μm in the insulating resin plate 1 but has an inner wall that is substantially vertical in the insulating resin plate 1 and 10 to 30 degrees from the vertical direction in the insulating resin layers 3A and 3B. Therefore, when the through conductor 5 is deposited and formed on the inner wall of the through hole 4 as will be described later, the plating solution for forming the through conductor 5 is formed inside the through hole 4. As a result, the through conductor 5 can be formed well in the through hole 4.
[0024]
When the diameter of the through hole 4 in the insulating resin plate 1 is less than 75 μm, the plating solution for forming the through conductor 5 is formed inside the through hole 4 when the through conductor 5 is deposited on the inner wall of the through hole 4. It is difficult to form the through conductor 5 on the inner wall of the through hole 4 without entering the through hole 4 on the other hand. On the other hand, if it exceeds 115 μm, it is difficult to arrange the through conductor 5 and the surface layer conductors 6A and 6B at high density. Become. Therefore, the diameter of the through hole 4 in the insulating resin plate 1 is specified in the range of 75 to 115 μm.
[0025]
In addition, when the inner wall of the through hole 4 in the insulating resin plate 1 is not substantially vertical, bubbles are likely to be left inside the through hole 4 when the through conductor 5 is deposited on the inner wall of the through hole 4. It is difficult to form the through conductor 5 on the inner wall of the through hole 4 without the plating solution for forming well reaching the part where the bubbles are left. Therefore, the inner wall of the through hole 4 in the insulating resin plate 1 is specified to be substantially vertical.
[0026]
Further, when the angle at which the inner wall of the through hole 4 extends outward in the insulating resin layers 3A and 3B is less than 10 degrees from the vertical direction, the through conductor 5 is formed when the through conductor 5 is deposited on the inner wall of the through hole 4. The plating solution for forming the metal does not enter the inside of the through-hole 4 well, and it becomes difficult to form the through-conductor 5 on the inner wall of the through-hole 4 on the other hand. It is difficult to stably and efficiently form the through-hole 4 in which the swell spreads. Therefore, the angle at which the inner wall of the through-hole 4 extends outward in the insulating resin layers 3A and 3B is specified in the range of 10 to 30 degrees from the vertical direction.
[0027]
The through conductor 5 deposited on the inner wall of the through hole 4 is made of a copper plating film having a thickness of about 8 to 25 μm, and the inner layer conductor 2A is positioned above and below the insulating resin plate 1 and the insulating resin layers 3A and 3B. 2B and surface layer conductors 6A and 6B function as connecting conductors that electrically connect each other.
[0028]
When the thickness of the through conductor 5 is less than 8 μm, the electrical resistance of the through conductor 5 tends to be too high. On the other hand, when the thickness exceeds 25 μm, the through conductor 5 is disposed inside the through hole 4 to which the through conductor 5 is attached. It becomes difficult to fill the solder resist 7 to be satisfactorily. Therefore, the thickness of the through conductor 5 is preferably in the range of 8 to 25 μm.
[0029]
Furthermore, a solder resist 7 made of a thermosetting resin such as an epoxy resin, a bismaleimide triazine resin, or a polyphenylene ether resin is deposited and filled in the surfaces of the insulating resin layers 3A and 3B and the inside of the through holes 4. The solder resist 7 functions as a protective layer for protecting the through conductor 5 and the surface layer conductors 6A and 6B and electrically insulating the surface layer wiring patterns in the surface layer conductors 6A and 6B. It is formed in a predetermined pattern that exposes a part.
[0030]
When the thickness of the solder resist 7 on the surface conductors 6A and 6B is less than 10 μm, the surface conductor 6 cannot be protected well and the surface wiring patterns in the surface conductors 6A and 6B are electrically connected to each other. On the other hand, when it exceeds 40 μm, it tends to be difficult to form the solder resist 7 in a predetermined pattern. Therefore, the thickness of the solder resist on the surface conductors 6A and 6B is preferably in the range of 10 to 40 μm.
[0031]
Thus, according to the wiring board of the present invention, the through conductor 5 can be satisfactorily formed in the through hole 4, and thereby a wiring board having an extremely high density wiring that does not cause the breakage of the through conductor 5 can be obtained. Can be provided.
[0032]
Next, a method for manufacturing the wiring board shown in FIG. 1 by the manufacturing method of the present invention will be described with reference to FIGS.
[0033]
First, as shown in a partial cross-sectional view in FIG. 2A, for example, a glass cloth or an aramid cloth made of an organic insulating material impregnated with a resin such as an epoxy resin, a bismaleimide triazine resin, or a polyphenylene ether resin has a thickness of 0.35. A double-sided copper-clad plate is prepared in which inner layer conductors 2A and 2B made of copper foil having a thickness of 7 to 12 μm are deposited on the upper and lower surfaces of an insulating resin plate 1 having a thickness of 0.45 mm. The inner layer conductors 2A and 2B have their surfaces roughened so that the center line average roughness Ra of the surfaces is about 0.2 to 2 μm.
[0034]
If the thickness of the insulating resin plate 1 is less than 0.35 mm, the insulating resin layers 3A and 3B are attached to the upper and lower surfaces of the insulating resin plate 1 or penetrate the insulating resin plate 1, the inner layer conductors 2A and 2B, and the insulating resin layers 3A and 3B. When the plurality of through holes 4 are formed, the wiring board is warped or deformed due to the influence of heat or external force, and the flatness required for the wiring board cannot be secured. On the other hand, when the thickness exceeds 0.45 mm, when the through conductor 5 is formed on the inner wall of the through hole 4 as will be described later, the plating solution is less likely to enter the through hole 4, and disconnection is likely to occur in the through conductor 5. Therefore, the thickness of the insulating resin plate 1 is specified in the range of 0.35 to 0.45 mm.
[0035]
Further, when the thickness of the inner layer conductors 2A and 2B is less than 7 μm, the conductor pattern of the inner layer conductors 2A and 2B cannot give sufficient electric characteristics as a power supply layer or a ground layer, and on the other hand, the thickness exceeds 12 μm. In this case, as will be described later, when the through hole 4 penetrating the insulating resin plate 1 and the inner layer conductors 2A and 2B and the insulating resin layers 3A and 3B is drilled by laser processing, the through hole 4 can be formed stably. It becomes difficult. Therefore, the thickness of the inner layer conductors 2A and 2B is specified in the range of 7 to 12 μm.
[0036]
Further, when the center line average roughness Ra of the inner layer conductors 2A and 2B is less than 0.2 μm, the insulating resin layers 3A and 3B are deposited on the upper and lower surfaces of the insulating resin plate 1 as described later. The inner layer conductors 2A and 2B and the insulating resin layers 3A and 3B are not firmly adhered to each other, and the inner layer conductors 2A and 2B and the insulating resin layers 3A and 3B tend to be peeled off, and the other exceeds 2 μm. And it tends to be difficult to form such a rough surface stably and efficiently. Accordingly, the center line average roughness Ra of the inner layer conductors 2A and 2B is preferably in the range of 0.2 to 2 μm.
[0037]
Further, the inner layer conductors 2A and 2B are penetrated by the through holes 4 at positions where the through holes 4 are formed, and a conductor pattern in contact with the through conductors 5 to be described later is provided corresponding to all the through holes 4, so that the laser When the through holes 4 are formed by processing, the absorption and reflection of the laser light is uniform in all the through holes 4, and all the through holes 4 can be formed substantially uniformly. Therefore, the inner layer conductors 2 </ b> A and 2 </ b> B are preferably provided with conductor patterns penetrating through the through holes 4 at positions where the through holes 4 are formed corresponding to all the through holes 4.
[0038]
Such inner layer conductors 2A and 2B have a copper foil having a thickness of about 8 to 16 μm adhered to the entire upper and lower surfaces of the insulating resin plate 1, and a photosensitive dry film resist is deposited on the copper foil. Then, this photosensitive dry film resist is exposed and developed by a well-known photolithography technique to form an etching mask having the dry film resist at the conductive pattern forming position, and then the copper foil exposed from the etching mask is cupric chloride. Etching is removed using an etching solution composed of an aqueous solution or ferric chloride aqueous solution, and finally the etching mask is peeled off, and then the surface is etched using a roughening solution containing formic acid in a cupric chloride aqueous solution. Formed by roughening.
[0039]
Next, as shown in a partial cross-sectional view in FIG. 2B, the insulating resin layers 3A and 3B having a thickness of 25 to 45 μm are formed on the upper and lower surfaces of the double-sided copper-clad plate 11 on the inner conductors 2A and 2B. To do. The insulating resin layers 3A and 3B are made of a thermosetting resin such as an epoxy resin, a bismaleimide triazine resin, or a polyphenylene ether resin, and the degree of decomposition with respect to a laser beam such as a carbon dioxide laser is larger than that of the insulating resin plate 1.
[0040]
When the thickness of the insulating resin layers 3A and 3B is less than 25 μm on the inner layer conductors 2A and 2B, the inner layer conductors 2A and 2B and the surface layer conductors 6A and 6B to be insulated from each other can be electrically well insulated. On the other hand, if the thickness exceeds 45 μm, the through-hole 4 can be satisfactorily formed when the through-hole 4 penetrating the insulating resin plate 1 and the inner layer conductors 2A and 2B and the insulating resin layers 3A and 3B is drilled by laser processing. It becomes difficult. Therefore, the thickness of the insulating layers 3A and 3B is specified in the range of 25 to 45 μm on the inner layer conductors 2A and 2B.
[0041]
In order to deposit and form the insulating resin layers 3A and 3B on the upper and lower surfaces of the double-sided copper clad plate formed by coating the inner layer conductors 2A and 2B on the upper and lower surfaces of the insulating resin plate 1, the thermosetting property in a semi-cured state is used. A method is adopted in which a resin film is temporarily pressure-bonded on both upper and lower surfaces of a double-sided copper-clad plate with a vacuum laminator and then heat-treated to be cured.
[0042]
Next, as shown in a partial cross-sectional view in FIG. 2C, a plurality of through holes 4 penetrating the insulating resin layers 3A and 3B, the inner layer conductors 2A and 2B, and the insulating resin plate 1 are drilled by laser processing. The through-hole 4 has a diameter of 75 to 115 μm in the insulating resin plate 1 and an inner wall that is substantially vertical. In the insulating resin layers 3A and 3B, the inner wall extends outward at an angle of 10 to 30 degrees from the vertical direction. Shape. In this case, by making the degree of decomposition of the insulating resin layers 3A and 3B with respect to the laser light larger than that of the insulating resin plate 1, the inner wall of the through hole 4 is substantially vertical in the insulating resin plate 1 and the insulating resin layers 3A and 3B. In the case of, the shape can be expanded outward at an angle of 10 to 30 degrees from the vertical direction.
[0043]
In this way, the diameter of the through hole 4 is made as small as 75 to 115 μm in the insulating resin plate 1 and the inner wall of the through hole 4 is directed outward at an angle of 10 to 30 degrees from the vertical direction in the insulating resin layers 3A and 3B. As described later, when the through conductor 5 and the surface layer conductors 6A and 6B are formed, the through conductor 5 and the surface layer conductors 6A and 6B can be arranged at a high density. Can be obtained. The through-hole 4 has a small diameter of 75 to 115 μm in the insulating resin plate 1, but the inner wall is substantially vertical in the insulating resin plate 1 and 10 to 30 degrees from the vertical direction in the insulating resin layers 3A and 3B. Since the shape spreads outward at an angle, the plating solution for forming the through conductor 5 is formed in the through hole 4 when the through conductor 5 is deposited on the inner wall of the through hole 4 as described later. As a result, the through conductor 5 can be satisfactorily formed in the through hole 4.
[0044]
When the diameter of the through hole 4 in the insulating resin plate 1 is less than 75 μm, the plating solution for forming the through conductor 5 is formed inside the through hole 4 when the through conductor 5 is deposited on the inner wall of the through hole 4. However, if the thickness exceeds 115 μm, it is difficult to dispose the through conductor 5 and the surface layer conductors 6A and 6B at a high density. Become. Therefore, the diameter of the through hole 4 in the insulating resin plate 1 is specified in the range of 75 to 115 μm.
[0045]
In addition, when the inner wall of the through hole 4 in the insulating resin plate 1 is not substantially vertical, bubbles are likely to be left inside the through hole 4 when the through conductor 5 is deposited on the inner wall of the through hole 4. It is difficult to form the through conductor 5 on the inner wall of the through hole 4 without the plating solution for forming well reaching the part where the bubbles are left. Therefore, the inner wall of the through hole 4 in the insulating resin plate 1 is specified to be substantially vertical.
[0046]
Further, when the angle at which the inner wall of the through hole 4 extends outward in the insulating resin layers 3A and 3B is less than 10 degrees from the vertical direction, the through conductor 5 is formed when the through conductor 5 is deposited on the inner wall of the through hole 4. The plating solution for forming the metal does not enter the inside of the through-hole 4 well, and it becomes difficult to form the through-conductor 5 on the inner wall of the through-hole 4 on the other hand. It is difficult to stably and efficiently form the through-hole 4 in which the swell spreads. Therefore, the angle at which the inner wall of the through-hole 4 extends outward in the insulating resin layers 3A and 3B is specified in the range of 10 to 30 degrees from the vertical direction.
[0047]
In order to form the through holes 4 in the insulating resin layers 3A and 3B, the inner layer conductors 2A and 2B, and the insulating resin plate 1, for example, black or black that absorbs energy of laser light satisfactorily on the insulating resin layers 3A and 3B. A laser processing sheet made of a resin having a color close to that of a laser beam is pasted, and a carbon dioxide laser beam with an output of 7 to 12 mJ is irradiated on a predetermined position with a pulse width of 50 to 500 μsec from the top of the laser processing sheet. Then, a method of drilling the through hole 4 is employed. At this time, if the output of the carbon dioxide laser beam is less than 7 mJ, it tends to be difficult to perforate the through hole 4 to a sufficient size, and if it exceeds 12 mJ, the through hole 4 in the insulating resin layers 3A and 3B is likely to be difficult. Tend to be too large. Therefore, the carbon dioxide laser light to be irradiated preferably has an output of 7 to 12 mJ and a pulse width of 50 to 500 μsec. The laser processing sheet is peeled off after the through holes 4 are formed. By forming the through holes 4 by laser processing in this way, the insulating resin plate 1 has a diameter of 75 to 115 μm and its inner wall is substantially vertical, and the inner walls of the insulating resin layers 3A and 3B are 10 The through-hole 4 having a shape that expands outward at an angle of ˜30 degrees can be easily formed.
[0048]
Next, as shown in a partial sectional view in FIG. 2D, a plating film 13A made of an electroless copper plating film having a thickness of 1 to 3 μm is deposited on the inner wall of the through hole 4 and the surfaces of the insulating resin layers 3A and 3B. Let In order to deposit the plating film 13A made of an electroless plating film, for example, a palladium catalyst is used on the inner walls of the through holes 4 and the surfaces of the insulating resin layers 3A and 3B by using a palladium active liquid containing ammonium chloride-based palladium acetate. And an electroless copper plating film may be deposited thereon using a copper sulfate-based electroless copper plating solution. Although the diameter of the through hole 4 is as small as 75 to 115 μm in the insulating resin plate 1, the inner wall is substantially vertical in the insulating resin plate 1 and at an angle of 10 to 30 degrees from the vertical direction in the insulating resin layers 3A and 3B. Since the shape spreads outward, the electroless copper plating solution penetrates well into the through hole 4, and as a result, the inner wall of the through hole 4 and the surfaces of the insulating resin layers 3A and 3B are electroless copper plated. The film can be satisfactorily deposited to a substantially uniform thickness. Before the plating film 13A made of an electroless copper plating film is deposited, the surface of the insulating resin layers 3A and 3B and the inner wall of the through hole 4 are made of a roughening solution made of, for example, a potassium permanganate solution or a sodium permanganate solution. If the surface roughness is made rough so that the center line average roughness Ra is about 0.2 to 2 μm, the plating film 13A made of an electroless copper plating film can be firmly applied. Therefore, before depositing the plating film 13A made of an electroless copper plating film, the surface of the insulating resin layers 3A and 3B and the inner wall of the through hole 4 are made of a roughening solution made of, for example, a potassium permanganate solution or a sodium permanganate solution. The center line average roughness Ra is preferably roughened to about 0.2 to 2 μm.
[0049]
Next, as shown in a partial cross-sectional view in FIG. 2E, a plating mask 14 is deposited on the electroless copper plating film on the insulating layers 3A and 3B, and the electroless exposed from the plating mask 14 is applied. Electroless copper plating film having a thickness of about 10 to 35 μm is deposited on the copper plating film, and the inner wall of the through hole 4 and the conductive pattern formation sites on the surfaces of the insulating resin layers 3A and 3B are selectively deposited thickly. A plating film 13B composed of a plating film and an electrolytic copper plating film is formed.
[0050]
The plating mask 14 is formed by, for example, depositing a photosensitive dry film resist on the electroless copper plating film on the insulating resin layers 3A and 3B, and exposing and developing the dry film resist by a photolithography technique. It is formed by processing into a pattern.
[0051]
Moreover, as an electrolytic copper plating solution for depositing the electrolytic copper plating film, for example, an electrolytic copper plating solution made of a copper sulfate system may be used. At this time, although the diameter of the through hole 4 is as small as 75 to 115 μm in the insulating resin plate 1, its inner wall is substantially vertical in the insulating resin plate 1 and 10 to 30 from the vertical direction in the insulating resin layers 3A and 3B. Since it has a shape that spreads outward at an angle, the electrolytic copper plating solution penetrates well into the through-hole 4, and as a result, electrolytic copper plating is applied to the inner wall of the through-hole 4 and the surfaces of the insulating resin layers 3A and 3B. The film is well deposited to a substantially uniform thickness.
[0052]
Next, as shown in a partial cross-sectional view in FIG. 2 (f), the electroless copper plating film and the electrolytic copper plating are removed until the plating mask 14 is peeled off and the electroless copper plating film under the plating mask 14 disappears. The film is etched to form the through conductor 5 on the inner wall of the through hole 4 and the surface conductors 6A and 6B on the surfaces of the insulating resin layers 3A and 3B.
[0053]
In order to etch the electroless copper plating film and the electrolytic copper plating film, an etching solution made of a cupric chloride aqueous solution or a ferric chloride aqueous solution may be used.
[0054]
Finally, a solder resist 7 made of a thermosetting resin such as epoxy resin, bismaleimide triazine resin, or polyphenylene ether is deposited and filled on the surfaces of the insulating resin layers 3A and 3B and the inside of the through holes 4 as shown in FIG. The wiring board of the present invention shown is completed.
[0055]
Note that the solder resist 7 is printed and applied with a photosensitive resin paste for the solder resist 7 so as to fill the through-holes 4 from the insulating layer 3A side and the 3B side using a conventionally known screen printing method. It is formed by exposing and developing into a predetermined pattern using a well-known photolithography technique. At this time, the through-hole 4 has a shape in which the inner wall of the insulating resin layers 3A and 3B expands outward at an angle of 10 to 30 degrees from the vertical direction, and therefore the resin for the solder resist 7 in the through-hole 4 The paste penetrates satisfactorily, and as a result, the inside of the through holes 4 can be satisfactorily filled with the solder resist 7.
[0056]
Thus, according to the method for manufacturing a wiring board of the present invention, it is possible to obtain a wiring board capable of extremely high-density wiring without causing disconnection in the through conductor 5.
[0057]
【The invention's effect】
According to the wiring board of the present invention, the upper and lower surfaces of the insulating resin plate having a thickness of 0.35 to 0.45 mm are made of copper foil having a thickness of 7 to 12 μm, and the inner layer wiring conductor pattern and the inner layer wiring conductor pattern are electrically An insulating resin layer having a thickness of 25 to 45 μm is deposited on the upper and lower surfaces of the double-sided copper clad plate to which the inner layer conductor having an independent dummy conductor pattern is deposited, and the insulating resin plate, The inner layer conductor and the insulating resin layer are vertically penetrated, and the insulating resin plate has a diameter of 75 to 115 μm and its inner wall is substantially vertical, and the inner wall of the insulating resin layer is 10 to 10 mm from the vertical direction. A plurality of through holes having a shape extending outward at an angle of 30 degrees are formed, and the through conductors connected to the inner layer conductor on the inner wall of the through holes and the surface of the insulating resin layer Since the surface layer conductor connected to each other is formed by plating, when the through conductor is applied to the inner wall of the through hole, the plating solution for attaching the through conductor enters the through hole well, As a result, it is possible to provide a wiring board with high density wiring in which the through conductor is well formed on the inner wall of the through hole and the through conductor does not break.
[0058]
According to the method for manufacturing a wiring board of the present invention, the upper and lower surfaces of an insulating resin plate having a thickness of 0.35 to 0.45 mm are made of copper foil having a thickness of 7 to 12 μm. An insulating resin layer having a thickness of 25 to 45 μm is deposited on the upper and lower surfaces of the double-sided copper-clad plate on which the inner layer conductor having a dummy conductor pattern electrically independent from the conductor pattern is deposited, and the insulation The resin plate, the inner layer conductor, and the insulating resin layer are vertically penetrated. The insulating resin plate has a diameter of 75 to 115 μm and its inner wall is substantially vertical. In the insulating resin layer, the inner wall is vertical. A plurality of through-holes having a shape extending outward at an angle of 10 to 30 degrees from the first through-hole, and then the through-conductors connected to the inner-layer conductor on the inner wall of the through-hole and the insulating resin layer Since the surface conductors connected to the through conductors on the surface are each deposited by plating, when the through conductor is deposited on the inner wall of the through hole, the plating solution for depositing the through conductor is good in the through hole. As a result, it is possible to obtain a wiring substrate with high-density wiring in which a through conductor is well formed on the inner wall of the through hole and no breakage occurs in the through conductor.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional view showing an example of an embodiment of a wiring board according to the present invention.
FIGS. 2A to 2F are partial cross-sectional views for each process for explaining a method of manufacturing a wiring board according to the present invention.
[Explanation of symbols]
1. Insulating resin plate
2A ・ 2B ・・・ Inner layer conductor
3A ・ 3B ・・・ Insulating resin layer
4 .... Through hole
5 .... Penetration conductor
6A ・ 6B ・・・ Surface conductor

Claims

厚みが０．３５〜０．４５ｍｍの絶縁樹脂板の上下両面に厚みが７〜１２μｍの銅箔から成り、内層配線導体パターンおよび該内層配線導体パターンから電気的に独立したダミー導体パターンを有する内層導体が被着された両面銅張板の前記上下両面に厚みが前記内層導体上で２５〜４５μｍの絶縁樹脂層が被着されているとともに前記絶縁樹脂板、前記内層導体および前記絶縁樹脂層を上下に貫通し、かつ前記絶縁樹脂板においては直径が７５〜１１５μｍでその内壁が略垂直であり、かつ前記絶縁樹脂層においてはその内壁が垂直方向から１０〜３０度の角度で外側に向けて拡がる形状の複数の貫通孔が形成され、該貫通孔の内壁に前記内層導体に接続された貫通導体および前記絶縁樹脂層の表面に前記貫通導体に接続された表層導体がそれぞれめっきにより被着形成されて成ることを特徴とする配線基板。Thickness Ri consists of copper foil having a thickness of 7~12μm the upper and lower surfaces of the insulating resin plate 0.35～0.45Mm, organic electrically independent dummy conductor pattern from the inner layer conductor patterns and inner layer conductor patterns wherein with the thickness on the upper and lower surfaces is an insulating resin layer of 25~45μm on the inner conductor is deposited insulating resin plate, the inner conductor and the insulation of the double-sided copper clad laminate in which the inner layer conductor is deposited you The insulating resin plate penetrates up and down, the diameter of the insulating resin plate is 75 to 115 μm, and the inner wall is substantially vertical, and the inner wall of the insulating resin layer is outside at an angle of 10 to 30 degrees from the vertical direction. extends to a plurality of through-holes of shape is formed, the through hole of the through conductors connected to said inner layer conductor to the inner wall and the insulating surface layer conductor connected to said through conductors on the surface of the resin layer pixel Wiring board, characterized by comprising been deposited and formed by respective plating.

前記内層導体は、前記貫通孔により貫通されるとともに前記貫通導体に接する導体パターンを前記全ての貫通孔に対応してそれぞれ前記上下両面に有することを特徴とする請求項１記載の配線基板。 2. The wiring board according to claim 1, wherein the inner layer conductor has a conductor pattern which is penetrated by the through hole and is in contact with the through conductor on each of the upper and lower surfaces corresponding to all the through holes.

厚みが０．３５〜０．４５ｍｍの絶縁樹脂板の上下両面に厚みが７〜１２μｍの銅箔から成り、内層配線導体パターンおよび該内層配線導体パターンから電気的に独立したダミー導体パターンを有する内層導体が被着された両面銅張板の前記上下両面に厚みが前記内層導体上で２５〜４５μｍの絶縁樹脂層を被着させるとともに前記絶縁樹脂板、前記内層導体および前記絶縁樹脂層を上下に貫通し、かつ前記絶縁樹脂板においては直径が７５〜１１５μｍでその内壁が略垂直であり、かつ前記絶縁樹脂層においてはその内壁が垂直方向から１０〜３０度の角度で外側に向けて拡がる形状の複数の貫通孔を形成し、次に前記貫通孔の内壁に前記内層導体に接続された貫通導体および前記絶縁樹脂層の表面に前記貫通導体に接続された表層導体をそれぞれめっきにより被着させることを特徴とする配線基板の製造方法。Thickness Ri consists of copper foil having a thickness of 7~12μm the upper and lower surfaces of the insulating resin plate 0.35～0.45Mm, having electrically independent dummy conductor pattern from the inner layer conductor patterns and inner layer conductor patterns An insulating resin layer having a thickness of 25 to 45 μm is deposited on the upper and lower surfaces of the double-sided copper-clad plate to which the inner layer conductor is applied, and the insulating resin plate, the inner layer conductor, and the insulating resin layer are The insulating resin plate has a diameter of 75 to 115 μm and its inner wall is substantially vertical, and the insulating resin layer has its inner wall extending outward at an angle of 10 to 30 degrees from the vertical direction. forming a plurality of through-holes of the shape, then the said on the inner wall of the through hole through conductor is connected to the inner conductor and the insulating resin layer its a connected surface conductor into the through conductors on the surface of Method for manufacturing a wiring substrate, characterized in that depositing the respective plating.

前記両面銅張板の前記貫通孔が形成される各位置の前記上下両面に前記貫通孔により貫通される前記内層導体の導体パターンをそれぞれ配設しておくとともに、該導体パターンを貫通して前記貫通孔を形成するとともにこの導体パターンに接して前記貫通導体を被着させることを特徴とする請求項３記載の配線基板の製造方法。 Conductor patterns of the inner layer conductors penetrated by the through holes are respectively disposed on the upper and lower surfaces of each position where the through holes of the double-sided copper-clad plate are formed, 4. The method of manufacturing a wiring board according to claim 3, wherein the through-hole is formed and the through-conductor is deposited in contact with the conductor pattern.

前記貫通孔をレーザー加工により形成することを特徴とする請求項３または請求項４記載の配線基板の製造方法。 5. The method for manufacturing a wiring board according to claim 3, wherein the through hole is formed by laser processing.