JP2004055897A - Multilayer wiring substrate, base material therefor and its manufacturing method - Google Patents

Multilayer wiring substrate, base material therefor and its manufacturing method Download PDF

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JP2004055897A
JP2004055897A JP2002212569A JP2002212569A JP2004055897A JP 2004055897 A JP2004055897 A JP 2004055897A JP 2002212569 A JP2002212569 A JP 2002212569A JP 2002212569 A JP2002212569 A JP 2002212569A JP 2004055897 A JP2004055897 A JP 2004055897A
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conductive layer
hole
hole diameter
base material
insulating base
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JP4008298B2 (en
Inventor
Shoji Ito
伊藤　彰二
Munekimi Mizutani
水谷　宗幹
Masahiro Okamoto
岡本　誠裕
Anan Ponpanpaanii
ポンパンパーニー・アナン
Satoru Nakao
中尾　知
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Fujikura Ltd
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Fujikura Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To obtain a thin multilayer wiring substrate without damaging contact reliability between a conductive resin composition and a conductive circuit part and without deteriorating smoothness of the substrate. <P>SOLUTION: In the base material for the multilayer wiring substrate, a conductive layer 12 forming a wiring pattern is provided to one surface of an insulating resin layer 11, and a bonding layer 13 for interlaminar bonding is provided to the other surface thereof. A through hole 14 passing through the conductive layer 12, the insulating resin layer 11 and the bonding layer 13 is filled with conductive resin composition 15 for obtaining interlayer conduction. A hole diameter Db of an outer surface side of the conductive layer 12 is smaller than a hole diameter Da of the conductive layer 12 in a border between the conductive layer 12 and the insulating resin layer 11 of the through hole 14. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
この発明は、多層配線基板（多層プリント配線板）、多層配線基板用基材およびその製造方法に関し、特に、フリップチップ実装などの高密度実装が可能な多層のフレキシブルプリント配線板等の多層配線基板、多層配線基板用基材およびその製造方法に関するものである。
【０００２】
【従来の技術】
ポリイミド樹脂は、高耐熱性、電気絶縁性、高屈曲性を有した樹脂であり、フレキシブルプリント配線板（ＦＰＣ）など、プリント配線板の絶縁層材料として利用されている。ポリイミド樹脂を絶縁層材料として応用したものの一つとして、ポリイミドフィルムを絶縁層材料として使用したフレキシブルプリント配線板（ＦＰＣ）を多層積層し、一括穴あけされたスルーホールによって層間導通を得る多層ＦＰＣがある。
【０００３】
しかし、スルーホールによる多層ＦＰＣでは、層間接続位置の制約のために、配線設計の自由度が低く、スルーホール上にチップを実装することができないため、実装密度を高くすることに限界があり、近年のより一層の高密度実装化の要求に対応できなくなっている。
【０００４】
このことに対処すべく、層間接続をスルーホールによらずにＩＶＨ（Ｉｎｔｅｒｓｔｉｔｉａｌ　Ｖｉａ　Ｈｏｌｅ）によって行い、ビア・オン・ビアが可能な樹脂多層プリント配線板、例えば、松下電器産業社のＡＬＩＶＨ（Ａｎｙ　Ｌａｙｅｒ　Ｉｎｔｅｒｓｔｉｔｉａｌ　Ｖｉａ　Ｈｏｌｅ）基板や、ポリイミドによるＦＰＣをスルーホールを使用せずにビルドアップ方式で多層に積層するソニーケミカル社のポリイミド複合多層ビルドアップ集積回路基板（ＭＯＳＡＩＣ）が開発されている。
【０００５】
また、ポリイミドフィルムを絶縁層としてそれの片面に銅箔による導電層を貼り付けられている汎用の銅張樹脂基材を出発基材として、簡便な工程によりＩＶＨ構造の多層ＦＰＣを得る構造と製法が本願出願人と同一の出願人による特願２００１−８５２２４号で提案されている。
【０００６】
特願２００１−８５２２４号で提案されている多層配線基板用基材では、絶縁層の一方の面に銅箔を設けた銅張樹脂基材に貫通孔（バイアホール）を穴あけした後、導電性樹脂組成物（樹脂系の導電性ペースト）を銅箔側からスクリーン印刷法等による印刷法によって充填することで、図１３に示されているようなＩＶＨ部分を形成している。なお、図１３において、１０１は絶縁層を、１０２は銅箔部を、１０４は貫通孔を、１０５は貫通孔１０４に充填された導電性樹脂組成物を各々示している。
【０００７】
そして、スクリーン印刷時のマスクの開口部の口径をＩＶＨ径より大きくすることにより、印刷時の位置合わせ精度にある程度の余裕ができ、また銅箔部１０２上に導電性樹脂組成物１０５によるマスク開口部口径相当の大きさのヘッド状部１０５Ａが形成され、貫通孔１０４に充填された導電性樹脂組成物１０５と銅箔部１０２との接触面積を大きくすることができ、貫通孔１０４に充填された導電性樹脂組成物１０５の貫通孔１０４よりの抜け落ちも防止できる。
【０００８】
【発明が解決しようとする課題】
しかしながら、ヘッド状部１０５Ａは印刷用マスクの厚さ等により基材表面よりも数１０μｍ程度の厚さをもって突出するため、多層配線基板の表面平滑性を確保するためには、銅箔部１０２上のヘッド状部１０５Ａの全体を層間接着剤の層内に埋め込むに十分な接着層の厚さが必要になり、接着層の厚さが厚くなることによって多層配線基板の厚膜化を招くことになる。これに対し、接着層を厚くしない場合には、多層配線基板の表面平滑性の低下を招くことになる。
【０００９】
導電性樹脂組成物が完全に硬化する以前に、多層積層を行うことで、導電性樹脂組成物と他層の銅箔との接触が密接に行われるようにすることが考えられるが、しかし、この場合には、図１４に示されているように、導電性樹脂組成物１０５の銅箔部１０２より上の部分（ヘッド状部１０５Ａ）が、多層積層時の積層圧Ｐによって押しつぶれ、圧潰状態で広がってしまい、基板表面上から見たヘッド状部１０５Ａの大きさを均一化することが困難であるばかりか、他配線部１０２’までヘッド状部１０５Ａの導電性樹脂組成物が広がってしまい、回路の短絡を招く虞れがある。
【００１０】
この発明は、上述の如き問題点を解消するためになされたもので、導電性樹組成物と導電回路部の接触信頼性を損なうことなく、しかも基板の平滑性を低下させることなく薄い多層配線基板を得ることができる多層配線基板用基材およびその製造方法および多層配線基板を提供することを目的としている。
【００１１】
【課題を解決するための手段】
上述の目的を達成するために、この発明による多層配線基板用基材は、絶縁性基材の片面に配線パターンをなす銅箔等による導電層を設けられ、前記絶縁性基材と前記導電層を貫通する貫通孔に層間導通を得るための導電性樹脂組成物を充填された多層配線基板用基材であって、前記貫通孔の前記導電層と前記絶縁性基材との境界部における前記導電層部分の孔径Ｄａより前記導電層の外表面側の孔径Ｄｂが小さい。
【００１２】
この多層配線基板用基材によれば、貫通孔の孔径が、導電層と絶縁性基材との境界部における前記導電層部分の孔径Ｄａより導電層の外表面側の孔径Ｄｂのほうが小さいから、導電層部分の貫通孔の内壁面が縦断面で見て曲面（近円弧面）あるいは傾斜面で、導電層外表面側が先細となるテーパ状の貫通孔になり、貫通孔内壁面の面積が同一径によるストレートな貫通孔である場合に比して大きくなり、貫通孔に充填された導電性樹脂組成物と導電層との導通接触が、増大された貫通孔内壁面（側周面）で確実に取られ、導電性樹脂組成物の導電層より上の部分（ヘッド状部）と導電層との接触面積確保から派生する諸問題から解放される。
【００１３】
また、この発明による多層配線基板用基材は、孔径Ｄａ＞孔径Ｄｂを前提として、前記貫通孔の前記導電層と前記絶縁性基材との境界部における前記導電層部分の孔径Ｄａが前記境界部における前記絶縁性基材部分の孔径Ｄｃより大きく、さらには、孔径Ｄａ、Ｄｂ、Ｄｃの相互の大小関係を、孔径Ｄａ＞孔径Ｄｃ＞孔径Ｄｂとすることができる。
【００１４】
また、この発明による多層配線基板用基材は、孔径Ｄａ＞孔径Ｄｂを前提として、前記貫通孔の前記導電層と前記絶縁性基材との境界部における前記絶縁性基材部分の孔径Ｄｃが前記境界部における前記導電層部分の孔径Ｄａに等しいかあるいはそれより大きいものにすることもできる。
【００１５】
また、この発明による多層配線基板用基材は、絶縁性基材の一方の面に配線パターンをなす導電層を、他方の面に層間接着のための接着層を設けられ、前記導電層と前記絶縁性基材と前記接着層を貫通する貫通孔に層間導通を得るための導電性樹脂組成物を充填された多層配線基板用基材であって、前記貫通孔の前記導電層と前記絶縁性基材との境界部における前記導電層部分の孔径Ｄａより前記導電層の外表面側の孔径Ｄｂが小さい。
【００１６】
この多層配線基板用基材でも、貫通孔の孔径が、導電層と絶縁性基材との境界部における前記導電層部分の孔径Ｄａより導電層の外表面側の孔径Ｄｂのほうが小さいから、導電層部分の貫通孔の内壁面が縦断面で見て曲面（近円弧面）あるいは傾斜面で、導電層外表面側が先細となるテーパ状の貫通孔になり、貫通孔内壁面の面積が同一径によるストレートな貫通孔である場合に比して大きくなり、貫通孔に充填された導電性樹脂組成物と導電層との導通接触が、増大された貫通孔内壁面（側周面）で確実に取られ、導電性樹脂組成物の導電層より上の部分（ヘッド状部）と導電層との接触面積確保から派生する諸問題から解放される。
【００１７】
また、絶縁性基材の一方の面に配線パターンをなす導電層を、他方の面に層間接着のための接着層を設けられた多層配線基板用基材でも、孔径Ｄａ＞孔径Ｄｂを前提として、前記貫通孔の前記導電層と前記絶縁性基材との境界部における前記導電層部分の孔径Ｄａが前記境界部における前記絶縁性基材部分の孔径Ｄｃより大きく、さらには、孔径Ｄａ、Ｄｂ、Ｄｃの相互の大小関係を、孔径Ｄａ＞孔径Ｄｃ＞孔径Ｄｂとしたり、あるいは、前記貫通孔の前記導電層と前記絶縁性基材との境界部における前記絶縁性基材部分の孔径Ｄｃが前記境界部における前記導電層部分の孔径Ｄａに等しいかあるいはそれより大きいものにすることができる。
【００１８】
この発明による多層配線基板用基材では、絶縁性基材をポリイミド等の可撓性樹脂フィルムにより構成し、可撓性樹脂フィルムの一方の面に銅箔による導電層を貼り付けられている汎用の銅張樹脂基材を出発基材とすることができる。また、接着層は熱可塑性ポリイミドにより構成することができる。
【００１９】
この発明による多層配線基板は、上述の発明による多層配線基板用基材を複数枚、重ねて接合したものである。
【００２０】
また、上述の目的を達成するために、この発明による多層配線基板用基材の製造方法は、絶縁性基材の片面に配線パターンをなす導電層を設けられたものに、導電層と絶縁性基材との境界部における前記導電層部分の孔径Ｄａより導電層の外表面側の孔径Ｄｂが小さい貫通孔を穿孔する穿孔工程、あるいは、導電層と絶縁性基材との境界部における前記導電層部分の孔径Ｄａより導電層の外表面側の孔径Ｄｂが小さく、且つ、前記境界部における前記導電層部分の孔径Ｄａが前記境界部における前記絶縁性基材部分の孔径Ｄｃより大きい貫通孔を穿孔する穿孔工程、あるいは、前記導電層と前記絶縁性基材との境界部における前記導電層部分の孔径Ｄａより前記導電層の外表面側の孔径Ｄｂが小さく、且つ、前記境界部における前記導電層部分の孔径Ｄａが前記境界部における前記絶縁性基材部分の孔径Ｄｃより大きく、しかも、前記孔径Ｄａ＞前記孔径Ｄｃ＞前記孔径Ｄｂである貫通孔を穿孔する穿孔工程、あるいは、前記導電層と前記絶縁性基材との境界部における前記導電層部分の孔径Ｄａより前記導電層の外表面側の孔径Ｄｂが小さく、且つ、前記境界部における前記絶縁性基材部分の孔径Ｄｃが前記境界部における前記導電層部分の孔径Ｄａに等しいかあるいはそれより大きい貫通孔を穿孔する穿孔工程と、導電性樹脂組成物を前記貫通孔に充填する充填工程とを有する。
【００２１】
また、上述の目的を達成するために、この発明による多層配線基板用基材の製造方法は、絶縁性基材の一方の面に配線パターンをなす導電層を、他方の面に層間接着のための接着層を設けられたものに、導電層と絶縁性基材との境界部における前記導電層部分の孔径Ｄａより導電層の外表面側の孔径Ｄｂが小さい貫通孔を穿孔する穿孔工程、あるいは、導電層と絶縁性基材との境界部における前記導電層部分の孔径Ｄａより導電層の外表面側の孔径Ｄｂが小さく、且つ、前記境界部における前記導電層部分の孔径Ｄａが前記境界部における前記絶縁性基材部分の孔径Ｄｃより大きい貫通孔を穿孔する穿孔工程、あるいは、前記導電層と前記絶縁性基材との境界部における前記導電層部分の孔径Ｄａより前記導電層の外表面側の孔径Ｄｂが小さく、且つ、前記境界部における前記導電層部分の孔径Ｄａが前記境界部における前記絶縁性基材部分の孔径Ｄｃより大きく、しかも、前記孔径Ｄａ＞前記孔径Ｄｃ＞前記孔径Ｄｂである貫通孔を穿孔する穿孔工程、あるいは前記導電層と前記絶縁性基材との境界部における前記導電層部分の孔径Ｄａより前記導電層の外表面側の孔径Ｄｂが小さく、且つ、前記境界部における前記絶縁性基材部分の孔径Ｄｃが前記境界部における前記導電層部分の孔径Ｄａに等しいかあるいはそれより大きい貫通孔を穿孔する穿孔工程と、導電性樹脂組成物を前記貫通孔に充填する充填工程とを有する。
【００２２】
この発明による多層配線基板用基材の製造方法における前記穿孔工程は、絶縁性基材、あるいは、接着層と絶縁性基材とに所定の孔径の穴あけを行う第１穴あけ工程と、穴あけされた絶縁性基材、あるいは、接着層・絶縁性基材の側から等方性を有するエッチングによって導電層に穴あけを行う第２穴あけ工程とを含んでおり、第２穴あけ工程は、回路形成のための導電層のエッチングと同工程で行うことができる。
【００２３】
【発明の実施の形態】
以下に添付の図を参照してこの発明の実施形態を詳細に説明する。
【００２４】
（実施形態１）
図１はこの発明による一実施形態に係わる多層配線基板用基材の基本構成を示している。
【００２５】
図１に示されている多層配線基板用基材は、絶縁性基材をなす絶縁樹脂層１１の一方の面に配線パターンをなす銅箔等による導電層１２を、他方の面に層間接着のための接着層１３を各々設けられ、接着層１３と絶縁樹脂層１１と導電層１２とを貫通する貫通孔１４を穿設されている。貫通孔１４には導電性樹脂組成物１５が充填され、ＩＶＨ（バイアホール）を形成している。
【００２６】
導電性樹脂組成物１５は、導電機能を有する金属粉末を樹脂バインダに混入したものを溶剤を含む粘性媒体に混ぜてペースト状にした導電性ペーストであり、接着層１３の側よりスクイジング等によって貫通孔１４に満遍なく穴埋め充填される。
【００２７】
ＦＰＣでは、絶縁樹脂層１１は、全芳香族ポリイミド（ＡＰＩ）等によるポリイミドフィルムやポリエステルフィルム等の可撓性を有する樹脂フィルムで構成され、絶縁樹脂層１１と導電層１２と接着層１３との３層構造は、汎用の片面銅箔付きポリイミド基材（銅張樹脂基材）を出発基材として、ポリイミド部（絶縁樹脂層１１）の銅箔（導電層１２）とは反対側の面に接着層１３としてポリイミド系接着材を貼付したもので構成できる。
【００２８】
ポリイミド系接着材による接着層１３は、熱可塑性ポリイミド（ＴＰＩ）あるいは熱可塑性ポリイミドに熱硬化機能を付与したフィルムの貼り付けにより形成することができる。熱可塑性ポリイミドの場合、基板の耐熱性を考慮し、ガラス転移点の高いものを使用するのが好ましい。
【００２９】
貫通孔１４は、導電層１２と絶縁樹脂層１１との境界部における導電層１２部分の孔径Ｄａより導電層１２の外表面側の孔径Ｄｂが小さく、すなわち、Ｄａ＞Ｄｂで、しかも、貫通孔１４の導電層１２と絶縁樹脂層１１との境界部における導電層１２部分の孔径Ｄａがこの境界部における絶縁樹脂層１１の部分の孔径Ｄｃより大きい、すなわち、Ｄａ＞Ｄｃに形成されている。更に、導電層１２の外表面側の孔径Ｄｂは前記境界部における絶縁樹脂層１１の部分の孔径Ｄｃより更に小さく、Ｄａ＞Ｄｃ＞Ｄｂになっている。この貫通孔１４の孔内全域に導電性樹脂組成物１５が充填されている。
【００３０】
これにより、貫通孔１４のうち、導電層１２を貫通する部分（孔）１４Ａ（図５（ｅ）参照）の内壁面１６が縦断面で見て曲面あるいは傾斜面で、貫通孔１４は、導電層部分１４Ａにおいて、導電層外表面側が先細となるテーパ状、換言すれば、すり鉢状をなしている。
【００３１】
貫通孔１４の穿孔は、第１穴あけ工程として、絶縁樹脂層１１および接着層１３にレーザ加工あるいは異方性エッチングによって所定孔径（導電層１２と絶縁樹脂層１１との境界部における絶縁樹脂層１１部分の孔径Ｄｃ）による略ストレートな孔１４Ｂ（図５（ｃ）参照）をあけ、第１穴あけ工程完了後に、第２穴あけ工程として、穴あけされた接着層・絶縁樹脂層の側（図１にて上側）から、すなわち、孔１４Ｂより等方性を有するエッチングによって導電層１２に、導電層１２と絶縁樹脂層１１との境界部における導電層１２部分の孔径Ｄａより導電層１２の外表面側の孔径Ｄｂが小さい孔１４Ａをあける。
【００３２】
導電層１２を貫通する部分１４Ａの貫通孔１４の内壁面形状は、等方性エッチングにおける縦方向進行速度と横方向進行速度との速度比等により決まり、エッチャントの選定により、全体が一つの曲率による湾曲面（球面）、異なる複数の曲率による湾曲面が滑らかに連続した曲面、その他、回転楕円面、回転放物線面、あるいは直線状の傾斜面等、任意のものにできる。
【００３３】
この多層配線基板用基材では、貫通孔１４の導電層１２と絶縁樹脂層１１との境界部における導電層１２部分の孔径Ｄａより導電層１２の外表面側の孔径Ｄｂが小さいから、導電層１２部分の貫通孔１４の内壁面１６が縦断面で見て曲面（近円弧面）あるいは傾斜面で、導電層１２部分の貫通孔１４は導電層外表面側が先細となるテーパ状になり、貫通孔内壁面１６の面積が同一径によるストレートな貫通孔である場合に比して大きくなる。
【００３４】
これにより、貫通孔１４に充填された導電性樹脂組成物１５と導電層１２との導通接触が、増大された貫通孔内壁面（側周面）１６で、所要の接触面積をもって信頼性高く行われ、導電性樹脂組成物の導電層より上の部分（ヘッド状部）と導電層との接触面積確保から派生する諸問題から解放される。
【００３５】
図２はこの発明による多層配線基板の一つの実施形態を示している。この多層配線基板は、図１に示されている構造の多層配線基板用基材を、１層目の基材１０Ａと２層目の基材１０Ｂとして、２枚重ね合わせ、１層目の基材１０Ａの接着層１３によって１層目の基材１０Ａと２層目の基材１０Ｂとを互いに接着接合してなる。２層目の基材１０Ｂの接着層１３上には表面部の配線パターンをなす銅箔による導電層１７が形成されている。
【００３６】
導電性樹脂組成物１５を充填された各貫通孔１４はＩＶＨをなし、各貫通孔１４の導電層１２と絶縁樹脂層１１との境界部における導電層１２部分の孔径Ｄａ（図１参照）より導電層１２の外表面側の孔径Ｄｂ（図１参照）が小さく、導電層１２部分の貫通孔１４の内壁面１６が縦断面で見て曲面（近円弧面）あるいは傾斜面で、導電層１２部分の貫通孔１４が導電層外表面側が先細となるテーパ状であるから、貫通孔内壁面１６の面積が同一径によるストレートな貫通孔である場合に比して大きくなり、貫通孔１４に充填された導電性樹脂組成物１５と導電層１２との導通接触が、増大された貫通孔内壁面１６で取られ、従来のものように、導電性樹脂組成物の導電層より上の部分（ヘッド状部）を設けなくても、導電性樹脂組成物１５と導電層１２との接触面積を確保でき、基板の平滑性を低下させることなく、薄い多層配線基板を得ることができる。
【００３７】
この発明による多層配線基板用基材は、図３に示されているように、絶縁性基材をなす絶縁樹脂層２１を、熱可塑性ポリイミド（ＴＰＩ）あるいは熱可塑性ポリイミドに熱硬化機能を付与したものなど、絶縁樹脂層自体が層間接着のための接着性を有するもので構成することができる。この場合には、絶縁樹脂層２１の一方の面に配線パターンをなす銅箔等による導電層２２を設け、他方の面の積層する接着層を省略できる。
【００３８】
この多層配線基板用基材では、絶縁樹脂層２１と導電層２２とを貫通する貫通孔２４を穿設され、その貫通孔２４に導電性樹脂組成物２５が充填されてＩＶＨ（バイアホール）が形成される。
【００３９】
貫通孔２４は、導電層２２と絶縁樹脂層２１との境界部における導電層１２部分の孔径Ｄａより導電層２２の外表面側の孔径Ｄｂが小さく、すなわち、Ｄａ＞Ｄｂで、しかも、貫通孔２４の導電層２２と絶縁樹脂層２１との境界部における導電層１２部分の孔径Ｄａがこの境界部における絶縁樹脂層２１の部分の孔径Ｄｃより大きい、すなわち、Ｄａ＞Ｄｃに形成されている。更に、導電層２２の外表面側の孔径Ｄｂは前記境界部における絶縁樹脂層２１の部分の孔径Ｄｃより更に小さく、Ｄａ＞Ｄｃ＞Ｄｂになっている。この貫通孔２４の孔内全域に導電性樹脂組成物１５が充填されている。
【００４０】
これにより、貫通孔２４のうち、導電層２２を貫通する部分の内壁面２６が縦断面で見て曲面あるいは傾斜面で、貫通孔２４は、導電層２２部分において、導電層外表面側が先細となるテーパ状、換言すれば、すり鉢状をなしている。
【００４１】
貫通孔２４の穿孔は、第１穴あけ工程として、絶縁樹脂層２１にレーザ加工あるいは異方性エッチングによって所定孔径（導電層２２と絶縁樹脂層２１との境界部における絶縁樹脂層２１部分の孔径Ｄｃ）による略ストレートな孔をあけ、第１穴あけ工程完了後に、第２穴あけ工程として、穴あけされた絶縁樹脂層２１の側（図３にて上側）から、すなわち、絶縁樹脂層２１にあけられた孔より等方性を有するエッチングによって導電層２２に、導電層２２と絶縁樹脂層２１との境界部における導電層１２部分の孔径Ｄａより導電層２２の外表面側の孔径Ｄｂが小さい孔をあける。
【００４２】
この場合も、導電層２２を貫通する部分の貫通孔２４の内壁面形状は、等方性エッチングにおける縦方向進行速度と横方向進行速度との速度比等により決まり、液状エッチャントの選定により、全体が一つの曲率による湾曲面（球面）、異なる複数の曲率による湾曲面が滑らかに連続した曲面、その他、回転楕円面、回転放物線面、あるいは直線状の傾斜面等、任意のものにできる。
【００４３】
この多層配線基板用基材でも、貫通孔２４の導電層２２と絶縁樹脂層２１との境界部における導電層１２部分の孔径Ｄａより導電層２２の外表面側の孔径Ｄｂが小さいから、導電層１２部分の貫通孔２４の内壁面２６が縦断面で見て曲面（近円弧面）あるいは傾斜面で、導電層２２部分の貫通孔２４は導電層外表面側が先細となるテーパ状になり、貫通孔内壁面２６の面積が同一径によるストレートな貫通孔である場合に比して大きくなる。
【００４４】
これにより、貫通孔２４に充填された導電性樹脂組成物２５と導電層２２との導通接触が、増大された貫通孔内壁面（側周面）２６で、所要の接触面積をもって信頼性高く行われ、導電性樹脂組成物の導電層より上の部分（ヘッド状部）と導電層との接触面積確保から派生する諸問題から解放される。
【００４５】
図４はこの発明による多層配線基板の他の実施の形態を示している。この多層配線基板は、図３に示されている構造の多層配線基板用基材を、１層目の基材２０Ａと２層目の基材２０Ｂとして、２枚重ね合わせ、１層目の基材２０Ａの接着性を有する絶縁樹脂層２１によって１層目の基材２０Ａと２層目の基材２０Ｂとを互いに接着接合してなる。２層目の基材２０Ｂの絶縁樹脂層２１上には表面部の配線パターンをなす銅箔による導電層２７が形成されている。
【００４６】
この多層配線基板でも、導電性樹脂組成物２５を充填された各貫通孔２４はＩＶＨをなし、各貫通孔２４の導電層２２と絶縁樹脂層２１との境界部における導電層２２部分の孔径Ｄａ（図３参照）より導電層２２の外表面側の孔径Ｄｂ（図３参照）が小さく、導電層２２部分の貫通孔２４の内壁面２６が縦断面で見て曲面（近円弧面）あるいは傾斜面で、導電層２２部分の貫通孔２４が導電層外表面側が先細となるテーパ状であるから、貫通孔内壁面２６の面積が同一径によるストレートな貫通孔である場合に比して大きくなり、貫通孔２４に充填された導電性樹脂組成物２５と導電層２２との導通接触が、増大された貫通孔内壁面２６で取られ、従来のものように、導電性樹脂組成物の導電層より上の部分（ヘッド状部）を設けなくても、導電性樹脂組成物２５と導電層２２との接触面積を確保でき、基板の平滑性を低下させることなく、薄い多層配線基板を得ることができる。
【００４７】
つぎに、図１に示されている多層配線基板用基材の製造方法、およびその多層配線基板用基材による多層配線基板の製造方法の一実施形態を図５、図６を参照して詳細に説明する。
【００４８】
まず、図５（ａ）、（ｂ）に示されているように、絶縁樹脂層（ポリイミドフィルム）１１の片面に銅箔による導電層１２を設けられた基材の絶縁樹脂層１１側に、熱可塑性ポリイミドあるいは熱可塑性ポリイミドに熱硬化機能を付与したフィルムを貼り付けて接着層１３を形成し、接着層１３側にＰＥＴによるマスキングテープ１８を貼り付ける。
【００４９】
つぎに、第１穴あけ工程として、図５（ｃ）に示されているように、マスキングテープ１８の側からレーザ光照射を行い、マスキングテープ１８を貫通して導電層１２を除いた部分、すなわち接着層１３と絶縁樹脂層１１とに、導電層１２と絶縁樹脂層１１との境界部における絶縁樹脂層１１部分の孔径がＤｃとなるＩＶＨのための略ストレートな孔１４Ｂをあける。
【００５０】
つぎに、図５（ｄ）に示されているように、導電層１２の表面に回路形成のためのエッチングレジスト１９を形成し、図５（ｅ）に示されているように、エッチングレジスト１９をマスクとして導電層１２側からエッチャントを侵蝕させて導電層１２に回路形成のためのエッチングを施すと同時に、第２穴あけ工程として、接着層１３、絶縁樹脂層１１にあけられている孔１４Ｂの側からもエッチャントを侵蝕させ、貫通孔形成のための等方性エッチングを導電層１２に施し、導電層１２にＩＶＨのための孔１４Ａをあける。
【００５１】
導電層１２が銅箔の場合、導電層１２に行う等方性エッチングは、塩化第２鉄を主成分とした水溶液や塩化第２銅を主成分としたエッチャントを用いて行うことができる。
【００５２】
等方性エッチングの場合、サイドエッチングによって導電層１２部分の貫通孔１４（孔１４Ａ）の内壁面１６は、図５（ｅ）に示されているように、縦断面で見て曲面（近円弧面）あるいは傾斜面になり、導電層１２部分の貫通孔１４はアンダカットを含んで導電層外表面側が先細となるテーパ状になる。
【００５３】
エッチングが完了すれば、図５（ｆ）に示されているように、エッチングレジスト１９を除去し、ＩＶＨのための貫通孔１４が完成する。この場合、貫通孔１４は、導電層１２と絶縁樹脂層１１との境界部における導電層１２部分の孔径Ｄａより導電層１２の外表面側の孔径Ｄｂが小さく、しかも、貫通孔１４の導電層１２と絶縁樹脂層１１との境界部における導電層１２部分の孔径Ｄａがこの境界部における絶縁樹脂層１１部分の孔径Ｄｃより大きいものになる。
【００５４】
貫通孔１４の穿孔が完了すれば、図５（ｇ）に示されているように、スクリーン印刷で使用するようなスキージプレート５１を使用してマスキングテープ１８側から導電性樹脂組成物（導電ペースト）１５をスクイジング（印刷法）によって貫通孔１４に穴埋め充填する。図５（ｈ）は、導電性樹脂組成物１５の穴埋め充填完了状態を示している。
【００５５】
導電性樹脂組成物１５は、後の工程における加熱に対する酸化を避けるため、銀ペーストを使用した。この時、粘度を３００ｄＰａ・ｓのものを使用したところ、銅箔部（導電層１２）の孔１４Ａから導電ペーストが抜け落ちることなく的確に穴埋め充填することができた。なお、導電性樹脂組成物１５としては、銀ペースト以外に、銅フィラーやカーボン混合物による導電性ペーストを使用することも可能である。
【００５６】
基材にはＰＥＴによるマスキングテープ１８が貼り付けられているから、メタルマスクやスクリーンマスクを介さず、スキージプレート５１を基材に直接接触させて穴埋めを行うことができるが、メタルマスクやスクリーンマスクを介して穴埋めを行うこともでき、導電性樹脂組成物１５の無駄を削減できる。
【００５７】
貫通孔１４は、導電層１２と絶縁樹脂層１１との境界部における導電層１２部分の孔径Ｄａより導電層１２の外表面側の孔径Ｄｂが小さく、ＩＶＨ（貫通孔１４）断面の導電層１２部分の形状が近円弧状であるため、銅箔部（導電層１２）と導電性樹脂組成物１５との密着が導電層１２部分の貫通孔１４の内壁面（側周面）１６で十分に行われる。
【００５８】
導電層１２部分の貫通孔１４の孔径は、導電性樹脂組成物１５との接触抵抗からの要求に加えて、導電性樹脂組成物１５の粘度やチキソ性といった諸特性に応じ、気泡の残留と導電性樹脂組成物１５の脱落を回避できるように選択することになり、３０〜５０μｍ程度になる。
【００５９】
導電性樹脂組成物１５の充填が完了すれば、図５（ｉ）に示されているように、メマスキングテープ１８を外して１枚の基材１０Ａを完成する。
【００６０】
この基材１０Ａを１層目の基材とし、図５（ａ）〜（ｉ）に示されているこれまでと同様の製法で作製した基材１０Ｂと、銅箔による導電層１７を各々適当な位置合わせ法によって位置合わせしつつ積層加熱圧着（ラミネーション）することで、図６（ａ）、（ｂ）に示されているように、多層化が達成される。
【００６１】
ラミネーションの際、基板を真空下に曝しながら加熱圧着することで、導電層１２による回路パターンの凹凸に対する接着層１３の追従性を高くすることができる。また、導電性樹脂組成物１５が柔らかい状態で積層を行い、導電性樹脂組成物１５と他層の銅箔との接触を密接にすることができる。
【００６２】
最後に、図６（ｃ）に示されているように、最外層の導電層１７をエッチングによって回路形成することで、多層配線板として完成を見る。
【００６３】
なお、図３に示されている多層配線基板用基材、およびその多層配線基板用基材による多層配線基板も、上述した製造方法と同等の製造方法によって製造することができる。
【００６４】
（実施形態２）
図７（ａ）、（ｂ）はこの発明による他の実施形態に係わる多層配線基板用基材の基本構成を示している。なお、図７（ａ）、（ｂ）において、図１に対応する部分は、図１に付した符号と同一の符号を付けて、その説明を省略する。
【００６５】
図７（ａ）、（ｂ）に示されている多層配線基板用基材は、図１に示されているものと同様に、絶縁性基材をなす絶縁樹脂層１１の一方の面に配線パターンをなす銅箔等による導電層１２を、他方の面に層間接着のための接着層１３を各々設けられ、接着層１３と絶縁樹脂層１１と導電層１２とを貫通する貫通孔１４を穿設されている。貫通孔１４には導電性樹脂組成物１５が充填され、ＩＶＨ（バイアホール）を形成している。
【００６６】
この実施の形態でも、ＦＰＣでは、絶縁樹脂層１１は、全芳香族ポリイミド（ＡＰＩ）等によるポリイミドフィルムやポリエステルフィルム等の可撓性を有する樹脂フィルムで構成でき、絶縁樹脂層１１と導電層１２と接着層１３との３層構造は、汎用の片面銅箔付きポリイミド基材（銅張樹脂基材）を出発基材として、ポリイミド部（絶縁樹脂層１１）の銅箔（導電層１２）とは反対側の面に接着層１３としてポリイミド系接着材を貼付したもので構成できる。
【００６７】
また、導電性樹脂組成物１５は、導電機能を有する金属粉末を樹脂バインダに混入したものを溶剤を含む粘性媒体に混ぜてペースト状にした導電性ペーストであってよく、接着層１３の側よりスクイジング等によって貫通孔１４に満遍なく穴埋め充填される。
【００６８】
ここで、図７（ａ）に示す実施形態では、貫通孔１４は、導電層１２と絶縁樹脂層１１との境界部における導電層１２部分の孔径Ｄａより導電層１２の外表面側の孔径Ｄｂが小さく、すなわち、Ｄａ＞Ｄｂで、しかも、導電層１２と絶縁樹脂層１１との境界部における絶縁樹脂層１１部分の孔径Ｄｃが、この境界部における導電層１２部分の孔径Ｄａに等しいか、これより少し大きい、すなわち、Ｄｃ≧Ｄａに形成され、孔内全域に導電性樹脂組成物１５を充填されている。
【００６９】
これにより、貫通孔１４のうち、導電層１２を貫通する部分（孔）１４Ａ（図５（ｅ）参照）の内壁面１６が縦断面で見て曲面あるいは傾斜面で、貫通孔１４は、導電層部分１４Ａにおいて、導電層外表面側が先細となるテーパ状、換言すれば、すり鉢状をなしている。
【００７０】
貫通孔１４の穿孔は、第１穴あけ工程として、絶縁樹脂層１１および接着層１３にレーザ加工あるいは異方性エッチングによって所定孔径による略ストレートな孔１４Ｂ（図１１（ｃ）参照）をあけ、第１穴あけ工程完了後に、第２穴あけ工程として、穴あけされた接着層・絶縁樹脂層の側（図７にて上側）から、すなわち、孔１４Ｂより等方性を有するエッチングによって導電層１２に、導電層１２と絶縁樹脂層１１との境界部における導電層１２部分の孔径Ｄａより導電層１２の外表面側の孔径Ｄｂが小さい孔１４Ａをあけ、この後に、第３穴あけ工程として、絶縁樹脂層１１および接着層１３の孔１４Ｂを、導電層１２と絶縁樹脂層１１との境界部における絶縁樹脂層１１部分の孔径Ｄｃがこの境界部における導電層１２部分の孔径Ｄａに等しいか、これより少し大きい孔１４Ｃ（図１１（ｇ）参照）に拡大する。
【００７１】
この場合も、導電層１２を貫通する部分１４Ａの貫通孔１４の内壁面形状は、等方性エッチングにおける縦方向進行速度と横方向進行速度との速度比等により決まり、エッチャントの選定により、全体が一つの曲率による湾曲面（球面）、異なる複数の曲率による湾曲面が滑らかに連続した曲面、その他、回転楕円面、回転放物線面、あるいは直線状の傾斜面等、任意のものにできる。
【００７２】
この多層配線基板用基材では、貫通孔１４の導電層１２と絶縁樹脂層１１との境界部における導電層１２部分の孔径Ｄａより導電層１２の外表面側の孔径Ｄｂが小さいから、導電層１２部分の貫通孔１４の内壁面１６が縦断面で見て曲面（近円弧面）あるいは傾斜面で、導電層１２部分の貫通孔１４は導電層外表面側が先細となるテーパ状になり、貫通孔内壁面１６の面積が同一径によるストレートな貫通孔である場合に比して大きくなる。
【００７３】
これにより、貫通孔１４に充填された導電性樹脂組成物１５と導電層１２との導通接触が、増大された貫通孔内壁面（側周面）１６で、所要の接触面積をもって信頼性高く行われ、導電性樹脂組成物の導電層より上の部分（ヘッド状部）と導電層との接触面積確保から派生する諸問題から解放される。
【００７４】
しかも、貫通孔１４の導電層１２と絶縁樹脂層１１との境界部における絶縁樹脂層１１部分の孔径Ｄｃが、この境界部における導電層１２部分の孔径Ｄａに等しいか、あるいはこれより少し大きいことにより、接着層１３の側から貫通孔１４内に行われる導電性樹脂組成物１５の充填において、それの充填流れに対して淀み領域になるアンダカット領域がなく、貫通孔１４内に気泡が残留することがなく、導電層１２部分の貫通孔１４の内壁面１６における導電性樹脂組成物１５と導電層１２との導通接触が所要の面積をもって確実に行われるようになる。
【００７５】
図７（ｂ）は、図７（ａ）に示した実施形態の変形例である。ここで、図７（ｂ）に示す変形例では、貫通孔１４は、導電層１２と絶縁樹脂層１１との境界部における導電層１２部分の孔径Ｄａより導電層１２の外表面側の孔径Ｄｂが小さく、すなわち、Ｄａ＞Ｄｂで、しかも、導電層１２と絶縁樹脂層１１との境界部における絶縁樹脂層１１部分の孔径Ｄｃが、この境界部における導電層１２部分の孔径Ｄａより大きい、すなわち、Ｄｃ＞Ｄａに形成され、孔内全域に導電性樹脂組成物１５を充填されている。
【００７６】
すなわち、この図７（ｂ）に示した変形例によれば、図７（ａ）に示した実施形態の効果に加え、導電性樹脂組成物１５と導電層１２との接触面積が図７（ｂ）のＥで示す部分だけ拡大するので、より接続性が向上する効果がある。
【００７７】
図８はこの発明による多層配線基板の他の実施形態を示している。この多層配線基板は、図７に示されている構造の多層配線基板用基材を、１層目の基材１０Ａと２層目の基材１０Ｂとして、２枚重ね合わせ、１層目の基材１０Ａの接着層１３によって１層目の基材１０Ａと２層目の基材１０Ｂとを互いに接着接合してなる。２層目の基材１０Ｂの接着層１３上には表面部の配線パターンをなす銅箔による導電層１７が形成されている。
【００７８】
導電性樹脂組成物１５を充填された各貫通孔１４はＩＶＨをなし、各貫通孔１４の導電層１２と絶縁樹脂層１１との境界部における導電層１２部分の孔径Ｄａ（図７参照）より導電層１２の外表面側の孔径Ｄｂ（図７参照）が小さく、導電層１２部分の貫通孔１４の内壁面１６が縦断面で見て曲面（近円弧面）あるいは傾斜面で、導電層１２部分の貫通孔１４が導電層外表面側が先細となるテーパ状であるから、貫通孔内壁面１６の面積が同一径によるストレートな貫通孔である場合に比して大きくなり、貫通孔１４に充填された導電性樹脂組成物１５と導電層１２との導通接触が、増大された貫通孔内壁面１６で取られ、従来のものように、導電性樹脂組成物の導電層より上の部分（ヘッド状部）を設けなくても、導電性樹脂組成物１５と導電層１２との接触面積を確保でき、基板の平滑性を低下させることなく、薄い多層配線基板を得ることができる。
【００７９】
しかも、貫通孔１４の導電層１２と絶縁樹脂層１１との境界部における絶縁樹脂層１１部分の孔径Ｄｃ（図７参照）が、この境界部における導電層１２部分の孔径Ｄａに等しいか、あるいはこれより少し大きいことにより、
接着層１３の側から貫通孔１４内に行われる導電性樹脂組成物１５の充填において、それの充填流れに対して淀み領域になるアンダカット領域がなく、貫通孔１４内に気泡が残留することがなく、導電層１２部分の貫通孔１４の内壁面１６における導電性樹脂組成物１５と導電層１２との導通接触が所要の面積をもって確実に行われるようになる。
【００８０】
この実施の形態においても、多層配線基板用基材は、図９に示されているように、絶縁性基材をなす絶縁樹脂層２１を、熱可塑性ポリイミド（ＴＰＩ）あるいは熱可塑性ポリイミドに熱硬化機能を付与したものなど、絶縁樹脂層自体が層間接着のための接着性を有するもので構成することができる。この場合には、絶縁樹脂層２１の一方の面に配線パターンをなす銅箔等による導電層２２を設け、他方の面の積層する接着層を省略できる。
【００８１】
この多層配線基板用基材では、絶縁樹脂層２１と導電層２２とを貫通する貫通孔２４を穿設され、その貫通孔２４に導電性樹脂組成物２５が充填されてＩＶＨ（バイアホール）が形成される。
【００８２】
貫通孔２４は、導電層２２と絶縁樹脂層２１との境界部における導電層１２部分の孔径Ｄａより導電層２２の外表面側の孔径Ｄｂが小さく、すなわち、Ｄａ＞Ｄｂで、しかも、導電層２２と絶縁樹脂層２１との境界部における絶縁樹脂層２１部分の孔径Ｄｃが、この境界部における導電層１２部分の孔径Ｄａに等しいか、これより少し大きい、すなわち、Ｄｃ≧Ｄａに形成され、孔内全域に導電性樹脂組成物１５を充填されている。
【００８３】
これにより、貫通孔２４のうち、導電層２２を貫通する部分の内壁面２６が縦断面で見て曲面あるいは傾斜面で、貫通孔２４は、導電層２２部分において、導電層外表面側が先細となるテーパ状、換言すれば、すり鉢状をなしている。
【００８４】
貫通孔２４の穿孔は、第１穴あけ工程として、絶縁樹脂層２１にレーザ加工あるいは異方性エッチングによって所定孔径による略ストレートな孔をあけ、第１穴あけ工程完了後に、第２穴あけ工程として、穴あけされた絶縁樹脂層２１の側（図９にて上側）から、すなわち、絶縁樹脂層２１にあけられた孔より等方性を有するエッチングによって導電層２２に、導電層２２と絶縁樹脂層２１との境界部における導電層２２部分の孔径Ｄａより導電層２２の外表面側の孔径Ｄｂが小さい孔をあけ、この後に、第３穴あけ工程として、絶縁樹脂層２１の孔２４Ｂを、貫通孔２４の導電層２２と絶縁樹脂層２１との境界部における絶縁樹脂層２１の孔径Ｄｃが、この境界部における導電層１２部分の孔径Ｄａに等しいか、これより少し大きい孔に拡大する。
【００８５】
この場合も、導電層２２を貫通する部分の貫通孔２４の内壁面形状は、等方性エッチングにおける縦方向進行速度と横方向進行速度との速度比等により決まり、液状エッチャントの選定により、全体が一つの曲率による湾曲面（球面）、異なる複数の曲率による湾曲面が滑らかに連続した曲面、その他、回転楕円面、回転放物線面、あるいは直線状の傾斜面等、任意のものにできる。
【００８６】
この多層配線基板用基材でも、貫通孔２４の導電層２２と絶縁樹脂層２１との境界部における導電層２２部分の孔径Ｄａより導電層２２の外表面側の孔径Ｄｂが小さいから、導電層２２部分の貫通孔２４の内壁面２６が縦断面で見て曲面（近円弧面）あるいは傾斜面で、導電層２２部分の貫通孔２４は導電層外表面側が先細となるテーパ状になり、貫通孔内壁面２６の面積が同一径によるストレートな貫通孔である場合に比して大きくなる。
【００８７】
これにより、貫通孔２４に充填された導電性樹脂組成物２５と導電層２２との導通接触が、増大された貫通孔内壁面（側周面）２６で、所要の接触面積をもって信頼性高く行われ、導電性樹脂組成物の導電層より上の部分（ヘッド状部）と導電層との接触面積確保から派生する諸問題から解放される。
【００８８】
しかも、通孔２４の導電層２２と絶縁樹脂層２１との境界部における絶縁樹脂層２１部分の孔径Ｄｃが、この境界部における導電層１２部分の孔径Ｄａに等しいか、これより少し大きいことにより、絶縁樹脂層２１の側から貫通孔２４内に行われる導電性樹脂組成物２５の充填において、それの充填流れに対して淀み領域になるアンダカット領域がなく、貫通孔２４内に気泡が残留することがなく、導電層２２部分の貫通孔２４の内壁面２６における導電性樹脂組成物２５と導電層２２との導通接触が所要の面積をもって確実に行われるようになる。
【００８９】
図１０はこの発明による多層配線基板の他の実施形態を示している。この多層配線基板は、図９に示されている構造の多層配線基板用基材を、１層目の基材２０Ａと２層目の基材２０Ｂとして、２枚重ね合わせ、１層目の基材２０Ａの接着性を有する絶縁樹脂層２１によって１層目の基材２０Ａと２層目の基材２０Ｂとを互いに接着接合してなる。２層目の基材２０Ｂの絶縁樹脂層２１上には表面部の配線パターンをなす銅箔による導電層２７が形成されている。
【００９０】
この多層配線基板でも、導電性樹脂組成物２５を充填された各貫通孔２４はＩＶＨをなし、各貫通孔２４の導電層２２と絶縁樹脂層２１との境界部における導電層２２部分の孔径Ｄａ（図９参照）より導電層２２の外表面側の孔径Ｄｂ（図９参照）が小さく、導電層２２部分の貫通孔２４の内壁面２６が縦断面で見て曲面（近円弧面）あるいは傾斜面で、導電層２２部分の貫通孔２４が導電層外表面側が先細となるテーパ状であるから、貫通孔内壁面２６の面積が同一径によるストレートな貫通孔である場合に比して大きくなり、貫通孔２４に充填された導電性樹脂組成物２５と導電層２２との導通接触が、増大された貫通孔内壁面２６で取られ、従来のものように、導電性樹脂組成物の導電層より上の部分（ヘッド状部）を設けなくても、導電性樹脂組成物２５と導電層２２との接触面積を確保でき、基板の平滑性を低下させることなく、薄い多層配線基板を得ることができる。
【００９１】
しかも、貫通孔２４の導電層２２と絶縁樹脂層２１との境界部における絶縁樹脂層２１部分の孔径Ｄｃ（図９参照）が、この境界部における導電層２２部分の孔径Ｄａに等しいか、これより少し大きいことにより、絶縁樹脂層２１の側から貫通孔２４内に行われる導電性樹脂組成物２５の充填において、それの充填流れに対して淀み領域になるアンダカット領域がなく、貫通孔２４内に気泡が残留することがなく、導電層２２部分の貫通孔２４の内壁面２６における導電性樹脂組成物２５と導電層２２との導通接触が所要の面積をもって確実に行われるようになる。
【００９２】
つぎに、図７に示されている多層配線基板用基材の製造方法、およびその多層配線基板用基材による多層配線基板の製造方法の一実施形態を図１１、図１２を参照して詳細に説明する。
【００９３】
まず、図１１（ａ）、（ｂ）に示されているように、絶縁樹脂層（ポリイミドフィルム）１１の片面に銅箔による導電層１２を設けられた基材の絶縁樹脂層１１側に、熱可塑性ポリイミドあるいは熱可塑性ポリイミドに熱硬化機能を付与したフィルムを貼り付けて接着層１３を形成し、接着層１３側にＰＥＴによるマスキングテープ１８を貼り付ける。
【００９４】
つぎに、第１穴あけ工程として、図１１（ｃ）に示されているように、マスキングテープ１８の側からレーザ光照射を行い、マスキングテープ１８を貫通して導電層１２を除いた部分、すなわち接着層１３と絶縁樹脂層１１とに、所定孔径によるＩＶＨのための略ストレートな孔１４Ｂをあける。
【００９５】
つぎに、図１１（ｄ）に示されているように、導電層１２の表面に回路形成のためのエッチングレジスト１９を形成し、図１１（ｅ）に示されているように、エッチングレジスト１９をマスクとして導電層１２側からエッチャントを侵蝕させて導電層１２に回路形成のためのエッチングを施すと同時に、第２穴あけ工程として、接着層１３、絶縁樹脂層１１にあけられている孔１４Ｂの側からもエッチャントを侵蝕させ、貫通孔形成のための等方性エッチングを導電層１２に施し、導電層１２にＩＶＨのための孔１４Ａをあける。
【００９６】
導電層１２が銅箔の場合、導電層１２に行う等方性エッチングは、塩化第２鉄を主成分とした水溶液や塩化第２銅を主成分としたエッチャントを用いて行うことができる。
【００９７】
等方性エッチングの場合、サイドエッチングによって導電層１２部分の貫通孔１４（孔１４Ａ）の内壁面１６は、図１１（ｅ）に示されているように、縦断面で見て曲面（近円弧面）あるいは傾斜面になり、導電層１２部分の貫通孔１４はアンダカットを含んで導電層外表面側が先細となるテーパ状になる。
【００９８】
エッチングが完了すれば、図１１（ｆ）に示されているように、エッチングレジスト１９を除去し、その後に、図１１（ｇ）に示されているように、第３穴あけ工程として、接着層１３、絶縁樹脂層１１にあけられている孔１４Ｂの孔径を、レーザ加工によって、導電層１２と絶縁樹脂層１１との境界部における導電層１２部分の孔径Ｄａとほぼ等しい孔径Ｄｃに拡大し、ＩＶＨのための貫通孔１４が完成する。この場合、貫通孔１４は、導電層１２と絶縁樹脂層１１との境界部における導電層１２部分の孔径Ｄａより導電層１２の外表面側の孔径Ｄｂが小さく、しかも、導電層１２と絶縁樹脂層１１との境界部における絶縁樹脂層１１部分の孔径Ｄｃが、この境界部における導電層１２部分の孔径Ｄａにほぼ等しいものになる。
【００９９】
貫通孔１４の穿孔が完了すれば、図１１（ｈ）に示されているように、スクリーン印刷で使用するようなスキージプレート５１を使用してマスキングテープ１８側から導電性樹脂組成物（導電ペースト）１５をスクイジング（印刷法）によって貫通孔１４に穴埋め充填する。図１１（ｉ）は、導電性樹脂組成物１５の穴埋め充填完了状態を示している。
【０１００】
貫通孔１４は、導電層１２と絶縁樹脂層１１との境界部における導電層１２部分の孔径Ｄａより導電層１２の外表面側の孔径Ｄｂが小さく、ＩＶＨ（貫通孔１４）断面の導電層１２部分の形状が近円弧状であるため、銅箔部（導電層１２）と導電性樹脂組成物１５との密着が導電層１２部分の貫通孔１４の内壁面（側周面）１６で十分に行われる。しかも、貫通孔１４の導電層１２と絶縁樹脂層１１との境界部における絶縁樹脂層１１部分の孔径Ｄｃが、この境界部における導電層１２部分の孔径Ｄａにほぼ等しいことにより、接着層１３の側から貫通孔１４内に行われる導電性樹脂組成物１５の充填において、それの充填流れに対して淀み領域になるアンダカット領域がなく、貫通孔１４内に有害な気泡が残留することがない。
【０１０１】
導電性樹脂組成物１５の充填が完了すれば、図１１（ｊ）に示されているように、メマスキングテープ１８を外して１枚の基材１０Ａを完成する。
【０１０２】
この基材１０Ａを１層目の基材とし、図１１（ａ）〜（ｊ）に示されているこれまでと同様の製法で作製した基材１０Ｂと、銅箔による導電層１７を各々適当な位置合わせ法によって位置合わせしつつ積層加熱圧着（ラミネーション）することで、図１２（ａ）、（ｂ）に示されているように、多層化が達成される。
【０１０３】
ラミネーションの際、基板を真空下に曝しながら加熱圧着することで、導電層１２による回路パターンの凹凸に対する接着層１３の追従性を高くすることができる。また、導電性樹脂組成物１５が柔らかい状態で積層を行い、導電性樹脂組成物１５と他層の銅箔との接触を密接にすることができる。
【０１０４】
最後に、図１２（ｃ）に示されているように、最外層の導電層１７をエッチングによって回路形成することで、多層配線板として完成を見る。
【０１０５】
なお、図９に示されている多層配線基板用基材、およびその多層配線基板用基材による多層配線基板も、上述した製造方法と同等の製造方法によって製造することができる。
【０１０６】
（その他の実施形態）
上述の実施形態では、いずれも、フレキシブルプリント配線板について述べたが、この発明はこれに限られることはなく、絶縁性基材がエポキシ樹脂系やプリプレグ等によるリジットタイプのプリント配線板にも同様に適用できる。
【０１０７】
【発明の効果】
以上の説明から理解される如く、この発明による多層配線基板、多層配線基板用基材およびその製造方法によれば、貫通孔の孔径が、導電層と絶縁性基材との境界部における導電層部分の孔径Ｄａより導電層の外表面側の孔径Ｄｂのほうが小さく、導電層部分の貫通孔の内壁面が縦断面で見て曲面（近円弧面）あるいは傾斜面で、導電層外表面側が先細となるテーパ状の貫通孔になるから、貫通孔内壁面の面積が同一径によるストレートな貫通孔である場合に比して大きくなり、貫通孔に充填された導電性樹脂組成物と導電層との導通接触が、増大された貫通孔内壁面（側周面）で確実に取られ、導電性樹脂組成物の導電層より上の部分（ヘッド状部）と導電層との接触面積確保から派生する諸問題から解放され、導電性樹脂組成物と導電層との導通が高い信頼性をもって安定して行われるようになる。
【図面の簡単な説明】
【図１】この発明の実施形態１に係わる多層配線基板用基材の基本構成を示す断面図である。
【図２】この発明の実施形態１に係わる多層配線基板を示す断面図である。
【図３】この発明の実施形態１に係わる多層配線基板用基材の他の基本構成を示す断面図である。
【図４】この発明の実施形態１に係わる多層配線基板を示す断面図である。
【図５】（ａ）〜（ｉ）はこの発明の実施形態１に係わる多層配線基板用基材の製造方法の一実施形態を示す工程図である。
【図６】（ａ）〜（ｃ）はこの発明の実施形態１に係わる多層配線基板の製造方法の一実施形態を示す工程図である。
【図７】（ａ）はこの発明の実施形態２に係わる多層配線基板用基材の基本構成を示す断面図であり、（ｂ）はその変形例である。
【図８】この発明の実施形態２に係わる多層配線基板を示す断面図である。
【図９】この発明の実施形態２に係わる多層配線基板用基材の他の基本構成を示す断面図である。
【図１０】この発明の実施形態２に係わる多層配線基板を示す断面図である。
【図１１】（ａ）〜（ｊ）はこの発明の実施形態２に係わる多層配線基板用基材の製造方法の一実施形態を示す工程図である。
【図１２】（ａ）〜（ｃ）はこの発明の実施形態２に係わる多層配線基板の製造方法の一実施形態を示す工程図である。
【図１３】従来の多層配線基板用基材のＩＶＨ構造を示す断面図である。
【図１４】従来の多層配線基板用基材のＩＶＨ構造における不具合を示す断面図である。
【符号の説明】
１０Ａ　１層目の基材
１０Ｂ　２層目の基材
１１　絶縁樹脂層
１２　導電層
１３　接着層
１４　貫通孔
１５　導電性樹脂組成物
１６　内壁面
１７　導電層
２０Ａ　１層目の基材
２０Ｂ　２層目の基材
２１　絶縁樹脂層
２２　導電層
２４　貫通孔
２５　導電性樹脂組成物
２６　内壁面
２７　導電層[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a multilayer wiring board (multilayer printed wiring board), a base material for the multilayer wiring board, and a method for manufacturing the same, and more particularly, to a multilayer wiring board such as a multilayer flexible printed wiring board capable of high-density mounting such as flip-chip mounting. And a method for manufacturing the same.
[0002]
[Prior art]
Polyimide resin is a resin having high heat resistance, electrical insulation, and high flexibility, and is used as an insulating layer material of a printed wiring board such as a flexible printed wiring board (FPC). One of the applications of a polyimide resin as an insulating layer material is a multilayer FPC in which a flexible printed wiring board (FPC) using a polyimide film as an insulating layer material is multilayer-stacked, and interlayer conduction is provided by through holes that are collectively drilled. .
[0003]
However, in a multilayer FPC using through holes, the degree of freedom in wiring design is low due to restrictions on interlayer connection positions, and it is not possible to mount a chip on the through holes. In recent years, it has become impossible to meet the demand for higher density mounting.
[0004]
In order to cope with this, interlayer connection is performed by IVH (Interstitial Via Hole) without using through holes, and a resin multilayer printed wiring board capable of via-on-via, for example, ALIVH (Any Layer) of Matsushita Electric Industrial Co., Ltd. An Interstitial Via Hole) substrate and a polyimide composite multilayer build-up integrated circuit board (MOSAIC) manufactured by Sony Chemical Co., Ltd., in which FPCs made of polyimide are stacked in multiple layers by a build-up method without using through holes, have been developed.
[0005]
In addition, using a general-purpose copper-clad resin base material having a polyimide film as an insulating layer and a conductive layer made of copper foil adhered to one side thereof as a starting base material, a structure and manufacturing method for obtaining a multilayer FPC having an IVH structure by a simple process. Has been proposed in Japanese Patent Application No. 2001-85224 filed by the same applicant as the present applicant.
[0006]
In the base material for a multilayer wiring board proposed in Japanese Patent Application No. 2001-85224, a through-hole (via hole) is formed in a copper-clad resin base material having a copper foil provided on one surface of an insulating layer, and then a conductive material is formed. By filling the resin composition (resin-based conductive paste) from the copper foil side by a printing method such as a screen printing method, an IVH portion as shown in FIG. 13 is formed. 13, reference numeral 101 denotes an insulating layer, 102 denotes a copper foil portion, 104 denotes a through hole, and 105 denotes a conductive resin composition filled in the through hole 104.
[0007]
By making the diameter of the opening of the mask at the time of screen printing larger than the IVH diameter, a certain margin can be given to the alignment accuracy at the time of printing, and the mask opening of the conductive resin composition 105 on the copper foil portion 102 can be provided. A head-shaped part 105A having a size equivalent to the diameter of the part is formed, and the contact area between the conductive resin composition 105 filled in the through hole 104 and the copper foil part 102 can be increased. Also, the conductive resin composition 105 can be prevented from falling out of the through hole 104.
[0008]
[Problems to be solved by the invention]
However, since the head-shaped portion 105A projects with a thickness of about several tens of μm from the surface of the base material due to the thickness of the printing mask or the like, the surface of the copper foil portion 102 is required to secure the surface smoothness of the multilayer wiring board. A sufficient thickness of the adhesive layer is required to embed the entire head-shaped portion 105A in the layer of the interlayer adhesive, and the increase in the thickness of the adhesive layer causes an increase in the thickness of the multilayer wiring board. Become. On the other hand, if the thickness of the adhesive layer is not increased, the surface smoothness of the multilayer wiring board will be reduced.
[0009]
Before the conductive resin composition is completely cured, by performing multilayer lamination, it is conceivable that the conductive resin composition and the copper foil of the other layer are brought into close contact with each other, however, In this case, as shown in FIG. 14, the portion (head-like portion 105A) of the conductive resin composition 105 above the copper foil portion 102 is crushed and crushed by the lamination pressure P during multilayer lamination. In this state, the size of the head-like portion 105A as viewed from the substrate surface is not only uniform, but also the conductive resin composition of the head-like portion 105A spreads to other wiring portions 102 '. This may cause a short circuit in the circuit.
[0010]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has been made in consideration of the above-described problems, and has been made in view of the thin multilayer wiring without deteriorating the contact reliability between the conductive tree composition and the conductive circuit portion and without reducing the smoothness of the substrate. It is an object of the present invention to provide a substrate for a multilayer wiring board from which a substrate can be obtained, a method for manufacturing the same, and a multilayer wiring board.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, a multilayer wiring board base material according to the present invention is provided with a conductive layer such as a copper foil forming a wiring pattern on one surface of an insulating base material, and the insulating base material and the conductive layer A multi-layer wiring board base material filled with a conductive resin composition for obtaining interlayer conduction in a through-hole penetrating through the through-hole, wherein at a boundary portion between the conductive layer and the insulating base material of the through-hole, The hole diameter Db on the outer surface side of the conductive layer is smaller than the hole diameter Da of the conductive layer portion.
[0012]
According to the base material for a multilayer wiring board, the hole diameter of the through hole is smaller at the boundary between the conductive layer and the insulating base material at the outer surface side of the conductive layer than at the boundary diameter Da of the conductive layer portion. The inner wall surface of the through hole in the conductive layer portion is a curved surface (near circular arc surface) or an inclined surface when viewed in a longitudinal section, and the outer surface side of the conductive layer becomes a tapered through hole that tapers. The conductive contact between the conductive resin composition and the conductive layer filled in the through hole is increased as compared with the case of the straight through hole having the same diameter, and the increased inner wall surface (side peripheral surface) of the through hole. It is reliably taken and is free from various problems derived from securing a contact area between the conductive layer and the portion of the conductive resin composition above the conductive layer (head-shaped portion).
[0013]
Further, in the base material for a multilayer wiring board according to the present invention, the hole diameter Da of the conductive layer portion at the boundary between the conductive layer and the insulating base material of the through hole is defined by the assumption that the hole diameter Da> the hole diameter Db. The hole diameter Dc of the insulating substrate portion in the portion may be larger than the hole diameter Dc, and the size relationship between the hole diameters Da, Db, and Dc may be as follows: hole diameter Da> hole diameter Dc> hole diameter Db.
[0014]
Further, the base material for a multilayer wiring board according to the present invention has a hole diameter Dc of a portion of the insulating base material at a boundary portion between the conductive layer and the insulating base material of the through hole, assuming that a hole size Da> a hole size Db. The diameter may be equal to or larger than the hole diameter Da of the conductive layer portion at the boundary.
[0015]
Further, the base material for a multilayer wiring board according to the present invention is provided with a conductive layer forming a wiring pattern on one surface of an insulating base material and an adhesive layer for interlayer bonding on the other surface. A multi-layer wiring board base material filled with a conductive resin composition for obtaining interlayer conduction in a through hole penetrating an insulating base material and the adhesive layer, wherein the conductive layer and the insulating property of the through hole are filled. The hole diameter Db on the outer surface side of the conductive layer is smaller than the hole diameter Da of the conductive layer portion at the boundary with the base material.
[0016]
Also in this substrate for a multilayer wiring board, since the hole diameter of the through hole is smaller at the boundary between the conductive layer and the insulating substrate, the hole diameter Db on the outer surface side of the conductive layer is smaller than the hole diameter Da of the conductive layer portion. The inner wall surface of the through hole in the layer portion is a curved surface (near circular arc surface) or an inclined surface when viewed in a longitudinal section, and the outer surface side of the conductive layer is a tapered through hole having a tapered shape. And the conductive contact between the conductive resin composition filled in the through-hole and the conductive layer is ensured by the increased inner wall surface (side peripheral surface) of the through-hole. It is removed from the problems arising from securing the contact area between the portion (head-like portion) of the conductive resin composition above the conductive layer and the conductive layer.
[0017]
Further, even in a base material for a multilayer wiring board in which a conductive layer forming a wiring pattern is provided on one surface of an insulating base material and an adhesive layer for interlayer bonding is provided on the other surface, it is assumed that a hole diameter Da> a hole diameter Db. The hole diameter Da of the conductive layer portion at the boundary between the conductive layer and the insulating base of the through hole is larger than the hole diameter Dc of the insulating base portion at the boundary, and further, the hole diameters Da and Db , Dc, the diameter of the hole is greater than the diameter of the hole Da> the diameter of the hole Dc> the diameter of the hole Db, or the hole diameter Dc of the insulating substrate portion at the boundary between the conductive layer and the insulating substrate of the through hole is The diameter may be equal to or larger than the hole diameter Da of the conductive layer portion at the boundary.
[0018]
In the base material for a multilayer wiring board according to the present invention, the insulating base material is made of a flexible resin film such as polyimide, and a conductive layer made of copper foil is attached to one surface of the flexible resin film. Can be used as a starting substrate. Further, the adhesive layer can be made of thermoplastic polyimide.
[0019]
A multilayer wiring board according to the present invention is obtained by laminating and joining a plurality of base materials for a multilayer wiring board according to the above-described invention.
[0020]
In order to achieve the above-mentioned object, a method of manufacturing a substrate for a multilayer wiring board according to the present invention comprises the steps of: providing a conductive layer forming a wiring pattern on one surface of an insulating substrate; A perforation step of perforating a through hole having a smaller diameter Db on the outer surface side of the conductive layer than a diameter Da of the conductive layer portion at the boundary with the base material, or the conductive layer at the boundary between the conductive layer and the insulating base material; The through hole having a smaller hole diameter Db on the outer surface side of the conductive layer than the hole diameter Da of the layer portion, and a hole diameter Da of the conductive layer portion at the boundary larger than the hole diameter Dc of the insulating base portion at the boundary. A hole diameter step Db on the outer surface side of the conductive layer is smaller than a hole diameter Da of the conductive layer portion at a boundary portion between the conductive layer and the insulating base material, and the conductive layer at the boundary portion. Layer The hole diameter Da is larger than the hole diameter Dc of the insulating base material portion at the boundary portion, and the hole diameter Da> the hole diameter Dc> the hole diameter Db. The hole diameter Db on the outer surface side of the conductive layer is smaller than the hole diameter Da of the conductive layer portion at the boundary portion with the insulating base material, and the hole diameter Dc of the insulating substrate portion at the boundary portion is smaller than the hole diameter Da at the boundary portion. The method includes a perforation step of perforating a through hole equal to or larger than the hole diameter Da of the conductive layer portion, and a filling step of filling the through hole with a conductive resin composition.
[0021]
Further, in order to achieve the above-mentioned object, a method for manufacturing a substrate for a multilayer wiring board according to the present invention includes the steps of: forming a conductive layer forming a wiring pattern on one surface of an insulating substrate; A step of piercing a through-hole having a smaller diameter Db on the outer surface side of the conductive layer than the diameter Da of the conductive layer portion at the boundary between the conductive layer and the insulating base material, or The hole diameter Db on the outer surface side of the conductive layer is smaller than the hole diameter Da of the conductive layer portion at the boundary between the conductive layer and the insulating base material, and the hole diameter Da of the conductive layer portion at the boundary is smaller than the boundary diameter. The hole diameter of the insulating substrate portion in step (a), or the outer surface of the conductive layer from the hole diameter Da of the conductive layer portion at the boundary between the conductive layer and the insulating substrate. Side hole diameter Db is small In addition, a hole diameter Da of the conductive layer portion at the boundary portion is larger than a hole diameter Dc of the insulating base portion portion at the boundary portion, and further, a through-hole in which the hole diameter Da> the hole diameter Dc> the hole diameter Db is pierced. A hole diameter Db on the outer surface side of the conductive layer is smaller than a hole diameter Da of the conductive layer portion at a boundary portion between the conductive layer and the insulating base material, and the insulating group at the boundary portion. A hole diameter Dc of the material portion is equal to or larger than a hole diameter Da of the conductive layer portion at the boundary portion; and a filling step of filling the through hole with a conductive resin composition is provided. .
[0022]
In the method for manufacturing a substrate for a multilayer wiring board according to the present invention, the perforating step includes a first perforating step of perforating an insulating substrate or an adhesive layer and the insulating substrate with a predetermined hole diameter, and perforating. A second perforating step of perforating the conductive layer by isotropic etching from the side of the insulating base material or the adhesive layer or the insulating base material, and the second perforating step is performed for forming a circuit. Can be performed in the same step as the etching of the conductive layer.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0024]
(Embodiment 1)
FIG. 1 shows a basic structure of a base material for a multilayer wiring board according to an embodiment of the present invention.
[0025]
The base material for a multilayer wiring board shown in FIG. 1 has a conductive layer 12 made of a copper foil or the like forming a wiring pattern on one surface of an insulating resin layer 11 forming an insulating base material, and an interlayer bonding film formed on the other surface. And a through hole 14 penetrating through the adhesive layer 13, the insulating resin layer 11, and the conductive layer 12. The through hole 14 is filled with the conductive resin composition 15 to form an IVH (via hole).
[0026]
The conductive resin composition 15 is a conductive paste obtained by mixing a metal powder having a conductive function into a resin binder and mixing it with a viscous medium containing a solvent to form a paste, and penetrates from the side of the adhesive layer 13 by squeezing or the like. The holes 14 are evenly filled.
[0027]
In the FPC, the insulating resin layer 11 is made of a flexible resin film such as a polyimide film made of wholly aromatic polyimide (API) or a polyester film, and is formed of the insulating resin layer 11, the conductive layer 12, and the adhesive layer 13. The three-layer structure is based on a general-purpose single-sided copper-foiled polyimide base material (copper-clad resin base material) as a starting base material, and is provided on the surface of the polyimide portion (insulating resin layer 11) opposite to the copper foil (conductive layer 12). The adhesive layer 13 may be formed by attaching a polyimide adhesive.
[0028]
The adhesive layer 13 made of a polyimide-based adhesive can be formed by attaching thermoplastic polyimide (TPI) or a film obtained by adding a thermosetting function to thermoplastic polyimide. In the case of thermoplastic polyimide, it is preferable to use one having a high glass transition point in consideration of the heat resistance of the substrate.
[0029]
The through hole 14 has a smaller hole diameter Db on the outer surface side of the conductive layer 12 than the hole diameter Da of the conductive layer 12 at the boundary between the conductive layer 12 and the insulating resin layer 11, that is, Da> Db. The hole diameter Da of the portion of the conductive layer 12 at the boundary between the conductive layer 12 and the insulating resin layer 11 is larger than the hole diameter Dc of the portion of the insulating resin layer 11 at the boundary, that is, Da> Dc. Further, the hole diameter Db on the outer surface side of the conductive layer 12 is smaller than the hole diameter Dc of the portion of the insulating resin layer 11 at the boundary, and Da>Dc> Db. The entire area of the through hole 14 is filled with the conductive resin composition 15.
[0030]
As a result, the inner wall surface 16 of the portion (hole) 14A (see FIG. 5E) of the through hole 14 that penetrates the conductive layer 12 is a curved or inclined surface when viewed in a longitudinal section, and the through hole 14 The layer portion 14A has a tapered shape in which the outer surface side of the conductive layer is tapered, in other words, a mortar shape.
[0031]
The perforation of the through hole 14 is performed by a laser processing or an anisotropic etching on the insulating resin layer 11 and the adhesive layer 13 as a first drilling step (the insulating resin layer 11 at the boundary between the conductive layer 12 and the insulating resin layer 11). A substantially straight hole 14B (see FIG. 5C) is formed by the hole diameter Dc of the portion, and after the completion of the first hole forming step, a second hole forming step is performed on the side of the holed adhesive layer / insulating resin layer (FIG. 1). From the upper side), that is, to the conductive layer 12 by etching having isotropic properties from the hole 14B, the outer surface side of the conductive layer 12 from the hole diameter Da of the conductive layer 12 at the boundary between the conductive layer 12 and the insulating resin layer 11. A hole 14A having a small hole diameter Db is formed.
[0032]
The shape of the inner wall surface of the through-hole 14 of the portion 14A penetrating the conductive layer 12 is determined by the speed ratio between the vertical traveling speed and the horizontal traveling speed in isotropic etching, and the whole is one curvature by selecting the etchant. Curved surface (spherical surface), a curved surface smoothly curved with a plurality of different curvatures, a spheroidal surface, a paraboloid of revolution, or a linear inclined surface.
[0033]
In the base material for a multilayer wiring board, since the hole diameter Db on the outer surface side of the conductive layer 12 is smaller than the hole diameter Da of the conductive layer 12 at the boundary between the conductive layer 12 and the insulating resin layer 11 in the through hole 14, the conductive layer The inner wall surface 16 of the through hole 14 in the 12 portion has a curved surface (near arc surface) or an inclined surface when viewed in a longitudinal section, and the through hole 14 in the conductive layer 12 portion has a tapered shape in which the outer surface side of the conductive layer is tapered. The area of the hole inner wall surface 16 is larger than that in the case of a straight through hole having the same diameter.
[0034]
As a result, conductive contact between the conductive resin composition 15 filled in the through hole 14 and the conductive layer 12 is performed with a required contact area with high reliability on the increased inner wall surface (side peripheral surface) 16 of the through hole. Thus, the present invention is free from various problems derived from securing a contact area between the conductive resin composition and a portion (head-like portion) above the conductive layer and the conductive layer.
[0035]
FIG. 2 shows one embodiment of a multilayer wiring board according to the present invention. In this multilayer wiring board, two sheets of the multilayer wiring board base material having the structure shown in FIG. 1 are superimposed as a first layer base material 10A and a second layer base material 10B. The first-layer base material 10A and the second-layer base material 10B are bonded and bonded to each other by the adhesive layer 13 of the material 10A. On the adhesive layer 13 of the second-layer substrate 10B, a conductive layer 17 made of copper foil forming a wiring pattern on the surface is formed.
[0036]
Each through-hole 14 filled with the conductive resin composition 15 forms an IVH, and is obtained from the hole diameter Da (see FIG. 1) of the conductive layer 12 at the boundary between the conductive layer 12 and the insulating resin layer 11 of each through-hole 14. The hole diameter Db (see FIG. 1) on the outer surface side of the conductive layer 12 is small, and the inner wall surface 16 of the through hole 14 in the conductive layer 12 has a curved surface (near arc surface) or an inclined surface when viewed in a longitudinal section. Since the through hole 14 of the portion is tapered such that the outer surface side of the conductive layer is tapered, the area of the inner wall surface 16 of the through hole is larger than that of a straight through hole having the same diameter, and the through hole 14 is filled. The conductive contact between the conductive resin composition 15 and the conductive layer 12 is established at the increased inner wall surface 16 of the through hole, and the portion (head) above the conductive layer of the conductive resin composition as in the conventional case is formed. ), The conductive resin composition 15 and Can ensure contact area between the conductive layer 12 without lowering the smoothness of the substrate, it is possible to obtain a thin multi-layer wiring board.
[0037]
As shown in FIG. 3, in the base material for a multilayer wiring board according to the present invention, the insulating resin layer 21 constituting the insulating base material is obtained by adding a thermosetting function to thermoplastic polyimide (TPI) or thermoplastic polyimide. For example, the insulating resin layer itself may have an adhesive property for interlayer adhesion. In this case, a conductive layer 22 made of copper foil or the like forming a wiring pattern is provided on one surface of the insulating resin layer 21, and the laminated adhesive layer on the other surface can be omitted.
[0038]
In the base material for a multilayer wiring board, a through hole 24 penetrating the insulating resin layer 21 and the conductive layer 22 is formed, and the through hole 24 is filled with the conductive resin composition 25 to form an IVH (via hole). It is formed.
[0039]
In the through hole 24, the hole diameter Db on the outer surface side of the conductive layer 22 is smaller than the hole diameter Da of the conductive layer 12 at the boundary between the conductive layer 22 and the insulating resin layer 21, that is, Da> Db. The hole diameter Da of the portion of the conductive layer 12 at the boundary between the conductive layer 22 and the insulating resin layer 21 is larger than the hole diameter Dc of the portion of the insulating resin layer 21 at the boundary, that is, Da> Dc. Further, the hole diameter Db on the outer surface side of the conductive layer 22 is even smaller than the hole diameter Dc of the portion of the insulating resin layer 21 at the boundary, and Da>Dc> Db. The entire area of the through hole 24 is filled with the conductive resin composition 15.
[0040]
As a result, the inner wall surface 26 of the portion of the through hole 24 that penetrates the conductive layer 22 is a curved surface or an inclined surface when viewed in a longitudinal section, and the through hole 24 is formed such that the outer surface of the conductive layer in the conductive layer 22 is tapered. It has a tapered shape, in other words, a mortar shape.
[0041]
Drilling of the through-hole 24 is performed by a laser processing or anisotropic etching on the insulating resin layer 21 as a first hole forming step (a hole diameter Dc of the insulating resin layer 21 at the boundary between the conductive layer 22 and the insulating resin layer 21). ), And after completion of the first drilling step, a second drilling step is performed from the side of the drilled insulating resin layer 21 (upper side in FIG. 3), that is, the insulating resin layer 21 is drilled. A hole having a smaller diameter Db on the outer surface side of the conductive layer 22 than the hole diameter Da of the portion of the conductive layer 12 at the boundary between the conductive layer 22 and the insulating resin layer 21 is formed in the conductive layer 22 by etching having isotropic properties. .
[0042]
Also in this case, the shape of the inner wall surface of the through hole 24 at the portion penetrating the conductive layer 22 is determined by the speed ratio between the vertical traveling speed and the horizontal traveling speed in isotropic etching and the like, and the entire liquid crystal etchant is selected. Can be any surface, such as a curved surface (spherical surface) with one curvature, a curved surface with smoothly continuous curved surfaces with a plurality of different curvatures, a spheroidal surface, a paraboloid of revolution, or a linear inclined surface.
[0043]
Also in this substrate for a multilayer wiring board, the hole diameter Db on the outer surface side of the conductive layer 22 is smaller than the hole diameter Da of the portion of the conductive layer 12 at the boundary between the conductive layer 22 and the insulating resin layer 21 of the through hole 24. The inner wall surface 26 of the through-hole 24 in the 12 portion has a curved surface (near arc surface) or an inclined surface when viewed in a longitudinal section, and the through-hole 24 in the conductive layer 22 portion has a tapered shape in which the outer surface side of the conductive layer is tapered. The area of the inner wall surface 26 is larger than that of a straight through hole having the same diameter.
[0044]
Thereby, the conductive contact between the conductive resin composition 25 filled in the through hole 24 and the conductive layer 22 can be performed with a required contact area with high reliability on the increased inner wall surface (side peripheral surface) 26 of the through hole. Thus, the present invention is free from various problems derived from securing a contact area between the conductive resin composition and a portion (head-shaped portion) above the conductive layer and the conductive layer.
[0045]
FIG. 4 shows another embodiment of the multilayer wiring board according to the present invention. In this multilayer wiring board, two sheets of the multilayer wiring board base material having the structure shown in FIG. 3 are superimposed on each other as a first layer base material 20A and a second layer base material 20B. The base material 20A of the first layer and the base material 20B of the second layer are bonded to each other by the insulating resin layer 21 having the adhesive property of the material 20A. On the insulating resin layer 21 of the second-layer base material 20B, a conductive layer 27 made of copper foil forming a wiring pattern on the surface is formed.
[0046]
Also in this multilayer wiring board, each through hole 24 filled with the conductive resin composition 25 forms an IVH, and the hole diameter Da of the conductive layer 22 at the boundary between the conductive layer 22 and the insulating resin layer 21 of each through hole 24. The hole diameter Db (see FIG. 3) on the outer surface side of the conductive layer 22 is smaller than that of the conductive layer 22 (see FIG. 3). In the surface, the through hole 24 of the conductive layer 22 is tapered such that the outer surface side of the conductive layer is tapered, so that the area of the inner wall surface 26 of the through hole is larger than that of a straight through hole having the same diameter. The conductive contact between the conductive resin composition 25 filled in the through hole 24 and the conductive layer 22 is made at the increased inner wall surface 26 of the through hole, and the conductive layer of the conductive resin composition is formed as in the prior art. Even without the upper part (head-shaped part), Can ensure contact area with the conductive resin composition 25 and conductive layer 22 without lowering the smoothness of the substrate, it is possible to obtain a thin multi-layer wiring board.
[0047]
Next, an embodiment of a method for manufacturing the base material for a multilayer wiring board shown in FIG. 1 and a method for manufacturing a multilayer wiring board using the base material for a multilayer wiring board will be described in detail with reference to FIGS. Will be described.
[0048]
First, as shown in FIGS. 5A and 5B, on the insulating resin layer 11 side of a base material provided with a conductive layer 12 made of copper foil on one surface of an insulating resin layer (polyimide film) 11, The adhesive layer 13 is formed by attaching a thermoplastic polyimide or a film having a thermosetting function to the thermoplastic polyimide, and a masking tape 18 made of PET is attached to the adhesive layer 13 side.
[0049]
Next, as a first drilling step, as shown in FIG. 5C, laser light irradiation is performed from the masking tape 18 side, and the portion excluding the conductive layer 12 through the masking tape 18, that is, In the adhesive layer 13 and the insulating resin layer 11, a substantially straight hole 14B for the IVH in which the hole diameter of the insulating resin layer 11 at the boundary between the conductive layer 12 and the insulating resin layer 11 is Dc is formed.
[0050]
Next, as shown in FIG. 5D, an etching resist 19 for forming a circuit is formed on the surface of the conductive layer 12, and as shown in FIG. Is used as a mask to etch the etchant from the conductive layer 12 side to etch the conductive layer 12 for forming a circuit. At the same time, as a second drilling step, the adhesive layer 13 and the hole 14B formed in the insulating resin layer 11 are removed. The etchant is also eroded from the side, and isotropic etching is performed on the conductive layer 12 to form a through hole, and a hole 14A for IVH is formed in the conductive layer 12.
[0051]
When the conductive layer 12 is a copper foil, the isotropic etching performed on the conductive layer 12 can be performed using an aqueous solution mainly containing ferric chloride or an etchant mainly containing cupric chloride.
[0052]
In the case of isotropic etching, the inner wall surface 16 of the through-hole 14 (hole 14A) in the conductive layer 12 is formed by a side etching so as to have a curved surface (near arc) as viewed in a longitudinal section, as shown in FIG. Surface) or an inclined surface, and the through hole 14 in the conductive layer 12 has a tapered shape including an undercut and the outer surface side of the conductive layer is tapered.
[0053]
When the etching is completed, as shown in FIG. 5F, the etching resist 19 is removed, and the through hole 14 for IVH is completed. In this case, the through hole 14 has a smaller hole diameter Db on the outer surface side of the conductive layer 12 than the hole diameter Da of the conductive layer 12 at the boundary between the conductive layer 12 and the insulating resin layer 11. The hole diameter Da of the conductive layer 12 at the boundary between the insulating resin layer 11 and the insulating resin layer 11 is larger than the hole diameter Dc of the insulating resin layer 11 at the boundary.
[0054]
When the perforation of the through hole 14 is completed, as shown in FIG. 5 (g), the conductive resin composition (conductive paste) is applied from the masking tape 18 side using a squeegee plate 51 used for screen printing. ) 15 is filled in the through holes 14 by squeezing (printing method). FIG. 5H shows a state where the filling of the conductive resin composition 15 is completed.
[0055]
The conductive resin composition 15 used a silver paste in order to avoid oxidation due to heating in a later step. At this time, when a material having a viscosity of 300 dPa · s was used, the conductive paste could be filled accurately without dropping out of the conductive paste from the holes 14A of the copper foil portion (conductive layer 12). In addition, as the conductive resin composition 15, in addition to the silver paste, a conductive paste made of a copper filler or a carbon mixture may be used.
[0056]
Since the masking tape 18 made of PET is adhered to the base material, the squeegee plate 51 can be directly contacted with the base material without using a metal mask or a screen mask to fill the hole. Can be filled through the process, and waste of the conductive resin composition 15 can be reduced.
[0057]
The through-hole 14 has a smaller hole diameter Db on the outer surface side of the conductive layer 12 than the hole diameter Da of the conductive layer 12 at the boundary between the conductive layer 12 and the insulating resin layer 11. Since the shape of the portion is a near arc shape, the adhesion between the copper foil portion (conductive layer 12) and the conductive resin composition 15 is sufficiently ensured by the inner wall surface (side peripheral surface) 16 of the through hole 14 in the conductive layer 12 portion. Done.
[0058]
The diameter of the through-holes 14 in the conductive layer 12 portion is determined by the properties of the conductive resin composition 15 such as viscosity and thixotropy, in addition to the requirement from the contact resistance with the conductive resin composition 15. The selection is made so that the conductive resin composition 15 can be prevented from falling off, and is about 30 to 50 μm.
[0059]
When the filling of the conductive resin composition 15 is completed, as shown in FIG. 5 (i), the masking tape 18 is removed to complete one base material 10A.
[0060]
This base material 10A is used as a first-layer base material, and a base material 10B manufactured by the same manufacturing method as shown in FIGS. 5A to 5I and a conductive layer 17 made of copper foil are appropriately used. As shown in FIGS. 6 (a) and 6 (b), multi-layering is achieved by performing lamination thermocompression bonding (lamination) while performing positioning by a simple positioning method.
[0061]
At the time of lamination, the adhesion of the adhesive layer 13 to the unevenness of the circuit pattern by the conductive layer 12 can be improved by subjecting the substrate to thermal compression while exposing it to a vacuum. In addition, lamination is performed in a state where the conductive resin composition 15 is soft, so that the conductive resin composition 15 can be in close contact with the copper foil of another layer.
[0062]
Finally, as shown in FIG. 6 (c), a circuit is formed by etching the outermost conductive layer 17, thereby completing the multilayer wiring board.
[0063]
In addition, the base material for a multilayer wiring board shown in FIG. 3 and the multilayer wiring board using the base material for a multilayer wiring board can also be manufactured by the same manufacturing method as the above-described manufacturing method.
[0064]
(Embodiment 2)
7A and 7B show a basic structure of a base material for a multilayer wiring board according to another embodiment of the present invention. In FIGS. 7A and 7B, parts corresponding to those in FIG. 1 are denoted by the same reference numerals as those in FIG. 1, and description thereof is omitted.
[0065]
The base material for a multilayer wiring board shown in FIGS. 7A and 7B is similar to the base material shown in FIG. 1 in that a wiring is provided on one surface of an insulating resin layer 11 forming an insulating base material. A conductive layer 12 made of copper foil or the like forming a pattern and an adhesive layer 13 for interlayer bonding are provided on the other surface, and a through hole 14 penetrating the adhesive layer 13, the insulating resin layer 11, and the conductive layer 12 is formed. Is established. The through hole 14 is filled with the conductive resin composition 15 to form an IVH (via hole).
[0066]
Also in this embodiment, in the FPC, the insulating resin layer 11 can be formed of a flexible resin film such as a polyimide film made of wholly aromatic polyimide (API) or a polyester film. The three-layer structure of the adhesive layer 13 and the general-purpose one-sided copper foil-containing polyimide base material (copper-clad resin base material) is used as a starting base material, with the copper foil (conductive layer 12) of the polyimide part (insulating resin layer 11). Can be constituted by attaching a polyimide-based adhesive as an adhesive layer 13 to the opposite surface.
[0067]
Further, the conductive resin composition 15 may be a conductive paste obtained by mixing a metal powder having a conductive function into a resin binder into a viscous medium containing a solvent to form a paste, and from the side of the adhesive layer 13. The through holes 14 are evenly filled and filled by squeezing or the like.
[0068]
Here, in the embodiment shown in FIG. 7A, the through-hole 14 has a hole diameter Db closer to the outer surface of the conductive layer 12 than the hole diameter Da of the conductive layer 12 at the boundary between the conductive layer 12 and the insulating resin layer 11. Is smaller, that is, Da> Db, and the hole diameter Dc of the insulating resin layer 11 at the boundary between the conductive layer 12 and the insulating resin layer 11 is equal to the hole diameter Da of the conductive layer 12 at the boundary, or The conductive resin composition 15 is formed slightly larger than this, that is, Dc ≧ Da, and the entire area of the hole is filled with the conductive resin composition 15.
[0069]
As a result, the inner wall surface 16 of the portion (hole) 14A (see FIG. 5E) of the through hole 14 that penetrates the conductive layer 12 is a curved or inclined surface when viewed in a longitudinal section, and the through hole 14 The layer portion 14A has a tapered shape in which the outer surface side of the conductive layer is tapered, in other words, a mortar shape.
[0070]
As a first drilling step, a substantially straight hole 14B (see FIG. 11 (c)) having a predetermined hole diameter is formed in the insulating resin layer 11 and the adhesive layer 13 by laser processing or anisotropic etching. After the completion of one hole forming step, as a second hole forming step, the conductive layer 12 is electrically connected to the conductive layer 12 from the side of the holed adhesive layer / insulating resin layer (upper side in FIG. 7), that is, by etching having isotropic properties from the hole 14B. A hole 14A having a smaller hole diameter Db on the outer surface side of the conductive layer 12 than the hole diameter Da of the conductive layer 12 at the boundary between the layer 12 and the insulating resin layer 11 is formed. And the hole diameter Dc of the insulating resin layer 11 at the boundary between the conductive layer 12 and the insulating resin layer 11 is the hole diameter Dc of the conductive layer 12 at the boundary between the conductive layer 12 and the insulating resin layer 11. Equal to, expanding it to little more than a large hole 14C (see FIG. 11 (g)) to.
[0071]
Also in this case, the shape of the inner wall surface of the through hole 14 of the portion 14A penetrating the conductive layer 12 is determined by the speed ratio between the vertical traveling speed and the horizontal traveling speed in isotropic etching, and the like. Can be an arbitrary surface such as a curved surface (spherical surface) having one curvature, a curved surface having smoothly continuous curved surfaces having a plurality of different curvatures, a spheroidal surface, a paraboloid of revolution, or a linear inclined surface.
[0072]
In the base material for a multilayer wiring board, since the hole diameter Db on the outer surface side of the conductive layer 12 is smaller than the hole diameter Da of the conductive layer 12 at the boundary between the conductive layer 12 and the insulating resin layer 11 in the through hole 14, the conductive layer The inner wall surface 16 of the through hole 14 in the 12 portion has a curved surface (near arc surface) or an inclined surface when viewed in a longitudinal section, and the through hole 14 in the conductive layer 12 portion has a tapered shape in which the outer surface side of the conductive layer is tapered. The area of the hole inner wall surface 16 is larger than that in the case of a straight through hole having the same diameter.
[0073]
As a result, conductive contact between the conductive resin composition 15 filled in the through hole 14 and the conductive layer 12 is performed with a required contact area with high reliability on the increased inner wall surface (side peripheral surface) 16 of the through hole. Thus, the present invention is free from various problems derived from securing a contact area between the conductive resin composition and a portion (head-like portion) above the conductive layer and the conductive layer.
[0074]
Moreover, the hole diameter Dc of the portion of the insulating resin layer 11 at the boundary between the conductive layer 12 and the insulating resin layer 11 of the through hole 14 is equal to or slightly larger than the hole diameter Da of the portion of the conductive layer 12 at this boundary. As a result, when the conductive resin composition 15 is filled into the through hole 14 from the side of the adhesive layer 13, there is no undercut region that becomes a stagnation region with respect to the filling flow, and bubbles remain in the through hole 14. Therefore, the conductive contact between the conductive resin composition 15 and the conductive layer 12 on the inner wall surface 16 of the through hole 14 in the conductive layer 12 can be reliably performed with a required area.
[0075]
FIG. 7B is a modification of the embodiment shown in FIG. Here, in the modified example shown in FIG. 7B, the through hole 14 has a hole diameter Db closer to the outer surface of the conductive layer 12 than the hole diameter Da of the conductive layer 12 at the boundary between the conductive layer 12 and the insulating resin layer 11. Is smaller, that is, Da> Db, and the hole diameter Dc of the insulating resin layer 11 at the boundary between the conductive layer 12 and the insulating resin layer 11 is larger than the hole diameter Da of the conductive layer 12 at the boundary. , Dc> Da, and the entire area inside the hole is filled with the conductive resin composition 15.
[0076]
That is, according to the modification shown in FIG. 7B, in addition to the effect of the embodiment shown in FIG. 7A, the contact area between the conductive resin composition 15 and the conductive layer 12 is reduced as shown in FIG. Since only the portion indicated by E in b) is enlarged, there is an effect that the connectivity is further improved.
[0077]
FIG. 8 shows another embodiment of the multilayer wiring board according to the present invention. In this multilayer wiring board, two sheets of the multilayer wiring board base material having the structure shown in FIG. 7 are overlapped with each other as a first layer base material 10A and a second layer base material 10B. The first-layer base material 10A and the second-layer base material 10B are bonded and bonded to each other by the adhesive layer 13 of the material 10A. On the adhesive layer 13 of the second-layer substrate 10B, a conductive layer 17 made of copper foil forming a wiring pattern on the surface is formed.
[0078]
Each through-hole 14 filled with the conductive resin composition 15 forms an IVH, and is determined from the hole diameter Da (see FIG. 7) of the conductive layer 12 at the boundary between the conductive layer 12 and the insulating resin layer 11 in each through-hole 14. The hole diameter Db (see FIG. 7) on the outer surface side of the conductive layer 12 is small, and the inner wall surface 16 of the through hole 14 in the conductive layer 12 has a curved surface (near arc surface) or an inclined surface when viewed in a longitudinal section. Since the through hole 14 of the portion is tapered such that the outer surface side of the conductive layer is tapered, the area of the inner wall surface 16 of the through hole is larger than that of a straight through hole having the same diameter, and the through hole 14 is filled. The conductive contact between the conductive resin composition 15 and the conductive layer 12 is established at the increased inner wall surface 16 of the through hole, and the portion (head) above the conductive layer of the conductive resin composition as in the conventional case is formed. ), The conductive resin composition 15 and Can ensure contact area between the conductive layer 12 without lowering the smoothness of the substrate, it is possible to obtain a thin multi-layer wiring board.
[0079]
Moreover, the hole diameter Dc of the portion of the insulating resin layer 11 at the boundary between the conductive layer 12 and the insulating resin layer 11 of the through hole 14 (see FIG. 7) is equal to the hole diameter Da of the portion of the conductive layer 12 at this boundary, or By being slightly larger,
When the conductive resin composition 15 is filled into the through hole 14 from the side of the adhesive layer 13, there is no undercut region that becomes a stagnation region with respect to the filling flow, and bubbles remain in the through hole 14. Therefore, conductive contact between the conductive resin composition 15 and the conductive layer 12 on the inner wall surface 16 of the through hole 14 in the conductive layer 12 can be reliably performed with a required area.
[0080]
Also in this embodiment, as shown in FIG. 9, the base material for a multilayer wiring board is obtained by converting the insulating resin layer 21 forming the insulating base material into thermoplastic polyimide (TPI) or thermoplastic polyimide. The insulating resin layer itself may have an adhesive property for interlayer adhesion, such as one having a function. In this case, a conductive layer 22 made of copper foil or the like forming a wiring pattern is provided on one surface of the insulating resin layer 21, and the laminated adhesive layer on the other surface can be omitted.
[0081]
In the base material for a multilayer wiring board, a through hole 24 penetrating the insulating resin layer 21 and the conductive layer 22 is formed, and the through hole 24 is filled with the conductive resin composition 25 to form an IVH (via hole). It is formed.
[0082]
In the through hole 24, the hole diameter Db on the outer surface side of the conductive layer 22 is smaller than the hole diameter Da of the portion of the conductive layer 12 at the boundary between the conductive layer 22 and the insulating resin layer 21, that is, Da> Db. The hole diameter Dc of the insulating resin layer 21 at the boundary between the insulating resin layer 21 and the insulating resin layer 21 is equal to or slightly larger than the hole diameter Da of the conductive layer 12 at the boundary, that is, Dc ≧ Da. The whole area inside the hole is filled with the conductive resin composition 15.
[0083]
As a result, the inner wall surface 26 of the portion of the through hole 24 that penetrates the conductive layer 22 is a curved surface or an inclined surface when viewed in a longitudinal section, and the through hole 24 is formed such that the outer surface of the conductive layer in the conductive layer 22 is tapered. It has a tapered shape, in other words, a mortar shape.
[0084]
The perforation of the through hole 24 is performed by forming a substantially straight hole with a predetermined hole diameter in the insulating resin layer 21 by laser processing or anisotropic etching as a first hole making step, and after the completion of the first hole making step, making a second hole making step. From the side of the insulating resin layer 21 (the upper side in FIG. 9), that is, the conductive layer 22 and the insulating resin layer 21 are formed on the conductive layer 22 by etching having isotropic properties from the holes formed in the insulating resin layer 21. Then, a hole having a smaller hole diameter Db on the outer surface side of the conductive layer 22 than the hole diameter Da of the conductive layer 22 at the boundary portion is formed. Then, as a third hole forming step, the hole 24B of the insulating resin layer 21 is The hole diameter Dc of the insulating resin layer 21 at the boundary between the conductive layer 22 and the insulating resin layer 21 is equal to or slightly larger than the hole diameter Da of the conductive layer 12 at this boundary. To.
[0085]
Also in this case, the shape of the inner wall surface of the through hole 24 at the portion penetrating the conductive layer 22 is determined by the speed ratio between the vertical traveling speed and the horizontal traveling speed in isotropic etching and the like, and the entire liquid crystal etchant is selected. Can be any surface, such as a curved surface (spherical surface) with one curvature, a curved surface with smoothly continuous curved surfaces with a plurality of different curvatures, a spheroidal surface, a paraboloid of revolution, or a linear inclined surface.
[0086]
Also in this multilayer wiring board base material, since the hole diameter Db on the outer surface side of the conductive layer 22 is smaller than the hole diameter Da of the conductive layer 22 at the boundary between the conductive layer 22 and the insulating resin layer 21 of the through hole 24, the conductive layer The inner wall surface 26 of the through hole 24 in the portion 22 has a curved surface (near arc surface) or an inclined surface when viewed in a longitudinal section, and the through hole 24 in the conductive layer 22 portion has a tapered shape in which the outer surface side of the conductive layer is tapered. The area of the inner wall surface 26 is larger than that of a straight through hole having the same diameter.
[0087]
Thereby, the conductive contact between the conductive resin composition 25 filled in the through hole 24 and the conductive layer 22 can be performed with a required contact area with high reliability on the increased inner wall surface (side peripheral surface) 26 of the through hole. Thus, the present invention is free from various problems derived from securing a contact area between the conductive resin composition and a portion (head-shaped portion) above the conductive layer and the conductive layer.
[0088]
Moreover, the hole diameter Dc of the portion of the insulating resin layer 21 at the boundary between the conductive layer 22 and the insulating resin layer 21 of the through hole 24 is equal to or slightly larger than the hole diameter Da of the portion of the conductive layer 12 at this boundary. In filling the conductive resin composition 25 into the through hole 24 from the side of the insulating resin layer 21, there is no undercut region which becomes a stagnation region with respect to the filling flow, and bubbles remain in the through hole 24. Therefore, the conductive contact between the conductive resin composition 25 and the conductive layer 22 on the inner wall surface 26 of the through hole 24 in the conductive layer 22 can be reliably performed with a required area.
[0089]
FIG. 10 shows another embodiment of the multilayer wiring board according to the present invention. In this multilayer wiring board, two sheets of the multilayer wiring board base material having the structure shown in FIG. 9 are superimposed on each other as a first layer base material 20A and a second layer base material 20B. The base material 20A of the first layer and the base material 20B of the second layer are bonded to each other by the insulating resin layer 21 having the adhesive property of the material 20A. On the insulating resin layer 21 of the second-layer base material 20B, a conductive layer 27 made of copper foil forming a wiring pattern on the surface is formed.
[0090]
Also in this multilayer wiring board, each through hole 24 filled with the conductive resin composition 25 forms an IVH, and the hole diameter Da of the conductive layer 22 at the boundary between the conductive layer 22 and the insulating resin layer 21 of each through hole 24. The hole diameter Db (see FIG. 9) on the outer surface side of the conductive layer 22 is smaller than that of the conductive layer 22 (see FIG. 9). In the surface, the through hole 24 of the conductive layer 22 is tapered such that the outer surface side of the conductive layer is tapered, so that the area of the inner wall surface 26 of the through hole is larger than that of a straight through hole having the same diameter. The conductive contact between the conductive resin composition 25 filled in the through hole 24 and the conductive layer 22 is made at the increased inner wall surface 26 of the through hole, and the conductive layer of the conductive resin composition is formed as in the prior art. Even without the upper part (head-shaped part), Can ensure contact area with the conductive resin composition 25 and conductive layer 22 without lowering the smoothness of the substrate, it is possible to obtain a thin multi-layer wiring board.
[0091]
Moreover, the hole diameter Dc of the portion of the insulating resin layer 21 at the boundary between the conductive layer 22 and the insulating resin layer 21 of the through hole 24 (see FIG. 9) is equal to or smaller than the hole diameter Da of the portion of the conductive layer 22 at this boundary. When the conductive resin composition 25 is filled into the through hole 24 from the side of the insulating resin layer 21, there is no undercut region which becomes a stagnation region with respect to the filling flow, and the through hole 24 No bubbles remain inside the conductive layer 22, and the conductive contact between the conductive resin composition 25 and the conductive layer 22 on the inner wall surface 26 of the through hole 24 in the conductive layer 22 portion is reliably performed with a required area.
[0092]
Next, an embodiment of a method for manufacturing a base material for a multilayer wiring board shown in FIG. 7 and a method for manufacturing a multilayer wiring board using the base material for a multilayer wiring board will be described in detail with reference to FIGS. Will be described.
[0093]
First, as shown in FIGS. 11A and 11B, on the insulating resin layer 11 side of a base material provided with a conductive layer 12 made of copper foil on one surface of an insulating resin layer (polyimide film) 11, The adhesive layer 13 is formed by attaching a thermoplastic polyimide or a film having a thermosetting function to the thermoplastic polyimide, and a masking tape 18 made of PET is attached to the adhesive layer 13 side.
[0094]
Next, as a first drilling step, as shown in FIG. 11C, laser light irradiation is performed from the side of the masking tape 18 to penetrate the masking tape 18 and remove the conductive layer 12, that is, a portion. A substantially straight hole 14B for IVH having a predetermined hole diameter is formed in the adhesive layer 13 and the insulating resin layer 11.
[0095]
Next, as shown in FIG. 11D, an etching resist 19 for forming a circuit is formed on the surface of the conductive layer 12, and as shown in FIG. Is used as a mask to etch the etchant from the conductive layer 12 side to etch the conductive layer 12 for forming a circuit. At the same time, as a second drilling step, the adhesive layer 13 and the hole 14B formed in the insulating resin layer 11 are removed. The etchant is also eroded from the side, and isotropic etching for forming a through hole is performed on the conductive layer 12, and a hole 14 </ b> A for IVH is formed in the conductive layer 12.
[0096]
When the conductive layer 12 is a copper foil, the isotropic etching performed on the conductive layer 12 can be performed using an aqueous solution mainly containing ferric chloride or an etchant mainly containing cupric chloride.
[0097]
In the case of isotropic etching, the inner wall surface 16 of the through-hole 14 (hole 14A) in the conductive layer 12 by side etching has a curved surface (near arc) as viewed in a longitudinal section, as shown in FIG. Surface) or an inclined surface, and the through hole 14 in the conductive layer 12 has a tapered shape including an undercut and the outer surface side of the conductive layer is tapered.
[0098]
When the etching is completed, the etching resist 19 is removed as shown in FIG. 11F, and thereafter, as shown in FIG. 13, the hole diameter of the hole 14B formed in the insulating resin layer 11 is enlarged by laser processing to a hole diameter Dc substantially equal to the hole diameter Da of the conductive layer 12 at the boundary between the conductive layer 12 and the insulating resin layer 11, The through hole 14 for IVH is completed. In this case, the through-hole 14 has a smaller hole diameter Db on the outer surface side of the conductive layer 12 than the hole diameter Da of the conductive layer 12 at the boundary between the conductive layer 12 and the insulating resin layer 11. The hole diameter Dc of the insulating resin layer 11 at the boundary with the layer 11 is substantially equal to the hole diameter Da of the conductive layer 12 at the boundary.
[0099]
When the perforation of the through hole 14 is completed, as shown in FIG. 11H, the conductive resin composition (conductive paste) is applied from the masking tape 18 side using a squeegee plate 51 used for screen printing. ) 15 is filled in the through holes 14 by squeezing (printing method). FIG. 11 (i) shows a state where the filling of the conductive resin composition 15 is completed.
[0100]
The through-hole 14 has a smaller hole diameter Db on the outer surface side of the conductive layer 12 than the hole diameter Da of the conductive layer 12 at the boundary between the conductive layer 12 and the insulating resin layer 11. Since the shape of the portion is a near arc shape, the adhesion between the copper foil portion (conductive layer 12) and the conductive resin composition 15 is sufficiently ensured by the inner wall surface (side peripheral surface) 16 of the through hole 14 in the conductive layer 12 portion. Done. Moreover, since the hole diameter Dc of the insulating resin layer 11 at the boundary between the conductive layer 12 and the insulating resin layer 11 of the through hole 14 is substantially equal to the hole diameter Da of the conductive layer 12 at the boundary, the bonding layer 13 When the conductive resin composition 15 is filled into the through hole 14 from the side, there is no undercut region that becomes a stagnation region with respect to the filling flow, and no harmful bubbles remain in the through hole 14. .
[0101]
When the filling of the conductive resin composition 15 is completed, as shown in FIG. 11 (j), the masking tape 18 is removed to complete one base material 10A.
[0102]
The base material 10A was used as a first layer base material, and a base material 10B manufactured by the same manufacturing method as shown in FIGS. 11A to 11J and a conductive layer 17 made of copper foil were appropriately used. By performing lamination thermocompression bonding (lamination) while performing alignment by a simple alignment method, multilayering is achieved as shown in FIGS. 12 (a) and 12 (b).
[0103]
At the time of lamination, the adhesion of the adhesive layer 13 to the unevenness of the circuit pattern by the conductive layer 12 can be improved by subjecting the substrate to thermal compression while exposing it to a vacuum. In addition, lamination is performed in a state where the conductive resin composition 15 is soft, so that the conductive resin composition 15 can be in close contact with the copper foil of another layer.
[0104]
Finally, as shown in FIG. 12 (c), the outermost conductive layer 17 is formed into a circuit by etching to see the completion as a multilayer wiring board.
[0105]
It should be noted that the multilayer wiring board base material shown in FIG. 9 and the multilayer wiring board using the multilayer wiring board base material can also be manufactured by the same manufacturing method as the above-described manufacturing method.
[0106]
(Other embodiments)
In each of the above embodiments, a flexible printed wiring board has been described, but the present invention is not limited to this, and the same applies to a rigid type printed wiring board made of an epoxy resin or a prepreg. Applicable to
[0107]
【The invention's effect】
As can be understood from the above description, according to the multilayer wiring board, the multilayer wiring board base material and the method of manufacturing the same according to the present invention, the diameter of the through-holes is reduced by the conductive layer at the boundary between the conductive layer and the insulating base material. The hole diameter Db on the outer surface side of the conductive layer is smaller than the hole diameter Da of the portion, the inner wall surface of the through hole in the conductive layer portion is a curved surface (near arc surface) or an inclined surface when viewed in a longitudinal section, and the outer surface side of the conductive layer is tapered. Since it becomes a tapered through hole, the area of the inner wall surface of the through hole becomes larger than in the case of a straight through hole with the same diameter, and the conductive resin composition and the conductive layer filled in the through hole Conductive contact is reliably taken on the increased inner wall surface (side peripheral surface) of the through hole, and is derived from securing a contact area between the conductive layer of the conductive resin composition above the conductive layer (head-shaped portion) and the conductive layer. Free from various problems, the conductive resin composition and the conductive layer It becomes to be performed stably with a conduction reliable.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a basic configuration of a base material for a multilayer wiring board according to Embodiment 1 of the present invention.
FIG. 2 is a sectional view showing a multilayer wiring board according to Embodiment 1 of the present invention.
FIG. 3 is a cross-sectional view showing another basic configuration of the base material for a multilayer wiring board according to Embodiment 1 of the present invention.
FIG. 4 is a sectional view showing a multilayer wiring board according to Embodiment 1 of the present invention;
FIGS. 5A to 5I are process diagrams showing one embodiment of a method for manufacturing a substrate for a multilayer wiring board according to Embodiment 1 of the present invention.
FIGS. 6A to 6C are process diagrams showing one embodiment of a method for manufacturing a multilayer wiring board according to the first embodiment of the present invention.
FIG. 7A is a cross-sectional view showing a basic structure of a base material for a multilayer wiring board according to Embodiment 2 of the present invention, and FIG. 7B is a modified example thereof.
FIG. 8 is a sectional view showing a multilayer wiring board according to Embodiment 2 of the present invention;
FIG. 9 is a cross-sectional view showing another basic configuration of the base material for a multilayer wiring board according to Embodiment 2 of the present invention.
FIG. 10 is a sectional view showing a multilayer wiring board according to Embodiment 2 of the present invention.
FIGS. 11A to 11J are process diagrams showing one embodiment of a method for manufacturing a substrate for a multilayer wiring board according to Embodiment 2 of the present invention.
12 (a) to 12 (c) are process diagrams showing one embodiment of a method for manufacturing a multilayer wiring board according to Embodiment 2 of the present invention.
FIG. 13 is a cross-sectional view showing an IVH structure of a conventional base material for a multilayer wiring board.
FIG. 14 is a cross-sectional view showing a defect in an IVH structure of a conventional base material for a multilayer wiring board.
[Explanation of symbols]
10A First layer base material
10B 2nd layer base material
11 Insulating resin layer
12 conductive layer
13 Adhesive layer
14 Through hole
15 conductive resin composition
16 Inner wall
17 Conductive layer
20A First layer substrate
20B 2nd layer base material
21 Insulating resin layer
22 conductive layer
24 Through hole
25 conductive resin composition
26 Inner wall
27 Conductive layer

Claims (23)

絶縁性基材の片面に配線パターンをなす導電層を設けられ、前記絶縁性基材と前記導電層を貫通する貫通孔に層間導通を得るための導電性樹脂組成物を充填された多層配線基板用基材であって、
前記貫通孔の前記導電層と前記絶縁性基材との境界部における前記導電層部分の孔径Ｄａより前記導電層の外表面側の孔径Ｄｂが小さいことを特徴とする多層配線基板用基材。A multilayer wiring board provided with a conductive layer forming a wiring pattern on one surface of an insulating base material and filled with a conductive resin composition for obtaining interlayer conduction in a through hole penetrating the insulating base material and the conductive layer A base material for
A substrate for a multilayer wiring board, wherein a hole diameter Db on an outer surface side of the conductive layer is smaller than a hole diameter Da of a portion of the conductive layer at a boundary portion between the conductive layer and the insulating base in the through hole. 絶縁性基材の片面に配線パターンをなす導電層を設けられ、前記絶縁性基材と前記導電層を貫通する貫通孔に層間導通を得るための導電性樹脂組成物を充填された多層配線基板用基材であって、
前記貫通孔の前記導電層と前記絶縁性基材との境界部における前記導電層部分の孔径Ｄａより前記導電層の外表面側の孔径Ｄｂが小さく、
且つ、前記境界部における前記導電層部分の孔径Ｄａが前記境界部における前記絶縁性基材部分の孔径Ｄｃより大きいことを特徴とする多層配線基板用基材。A multilayer wiring board provided with a conductive layer forming a wiring pattern on one surface of an insulating base material and filled with a conductive resin composition for obtaining interlayer conduction in a through hole penetrating the insulating base material and the conductive layer A base material for
The hole diameter Db on the outer surface side of the conductive layer is smaller than the hole diameter Da of the conductive layer portion at the boundary between the conductive layer and the insulating base material of the through hole,
And a hole diameter Da of the conductive layer portion at the boundary portion is larger than a hole diameter Dc of the insulating base portion portion at the boundary portion. 絶縁性基材の片面に配線パターンをなす導電層を設けられ、前記絶縁性基材と前記導電層を貫通する貫通孔に層間導通を得るための導電性樹脂組成物を充填された多層配線基板用基材であって、
前記貫通孔の前記導電層と前記絶縁性基材との境界部における前記導電層部分の孔径Ｄａより前記導電層の外表面側の孔径Ｄｂが小さく、
且つ、前記境界部における前記導電層部分の孔径Ｄａが前記境界部における前記絶縁性基材部分の孔径Ｄｃより大きく、しかも、前記孔径Ｄａ＞前記孔径Ｄｃ＞前記孔径Ｄｂであることを特徴とする多層配線基板用基材。A multilayer wiring board provided with a conductive layer forming a wiring pattern on one surface of an insulating base material and filled with a conductive resin composition for obtaining interlayer conduction in a through hole penetrating the insulating base material and the conductive layer A base material for
The hole diameter Db on the outer surface side of the conductive layer is smaller than the hole diameter Da of the conductive layer portion at the boundary between the conductive layer and the insulating base material of the through hole,
Further, the hole diameter Da of the conductive layer portion at the boundary portion is larger than the hole diameter Dc of the insulating base portion portion at the boundary portion, and the hole diameter Da> the hole diameter Dc> the hole diameter Db. Substrate for multilayer wiring board. 絶縁性基材の片面に配線パターンをなす導電層を設けられ、前記絶縁性基材と前記導電層を貫通する貫通孔に層間導通を得るための導電性樹脂組成物を充填された多層配線基板用基材であって、
前記貫通孔の前記導電層と前記絶縁性基材との境界部における前記導電層部分の孔径Ｄａより前記導電層の外表面側の孔径Ｄｂが小さく、
且つ、前記境界部における前記絶縁性基材部分の孔径Ｄｃが前記境界部における前記導電層部分の孔径Ｄａに等しいかあるいはそれより大きいことを特徴とする多層配線基板用基材。A multilayer wiring board provided with a conductive layer forming a wiring pattern on one surface of an insulating base material and filled with a conductive resin composition for obtaining interlayer conduction in a through hole penetrating the insulating base material and the conductive layer A base material for
The hole diameter Db on the outer surface side of the conductive layer is smaller than the hole diameter Da of the conductive layer portion at the boundary between the conductive layer and the insulating base material of the through hole,
And a hole diameter Dc of the insulating substrate portion at the boundary portion is equal to or larger than a hole diameter Da of the conductive layer portion at the boundary portion. 絶縁性基材の一方の面に配線パターンをなす導電層を、他方の面に層間接着のための接着層を設けられ、前記導電層と前記絶縁性基材と前記接着層を貫通する貫通孔に層間導通を得るための導電性樹脂組成物を充填された多層配線基板用基材であって、
前記貫通孔の前記導電層と前記絶縁性基材との境界部における前記導電層部分の孔径Ｄａより前記導電層の外表面側の孔径Ｄｂが小さいことを特徴とする多層配線基板用基材。A conductive layer forming a wiring pattern is provided on one surface of an insulating base material, and an adhesive layer for interlayer bonding is provided on the other surface, and a through hole penetrating the conductive layer, the insulating base material, and the adhesive layer. A substrate for a multilayer wiring board filled with a conductive resin composition for obtaining interlayer conduction,
A substrate for a multilayer wiring board, wherein a hole diameter Db on an outer surface side of the conductive layer is smaller than a hole diameter Da of a portion of the conductive layer at a boundary portion between the conductive layer and the insulating base in the through hole. 絶縁性基材の一方の面に配線パターンをなす導電層を、他方の面に層間接着のための接着層を設けられ、前記導電層と前記絶縁性基材と前記接着層を貫通する貫通孔に層間導通を得るための導電性樹脂組成物を充填された多層配線基板用基材であって、
前記貫通孔の前記導電層と前記絶縁性基材との境界部における前記導電層部分の孔径Ｄａより前記導電層の外表面側の孔径Ｄｂが小さく、
且つ、前記境界部における前記導電層部分の孔径Ｄａが前記境界部における前記絶縁性基材部分の孔径Ｄｃより大きいことを特徴とする多層配線基板用基材。A conductive layer forming a wiring pattern is provided on one surface of an insulating base material, and an adhesive layer for interlayer bonding is provided on the other surface, and a through hole penetrating the conductive layer, the insulating base material, and the adhesive layer. A substrate for a multilayer wiring board filled with a conductive resin composition for obtaining interlayer conduction,
The hole diameter Db on the outer surface side of the conductive layer is smaller than the hole diameter Da of the conductive layer portion at the boundary between the conductive layer and the insulating base material of the through hole,
And a hole diameter Da of the conductive layer portion at the boundary portion is larger than a hole diameter Dc of the insulating base portion portion at the boundary portion. 絶縁性基材の一方の面に配線パターンをなす導電層を、他方の面に層間接着のための接着層を設けられ、前記導電層と前記絶縁性基材と前記接着層を貫通する貫通孔に層間導通を得るための導電性樹脂組成物を充填された多層配線基板用基材であって、
前記貫通孔の前記導電層と前記絶縁性基材との境界部における前記導電層部分の孔径Ｄａより前記導電層の外表面側の孔径Ｄｂが小さく、
且つ、前記境界部における前記導電層部分の孔径Ｄａが前記境界部における前記絶縁性基材部分の孔径Ｄｃより大きく、しかも、前記孔径Ｄａ＞前記孔径Ｄｃ＞前記孔径Ｄｂであることを特徴とする多層配線基板用基材。A conductive layer forming a wiring pattern is provided on one surface of an insulating base material, and an adhesive layer for interlayer bonding is provided on the other surface, and a through hole penetrating the conductive layer, the insulating base material, and the adhesive layer. A substrate for a multilayer wiring board filled with a conductive resin composition for obtaining interlayer conduction,
The hole diameter Db on the outer surface side of the conductive layer is smaller than the hole diameter Da of the conductive layer portion at the boundary between the conductive layer and the insulating base material of the through hole,
Further, the hole diameter Da of the conductive layer portion at the boundary portion is larger than the hole diameter Dc of the insulating base portion portion at the boundary portion, and the hole diameter Da> the hole diameter Dc> the hole diameter Db. Substrate for multilayer wiring board. 絶縁性基材の一方の面に配線パターンをなす導電層を、他方の面に層間接着のための接着層を設けられ、前記導電層と前記絶縁性基材と前記接着層を貫通する貫通孔に層間導通を得るための導電性樹脂組成物を充填された多層配線基板用基材であって、
前記貫通孔の前記導電層と前記絶縁性基材との境界部における前記導電層部分の孔径Ｄａより前記導電層の外表面側の孔径Ｄｂが小さく、
且つ、前記境界部における前記絶縁性基材部分の孔径Ｄｃが前記境界部における前記導電層部分の孔径Ｄａに等しいかあるいはそれより大きいことを特徴とする多層配線基板用基材。A conductive layer forming a wiring pattern is provided on one surface of an insulating base material, and an adhesive layer for interlayer bonding is provided on the other surface, and a through hole penetrating the conductive layer, the insulating base material, and the adhesive layer. A substrate for a multilayer wiring board filled with a conductive resin composition for obtaining interlayer conduction,
The hole diameter Db on the outer surface side of the conductive layer is smaller than the hole diameter Da of the conductive layer portion at the boundary between the conductive layer and the insulating base material of the through hole,
And a hole diameter Dc of the insulating substrate portion at the boundary portion is equal to or larger than a hole diameter Da of the conductive layer portion at the boundary portion. 前記絶縁性基材はポリイミド等の可撓性樹脂フィルムであることを特徴とする請求項１〜８の何れか１項記載の多層配線基板用基材。The substrate for a multilayer wiring board according to any one of claims 1 to 8, wherein the insulating substrate is a flexible resin film such as polyimide. 接着層は熱可塑性ポリイミドにより構成されていることを特徴とする請求項５〜８の何れか１項記載の多層配線基板用基材。The base material for a multilayer wiring board according to any one of claims 5 to 8, wherein the adhesive layer is made of thermoplastic polyimide. 前記貫通孔の前記導電層部分の内壁面が縦断面で見て曲面あるいは傾斜面で、前記貫通孔は前記導電層部分において導電層外表面側が先細となるテーパ状をなしていることを特徴とする請求項１〜１０の何れか１項記載の多層配線基板用基材。An inner wall surface of the conductive layer portion of the through hole has a curved surface or an inclined surface as viewed in a longitudinal section, and the through hole has a tapered shape in which the outer surface side of the conductive layer in the conductive layer portion is tapered. The base material for a multilayer wiring board according to any one of claims 1 to 10. 請求項１〜１１の何れか１項記載の多層配線基板用基材を複数枚、重ねて接合してなる多層配線基板。A multilayer wiring board comprising a plurality of the multilayer wiring board substrates according to any one of claims 1 to 11, which are stacked and joined. 絶縁性基材の片面に配線パターンをなす導電層を設けられたものに、前記導電層と前記絶縁性基材との境界部における前記導電層部分の孔径Ｄａより前記導電層の外表面側の孔径Ｄｂが小さい貫通孔を穿孔する穿孔工程と、
導電性樹脂組成物を前記貫通孔に充填する充填工程と、
を有する多層配線基板用基材の製造方法。The one provided with a conductive layer forming a wiring pattern on one surface of the insulating base material, the outer surface side of the conductive layer from the hole diameter Da of the conductive layer portion at the boundary between the conductive layer and the insulating base material A piercing step of piercing a through hole having a small hole diameter Db;
A filling step of filling the through-hole with a conductive resin composition,
A method for producing a substrate for a multilayer wiring board, comprising: 絶縁性基材の片面に配線パターンをなす導電層を設けられたものに、前記導電層と前記絶縁性基材との境界部における前記導電層部分の孔径Ｄａより前記導電層の外表面側の孔径Ｄｂが小さく、且つ、前記境界部における前記導電層部分の孔径Ｄａが前記境界部における前記絶縁性基材部分の孔径Ｄｃより大きい貫通孔を穿孔する穿孔工程と、
導電性樹脂組成物を前記貫通孔に充填する充填工程と、
を有する多層配線基板用基材の製造方法。The one provided with a conductive layer forming a wiring pattern on one surface of the insulating base material, the outer surface side of the conductive layer from the hole diameter Da of the conductive layer portion at the boundary between the conductive layer and the insulating base material A hole diameter Db is small, and a hole diameter Da of the conductive layer portion at the boundary portion is a hole diameter larger than the hole diameter Dc of the insulating substrate portion at the boundary portion;
A filling step of filling the through-hole with a conductive resin composition,
A method for producing a substrate for a multilayer wiring board, comprising: 絶縁性基材の片面に配線パターンをなす導電層を設けられたものに、前記導電層と前記絶縁性基材との境界部における前記導電層部分の孔径Ｄａより前記導電層の外表面側の孔径Ｄｂが小さく、且つ、前記境界部における前記導電層部分の孔径Ｄａが前記境界部における前記絶縁性基材部分の孔径Ｄｃより大きく、しかも、前記孔径Ｄａ＞前記孔径Ｄｃ＞前記孔径Ｄｂである貫通孔を穿孔する穿孔工程と、
導電性樹脂組成物を前記貫通孔に充填する充填工程と、
を有する多層配線基板用基材の製造方法。The one provided with a conductive layer forming a wiring pattern on one surface of the insulating base material, the outer surface side of the conductive layer from the hole diameter Da of the conductive layer portion at the boundary between the conductive layer and the insulating base material The hole diameter Db is small, and the hole diameter Da of the conductive layer portion at the boundary is larger than the hole diameter Dc of the insulating base material portion at the boundary, and the hole diameter Da> the hole diameter Dc> the hole diameter Db. A drilling step of drilling a through hole,
A filling step of filling the through-hole with a conductive resin composition,
A method for producing a substrate for a multilayer wiring board, comprising: 絶縁性基材の片面に配線パターンをなす導電層を設けられたものに、前記導電層と前記絶縁性基材との境界部における前記導電層部分の孔径Ｄａより前記導電層の外表面側の孔径Ｄｂが小さく、且つ、前記境界部における前記絶縁性基材部分の孔径Ｄｃが前記境界部における前記導電層部分の孔径Ｄａに等しいかあるいはそれより大きい貫通孔を穿孔する穿孔工程と、
導電性樹脂組成物を前記貫通孔に充填する充填工程と、
を有する多層配線基板用基材の製造方法。The one provided with a conductive layer forming a wiring pattern on one surface of the insulating base material, the outer surface side of the conductive layer from the hole diameter Da of the conductive layer portion at the boundary between the conductive layer and the insulating base material A hole diameter Db is small, and a hole diameter Dc of the insulating base portion at the boundary portion is equal to or larger than a hole diameter Da of the conductive layer portion at the boundary portion;
A filling step of filling the through-hole with a conductive resin composition,
A method for producing a substrate for a multilayer wiring board, comprising: 前記穿孔工程は、絶縁性基材に所定の孔径の穴あけを行う第１穴あけ工程と、穴あけされた絶縁性基材の側から等方性を有するエッチングによって導電層に穴あけを行う第２穴あけ工程とを含んでいることを特徴とする請求項１３〜１６の何れか１項記載の多層配線基板用基材の製造方法。The perforating step includes a first perforating step of perforating the insulating base material having a predetermined hole diameter, and a second perforating step of perforating the conductive layer by isotropic etching from the perforated insulating base material side. The method for producing a base material for a multilayer wiring board according to any one of claims 13 to 16, comprising: 絶縁性基材の一方の面に配線パターンをなす導電層を、他方の面に層間接着のための接着層を設けられたものに、前記導電層と前記絶縁性基材との境界部における前記導電層部分の孔径Ｄａより前記導電層の外表面側の孔径Ｄｂが小さい貫通孔を穿孔する穿孔工程と、
導電性樹脂組成物を前記貫通孔に充填する充填工程と、
を有する多層配線基板用基材の製造方法。A conductive layer that forms a wiring pattern on one surface of an insulating base material, and an adhesive layer for interlayer bonding provided on the other surface, at the boundary between the conductive layer and the insulating base material. A perforation step of perforating a through hole having a smaller diameter Db on the outer surface side of the conductive layer than the diameter Da of the conductive layer portion;
A filling step of filling the through-hole with a conductive resin composition,
A method for producing a substrate for a multilayer wiring board, comprising: 絶縁性基材の一方の面に配線パターンをなす導電層を、他方の面に層間接着のための接着層を設けられたものに、導電層と絶縁性基材との境界部における前記導電層部分の孔径Ｄａより導電層の外表面側の孔径Ｄｂが小さく、且つ、前記境界部における前記導電層部分の孔径Ｄａが前記境界部における前記絶縁性基材部分の孔径Ｄｃより大きい貫通孔を穿孔する穿孔工程と、
導電性樹脂組成物を前記貫通孔に充填する充填工程と、
を有する多層配線基板用基材の製造方法。A conductive layer forming a wiring pattern is provided on one surface of an insulating base material, and an adhesive layer for interlayer bonding is provided on the other surface, and the conductive layer at a boundary between the conductive layer and the insulating base material is provided. The hole diameter Db on the outer surface side of the conductive layer is smaller than the hole diameter Da of the portion, and the hole diameter Da of the conductive layer portion at the boundary is larger than the hole diameter Dc of the insulating base portion at the boundary. Perforating process,
A filling step of filling the through-hole with a conductive resin composition,
A method for producing a substrate for a multilayer wiring board, comprising: 絶縁性基材の一方の面に配線パターンをなす導電層を、他方の面に層間接着のための接着層を設けられたものに、前記導電層と前記絶縁性基材との境界部における前記導電層部分の孔径Ｄａより前記導電層の外表面側の孔径Ｄｂが小さく、且つ、前記境界部における前記導電層部分の孔径Ｄａが前記境界部における前記絶縁性基材部分の孔径Ｄｃより大きく、しかも、前記孔径Ｄａ＞前記孔径Ｄｃ＞前記孔径Ｄｂである貫通孔を穿孔する穿孔工程と、
導電性樹脂組成物を前記貫通孔に充填する充填工程と、
を有する多層配線基板用基材の製造方法。A conductive layer that forms a wiring pattern on one surface of an insulating base material, and an adhesive layer for interlayer bonding provided on the other surface, at the boundary between the conductive layer and the insulating base material. The hole diameter Db on the outer surface side of the conductive layer is smaller than the hole diameter Da of the conductive layer portion, and the hole diameter Da of the conductive layer portion at the boundary portion is larger than the hole diameter Dc of the insulating base portion portion at the boundary portion, And a perforation step of perforating a through-hole having the hole diameter Da> the hole diameter Dc> the hole diameter Db;
A filling step of filling the through-hole with a conductive resin composition,
A method for producing a substrate for a multilayer wiring board, comprising: 絶縁性基材の一方の面に配線パターンをなす導電層を、他方の面に層間接着のための接着層を設けられたものに、前記導電層と前記絶縁性基材との境界部における前記導電層部分の孔径Ｄａより前記導電層の外表面側の孔径Ｄｂが小さく、且つ、前記境界部における前記絶縁性基材部分の孔径Ｄｃが前記境界部における前記導電層部分の孔径Ｄａに等しいかあるいはそれより大きい貫通孔を穿孔する穿孔工程と、
導電性樹脂組成物を前記貫通孔に充填する充填工程と、
を有する多層配線基板用基材の製造方法。A conductive layer that forms a wiring pattern on one surface of an insulating base material, and an adhesive layer for interlayer bonding provided on the other surface, at the boundary between the conductive layer and the insulating base material. Is the hole diameter Db on the outer surface side of the conductive layer smaller than the hole diameter Da of the conductive layer portion, and is the hole diameter Dc of the insulating base portion portion at the boundary portion equal to the hole diameter Da of the conductive layer portion at the boundary portion? Or a drilling step of drilling a larger through hole,
A filling step of filling the through-hole with a conductive resin composition,
A method for producing a substrate for a multilayer wiring board, comprising: 前記穿孔工程は、接着層と絶縁性基材とに所定の孔径の穴あけを行う第１穴あけ工程と、穴あけされた接着層・絶縁性基材の側から等方性を有するエッチングによって導電層に穴あけを行う第２穴あけ工程とを含んでいることを特徴とする請求項１８〜２１の何れか１項記載の多層配用基材の製造方法。The perforating step includes a first perforating step of perforating the adhesive layer and the insulating base material with a predetermined hole diameter, and an isotropic etching from the side of the perforated adhesive layer / insulating base material to the conductive layer. 22. The method for producing a multilayer distribution base material according to any one of claims 18 to 21, further comprising a second perforating step of perforating. 前記第２穴あけ工程は、回路形成のための導電層のエッチングと同工程で行うことを特徴とする請求項１７または２２記載の多層配線基板用基材の製造方法。23. The method according to claim 17, wherein the second drilling step is performed in the same step as the etching of the conductive layer for forming a circuit.
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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007250581A (en) * 2006-03-13 2007-09-27 Fujitsu Ltd Multilayer wiring board and production method therefor
JP2007250996A (en) * 2006-03-17 2007-09-27 Kyocera Corp Wiring board, electronic device equipped with wiring board, and probe card
WO2009017051A1 (en) * 2007-07-27 2009-02-05 Zeon Corporation Composite for multilayer circuit board
JP2014086605A (en) * 2012-10-25 2014-05-12 Ngk Spark Plug Co Ltd Wiring board and method of manufacturing the same
KR20190038016A (en) * 2017-09-29 2019-04-08 삼성전기주식회사 Coil component and method for manufacturing the same

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007250581A (en) * 2006-03-13 2007-09-27 Fujitsu Ltd Multilayer wiring board and production method therefor
JP2007250996A (en) * 2006-03-17 2007-09-27 Kyocera Corp Wiring board, electronic device equipped with wiring board, and probe card
WO2009017051A1 (en) * 2007-07-27 2009-02-05 Zeon Corporation Composite for multilayer circuit board
JP5353698B2 (en) * 2007-07-27 2013-11-27 日本ゼオン株式会社 Method for producing composite for multilayer circuit board
JP2014086605A (en) * 2012-10-25 2014-05-12 Ngk Spark Plug Co Ltd Wiring board and method of manufacturing the same
KR20190038016A (en) * 2017-09-29 2019-04-08 삼성전기주식회사 Coil component and method for manufacturing the same
US11315718B2 (en) * 2017-09-29 2022-04-26 Samsung Electro-Mechanics Co., Ltd. Coil component and method for manufacturing the same
KR102450597B1 (en) * 2017-09-29 2022-10-07 삼성전기주식회사 Coil component and method for manufacturing the same

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