JP2004179011A - Insulating film and multilayer wiring board using this - Google Patents

Insulating film and multilayer wiring board using this Download PDF

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Publication number
JP2004179011A
JP2004179011A JP2002344736A JP2002344736A JP2004179011A JP 2004179011 A JP2004179011 A JP 2004179011A JP 2002344736 A JP2002344736 A JP 2002344736A JP 2002344736 A JP2002344736 A JP 2002344736A JP 2004179011 A JP2004179011 A JP 2004179011A
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Prior art keywords
insulating film
liquid crystal
crystal polymer
layer
wiring board
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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JP2002344736A
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Japanese (ja)
Inventor
Takuji Seri
拓司 世利
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Kyocera Corp
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Kyocera Corp
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Priority to JP2002344736A priority Critical patent/JP2004179011A/en
Publication of JP2004179011A publication Critical patent/JP2004179011A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/10—Bump connectors; Manufacturing methods related thereto
    • H01L2224/15—Structure, shape, material or disposition of the bump connectors after the connecting process
    • H01L2224/16—Structure, shape, material or disposition of the bump connectors after the connecting process of an individual bump connector
    • H01L2224/161—Disposition
    • H01L2224/16151—Disposition the bump connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
    • H01L2224/16221—Disposition the bump connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
    • H01L2224/16225—Disposition the bump connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being non-metallic, e.g. insulating substrate with or without metallisation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/26—Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
    • H01L2224/31—Structure, shape, material or disposition of the layer connectors after the connecting process
    • H01L2224/32—Structure, shape, material or disposition of the layer connectors after the connecting process of an individual layer connector
    • H01L2224/321—Disposition
    • H01L2224/32151—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
    • H01L2224/32221—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
    • H01L2224/32225—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being non-metallic, e.g. insulating substrate with or without metallisation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/73—Means for bonding being of different types provided for in two or more of groups H01L2224/10, H01L2224/18, H01L2224/26, H01L2224/34, H01L2224/42, H01L2224/50, H01L2224/63, H01L2224/71
    • H01L2224/732—Location after the connecting process
    • H01L2224/73201—Location after the connecting process on the same surface
    • H01L2224/73203—Bump and layer connectors
    • H01L2224/73204—Bump and layer connectors the bump connector being embedded into the layer connector
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/15—Details of package parts other than the semiconductor or other solid state devices to be connected
    • H01L2924/151—Die mounting substrate
    • H01L2924/153—Connection portion
    • H01L2924/1531—Connection portion the connection portion being formed only on the surface of the substrate opposite to the die mounting surface
    • H01L2924/15311—Connection portion the connection portion being formed only on the surface of the substrate opposite to the die mounting surface being a ball array, e.g. BGA

Abstract

<P>PROBLEM TO BE SOLVED: To provide an insulating film with an excellent insulating property and conduction reliability and a multilayer wiring board using the same. <P>SOLUTION: The multilayer wiring board is provided with a coating layer 2 made of thermosetting resin on top and bottom faces of liquid crystal polymer layer 1, with a thermal expansion coefficient in a layer direction of 3×10<SP>-6</SP>to 40×10<SP>-6</SP>/°C and a contraction percentage in a layer direction of 0.15% or less after heating for 2 to 180 minutes at temperatures of 190 to 270°C. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、各種ＡＶ機器や家電機器・通信機器・コンピュータやその周辺機器等の電子機器に使用される絶縁フィルムおよびこれを用いた多層配線基板に関し、特に液晶ポリマーを一部に用いた絶縁フィルムおよびこれを用いた多層配線基板に関する。
【０００２】
【従来の技術】
従来、半導体素子等の能動部品や容量素子・抵抗素子等の受動部品を多数搭載して所定の電子回路を構成した混成集積回路を形成するための多層配線基板は、通常、ガラスクロスにエポキシ樹脂を含浸させて成る絶縁フィルムにドリルによって上下に貫通孔を形成し、この貫通孔内部および絶縁層表面に複数の配線導体を形成した配線基板を、多数積層することによって形成されている。
【０００３】
一般に、現在の電子機器は、移動体通信機器に代表されるように小型・薄型・軽量・高性能・高機能・高品質・高信頼性が要求されており、このような電子機器に搭載される混成集積回路等の電子部品も小型・高密度化が要求されるようになってきており、このような高密度化の要求に応えるために、電子部品を構成する多層配線基板も、配線導体の微細化や絶縁層の薄層化・貫通孔の微細化が必要となってきている。このため、近年、貫通孔を微細化するために、ドリル加工より微細加工が可能なレーザ加工が用いられるようになってきた。
【０００４】
しかしながら、ガラスクロスにエポキシ樹脂を含浸させて成る絶縁フィルムは、ガラスクロスをレーザにより穿設加工することが困難なために貫通孔の微細化には限界があり、また、ガラスクロスの厚みが不均一のために均一な孔径の貫通孔を形成することが困難であるという問題点を有していた。
【０００５】
このような問題点を解決するために、アラミド樹脂繊維で製作した不織布にエポキシ樹脂を含浸させて成る絶縁フィルムや、ポリイミドフィルムにエポキシ系接着剤を塗布して成る絶縁フィルムを絶縁層に用いた多層配線基板が提案されている。
【０００６】
しかしながら、アラミド不織布やポリイミドフィルムを用いた絶縁フィルムは吸湿性が高く、吸湿した状態で半田リフローを行なうと半田リフローの熱により吸湿した水分が気化してガスが発生し、絶縁層間で剥離してしまう等の問題点を有していた。
【０００７】
このような問題点を解決するために、多層配線基板の絶縁層の材料として液晶ポリマーを用いることが検討されている。液晶ポリマーから成る層は、剛直な分子で構成されているとともに分子同士がある程度規則的に並んだ構成をしており分子間力が強いことから、高耐熱性・高弾性率・高寸法安定性・低吸湿性を示し、ガラスクロスのような強化材を用いる必要がなく、また、微細加工性にも優れるという特徴を有している。さらに、高周波領域においても、低誘電率・低誘電正接であり高周波特性に優れるという特徴を有している。
【０００８】
このような液晶ポリマーの特徴を活かし、特開平８−９７５６５号公報には、回路層が第１の液晶ポリマーを含み、この回路層間に第１の液晶ポリマーの融点よりも低い融点を有する第２の液晶ポリマーを含む接着剤層を挿入して成る多層プリント回路基板が提案されている。
【０００９】
【特許文献１】
特開平８−９７５６５号公報
【００１０】
【発明が解決しようとする課題】
しかしながら、特開平８−９７５６５号公報に提案された多層プリント回路基板は、回路層同士を間に液晶ポリマーを含む接着剤層を挿入して熱圧着により接着する際、液晶ポリマー分子が剛直であるとともにある程度分子が規則正しく配向して分子間力が強くなっているために分子が動き難く、回路層の液晶ポリマーと接着剤層の液晶ポリマーの表面のごく一部の分子だけしか絡み合うことができないために密着性が悪く、高温バイアス試験において層間で剥離して絶縁不良が発生してしまうという問題点を有していた。
【００１１】
また、回路層の導体箔と液晶ポリマーを熱融着により接着する際、液晶ポリマー分子が動き難いために導体箔表面の微細な凹部に入ることができず、その結果、十分なアンカー効果を発揮することができず、導体箔と液晶ポリマーとの密着性が悪くなって、高温高湿下において両者間で剥離して導体箔が断線してしまうという問題点も有していた。
【００１２】
本発明はかかる従来技術の問題点に鑑み案出されたものであり、その目的は、絶縁性・導通信頼性に優れた絶縁フィルムおよびこれを用いた多層配線基板を提供することに有る。
【００１３】
【課題を解決するための手段】
本発明の絶縁フィルムは、液晶ポリマー層の上下面に熱硬化性樹脂から成る被覆層を有して成り、層方向における熱膨張係数が３×１０−６〜４０×１０−６／℃であり、かつ１９０〜２７０℃の温度で２〜１８０分間加熱した際の前記層方向における収縮率が０．１５％以下であることを特徴とするものである。
【００１４】
本発明の絶縁フィルムによれば、絶縁フィルムを液晶ポリマー層の上下面に熱硬化性樹脂から成る被覆層を有する構成とし、絶縁フィルムの層方向における熱膨張係数を３×１０−６〜４０×１０−６／℃としたことから、この絶縁フィルムを用いて配線基板を製作した場合、絶縁フィルムの熱膨張係数が配線導体の熱膨張係数に近似し、絶縁フィルムと配線導体との熱膨張差による応力を小さなものとすることができ、その結果、高温高湿下で絶縁フィルムと配線導体間で剥離したり、温度サイクル試験で絶縁フィルムにクラックが発生して配線導体が断線してしまうことがない。また、熱硬化性樹脂の分子が液晶ポリマー分子ほど剛直ではなく、また、規則正しい配向性も示さないことから分子が比較的動きやすく、その結果、絶縁フィルムを多層化した場合においても、絶縁フィルム同士の密着性が良好となり、高温バイアス試験において絶縁フィルム間で剥離して絶縁不良が発生してしまうこともない。さらに、絶縁フィルム表面に配線導体を配設した場合においても、熱硬化性樹脂の分子が配線導体表面の微細な凹部に入り込み十分なアンカー効果を発揮することができ、絶縁フィルムと配線導体との密着性が良好となり、その結果、高温高湿下で両者間で剥離して配線導体が断線してしまうということもない。また、１９０〜２７０℃の温度で２〜１８０分間加熱した際の層方向における収縮率を０．１５％以下としたことから、絶縁フィルムに配線導体および貫通導体を配設するとともに絶縁フィルムを多層化して多層配線基板を製作する場合においても、多層化する際の加熱プレスによって絶縁フィルムの層方向における貫通導体の位置精度が低下したり、貫通導体の直径にばらつきが生じることもなく、その結果、配線導体と貫通導体との導通信頼性に優れた多層配線基板を製作することができる。
【００１５】
また、本発明の絶縁フィルムは、上記構成において、液晶ポリマー層の厚みが絶縁フィルムの厚みの４０〜９０％であることを特徴とするものである。
【００１６】
本発明の絶縁フィルムによれば、上記構成において、液晶ポリマー層の厚みを絶縁フィルムの厚みの４０〜９０％とした場合には、温度サイクル試験等の際に絶縁フィルムに熱応力が印加されたとしても、小さな熱膨張係数と小さな収縮率を有する液晶ポリマー層が大きな熱膨張係数と大きな収縮率を有する被覆層を良好に拘束して絶縁フィルム全体の熱膨張や収縮を小さなものとすることができる。
【００１７】
さらに、本発明の絶縁フィルムは、上記構成において、液晶ポリマー層の水との接触角が３〜６５°であって、かつ表面エネルギーが４５〜８０ｍＪ／ｍ２であることを特徴とするものである。
【００１８】
本発明の絶縁フィルムによれば、上記構成において、液晶ポリマー層を水との接触角が３〜６５°であって、かつ表面エネルギーが４５〜８０ｍＪ／ｍ２とした場合には、液晶ポリマー層表面の活性化された比較的熱運動しやすい分子層と熱硬化性樹脂から成る被覆層とが良好に絡み合って結合し、液晶ポリマー層と被覆層とがより強固に密着した絶縁フィルムとすることができる。
【００１９】
また、本発明の絶縁フィルムは、上記構成において、液晶ポリマー層の上下面の算術平均粗さＲａが０．０５〜５μｍであることを特徴とするものである。
【００２０】
本発明の絶縁フィルムによれば、上記構成において、液晶ポリマー層の上下面の算術平均粗さＲａを０．０５〜５μｍとした場合には、液晶ポリマー層の上下面が熱硬化性樹脂から成る被覆層と良好なアンカー効果を有する密着性の良好なものとなり、液晶ポリマー層と被覆層とがより強固に密着した絶縁フィルムとすることができる。
【００２１】
また、本発明の絶縁フィルムは、上記構成において、被覆層は粒子径が０．１〜２μｍの無機絶縁粉末を１０〜７０体積％含有していることを特徴とするものである。
【００２２】
本発明の絶縁フィルムによれば、上記構成において、被覆層を粒子径が０．１〜２μｍの無機絶縁粉末を１０〜７０体積％含有するものとした場合には、絶縁フィルムに配線導体および貫通導体を配設するとともに絶縁フィルムを多層化して多層配線基板を製作する場合においても、無機絶縁粉末が被覆層の流動性や加熱プレスによる収縮を抑制し、多層化する際の加熱プレスによって層方向における貫通導体の位置ずれや貫通導体の直径のばらつき、さらには被覆層の厚みばらつきを低減することができ、より寸法安定性に優れた絶縁フィルムとすることができる。
【００２３】
さらに、本発明の絶縁フィルムは、上記構成において、無機絶縁粉末はその形状が略球状であることを特徴とするものである。
【００２４】
本発明の絶縁フィルムによれば、上記構成において、無機絶縁粉末の形状を略球状とした場合には、無機絶縁粉末を熱硬化性樹脂へ充填する際に充填性や混練性が良好となり、無機絶縁粉末を熱硬化性樹脂から成る被覆層へ一様に分布させることができ、その結果、被覆層の熱膨張係数や収縮率がより均一な絶縁フィルムとすることができる。
【００２５】
また、本発明の絶縁フィルムは、上記構成において、熱硬化性樹脂が熱硬化性ポリフェニレンエーテルであることを特徴とするものである。
【００２６】
本発明の絶縁フィルムによれば、上記構成において、熱硬化性樹脂を熱硬化性ポリフェニレンエーテルとした場合には、熱硬化性ポリフェニレンエーテルが耐熱性に優れるとともに寸法安定性に優れることから、温度サイクル信頼性に優れるとともに、配線導体を接着する際の位置精度の良好な絶縁フィルムとすることができる。
【００２７】
本発明の多層配線基板は、上下面の少なくとも一方の面に金属箔から成る配線導体が配設された上記の絶縁フィルムを複数積層して成るとともに、この絶縁フィルムを挟んで上下に位置する配線導体間を絶縁フィルムに形成された貫通導体を介して電気的に接続したことを特徴とするものである。
【００２８】
本発明の多層配線基板によれば、多層配線基板を上記の絶縁フィルムを用いて形成したことから、耐湿性・導通信頼性に優れた多層配線基板とすることができる。
【００２９】
【発明の実施の形態】
次に本発明の絶縁フィルムおよびこれを用いた多層配線基板を添付の図面に基づいて詳細に説明する。
図１は、本発明の絶縁フィルムの実施の形態の一例を示す断面図であり、図２は図１の絶縁フィルムを用いて製作した本発明の多層配線基板の実施の形態の一例を示す断面図である。なお、図２は、本発明の多層配線基板に半導体素子等の電子部品を搭載して混成集積回路とした場合の例を示している。また、図３は、図２に示す多層配線基板の配線導体の幅方向の要部拡大断面図である。
【００３０】
これらの図において１は液晶ポリマー層、２は熱硬化性樹脂から成る被覆層で、主にこれらで本発明の絶縁フィルム３が構成されている。また、４は配線導体、５は貫通導体、７は半導体素子等の電子部品で、主に絶縁フィルム３と配線導体４と貫通導体５とで本発明の多層配線基板６が構成されている。なお、本例の多層配線基板６では、絶縁フィルム３を４層積層して成るものを示している。
【００３１】
絶縁フィルム３は、液晶ポリマー層１と、その上下面に被着形成された熱硬化性樹脂から成る被覆層２とから構成されており、これを用いて多層配線基板６を形成した場合、配線導体４や多層配線基板６に搭載される電子部品７の支持体としての機能を有する。
【００３２】
なお、ここで液晶ポリマーとは、溶融状態あるいは溶液状態において、液晶性を示すポリマーあるいは光学的に複屈折する性質を有するポリマーを指し、一般に溶液状態で液晶性を示すリオトロピック液晶ポリマーや溶融時に液晶性を示すサーモトロピック液晶ポリマー、あるいは、熱変形温度で分類される１型・２型・３型すべての液晶ポリマーを含むものであり、本発明に用いる液晶ポリマーとしては、温度サイクル信頼性・半田耐熱性・加工性の観点からは２３０〜４２０℃の温度、特に２７０〜３８０℃の温度に融点を有するものが好ましい。
【００３３】
絶縁フィルム３は、これを用いて多層配線基板６を製作する際に、配線導体４と熱膨張係数を近いものとし、絶縁フィルム３と配線導体４との剥離や絶縁フィルム３のクラックに対する耐性をより高いものにするという観点からは、上下面に平行な方向、すなわち層方向における熱膨張係数を３×１０−６〜４０×１０−６／℃とすることが重要である。
【００３４】
また、絶縁フィルム３は、多層化する際の加熱プレスによって絶縁フィルム３の層方向における貫通導体５の位置精度が低下したり、貫通導体５の直径にばらつきが生じることを防止するという観点からは、１９０〜２７０℃の温度で２〜１８０分間加熱した際の層方向における収縮率を０．１５％以下としておく必要があり、そして、本発明の絶縁フィルム３においてはこのことが重要である。
【００３５】
本発明の絶縁フィルム３によれば、絶縁フィルム３の層方向における熱膨張係数を３×１０−６〜４０×１０−６／℃としたことから、この絶縁フィルム３を用いて配線基板６を製作した場合、絶縁フィルム３の熱膨張係数が配線導体４の熱膨張係数に近似し、絶縁フィルム３と配線導体４との熱膨張差による応力を小さなものとすることができ、その結果、高温高湿下で絶縁フィルム３と配線導体４間で剥離したり、温度サイクル試験で絶縁フィルム３にクラックが発生して配線導体４が断線してしまうということがない。
【００３６】
また、熱硬化性樹脂の分子が液晶ポリマー分子ほど剛直ではなく、規則正しい配向性も示さないことから分子が比較的動きやすく、その結果、絶縁フィルム３を多層化した場合においても、絶縁フィルム３同士の密着性が良好となり、高温バイアス試験において絶縁フィルム３間で剥離して絶縁不良が発生してしまうこともない。
【００３７】
さらに、絶縁フィルム３表面に配線導体４を配設した場合においても、熱硬化性樹脂の分子が配線導体４表面の微細な凹部に入り込み十分なアンカー効果を発揮することができ、絶縁フィルム３と配線導体４との密着性が良好となり、その結果、高温高湿下で両者間で剥離して配線導体４が断線してしまうということもない。
【００３８】
また、１９０〜２７０℃の温度で２〜１８０分間加熱した際の絶縁フィルム３の上下面に平行な方向における収縮率を０．１５％以下としたことから、絶縁フィルム３に配線導体４および貫通導体５を配設するとともに絶縁フィルム３を多層化して多層配線基板６を製作する場合においても、多層化する際の加熱プレスによって絶縁フィルム３の上下面に平行な方向における貫通導体５の位置精度が低下したり、貫通導体５の直径にばらつきが生じることもなく、その結果、配線導体４と貫通導体５との導通信頼性に優れた多層配線基板６を製作することができる。
【００３９】
なお、絶縁フィルム３の熱膨張係数が３×１０−６／℃未満となると、絶縁フィルム３の熱膨張係数が配線導体４よりも小さくなりすぎて絶縁フィルム３と配線導体４間で剥離が生じ易くなる傾向があり、４０×１０−６／℃を超えると、絶縁フィルム３の熱膨張係数が配線導体４よりも大きくなりすぎて絶縁フィルム３に熱膨張差によるクラックが生じる傾向にある。したがって、絶縁フィルム３は、層方向における熱膨張係数が３×１０−６〜４０×１０−６／℃であることが重要である。
【００４０】
また、絶縁フィルム３の１９０〜２７０℃の温度で２〜１８０分間加熱した際の層方向における収縮率が０．１５％を超えると、上下面と平行な方向における貫通導体５の位置精度の低下や貫通導体５の直径のばらつきを防止することが困難となり、高温高湿下で貫通導体５の抵抗が上昇する傾向にある。したがって、絶縁フィルム３の１９０〜２７０℃の温度で２〜１８０分間加熱した際の層方向における収縮率は０．１５％以下であることが重要である。さらに、絶縁フィルム３を４層以上積層して多層配線基板６を製作する場合には、貫通導体５の高温高湿下での導通信頼性の観点からは０．１％以下としておくことがより好ましい。
【００４１】
なお、ここで絶縁フィルム３の１９０〜２７０℃の温度で２〜１８０分間加熱した際の層方向における収縮率とは、絶縁フィルム３のみを１９０〜２７０℃の任意の温度で３〜１８０分間の範囲で加熱した時に、層方向における任意の２点間の寸法変化量を加熱前の寸法で除した値を意味し、定量可能なものである。この収縮率は２軸延伸法やインフレーション法で液晶ポリマー層１を製作する際に圧力や昇温速度を適宜調整することにより、また、液晶ポリマー層１の上下面に被覆層２を形成する際に液晶ポリマー層１の表面処理雰囲気や時間を適宜調整することにより、さらに、被覆層２を液晶ポリマー層１の上下面に形成した後、被覆層２を加熱・乾燥する際の温度や時間を適宜調整することにより、所望の値とすることができる。
【００４２】
また、液晶ポリマー層１は、層としての物性を損なわない範囲内で、熱安定性を改善するための酸化防止剤や耐光性を改善するための紫外線吸収剤等の光安定剤、難燃性を付加するためのハロゲン系もしくはリン酸系の難燃性剤、アンチモン系化合物やホウ酸亜鉛・メタホウ酸バリウム・酸化ジルコニウム等の難燃助剤、潤滑性を改善するための高級脂肪酸や高級脂肪酸エステル・高級脂肪酸金属塩・フルオロカーボン系界面活性剤等の滑剤、熱膨張係数や収縮率を調整するため、および／または機械的強度を向上するための酸化アルミニウム・酸化珪素・酸化チタン・酸化バリウム・酸化ストロンチウム・酸化ジルコニウム・酸化カルシウム・ゼオライト・窒化珪素・窒化アルミニウム・炭化珪素・チタン酸カリウム・チタン酸バリウム・チタン酸ストロンチウム・チタン酸カルシウム・ホウ酸アルミニウム・スズ酸バリウム・ジルコン酸バリウム・ジルコン酸ストロンチウム等の充填材を含有してもよい。
【００４３】
なお、上記の充填材等の粒子形状は、略球状・針状・フレーク状等があり、充填性の観点からは略球状が好ましい。また、粒子径は、通常０．１〜１５μｍ程度であり、液晶ポリマー層１の厚みよりも小さい。
【００４４】
また、液晶ポリマー層１の厚みは、小さな熱膨張係数と小さな収縮率を有する液晶ポリマー層１が大きな熱膨張係数と大きな収縮率を有する被覆層２を良好に拘束して絶縁フィルム３全体の熱膨張や収縮を小さなものとするという観点からは、絶縁フィルム３の厚みの４０〜９０％としておくことが好ましい。
【００４５】
液晶ポリマー層１の厚みが絶縁フィルム３の厚みの４０％未満であると液晶ポリマー層１が被覆層２の熱膨張や収縮を拘束することが困難となり、例えばこの絶縁フィルム３を用いて多層配線基板６を製作した際に、絶縁フィルム３の熱膨張係数や収縮率が配線導体４の値よりも大きくなり、これらの熱膨張差や収縮差による応力により絶縁フィルム３にクラックが発生し易くなる傾向にある。また、液晶ポリマー層１の厚みが９０％を超えると、被覆層２の熱膨張が絶縁フィルム３の熱膨張に寄与する効果が小さくなって絶縁フィルム３の熱膨張係数が配線導体４の熱膨張係数よりも小さくなり、これらの熱膨張差により配線導体４の剥離を生じ易くなる傾向にある。したがって、液晶ポリマー層１の厚みは絶縁フィルム３の厚みの４０〜９０％としておくことが好ましく、特に多層配線基板６を製作し電子部品７を実装したときの接続信頼性の観点からは５０〜８５％の範囲としておくことが好ましい。
【００４６】
また、液晶ポリマー層１は、被覆層２との密着性を良好とするために、その表面をバフ研磨・ブラスト研磨・ブラシ研磨・プラズマ処理・コロナ処理・紫外線処理・薬品処理等の方法を用いて水との接触角が３〜６５゜であって、かつ表面エネルギーが４５〜８０ｍＪ／ｍ２となるように処理しておくことが好ましい。
【００４７】
液晶ポリマー層１に対する水の濡れ性は、液晶ポリマー層１の上下面の水素結合可能な活性基の存在する割合と相関関係にあり、液晶ポリマー層１の上下面を水との接触角が３〜６５°とすることにより、被覆層２が液晶ポリマー層１の上下面と強い分子間力で結合して、液晶ポリマー層１と被覆層２との密着性をさらに良好なものとなすことができ、その結果、高温バイアス試験においても両者間で剥離することのない絶縁フィルム３とすることができる。
【００４８】
液晶ポリマー層１は、水との接触角が３°より小さいと、被覆層２が液晶ポリマー層１上に極端に広がってしまって位置精度が低下し、絶縁フィルム３を複数枚重ねるとともに加熱・加圧して多層化する際に、絶縁フィルム３の表面に形成される配線導体４や内部に形成される貫通導体５の位置がずれて断線し易くなる傾向があり、また、６５°を超えると液晶ポリマー層１と被覆層２との密着性が低下して両者間で剥離し易くなる傾向がある。したがって、液晶ポリマー層１の上下面の水との接触角は３〜６５°の範囲としておくことが好ましい。
【００４９】
なお、接触角を評価するための水は、ＪＩＳ Ｋ ００５０「化学分析方法通則」に規定される蒸留法もしくはイオン交換法によって精製した水、または逆浸透法・拘留法・イオン交換法等を組み合わせた方法によって精製した水を示す。
【００５０】
また、液晶ポリマー層１は、表面の活性化された比較的熱運動しやすい分子層と被覆層２とが良好に絡み合って結合し、両者の密着をさらに強固なものとするという観点からは、その表面エネルギーを４５〜８０ｍＪ／ｍ２とすることが好ましい。
【００５１】
液晶ポリマー層１の上下面の表面エネルギーが４５ｍＪ／ｍ２未満であると、液晶ポリマー層１表面の分子層が十分に活性化されず、被覆層２と良好に絡み合って結合することが困難となる傾向があり、８０ｍＪ／ｍ２を超えると液晶ポリマー層１の表面が非常に反応性が高くなって空気中の酸素と反応してその表面に強度の弱い酸化物が形成され、その結果、液晶ポリマー層１と被覆層２との密着性が低下して両者間で剥離し易く成る傾向がある。したがって、液晶ポリマー層１の表面エネルギーを４５〜８０ｍＪ／ｍ２とすることが好ましい。
【００５２】
さらに、液晶ポリマー層１は、その表面の算術平均粗さＲａを０．０５〜５μｍとしておくことが好ましい。表面の算術平均粗さＲａを０．０５〜５μｍとした場合には、液晶ポリマー層１の上下面が被覆層２と良好なアンカー効果を有する密着性の良好なものとなり、液晶ポリマー層１と被覆層２とがより強固に密着したものとすることができる。
【００５３】
なお、算術平均粗さＲａは、半田リフローの際に液晶ポリマー層１と被覆層２との剥離を防止するという観点からは０．０５μｍ以上であることが好ましく、表面に被覆層２を形成する際に空気のかみ込みを防止するという観点からは５μｍ以下であることが好ましい。したがって、液晶ポリマー層１は、その表面の算術平均粗さＲａを０．０５〜５μｍとすることが好ましい。
【００５４】
次に、被覆層２は、熱硬化性樹脂から成り、後述する配線導体４を被着形成する際の接着剤の機能を有するとともに、絶縁フィルム３を用いて多層配線基板６を構成する際に、絶縁フィルム３同士を積層する際の接着剤の役目を果たす。
【００５５】
このような熱硬化性樹脂としては、エポキシ樹脂やシアネート樹脂・フェノール樹脂・ポリイミド樹脂・熱硬化性ポリフェニレンエーテル樹脂・ビスマレイミドトリアジン樹脂等の加熱により硬化反応する樹脂が用いられ、とりわけ温度サイクル信頼性や配線導体４を接着する際の位置精度の観点からは、アリル変性ポリフェニレンエーテル等の熱硬化性ポリフェニレンエーテルを含有することが好ましい。
【００５６】
また、被覆層２は、弾性率を調整するためのゴム成分や熱安定性を改善するための酸化防止剤、耐光性を改善するための紫外線吸収剤等の光安定剤、難燃性を付加するためのハロゲン系もしくはリン酸系の難燃性剤、アンチモン系化合物やホウ酸亜鉛・メタホウ酸バリウム・酸化ジルコニウム等の難燃助剤、潤滑性を改善するための高級脂肪酸や高級脂肪酸エステルや高級脂肪酸金属塩・フルオロカーボン系界面活性剤等の滑剤、熱膨張係数や収縮率を調整したり機械的強度を向上するための酸化アルミニウムや酸化珪素・酸化チタン・酸化バリウム・酸化ストロンチウム・酸化ジルコニウム・酸化カルシウム・ゼオライト・窒化珪素・窒化アルミニウム・炭化珪素・チタン酸カリウム・チタン酸バリウム・チタン酸ストロンチウム・チタン酸カルシウム・ホウ酸アルミニウム・スズ酸バリウム・ジルコン酸バリウム・ジルコン酸ストロンチウム等の充填材、あるいは、充填材との親和性を高めこれらの接合性向上と機械的強度を高めるためのシラン系カップリング剤やチタネート系カップリング剤等のカップリング剤を含有してもよい。
【００５７】
特に絶縁フィルム３を積層・加圧して多層配線基板６を形成する際に、被覆層２の流動性や加熱プレスによる収縮を抑制し、貫通導体５の位置ずれや被覆層２の厚みばらつきを防止するという観点からは、被覆層２は充填材として１０体積％以上の無機絶縁粉末を含有することが好ましい。また、液晶ポリマー層１との接着界面および配線導体４との接着界面での半田リフロー時の剥離を防止するという観点からは、無機絶縁粉末の含有量を７０体積％以下とすることが好ましい。したがって、熱硬化性樹脂から成る被覆層２は１０〜７０体積％の無機絶縁粉末を含有させておくことが好ましい。
【００５８】
なお、上記の無機絶縁粉末の形状は、略球状・針状・フレーク状等があり、充填性や熱膨張係数および収縮率の均一性の観点からは、粒子径が０．１〜２μｍであって、形状は略球状であることが好ましい。
【００５９】
このような絶縁フィルム３は、例えば粒径が０．１〜２μｍ程度の酸化珪素等の無機絶縁粉末に、熱硬化性ポリフェニレンエーテル樹脂と溶剤・可塑剤・分散剤等を添加して得たペーストを、プラズマ処理により水との接触角が３〜６５°であって、かつ表面エネルギーが４５〜８０ｍＪ／ｍ２となるように表面処理した、融点が２３０〜４２０℃の液晶ポリマー層１の上下面に従来周知のドクタブレード法等のシート成型法を採用して被覆層２を形成した後、あるいは上記のペースト中に液晶ポリマー層１を浸漬し垂直に引き上げることによって液晶ポリマー層１の表面に被覆層２を形成した後、これを６０〜１００℃の温度で５分〜３時間加熱・乾燥することにより製作される。
【００６０】
なお、絶縁フィルム３の厚みは絶縁信頼性を確保するという観点からは１０〜３００μｍであることが好ましく、また、高耐熱性・低吸湿性・高寸法安定性を確保するという観点からは液晶ポリマー層１の厚みを絶縁フィルム３の厚みの４０〜９０％の範囲としておくことが好ましい。
【００６１】
また、本発明の多層配線基板６は、上下面の少なくとも一方の面に金属箔から成る配線導体４が配設された絶縁フィルム３を複数積層して成るとともに、この絶縁フィルム３を挟んで上下に位置する配線導体４間を絶縁フィルム３に形成された貫通導体５を介して電気的に接続することにより形成されている。
【００６２】
配線導体４は、その厚みが２〜３０μｍで銅・金等の良導電性の金属箔から成り、多層配線基板６に搭載される電子部品７を外部電気回路（図示せず）に電気的に接続する機能を有する。
【００６３】
このような配線導体４は、絶縁フィルム３を複数積層する際、配線導体４の周囲にボイドが発生するのを防止するという観点からは、図３の要部拡大断面図に示すように、被覆層２に少なくとも配線導体４の表面と被覆層２の表面とが平坦となるように埋設されていることが好ましい。また、配線導体４を被覆層２に埋設する際に、被覆層２の乾燥状態での気孔率を３〜４０体積％としておくと、配線導体４周囲の被覆層２の樹脂盛り上がりを生じさせず平坦化することができるとともに配線導体４と被覆層２の間に挟まれる空気の排出を容易にして気泡の巻き込みを防止することができる。なお、乾燥状態での気孔率が４０体積％を超えると、複数積層した絶縁フィルム３を加圧・加熱硬化した後に被覆層２内に気孔が残存し、この気孔が空気中の水分を吸着して絶縁性が低下してしまうおそれがあるので、被覆層２の乾燥状態での気孔率を３〜４０体積％の範囲としておくことが好ましい。
【００６４】
このような被覆層２の乾燥状態での気孔率は、被覆層２を液晶ポリマー層１の表面上に塗布し乾燥する際に、乾燥温度や昇温速度等の乾燥条件を適宜調整することにより所望の値とすることができる。
【００６５】
さらに、絶縁フィルム３に配設された配線導体４の幅方向の断面形状を、絶縁フィルム３側の底辺の長さが対向する底辺の長さよりも短い台形状とするとともに、絶縁フィルム３側の底辺と側辺との成す角度を９５〜１５０°とすることが好ましい。絶縁フィルム３に配設された配線導体４の幅方向の断面形状を、絶縁フィルム３側の底辺の長さが対向する底辺の長さよりも短い台形状とするとともに、絶縁フィルム３側の底辺と側辺との成す角度を９５〜１５０°とすることにより、配線導体４を被覆層２に埋設する際に、配線導体４を被覆層２に容易に埋設して配線導体４を埋設した後の被覆層２表面をほぼ平坦にすることができ、積層の際に空気をかみ込んで絶縁性を低下させることのない多層配線基板６とすることができる。なお、気泡をかみ込むことなく埋設するという観点からは、絶縁フィルム３側の底辺と側辺との成す角度を９５°以上とすることが好ましく、配線導体２を微細化するという観点からは１５０°以下とすることが好ましい。
【００６６】
また、絶縁フィルム３の層間において、配線導体４の長さの短い底辺と液晶ポリマー層１との間に位置する被覆層２の厚みｘ（μｍ）が、上下の液晶ポリマー層１間の距離をＴ（μｍ）、配線導体４の厚みをｔ（μｍ）としたときに、３μｍ≦０．５Ｔ−ｔ≦ｘ≦０．５Ｔ≦３５μｍ（ただし、８μｍ≦Ｔ≦７０μｍ、１μｍ≦ｔ≦３２μｍ）であることが好ましい。
【００６７】
液晶ポリマー層１間の距離をＴ（μｍ）、配線導体４の厚みをｔ（μｍ）としたときに、配線導体４の長さの短い底辺と液晶ポリマー層１間の熱硬化性樹脂から成る被覆層２の厚みｘ（μｍ）を３μｍ≦０．５Ｔ−ｔ≦ｘ≦０．５Ｔ≦３５μｍとすることにより、配線導体４の長さの短い底辺と液晶ポリマー層１間の距離および配線導体４の長さの長い底辺と隣接する液晶ポリマー層１間の距離の差をｔ（μｍ）未満と小さくすることができ、被覆層２の厚みが大きく異なることから生じる多層配線基板６の反りを防止することができる。したがって、配線導体４の台形状の上底側表面と液晶ポリマー層１の間に位置する、被覆層２の厚みｘ（μｍ）を、液晶ポリマー層１間の距離をＴ（μｍ）、配線導体４の厚みをｔ（μｍ）としたときに、３μｍ≦０．５Ｔ−ｔ≦ｘ≦０．５Ｔ≦３５μｍの範囲とすることが好ましい。
【００６８】
このような配線導体４は、絶縁フィルム３となる前駆体シートに、公知のフォトレジストを用いたサブトラクティブ法によりパターン形成した、例えば銅から成る金属箔を転写法等により被着形成することにより形成される。先ず、支持体と成るフィルム上に銅から成る金属箔を接着剤を介して接着した金属箔転写用フィルムを用意し、次に、フィルム上の金属箔を公知のフォトレジストを用いたサブトラクティブ法を使用してパターン状にエッチングする。この時、パターンの表面側の側面は、フィルム側の側面に較べてエッチング液に接する時間が長いためにエッチングされやすく、パターンの幅方向の断面形状を台形状とすることができる。なお、台形の形状は、エッチング液の濃度やエッチング時間を調整することにより短い底辺と側辺とのなす角度を９５〜１５０°の台形状とすることができる。
【００６９】
そして、この金属箔転写用フィルムを絶縁フィルム３と成る前駆体シートに積層し、温度が１００〜２００℃で圧力が０．５〜１０ＭＰａの条件で１０分〜１時間ホットプレスした後、支持体と成るフィルムを剥離除去して金属箔を絶縁フィルム３と成る前駆体シート表面に転写させることにより、台形状の上底側が被覆層２に埋設された配線導体４を形成することができる。
【００７０】
なお、配線導体４の長さの短い底辺と対向する液晶ポリマー層１間の被覆層２の厚みｘ（μｍ）は、金属箔転写時のホットプレスの圧力を調整することにより所望の範囲とすることができる。また、配線導体４は被覆層２との密着性を高めるためにその表面にバフ研磨・ブラスト研磨・ブラシ研磨・薬品処理等の処理で表面を粗化しておくことが好ましい。
【００７１】
また、絶縁フィルム３には、直径が２０〜１５０μｍ程度の貫通導体５が形成されている。貫通導体５は、絶縁フィルム３を挟んで上下に位置する配線導体４を電気的に接続する機能を有し、絶縁フィルム３にレーザにより穿設加工を施すことにより貫通孔を形成した後、この貫通孔に銅・銀・金・半田等から成る導電性ペーストを従来周知のスクリーン印刷法により埋め込むことにより形成される。
【００７２】
本発明の多層配線基板６によれば、絶縁フィルム３を液晶ポリマー層１の上下面に熱硬化性樹脂から成る被覆層２を有したものとしたことから、液晶ポリマー層１が高耐熱性・高弾性率・高寸法安定性・低吸湿性であり、ガラスクロスのような強化材を用いなくとも絶縁フィルム３を構成することが可能となり、その結果、レーザによる穿設加工が容易となり微細で均一な貫通孔を形成できる。
【００７３】
このような多層配線基板６は、上述したような方法で製作した絶縁フィルム３と成る前駆体シートの所望の位置に貫通導体５を形成した後、パターン形成した例えば銅の金属箔を、温度が１００〜２００℃で圧力が０．５〜１０ＭＰａの条件で１０分〜１時間ホットプレスして転写し、これらを積層して最終的に温度が１５０〜３００℃で圧力が０．５〜１０ＭＰａの条件で３０分〜２４時間ホットプレスして完全硬化させることにより製作される。
【００７４】
かくして本発明の多層配線基板６によれば、上記構成の多層配線基板６の上面に形成した配線導体４の一部から成る接続パッド８に半田等の導体バンプ８を介して半導体素子等の電子部品７を電気的に接続するとともに、多層配線基板６の下面に形成した配線導体４の一部から成る接続パッド８に半田等の導体バンプ９を形成することにより配線密度が高く絶縁性に優れた混成集積回路とすることができる。
【００７５】
なお、本発明の多層配線基板６は上述の実施例に限定されるものではなく、本発明の要旨を逸脱しない範囲であれば種々の変更は可能であり、例えば、上述の実施例では４層の絶縁フィルム３を積層することによって多層配線基板６を製作したが、２層や３層、あるいは５層以上の絶縁フィルム３を積層して多層配線基板６を製作してもよい。また、本発明の多層配線基板６の上下表面に、１層や２層、あるいは３層以上の有機樹脂を主成分とする絶縁層から成るビルドアップ層やソルダーレジスト層１０、あるいは多層配線基板６に電子部品７を搭載後、多層配線基板６と電子部品６との間にアンダーフィル材１１を形成してもよい。
【００７６】
【実施例】
次に本発明の絶縁フィルムおよびこれを用いた多層配線基板を、以下の試料を用いて評価した。
（実施例１）
先ず、熱硬化性ポリフェニレンエーテル樹脂に平均粒径が０．６μｍの球状溶融シリカをその含有量が４０体積％となるように加え、これに溶剤としてトルエン、さらに有機樹脂の硬化を促進させるための触媒を添加し、１時間混合してワニスを調整した。次に、融点が２９０℃であるとともに、かつ層方向における熱膨張係数が−３×１０−６〜１６×１０−６／℃の液晶ポリマー層の表面を、真空プラズマ装置を用いて、電圧を２７ｋＶ、雰囲気をＯ２およびＣＦ４（ガス流量をそれぞれ５０〜２００ｃｍ３／分の範囲で調整）とし、片面１５〜３５分の条件でプラズマ処理して、この液晶ポリマー層の上面に上記ワニスをドクターブレード法により塗布し、厚さが３０μｍの熱硬化性ポリフェニレンエーテル被覆層を成形した。そして、この液晶ポリマー層の下面にも同様に熱硬化性ポリフェニレンエーテル被覆層を成形し、上下面に平行な方向における種々の熱膨張係数と収縮率を有する絶縁フィルムを製作した。
【００７７】
さらに、この絶縁フィルムに、ＵＶ−ＹＡＧレーザにより直径５０μｍの貫通孔を形成し、この貫通孔に銅粉末と有機バインダを含有する導体ペーストをスクリーン印刷により埋め込むことにより貫通導体を形成した。
【００７８】
次に、厚さが９μｍで、回路状に形成した銅箔が付いた転写用支持フィルムと、貫通導体が形成された絶縁フィルムとを位置合わせして真空積層機により５ＭＰａの圧力で３０秒加圧した後、転写用支持フィルムを剥離して配線導体を絶縁フィルム上に埋設した。最後に、この配線導体が形成された絶縁フィルムを４枚重ね合わせ、３ＭＰａの圧力下で２００℃の温度で５時間加熱処理して完全硬化させて多層配線基板を得た（試料Ｎｏ．１〜１２）。
【００７９】
（比較例）
比較例用として用いた多層配線基板は、まず、表面に銅箔を熱溶融により接着した融点が３２０℃の液晶ポリマー層にフォトレジストを用いて回路状の配線導体を形成し、次に、ＵＶ−ＹＡＧレーザにより直径５０μｍの貫通孔を形成し、さらにこの貫通孔に銅粉末と有機バインダを含有する導体ペーストをスクリーン印刷により埋め込むことにより貫通導体を形成して回路基板を作製した後、これらの回路基板を融点が２８０℃の液晶ポリマー層を間に挟んで１ＭＰａの圧力下で２８５℃の温度で５分間加熱プレスすることにより製作した。
【００８０】
導通信頼性の評価を行なうためのテスト基板として、その内部に多層配線基板の絶縁層を介して位置する上下２層の配線導体と両者を電気的に接続する貫通導体とでビアチェーンを形成したものとし、導通信頼性の評価は、温度が１３０℃、相対湿度が８５％の条件で高温高湿試験を行ない、導通抵抗の試験前に対する変化率が１５％未満を良、１５％以上を否とした。表１に導通信頼性結果を示す。
【００８１】
【表１】

Figure 2004179011
【００８２】
表１からは、絶縁フィルムの層方向における熱膨張係数が３×１０−６／℃未満の多層配線基板（試料Ｎｏ．１）および熱膨張係数が４０×１０−６／℃を超える多層配線基板（試料Ｎｏ．６、７）では、高温高湿試験１６８時間後でも導通抵抗は変化率が１２％以下と小さいが、２４０時間後で導通抵抗は変化率が１６％以上と大きく、導通信頼性にやや劣る傾向があることがわかった。また、比較例の多層配線基板では、高温高湿試験１６８時間後でも導通抵抗は変化率が１９％と大きく劣化し導通信頼性に劣ることがわかった。
【００８３】
それらに対し、絶縁フィルムの上下面に平行な方向における熱膨張係数が３×１０−６〜４０×１０−６／℃の多層配線基板（試料Ｎｏ．２〜５）では、いずれも高温高湿試験１６８時間後で導通抵抗の変化率は１０％以下と小さく、さらに２４０時間後でも導通抵抗の変化率は１４％以下と小さく、導通信頼性に優れていた。しかし、熱膨張係数が３×１０−６〜４０×１０−６／℃であっても、絶縁フィルムの上下面に平行な方向における収縮率が０．１５％を超える多層配線基板（試料Ｎｏ．１１、１２）では、高温高湿試験１６８時間後でも導通抵抗は変化率が１３％以下と小さいが、２４０時間後で導通抵抗は変化率が１６％以上と大きく、導通信頼性にやや劣る傾向があった。
【００８４】
一方、絶縁フィルムの層方向における熱膨張係数が３×１０−６〜４０×１０−６／℃であり、かつ、絶縁フィルムの層方向における収縮率が０．１５％以下の多層配線基板（試料Ｎｏ．２〜５、８〜１０）では、高温高湿試験２４０時間後でも導通抵抗は変化率が１４％以下と小さく、導通信頼性において特に優れていることがわかった。
【００８５】
（実施例２）
実施例２用として用いた多層配線基板は、液晶ポリマー層を、その絶縁フィルムに対する厚さが種々の割合になるように変更した以外は、実施例１用の多層配線基板と同様の方法で製作した（試料Ｎｏ．１３〜１８）。なお、絶縁フィルムの厚さが２００μｍとなるように、液晶ポリマー層と被覆層の厚さを調整した。また、絶縁フィルムの上下面に平行な方向における熱膨張係数は３×１０−６〜４０×１０−６／℃の範囲にあり、さらに、１９０〜２７０℃の温度で２〜１８０分間加熱した際の上下面に平行な方向における収縮率は０．１５％以下であった。
【００８６】
絶縁性の評価を行なうためのテスト基板として、直径が４０００μｍの円形の導体パターンを多層配線基板内に絶縁層を挟んで対向するように形成し、絶縁信頼性の評価は、試料を温度が１３０℃、相対湿度が８５％の条件で、印加電圧５．５Ｖの高温バイアス試験を行ない、円形の導体パターン間の絶縁抵抗を測定し、試験前後の変化量を比較することにより評価した。絶縁信頼性の良否の判断は、絶縁抵抗が１．０×１０８Ω以上を良、１．０×１０８Ω未満を否とした。表２に絶縁信頼性結果を示す。
【００８７】
【表２】
Figure 2004179011
【００８８】
表２からは、液晶ポリマー層の絶縁フィルムに対する厚さの割合が４０％未満の多層配線基板（試料Ｎｏ．１３、１４）および９０％を超える多層配線基板（試料Ｎｏ．１８）では、高温バイアス試験１６８時間後の絶縁抵抗は良好であるものの、２４０時間以上では絶縁抵抗が８．８×１０７Ω以下と劣化する傾向にあることがわかった。
【００８９】
それらに対して本発明の多層配線基板である実施例（試料Ｎｏ．１５〜１７）では、高温バイアス試験２４０時間後でも２．１×１０８Ω以上であり、絶縁信頼性において特に優れていることがわかった。
【００９０】
（実施例３）
実施例３用として用いた多層配線基板は、表面が種々の水との接触角および表面エネルギーを有する液晶ポリマー層に変更した以外は、実施例１用の多層配線基板と同様の方法で製作した（試料Ｎｏ．１９〜２７）。
【００９１】
なお、密着性の評価は、多層配線基板を種々の温度の半田浴に２０秒間浸漬し、これを５回繰り返した後、多層配線基板の外観を観察することにより密着性の評価を行なった。表３に密着性の評価結果を示す。
【００９２】
【表３】
Figure 2004179011
【００９３】
表３からは、液晶ポリマー層表面の水との接触角が３°未満の多層配線基板（試料Ｎｏ．１９）および接触角が６５°を超える多層配線基板（試料Ｎｏ．２３）では、温度が２６０℃の半田浴への浸漬を５回繰り返しても多層配線基板の外観に変化は無かったが、温度条件の厳しい２９０℃の半田浴への浸漬を５回繰り返した時点で、液晶ポリマー層と被覆層間で剥がれを生じることにより多層配線基板に膨れ部が発生し、密着性にやや劣る傾向があった。それらに対し、接触角が３〜６５°の多層配線基板（試料Ｎｏ．２０〜２２）では、温度が２９０℃の半田浴への浸漬を５回繰り返しても多層配線基板の外観に変化は無く、密着性に優れていた。しかし、接触角が３〜６５°であっても、液晶ポリマー層の表面エネルギーが４５ｍＪ／ｍ２未満の多層配線基板（試料Ｎｏ．２４）および８０ｍＪ／ｍ２以上の多層配線基板（試料Ｎｏ．２７）では、温度が２６０℃の半田浴への浸漬を５回繰り返しても多層配線基板の外観に変化は無かったが、温度条件の厳しい２９０℃の半田浴への浸漬を５回繰り返した時点で、液晶ポリマー層と被覆層間で剥がれを生じることにより多層配線基板に膨れ部が発生し、密着性にやや劣る傾向があった。一方、接触角が３〜６５°であり、かつ、表面エネルギーが４５〜８０ｍＪ／ｍ２の多層配線基板（試料Ｎｏ．２０〜２２、２５、２６）では、温度が２９０℃の半田浴への浸漬を５回繰り返しても多層配線基板の外観に変化は無く、密着性において特に優れていることがわかった。
【００９４】
【発明の効果】
本発明の絶縁フィルムによれば、絶縁フィルムを液晶ポリマー層の上下面に熱硬化性樹脂から成る被覆層を有する構成とし、層方向における熱膨張係数を３×１０−６〜４０×１０−６／℃としたことから、この絶縁フィルムを用いて配線基板を製作した場合、絶縁フィルムの熱膨張係数が配線導体の熱膨張係数に近似し、絶縁フィルムと配線導体との熱膨張差による応力を小さなものとすることができ、その結果、高温高湿下で絶縁フィルムと配線導体間で剥離したり、温度サイクル試験で絶縁フィルムにクラックが発生して配線導体が断線してしまうことがない。また、熱硬化性樹脂の分子が液晶ポリマー分子ほど剛直ではなく、また、規則正しい配向性も示さないことから分子が比較的動きやすく、その結果、絶縁フィルムを多層化した場合においても、絶縁フィルム同士の密着性が良好となり、高温バイアス試験において絶縁フィルム間で剥離して絶縁不良が発生してしまうこともない。さらに、絶縁フィルム表面に配線導体を配設した場合においても、熱硬化性樹脂の分子が配線導体表面の微細な凹部に入り込み十分なアンカー効果を発揮することができ、絶縁フィルムと配線導体との密着性が良好となり、その結果、高温高湿下で両者間で剥離して配線導体が断線してしまうということもない。また、１９０〜２７０℃の温度で２〜１８０分間加熱した際の層方向における収縮率を０．１５％以下としたことから、絶縁フィルムに配線導体および貫通導体を配設するとともに絶縁フィルムを多層化して多層配線基板を製作する場合においても、多層化する際の加熱プレスによって絶縁フィルムの層方向における貫通導体の位置精度が低下したり、貫通導体の直径にばらつきが生じることもなく、その結果、配線導体と貫通導体との導通信頼性に優れた多層配線基板を製作することができる。
【００９５】
また、本発明の絶縁フィルムによれば、上記構成において、液晶ポリマー層の厚みを絶縁フィルムの厚みの４０〜９０％とした場合には、温度サイクル試験等の際に絶縁フィルムに熱応力が印加されたとしても、小さな熱膨張係数と小さな収縮率を有する液晶ポリマー層が大きな熱膨張係数と大きな収縮率を有する被覆層を良好に拘束して絶縁フィルム全体の熱膨張や収縮を小さなものとすることができる。
【００９６】
さらに、本発明の絶縁フィルムによれば、上記構成において、液晶ポリマー層を水との接触角が３〜６５°であって、かつ表面エネルギーが４５〜８０ｍＪ／ｍ２とした場合には、液晶ポリマー層表面の活性化された比較的熱運動しやすい分子層と熱硬化性樹脂から成る被覆層とが良好に絡み合って結合し、液晶ポリマー層と被覆層とがより強固に密着した絶縁フィルムとすることができる。
【００９７】
また、本発明の絶縁フィルムによれば、上記構成において、液晶ポリマー層の上下面の算術平均粗さＲａを０．０５〜５μｍとした場合には、液晶ポリマー層の上下面が熱硬化性樹脂から成る被覆層と良好なアンカー効果を有する密着性の良好なものとなり、液晶ポリマー層と被覆層とがより強固に密着した絶縁フィルムとすることができる。
【００９８】
また、本発明の絶縁フィルムによれば、上記構成において、被覆層を粒子径が０．１〜２μｍの無機絶縁粉末を１０〜７０体積％含有するものとした場合には、絶縁フィルムに配線導体および貫通導体を配設するとともに絶縁フィルムを多層化して多層配線基板を製作する場合においても、無機絶縁粉末が被覆層の流動性や加熱プレスによる収縮を抑制し、多層化する際の加熱プレスによって層方向における貫通導体の位置ずれや貫通導体の直径のばらつき、さらには被覆層の厚みばらつきを低減することができ、より寸法安定性に優れた絶縁フィルムとすることができる。
【００９９】
さらに、本発明の絶縁フィルムによれば、上記構成において、無機絶縁粉末の形状を略球状とした場合には、無機絶縁粉末を熱硬化性樹脂へ充填する際に充填性や混練性が良好となり、無機絶縁粉末を熱硬化性樹脂から成る被覆層へ一様に分布させることができ、その結果、被覆層の熱膨張係数や収縮率がより均一な絶縁フィルムとすることができる。
【０１００】
また、本発明の絶縁フィルムによれば、上記構成において、熱硬化性樹脂を熱硬化性ポリフェニレンエーテルとした場合には、熱硬化性ポリフェニレンエーテルが耐熱性に優れるとともに寸法安定性に優れることから、温度サイクル信頼性に優れるとともに、配線導体を接着する際の位置精度の良好な絶縁フィルムとすることができる。
【０１０１】
本発明の多層配線基板によれば、多層配線基板を上記の絶縁フィルムを用いて形成したことから、耐湿性・導通信頼性に優れた多層配線基板とすることができる。
【図面の簡単な説明】
【図１】本発明の絶縁フィルムの実施の形態の一例を示す断面図である。
【図２】本発明の多層配線基板の実施の形態の一例を示す断面図である。
【図３】図２に示す多層配線基板の要部拡大断面図である。
【符号の説明】
１・・・・・・・・液晶ポリマー層
２・・・・・・・・被覆層
３・・・・・・・・絶縁フィルム
４・・・・・・・・配線導体
５・・・・・・・・貫通導体
６・・・・・・・・多層配線基板[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an insulating film used for electronic devices such as various AV devices, home appliances, communication devices, computers and peripheral devices thereof, and a multilayer wiring board using the same, particularly an insulating film partially using a liquid crystal polymer. And a multilayer wiring board using the same.
[0002]
[Prior art]
Conventionally, a multi-layer wiring board for forming a hybrid integrated circuit in which a predetermined electronic circuit is formed by mounting a large number of active parts such as semiconductor elements and passive parts such as capacitance elements and resistance elements is usually made of epoxy resin on glass cloth. Are formed by drilling up and down through holes in an insulating film impregnated with, and a plurality of wiring boards having a plurality of wiring conductors formed inside the through holes and on the surface of the insulating layer.
[0003]
In general, modern electronic devices are required to be small, thin, lightweight, high-performance, high-performance, high-quality, and high-reliable, as represented by mobile communication devices. Electronic components such as hybrid integrated circuits are also required to be smaller and have higher densities. In order to respond to such demands for higher densities, multilayer wiring boards that make up electronic components have also been required to have wiring conductors. It has become necessary to reduce the size of insulating layers, to make insulating layers thinner, and to make through holes finer. For this reason, in recent years, in order to miniaturize the through holes, laser processing that can perform finer processing than drill processing has been used.
[0004]
However, an insulating film formed by impregnating a glass cloth with an epoxy resin has difficulty in making the glass cloth with a laser, so there is a limit to miniaturization of the through-hole, and the thickness of the glass cloth is not sufficient. There is a problem that it is difficult to form a through hole having a uniform diameter for uniformity.
[0005]
In order to solve such problems, an insulating film formed by impregnating a non-woven fabric made of aramid resin fiber with an epoxy resin, or an insulating film formed by applying an epoxy-based adhesive to a polyimide film was used as an insulating layer. A multilayer wiring board has been proposed.
[0006]
However, insulating films using aramid nonwoven fabric or polyimide film have high hygroscopicity, and when solder reflow is performed in a state of moisture absorption, the moisture absorbed by the heat of the solder reflow is vaporized to generate gas, which is separated between the insulating layers. There was a problem such as getting lost.
[0007]
In order to solve such problems, use of a liquid crystal polymer as a material for an insulating layer of a multilayer wiring board has been studied. The layer composed of liquid crystal polymer is composed of rigid molecules and has a structure in which the molecules are regularly arranged to some extent. Since the intermolecular force is strong, it has high heat resistance, high elastic modulus, and high dimensional stability. -It has low hygroscopicity, does not require the use of a reinforcing material such as glass cloth, and has excellent features of fine workability. Further, it has a characteristic that it has a low dielectric constant and a low dielectric loss tangent and is excellent in high frequency characteristics even in a high frequency region.
[0008]
Utilizing such characteristics of the liquid crystal polymer, JP-A-8-97565 discloses that a circuit layer contains a first liquid crystal polymer, and a second layer having a melting point lower than the melting point of the first liquid crystal polymer between the circuit layers. There has been proposed a multilayer printed circuit board formed by inserting an adhesive layer containing a liquid crystal polymer.
[0009]
[Patent Document 1]
JP-A-8-97565
[0010]
[Problems to be solved by the invention]
However, in the multilayer printed circuit board proposed in Japanese Patent Application Laid-Open No. H8-97565, the liquid crystal polymer molecules are rigid when the circuit layers are bonded by thermocompression bonding by inserting an adhesive layer containing a liquid crystal polymer therebetween. At the same time, molecules are regularly oriented to some extent and the intermolecular force is strengthened, making it difficult for the molecules to move, and only a small part of the surface of the liquid crystal polymer in the circuit layer and the liquid crystal polymer in the adhesive layer can be entangled. In addition, there is a problem that the adhesion between the layers is poor, and the layers are peeled off in a high-temperature bias test to cause insulation failure.
[0011]
In addition, when the conductor foil of the circuit layer and the liquid crystal polymer are bonded by heat fusion, the liquid crystal polymer molecules are difficult to move and cannot enter the fine recesses on the conductor foil surface, resulting in a sufficient anchor effect. In addition, the adhesion between the conductor foil and the liquid crystal polymer is deteriorated, and the conductor foil is peeled off under high temperature and high humidity to cause a disconnection of the conductor foil.
[0012]
The present invention has been made in view of the problems of the related art, and an object of the present invention is to provide an insulating film having excellent insulating properties and conduction reliability and a multilayer wiring board using the same.
[0013]
[Means for Solving the Problems]
The insulating film of the present invention has a coating layer made of a thermosetting resin on the upper and lower surfaces of a liquid crystal polymer layer, and has a thermal expansion coefficient of 3 × 10 in the layer direction. -6 ~ 40 × 10 -6 / ° C and a shrinkage ratio in the layer direction of 0.15% or less when heated at a temperature of 190 to 270 ° C for 2 to 180 minutes.
[0014]
According to the insulating film of the present invention, the insulating film has a coating layer made of a thermosetting resin on the upper and lower surfaces of the liquid crystal polymer layer, and has a thermal expansion coefficient of 3 × 10 in the layer direction of the insulating film. -6 ~ 40 × 10 -6 / ° C, when a wiring board is manufactured using this insulating film, the coefficient of thermal expansion of the insulating film approximates the coefficient of thermal expansion of the wiring conductor, and the stress due to the difference in thermal expansion between the insulating film and the wiring conductor is reduced. As a result, the insulating film and the wiring conductor do not peel under high temperature and high humidity, and the wiring conductor does not break due to cracks in the insulating film in a temperature cycle test. In addition, since the molecules of the thermosetting resin are not as rigid as liquid crystal polymer molecules and do not show regular orientation, the molecules are relatively easy to move. And the adhesion between the insulating films does not occur in the high-temperature bias test, thereby preventing insulation failure. Furthermore, even when the wiring conductor is provided on the surface of the insulating film, the molecules of the thermosetting resin can enter the fine recesses on the surface of the wiring conductor and exert a sufficient anchor effect, and the connection between the insulating film and the wiring conductor can be achieved. Adhesion is improved, and as a result, there is no possibility that the wiring conductor is disconnected due to separation between the two under high temperature and high humidity. In addition, since the shrinkage in the layer direction when heated at a temperature of 190 to 270 ° C. for 2 to 180 minutes is set to 0.15% or less, the wiring conductor and the through conductor are provided on the insulating film, and the insulating film is multilayered. In the case of manufacturing a multilayer wiring board by making it into a multilayer, the heat press at the time of forming the multilayer does not reduce the positional accuracy of the through conductor in the layer direction of the insulating film or cause a variation in the diameter of the through conductor, and as a result, Thus, it is possible to manufacture a multilayer wiring board having excellent conduction reliability between the wiring conductor and the through conductor.
[0015]
Further, the insulating film of the present invention is characterized in that, in the above configuration, the thickness of the liquid crystal polymer layer is 40 to 90% of the thickness of the insulating film.
[0016]
According to the insulating film of the present invention, in the above configuration, when the thickness of the liquid crystal polymer layer is 40 to 90% of the thickness of the insulating film, thermal stress is applied to the insulating film during a temperature cycle test or the like. Even if the liquid crystal polymer layer having a small coefficient of thermal expansion and a small shrinkage rate can well restrain the coating layer having a large coefficient of thermal expansion and a large shrinkage rate, the thermal expansion and shrinkage of the entire insulating film can be reduced. it can.
[0017]
Furthermore, the insulating film of the present invention, in the above configuration, has a contact angle of water of the liquid crystal polymer layer of 3 to 65 ° and a surface energy of 45 to 80 mJ / m. 2 It is characterized by being.
[0018]
According to the insulating film of the present invention, in the above configuration, the liquid crystal polymer layer has a contact angle with water of 3 to 65 ° and a surface energy of 45 to 80 mJ / m. 2 In this case, the activated molecular layer on the surface of the liquid crystal polymer layer which is relatively easily moved by heat and the coating layer made of a thermosetting resin are entangled and bonded well, and the liquid crystal polymer layer and the coating layer become more An insulating film that is tightly adhered can be obtained.
[0019]
Further, the insulating film of the present invention is characterized in that, in the above configuration, the arithmetic average roughness Ra of the upper and lower surfaces of the liquid crystal polymer layer is 0.05 to 5 μm.
[0020]
According to the insulating film of the present invention, when the arithmetic average roughness Ra of the upper and lower surfaces of the liquid crystal polymer layer is set to 0.05 to 5 μm in the above configuration, the upper and lower surfaces of the liquid crystal polymer layer are made of a thermosetting resin. Good adhesion with the coating layer and good anchoring effect is obtained, and an insulating film in which the liquid crystal polymer layer and the coating layer are more firmly adhered can be obtained.
[0021]
Further, the insulating film of the present invention is characterized in that, in the above configuration, the coating layer contains 10 to 70% by volume of an inorganic insulating powder having a particle diameter of 0.1 to 2 μm.
[0022]
According to the insulating film of the present invention, in the above structure, when the coating layer contains 10 to 70% by volume of an inorganic insulating powder having a particle size of 0.1 to 2 μm, the insulating film has a wiring conductor and a penetrating hole. Even in the case where a conductor is arranged and the insulating film is multilayered to produce a multilayer wiring board, the inorganic insulating powder suppresses the fluidity of the coating layer and shrinkage due to the heat press, and the layer direction is controlled by the heat press when forming the multilayer. In this case, the displacement of the through conductor, the variation in the diameter of the through conductor, and the variation in the thickness of the coating layer can be reduced, and an insulating film having more excellent dimensional stability can be obtained.
[0023]
Furthermore, the insulating film of the present invention is characterized in that, in the above configuration, the shape of the inorganic insulating powder is substantially spherical.
[0024]
According to the insulating film of the present invention, in the above configuration, when the shape of the inorganic insulating powder is substantially spherical, the filling property and the kneading property become good when the inorganic insulating powder is filled into the thermosetting resin. The insulating powder can be uniformly distributed on the coating layer made of the thermosetting resin, and as a result, an insulating film having a more uniform thermal expansion coefficient and contraction rate of the coating layer can be obtained.
[0025]
Further, the insulating film of the present invention is characterized in that, in the above configuration, the thermosetting resin is a thermosetting polyphenylene ether.
[0026]
According to the insulating film of the present invention, in the above configuration, when the thermosetting resin is thermosetting polyphenylene ether, the thermosetting polyphenylene ether has excellent heat resistance and excellent dimensional stability, so that the temperature cycle An insulating film having excellent reliability and good positional accuracy when bonding the wiring conductor can be obtained.
[0027]
The multilayer wiring board of the present invention is formed by laminating a plurality of the above-mentioned insulating films in which wiring conductors made of metal foil are disposed on at least one of the upper and lower surfaces, and the wirings located above and below the insulating film. The invention is characterized in that the conductors are electrically connected via a through conductor formed in the insulating film.
[0028]
According to the multilayer wiring board of the present invention, since the multilayer wiring board is formed using the insulating film, a multilayer wiring board having excellent moisture resistance and conduction reliability can be obtained.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an insulating film of the present invention and a multilayer wiring board using the same will be described in detail with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view showing an example of an embodiment of the insulating film of the present invention. FIG. 2 is a cross-sectional view showing an example of an embodiment of the multilayer wiring board of the present invention manufactured using the insulating film of FIG. FIG. FIG. 2 shows an example in which electronic components such as semiconductor elements are mounted on a multilayer wiring board of the present invention to form a hybrid integrated circuit. FIG. 3 is an enlarged cross-sectional view of a main part of the wiring conductor of the multilayer wiring board shown in FIG. 2 in the width direction.
[0030]
In these figures, 1 is a liquid crystal polymer layer, 2 is a coating layer made of a thermosetting resin, and these mainly constitute the insulating film 3 of the present invention. Reference numeral 4 denotes a wiring conductor, 5 denotes a through conductor, and 7 denotes an electronic component such as a semiconductor element. The multilayer wiring board 6 of the present invention mainly includes the insulating film 3, the wiring conductor 4, and the through conductor 5. In addition, the multilayer wiring board 6 of the present embodiment shows a structure in which the insulating films 3 are laminated in four layers.
[0031]
The insulating film 3 is composed of a liquid crystal polymer layer 1 and a coating layer 2 made of a thermosetting resin which is formed on the upper and lower surfaces thereof. It has a function as a support of the conductor 4 and the electronic component 7 mounted on the multilayer wiring board 6.
[0032]
Here, the liquid crystal polymer refers to a polymer exhibiting liquid crystallinity or a polymer having an optically birefringent property in a molten state or a solution state, and is generally a lyotropic liquid crystal polymer exhibiting liquid crystallinity in a solution state or a liquid crystal polymer in a molten state. The liquid crystal polymer used in the present invention includes a thermotropic liquid crystal polymer exhibiting the property, or a liquid crystal polymer of all types 1, 2, and 3 classified by heat distortion temperature. From the viewpoints of heat resistance and workability, those having a melting point at a temperature of 230 to 420 ° C, particularly 270 to 380 ° C are preferable.
[0033]
When the insulating film 3 is used to manufacture the multilayer wiring board 6, the thermal expansion coefficient of the insulating film 3 is close to that of the wiring conductor 4, and the insulation film 3 is resistant to peeling of the insulating film 3 from the wiring conductor 4 and cracking of the insulating film 3. From the viewpoint of increasing the thermal expansion coefficient, the coefficient of thermal expansion in the direction parallel to the upper and lower surfaces, that is, in the layer direction, is 3 × 10 -6 ~ 40 × 10 -6 / ° C is important.
[0034]
In addition, from the viewpoint of preventing the positioning accuracy of the through conductor 5 in the layer direction of the insulating film 3 from being lowered or the diameter of the through conductor 5 from being varied due to the heating press at the time of forming the insulating film 3 into a multilayer. The shrinkage in the layer direction when heated at a temperature of 190 to 270 ° C. for 2 to 180 minutes must be 0.15% or less, and this is important for the insulating film 3 of the present invention.
[0035]
According to the insulating film 3 of the present invention, the thermal expansion coefficient in the layer direction of the insulating film 3 is 3 × 10 -6 ~ 40 × 10 -6 / ° C., when the wiring board 6 is manufactured using the insulating film 3, the coefficient of thermal expansion of the insulating film 3 approximates the coefficient of thermal expansion of the wiring conductor 4, and the The stress due to the difference in thermal expansion can be reduced, and as a result, the insulating film 3 and the wiring conductor 4 are peeled off under high temperature and high humidity, or the insulating film 3 is cracked by a temperature cycle test to cause the wiring conductor to fail. 4 does not break.
[0036]
In addition, since the molecules of the thermosetting resin are not as rigid as liquid crystal polymer molecules and do not show regular orientation, the molecules are relatively easy to move. As a result, even when the insulating films 3 are multilayered, the insulating films 3 And the adhesion between the insulating films 3 in the high-temperature bias test does not occur to cause insulation failure.
[0037]
Furthermore, even when the wiring conductor 4 is provided on the surface of the insulating film 3, molecules of the thermosetting resin can enter the minute recesses on the surface of the wiring conductor 4 and exhibit a sufficient anchor effect, and Adhesion with the wiring conductor 4 is improved, and as a result, there is no possibility that the wiring conductor 4 is disconnected due to separation between the two under high temperature and high humidity.
[0038]
Also, since the shrinkage in the direction parallel to the upper and lower surfaces of the insulating film 3 when heated at a temperature of 190 to 270 ° C. for 2 to 180 minutes is set to 0.15% or less, the wiring conductor 4 and the Even when the conductor 5 is provided and the insulating film 3 is multilayered to produce the multilayer wiring board 6, the positional accuracy of the through conductor 5 in a direction parallel to the upper and lower surfaces of the insulating film 3 by the heat press during the multilayering. Thus, the multilayer wiring board 6 having excellent conduction reliability between the wiring conductor 4 and the through conductor 5 can be manufactured.
[0039]
Note that the thermal expansion coefficient of the insulating film 3 is 3 × 10 -6 When the temperature is less than / ° C, the thermal expansion coefficient of the insulating film 3 becomes too small compared to the wiring conductor 4 and the insulating film 3 tends to peel off easily from the wiring conductor 4. -6 If the temperature exceeds / ° C., the thermal expansion coefficient of the insulating film 3 becomes too large as compared with that of the wiring conductor 4, and the insulating film 3 tends to crack due to a difference in thermal expansion. Therefore, the insulating film 3 has a thermal expansion coefficient in the layer direction of 3 × 10 -6 ~ 40 × 10 -6 / ° C is important.
[0040]
If the shrinkage in the layer direction of the insulating film 3 when heated at a temperature of 190 to 270 ° C. for 2 to 180 minutes exceeds 0.15%, the positional accuracy of the through conductor 5 in the direction parallel to the upper and lower surfaces decreases. In addition, it is difficult to prevent variations in the diameter of the through conductor 5 and the resistance of the through conductor 5 tends to increase under high temperature and high humidity. Therefore, it is important that the shrinkage in the layer direction when the insulating film 3 is heated at a temperature of 190 to 270 ° C. for 2 to 180 minutes is 0.15% or less. Furthermore, when the multilayer wiring board 6 is manufactured by laminating four or more layers of the insulating film 3, from the viewpoint of the conduction reliability of the through conductor 5 under high temperature and high humidity, it is more preferable to set it to 0.1% or less. preferable.
[0041]
Here, the shrinkage in the layer direction when the insulating film 3 is heated at a temperature of 190 to 270 ° C. for 2 to 180 minutes means that only the insulating film 3 is heated at an arbitrary temperature of 190 to 270 ° C. for 3 to 180 minutes. When heated in the range, it means a value obtained by dividing the amount of dimensional change between any two points in the layer direction by the size before heating, and is quantifiable. The shrinkage can be adjusted by appropriately adjusting the pressure and the rate of temperature rise when the liquid crystal polymer layer 1 is manufactured by the biaxial stretching method or the inflation method, and when the coating layer 2 is formed on the upper and lower surfaces of the liquid crystal polymer layer 1. By appropriately adjusting the surface treatment atmosphere and time of the liquid crystal polymer layer 1, the temperature and time for heating and drying the coating layer 2 after forming the coating layer 2 on the upper and lower surfaces of the liquid crystal polymer layer 1 are further adjusted. A desired value can be obtained by appropriately adjusting.
[0042]
The liquid crystal polymer layer 1 is provided with a light stabilizer such as an antioxidant for improving thermal stability and an ultraviolet absorber for improving light resistance, as long as the physical properties of the layer are not impaired. Halogen or phosphoric acid-based flame retardants to add water, flame retardant aids such as antimony compounds and zinc borate / barium metaborate / zirconium oxide, higher fatty acids and higher fatty acids to improve lubricity Lubricants such as esters, higher fatty acid metal salts, fluorocarbon surfactants, and the like, aluminum oxide, silicon oxide, titanium oxide, barium oxide, for adjusting the coefficient of thermal expansion and shrinkage and / or improving mechanical strength. Strontium oxide, zirconium oxide, calcium oxide, zeolite, silicon nitride, aluminum nitride, silicon carbide, potassium titanate, barium titanate It may contain fillers such as Tan strontium-calcium titanate, aluminum borate, barium stannate, barium zirconate, strontium zirconate.
[0043]
In addition, the particle shape of the above-mentioned filler and the like includes a substantially spherical shape, a needle shape, a flake shape and the like, and a substantially spherical shape is preferable from the viewpoint of the filling property. The particle size is usually about 0.1 to 15 μm, which is smaller than the thickness of the liquid crystal polymer layer 1.
[0044]
In addition, the thickness of the liquid crystal polymer layer 1 is such that the liquid crystal polymer layer 1 having a small coefficient of thermal expansion and a small shrinkage rate satisfactorily constrains the coating layer 2 having a large coefficient of thermal expansion and a large shrinkage rate, and From the viewpoint of reducing expansion and contraction, it is preferable to set the thickness to 40 to 90% of the thickness of the insulating film 3.
[0045]
If the thickness of the liquid crystal polymer layer 1 is less than 40% of the thickness of the insulating film 3, it becomes difficult for the liquid crystal polymer layer 1 to restrain the thermal expansion and contraction of the coating layer 2. When the substrate 6 is manufactured, the thermal expansion coefficient and the contraction rate of the insulating film 3 become larger than the value of the wiring conductor 4, and cracks are easily generated in the insulating film 3 due to the stress due to the difference in thermal expansion and contraction. There is a tendency. If the thickness of the liquid crystal polymer layer 1 exceeds 90%, the effect of the thermal expansion of the coating layer 2 contributing to the thermal expansion of the insulating film 3 becomes small, and the thermal expansion coefficient of the insulating film 3 becomes smaller than that of the wiring conductor 4. The thermal expansion difference tends to cause the peeling of the wiring conductor 4 easily. Therefore, the thickness of the liquid crystal polymer layer 1 is preferably set to 40 to 90% of the thickness of the insulating film 3, and particularly from the viewpoint of connection reliability when the multilayer wiring board 6 is manufactured and the electronic components 7 are mounted. It is preferable to set the range to 85%.
[0046]
The liquid crystal polymer layer 1 uses a method such as buffing, blasting, brushing, plasma treatment, corona treatment, ultraviolet treatment, or chemical treatment to improve the adhesion to the coating layer 2. The contact angle with water is 3 to 65 ° and the surface energy is 45 to 80 mJ / m 2 It is preferable to perform processing so that
[0047]
The wettability of water with respect to the liquid crystal polymer layer 1 is correlated with the proportion of active groups capable of hydrogen bonding on the upper and lower surfaces of the liquid crystal polymer layer 1. By setting the angle to about 65 °, the coating layer 2 is bonded to the upper and lower surfaces of the liquid crystal polymer layer 1 with a strong intermolecular force, so that the adhesion between the liquid crystal polymer layer 1 and the coating layer 2 is further improved. As a result, it is possible to obtain an insulating film 3 that does not peel off between the two even in a high-temperature bias test.
[0048]
If the liquid crystal polymer layer 1 has a contact angle with water of less than 3 °, the coating layer 2 is extremely spread on the liquid crystal polymer layer 1 and the positional accuracy is reduced. When a multilayer structure is formed by applying pressure, the position of the wiring conductor 4 formed on the surface of the insulating film 3 and the position of the through conductor 5 formed therein tend to be shifted, and the wire tends to be easily broken. There is a tendency that the adhesion between the liquid crystal polymer layer 1 and the coating layer 2 is reduced, and the liquid crystal polymer layer 1 and the coating layer 2 are easily separated. Therefore, it is preferable to set the contact angle of the upper and lower surfaces of the liquid crystal polymer layer 1 with water in the range of 3 to 65 °.
[0049]
The water for evaluating the contact angle is water purified by a distillation method or an ion exchange method specified in JIS K 0050 “General rules for chemical analysis methods”, or a combination of a reverse osmosis method, a detention method, and an ion exchange method. Water purified by the above method.
[0050]
Further, the liquid crystal polymer layer 1 has a surface layer in which the activated molecular layer which is relatively easily subjected to thermal motion and the coating layer 2 are entangled and bonded well, and from the viewpoint of further strengthening the adhesion between them, Its surface energy is 45-80 mJ / m 2 It is preferable that
[0051]
The surface energy of the upper and lower surfaces of the liquid crystal polymer layer 1 is 45 mJ / m 2 If it is less than 1, the molecular layer on the surface of the liquid crystal polymer layer 1 will not be sufficiently activated, and it will tend to be difficult to entangle and bond with the coating layer 2, and to be 80 mJ / m2. 2 Is exceeded, the surface of the liquid crystal polymer layer 1 becomes very reactive and reacts with oxygen in the air to form an oxide having low strength on the surface. As a result, the liquid crystal polymer layer 1 and the coating layer 2 Tends to decrease in adhesiveness, and the two are easily peeled off from each other. Therefore, the surface energy of the liquid crystal polymer layer 1 is set to 45 to 80 mJ / m. 2 It is preferable that
[0052]
Further, the arithmetic average roughness Ra of the surface of the liquid crystal polymer layer 1 is preferably set to 0.05 to 5 μm. When the arithmetic mean roughness Ra of the surface is set to 0.05 to 5 μm, the upper and lower surfaces of the liquid crystal polymer layer 1 have good adhesion with the coating layer 2 and have a good anchoring effect. The coating layer 2 can be more firmly adhered.
[0053]
The arithmetic average roughness Ra is preferably 0.05 μm or more from the viewpoint of preventing peeling of the liquid crystal polymer layer 1 and the coating layer 2 during solder reflow, and the coating layer 2 is formed on the surface. In this case, the thickness is preferably 5 μm or less from the viewpoint of preventing air entrapment. Therefore, it is preferable that the arithmetic average roughness Ra of the surface of the liquid crystal polymer layer 1 is 0.05 to 5 μm.
[0054]
Next, the coating layer 2 is made of a thermosetting resin, has a function of an adhesive when a wiring conductor 4 to be described later is adhered and formed, and is used when forming the multilayer wiring board 6 using the insulating film 3. And serves as an adhesive when the insulating films 3 are laminated.
[0055]
As such a thermosetting resin, a resin which cures by heating, such as an epoxy resin, a cyanate resin, a phenol resin, a polyimide resin, a thermosetting polyphenylene ether resin, and a bismaleimide triazine resin, is used. It is preferable to contain a thermosetting polyphenylene ether such as an allyl-modified polyphenylene ether from the viewpoint of positional accuracy when bonding the wiring conductor 4 and the wiring conductor 4.
[0056]
The coating layer 2 has a rubber component for adjusting the elastic modulus, an antioxidant for improving thermal stability, a light stabilizer such as an ultraviolet absorber for improving light resistance, and flame retardancy. Halogen or phosphoric acid flame retardants, antimony compounds and flame retardant aids such as zinc borate, barium metaborate and zirconium oxide, higher fatty acids and higher fatty acid esters to improve lubricity Lubricants such as higher fatty acid metal salts and fluorocarbon surfactants, aluminum oxide, silicon oxide, titanium oxide, barium oxide, strontium oxide, zirconium oxide, and the like for adjusting the coefficient of thermal expansion and contraction and improving mechanical strength Calcium oxide, zeolite, silicon nitride, aluminum nitride, silicon carbide, potassium titanate, barium titanate, strontium titanate, titanium Fillers such as calcium, aluminum borate, barium stannate, barium zirconate, strontium zirconate, or silane-based coupling agents to increase the affinity with the fillers to improve their bondability and mechanical strength And a coupling agent such as a titanate coupling agent.
[0057]
In particular, when the insulating film 3 is laminated and pressed to form the multilayer wiring board 6, the fluidity of the coating layer 2 and the shrinkage due to the heat press are suppressed, and the displacement of the through conductor 5 and the thickness variation of the coating layer 2 are prevented. From the viewpoint of doing so, the coating layer 2 preferably contains 10% by volume or more of inorganic insulating powder as a filler. Further, from the viewpoint of preventing peeling during solder reflow at the bonding interface with the liquid crystal polymer layer 1 and the bonding interface with the wiring conductor 4, the content of the inorganic insulating powder is preferably set to 70% by volume or less. Therefore, it is preferable that the coating layer 2 made of the thermosetting resin contains 10 to 70% by volume of the inorganic insulating powder.
[0058]
In addition, the shape of the above-mentioned inorganic insulating powder has a substantially spherical shape, a needle shape, a flake shape, and the like. From the viewpoint of filling property and uniformity of thermal expansion coefficient and shrinkage, the particle diameter is 0.1 to 2 μm. The shape is preferably substantially spherical.
[0059]
Such an insulating film 3 is, for example, a paste obtained by adding a thermosetting polyphenylene ether resin, a solvent, a plasticizer, and a dispersant to an inorganic insulating powder such as silicon oxide having a particle size of about 0.1 to 2 μm. Has a contact angle with water of 3 to 65 ° by plasma treatment and a surface energy of 45 to 80 mJ / m. 2 After the coating layer 2 is formed on the upper and lower surfaces of the liquid crystal polymer layer 1 having a melting point of 230 to 420 ° C. by using a conventionally known sheet molding method such as a doctor blade method, or the above paste A liquid crystal polymer layer 1 is immersed therein and vertically pulled up to form a coating layer 2 on the surface of the liquid crystal polymer layer 1, which is then heated and dried at a temperature of 60 to 100 ° C. for 5 minutes to 3 hours. Is done.
[0060]
The thickness of the insulating film 3 is preferably from 10 to 300 μm from the viewpoint of ensuring insulation reliability, and from the viewpoint of ensuring high heat resistance, low moisture absorption, and high dimensional stability, a liquid crystal polymer. It is preferable that the thickness of the layer 1 be in the range of 40 to 90% of the thickness of the insulating film 3.
[0061]
The multilayer wiring board 6 of the present invention is formed by laminating a plurality of insulating films 3 each having a wiring conductor 4 made of a metal foil disposed on at least one of the upper and lower surfaces, and vertically interposing the insulating film 3 therebetween. Are formed by electrically connecting the wiring conductors 4 located at the position (1) through the through conductor 5 formed on the insulating film 3.
[0062]
The wiring conductor 4 has a thickness of 2 to 30 μm and is made of a highly conductive metal foil such as copper or gold, and electrically connects the electronic component 7 mounted on the multilayer wiring board 6 to an external electric circuit (not shown). Has the function of connecting.
[0063]
From the viewpoint of preventing the occurrence of voids around the wiring conductor 4 when a plurality of the insulating films 3 are laminated, the wiring conductor 4 is coated as shown in the main part enlarged sectional view of FIG. It is preferable that at least the surface of the wiring conductor 4 and the surface of the coating layer 2 are buried in the layer 2 so as to be flat. Further, when the porosity in the dry state of the coating layer 2 is set to 3 to 40% by volume when the wiring conductor 4 is embedded in the coating layer 2, the resin rise of the coating layer 2 around the wiring conductor 4 does not occur. Flattening can be performed, and air trapped between the wiring conductor 4 and the coating layer 2 can be easily discharged to prevent air bubbles from being trapped. If the porosity in the dry state exceeds 40% by volume, pores remain in the coating layer 2 after pressurizing and heating and curing the laminated insulating films 3, and the pores adsorb moisture in the air. Therefore, it is preferable that the porosity of the coating layer 2 in a dry state is in the range of 3 to 40% by volume.
[0064]
The porosity of the coating layer 2 in the dry state can be adjusted by appropriately adjusting drying conditions such as a drying temperature and a temperature rising rate when the coating layer 2 is applied on the surface of the liquid crystal polymer layer 1 and dried. It can be a desired value.
[0065]
Further, the cross-sectional shape in the width direction of the wiring conductor 4 provided on the insulating film 3 is a trapezoidal shape in which the length of the base on the side of the insulating film 3 is shorter than the length of the base opposite thereto, and It is preferable that the angle between the bottom side and the side side is 95 to 150 °. The cross-sectional shape in the width direction of the wiring conductor 4 disposed on the insulating film 3 is trapezoidal in which the length of the base on the insulating film 3 side is shorter than the length of the opposing base, and the cross-sectional shape of the base on the insulating film 3 side is reduced. When the wiring conductor 4 is embedded in the coating layer 2 by setting the angle between the side conductors to 95 to 150 °, the wiring conductor 4 is easily embedded in the coating layer 2 and the wiring conductor 4 after the wiring conductor 4 is embedded. The surface of the coating layer 2 can be made substantially flat, and the multilayer wiring board 6 can be obtained in which the air is not trapped during the lamination and the insulating property is not reduced. In addition, from the viewpoint of burying without entrapping air bubbles, it is preferable that the angle between the bottom side and the side of the insulating film 3 side is 95 ° or more, and from the viewpoint of miniaturizing the wiring conductor 2, it is 150 °. ° or less.
[0066]
The thickness x (μm) of the coating layer 2 located between the short base of the wiring conductor 4 and the liquid crystal polymer layer 1 between the layers of the insulating film 3 is determined by the distance between the upper and lower liquid crystal polymer layers 1. T (μm), assuming that the thickness of the wiring conductor 4 is t (μm), 3 μm ≦ 0.5T−t ≦ x ≦ 0.5T ≦ 35 μm (8 μm ≦ T ≦ 70 μm, 1 μm ≦ t ≦ 32 μm) It is preferable that
[0067]
When the distance between the liquid crystal polymer layers 1 is T (μm) and the thickness of the wiring conductor 4 is t (μm), the wiring conductor 4 is made of a thermosetting resin between the short bottom of the length and the liquid crystal polymer layer 1. By setting the thickness x (μm) of the coating layer 2 to 3 μm ≦ 0.5T−t ≦ x ≦ 0.5T ≦ 35 μm, the distance between the short bottom of the wiring conductor 4 and the liquid crystal polymer layer 1 and the wiring conductor 4 can be reduced to less than t (μm), and the warpage of the multilayer wiring board 6 caused by the large difference in the thickness of the coating layer 2 can be reduced. Can be prevented. Therefore, the thickness x (μm) of the coating layer 2 located between the trapezoidal upper bottom surface of the wiring conductor 4 and the liquid crystal polymer layer 1 is determined by the distance between the liquid crystal polymer layers 1 is T (μm). Assuming that the thickness of No. 4 is t (μm), it is preferable that the range of 3 μm ≦ 0.5T−t ≦ x ≦ 0.5T ≦ 35 μm is satisfied.
[0068]
Such a wiring conductor 4 is formed by forming a metal foil made of, for example, copper on a precursor sheet to be the insulating film 3 by a subtractive method using a known photoresist, for example, by a transfer method or the like. It is formed. First, a metal foil transfer film is prepared by bonding a metal foil made of copper on a film serving as a support via an adhesive, and then the metal foil on the film is subjected to a subtractive method using a known photoresist. Is used to etch in a pattern. At this time, the side surface on the front surface side of the pattern is more likely to be etched because it has a longer contact time with the etchant than the side surface on the film side, and the cross-sectional shape in the width direction of the pattern can be trapezoidal. Note that the trapezoidal shape can be a trapezoidal shape in which the angle between the short base and the side is 95 to 150 ° by adjusting the concentration of the etching solution and the etching time.
[0069]
Then, the metal foil transfer film is laminated on a precursor sheet to be the insulating film 3 and hot-pressed at a temperature of 100 to 200 ° C. and a pressure of 0.5 to 10 MPa for 10 minutes to 1 hour. By peeling off the film and transferring the metal foil to the surface of the precursor sheet as the insulating film 3, the wiring conductor 4 having the trapezoidal upper bottom side embedded in the coating layer 2 can be formed.
[0070]
In addition, the thickness x (μm) of the coating layer 2 between the liquid crystal polymer layer 1 and the base having the shorter length of the wiring conductor 4 is adjusted to a desired range by adjusting the pressure of the hot press during the transfer of the metal foil. be able to. The surface of the wiring conductor 4 is preferably roughened by a process such as buffing, blasting, brushing, or chemical treatment in order to enhance the adhesion to the coating layer 2.
[0071]
In addition, a through conductor 5 having a diameter of about 20 to 150 μm is formed on the insulating film 3. The through conductor 5 has a function of electrically connecting the wiring conductors 4 positioned above and below the insulating film 3 with the insulating film 3 interposed therebetween. It is formed by embedding a conductive paste made of copper, silver, gold, solder, or the like in the through hole by a conventionally known screen printing method.
[0072]
According to the multilayer wiring board 6 of the present invention, since the insulating film 3 has the covering layer 2 made of a thermosetting resin on the upper and lower surfaces of the liquid crystal polymer layer 1, the liquid crystal polymer layer 1 has high heat resistance. It has high elastic modulus, high dimensional stability, and low hygroscopicity, making it possible to form the insulating film 3 without using a reinforcing material such as glass cloth. A uniform through hole can be formed.
[0073]
In such a multilayer wiring board 6, after forming the through conductor 5 at a desired position of the precursor sheet to be the insulating film 3 manufactured by the method described above, the patterned metal foil of copper, for example, is heated at a desired temperature. Transfer by hot pressing at 100 to 200 ° C for 10 minutes to 1 hour under the condition of pressure of 0.5 to 10 MPa, laminating these, finally temperature of 150 to 300 ° C and pressure of 0.5 to 10 MPa. It is manufactured by hot-pressing for 30 minutes to 24 hours under the conditions to completely cure.
[0074]
Thus, according to the multilayer wiring board 6 of the present invention, the connection pads 8 formed on a part of the wiring conductor 4 formed on the upper surface of the multilayer wiring board 6 having the above structure are connected to the connection pads 8 of the semiconductor elements or the like via the conductor bumps 8 such as solder. The parts 7 are electrically connected, and the conductor bumps 9 such as solder are formed on the connection pads 8 formed on a part of the wiring conductors 4 formed on the lower surface of the multilayer wiring board 6 so that the wiring density is high and the insulation is excellent. Hybrid integrated circuit.
[0075]
The multilayer wiring board 6 of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention. Although the multilayer wiring board 6 was manufactured by laminating the insulating films 3 of the above, the multilayer wiring board 6 may be manufactured by laminating two, three, or five or more layers of the insulating film 3. In addition, a build-up layer or a solder resist layer 10 composed of an insulating layer containing one, two, or three or more organic resins as a main component, or a multilayer wiring board 6 on the upper and lower surfaces of the multilayer wiring board 6 of the present invention. After the electronic component 7 is mounted on the electronic component 6, the underfill material 11 may be formed between the multilayer wiring board 6 and the electronic component 6.
[0076]
【Example】
Next, the insulating film of the present invention and the multilayer wiring board using the same were evaluated using the following samples.
(Example 1)
First, spherical fused silica having an average particle size of 0.6 μm is added to a thermosetting polyphenylene ether resin so that the content thereof becomes 40% by volume, and toluene is used as a solvent, and further, a solvent for accelerating the curing of the organic resin. The catalyst was added and mixed for 1 hour to prepare a varnish. Next, the melting point is 290 ° C. and the coefficient of thermal expansion in the layer direction is −3 × 10 -6 ~ 16 × 10 -6 The surface of the liquid crystal polymer layer having a voltage of 27 kV and an atmosphere of O / C was measured using a vacuum plasma apparatus. 2 And CF 4 (The gas flow rate is 50-200cm each. 3 / Min) and plasma treatment under the condition of 15 to 35 minutes on one side, the varnish is applied on the upper surface of this liquid crystal polymer layer by a doctor blade method, and a thermosetting polyphenylene ether having a thickness of 30 μm is coated. The layers were formed. Then, a thermosetting polyphenylene ether coating layer was similarly formed on the lower surface of the liquid crystal polymer layer to produce insulating films having various coefficients of thermal expansion and contraction in directions parallel to the upper and lower surfaces.
[0077]
Further, a through hole having a diameter of 50 μm was formed in the insulating film by a UV-YAG laser, and a conductive paste containing copper powder and an organic binder was embedded in the through hole by screen printing to form a through conductor.
[0078]
Next, a transfer support film having a thickness of 9 μm and having a copper foil formed in a circuit shape and an insulating film on which a through conductor is formed are aligned, and a pressure of 5 MPa is applied for 30 seconds by a vacuum laminating machine. After pressing, the transfer support film was peeled off, and the wiring conductor was embedded on the insulating film. Finally, four insulating films on which the wiring conductors were formed were superimposed, heated at 200 ° C. for 5 hours under a pressure of 3 MPa and completely cured to obtain a multilayer wiring board (Sample No. 1 to No. 1). 12).
[0079]
(Comparative example)
In the multilayer wiring board used for the comparative example, first, a circuit-like wiring conductor was formed by using a photoresist on a liquid crystal polymer layer having a melting point of 320 ° C. in which a copper foil was bonded by heat melting to the surface, and then UV A through-hole having a diameter of 50 μm is formed by a −YAG laser, and a conductive paste containing copper powder and an organic binder is further embedded in the through-hole by screen printing to form a through-conductor. A circuit board was manufactured by hot pressing at a temperature of 285 ° C. for 5 minutes under a pressure of 1 MPa with a liquid crystal polymer layer having a melting point of 280 ° C. interposed therebetween.
[0080]
As a test board for conducting continuity evaluation, a via chain was formed with upper and lower two-layered wiring conductors located inside via an insulating layer of a multilayer wiring board and through conductors electrically connecting both of them. Conduction reliability was evaluated by conducting a high-temperature and high-humidity test under the conditions of a temperature of 130 ° C. and a relative humidity of 85%, and the rate of change of the conduction resistance with respect to before the test was less than 15%, and not more than 15%. And Table 1 shows the conduction reliability results.
[0081]
[Table 1]
Figure 2004179011
[0082]
From Table 1, the thermal expansion coefficient in the layer direction of the insulating film is 3 × 10 -6 / Multi-layer wiring board of less than / ° C (Sample No. 1) and thermal expansion coefficient of 40 × 10 -6 In the multilayer wiring board (sample Nos. 6 and 7) exceeding / ° C, the change rate of the conduction resistance is as small as 12% or less even after 168 hours of the high temperature and high humidity test, but the change rate of the conduction resistance is 16% after 240 hours. It was found that there was a tendency that conduction reliability was slightly inferior to the above. In addition, in the multilayer wiring board of the comparative example, even after 168 hours of the high-temperature and high-humidity test, the rate of change of the conduction resistance was greatly deteriorated to 19%, and the conduction reliability was poor.
[0083]
On the other hand, the thermal expansion coefficient in the direction parallel to the upper and lower surfaces of the insulating film is 3 × 10 -6 ~ 40 × 10 -6 / C multilayer circuit board (Sample Nos. 2 to 5), the change rate of the conduction resistance was as small as 10% or less after 168 hours of the high-temperature and high-humidity test, and the change rate of the conduction resistance was 14% even after 240 hours. % Or less, and excellent conduction reliability. However, the thermal expansion coefficient is 3 × 10 -6 ~ 40 × 10 -6 / ° C., the conduction resistance of the multilayer wiring board (sample Nos. 11 and 12) whose shrinkage in the direction parallel to the upper and lower surfaces of the insulating film exceeds 0.15% even after 168 hours of the high temperature and high humidity test. Although the rate of change was as small as 13% or less, the conduction resistance after 240 hours was as large as 16% or more and the conduction reliability tended to be slightly inferior.
[0084]
On the other hand, the thermal expansion coefficient in the layer direction of the insulating film is 3 × 10 -6 ~ 40 × 10 -6 / ° C., and in a multilayer wiring board (sample Nos. 2 to 5 and 8 to 10) having a shrinkage rate of 0.15% or less in the layer direction of the insulating film, the conduction resistance is not changed even after 240 hours of the high-temperature and high-humidity test. It was found that the rate of change was as small as 14% or less, and the conduction reliability was particularly excellent.
[0085]
(Example 2)
The multilayer wiring board used for Example 2 was manufactured in the same manner as the multilayer wiring board for Example 1 except that the thickness of the liquid crystal polymer layer with respect to the insulating film was changed to various ratios. (Sample Nos. 13 to 18). The thickness of the liquid crystal polymer layer and the thickness of the coating layer were adjusted so that the thickness of the insulating film was 200 μm. The thermal expansion coefficient in a direction parallel to the upper and lower surfaces of the insulating film is 3 × 10 -6 ~ 40 × 10 -6 / ° C, and the shrinkage in the direction parallel to the upper and lower surfaces when heated at a temperature of 190 to 270 ° C for 2 to 180 minutes was 0.15% or less.
[0086]
As a test board for evaluating the insulation property, a circular conductor pattern having a diameter of 4000 μm was formed in a multilayer wiring board so as to face each other with an insulating layer interposed therebetween. A high-temperature bias test with an applied voltage of 5.5 V was performed under the conditions of a temperature of 85 ° C. and a relative humidity of 85%, the insulation resistance between the circular conductor patterns was measured, and the amount of change before and after the test was evaluated. Whether insulation reliability is good or bad is determined by insulation resistance of 1.0 × 10 8 Ω or better, 1.0 × 10 8 Less than Ω was judged as negative. Table 2 shows the results of insulation reliability.
[0087]
[Table 2]
Figure 2004179011
[0088]
From Table 2, it can be seen that the high-temperature bias was applied to the multilayer wiring boards (sample Nos. 13 and 14) in which the ratio of the thickness of the liquid crystal polymer layer to the insulating film was less than 40% and the multilayer wiring boards exceeding 90% (sample No. 18). Although the insulation resistance after 168 hours of the test was good, the insulation resistance was 8.8 × 10 after 240 hours. 7 It was found that there was a tendency to deteriorate to Ω or less.
[0089]
On the other hand, in the embodiment (sample Nos. 15 to 17) which is the multilayer wiring board of the present invention, even after 240 hours of the high temperature bias test, 2.1 × 10 8 Ω or more, which proved to be particularly excellent in insulation reliability.
[0090]
(Example 3)
The multilayer wiring board used for Example 3 was manufactured in the same manner as the multilayer wiring board for Example 1, except that the surface was changed to a liquid crystal polymer layer having various contact angles with water and surface energy. (Sample Nos. 19 to 27).
[0091]
The adhesion was evaluated by immersing the multilayer wiring board in a solder bath at various temperatures for 20 seconds, repeating this five times, and then observing the appearance of the multilayer wiring board to evaluate the adhesion. Table 3 shows the evaluation results of the adhesion.
[0092]
[Table 3]
Figure 2004179011
[0093]
Table 3 shows that the temperature of the multilayer wiring board having a contact angle of less than 3 ° with water on the surface of the liquid crystal polymer layer (sample No. 19) and the multilayer wiring board having a contact angle of more than 65 ° (sample No. 23) are higher. Although the appearance of the multilayer wiring board did not change even if the immersion in the solder bath at 260 ° C. was repeated 5 times, the liquid crystal polymer layer and the liquid crystal polymer layer were not changed when the immersion in the solder bath at 290 ° C. under severe temperature conditions was repeated 5 times. The peeling between the coating layers causes a swelling portion in the multilayer wiring board, and the adhesion tends to be slightly inferior. On the other hand, in the multilayer wiring board having a contact angle of 3 to 65 ° (sample Nos. 20 to 22), the appearance of the multilayer wiring board did not change even if the immersion in the solder bath at a temperature of 290 ° C. was repeated 5 times. And excellent adhesion. However, even when the contact angle is 3 to 65 °, the surface energy of the liquid crystal polymer layer is 45 mJ / m 2. 2 Multilayer wiring board (sample No. 24) less than 80 mJ / m 2 In the above multilayer wiring board (Sample No. 27), there was no change in the appearance of the multilayer wiring board even when the immersion in the solder bath at a temperature of 260 ° C. was repeated five times, but the solder bath at 290 ° C. under severe temperature conditions was used. When the immersion in the multilayer wiring board was repeated five times, peeling occurred between the liquid crystal polymer layer and the coating layer, so that a swelling portion was generated in the multilayer wiring board, and the adhesion tended to be slightly inferior. On the other hand, the contact angle is 3 to 65 ° and the surface energy is 45 to 80 mJ / m. 2 In the multilayer wiring board (Sample Nos. 20 to 22, 25, and 26), the appearance of the multilayer wiring board did not change even when the immersion in the solder bath at a temperature of 290 ° C. was repeated 5 times, and the adhesion was particularly excellent. I knew it was there.
[0094]
【The invention's effect】
According to the insulating film of the present invention, the insulating film is configured to have a coating layer made of a thermosetting resin on the upper and lower surfaces of the liquid crystal polymer layer, and has a coefficient of thermal expansion of 3 × 10 in the layer direction. -6 ~ 40 × 10 -6 / ° C, when a wiring board is manufactured using this insulating film, the coefficient of thermal expansion of the insulating film approximates the coefficient of thermal expansion of the wiring conductor, and the stress due to the difference in thermal expansion between the insulating film and the wiring conductor is reduced. As a result, the insulating film and the wiring conductor do not peel under high temperature and high humidity, and the wiring conductor does not break due to cracks in the insulating film in a temperature cycle test. In addition, since the molecules of the thermosetting resin are not as rigid as liquid crystal polymer molecules and do not show regular orientation, the molecules are relatively easy to move. And the adhesion between the insulating films does not occur in the high-temperature bias test, thereby preventing insulation failure. Furthermore, even when the wiring conductor is provided on the surface of the insulating film, the molecules of the thermosetting resin can enter the fine recesses on the surface of the wiring conductor and exert a sufficient anchor effect, and the connection between the insulating film and the wiring conductor can be achieved. Adhesion is improved, and as a result, there is no possibility that the wiring conductor is disconnected due to separation between the two under high temperature and high humidity. In addition, since the shrinkage in the layer direction when heated at a temperature of 190 to 270 ° C. for 2 to 180 minutes is set to 0.15% or less, the wiring conductor and the through conductor are provided on the insulating film, and the insulating film is multilayered. In the case of manufacturing a multilayer wiring board by making it into a multilayer, the heat press at the time of forming the multilayer does not reduce the positional accuracy of the through conductor in the layer direction of the insulating film or cause a variation in the diameter of the through conductor, and as a result, Thus, it is possible to manufacture a multilayer wiring board having excellent conduction reliability between the wiring conductor and the through conductor.
[0095]
Further, according to the insulating film of the present invention, when the thickness of the liquid crystal polymer layer is set to 40 to 90% of the thickness of the insulating film in the above configuration, thermal stress is applied to the insulating film during a temperature cycle test or the like. Even if it is done, the liquid crystal polymer layer having a small coefficient of thermal expansion and a small shrinkage rate satisfactorily constrains the coating layer having a large coefficient of thermal expansion and a large shrinkage rate to reduce the thermal expansion and shrinkage of the entire insulating film. be able to.
[0096]
Further, according to the insulating film of the present invention, in the above configuration, the liquid crystal polymer layer has a contact angle with water of 3 to 65 ° and a surface energy of 45 to 80 mJ / m. 2 In this case, the activated molecular layer on the surface of the liquid crystal polymer layer which is relatively easily moved by heat and the coating layer made of a thermosetting resin are entangled and bonded well, and the liquid crystal polymer layer and the coating layer become more An insulating film that is tightly adhered can be obtained.
[0097]
According to the insulating film of the present invention, when the arithmetic average roughness Ra of the upper and lower surfaces of the liquid crystal polymer layer is set to 0.05 to 5 μm in the above configuration, the upper and lower surfaces of the liquid crystal polymer layer are formed of a thermosetting resin. And a good anchoring effect having a good anchor effect, and an insulating film in which the liquid crystal polymer layer and the coating layer are more firmly adhered to each other.
[0098]
According to the insulating film of the present invention, when the coating layer contains 10 to 70% by volume of an inorganic insulating powder having a particle size of 0.1 to 2 μm in the above-described configuration, the wiring film is formed on the insulating film. In the case where a multilayer wiring board is produced by arranging through conductors and multilayering the insulating film, the inorganic insulating powder suppresses the fluidity of the coating layer and shrinkage due to the hot press, and by the hot press when forming the multilayer. Displacement of the through conductor in the layer direction, variation in the diameter of the through conductor, and variation in the thickness of the coating layer can be reduced, and an insulating film having more excellent dimensional stability can be obtained.
[0099]
Furthermore, according to the insulating film of the present invention, in the above configuration, when the shape of the inorganic insulating powder is substantially spherical, the filling property and the kneading property are improved when the inorganic insulating powder is filled into the thermosetting resin. In addition, the inorganic insulating powder can be uniformly distributed in the coating layer made of the thermosetting resin, and as a result, an insulating film having a more uniform thermal expansion coefficient and contraction rate of the coating layer can be obtained.
[0100]
According to the insulating film of the present invention, in the above-described configuration, when the thermosetting resin is a thermosetting polyphenylene ether, the thermosetting polyphenylene ether has excellent heat resistance and excellent dimensional stability. An insulating film having excellent temperature cycle reliability and good positional accuracy when bonding a wiring conductor can be obtained.
[0101]
According to the multilayer wiring board of the present invention, since the multilayer wiring board is formed using the insulating film, a multilayer wiring board having excellent moisture resistance and conduction reliability can be obtained.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an example of an embodiment of an insulating film of the present invention.
FIG. 2 is a sectional view showing an example of an embodiment of a multilayer wiring board of the present invention.
FIG. 3 is an enlarged sectional view of a main part of the multilayer wiring board shown in FIG. 2;
[Explanation of symbols]
1 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Liquid crystal polymer layer
2 .......... Coating layer
3 ... Insulating film
4 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Wiring conductor
5 ... Through conductor
6 ... multilayer wiring board

Claims (8)

液晶ポリマー層の上下面に熱硬化性樹脂から成る被覆層を有して成り、層方向における熱膨張係数が３×１０−６〜４０×１０−６／℃であり、かつ１９０〜２７０℃の温度で２〜１８０分間加熱した際の前記層方向における収縮率が０．１５％以下であることを特徴とする絶縁フィルム。It has a coating layer made of a thermosetting resin on the upper and lower surfaces of the liquid crystal polymer layer, and has a coefficient of thermal expansion in the layer direction of 3 × 10 −6 to 40 × 10 −6 / ° C. and 190 to 270 ° C. An insulating film having a shrinkage in the layer direction of 0.15% or less when heated at a temperature for 2 to 180 minutes. 前記液晶ポリマー層の厚みが４０〜９０％であることを特徴とする請求項１記載の絶縁フィルム。The insulating film according to claim 1, wherein the thickness of the liquid crystal polymer layer is 40 to 90%. 前記液晶ポリマー層は、水との接触角が３〜６５°であって、かつ表面エネルギーが４５〜８０ｍＪ／ｍ２であることを特徴とする請求項１または請求項２記載の絶縁フィルム。3. The insulating film according to claim 1, wherein the liquid crystal polymer layer has a contact angle with water of 3 to 65 ° and a surface energy of 45 to 80 mJ / m 2. 4 . 前記液晶ポリマー層の上下面は算術平均粗さＲａが０．０５〜５μｍであることを特徴とする請求項１乃至請求項３のいずれかに記載の絶縁フィルム。4. The insulating film according to claim 1, wherein upper and lower surfaces of the liquid crystal polymer layer have an arithmetic average roughness Ra of 0.05 to 5 μm. 5. 前記被覆層は、粒子径が０．１〜２μｍである無機絶縁粉末を１０〜７０体積％含有していることを特徴とする請求項１乃至請求項４のいずれかに記載の絶縁フィルム。The insulating film according to claim 1, wherein the coating layer contains 10 to 70% by volume of an inorganic insulating powder having a particle size of 0.1 to 2 μm. 前記無機絶縁粉末は、その形状が略球状であることを特徴とする請求項５記載の絶縁フィルム。The insulating film according to claim 5, wherein the inorganic insulating powder has a substantially spherical shape. 前記熱硬化性樹脂が熱硬化性ポリフェニレンエーテルであることを特徴とする請求項１乃至請求項６のいずれかに記載の絶縁フィルム。The insulating film according to any one of claims 1 to 6, wherein the thermosetting resin is a thermosetting polyphenylene ether. 上下面の少なくとも一方の面に金属箔から成る配線導体が配設された請求項１乃至請求項７のいずれかに記載の絶縁フィルムを複数積層して成るとともに、該絶縁フィルムを挟んで上下に位置する前記配線導体間を前記絶縁フィルムに形成された貫通導体を介して電気的に接続したことを特徴とする多層配線基板。A wiring conductor made of a metal foil is disposed on at least one of the upper and lower surfaces, wherein the insulating film according to any one of claims 1 to 7 is laminated, and vertically arranged with the insulating film interposed therebetween. A multilayer wiring board, wherein the located wiring conductors are electrically connected via a through conductor formed in the insulating film.
JP2002344736A 2002-11-27 2002-11-27 Insulating film and multilayer wiring board using this Pending JP2004179011A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006344570A (en) * 2004-08-06 2006-12-21 Mitsubishi Gas Chem Co Inc Insulated ultrafine powder and high dielectric constant resin composite material
JP7447459B2 (en) 2019-12-16 2024-03-12 株式会社レゾナック Method of manufacturing a laminated film, wiring board, and method of manufacturing a semiconductor device

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006344570A (en) * 2004-08-06 2006-12-21 Mitsubishi Gas Chem Co Inc Insulated ultrafine powder and high dielectric constant resin composite material
JP7447459B2 (en) 2019-12-16 2024-03-12 株式会社レゾナック Method of manufacturing a laminated film, wiring board, and method of manufacturing a semiconductor device

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