JP3944430B2 - Heat resistant porous resin multilayer substrate - Google Patents

Description

【００１３】
（式中、Ｒは炭化水素骨格を表し、Ｒ¹ は、同一又は異なって、水素原子又は炭素数１〜２０の炭化水素基を表し、Ｒ²，Ｒ³及びＲ⁴ は、同一又は異なっても良く、水素原子又は炭素数１〜６のアルキル基を表し、ｍは１〜４の整数、ｎは２以上の整数を表す。）で示される複数のスチレン基を有する重量平均分子量1000以下の架橋成分と、高分子量体とを含有する樹脂組成物を接着剤または充填剤とした耐熱性多孔質配線板である。
【００１４】
ジビニルベンゼンの硬化物の耐熱性が高く、その誘電率及び誘電正接が低いことはすでに述べた。本発明により、スチレン基を複数有する重量平均分子量が
１０００以下で不揮発性の炭化水素骨格の架橋成分と、高分子量体とを含有する樹脂組成物が、硬化時にひび割れせず、誘電率及び誘電正接が低い硬化物を与えることが明らかとなった。スチレン基間をアルキレン基のような柔軟な炭化水素骨格で結合しているため、硬化時のひび割れが生じないものである。
【００１５】
また、耐熱性多孔質樹脂フィルムは、フィルム層と多孔質層を２層以上積層した積層フィルムで構成されていても良い。また、耐熱性多孔質樹脂フィルムの空孔に接着剤が含浸されていても良い。
【００１６】
本発明は、耐熱性多孔質樹脂フィルムを接着剤を介して積層し、スルーホールに形成された電極を介して層間の配線が接続された構成を有する両面配線基板において、前記接着層が低誘電正接樹脂組成物である耐熱性多孔質両面配線基板である。また、前記スルーホール内表面に低誘電正接樹脂組成物コーティング膜を有する耐熱性多孔質両面配線基板である。また、本発明の多孔質ポリイミド両面配線板は前記低誘電樹脂接着剤で接着し積層した耐熱性多孔質基板とすることができる。
【００１７】
本発明の低誘電率、低誘電正接多層基板材料は、高周波伝送損失を小さくすることができる。また、熱膨張係数はＣｕ配線材料とほぼ同程度の値を有しており、信頼性に優れた電子部品を提供することができる。さらに、積層プロセスが簡単で電子部品の低コスト化することができる。
【００１８】
【発明の実施の形態】
本発明で用いる樹脂組成物及びその硬化物について説明する。
【００１９】
本発明で用いる樹脂組成物は、上記の一般式（化１）で示される複数のスチレン基を有する重量平均分子量１０００以下の架橋成分と、高分子量体とを含有する樹脂組成物であって、該樹脂組成物を１８０℃１００分で硬化させて得られる硬化物のガラス転移温度が１７０℃以上であるか、又は該硬化物の１７０℃における弾性率が５００ＭＰａ以上であることが好ましい。
【００２０】
なお、本明細書中において、ガラス転移温度とは、昇温速度５℃／分の条件で動的粘弾性特性を観測した際に、損失弾性率と貯蔵弾性率の比であるtanδ がピークとなる温度を示すものである。誘電率及び誘電正接が低く、ガラス転移温度が高く、高温下における弾性率が高い本発明で用いる樹脂組成物を多孔質ポリイミドと組合わせたプリント基板を使用することにより、電気信号の誘電損失を低く押さえ、かつ金ワイヤボンディング、ハンダ付等の高温での加工プロセスにおける変形を抑制することができる。
【００２１】
前記式において、Ｒで表される炭化水素骨格は、該架橋成分の重量平均分子量が１０００以下となるものであれば特に制限はない。即ち、Ｒで表される炭化水素骨格は、スチレン基における置換基、Ｒ¹，Ｒ²，Ｒ³及びＲ⁴の有無及びその大きさ、ｍ及びｎの数に応じて適宜選択することができるが、一般には炭素数１〜６０であり、好ましくは炭素数２〜３０である。Ｒで表される炭化水素骨格は、直鎖状又は分枝状のいずれでもよく、また、脂環式構造，芳香族環構造等の環構造を１つ以上含んでいてもよく、更に、ビニレン，エチニレン等の不飽和結合を含んでいてもよい。
【００２２】
Ｒで表される炭化水素骨格としては、例えば、エチレン，トリメチレン，テトラメチレン，メチルトリメチレン，メチルテトラメチレン，ペンタメチレン，メチルペンタメチレン，シクロペンチレン，シクロヘキシレン，フェニレン，フェニレンジエチレン，キシリレン、１−フェニレン−３−メチルプロペニレン等が挙げられる。
【００２３】
前記式において、Ｒ¹ で表される炭化水素基としては、炭素数１〜２０、好ましくは炭素数１〜１０の、直鎖状もしくは分枝状のアルキル基、例えばメチル，エチル、ｎ−プロピル，イソプロピル、ｎ−ブチル，イソブチル、ｓ−ブチル，ペンチル，ヘキシル，デシル，エイコシル；炭素数２〜２０、好ましくは炭素数２〜１０の、直鎖状もしくは分枝状のアルケニル基、例えばビニル、１−プロペニル、２−プロペニル、２−メチルアリル；アリール基、例えばフェニル，ナフチル，ベンジル，フェネチル，スチリル，シンナミルが挙げられる。
【００２４】
前記式において、ｎが２以上の整数であることからＲ¹ は複数存在し、ｍが２〜４の整数である場合も、Ｒ¹ は複数存在するが、そのような複数存在するＲ¹ は同一でも異なっていてもよく、その結合位置も同一でも異なっていてもよい。
【００２５】
前記式において、Ｒ²，Ｒ³又はＲ⁴ で表されるアルキル基としては、炭素数１〜６の直鎖状もしくは分枝状のアルキル基、例えばメチル，エチル、ｎ−プロピル，イソプロピル、ｎ−ブチル，イソブチル，ヘキシルが挙げられる。
【００２６】
前記式において、置換されていてもよいビニル基［(Ｒ³)(Ｒ⁴)Ｃ＝Ｃ(Ｒ²)−］は、ベンゼン環上、Ｒに対して、好ましくはメタ位又はパラ位に存在する。
【００２７】
本発明に用いる架橋成分としては、複数の置換されていてもよいスチレン基を有する重量平均分子量１０００以下の多官能性モノマーが好ましい。スチレン基は反応性が高く、誘電率及び誘電正接が非常に低い。架橋成分の骨格には誘電率及び誘電正接の観点から炭化水素骨格を採用することが好ましい。これによって、スチレン基の低誘電率性及び低誘電正接性を損なうことなく、該架橋成分に不揮発性及び柔軟性を付与することができる。また、重量平均分子量１０００以下の架橋成分を選択することによって、比較的低い温度で溶融流動性を示し、有機溶媒への溶解性もよくなるため、成形加工及びワニス化が容易になる。架橋成分の重量平均分子量が大きすぎると、溶融流動性が低くなり、成形加工の際に架橋が生じて成形不良となる場合がある。該架橋成分の重量平均分子量は１０００以下であれば制限はないが、好ましくは２００〜５００である。
【００２８】
架橋成分の好ましい例としては、１，２−ビス（ｐ−ビニルフェニル）エタン、１，２−ビス（ｍ−ビニルフェニル）エタン、１−（ｐ−ビニルフェニル）−２−(ｍ−ビニルフェニル）エタン、１，４−ビス(ｐ−ビニルフェニルエチル）ベンゼン、１，４−ビス（ｍ−ビニルフェニルエチル）ベンゼン、１，３−ビス（ｐ−ビニルフェニルエチル）ベンゼン、１，３−ビス（ｍ−ビニルフェニルエチル）ベンゼン、１−（ｐ−ビニルフェニルエチル）−４−（ｍ−ビニルフェニルエチル）ベンゼン、１−（ｐ−ビニルフェニルエチル）−３−（ｍ−ビニルフェニルエチル）ベンゼン及び側鎖にビニル基を有するジビニルベンゼン重合体
（オリゴマー）等が挙げられる。これらの架橋成分は２種以上組み合わせて使用することもできる。
【００２９】
本発明に好ましく用いられる架橋成分の合成方法としては、特開平１１−
６０５１９号公報に記載の方法で合成されたハロゲノアルキルスチレンをグリニャール反応によって種々のハロゲン化物とカップリングする方法、Makromol．
Chem．vol．１８７、２３頁(１９８６）記載の側鎖にビニル基を有するジビニルベンゼンオリゴマーの合成方法が挙げられるが、これらに限定されない。このようにして得られた架橋成分は、特に硬化触媒を添加しなくとも１８０℃以下の比較的低い温度で架橋し、耐熱性が高く、誘電率及び誘電正接の低い硬化物を与える。しかし、該架橋成分を高分子量体と組み合わせずに単独で使用した場合には、プリプレグ化した際のタックフリー性が得られない場合や、また、硬化後に十分な機械強度を得られない場合がある。
【００３０】
本発明では前述の架橋成分と高分子量体とを組み合わせることによって、タックフリー性及び硬化物の機械強度の向上を図ることを特徴としている。本発明に使用される高分子量体は、そのガラス転移温度が１７０℃以上であるか、又は
１７０℃における弾性率が５００ＭＰａ以上であり、かつワニス化が容易な可溶性ポリマーであることが好ましく、ガラス転移温度が１７０〜３００℃であるか、又は１７０℃における弾性率が５００〜３０００ＭＰａであることが更に好ましい。高分子量体が硬化性を有する場合には、硬化後のガラス転移温度が１７０℃以上であるか又は１７０℃における弾性率が５００ＭＰａ以上であることが好ましく、硬化後のガラス転移温度が１７０〜３００℃であるか又は１７０℃における弾性率が５００〜３０００ＭＰａであることが更に好ましい。このような高分子量体の具体的な例としては、ブタジエン，イソプレン，スチレン，メチルスチレン，エチルスチレン，ジビニルベンゼン，アクリル酸エステル（例えば、アクリル酸メチル，アクリル酸ブチル，アクリル酸フェニルなど），アクリロニトリル、Ｎ−フェニルマレイミドからなる単独および共重合体，置換基を有していてもよいポリフェニレンオキサイドならびに脂環式構造を有するポリオレフィン等が挙げられるが、これらに限定されない。本発明に用いる架橋成分は殆どの有機溶媒に可溶であるため、種々の高分子量体と混合し、均一なワニスを得ることができる。前記有機溶媒としては、例えば、アセトン，メチルエチルケトン，メチルイソブチルケトン等のケトン類，トルエン，キシレン等の芳香族炭化水素類、Ｎ，Ｎ−ジメチルホルムアミド、Ｎ，Ｎ−ジメチルアセトアミド等のアミド類，ジエチルエーテル，エチレングリコールモノメチルエーテル，プロピレングリコールモノメチルエーテル，テトラヒドロフラン，ジオキサン等のエーテル類，メタノール，エタノール，イソプロパノール等のアルコール類等が挙げられ、これらの有機溶剤は単独で、又は２種以上混合して用いることができる。ブタジエン、イソプレン及びアクリル酸エステルなどのゴム状成分は、それを含む樹脂組成物の硬化物に柔軟性及び接着性を付与し、かつ塗膜に平滑性を付与する。スチレン、エチルスチレン及び／又はアクリロニトリルは、先のゴム状成分と共重合することによって、その硬化物の耐熱性を向上させる働きを有する。ジビニルベンゼン及び／又はＮ−ビニルフェニルマレイミドを用い、公知のイオン重合法によって、側鎖に官能基を有する高分子量体を合成することができる。特にＮ−ビニルフェニルマレイミドは、アニオン重合によってマレイミド基のみが、カチオン重合によってスチレン基のみが重合するため、各種単量体との共重合が容易であり、その共重合体のガラス転移温度は高い。また、側鎖に官能基を有する高分子量体は、前記架橋成分と反応するため、該高分子量体と架橋成分とを含む樹脂組成物は硬化後相分離がおさえられ、強固な硬化物を与える。ポリフェニレンオキサイド及び脂環式構造を有するポリオレフィンは耐熱性ポリマーであり、前記架橋成分とアロイ化することによって、硬化物に柔軟性及び接着性を付与し、その機械強度を向上させることができる。これらの高分子量体は単独で用いても、複合して用いてもよい。例えば、ポリフェニレンオキサイドとポリブタジエンとを組合せるのが好ましい。
【００３１】
本発明で用いる樹脂組成物に含まれる架橋成分、高分子量体及び充填剤の添加量に関しては特に制限はないが、架橋成分が５〜９５重量部、高分子量体が９５〜５重量部、充填剤が７０〜５重量部の範囲で添加するのが好ましい。前記組成範囲内で、成膜性の付与，強度の向上，熱膨張係数の低減，誘電率の調整，軽量化及び表面粗化によるめっき配線との接着力の向上等の目的に応じて組成を調整することができる。より好ましい組成としては、架橋成分が５０〜９５重量部、高分子量体が５０〜５重量部、充填剤が７０〜５重量部であり、更に好ましい組成としては、架橋成分が５０〜８０重量部、高分子量体が５０〜２０重量部、充填剤が７０〜５重量部であり、この組成範囲により架橋性の官能基を持たない高分子量体を用いた場合にもその硬化物の耐溶剤性が保たれる。
【００３２】
本発明で用いる樹脂組成物は硬化触媒を添加しなくとも加熱のみによって硬化することができるが、硬化効率の向上を目的として、スチレン基を重合しうる硬化触媒を添加することができる。その添加量には特に制限はないが、硬化触媒の残基が誘電特性に悪影響を与える恐れがあるので、前記架橋成分及び高分子量体の合計１００重量部に対して、０.０００５〜１０ 重量部とすることが望ましい。硬化触媒を前記範囲で添加することにより、スチレン基の重合反応が促進され、低温で強固な硬化物を得ることができる。スチレン基の重合を開始しうるカチオン又はラジカル活性種を、熱又は光によって生成する硬化触媒の例を以下に示す。カチオン重合開始剤としては、ＢＦ₄，ＰＦ₆，ＡｓＦ₆，ＳｂＦ₆を対アニオンとするジアリルヨードニウム塩，トリアリルスルホニウム塩及び脂肪族スルホニウム塩が挙げられ、旭電化工業製ＳＰ−７０，１７２，ＣＰ−６６，日本曹達製ＣＩ−２８５５,２８２３,三新化学工業製ＳＩ−１００Ｌ及びＳＩ−１５０Ｌ等の市販品を使用することができる。ラジカル重合開始剤としては、ベンゾイン及びベンゾインメチルのようなベンゾイン系化合物，アセトフェノン及び２，２−ジメトキシ−２−フェニルアセトフェノンのようなアセトフェノン系化合物、チオキサントン及び２，４−ジエチルチオキサントンのようなチオキサンソン系化合物、４，４′−ジアジドカルコン、２，６−ビス（４′−アジドベンザル）シクロヘキサノン及び４，４′−ジアジドベンゾフェノンのようなビスアジド化合物、アゾビスイソブチルニトリル、２，２−アゾビスプロパン、ｍ，ｍ′−アゾキシスチレン及びヒドラゾンのようなアゾ化合物、ならびに２，５−ジメチル−２，５−ジ（ｔ−ブチルパーオキシ）ヘキサン及び２，５−ジメチル−２，５−ジ（ｔ−ブチルパーオキシ）ヘキシン−３、ジクミルパーオキシドのような有機過酸化物等が挙げられる。特に、官能基を持たない化合物の水素引き抜きを生じさせ、架橋成分と高分子量体間の架橋をもたらしうる有機過酸化物又はビスアジド化合物を添加することが望ましい。
【００３３】
本発明で用いる樹脂組成物には、保存安定性を増すために重合禁止剤を添加することもできる。その添加量は、誘電特性，硬化時の反応性を著しく阻害しないような範囲であることが好ましく、前記架橋成分及び高分子量体の合計１００重量部に対して、０.０００５〜５ 重量部とすることが望ましい。重合禁止剤を前記範囲で添加すると、保存時の余計な架橋反応を抑制することができ、また、硬化時に著しい硬化障害をもたらすこともない。重合禁止剤の例としては、ハイドロキノン、ｐ−ベンゾキノン，クロラニル，トリメチルキノン、４−ｔ−ブチルピロカテコール等のキノン類及び芳香族ジオール類が挙げられる。
【００３４】
本発明で用いる耐熱性多孔質樹脂フィルムについて以下説明する。本発明では、ポリイミド，アラミド，ポリサンフォン，ポリエーテルサルフォン，ポリエーテルエーテルケトン，ポリベンゾオキサゾール，ポリフェニレンサルファイド，シンジオタクチックポリスチレン，ポリエーテルニトリル，ポリテトラフロロエチレンなどの耐熱性多孔質樹脂材料を使用することができる。ただし、多孔質ポリイミドフィルムの場合は、主に芳香族テトラカルボン酸二無水物としてsBPDAを用い、芳香族ジアミンとしてＰＰＤおよびＤＤＥを用いることが好ましい。この組成で作成したポリイミドは多孔質化した場合でも機械強度，誘電特性，熱膨張などの物性が良好となる。また、多孔質ポリイミドフィルムは、下記式ａ記載の構造であり、Ｒが下記式ｂ，ｃの構造からなる多孔質ポリイミドフィルムであって、ｂ／（ｂ＋ｃ）が０.８〜１.０とすることが好ましい。
【００３５】
【化２】

【００３６】
【化３】

【００３７】
【化４】

【００３８】
ポリイミドは、芳香族テトラカルボン酸二無水物と芳香族ジアミンとからポリアミック酸を経由し、イミド化して合成される。芳香族テトラカルボン酸二無水物および芳香族ジアミンの組み合わせは多数あり、その組み合わせにより、合成されるポリイミドのパッキング係数は異なる。
【００３９】
ここでパッキング係数（Ｋ）とは、Polymer．Sci．ＵＳＳＲ，１２，５５６（１９７０）にSlonimskiiやAskadskiiによって提案されたものであり、分子鎖の固有体積（Ｖint）を密度から求まる実際のモル体積（Ｖtrue）で割った値として
Ｋ＝Ｖint／Ｖtrue＝ＮＡΣΔＶｉ／（Ｍ／ｄ）
ＮＡ：アボガドロ数
ΔＶｉ：構成原子の真の体積
Ｍ：分子量
ｄ：密度
のように定義される。
【００４０】
多孔質化すると、誘電率および誘電正接は低下し、改善されるが、一方でポリイミドフィルムの機械的強度は低下する。そのため、多孔質化しない状態でポリイミドフィルムの機械的強度は可能な限り高くしなければ、多孔質化した際に十分な機械的強度が実現できない。
【００４１】
上記のパッキング係数を大きくすれば、一般に機械的強度が向上する。一方で、熱膨張係数，伸びといった物性はパッキング係数が大きすぎると問題が生じる場合がある。パッキング係数を大きくすると伸び、熱膨張係数が小さくなり、フレキシブル性や熱膨張係数のＣｕ配線とのマッチングが悪くなり、信頼性が低下する場合がある。したがって、芳香族ジアミンおよび芳香族テトラカルボン酸二無水物の組み合わせを最適化することが必要である。本発明においては、芳香族テトラカルボン酸二無水物としてｓＢＰＤＡ（ビフェニルテトラカルボン酸二無水物），芳香族ジアミンとしてＰＰＤ(パラフェニレンジアミン)とＤＤＥ（４，４′−ジアミノジフェニルエーテル）を採用し、ＰＰＤ組成比がモル％で１００〜８０％とする。この組成においては、Ｃｕ配線と熱膨張係数のマッチング，誘電特性が良好であり、強度も十分となる。
【００４２】
溶媒としては、ポリマーを溶解するものであれば、特に限定されず、例えば、Ｎ−メチルピロリドン、γ−ブチロラクトン等がある。
【００４３】
多孔質層の形成方法には、湿式凝固法，乾式凝固法，延伸法など種々の製膜方法がある。そのうちで、湿式凝固法によれば、連続気泡多孔質膜が得られ好ましい。
【００４４】
湿式凝固法では、一般に、溶剤に樹脂と添加剤等を溶解した製膜原液(ドープ)を調製し、これを基材に塗布（キャスト）したものを凝固液に浸漬して溶剤置換させ、樹脂を凝固（ゲル化）させ、その後、凝固液等を乾燥除去し、多孔質層を得る。
【００４５】
多孔質化していないフィルム層や多孔質層を銅箔上に直接形成させることもできる。
【００４６】
なお、湿式凝固法におけるドープは、好ましくは−２０〜４０℃の温度範囲で塗布される。また、凝固液としては、用いる樹脂を溶解せずに上記溶剤と相溶性を有するものであれば、限定されない。水と、メタノール，エタノール，イソプロピルアルコール等のアルコール類と、これらの混合液とが用いられ、特に水がよく用いられる。浸漬時の凝固液の温度は特に限定されない。好ましくは、０〜５０℃の温度範囲である。
【００４７】
製膜原液のポリマー濃度は、５重量％から２５重量％の範囲が好ましく、特に、より優れた強度を有する多孔質成型体を得るには、７重量％以上であり、高空孔率を有する多孔質成型体を得るには、２０重量％以下がより好ましい。濃度が高すぎると、粘度が高くなりすぎて取り扱いが困難になるし、濃度が低すぎると、多孔質膜を形成できないからである。
【００４８】
孔径形状や孔径制御のために硝酸リチウムのような無機物やポリビニルピロリドンのような有機物を添加することもできる。添加物の濃度は、溶液中に１重量％から１０重量％まで添加するのが好ましい。硝酸リチウムを添加すると、溶剤と凝固液との置換速度が速く、スポンジ構造の中にフィンガーボイド構造（指状にボイドを有する構造）を形成できる。ポリビニルピロリドンのような凝固スピードを遅くする添加剤を加えると、スポンジ構造が均一に広がった多孔質層が得られる。
【００４９】
ドープは一定の厚みに塗布し、水等の凝固液中に浸積して凝固させたり、水蒸気雰囲気下に放置して凝固した後、水中に浸積するなどして、脱溶剤され、多孔質層となる。多孔質層の形成後、凝固液から取り出し、乾燥する。乾燥温度は、特に制限されない。２００℃以下での乾燥が望ましい。
【００５０】
形成した多孔質層，フィルム層は、最終的に２００〜５００℃で熱処理して、前駆体（ポリアミド酸）を加熱閉環させてポリイミド化する。
【００５１】
上記の手段により、５０〜８５％程度の高い空孔率を有する多孔質成型体を銅箔上に形成できる。
【００５２】
本発明は上記低誘電正接樹脂組成物を接着剤または充填剤とすることで多層基板を作成することができる。接着剤として使用する場合は、片面銅箔付多孔質ポリイミドフィルムを接着し両面配線板を作製する。両面配線板は片面銅箔付多孔質ポリイミドフィルムを接着し作製する。次いで銅箔をエッチングし表面配線を形成し、プリプレグをはさみ加熱プレス加工して積層することができる。次いでスルーホールを形成したのちスルーホールに配線を形成し層間接続を行って、多層基板を作成することができる。表面配線の形成は通常のフォトリソグラフィーを用いることができる。スルーホールの形成はドリル、レーザーなどにより加工される。多孔質材料の空孔が連続孔で液体の浸入が懸念される場合は、スルーホール内面に充填剤として使用するワニスをコーティングして拡散防止膜を形成し、液体の空孔内侵入を防止させる。この拡散防止膜により不純物の浸入を防止し、簡単な洗浄プロセスで信頼性の高い多層基板を作成することができる。層間接続用の配線はメッキプロセスやペースト充填などにより形成することができる。加圧プレス加工の条件は、樹脂組成物によるが、例えば高分子量体として環状ポリオレフィンを使用した場合には、１２０〜１８０℃，１.０〜５ＭＰａ で１〜３時間成形するのが好ましい。
【００５３】
ワニスを充填剤として用いる多層基板は、銅箔無し多孔質ポリイミドフィルムおよび片面銅箔付多孔質ポリイミドフィルムにワニスを含浸し、乾燥させプリプレグとして用いることによって作製する。一般にプリプレグは樹脂組成物をガラスクロスや不織布に含浸させて得られる。ガラスクロスや不織布はプレス加工時によれや凝集といった問題が生じ微細領域では不均一な組成となる場合がある。そこで、プリプレグの基材となる多孔質ポリイミドフィルムに特に限定はないが、好ましくは空孔径が０.５μｍ 以下で、空孔率が３０％以上、より好ましくは空孔径が０.２〜０.５μｍで、空孔率が４０〜７０％とする。この範囲であれば充填剤とポリイミドの組成が微細領域でも十分に均一となり、配線形成後の電気特性にばらつきを小さくすることができる。空孔径が０.２μｍ より小さい場合、エッチング液やメッキ液が浸入した際に洗浄が困難となる。エッチング液，メッキ液等は容易に空孔内に浸入する。空孔径が小さい場合液の乾燥速度が速く液中の塩などの固形物が空孔内で析出する。一旦析出すると洗浄が困難となり多孔質フィルム中に残存し電気特性が低下してしまう。
【００５４】
プリプレグは、低誘電正接樹脂組成物を用いて作製したワニスに、基材となる片面銅箔付多孔質ポリイミドフィルムを浸し、その後これを乾燥することにより作製される。含浸後の乾燥条件は樹脂組成物によるが、例えば溶媒としてトルエンを使用した場合は、８０〜１３０℃で３０〜９０分程度乾燥するのが好ましい。
【００５５】
また、本発明のプリプレグは、充填材の充填率を変化させることで、誘電率，誘電正接を任意に設定することができる。
【００５６】
本発明の銅箔付プリプレグは銅箔をエッチングし表面配線を形成し、積層し加熱プレス加工することによって多層化し、スルーホールを形成し、スルーホールに配線を形成させ層間接続を行って多層基板を作成することができる。また、本発明の銅箔付プリプレグは銅箔をエッチングし表面配線を形成し、さらにビアホールを形成し、ビアホールに配線を形成させた後、積層し加熱プレス加工することによって、多層基板を一体成型することができる。表面配線の形成は通常のフォトリソグラフィーを用いることができる。スルーホール及びビアホールの形成はドリル，レーザーなどにより加工される。多孔質材料の空孔に充填材を完全に充填せずに、空孔が存在し、連続孔で液体の浸入が懸念される場合は、スルーホール内面に充填剤として使用するワニスをコーティングし、拡散防止膜を形成しても良い。この拡散防止膜により不純物の浸入を防止し、簡単な洗浄プロセスで信頼性の高い多層基板を作成することができる。層間接続用の配線はメッキプロセスやペースト充填などにより形成することができる。加圧プレス加工の条件は、樹脂組成物によるが、例えば高分子量体として環状ポリオレフィンを使用した場合には、１２０〜１８０℃、１.０〜５ＭＰａ で１〜３時間成形するのが好ましい。
【００５７】
このようにして得られた多層基板は誘電正接が低いため、誘電損失の小さな多層基板となる。また、本発明の多層基板は、Ｃｕと熱膨張係数が同等で信頼性の高い多層基板を提供することができる。
【００５８】
（実施例）
以下に実施例を示して本発明を具体的に説明するが、本発明はこれらに限定されない。なお、以下の説明中に部とあるのは、特に断りのない限り重量部を指す。
【００５９】
表１〜表２に本発明の実施例の組成及びその特性を示す。以下に使用した試薬の名称，合成方法，ワニスの調製方法，多孔質ポリイミドフィルムの製造法，両面板の作成法及び硬化物の評価方法を説明する。
【００６０】
（１）１，２−ビス（ビニルフェニル）エタン（ＢＶＰＥ）の合成
１，２−ビス（ビニルフェニル）エタン（ＢＶＰＥ）は、以下に示すような公知の方法で合成した。５００ｍｌの三つ口フラスコにグリニャール反応用粒状マグネシウム（関東化学製）５.３６ｇ(２２０mmol）をとり、滴下ロート，窒素導入管及びセプタムキャップを取り付けた。窒素気流下、スターラーによってマグネシウム粒を攪拌しながら、系全体をドライヤーで加熱脱水した。乾燥テトラヒドロフラン３００ｍｌをシリンジにとり、セプタムキャップを通じて注入した。溶液を−５℃に冷却した後、滴下ロートを用いてビニルベンジルクロライド
（ＶＢＣ，東京化成製）３０.５ｇ（２００mmol）を約４時間かけて滴下した。滴下終了後、０℃／２０時間、攪拌を続けた。反応終了後、反応溶液をろ過して残存マグネシウムを除き、エバポレーターで濃縮した。濃縮溶液をヘキサンで希釈し、３.６％ 塩酸水溶液で１回、純水で３回洗浄し、次いで硫酸マグネシウムで脱水した。脱水溶液をシリカゲル（和光純薬製ワコーゲルＣ３００）／ヘキサンのショートカラムに通して精製し、真空乾燥してＢＶＰＥを得た。得られた
ＢＶＰＥはｍ−ｍ体（液状），ｍ−ｐ体（液状），ｐ−ｐ体（結晶）の混合物であり、収率は９０％であった。¹Ｈ−ＮＭＲ によって構造を調べたところその値は文献値と一致した(６Ｈ−ビニル：α−２Ｈ，６.７，β−４Ｈ，５.７，５.２；８Ｈ−アロマティック：７.１〜７.３５；４Ｈ−メチレン：２.９ ）。この
ＢＶＰＥを架橋成分として用いた。
【００６１】
（２）その他の試薬
その他の高分子量体，架橋成分として、以下に示すものを使用した。
【００６２】
高分子量体；
Zeonor：日本ゼオン製，環状ポリオレフィン（Zeonor1600R）
ＰＰＥ：アルドリッチ製，ポリ−２，６−ジメチル−１，４−フェニレンオキシド
脂環式アクリレート：日本化薬株式会社，Ｒ−６８４
硬化触媒；
２５Ｂ：日本油脂製２，５−ジメチル−２，５−ビス(ｔ−ブチルパーオキシ)ヘキシン−３（パーヘキシン２５Ｂ）
（３）ワニスの調製方法
所定量の高分子量体，架橋成分及び硬化触媒等をクロロホルム又は二硫化炭素に溶解することによって樹脂組成物のワニスを作製した。
【００６３】
（４）片面銅箔付多孔質ポリイミドフィルムの作製
窒素フローが可能なグローブボックスにおいて、所定の比率で混合した芳香族ジアミンであるＰＰＤおよびＤＤＥをＮ−メチルピロリドンに加え、室温で撹絆した。次いで、芳香族ジアミン１モルに対し、酸無水物であるｓＢＰＤＡを１モル加え、１時間ほど窒素フロー中で撹絆し、固形分１０ｗｔ％のポリアミド酸溶液を得た。
【００６４】
得られたポリアミド酸溶液を厚さ１８μｍの銅箔に塗布し、水が入った凝固槽中に浸漬して水と接触させゲル化（凝固）させた。これを取り出し、１２０℃で十分に乾燥させ、さらに４００℃で３０分間処理しイミド化させ、多孔質ポリイミドフィルムを銅箔上に形成し、片面銅箔付銅箔付き多孔質ポリイミドフィルムを作成した。なお、空孔率は６５％、空孔径が約０.２μｍであった。
【００６５】
（５）多孔質アラミドフィルムの作製
芳香族ポリアミド（帝人（株）製，コーネックス）をＮ−メチル−２−ピロリドン（ＮＭＰ）中に溶解し芳香族ポリアミド（１００重量部），ＮＭＰ（９００重量部）のポリマー溶液を得た。
【００６６】
これを厚み１９０μｍの厚さでポリプロピレンフィルム上に塗布し、６０℃の水槽に浸漬して多孔質フィルムを形成した。その後、１昼夜水中保存して脱溶剤を行った。
【００６７】
得られた多孔体は、厚み３５μｍの連続孔が形成されたスポンジ構造となっていた。平均孔径は２μｍ、空孔率は４５％であった。
【００６８】
（６）片面銅箔フィルム層付多孔質ポリイミドフィルムの作製
１０ｗｔ％のポリアミド酸溶液を、厚さ１８μｍの銅箔に塗布してフィルム層を形成し１２０℃で十分に乾燥させ、さらに窒素中４００℃で３０分間処理しイミド化させた。次いでポリアミド酸溶液をフィルム層上に塗布し、水が入った凝固槽中に浸漬して水と接触させゲル化（凝固）させた。これを取り出し、１２０℃で十分に乾燥させ、さらに窒素中４００℃で３０分間処理しイミド化させ、多孔質ポリイミドフィルムをフィルム層上に形成し、片面銅箔フィルム層付き多孔質ポリイミドフィルムを作成した。
【００６９】
なお、フィルム層込みの空孔率は５２％、多孔質層の空孔径が約０.２μｍであった。
【００７０】
（７）両面銅箔フィルム層付多孔質ポリイミドフィルムの作製
図１に示した両面板の作成法に従い以下説明する。前記ワニスを接着剤とし片面銅箔フィルム層付多孔質ポリイミドフィルムを両面銅箔フィルム層付多孔質ポリイミドフィルムとする工程である。
（ａ）接着剤の塗布
銅箔１，フィルム層２，多孔質層３からなる片面銅箔フィルム層付多孔質ポリイミドフィルム４の多孔質層面にワニスを塗布後に乾燥し、低誘電正接接着層５を形成した。
（ｂ）両面銅箔フィルム層付多孔質ポリイミドフィルムの形成
低誘電正接接着層を形成した片面銅箔フィルム層付多孔質ポリイミドフィルム４と接着層を形成していない片面銅箔フィルム層付多孔質ポリイミドフィルムを貼り合わせ、ポリイミドフィルム及び鏡板を介し、真空下で、加熱及び加圧して接着し両面銅箔フィルム層付多孔質ポリイミドフィルム６を作製した。加熱条件は、１２０℃／３０分，１８０℃／１００分で、プレス圧力１.５ＭＰａ とした。
【００７１】
（８）両面銅箔付多孔質アラミドフィルムの作製
両面板の作成法にについて説明する。前記ワニスを接着剤とし銅箔と多孔質アラミドフィルム接着し両面銅付多孔質アラミドフィルムとする工程である。
（ａ）接着剤の塗布
多孔質アラミドフィルムを成膜時の基材としたポリプロピレンフィルムからはがし、取り出した多孔質アラミドフィルムにワニスを塗布後に乾燥し、低誘電正接接着層を両面に形成した。
（ｂ）両面銅箔付多孔質アラミドフィルムの形成
低誘電正接接着層を形成した接着層付多孔質アラミドフィルムの上下に銅箔を貼り合わせ、ポリイミドフィルム及び鏡板を介し、真空下で、加熱及び加圧して接着し両面銅箔付多孔質アラミドフィルムを作製した。加熱条件は、１２０℃／３０分，１８０℃／１００分で、プレス圧力１.５ＭＰａとした。
【００７２】
（９）ポリイミドプリプレグの作製
実施例において作製したポリイミドプリプレグはすべて、樹脂組成物のワニスを充填剤として多孔質ポリイミドフィルムまたは片面銅箔付多孔質ポリイミドフィルムに含浸して作製した。図２に従いプリプレグ作製を説明する。
（ａ）片面銅箔付多孔質ポリイミドフィルムの作製
固形分１０ｗｔ％のポリアミド酸溶液を厚さ１８μｍの銅箔１に塗布して、水が入った凝固槽中に浸漬して水と接触させゲル化（凝固）させた。これを取り出し、１２０℃で十分に乾燥させ、さらに窒素中４００℃で３０分間処理しイミド化させ、多孔質ポリイミドフィルム７を銅箔１上に形成し、片面銅箔付多孔質ポリイミドフィルム８を作成した。なお、銅箔を取り除いた状態で使用する場合はＦｅＣｌ₃／ＨＣｌ エッチング液を用いて銅箔をエッチアウトし、希ＨＣｌ，水で洗浄し多孔質ポリイミドフィルムとした。
（ｂ）ワニスの充填
片面銅箔付多孔質ポリイミドフィルムまたは多孔質ポリイミドフィルムの多孔質面に十分な量のワニスを塗布し、真空装置内で吸引し多孔質層内にワニスを含浸し低誘電正接充填物９を多孔質ポリイミドフィルム７内に充填した。次いで
９０℃で６０分間乾燥し、１２０℃で１時間加熱処理を行いプリプレグ１０作製した。
【００７３】
（１０）アラミドプリプレグの作製
実施例において作製したアラミドプリプレグはすべて、樹脂組成物のワニスを充填剤として多孔質アラミドフィルムに含浸して作製した。
【００７４】
多孔質アラミドフィルムを成膜時の基材としたポリプロピレンフィルムからはがし、取り出した多孔質アラミドフィルムにワニスを充填したのち乾燥し、低誘電正接接着層を両面に形成した。
【００７５】
多孔質アラミドフィルムに十分な量のワニスを塗布し、真空装置内で吸引し多孔質層内にワニスを含浸し低誘電正接充填物を多孔質アラミドフィルム内に充填した。次いで９０℃で６０分間乾燥し、１２０℃で１時間加熱処理を行いアラミドプリプレグ作製した。
【００７６】
（１１）誘電率及び誘電正接の測定
誘電率，誘電正接は空洞共振器摂動法（アジレントテクノロジー製8722ES型ネットワークアナライザー,関東電子応用開発製空洞共振器）によって、１０ＧＨzでの値を観測した。
【００７７】
（１２）引張強度の測定
引張強度は、島津製ＡＧＳ−１００型引張試験機を用い、幅２mm，長さ７０mmのサンプルを用い、室温，支点間距離２０mm引張速度１０mm／分の条件で測定した。
【００７８】
（１３）接着及びピール強度
接着及びピール強度測定用サンプルは、各樹脂組成物を電解銅箔（１８μｍ）の粗面上に樹脂板の作製方法と同様の条件で樹脂層を形成して作製した。樹脂層は厚さ２mm、大きさは７０×７０mmとした。樹脂層上の電解銅箔を幅１０mmに切断して、その接着及びピール強度を測定した。
【００７９】
（１４）熱膨張係数の測定
熱膨張係数は、ＴＭＡを用い、幅５mm，長さ２５mmのサンプルを用い、２℃／minの昇温速度で測定した。
【００８０】
［実施例１〜３］
実施例１〜３は、多孔質ポリイミドフィルムを低誘電正接樹脂で接着し積層化した基板の実施例であり、高分子量体であるZeonor、ＰＰＥ，ポリビニルベンジルエーテルと架橋成分であるＢＶＰＥをそれぞれ１：１の配合比で含み、更に樹脂成分の重量に対して１ｗｔ％の硬化触媒２５Ｂを含んでなる樹脂組成物を接着剤として用いた例である。これらの組成物の硬化物は、溶媒に二硫化硫黄を使用してワニスを調製し、上述の方法で両面板を作製した例である。表１に示した各実施例から明らかなように、各樹脂板の誘電率及び誘電正接は非常に低く、誘電率は２.１５〜２.３０であり、誘電正接は０.００１８〜０.００２８であった。その他の特性は添加した高分子量体の特性が反映され、引張強度が９０〜１１５ＭＰａ、熱膨張係数が１６〜２０ppm／℃，ピール及び接着強度が０.８ 〜１.２Ｎ／ｍと優れた値を示した。多孔質ポリイミドフィルムを低誘電正接接着剤を用いて、低誘電正接，高強度，低熱膨張積層板を作成できることを確認した。
【００８１】
また、多孔質アラミドフィルムを用いて、多孔質ポリイミドフィルム同様に高分子量体であるZeonor、ＰＰＥ，ポリビニルベンジルエーテルと架橋成分であるＢＶＰＥをそれぞれ１：１の配合比で含み、更に樹脂成分の重量に対して１wt％の硬化触媒２５Ｂを含んでなる樹脂組成物を接着剤として用い積層したところ、多孔質ポリイミド同様の結果が得られ、多孔質アラミドフィルムの有効性を確認した。
【００８２】
【表１】

【００８３】
［実施例４，５］
実施例４，５は、多孔質ポリイミドフィルムに低誘電正接樹脂を充填した基板の実施例であり、高分子量体であるZeonor、ＰＰＥと架橋成分であるＢＶＰＥをそれぞれ１：１の配合比で含み、更に樹脂成分の重量に対して１ｗｔ％の硬化触媒２５Ｂを含んでなる樹脂組成物を充填剤として用いた例である。これらの組成物の硬化物は、溶媒に二硫化硫黄を使用してワニスを調製し、上述の方法で両面板として作製した。各実施例から明らかなように本樹脂組成物の誘電率及び誘電正接は非常に低く、誘電率は３.２３，３.３１ であり、誘電正接は０.００２５、０.００２８ であった。その他の特性は添加した高分子量体の特性が反映され、引張強度が１２０，１３５ＭＰａ、熱膨張係数が１７，１９ppm／℃ ，ピール及び接着強度が０.８、１.１Ｎ／ｍと優れた値を示した。多孔質ポリイミドフィルムを低誘電正接接着剤を用いて、低誘電正接、高強度、低熱膨張充填基板を作成できることを確認した。
【００８４】
また、多孔質アラミドフィルムを用いて、多孔質ポリイミドフィルム同様に高分子量体であるZeonor、ＰＰＥと架橋成分であるＢＶＰＥをそれぞれ１：１の配合比で含み、更に樹脂成分の重量に対して１ｗｔ％の硬化触媒２５Ｂを含んでなる樹脂組成物を充填剤として用い積層したところ、多孔質ポリイミド同様の結果が得られ、多孔質アラミドフィルムの有効性を確認した。
【００８５】
【表２】

【００８６】
［実施例６］
実施例６は、実施例２で作製した両面板を積層して多層回路基板を作製した例である。
【００８７】
以下に本発明の多層プリント基板の作成例を図３の工程図に従い説明する。
【００８８】
（Ａ）銅箔１，フィルム層２，多孔質層３，低誘電正接接着層５からなる両面銅箔フィルム層付多孔質ポリイミドフィルム６の両面にフォトレジスト（日立化成製ＨＳ４２５）をラミネートして片面には配線パターンを露光し、現像，エッチング後、レジストを剥離して片面に配線パターン１１を形成し、配線付両面板１２を作製した。
【００８９】
（Ｂ）次に実施例５で作製した銅箔をエッチアウトしたプリプレグを配線付両面板１２で挟み、真空下，加熱，加圧して多層化し多層基板１３を作成した。加熱条件は１２０℃／３０分，１８０℃／１００分，プレス圧力１.５ＭＰａ の多段階加熱とした。
【００９０】
（Ｃ）多層基板１３の両面にフォトレジスト（日立化成製ＨＳ４２５）をラミネートして、所定の位置にドリル加工によりスルーホール（以下ＴＨ）１４を形成し、次いで実施例２で使用したワニスを塗布しＴＨ１４内面に拡散防止膜１５を形成させた。
【００９１】
（Ｄ）レジスト剥離後に両面板をめっき触媒のコロイド溶液に浸して、ＴＨ内、基板表面に触媒を付与し、めっき触媒の活性化処理の後、無電解めっき（日立化成製ＣＵＳＴ２０００）により、約１μｍの種膜を設けた。次いで両面板の端部に電極を設置して電解めっきによって銅箔及びスルー部分にめっき銅１６を約１８μｍ形成し、層間接続を行い多層回路基板１７を作製した。
【００９２】
本多層配線板を２００℃のハンダリフロー槽に１０分間，２８８℃ハンダ槽に１分保持したが、樹脂界面、配線の剥離等は生じなかった。また、配線を形成したサンプルについて、温度を−５０と１５０℃との間で上下させる熱サイクル試験を３０００サイクル実行したところ、配線切断および剥離等の不良が発生することはなかった。さらに、４０Ｖ印加、８５℃／８５％高温高湿中でマイグレーション試験を行ったところ、表面配線及びＴＨ配線間の絶縁性は１０００時間後でも問題はなかった。
【００９３】
本発明の多層基板は誘電正接が小さく、熱膨張係数がＣｕと同等である基板を使用しているため、信頼性が高く、高周波回路に適用しても伝送損失が小さくすることができる。また、両面板の段階で任意の配線パターンを形成しこれらを一括して積層するためプロセスの簡略化が可能で低コスト化できる。さらに、多孔質層を使用しているため表面配線及びＴＨ配線間のマイグレーションに問題が発生する可能性があるが、フィルム層の付与及びＴＨ内面に低誘電正接拡散防止膜を形成しているので伝送特性を低下することなくマイグレーションを防止することができる。
【００９４】
［実施例７］
実施例７は、実施例５で作製した銅箔付プリプレグを積層して多層配線基板を作製した例である。
以下に本発明の多層プリント基板の作成例を図４の工程図に従い説明する。
【００９５】
（Ａ）銅箔，多孔質ポリイミドフィルム，低誘電正接充填物からなる片面銅箔付多孔質ポリイミドフィルムの銅箔面にフォトレジスト(日立化成製ＨＳ４２５)をラミネートして配線パターンを露光し、現像，エッチング後、レジストを剥離して片面に配線パターン１１を形成し、配線付プリプレグ１８を作製した。
【００９６】
（Ｂ）次に配線付プリプレグ１８を配線パターンを形成していない銅箔付プリプレグで挟み、真空下、加熱，加圧して多層化し多層基板１３を作成した。加熱条件は１２０℃／３０分，１８０℃／１００分，プレス圧力１.５ＭＰａ の多段階加熱とした。
【００９７】
（Ｃ）多層基板１３の両面にフォトレジスト（日立化成製ＨＳ４２５）をラミネートして、所定の位置にドリル加工によりスルーホール（以下ＴＨ）１４を形成させた。このとき通常は多孔質層は低誘電正接充填物が充填されているためメッキ工程での残留物の問題はないが、場合によってはプリプレグから充填物が層間に染み出した際に多孔質層の空孔が再現する。この場合は実施例６同様に拡散防止膜を形成して多孔質層内へのメッキ液浸入の防止処理を行っても良い。
【００９８】
（Ｄ）レジスト剥離後に両面板をめっき触媒のコロイド溶液に浸して、ＴＨ内、基板表面に触媒を付与し、めっき触媒の活性化処理の後、無電解めっき（日立化成製ＣＵＳＴ２０００）により、約１μｍの種膜を設けた。次いで両面板の端部に電極を設置して電解めっきによって銅箔及びスルー部分にめっき銅１６を約１８μｍ形成し、層間接続を行い多層回路基板１７を作製した。
【００９９】
本多層配線板を２００℃のハンダリフロー槽に１０分間、２８８℃ハンダ槽に１分保持したが、樹脂界面、配線の剥離等は生じなかった。また、配線を形成したサンプルについて、温度を−５０と１５０℃との間で上下させる熱サイクル試験を３０００サイクル実行したところ、配線切断および剥離等の不良が発生することはなかった。さらに、４０Ｖ印加、８５℃／８５％高温高湿中でマイグレーション試験を行ったところ、表面配線及びＴＨ配線間の絶縁性は１０００時間後でも問題はなかった。
【０１００】
本発明の多層基板は誘電正接が小さく、熱膨張係数がＣｕと同等である基板を使用しているため、信頼性が高く、高周波回路に適用しても伝送損失が小さくすることができる。また、片面板の段階で任意の配線パターンを形成しこれらを一括して積層するためプロセスの簡略化が可能で低コスト化できる。さらに、多孔質層に低誘電正接樹脂を含浸しているため伝送特性を低下することなくマイグレーションを防止することができる。
【０１０１】
［実施例８］
実施例８は、本発明の多層配線基板をアンテナに適用した例を示す。以下、図面を参照して本発明の実施の形態を詳細に説明する。
【０１０２】
図５は、本発明のアンテナ素子一体型高周波回路モジュールの要部断面構造を示す断面図である。本実施例は、５ＧＨｚ帯の円偏波の信号を送受信するためのアンテナ素子一体型高周波回路モジュールである。図１に示すように、本実施例のアンテナ素子一体型高周波回路モジュールは、矩形の基板１９，ＭＭＩＣを用いて構成した高周波回路モジュール２０、並びにディスクリート部品２１で構成される。高周波回路モジュール２０は、図示しないがガラスセラミクスを用いた多層基板により作製したパッケージに、ＧａＡｓ半導体を用いて作製したMMICチップが積層されて構成される。ＭＭＩＣチップは、スイッチ、低雑音増幅器、電力増幅器、ミキサ、逓倍器などを構成する。これらのＭＭＩＣチップ間を接続する配線などはガラスセラミクスのパッケージ内に設けられており、また、MMICチップは、ワイヤボンディングでパッケージ内に設けられた配線と接続されている。また、バンドパスフィルタ，フェーズロックループ（ＰＬＬ）モジュール，水晶発振器は、ディスクリート部品２１で構成される。基板１９は、銅箔からなる３層の導体層と、２層の誘電体層（２２，２３）から形成されており、各導体層は、上から順に、アンテナ素子２４，接地電極２５，配線２６として使用され、配線２６がクロスする部分はジャンパー配線２９によって接続される。アンテナ素子一体化高周波回路モジュールは外部接続端子３０により外部と接続される。
【０１０３】
第３の導体層には、複数の配線２６、即ち、高周波回路モジュール２０への電源供給線，高周波回路モジュール２０とディスクリート部品２１および外部回路をつなぐための配線、並びにアンテナ素子２４と高周波回路モジュール２０を接続するための配線などが形成される。アンテナ素子２４と、配線２６の一部はビアホール２７によって接続される。また、配線２６と同じ導体層に形成されたパタンの一部と接地電極２５とは、ビアホール２８により電気的接続されて、前記配線２６と同じ導体層に形成されたパタンの一部は接地電極２５と同電位になるように構成される。
【０１０４】
本実施例において、基板１９を構成する誘電体層２２の厚さと、誘電体層２３の厚さとは異なっている。アンテナに必要とされる帯域や利得などによって、誘電体層２２の厚さは適宜変化させる。また、誘電体層２３の厚さも、アンテナ素子一体型高周波回路モジュールの全体の厚さ、あるいは、配線２６の幅が所望の値になるように、適宜変化させる。本実施例で使用する誘電体層は本発明の多孔質配線板を使用しており、低誘電正接であり伝送損失を小さくすることができる。
【０１０５】
また本実施例で基板１９は、３層の導体層と２層の誘電体層により構成されているが、誘電体層２２と誘電体層２３は電気的特性を変化させることができる。特に、誘電体層２２と誘電体層２３は比誘電率を変化させ、誘電体層２３の比誘電率を大きくすることが有効である。
【０１０６】
本実施例において、誘電体層２３上に銅箔を用いて４分の１波長の配線を形成する場合、その長さは誘電体層２３の比誘電率によって変化し、比誘電率が大きいほど配線パタンとしての長さは短くなる。したがって、本実施例では、４分の１波長の配線パタンを短くして、アンテナ素子一体型高周波回路モジュールを小型化するために、比誘電率の大きな誘電体層２３を用いている。一方、アンテナの電気的特性は、一般に誘電体層２２の比誘電率が小さいほうが良くなるため、誘電体層２２は誘電体層２３よりも比誘電率の小さいものを用いている。
【０１０７】
このように、本実施の形態では、基板１９を比誘電率が異なる誘電体層２２と誘電体層２３を用いて構成することにより、アンテナの特性が良く、かつ小型のアンテナ素子一体型高周波回路モジュールを実現することができる。なお誘電体層の誘電率を変化させる場合は、低誘電率材料には実施例１〜３で作製した多孔質ポリイミドを使用しており、伝送損失を小さくすることができる。一方、高誘電体層には実施例４，５で作製した多孔質に低誘電樹脂物を充填したものを使用する。また、酸化物高誘電体粒子を多孔質層に充填し、高誘電体層とすることもできる。多孔質体を使用することで多孔質層内に充填物の種類や充填量を制御することで自由に誘電体層の誘電率を操作することができ、回路基板の設計を簡略化できる。
【０１０８】
以上説明した実施例によれば、作製工程において不揮発性で、溶解性及び各種樹脂との相溶性に優れ、その上、硬化後の誘電率及び誘電正接が低く、耐熱性及び柔軟性が良好な架橋剤を含む樹脂組成物を接着剤または充填材に用い、多層化が容易で、誘電率，誘電正接が小さく、機械的強度が高く、配線切断等を防止でき信頼性が高い構造の高周波用多孔質ポリイミドフィルム、および高周波用多孔質ポリイミド回路基板を得ることできる。
【０１０９】
【発明の効果】
本発明によれば、低誘電正接，高強度，低熱膨張の耐熱性多孔質樹脂配線基板を得ることができる。
【図面の簡単な説明】
【図１】低誘電正接接着層を有した両面板を現わす模式図である。
【図２】低誘電正接樹脂含浸プリプレグを現わす模式図である。
【図３】図１の両面板を使用した多層配線板作製時のプロセスを現わす模式図である。
【図４】図２の両面板を使用した多層配線板作製時のプロセスを現わす模式図である。
【図５】アンテナ素子一体高周波モジュールを現わす断面図である。
【符号の説明】
１…銅箔、２…フィルム層、３…多孔質層、４…片面銅箔フィルム層付多孔質ポリイミドフィルム、５…低誘電正接接着層、６…両面銅箔フィルム層付多孔質ポリイミドフィルム、７…多孔質ポリイミドフィルム、８…銅箔付き多孔質ポリイミドフィルム、９…低誘電正接充填物、１０…プリプレグ、１１…配線パターン、１２…配線付両面板、１３…多層基板、１４…ＴＨ、１５…拡散防止膜、１６…メッキ銅、１７…多層回路基板、１８…配線付プリプレグ、１９…基板、２０…高周波回路モジュール、２１…ディスクリート部品、２２，２３…誘電体層、２４…アンテナ素子、２５…接地電極、２６…配線、２７，２８…ビアホール、２９…ジャンパー配線、３０…外部接続端子。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a printed wiring board with low dielectric loss, a laminated board with a conductor, a prepreg, a method for producing a laminated board, and an electronic component using them, in order to cope with high-frequency signals.
[0002]
[Prior art]
In recent years, the signal band of information communication devices such as PHS and mobile phones, and the CPU clock time of computers have reached the GHz band, and higher frequencies are advancing. The dielectric loss of an electrical signal is proportional to the product of the square root of the dielectric constant of the insulator forming the circuit, the dielectric loss tangent and the frequency of the signal used. Therefore, the higher the frequency of the signal used, the greater the dielectric loss. Since the dielectric loss attenuates the electrical signal and impairs the reliability of the signal, in order to suppress this, it is necessary to select a material having a small dielectric constant and dielectric loss tangent for the insulator. Removal of polar groups in the molecular structure is effective in reducing the dielectric constant and dielectric loss tangent of insulators. Fluorine resin, curable polyolefin, cyanate ester resin, curable polyphenylene oxide, allyl-modified polyphenylene ether, divinyl A polyetherimide modified with benzene or divinylnaphthalene has been proposed.
[0003]
A fluororesin represented by polytetrafluoroethylene (PTFE) has a low dielectric constant and dielectric loss tangent, and is used as a substrate material for handling high-frequency signals. However, since PTFE is a thermoplastic resin, it has a large expansion / contraction during molding and is difficult to handle. Various proposals for imparting crosslinkability and solubility to fluororesins have also been made, but these materials are generally expensive and many of them do not reach PTFE in terms of characteristics. In contrast, various non-fluorine-based low dielectric constant and low dielectric loss tangent resins that are soluble in organic solvents and easy to handle have been studied. For example, a glass cloth impregnated with a diene polymer such as polybutadiene described in JP-A-8-208856 and cured with a peroxide; as disclosed in JP-A-10-158337, an epoxy group is added to a norbornene addition type polymer. Examples of cyclic polyolefins to which curability is imparted by introducing a cyano group; examples in which cyanate esters, diene polymers and epoxy resins are heated to form a B stage as described in JP-A-11-124491; JP-A-9-118759 Examples of modified resins composed of polyphenylene oxide, diene polymers and triallyl isocyanate; Examples of resin compositions composed of allylated polyphenylene ether and triallyl isocyanate described in JP-A-9-246429; described in JP-A-5-156159 Polyetherimide with styrene and divinylben An example of alloying styrene or divinylnaphthalene; a resin composition comprising, for example, hydroquinone bis (vinylbenzyl) ether and a novolak phenol resin synthesized by a Williamson reaction from a dihydroxy compound described in JP-A-5-78552 and chloromethylstyrene There are many examples. Many of the foregoing examples stated that divinylbenzene may be included as a crosslinking agent or crosslinking aid. This is because divinylbenzene does not have a polar group in the structure, the cured product has a low dielectric constant and dielectric loss tangent, and a high thermal decomposition temperature of 350 ° C. or higher. However, since the divinylbenzene cured product is very brittle, it has a drawback that the cured product is easily cracked during curing. Therefore, the amount of divinylbenzene added is usually set lower than other resin components. Even in the example of JP-A-5-156159 using divinylbenzene as the main crosslinking agent, the addition amount is about 9% of the whole resin. The divinylnaphthalene described in the publication also has the same problem as divinylbenzene in terms of the brittleness of the cured product. Further, since divinylbenzene has volatility, it has a drawback that it is difficult to control the properties of the cured product because it is volatilized during curing. On the other hand, JP-A-5-78552 discloses that bisstyrene compounds such as hydroquinone bis (vinylbenzyl) ether are non-volatile and give a highly flexible cured product. However, in general, an alkylene ether group is disadvantageous in terms of dielectric constant, dielectric loss tangent, and heat resistance as compared with an alkylene group and an arylene group. A hydrocarbon-based skeleton such as an alkylene group or an arylene group is preferable for the structure that bonds styrene groups. Examples of polyfunctional styrene compounds in which styrene groups are bonded with ethylene groups include 1,2-bis (vinylphenyl) ethane described in JP-A-9-208625, Makromol. Chem. vol.187, page 23 (1986), there is a divinylbenzene oligomer having a vinyl group in the side chain. However, in these reports, the mechanical strength, heat resistance, dielectric constant or dielectric loss tangent has not been studied.
[0004]
On the other hand, the dielectric properties of materials such as polyimide and the above-mentioned low dielectric loss tangent resin composition, whose thermal expansion coefficients are in good agreement with the Cu wiring material, have unique values for each material determined by its molecular structure. There are limits to controlling In view of this, many porous materials have been reported in which low dielectric constant (= 1) air is included in the material to make it porous to control dielectric properties such as polyimide.
[0005]
Japanese Patent Laid-Open No. 2000-154273 discloses that a nanopore, that is, a hole having a diameter of nm is formed by supercritical carbon dioxide gas, and 400 m ² A low dielectric property is obtained by using a porous material having a high surface area of at least / g. Japanese Laid-Open Patent Publication No. 2001-123953 is provided with a skin layer, and Japanese Laid-Open Patent Publication No. 2001-126534 is obtained by laminating a film layer (non-porous layer) to obtain a low dielectric material having increased strength. Japanese Patent Application Laid-Open No. 9-046012 obtains a porous material in which a porous film and Cu are joined with an epoxy adhesive having low dielectric properties.
[0006]
[Problems to be solved by the invention]
Conventionally, divinylbenzene, which has been used as a cross-linking agent that can lower the dielectric constant and dielectric loss tangent of a composition containing it, has drawbacks such as volatility and brittleness of the cured product. Was.
[0007]
When the porous material is made porous, the strength of the film decreases. Further, as described in Japanese Patent Application Laid-Open No. 2000-319442, when the porous layer has continuous holes, the etching solution penetrates through the continuous holes when forming a circuit pattern by etching, and Cu Since the wiring material such as is etched also from the film side, it becomes difficult to form the wiring as designed. Furthermore, in this conventional example, there is no consideration for the difference in thermal expansion coefficient between the Cu wiring material and the film.
[0008]
When a skin layer or a film layer is laminated on a polyimide film, wiring etching from the film side can be prevented during etching. However, when polytetrafluoroethylene, polyethylene or the like is used, the thermal expansion coefficients of the Cu wiring material and the film do not coincide with each other, which causes problems such as cutting of the wiring.
[0009]
An object of the present invention is to provide a heat-resistant porous resin wiring board having a low dielectric loss tangent, high strength, and low thermal expansion.
[0010]
[Means for Solving the Problems]
The present invention includes the following inventions.
[0011]
The present invention includes the following general formula:
[0012]
[Chemical 1]

[0013]
(Wherein R represents a hydrocarbon skeleton, R ¹ Are the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms; ² , R ^Three And R ^Four May be the same or different and each represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, m represents an integer of 1 to 4, and n represents an integer of 2 or more. And a resin composition containing a cross-linking component having a plurality of styrene groups having a weight average molecular weight of 1000 or less and a high molecular weight material, and a heat-resistant porous wiring board using an adhesive or a filler.
[0014]
As described above, the cured product of divinylbenzene has high heat resistance and low dielectric constant and dielectric loss tangent. According to the present invention, the weight average molecular weight having a plurality of styrene groups is
It became clear that a resin composition containing a non-volatile hydrocarbon skeleton crosslinking component of 1000 or less and a high molecular weight substance does not crack during curing, and gives a cured product having a low dielectric constant and dielectric loss tangent. Since the styrene groups are bonded with a flexible hydrocarbon skeleton such as an alkylene group, no cracking occurs during curing.
[0015]
The heat resistant porous resin film may be composed of a laminated film in which two or more film layers and porous layers are laminated. Further, the pores of the heat resistant porous resin film may be impregnated with an adhesive.
[0016]
The present invention relates to a double-sided wiring board having a configuration in which a heat-resistant porous resin film is laminated via an adhesive and interlayer wirings are connected via electrodes formed in through-holes. It is a heat-resistant porous double-sided wiring board which is a tangent resin composition. The heat-resistant porous double-sided wiring board having a low dielectric loss tangent resin composition coating film on the inner surface of the through hole. The porous polyimide double-sided wiring board of the present invention can be a heat-resistant porous substrate bonded and laminated with the low dielectric resin adhesive.
[0017]
The low dielectric constant, low dielectric loss tangent multilayer substrate material of the present invention can reduce high frequency transmission loss. In addition, the coefficient of thermal expansion has almost the same value as that of the Cu wiring material, and an electronic component having excellent reliability can be provided. Furthermore, the stacking process is simple and the cost of electronic components can be reduced.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
The resin composition used in the present invention and the cured product thereof will be described.
[0019]
The resin composition used in the present invention is a resin composition containing a cross-linking component having a weight average molecular weight of 1000 or less having a plurality of styrene groups represented by the above general formula (Chemical Formula 1), and a high molecular weight substance, The glass transition temperature of a cured product obtained by curing the resin composition at 180 ° C. for 100 minutes is preferably 170 ° C. or higher, or the elastic modulus of the cured product at 170 ° C. is 500 MPa or higher.
[0020]
In the present specification, the glass transition temperature is the peak of tan δ, which is the ratio of loss elastic modulus to storage elastic modulus, when dynamic viscoelastic properties are observed under the condition of a heating rate of 5 ° C./min. Temperature. By using a printed circuit board in which the resin composition used in the present invention has a low dielectric constant and dielectric loss tangent, a high glass transition temperature, and a high elastic modulus at high temperatures combined with porous polyimide, the dielectric loss of electric signals can be reduced. It is possible to suppress the deformation in a processing process at a high temperature such as gold wire bonding and soldering.
[0021]
In the above formula, the hydrocarbon skeleton represented by R is not particularly limited as long as the weight average molecular weight of the crosslinking component is 1000 or less. That is, the hydrocarbon skeleton represented by R is a substituent in the styrene group, R ¹ , R ² , R ^Three And R ^Four Although it can select suitably according to the presence or absence and its magnitude | size, and the number of m and n, generally it is C1-C60, Preferably it is C2-C30. The hydrocarbon skeleton represented by R may be either linear or branched, and may contain one or more ring structures such as an alicyclic structure and an aromatic ring structure, and further vinylene. , And may contain an unsaturated bond such as ethynylene.
[0022]
Examples of the hydrocarbon skeleton represented by R include ethylene, trimethylene, tetramethylene, methyltrimethylene, methyltetramethylene, pentamethylene, methylpentamethylene, cyclopentylene, cyclohexylene, phenylene, phenylenediethylene, xylylene, 1 -Phenylene-3-methylpropenylene and the like.
[0023]
In the above formula, R ¹ The hydrocarbon group represented by the formula is a linear or branched alkyl group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl. , Isobutyl, s-butyl, pentyl, hexyl, decyl, eicosyl; linear or branched alkenyl groups having 2 to 20 carbon atoms, preferably 2 to 10 carbon atoms, such as vinyl, 1-propenyl, 2- Propenyl, 2-methylallyl; aryl groups such as phenyl, naphthyl, benzyl, phenethyl, styryl, cinnamyl.
[0024]
In the above formula, since n is an integer of 2 or more, R ¹ Are present, and when m is an integer of 2 to 4, R ¹ There are multiple, but such multiple R ¹ May be the same or different, and the bonding position may be the same or different.
[0025]
In the above formula, R ² , R ^Three Or R ^Four Examples of the alkyl group represented by the formula include linear or branched alkyl groups having 1 to 6 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and hexyl.
[0026]
In the above formula, an optionally substituted vinyl group [(R ^Three ) (R ^Four ) C = C (R ² )-] Is preferably present in the meta or para position relative to R on the benzene ring.
[0027]
As the crosslinking component used in the present invention, a polyfunctional monomer having a plurality of optionally substituted styrene groups and having a weight average molecular weight of 1000 or less is preferable. Styrene groups are highly reactive and have a very low dielectric constant and dielectric loss tangent. It is preferable to adopt a hydrocarbon skeleton as the skeleton of the crosslinking component from the viewpoint of dielectric constant and dielectric loss tangent. This makes it possible to impart non-volatility and flexibility to the crosslinking component without impairing the low dielectric constant and low dielectric loss tangent of the styrene group. In addition, by selecting a crosslinking component having a weight average molecular weight of 1000 or less, melt flowability is exhibited at a relatively low temperature and solubility in an organic solvent is improved, so that molding and varnishing are facilitated. If the weight average molecular weight of the cross-linking component is too large, melt flowability is lowered, and cross-linking may occur during molding processing, resulting in poor molding. Although there will be no restriction | limiting if the weight average molecular weight of this crosslinking component is 1000 or less, Preferably it is 200-500.
[0028]
Preferred examples of the crosslinking component include 1,2-bis (p-vinylphenyl) ethane, 1,2-bis (m-vinylphenyl) ethane, 1- (p-vinylphenyl) -2- (m-vinylphenyl). ) Ethane, 1,4-bis (p-vinylphenylethyl) benzene, 1,4-bis (m-vinylphenylethyl) benzene, 1,3-bis (p-vinylphenylethyl) benzene, 1,3-bis (M-vinylphenylethyl) benzene, 1- (p-vinylphenylethyl) -4- (m-vinylphenylethyl) benzene, 1- (p-vinylphenylethyl) -3- (m-vinylphenylethyl) benzene And divinylbenzene polymer having vinyl group in side chain
(Oligomer) and the like. Two or more of these crosslinking components can be used in combination.
[0029]
As a method for synthesizing a crosslinking component preferably used in the present invention, Japanese Patent Application Laid-Open No. Hei 11-
A method of coupling halogenoalkyl styrene synthesized by the method described in JP 60519 A with various halides by Grignard reaction, Makromol.
Chem. vol. The synthesis method of the divinylbenzene oligomer which has a vinyl group in the side chain of 187, 23 pages (1986) is mentioned, However, It is not limited to these. The cross-linking component thus obtained cross-links at a relatively low temperature of 180 ° C. or lower without adding a curing catalyst, and gives a cured product having high heat resistance and low dielectric constant and dielectric loss tangent. However, when the crosslinking component is used alone without being combined with a high molecular weight material, tack-free properties when prepreg is obtained may not be obtained, or sufficient mechanical strength may not be obtained after curing. is there.
[0030]
The present invention is characterized in that the tack-free property and the mechanical strength of the cured product are improved by combining the above-mentioned crosslinking component and high molecular weight substance. The high molecular weight substance used in the present invention has a glass transition temperature of 170 ° C. or higher, or
It is preferably a soluble polymer having an elastic modulus at 170 ° C. of 500 MPa or more and easily varnished, and has a glass transition temperature of 170 to 300 ° C. or an elastic modulus at 170 ° C. of 500 to 3000 MPa. Is more preferable. When the high molecular weight body is curable, the glass transition temperature after curing is preferably 170 ° C or higher, or the elastic modulus at 170 ° C is preferably 500 MPa or higher, and the glass transition temperature after curing is 170 to 300. It is more preferable that the elastic modulus at 150 ° C is 500 to 3000 MPa. Specific examples of such high molecular weight compounds include butadiene, isoprene, styrene, methyl styrene, ethyl styrene, divinyl benzene, acrylate esters (eg, methyl acrylate, butyl acrylate, phenyl acrylate, etc.), acrylonitrile. , N-phenylmaleimide homopolymers and copolymers, polyphenylene oxides optionally having substituents, polyolefins having an alicyclic structure, and the like, but are not limited thereto. Since the crosslinking component used in the present invention is soluble in most organic solvents, it can be mixed with various high molecular weight substances to obtain a uniform varnish. Examples of the organic solvent include ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; aromatic hydrocarbons such as toluene and xylene; amides such as N, N-dimethylformamide and N, N-dimethylacetamide; Examples include ethers, ethers such as ethylene glycol monomethyl ether, propylene glycol monomethyl ether, tetrahydrofuran and dioxane, and alcohols such as methanol, ethanol and isopropanol. These organic solvents are used alone or in combination of two or more. be able to. Rubber-like components such as butadiene, isoprene and acrylic acid ester impart flexibility and adhesion to the cured product of the resin composition containing the rubber component, and impart smoothness to the coating film. Styrene, ethylstyrene, and / or acrylonitrile has a function of improving the heat resistance of the cured product by copolymerizing with the above rubbery component. By using divinylbenzene and / or N-vinylphenylmaleimide, a high molecular weight product having a functional group in the side chain can be synthesized by a known ionic polymerization method. In particular, N-vinylphenylmaleimide can be easily copolymerized with various monomers because only maleimide groups are polymerized by anionic polymerization and only styrene groups are polymerized by cationic polymerization, and the glass transition temperature of the copolymer is high. . In addition, since the high molecular weight body having a functional group in the side chain reacts with the crosslinking component, the resin composition containing the high molecular weight body and the crosslinking component is suppressed in phase separation after curing and gives a strong cured product. . Polyphenylene oxide and polyolefin having an alicyclic structure are heat resistant polymers, and by alloying with the cross-linking component, the cured product can be given flexibility and adhesiveness, and its mechanical strength can be improved. These high molecular weight substances may be used alone or in combination. For example, it is preferable to combine polyphenylene oxide and polybutadiene.
[0031]
The addition amount of the crosslinking component, the high molecular weight body and the filler contained in the resin composition used in the present invention is not particularly limited, but the crosslinking component is 5 to 95 parts by weight, the high molecular weight body is 95 to 5 parts by weight, the filling It is preferable to add the agent in the range of 70 to 5 parts by weight. Within the above composition range, the composition can be selected depending on the purpose such as imparting film formability, improving strength, reducing the thermal expansion coefficient, adjusting the dielectric constant, reducing the weight and improving the adhesion with the plated wiring by surface roughening. Can be adjusted. More preferable composition is 50 to 95 parts by weight of the crosslinking component, 50 to 5 parts by weight of the high molecular weight material, and 70 to 5 parts by weight of the filler, and more preferable composition is 50 to 80 parts by weight of the crosslinking component. The high molecular weight body is 50 to 20 parts by weight, and the filler is 70 to 5 parts by weight, and even when a high molecular weight body having no crosslinkable functional group is used according to this composition range, the solvent resistance of the cured product is also obtained. Is preserved.
[0032]
Although the resin composition used in the present invention can be cured only by heating without adding a curing catalyst, a curing catalyst capable of polymerizing styrene groups can be added for the purpose of improving curing efficiency. The addition amount is not particularly limited, but since the residue of the curing catalyst may adversely affect the dielectric properties, 0.0005 to 10 weights per 100 weight parts of the total of the crosslinking component and the high molecular weight material. It is desirable to be a part. By adding the curing catalyst within the above range, the polymerization reaction of the styrene group is promoted, and a strong cured product can be obtained at a low temperature. Examples of curing catalysts that generate cation or radical active species capable of initiating polymerization of styrene groups by heat or light are shown below. As a cationic polymerization initiator, BF _Four , PF ₆ , AsF ₆ , SbF ₆ Diallyl iodonium salt, triallyl sulfonium salt and aliphatic sulfonium salt having a counter-anion as a counter anion, SP-70,172, CP-66 manufactured by Asahi Denka Kogyo, CI-2855,2823 manufactured by Nippon Soda, manufactured by Sanshin Chemical Industry Commercial products such as SI-100L and SI-150L can be used. As radical polymerization initiators, benzoin compounds such as benzoin and benzoin methyl, acetophenone compounds such as acetophenone and 2,2-dimethoxy-2-phenylacetophenone, thioxanthone compounds such as thioxanthone and 2,4-diethylthioxanthone Compounds, bisazide compounds such as 4,4'-diazidochalcone, 2,6-bis (4'-azidobenzal) cyclohexanone and 4,4'-diazidobenzophenone, azobisisobutylnitrile, 2,2-azobispropane , Azo compounds such as m, m'-azoxystyrene and hydrazone, and 2,5-dimethyl-2,5-di (t-butylperoxy) hexane and 2,5-dimethyl-2,5-di ( t-butylperoxy) hexyne-3, dicumylpa Organic peroxides such as oxides. In particular, it is desirable to add an organic peroxide or a bisazide compound that can cause hydrogen abstraction of a compound having no functional group and cause crosslinking between the crosslinking component and the high molecular weight substance.
[0033]
A polymerization inhibitor may be added to the resin composition used in the present invention in order to increase storage stability. The addition amount is preferably in a range that does not significantly impair the dielectric properties and reactivity during curing, and is 0.0005 to 5 parts by weight with respect to 100 parts by weight of the total of the crosslinking component and the high molecular weight body. It is desirable to do. When the polymerization inhibitor is added within the above range, an excessive crosslinking reaction during storage can be suppressed, and no significant curing failure is caused during curing. Examples of the polymerization inhibitor include quinones such as hydroquinone, p-benzoquinone, chloranil, trimethylquinone, 4-t-butylpyrocatechol, and aromatic diols.
[0034]
The heat resistant porous resin film used in the present invention will be described below. In the present invention, heat-resistant porous resin materials such as polyimide, aramid, polysanphone, polyethersulfone, polyetheretherketone, polybenzoxazole, polyphenylenesulfide, syndiotactic polystyrene, polyethernitrile, and polytetrafluoroethylene Can be used. However, in the case of a porous polyimide film, it is preferable to mainly use sBPDA as the aromatic tetracarboxylic dianhydride and PPD and DDE as the aromatic diamine. Even when a polyimide made with this composition is made porous, the physical properties such as mechanical strength, dielectric properties and thermal expansion are good. Further, the porous polyimide film has a structure described by the following formula a, R is a porous polyimide film having a structure of the following formulas b and c, and b / (b + c) is 0.8 to 1.0. It is preferable to do.
[0035]
[Chemical 2]

[0036]
[Chemical 3]

[0037]
[Formula 4]

[0038]
Polyimide is synthesized by imidization from an aromatic tetracarboxylic dianhydride and an aromatic diamine via a polyamic acid. There are many combinations of aromatic tetracarboxylic dianhydrides and aromatic diamines, and the packing coefficient of the synthesized polyimide differs depending on the combination.
[0039]
Here, the packing coefficient (K) is Polymer. Sci. USSR, 12,556 (1970), proposed by Slonimskii and Askadskii, and obtained by dividing the intrinsic volume (Vint) of the molecular chain by the actual molar volume (Vtrue) obtained from the density.
K = Vint / Vtrue = NAΣΔVi / (M / d)
NA: Avogadro's number
ΔVi: true volume of constituent atoms
M: Molecular weight
d: Density
Is defined as follows.
[0040]
Making it porous reduces and improves the dielectric constant and dielectric loss tangent, while reducing the mechanical strength of the polyimide film. Therefore, unless the mechanical strength of the polyimide film is made as high as possible without being made porous, sufficient mechanical strength cannot be realized when it is made porous.
[0041]
Increasing the packing factor generally improves the mechanical strength. On the other hand, physical properties such as thermal expansion coefficient and elongation may cause problems if the packing coefficient is too large. When the packing coefficient is increased, the elongation and thermal expansion coefficient are reduced, matching with Cu wiring having flexibility and thermal expansion coefficient is deteriorated, and reliability may be lowered. Therefore, it is necessary to optimize the combination of aromatic diamine and aromatic tetracarboxylic dianhydride. In the present invention, sBPDA (biphenyltetracarboxylic dianhydride) is used as the aromatic tetracarboxylic dianhydride, PPD (paraphenylenediamine) and DDE (4,4′-diaminodiphenyl ether) are used as the aromatic diamine, The PPD composition ratio is 100% to 80% in terms of mol%. In this composition, matching between Cu wiring and thermal expansion coefficient, dielectric characteristics are good, and strength is sufficient.
[0042]
The solvent is not particularly limited as long as it dissolves the polymer, and examples thereof include N-methylpyrrolidone and γ-butyrolactone.
[0043]
As a method for forming the porous layer, there are various film forming methods such as a wet coagulation method, a dry coagulation method, and a stretching method. Among them, according to the wet coagulation method, an open-cell porous membrane can be obtained and is preferable.
[0044]
In the wet coagulation method, in general, a film-forming stock solution (dope) in which a resin and additives are dissolved in a solvent is prepared, and this is coated (cast) on a substrate and immersed in the coagulation solution to replace the solvent. Is coagulated (gelled), and then the coagulating liquid and the like are removed by drying to obtain a porous layer.
[0045]
A non-porous film layer or porous layer can also be formed directly on the copper foil.
[0046]
The dope in the wet coagulation method is preferably applied in the temperature range of -20 to 40 ° C. The coagulation liquid is not limited as long as it does not dissolve the resin to be used and is compatible with the solvent. Water, alcohols such as methanol, ethanol and isopropyl alcohol, and a mixed solution thereof are used, and water is particularly often used. The temperature of the coagulation liquid at the time of immersion is not particularly limited. Preferably, it is the temperature range of 0-50 degreeC.
[0047]
The polymer concentration of the film forming stock solution is preferably in the range of 5% by weight to 25% by weight. In particular, in order to obtain a porous molded body having superior strength, the polymer concentration is 7% by weight or more and has a high porosity. In order to obtain a molded product, the content is more preferably 20% by weight or less. If the concentration is too high, the viscosity becomes too high and handling becomes difficult, and if the concentration is too low, a porous film cannot be formed.
[0048]
An inorganic substance such as lithium nitrate or an organic substance such as polyvinyl pyrrolidone can be added for controlling the pore shape and the pore diameter. The concentration of the additive is preferably 1 to 10% by weight in the solution. When lithium nitrate is added, the replacement speed of the solvent and the coagulating liquid is high, and a finger void structure (structure having voids in a finger shape) can be formed in the sponge structure. When an additive such as polyvinyl pyrrolidone that slows the coagulation speed is added, a porous layer having a sponge structure uniformly spread can be obtained.
[0049]
The dope is applied to a certain thickness and immersed in a coagulation liquid such as water to solidify, or left in a water vapor atmosphere to solidify, and then immersed in water to remove the solvent and become porous. Become a layer. After forming the porous layer, the porous layer is taken out from the coagulation liquid and dried. The drying temperature is not particularly limited. Drying at 200 ° C. or lower is desirable.
[0050]
The formed porous layer and film layer are finally heat-treated at 200 to 500 ° C., and the precursor (polyamic acid) is heated and closed to be polyimide.
[0051]
By the above means, a porous molded body having a high porosity of about 50 to 85% can be formed on the copper foil.
[0052]
In the present invention, a multilayer substrate can be produced by using the low dielectric loss tangent resin composition as an adhesive or filler. When used as an adhesive, a single-sided copper foil-attached porous polyimide film is adhered to produce a double-sided wiring board. The double-sided wiring board is prepared by bonding a porous polyimide film with a single-sided copper foil. Next, the copper foil can be etched to form a surface wiring, and a prepreg can be sandwiched and heated and pressed to be laminated. Next, after forming a through hole, a wiring can be formed in the through hole and interlayer connection can be performed to form a multilayer substrate. Ordinary photolithography can be used to form the surface wiring. The formation of the through hole is processed by a drill, a laser or the like. If the pores of the porous material are continuous holes and there is a concern about the ingress of liquid, the inner surface of the through hole is coated with a varnish used as a filler to form a diffusion prevention film to prevent liquid from entering the pores. . This diffusion prevention film prevents impurities from entering, and a highly reliable multilayer substrate can be produced by a simple cleaning process. Wiring for interlayer connection can be formed by a plating process or paste filling. The conditions for the press working depend on the resin composition. For example, when cyclic polyolefin is used as the high molecular weight material, it is preferably molded at 120 to 180 ° C. and 1.0 to 5 MPa for 1 to 3 hours.
[0053]
A multilayer substrate using a varnish as a filler is prepared by impregnating a porous polyimide film without a copper foil and a porous polyimide film with a single-sided copper foil with the varnish, drying it, and using it as a prepreg. Generally, a prepreg is obtained by impregnating a resin cloth into a glass cloth or a nonwoven fabric. Glass cloth and non-woven fabric have problems such as sag and agglomeration during press processing, and may have a non-uniform composition in a fine region. Therefore, there is no particular limitation on the porous polyimide film used as the base material of the prepreg, but preferably the pore diameter is 0.5 μm or less, the porosity is 30% or more, more preferably the pore diameter is 0.2 to 0.2. The porosity is 40 to 70% at 5 μm. Within this range, the composition of the filler and polyimide is sufficiently uniform even in a fine region, and variations in electrical characteristics after wiring formation can be reduced. When the pore diameter is smaller than 0.2 μm, cleaning becomes difficult when an etching solution or a plating solution enters. Etching solution, plating solution, etc. easily enter the pores. When the pore diameter is small, the drying speed of the liquid is fast and solids such as salt in the liquid are precipitated in the pores. Once deposited, it becomes difficult to clean and remains in the porous film, resulting in deterioration of electrical characteristics.
[0054]
A prepreg is produced by immersing a porous polyimide film with a single-sided copper foil serving as a base material in a varnish produced using a low dielectric loss tangent resin composition, and then drying it. Although the drying conditions after the impregnation depend on the resin composition, for example, when toluene is used as a solvent, it is preferably dried at 80 to 130 ° C. for about 30 to 90 minutes.
[0055]
In the prepreg of the present invention, the dielectric constant and dielectric loss tangent can be arbitrarily set by changing the filling rate of the filler.
[0056]
The prepreg with copper foil of the present invention forms a multilayer by etching a copper foil to form a surface wiring, laminating and heat-pressing, forming a through hole, forming a wiring in the through hole, and performing interlayer connection to form a multilayer substrate Can be created. In addition, the prepreg with copper foil of the present invention forms a multilayer substrate by integrally etching a copper foil to form a surface wiring, further forming a via hole, forming a wiring in the via hole, and then laminating and hot pressing. can do. Ordinary photolithography can be used to form the surface wiring. Through holes and via holes are formed by drills, lasers, and the like. If the pores are not completely filled into the pores of the porous material, and there is a concern about liquid intrusion at the continuous pores, coat the varnish to be used as a filler on the inner surface of the through hole, A diffusion preventing film may be formed. This diffusion prevention film prevents impurities from entering, and a highly reliable multilayer substrate can be produced by a simple cleaning process. Wiring for interlayer connection can be formed by a plating process or paste filling. The conditions of the press working depend on the resin composition. For example, when cyclic polyolefin is used as the high molecular weight body, it is preferably molded at 120 to 180 ° C. and 1.0 to 5 MPa for 1 to 3 hours.
[0057]
Since the multilayer substrate thus obtained has a low dielectric loss tangent, the multilayer substrate has a small dielectric loss. The multilayer substrate of the present invention can provide a highly reliable multilayer substrate having the same thermal expansion coefficient as that of Cu.
[0058]
(Example)
EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these. In the following description, “parts” refers to parts by weight unless otherwise specified.
[0059]
Tables 1 and 2 show the compositions and characteristics of the examples of the present invention. The name of the reagent used, the synthesis method, the preparation method of the varnish, the production method of the porous polyimide film, the production method of the double-sided plate, and the evaluation method of the cured product will be described below.
[0060]
(1) Synthesis of 1,2-bis (vinylphenyl) ethane (BVPE)
1,2-bis (vinylphenyl) ethane (BVPE) was synthesized by a known method as shown below. In a 500 ml three-necked flask, 5.36 g (220 mmol) of granular magnesium for Grignard reaction (manufactured by Kanto Chemical Co., Inc.) was taken, and a dropping funnel, a nitrogen introducing tube and a septum cap were attached. The whole system was heated and dehydrated with a dryer while stirring the magnesium particles with a stirrer under a nitrogen stream. 300 ml of dry tetrahydrofuran was taken into a syringe and injected through a septum cap. After cooling the solution to −5 ° C., vinyl benzyl chloride using a dropping funnel
30.5 g (200 mmol) (VBC, manufactured by Tokyo Chemical Industry Co., Ltd.) was added dropwise over about 4 hours. After completion of the dropwise addition, stirring was continued at 0 ° C./20 hours. After completion of the reaction, the reaction solution was filtered to remove residual magnesium and concentrated with an evaporator. The concentrated solution was diluted with hexane, washed once with a 3.6% hydrochloric acid aqueous solution and three times with pure water, and then dehydrated with magnesium sulfate. The dewatered aqueous solution was purified by passing through a short column of silica gel (Wakogel C300 manufactured by Wako Pure Chemical Industries) / hexane and vacuum dried to obtain BVPE. Obtained
BVPE was a mixture of mm body (liquid), mp body (liquid), and pp body (crystal), and the yield was 90%. ¹ When the structure was examined by H-NMR, the value was consistent with the literature value (6H-vinyl: α-2H, 6.7, β-4H, 5.7, 5.2; 8H-aromatic: 7.1 ~ 7.35; 4H-methylene: 2.9). this
BVPE was used as a crosslinking component.
[0061]
(2) Other reagents
The following are used as other high molecular weight substances and crosslinking components.
[0062]
High molecular weight body;
Zeonor: A product made by Nippon Zeon, cyclic polyolefin (Zeonor1600R)
PPE: manufactured by Aldrich, poly-2,6-dimethyl-1,4-phenylene oxide
Alicyclic acrylate: Nippon Kayaku Co., Ltd., R-684
Curing catalyst;
25B: 2,5-dimethyl-2,5-bis (t-butylperoxy) hexyne-3 (perhexine 25B) manufactured by NOF
(3) Preparation method of varnish
A varnish of a resin composition was prepared by dissolving a predetermined amount of a high molecular weight substance, a crosslinking component, a curing catalyst, and the like in chloroform or carbon disulfide.
[0063]
(4) Production of porous polyimide film with single-sided copper foil
In a glove box capable of nitrogen flow, aromatic diamines PPD and DDE mixed at a predetermined ratio were added to N-methylpyrrolidone and stirred at room temperature. Next, 1 mol of sBPDA, which is an acid anhydride, was added to 1 mol of aromatic diamine and stirred in a nitrogen flow for about 1 hour to obtain a polyamic acid solution having a solid content of 10 wt%.
[0064]
The obtained polyamic acid solution was applied to a copper foil having a thickness of 18 μm, immersed in a coagulation tank containing water, and contacted with water to gel (coagulate). This was taken out, sufficiently dried at 120 ° C., further processed at 400 ° C. for 30 minutes to be imidized, a porous polyimide film was formed on the copper foil, and a single-sided copper foil-attached porous polyimide film with a copper foil was prepared. . The porosity was 65% and the pore diameter was about 0.2 μm.
[0065]
(5) Production of porous aramid film
Aromatic polyamide (manufactured by Teijin Limited, Conex) was dissolved in N-methyl-2-pyrrolidone (NMP) to obtain a polymer solution of aromatic polyamide (100 parts by weight) and NMP (900 parts by weight).
[0066]
This was applied on a polypropylene film with a thickness of 190 μm and immersed in a water bath at 60 ° C. to form a porous film. Thereafter, it was stored in water for one day and night to remove the solvent.
[0067]
The obtained porous body had a sponge structure in which continuous pores having a thickness of 35 μm were formed. The average pore diameter was 2 μm and the porosity was 45%.
[0068]
(6) Production of porous polyimide film with single-sided copper foil film layer
A 10 wt% polyamic acid solution was applied to a copper foil having a thickness of 18 μm to form a film layer, sufficiently dried at 120 ° C., and further treated at 400 ° C. for 30 minutes in nitrogen to be imidized. Next, the polyamic acid solution was applied onto the film layer, immersed in a coagulation tank containing water, and contacted with water to gel (coagulate). This is taken out, dried sufficiently at 120 ° C., further processed at 400 ° C. in nitrogen for 30 minutes to be imidized, a porous polyimide film is formed on the film layer, and a porous polyimide film with a single-sided copper foil film layer is created. did.
[0069]
The porosity including the film layer was 52%, and the pore diameter of the porous layer was about 0.2 μm.
[0070]
(7) Production of porous polyimide film with double-sided copper foil film layer
This will be described below in accordance with the method for producing the double-sided board shown in FIG. In this process, the varnish is used as an adhesive and the porous polyimide film with a single-sided copper foil film layer is used as a porous polyimide film with a double-sided copper foil film layer.
(A) Application of adhesive
A low dielectric loss tangent adhesive layer 5 was formed by applying a varnish to the porous layer surface of the porous polyimide film 4 with a single-sided copper foil film layer comprising the copper foil 1, the film layer 2, and the porous layer 3.
(B) Formation of porous polyimide film with double-sided copper foil film layer
A porous polyimide film 4 with a single-sided copper foil film layer on which a low dielectric loss tangent adhesive layer is formed and a porous polyimide film with a single-sided copper foil film layer on which an adhesive layer is not formed are bonded together, and are subjected to vacuum under a polyimide film and a mirror plate. Then, the porous polyimide film 6 with a double-sided copper foil film layer was produced by heating and pressurizing and bonding. The heating conditions were 120 ° C./30 minutes and 180 ° C./100 minutes, and the press pressure was 1.5 MPa.
[0071]
(8) Production of porous aramid film with double-sided copper foil
A method for creating a double-sided board will be described. In this process, the varnish is used as an adhesive to bond a copper foil and a porous aramid film to form a porous aramid film with double-sided copper.
(A) Application of adhesive
The porous aramid film was peeled off from the polypropylene film used as a base material at the time of film formation, and varnish was applied to the taken out porous aramid film and then dried to form low dielectric loss tangent adhesive layers on both surfaces.
(B) Formation of porous aramid film with double-sided copper foil
Adhesive layered porous aramid film with low dielectric loss tangent adhesive layer is bonded with copper foil on top and bottom, and bonded with heat and pressure under vacuum through polyimide film and end plate, porous aramid film with double-sided copper foil Was made. The heating conditions were 120 ° C./30 minutes and 180 ° C./100 minutes, and the press pressure was 1.5 MPa.
[0072]
(9) Preparation of polyimide prepreg
The polyimide prepregs produced in the examples were all produced by impregnating a porous polyimide film or a porous polyimide film with a single-sided copper foil using the varnish of the resin composition as a filler. The prepreg production will be described with reference to FIG.
(A) Production of porous polyimide film with single-sided copper foil
A polyamic acid solution having a solid content of 10 wt% was applied to a copper foil 1 having a thickness of 18 μm, immersed in a coagulation tank containing water, and contacted with water to gel (coagulate). This was taken out and sufficiently dried at 120 ° C., and further imidized by treatment at 400 ° C. for 30 minutes in nitrogen to form a porous polyimide film 7 on the copper foil 1. Created. When using with the copper foil removed, FeCl _Three The copper foil was etched out using a / HCl etching solution and washed with dilute HCl and water to obtain a porous polyimide film.
(B) Filling varnish
Apply a sufficient amount of varnish to the porous polyimide film with single-sided copper foil or the porous surface of the porous polyimide film, suck it in a vacuum device and impregnate the varnish in the porous layer, and make the low dielectric loss tangent filler 9 porous The polyimide film 7 was filled. Then
The prepreg 10 was produced by drying at 90 ° C. for 60 minutes and heat treatment at 120 ° C. for 1 hour.
[0073]
(10) Preparation of aramid prepreg
All the aramid prepregs produced in the examples were produced by impregnating a porous aramid film with the varnish of the resin composition as a filler.
[0074]
The porous aramid film was peeled off from the polypropylene film used as a base material at the time of film formation, and the taken porous aramid film was filled with varnish and then dried to form low dielectric loss tangent adhesive layers on both sides.
[0075]
A sufficient amount of varnish was applied to the porous aramid film, sucked in a vacuum apparatus, impregnated with the varnish in the porous layer, and filled with a low dielectric loss tangent filler in the porous aramid film. Subsequently, it dried at 90 degreeC for 60 minute (s), and heat-processed at 120 degreeC for 1 hour, and produced the aramid prepreg.
[0076]
(11) Measurement of dielectric constant and dielectric loss tangent
The dielectric constant and dielectric loss tangent were measured at 10 GHz by a cavity resonator perturbation method (Agilent Technology 8722ES network analyzer, Kanto Electronics Application Development cavity resonator).
[0077]
(12) Measurement of tensile strength
Tensile strength was measured using a Shimadzu AGS-100 type tensile tester using a sample with a width of 2 mm and a length of 70 mm under conditions of room temperature, distance between fulcrums of 20 mm, and tensile speed of 10 mm / min.
[0078]
(13) Adhesion and peel strength
A sample for measuring adhesion and peel strength was prepared by forming a resin layer on each rough surface of an electrolytic copper foil (18 μm) under the same conditions as in the method for preparing a resin plate. The resin layer had a thickness of 2 mm and a size of 70 × 70 mm. The electrolytic copper foil on the resin layer was cut into a width of 10 mm, and its adhesion and peel strength were measured.
[0079]
(14) Measurement of thermal expansion coefficient
The thermal expansion coefficient was measured using a TMA, a sample having a width of 5 mm and a length of 25 mm, and a temperature increase rate of 2 ° C./min.
[0080]
[Examples 1 to 3]
Examples 1 to 3 are examples of a substrate in which a porous polyimide film was bonded and laminated with a low dielectric loss tangent resin, and each of Zeonor, PPE, polyvinyl benzyl ether, which is a high molecular weight substance, and BVPE, which is a cross-linking component, 1 1 is an example in which a resin composition containing 1 wt% of a curing catalyst 25B with respect to the weight of the resin component is used as an adhesive. The cured product of these compositions is an example in which a varnish was prepared using sulfur disulfide as a solvent and a double-sided board was produced by the above-described method. As is clear from each example shown in Table 1, the dielectric constant and dielectric loss tangent of each resin plate are very low, the dielectric constant is 2.15 to 2.30, and the dielectric loss tangent is 0.0019 to 0.30. 0028. The other properties reflect the properties of the added high molecular weight material, with a tensile strength of 90 to 115 MPa, a thermal expansion coefficient of 16 to 20 ppm / ° C., peel and adhesive strength of 0.8 to 1.2 N / m and excellent values. showed that. It was confirmed that a low dielectric loss tangent, high strength, and low thermal expansion laminate can be made from a porous polyimide film using a low dielectric loss tangent adhesive.
[0081]
In addition, using a porous aramid film, like the porous polyimide film, it contains Zeonor, PPE, polyvinyl benzyl ether, which is a high molecular weight substance, and BVPE, which is a crosslinking component, in a mixing ratio of 1: 1, respectively, and further the weight of the resin component When a resin composition containing 1 wt% of the curing catalyst 25B was laminated as an adhesive, results similar to porous polyimide were obtained, confirming the effectiveness of the porous aramid film.
[0082]
[Table 1]

[0083]
[Examples 4 and 5]
Examples 4 and 5 are examples of a substrate in which a porous polyimide film is filled with a low dielectric loss tangent resin, and each contains a high molecular weight Zeonor, PPE, and a crosslinking component BVPE in a mixing ratio of 1: 1. Furthermore, this is an example in which a resin composition containing 1 wt% of the curing catalyst 25B with respect to the weight of the resin component is used as a filler. Cured products of these compositions were prepared as double-sided boards by the above-described method by preparing varnishes using sulfur disulfide as a solvent. As is clear from each example, the dielectric constant and dielectric loss tangent of the resin composition were very low, the dielectric constant was 3.23 and 3.31, and the dielectric loss tangent was 0.0025 and 0.000028. Other properties reflect the properties of the added high molecular weight material, with excellent tensile strength of 120,135 MPa, thermal expansion coefficient of 17,19 ppm / ° C., peel and adhesive strength of 0.8, 1.1 N / m. showed that. It was confirmed that a low dielectric loss tangent, high strength, and low thermal expansion filled substrate can be produced from a porous polyimide film using a low dielectric loss tangent adhesive.
[0084]
Also, using a porous aramid film, similarly to the porous polyimide film, it contains high molecular weight Zeonor, PPE and crosslinking component BVPE at a mixing ratio of 1: 1, respectively, and further 1 wt. When the resin composition containing 25% of the curing catalyst 25B was laminated as a filler, the same result as that of porous polyimide was obtained, and the effectiveness of the porous aramid film was confirmed.
[0085]
[Table 2]

[0086]
[Example 6]
Example 6 is an example in which the double-sided board produced in Example 2 was laminated to produce a multilayer circuit board.
[0087]
An example of producing a multilayer printed board according to the present invention will be described below with reference to the process diagram of FIG.
[0088]
(A) A photoresist (HS425 manufactured by Hitachi Chemical Co., Ltd.) is laminated on both sides of a porous polyimide film 6 with a double-sided copper foil film layer comprising a copper foil 1, a film layer 2, a porous layer 3, and a low dielectric loss tangent adhesive layer 5. The wiring pattern was exposed on one side, developed and etched, the resist was peeled off to form the wiring pattern 11 on one side, and a double-sided board 12 with wiring was prepared.
[0089]
(B) Next, the prepreg obtained by etching out the copper foil prepared in Example 5 was sandwiched between the double-sided boards 12 with wiring, and heated and pressed under vacuum to form a multilayer board 13. The heating conditions were 120 ° C./30 minutes, 180 ° C./100 minutes, and multistage heating with a press pressure of 1.5 MPa.
[0090]
(C) A photoresist (HS425 manufactured by Hitachi Chemical Co., Ltd.) is laminated on both surfaces of the multilayer substrate 13, and through holes (hereinafter referred to as TH) 14 are formed at predetermined positions by drilling, and then the varnish used in Example 2 is applied. Then, the diffusion prevention film 15 was formed on the inner surface of TH14.
[0091]
(D) After stripping the resist, immerse the double-sided plate in a colloidal solution of the plating catalyst, apply the catalyst to the substrate surface in TH, and after the activation treatment of the plating catalyst, by electroless plating (CUST2000 manufactured by Hitachi Chemical) A 1 μm seed film was provided. Next, electrodes were placed on the ends of the double-sided plates, and the plated copper 16 was formed on the copper foil and the through portion by electrolytic plating to a thickness of about 18 μm, and interlayer connection was made to produce a multilayer circuit board 17.
[0092]
This multilayer wiring board was held in a solder reflow bath at 200 ° C. for 10 minutes and in a 288 ° C. solder bath for 1 minute, but no resin interface, wiring peeling, etc. occurred. Moreover, when the thermal cycle test which raises / lowers the temperature between −50 and 150 ° C. was executed for the sample on which the wiring was formed, 3000 defects were not generated, such as wiring cutting and peeling. Furthermore, when a migration test was performed in the presence of 40 V and 85 ° C./85% high temperature and high humidity, the insulation between the surface wiring and the TH wiring had no problem even after 1000 hours.
[0093]
Since the multilayer substrate of the present invention uses a substrate having a small dielectric loss tangent and a thermal expansion coefficient equivalent to that of Cu, the reliability is high and transmission loss can be reduced even when applied to a high frequency circuit. In addition, since an arbitrary wiring pattern is formed at the stage of the double-sided board and these are laminated together, the process can be simplified and the cost can be reduced. In addition, since a porous layer is used, there may be a problem in migration between the surface wiring and the TH wiring. However, since a low dielectric loss tangent diffusion prevention film is formed on the inner surface of the film and the TH inner surface. Migration can be prevented without degrading transmission characteristics.
[0094]
[Example 7]
Example 7 is an example in which the prepreg with copper foil produced in Example 5 was laminated to produce a multilayer wiring board.
An example of producing the multilayer printed board according to the present invention will be described below with reference to the process diagram of FIG.
[0095]
(A) A photoresist (HS425 manufactured by Hitachi Chemical Co., Ltd.) is laminated on a copper foil surface of a porous polyimide film with a single-sided copper foil made of a copper foil, a porous polyimide film, and a low dielectric loss tangent filler, and a wiring pattern is exposed and developed. After etching, the resist was peeled off to form the wiring pattern 11 on one side, and a prepreg 18 with wiring was produced.
[0096]
(B) Next, the prepreg 18 with wiring was sandwiched between prepregs with a copper foil on which a wiring pattern was not formed, and was heated and pressed under vacuum to form a multilayer substrate 13. The heating conditions were 120 ° C./30 minutes, 180 ° C./100 minutes, and multistage heating with a press pressure of 1.5 MPa.
[0097]
(C) Photoresist (HS425 manufactured by Hitachi Chemical Co., Ltd.) was laminated on both surfaces of the multilayer substrate 13, and through holes (hereinafter referred to as TH) 14 were formed at predetermined positions by drilling. At this time, since the porous layer is usually filled with a low dielectric loss tangent filler, there is no problem of a residue in the plating process, but in some cases, when the filler oozes out from the prepreg, The holes are reproduced. In this case, a diffusion preventing film may be formed in the same manner as in Example 6 to prevent the plating solution from entering the porous layer.
[0098]
(D) After stripping the resist, immerse the double-sided plate in a colloidal solution of the plating catalyst, apply the catalyst to the substrate surface in TH, and after the activation treatment of the plating catalyst, electroless plating (Hitachi Chemical CUST2000) A 1 μm seed film was provided. Next, electrodes were placed on the ends of the double-sided plates, and the plated copper 16 was formed on the copper foil and the through portion by electrolytic plating to a thickness of about 18 μm, and interlayer connection was made to produce a multilayer circuit board 17.
[0099]
The multilayer wiring board was held in a solder reflow bath at 200 ° C. for 10 minutes and in a 288 ° C. solder bath for 1 minute, but no resin interface, wiring peeling, or the like occurred. Moreover, when the thermal cycle test which raises / lowers the temperature between −50 and 150 ° C. was executed for the sample on which the wiring was formed, 3000 defects were not generated, such as wiring cutting and peeling. Furthermore, when a migration test was performed in the presence of 40 V and 85 ° C./85% high temperature and high humidity, the insulation between the surface wiring and the TH wiring had no problem even after 1000 hours.
[0100]
Since the multilayer substrate of the present invention uses a substrate having a small dielectric loss tangent and a thermal expansion coefficient equivalent to that of Cu, the reliability is high and transmission loss can be reduced even when applied to a high frequency circuit. Further, since an arbitrary wiring pattern is formed at the stage of a single-sided plate and these are laminated together, the process can be simplified and the cost can be reduced. Furthermore, since the porous layer is impregnated with a low dielectric loss tangent resin, migration can be prevented without deteriorating transmission characteristics.
[0101]
[Example 8]
Example 8 shows an example in which the multilayer wiring board of the present invention is applied to an antenna. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0102]
FIG. 5 is a cross-sectional view showing a main-part cross-sectional structure of the antenna element integrated high-frequency circuit module of the present invention. This embodiment is an antenna element integrated high-frequency circuit module for transmitting and receiving circularly polarized signals in the 5 GHz band. As shown in FIG. 1, the antenna element integrated high-frequency circuit module of this embodiment includes a rectangular substrate 19, a high-frequency circuit module 20 configured using an MMIC, and a discrete component 21. Although not shown, the high-frequency circuit module 20 is configured by stacking an MMIC chip manufactured using a GaAs semiconductor on a package manufactured using a multilayer substrate using glass ceramics. The MMIC chip constitutes a switch, a low noise amplifier, a power amplifier, a mixer, a multiplier, and the like. Wiring and the like for connecting these MMIC chips are provided in a glass ceramic package, and the MMIC chip is connected to wiring provided in the package by wire bonding. The bandpass filter, the phase-locked loop (PLL) module, and the crystal oscillator are composed of discrete components 21. The substrate 19 is formed of three conductor layers made of copper foil and two dielectric layers (22, 23). Each conductor layer is arranged in order from the top, the antenna element 24, the ground electrode 25, and the wiring. 26, and the part where the wiring 26 crosses is connected by a jumper wiring 29. The antenna element integrated high-frequency circuit module is connected to the outside by an external connection terminal 30.
[0103]
The third conductor layer includes a plurality of wirings 26, that is, power supply lines to the high-frequency circuit module 20, wiring for connecting the high-frequency circuit module 20, the discrete component 21, and an external circuit, and the antenna element 24 and the high-frequency circuit module. Wiring or the like for connecting 20 is formed. The antenna element 24 and a part of the wiring 26 are connected by a via hole 27. A part of the pattern formed in the same conductor layer as the wiring 26 and the ground electrode 25 are electrically connected by a via hole 28, and a part of the pattern formed in the same conductor layer as the wiring 26 is connected to the ground electrode. 25 and the same potential.
[0104]
In this embodiment, the thickness of the dielectric layer 22 constituting the substrate 19 is different from the thickness of the dielectric layer 23. The thickness of the dielectric layer 22 is changed as appropriate according to the bandwidth and gain required for the antenna. Further, the thickness of the dielectric layer 23 is also appropriately changed so that the entire thickness of the antenna element integrated high-frequency circuit module or the width of the wiring 26 becomes a desired value. The dielectric layer used in this embodiment uses the porous wiring board of the present invention, has a low dielectric loss tangent, and can reduce transmission loss.
[0105]
In this embodiment, the substrate 19 is composed of three conductor layers and two dielectric layers. However, the dielectric layer 22 and the dielectric layer 23 can change electrical characteristics. In particular, it is effective to increase the relative dielectric constant of the dielectric layer 23 by changing the relative dielectric constant of the dielectric layer 22 and the dielectric layer 23.
[0106]
In this embodiment, when a quarter-wavelength wiring is formed on the dielectric layer 23 using copper foil, the length varies depending on the relative dielectric constant of the dielectric layer 23, and the larger the relative dielectric constant, the greater the relative dielectric constant. The length as the wiring pattern is shortened. Therefore, in this embodiment, the dielectric layer 23 having a large relative dielectric constant is used in order to shorten the wiring pattern of the quarter wavelength and to reduce the size of the antenna element integrated high-frequency circuit module. On the other hand, since the electrical characteristics of the antenna are generally better when the dielectric layer 22 has a smaller relative dielectric constant, the dielectric layer 22 having a relative dielectric constant smaller than that of the dielectric layer 23 is used.
[0107]
As described above, in the present embodiment, the substrate 19 is configured using the dielectric layer 22 and the dielectric layer 23 having different relative dielectric constants, so that the antenna characteristics are good and the small antenna element integrated high-frequency circuit is provided. Modules can be realized. In the case where the dielectric constant of the dielectric layer is changed, the porous polyimide produced in Examples 1 to 3 is used as the low dielectric constant material, and transmission loss can be reduced. On the other hand, as the high dielectric layer, a porous material prepared in Examples 4 and 5 and filled with a low dielectric resin material is used. Alternatively, a high dielectric layer can be formed by filling a porous layer with oxide high dielectric particles. By using a porous body, the dielectric constant of the dielectric layer can be freely manipulated by controlling the type and amount of filler in the porous layer, and the design of the circuit board can be simplified.
[0108]
According to the embodiment described above, it is non-volatile in the production process, excellent in solubility and compatibility with various resins, and has a low dielectric constant and dielectric loss tangent after curing, and good heat resistance and flexibility. A resin composition containing a crosslinking agent is used for adhesives or fillers, making it easy to multilayer, high dielectric strength, low dielectric loss tangent, high mechanical strength, preventing wiring breakage, etc., and high reliability A porous polyimide film and a high-frequency porous polyimide circuit board can be obtained.
[0109]
【The invention's effect】
According to the present invention, a heat-resistant porous resin wiring board having a low dielectric loss tangent, high strength, and low thermal expansion can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a double-sided board having a low dielectric loss tangent adhesive layer.
FIG. 2 is a schematic view showing a low dielectric loss tangent resin impregnated prepreg.
FIG. 3 is a schematic view showing a process for producing a multilayer wiring board using the double-sided board of FIG. 1;
4 is a schematic view showing a process for producing a multilayer wiring board using the double-sided board of FIG. 2;
FIG. 5 is a cross-sectional view showing an antenna element integrated high-frequency module.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Copper foil, 2 ... Film layer, 3 ... Porous layer, 4 ... Porous polyimide film with single-sided copper foil film layer, 5 ... Low dielectric loss tangent adhesive layer, 6 ... Porous polyimide film with double-sided copper foil film layer, DESCRIPTION OF SYMBOLS 7 ... Porous polyimide film, 8 ... Porous polyimide film with copper foil, 9 ... Low dielectric loss tangent filling, 10 ... Pre-preg, 11 ... Wiring pattern, 12 ... Double-sided board with wiring, 13 ... Multi-layer substrate, 14 ... TH, DESCRIPTION OF SYMBOLS 15 ... Diffusion prevention film, 16 ... Plated copper, 17 ... Multi-layer circuit board, 18 ... Prepreg with wiring, 19 ... Substrate, 20 ... High frequency circuit module, 21 ... Discrete component, 22, 23 ... Dielectric layer, 24 ... Antenna element 25 ... ground electrode, 26 ... wiring, 27, 28 ... via hole, 29 ... jumper wiring, 30 ... external connection terminal.

Claims (16)

It has an adhesive, a heat-resistant porous resin film laminated via the adhesive, and a conductor layer formed on both sides or one side of the heat-resistant porous resin film, and the adhesive has the following general formula:

(Wherein, R represents a hydrocarbon skeleton, R ¹ represents the same or different, represent a hydrogen atom or a hydrocarbon group having a carbon number of 1 to 20, R ^2, R ³ and R ⁴ are the same or different And represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, m represents an integer of 1 to 4, and n represents an integer of 2 or more.)
A heat-resistant porous resin wiring board, which is a low dielectric loss tangent resin composition containing a cross-linking component having a weight average molecular weight of 1000 or less having a plurality of styrene groups and a high molecular weight substance. The heat-resistant porous resin wiring board according to claim 1, wherein the low dielectric loss tangent resin composition further contains at least one of a curing catalyst capable of polymerizing styrene groups and a polymerization inhibitor capable of suppressing polymerization of styrene groups. A heat-resistant porous resin wiring board. 3. The heat-resistant porous resin wiring board according to claim 2, wherein the addition amount of the curing catalyst is 0.0005 to 10 parts by weight with respect to a total of 100 parts by weight of the cross-linking component and the high molecular weight body, and the polymerization A heat-resistant porous resin wiring board characterized in that the addition amount of the inhibitor is 0.0005 to 5 parts by weight. 2. The heat resistant porous resin wiring board according to claim 1, wherein the high molecular weight substance is butadiene, isoprene, styrene, methylstyrene, ethylstyrene, divinylbenzene, acrylate ester, acrylonitrile, N-phenylmaleimide, N-vinyl. It is a polymer comprising at least one of phenylmaleimide and polyvinylbenzyl ether, polyphenylene oxide optionally having a substituent, and at least one resin selected from the group consisting of polyolefins having an alicyclic structure, Heat resistant porous resin wiring board. 2. The heat resistant porous resin wiring board according to claim 1, wherein the heat resistant porous resin film is a laminated film in which two or more film layers and a porous layer are laminated. substrate. 2. The heat resistant porous resin wiring board according to claim 1, wherein the adhesive is impregnated in pores of the heat resistant porous resin film. 2. The heat resistant porous resin wiring board according to claim 1, comprising a through hole formed in a predetermined position and an electrode formed in the through hole. . 8. The heat resistant porous resin wiring board according to claim 7, further comprising a coating film of the low dielectric loss tangent resin composition on the inner surface of the through hole. The heat-resistant porous resin multilayer wiring board according to claim 7, wherein the heat-resistant porous resin wiring board is laminated with an adhesive. A heat-resistant porous resin film is impregnated with a low dielectric loss tangent resin composition containing a crosslinking component having a weight average molecular weight of 1000 or less and having a plurality of styrene groups represented by the following general formula, and dried. A prepreg characterized by

(Wherein, R represents a hydrocarbon skeleton, R ¹ represents the same or different, represent a hydrogen atom or a hydrocarbon group having a carbon number of 1 to 20, R ^2, R ³ and R ⁴ are the same or different And represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, m represents an integer of 1 to 4, and n represents an integer of 2 or more.) A multilayer wiring board, wherein a conductor layer is provided on both sides or one side of the prepreg according to claim 10 or a cured product thereof. A method for producing a laminated wiring board, comprising: forming a through-hole electrode; etching a conductor layer; and forming a wiring; and laminating and heat-pressing the prepreg according to claim 11. An electronic component comprising the heat-resistant porous resin multilayer wiring board according to claim 1. The heat-resistant porous resin wiring board according to claim 1, wherein the heat-resistant porous resin film has a structure of the formula a, and R is a porous polyimide film having a structure of the following formulas b and c, b / (b + c) is 0.8 to 1.0, a heat-resistant porous resin wiring board.

2. The heat resistant porous resin wiring board according to claim 1, wherein the conductor layer is copper. A heat-resistant porous resin film, a filler filled in pores of the heat-resistant porous resin film, and a conductor layer formed on both sides or one side of the heat-resistant porous resin film, and the filling The agent has the following general formula:

(Wherein, R represents a hydrocarbon skeleton, R ¹ represents the same or different, represent a hydrogen atom or a hydrocarbon group having a carbon number of 1 to 20, R ^2, R ³ and R ⁴ are the same or different And represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, m represents an integer of 1 to 4, and n represents an integer of 2 or more.)
A heat-resistant porous resin wiring board, which is a low dielectric loss tangent resin composition containing a cross-linking component having a weight average molecular weight of 1000 or less having a plurality of styrene groups and a high molecular weight substance.

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