JP4017769B2 - Printed wiring board base material and manufacturing method thereof - Google Patents

Description

【００２６】
【化２】

【００２７】
【化３】

【００２８】
上記した溶融液晶性ポリエステルのうちでも、上記した化学式(１１)で表される、パラヒドロキシ安息香酸単位（Ｘ単位）と２−ヒドロキシ−６−ナフトエ酸単位からなる構造単位（Ｙ単位）の合計が６５モル％以上、特に８０モル％以上である溶融液晶性ポリエステルであることが好ましく、両単位の合計量に対して２−ヒドロキシ−６−ナフトエ酸単位の割合が５〜４５モル％である溶融液晶性ポリエステルよりなることが溶融紡糸性および繊維性能の点から特に好ましい。
【００２９】
Ａ成分、Ｂ成分およびＢ₀成分を構成する溶融液晶性ポリエステルには、本発明の効果を損なわない範囲で、必要に応じて、ポリエチレンテレフタレート、変性ポリエチレンテレフタレート、ポリオレフィン、ポリカーボネート、ポリアリレート、ポリアミド、ポリフェニレンサルファイド、ポリエステルエーテルケトン、ポリアリレート、フッ素含有樹脂など他のポリマーの１種または２種以上が含まれていてもよく、また酸化チタン、カオリン、シリカ、酸化バリウムなどの無機物、カーボンブラック、染料や顔料や染料などの着色剤、酸化防止剤、紫外線吸収剤、光安定剤などの各種添加剤の１種または２種以上が配合されていてもよい。繊維性能などの点からは、溶融液晶性ポリエステル以外の成分の含有量は、溶融液晶性ポリエステル繊維の重量に基づいて、５０重量％以下であることが好ましく、３０重量％以下であることがより好ましく、１０重量％以下であることが更に好ましい。
【００３０】
本発明で用いるＡ成分（主体繊維）の融点は、得られるプリント配線基板基材の耐熱性、寸法安定性、バインダーにおける孔形成性、製造工程性などの点から、２９０℃以上であることが必要であり、３００〜３９０℃であることが好ましく、３００〜３５０℃であることがより好ましい。
Ａ成分は、１種類の溶融液晶性ポリエステルを用いて得られる繊維であっても、または２種類以上の溶融液晶性ポリエステルを用いて得られる混合紡糸繊維、複合繊維、混繊繊維であってもよい。
【００３１】
２９０℃以上の融点を有するＡ成分（主体繊維）は、例えば溶融液晶性ポリエステルを溶融紡糸して紡糸原糸を製造し、それを熱処理して固相重合させることにより得られる。溶融液晶性ポリエステルを溶融紡糸した場合に、紡糸前後でのポリマーの分子量は実質的に変化しないが、紡糸して得られた繊維（紡糸原糸）を熱処理すると固相重合が生じて重合度が上がり、融点（耐熱性）および機械的性能などが顕著に高くなり、本発明で用いる主体繊維（Ａ成分）として好ましいものとなる。溶融紡糸により得られる紡糸原糸を構成する溶融液晶性ポリエステルは一般に８０〜１２０量体程度であるが、主体繊維（Ａ成分）は２５０〜３５０量体程度の溶融液晶性ポリエステルから構成されていることが好ましい。
【００３２】
紡糸原糸を主体繊維（Ａ成分）に変えるための熱処理条件（固相重合条件）は特に限定されないが、紡糸原糸を構成する溶融液晶性ポリエステルの融点（Ｔｍ）（℃）に対して、（Ｔｍ−６０℃）〜（Ｔｍ＋２０℃）の温度範囲で熱処理を行うことが好ましく、（Ｔｍ−４０℃）からＴｍまで徐々に昇温しながら熱処理（固相重合）を行うのがより好ましい。熱処理時の加熱方法としては、例えば加熱板や赤外線ヒーターなどからの輻射熱を利用する方法、熱ローラー、熱プレートなどに接触させる方法、高周波などを利用する内部加熱方法などを挙げることができる。熱処理は、緊張下に行ってもまたは無緊張下に行ってもよい。
【００３３】
前記熱処理時の雰囲気は特に制限されず、窒素ガス、炭酸ガスなどの不活性ガス雰囲気下、または空気のような酸素を含有する活性ガス雰囲気下で行うことができ、減圧下に行ってもよい。また、熱処理時に水分や湿分が存在すると繊維物性の低下するので、除湿したガスを用いることが好ましい。
【００３４】
主体繊維（Ａ成分）を製造するためのより具体的で且つ好適な方法としては例えば次の方法が挙げられる。例えば、パラヒドロキシ安息香酸単位（Ｘ単位）：２−ヒドロキシ−６−ナフトエ酸単位（Ｙ単位）の割合（モル比）が７３：２７、溶融粘度が４３０ポイズ、重合度１００程度、融点２８０℃程度の溶融液晶性ポリエステルを、１４０℃で１００時間真空乾燥した後、ベント付単軸押出機に供給し、サンド層と金属繊維よりなる平均孔径５μｍのフィルター層を通して濾過した後、紡糸口金（ノズル孔径０．０８ｍｍ、５０ホール）から３２０℃で紡出させて溶融液晶性ポリエステル繊維（紡糸原糸）（融点２８０℃）を製造し、この繊維を２８０〜３００℃で熱処理して固相重合を行わせて、その重合度を３００程度にまで上昇させることにより、主体繊維（Ａ成分）として好適な繊維を円滑かつ効率的に得ることができる。
【００３５】
主体繊維（Ａ成分）の形態は、フィラメント、カットファイバー、叩解物などのいずれでもよく特に限定されないが、抄造性、得られるプリント配線基板基材の機械的性能、樹脂含浸性などの点から、紡糸して得られた繊維をカットして得られるカットファイバーであることが好ましい。該カットファイバーでは、抄造性、紙力などの点から繊維径が５〜３０μｍおよび繊維長が２〜２０ｍｍであるのが好ましい。カットファイバーの形態で用いる場合は、融点を高めるための熱処理（固相重合）を、カットする前またはカットした後のいずれの段階で行ってもよい。
【００３６】
主体繊維（Ａ成分）の繊維強度は１６ｇ／ｄ以上であることが好ましく、１８ｇ／ｄ以上であることがより好ましく、２０ｇ／ｄ以上であることがさらに好ましい。繊維強度の上限値は特に限定されないが、製造コストなどの点からは繊維強度を５０ｇ／ｄ以下とするのが好ましい。主体繊維（Ａ成分）の弾性率は４００ｇ／ｄ以上であることが好ましく、５００〜２０００ｇ／ｄであることがより好ましい。
【００３７】
本発明のプリント配線基板基材の製造に当たっては、上記した主体繊維（Ａ成分）と共に、バインダー効果、バインダーにおける孔形成性の点から、融点が２９０℃未満、好ましくは２８０℃以下の溶融液晶性ポリエステルバインダー繊維（Ｂ₀成分）を用いる。得られるプリント配線基板基材の耐熱性の点からは、融点の高いバインダー繊維（Ｂ₀成分）を用いることが好ましいが、バインダー繊維（Ｂ₀成分）の融点が高すぎると、主体繊維（Ａ成分）に対するバインダー効果が低くなり、しかもバインダー繊維（Ｂ₀成分）を溶融しても樹脂の含浸に適する孔を有するフィルム状バインダー（Ｂ成分）が形成されにくくなり、得られるプリント配線基板基材の機械的性能および樹脂含浸性が低下する。そのため、良好な耐熱性、機械的性能および樹脂含浸性［フィルム状バインダー（Ｂ成分）における孔形成性］を兼ね備えたプリント配線基板基材を得るためには、溶融液晶性ポリエステルバインダー繊維（Ｂ₀成分）として融点が２６０〜２８０℃の範囲内のものを用いることが好ましく、２６０〜２７０℃の範囲内のものを用いることがより好ましい。前記した融点を有するバインダー繊維（Ｂ₀成分）を用いる場合は、抄造時にはバインダー繊維（Ｂ₀成分）の融点が低く優れたバインダー効果を発揮すると共に、溶融により粘度が十分に低下して樹脂の含浸に適する孔を有するフィルム状のバインダーとなり、次いでそれを熱処理して固相重合して融点２９０℃以上のフィルム状バインダー（Ｂ成分）とすることにより、耐熱性および機械的性能が顕著に向上したプリント配線基板基材が得られる。
【００３８】
融点２９０℃未満のバインダー繊維（Ｂ₀成分）としては、融点２９０℃未満の溶融液晶性ポリエステルを溶融紡糸して得られる原糸、すなわち溶融紡糸後に融点を上昇させるための熱処理（固相重合）が施されていない繊維などを用いることができる。
【００３９】
バインダー繊維(Ｂ₀成分)は、その名の示すとおり繊維状であることが必要である。バインダー(Ｂ₀成分)が粉末状または粒状であると、主体繊維（Ａ成分)とバインダー（Ｂ₀成分）とが均一に分散した湿式抄造物を得ることが困難になり、該湿式抄造物中のバインダーを溶融させても粘度が十分に低下しないためフィルム状バインダーとなりにくく、しかも該フィルム状バインダーに樹脂の含浸に適当な所定の孔が形成されず、本発明のプリント配線基板基材が得られない。
【００４０】
バインダー繊維（Ｂ₀成分）の繊維形態は特に限定されないが、抄造性、孔形成性などの点から微細なパルプ状物であることが好ましく、抄造性、バインダー性能、孔形成性がより良好になる点から、繊維径１〜７μｍ、特に１〜５μｍ、繊維長０．１〜３ｍｍ程度のパルプ状であることがより好ましい。パルプ状のバインダー繊維（Ｂ₀成分）は、微細で、抄造性、バインダー効果が高く、しかも互いに溶融一体化して容易にフィルムとなり且つ該フィルムに所定の孔が形成され易く、一層優れた効果を奏する。前記と同様の理由から、バインダー繊維(Ｂ₀成分）としては濾水度（ＣＦＳ；カナディアンスタンダードフリーネス値）が６００ｃｃ以下のものが好ましく用いられ、０〜５５０ｃｃのものがより好ましく用いられる。
【００４１】
パルプ状のバインダー繊維（Ｂ₀成分）は、溶融液晶性ポリエステル繊維、溶融液晶性ポリエステルからなるフィルムやその他の成形物、好ましくは溶融液晶性ポリエステルの紡糸原糸を、リファイナーなどで叩解・粉砕することにより製造でき、或いは溶融液晶性ポリエステルを１成分とする海島型複合繊維、貼合型複合繊維から、繊維を短繊維状にカットする前またはカットした後に溶剤、酸、アルカリ処理などを施して他の成分を除去することによっても製造できる。
本発明では、バインダー繊維（Ｂ₀成分）として、単繊維繊度５デニール以下の溶融液晶性ポリエステル繊維のカットファイバーを叩解・粉砕して得られるパルプ状繊維がより好ましく用いられる。
【００４２】
また、バインダー繊維（Ｂ₀成分）は、１種類の溶融液晶性ポリエステルの単独繊維であっても、或いは２種以上の溶融液晶性ポリエステルを用いて形成した混合紡糸繊維、複合繊維および／または混繊繊維であってもよい。
【００４３】
さらに、バインダー繊維（Ｂ₀成分）は、繊維強度５〜１５ｇ／ｄの溶融液晶性ポリエステル繊維または該繊維を叩解・粉砕したものであることが好ましい。さらに、バインダー繊維（Ｂ₀成分）の弾性率は２００〜６００ｇ／ｄ程度であることが好ましい。
【００４４】
本発明のプリント配線基板基材の製造方法は特に限定されないが、例えば以下の方法により好適に製造できる。
まず、上記した主体繊維（Ａ成分）とバインダー繊維（Ｂ₀成分）を少なくとも含む紙料を湿式抄造して抄造物をつくる。
その際の主体繊維（Ａ成分）：バインダー繊維（Ｂ₀成分）の配合比（重量比）は、抄造性、得られるプリント配線基板基材の機械的性能などの点から、２０：８０〜９０：１０とするのが好ましく、前記した特性と併せて孔形成性（樹脂含浸性）をより良好なものとするためには、前記配合比が２０：８０〜６０：４０であるのがより好ましい。バインダー繊維（Ｂ₀成分）の配合割合が小さすぎると主体繊維（Ａ成分）間の接着・固定が不十分になって抄造性および紙力が低下すると共に、樹脂の含浸に好適な孔を有するフィルム状バインダーが基材中に形成されにくくなる。すなわち、本発明のプリント配線基板基材を得るためには、バインダー繊維（Ｂ₀成分）の粘度が溶融により十分に低下し各バインダー繊維（Ｂ₀成分）が一体化してフィルム状になると共に該フィルム中に特定の孔が特定数で形成される必要があるが、バインダー繊維（Ｂ₀成分）が少な過ぎるとそれを溶融してもフィルム状バインダーとならず、しかも孔が形成されにくくなる。逆に主体繊維（Ａ成分）の配合割合が少なすぎると、得られるプリント配線基板基材の機械的性能、寸法安定性が不十分になり、またフィルム状バインダー中に特定の孔が形成されにくくなる。
【００４５】
また、抄造物の製造に用いる上記した紙料には、主体繊維（Ａ成分）およびバインダー繊維（Ｂ₀成分）以外の成分が含まれていてもよいが、本発明の効果を損なわないようにするために、紙料中の固形分の５０重量％以上、特に８０重量％、さらには９０重量％以上が主体繊維（Ａ成分）とバインダー繊維（Ｂ₀成分）からなることが好ましい。
さらに、紙料は、固形分濃度０．０１〜１重量％の水性分散液（水性懸濁液）の形態とすることが好ましい。
【００４６】
湿式抄造に当たっては、用いる湿式抄造機は特に限定されず、従来公知の装置を使用すればよい。具体的には、例えば、円網式湿式抄造機、短網式湿式抄造機、短網傾斜式湿式抄造機、長網式湿式抄造機のワイヤーとヤンキー、多筒式湿式抄造機、熱風または輻射熱式のドライヤーを備えた湿式抄造機などを挙げることができる。得られた湿式抄造物を乾燥することにより湿式不織布を製造することができるが、該湿式抄造物は通常６０％以上の高い空隙率を有しており、樹脂含浸性は良好であるが機械的性能が低く（通常裂断長０．２ｋｍ以下）、工程通過性に問題がある。そのため、本発明では、乾燥後の上記湿式抄造物を非加圧下に熱処理する必要があり、熱処理を行ってバインダー繊維（Ｂ₀成分）を溶融させて、湿式抄造物中に開口面積４００〜１００００μｍ²の孔を５個以上／ｍｍ²の割合で有するフィルム状バインダーを形成すると共に主体繊維（Ａ成分）間を固定する。バインダー繊維（Ｂ₀成分）を前記した特定の孔を有するフィルム状バインダーにすることによって樹脂含浸性に優れるプリント配線基板基材が得られる。このとき、バインダー繊維（Ｂ₀成分）から形成されたフィルム状バインダーを固相重合して融点を２９０℃以上にする（すなわちＢ成分にする）ことが必要である。該フィルム状バインダーの固相重合を行わないと、プリント配線基板基材の耐熱性が不十分になり、しかも主体繊維（Ａ成分）間の結合も強固にならず、本発明で目的とするプリント配線基板が得られない。
【００４７】
湿式抄造物に対する熱処理は、上述のように実質的に非加圧下に行う必要があり、従来広く行われている加圧を伴う熱プレス処理（熱カレンダー処理）を採用すると、紙力は高くなるものの、樹脂含浸性が大幅に低下して、目的とするプリント配線基板基材が得られない。
本発明でいう「非加圧下」とは、湿式抄造物に実質的に大きな圧力が加わらない状態をいい、かかる状態であればどのような方法で熱処理を行ってもよい。例えば、湿式抄造物の片面または両面を熱ローラーに接触させて連続的に加熱する方法などが挙げられる。このとき、湿式抄造物に対する練るローラーの線圧を小さくすることが必要であり、線圧０〜１０ｋｇ／ｃｍ程度にするのが好ましい。勿論、熱ローラーによる接触加熱方式に代えて、熱風などによる対流加熱方式、遠赤外線などによる輻射加熱方式などを採用してよく、これらの２種以上を併用しても構わない。具体的な熱処理条件は、主体繊維（Ａ成分）およびバインダー繊維（Ｂ₀成分）の種類、両者の配合割合などによって異なり得るが、一般的には、熱処理温度を２００〜４００℃、特に２６０〜３５０℃程度とするのが好ましく、熱処理時間は１０分から４８時間程度、特に１０〜４０時間程度とするのが好ましい。
【００４８】
バインダー繊維（Ｂ₀成分）を溶融させるための熱処理と固相重合のための熱処理は同一工程で行っても、または別工程で行っても構わないが、熱ローラー処理を行ってバインダー繊維（Ｂ₀成分）を溶融接着させた後、熱風処理を行って固相重合を行うのが好ましい。このときに、バインダー繊維（Ｂ₀成分）を溶融させるための熱処理は、［バインダー繊維（Ｂ₀成分）の融点（Ｔｍ）−１０℃］から［前記融点（Ｔｍ）＋１０℃］の範囲内の温度で、線速５〜３０ｍ／分で行うことが好ましく、また固相重合のための熱処理は、［前記融点（Ｔｍ）＋１０℃］から［前記融点（Ｔｍ）＋７０℃］の範囲内の温度で、熱処理時間１０〜３０時間の条件下に行うことが好ましい。前記した熱処理条件を採用することにより、樹脂含浸性、機械的性能などの諸性能に優れたプリント配線基板基材を効果的に製造できる。また、工程性などの点からは、湿式抄造物を低温（例えば１００〜１５０℃程度）で加熱して乾燥した後に、バインダー繊維（Ｂ₀成分）を溶融するための前記した熱処理を行うのが好ましい。
【００４９】
さらに、プリント配線基板には薄いことが要求されることから、バインダー繊維（Ｂ₀成分）を溶融させるための熱処理と固相重合させるための熱処理を行って得られるプリント配線基板基を、必要に応じてさらに低温プレス処理して厚さを減じてもよい。上記した溶融および固相重合のための熱処理によって基材の形態が安定されているので、低温プレス処理を行っても基材の樹脂含浸性を実質的に損なうことなく薄肉化できる。低温プレス処理の温度は０〜１４０℃、特に０〜１００℃であるのが好ましく、線圧は１００ｋｇ／ｃｍ以下、特に１〜５０ｋｇ／ｃｍであるのが好ましい。
【００５０】
また、得られたプリント配線基板基材は、それに含浸させる樹脂との接着性、樹脂による濡れ性などを向上させるために、必要に応じて物理的および／または科学的処理などを施してもよい。具体的には、コロナ放電処理、グロー放電処理、プラズマ処理、電子線照射処理、紫外線照射処理、酸素含有雰囲気中での熱処理などの物理的処理や、スパッタリングなどの化学的処理などが挙げられる。これらの２種以上の処理を併用してもよい。バインダー繊維（Ｂ₀成分）の溶融および／または固相重合を行うための熱処理を酸素含有雰囲気中で行った場合は、新たに別の処理を行うことなく、基材の樹脂との接着性、濡れ性を顕著に高めることができる。特に、酸素含有雰囲気中での熱処理、コロナ放電処理またはそれらの両方を行うと、基材の樹脂との接着性を効率的に高めることができ好ましい。
【００５１】
前記した酸素含有雰囲気中での熱処理を行うと、主体繊維（Ａ成分）の表面が酸化されてカルボキシル基などの極性基が表面に形成され、樹脂との接着性および濡れ性が向上する。この熱処理は２００〜４００℃、特に３００〜４００℃で１分以上行うのが好ましい。該熱処理時間は工程性の点からは３０時間以下であるのが好ましい。この熱処理は、バインダー繊維（Ｂ₀成分）の溶融および／または固相重合を目的として熱処理と同一工程で行ってもまたは別工程で行ってよい。
また、前記したコロナ放電処理を行う場合は、活性化効果および繊維の炭化を抑制する点から０．５〜３キロワットの条件下で行うのが好ましい。
【００５２】
上記により得られる本発明のプリント配線基板基材はそのままで流通、販売することができる。また、該基材に熱硬化性樹脂および／または熱可塑性樹脂（マトリックス樹脂）を含浸または付着してプリプレグを製造し、これを単層で用いるかまたは複数枚積層してプリント配線基板を製造することができる。
プリプレグの製造に用いる好適なマトリックス樹脂としては、例えば、フェノール樹脂、エポキシ樹脂、不飽和ポリエステル樹脂、シアナート樹脂、マレイミド樹脂、ポリイミド樹脂などから選ばれる１種または２種以上の熱硬化性樹脂が挙げられる。さらに、前記した熱硬化性樹脂の１種または２種にポリビニルブチラール、アクリロニトリル−ブタジエンゴム、多官能性アクリート化合物などを加えて変性したものや、架橋ポリエチレン、ビスマレイド−トリアジン系樹脂、架橋ポリエチレン変性エポキシ樹脂、架橋ポリエチレン変性シアナート樹脂、ポリフェニレンエーテル変性シアナート樹脂などをの熱可塑性樹脂で変性した熱硬化性樹脂（ＩＰＭ型またはセミＩＰＭ型のポリマーアロイ）などもマトリックス樹脂として用いることができる。なかでも、エポキシ樹脂、ポリイミド樹脂、不飽和ポリエステル樹脂、シアナート樹脂などがプリント配線基板のマトリックス樹脂として好適である。
また、主体繊維（Ａ成分）および／またはバインダー繊維（Ｂ₀成分）として、ｐ−ヒドロキシ安息香酸単位（Ｘ単位）と２−ヒドロキシ−６−ナフトエ酸単位（Ｙ単位）から主としてなる溶融異方性ポリエステルからなる繊維を用いる場合は、該繊維との接着性に優れ、且つ絶縁性、耐熱性などに優れるビスマレイド−トリアジン樹脂が、マトリックス樹脂として好ましく使用される。
【００５３】
該プリプレグにおけるマトリックス樹脂の含有量は特に制限されないが、層間剥離および成形不良を抑制し、かつプリント配線基板の機械的性能、寸法安定性、熱安定性を良好なものにする点から、プリプレグの全重量の３０〜９５重量％、特に４０〜８０重量％をマトリックス樹脂とするのが好ましい。
【００５４】
プリント配線基板基材への樹脂の含浸または付着方法は特に限定されず、従来公知の方法を用いればよい。例えば、含浸法、塗布法、転写法などを採用すればよい。具体的には、マトリックス樹脂を溶剤に溶解して調製したワニスを基材に含浸して乾燥する方法、溶剤を使用しないで調製した常温状態または加熱状態にある液状マトリックス樹脂を基材に含浸させる方法、粉末状のマトリックス樹脂を基材に固定する方法、離型性を有するフイルムやシートにマトリックス樹脂の層を形成した後にそれを基材に転写する方法などが採用できる。本発明のプリント配線基板基材は樹脂含浸性に優れていることから、プリント配線基板基材の全体に樹脂を含浸することができ、優れた効果が奏される。なお、基材に含浸または付着したマトリックス樹脂を乾燥させる場合は、縦型ドライヤーにより非接触状態で乾燥するのが好ましい。
【００５５】
かかる方法で得られたプリプレグを少なくとも１枚以上用いてプリント配線板を製造すればよい。具体的には、上記プリプレグの単層からなるプリント配線基板、上記プリプレグを２枚以上積層してなるプリント配線基板、上記プリプレグ１枚以上と他の材料（例えばガラスクロス、ガラス不織布、その他の繊維布帛や多孔質基材、プラスチックシート、プラスチックフイルム、プラスチック板など）を積層してなるプリント配線基板などが挙げられる。本発明の効果を十分に達成するためには、実質的に本発明のプリント配線基板基材に樹脂を含浸してなるプリプレグのみからプリント配線基板を構成するのが好ましく、その際に機械的性能、電気特性、加工性などを良好なものとするために該プリプレグを２〜５枚程度積層してプリント配線基板を製造するのがより好ましい。
【００５６】
かかるプリント配線基板に金属層を積層することによりプリント配線板が得られる。金属層は単層であってもまたは複数層形成されていてもよい。
金属層としては、金属箔、金属シート、金属板、金属網などが挙げられ、場合によってはこれらの２種以上を併用してもよい。また、金属層に表面処理などが施されていてもよい。金属層を構成する金属としては、銅、鉄、アルミニウムなどが好適であり、なかでも銅を用いるのが好ましい。勿論、前記した金属の２種以上を併用することもできる。金属層の厚さは、取り扱い性、電気特性などの点から１０〜５０μｍ程度とするのが好ましい。金属層とプリント配線基板との接着は、場合により接着剤を用いて行ってもよい。
【００５７】
プリント配線板の製造方法は特に限定されず、従来既知の方法と同様にして製造すればよい。例えば、本発明のプリント配線基板基材に樹脂を含浸したプリプレグを１枚または２枚以上用い、必要に応じてさらに他の材料も併用して、これらと金属層を重ね合わせて加圧加熱し、マトリックス樹脂を硬化および／または固化すると共に層間の接着を行って、目的とするプリント配線板を製造することができる。その際の加熱温度、圧力などはマトリックス樹脂の種類、積層する材料の種類、層数などに応じて適当な条件を採用すればよい。勿論、予め複数のプリプレグを積層一体化した後に金属層を積層一体化してもよい。
【００５８】
プリント配線板の厚さは、取り扱い性などの点から、０．２〜０．８ｍｍ程度であるのが好ましく、また比重は１．５以下、特に０．８〜１．４であるのが好ましい。さらに、電気特性の点からは、プリント配線板の誘電率は３．３以下、特に２．０〜３．２であるのが好ましく、また誘電正接は０．００９８以下、特に０．００８５〜０．００９５であるのが好ましい。
【００５９】
【実施例】
以下に実施例を挙げて本発明をさらに具体的に説明するが、本発明は以下の実施例に何ら限定されるものではない。また、実施例および比較例における各種物性の測定法または評価法を以下に示す。
【００６０】
［溶融液晶性ポリエステルの溶融粘度（ポイズ）］
溶融液晶性ポリエステルの粘度を、温度３００℃、剪断速度ｒ＝１０００ｓｅｃ^-1の条件下にキャピログラフ（東洋精機社製「キャピログラフ１Ｂ型」）を用いて測定した。
【００６１】
［融点（℃）］
上述のように、ＤＳＣ装置（例えばＭｅｔｔｌｅｒ社製「ＴＡ３０００］）に、サンプルを１０〜２０ｍｇ量り採ってアルミ製パンに封入した後、キャリヤーガスとして窒素を１００ｃｃ／分の流速で流し、２０℃／分で昇温したときの吸熱ピークを測定して求めた。１ｓｔ Ｒｕｎで明確な吸熱ピークが現れない場合は、５０℃／分の昇温速度で予想される流れ温度よりも５０℃高い温度まで昇温し、その温度で３分間完全に溶融した後、８０℃／分の降温速度で５０℃まで冷却し、しかる後に２０℃／分の昇温速度で吸熱ピークを測定した。
【００６２】
［繊維の強度（ｇ／ｄ）］
ＪＩＳ Ｌ１０１３に準じ、強伸度試験機（島津製作所製「強伸度試験機ＤＣＳ−１００型」）を用いて、試料長２０ｃｍ、初荷重０．１ｇ／ｄ、引張速度１０ｃｍ／分の条件で引張破断試験を行い、得られた応力−歪曲線から繊維の強度を求めた。５点以上の測定値の平均値を採用した。
【００６３】
［繊維の弾性率（ｇ／ｄ））］
ＪＩＳ Ｌ１０１３に準じ、強伸度試験機（島津製作所製「強伸度試験機ＤＣＳ−１００型」）を用いて、試料長２００ｍｍ、初荷重０．１ｇ／ｄ、引張速度１０ｃｍ／分の条件で引張破断試験を行い、得られた応力−歪曲線から、繊維の弾性率＝（ｗ／Ｄ）／（ΔＬ／Ｌ）により算出した。なお、ｗはΔＬ伸長したときの荷重（ｇ）、Ｄは繊維のデニール（ｄ）、ΔＬは荷重により伸長した長さ（ｍｍ）およびＬは繊維の元の長さ（２００ｍｍ）を表す。］
【００６４】
［繊維径（μｍ）］
走査電子顕微鏡で１０００倍に拡大した繊維側面の写真を撮り、任意の１０カ所で繊維直径を測定し、相加平均を繊維径とした。
【００６５】
［プリント配線基板基材中のフィルム状バインダーにおける孔数（個／ｍｍ²）および孔の平均開口面積（μｍ²）］
プリント配線基板基材の表面を拡大写真撮影し（倍率１００倍程度、写真撮影面積０．２ｍｍ²以上）、該写真上でフィルム状バインダー（Ｂ成分）に形成されている開口面積４００〜１００００μｍ²の孔の数を計測し、フィルム状バインダー１ｍｍ²当たり孔の数を求めた。さらに、開口面積が４００〜１００００μｍ²の範囲にある孔の開口面積を相加平均して平均開口面積を求めた。
なお、ここでいうフィルム状バインダー（Ｂ成分）に形成された孔とは、実質的にバインダーが存在しない主体繊維（Ａ成分）間に形成された空隙とは明確に区別されるものであり、孔の開口面積は、孔より下層に主体繊維（Ａ成分）が存在していないことが判別できる部位の面積とした。
【００６６】
［プリント配線基板基材における主体繊維(Ａ成分)の面積割合（％）］
プリント配線基板基材の表面を拡大写真撮影し（倍率１００倍程度）、該基材の表層部に主体繊維（Ａ成分）が存在すると認められる部位の面積割合（基材の表面積に対する該部位の合計面積の割合）を求めて、主体繊維（Ａ成分）の面積割合とした。
【００６７】
［プリント配線基板基材における孔形成割合（％）］
プリント配線基板基材の表面を拡大写真撮影し（倍率１００倍程度）、フィルム状バインダー（Ｂ成分）に占める開口面積４００〜１００００μｍ²の孔の合計面積の割合（基材の表面積に対する前記孔の合計面積の割合）を、孔形成割合とした。
【００６８】
［プリント配線基板基材の目付（ｇ／ｍ²）および厚さ（μｍ）］
プリント配線基板基材の目付はＪＩＳ Ｐ８１２４に準じて、また厚さはＪＩＳ Ｐ８１１８に準じて測定した。
【００６９】
［プリント配線基板基材の目付の標準偏差］
プリント配線基板基材の端から２０ｃｍ以上内側に入った位置で正方形（５０ｃｍ×５０ｃｍ）の試験片を切り出し、それを５ｃｍ×５ｃｍの小正方形に裁断し、それにより得られる１００個の小正方形の目付をそれぞれ測定し、その標準偏差を求めた。標準偏差が小さいほど基材の厚さが均一であり、繊維が均一に分散していることを意味する。
【００７０】
［プリント配線基板基材の空隙率（％）］
ＪＩＳ Ｐ８１２４およびＪＩＳ Ｐ８１１８に準じて試料（プリント配線基板基材）の坪量Ｗ（ｇ／ｍ²）および厚さＤ（ｍｍ）を測定し、空隙率（％）＝［１−｛Ｗ／（Ｄ×１０³×ｄ）｝］×１００により算出した。なお、ｄはプリント配線基板基材を構成しているポリマーの密度（ｇ／ｃｍ³）である。
【００７１】
［プリント配線基板基材の裂断長（ｋｍ）］
経×緯＝２００ｍｍ×１５０ｍｍの試験片をプリント配線基板基材から切り出し、ＪＩＳ Ｐ８１１３−１９７６に準じて経方向および緯方向の強度を測定し、その値を坪量で除して裂断長を算出し、その相加平均を裂断長とした。裂断長はプリント配線基板の引張強度を主に示す指標である。一般に裂断長が０．６ｋｍ以上であれば樹脂含浸工程などの工程通過性、寸法安定性などが良好となる。
【００７２】
［プリント配線基板基材の樹脂含浸性］
以下の参考例３で製造したマトリックス樹脂液（ワニス）にシアニングブルー粉末を０．５重量％添加したものをプリント配線基板基材に含浸させ、１５０℃で６分間加熱し乾燥させてプリプレグとし、これに厚さ１８μｍの銅箔を積層して、温度１８０℃、面圧２０ｋｇ／ｃｍ²、時間９０分の条件で熱プレスした。これにより得られた銅張積層板から縦×横＝１０ｃｍ×１０ｃｍの試験片を切り取り、塩化第２鉄溶液を用いて室温で１０分間エッチングしてその表面の状態を顕微鏡で観察して、直径０．５ｍｍ以上の白色の斑点（樹脂の非含浸部）の数を数えた。白色の斑点の数が多いほど樹脂含浸性が低いことを示し、樹脂含浸性が低くて劣るものでは、エッチング工程で吸水した後にハンダ工程を通過させると表面の破壊等を生じ、また期間経過による吸水が生じて絶縁破壊などのトラブルの原因となる。
【００７３】
［プリント配線基板基材の乾熱収縮率（耐熱性）（％）］
プリント配線基板基材から採取した試験片（約１０ｃｍ×１０ｃｍ）をオーブン中で、２８０℃で２４時間および３２０℃で２４時間熱処理したときの面積収縮率を測定して耐熱性の評価を行った。なお、面積収縮率は、熱処理前の試験片面積をＡ（１００ｃｍ²）および熱処理後の試験片面積をＢとして、面積収縮率（％）＝｛（Ａ−Ｂ）／Ａ｝×１００により算出される値である。
【００７４】
［プリント配線基板基材への樹脂付着性］
プリント配線基板基材の表面に下記の参考例３で製造したマトリックス樹脂液（ワニス）を６５±２重量％／（基材重量＋樹脂重量）の割合で塗布して含浸させ、それにより得られたプリプレグを目視にて観察し、基材にマトリックス樹脂が薄く均一に含浸した状態で付着している場合を極めて良好（◎）、基材にマトリックス樹脂が薄く含浸しているがはじき部分がある場合をほぼ良好（○）、および基材表面にマトリックス樹脂が厚く付着していて内部まで含浸していない場合を不良（×）として評価した。
【００７５】
［プリント配線板の誘電率および誘電正接］
ＪＩＳ Ｃ６４８１に準じて、変性ブリッジ法により温度２５℃±２℃の条件でプリント配線板の誘電率および誘電正接を測定した。
【００７６】
［プリント配線板の比重］
プリント配線板をエッチング処理して銅箔を完全に除去し、充分に水洗浄した後、１２０℃で２時間乾燥処理し、それから正方形（２５ｍｍ×２５ｍｍ）の試験片を切り出して、ＪＩＳ Ｋ７１１２法にしたがって比重を測定した。
【００７７】
［プリント配線板のハンダ耐熱性］
プリント配線板から正方形の試験片（５０ｍｍ×５０ｍｍ）を切り出し、エッチング法によって銅箔の３／４を除去し、充分に水洗浄を行った後、１２０℃で１時間乾燥した。それを沸騰水中に入れて２時間、４時間、６時間または８時間煮沸した後に取り出し空気中で２６０℃で１８０秒間加熱した。室温に冷却した後、銅箔面、銅箔除去面、端面およびプリント配線基板面における膨れおよび／または剥がれの有無を目視にて観察して、いずれの面にも膨れおよび／または剥がれが全く生じていない場合を良好（○）、１カ所でも膨れおよび／または剥がれが生じていた場合を不良（×）として評価した。また、沸騰水中で煮沸処理しない試験片（煮沸時間０時間）についても、空気中で２６０℃で１８０秒間加熱して、同様に膨れおよび／または剥がれの有無を観察した。
ハンダ耐熱性の低いプリント配線板は、当初は電気特性に優れていても長期間経過すると吸湿などが生じて電気特性が低下する。
【００７８】
《参考例１》［溶融液晶性ポリエステル繊維（主体繊維；Ａ成分）の製造］
（１） 溶融液晶性ポリエステルとして前記の式（１１）で示したパラヒドロキシ安息香酸単位（構造単位Ｘ）：２−ヒドロキシ−６−ナフトエ酸単位（構造単位Ｙ）の割合（モル比）が７３：２７である溶融液晶性ポリエステル（溶融粘度４３０ポイズ、重合度１００、融点２８０℃）を１４０℃で１００時間真空乾燥し、それをベント付単軸押出機に供給し、サンド層と金属繊維よりなる平均孔径５μｍのフィルター層を通して濾過した後、紡糸口金（ノズル孔径０．０８ｍｍ、５０ホール）から３２０℃で紡出させて、平均繊維径が１７μの溶融液晶性ポリエステル紡糸原糸（融点２８０℃、強度１３ｇ／ｄ、弾性率５２０ｇ／ｄ）を製造した。
（２） 上記（１）で得られた溶融液晶性ポリエステル紡糸原糸を２８０〜３００℃で１７時間熱処理して固相重合を行って融点３２０℃に上昇させ、それを繊維長５ｍｍにカットして、強度２５ｇ／ｄおよび弾性率５５０ｇ／ｄの溶融液晶性ポリエステル短繊維（主体繊維；Ａ成分）（融点３２０℃）を製造した。
【００７９】
《参考例２》［溶融液晶性ポリエステル繊維状バインダー（Ｂ₀成分）の製造］（１） 溶融液晶性ポリエステルとして前記の式（１１）で示したパラヒドロキシ安息香酸単位（構造単位Ｘ）：２−ヒドロキシ−６−ナフトエ酸単位（構造単位Ｙ）の割合（モル比）が７３：２７である溶融液晶性ポリエステル（溶融粘度４３０ポイズ、重合度１００、融点２８０℃）を１４０℃で１００時間真空乾燥し、それをベント付単軸押出機に供給し、サンド層と金属繊維よりなる平均孔径５μｍのフィルター層を通して濾過した後、紡糸口金（ノズル孔径０．０８ｍｍ、５０ホール）から３２０℃で紡出させて、平均繊維径が１７μの溶融液晶性ポリエステル紡糸原糸（融点２８０℃、強度１３ｇ／ｄ、弾性率５２０ｇ／ｄ）を製造した。
（２） 上記（１）で得られた溶融異方性ポリエステル紡糸原糸を繊維長５ｍｍに切断した後、水に分散させて水性懸濁液をつくり、汎用のディスクリファイナーにより叩解して、繊維径１〜５μｍ程度の溶融液晶性ポリエステル繊維状バインダー（Ｂ₀成分）（ＣＳＦ５００ｃｃ）（融点２８０℃）を製造した。
【００８０】
《参考例３》［マトリックス樹脂液（ワニス）の製造］
２，２−ビス（４−シアナトフェニル）プロパン９００重量部とビス（４−マレイドフェニル）メタン１００重量部を１５０℃で１３０分間予備反応させた後、それにより得られる生成物をメチルエチルケトンとＮ，Ｎ−ジメチルホルムアミドの混合溶媒６０重量部中に溶解した。得られた溶液５０重量部に、ビスフェノールＡエポキシ樹脂（油化シェルエポキシ社製「エピコート１００１」、エポキシ当量＝４５０〜５００）７０重量部およびオクチル酸亜鉛０．０２重量部を溶解させてマトリックス樹脂液（ワニス）を製造した。
【００８１】
《実施例１〜３》
（１） 上記の参考例１で製造した溶融液晶性ポリエステル繊維（Ａ成分）と参考例２で製造した溶融液晶性ポリエステル繊維状バインダー（Ｂ₀成分）を、下記の表１に示す割合（重量比）で用いて０．１％の水性スラリー（紙料）を調製し、該紙料を用いて円網ヤンキー試験抄造機にて湿式抄造し、１０５℃で乾燥して目付け約５０ｇ／ｍ²、厚さ約１２０μｍの湿式抄造物（原反）を製造した。（２） 上記（１）で得られた原反を、スチール製熱ローラ（温度２８０℃、線速１０ｍ／分）の表面に非加圧下（圧力０ｋｇ／ｃｍ）に接触させて加熱処理を行い、次いで３００℃の熱風式乾燥炉中に２４時間放置して空気中で熱処理を行った。さらにコロナ放電処理装置（出力１ＫＷ／ｍ²）中に１０ｍ／分の速度で連続的に通過させてコロナ放電処理を行ってプリント配線基板基材を製造した。これにより得られたプリント配線基板基材の物性を上記した方法で測定または評価したところ、下記の表１に示すとおりであった。
【００８２】
（３） 上記（２）で得られたプリント配線基板基材に上記の参考例３で製造したマトリックス樹脂液（ワニス）を含浸させ、１５０℃で乾燥して樹脂含量６６〜６８重量％のプリプレグを製造した。このプリプレグを４枚重ね、その両面に厚さ３５μｍの銅箔を積層した。該積層体をステンレススチール製の鏡面間に配置して、圧力４０ｋｇ／ｃｍ²、温度２００℃の条件下で２時間加圧加熱して積層成形を行って、厚さ０．４０〜０．４５ｍｍのプリント配線板を製造した。これにより得られたプリント配線板の物性を上記した方法で測定または評価したところ、下記の表１に示すとおりであった。
【００８３】
《実施例４》
実施例２の（２）において、３００℃の熱風式乾燥炉中で熱処理を行った後に、スチール製熱ローラー（温度８０℃、線速１０ｍ／分）で線圧３０ｋｇ／ｃｍの条件で低温プレス処理を行ってプリント配線基板基材の厚みを減じ、その後にコロナ放電処理を行った以外は実施例２と同様にして、プリント配線基板基材およびプリント配線板の製造を行った。結果を表１に示す。
【００８４】
《実施例５》
コロナ放電処理を行わなかった以外は実施例２と同様にして、プリント配線基板基材およびプリント配線板を製造した。結果を表１に示す。
【００８５】
《比較例１》
溶融液晶性ポリエステル繊維（Ａ成分）と溶融液晶性ポリエステル繊維状バインダー（Ｂ₀成分）を表１に示すように９５：５の重量比で用いた以外は実施例１と同様にしてプリント配線基板基材およびプリント配線板を製造した。結果を下記の表２に示す。
【００８６】
《比較例２》
溶融液晶性ポリエステル繊維状バインダー（Ｂ₀成分）を単独で用いて原反を製造し、該原反を温度２５０℃のスチール製熱ローラ（線速１０ｍ／分）の表面に非加圧下（圧力０ｋｇ／ｃｍ）に接触させて加熱処理を行った以外は実施例１と同様にしてプリント配線基板基材およびプリント配線板の製造を行った。結果を表２に示す。
【００８７】
《比較例３》
実施例２の（２）において熱風式乾燥炉中での熱処理を行わなかった以外は実施例２と同様にしてプリント配線基板基材およびプリント配線板を製造した［すなわちこの比較例３では溶融液晶性ポリエステル繊維状バインダー（Ｂ₀成分）の溶融により形成されたフィルム状バインダーの固相重合が行われていないため該フィルム状バインダーの融点は２８０℃のままである］。結果を下記の表２に示す。
【００８８】
《比較例４》
スチール製熱ローラーでの熱処理条件をローラー表面温度２８０℃、線圧８０ｋｇ／ｃｍに変更し、かつ熱風式乾燥炉中での熱処理を窒素ガス雰囲気下で行った以外は実施例２と同様にしてプリント配線基板基材およびプリント配線板の製造を行った。結果を表２に示す。
【００８９】
《比較例５》
（１） 参考例１の（１）と同じ工程を行って平均繊維径１７μｍの溶融液晶性ポリエステル紡糸原糸（融点２８０℃）を製造した後、その原糸を２８０〜３００℃で１７時間熱処理して固相重合を行って溶融液晶性ポリエステル繊維（融点３２０℃）を製造した。
（２） 上記（１）で得られた溶融液晶性ポリエステル繊維（融点３２０℃）を１００万デニール程度の束にした後、８０℃で機械捲縮を行い、それを切断して繊維長５１ｍｍ、平均繊維径１７μｍ、捲縮数１２回／インチの捲縮繊維を製造し、この捲縮繊維を用いてカード法により繊維ウエブを製造した。このときに、ウエブ内での繊維の配向状態が、ウエブの長さ方向に配列する繊維と、長さ方向に対して交叉する繊維の重量比が１：４になるようにした。
（３） 上記（２）で得られたウエブを８０メッシュの支持体上に載せて、その表側を水流絡合処理（スパンレース処理）（水噴射ノズル径０．１３ｍｍ、ノズルピッチ０．６ｍｍ、ウエブに対する角度９０°、水噴射圧力８０ｋｇ／ｃｍ²）し、ウエブ裏側を同様に水流絡合処理した後、再度ウエブ表側を同様に水流絡合処理して原反を製造した。
（４） 上記（３）で得られた原反を温度２８０℃のスチール製熱ローラーを用いて線圧８０ｋｇ／ｃｍ、線速１０ｍ／分の条件下で加熱加圧処理を行った後、それ以後は実施例１と同様の工程を行ってプリント配線基板基材およびプリント配線板を製造した。結果を下記の表３に示す。
なお、この比較例５で得られたプリント配線基板基材は、引張弾性率が低くて大きな伸びを生じ、工程通過性に劣るものであった。
【００９０】
《比較例６》
（１） 参考例１の（１）と同じ工程を行って平均繊維径１７μｍの溶融液晶性ポリエステル紡糸原糸（融点２８０℃）を製造した後、その原糸を２８０〜３００℃で１７時間熱処理して固相重合を行って溶融液晶性ポリエステル繊維（融点３２０℃）を製造した。
（２） 上記（１）で得られた溶融液晶性ポリエステル繊維（融点３２０℃）と、参考例１の（１）と同じ工程を行って得られた溶融液晶性ポリエステル紡糸原糸（融点２８０℃）を９０：１０の重量比で用いて１００万デニールの束にした後、８０℃で機械捲縮を行い、それを切断して繊維長５１ｍｍ、平均繊維径１７μｍ、捲縮数１２回／インチの捲縮繊維を製造し、カード法により繊維ウエブを製造した。このときに、ウエブ内での繊維の配向状態が、ウエブの長さ方向に配列する繊維と、長さ方向に対して交叉する繊維の重量比が１：４になるようにした。
（３） 上記（２）で得られたウエブを用いて比較例５の（３）および（４）と同じ工程を行って、プリント配線基板基材およびプリント配線板を製造した。結果を下記の表３に示す。
なお、この比較例６で得られたプリント配線基板基材は、湿式抄造物のような緻密な構造を有しておらず、そのため繊維状バインダー（融点２８０℃の溶融液晶性ポリエステル繊維）の溶融により主体繊維（融点３２０℃の溶融液晶性ポリエステル繊維）と繊維状バインダーの接触部分は結合しているが、バインダーはフィルム状にならず、均質性に劣るものであった。
【００９１】
《比較例７》
溶融液晶性ポリエステル繊維（主体繊維：Ａ成分）の代わりにアラミド繊維（デュポン社製「ケブラー４９」、平均繊維径１３μｍ、繊維長５ｍｍ）を用い、また溶融液晶性ポリエステル繊維状バインダー（Ｂ₀成分）の代わりにアラミドパルプ［デュポン社製「ノーメックスパルプ」、濾水度（ＣＳＦ）＝２００ｃｃ）を用いた以外は実施例１と同様にしてプリント配線基板基材およびプリント配線板を製造した。結果を表３に示す。
【００９２】
【表１】

【００９３】
【表２】

【００９４】
【表３】

【００９５】
上記の表１〜表３の結果から明らかなように、実施例１〜５の本発明のプリント配線基板基材は、樹脂含浸性、樹脂付着性および均質性に優れ且つ乾熱収縮率が小さく耐熱性に優れており、しかも裂断長が大きく充分な強度を有していてプリント配線板を製造する際の工程通以下性に優れたものであった。また、実施例１〜５の本発明のプリント配線基板基材を用いて得られたプリント配線板は、低誘電率、低比重であり、均質性、耐熱性、ハンダ耐熱性にも優れたものであった。特に、コロナ放電処理を施したもの（実施例１〜４）は、マトリックス樹脂の付着性が高く、ハンダ耐熱性に優れていた。
【００９６】
一方、溶融液晶性ポリエステル繊維（主体繊維；Ａ成分）と溶融液晶性ポリエステル繊維状バインダー（Ｂ₀成分）を用いていても、Ｂ₀成分の配合割合が少ない比較例１の場合には、バインダーがフィルム状にならないために主体繊維（Ａ成分）間の接着が強固になされず、プリント配線基板基材の強度（裂断長）が低いものとなった。
また、主体繊維（Ａ成分）を配合せずに繊維状バインダー（Ｂ₀成分）のみを用いた比較例２の場合には、Ｂ₀成分は溶融してフィルム状になるものの該フィルムに特定の開口面積を有する孔が特定数形成されず、しかも抄造時にバインダーが溶融・収縮して形態が維持できず、得られるプリント配線基板基材の樹脂含浸性に劣るものであった。
【００９７】
さらに、比較例３のものでは、溶融液晶性ポリエステル繊維状バインダー(Ｂ₀成分）の溶融によって湿式抄造物中に本発明で規定している所定の開口面積を有する孔を所定の数でフィルム状バインダーが形成されているが、該フィルム状バインダーの固相重合が行われていないために、フィルム状バインダーの融点が２９０℃未満であり、そのため得られるプリント配線基板基材の乾熱収縮率が大きくて耐熱性に劣り、しかも裂断長が小さく十分な強度を持たなかった。また、比較例３で得られたプリント配線板は、当初は電気特性が良好であるものの、ハンダ耐熱性が低く、長期にわたって良好な電気特性を保持できなかった。
また、非加圧下での熱処理の代わりに加圧下での熱プレス処理を施した比較例４では、プリント配線基板基材に所望の孔が形成されておらず樹脂含浸性が低いものとなり、当初の電気特性は良好であるものの、ハンダ耐熱性が低く、長期にわたって良好な電気特性を保持できるものではなかった。
【００９８】
また、比較例５では、溶融液晶性ポリエステル繊維（Ａ成分）を単独で用いて湿式抄造によらずに水流絡合法（スパンレース法）で絡合した不織布を原反としているため、比較例５で得られたプリント配線基板基材は、目付の標準偏差値が大きくて厚さ斑が著しく、各部分における特性が不均一であり、しかも樹脂含浸性に劣り、得られるプリント配線板の電気特性に劣るものであった。その上、上述のようにプリント配線基板基材の引張弾性率が低いために大きな伸びを生じ、工程通過性の点でも問題があった。
そして、比較例６では、溶融液晶性ポリエステル繊維（Ａ成分）と溶融液晶性ポリエステル繊維状バインダー（Ｂ₀成分）を併用してはいるが、湿式抄造によらずに水流絡合法（スパンレース法）で絡合した不織布を原反として用いたため、比較例６で得られたプリント配線基板基材も、目付の標準偏差値が大きくて厚さ斑が著しく、各部分における特性が不均一であり、しかも樹脂含浸性に劣り、得られるプリント配線板の電気特性に劣るものであった。その上、上述のように、湿式抄造物（湿式不織布）のように緻密な構造を有していないため、溶融液晶性ポリエステル繊維（Ａ成分）と溶融液晶性ポリエステル繊維状バインダー（Ｂ₀成分）の接触部分は結合するものの、バインダーはフィルム状にならず、均質性に劣っていた。
【００９９】
また、アラミド繊維とアラミドパルプを用いた比較例７では、繊維およびパルプの吸湿性が高いために、得られるプリント配線板の強制加湿後のハンダ耐熱性が劣っており、しかも誘電率および誘電正接が高く、電気特性が不良であった。
【０１００】
【発明の効果】
本発明のプリント配線基板基材は、寸法安定性、機械的性能、耐熱性、樹脂含浸性および均質性などの諸性能に優れ、プリプレグおよびプリント配線板を製造する際の工程通過性および取り扱い性に優れている。
上記した優れた諸性能を有する本発明のプリント配線基板基材を用いることにより、寸法安定性、耐湿性、耐熱性、均質性、ハンダ耐熱性に優れ、しかも低比重で軽量性に優れ、且つ誘電率および誘電正接が低くて電気特性に優れるプリント配線基板およびプリント配線板が得られる。
そして、本発明の製造方法による場合は、上記した優れた諸性能を有するプリント配線基板基材を極めて円滑に且つ確実に製造することができる。
【図面の簡単な説明】
【図１】本発明のプリント配線基板基材の一例の表面状態を示す電子顕微鏡写真である。
【図２】原反の製造時に加圧を伴う熱カレンダー処理を施こして得られたプリント配線基板基材の表面の状態を示す電子顕微鏡写真である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a printed wiring board substrate, a method for manufacturing the same, a printed wiring board, and a printed wiring board.
[0002]
[Prior art]
Glass fiber cloth has been used as a printed wiring board base material for a long time, but glass fiber has a drawback that it has a high dielectric constant and is heavy. In recent years, the use of liquid crystal aramid fibers has been studied. However, aramid fibers have high hygroscopicity and are not sufficiently satisfactory as printed wiring boards that require excellent electrical insulation.
[0003]
From the above, it has been proposed to use a molten liquid crystalline polyester fiber having a low dielectric constant, a low specific gravity, and a low hygroscopic property as a printed wiring board substrate. For example, Japanese Patent Application Laid-Open No. Sho 62-36892 describes a printed wiring board based on a woven fabric made of molten liquid crystalline polyester fiber. A thin woven fabric is produced using molten liquid crystalline polyester fiber. In this case, there is a problem that the process passability is low and the manufacturing cost is high, and the obtained printed wiring board base material is also inferior in homogeneity and has low workability such as resin impregnation.
It has also been proposed to use a dry nonwoven fabric obtained by a spunlace method (water entanglement method) as a base material for a printed wiring board (WO96 / 15306). However, since this dry nonwoven fabric has low mechanical properties and homogeneity, and the adverse effects such as thickness unevenness become more serious as it becomes thinner, it is not satisfactory as a printed wiring board substrate.
[0004]
[Problems to be solved by the invention]
On the other hand, a wet nonwoven fabric (wet paper product) made of molten liquid crystalline polyester fiber is excellent in mechanical performance, has high homogeneity, and has no spots even when it is thin. For example, JP-A-7-48718 and JP-A-8-170295 describe paper obtained by wet papermaking of molten liquid crystalline polyester short fibers and molten liquid crystalline polyester pulp. However, this paper is still inadequate in terms of resin impregnation properties, heat resistance, etc., and such conventional methods are based on excellent properties such as homogeneity, resin impregnation properties, mechanical performance, heat resistance, etc. No material was obtained.
[0005]
That is, in order to improve the mechanical performance, homogeneity, etc. of the nonwoven fabric, heat calendering is generally performed. However, when such processing is performed, the surface of the nonwoven fabric becomes a film by heat compression, and the pore size becomes minute. Moreover, the number of holes that can be impregnated with resin is drastically reduced. For this reason, the resin impregnation property becomes low and it becomes difficult to impregnate the entire nonwoven fabric with resin, and there is a problem that a portion not impregnated with resin is inevitably formed inside the nonwoven fabric. If there are a large number of voids not impregnated with resin, the electrical insulation becomes unstable at the time of moisture absorption, the solder heat resistance becomes poor, and it becomes insufficient as a printed wiring board substrate that requires high performance. However, unless heat calendering (heat pressure treatment) is applied, the nonwoven fabric cannot be provided with a strength that can withstand manufacturing processes such as a resin impregnation step, and problems such as dimensional stability arise. In this case, it was difficult to obtain a printed wiring board substrate having both the characteristics of resin impregnation and the characteristics of mechanical performance and dimensional stability.
[0006]
In addition, it has been studied to manufacture a printed wiring board substrate by mixing reinforcing fibers with a resin, but it is difficult to uniformly disperse the reinforcing fibers in the resin, and the orientation direction of the fibers is There is a limit to the reinforcing effect that can be obtained because it is random.
An object of the present invention is to provide a printed wiring board substrate excellent in various properties such as homogeneity, resin impregnation property, mechanical performance, and heat resistance, and an efficient production method thereof.
Furthermore, the present invention is excellent in various properties such as homogeneity, mechanical performance, heat resistance, moisture resistance and solder heat resistance, and has a low dielectric constant and dielectric loss tangent, and also has excellent electrical characteristics and printed wiring board. The purpose is to provide.
[0007]
[Means for Solving the Problems]
The present invention
(1) From a wet papermaking composed of a molten liquid crystalline polyester fiber (component A) having a melting point of 290 ° C. or higher and a molten liquid crystalline polyester binder (component B) having a melting point of 290 ° C. or higher, wherein the A component is fixed by the B component A printed wiring board base material, wherein the B component has an opening area of 400 to 10,000 μm in the wet papermaking ² 5 holes / mm or more ² It is the printed wiring board base material characterized by having formed the film form which has the ratio.
[0008]
And this invention,
(2) The blending (weight ratio) of the molten liquid crystalline polyester fiber (component A) and the molten liquid crystalline polyester binder (component B) in the wet papermaking product is 20:80 to 90:10 as described in (1) above. Printed circuit board substrate;
(3) The printed wiring board substrate according to any one of (1) and (2), wherein the porosity is 40% or more and the breaking length is 0.6 km or more; and
(4) The basis weight is 20 to 100 g / m. ² The printed wiring board substrate according to any one of the above (1) to (3);
Is included as a preferred embodiment thereof.
[0009]
Furthermore, the present invention provides
(5) Molten liquid crystalline polyester fiber (component A) having a melting point of 290 ° C. or higher and molten liquid crystalline polyester fiber binder (B) having a melting point of less than 290 ° C. ₀ The paper stock containing the component) is subjected to wet papermaking, and the obtained wet papermaking is heat-treated under no pressure, and B ₀ Opening area 400-10000μm by melting components ² 5 holes / mm or more ² A printed wiring board comprising a film-like molten liquid crystalline polyester binder (B component) having a ratio of 1 to 5 and fixing between the A components, and further increasing the melting point of the B component to 290 ° C. or more by solid phase polymerization. It is a manufacturing method of a base material.
[0010]
And this invention,
(6) At least one prepreg formed by impregnating or adhering a thermosetting resin and / or a thermoplastic resin to the printed wiring board substrate according to any one of (1) to (4) above is used. Printed wiring board;
(7) A printed wiring board using the printed wiring board according to (6) above;
(8) A printed wiring board obtained by laminating at least the printed wiring board according to (6) and a copper layer;
It is.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The printed wiring board base material of the present invention (hereinafter sometimes simply referred to as “base material”) is a wet paper product composed of a molten liquid crystalline polyester fiber (component A) and a molten liquid crystalline polyester binder (component B). (Wet non-woven fabric), which is characterized in that a melted liquid crystalline polyester fiber (main fiber; component A) excellent in heat resistance is firmly fixed by a specific film-like binder (component B), By using a specific binder as a constituent component, the base material is excellent in various properties such as homogeneity, heat resistance, resin impregnation property, and mechanical performance.
[0012]
The binder (B component) in the printed wiring board base material of the present invention has specific holes formed as illustrated in FIG. 1 (photo) taken with an electron microscope as an example of the printed wiring board base material of the present invention. A film-like binder that exists in the wet paper making up the base material in the form of a thin film, thereby making the base material excellent in resin impregnation properties, homogeneity, mechanical performance, heat resistance, etc. .
That is, the film-like binder (component B) constituting the printed wiring board substrate of the present invention has an opening area of 400 to 10,000 μm. ² Of the unit area of the film-like binder (1 mm ² ) At a rate of 5 or more. If the size of the holes in the film-like binder is too small than the above, or if the number of holes is too small than the above, the resin impregnation property becomes insufficient, and conversely, if the size of the holes is too large, the main fibers Between (A component) is not fixed firmly and a desired base material is not obtained.
[0013]
From the viewpoints of resin impregnation and mechanical performance of the printed wiring board substrate, the opening area of the film binder (component B) is 400 to 10,000 μm. ² 10-200 holes / mm ² Is preferably formed at a rate of 40 to 150 / mm ² More preferably, it is formed at a ratio of For the same reason, the opening area of one hole in the film-like binder (component B) is 1000 to 5000 μm. ² It is preferable that it is 1000-4000 micrometers. ² It is more preferable that
Moreover, it is preferable from the point of resin impregnation that the shape of a hole is a smooth shape without corners, such as circular and an ellipse.
The “pores formed in the film-like binder (component B)” in the present specification is clearly distinguished from the voids formed between the main fibers (component A) substantially free of binder. Is. The opening area of the holes in the film-like binder (component B) can be obtained from a photograph of an enlarged photograph (for example, about 100 times magnification) of the surface of the printed wiring board substrate. At this time, the opening area of the hole is the area of the hole formed at a site where it can be determined that the main fiber (component A) or the like is not present below the hole.
[0014]
From the viewpoint of resin impregnation and mechanical performance of the printed wiring board substrate, the total area of the holes formed in the film binder (B component) on the substrate surface is the entire film binder (B component). Is preferably 5% or more, more preferably within a range of 10 to 50%, and within a range of 10 to 20%. Is more preferable.
Further, in the printed wiring board base material, the portion of the base material surface that is determined to have the main fibers (component A) present on the surface portion is 5% or more with respect to the surface area of the base material. Preferably, it is in the range of 10 to 50%, more preferably in the range of 20 to 40%.
Furthermore, when the base material of the printed wiring board of the present invention is impregnated with a resin, the non-impregnated portion of the resin (the white portion not impregnated with the resin described in the following examples) is substantially zero. It is preferable that
[0015]
In the printed wiring board substrate of the present invention, both the melting point of the component A (melted liquid crystalline polyester fiber; main fiber) and the melting point of the film binder (component B) constituting the substrate must be 290 ° C. or higher. It is. If the melting points of the A component and the B component are lower than 290 ° C., the heat resistance of the substrate is lowered (the dry heat shrinkage rate is increased), and the heat resistance dimensional stability is lacking, and the printed wiring board manufacturing process Problems arise above. Conventionally, a binder having a low melting point has been used as a binder in a printed wiring board substrate. However, in the printed wiring board substrate of the present invention, both the main component (component A) and the binder (component B) are 290 ° C. or higher. It has a high melting point and is excellent in heat resistance, and since the main fibers (component A) are firmly fixed by the binder (component B) having excellent heat resistance, mechanical performance and dimensions Excellent performance such as stability and heat resistance. From the viewpoint of heat resistance, manufacturing processability, etc., the melting point of the main fiber (component A) and the binder (component B) constituting the printed wiring board substrate is preferably in the range of 300 to 390 ° C., 300 More preferably, it is in the range of ˜350 ° C.
[0016]
The molten liquid crystalline polyester fiber (component A), the molten liquid crystalline polyester binder (component B), and the molten liquid crystalline polyester fibrous binder (B before being made into the component B) as used herein. ₀ The melting point of the component) is A component, B component or B ₀ It is the peak temperature of the main endothermic peak observed with a differential scanning calorimeter (DSC) measured according to JIS K7121 for the molten liquid crystalline polyester constituting the component. Specifically, a sample is weighed into a DSC apparatus (for example, “TA3000” manufactured by Mettler, Inc.), and 10 to 20 mg of a sample is weighed and sealed in an aluminum pan, and then nitrogen as a carrier gas is allowed to flow at a flow rate of 100 cc / min. The endothermic peak when the temperature is raised in minutes can be measured, and if a clear endothermic peak does not appear at 1st Run depending on the type of polymer, the flow temperature is expected from the temperature rise rate of 50 ° C / minute. The temperature is raised to 50 ° C., melted completely at that temperature for 3 minutes, then cooled to 50 ° C. at a cooling rate of 80 ° C./min, and then the endothermic peak is measured at a heating rate of 20 ° C./min. Good.
[0017]
The printed wiring board substrate of the present invention preferably has a dry heat shrinkage of 3% or less when heat treated at a temperature of 320 ° C. for 24 hours from the viewpoint of process stability, dimensional stability, etc. More preferably, it is 2.5%, and still more preferably 0-2%.
Furthermore, the printed wiring board substrate of the present invention preferably has a breaking length of 0.6 km or more, more preferably 1 km or more, from the viewpoint of process stability, dimensional stability, and the like. The upper limit of the breaking length is not limited, but is preferably 10 km or less from the viewpoint of cost.
The printed wiring board substrate of the present invention preferably has a porosity of 40% or more from the viewpoint of resin impregnation and the like, and has a porosity of 45 to 70% from the viewpoint of resin impregnation and mechanical performance. It is more preferable that
[0018]
In addition, since the printed wiring board base material is generally required to be thin, the printed wiring board base material of the present invention preferably has a thickness of 20 to 200 μm, more preferably 25 to 100 μm. preferable.
Furthermore, the printed wiring board base material of the present invention has a basis weight of 20 to 100 g / m in terms of mechanical performance, resin impregnation property, and the like. ² Is preferably 25 to 50 g / m. ² It is more preferable that Furthermore, the basis weight standard deviation value of the printed wiring board substrate of the present invention is preferably 0.7 to 1.1 from the viewpoint of homogeneity.
[0019]
Although the manufacturing method of the printed wiring board base material of this invention is not specifically limited, It cannot obtain by the method of performing a heat | fever calendar process at high temperature and high pressure like the past. When heat calendering is performed at high temperature and pressure, the surface of the base material becomes a film, but the film shape in which a predetermined number of holes having a predetermined opening area are formed as in the printed wiring board base material of the present invention Instead, for example, as illustrated in the electron micrograph of FIG. 2, since there are almost no holes, the resin impregnation property is extremely low.
[0020]
As a suitable manufacturing method of the printed wiring board substrate of the present invention, a molten liquid crystalline polyester fiber (component A) having a melting point of 290 ° C. or higher and a molten liquid crystalline polyester fibrous binder having a melting point of less than 290 ° C. (B ₀ The paper stock containing the component) is subjected to wet papermaking, and the obtained wet papermaking is heat-treated under no pressure, and B ₀ Opening area 400-10000μm by melting components ² 5 holes / mm or more ² And a film-like melted liquid crystalline polyester binder (B component) having a ratio of A, and fixing between the A components, and further increasing the melting point of the B component to 290 ° C. or more by solid phase polymerization.
[0021]
That is, in producing the printed wiring board substrate of the present invention by the above-described method, a molten liquid crystalline polyester fiber (component A) having a melting point of 290 ° C. or higher and a molten liquid crystalline polyester fibrous binder having a melting point of less than 290 ° C. (B ₀ It is necessary to use the component in combination. The fibrous binder (B ₀ The component) may shrink during melting, but the form of the substrate is maintained by the presence of the high melting point component A (main fiber). Moreover, in the presence of component A, B ₀ When the ingredients melt, B ₀ The component changes from a fiber form to a B component having a film shape having specific pores, whereby the printed wiring board substrate of the present invention having excellent resin impregnation property, mechanical performance, and shape retention is obtained.
A molten liquid crystalline polyester fiber having a melting point of less than 290 ° C. (for example, B ₀ When only component) is used, the mechanical performance and shape retention of the base material are insufficient, and conversely, only melted liquid crystalline polyester fiber (for example, component A) having a melting point of 290 ° C. or higher is used. In such a case, only a substrate having poor mechanical performance can be obtained because the binder effect is insufficient.
[0022]
Further, from the viewpoint of the binder effect, the lower the melting point of the binder fiber, the better. However, simply using the binder fiber having a low melting point causes a problem because the heat resistance of the obtained base material is lowered. On the other hand, in the present invention, the binder fiber has a low melting point when making paper to obtain a wet nonwoven fabric and when fixing the main fiber (component A), and exhibits excellent binder performance. Thus, a fibrous binder (B) which becomes a molten liquid crystalline polyester film binder (B component) that firmly fixes the main fibers (A component) and at the same time exhibits excellent heat resistance and mechanical performance. ₀ Since the component) is used, a printed wiring board substrate excellent in various performances such as mechanical performance, shape retention, heat resistance and resin impregnation can be obtained.
[0023]
In addition, “melting liquid crystallinity” in the present specification is also called “melting anisotropy”, and indicates optical liquid crystallinity (anisotropy) in a molten phase. Whether a polymer has “molten liquid crystallinity” or not can be easily known by a known method. For example, a sample (polymer) placed on a hot stage is heated and heated in a nitrogen atmosphere, and the transmitted light is observed. The presence or absence of molten liquid crystallinity can be examined by a commonly employed method such as the method of
[0024]
Printed wiring board substrate of the present invention and molten liquid crystalline polyester fiber (component A), molten liquid crystalline polyester binder (component B) and molten liquid crystalline polyester fibrous binder (B ₀ The molten liquid crystalline polyester constituting the component) is a polyester composed of repeating structural units such as aromatic diol, aromatic dicarboxylic acid, and aromatic hydroxycarboxylic acid, and the molten liquid crystalline polyester (1) to (1) represented by the following chemical formula: 12) is preferred. Of course, in order to improve the spinnability, the molten liquid crystalline polyester may have other copolymer units such as an isophthalic acid unit as necessary, but other points from the viewpoint of fiber performance and the like. The proportion of the copolymer unit is preferably a small amount (usually 20 mol% or less).
[0025]
[Chemical 1]

[0026]
[Chemical 2]

[0027]
[Chemical 3]

[0028]
Among the above-described molten liquid crystalline polyesters, the total of structural units (Y units) composed of parahydroxybenzoic acid units (X units) and 2-hydroxy-6-naphthoic acid units represented by the above chemical formula (11). Is preferably 65% by mole or more, particularly preferably 80% by mole or more of the melted liquid crystalline polyester, and the ratio of 2-hydroxy-6-naphthoic acid units to 5-45% by mole based on the total amount of both units. It is particularly preferred from the viewpoint of melt spinnability and fiber performance that it is made of a melt liquid crystalline polyester.
[0029]
A component, B component and B ₀ The melted liquid crystalline polyester constituting the component may be polyethylene terephthalate, modified polyethylene terephthalate, polyolefin, polycarbonate, polyarylate, polyamide, polyphenylene sulfide, polyester ether ketone, One or more of other polymers such as arylate and fluorine-containing resin may be contained, and inorganic materials such as titanium oxide, kaolin, silica and barium oxide, colorants such as carbon black, dyes, pigments and dyes In addition, one or more of various additives such as antioxidants, ultraviolet absorbers, and light stabilizers may be blended. From the standpoint of fiber performance and the like, the content of components other than the molten liquid crystalline polyester is preferably 50% by weight or less, more preferably 30% by weight or less, based on the weight of the molten liquid crystalline polyester fiber. Preferably, it is 10% by weight or less.
[0030]
The melting point of the component A (main fiber) used in the present invention is 290 ° C. or higher from the viewpoint of the heat resistance, dimensional stability, hole forming property in the binder, manufacturing processability, etc. of the obtained printed wiring board substrate. It is necessary and it is preferable that it is 300-390 degreeC, and it is more preferable that it is 300-350 degreeC.
The component A may be a fiber obtained by using one type of molten liquid crystalline polyester, or may be a mixed spun fiber, composite fiber, or mixed fiber obtained by using two or more types of molten liquid crystalline polyester. Good.
[0031]
The component A (main fiber) having a melting point of 290 ° C. or higher can be obtained, for example, by melt spinning a molten liquid crystalline polyester to produce a spinning raw yarn, and heat-treating it to cause solid phase polymerization. When melt-spinned polyester is melt-spun, the molecular weight of the polymer before and after spinning does not change substantially, but when the fiber (spun yarn) obtained by spinning is heat-treated, solid-state polymerization occurs and the degree of polymerization is increased. As a result, the melting point (heat resistance), mechanical performance and the like are remarkably increased, which is preferable as the main fiber (component A) used in the present invention. The molten liquid crystalline polyester constituting the spinning yarn obtained by melt spinning is generally about 80-120 mer, but the main fiber (component A) is composed of about 250-350 mer molten liquid crystalline polyester. It is preferable.
[0032]
The heat treatment conditions (solid phase polymerization conditions) for changing the spinning yarn into the main fiber (component A) are not particularly limited, but with respect to the melting point (Tm) (° C.) of the molten liquid crystalline polyester constituting the spinning yarn. It is preferable to perform the heat treatment in a temperature range of (Tm-60 ° C.) to (Tm + 20 ° C.), and it is more preferable to perform the heat treatment (solid phase polymerization) while gradually raising the temperature from (Tm-40 ° C.) to Tm. As a heating method at the time of heat treatment, for example, a method using radiant heat from a heating plate or an infrared heater, a method of contacting with a heat roller or a hot plate, an internal heating method using high frequency or the like can be cited. The heat treatment may be performed under tension or without tension.
[0033]
The atmosphere during the heat treatment is not particularly limited, and can be performed under an inert gas atmosphere such as nitrogen gas or carbon dioxide gas or under an active gas atmosphere containing oxygen such as air, and may be performed under reduced pressure. . In addition, if moisture or moisture is present during the heat treatment, the physical properties of the fiber are lowered, so it is preferable to use a dehumidified gas.
[0034]
As a more specific and preferable method for producing the main fiber (component A), for example, the following method may be mentioned. For example, the ratio (molar ratio) of parahydroxybenzoic acid unit (X unit): 2-hydroxy-6-naphthoic acid unit (Y unit) is 73:27, the melt viscosity is 430 poise, the degree of polymerization is about 100, and the melting point is 280 ° C. After about 100 hours of drying at 140 ° C. for 100 hours, the melted liquid crystalline polyester was supplied to a single screw extruder with a vent, filtered through a filter layer having a mean pore diameter of 5 μm consisting of a sand layer and metal fibers, and a spinneret (nozzle A molten liquid crystalline polyester fiber (spun yarn) (melting point 280 ° C.) is produced by spinning at a temperature of 320 ° C. from a hole diameter of 0.08 mm and 50 holes, and this fiber is heat-treated at 280 to 300 ° C. to perform solid-phase polymerization. By carrying out the process and raising the degree of polymerization to about 300, fibers suitable as the main fiber (component A) can be obtained smoothly and efficiently.
[0035]
The form of the main fiber (component A) may be any of filaments, cut fibers, beaten products, etc., and is not particularly limited, but from the viewpoint of papermaking properties, mechanical performance of the obtained printed wiring board substrate, resin impregnation properties, etc. A cut fiber obtained by cutting a fiber obtained by spinning is preferable. The cut fiber preferably has a fiber diameter of 5 to 30 μm and a fiber length of 2 to 20 mm from the viewpoints of papermaking property and paper strength. When used in the form of a cut fiber, the heat treatment (solid phase polymerization) for increasing the melting point may be performed at any stage before cutting or after cutting.
[0036]
The fiber strength of the main fiber (component A) is preferably 16 g / d or more, more preferably 18 g / d or more, and further preferably 20 g / d or more. The upper limit of the fiber strength is not particularly limited, but the fiber strength is preferably 50 g / d or less from the viewpoint of production cost. The elastic modulus of the main fiber (component A) is preferably 400 g / d or more, and more preferably 500 to 2000 g / d.
[0037]
In the production of the printed wiring board substrate of the present invention, in addition to the main fiber (component A), from the viewpoint of the binder effect and the hole forming property in the binder, the melting point is less than 290 ° C., preferably 280 ° C. or less. Polyester binder fiber (B ₀ Component). From the viewpoint of heat resistance of the obtained printed wiring board substrate, a binder fiber (B ₀ Component) is preferred, but the binder fiber (B ₀ If the melting point of the component) is too high, the binder effect on the main fiber (component A) will be low, and the binder fiber (B ₀ Even if the component) is melted, it becomes difficult to form a film-like binder (B component) having pores suitable for impregnation of the resin, and the mechanical performance and resin impregnation property of the obtained printed wiring board substrate are lowered. Therefore, in order to obtain a printed wiring board substrate having good heat resistance, mechanical performance, and resin impregnation properties [pore formation in a film-like binder (component B)], a molten liquid crystalline polyester binder fiber (B ₀ It is preferable to use a component having a melting point within the range of 260 to 280 ° C, and more preferably within the range of 260 to 270 ° C. Binder fiber (B ₀ When using the component, binder fiber (B ₀ Component) has a low melting point and exhibits an excellent binder effect, and the viscosity is sufficiently lowered by melting to form a film-like binder having pores suitable for resin impregnation. By setting it as a film-like binder (B component) of 290 degreeC or more, the printed wiring board base material which heat resistance and mechanical performance improved notably is obtained.
[0038]
Binder fiber (B ₀ As the component, a raw yarn obtained by melt spinning a melted liquid crystalline polyester having a melting point of less than 290 ° C., that is, a fiber not subjected to heat treatment (solid phase polymerization) for increasing the melting point after melt spinning is used. Can do.
[0039]
Binder fiber (B ₀ The component is required to be fibrous as the name implies. Binder (B ₀ When the component) is powdery or granular, the main fiber (component A) and the binder (B ₀ It is difficult to obtain a wet paper product in which the component) is uniformly dispersed, and even if the binder in the wet paper product is melted, the viscosity is not sufficiently reduced, so that it is difficult to become a film-like binder. Predetermined holes suitable for resin impregnation are not formed, and the printed wiring board substrate of the present invention cannot be obtained.
[0040]
Binder fiber (B ₀ Although the fiber form of the component) is not particularly limited, it is preferably a fine pulp-like material from the viewpoint of papermaking property, hole forming property, etc., and the fiber from the point that papermaking property, binder performance, and hole forming property become better. More preferably, it is in the form of pulp having a diameter of 1 to 7 μm, particularly 1 to 5 μm, and a fiber length of about 0.1 to 3 mm. Pulp-like binder fiber (B ₀ The component) is fine, has a high paper-making property, and a high binder effect. Further, the component is easily melted and integrated with each other to easily form a film, and a predetermined hole is easily formed in the film. For the same reason as described above, the binder fiber (B ₀ As the component, those having a freeness (CFS; Canadian standard freeness value) of 600 cc or less are preferably used, and those having 0 to 550 cc are more preferably used.
[0041]
Pulp-like binder fiber (B ₀ Component) can be produced by beating and pulverizing a melt liquid crystalline polyester fiber, a film made of molten liquid crystalline polyester and other molded articles, preferably a spinning base of melted liquid crystalline polyester with a refiner or the like, or a molten liquid crystal By removing solvent, acid, alkali treatment, etc. before or after cutting the fiber into short fibers from the sea-island type composite fiber or laminating type composite fiber containing a reactive polyester as one component Can also be manufactured.
In the present invention, the binder fiber (B ₀ As the component, a pulp-like fiber obtained by beating and pulverizing cut liquid crystal melted polyester fiber having a single fiber fineness of 5 denier or less is more preferably used.
[0042]
In addition, binder fiber (B ₀ The component) may be a single fiber of a single type of molten liquid crystalline polyester, or may be a mixed spun fiber, composite fiber and / or mixed fiber formed using two or more types of molten liquid crystalline polyester. .
[0043]
Furthermore, binder fiber (B ₀ The component) is preferably a melted liquid crystalline polyester fiber having a fiber strength of 5 to 15 g / d or one obtained by beating and grinding the fiber. Furthermore, binder fiber (B ₀ The elastic modulus of component) is preferably about 200 to 600 g / d.
[0044]
Although the manufacturing method of the printed wiring board base material of this invention is not specifically limited, For example, it can manufacture suitably with the following method.
First, the main fiber (component A) and binder fiber (B ₀ The paper stock containing at least the component) is wet-made to make a paper product.
Main fiber (component A) at that time: Binder fiber (B ₀ The blending ratio (weight ratio) of the component) is preferably 20:80 to 90:10 from the viewpoints of papermaking properties, mechanical performance of the obtained printed wiring board substrate, and the like. In order to make the formability (resin impregnation property) better, the blending ratio is more preferably 20:80 to 60:40. Binder fiber (B ₀ If the blending ratio of component) is too small, adhesion / fixation between the main fibers (component A) becomes insufficient, and the paper-making property and paper strength decrease, and a film-like binder having pores suitable for resin impregnation is based. It becomes difficult to form in the material. That is, in order to obtain the printed wiring board substrate of the present invention, the binder fiber (B ₀ The viscosity of the component) is sufficiently lowered by melting and each binder fiber (B ₀ The component) is integrated into a film and a specific number of holes need to be formed in the film, but the binder fiber (B ₀ If the component is too small, it will not be a film-like binder even if it is melted, and it will be difficult to form pores. On the other hand, if the blending ratio of the main fibers (component A) is too small, the mechanical performance and dimensional stability of the obtained printed wiring board substrate will be insufficient, and it will be difficult to form specific holes in the film binder. Become.
[0045]
In addition, the above-mentioned paper materials used for the production of paper products include main fibers (component A) and binder fibers (B ₀ Components other than (Component) may be included, but in order not to impair the effects of the present invention, 50% by weight or more, particularly 80% by weight, or more preferably 90% by weight or more of the solid content in the paper stock The main fiber (component A) and the binder fiber (B ₀ Component).
Furthermore, the paper stock is preferably in the form of an aqueous dispersion (aqueous suspension) having a solid content concentration of 0.01 to 1% by weight.
[0046]
In wet papermaking, the wet papermaking machine to be used is not particularly limited, and a conventionally known apparatus may be used. Specifically, for example, a circular net type wet paper machine, a short net type wet paper machine, a short net tilt type wet paper machine, a wire and Yankee of a long net type wet paper machine, a multi-cylinder wet paper machine, hot air or radiant heat And a wet papermaking machine equipped with a dryer of the type. A wet nonwoven fabric can be produced by drying the obtained wet paper product, but the wet paper product usually has a high porosity of 60% or more, and has good resin impregnation properties but mechanical properties. The performance is low (usually a fracture length of 0.2 km or less), and there is a problem in process passage. Therefore, in this invention, it is necessary to heat-process the said wet papermaking after drying under a non-pressurization, and it heat-processes and binder fiber (B ₀ Ingredient) is melted and the opening area is 400-10000 μm in the wet papermaking ² 5 holes / mm or more ² A film-like binder having a ratio of 1 to 5 is formed and the main fibers (component A) are fixed. Binder fiber (B ₀ By making the component) into a film-like binder having the specific holes described above, a printed wiring board substrate having excellent resin impregnation properties can be obtained. At this time, the binder fiber (B ₀ It is necessary to solid-phase polymerize the film-like binder formed from (Component) to have a melting point of 290 ° C. or higher (that is, B component). Without solid-phase polymerization of the film-like binder, the heat resistance of the printed wiring board substrate becomes insufficient, and the bond between the main fibers (component A) does not become strong. A wiring board cannot be obtained.
[0047]
As described above, the heat treatment for the wet paper product needs to be performed under substantially no pressure, and the paper strength becomes higher when the heat press treatment (heat calender treatment) with pressurization which has been widely performed conventionally is employed. However, the resin impregnation property is greatly reduced, and the desired printed wiring board substrate cannot be obtained.
“Unpressurized” as used in the present invention refers to a state in which a substantially large pressure is not applied to the wet paper product, and heat treatment may be performed by any method as long as it is in such a state. For example, a method of continuously heating one side or both sides of the wet papermaking by bringing it into contact with a heat roller can be mentioned. At this time, it is necessary to reduce the linear pressure of the kneading roller with respect to the wet paper product, and it is preferable to set the linear pressure to about 0 to 10 kg / cm. Of course, instead of the contact heating method using a heat roller, a convection heating method using hot air or the like, a radiant heating method using far infrared rays, or the like may be employed, and two or more of these may be used in combination. Specific heat treatment conditions are: main fiber (component A) and binder fiber (B ₀ The heat treatment temperature is generally 200 to 400 ° C., particularly preferably about 260 to 350 ° C., and the heat treatment time is about 10 minutes to 48 hours, It is preferably about 10 to 40 hours.
[0048]
Binder fiber (B ₀ The heat treatment for melting the component) and the heat treatment for solid-phase polymerization may be performed in the same process or in separate processes. ₀ After the component) is melt-bonded, it is preferably subjected to solid-state polymerization by hot air treatment. At this time, the binder fiber (B ₀ The heat treatment for melting the component is [binder fiber (B ₀ Component) melting point (Tm) −10 ° C.] to [the melting point (Tm) + 10 ° C.], preferably at a linear velocity of 5 to 30 m / min. It is preferable to carry out the treatment at a temperature within the range of [the melting point (Tm) + 10 ° C.] to [the melting point (Tm) + 70 ° C.] for 10 to 30 hours. By adopting the above-mentioned heat treatment conditions, a printed wiring board substrate excellent in various performances such as resin impregnation property and mechanical performance can be effectively produced. From the viewpoint of processability, the wet paper product is dried by heating at a low temperature (eg, about 100 to 150 ° C.), and then the binder fiber (B ₀ It is preferable to perform the heat treatment described above for melting the component.
[0049]
Furthermore, since the printed wiring board is required to be thin, the binder fiber (B ₀ The printed wiring board group obtained by performing the heat treatment for melting the component) and the heat treatment for solid-phase polymerization may be further subjected to a low-temperature press treatment to reduce the thickness as necessary. Since the shape of the substrate is stabilized by the heat treatment for melting and solid phase polymerization described above, the substrate can be thinned without substantially impairing the resin impregnation property of the substrate even if low-temperature press treatment is performed. The temperature of the low-temperature press treatment is preferably 0 to 140 ° C., particularly preferably 0 to 100 ° C., and the linear pressure is preferably 100 kg / cm or less, particularly 1 to 50 kg / cm.
[0050]
In addition, the obtained printed wiring board base material may be subjected to physical and / or scientific treatment as necessary in order to improve adhesion to the resin impregnated therein, wettability with the resin, and the like. . Specifically, corona discharge treatment, glow discharge treatment, plasma treatment, electron beam irradiation treatment, ultraviolet irradiation treatment, physical treatment such as heat treatment in an oxygen-containing atmosphere, chemical treatment such as sputtering, and the like can be given. Two or more kinds of these treatments may be used in combination. Binder fiber (B ₀ If the heat treatment for melting and / or solid-phase polymerization of the component) is performed in an oxygen-containing atmosphere, the adhesiveness and wettability of the substrate with the resin are remarkably achieved without performing another process. Can be increased. In particular, it is preferable to perform heat treatment in an oxygen-containing atmosphere, corona discharge treatment, or both, because the adhesiveness of the substrate to the resin can be increased efficiently.
[0051]
When the heat treatment in the oxygen-containing atmosphere described above is performed, the surface of the main fiber (component A) is oxidized to form polar groups such as carboxyl groups on the surface, thereby improving the adhesion and wettability with the resin. This heat treatment is preferably performed at 200 to 400 ° C., particularly 300 to 400 ° C. for 1 minute or longer. The heat treatment time is preferably 30 hours or less from the viewpoint of processability. This heat treatment is performed using binder fiber (B ₀ For the purpose of melting and / or solid phase polymerization of the component), it may be carried out in the same step as the heat treatment or in a separate step.
Moreover, when performing an above-mentioned corona discharge process, it is preferable to carry out on the conditions of 0.5-3 kilowatt from the point which suppresses the activation effect and carbonization of a fiber.
[0052]
The printed wiring board substrate of the present invention obtained as described above can be distributed and sold as it is. Further, a prepreg is manufactured by impregnating or adhering a thermosetting resin and / or a thermoplastic resin (matrix resin) to the base material, and a printed wiring board is manufactured by using this as a single layer or by laminating a plurality of sheets. be able to.
Suitable matrix resins used for the production of prepreg include, for example, one or more thermosetting resins selected from phenol resins, epoxy resins, unsaturated polyester resins, cyanate resins, maleimide resins, polyimide resins and the like. It is done. Furthermore, one or two of the thermosetting resins described above are modified by adding polyvinyl butyral, acrylonitrile-butadiene rubber, polyfunctional acrylate compound, etc., crosslinked polyethylene, bismaleide-triazine resin, crosslinked polyethylene modified epoxy. A thermosetting resin (IPM type or semi-IPM type polymer alloy) modified with a thermoplastic resin such as a resin, a crosslinked polyethylene-modified cyanate resin, or a polyphenylene ether-modified cyanate resin can also be used as the matrix resin. Among these, epoxy resins, polyimide resins, unsaturated polyester resins, cyanate resins, and the like are suitable as matrix resins for printed wiring boards.
Also, the main fiber (component A) and / or the binder fiber (B ₀ In the case of using a fiber made of a melt anisotropic polyester mainly composed of a p-hydroxybenzoic acid unit (X unit) and a 2-hydroxy-6-naphthoic acid unit (Y unit) as the component), the adhesion to the fiber Bismaleide-triazine resin, which is excellent in insulation and heat resistance, is preferably used as the matrix resin.
[0053]
The content of the matrix resin in the prepreg is not particularly limited. From the viewpoint of suppressing delamination and molding defects, and improving the mechanical performance, dimensional stability, and thermal stability of the printed wiring board, It is preferable to use 30 to 95% by weight, particularly 40 to 80% by weight of the total weight as the matrix resin.
[0054]
The method for impregnating or attaching the resin to the printed wiring board substrate is not particularly limited, and a conventionally known method may be used. For example, an impregnation method, a coating method, a transfer method, or the like may be employed. Specifically, the substrate is impregnated with a varnish prepared by dissolving a matrix resin in a solvent, and the substrate is impregnated with a liquid matrix resin in a normal temperature state or heated state prepared without using a solvent. A method, a method of fixing a powdered matrix resin to a substrate, a method of forming a layer of a matrix resin on a film or sheet having releasability, and then transferring it to the substrate can be employed. Since the printed wiring board base material of the present invention is excellent in resin impregnation properties, the entire printed wiring board base material can be impregnated with resin, and an excellent effect is exhibited. In addition, when drying the matrix resin impregnated or adhered to the base material, it is preferable to dry in a non-contact state with a vertical dryer.
[0055]
A printed wiring board may be manufactured using at least one prepreg obtained by such a method. Specifically, a printed wiring board composed of a single layer of the prepreg, a printed wiring board formed by laminating two or more of the prepregs, one or more of the prepregs and other materials (for example, glass cloth, glass nonwoven fabric, other fibers) And a printed wiring board formed by laminating a cloth, a porous substrate, a plastic sheet, a plastic film, a plastic plate, or the like. In order to sufficiently achieve the effects of the present invention, it is preferable that the printed wiring board is composed substantially only of the prepreg formed by impregnating the printed wiring board base material of the present invention with a resin. In order to improve electrical characteristics and workability, it is more preferable to produce a printed wiring board by laminating about 2 to 5 prepregs.
[0056]
A printed wiring board is obtained by laminating a metal layer on such a printed wiring board. The metal layer may be a single layer or a plurality of layers.
Examples of the metal layer include a metal foil, a metal sheet, a metal plate, and a metal net. In some cases, two or more of these may be used in combination. Moreover, surface treatment etc. may be given to the metal layer. As the metal constituting the metal layer, copper, iron, aluminum and the like are preferable, and copper is particularly preferable. Of course, two or more of the aforementioned metals can be used in combination. The thickness of the metal layer is preferably about 10 to 50 μm from the viewpoints of handleability and electrical characteristics. Adhesion between the metal layer and the printed wiring board may be performed using an adhesive in some cases.
[0057]
The manufacturing method of a printed wiring board is not specifically limited, What is necessary is just to manufacture similarly to a conventionally well-known method. For example, one or more prepregs in which the printed wiring board base material of the present invention is impregnated with resin are used, and if necessary, other materials are used together, and these and the metal layer are superposed and heated under pressure. The target printed wiring board can be manufactured by curing and / or solidifying the matrix resin and bonding the layers. Appropriate conditions may be employed for the heating temperature, pressure, and the like in accordance with the type of matrix resin, the type of material to be laminated, the number of layers, and the like. Of course, the metal layers may be laminated and integrated after a plurality of prepregs are laminated and integrated in advance.
[0058]
The thickness of the printed wiring board is preferably about 0.2 to 0.8 mm from the viewpoint of handleability and the like, and the specific gravity is preferably 1.5 or less, particularly preferably 0.8 to 1.4. . Furthermore, from the viewpoint of electrical characteristics, the dielectric constant of the printed wiring board is preferably 3.3 or less, particularly 2.0 to 3.2, and the dielectric loss tangent is 0.0098 or less, particularly 0.0085 to 0. .0095 is preferred.
[0059]
【Example】
The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to the following examples. In addition, measurement methods or evaluation methods for various physical properties in Examples and Comparative Examples are shown below.
[0060]
[Melt viscosity of melted liquid crystalline polyester (poise)]
The viscosity of the molten liquid crystalline polyester is as follows: temperature 300 ° C., shear rate r = 1000 sec. ^-1 The measurement was performed using a capillograph (“Capillograph Type 1B” manufactured by Toyo Seiki Co., Ltd.) under the above conditions.
[0061]
[Melting point (° C)]
As described above, after weighing 10 to 20 mg of a sample in a DSC apparatus (for example, “TA3000” manufactured by Mettler) and enclosing it in an aluminum pan, nitrogen is flowed at a flow rate of 100 cc / min as a carrier gas, The endothermic peak was measured when the temperature was raised in minutes, and if no clear endothermic peak appeared at 1st Run, the temperature increased to 50 ° C higher than the expected flow temperature at a rate of temperature increase of 50 ° C / min. The temperature was raised, and the mixture was completely melted at that temperature for 3 minutes, then cooled to 50 ° C. at a rate of temperature decrease of 80 ° C./min, and then an endothermic peak was measured at a rate of temperature increase of 20 ° C./min.
[0062]
[Fiber strength (g / d)]
In accordance with JIS L1013, using a high elongation tester (“Strong elongation tester DCS-100 type” manufactured by Shimadzu Corporation) under the conditions of a sample length of 20 cm, an initial load of 0.1 g / d, and a tensile speed of 10 cm / min. A tensile fracture test was performed, and the strength of the fiber was determined from the obtained stress-strain curve. An average value of five or more measured values was adopted.
[0063]
[Elastic modulus of fiber (g / d))]
According to JIS L1013, using a high elongation tester (“Strong elongation tester DCS-100 type” manufactured by Shimadzu Corporation) under the conditions of a sample length of 200 mm, an initial load of 0.1 g / d, and a tensile speed of 10 cm / min. A tensile fracture test was performed, and the elastic modulus of the fiber = (w / D) / (ΔL / L) was calculated from the obtained stress-strain curve. Here, w is the load (g) when ΔL is stretched, D is the denier (d) of the fiber, ΔL is the length (mm) stretched by the load, and L is the original length (200 mm) of the fiber. ]
[0064]
[Fiber diameter (μm)]
A photograph of the side surface of the fiber magnified 1000 times with a scanning electron microscope was taken, the fiber diameter was measured at any 10 locations, and the arithmetic mean was taken as the fiber diameter.
[0065]
[Number of holes in film binder in printed wiring board substrate (pieces / mm ² ) And the average opening area (μm) ² ]]
The surface of the printed wiring board substrate was enlarged and photographed (magnification about 100 times, photography area 0.2 mm) ² Above), an opening area of 400 to 10000 μm formed in the film-like binder (component B) on the photograph ² Measure the number of holes in the film binder 1mm ² The number of hit holes was determined. Furthermore, the opening area is 400 to 10000 μm ² The average opening area was obtained by arithmetically averaging the opening areas of the pores in the range.
In addition, the hole formed in the film-like binder here (B component) is clearly distinguished from the void formed between the main fibers (A component) substantially free of the binder, The opening area of the hole was the area of a part where it can be determined that the main fiber (component A) is not present below the hole.
[0066]
[Area ratio (%) of the main fiber (component A) in the printed wiring board substrate]
The surface of the printed wiring board substrate is magnified (about 100 times magnification), and the area ratio of the portion where the main fibers (component A) are present in the surface layer of the substrate (the portion of the portion relative to the surface area of the substrate) The ratio of the total area) was determined and used as the area ratio of the main fibers (component A).
[0067]
[Percentage of hole formation in printed wiring board substrate (%)]
The surface of the printed circuit board substrate is enlarged (about 100 times magnification), and the opening area occupied by the film binder (component B) is 400 to 10,000 μm. ² The ratio of the total area of the holes (the ratio of the total area of the holes to the surface area of the substrate) was defined as the hole formation ratio.
[0068]
[Weight of printed wiring board substrate (g / m ² ) And thickness (μm)]
The basis weight of the printed wiring board substrate was measured according to JIS P8124, and the thickness was measured according to JIS P8118.
[0069]
[Standard deviation of printed circuit board substrate weight]
A square (50 cm × 50 cm) test piece was cut out at a position 20 cm or more inside from the edge of the printed wiring board substrate, cut into small squares of 5 cm × 5 cm, and 100 small squares obtained thereby. Each basis weight was measured and its standard deviation was determined. The smaller the standard deviation, the more uniform the thickness of the substrate, which means that the fibers are uniformly dispersed.
[0070]
[Porosity of printed wiring board substrate (%)]
Basis weight W (g / m) of sample (printed wiring board substrate) according to JIS P8124 and JIS P8118 ² ) And thickness D (mm), and porosity (%) = [1− {W / (D × 10 ^Three × d)}] × 100. In addition, d is the density (g / cm) of the polymer constituting the printed wiring board substrate. ^Three ).
[0071]
[Cutting length of printed wiring board substrate (km)]
Cut a test piece of warp x weft = 200 mm x 150 mm from a printed wiring board substrate, measure the strength in the warp direction and the weft direction according to JIS P8113-1976, and divide the value by the basis weight to obtain the breaking length. Calculation was made and the arithmetic average was taken as the fracture length. The breaking length is an index mainly showing the tensile strength of the printed wiring board. In general, when the breaking length is 0.6 km or more, process passability such as a resin impregnation process and dimensional stability are improved.
[0072]
[Resin impregnation of printed wiring board substrate]
The matrix resin solution (varnish) produced in Reference Example 3 below was impregnated with 0.5% by weight of cyaning blue powder on a printed wiring board substrate, heated at 150 ° C. for 6 minutes and dried to form a prepreg. Then, a copper foil with a thickness of 18 μm is laminated on this, and the temperature is 180 ° C. and the surface pressure is 20 kg / cm. ² And hot pressing for 90 minutes. A test piece of length × width = 10 cm × 10 cm was cut out from the copper clad laminate thus obtained, etched with a ferric chloride solution at room temperature for 10 minutes, and the surface state was observed with a microscope, and the diameter was measured. The number of white spots (resin non-impregnated portion) of 0.5 mm or more was counted. The larger the number of white spots, the lower the resin impregnation property. The lower the resin impregnation property, the lower the resin impregnation property. Water absorption occurs, causing problems such as dielectric breakdown.
[0073]
[Dry heat shrinkage (heat resistance) of printed wiring board base material (%)]
The heat resistance was evaluated by measuring the area shrinkage ratio when a test piece (about 10 cm × 10 cm) collected from the printed wiring board substrate was heat-treated in an oven at 280 ° C. for 24 hours and 320 ° C. for 24 hours. . In addition, the area shrinkage rate is the test piece area before heat treatment A (100 cm ² ) And the area of the specimen after the heat treatment is B, the area shrinkage rate (%) = {(A−B) / A} × 100.
[0074]
[Adhesion of resin to printed wiring board substrate]
It is obtained by applying and impregnating the surface of the printed wiring board base material with the matrix resin liquid (varnish) produced in Reference Example 3 below at a rate of 65 ± 2% by weight / (base material weight + resin weight). When the prepreg is visually observed and adhered to the base material in a thin and uniformly impregnated state with the matrix resin, it is very good (◎). The base material is thinly impregnated with the matrix resin, but there is a repelling part. The case was evaluated as good (O), and the case where the matrix resin was thickly adhered to the surface of the substrate and not impregnated to the inside was evaluated as defective (x).
[0075]
[Dielectric constant and dielectric loss tangent of printed wiring board]
According to JIS C6481, the dielectric constant and dielectric loss tangent of the printed wiring board were measured by a modified bridge method at a temperature of 25 ° C. ± 2 ° C.
[0076]
[Specific gravity of printed wiring board]
The printed wiring board is etched to completely remove the copper foil, thoroughly washed with water, then dried at 120 ° C. for 2 hours, and then a square (25 mm × 25 mm) test piece is cut out and subjected to JIS K7112 method. Therefore, the specific gravity was measured.
[0077]
[Solder heat resistance of printed wiring board]
A square test piece (50 mm × 50 mm) was cut out from the printed wiring board, 3/4 of the copper foil was removed by an etching method, sufficiently washed with water, and then dried at 120 ° C. for 1 hour. It was placed in boiling water, boiled for 2, 4, 6 or 8 hours, then taken out and heated in air at 260 ° C. for 180 seconds. After cooling to room temperature, the copper foil surface, the copper foil removal surface, the end surface, and the printed wiring board surface were visually observed for swelling and / or peeling, and any surface was completely swollen and / or peeled. The case where it was not good (O) and the case where swelling and / or peeling occurred even at one place were evaluated as bad (X). Moreover, also about the test piece (boiling time 0 hours) which is not boiled in boiling water, it heated in the air at 260 degreeC for 180 second, and the presence or absence of the swelling and / or peeling was observed similarly.
Even if printed wiring boards with low solder heat resistance are initially excellent in electrical characteristics, moisture absorption occurs after a long period of time, resulting in a decrease in electrical characteristics.
[0078]
<< Reference Example 1 >> [Production of Molten Liquid Crystalline Polyester Fiber (Main Fiber; Component A)]
(1) A ratio (molar ratio) of parahydroxybenzoic acid unit (structural unit X): 2-hydroxy-6-naphthoic acid unit (structural unit Y) represented by the above formula (11) as the melted liquid crystalline polyester is 73. : Melted liquid crystalline polyester (melt viscosity 430 poise, polymerization degree 100, melting point 280 ° C.) is vacuum-dried at 140 ° C. for 100 hours, and is supplied to a single screw extruder with a vent. After filtering through a filter layer having an average pore diameter of 5 μm, spinning is performed at 320 ° C. from a spinneret (nozzle hole diameter 0.08 mm, 50 holes), and a melt liquid crystalline polyester spinning yarn (melting point 280 ° C.) having an average fiber diameter of 17 μm. Strength 13 g / d, elastic modulus 520 g / d).
(2) The molten liquid crystalline polyester spinning yarn obtained in the above (1) was heat-treated at 280 to 300 ° C. for 17 hours to carry out solid phase polymerization to raise the melting point to 320 ° C., and cut it into a fiber length of 5 mm. Thus, a molten liquid crystalline polyester short fiber (main fiber; component A) (melting point: 320 ° C.) having a strength of 25 g / d and an elastic modulus of 550 g / d was produced.
[0079]
<< Reference Example 2 >> [Melted liquid crystalline polyester fibrous binder (B ₀ Production of component)] (1) Ratio of parahydroxybenzoic acid unit (structural unit X) represented by the above formula (11) as a molten liquid crystalline polyester: 2-hydroxy-6-naphthoic acid unit (structural unit Y) ( Molten liquid crystalline polyester (melt viscosity 430 poise, degree of polymerization 100, melting point 280 ° C.) having a molar ratio of 73:27 is vacuum-dried at 140 ° C. for 100 hours, and is supplied to a single screw extruder with a vent, After filtering through a filter layer having an average pore diameter of 5 μm consisting of a layer and a metal fiber, spinning is performed from a spinneret (nozzle hole diameter 0.08 mm, 50 holes) at 320 ° C. to obtain a melt liquid crystalline polyester spinning raw material having an average fiber diameter of 17 μm. A yarn (melting point 280 ° C., strength 13 g / d, elastic modulus 520 g / d) was produced.
(2) The melt anisotropic polyester spinning yarn obtained in the above (1) is cut into a fiber length of 5 mm, then dispersed in water to form an aqueous suspension, and beaten with a general-purpose disc refiner. Molten liquid crystalline polyester fibrous binder (B ₀ Ingredient) (CSF 500 cc) (melting point 280 ° C.).
[0080]
<< Reference Example 3 >> [Production of matrix resin liquid (varnish)]
After pre-reacting 900 parts by weight of 2,2-bis (4-cyanatophenyl) propane and 100 parts by weight of bis (4-maleidophenyl) methane at 150 ° C. for 130 minutes, the resulting product is reacted with methyl ethyl ketone. Dissolved in 60 parts by weight of a mixed solvent of N, N-dimethylformamide. In 50 parts by weight of the obtained solution, 70 parts by weight of bisphenol A epoxy resin (“Epicoat 1001” manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent = 450 to 500) and 0.02 part by weight of zinc octylate were dissolved to form a matrix resin. A liquid (varnish) was produced.
[0081]
<< Examples 1-3 >>
(1) Molten liquid crystalline polyester fiber (component A) produced in Reference Example 1 and molten liquid crystalline polyester fiber binder (B) produced in Reference Example 2 ₀ Ingredients) are used in the proportions (weight ratio) shown in Table 1 below to prepare a 0.1% aqueous slurry (paper material), and wet papermaking is performed using the paper stock with a circular net Yankee test papermaking machine. , Dried at 105 ° C., about 50 g / m ² A wet paper product (raw material) having a thickness of about 120 μm was produced. (2) The raw material obtained in (1) above is subjected to heat treatment by bringing it into contact with the surface of a steel heat roller (temperature: 280 ° C., linear speed: 10 m / min) under no pressure (pressure: 0 kg / cm). Then, it was left in a 300 ° C. hot air drying oven for 24 hours and heat-treated in air. Furthermore, corona discharge treatment equipment (output 1KW / m ² ) Was continuously passed at a speed of 10 m / min for corona discharge treatment to produce a printed wiring board substrate. The physical properties of the printed wiring board substrate thus obtained were measured or evaluated by the method described above, and as shown in Table 1 below.
[0082]
(3) The printed wiring board substrate obtained in (2) above is impregnated with the matrix resin liquid (varnish) produced in Reference Example 3 above, dried at 150 ° C., and a prepreg having a resin content of 66 to 68% by weight. Manufactured. Four prepregs were stacked, and a copper foil having a thickness of 35 μm was stacked on both sides thereof. The laminate is placed between mirror surfaces made of stainless steel, and the pressure is 40 kg / cm. ² The laminate was molded by pressurizing and heating at a temperature of 200 ° C. for 2 hours to produce a printed wiring board having a thickness of 0.40 to 0.45 mm. The physical properties of the printed wiring board thus obtained were measured or evaluated by the method described above, and as shown in Table 1 below.
[0083]
Example 4
In Example 2 (2), after heat treatment in a 300 ° C. hot-air drying furnace, a low-temperature press was performed with a steel hot roller (temperature 80 ° C., linear speed 10 m / min) under a linear pressure of 30 kg / cm. The printed wiring board base material and the printed wiring board were manufactured in the same manner as in Example 2 except that the thickness of the printed wiring board base material was reduced by the treatment, and then the corona discharge treatment was performed. The results are shown in Table 1.
[0084]
Example 5
A printed wiring board substrate and a printed wiring board were produced in the same manner as in Example 2 except that the corona discharge treatment was not performed. The results are shown in Table 1.
[0085]
<< Comparative Example 1 >>
Molten liquid crystalline polyester fiber (component A) and molten liquid crystalline polyester fibrous binder (B ₀ As shown in Table 1, a printed wiring board substrate and a printed wiring board were produced in the same manner as in Example 1 except that the component was used at a weight ratio of 95: 5 as shown in Table 1. The results are shown in Table 2 below.
[0086]
<< Comparative Example 2 >>
Molten liquid crystalline polyester fibrous binder (B ₀ Ingredients) are used alone to produce a raw fabric, and the raw fabric is brought into contact with the surface of a steel heat roller (linear speed 10 m / min) at a temperature of 250 ° C. under non-pressurization (pressure 0 kg / cm). A printed wiring board substrate and a printed wiring board were produced in the same manner as in Example 1 except that the above was performed. The results are shown in Table 2.
[0087]
<< Comparative Example 3 >>
A printed wiring board substrate and a printed wiring board were produced in the same manner as in Example 2 except that the heat treatment in the hot-air drying furnace was not performed in Example 2 (2). -Based polyester fibrous binder (B ₀ Since the film-like binder formed by melting the component) has not been subjected to solid phase polymerization, the melting point of the film-like binder remains at 280 ° C.]. The results are shown in Table 2 below.
[0088]
<< Comparative Example 4 >>
The heat treatment conditions with a steel hot roller were changed to a roller surface temperature of 280 ° C. and a linear pressure of 80 kg / cm, and the heat treatment in a hot air drying furnace was performed in a nitrogen gas atmosphere in the same manner as in Example 2. A printed wiring board substrate and a printed wiring board were produced. The results are shown in Table 2.
[0089]
<< Comparative Example 5 >>
(1) After performing the same process as (1) of Reference Example 1 to produce a melted liquid crystalline polyester spinning yarn (melting point 280 ° C.) having an average fiber diameter of 17 μm, the yarn is heat treated at 280 to 300 ° C. for 17 hours. Then, solid phase polymerization was carried out to produce a molten liquid crystalline polyester fiber (melting point: 320 ° C.).
(2) The molten liquid crystalline polyester fiber (melting point: 320 ° C.) obtained in the above (1) is made into a bundle of about 1 million denier, then subjected to mechanical crimping at 80 ° C., and cut into a fiber length of 51 mm, A crimped fiber having an average fiber diameter of 17 μm and a number of crimps of 12 times / inch was produced, and a fiber web was produced by the card method using the crimped fiber. At this time, the fiber orientation state in the web was such that the weight ratio of the fibers arranged in the length direction of the web and the fibers intersecting in the length direction was 1: 4.
(3) The web obtained in the above (2) is placed on an 80-mesh support, and the front side is hydroentangled (spun lace) (water jet nozzle diameter 0.13 mm, nozzle pitch 0.6 mm, 90 ° angle to the web, water injection pressure 80 kg / cm ² The web back side was similarly subjected to hydroentanglement treatment, and the web front side was again subjected to hydroentanglement treatment to produce a raw fabric.
(4) The raw material obtained in (3) above was subjected to heat and pressure treatment using a steel heat roller at a temperature of 280 ° C. under conditions of a linear pressure of 80 kg / cm and a linear speed of 10 m / min. Thereafter, the same process as in Example 1 was performed to produce a printed wiring board substrate and a printed wiring board. The results are shown in Table 3 below.
Note that the printed wiring board substrate obtained in Comparative Example 5 had a low tensile elastic modulus and a large elongation, and was inferior in process passability.
[0090]
<< Comparative Example 6 >>
(1) After performing the same process as (1) of Reference Example 1 to produce a melted liquid crystalline polyester spinning yarn (melting point 280 ° C.) having an average fiber diameter of 17 μm, the yarn is heat treated at 280 to 300 ° C. for 17 hours. Then, solid phase polymerization was carried out to produce a molten liquid crystalline polyester fiber (melting point: 320 ° C.).
(2) Molten liquid crystalline polyester fiber (melting point: 320 ° C.) obtained in (1) above and molten liquid crystalline polyester spinning yarn (melting point: 280 ° C.) obtained by performing the same step as (1) in Reference Example 1. ) At a weight ratio of 90:10 to make a bundle of 1 million denier, then mechanical crimped at 80 ° C. and cut to a fiber length of 51 mm, an average fiber diameter of 17 μm, and the number of crimps of 12 times / inch A crimped fiber was produced, and a fiber web was produced by the card method. At this time, the fiber orientation state in the web was such that the weight ratio of the fibers arranged in the length direction of the web and the fibers intersecting in the length direction was 1: 4.
(3) Using the web obtained in (2) above, the same steps as (3) and (4) of Comparative Example 5 were performed to produce a printed wiring board substrate and a printed wiring board. The results are shown in Table 3 below.
In addition, the printed wiring board base material obtained in this Comparative Example 6 does not have a dense structure such as a wet paper product, and therefore melts a fibrous binder (melting liquid crystalline polyester fiber having a melting point of 280 ° C.). As a result, the contact portion between the main fiber (melting liquid crystalline polyester fiber having a melting point of 320 ° C.) and the fibrous binder is bonded, but the binder does not become a film and is inferior in homogeneity.
[0091]
<< Comparative Example 7 >>
An aramid fiber (“Kevlar 49” manufactured by DuPont, average fiber diameter 13 μm, fiber length 5 mm) is used in place of the molten liquid crystalline polyester fiber (main fiber: component A), and a molten liquid crystalline polyester fibrous binder (B ₀ A printed wiring board substrate and a printed wiring board were produced in the same manner as in Example 1 except that aramid pulp (“Nomex Pulp” manufactured by DuPont, freeness (CSF) = 200 cc) was used instead of the component. The results are shown in Table 3.
[0092]
[Table 1]

[0093]
[Table 2]

[0094]
[Table 3]

[0095]
As is apparent from the results in Tables 1 to 3, the printed wiring board base materials of the present invention of Examples 1 to 5 are excellent in resin impregnation property, resin adhesion property and homogeneity, and have a low dry heat shrinkage rate. It was excellent in heat resistance, and had a large fracture length and sufficient strength, and was excellent in processability when producing a printed wiring board. Moreover, the printed wiring board obtained using the printed wiring board base material of the present invention of Examples 1 to 5 has a low dielectric constant and a low specific gravity, and is excellent in homogeneity, heat resistance, and solder heat resistance. Met. Particularly, those subjected to corona discharge treatment (Examples 1 to 4) had high adhesion of the matrix resin and excellent solder heat resistance.
[0096]
On the other hand, molten liquid crystalline polyester fiber (main fiber; component A) and molten liquid crystalline polyester fibrous binder (B ₀ Component), B ₀ In the case of Comparative Example 1 where the blending ratio of the components is small, since the binder does not become a film, the adhesion between the main fibers (component A) is not strengthened, and the strength (breaking length) of the printed wiring board substrate is increased. It became low.
In addition, fibrous binder (B ₀ In the case of Comparative Example 2 using only the component, B ₀ Although the component is melted to form a film, a specific number of holes having a specific opening area are not formed in the film, and the binder cannot be melted and shrunk during paper making, and the shape cannot be maintained, and the obtained printed wiring board substrate The resin impregnation property was inferior.
[0097]
Further, in Comparative Example 3, a melted liquid crystalline polyester fibrous binder (B ₀ The film binder is formed with a predetermined number of holes having a predetermined opening area defined in the present invention in the wet papermaking by melting the component), but the film binder is solid-phase polymerized. Therefore, the melting point of the film-like binder is less than 290 ° C., so that the resulting printed wiring board base material has a large dry heat shrinkage ratio, is inferior in heat resistance, and has a small fracture length and does not have sufficient strength. It was. Moreover, although the printed wiring board obtained in Comparative Example 3 had good electrical characteristics at the beginning, it had low solder heat resistance and could not maintain good electrical characteristics over a long period of time.
Further, in Comparative Example 4 in which heat press treatment under pressure was performed instead of heat treatment under no pressure, a desired hole was not formed in the printed wiring board base material, and the resin impregnation property was low. Although the electrical characteristics of this were good, the solder heat resistance was low, and good electrical characteristics could not be maintained over a long period of time.
[0098]
Moreover, in Comparative Example 5, since the nonwoven fabric entangled by the hydroentanglement method (spun lace method) using the melted liquid crystalline polyester fiber (component A) alone and not by wet papermaking is used as the original fabric, Comparative Example 5 The printed wiring board base material obtained in (1) has a large standard deviation value of the basis weight, marked unevenness in thickness, uneven properties in each part, and poor resin impregnation properties, and electrical characteristics of the obtained printed wiring board It was inferior to. In addition, since the tensile elastic modulus of the printed wiring board substrate is low as described above, a large elongation occurs, and there is a problem in terms of process passability.
In Comparative Example 6, the molten liquid crystalline polyester fiber (component A) and the molten liquid crystalline polyester fibrous binder (B ₀ Component) is used in combination, but because the nonwoven fabric entangled by the hydroentanglement method (spun lace method) without using wet papermaking was used as the original fabric, the printed wiring board substrate obtained in Comparative Example 6 The basis weight standard deviation value was large, the thickness unevenness was remarkable, the characteristics in each part were uneven, the resin impregnation property was inferior, and the electrical characteristics of the obtained printed wiring board were inferior. In addition, as described above, since it does not have a dense structure like a wet paper product (wet nonwoven fabric), a molten liquid crystalline polyester fiber (component A) and a molten liquid crystalline polyester fibrous binder (B ₀ Although the contact portion of the component) was bonded, the binder was not film-like and was inferior in homogeneity.
[0099]
In Comparative Example 7 using aramid fibers and aramid pulp, the heat resistance of the printed wiring board obtained after forced humidification is inferior due to the high hygroscopicity of the fibers and pulp, and the dielectric constant and dielectric loss tangent. The electrical characteristics were poor.
[0100]
【The invention's effect】
The printed wiring board substrate of the present invention is excellent in various performances such as dimensional stability, mechanical performance, heat resistance, resin impregnation property and homogeneity, and process passability and handleability when manufacturing prepregs and printed wiring boards. Is excellent.
By using the printed wiring board substrate of the present invention having the above-described excellent performances, it is excellent in dimensional stability, moisture resistance, heat resistance, homogeneity, solder heat resistance, low specific gravity and light weight, and A printed wiring board and a printed wiring board having a low dielectric constant and dielectric loss tangent and excellent electrical characteristics can be obtained.
And according to the manufacturing method of this invention, the printed wiring board base material which has the above-mentioned various performance can be manufactured very smoothly and reliably.
[Brief description of the drawings]
FIG. 1 is an electron micrograph showing the surface state of an example of a printed wiring board substrate of the present invention.
FIG. 2 is an electron micrograph showing the state of the surface of a printed wiring board substrate obtained by applying a heat calendering process with pressure during the production of the original fabric.

Claims (8)

Printed wiring composed of a wet paper product composed of a molten liquid crystalline polyester fiber (component A) having a melting point of 290 ° C. or higher and a molten liquid crystalline polyester binder (component B) having a melting point of 290 ° C. or higher, wherein the A component is fixed by the B component. A printed wiring board, which is a substrate substrate, wherein the component B is in the form of a film having 5 or more holes / mm ² of holes having an opening area of 400 to 10000 μm ^{2 in} the wet paper product Base material. The printed wiring board according to claim 1, wherein a blending ratio (weight ratio) of the molten liquid crystalline polyester fiber (component A) and the molten liquid crystalline polyester binder (component B) in the wet papermaking product is 20:80 to 90:10. Base material. The printed wiring board substrate according to claim 1, wherein the porosity is 40% or more and the breaking length is 0.6 km or more. Printed circuit board substrate according to claim 1 having a basis weight is 20 to 100 g / m ^2. A paper stock containing a molten liquid crystalline polyester fiber (component A) having a melting point of 290 ° C. or higher and a molten liquid crystalline polyester fiber binder (B ₀ component) having a melting point of less than 290 ° C. is wet-made, and the obtained wet paper product is not added. heat treated under pressure, B ₀ and the components are melted between a component as well as the opening area 400~10000μm film-like liquid crystalline polyester binder having a ^second hole at a ratio of 5 or more / mm ² (B component) A method for producing a printed wiring board substrate, comprising fixing and further increasing the melting point of the component B to 290 ° C. or higher by solid phase polymerization. A printed wiring board comprising at least one prepreg formed by impregnating or adhering a thermosetting resin and / or a thermoplastic resin to the printed wiring board base material according to any one of claims 1 to 4. A printed wiring board using the printed wiring board according to claim 6. A printed wiring board obtained by laminating at least the printed wiring board according to claim 6 and a copper layer.

Images