JP3957522B2 - High precision foamed coaxial cable - Google Patents

Description

【００５２】
絶縁体２は、気孔率が６０％以上で、その精度が±５％とし、厚さの公差が±３μｍで、圧縮応力０．２４〜０．２８Ｋｇ重の時圧縮変形歪みが０．６〜０．８％の焼成多孔質ＰＴＦＥテープ体か、または重量平均分子量５００万以上のポリエチレン多孔質テープ体等を適用して、テープ体幅４．６ｍｍ、厚さ０．０９ｍｍのテープ体を、内部導体への巻回角度を８０度、１／２重ねで巻回して、更に、幅６．９ｍｍ、厚さ０．０９ｍｍのテープ体を巻回角度８０度、１／２重ねで巻回して構成する。
【００５３】
テープ体を巻回して構成された絶縁線心１０は、外径の変動を絶縁体外径の中心値の±１．５％に形成される。気孔率を６０％以上にし、その精度を±５％とするのは、伝搬遅延時間を速める（比誘電率１．４以下を満足させる）為であり、また、特性インピーダンス値の精度にも、絶縁体の比誘電率の精度が影響するからである。その厚さの公差を±３μｍにすることと、テープの巻回の重ねを１／２とするのは、絶縁体２の厚さの精度を上げるためである。
【００５４】
圧縮応力が０．２４〜０．２８Ｋｇ重である場合に、圧縮変形歪みが０．６〜０．８％の焼成ＰＴＦＥテープを用い、且つ巻回角度を８０度とするのは、巻回の際のテープ体の潰れを軽減させるためである。絶縁体２の外径の変動を±１％に形成する方法は、テープ体巻回後または後述する編組体層の形成時等に絶縁体２の外径を所定外径に成形する成形ダイスに絶縁線心１０を挿通して成形処理によりなされる。
【００５５】
この成形処理は、図２（イ）（ロ）に示された多孔質テープ体（テープ巻き体）２１により生じる内部導体１の周りと、絶縁体２の外部の空隙部ａ，ｂをなくして、絶縁体２の内部導体への密着化を図り、巻回による絶縁体２の内外周の凸凹を無くすものである。この処理によって、絶縁体２の厚さが均一化され、外径のバラツキが無くなり、外径が真円円筒体状に形成される。
【００５６】
この成形処理は、多孔質テープ体２１の気孔率を６０％以上にしても、その厚さを上記の数値に限定したために可能となるものである。従来の伝送速度を速くするだけの発泡度を７０以上にした同軸ケーブルにおいては、多孔質テープ体２１の機械的強度が弱い為と、絶縁体２の外径の変動、凸凹によりできなかった。
【００５７】
その外径の変動を±１．５％に形成された絶縁線心１０、即ち絶縁体２の外周には、外部導体３が形成される。外部導体３は、外径が０．０５〜０．１０ｍｍの軟銅線を適用して、その外周に厚さ１〜３μｍの銀またはニッケルのメッキ層を施して、更に、厚さ０．２〜０．５μｍの錫合金のメッキ層を施し、外径公差が±２／１０００ｍｍの二層メッキ層を有する軟銅線を適用して、編組角度６５〜７５°、編組密度９５％以上で編組し、編組体の外径精度を外径中心値の±２％に形成する。
【００５８】
外部導体３に編組体を適用する理由は、高精度発泡同軸ケーブルに曲げ、捻り、押圧、摺動、その他の機械的ストレスが付加された時に、絶縁体２及び外部導体３にダメージを与えないことと、ケーブルに柔軟性を持たせる為である。
【００５９】
また、編組素線に銀またはニッケル等のメッキ層と、錫合金メッキ層との二層のメッキ層を有する軟銅線を適用するのは、素線表面の摩擦抵抗を小さくして、滑り性を良くして、ケーブルに機械的ストレスが付加された時に、各素線が動き易く、ストレスを分散して、絶縁体２に影響させないためと、編組体の形状が維持されて絶縁体２を保持し、編組体の挫屈を防ぐと同時に内部応力の解放を防ぐためである。
【００６０】
各素線外周に錫合金メッキ層設ける理由は、上記の滑り性を良くする他、ウィスカ防止の為である。錫合金の内容は錫と銅からなり、銅の含有比率は０．６〜２．５％で構成される。また、その他に銀が０．３〜３．５％、ビスマスが１〜１０％含有したものなど、一般的に鉛フリー半田メッキと呼ばれるものの適用も可能である。各素線のメッキ構成については、導電率が大きく、動的摩擦係数の小さい錫メッキを適用するのが有効であるが、錫単独では、高温下で使用すると、銅が錫メッキ層に拡散し、拡散応力によりウィスカの発生・成長が促進され、成長したウィスカによる内部導体１と外部導体３とのショートを防止するためであり、ウィスカを防止するには、次の▲１▼〜▲４▼のことが有効である。
【００６１】
▲１▼内部の銅の拡散を防止する。▲２▼錫に添加物を入れる。▲３▼熱処理による内部応力を減少させる。▲４▼メッキの厚さを薄くする。ここで、銀メッキ、ニッケルメッキ等のメッキ層を設けることは、銅の拡散防止となるが動的摩擦係数が大きい為、素線同士の動きが悪くなり、ケーブルの柔軟性を無くす。
【００６２】
素線同士の動きを良くしてケーブルに柔軟性を持たせる為には、上記のメッキ層の上に更に、０．２〜０．５μｍの錫合金溶融メッキ層を施した軟銅線を適用することにより対応できた。下地の銀、またはニッケル等のメッキ層の厚さを１〜３μｍとするのは、銅の拡散防止には１μｍ以上の厚さが必要であるが、厚すぎるとケーブルの柔軟性に悪影響する。錫合金メッキの厚さを０．２μｍ以下にすると下地の銀メッキが露出して、柔軟性に欠け、また、０．５μｍ以上にするとウィスカが発生し易くなる。ここで、各金属の動的摩擦係数の概要を記述すると、銀は１．３０、銅は０．９０、錫合金は０．５５となり、この値から動的摩擦係数の小さい錫合金メッキを編組体の素線に適用することが有効であることが理解できる。なお、各金属の動的摩擦係数は、Ｂｏｗｄｅｎ型低加重摩耗試験器により求めたものである。
【００６３】
編組体の外径精度を外径中心値の±２％に成形することにより、編組体層がその長さ方向に絞られるようになり、編組体自体の空隙部がなくなり、編組体が絶縁体により密着して編組体と絶縁体間との空隙部もなくなり、編組体内径がより真円円筒体状に近づき、特性インピーダンス値の一定化と、その変動を少なくする。編組体層の外径精度を±２％に形成する方法は、編組後または後述する同軸ケーブル外被４の成形時等に編組体層外径を所定外径に成形する成形ダイスに編組体層付き線心を挿通させて成形処理によりなされる。
【００６４】
この成形処理は、多孔質テープ体２１を前述した内容に限定したために絶縁体２の機械的強度が向上し、更に絶縁体２の外径の変動、凸凹がなくなり、編組体の外径変動、凸凹が無くなった為に可能となり、さらに、編組体を錫合金メッキ層を有する軟銅線で構成することにより、摩擦抵抗を小さくして成形ダイスヘの挿通が可能となり、成形処理ができるようになった。
【００６５】
なお、従来の伝送速度を速くするだけの発泡度７０以上にしたテープ巻き絶縁体の同軸ケーブルにおいては、編組体シールド層の外径変動、外径凸凹が大きい為に、この成形処理はできなかった。
【００６６】
上記の成形処理によって編組体の外径精度を外径中心値の±２％に成形された編組体層外周には、外被４が、その厚さを外部導体３の厚さの０．５倍以上の厚さとして、編組体層との密着力が２３℃において、２０ｇ／ｍｍ²以上として、ＦＥＰ樹脂の押し出し成形により構成される。ここで、厚さを限定する理由は、ケーブルに機械的ストレスが付加された時、編組体の形状を維持し挫屈を防止するためであり、密着力が２０ｇ／ｍｍ²未満であると、編組体の内部応力の解放をおさえることができない。この結果、特性インピーダンス値の精度の安定性に欠ける。密着力が２０ｇ／ｍｍ²以上であれば、内部応力の解放を抑えることができる。
【００６７】
次に、図３を参照して、多孔質テープ体２１の巻回と、絶縁体２の外径の変動を±１．５％に成形する方法を説明する。
【００６８】
撚り合わせ導体（内部導体）１を、テープ巻き装置の第１、第２、第３のガイドダイス３０ａ，３０ｂ，３０ｃと、成形ダイス３１ａ，３１ｂに図示せぬ供給部から供給する。供給された導体１は、矢印Ｙ１の方向に所定の回転数で回転させる。この回転する導体１は、所定速度で矢印Ｙ２の方向に送られることにより、第１のガイドダイス３０ａを通過した後、第２ダイス３０ｂの手前で、テープ体供給部１５から供給された多孔質テープ体２１が巻回される。これは、多孔質テープ体２１を導体１に対して、角度８０°、テープ張力３００ｇにして、導体１自体の矢印Ｙ１方向の回転により、導体１の外周に１／２重ねで巻回し、更に、その外周にもう一度テープ体を巻回するものである。
【００６９】
このように多孔質テープ体２１を巻回して第２ダイス３０ｂを通過したテープ巻体は、第２と第３のガイドダイス３０ｂ，３０ｃ間に配置された第１と第２の成形ダイス３１ａ，３１ｂに挿通される。ここで、内径１．１３ｍｍ、内径長３．０ｍｍの第１成形ダイス３１ａで、外径の変動が±２％で成形される。第１成形ダイス３１ａを通過した多孔質テープ体２１は、次に第２成形ダイス３１ｂに挿通され、ここで、内径１．１２ｍｍ、内径長３．００ｍｍの寸法で、所定外径とその公差で成形される。以上の成形処理により多孔質テープ体２１の外径が真円円筒体状になり、導体１との密着が良くなり、厚さの不均一、外径の凸凹、外径のバラツキ等が減少される。成形ダイス３１ａ，３１ｂにより成形される多孔質テープ体２１の成形をよりスムースに行う場合は、成形ダイス３１ａ，３１ｂ等を所定の回転数を持って回転させながら行うこともできる。更にテープ巻きと、テープ体の焼成とを同時に行う場合は、成形ダイス３１ａ，３１ｂを焼成温度に加熱しても良い。
【００７０】
次に、図４を参照して、編組体（外部導体）３の編組と、編組体の外径精度を外径中心値の±２％に形成する方法の概要を説明する。
【００７１】
導体１の外周にテープ体を巻回して、所定外径と、所定外径精度に成形されたテープ巻体絶縁線心１０は編組装置４０に供給され、編組装置４０の第１、第２のガイドダイス４１，４２と、成形ダイス４３に挿通される。
【００７２】
第１ガイドダイス４１は、絶縁線心１０のガイドを行う他に、編組する前の絶縁線心１０を所定外径と所定外径精度に成形する。第１ガイドダイス４１を通過した絶縁線心１０は、複数の編組用素線４４を有して交互に反対方向に回転する編組装置４０の回転により、編組用素線４４が編み込まれて第２ガイドダイス４２の直前で編組される。第２ガイドダイス４２は、編組体３をガイドするとともに、編組体３の外周の成形をも行う。
【００７３】
第２ガイドダイス（編組用ダイス）４２を通過した編組体３は、内径１．５０ｍｍ、内径長３．００ｍｍの内径を有する成形ダイス４３に挿通され、成形ダイス４３により編組体３が成形される。この成形により、編組体３がその長さ方向に引っ張られて、絞られる為に編組体３自体の空隙部がなくなり編組体３が絶縁体２に、より密着して編組体３と絶縁体２間の空隙部がなくなり編組体３内径がより絶縁体２外径の値に近くなり、編組体３厚さの不均一、外径の凸凹、外径のバラツキ等を減少させて、真円円筒体状に近づき、特性インピーダンス値の一定化とその変動を少なくする。
【００７４】
次に、この他の実施の形態を、図５〜図１０を参照して説明する。
【００７５】
まず、図５（イ）に示すように、他の実施の形態の同軸ケーブル５０は、内部導体１と、この導体１の外周に多孔質テープ体を巻回して構成された絶縁体２と、絶縁体２の外周に設けられた編組体による外部導体３と、外部導体３の外周に設けられた外被４とから成る。さらに、図５（ロ）に示す同軸ケーブル５５は、絶縁体２の外周に外径保持層５６が形成されている。
【００７６】
絶縁体２は、気孔率が６０％以上で、その精度が±５％であり、厚さが±３μｍで、圧縮応力が０．２４〜０．２８Ｋｇ重である場合に、圧縮変形歪みが０．６〜０．８％の焼成多孔質ＰＴＦＥテープ体、または、５００万以上の重量平均分子量のポリエチレン多孔質テープ体等を適用して、図６に示すように、テープ体幅２．５ｍｍ±３μｍで、厚さ０．１８０ｍｍのテープ体２１ａを内部導体１への巻回角度８０度をもって、テープ体２１ａの重ねを無くして二回巻として構成する。または、図７に示すように、内部導体１の外周に２枚のテープ体２１ｂを持って、テープ体２１ｂの幅の間隔を持って重ねを無くして巻回することによって絶縁体２を形成すると、テープ体２１ａの重ねが無いので、導体１側の空隙、絶縁体２の外部の凸凹が無くなり、絶縁体２は、外径の変動を、絶縁体２の外径の中心値の±１．５％に形成することができる。
【００７７】
また、外径の変動が±１％に形成された絶縁体２の外周には、プラスチックテープ体を持って、巻回角度８０度で重なりを無くして巻回された外径保持層５６を設けても良い。この外径保持層５６は、絶縁体２の外径を±１％に成形した後、成形された外径が時間の経過と共に元に戻るのを阻止する為のものであり、厚さ０．０２５ｍｍ、幅７．５ｍｍのポリエチレンテレフタレートテープ等を適用することができる。
【００７８】
外径の変動が±２％に形成された絶縁体２の外周には、外部導体３が形成される。外部導体３は編組体により構成され、編組体の適用仕様は、上記した内容と同じである。異なる点は、編組の仕方であり、編組の仕方は、図８（ロ）に示すように、従来の編組の編み方が各打数の内、２打を上にして（この場合２オーバーとする）、次は他の２打の下を通って（この場合２アンダーとする）編組されている。
【００７９】
本実施の形態は、この編み方を適用してもよいが、図８（イ）に示す各打数の編み方が１打毎に１オーバー、１アンダーで編組すると、各打が締まり、絶縁体２との密着力が大きくなり、絶縁体２の保持力が大きくなる。更に編組体自体が各打の締まりにより円筒化し易くなる。
【００８０】
次に、絶縁体２が、テープ幅を絶縁体２の外径の３倍として、テープ体幅の精度を±１％として、巻回角度８０度をもって、内部導体１の外周に重ねをなくして巻回される場合（請求項４に対応）の絶縁体２の構成方法を、図９を参照して説明する。
【００８１】
撚り合わせ導体（内部導体）１を、テープ巻装置の第１、第２、第３、第４のガイドダイス９３ａ，９３ｂ，９３ｃ，９３ｄと、成形ダイス９４とに、図示せぬ供給部から供給して挿通する。この供給された導体１は、矢印Ｙ１の方向に所定回転数で図示せぬ回転駆動部の回転駆動により回転され、図示せぬ引き取り部によって所定速度で矢印Ｙ２の方向に引き取られる。
【００８２】
第１のガイドダイス９３ａを通過した導体１は、第２のガイドダイス９３ｂの手前で、テープ体供給部９１から所定角度をもって供給される多孔質テープ体２１ｃが、導体１の矢印Ｙ１の回転と、矢印Ｙ２の進行とにより、その外周に重ね無しで巻回される。
【００８３】
テープ２１ｃが巻回された導体１は、第２のガイドダイス９３ｂを通過し、第３のガイド９３ｃの手前で、テープ体供給部９２からテープ２１ｃと反対方向に供給されるテープ体２１ｄが、その外周に巻回される。このテープ巻回により、テープ体２１は重ね無しで導体１に二重に巻回される。テープ体２１ｄを巻回して、第３のガイドダイス９３ｃを通過したテープ巻体は、第３と第４のガイドダイス９３ｃ，９３ｄ間に配置された成形ダイス９４に挿通され、内径１・１２ｍｍ、ダイス長３．００ｍｍのダイスを通ることにより、絶縁体２の外径の変動が±２％で成形される。
【００８４】
以上のテープ体２１の巻回と成形により、絶縁体２の外径は真円状になり、導体１との密着が向上して、厚さの不均一、外径の凸凹、外径のバラツキ等が減少される。テープ巻体２１を成形ダイス９４で成形した後に、その成形精度を維持させる為に、第４のガイドダイス９３ｄにおいて厚さが薄くても機械的強度の高いテープ体２１を巻回して外形保持層を設けても良い。
【００８５】
次に、絶縁体２が、多孔質テープ体２１を少なくとも２枚以上有し、各々テープ幅間隔で、内部導体１の外周に、互いに同方向に重ねをなくして巻回されて構成される場合（請求項５に対応）の絶縁体２の構成方法を、図１０を参照して説明する。
【００８６】
第２のガイドダイス９３ｂの手前で、第１のテープ供給部９１から供給された多孔質テープ体２１ｃを、テープ体幅の間隔で導体１の外周に巻回する。次に、ガイドダイス９３ｃの手前で、先に巻回されたテープ体の巻回されていない所に、第２のテープ供給部９２から供給されたテープ体２１ｄを巻回する。このように２つのテープ体２１ｃ、２１ｄを、重ねを無くして巻回することにより、導体１の外周にテープ巻回により生じる凸凹、外形のバラツキ等を少なくすることができる。絶縁体比誘電率のバラツキをも少なくすることができる。ガイドダイス９３ｃを通過して、重ねを無くして巻き回されたテープ巻体２１を、成形ダイス９４に挿通して、テープ巻体２１の外形変動を±１％で成形する。テープ巻体２１の外周に、他のテープ体を巻回して外形保持層を成形しても良い。
【００８７】
次に、各同軸ケーブルの構造およびその特性を、次の表１および表２に表す。
【００８８】
【表１】

【表２】

これら表１および表２において、内部導体は、銀メッキ軟銅線の０．１６ｍｍの７ケ撚りとし、絶縁体の多孔質テープ体は、孔多率７０％のＰＴＦＥテープ体を適用した。外部導体は、銀メッキ軟銅線を適用したものはＡｇで表示し、軟銅線そのものを適用したものはＣｕで表示し、錫合金メッキ軟銅線を適用したものはＡｇ−Ｓｎで表示した。本発明であるＡｇ−Ｓｎのもので絶縁体、編組体ともに成形ダイスに挿通して成形したものをＳＭＬ１で表し、絶縁体、編組体ともに成形しないものをＳＭＬ２で表した。
【００８９】
上記の各同軸ケーブルの特性を比較するために実施した試験の内容を、次の▲１▼〜▲３▼に記述する。
【００９０】
▲１▼曲げ試験：５００ｍｍにカットしたケーブルの特性インピーダンス値（Ａ）を測定し、ケーブルの中央部約２００ｍｍを外径５．０ｍｍのマンドレルに張力２００ｇで１０回巻き付け、その状態での特性インピーダンス値（Ｂ）を測定し、（Ａ）−（Ｂ）にて特性インピーダンス値の変化を求める。その結果を表１に表した。結果として、編組体素線に動摩擦係数の小さい錫合金を用いて、絶縁体、編組体共に、その外径を成形したので特性インピーダンス値の変動が少なく、ケーブルの柔軟性が良くなり、曲げによる特性インピーダンス値の変化が小さくなった。
【００９１】
▲２▼柔軟性試験：長さ１５０ｍｍとしたケーブルの略中央部に７２ｍｍの標線を付け、温度２３±２℃、相対湿度６５％以下で２時間放置した試験片２本を、その両端を４０ｍｍ迄に圧縮させた時の力の値を求める。その結果を表１に示した。結果として、編組体素線に錫合金メッキ軟銅線を用いて、編組体としたので、編組体の各素線が動き易くなり、柔軟性が良くなった。
【００９２】
▲３▼特性インピーダンスの測定値：ＴＤＲ測定法を適用して、先のＳＭＬ１，２の測定値を表２に示す。結果として、ＳＭＬ１の特性インピーダンスはバラツキが少なく安定しており、ＳＭＬ２は、特性インピーダンスのバラツキが大きく、±１Ωを満足することができない。
【００９３】
【発明の効果】
以上説明したように、本発明によれば、内部導体、発泡絶縁体、外部導体、外被の順で内部から外部へ向かい形成される高精度発泡同軸ケーブルを、内部導体の外径寸法の精度を４／１０００ｍｍ以下とし、発泡絶縁体の外径寸法の精度を±０．０２ｍｍにすると共に、その形状を真円状に形成し、外部導体の外径寸法の精度を外径中心値の±２％にすると共に、その形状を真円状に形成し、発泡絶縁体を介在した内部導体と外部導体間の特性インピーダンス値の精度を±１Ωとしたので、高精度発泡同軸ケーブルを構成する内部導体、絶縁体、外部導体等の外形の凸凹と外径のバラヅキを少なくして外径寸法の精度を向上させ、各部材が真円状にすることができ、特性インピーダンス値の変動を少なくすることができる。従って、ケーブルに柔軟性を持たせることができ、特性インピーダンス値を±１Ωにすることができた。又、特性インピーダンス値は、ケーブルに各種機械的ストレスが付加されてもその精度を維持することができた。
【００９４】
また、上記の内部導体は、外径寸法の精度が２／１０００ｍｍ以下で、１〜３μｍ厚の銀メッキが施された銀メッキ軟銅線を撚り合わせて成り、その撚り合わせピッチが、層芯径の２０倍以下であるようにしたので、特性インピーダンス値の変動を少なくする為の、内部導体の凸凹と外径変動を小さくすることができる。従って、内部導体に柔軟性と、機械的強度を持たせて、更に特性インピーダンス値を±１Ωにすることができた。
【００９５】
また、発泡絶縁体は、多孔質テープ体を内部導体の外周に、角度８０度、１／２重ね巻きで巻回して成り、この巻回後の発泡絶縁体の厚さの変動が±０．０１ｍｍ、外径の変動が±０．０２ｍｍであるようにしたので、内部導体と絶縁体間のテープ巻回により生じる空隙を無くして内部導体と絶縁体の密着度を大きくし、絶縁体外形を真円状に近づけて、外径のバラツキを少なくすることができる。従って、ケーブルに機械的ストレスが付加されても絶縁体形状が変化せず、内部導体との密着を維持することができて、特性インピーダンス値の変化を小さくすることができた。
【００９６】
また、発泡絶縁体は、多孔質テープ体を内部導体の外周に、多孔質テープ体自体が重ならないように巻回角度８０度で巻回して成り、その巻回される多孔質テープ体の幅が発泡絶縁体の外径寸法の３倍で且つその幅の精度が±１％である。さらに、発泡絶縁体は、多孔質テープ体を少なくとも２枚以上有し、各々がテープ幅間隔で内部導体の外周に同方向に重ならないように巻回されて成るようにしたので、テープ体の巻回により構成される絶縁体のテープ体の重ねを無くして、テープ体巻回の重ねにより生じる導体と絶縁体間の空隙及び絶縁体外周の空隙と凸凹がなくなり、外径のバラツキが少なくなり、絶縁体の比誘電率が一定化する。従って、テープ巻き工程でのテープ断線が無くなり生産性が向上した。
【００９７】
また、発泡絶縁体は、その外周にポリエチレンテレフタレートのプラスチックテープ体を巻回して構成される外径保持層を有するので、絶縁体外径の凸凹、変動を押さえ、絶縁体外径を均一化すると共に、絶縁体の機械的強度を強化できる。従って、絶縁体の機械的強度を向上させ、特性インピーダンス値を±１Ωにすることができた。
【００９８】
また、多孔質テープ体は、その気孔率が６０％以上、気孔精度が±５％、厚さの公差が±３μｍ、圧縮応力が０．２４〜０．２８Ｋｇ重である場合に、圧縮変形歪みが０．６〜０．８％の焼成ＰＴＦＥテープ体である。さらに、多孔質テープ体は、その気孔率が６０％以上、気孔精度が±５％、厚さの公差が±３μｍである重量平均分子量５００万以上のポリエチレンテープ体であるようにしたので、発泡絶縁体を構成する多孔質テープ体の比誘電率と、厚さと、機械的強度等のバラツキを少なくして、絶縁体の比誘電率と外径の変動を少なくするとともにテープ体の巻回張力を一定化とすることができる。従って、特性インピーダンス値を±１Ωにすることができた。
【００９９】
また、外部導体は、厚さ１〜３μｍの銀メッキ軟銅線に、厚さ０．２〜０．５μｍの錫合金メッキを施して外径公差±２／１０００ｍｍとした２層メッキ軟銅線の編組体により成る。さらに、外部導体は、厚さ１〜３μｍのニッケルメッキ軟銅線に、厚さ０．２〜０．５μｍの錫合金メッキを施して外径公差±２／１０００ｍｍとした２層メッキ軟銅線の編組体により成るので、編組体を構成する各打の素線が、ケーブルに機械的ストレスを受けた際に個々に移動可能となる。又編組体の滑り性が向上したので柔軟性が良くなり、滑り性と柔軟性とが向上したので編組体の成形が可能となり、編組体の凸凹外径変動を小さくして、絶縁体への密着度が向上する。従って、ケーブルの柔軟性を向上させ、機械的ストレスが付加されても特性インピーダンス値の変化を小さくすることができた。
【０１００】
また、錫合金メッキは、錫と銅とから成り、銅の含有比率は０．６〜２．５％であるようにしたので、銅の拡散が防止され、ウィスカの発生、成長が抑制され、導電率を維持した編細体とし、編組体素線の滑り性が良くなる。従って、ケーブルに柔軟性をもたせ、特性インピーダンス値の精度を保つことができた。
【０１０１】
また、外部導体を構成する編組体は、編組体を構成する各編組打数が１オーバー１アンダーで編組したので、編組体を構成する各打が１オーバー・１アンダーで編組されるので、編組体自体の形状維持力が大きくなるので絶縁体を保持する保持力が大きくなり、絶縁体との密着が向上する。従って、編組体が柔軟性を有したまま、形状維持力、絶縁体保持力が大きく成るので、ケーブルに付加される機械的ストレスの影響が少なく、特性インピーダンス値の変化を小さくすることができる。
【０１０２】
また、外被は、その厚さを外部導体の厚さの０．５倍以上の厚さとし、この厚さの精度を３／１００ｍｍ以下とし、外部導体との密着力を２３℃において２０ｇ／ｍｍ²以上とし、ＦＥＰ樹脂の押し出し成形により成るようにしたので、外部導体の円筒状外形を維持して、その解放を抑えることができ、特性インピーダンス値の精度を向上させることができる。従って、ケーブルに柔軟性を持たせ、特性インピーダンス値の精度を保つことができた。
【０１０３】
以上説明したとおり、本発明の高精度発泡同軸ケーブルは、柔軟性を有して、ケーブルに加わる曲げ、捻り、摺動等の機械的ストレスを受けても、その影響を受けず、伝送特性が安定し、機械的ストレスを受けても伝送特性の変動が少なくでき、且つ特性インピーダンス値の精度を小さくできるので、工業化に際して多大な効果を有する。
【図面の簡単な説明】
【図１】本発明の実施の形態に係る高精度発泡同軸ケーブルの構成を示す斜視図である。
【図２】上記実施の形態に係る高精度発泡同軸ケーブルにおける多孔質テープ体を内部導体外周に巻回した構成を示す図である。
【図３】上記実施の形態に係る高精度発泡同軸ケーブルにおける多孔質テープ体の巻回方法を説明するための図である。
【図４】上記実施の形態に係る高精度発泡同軸ケーブルにおける外部導体の製造方法を説明するための図である。
【図５】他の実施の形態に係る高精度発泡同軸ケーブルの構成を示す断面図である。
【図６】他の実施の形態に係る高精度発泡同軸ケーブルにおいて、２枚の多孔質テープ体を、重ねを無くして巻回した線心の断面図である。
【図７】他の実施の形態に係る高精度発泡同軸ケーブルにおいて、２枚の多孔質テープ体を互いに所定間隔で巻回する様子を示す図である。
【図８】他の実施の形態に係る高精度発泡同軸ケーブルにおける編組体の構造を示す図である。
【図９】他の実施の形態に係る高精度発泡同軸ケーブルにおいて、２枚の多孔質テープ体を、重ねを無くして巻き回する様子を示す図である。
【図１０】他の実施の形態に係る高精度発泡同軸ケーブルにおいて、２枚の多孔質テープ体を、互いに所定間隔で巻き回する様子を示す図である。
【符号の説明】
１ 内部導体
２ 絶縁体（発泡絶縁体）
３ 外部導体
４ 外被
１０ 絶縁線心
２１，２１ａ，２１ｂ，２１ｃ，２１ｄ 多孔質テープ体
１５，９１，９２ テープ体供給部
３０ａ，３０ｂ，３０ｃ，４１，４２，９３ａ，９３ｂ，９３ｃ，９３ｄ ガイドダイス
３１ａ，３１ｂ，４３，９４ 成形ダイス
４０ 編組装置
４４ 編組用素線
５０，５５ 他の実施の形態の高精度発泡同軸ケーブル
５６ 外径保持層
ａ，ｂ 絶縁体２の外部の空隙部
Ｙ１ 回転方向
Ｙ２ 移動方向[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-precision foamed coaxial cable in which an insulator around an inner conductor is formed of a porous tape body and an outer conductor is formed of a braided shield body, for example, an information communication device and a semiconductor element applied to the device The present invention relates to a high-precision foamed coaxial cable that is applied to the test / inspection equipment and the like and has little change in characteristic impedance value.
[0002]
[Prior art]
With the advancement of the advanced information society in recent years, there is an increasing demand for an increase in transmission speed and an improvement in transmission accuracy of information communication devices and semiconductor element test / inspection devices applied to the devices. For this reason, even in the case of a coaxial cable and a coaxial cord that are applied to the devices and apparatuses, an increase in transmission speed and an improvement in transmission accuracy are required.
[0003]
Here, typical electrical characteristics required for the coaxial cable are described as follows.
[0004]
Propagation delay time (Td) = √ε / 0.3 (nS / m)
Relative transmission speed (V) = 100 / √ε (%)
Characteristic impedance (Zo) = 60 / √ε · LnD / d (Ω)
Capacitance (C) = 55.63ε / LnD / d (PF / m)
Where ε is the dielectric constant of the insulator, D is the outer diameter of the insulator (the inner diameter of the outer conductor), and d is the outer diameter of the conductor (the outer diameter of the inner conductor).
[0005]
Therefore, the transmission characteristics of the coaxial cable are related to the relative dielectric constant of the insulator, the outer diameter of the inner conductor and the insulator. The smaller the value of the relative dielectric constant, the better the transmission characteristics, and the inner conductor. As for the outer diameter of the insulator, it can be understood that the ratio and variation are largely involved. In particular, with respect to the characteristic impedance and capacitance, the relative dielectric constant of the insulator is small and its variation is small, and there are few variations such as the outer diameter of the inner conductor and the insulator (inner diameter of the shield layer). It can be understood that it is ideal to form the shape of a more perfect circular cylinder.
[0006]
[Problems to be solved by the invention]
However, the conventional coaxial cable has the following problems (1) to (4).
[0007]
(1) The inner conductor applied to the coaxial cable is an AWG 20-30 silver-plated annealed copper wire or a twisted conductor obtained by twisting them, but the outer diameter tolerance of the silver-plated annealed copper wire is ± 3/1000 mm. Yes, in the case of twisted conductors, for example, when these seven twists are twisted, the tolerance of the twisted outer diameter becomes ± 3 × 3/1000 mm. For this reason, if the cable is made within the tolerance of the outer diameter of those, it becomes a large variation factor in the above-mentioned characteristic impedance, capacitance and the like. This effect increases as the inner conductor becomes thinner.
[0008]
(2) The foam insulator applied to the coaxial cable is designed to reduce the propagation delay time of the cable as much as possible and increase the transmission speed. At present, the porosity (foaming rate) is set to 60% or more. By providing a large number of gaps, the dielectric constant (ε) of the insulator is set to 1.4 or less, thereby shortening the transmission time, reducing the attenuation, and the like. As an insulator material having a porosity of 60% or more and a relative dielectric constant of 1.4 or less, a porous tape body of polytetrafluoroethylene (PTFE) (Japanese Patent Publication Nos. 42-13560 and 51-18991) (Patent Documents etc.) are wound around the outer circumference of the inner conductor and fired at the time of winding or after winding. Other porous tapes having a weight average molecular weight of 5 million or more are used. Is applied (Japanese Patent Application No. 2000-110443).
[0009]
However, these insulator layers have large variations in thickness and porosity due to the properties of the porous tape body, and there is a strong demand for improvement in the stability of the transmission characteristics of the coaxial cable. In particular, a coaxial cable with an inner conductor size of AWG24 or larger and a characteristic impedance value of 50Ω is stabilized by eliminating variations in transmission characteristics due to variations in thickness, outer diameter, porosity, firing, etc. It was a major obstacle.
[0010]
In addition, since the insulator layer is formed by laminating and winding a porous tape body on the outer periphery of the inner conductor, an irregularity of the outer shape due to the gap portion and the overlap occurs in the overlapping portion of the tape body on the outer periphery of the conductor, and the relative dielectric constant In addition, the variation in the outer diameter becomes extremely large.
[0011]
In addition, since this insulator layer is formed by winding a porous tape body having a very low mechanical strength, in order to eliminate elongation and breakage during winding of the tape body itself, and to extend and break the ultrafine internal conductor. In order to eliminate this, the tension of the tape body needs to be extremely small. For this reason, the insulator after winding is further increased in unevenness in outer shape and variation in outer diameter, is very weak in contact with the inner conductor, and is further expanded in variation in relative permittivity and outer diameter.
[0012]
Furthermore, this insulator layer has a relatively low dielectric constant mainly for the purpose of increasing the transmission speed by minimizing the propagation delay time of the cable, so that the mechanical strength, that is, the bending and twisting that the coaxial cable undergoes. However, it still has the disadvantage that it is difficult to maintain the structural dimensions of the coaxial cable due to mechanical stress such as pressing and sliding. The biggest drawback is that it is difficult to maintain the insulator outer diameter at a predetermined outer diameter to eliminate the variation and to form the insulator in a cylindrical shape.
[0013]
(3) The outer conductor that is largely involved in the transmission characteristics of the coaxial cable is a conventional type of coaxial cable in which a plastic tape body having a metal layer such as copper is wound around the outer periphery of the insulator or vertically attached. Or a braided body braided with silver-plated or tin-plated soft copper wire with an outer diameter tolerance of ± 3/1000 mm according to JIS standards, and the above tape body and the above braided body A combination of the above and the like has been applied.
[0014]
However, when the tape body is wound or vertically attached, the flexibility of the cable is insufficient, and the external conductor is easily broken due to mechanical stress such as bending or twisting applied to the cable. The function cannot be performed. In the braided body of silver-plated annealed copper wire, since the sliding property of silver is small, the frictional force due to the contact between the silver-plated annealed copper wires increases, and each braided body is configured by mechanical stress such as bending and twisting applied to the cable. There is no movement of the wire, the cable lacks flexibility, the insulation layer is deformed, the characteristic impedance value fluctuates, the influence of mechanical stress cannot be reduced, the cable life is shortened, etc. Built-in topic.
[0015]
In a braided body of tin-plated annealed copper wire, when used at a high temperature (80 ° C. or higher), copper diffuses into the tin-plated layer and promotes the generation and growth of tin whiskers by diffusion stress. When this whisker grows greatly, it may break through the ultrathin insulator and cause a short circuit with the internal conductor. Further, as described in the description of the insulator in (2) above, each of the above outer conductors is formed on the outer periphery of the insulator with the unevenness of the outer shape of the insulator and the variation of the outer diameter. The inside and outside of the conductor was uneven, and the variation in outer diameter remained large, and there were many gaps between the outer conductor and the insulator layer, leaving a factor of variation in the relative permittivity.
[0016]
{Circle around (4)} The outer jacket provided on the outer conductor outer periphery is conventionally formed of a material made of vinyl chloride resin, polyethylene resin, fluororesin, or a material obtained by cross-linking them. In this configuration, priority is given to protecting the outer conductor, eliminating the movement of the outer conductor, and making the finished outer diameter as thin as possible, and the gap resin of the braided body is filled with the jacket resin. For this reason, when mechanical stress such as bending, twisting, sliding, etc. is applied to the coaxial cable, the coaxial core is allowed to move in the jacket to relieve the stress (movement of each strand of the braided body). I couldn't.
[0017]
The present invention has been made in view of the above points, and increases the transmission speed, improves the characteristic impedance value, improves the flexibility of the cable, and bends, twists, presses, slides, etc. applied to the cable. It is an object of the present invention to provide a high-precision foamed coaxial cable that can maintain a predetermined mechanical strength and reduce changes in characteristic impedance values by reducing the stress even when subjected to mechanical stress.
[0018]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the high-precision foamed coaxial cable of the present invention is a foam insulation having a low dielectric constant by an inner conductor formed by twisting a plurality of conductive wires and a porous tape body formed on the outer periphery of the inner conductor. Body and the outer periphery of this foam insulation A two-layer plated annealed copper wire in which tin alloy plating is applied to an annealed copper wire plated with silver or nickel In a high-precision foamed coaxial cable composed of an outer conductor made up of a large number of braided conductive wires and an outer sheath made of heat-resistant resin formed on the outer periphery of the outer conductor, the accuracy of the outer diameter of the inner conductor is 4 / 1000 mm or less, the accuracy of the outer diameter of the foamed insulator is ± 0.02 mm, the shape is formed in a perfect circle, and the accuracy of the outer diameter of the outer conductor is ±± of the center value of the outer diameter. 2%, the shape is formed into a perfect circle, and the accuracy of the characteristic impedance value between the inner conductor and the outer conductor with the foamed insulator interposed is set to ± 1Ω.
[0019]
According to this configuration, It has flexibility and is not affected by mechanical stress such as bending, twisting and sliding applied to the cable. The accuracy of the outer diameter can be improved by reducing the unevenness of the outer diameter and the outer diameter of the inner conductor, insulator, outer conductor, etc. constituting the high-precision foamed coaxial cable, and each member can be made into a perfect circle. Thus, fluctuations in the characteristic impedance value can be reduced.
[0020]
The inner conductor is formed by twisting a silver-plated annealed copper wire with a silver plating thickness of 1 to 3 μm with an accuracy of an outer diameter dimension of 2/1000 mm or less, and the twist pitch is the layer core diameter. It is characterized by being 20 times or less.
[0021]
According to this configuration, it is possible to reduce the unevenness of the inner conductor and the outer diameter fluctuation in order to reduce the fluctuation of the characteristic impedance value.
[0022]
The foamed insulator is formed by winding the porous tape body around the inner conductor with an angle of 80 degrees and ½ lap winding, and the thickness of the foamed insulator after the winding varies. It is characterized by a variation of ± 0.01 mm and an outer diameter of ± 0.02 mm.
[0023]
According to this configuration, the gap generated by winding the tape between the inner conductor and the insulator is eliminated, the adhesion between the inner conductor and the insulator is increased, the outer shape of the insulator is made close to a perfect circle, and the variation in outer diameter is reduced. Can be reduced.
[0024]
The foamed insulator is formed by winding the porous tape body around the inner conductor at a winding angle of 80 degrees so that the porous tape body itself does not overlap, and the wound porous tape. The width of the body is three times the outer diameter of the foamed insulator, and the accuracy of the width is ± 1%.
[0025]
Further, the foamed insulator has at least two or more of the porous tape bodies, and each of the foamed insulators is wound so as not to overlap the outer periphery of the inner conductor in the same direction at a tape width interval. .
[0026]
According to these configurations, there is no overlap of the tape body of the insulator constituted by winding the tape body, and the gap between the conductor and the insulator and the gap and irregularities on the outer periphery of the insulator caused by the tape body winding overlap. This eliminates the variation in the outer diameter and stabilizes the relative dielectric constant of the insulator.
[0027]
Further, the foamed insulator has an outer diameter holding layer formed by winding a polyethylene terephthalate plastic tape body on the outer periphery thereof.
[0028]
According to this configuration, it is possible to suppress irregularities and fluctuations in the outer diameter of the insulator, uniformize the outer diameter of the insulator, and enhance the mechanical strength of the insulator.
[0029]
The porous tape body is compressed and deformed when the porosity is 60% or more, the porosity accuracy is ± 5%, the thickness tolerance is ± 3 μm, and the compressive stress is 0.24 to 0.28 kg weight. It is characterized by being a sintered PTFE tape body having a strain of 0.6 to 0.8%.
[0030]
The porous tape body is a polyethylene tape body having a weight average molecular weight of 5 million or more having a porosity of 60% or more, a porosity accuracy of ± 5%, and a thickness tolerance of ± 3 μm. .
[0031]
According to these configurations, variations in the relative dielectric constant, thickness, and mechanical strength of the porous tape body constituting the foamed insulator are reduced, and fluctuations in the relative dielectric constant and outer diameter of the insulator are reduced. In addition, the winding tension of the tape body can be made constant.
[0032]
The outer conductor is a two-layer plated annealed copper wire having an outer diameter tolerance of ± 2/1000 mm by subjecting a silver plated annealed copper wire with a thickness of 1 to 3 μm to a tin alloy plating with a thickness of 0.2 to 0.5 μm. It is characterized by comprising a braided body.
[0033]
The outer conductor is a two-layer plated annealed copper wire having an outer diameter tolerance of ± 2/1000 mm by applying a 0.2 to 0.5 μm thick tin alloy plating to a nickel plated annealed copper wire having a thickness of 1 to 3 μm. It is characterized by comprising a braided body.
[0034]
According to these configurations, the strands of each striking wire constituting the braided body can be individually moved when the cable is subjected to mechanical stress. In addition, since the sliding property of the braided body has been improved, the flexibility has been improved, and since the sliding property and the flexibility have been improved, the braided body can be molded, and the fluctuation in the outer diameter of the braided body can be reduced to reduce the fluctuation to the insulator. Adhesion is improved.
[0035]
The tin alloy plating is composed of tin and copper, and the content ratio of copper is 0.6 to 2.5%.
[0036]
According to this configuration, copper diffusion is prevented, whisker generation and growth are suppressed, and a knitted fabric that maintains electrical conductivity is obtained, and the slidability of the braided body wire is improved.
[0037]
The braided body constituting the outer conductor is characterized in that each braided striking part constituting the braided body is braided with 1 over 1 under.
[0038]
According to this structure, since each striking that constitutes the braided body is braided with 1 over and 1 under, the shape maintaining force of the braided body itself increases, so that the holding force for holding the insulator increases, and the insulator and Improved adhesion.
[0039]
In addition, the thickness of the outer cover is 0.5 times or more the thickness of the outer conductor, the accuracy of the thickness is 3/100 mm or less, and the adhesion with the outer conductor is 23 ° C. 20 g / mm ² As described above, it is characterized by being formed by extrusion molding of FEP resin.
[0040]
According to this configuration, it is possible to maintain the cylindrical outer shape of the outer conductor, suppress the release thereof, and improve the accuracy of the characteristic impedance value.
[0041]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0042]
(Embodiment)
FIG. 1 is a perspective view showing a configuration of a high-precision foamed coaxial cable according to an embodiment of the present invention.
[0043]
The high-precision foamed coaxial cable shown in FIG. 1 is configured by covering an inner conductor 1 having a plurality of strands with an insulator 2, an outer conductor 3 made of a braided body, and a jacket 4 in this order. As shown in FIGS. 2A and 2B, the insulated wire core 10 is formed by winding the inner conductor 1 and the porous tape body 21 around the inner conductor 1 in a 1/2 layer. It consists of an insulator 2 constructed.
[0044]
This high-precision foamed coaxial cable is applied to, for example, information communication equipment and semiconductor element testing / inspection equipment applied to the equipment, but the high-precision foamed coaxial cable is applicable to such equipment and equipment. The required characteristics are flexible and are not affected by mechanical stress such as bending, twisting, sliding, etc., and transmission characteristics, especially characteristic impedance values are stable, even if mechanical stress is applied. There are few fluctuations in the characteristic value, and furthermore, the outer diameter is small and the film has heat resistance.
[0045]
The conditions for improving the flexibility of the coaxial cable include the following items (1) to (6). (1) Each strand constituting the inner conductor 1 has flexibility, and each strand can move when it is a stranded wire. (2) The inner conductor 1 and the insulator 2 are not in close contact (integrated) and can be moved individually. (3) The outer conductor 3 is composed of a braided body. (4) The insulator 2 and the outer conductor 3 are not in close contact (integrated) and can be moved individually. (5) Each strand of the outer conductor 3 can be moved individually. (6) Conditions are required such that the outer conductor 3 and the outer jacket 4 are not in close contact (integrated) but can be moved individually. That is, in order to reduce the influence of mechanical stress and improve flexibility, it is an indispensable condition that the members 1, 2, 3, and 4 constituting the coaxial cable are individually movable.
[0046]
Further, the conditions for improving the accuracy of the characteristic impedance value of the coaxial cable include the following contents (1) to (4). (1) The strands constituting the inner conductor 1 are integrated and formed into a perfect circle, and the fluctuation of the outer diameter is small. (2) The insulator 2 has a constant relative dielectric constant, is formed in a perfect circle, has a small variation in outer diameter, and is in close contact (integrated) with the inner conductor 1. (3) The outer conductor 3 is integrated and formed into a perfect circular body, there is no fluctuation in the outer diameter and thickness, and the outer conductor 3 is in close contact (integrated) with one insulator. (4) The outer jacket 4 is tightly integrated with the outer conductor 3, and conditions such as restricting the movement of the outer conductor 3 within the outer jacket 4 are required. In other words, in order to improve the accuracy of the characteristic impedance value, it is indispensable to tightly integrate each component member, finish it into a perfect circle, reduce fluctuations in the outer diameter, and make the relative dielectric constant constant. . For these reasons, the conditions for making the coaxial cable flexible and the conditions for improving the accuracy of the characteristic impedance value are exactly the opposite.
[0047]
Therefore, in the high precision foamed coaxial cable of the present embodiment, the following conditions (1) to (5) are satisfied. {Circle around (1)} The inner conductor 1 is composed of a stranded wire, and the movement of each strand is possible, the stranded outer diameter is uniform, the fluctuation thereof is small, and the shape is a perfect circle. (2) For the insulator 2, a porous tape was applied to reduce the relative dielectric constant so that the porosity, thickness, and mechanical strength were constant. (3) The insulator 2 is composed of a porous tape body, and is tightly integrated with the inner conductor 1 so that the relative permittivity, thickness, and appearance thereof are small and the outer diameter is a perfect circle. . (4) The outer conductor 3 is composed of a braided body, has a large shape maintaining force, has flexibility, is tightly integrated with the insulator 2, has little fluctuation in outer diameter and thickness, and has a true inner diameter. It was made to be circular. (5) The outer sheath 4 has heat resistance and flexibility, and has a finished outer diameter with less influence on the outer conductor 3, the insulator 2, and the inner conductor 1 even when subjected to heat and mechanical stress. Was made thin.
[0048]
From this, the high-precision foamed coaxial cable of the present embodiment has a thickness of the inner conductor 1 (the conductor size is described in an example in which AWG # 26 is applied) as shown in FIGS. An annealed copper wire with a silver plating of 1 to 3 μm, whose outer diameter is 0.16 mm and whose outer diameter accuracy is 2/1000 mm or less is applied as a twisted conductor. In the form, as seven twisted conductors, the twisted pt is 20 times or less the layer core diameter, External dimensions The accuracy was set to 4/1000 mm or less.
[0049]
In order to make the outer diameter accuracy of the silver-plated annealed copper wire less than 2/1000 mm, the inner diameter accuracy of the wire drawing die should be 1/1000 mm or less, and the physical property management and take-up speed should be ± 1%. Do. Moreover, in order to make the twisted outer diameter accuracy 4/1000 mm or less, the winding tension at the time of twisting is set to ± 5%.
[0050]
The reason for limiting the outer diameter accuracy and the twisted outer diameter accuracy of the silver-plated annealed copper wire is to reduce the variation in the outer diameter of the inner conductor 1 in the thin coaxial cable, and to form it into a perfect circle, thus characteristic impedance This is an indispensable condition for eliminating the fluctuation of the value and improving its accuracy.
[0051]
When the outer diameter accuracy of each strand is 3/1000 mm or less, the variation of the seven twisted outer diameters is expressed by Equation 1. On the other hand, when the accuracy of the twisted outer diameter is 5/1000 mm, the characteristic impedance value ± 1Ω is satisfied when the outer diameter of the insulator 2 fluctuates by 0.02 mm from the formula for calculating the characteristic impedance value described in the conventional example. I can't understand.
[Formula 1]

[0052]
The insulator 2 has a porosity of 60% or more, an accuracy of ± 5%, a thickness tolerance of ± 3 μm, and a compressive deformation strain of 0.24 to 0.28 kg weight when the compressive stress is 0.24 to 0.28 kg. Miga A tape having a width of 4.6 mm and a thickness of 0.09 mm by applying a 0.6 to 0.8% sintered porous PTFE tape or a polyethylene porous tape having a weight average molecular weight of 5 million or more. The body was wound at a winding angle of 80 degrees and 1/2 lap on the inner conductor, and a tape body having a width of 6.9 mm and a thickness of 0.09 mm was wound at a winding angle of 80 degrees and ½ lap. Construct by winding.
[0053]
Insulated wire core 10 formed by winding a tape body is formed such that the variation in outer diameter is ± 1.5% of the center value of the outer diameter of the insulator. The porosity is set to 60% or more and the accuracy is set to ± 5% in order to increase the propagation delay time (satisfies a relative dielectric constant of 1.4 or less). This is because the accuracy of the relative dielectric constant of the insulator is affected. The reason why the tolerance of the thickness is ± 3 μm and the overlap of the winding of the tape is ½ is to increase the accuracy of the thickness of the insulator 2.
[0054]
Compressive stress But 0.24-0.28kg weight If Compressive deformation strain Only The reason why the sintered PTFE tape of 0.6 to 0.8% is used and the winding angle is set to 80 degrees is to reduce the collapse of the tape body during winding. The method of forming the fluctuation of the outer diameter of the insulator 2 to ± 1% is a molding die for forming the outer diameter of the insulator 2 to a predetermined outer diameter after winding the tape body or when forming a braided body layer to be described later. The insulating wire core 10 is inserted and formed by a molding process.
[0055]
This molding process eliminates the voids a and b around the inner conductor 1 and the outside of the insulator 2 generated by the porous tape body (tape wound body) 21 shown in FIGS. The insulator 2 is closely attached to the inner conductor, and the irregularities on the inner and outer circumferences of the insulator 2 due to winding are eliminated. By this treatment, the thickness of the insulator 2 is made uniform, variation in the outer diameter is eliminated, and the outer diameter is formed in a perfect circular cylindrical shape.
[0056]
This molding process is possible because the thickness of the porous tape body 21 is limited to the above numerical value even when the porosity of the porous tape body 21 is 60% or more. In a conventional coaxial cable with a degree of foaming of 70 or more that only increases the transmission speed, the mechanical strength of the porous tape body 21 is weak, and the outer diameter of the insulator 2 varies and is uneven.
[0057]
An outer conductor 3 is formed on the outer periphery of the insulating wire core 10, that is, the outer periphery of the insulator 2, whose outer diameter variation is ± 1.5%. The outer conductor 3 is applied with an annealed copper wire having an outer diameter of 0.05 to 0.10 mm, and a silver or nickel plating layer having a thickness of 1 to 3 μm is applied to the outer periphery thereof. 0.2-0.5 Applying a plated layer of tin alloy of μm, applying an annealed copper wire having a two-layer plating layer with an outer diameter tolerance of ± 2/1000 mm, braiding at a braid angle of 65 to 75 ° and a braid density of 95% or more, and braiding the body's Outer diameter accuracy Of outer diameter ± 2 % To form.
[0058]
The reason why the braided body is applied to the outer conductor 3 is that the insulator 2 and the outer conductor 3 are not damaged when bending, twisting, pressing, sliding, or other mechanical stress is applied to the high-precision foamed coaxial cable. And to make the cable flexible.
[0059]
In addition, applying an annealed copper wire having two plating layers, a silver or nickel plating layer and a tin alloy plating layer, to the braided wire reduces the frictional resistance on the surface of the wire and reduces slipping. Better, when the mechanical stress is applied to the cable, each strand is easy to move, the stress is distributed and does not affect the insulator 2, and the shape of the braid is maintained to hold the insulator 2 In order to prevent the braided body from buckling, the internal stress is prevented from being released.
[0060]
The reason why the tin alloy plating layer is provided on the outer periphery of each element wire is to improve the above-described sliding property and to prevent whisker. The content of the tin alloy is composed of tin and copper, and the copper content is 0.6 to 2.5%. Moreover, what is generally called lead-free solder plating, such as silver containing 0.3 to 3.5% and bismuth 1 to 10%, is also applicable. It is effective to apply tin plating with a high conductivity and a small dynamic friction coefficient for the plating configuration of each strand. However, with tin alone, copper diffuses into the tin plating layer when used at high temperatures. This is because the generation and growth of whiskers are promoted by the diffusion stress, and the shorted between the inner conductor 1 and the outer conductor 3 due to the grown whiskers is prevented. To prevent whiskers, the following (1) to (4) are used. It is effective.
[0061]
(1) Prevent internal copper diffusion. (2) Add additives to tin. (3) Reduce internal stress due to heat treatment. (4) Reduce the plating thickness. Here, providing a plating layer such as silver plating or nickel plating prevents copper from being diffused, but since the dynamic friction coefficient is large, the movement of the wires deteriorates and the flexibility of the cable is lost.
[0062]
In order to improve the movement between the strands and make the cable flexible, on the above plating layer, 0.2-0.5 This was achieved by applying an annealed copper wire with a μm tin alloy hot-plated layer. The thickness of the underlying silver or nickel plating layer of 1 to 3 μm is required to be 1 μm or more to prevent copper diffusion, but if it is too thick, the flexibility of the cable is adversely affected. If the thickness of the tin alloy plating is 0.2 μm or less, the underlying silver plating is exposed and lacks flexibility, and if it is 0.5 μm or more, whiskers are likely to occur. Here, the outline of the dynamic friction coefficient of each metal is described as follows: 1.30 for silver, 0.90 for copper, and 0.55 for tin alloy. It can be understood that it is effective to apply to a body wire. In addition, the dynamic friction coefficient of each metal was calculated | required with the Bowden type | mold low load abrasion tester.
[0063]
The outer diameter accuracy of the braided body Of outer diameter By forming to ± 2%, the braided body layer becomes narrowed in the length direction, the gap of the braided body itself disappears, and the braided body is in close contact with the insulator so that the space between the braided body and the insulator The void portion is also eliminated, the inner diameter of the braided body becomes closer to a perfect circular cylindrical shape, and the characteristic impedance value is made constant and its fluctuation is reduced. The method of forming the outer diameter accuracy of the braided body layer to ± 2% is that the braided body layer is formed on a forming die for forming the outer diameter of the braided body layer to a predetermined outer diameter after braiding or when forming a coaxial cable jacket 4 described later. It is made by a molding process by inserting an attached wire core.
[0064]
Since this molding process is limited to the above-described content of the porous tape body 21, the mechanical strength of the insulator 2 is improved. Further, the outer diameter of the insulator 2 is not changed and irregularities are eliminated, and the outer diameter of the braid is changed. It became possible because there were no irregularities, and furthermore, by configuring the braided body with an annealed copper wire having a tin alloy plating layer, it became possible to insert into the forming die with a reduced frictional resistance, and to perform the forming process .
[0065]
In addition, in a conventional tape-insulated coaxial cable with a foaming degree of 70 or more that only increases the transmission speed, this braiding shield layer has a large outer diameter variation and outer diameter unevenness, so this molding process cannot be performed. It was.
[0066]
By the above molding process Braided Outside diameter accuracy The outer diameter center value On the outer periphery of the braid body layer molded to ± 2%, the thickness of the jacket 4 is 0.5 times or more the thickness of the outer conductor 3, and the adhesion with the braid body layer is 23 ° C. 20 g / mm ² As mentioned above, it is comprised by extrusion molding of FEP resin. Here, the reason for limiting the thickness is to maintain the shape of the braided body and prevent buckling when mechanical stress is applied to the cable, and the adhesion force is 20 g / mm. ² If it is less than this, the internal stress of the braided body cannot be released. As a result, the accuracy of the characteristic impedance value is not stable. Adhesive strength is 20 g / mm ² If it is above, release of an internal stress can be suppressed.
[0067]
Next, with reference to FIG. 3, a method for forming the winding of the porous tape body 21 and the variation of the outer diameter of the insulator 2 to ± 1.5% will be described.
[0068]
The twisted conductor (inner conductor) 1 is supplied from a supply unit (not shown) to the first, second, and third guide dies 30a, 30b, and 30c and the forming dies 31a and 31b of the tape winding device. The supplied conductor 1 is rotated at a predetermined rotational speed in the direction of the arrow Y1. The rotating conductor 1 is sent in the direction of the arrow Y2 at a predetermined speed, so that it passes through the first guide die 30a and then is supplied from the tape body supply unit 15 before the second die 30b. The tape body 21 is wound. This is because the porous tape body 21 is wound around the outer periphery of the conductor 1 in a 1/2 layer by rotating the conductor 1 itself in an arrow Y1 direction at an angle of 80 ° and a tape tension of 300 g with respect to the conductor 1, The tape body is once again wound around the outer periphery.
[0069]
Thus, the tape winding body wound around the porous tape body 21 and passed through the second die 30b includes first and second molding dies 31a, which are disposed between the second and third guide dies 30b and 30c. It is inserted into 31b. Here, the first forming die 31a having an inner diameter of 1.13 mm and an inner diameter length of 3.0 mm is molded with an outer diameter variation of ± 2%. The porous tape body 21 that has passed through the first molding die 31a is then inserted into the second molding die 31b, where the inner diameter is 1.12 mm and the inner length is 3.00 mm, with a predetermined outer diameter and its tolerance. Molded. By the above forming process, the outer diameter of the porous tape body 21 becomes a perfect circular cylinder, and the close contact with the conductor 1 is improved, and unevenness in thickness, unevenness in outer diameter, variation in outer diameter, and the like are reduced. The When the porous tape body 21 formed by the forming dies 31a and 31b is more smoothly formed, the forming dies 31a and 31b can be rotated while rotating at a predetermined rotational speed. Furthermore, when performing tape winding and baking of a tape body simultaneously, you may heat the shaping | molding dies 31a and 31b to baking temperature.
[0070]
Next, referring to FIG. 4, the braid of the braided body (outer conductor) 3 and the braided body of Outer diameter accuracy Of outer diameter ± 2 The outline of the method for forming the film will be described.
[0071]
A tape body is wound around the outer circumference of the conductor 1, and the tape wound insulation core 10 formed with a predetermined outer diameter and a predetermined outer diameter accuracy is supplied to the braiding device 40. The first and second of the braiding device 40 The guide dies 41 and 42 and the forming die 43 are inserted.
[0072]
In addition to guiding the insulated wire core 10, the first guide die 41 shapes the insulated wire core 10 before braiding with a predetermined outer diameter and a predetermined outer diameter accuracy. The insulated wire core 10 that has passed through the first guide die 41 has a plurality of braiding strands 44, and the braiding strands 44 are knitted by the rotation of the braiding device 40 that alternately rotates in the opposite direction. It is braided just before the guide die 42. The second guide die 42 guides the braided body 3 and also forms the outer periphery of the braided body 3.
[0073]
The braided body 3 that has passed through the second guide die (braided die) 42 is inserted into a molding die 43 having an inner diameter of 1.50 mm and an inner diameter of 3.00 mm, and the braided body 3 is molded by the molding die 43. . By this forming, the braided body 3 is pulled in the length direction and is squeezed so that the gap of the braided body 3 itself disappears so that the braided body 3 is more closely attached to the insulator 2 and the braided body 3 and the insulator 2 There is no gap between them, the inner diameter of the braided body 3 is closer to the outer diameter of the insulator 2, and the thickness of the braided body 3 is not uniform, the outer diameter is uneven, the outer diameter varies, etc. It approaches the body shape and stabilizes the characteristic impedance value and reduces its fluctuation.
[0074]
Next, another embodiment will be described with reference to FIGS.
[0075]
First, as shown in FIG. 5 (a), a coaxial cable 50 according to another embodiment includes an inner conductor 1, an insulator 2 formed by winding a porous tape body around the conductor 1, The outer conductor 3 is a braided body provided on the outer periphery of the insulator 2 and the outer cover 4 is provided on the outer periphery of the outer conductor 3. Furthermore, an outer diameter holding layer 56 is formed on the outer periphery of the insulator 2 in the coaxial cable 55 shown in FIG.
[0076]
The insulator 2 has a porosity of 60% or more, an accuracy of ± 5%, a thickness of ± 3 μm, When the compressive stress is 0.24 to 0.28 kg weight, compression Deformation distortion Is applied to a fired porous PTFE tape body having 0.6 to 0.8%, or a polyethylene porous tape body having a weight average molecular weight of 5 million or more and the like, as shown in FIG. A tape body 21a having a thickness of 5 mm ± 3 μm and a thickness of 0.180 mm is configured to have a winding angle of 80 degrees around the inner conductor 1 and to form a double winding without overlapping the tape body 21a. Alternatively, as shown in FIG. 7, when the insulator 2 is formed by holding the two tape bodies 21b on the outer periphery of the inner conductor 1 and winding the tape bodies 21b with a gap between the tape bodies 21b without overlapping. Since there is no overlap of the tape body 21a, there are no gaps on the conductor 1 side and irregularities on the outside of the insulator 2, and the insulator 2 is subject to fluctuations in the outer diameter within ± 1. Of the center value of the outer diameter of the insulator 2. 5% can be formed.
[0077]
In addition, an outer diameter holding layer 56 is provided on the outer periphery of the insulator 2 having a variation in outer diameter of ± 1%. The outer diameter holding layer 56 is wound with a plastic tape body and without overlapping at a winding angle of 80 degrees. May be. The outer diameter holding layer 56 is for preventing the molded outer diameter from returning to its original shape with the passage of time after the outer diameter of the insulator 2 is molded to ± 1%. A polyethylene terephthalate tape having a width of 025 mm and a width of 7.5 mm can be applied.
[0078]
An outer conductor 3 is formed on the outer periphery of the insulator 2 having a variation in outer diameter of ± 2%. The outer conductor 3 is composed of a braided body, and the applicable specifications of the braided body are the same as described above. The difference is the way of braiding. As shown in FIG. 8 (b), the method of knitting is that the conventional method of knitting is to increase 2 strokes out of each number of strikes (in this case, 2 over) ), The next is braided under the other two strokes (in this case, 2 under).
[0079]
In this embodiment, this knitting method may be applied. However, if the knitting method of each number of strokes shown in FIG. 2 is increased, and the holding force of the insulator 2 is increased. Furthermore, the braided body itself becomes easy to be cylindrical by tightening each shot.
[0080]
Next, the insulator 2 has a tape width of 3 times the outer diameter of the insulator 2, the accuracy of the tape body width is ± 1%, the winding angle is 80 degrees, and the outer periphery of the inner conductor 1 is eliminated. A configuration method of the insulator 2 when wound (corresponding to claim 4) will be described with reference to FIG.
[0081]
The twisted conductor (inner conductor) 1 is supplied from a supply unit (not shown) to the first, second, third, and fourth guide dies 93a, 93b, 93c, and 93d of the tape winding device and the forming die 94. And insert. The supplied conductor 1 is rotated in the direction of arrow Y1 by a rotational drive of a rotary drive unit (not shown) at a predetermined rotational speed, and is taken up in the direction of arrow Y2 by a take-up unit (not shown) at a predetermined speed.
[0082]
The conductor 1 that has passed through the first guide die 93a is in front of the second guide die 93b, and the porous tape body 21c supplied from the tape body supply section 91 at a predetermined angle is rotated with the rotation of the arrow Y1 of the conductor 1. By the progress of the arrow Y2, it is wound around the outer periphery without overlapping.
[0083]
The conductor 1 around which the tape 21c is wound passes through the second guide die 93b, and the tape body 21d supplied in the direction opposite to the tape 21c from the tape body supply unit 92 is before the third guide 93c. It is wound around the outer periphery. By this tape winding, the tape body 21 is doubly wound around the conductor 1 without overlapping. The tape body wound around the tape body 21d and passed through the third guide die 93c is inserted into a forming die 94 disposed between the third and fourth guide dies 93c and 93d, and has an inner diameter of 1 · 12 mm. By passing the die having a die length of 3.00 mm, the variation of the outer diameter of the insulator 2 is formed with ± 2%.
[0084]
By winding and forming the tape body 21 as described above, the outer diameter of the insulator 2 becomes a perfect circle, and the close contact with the conductor 1 is improved, resulting in uneven thickness, uneven outer diameter, and variation in outer diameter. Etc. are reduced. After the tape roll 21 is formed with the forming die 94, in order to maintain the forming accuracy, the outer shape holding layer is wound by winding the tape body 21 with high mechanical strength even if the thickness is small in the fourth guide die 93d. May be provided.
[0085]
Next, when the insulator 2 has at least two porous tape bodies 21 and is wound around the outer circumference of the inner conductor 1 at intervals of the tape width without overlapping each other in the same direction. A method of configuring the insulator 2 (corresponding to claim 5) will be described with reference to FIG.
[0086]
Before the second guide die 93b, the porous tape body 21c supplied from the first tape supply section 91 is wound around the outer periphery of the conductor 1 at intervals of the tape body width. Next, before the guide die 93c, the tape body 21d supplied from the second tape supply unit 92 is wound around the previously wound tape body where it is not wound. Thus, by winding the two tape bodies 21c and 21d without overlapping, it is possible to reduce unevenness, variation in outer shape, and the like caused by tape winding on the outer periphery of the conductor 1. Variations in the dielectric relative dielectric constant can also be reduced. The tape wound body 21 that has passed through the guide die 93c and is wound without being overlapped is inserted into the forming die 94, and the variation in the outer shape of the tape wound body 21 is formed at ± 1%. Another external tape body may be wound around the outer periphery of the tape roll 21 to form the outer shape holding layer.
[0087]
Next, the structure and characteristics of each coaxial cable are shown in the following Table 1 and Table 2.
[0088]
[Table 1]

[Table 2]

In these Tables 1 and 2, the inner conductor was a 7-strand of 0.16 mm silver-plated annealed copper wire, and the PTFE tape body having a porosity of 70% was applied as the porous porous body. The external conductor applied with a silver-plated annealed copper wire was indicated by Ag, the conductor applied with the annealed copper wire itself was indicated with Cu, and the conductor applied with a tin alloy-plated annealed copper wire was indicated with Ag-Sn. In the present invention, Ag-Sn, which is formed by inserting both of the insulator and the braid through a forming die, is indicated by SML1, and the insulator and the braid which are not formed is indicated by SML2.
[0089]
The contents of the tests conducted to compare the characteristics of the above coaxial cables are described in the following (1) to (3).
[0090]
(1) Bending test: The characteristic impedance value (A) of the cable cut to 500 mm was measured, and the central part of the cable was wound about 10 times with a tension of 200 g around a mandrel with an outer diameter of 5.0 mm, and the characteristic impedance in that state The value (B) is measured, and the change of the characteristic impedance value is obtained from (A)-(B). The results are shown in Table 1. As a result, since the outer diameter of both the insulator and the braided body is molded using a tin alloy with a small dynamic friction coefficient for the braided body wire, the fluctuation of the characteristic impedance value is small, and the flexibility of the cable is improved. The change of characteristic impedance value became small.
[0091]
(2) Flexibility test: Two test pieces with a 72 mm mark attached to the center of a cable with a length of 150 mm and left at a temperature of 23 ± 2 ° C. and a relative humidity of 65% or less for 2 hours are attached to both ends. The value of force when compressed to 40 mm is obtained. The results are shown in Table 1. As a result, since the braided body wire was made of a tin alloy-plated annealed copper wire to form a braided body, each strand of the braided body was easy to move and the flexibility was improved.
[0092]
(3) Measured value of characteristic impedance: Table 2 shows the measured values of the previous SML1 and 2, applying the TDR measurement method. As a result, the characteristic impedance of SML1 is stable with little variation, and SML2 has a large variation in characteristic impedance, and cannot satisfy ± 1Ω.
[0093]
【The invention's effect】
As described above, according to the present invention, the high-precision foamed coaxial cable formed from the inside to the outside in the order of the inner conductor, the foamed insulator, the outer conductor, and the outer jacket, 4/1000 mm or less, the accuracy of the outer diameter of the foamed insulator is ± 0.02 mm, the shape is formed in a perfect circle, and the accuracy of the outer diameter of the outer conductor is ±± of the center value of the outer diameter. 2%, and the shape is formed in a perfect circle, and the accuracy of the characteristic impedance value between the inner conductor and the outer conductor with the foam insulation interposed is set to ± 1Ω. Improves the accuracy of the outer diameter by reducing the unevenness of the outer shape and the outer diameter of conductors, insulators, outer conductors, etc., each member can be made into a perfect circle, and fluctuations in the characteristic impedance value are reduced be able to. Therefore, the cable can be made flexible and the characteristic impedance value can be set to ± 1Ω. Further, the characteristic impedance value could maintain its accuracy even when various mechanical stresses were applied to the cable.
[0094]
The inner conductor is formed by twisting a silver-plated annealed copper wire with a silver plating thickness of 1 to 3 μm with an outer diameter accuracy of 2/1000 mm or less, and the twist pitch is determined by the layer core diameter. Therefore, it is possible to reduce the unevenness of the inner conductor and the fluctuation of the outer diameter in order to reduce the fluctuation of the characteristic impedance value. Therefore, the inner conductor has flexibility and mechanical strength, and the characteristic impedance value can be made ± 1Ω.
[0095]
The foamed insulator is formed by winding a porous tape body around the inner conductor at an angle of 80 degrees and 1/2 lap winding, and the variation in thickness of the foamed insulator after this winding is ± 0. 01mm and the outer diameter variation is ± 0.02mm, eliminating the gap caused by winding the tape between the inner conductor and the insulator, increasing the adhesion between the inner conductor and the insulator, The variation in the outer diameter can be reduced by making it close to a perfect circle. Therefore, even when mechanical stress is applied to the cable, the shape of the insulator does not change, the adhesion with the internal conductor can be maintained, and the change in the characteristic impedance value can be reduced.
[0096]
The foamed insulator is formed by winding the porous tape body around the inner conductor at a winding angle of 80 degrees so that the porous tape body itself does not overlap, and the width of the wound porous tape body. Is 3 times the outer diameter of the foamed insulator and its width accuracy is ± 1%. Furthermore, the foamed insulator has at least two or more porous tape bodies, and each of them is wound so as not to overlap the outer circumference of the inner conductor at the tape width interval in the same direction. There is no overlap of the tape body of the insulator formed by winding, and there is no gap between the conductor and insulator and the gap and unevenness of the outer periphery of the insulator caused by the overlap of the tape body winding, and the variation in outer diameter is reduced. The dielectric constant of the insulator becomes constant. Therefore, the tape breakage in the tape winding process is eliminated and the productivity is improved.
[0097]
In addition, since the foamed insulator has an outer diameter holding layer configured by winding a polyethylene terephthalate plastic tape body on the outer periphery thereof, the unevenness and fluctuation of the outer diameter of the insulator are suppressed, and the outer diameter of the insulator is made uniform. The mechanical strength of the insulator can be enhanced. Therefore, the mechanical strength of the insulator could be improved and the characteristic impedance value could be ± 1Ω.
[0098]
In addition, the porous tape body has a compressive deformation strain when the porosity is 60% or more, the pore accuracy is ± 5%, the thickness tolerance is ± 3 μm, and the compressive stress is 0.24 to 0.28 kg weight. Is a sintered PTFE tape body of 0.6 to 0.8%. Furthermore, since the porous tape body is a polyethylene tape body having a weight average molecular weight of 5 million or more with a porosity of 60% or more, a porosity accuracy of ± 5%, and a thickness tolerance of ± 3 μm, it is foamed. The variation of the dielectric constant, thickness, and mechanical strength of the porous tape body that constitutes the insulator is reduced to reduce the variation of the dielectric constant and outer diameter of the insulator, and the winding tension of the tape body. Can be made constant. Therefore, the characteristic impedance value could be ± 1Ω.
[0099]
The outer conductor is a braid of two-layer plated anodized copper wire that has an outer diameter tolerance of ± 2/1000 mm by subjecting a silver-plated annealed copper wire with a thickness of 1 to 3 μm to a tin alloy plating with a thickness of 0.2 to 0.5 μm. Consists of the body. Further, the outer conductor is a braid of a two-layer plated anodized copper wire having an outer diameter tolerance of ± 2/1000 mm by subjecting a nickel-plated annealed copper wire with a thickness of 1 to 3 μm to a tin alloy plating with a thickness of 0.2 to 0.5 μm. Since it consists of a body, the strands of each striking wire constituting the braided body can be individually moved when the cable is subjected to mechanical stress. In addition, since the sliding property of the braided body has been improved, the flexibility has been improved, and since the sliding property and the flexibility have been improved, the braided body can be molded, and the fluctuation in the outer diameter of the braided body can be reduced to reduce the fluctuation to the insulator. Adhesion is improved. Accordingly, the flexibility of the cable can be improved, and the change in the characteristic impedance value can be reduced even when mechanical stress is applied.
[0100]
In addition, the tin alloy plating is composed of tin and copper, and the copper content ratio is 0.6 to 2.5%, so that copper diffusion is prevented, whisker generation and growth are suppressed, The knitted fabric is maintained in electrical conductivity, and the slidability of the braided body wire is improved. Therefore, it was possible to give the cable flexibility and to maintain the accuracy of the characteristic impedance value.
[0101]
Further, since the braided body constituting the outer conductor is braided with 1 over 1 under the number of braids forming the braided body, each striking constituting the braided body is braided with 1 over / 1 under. Since the shape maintaining force of itself is increased, the holding force for holding the insulator is increased, and the adhesion with the insulator is improved. Therefore, since the shape maintaining force and the insulator holding force are increased while the braided body is flexible, the influence of mechanical stress applied to the cable is small, and the change in the characteristic impedance value can be reduced.
[0102]
Further, the thickness of the jacket is 0.5 times or more the thickness of the outer conductor, the accuracy of the thickness is 3/100 mm or less, and the adhesion with the outer conductor is 20 g / mm at 23 ° C. ² As described above, since the FEP resin is formed by extrusion molding, it is possible to maintain the cylindrical outer shape of the outer conductor, suppress the release thereof, and improve the accuracy of the characteristic impedance value. Therefore, it was possible to keep the cable flexible and to maintain the accuracy of the characteristic impedance value.
[0103]
As described above, the high-precision foamed coaxial cable of the present invention has flexibility, and is not affected by mechanical stress such as bending, twisting, and sliding applied to the cable, and has transmission characteristics. Even when subjected to mechanical stress, the fluctuation of transmission characteristics can be reduced and the accuracy of characteristic impedance values can be reduced.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a configuration of a high-precision foamed coaxial cable according to an embodiment of the present invention.
FIG. 2 is a diagram showing a configuration in which a porous tape body in the high-precision foamed coaxial cable according to the embodiment is wound around an inner conductor outer periphery.
FIG. 3 is a view for explaining a method of winding a porous tape body in the high-precision foamed coaxial cable according to the embodiment.
FIG. 4 is a diagram for explaining a method of manufacturing an outer conductor in the high-precision foamed coaxial cable according to the embodiment.
FIG. 5 is a cross-sectional view showing a configuration of a high-precision foamed coaxial cable according to another embodiment.
6 is a cross-sectional view of a wire core in which two porous tape bodies are wound without overlapping, in a high-precision foamed coaxial cable according to another embodiment. FIG.
FIG. 7 is a view showing a state in which two porous tape bodies are wound at a predetermined interval from each other in a high-precision foamed coaxial cable according to another embodiment.
FIG. 8 is a diagram showing a structure of a braided body in a high-precision foamed coaxial cable according to another embodiment.
FIG. 9 is a view showing a state in which two porous tape bodies are wound without overlapping, in a high-precision foamed coaxial cable according to another embodiment.
FIG. 10 is a diagram showing a state in which two porous tape bodies are wound at a predetermined interval from each other in a high-precision foamed coaxial cable according to another embodiment.
[Explanation of symbols]
1 Inner conductor
2 Insulator (foamed insulator)
3 Outer conductor
4 jacket
10 Insulated wire core
21, 21a, 21b, 21c, 21d porous tape body
15, 91, 92 Tape body supply section
30a, 30b, 30c, 41, 42, 93a, 93b, 93c, 93d Guide dice
31a, 31b, 43, 94 Molding dies
40 Braiding device
44 Wire for braiding
50, 55 High-precision foamed coaxial cable according to another embodiment
56 Outer diameter retention layer
a, b Gaps outside the insulator 2
Y1 direction of rotation
Y2 moving direction

Claims (14)

An inner conductor formed by twisting a plurality of conductive wires;
  A low dielectric constant foam insulator with a porous tape formed on the outer periphery of the inner conductor;
  An outer conductor composed of a plurality of conductive thin wires braided with a two-layer plated annealed copper wire in which a copper alloy wire plated with silver or nickel is plated on the outer periphery of the foamed insulator;
  A high-precision foamed coaxial cable comprising a heat-resistant outer sheath formed on the outer periphery of the outer conductor. The accuracy of the outer diameter of the inner conductor is 4/1000 mm or less,
  The accuracy of the outer diameter of the foamed insulator is ± 0.02 mm, and the shape is formed into a perfect circle,
  The accuracy of the outer diameter of the outer conductor is set to ± 2% of the center value of the outer diameter, and the shape is formed into a perfect circle,
  2. The high-precision foamed coaxial cable according to claim 1, wherein the accuracy of a characteristic impedance value between the inner conductor and the outer conductor through which the foamed insulator is interposed is ± 1Ω.   The inner conductor is formed by twisting a silver-plated annealed copper wire with a silver plating thickness of 1 to 3 μm with an accuracy of an outer diameter of 2/1000 mm or less, and the twist pitch is 20 times the layer core diameter. The high-precision foamed coaxial cable according to claim 1, wherein:   The foamed insulator is formed by winding the porous tape body around the outer circumference of the inner conductor with an angle of 80 degrees and 1/2 lap winding, and the variation in thickness of the foamed insulator after this winding is ± 0. The high-precision foamed coaxial cable according to claim 1, wherein the variation in outer diameter is 0.01 mm and the variation in outer diameter is ± 0.02 mm.   The foamed insulator is formed by winding the porous tape body around the inner conductor at a winding angle of 80 degrees so that the porous tape body itself does not overlap. The high-precision foamed coaxial cable according to claim 1, wherein the width is three times the outer diameter of the foamed insulator and the accuracy of the width is ± 1%.   The foamed insulator has at least two or more of the porous tape bodies, and each of the foamed insulators is wound so as not to overlap the outer circumference of the inner conductor in the same direction at a tape width interval. 1. A high-precision foamed coaxial cable according to 1.   The high-precision foamed coaxial cable according to any one of claims 3 to 5, wherein the foamed insulator has an outer diameter holding layer formed by winding a polyethylene terephthalate plastic tape body on an outer periphery thereof.   The porous tape body has a compressive deformation strain when the porosity is 60% or more, the pore accuracy is ± 5%, the thickness tolerance is ± 3 μm, and the compressive stress is 0.24 to 0.28 kg weight. The high-precision foamed coaxial cable according to any one of claims 3 to 6, which is a fired PTFE tape body of 0.6 to 0.8%.   The porous tape body is a polyethylene tape body having a weight average molecular weight of 5 million or more, having a porosity of 60% or more, a porosity accuracy of ± 5%, and a thickness tolerance of ± 3 μm. The high precision foamed coaxial cable in any one of 3-6.   The outer conductor is a braided body of two-layer plated anodized copper wire having an outer diameter tolerance of ± 2/1000 mm by applying a 0.2 to 0.5 μm thick tin alloy plating to a silver plated anodized copper wire having a thickness of 1 to 3 μm The high-precision foamed coaxial cable according to claim 1, wherein   The outer conductor is a braided body of a two-layer plated annealed copper wire having an outer diameter tolerance of ± 2/1000 mm by subjecting a nickel plated annealed copper wire with a thickness of 1 to 3 μm to a tin alloy plating with a thickness of 0.2 to 0.5 μm. The high-precision foamed coaxial cable according to claim 1, wherein   11. The high-precision foamed coaxial cable according to claim 9, wherein the tin alloy plating is made of tin and copper, and the content ratio of copper is 0.6 to 2.5%.   The high-precision foamed coaxial cable according to any one of claims 1, 9, and 10, wherein the braided body constituting the outer conductor is braided so that the number of braids constituting the braided body is 1 over 1 under. . The thickness of the jacket is 0.5 times or more the thickness of the outer conductor, the accuracy of the thickness is 3/100 mm or less, and the adhesion with the outer conductor is 20 g / 23 at 23 ° C. and mm ² or more, a high-precision foamed coaxial cable according to claim 1, characterized by comprising the extrusion of FEP resin.

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