JP3625369B2 - Semi-rigid coaxial cable and manufacturing method thereof - Google Patents
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Description
【０００１】
【産業上の利用分野】
本発明は、携帯用電話機等の小型電子機器の高周波伝送線路に用いられるセミリジッド型同軸ケーブルおよびその製造方法に関するものである。
【０００２】
【従来の技術】
携帯用電話機等の小型電子機器の高周波伝送線路として使用されるセミリジッド型同軸ケーブルは、細径で可撓性に富み高周波電気特性に優れるとともにはんだ接続作業から耐熱性能に優れることが要求される。
かかる要求に応えるセミリジッド型同軸ケーブルとして、本願出願人は特開平６−１８７８４７号公報において、中心導体の外周に４ふっ化エチレン樹脂（ＰＴＦＥ）或いは４ふっ化エチレン−６ふっ化プロピレン共重合体樹脂（ＦＥＰ）等の低誘電率絶縁層を被覆し、この低誘電率絶縁層外周に無電解めっきによるアンカー金属層と電気めっきによる良導電性金属層とを施し外部導体層としたセミリジッド型同軸ケーブルを提案し、実用に供している。
上記のセミリジッド型同軸ケーブルは、従来の外部導体層に銅パイプを用いたセミリジッド型同軸ケーブルに比べ、低誘電率絶縁層と外部導体層間の密着性に優れていて可撓性に富み、細径化が可能であるという利点があった。
【０００３】
【発明が解決しようとする課題】
セミリジッド型同軸ケーブルの細径化に伴い、セミリジッド型同軸ケーブルも他の電子部品と同様に回路基板とはんだ接続する際にリフロー炉を用いた自動はんだ接続方式が適用されるようになり、セミリジッド型同軸ケーブルの耐熱性能の更なる改良が求められている。かかる要求に対応するため、絶縁層には充実型ふっ素系樹脂絶縁層に代わって耐熱性能の良い多孔質ふっ素系樹脂絶縁層が多用されるようになった。
【０００４】
上叙の金属めっきにより外部導体層を形成するセミリジッド型同軸ケーブルの場合、絶縁層が充実絶縁体で形成されているものについては金属めっきを施すときに格別の不都合を生じることはなかった。しかし、絶縁層が多孔質絶縁体で形成されるようになると、めっき前処理工程において多孔質絶縁層表面の活性化処理を行ったときに活性化液が絶縁層表面から細かな気孔を通って多孔質絶縁層内部に浸透し、多孔質絶縁層内部までが活性化処理され、金属めっきを施したときに金属めっき層が多孔質絶縁層内に楔のように食い込んで形成され、多孔質絶縁層と金属めっき外部導体層との密着度を強めるという不具合を生じていた。このため、同軸ケーブルの端末加工の際、金属めっき外部導体層と多孔質絶縁層の剥離が困難になるという問題があった。また、健全な金属めっき外部導体層を形成し難いという問題があった。
【０００５】
更に加えて、多孔質絶縁層全般の問題として、多孔質絶縁体は充実絶縁体に比較し剛性の低下が避けられない。このため、セミリジッド型同軸ケーブルの端末加工の際に多孔質絶縁層を中心導体から輪切り剥離しようとすると、多孔質絶縁層が剥離工具によって潰されしかも引き伸ばされてしまって、多孔質絶縁層の輪切り剥離加工を確実に行うことが難しいという問題があった。
【０００６】
そこで、本発明の目的は、多孔質絶縁層の表面に健全な金属めっき外部導体層を形成することができ、かつ多孔質絶縁層表面の剛性を高めることのできる、端末加工性に優れるセミリジッド型同軸ケーブルとその製造方法を提供することにある。
【０００７】
【課題を解決するための手段】
本発明のセミリジッド型同軸ケーブルは、中心導体の外周に表面を焼結した多孔質４ふっ化エチレン樹脂絶縁層を設け、この表面焼結された多孔質４ふっ化エチレン樹脂絶縁層上に無電解めっきアンカー金属層と電気めっき金属層を順次施した外部導体層を設けたことを構成上の特徴とするものである。
【０００８】
本発明のセミリジッド型同軸ケーブルの製造方法は、中心導体の外周に未焼結の多孔質４ふっ化エチレン樹脂絶縁層を施す被覆工程と該未焼結多孔質４ふっ化エチレン樹脂絶縁層の表面を焼結する焼成工程からなる絶縁体コア形成工程と、前記表面焼結した絶縁体コアの表面を短時間で活性化処理する迅速エッチング処理工程と、前記迅速エッチング処理された絶縁体コアの外周に無電解めっき法によりアンカー金属層を形成する無電解めっき工程と該アンカー金属層の外周に電気めっき法により金属層を形成する電気めっき工程からなる外部導体層形成工程とを有することを構成上の特徴とするものである。
【０００９】
【作用】
本発明のセミリジッド型同軸ケーブルでは、多孔質ＰＴＦＥ樹脂絶縁層の表面は焼結され気孔のない充実状外皮で形作られているので、この充実状外皮により表面活性化処理時にも活性化液が多孔質絶縁層の気孔を通って多孔質絶縁層内に浸透することがなくなり、多孔質絶縁層表面のみをエッチング処理することができる。従って、金属めっき層を施したときにも金属めっき層が多孔質絶縁層内部に楔状に入り込んで形成されることがなく、多孔質絶縁層表面にのみ健全な金属めっき外部導体層が形成される。この結果、多孔質ＰＴＦＥ樹脂絶縁層と金属めっき外部導体層との密着強度が強く成り過ぎることがなくなり、端末加工の際に多孔質絶縁層から金属めっき外部導体層を剥離する作業が容易となる。また、絶縁層内は多孔質層で形成されるので、高周波電気特性に大きな低下をもたらすこともない。
また、多孔質絶縁層表面は焼結されて充実状外皮を形成しているので、多孔質絶縁層表面の剛性は高まり、端末加工の際に多孔質絶縁層が剥離工具で潰されたり引き伸ばされることがなくなり、多孔質絶縁層を中心導体から確実、容易に輪切り剥離することが可能となる。
【００１０】
また、上記セミリジッド型同軸ケーブルにおいて、多孔質ＰＴＦＥ樹脂絶縁層表面を焼結するとともに多孔質絶縁層内の気孔率を内層から表面に向かって順次減少して形成すれば、表面活性化液の多孔質絶縁層内部への浸透はより一層阻止され、多孔質絶縁層と金属めっき外部導体層との密着強度の増大を防止する効果が更に高まる。また、中心導体と接触する多孔質絶縁層の内側は多気孔率層で形成されているので、多孔質ＰＴＦＥ樹脂絶縁層と中心導体との密着強度も増大することがなく好ましい。
【００１１】
本発明のセミリジッド型同軸ケーブルの製造方法では、焼成工程において未焼結の多孔質ＰＴＦＥ絶縁層表面のみを短時間で加熱焼結して表面に薄い充実状外皮を有する絶縁体コア形成し、この絶縁体コア表面の薄い充実状外皮を活性化処理し金属めっき層を施すものである。従って、絶縁体コア表面の薄い充実状外皮を過度の活性化処理から保護しつつ適正な表面活性化を施して健全な金属めっき層を形成する必要がある。そこで、本発明のエッチング処理工程では、活性化処理を通常の処理時間の約１／１０以下の極く短時間の処理時間で行う迅速エッチング処理方法を採用し、表面活性化液による絶縁体コア表面の薄い充実状外皮の浸食を防止し、健全な金属めっき層を形成するに必要な限度の活性化処理を実現した。これにより、絶縁体コア表面の焼結層が過度に浸食されることにより生ずる表面活性化液の多孔質絶縁層内への浸透の恐れがなくなった。この結果、後工程の金属めっき工程において、金属めっきが多孔質絶縁層内に楔状に形成される不都合が解消され、多孔質絶縁層と金属めっき外部導体層との密着度が強くなり過ぎるという不具合の発生が防止された。なお、活性化処理時間は多孔質絶縁層表面の焼結程度を勘案し実験的に決定された。
また、未焼結の多孔質ＰＴＦＥ樹脂絶縁層の焼成工程では、未焼結の多孔質絶縁層表面のみを短時間加熱する方法を採用しているので、多孔質絶縁層表面に焼結された剛性の高い薄い充実状外皮が形成され、端末加工の際に多孔質絶縁層が剥離工具で潰されたり引き伸ばされたりする不具合の発生が解消され、多孔質絶縁層を中心導体から確実、容易に輪切り剥離することが可能となる。
【００１２】
上記セミリジッド型同軸ケーブルの製造方法において、未焼結多孔質ＰＴＦＥ樹脂絶縁層の焼成工程の際に、短時間加熱焼結手段の加熱温度、加熱時間の設定を変えることにより、未焼結多孔質ＰＴＦＥ樹脂絶縁層表面の焼結とともに該絶縁層の内層から表面に向かって気孔率を順次減少させて形成させることが可能である。このように多孔質絶縁層の内層から表面に向かって気孔率を順次減少させて形成すれば、活性化液の多孔質絶縁層内部への浸透阻止効果が高まり、迅速エッチング処理工程における適正な活性化処理時間帶の拡大が可能となり迅速エッチング処理効果を一層高めることができる。
【００１３】
また、上記セミリジッド型同軸ケーブルの製造方法において、絶縁体コア表面の迅速エッチング処理時間は０．１０秒以上０．２５秒以内に設定することが望ましい。エッチング処理時間が０．１０秒より短いと、エッチング処理の効果が薄く、金属めっき層の形成が困難となるためである。また、エッチング処理時間が０．２５秒より長いと、絶縁体コア表面に折角形成した焼結層がエッチング処理により侵食され、多孔質絶縁層表面に焼結層を形成した効果が失われてしまうためである。
【００１４】
また、上記セミリジッド型同軸ケーブルの製造方法において、絶縁体コア表面の迅速エッチング処理工程と外部金属導体層形成工程を分割してそれぞれ独立した工程で行うことが望ましい。これは、迅速エッチング処理工程におけるエッチング処理時間と外部金属導体層形成工程におけるめっき処理時間とでは処理時間が大きく異なり、生産効率或いは装置効率を考慮すれば分割工程とすることが効果的であることによる。
【００１５】
【実施例】
以下、図に示す実施例に基づき本発明を更に詳細に説明する。なお、これにより本発明が限定されるものではない。
【００１６】
図１は、本発明のセミリジッド型同軸ケーブルの１実施例を示す横断面図である。セミリジッド型同軸ケーブル１は、中心導体２の外周に表面焼結層３ａと多孔質層３ｂからなる多孔質ＰＴＦＥ樹脂絶縁層３を設けて絶縁体コア４が形成され、この絶縁体コア４の外周に無電解めっきアンカー金属層５ａと電気めっき金属層５ｂが順次施された外部金属導体層５が形成されている。
多孔質ＰＴＦＥ樹脂絶縁層３は、未焼結の多孔質ＰＴＦＥ樹脂をペースト押出成形するか、または未焼結の多孔質ＰＴＦＥ樹脂テープを重ね巻きした後、この表面を焼結して形成される。なお、図１では多孔質ＰＴＦＥ樹脂絶縁層３は、内層から表面に向かって気孔率が順次減少して形成された例を示している。
【００１７】
図２は、本発明のセミリジッド型同軸ケーブルの製造方法の１実施例を示す工程フロー図で、この工程フロー図に沿いセミリジッド型同軸ケーブル１の製造方法を詳述する。
絶縁体コア形成工程は被覆工程と焼成工程とでなる。被覆工程では、中心導体２の外周にペースト押出成形により、例えば気孔率５０％の未焼結の多孔質ＰＴＦＥ樹脂層が被覆される。焼成工程では、この未焼結の多孔質ＰＴＦＥ樹脂被覆コアを雰囲気温度３２０〜３３０°Ｃのサンドバス槽に約３秒間通して未焼結コアの表面を焼結し、表面焼結層３ａと多孔質層３ｂを有する平均気孔率２５％の多孔質ＰＴＦＥ樹脂絶縁層３の被覆された絶縁体コア４が形成される。
【００１８】
次の迅速エッチング処理工程では、絶縁体コア４は液温１０°Ｃの金属ナトリウム−ナフタレン錯体溶液槽中に導入され０．１０秒〜０．２５秒間浸せき処理されて通過し、絶縁体コア４の表面が活性化される。この後、アルコール洗浄と水洗により絶縁体コア４表面に付着する金属ナトリウム−ナフタレン錯体溶液が除去され乾燥される。
【００１９】
次に、絶縁体コア４は外部導体層形成工程に導入される。無電解めっき工程では、絶縁体コア４の脱脂洗浄と水洗の後、前処理として、絶縁体コア４は、表面に二塩化第一錫（ＳｎＣｌ2 ）を吸着させるシンセタイジング処理が施され、更にその表面にパラジウム（Ｐｄ）を還元析出させる二塩化パラジウム（ＰｄＣｌ2 ）溶液中でのアクチベイテング処理が施され、この後、８０°Ｃの無電解ニッケル−リン（Ｎｉ−Ｐ）めっき液を用いた無電解めっき処理が施され、絶縁体コア４表面にＮｉ−Ｐのアンカー金属層５ａが析出形成される。続いて、電気めっき工程では、絶縁体コア４は、水洗後、２５°Ｃの硫酸銅めっき液中で電流密度１Ａ／ｄｍ2 、めっき時間２０分の条件で銅めっきが施され、更に２５°Ｃの光沢硫酸銅めっき液中で電流密度５Ａ／ｄｍ2 、めっき時間４０分の条件で光沢銅めっきが施され電気めっき金属層５ｂが形成され、水洗、乾燥して外部導体層５が得られる。かくして、セミリジッド型同軸ケーブル１が製造される。
【００２０】
次に、本発明の要点をなす迅速エッチング処理時間をそれぞれ変えて製作した実施例を記す。なお、各実施例とも上記に説明した図２のフロー工程図に従い製造した図１の構成を有するセミリジッド型同軸ケーブルである。
【００２１】
−比較例１−
外径０．１２ｍｍの銀めっき銅線の中心導体２の外周に、ペースト押出により気孔率５０％の未焼結の多孔質ＰＴＦＥ樹脂を被覆し、これを３２０°Ｃのサンドバス槽で３秒間焼結し、被覆厚さ０．１８ｍｍ、平均気孔率２５％の表面焼結させた多孔質ＰＴＦＥ樹脂絶縁層３を設け、外径０．４８ｍｍの絶縁体コア４を得た。次に、この絶縁体コア４を液温１０°Ｃの金属ナトリウム−ナフタレン錯体溶液中で０．２６秒間活性化処理した。次に、この絶縁体コア４の外周に無電解めっきにより１μｍ厚さのＮｉ−Ｐアンカー金属層５ａを施し、更にアンカー金属層５ａ上に電気めっきにより６０μｍ厚さの銅めっきの金属層５ｂを施し、合計厚さ６１μｍの外部導体層５を設けた。得られたセミリジッド型同軸ケーブル１の外径は０．６０２ｍｍであった。
−実施例１−
絶縁体コア４の金属ナトリウム−ナフタレン錯体溶液中での活性化処理時間を０．２５秒間とした以外は、比較例１と全く同一条件でセミリジッド型同軸ケーブル１を製造した。
−実施例２−
絶縁体コア４の金属ナトリウム−ナフタレン錯体溶液中での活性化処理時間を０．１５秒間とした以外は、比較例１と全く同一条件でセミリジッド型同軸ケーブル１を製造した。
−実施例３−
絶縁体コア４の金属ナトリウム−ナフタレン錯体溶液中での活性化処理時間を０．１０秒間とした以外は、比較例１と全く同一条件でセミリジッド型同軸ケーブル１を製造した。
−比較例２−
絶縁体コア４の金属ナトリウム−ナフタレン錯体溶液中での活性化処理時間を０．０５秒間とした以外は、比較例１と全く同一条件でセミリジッド型同軸ケーブル１を製造した。
【００２２】
上記の活性化処理時間を変えて製作した比較例１，２および実施例１〜３の試料について、絶縁体コア４上への金属めっき性および形成した金属めっき外部導体層５と絶縁体コア４との端末剥離性の評価をした結果を表１に示す。また、比較例１，２および実施例２，３の絶縁体コア４について、エッチング処理した後の多孔質ＰＴＦＥ樹脂絶縁層３の状態を観察した断面拡大写真を図３に示す。
【００２３】
下記表１の評価結果から明らかなように、多孔質ＰＴＦＥ樹脂絶縁層３の表面を焼結し、この多孔質ＰＴＦＥ樹脂絶縁層３を迅速エッチング処理することよって、健全な金属めっき層を施すことが可能となり、また形成された金属めっき外部導体層５と絶縁体コア４との剥離性も極めて良好となることが分かる。
また、図３に見られる如く、エッチング処理時間は多孔質ＰＴＦＥ樹脂絶縁層３の侵食に顕著な影響を及ぼすことが分かり、迅速エッチング処理時間の効果がはっきり確認できる。
【００２４】
【表１】
【００２５】
【発明の効果】
本発明のセミリジッド型同軸ケーブルおよびその製造方法によれば、多孔質ＰＴＦＥ樹脂絶縁層に外部金属導体層を形成するに際し、多孔質ＰＴＦＥ樹脂絶縁層表面を焼結し極く短時間の活性化処理を施すだけという極めて簡便な手段により、該絶縁層表面に健全な外部金属導体層を形成することができる。このように形成された外部金属導体層は多孔質ＰＴＦＥ樹脂絶縁層内に楔状に形成されることがないので、多孔質ＰＴＦＥ樹脂絶縁層との密着性が過度になることなく適正に保持される。従って、端末処理を施す際、外部金属導体層を多孔質ＰＴＦＥ樹脂絶縁層から確実、容易に剥離することができる。また、多孔質ＰＴＦＥ樹脂絶縁層表面だけが焼結されるものであるので、絶縁層の高周波電気特性に大きな低下をもたらすことなく多孔質絶縁層表面の剛性を高めることができる。従って、端末加工処理を施すときに、多孔質ＰＴＦＥ樹脂絶縁層が潰れたり引き伸ばされたりすることがなくなり、多孔質ＰＴＦＥ樹脂絶縁層を中心導体から輪切り剥離することが容易に行える。また、中心導体と接する多孔質ＰＴＦＥ樹脂絶縁層の内層側は多孔質体で形成されるので、中心導体と多孔質ＰＴＦＥ樹脂絶縁層との密着性が過度になることはない。
かかる本発明のセミリジッド型同軸ケーブルおよびその製造方法は、高周波電気特性、耐熱性、端末加工性に優れるセミリジッド型同軸ケーブルを提供するうえで有用である。[0001]
[Industrial application fields]
The present invention relates to a semi-rigid coaxial cable used for a high-frequency transmission line of a small electronic device such as a portable telephone and a method for manufacturing the same.
[0002]
[Prior art]
A semi-rigid coaxial cable used as a high-frequency transmission line for a small electronic device such as a portable telephone is required to have a small diameter, high flexibility, excellent high-frequency electrical characteristics, and excellent heat resistance from solder connection work.
As a semi-rigid coaxial cable that meets such demands, the applicant of the present application disclosed in Japanese Patent Application Laid-Open No. 6-187847 on the outer periphery of a central conductor, a tetrafluoroethylene resin (PTFE) or a tetrafluoroethylene-6 propylene copolymer resin. A semi-rigid coaxial cable that is coated with a low dielectric constant insulating layer such as (FEP) and the outer dielectric layer is coated with an anchor metal layer by electroless plating and a highly conductive metal layer by electroplating on the outer periphery of the low dielectric constant insulating layer. Proposed for practical use.
The semi-rigid coaxial cable described above is superior in adhesion between the low dielectric constant insulating layer and the outer conductor layer, and is more flexible and thinner than conventional semi-rigid coaxial cables that use copper pipes for the outer conductor layer. There was an advantage that it was possible.
[0003]
[Problems to be solved by the invention]
As the semi-rigid coaxial cable is made thinner, the semi-rigid coaxial cable will be applied with an automatic solder connection method using a reflow furnace when soldered to the circuit board in the same way as other electronic components. There is a need for further improvements in the heat resistance of coaxial cables. In order to meet such demands, porous fluorine resin insulation layers with good heat resistance have been frequently used as insulation layers in place of solid fluorine resin insulation layers.
[0004]
In the case of the semi-rigid coaxial cable in which the outer conductor layer is formed by metal plating as described above, no particular inconvenience occurred when the metal plating was performed for the case where the insulating layer was formed of a solid insulator. However, when the insulating layer is formed of a porous insulator, the activation liquid passes through fine pores from the surface of the insulating layer when the surface of the porous insulating layer is activated in the pre-plating process. Penetration into the porous insulating layer, the inside of the porous insulating layer is activated, and when metal plating is applied, the metal plating layer is formed by biting into the porous insulating layer like a wedge, and porous insulation There was a problem that the adhesion between the layer and the metal-plated outer conductor layer was increased. For this reason, there has been a problem that peeling of the metal-plated outer conductor layer and the porous insulating layer becomes difficult during the end processing of the coaxial cable. There is also a problem that it is difficult to form a sound metal-plated outer conductor layer.
[0005]
In addition, as a general problem of the porous insulating layer, a decrease in rigidity is unavoidable as compared with a solid insulator. For this reason, if the porous insulating layer is to be peeled off from the central conductor during the end processing of the semi-rigid coaxial cable, the porous insulating layer is crushed and stretched by the peeling tool, and the porous insulating layer is cut into round pieces. There was a problem that it was difficult to reliably perform the peeling process.
[0006]
Therefore, an object of the present invention is to provide a semi-rigid type that can form a sound metal-plated outer conductor layer on the surface of the porous insulating layer and can enhance the rigidity of the surface of the porous insulating layer, and has excellent terminal processability. It is to provide a coaxial cable and a manufacturing method thereof.
[0007]
[Means for Solving the Problems]
The semi-rigid coaxial cable of the present invention is provided with a porous tetrafluoroethylene resin insulating layer having a sintered surface on the outer periphery of a central conductor, and electrolessly formed on the surface-sintered porous tetrafluoroethylene resin insulating layer. A structural feature is that an outer conductor layer is formed by sequentially applying a plating anchor metal layer and an electroplating metal layer.
[0008]
The method for producing a semi-rigid coaxial cable according to the present invention includes a coating step of applying an unsintered porous tetrafluoroethylene resin insulating layer to the outer periphery of a central conductor, and a surface of the unsintered porous tetrafluoroethylene resin insulating layer. An insulator core forming step comprising a firing step for sintering, a rapid etching treatment step for activating the surface of the surface-sintered insulator core in a short time, and an outer periphery of the insulator core subjected to the rapid etching treatment And an external conductor layer forming step comprising an electroless plating step for forming an anchor metal layer by electroless plating and an electroplating step for forming a metal layer by electroplating on the outer periphery of the anchor metal layer. It is the feature of.
[0009]
[Action]
In the semi-rigid coaxial cable of the present invention, the surface of the porous PTFE resin insulation layer is formed with a solid outer skin that is sintered and has no pores. The porous insulating layer does not penetrate through the pores of the porous insulating layer and only the surface of the porous insulating layer can be etched. Therefore, even when the metal plating layer is applied, the metal plating layer is not formed in a wedge shape inside the porous insulating layer, and a healthy metal plating outer conductor layer is formed only on the surface of the porous insulating layer. . As a result, the adhesion strength between the porous PTFE resin insulating layer and the metal-plated outer conductor layer does not become too strong, and the work of peeling the metal-plated outer conductor layer from the porous insulating layer at the end processing becomes easy. . Further, since the inside of the insulating layer is formed of a porous layer, the high frequency electrical characteristics are not greatly reduced.
Moreover, since the porous insulating layer surface is sintered to form a solid outer skin, the rigidity of the porous insulating layer surface is increased, and the porous insulating layer is crushed or stretched by a peeling tool during terminal processing. As a result, the porous insulating layer can be reliably and easily peeled off from the central conductor.
[0010]
Further, in the semi-rigid coaxial cable, if the surface of the porous PTFE resin insulation layer is sintered and the porosity in the porous insulation layer is sequentially decreased from the inner layer toward the surface, the porosity of the surface activation liquid is increased. Penetration into the porous insulating layer is further prevented, and the effect of preventing an increase in adhesion strength between the porous insulating layer and the metal-plated outer conductor layer is further enhanced. Moreover, since the inside of the porous insulating layer that contacts the central conductor is formed of a multi-porosity layer, the adhesion strength between the porous PTFE resin insulating layer and the central conductor does not increase, which is preferable.
[0011]
In the method for producing the semi-rigid coaxial cable of the present invention, only the surface of the unsintered porous PTFE insulating layer is heated and sintered in a short time in the firing step to form an insulating core having a thin solid outer skin on the surface. A thin solid skin on the surface of the insulator core is activated and a metal plating layer is applied. Therefore, it is necessary to form a healthy metal plating layer by performing appropriate surface activation while protecting the thin solid skin on the insulator core surface from excessive activation treatment. Therefore, the etching process of the present invention employs a rapid etching process method in which the activation process is performed in a very short processing time of about 1/10 or less of the normal processing time, and the insulator core by the surface activation liquid is used. It prevents the erosion of the solid outer skin with a thin surface and realizes the activation treatment to the limit necessary to form a healthy metal plating layer. This eliminates the risk of penetration of the surface activation liquid into the porous insulating layer caused by excessive erosion of the sintered layer on the insulator core surface. As a result, in the subsequent metal plating step, the disadvantage that the metal plating is formed in a wedge shape in the porous insulating layer is eliminated, and the adhesion between the porous insulating layer and the metal plating outer conductor layer becomes too strong. Occurrence was prevented. The activation treatment time was experimentally determined in consideration of the degree of sintering of the porous insulating layer surface.
Further, in the firing process of the unsintered porous PTFE resin insulating layer, a method of heating only the unsintered porous insulating layer surface for a short time is adopted, so that the unsintered porous PTFE resin insulating layer was sintered on the porous insulating layer surface. A thin solid outer shell with high rigidity is formed, and the problem that the porous insulating layer is crushed or stretched by the peeling tool during terminal processing is eliminated, and the porous insulating layer is reliably and easily removed from the central conductor. It becomes possible to peel off the ring.
[0012]
In the method for producing the semi-rigid coaxial cable, the sintering temperature is changed by changing the setting of the heating temperature and the heating time of the short-time heating and sintering means during the firing step of the unsintered porous PTFE resin insulation layer. Along with sintering of the surface of the PTFE resin insulating layer, it is possible to form the insulating layer by sequentially decreasing the porosity from the inner layer toward the surface. In this way, if the porosity is decreased from the inner layer to the surface of the porous insulating layer, the effect of preventing the activation liquid from penetrating into the porous insulating layer is increased, and the appropriate activity in the rapid etching process is increased. It is possible to extend the chemical treatment time 帶 and further enhance the rapid etching effect.
[0013]
In the method for producing the semi-rigid coaxial cable, it is desirable that the rapid etching time for the surface of the insulator core is set to 0.10 seconds or more and 0.25 seconds or less. This is because if the etching processing time is shorter than 0.10 seconds, the effect of the etching processing is thin and it is difficult to form the metal plating layer. Also, if the etching process time is longer than 0.25 seconds, the sintered layer formed on the insulator core surface is eroded by the etching process, and the effect of forming the sintered layer on the porous insulating layer surface is lost. Because.
[0014]
In the method for manufacturing the semi-rigid coaxial cable, it is desirable to divide the rapid etching process step on the surface of the insulator core and the external metal conductor layer forming step into separate steps. This is because the processing time differs greatly between the etching time in the rapid etching process and the plating time in the external metal conductor layer forming process, and it is effective to use the division process in consideration of production efficiency or equipment efficiency. by.
[0015]
【Example】
Hereinafter, the present invention will be described in more detail based on the embodiments shown in the drawings. Note that the present invention is not limited thereby.
[0016]
FIG. 1 is a cross-sectional view showing one embodiment of the semi-rigid coaxial cable of the present invention. In the semi-rigid coaxial cable 1, an insulating core 4 is formed by providing a porous PTFE resin insulating layer 3 including a surface sintered layer 3a and a porous layer 3b on the outer periphery of a central conductor 2, and the outer periphery of the insulating core 4 is formed. The outer metal conductor layer 5 is formed by sequentially applying the electroless plating anchor metal layer 5a and the electroplating metal layer 5b.
The porous PTFE resin insulation layer 3 is formed by paste extrusion molding of unsintered porous PTFE resin or lap winding of unsintered porous PTFE resin tape and then sintering this surface. . FIG. 1 shows an example in which the porous PTFE resin insulation layer 3 is formed with the porosity decreasing sequentially from the inner layer to the surface.
[0017]
FIG. 2 is a process flow diagram showing an embodiment of a method for producing a semi-rigid coaxial cable according to the present invention. The method for producing the semi-rigid coaxial cable 1 will be described in detail along this process flow diagram.
The insulator core forming process consists of a coating process and a firing process. In the covering step, an unsintered porous PTFE resin layer having a porosity of 50%, for example, is coated on the outer periphery of the center conductor 2 by paste extrusion molding. In the firing step, the unsintered porous PTFE resin-coated core is passed through a sand bath tank having an atmospheric temperature of 320 to 330 ° C. for about 3 seconds to sinter the surface of the unsintered core, The insulating core 4 covered with the porous PTFE resin insulating layer 3 having the porous layer 3b and having an average porosity of 25% is formed.
[0018]
In the next rapid etching treatment step, the insulator core 4 is introduced into a metal sodium-naphthalene complex solution bath having a liquid temperature of 10 ° C., soaked through for 0.10 seconds to 0.25 seconds, and passed through the insulator core 4. The surface of is activated. Thereafter, the metal sodium-naphthalene complex solution adhering to the surface of the insulator core 4 is removed by alcohol washing and water washing and dried.
[0019]
Next, the insulator core 4 is introduced into the outer conductor layer forming step. In the electroless plating process, the insulator core 4 is subjected to a synthesizing process for adsorbing stannous dichloride (SnCl 2 ) on the surface as a pretreatment after degreasing and water washing of the insulator core 4. Further, an activation treatment in a palladium dichloride (PdCl 2 ) solution for reducing and precipitating palladium (Pd) on the surface is performed, and then an electroless nickel-phosphorus (Ni-P) plating solution at 80 ° C. The electroless plating process using is performed, and an Ni—P anchor metal layer 5 a is deposited on the surface of the insulator core 4. Subsequently, in the electroplating process, the insulator core 4 is subjected to copper plating in a copper sulfate plating solution at 25 ° C. under conditions of a current density of 1 A / dm 2 and a plating time of 20 minutes, and further 25 ° C. Bright copper plating is performed in a bright copper sulfate plating solution of C under conditions of a current density of 5 A / dm 2 and a plating time of 40 minutes to form an electroplated metal layer 5 b, washed with water and dried to obtain the outer conductor layer 5. . Thus, the semi-rigid coaxial cable 1 is manufactured.
[0020]
Next, examples will be described in which the rapid etching processing time which is the main point of the present invention is changed. Each example is a semi-rigid coaxial cable having the configuration of FIG. 1 manufactured according to the flow process diagram of FIG. 2 described above.
[0021]
-Comparative Example 1-
The outer periphery of the central conductor 2 of a silver-plated copper wire having an outer diameter of 0.12 mm is coated with an unsintered porous PTFE resin having a porosity of 50% by paste extrusion, and this is covered in a sand bath bath at 320 ° C. for 3 seconds. Sintered porous PTFE resin insulating layer 3 having a coating thickness of 0.18 mm and an average porosity of 25% was provided to obtain insulating core 4 having an outer diameter of 0.48 mm. Next, the insulator core 4 was activated in a metal sodium-naphthalene complex solution at a liquid temperature of 10 ° C. for 0.26 seconds. Next, a Ni-P anchor metal layer 5a having a thickness of 1 μm is applied to the outer periphery of the insulator core 4 by electroless plating, and a copper plating metal layer 5b having a thickness of 60 μm is formed on the anchor metal layer 5a by electroplating. The outer conductor layer 5 having a total thickness of 61 μm was provided. The outer diameter of the obtained semi-rigid coaxial cable 1 was 0.602 mm.
Example 1
A semi-rigid coaxial cable 1 was manufactured under exactly the same conditions as in Comparative Example 1 except that the activation time of the insulator core 4 in the metal sodium-naphthalene complex solution was 0.25 seconds.
-Example 2-
A semi-rigid coaxial cable 1 was manufactured under exactly the same conditions as in Comparative Example 1 except that the activation time of the insulator core 4 in the metal sodium-naphthalene complex solution was 0.15 seconds.
Example 3
A semi-rigid coaxial cable 1 was manufactured under exactly the same conditions as in Comparative Example 1 except that the activation time of the insulator core 4 in the metal sodium-naphthalene complex solution was 0.10 seconds.
-Comparative Example 2-
A semi-rigid coaxial cable 1 was manufactured under exactly the same conditions as in Comparative Example 1 except that the activation time of the insulator core 4 in the metal sodium-naphthalene complex solution was 0.05 seconds.
[0022]
About the samples of Comparative Examples 1 and 2 and Examples 1 to 3 manufactured by changing the activation processing time, the metal plating property on the insulator core 4 and the formed metal plating outer conductor layer 5 and the insulator core 4 Table 1 shows the results of terminal peelability evaluation. Moreover, about the insulator core 4 of the comparative examples 1 and 2 and Example 2 , 3, the cross-sectional enlarged photograph which observed the state of the porous PTFE resin insulation layer 3 after an etching process is shown in FIG.
[0023]
As is clear from the evaluation results in Table 1 below, the surface of the porous PTFE resin insulation layer 3 is sintered, and the porous PTFE resin insulation layer 3 is subjected to a rapid etching treatment to thereby apply a healthy metal plating layer. It can be seen that the peelability between the formed metal-plated outer conductor layer 5 and the insulator core 4 is extremely good.
Further, as seen in FIG. 3, it can be seen that the etching time significantly affects the erosion of the porous PTFE resin insulation layer 3, and the effect of the rapid etching time can be clearly confirmed.
[0024]
[Table 1]
[0025]
【The invention's effect】
According to the semi-rigid coaxial cable of the present invention and the method of manufacturing the same, when forming the external metal conductor layer on the porous PTFE resin insulation layer, the surface of the porous PTFE resin insulation layer is sintered and an extremely short activation process is performed. A sound external metal conductor layer can be formed on the surface of the insulating layer by a very simple means of simply applying the above. Since the external metal conductor layer formed in this way is not formed in a wedge shape in the porous PTFE resin insulating layer, the adhesiveness with the porous PTFE resin insulating layer is properly maintained without becoming excessive. . Therefore, when the terminal treatment is performed, the outer metal conductor layer can be reliably and easily peeled from the porous PTFE resin insulating layer. Moreover, since only the surface of the porous PTFE resin insulating layer is sintered, the rigidity of the surface of the porous insulating layer can be increased without causing a significant deterioration in the high-frequency electrical characteristics of the insulating layer. Therefore, when the terminal processing is performed, the porous PTFE resin insulating layer is not crushed or stretched, and the porous PTFE resin insulating layer can be easily peeled off from the center conductor. Further, since the inner layer side of the porous PTFE resin insulating layer in contact with the central conductor is formed of a porous body, the adhesion between the central conductor and the porous PTFE resin insulating layer does not become excessive.
Such a semi-rigid coaxial cable and a method for producing the same according to the present invention are useful in providing a semi-rigid coaxial cable excellent in high-frequency electrical characteristics, heat resistance, and terminal processability.
Claims (6)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP03431198A JP3625369B2 (en) | 1998-01-29 | 1998-01-29 | Semi-rigid coaxial cable and manufacturing method thereof |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP03431198A JP3625369B2 (en) | 1998-01-29 | 1998-01-29 | Semi-rigid coaxial cable and manufacturing method thereof |
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| Publication Number | Publication Date |
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| JPH11213777A JPH11213777A (en) | 1999-08-06 |
| JP3625369B2 true JP3625369B2 (en) | 2005-03-02 |
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| JP4617538B2 (en) * | 2000-06-15 | 2011-01-26 | ダイキン工業株式会社 | Polytetrafluoroethylene mixed powder for insulation of high-frequency signal transmission products and high-frequency signal transmission products using the same |
| EP2372721A4 (en) * | 2008-12-02 | 2014-01-01 | Fujikura Ltd | Transmitting cable and signal transmitting cable using same |
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