JP3599308B2

JP3599308B2 - Semi-rigid coaxial cable and method of manufacturing the same

Info

Publication number: JP3599308B2
Application number: JP4118498A
Authority: JP
Inventors: 弘北沢; 辰男山口
Original assignee: Totoku Electric Co Ltd
Current assignee: Totoku Electric Co Ltd
Priority date: 1998-02-06
Filing date: 1998-02-06
Publication date: 2004-12-08
Anticipated expiration: 2018-02-06
Also published as: JPH11224547A

Description

【０００１】
【産業上の利用分野】
本発明は、セミリジッド同軸ケーブル及びその製造方法に関する。更に詳しくは、小型電子機器の高周波伝送線路に好適な、外部導体をめっきにより形成させるセミリジッド同軸ケーブル及びその製造方法に関する。
【０００２】
【従来の技術】
近時、携帯電話に代表される民生機器等の高周波回路基板、高周波部品間の伝送線路としてセミリジッド同軸ケーブルが広く採用されるようになり、基板へのはんだ付け作業に於いても、従来のはんだゴテによる手作業から、自動化が可能なリフローはんだ付け炉（以下、リフロー炉と略記する）に変わりつつある。
従来より公知のセミリジッド同軸ケーブルとしては、銀めっき銅覆鋼線からなる中心導体の外周に充実絶縁体、例えばポリテトラフルオロエチレン（ＰＴＦＥ）をペースト押出しにより形成し、その外周に銅等の良導電性金属パイプを封入し、ダイスにより引き抜き加工を施し、絶縁体と密着させて外部導体を形成させたセミリジッド同軸ケーブル（以下、パイプ引き抜きセミリジッド同軸ケーブルと略記する）がある。
【０００３】
また、前記良導電性金属パイプの引き抜き加工の代わりに、外部導体をめっきにより形成させたセミリジッド同軸ケーブル（以下、めっきによるセミリジッド同軸ケーブルと略記する）もある。例えば、外部導体にアンカー金属層からなる無電解めっきと、電気めっきを併用させた特開平６−１８７８４７号の同軸ケーブルの製造方法（本発明者等の発明）は、電気めっき厚さを容易にコントロールできるため細径化が可能であり、軽薄・短小化には好適である。
【０００４】
【発明が解決しようとする課題】
しかしながら、前記パイプ引き抜きセミリジッド同軸ケーブルは、リフロー炉を通した時、引き抜き加工で生じた外部導体の歪みや絶縁体へのストレス、または外部導体と絶縁体との熱膨張の相違いによって、端末部では絶縁体が突き出したり、外部導体にクラックが生じ易くなり、そのことによって、電圧定在波比の悪化やシールド効果の低下を招来するという欠点を有している。そのため、外部導体厚さを必要以上に厚く（例えば１５０μｍ）することで外部導体のクラックや絶縁体の突き出しを抑制しており、軽薄・短小化の要求に答えられないという問題があった。
【０００５】
一方、前記めっきによるセミリジッド同軸ケーブルに於いては、通常、絶縁体としてフッ素樹脂の充実体を用いるので、リフロー炉を通した時、前記パイプ引き抜きセミリジッド同軸ケーブル程ではないが、端末部では絶縁体が突き出したり、外部導体にクラックが生じてしまうという問題があった。
【０００６】
本発明は、上記従来技術が有する各種問題点を解決するためになされたもので、リフロー炉を通した時に、端末部での絶縁体の突き出しや外部導体のクラックの発生を防止することができ、端末加工性が良好にでき、更には、めっきによる外部導体の形成が良好にできるセミリジッド同軸ケーブル及びその製造方法を提供することを目的とする。
【０００７】
【課題を解決するための手段】
上記目的を達成するために、第１の観点として本発明は、中心導体１の外周に多孔質絶縁体２を設け、この絶縁体２の外周に外部導体５として、無電解めっきによるアンカー金属層３及び電気めっきによる良導電性金属層４を設けたセミリジッド同軸ケーブルであって、
前記多孔質絶縁体２は、比誘電率（ε）が、１．７５≦ε＜２．００
の条件範囲内の多孔質ポリテトラフルオロエチレン（ＰＴＦＥ）樹脂（以下、多孔質ＰＴＦＥ樹脂と略記する）であり、また前記多孔質絶縁体２の外周に形成されるアンカー金属層３に必要な予備的処理として、前記多孔質絶縁体２の外周に、めっきが可能な金属触媒（以下、金属触媒と略記する）の金属濃度（Ｃ）μｇ／ｃｍ^２が、０．８≦Ｃ＜２．６の条件範囲内で施されているセミリジッド同軸ケーブルにある。
【０００８】
上記本発明の第１の観点のセミリジッド同軸ケーブルは、ＰＴＦＥからなる多孔質絶縁体２の比誘電率（ε）が、１．７５≦ε＜２．００の条件範囲内であることによって、リフロー炉等によるはんだ付け時の熱膨張が緩和され、外部導体５のクラックが抑制できる。また、端末剥離工程に於いて、外部導体５の引き抜き時に多孔質絶縁体２が引きちぎれたり、延ばされてしまうことがなく好ましい。
【０００９】
なお、比誘電率（ε）が１．７５未満の場合は、絶縁体の強度が脆いため、端末剥離工程に於いて、外部導体５の引き抜き時に多孔質絶縁体２が引きちぎれたり、引き延ばされてしまうので好ましくない。多孔質絶縁体２が引き延ばされた状態を図２の写真図に示す。また、比誘電率（ε）が２．００以上の場合は、外部導体５のクラックの抑制に効果がないので好ましくない。
【００１０】
更に、前記多孔質絶縁体２の外周には、金属濃度（Ｃ）μｇ／ｃｍ^２が０．８≦Ｃ＜２．６の、金属触媒が設けられているので、良好な無電解めっきが可能となるため、アンカー金属層３が良好に設けられ、更に電気めっきを併用することによって良導電性金属層４が設けられ、めっきによる外部導体５が良好に形成される。なお、金属触媒の金属濃度（Ｃ）μｇ／ｃｍ^２の測定方法としては、金属触媒付与後、濃硝酸によって剥離溶解させ、原子吸光光度計によって濃度測定を行える。
【００１１】
なお、前記金属濃度（Ｃ）μｇ／ｃｍ^２が０．８未満の場合は、良好な無電解めっきが出来ないため好ましくない。また、金属濃度（Ｃ）μｇ／ｃｍ^２が２．６以上の場合は、必要以上に金属触媒が吸着されているため、めっき反応が促進され、絶縁体と外部導体との間の密着を低下させてしまうばかりでなく、電気めっき時にアンカー金属層が剥離され、一部に無めっきを招来させてしまうため、良好な外部導体を形成させることが困難となってしまう。
【００１２】
第２の観点として本発明は、中心導体１の外周に多孔質絶縁体２を設け、この絶縁体２の外周に外部導体５として、無電解めっきによるアンカー金属層３及び電気めっきによる良導電性金属層４を設けたセミリジッド同軸ケーブルであって、
前記多孔質絶縁体２は、比誘電率（ε）が、１．８５≦ε≦１．９５
の条件範囲内の多孔質ポリテトラフルオロエチレン（ＰＴＦＥ）樹脂であり、また前記多孔質絶縁体２の外周に形成されるアンカー金属層３に必要な予備的処理として、前記多孔質絶縁体２の外周に、金属触媒の金属濃度（Ｃ）μｇ／ｃｍ^２が、１．５≦Ｃ≦２．５の条件範囲内で施されているセミリジッド同軸ケーブルにある。
【００１３】
上記本発明の第２の観点のセミリジッド同軸ケーブルは、ＰＴＦＥからなる多孔質絶縁体２の比誘電率（ε）が、１．８５≦ε≦１．９５の条件範囲内であることによって、リフロー炉等によるはんだ付け時の熱膨張が緩和され、外部導体５のクラックが抑制できる。また、端末剥離工程に於いて、外部導体５の引き抜き時に多孔質絶縁体２が引きちぎれたり、引き延ばされてしまうことがなく端末加工精度が良好である。この状態を図３の写真図に示す。
【００１４】
なお、比誘電率（ε）が１．８５未満の場合は、端末剥離工程に於いて、中心導体、多孔質絶縁体、外部導体の段差加工寸法精度が厳しい場合（例えば、±０．１ｍｍ）、その寸法精度を十分に満足できない。また、比誘電率（ε）が、１．９５を超える場合は、厳しいはんだ付け条件を強いられた場合（例えば、はんだ付け温度３８０℃、はんだ付け時間１０秒）、外部導体５にクラックを招来してしまうので好ましくない。
【００１５】
更に、前記多孔質絶縁体２の外周には、金属濃度（Ｃ）μｇ／ｃｍ^２が１．５≦Ｃ≦２．５の、金属触媒が設けられているので、良好な無電解めっきが可能となるため、アンカー金属層３が良好に設けられ、更に電気めっきを併用することによって良導電性金属層４が設けられ、めっきによる外部導体５が良好に形成される。
【００１６】
なお、金属触媒の金属濃度（Ｃ）μｇ／ｃｍ^２が１．５未満の場合、絶縁体外径が細径の時（例えば、０．５ｍｍ以下）は、めっき液と被めっき体（多孔質絶縁体２）とのバランスが悪く、無電解めっきによるアンカー金属層３形成時に、一部無めっきを招来させてしまうので好ましくない。また、金属触媒の金属濃度（Ｃ）μｇ／ｃｍ^２が２．５を超える場合、絶縁体外径が細径の時（例えば、０．５ｍｍ以下）は、必要以上に金属触媒が吸着されているため、めっき反応が促進され、多孔質絶縁体２と外部導体５との間の密着を低下させてしまうばかりでなく、電気めっき時にアンカー金属層３が剥離され、一部無めっきを招来させてしまうため、良好な外部導体を形成させることが困難となってしまうので好ましくない。
【００１７】
第３の観点として本発明は、前記めっきが可能な金属触媒が、パラジウム、金、銀、銅等標準酸化還元電位が１．５Ｖ以上の金属である前記第１および第２の観点のセミリジッド同軸ケーブルにある。
【００１８】
上記本発明の第３の観点のセミリジッド同軸ケーブルは、金属触媒として、パラジウム、金、銀、銅等標準酸化還元電位が１．５Ｖ以上の金属を好ましく用いることが出来る。
【００１９】
第４の観点として本発明は、中心導体１の外周に多孔質絶縁体２を設け、この絶縁体２の外周に外部導体５として，無電解めっきによるアンカー金属層３及び電気めっきによる良導電性金属層４を設けてセミリジッド同軸ケーブル１０とするセミリジッド同軸ケーブルの製造方法であって、
前記多孔質絶縁体２は、比誘電率（ε）が、１．７５≦ε＜２．００
の多孔質ポリテトラフルオロエチレン（ＰＴＦＥ）樹脂をペースト押出しにより形成し、また前記外部導体５を形成する前の予備的処理として、前記多孔質絶縁体２の外周に、金属濃度（Ｃ）μｇ／ｃｍ^２が、０．８≦Ｃ＜２．６
の、金属触媒を設けてからアンカー金属層３を形成するセミリジッド同軸ケーブルの製造方法にある。
【００２０】
上記本発明の第４の観点のセミリジッド同軸ケーブルの製造方法によれば、前記第１の観点のセミリジッド同軸ケーブルを効率よく製造することが出来る。
【００２１】
第５の観点として本発明は、中心導体１の外周に多孔質絶縁体２を設け、この絶縁体２の外周に外部導体５として，無電解めっきによるアンカー金属層３及び電気めっきによる良導電性金属層４を設けてセミリジッド同軸ケーブル１０とするセミリジッド同軸ケーブルの製造方法であって、
前記多孔質絶縁体２は、比誘電率（ε）が、１．８５≦ε≦１．９５の多孔質ポリテトラフルオロエチレン（ＰＴＦＥ）樹脂をペースト押出しにより形成し、また前記外部導体５を形成する前の予備的処理として、前記多孔質絶縁体２の外周に、金属濃度（Ｃ）μｇ／ｃｍ^２が、１．５≦Ｃ≦２．５の、めっきが可能な金属触媒を設けてからアンカー金属層３を形成するセミリジッド同軸ケーブルの製造方法にある。
【００２２】
上記本発明の第５の観点のセミリジッド同軸ケーブルの製造方法によれば、前記第２の観点のセミリジッド同軸ケーブルを効率よく製造することが出来る。
【００２３】
第６の観点として本発明は、前記めっきが可能な金属触媒が、パラジウム、金、銀、銅等標準酸化還元電位が１．５Ｖ以上の金属である前記第４および第５の観点のセミリジッド同軸ケーブルの製造方法にある。
【００２４】
上記本発明の第６の観点のセミリジッド同軸ケーブルの製造方法によれば、前記第３の観点のセミリジッド同軸ケーブルを効率よく製造することができる。
【００２５】
【発明の実施の形態】
以下、本発明の内容を実施の形態により詳細に説明する。図１は本発明のセミリジッド同軸ケーブルの一実施例を示す横断面図である。また、外部導体の形成方法は、本発明者等の発明である特開平６−１８７８４７号に準拠している。なお、本発明は本実施の形態に限定されるものではない。
【００２６】
１．第１の実施の形態
中心導体１として、φ０．１６２ｍｍの銀めっき銅覆鋼線（Ａｇ−ＣＰ）の外周に、絶縁体外径０．５０ｍｍ、比誘電率１．８５の多孔質ＰＴＦＥ樹脂をペースト押し出しによって形成し、多孔質絶縁体２を設けた。次に前記多孔質絶縁体２の表面を金属ナトリウム−ナフタレン錯体溶液中に浸漬させて親水性化した後水洗し、パラジウム−スズコロイド溶液中に浴温３０℃，３分間の条件によって浸漬し、該絶縁体２の表面上にパラジウムイオンを吸着させた。更に水洗後、酸性溶液中に浸漬し、パラジウムイオンを金属として還元析出させた。この条件下によって、めっきが可能な金属触媒を原子吸光によって測定したところ１．５μｇ／ｃｍ^２であった。続いて、無電解ニッケルめっきによってニッケルからなるアンカー金属層３を０．５μｍ厚さに形成させ、更にその外周に電気硫酸銅めっきによって５０μｍ厚さの銅からなる良導電性金属層４を施し、前記アンカー金属層３と良導電性金属層４により外部導体５とし、仕上がり外径が０．６０ｍｍのセミリジッド同軸ケーブル１０を製造した。表１にその要部構成を示す。
【００２７】
２．第２の実施の形態
中心導体１として、φ０．１６２ｍｍの銀めっき銅覆鋼線の外周に、絶縁体外径０．５０ｍｍ、比誘電率１．９０の多孔質ＰＴＦＥ樹脂をペースト押し出しによって形成し、多孔質絶縁体２を設けた。次に前記第１の実施の形態と同様にして、前記多孔質絶縁体２の表面上にパラジウムイオンを金属として還元析出させた。この条件下によって、めっきが可能な金属触媒を原子吸光によって測定したところ２．０μｇ／ｃｍ^２であった。続いて、前記第１の実施の形態と同様にして、ニッケルからなるアンカー金属層３を０．５μｍ厚さに形成させ、更にその外周に５０μｍ厚さの銅からなる良導電性金属層４を施し、仕上がり外径が０．６０ｍｍのセミリジッド同軸ケーブル１０を製造した。表１にその要部構成を示す。
【００２８】
３．第３の実施の形態
中心導体１として、φ０．１６２ｍｍの銀めっき銅覆鋼線の外周に、絶縁体外径０．５０ｍｍ、比誘電率１．９５の多孔質ＰＴＦＥ樹脂をペースト押し出しによって形成し、多孔質絶縁体２を設けた。次に前記第１の実施の形態と同様にして、前記多孔質絶縁体２の表面上にパラジウムイオンを金属として還元析出させた。この条件下によって、めっきが可能な金属触媒を原子吸光によって測定したところ２．５μｇ／ｃｍ^２であった。続いて、前記第１の実施の形態と同様にして、ニッケルからなるアンカー金属層３を０．５μｍ厚さに形成させ、更にその外周に５０μｍ厚さの銅からなる良導電性金属層４を施し、仕上がり外径が０．６０ｍｍのセミリジッド同軸ケーブル１０を製造した。表１にその要部構成を示す。
【００２９】
４．第４の実施の形態
中心導体１として、φ０．１６２ｍｍの銀めっき銅覆鋼線の外周に、絶縁体外径０．５０ｍｍ、比誘電率１．９０の多孔質ＰＴＦＥ樹脂をペースト押し出しによって形成し、多孔質絶縁体２を設けた。次に前記多孔質絶縁体２の表面を金属ナトリウム−ナフタレン錯体溶液中に浸漬させて親水性化した後水洗し、塩化金水溶液中に浴温４０℃，３分間の条件によって浸漬し、該絶縁体２の表面上に塩化金イオンを吸着させた。更に水洗後、酸性溶液中に浸漬し、塩化金イオンを金属として還元析出させた。この条件下によって、めっきが可能な金属触媒を原子吸光によって測定したところ２．５μｇ／ｃｍ^２であった。続いて、前記第１の実施の形態と同様にして、ニッケルからなるアンカー金属層３を０．５μｍ厚さに形成させ、更にその外周に５０μｍ厚さの銅からなる良導電性金属層４を施し、仕上がり外径が０．６０ｍｍのセミリジッド同軸ケーブル１０を製造した。表１にその要部構成を示す。
【００３０】
５．第５〜７の実施の形態
第５〜７の実施の形態については、多孔質絶縁体２の比誘電率と、金属触媒の種類，濃度を表１のように設定し、その他は前記第１の実施の形態に準じて仕上がり外径が０．６０ｍｍのセミリジッド同軸ケーブル１０を製造した。
【００３１】
６．比較例
比較例１、２
比較例１、２については、多孔質絶縁体の比誘電率と、金属触媒の種類，濃度を表１のように設定し、その他は前記第１の実施の形態に準じて仕上がり外径が０．６０ｍｍのセミリジッド同軸ケーブルを製造した。
【００３２】
上記本発明の実施の形態及び比較例のセミリジッド同軸ケーブルについて、その要部構成を下記表１に示す。また、本発明の実施の形態及び比較例のセミリジッド同軸ケーブルついての特性試験として、端末加工性とはんだ付け性（はんだ付け時の外部導体のクラック）を調査した。なお、はんだ付けは、コテ先温度３８０℃，５秒間の条件で直接コテ先をケーブルに接触させた。その結果を、下記表２に示す。
【００３３】
【表１】

【００３４】
【表２】

【００３５】
上記表２から明らかなように、本発明のセミリジッド同軸ケーブルは端末加工性及びはんだ付け性が良いことが分かる。一方比較例のセミリジッド同軸ケーブルは端末加工性又ははんだ付け性のどちらかが悪いことが分かる。
【００３６】
【発明の効果】
本発明の製造方法により得られるセミリジッド同軸ケーブルでは、ＰＴＦＥからなる多孔質絶縁体の比誘電率（ε）が、１．７５≦ε＜２．００の条件範囲内であることによって、リフロー炉等によるはんだ付け時の熱膨張が緩和され、外部導体のクラックが抑制できるようになった。
また、その外周に形成されるアンカー金属層に必要な予備的処理として、金属触媒の金属濃度（Ｃ）μｇ／ｃｍ^２が０．８≦Ｃ＜２．６であることによって、良好な無電解めっきが可能となるため、電気めっきを併用することによって、めっきによる外部導体の形成が良好となった。
【００３７】
更に好ましくは、ＰＴＦＥからなる多孔質絶縁体の比誘電率（ε）が、１．８５≦ε＜１．９５の条件範囲内であることによって、はんだ付け時の熱膨張が緩和され、外部導体のクラックが抑制できるとともに端末加工精度が良好となった。
また、その外周に形成されるアンカー金属層に必要な予備的処理として、金属触媒の金属濃度（Ｃ）μｇ／ｃｍ^２を１．５≦Ｃ＜２．５の条件範囲内にすることによって、絶縁体外径が細径の場合においても良好な外部導体を形成させることが容易となった。
従って、本発明のセミリジッド同軸ケーブルは、軽薄・短小化に好適となり、産業上に寄与するところ極めて大である。
【図面の簡単な説明】
【図１】本発明のセミリジッド同軸ケーブルの一実施例を示す横断面図である。（従来例にも使用）
【図２】端末剥離工程に於いて、外部導体の引き抜き時に多孔質絶縁体が引き延ばされた状態を示す写真図である。
【図３】端末剥離工程に於いて、外部導体の引き抜き時に多孔質絶縁体が引きちぎれたり、引き延ばされてしまうことがなく、端末加工精度が良好な状態を示す写真図である。
【符号の説明】
１中心導体
２多孔質絶縁体
３アンカー金属層
４良導電性金属層
５外部導体
１０セミリジッド同軸ケーブル[0001]
[Industrial applications]
The present invention relates to a semi-rigid coaxial cable and a method for manufacturing the same. More specifically, the present invention relates to a semi-rigid coaxial cable suitable for a high-frequency transmission line of a small electronic device and having an outer conductor formed by plating, and a method of manufacturing the same.
[0002]
[Prior art]
In recent years, semi-rigid coaxial cables have become widely used as transmission lines between high-frequency circuit boards and high-frequency components of consumer electronics such as mobile phones. It is changing from a manual operation with a trowel to a reflow soldering furnace that can be automated (hereinafter abbreviated as a reflow furnace).
As a conventionally known semi-rigid coaxial cable, a solid insulator, for example, polytetrafluoroethylene (PTFE) is formed on the outer periphery of a center conductor made of silver-plated copper-coated steel wire by paste extrusion, and a good conductive material such as copper is formed on the outer periphery. There is a semi-rigid coaxial cable (hereinafter, abbreviated as a pipe-pulled semi-rigid coaxial cable) in which a conductive metal pipe is sealed, subjected to a drawing process with a die, and brought into close contact with an insulator to form an outer conductor.
[0003]
There is also a semi-rigid coaxial cable in which an outer conductor is formed by plating (hereinafter, abbreviated as a semi-rigid coaxial cable by plating) instead of the drawing of the good conductive metal pipe. For example, the method of manufacturing a coaxial cable (inventor of the present inventors) disclosed in Japanese Patent Application Laid-Open No. HEI 6-187847 in which electroless plating comprising an anchor metal layer and electroplating are used in combination for the outer conductor is easy to reduce the electroplating thickness. Since it can be controlled, it is possible to reduce the diameter, which is suitable for reducing the weight and thickness.
[0004]
[Problems to be solved by the invention]
However, the pipe drawn semi-rigid coaxial cable, when passed through a reflow furnace, the distortion of the outer conductor caused by the drawing process, the stress on the insulator, or the difference in thermal expansion between the outer conductor and the insulator, In this case, the insulator easily protrudes and a crack is easily generated in the outer conductor, which has a drawback that the voltage standing wave ratio is deteriorated and the shielding effect is lowered. For this reason, by making the thickness of the outer conductor thicker than necessary (for example, 150 μm), cracks in the outer conductor and protrusion of the insulator are suppressed, and there has been a problem that the demand for lighter, thinner and shorter devices cannot be met.
[0005]
On the other hand, in the semi-rigid coaxial cable by plating, usually, a solid body of a fluororesin is used as an insulator. However, there has been a problem that the protrusions protrude or cracks occur in the outer conductor.
[0006]
The present invention has been made in order to solve the above-described various problems of the related art, and can prevent the protrusion of the insulator at the terminal portion and the occurrence of cracks in the outer conductor when passing through a reflow furnace. It is another object of the present invention to provide a semi-rigid coaxial cable capable of improving the terminal workability and forming the outer conductor by plating, and a method of manufacturing the same.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, as a first aspect, the present invention provides a porous insulator 2 provided on an outer periphery of a center conductor 1, and an outer conductor 5 provided on an outer periphery of the insulator 2 as an anchor metal layer formed by electroless plating. 3 and a semi-rigid coaxial cable provided with a good conductive metal layer 4 by electroplating,
The porous insulator 2 has a relative dielectric constant (ε) of 1.75 ≦ ε <2.00.
(Hereinafter, abbreviated as porous PTFE resin) within the above condition range, and a necessary auxiliary metal layer 3 for the anchor metal layer 3 formed on the outer periphery of the porous insulator 2. As a typical treatment, the metal concentration (C) μg / cm ^{2 of} a metal catalyst capable of plating (hereinafter abbreviated as “metal catalyst”) on the outer periphery of the porous insulator ² is 0.8 ≦ C <2.6. The semi-rigid coaxial cable is provided within the range of conditions.
[0008]
In the semi-rigid coaxial cable according to the first aspect of the present invention, the relative dielectric constant (ε) of the porous insulator 2 made of PTFE is in the range of 1.75 ≦ ε <2.00, and the reflow Thermal expansion during soldering in a furnace or the like is alleviated, and cracks in the outer conductor 5 can be suppressed. Further, in the terminal peeling step, the porous insulator 2 is preferably not torn or stretched when the outer conductor 5 is pulled out.
[0009]
When the relative dielectric constant (ε) is less than 1.75, the strength of the insulator is brittle, so that the porous insulator 2 is torn or stretched when the outer conductor 5 is pulled out in the terminal peeling step. It is not preferable because it is done. FIG. 2 is a photograph showing a state in which the porous insulator 2 is elongated. Further, when the relative dielectric constant (ε) is 2.00 or more, it is not preferable because it has no effect on suppressing cracks in the outer conductor 5.
[0010]
Further, since a metal catalyst having a metal concentration (C) μg / cm ² of 0.8 ≦ C <2.6 is provided on the outer periphery of the porous insulator 2, good electroless plating is possible. Therefore, the anchor metal layer 3 is favorably provided, and the good conductive metal layer 4 is further provided by using electroplating in combination, so that the outer conductor 5 is favorably formed by plating. In addition, as a method of measuring the metal concentration (C) μg / cm ² of the metal catalyst, after applying the metal catalyst, the metal catalyst is separated and dissolved with concentrated nitric acid, and the concentration can be measured by an atomic absorption spectrophotometer.
[0011]
When the metal concentration (C) μg / cm ² is less than 0.8, good electroless plating cannot be performed, which is not preferable. When the metal concentration (C) μg / cm ² is 2.6 or more, the plating reaction is promoted because the metal catalyst is adsorbed more than necessary, and the adhesion between the insulator and the external conductor is reduced. In addition to this, the anchor metal layer is peeled off during electroplating, which causes non-plating to occur partially, which makes it difficult to form a good external conductor.
[0012]
According to a second aspect of the present invention, a porous insulator 2 is provided on the outer periphery of a center conductor 1 and an outer conductor 5 is provided on the outer periphery of the insulator 2 as an anchor metal layer 3 formed by electroless plating and a conductive material formed by electroplating. A semi-rigid coaxial cable provided with a metal layer 4,
The porous insulator 2 has a relative dielectric constant (ε) of 1.85 ≦ ε ≦ 1.95.
As a preliminary treatment necessary for the anchor metal layer 3 formed on the outer periphery of the porous insulator 2, a porous polytetrafluoroethylene (PTFE) resin within the condition range of The semi-rigid coaxial cable is provided on the outer periphery with a metal concentration (C) μg / cm ² of the metal catalyst within a range of 1.5 ≦ C ≦ 2.5.
[0013]
In the semi-rigid coaxial cable according to the second aspect of the present invention, the relative dielectric constant (ε) of the porous insulator 2 made of PTFE is in the range of 1.85 ≦ ε ≦ 1.95, and the reflow Thermal expansion during soldering in a furnace or the like is alleviated, and cracks in the outer conductor 5 can be suppressed. Further, in the terminal peeling step, the porous insulator 2 is not torn or stretched when the outer conductor 5 is pulled out, and the terminal processing accuracy is good. This state is shown in the photograph of FIG.
[0014]
When the relative dielectric constant (ε) is less than 1.85, the step processing dimensional accuracy of the center conductor, the porous insulator, and the outer conductor is severe in the terminal peeling step (for example, ± 0.1 mm). However, the dimensional accuracy cannot be sufficiently satisfied. When the relative dielectric constant (ε) exceeds 1.95, cracks may occur in the outer conductor 5 when severe soldering conditions are imposed (for example, a soldering temperature of 380 ° C. and a soldering time of 10 seconds). It is not preferable.
[0015]
Further, since a metal catalyst having a metal concentration (C) μg / cm ² of 1.5 ≦ C ≦ 2.5 is provided on the outer periphery of the porous insulator 2, good electroless plating is possible. Therefore, the anchor metal layer 3 is favorably provided, and the good conductive metal layer 4 is further provided by using electroplating in combination, so that the outer conductor 5 is favorably formed by plating.
[0016]
When the metal concentration (C) μg / cm ^{2 of} the metal catalyst is less than 1.5, when the outer diameter of the insulator is small (for example, 0.5 mm or less), the plating solution and the object to be plated (porous insulating material) The balance with the body 2) is poor, and when the anchor metal layer 3 is formed by the electroless plating, plating is partially unpreferably caused. Further, when the metal concentration (C) μg / cm ^{2 of} the metal catalyst exceeds 2.5, and when the outer diameter of the insulator is small (for example, 0.5 mm or less), the metal catalyst is adsorbed more than necessary. Therefore, the plating reaction is promoted, and not only does the adhesion between the porous insulator 2 and the outer conductor 5 decrease, but also the anchor metal layer 3 is peeled off during electroplating, which causes some non-plating. Therefore, it is difficult to form a good external conductor, which is not preferable.
[0017]
As a third aspect, the present invention provides the semi-rigid coaxial according to the first and second aspects, wherein the metal catalyst capable of plating is a metal such as palladium, gold, silver, and copper having a standard oxidation-reduction potential of 1.5 V or more. On the cable.
[0018]
In the semi-rigid coaxial cable according to the third aspect of the present invention, a metal having a standard oxidation-reduction potential of 1.5 V or more, such as palladium, gold, silver, or copper, can be preferably used as a metal catalyst.
[0019]
According to a fourth aspect of the present invention, a porous insulator 2 is provided on the outer periphery of the center conductor 1, and the outer conductor 5 is provided on the outer periphery of the insulator 2 as an anchor metal layer 3 by electroless plating and a good conductivity by electroplating. A method for manufacturing a semi-rigid coaxial cable having a metal layer 4 and a semi-rigid coaxial cable 10,
The porous insulator 2 has a relative dielectric constant (ε) of 1.75 ≦ ε <2.00.
The porous polytetrafluoroethylene (PTFE) resin is formed by paste extrusion, and as a preliminary treatment before the outer conductor 5 is formed, a metal concentration (C) μg / cm ² is 0.8 ≦ C <2.6
The method for producing a semi-rigid coaxial cable in which an anchor metal layer 3 is formed after providing a metal catalyst.
[0020]
According to the method for manufacturing a semi-rigid coaxial cable according to the fourth aspect of the present invention, the semi-rigid coaxial cable according to the first aspect can be efficiently manufactured.
[0021]
According to a fifth aspect of the present invention, a porous insulator 2 is provided on the outer periphery of the center conductor 1, and the outer conductor 5 is provided on the outer periphery of the insulator 2 as an anchor metal layer 3 by electroless plating and a good conductivity by electroplating. A method for manufacturing a semi-rigid coaxial cable having a metal layer 4 and a semi-rigid coaxial cable 10,
The porous insulator 2 is formed by extruding a porous polytetrafluoroethylene (PTFE) resin having a relative dielectric constant (ε) of 1.85 ≦ ε ≦ 1.95 by paste extrusion, and forming the external conductor 5. As a preliminary treatment before plating, a metal catalyst capable of plating with a metal concentration (C) μg / cm ² of 1.5 ≦ C ≦ 2.5 is provided on the outer periphery of the porous insulator 2. The method is for manufacturing a semi-rigid coaxial cable forming the anchor metal layer 3.
[0022]
According to the method for manufacturing a semi-rigid coaxial cable according to the fifth aspect of the present invention, the semi-rigid coaxial cable according to the second aspect can be efficiently manufactured.
[0023]
As a sixth aspect, the present invention provides the semi-rigid coaxial cable according to the fourth and fifth aspects, wherein the metal catalyst capable of plating is a metal having a standard oxidation-reduction potential of 1.5 V or more, such as palladium, gold, silver, and copper. In the method of manufacturing the cable.
[0024]
According to the method for manufacturing a semi-rigid coaxial cable according to the sixth aspect of the present invention, the semi-rigid coaxial cable according to the third aspect can be efficiently manufactured.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the contents of the present invention will be described in detail by embodiments. FIG. 1 is a cross-sectional view showing one embodiment of the semi-rigid coaxial cable of the present invention. The method of forming the outer conductor conforms to Japanese Patent Application Laid-Open No. 6-187847, which is an invention of the present inventors. Note that the present invention is not limited to the present embodiment.
[0026]
1. First Embodiment As a central conductor 1, a porous PTFE resin having an insulator outer diameter of 0.50 mm and a relative dielectric constant of 1.85 is paste on the outer periphery of a silver-plated copper-clad steel wire (Ag-CP) having a diameter of 0.162 mm. The porous insulator 2 was formed by extrusion. Next, the surface of the porous insulator 2 is immersed in a metal sodium-naphthalene complex solution to make it hydrophilic, washed with water, and immersed in a palladium-tin colloid solution at a bath temperature of 30 ° C. for 3 minutes. Palladium ions were adsorbed on the surface of the insulator 2. Further, after washing with water, it was immersed in an acidic solution, and reduced and precipitated using palladium ion as a metal. Under these conditions, the metal catalyst capable of plating was measured by atomic absorption and found to be 1.5 μg / cm ² . Subsequently, an anchor metal layer 3 made of nickel is formed to a thickness of 0.5 μm by electroless nickel plating, and a good conductive metal layer 4 made of copper having a thickness of 50 μm is applied to the outer periphery of the anchor metal layer 3 by electrolytic copper sulfate plating. A semi-rigid coaxial cable 10 having a finished outer diameter of 0.60 mm was manufactured by using the anchor metal layer 3 and the good conductive metal layer 4 as the outer conductor 5. Table 1 shows the configuration of the main part.
[0027]
2. Second Embodiment As a central conductor 1, a porous PTFE resin having an insulator outer diameter of 0.50 mm and a relative dielectric constant of 1.90 is formed on a periphery of a silver-plated copper-coated steel wire having a diameter of 0.162 mm by paste extrusion, A porous insulator 2 was provided. Next, in the same manner as in the first embodiment, palladium ions were reduced and deposited on the surface of the porous insulator 2 as a metal. Under these conditions, the metal catalyst capable of plating was measured by atomic absorption to find that it was 2.0 μg / cm ² . Subsequently, in the same manner as in the first embodiment, an anchor metal layer 3 made of nickel is formed to a thickness of 0.5 μm, and a good conductive metal layer 4 made of copper having a thickness of 50 μm is further formed around the anchor metal layer 3. The semi-rigid coaxial cable 10 having a finished outer diameter of 0.60 mm was manufactured. Table 1 shows the configuration of the main part.
[0028]
3. Third Embodiment As the central conductor 1, a porous PTFE resin having an insulator outer diameter of 0.50 mm and a relative dielectric constant of 1.95 is formed on a periphery of a silver-plated copper-covered steel wire having a diameter of 0.162 mm by paste extrusion, A porous insulator 2 was provided. Next, in the same manner as in the first embodiment, palladium ions were reduced and deposited on the surface of the porous insulator 2 as a metal. Under these conditions, the metal catalyst capable of plating was measured by atomic absorption to find that it was 2.5 μg / cm ² . Subsequently, in the same manner as in the first embodiment, an anchor metal layer 3 made of nickel is formed to a thickness of 0.5 μm, and a good conductive metal layer 4 made of copper having a thickness of 50 μm is further formed around the anchor metal layer 3. The semi-rigid coaxial cable 10 having a finished outer diameter of 0.60 mm was manufactured. Table 1 shows the configuration of the main part.
[0029]
4. Fourth Embodiment As a central conductor 1, a porous PTFE resin having an insulator outer diameter of 0.50 mm and a relative dielectric constant of 1.90 is formed on a periphery of a silver-plated copper-covered steel wire having a diameter of 0.162 mm by paste extrusion, A porous insulator 2 was provided. Next, the surface of the porous insulator 2 is immersed in a metal sodium-naphthalene complex solution to make it hydrophilic, washed with water, and immersed in an aqueous solution of gold chloride at a bath temperature of 40 ° C. for 3 minutes. Gold chloride ions were adsorbed on the surface of the body 2. Further, after washing with water, it was immersed in an acidic solution, and reduced and precipitated using gold chloride ions as a metal. Under these conditions, the metal catalyst capable of plating was measured by atomic absorption to find that it was 2.5 μg / cm ² . Subsequently, in the same manner as in the first embodiment, an anchor metal layer 3 made of nickel is formed to a thickness of 0.5 μm, and a good conductive metal layer 4 made of copper having a thickness of 50 μm is further formed around the anchor metal layer 3. The semi-rigid coaxial cable 10 having a finished outer diameter of 0.60 mm was manufactured. Table 1 shows the configuration of the main part.
[0030]
5. Fifth to Seventh Embodiments In the fifth to seventh embodiments, the relative dielectric constant of the porous insulator 2, the type and concentration of the metal catalyst are set as shown in Table 1, and the others are the same as those of the first embodiment. A semi-rigid coaxial cable 10 having a finished outer diameter of 0.60 mm was manufactured according to the embodiment.
[0031]
6. Comparative Examples Comparative Examples 1 and 2
In Comparative Examples 1 and 2, the relative dielectric constant of the porous insulator, the type and concentration of the metal catalyst were set as shown in Table 1, and the remaining outer diameter was 0 according to the first embodiment. A .60 mm semi-rigid coaxial cable was manufactured.
[0032]
Table 1 below shows the main configuration of the semi-rigid coaxial cable according to the embodiment of the present invention and the comparative example. In addition, as a characteristic test for the semi-rigid coaxial cable according to the embodiment of the present invention and the comparative example, terminal workability and solderability (cracks of the outer conductor during soldering) were investigated. In the soldering, the iron tip was brought into direct contact with the cable at a temperature of 380 ° C. for 5 seconds. The results are shown in Table 2 below.
[0033]
[Table 1]

[0034]
[Table 2]

[0035]
As is clear from Table 2, the semi-rigid coaxial cable of the present invention has good terminal workability and solderability. On the other hand, it can be seen that the semi-rigid coaxial cable of the comparative example has poor end workability or solderability.
[0036]
【The invention's effect】
In the semi-rigid coaxial cable obtained by the production method of the present invention, the relative dielectric constant (ε) of the porous insulator made of PTFE is in the range of 1.75 ≦ ε <2.00, and the reflow furnace or the like is used. , The thermal expansion during soldering is reduced, and cracks in the outer conductor can be suppressed.
As a preliminary treatment required for the anchor metal layer formed on the outer periphery, good electrolessness can be obtained by setting the metal concentration (C) μg / cm ² of the metal catalyst to 0.8 ≦ C <2.6. Since plating is possible, the formation of the outer conductor by plating is improved by using electroplating in combination.
[0037]
More preferably, when the relative dielectric constant (ε) of the porous insulator made of PTFE is within the range of 1.85 ≦ ε <1.95, thermal expansion during soldering is reduced, and the external conductor Cracks can be suppressed, and the terminal processing accuracy is improved.
In addition, as a preliminary treatment required for the anchor metal layer formed on the outer periphery, the metal concentration (C) μg / cm ² of the metal catalyst is set to fall within the range of 1.5 ≦ C <2.5. Even when the outer diameter of the insulator is small, it is easy to form a good external conductor.
Therefore, the semi-rigid coaxial cable of the present invention is suitable for reduction in weight and thickness, and is extremely large in terms of industrial contribution.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing one embodiment of a semi-rigid coaxial cable of the present invention. (Also used in conventional examples)
FIG. 2 is a photograph showing a state in which a porous insulator is stretched when an external conductor is pulled out in a terminal peeling step.
FIG. 3 is a photographic view showing a state in which a porous insulator is not torn or stretched at the time of pulling out an external conductor in a terminal peeling step and terminal processing accuracy is good.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Center conductor 2 Porous insulator 3 Anchor metal layer 4 Good conductive metal layer 5 Outer conductor 10 Semi-rigid coaxial cable

Claims

A semi-rigid coaxial cable in which a porous insulator 2 is provided on an outer periphery of a center conductor 1 and an anchor metal layer 3 formed by electroless plating and a good conductive metal layer 4 formed by electroplating are provided as outer conductors 5 on the outer periphery of the insulator 2. And
The porous insulator 2 has a relative dielectric constant (ε),
1.75 ≦ ε <2.00
As a preliminary treatment required for the anchor metal layer 3 formed on the outer periphery of the porous insulator 2, the outer periphery of the porous insulator 2 is The metal concentration (C) μg / cm ² of the metal catalyst capable of plating is
0.8 ≦ C <2.6
A semi-rigid coaxial cable, which is provided within the following condition range.

A semi-rigid coaxial cable in which a porous insulator 2 is provided on an outer periphery of a center conductor 1 and an anchor metal layer 3 formed by electroless plating and a good conductive metal layer 4 formed by electroplating are provided as outer conductors 5 on the outer periphery of the insulator 2. And
The porous insulator 2 has a relative dielectric constant (ε),
1.85 ≦ ε ≦ 1.95
As a preliminary treatment required for the anchor metal layer 3 formed on the outer periphery of the porous insulator 2, the outer periphery of the porous insulator 2 is The metal concentration (C) μg / cm ² of the metal catalyst capable of plating is
1.5 ≦ C ≦ 2.5
A semi-rigid coaxial cable, which is provided within the following condition range.

The semi-rigid coaxial cable according to claim 1 or 2, wherein the metal catalyst capable of plating is a metal having a standard oxidation-reduction potential of 1.5 V or more, such as palladium, gold, silver, and copper.

A semi-rigid coaxial cable having a porous insulator 2 provided on the outer periphery of a center conductor 1 and an anchor metal layer 3 formed by electroless plating and a good conductive metal layer 4 formed by electroplating provided as an outer conductor 5 on the outer periphery of the insulator 2 10. A method of manufacturing a semi-rigid coaxial cable, which is set to 10.
The porous insulator 2 has a relative dielectric constant (ε) of 1.75 ≦ ε <2.00.
As a preliminary treatment before forming the outer conductor 5, a metal concentration (C) μg / cm ² is formed around the porous insulator 2 as a preliminary treatment before forming the outer conductor 5. , 0.8 ≦ C <2.6
A method for producing a semi-rigid coaxial cable, wherein a metal catalyst capable of plating is provided and then the anchor metal layer 3 is formed.

A semi-rigid coaxial cable having a porous insulator 2 provided on the outer periphery of a center conductor 1 and an anchor metal layer 3 formed by electroless plating and a good conductive metal layer 4 formed by electroplating as an outer conductor 5 on the outer periphery of the insulator 2 10. A method of manufacturing a semi-rigid coaxial cable, which is set to 10.
The porous insulator 2 has a relative dielectric constant (ε) of 1.85 ≦ ε ≦ 1.95.
As a preliminary treatment before forming the outer conductor 5, a metal concentration (C) μg / cm ² is formed around the porous insulator 2 as a preliminary treatment before forming the outer conductor 5. , 1.5 ≦ C ≦ 2.5
A method for producing a semi-rigid coaxial cable, wherein a metal catalyst capable of plating is provided and then the anchor metal layer 3 is formed.

The method for producing a semi-rigid coaxial cable according to claim 4 or 5, wherein the metal catalyst capable of plating is a metal having a standard oxidation-reduction potential of 1.5 V or more, such as palladium, gold, silver, and copper.