GB1078575A - Improvements in or relating to flexible waveguides - Google Patents

Abstract

<PICT:1078575/C6-C7/1> To produce a bellows-type flexible waveguide a metal mandrel 11 is electroplated with copper or copper alloy 12 to the required thickness, jointing end flanges 13 are soldered at 15 to the electrodeposit, a rubber or similar material protective covering 14 is moulded on to the waveguide, and the mandrel is then removed, e.g. with hot caustic soda solution or hydrochloric acid for aluminium or zinc respectively or by immersion in an oil bath heated above the melting point of the mandrel for low melting alloys. As described, after cleaning, the mandrel is electroplated with not more than 0.02 inch layer of the copper or copper alloy, e.g. Cu-Zn, Cu-Sn, and after removal of the mandrel the waveguide is subsequently electroplated internally with a 0.1 mil layer of silver using an internal silver anode rod or plate located by insulating spacers. Typically cyanide baths are used for the electroplating steps and brighteners (unspecified) may be included in the baths. For smooth, uniform deposition of the copper or copper alloy the mandrel may be rotated during plating and air agitation of the bath and periodic reverse current with a 15 secs. cathodic and 2 secs. anodic period may be employed. The copper-zinc alloy bath may include Rochelle salt. The mandrels may be initially degreased with trichlorethylene and then freed of oxide with tartaric acid before plating.