Rainer,
Thank you very much for your explanation. The question came to me through
one of our Engineers who works in our Space Products sector so, I know that
you have correctly identified the phenomenon.
Thanks again for the information and the website link.
Bill Kasprzak
Moog Inc., Electronic Assembly Engineering
> -----Original Message-----
> From: Blomberg, Rainer (FL51) [SMTP:[log in to unmask]]
> Sent: Monday, December 03, 2001 9:27 AM
> To: [log in to unmask]
> Subject: Re: [TN] Red plaque on Silver plated wire?
>
> I have never seen it, but have heard about it during investigation of
> 'Green
> Plague'. The electronics industry term is "Red Plague" not Plaque, and is
> corrosion associated with the use of silver-plated copper wire. Red
> Plague,
> named for it's color, (as opposed to Green Plague) is the cuprous oxide
> (possibly with some black cupric oxide)corrosion product that forms when a
> galvanic cell is formed between copper and silver. This was first studied
> in the sixties when it was established that 'red plague' originates at
> breaks in the silver plating of copper wire strands in the presence of
> moisture and oxygen. Although 'red plague' corrosion of silver plated
> wire
> in service is extremely rare, for high-rel space applications, it is
> necessary to control all steps in the handling and processing of the wire.
> Control seems to be mainly by the wire manufacturer to provide a quality,
> uniform plated thickness (at least 2 um and preferably 4 um) of silver
> without imperfections such as scrapes or porosity. It is important that
> manufacturers ensure they do not damage the continuity of the silver
> plating. In addition, humidity controls can be implemented (dry-nitrogen
> backfill or desiccant) for dry packaging to keep wire reels or spools
> below
> 50% RH.
>
> More information is available and can be found in this book:
> Metallurgical Assessment of Spacecraft Parts, Materials and Processes
> (Second Edition)
> Barrie D. Dunn
> Praxis Publishing Ltd.
> (See http://www.praxis-publishing.co.uk/space/metal.htm)
>
> > Rainer G. Blomberg
> > Honeywell -Space Systems Clearwater
> Staff Production Engineer
> > 13350 US Hwy 19 N MS 802-3
> > Clearwater, FL 33764-7290
> (727) 539-5534 Phone
> (727) 790-8738 Pager
> (727) 539-4469 Fax
> e-mail: [log in to unmask]
>
>
>
> -----Original Message-----
> From: Kasprzak, Bill (sys) USX [mailto:[log in to unmask]]
> Sent: Friday, November 30, 2001 3:08 PM
> To: [log in to unmask]
> Subject: [TN] Red plaque on Silver plated wire?
>
>
> Anybody out there ever hear about having to control red plaque on silver
> plated wire?
>
> This showed up on a spec for a job we're contemplating.
>
> Any and all ('cept wisecracks) responses appreciated. Thanks.
>
> Bill Kasprzak
> Moog Inc., Electronic Assembly Engineering
>
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