David, Thank you for asking this question. I presently am in the early stages of qualifying Immersion Silver and have caused a phenomenon that I think may be "Red Plague". After 24 hours in 85/85 environment (we were trying to grow dendrites) all PCBs have a reddish brown corrosion appearance. One sample was direct from vendor, one sample after 5 thermal excursions to reflow temps and another sample after wash with solvent, alcohol and 5 thermal excursions. I think this phenomenon is from the extremely thin layer created by immersion process causing the Cu/Ag intermetallic to actually be the surface of the finish. With this said I wonder can Immersion Silver thickness be increased (from 8 to 11 microinches [0.2 to 0.3 microns] to maybe 30+ microinch [8+ micron] range)to allow non-intermetallic silver to be on surface? Hey experts, how about some help? Thanks in Advance, FNK Frank N Kimmey, C.I.D.+ Senior PCB Designer Powerwave Technologies PH. 916-941-3159 Fax 916-941-3195 -----Original Message----- From: David Douthit [mailto:[log in to unmask]] Sent: Monday, December 03, 2001 11:58 AM To: [log in to unmask] Subject: Re: [TN] Red plaque on Silver plated wire? Does this "Red Plague" effect immersion silver finishes??? David A. Douthit Manager LoCan LLC David Fish wrote: > Expanding on Rainer's points look here: > http://www.corrosion-doctors.org/MatSelect/corrsilver.htm > > Dave Fish > ----- Original Message ----- > From: "Blomberg, Rainer (FL51)" <[log in to unmask]> > To: <[log in to unmask]> > Sent: Monday, December 03, 2001 6:27 AM > 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 > > > > -------------------------------------------------------------------------- > -- > > ----- > > Technet Mail List provided as a free service by IPC using LISTSERV 1.8d > > To unsubscribe, send a message to [log in to unmask] with following text in > > the BODY (NOT the subject field): SIGNOFF Technet > > To temporarily halt delivery of Technet send the following message: SET > > Technet NOMAIL > > Search previous postings at: www.ipc.org > On-Line Resources & Databases > > > E-mail Archives > > Please visit IPC web site (http://www.ipc.org/html/forum.htm) for > additional > > information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 > > ext.5315 > > -------------------------------------------------------------------------- > -- > > ----- > > > > -------------------------------------------------------------------------- > ------- > > Technet Mail List provided as a free service by IPC using LISTSERV 1.8d > > To unsubscribe, send a message to [log in to unmask] with following text in > > the BODY (NOT the subject field): SIGNOFF Technet > > To temporarily halt delivery of Technet send the following message: SET > Technet NOMAIL > > Search previous postings at: www.ipc.org > On-Line Resources & Databases > > E-mail Archives > > Please visit IPC web site (http://www.ipc.org/html/forum.htm) for > additional > > information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 > ext.5315 > > -------------------------------------------------------------------------- > ------- > > > > ---------------------------------------------------------------------------- ----- > Technet Mail List provided as a free service by IPC using LISTSERV 1.8d > To unsubscribe, send a message to [log in to unmask] with following text in > the BODY (NOT the subject field): SIGNOFF Technet > To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL > Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives > Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional > information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 > ---------------------------------------------------------------------------- ----- ---------------------------------------------------------------------------- ----- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------- ----- --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------