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
---------------------------------------------------------------------------------
|
