George -
Enthone calls is "copper creep". It is also referred to as copper
corrosion. Dave Hillman of Rockwell published on it.
http://www.smta.org/knowledge/proceedings_abstract.cfm?PROC_ID=1765
The HP paper was presented at ISFTA 2006:
(See attached file: S18_1.pdf)
Unfortunately, you've caught me on the road at the moment. I can send you
further docs and pics next week when I have access to the rest of my
material.
Thanks,
Cheryl Tulkoff
Senior Reliability Engineer
Phone:(512) 683-8586
Fax: (512) 683-8520
National Instruments
11500 N. Mopac Expressway
Building C
Austin, TX 78759-3504
"Wenger, George
M."
<George.Wenger@an To
drew.com> "TechNet E-Mail Forum"
<[log in to unmask]>, "Cheryl Tulkoff"
08/10/2007 07:30 <[log in to unmask]>
PM cc
Subject
RE: [TN] Silver PCB finish and
reliability (question)
Cheryl,
When you indicate a quick Google search on the topic, what topic are you
referring to? Copper creep is typically a thermal issue with copper
alloys and I'm not sure I've every seen it related to immersion silver
surface finish.
Regards,
George
George M. Wenger
Andrew Corporation Wireless Network Solutions
Senior Principal FMA / Reliability Engineer
40 Technology Drive, Warren, NJ 07059
(908) 546-4531 [Office] (732) 309-8964 [Cell]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Cheryl Tulkoff
Sent: Friday, August 10, 2007 6:30 PM
To: [log in to unmask]
Subject: Re: [TN] Silver PCB finish and reliability (question)
Carl -
Immersion silver is our finish of choice for most of our PCBs - both
leaded
and lead free. There is one known reliability issue referred to as
"copper
creep." In customer environments with high sulfur along with humidity
and
air flow, you can get catastrophic failures. This usually affects vias
or
other areas where there is no solder over the silver. Both Dell and HP
have
published on the topic and we have confirmed failures due to the problem
as
well. We have been working with the immersion silver finish suppliers on
potential improvements.
Industries like tire manufacture, water treatment, paper processing etc.
are likely candidates for problems.
You can do a quick google search on the topic. If you cannot locate the
papers, you can contact me for more details.
Cheryl Tulkoff
Senior Reliability Engineer
Phone:(512) 683-8586
Fax: (512) 683-8520
National Instruments
11500 N. Mopac Expressway
Building C
Austin, TX 78759-3504
Carl VanWormer
<[log in to unmask]>
Sent by: TechNet
To
<[log in to unmask]> [log in to unmask]
cc
08/10/2007 04:07
Subject
PM [TN] Silver PCB finish and
reliability (question)
Please respond to
TechNet E-Mail
Forum
<[log in to unmask]>
; Please respond
to
Carl VanWormer
<[log in to unmask]>
For non-BGA, surface mount boards, we have always ordered HASL boards.
In
our progress towards ROHS compliance, management has changed the default
specification to ENIG. Our board house has HASL, ENIG, and Silver as
options, with Silver at about the same price as HASL and ENIG with a
significant premium (along with a 2 to 3 days added to the processing
time). When I asked management why we couldn't use Silver, I was told
that
there are significant problems with the Silver processed boards (with no
real explanation).
My question to the Group: Is there any good reason to avoid Silver as a
surface finish on my consumer and industrial boards?
Your scary stories are welcomed . . .
Thanks,
Carl
Carl Van Wormer
Cipher Systems
1800 NW 169th Place, Suite B-100
Beaverton, OR 97006
Phone (503)-617-7447 extension 20
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