There are many lead-free terminations out there now and lots of tin only
finishes and they are growing all the time.
The concern that some people have shown that as the ball does not become
liquid you will not get the same realignment and double drop experienced
with tin/lead and tin/lead balls. My gut feel is that this should not be
a problem in terms of joint reliability it may be an issue if the
process needs the realignment and the ability of coplanairity correction
that we have benefited from in the past.
NPL are currently finalising a project on the issue of tin/lead and
lead-free parts to look at reliability and what I consider more of a
concern the secondary reflow that may occur on wave, double sided reflow
and rework when using tin/lead parts with lead-free solder. In this case
we can suffer with intermittent joints that we will have problems
getting out of the factory.
There are five slides on a little project of mine which I will be
discussing at the IPC Conference next week, hopefully in the sunshine of
San Jose!!!
See the slide link www.bobwillis.co.uk/pdf/secondary.pdf
Bob Willis
2 Fourth Ave, Chelmsford,
Essex, CM1 4HA, England
Email: [log in to unmask]
Web: www.leadfreesoldering.com
Web: www.bobwillis.co.uk
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Marsico, James
Sent: 11 March 2004 20:28
To: [log in to unmask]
Subject: [LF] lead-free components with PbSn process
Good Day All:
I've posted a similar question on technet, but I thought this forum
would be
more appropriate.
What are the problems, if any, with using lead-free components with a
PbSn
SMT process? Are there any compatibility issues? How about long-term
reliability for military products?
Also, is anyone concerned with the influx of components with pure tin
finishes with regard to tin whiskers?
One more thing... are there concerns that "custom" components,
specified
with a PbSn finish, might become extinct (DMS, diminishing manufacturing
source)?
Thanks for your advice,
Jim Marsico
Senior Engineer
Production Engineering
EDO Electronics Systems Group
[log in to unmask] <mailto:[log in to unmask]>
631-595-5879
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