Hi Randy,

The discoloration you see is most likely caused by impurities (organic
co-deposits) present in the matte-tin outer layer.  Assuming you reflowed
these parts above the 232 deg. C. melting point of tin, these co-deposits
would migrate to the surface.  You may find that this yellowish outer
coating is easily removed either mechanically or chemically, and does not
inhibit solderability.  A cross-section comparison between a non-reflowed
part and the reflowed part should reveal if this is your root cause.
Tighter control over the tin plating process should prevent this issue.

Good Luck,

Howard A. Cyker
Senior Manufacturing Engineer
SynQor, Inc.
E-mail:  [log in to unmask]


-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of R Buchter
Sent: Tuesday, May 31, 2005 5:24 PM
To: [log in to unmask]
Subject: Re: [LF] PN's changing

Hello All,

We have encountered a concern with a lead free stamped part. It is
stainless
steel base metal with 1.27micrometers minimum nickel underplate and 2.54
micrometers minimum matte tin overplate. The plastic is LCP.

After reflow, the matte tin has a yellowish color.

What could this be and how can it be avoided? Is high solder temperature
causing this? Does the stainless steel have something to do with it, as
copper alloy contacts with similar platings do not appear to have this?
Is
the LCP a factor?

Thanks in advance!

Best Regards,

Randy Buchter
Product Design Manager
Ranoda Electronics

------------------------------------------------------------------------
-------Leadfee Mail List provided as a 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 Leadfree
To temporarily stop/(start) delivery of Leadree for vacation breaks
send: SET Leadfree NOMAIL/(MAIL)
Search previous postings at: http://listserv.ipc.org/archives
Please visit IPC web site
http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100
ext.2815

------------------------------------------------------------------------------------------------


This message is for the designated recipient only and may
contain privileged, proprietary, or otherwise private information.
If you have received it in error, please notify the sender
immediately and delete the original.  Any unauthorized use of
this email is prohibited.
------------------------------------------------------------------------------------------------


[mf2]

-------------------------------------------------------------------------------Leadfee Mail List provided as a 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 Leadfree
To temporarily stop/(start) delivery of Leadree for vacation breaks send: SET Leadfree NOMAIL/(MAIL)
Search previous postings at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-------------------------------------------------------------------------------