"Bi reduces melting point of the solder. Bi improves wettability. In the
presence of lead from HASL boards or components Bi can greatly reduce
thermal cycle fatigue resistance due to the formation of Sn16Pb32Bi52
(MP=95C) which can diffuse along the grain boundaries".
http://www.kester.com/en-us/leadfree/alloys.aspx

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Jack C. Olson
Sent: Wednesday, January 12, 2005 10:26 AM
To: [log in to unmask]
Subject: [TN] Soldering LeadFree components with SnPb


I have a question for the assembly folks out there; We just recieved
notification that one of our connectors is no longer available
with tin/lead plating contacts, and that they are now tin/bismuth.
I searched the last two years of Technet archives for the word
"bismuth" and only found this one comment with no other responses:
(there were other posts with "bismuth", but not relevant)

-=-=-
Some component lead-free finishes are not compatible with current
tin/lead assembly processing. Bismuth can weaken tin-lead solder joints.
Tin finishes should only be matte (no brighteners) or fully annealed
(low stress to ensure against tin whiskers that can ruin satellites and
cause fires).
Karl Sauter
Staff Engineer, Engineering Technologies
Sun Microsystems Inc.
-=-=-

We are NOT using a lead-free assembly process.
Someone give me some good news.... PLEASE!

Jack

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e
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 or (re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts 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
-----------------------------------------------------

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e
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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts 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
-----------------------------------------------------