Carrie,
First of all, the melting temperature for Sn is 232 C, not 217 C, which, however, doesn't make the situation you are asking about worse. During re-flow Sn isn't going to melt down be will be dissolved in the solder. That's how it usually "works". :-)
Regards,
Vladimir
Vladimir Igoshev, Ph. D.
Senior Materials Researcher
Research in Motion
451 Phillip St.
Waterloo, ON, N2L 3X2
Voice: (+1) 519-888-7465, ext. 5283
Fax: (+1) 519-886-0863
E-mail: [log in to unmask]
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]]On Behalf Of Morse, Carrie
Sent: Tuesday, November 01, 2005 3:19 PM
To: [log in to unmask]
Subject: [LF] Matte Tin Lead Finish in Good old SnPb Joints
OK, OK....Put the Guns Down....(especially if they have leaded bullets!)
I have a customer asking about the reliability of a solder joint that
would be made using a component finished in Matte Tin but, soldered
using SnPb.
His concern is that Tin has a melting point of 217C yet, most SnPb
process target a Max Temp of 210-225C.
Hasn't Tin been used for years on components? Has this always been an
issue? Or, is this new?
Is it an issue? Do we need to increase our profiles to be above 217C
for some period of time? If so, what IS that time and what IS that
temp?
Any metallurgists/process folks want to give their 5 cents worth
(yes...it's no longer 2 cents -- the price has gone up to keep in line
with the new cost of our new and improved solder pastes!)
TIA,
Carrie
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