Thanks Werner,
The reflow temperature measured at the lead I/F is 215C. These boards have
been built for the last 2 years without this problem but now there is.
If the joints are rerun with a soldering iron the problem goes away but this
is a cumbersome, non value added activity which I am trying to address.
I am considering having the failed joints analysed by one of the
universities that specialise in Auger / SIM microscopy.
Regarding your last comment, if the lead / foot wasn't solderable at all
would you expect the formation of a joint ie. a nice meniscus as we have,
though obviously a weak metallurgical bond I wouldn't have thought so!
Regards,
Iain.
-----Original Message-----
From: Werner Engelmaier [mailto:[log in to unmask]]
Sent: 08 April 2004 13:05
To: [log in to unmask]
Subject: Re: [TN] Strange phenomenon!
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Hi Iain,
Remember, that what you are soldering to in Alloy 42 is the 42% nickel in
it.
As such you need to raise the reflow temperature some 15 to 20°C over what
is
needed for Cu.
Also, there occasionally apppears Allloy 42 that is not solderable at
all; thus, your gullwing feet are simply encased in solder without any
metallurgical bond.
Regards,
Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL 32174 USA
Phone: 386-437-8747, Fax: 386-437-8737
E-mail: [log in to unmask], Website: www.engelmaier.com
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