Hello,

I am looking for some information either from experience or papers on
what causes brittle solder joints.  We have immersion gold over nickel
and use eutectic solder paste. Board material is high-temp FR4.   I
would like to know:

1.  How many heat cycles a solder joint will tolerate without becoming
brittle.  Is there a temp that a solder joint becomes brittle and the
crystalline structure changes (as in steel tempering)?
2.  What would be the definition of a heat cycle (would it be reaching
183 C or something else)?
3.  What is a safe temp to have boards at  during a stress testing..

any information or a contact to find information would be greatly
appreciated.
Thanks in advance for your help,

Christina Piasky ([log in to unmask])
Sequent Computer Systems

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