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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