Elina

In LEADFREE we soldered  SnAgCu with 245 C but this was the absolute
bottom line. At 240 C the solder wasn't really liquid anymore.
In my opinion, even 250 C is hot enough to solder SnAgCu. A result we
confirmed with several boards producing wonderful solder joints.
However, 250 C is the temperature of the wave. We had one project
partner having a temperature difference of 20 C between solderpot-
temperature (display) and wave temperature.
Soldering above 260 C gave lots of bridges due to decomposition of the
flux in the first wave.
Several project partners reduced now their superheat in the SnPb wave
to 50 C due to the results with SnAgCu and are quite happy (at least I
didn't hear anything else so far).
Thus I assume 70 C superheat is too much. Also for SnPb.



Best regards

Guenter



EMPA
Swiss Federal Laboratories  for Materials Testing and Research
Centre for Reliability
Guenter Grossmann,  Senior Engineer

8600 Duebendorf
Switzerland

Phone: xx41 1 823 4279
Fax :     xx41 1 823 4054
mail:     [log in to unmask]

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