wrote in message
ups.com...
I don't do much soldering (obviously) but which is better and is less
prone to cracking in the future? The newer Lead-free rosin core or the
63/37 tin/lead rosin core? A store in my town only stocks these two.
This for a small circuit board repair project.

Also, What can I use to cleanup the dried-up rosin residue on the PCB?

Thanks


Phillip -

NEVER use acid core solder on electronic circuits (or kiss that appliance /
project goodbye).

63 / 37 is the Eutectic of Tin and Lead metals.
Eutectic is an English word that comes from the Greek 'eutektos', meaning
'easily melted.'

The lowest temperature at which a mix of two materials will melt.
Often the temperature is an anomaly, that is, it is much lower than the
melting temperatures of only slightly different mixtures. Lead-tin solder is
an example. Lead melts at 327 C, tin at 231 C.
The lowest melting combination is 67 lead, 33 tin ( 180 C ).

Non-eutectic mixtures have a melting or softening (plastic) range. Such
mixtures do not flow well until thoroughly heated past the softening
(plastic) range. Kester solder Alloy temperature chart
http://www.kester.com/en-us/technical/alloy.aspx

g. beat