Hi Rikard:

Your experience is very much like mine prior to using liquid flux on solder 
wick.  I don't buy the chemical action explanation, but rather the thermal 
conductivity explanation.
Google "solder flux boiling point melting" and what you will find is a slew of 
patents for fluxes that boil at temperatures higher than solder melts.

That way you have a liquid that can make intimate contact with about anything 
and transfer the heat.  Putting an air gap in a thermal path really cuts down 
the heat flow.

For a per fluxed solder wick to work it would need a lot of flux powder and 
small wire diameters to the air space the flux needs to fill is small.  When 
using liquid flux the wire size is not as important (i.e. the cheap wicks work 
great).

-- 
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.precisionclock.com

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