Those jobs that require a highly reactive flux, we use no-clean solder. These days, that would be repair work involving pin and hole. The residue is absolutely non-hydroscopic and it has been shown that statistically it does not promote the growth of tin whiskers (Or any other type of whisker...). You don't have to clean
Marvin Dickens wrote:
I'm a huge fan of water-soluble flux, and prefer it when doing SMT stuff. Of course, it's a little less reactive than rosin, so you need to really inspect your joints after soldering.
Regarding water soluable solders, take a look at:
http://www.tselectronic.com/solder/solder.html?tse_Session=87ad1697d9d7666613a61c09428f3791
Water soluable solder paste is also readily available. In fact, water soluable solder products are available in any form factor you can think of.
My only complaint, and it's a small one, is that you really do have to clean it off.
The flux is naturally hygroscopic and will, over time, increase its conductivity to the point of affecting the surrounding circuit. This is only a problem if you use the water-soluble flux on everything including prototype boards you might normally leave uncleaned. Fortunately, cleaning the flux off the board is such a trivial matter there's no real excuse for leaving the flux on.
I totally agree with you - it comes off so easily.
Best
Marvin