In the bad old days, I'dve simply flooded the item
with Freon TF, but
that's a no-no now. Same for carbon tet. What do you folks use when
something more aggressive than air is called for?
Propan-2-ol (isopropanol, isopropyl alcohol). You can get spray cans of
it in the UK. Spray it on the board (oe whatever), then brush.
It's safe on most things (I seem to remember it's a bad idea on some
optical plastics, though). Certainly OK on PCBs, IC packages, etc.
-tony