F-SW22 vs F-SW33 flux. What to these figures mean?
F-SW-22 is weakly corrosive and contains inorganic salts.

F-SW-33 is non-corrosive and is rosin free w/o halides.

You'd use F-SW-22 if there was solder-ability issues, but you must clean the board after wards.

You'd use F-SW-33 for a normal (cleaner) situation, and is advertised as no-clean .  I'd recommend you clean it anyways.