one more question,
Is it true that no-clean solder is more hazardous than Rosin core solder ?
nope in short it depend... on manufacturer of flux and activators in it , if you want non irritant flux focus on syntetic flux like amtech lf-4300 or syntech based such as syntech-tf or syntech-lf-tf for lead free solder only these are syntetic fluxes
all other fluxes are usually irritant especially rosin based RMA but there is also one syntetic flux manufacturer Alpha OM-338 and this flux is the whorst hell irritant product which i ever tryin ! but it is syntetic
all other amtech water washable flux like lf-4200 etc. they are syntetic too and should not irritate but water washable flux is not recommended to solder bga even i think it must be cleaned after smd soldering process
syntech products are no-clean not water washable and they are very good for bga reballing etc. syntetic made smell nice and not irritate , it is same product as chip quik flux just manufactured by amtech
if you wanna solder lead-free only choose SYNTECH-LF-TF if leadded only SYNTECH-TF
classic rosin flux does not require cleaning
not exactly coz if you have rosin flux with REM1 speciffication you must clean it after soldering process mostly rma flux need cleaning anyways i dont understand why some people using rma flux for bga placement instead of using no-clean type