As the circuit on the PCB will begin to oxidize within some ten minutes, if protection has not been adopted, oxidation will serious spoil the solderability when the soldering  process  take place in the assembling factories.

# CR712 PCB Pre-Flux is a Low solids rosin/resin based surface’s preservative that will protect and maintains solderability of single-sided, through-holes and surface mount PCB copper pads. PCBs coated with CR712 when exit from the drying stage will be non-tacky and the surface’s glossy in appearance. Cosmetically, the PCB’s surface will look very clean with minimal residue. This copper protectant coating are compatible with rosin/resin and no-clean type of wave-soldering fluxes. OSP replacement, No rinse is needed.