What is clean PCB assembly process?
It is processed with clean-needed solder paste composed by a type of Water Soluble Flux,which can provide excellent soldering performance. But with it’s flux residues left after soldering process is very sensitive and reactive to water so it is easy to corrode PCB board. Hence, it is necessary to completely remove the flux residues from water-soluble flux after soldering. This can be done by very thoroughly washing the PCB boards with distilled water.Due to it’s corrosive nature feature, even some slight residues can take the failures to the PCB board over time.

What is Non-clean PCB assembly process?
It is processed with no-Clean Flux.No-Clean Flux actually means that the flux residue left on the PCB board after soldering is no need be cleaned or removed. Therefore, in fact it is just very low residue flux that so it does not require cleaning in most PCB assembly cases.But, in some certain cases, even this low residue flux have to be cleaned. For example, if there is a through-hole soldering process at PCB assembly WELLER will always keep cleaning the flux that remains from this process. This is a basic process at Weller’s PCB assembly that to clean this No-Clean Flux residue . Though No-Clean Flux exists for very good soldering it is not at the same quality level as Water Soluble Flux, but it also does not take the same risks as the Water Soluble Flux does.