Bittele's Use of Flux in PCB Assembly No-Clean Flux vs. Water Soluble Flux
The purpose of flux is to help create strong solder joints by first cleaning the metal surfaces. Specifically, the goal of the flux is to remove any oxides of the metal surfaces that may interfere with the soldering process causing a poor solder joint to form.
Water Soluble Flux is a very aggressive cleaner and oxidizer. It is much more reactive than No-Clean Flux and is thus a stronger cleaner. Though this provides excellent soldering results it also has a downside. The flux residue from water-soluble flux is quite corrosive after soldering and needs to be completely removed, this is done by very thoroughly washing the boards with distilled water. Even slight residues can cause failures in the board over time due to their corrosive nature. Due to the high reactivity of Water Soluble Flux, even the equipment at Bittele is chemically attacked, and thus regular machine maintenance is very important.
No-Clean Flux actually means that the amount of residue left behind is negligible to the point where there is no need for it to be cleaned. Thus it is in fact just very low residue flux that does not require cleaning in most cases. However, in certain cases, even this low residue flux must be cleaned. For example, when doing through-hole soldering Bittele will always clean the flux that remains from this process. To clean this No-Clean Flux residue Bittele uses a flux remover cleaning agent. Though No-Clean Flux allows for very good soldering it is not at the same level as Water Soluble Flux, but it also does not carry the same risks as the Water Soluble Flux does.
Bittele’s standard is to use No-Clean Flux, however, we can accommodate Water Soluble Flux requests as well. If you would like your assembly to be done with Water Soluble Flux please let us know if your ‘request for quote’ (RFQ) email to us, or mention it in your assembly specifications.