Modern HFE co-solvent cleaning processes are available options if short drying times and/or water-free cleaning is required. This is often utilized in the military and aerospace sectors. HFEs (hydrofluoroethers) were developed as replacements for CFCs or similar solvents exhibiting the following properties: nonflammable, non conductive, dries quickly and residue free.
Together with a co-solvent, the HFE is used in a cleaning bath with spray-under-immersion or ultrasonic agitation in order to dissolve persistent residues. The rinsing step takes place in a bath with HFE only and subsequently with steam rinsing. Finally, the PCBs are dried by intensive cooling. This process must be carried out in a cleaning machine with efficient cooling technology, preventing evaporation of the HFE.