What is defluxing?
Defluxing removes soldering flux residue from printed circuit boards and electronic assemblies after reflow or wave soldering. Left in place, rosin and activator residues attract moisture, cause surface leakage between conductors, and can drive electrochemical migration and eventual failure.
Flux does a necessary job during soldering — it strips oxide so solder wets the pad — but what remains afterwards is an acidic, hygroscopic residue sitting between fine-pitch conductors.
Modern no-clean fluxes are formulated so the residue is benign and can be left. That assumption breaks down under conformal coating, in high-humidity environments, in high-voltage designs, and wherever the assembly must pass ionic-contamination testing.
Defluxing chemistry is chosen against the flux type — rosin, water-soluble or no-clean — and against material compatibility, since aggressive cleaners can attack component markings, plastics and adhesives.
