Why is no-clean flux causing failures?

No-clean causes failures when residues are:

• hygroscopic or ionically active and lead to leakage currents,

• mechanically unstable and trap contaminants under components,

• chemically altered during lead-free reflow to form white rosinates that reduce coating adhesion.

Field examples: leakage in high-voltage boards, intermittent ICT failures, and conformal coating delamination. Root cause teams should correlate residue maps to failure sites and consider targeted cleaning or alternate flux formulations.