Tackling QFNs: Cleaning techniques

QFNs have large thermal pads with very low standoff. Effective strategies:

• use solvent-based flux removers with surfactant boosters to improve wetting,

• apply vacuum-assisted cleaning or capillary flushing if board design permits,

• consider temporary coating or masking of sensitive areas during cleaning.

Measure success by microsectioning and SIR testing. ZESTRON’s process engineers often recommend combination chemistries for stubborn QFN residues.