Cleaning lead-free flux residue
Challenges with lead-free flux
Lead-free assemblies typically use higher reflow temperatures and fluxes containing stronger activators. Challenges include:
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more tenacious residues, especially from no-clean lead-free fluxes;
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increased risk of corrosion if residues are ionic and hygroscopic;
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sensitivity of silver, copper, and mixed finish systems.
ZESTRON recommends early testing when changing to lead-free alloys.
Effective cleaning approaches
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use alkaline aqueous cleaners with corrosion inhibitors and chelants;
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apply ultrasonic or megasonic energy for dense assemblies;
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optimize rinse quality to prevent redeposition and white residues;
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validate with conformal coating adhesion tests if coating follows cleaning.
ZESTRON provides validated chemistries proven on lead-free process lines and offers failure mode analysis when issues occur.