Stencil Cleaning: Aqueous/Semi-aqueous & Flux Residue
Match the flux type and aperture geometry: aqueous/semi-aqueous emulsify and disperse, solvents dissolve — each with trade-offs.
1Residue type sets the route
Rosin/resin fluxes (R/RA/RMA) leave tacky hydrophobic residue needing saponification or solvent penetration; water-soluble residue rinses with neutral aqueous; no-clean leaves less but still affects conductivity. Residue inside aperture walls directly degrades subsequent paste transfer.
2Aqueous vs semi-aqueous vs solvent
Aqueous uses water as main solvent, emulsifying/dispersing insoluble residue into a rinsable state — green and safe but needs rinse and dry. Semi-aqueous adds co-solvent/penetrant to balance solvency and safety. Pure solvents (esp. halogenated) dissolve well and dry fast but are volatile; some are ODS-restricted.
3Cleaning method & acceptance
Automated stencil cleaning uses wet wipe + vacuum + dry wipe: wet removes paste, vacuum pulls residue from apertures, dry removes cleaner. Verify apertures are clear with no white residue, using ionic contamination (ROSE) and magnification when needed.