Is chemistry necessary for cleaning no-clean lead-free materials?
Fernando: Most soldering and fluxing technologies developed today use no-clean technology. No-clean may or may not have to be cleaned with chemistry. Cleaning no-clean with chemistry could be due to reliability concerns, but it could also be a cosmetic issue. EMSNow: How about water soluble lead-free materials, is water good enough? Fernando: Water soluble materials have to be cleaned 100 percent because any remaining residues can become corrosive and damage the assembly, produce yield losses that can add significant cost to assemblies, and failing reliability requirements can cause significant profit losses as well as image deterioration of a company. There are several factors that make chemistry necessary for cleaning water soluble lead-free materials: higher reflow temperatures (bake-on residues), more aggressive fluxes, lower standoffs, tighter pitch and higher component density. All these factors require a much lower surface tension than the 72 dynes/cm that water has, thus making
