Alpha WS-819 water-soluble, Pb-free solder paste reportedly withstands 50% +/-15% humidity. Developed for Pb-free PCBs. Is said to provide long stencil life, reduced printing cycle time, voiding resistance, and water cleaning without saponifiers and special waste water treatment and disposal systems. Has been tested on Enthone OSP, Alpha immersion silver, and immersion tin and ENIG finishes.

Cookson Electronics, www.cooksonelectronics.com