From the SWA data sheet--"SWA is ideally suited for the removal of flux resides and many other cleaning applications that do not contain sensitive metals and substrates. Used for cleaning metals prior to plating operations to provide an extremely clean and slightly roughened surface, allowing excellent bonding of the plated material."
From the SWAS data sheet--"SWAS is ideally suited for the removal of very stubborn flux resides and no-clean fluxes, which can be extremely difficult to remove."
Based on the data sheet information, it appears you are using a far more aggressive cleaning solution than you need to. Water soluble fluxes clean off much easier than no-clean fluxes do. My guess would be that the Safewash is removing the gold plating.
We do a similar cleaning process for our water soluble fluxes after both SMT load and selective solder assembly steps. We use an ultrasonic tank filled with tap water and 1 ounce of cleaning agent per gallon. After 15-20 minutes in the ultrasonic tank at 35C the boards are rinsed by hand using DI water. The cleaning agent we use is from Omegasonics --> Omega Aqua Clean LPH. The flux we use in our selective solder process is Kester 2235.
Our process cleans water soluble flux very well if cleaned within 24 hours of the boards being processed. We have sent boards off for cleanliness testing per standards with passing results. It does not clean no-clean fluxes. Fresh water with cleaning agent needs to be put into ultrasonic tank every 2-4 days depending on volume of boards cleaned. I hope this information helps.
reply »