This is quite a common phenomenon and is due to the fact that your cleaning process is too good. Most cleaning processes leave a monolayer of organics over the solder joints, which give a certain amount of protection against oxidation. If the cleaning is too good, then this monolayer will not exist and, with the temperature of the last rinse, you will get a fine layer of oxidation which can appear blue or yellow, according to the conditions. It is nothing to worry about. Brian On 21/07/2014 17:29, Richard Krug wrote: > We have recently discovered some CCA's with a distinctive, transparent blue color on the solder joints. Viewed perpendicular to the solder joint surface, surface looks normal. The solder surface appears blue when viewed at an angle. I see no residues at up to 30x magnification. Boards were wave soldered using Sn63Pb37 solder with ORH1 flux, then in-line water washed with a low concentration of a saponifier as one of our common assembly processes. > > Any ideas of what the condition is or what caused it? > > Dick Krug, CSSBB, CSMTPE > Lead Process Engineer > Sparton Brooksville, LLC > 30167 Power Line Road > Brooksville, FL 34602-8299 > p (352) 540-4012 (Internal Ext. 2012) > [log in to unmask] > > ______________________________________________________________________ > This email has been scanned by the Symantec Email Security.cloud service. > For more information please contact helpdesk at x2960 or [log in to unmask] > ______________________________________________________________________ > ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________