Good point re CaCl2 used for deicing. As you probably know, in a former life I made the Microcontaminometer. With the smallest tank, it could measure down to picograms NaCl equivalent. I had some thoroughly cleaned samples, 1" x 1" ceramic hybrid wafers, on my bench for testing. Suddenly, they showed ionic contamination levels much higher than they should have, which puzzled me. I was pondering on this when I saw a salt (NaCl) sprinkler going along the road and light dawned. The tyres of cars passing kicked up an aerosol of slush and salt that presumably evaporated leaving a suspension of submicroscopic salt crystals that floated everywhere including into my lab, which was a good 20 m from the road (and the windows were shut!). This hypothesis was confirmed on a number of subsequent occasions. Similarly, I had a customer in Rennes at the foot of the Brittany peninsula, about 50 km from the coast. He told me that his PCBs showed consistently slightly higher ionic contamination readings when a violent north-westerly Atlantic storm was raging. However, tap water is the most probable source of Ca. I'm afraid that 1 ppm is meaningless as such unless we know the area from which the aliquot was derived. 1 ppm from a sample the size of an A4 paper sheet would be bugger all in terms of reliability but it may be a different story if the sample was a small passive component. Brian On 11.02.2014 00:08, Richard Kraszewski wrote: > I am occasionally seeing irritating low levels of calcium in some assemblies that we test via ion chromatography. > > Some organizations required spec levels as low as <1 ppm. > > My questions to you techies is: > > #1 Besides wash water are there any other sources of calcium that come to mind? > > #2 is there any real value in having Calcium specs down as low as 1 ppm? (I suspect not and this spec was merely carried over from the semiconductor industry where it may have more value) > > CH65 is of some help here in that is does speak much more of the evils of Na that Ca& Mg, but not as much as I had hoped. > > Thoughts?? > > Rich� Kraszewski > Senior Process Engineer > Plexus Engineering Solutions > > ______________________________________________________________________ > 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] ______________________________________________________________________