This tangent on cow saliva got me wondering whether there's a Bizzaro TechNet where we all have bovine alter-egos. E.g.: Mike Buecow Joyce Moo Doug Paulstein Dave Hillstein Brahman Ellis Anyway... Mike -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Douglas Pauls Sent: Tuesday, February 11, 2014 9:11 AM To: [log in to unmask] Subject: Re: [TN] Risks Associated with Calcium I have to print this one out and frame it. I think Brian and I have stumbled across Plexus's secret cleaning process - cows licking the electronics. Low cost, the rough tongue represents mechanical removal. Not sure what the surface tension of cow saliva is. I can just imagine the look on my co-ops face when I tell her to go research that...... Doug Pauls From: Brian Ellis <[log in to unmask]> To: TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask] Date: 02/11/2014 07:43 AM Subject: Re: [TN] Risks Associated with Calcium I bow to Doug's superior but cheesy knowledge (buttering him up!). However, in dairy farming regions, the cow lick is a dangerous source of sodium contamination. A cow's tongue is like a rasp and she must liberate a fine lick powder when using one. In a high wind, this powder would travel at a good lick, onto everyone's PCBs. An ionic tester could cream off the salt deposits. Brian On 11.02.2014 15:17, Douglas Pauls wrote: > Brian raises some excellent points, but I must disagree that the most > likely source of calcium is the tap water. > > Rich works up in Wisconsin (Up Nort). Wisconsin is a dairy state and cows > are everywhere. Using Brian's submicroscopic theory, your calcium is > coming from when cows walk by the plant. Perfectly logical. You have > a Holstein Crisis. > > Your second most likely source of calcium could either be from tap water, > or it could be coming from your solder mask. Many masks have a > certain amount of calcium as a filler compound. Elevated levels of > calcium in your extract solutions may mean the solder mask is not > fully cured or that > it is chemically degrading, allowing the filler material to leech out. > > Doug Pauls > > > > From: Brian Ellis <[log in to unmask]> > To: <[log in to unmask]> > Date: 02/11/2014 01:57 AM > Subject: Re: [TN] Risks Associated with Calcium > Sent by: TechNet <[log in to unmask]> > > > > 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] > ______________________________________________________________________ > > > > > ______________________________________________________________________ > 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] ______________________________________________________________________ ______________________________________________________________________ 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] ______________________________________________________________________