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
>>
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