You're welcome.
In thinking about this a little more, the only specification that I have
seen that touches on calcium is in IPC-5704, the bare board cleanliness
spec that is based on Delco's Q-7000 bare board specification. In that
spec, they list that the combined sodium and potassium content has to be
less than 2 ug/cm2 for non-OSP boards and 4 ug/cm2 for OSP boards. It
lists a maximum for total inorganic at 3.8 and 5.9 respectively for
non-OSP/OSP boards. So if you had high calcium, you might go over the
total inorganic. But I know that those values were based on Wittmers (et
al) work where the cations were treated as process indicators.
That brings up a question Rich, are these OSP boards that show the high
calcium?
Doug Pauls
From: "Stadem, Richard D." <[log in to unmask]>
To: <[log in to unmask]>
Date: 02/11/2014 01:53 PM
Subject: Re: [TN] Risks Associated with Calcium
Sent by: TechNet <[log in to unmask]>
Now that is a very useful post. Thanks, Doug!
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Douglas Pauls
Sent: Tuesday, February 11, 2014 1:30 PM
To: [log in to unmask]
Subject: Re: [TN] Risks Associated with Calcium
Awwww, it was much more fun being surreal.
Rich, I cannot recall a single instance where calcium, or even high levels
of calcium had any impact on reliability. Calcium, potassium, magnesium
are all pretty benign. It is the anions that seem to be the root cause of
many of the electrochemical failures seen in the industry, so that is
where all the research has been focused. Phil Wittmer and some of his
colleagues at Delco Electronics (now Delphi) published papers years ago
where they treated cations as process indicators. If you saw high levels
of potassium, sodium or ammonium, you likely had problems with the
cleaning of your solder mask developing and cleaning materials. The
residues from those chemicals, manifest as high levels of the cations,
were causes of problems. They could also indicate a problem with solder
mask degree of cure, which I alluded to before. If an incompletely cured
solder mask is exposed to other plating solutions or flux, then those
chemicals may be absorbed into the solder mask and not be found by
conventional ionic contamination testing. Long story short, I treat it as
a process indicator, not as a harmful material.
What I would recommend it to take some of the bare boards for the
assemblies in question. If they exhibit high levels of calcium in the
bare board, before they even touch your processses, then you have a bare
board issue. If the calcium is low, then do testing throughout your
process to find where the calcium jumps up in level. That is always the
process that I used at CSL. I would guess Eric Camden would say the same.
Simple sound science. Track back till you find the course.
Doug Pauls
From: Richard Kraszewski <[log in to unmask]>
To: <[log in to unmask]>
Date: 02/11/2014 11:40 AM
Subject: Re: [TN] Risks Associated with Calcium
Sent by: TechNet <[log in to unmask]>
OK then....
Thanks for the replies. Even the ones that turned this into a more
surreal experience than even I typically expect to have on any given
workday.
My list of more bland replies (albeit it begrudgingly useful) both on and
off forum include the following:
#1 CaCl2 from deicing compounds.
#2 Calcium from factory humidification misters
#3 Talc from powdered gloves
#4 E-glass in the laminate
#5 filler in the solder mask
#6 DI water
The above list is useful from a source stand point, however am still
struggling with the effects that could be seen with low levels of Ca (i.e.
<1-2 ugm/inch). I suspect none if any.
Studies conducted by the Minzari in Denmark suggests that calcium warrants
limited concerns as only Sn, Pb, Cu and Ag present sizable ECM risk.
(IEEE, volume 9, Sept 2009).
I have a suspicion that any requirements for low levels of calcium on
assemblies have been propagated from those used in the semiconductor
industry. While those may be required in semiconductor world, they may not
have good applicability in the realm of PCA manufacture.
Any further thoughts on "RISKS" associated with low levels of calcium?
Rich Kraszewski
PLEXUS
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Tuesday, February 11, 2014 9:15 AM
To: [log in to unmask]
Subject: Re: [TN] Risks Associated with Calcium
Hi Steve,
You hit the nail on the head!!
http://www.youtube.com/watch?v=KX9mBaHtTrs
Steve
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steven Creswick
Sent: Tuesday, February 11, 2014 7:22 AM
To: [log in to unmask]
Subject: Re: [TN] Risks Associated with Calcium
Doug,
Don't overlook that which is right in front of your co-ops face!
Please remember that a cow's tongue is long enough, and flexible enough to
reach inside its nostrils and extricate whatever may be resident there.
Certainly, at this time of year there may be significant 'thickening
agents' and moisture present.
Just thought you would like to know for testing!
Steve Creswick
Sr Associate - Balanced Enterprise Solutions
http://www.linkedin.com/in/stevencreswick
616 834 1883
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