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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