See below

-----Original Message-----
From: [log in to unmask] [mailto:[log in to unmask]]
Sent: February 26, 2001 5:41 PM
To: TechNet E-Mail Forum.; Bev Christian
Cc: @mhs99ykf.rim.net
Subject: Re: [TN] Contamination by Fire Combustion Products and J-STD-001
rev.B



Contamination by Fire Combustion Products.

I order to get around the problem of appropriate standards we conducted a
survey of 4 computer rooms, carefully selecting four surfaces, two
horizontal, two vertical. When the surfaces are matched and anion
concentrations compared we are unable to distinguish the room with the fire.
It turns out to be the second cleanest room of the four. (It was a very
small fire).
So - where to with future reliability of the boards?
[Bev Christian] Then I would say leave the boards alone.  There is no
problem.

I cannot pick a standard without justification.
The ANSI J-STD-001B has been inappropriately cited by the restoration
company (beginning with Re....) as the qualifying standard - and the
equipment manufacturers have used this standard to disqualifiy equipment
based on the chloride content of WIPES taken from the EXTERNAL  surfaces of
the equipment enclosures! - Beggers belief.
[Bev Christian] Yes, it is unbelievable that they would chose this as their
"standard" and even more bizarre to apply it (Omega meter-type results) to
metal enclosures.  I do not remember them doing this before.

One "large OEM company"  :)  used IC cation/anion standards that were
gleaned from the CSL articles.  A single composite ionic contamination
measurement would NEVER be used to determine system cleanliness.  The only
reason wipe samples would be taken from the outside would be for comparison
purposes and attempting to determine a baseline. Certainly this would not be
used alone to determine whether the equipment inside was contaminated.

Was the smoke heavy or light, was the equipment sealed, did it have passive
air flow, where were the openings, were the fans running on an active
cooling system, what type of ventilation system did the room have?  All
these as well as type of fire, size and I think Doug Pauls mentioned type of
fire suppression unit would need to be asked in the case of a more severe
fire than the one you have described.

I have just received an IVF Research Publication - "Cleanliness and
Reliability: Evaluation of Test Methods and the Impact of Contamination from
the Production Process on the Reliability of Printed Circuit Board
Assemblies" where they state: "there is no clear correlation between the
results from the measurements (resistivity of solvent extract & ion
chromotography) and the reliability of the test product.

I recently spoke with a Melbourne based R&D lab who were investigating
intermittant failures of circuit boards. They discovered that the populated
boards were arriving with 20 to 30 micrograms of NaCl equivalent per sq inch
from the manufacturer but could not relate the failures to the ionic
contamination.
[Bev Christian] Doug?

What I need is some further documented experience on the reliability of
circuit boards (Like the publication above) to support or discount my "do
nothing" case.
Thank you all for providing telephone numbers for relevant contacts. I am in
Melbourne Australia - Could you please indicate in which country these kind
folk reside.
Timothy Cousins
http://www.timcousins.com.au