Dave,
No apologies are necessary. The amount of ignorance in the area of
conformal coating (or materials in general) is staggering, more so the
farther you get from the field. I think your work was valuable to show
what real end use environments were, as opposed to the tests we used to
simulate them.
We are now working on the A revision to the Conformal Coating Handbook,
with much more manufacturing information being put into it.
Doug Pauls
David Douthit <[log in to unmask]>
10/22/2010 04:42 PM
To
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
cc
Subject
Re: [TN] Conformal Coating Board Edges
Doug,
| am offering my apologies to members of this forum for my actions while
dealing with "coating" issues.
The only excuse | can give is very high level of frustration | developed
while trying to gain information and resolve
difficulties with the attitudes surrounding coatings in general (A lot of
if the unit makes it past warranty so what).
Coatings can greatly improve the operational efficiency of hardware if the
limitations and characteristics of the coating material is understood.
Unfortunately these issues can be overlooked during design, manufacturing,
and field operations of equipment.
This results in abnormal operational events that can rank a close second
to solder joint problems in "harsh environments".
Because testing of hardware in simulated end use environments is difficult
(if not impossible), expensive, and time consuming
it is difficult to raise the issue with much hope of a positive response.
The |PC "stepped up to the plate" and created the "Conformal Coatings
Handbook" which has clarified and addressed many of the issues | had.
For that | want thank the |PC and all the members of that committee for
the long hours and hard work (plus putting up with me) that went into
and continues to go into that document. |t was a real balm that helped
"ease a tortured soul".
David A. Douthit
On Oct 22, 2010, at 7:26 AM, Douglas Pauls wrote:
Yes, I remember Dave Douthit. I did not always agree with his approaches
to things, but he did have some interesting data.
The indoor NH3 is not that hard to fathom. Most of your industrial
cleaning solutions, especially for glass, have some ammonia in it, so PPB
levels of NH3 are not unusual. If you are anywhere in the Midwest in the
United States, anywhere from April to June, farmers are planting fields
and most apply anhydrous ammonia during the process. I am betting Iowa is
a whole lot higher in NH3 during that time than the PPB range.
Doug Pauls
Inge <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
10/21/2010 04:51 PM
Please respond to
Inge <[log in to unmask]>
To
[log in to unmask]
cc
Subject
Re: [TN] Conformal Coating Board Edges
"Second, how do you determine how harsh an environment has to be in order
to coat the edges? "
Dough Pauls
Answer:
Do you remember David Douthit? His definition of Harsh was environments
that belong to the upper range of the values in the 'OUTDOOR' column. His
work. There exist no true formulas, but the values below shall in
principle be multiplied with Temperature, Time, barometric pressure and
local weather conditions (sun radiation for example). We have in principle
followed similar figures.
Concentration of selected gaseous air constituents (ppb) in the United
States.
OUTDOOR
O3 4-43
H2O2 10-30
SO2 1-65
H2S 0.7-24
NO2 9-78
HNO3 1-10
NH3 7-16
HCL 0.18-3
CL2 0.005-0.08
HCHO 4-15
HCOOH 4-20
INDOOR
O3 3-30
H2O2 5
SO2 0.3-14
H2S 0.1-0.7
NO2 1-29
HNO3 3
NH3 13-259
HCL 0.05-0.18
CL2 0.001-0.005
HCHO 10
HCOOH 20
There is one thing I don't understand: NH3 up to 259 ppb indoor.
Hope this gave you at least an idea.
/Inge
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