Hi Joyce - well, I haven't done that but if you set the chamber for 0C and
85RH, you do get snow.
Dave Hillman
Rockwell Collins
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Joyce Koo <[log in to unmask]>
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02/13/2012 03:42 PM
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Re: [TN] Conf Coating in Cold and Clammy
I thought 10C/85RH will rain in the chamber.
Joyce Koo
Materials Researcher - Materials Interconnect Lab
Research In Motion Limited
Office: (519) 888-7465 79945
Mobile: (226) 220-4760
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Chris Mahanna
Sent: Monday, February 13, 2012 4:24 PM
To: [log in to unmask]
Subject: Re: [TN] Conf Coating in Cold and Clammy
Very interesting...
Here's what I would try:
Prove you can stabilize 10C/85 RH chamber (this might not be easy)
Bond a thermoelectric chiller to the back of a comb pattern
Bond a thermistor to the surface near the comb pattern (by the guard
maybe?)
Coat and cure.
Using the thermistor as the feedback control for the chiller, cyclically
drive the comb surface to ~7.5C (allowing light condensation), then let it
warm and the condensate evaporate (or absorb) to complete the cycle.
I'd guess that with reasonable airflow you could get several cycles an
hour.
Not the kind of thing you can scale up to dozens of samples, but 10 might
be doable in a single chamber.
Chris
Chris Mahanna
Robisan Lab
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Douglas Pauls
Sent: 2012/02/10 4:42 PM
To: [log in to unmask]
Subject: [TN] Conf Coating in Cold and Clammy
Good afternoon all,
Recognizing that asking a question of this group late on a Friday
afternoon is questionable judgement on my part, I will give it a shot
anyway.
I am in the midst of the most perplexing material investigation of my
life. Provided I do not get shot, hung or tarred/feathered, I will have
some neat stuff to publish in the next few years. I have a general
question on testing coatings, other than what you might do in aerospace.
Most temperature-humidity tests done on conformal coating are of the
cyclical variety, 25C to 65C, 90% RH for a week. This one is found in
MIL-I-46058 and IPC-CC-830 and is used for material qualification. Nothing
unusual there.
There are cyclical temperature-humidity test that are done as part of
product qualification, such as DO-160E or MIL-STD-883. But these are also
of the cyclical variety and 25C to 65C is common there as well. Nothing
unusual there.
How would one simulate a coated assembly, stored in a cold and clammy
environment (40-50F, 85-100% RH with probable dew points each day) for
months at a time, then powered up?
Are there any tests done in your industry that tests a coatings resistance
to a prolonged cold and clammy conditions? Ideally with some form of
acceleration factor? I know that the automotive industry has something
called a "damp heat" kind of test, but have no experience with that.
I know I can program my humidity chamber for an environment, but don't
really have time to let it sit 3-6 months. It has been suggested that I
jump in my time machine and go back 6 months and I would be done by now,
but my flux capacitor went through our Kyzen cleaning process and has no
flux left. I blame Hillman.
So, any thoughts would be appreciated.
Doug Pauls
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