Doug,

You might consider looking into use of an autoclave.  Autoclave testing will
separate the wheat from the chaff within hours as far as CC integrity.  

JESD22-A102 has test conditions ranging from 24-336hrs at 121°C, 15 psig

Most polymers will 'discombobulate' within the first 24 hrs [96 hrs is
somewhat difficult to get to].  It is a brutal test!

You will pick up differences between materials [depending on test duration]
within hours, but one is still left to justify the correlation between
'steamy hot' and 'clammy cold'.

I keep an autoclave in the basement for those 'special occasions'!

Steve C



-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Douglas Pauls
Sent: Friday, February 10, 2012 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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