Steve,
I have not used that specific material before, but have worked with 2-part 
systems.  A few questions and observations:

1.  What did you mix the material with?  Metal spatula (good) or popscicle 
stick (bad)? 
2.  How well did you scrape the sides of the container?  Was it a clean 
plastic mixing cup (good) or wax-coated Dixie cup (bad)?
3.  Did you bake out the potted assemblies first?
4.  Was there a primer involved? 
5.  What kinds of "schmutz" may be on the assembly that may poison the 
cure reaction?  Urethanes don't like water.
6.  Does the manufacturer recommend a rest time before potting?  Degassing 
before potting?

You might want to pick up IPC-HDBK-850, The Potting and Encapsulation 
Handbook for lots of good information.


Doug Pauls



From:   stephen gregory <[log in to unmask]>
To:     <[log in to unmask]>
Date:   07/22/2013 01:46 PM
Subject:        [TN] Epic Resins S7144A 2-part polyurethane potting 
material
Sent by:        TechNet <[log in to unmask]>



Hi All,
 
Have any of you used Epic Resins S7144A 2-part polyurethane potting 
material?
 
I tried to last week, and pretty much made a mess. Followed the datasheet 
and mixed it in the volume ratio of 3-parts part-A (300-cc) to 1-part 
part-B (100-cc). I mixed more material than I actually needed. I'm mixing 
it by hand because we don't have a MMD system. 
 
I thought I had mixed everything thoroughly (4-5 minutes). I determined 
ahead of time how much material would be needed for each unit (35-cc's). 
After mixing, I drew the material into a 60-cc syringe and 
dispensed 35-cc into each case. I let it room cure (24-30 hours).
 
I did 4-units and each one of them had a different result, from swelling 
and bubbling of the material completely out of the case, to little or no 
cure. I'm at a loss as to why that happened.
 
Just wondering if any of you have ever used the material and can give me 
some pointers.
 
Thanks guys,
 
Steve

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