Hello Paul

For a lot of chemical tests its not just about the coating material but
about the coating coverage too. Thin edge coverage where the coating pulls
away from the sharp corners of components etc has a very large influence
on the chemical effects. After all, if you don¹t coat the device well it
leaves ³holes² in the coating where the gases can attack. This is why
parylene or vapour deposition coatings can be superior in this regard as
they are homogeneous when applied. Liquid coatings are rarely homogeneous
due to surface tension effects.


Take a look at the coating method you are going to use. I can send you
some more links on this topic off line if you need help.


Best Regards

Dr Lee Hitchens
SCH Technologies 





On 30/07/2014 20:24, "Paul Jackson" <[log in to unmask]>
wrote:

>Jeffrey,
>
>I don't believe this is the material they tested. I will pass it along.
>
>thanks,
>Paul_<http://www.omnicircuitboards.com/>_
>
>On 7/30/14 12:03 PM, McGlaughlin, Jeffrey A wrote:
>> Have they looked into Parylene (poly-paraxylylene) coating. The coating
>>is thin mechanic lay and thermally stable and will withstand  exposure
>>to most chemicals including Hydrofluoric Acid.
>>
>>
>> Jeffrey McGlaughlin, C.I.D.
>> Engineering Designer
>>
>> Battelle
>> 505 King Avenue
>> Columbus Ohio 43201-2693
>> [log in to unmask]
>>
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>> -----Original Message-----
>> From: TechNet [mailto:[log in to unmask]] On Behalf Of Paul Jackson
>> Sent: Wednesday, July 30, 2014 12:48 PM
>> To: [log in to unmask]
>> Subject: [TN] Conformal coating for Sulfur environments
>>
>> We have a customer whose PCBAs are subjected to flower of sulfur rich
>> environments. The sulfur quickly corrodes any area not covered in
>> soldermask. They would like to use a conformal coating but their
>> research to-date has only come up with one solution which has published
>> data specifically concerning sulfur and the coating is too viscous for
>> their application.
>>
>> Does anyone have experience with a conformal coating which is proven to
>> survive in an environment with sulfur?
>>
>> Any help would be greatly appreciated.
>>
>> Thanks,
>>
>> Paul
>> Omni Circuit Boards
>>
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