So far as I can see a lot of conformal coating practices are done from fear
of stopping. So far as inspection and so on is concerned have you tried
polarised light - or is that too obvious a question?
Best Wishes
Mike
----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Lee Hitchens
Sent: Thursday, May 16, 2013 7:55 AM
To: [log in to unmask]
Subject: Re: [TN] Conformal Coating Question
Hello Dale
I would support both the responses so far. We have customers which we
must coat the edges for and its a real pain trying to do it with a
robot. So much so we do it by hand!
But, 99% of our customers don't care. Moisture penetration is a valid
point for sealing the edges if that is an issue for the laminate. I
guess adhesion is a key factor and and how well the coating adheres /
fills the voids and holes in the laminate on the edge as well. Its
another example of something that has been done for years in conformal
coating but the true reasons are lost in the annuls of time with many
engineers. Another factor I can throw in is that the majority of coating
in automotive electronics is robot sprayed, they generally don't coat
the edges and the automotive spec's and environment can be pretty harsh.
Finally, how do you intend to inspect? I am working on a project
inspecting cables for deep penetration of the coating to act as a
sealant and I can see you are going to have the same sort of problems we
have. Using black light blue lights gives you too many reflections to
see with the naked eye and an operator will go crazy trying to confirm
the coating is there. We use single wavelength LEDs and a camera now
which cuts out the white light factor but as you can guess its a real
problem.
Best Regards
Lee Hitchens
Technical Director
SCH Technologies is a Division of SCH Services Limited
Mob: +44 (0) 7862 25 33 21 www.conformalcoating.co.uk
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On 15/05/2013 20:08, Dale Ritzen wrote:
> Hello Technetters,
> Don't know if this has come up before or not (nothing in the archives),
but we are researching any conformal coating requirements specifying that
the edges - not just the surfaces - of the boards be covered. With the
emergence of automated coating equipment, i.e. moving away from the spray or
dunk coating processes, we are finding it hard to identify a coating machine
that can do board edges. So...
>
> 1. Is there a valid need to coat the board edges, or is this simply a
customer driven requirement? (I'm waiting for an "It depends..." on this
one.)
> 2. Are there any IPC standards that address this specific question?
J-STD-001E, section 10, covers coating to "all areas designated for coverage
on the assembly drawing/documentation", and does not specifically mention
board edges. I don't have copies of HDBK-830 or CC-830B for reference, so am
relying on your inputs and experience with this question. I would be glad to
do some reading up on this if anyone has any suggestions for white papers or
other documents that cover this (pun intended).
>
> We'd really like to understand what the industry-wide requirements are for
conformal coat in this regard. Might be a lost cause already as we have been
getting the boards sprayed for years, so the customer is used to seeing
every surface coated, including edges. But, the only spec they've quoted so
far is the old Mil-I-46058C which was removed from service back in the
1990's. After reading through it though, I don't find anything that
specifically addresses this question.
>
> Any feedback would be appreciated!
>
> Dale Ritzen, ASQ CQA
> Manager | Quality Group and ISO Management Representative
> _____________________________________________
> Austin Manufacturing Services
>
>
>
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