Steve

The conformal coating is a surface finish - so is paint. Would you paint a
dirty surface?

No-clean does not mean no residue. You would be well advised to run
accelerated life testing of the end product at the conditions the assembly
will have to endure viz: Temperature, humidity extremes and any other
nasties it may encounter. Take a good look at  IPC-CC-830 for more detail
and figure the class of your product to determine the test regime.

It should not be necessary to do X sections. A true conformal coating should
not impart stress or contribute to CTE mismatches between component,
component leg, solder joint and solder pad and board.

Consider the film thickness that SHOULD be applied. I am taking a wild guess
that this product may be in aerosol. If so, bear-in-mind that aerosols
contain typically less than 5% solids (coating). To coat correctly at around
2 to 3 mils per side on the flat land area (2 to 3 times more than that for
the fillets around the components) you would probably require around 1
aerosol to maybe 2 or 3 assemblies that are around 6 x 6 inches.

To measure thickness, measure a flat coupon before and after using a
micrometer making sure the coating is dry first! Coat the coupon along with
the assemblies.

If you are going to dip coat (best) then immerse at less than 12 inches per
minute and withdraw at less than around 4 to 6 inches per minute. This
should give you coating to the desired film thickness in one pass, both
sides and under the components.

If you would like a little more, take a look at my web site given below and
call me off line.

Regards,
Graham Naisbitt

[log in to unmask]

WEB: http://www.concoat.co.uk

CONCOAT Ltd
Alasan House, Albany Park
CAMBERLEY GU15 2PL UK

Tel: +44 (0) 1276 691100  Fax: +44 (0) 1276 691227
----- Original Message -----
From: Steve Collins <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, May 18, 2000 3:07 PM
Subject: [TN] Conformal Coating newbie


>
>
> We are about to embark on our first use of a conformal coating and I have
been
> ask to check out a few things.
>
> The material we will be using is Konform


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âUR. My first question is how does this
material respond to a no-clean process.
With this material should we do some crossections of the solder joints after
the
conformal coating has dried to check the solder joints from stress.

Anyone with any ideas on this coating that wishes to contribute inf. it will
be
gladly accepted.

Steve Collins

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