Hello folks,

We have a project where the customer had a problem with ants getting into
and onto the circuit assembly mounted in a box, on a wall on the outside of
a house.

The Conformal coating material was able to provide all the protection they
required - formic acid - and was based upon a single component polyurethane
coating applied by means of dipping.

I have a complete article and photo's provided by the customer which I will
be happy to share with those interested, if you would please contact me off
line.

Regards, Graham Naisbitt

[log in to unmask]

Concoat Ltd             Phone: +44 1276 691100
Alasan House          Fax:      +44 1276 691227
Albany Park
CAMBERLEY
GU15 2PL UK

Any opinions expressed are those of this employer.

-----Original Message-----
From: Bernard Williams <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: 10 September 1998 23:47
Subject: [TN] Environmental testing - insects


>Clive:
>Yep, sounds strange but I came across the term  on a PCB testing facility's
>web pages (as part of a series of tests on populated PCB boards). (They
didn't reply to my email)
>
>In any case we are concerned with ants/cockroaches blowing up our
>high voltage IGBT dpak devices and am looking for anyone with
experience/solutions.
>Termites in NZ aren't that big or hungry!
>
>We have a great example where an ant has been forever immortalised
>when climbing up this dpak device. It used the gate lead as a step for one
foot and that centre drain "stub"  as a step for another foot.  It's frozen
dead (not vapourised) and so is the device!
>Seems enough charge went through the ant to raise the gate voltage and put
the IGBT
>into its linear region with consequent overheating and failure.
>
>Potting would be a solution but it is expensive.
>Conformal coat doesn't really work, it isn't very rugged,
>especially over sharp points.
>
>Perhaps noone really worries too much about this sort of thing but if
>anyone has experience in this area it would be great to hear from you.
>
>Bernard Williams
>(Electronic Engineer)
>_________________________________
>Fisher & Paykel
>Laundry Division
>78 Springs Rd., East Tamaki, Auckland.
>PO Box 58-732, Greenmount, Auckland.
>
>Tel: (09) 273-0640  ext.6695.
>Fax: (09) 273-0649
>Email: [log in to unmask]
>
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