Thank you all for your answers.

Anyone has a picture of dendrites?

-----Original Message-----
From: [log in to unmask] [mailto:[log in to unmask]]
Sent: Thursday, March 21, 2002 2:44 PM
To: [log in to unmask]
Subject: Re: [TN] Dendrites growth


In a message dated 3/21/2002 10:24:53 AM US Eastern Standard Time,
[log in to unmask] writes:

<< Is conformal coating a good protection against dendrites? >>

Graham's answer is a very good one.  In a way, this question reminds me of
an
advertisement that I often saw in bicycling magazines during my college
days.
 It was for a new type of lock to hold one's bicycle to the parking rack,
and
it had for a headline "Resists Atomic Bombs".  The key being that it was not
100% successful, but it did offer resistance.
   In every comparative test that I have ever done, uncoated boards fared
far
worse than coated ones with respect to dendritic growth.  Does that mean
that
conformal coating will prevent dendrites from EVER appearing?  Clearly not.
My typical tests were 100 hours at 85 C and 85% RH, with power applied, with
the acrylic coated boards normally surviving the entire test and the
uncoated
boards failing in 2-8 hours, depending on the soldering process variables
involved.

Jon Moore

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