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December 1999

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Subject:
From:
David Douthit <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Tue, 28 Dec 1999 23:13:16 -0700
Content-Type:
text/plain
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text/plain (46 lines)
Technetters,

I would like some expert opinions on what constitutes a "harsh
environment".
In order to stimulate some debate the following is one proposed
definition.

"Due to the highly competitive nature of the electronics industry and
costs of coating the issue of whether coating is required or not can
become a hotly debated topic. The primary issue is "What is a harsh
environment?".

The following general rules can be considered as the boundary line
condition for a "harsh environment". There are three minimum conditions
which must exist in the localized area of the circuitry at the same time
with or without power applied:
1. A relative humidity of 60% or higher.
2. Temperatures above 0 degrees C.
3. The deposition of ionic contaminates on the circuitry surface which
will exceed 1.5ug
     of NaCl or its' equivalent per square cm during the expected
lifetime of the product.

Consideration of these conditions must also include shipping, storage,
and handling of the product. These conditions are a reference point and
exceptions are possible. Researching these environments are required to
determine if these conditions exist."

Thank you for your time.

D. A. Douthit

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