Even with all of the ESD controls in place, the mil specs require the
assembly operation to shut down if the humidity goes below 25%!!!
Elliott WA6TLA
----- Original Message -----
From: "Rick Dettinger" <[EMAIL PROTECTED]>
To: "Ron D'Eau Claire" <[EMAIL PROTECTED]>
Cc: <[email protected]>
Sent: Saturday, July 26, 2008 10:03 AM
Subject: Re: [Elecraft] ESD Safety
Looks like the only solution is to work under water. All of the voltages
exceed the 30 volts or so level we have heard cause damage to sensitive
components.
73
Rick Dettinger K7MW
====================================
On Jul 26, 2008, at 9:51 AM, Ron D'Eau Claire wrote:
This is a subject that comes up here regularly among those working on
their Elecraft (and other) rigs.
Doing some research on a project, I ran across the following values
published by Hewlett-Packard Company. They provide some insight about
why it's important to use ESD-safe handling procedures.
The "PCBs" mentioned below are, of course, Printed Circuit Boards, not
the stuff found in old capacitors and transformers. "DIPs" are Dual
In-line Pin integrated circuits such as found throughout Elecraft rigs.
Typical Electrostatic Voltage Levels
Relative Humidity for each voltage level shown below:
10%
40%
55%
Walking across carpet
35,000 V
15,000 V
7,500 V
Walking across vinyl floor
12,000 V
5,000 V
3,000 V
Motions of bench worker
6,000 V
800 V
400 V
Removing DIPS from plastic tube
2,000 V
700 V
400 V
Removing DIPS from vinyl tray
11,500 V
4,000 V
2,000 V
Removing DIPS from Styrofoam
14,500 V
5,000 V
3,500 V
Removing bubble pack from PCB
26,500 V
20,000 V
7,000 V
Packing PCBs in foam-lined box
21,000 V
11,000 V
5,000 V
Ron AC7AC
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