Re: How do you harden electronics?

Hello Todd

I did some research which confirmed what I already belived.  Hardening consists 
primarily of using conductive materials to surrond electronics.

Below are some excerpts from the Internet............  Gus Calabrese
 http://www.geocities.com/CapeCanaveral/5971/emp.html

EMP Hardening 
There are two things to consider when considering hardening targets against EMP. 
The first question to answer is whether the hardened system will become useless if 
shielded. The second question to be answered is whether the target is 
economically worthwhile to harden. The answers to these two questions are used 
to determine what devices should be shielded 

To explain the first consideration, Makoff and Tsipis give the following simple 
example. If there was a communication plane with many antennas used to collect 
and transfer data, it would not be useful if its antennas were removed. However, to 
harden the plane, the antennas would need to be removed because they provide a 
direct path to the interior of the plane.(18) It is important to understand how the 
hardening will affect the performance of the hardened item. 

The second consideration is very easy to understand. Some systems, although 
important, may not seem worthwhile enough to harden due to the high costs of 
shielding. "It may cost from 30% to 50% of the cost of a ground based 
communication center…just to refit it to withstand EMP," and, "as high as 10% of the 
cost for each plane."(19) 

There are two basic ways to harden items against EMP effects.20 The first method 
is metallic shielding. The alternative is tailored hardening. Both methods will be 
briefly described. 

Metallic shielding is used to, "Exclude energy propagated through fields in 
space."(21) Shields are made of a continuous piece of some metal such as steel or 
copper. A metal enclosure generally does not fully shield the interior because of the 
small holes that are likely to exist. Therefore, this type of shielding often contains 
additional elements to create the barrier. Commonly, only a fraction of a millimeter 
(22) of a metal is needed to supply adequate protection. This shield must 
completely surround the item to be shielded. A tight box must be formed to create 
the shield. The cost of such shielding (in1986 dollars) is $1000 per square meter 
for a welded-steel shield after installation.(23) 

The alternative method, tailored hardening, is a more cost-effective way of 
hardening. In this method, only the most vulnerable elements and circuits are 
redesigned to be more rugged. The more rugged elements will be able to withstand 
much higher currents. However, a committee of the National Academy of Sciences 
is skeptical of this method due to unpredictable failures in testing.(24) Also, the use 
of this method is not recommended by the National Research Council. They 
doubted whether the approximations made to evaluate susceptibilities of the 
components were accurate. They did concede that tailored hardening may be 
useful to make existing systems less vulnerable.(25) 

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000000000000000000000000000000000000 http://www.textfiles.com/survival/emp.txt

THREE ten-megaton thermonuclear weapons detonated 250 miles ( 400 
kilometers )
above the United States or Canada would produce EMP's strong enough to knock
out the entire electrical power grid of North America including the entire
civilian-telephone network, and just about every broadcast station.
 Virtually every piece of unprotected electronic equipment in the country
-- radios, TV sets, computers, electronic controls in homes, office build-
ings, factories, cars, airplanes, and instruments in hospitals -- would be
damaged, if not destroyed.  The pulses would also damage or destroy large
portions of the military command's control and communication (C3) system.
A chain reaction could be set in motion at nuclear power plants, due to elec-
tromagnetic pulses. Although it is a point that is frequently disputed, the
possibility exists that reactor core meltdowns might occur as a result of
EMP's.  The meltdowns would be a by-product of electronic control system
failure.  The control systems are used to monitor and control the processes at
the plants. The EMP's could cause the system to fail and result in partial or
complete loss of control over vital functions, causing subsequent melt-
downs.  We know that those nuclear plants are designed to be fail safe,
but has anyone considered the possibility of every circuit breaker in a
plant failing at the same instant?    

(cut)
THERE are three major design criteria which must be considered when hardening
against EMP's.  They are cost, the equipment's ability to survive EMP, and
failure rates of the shielding components.                               
COST includes both installation and maintenance.  Some protection practices,
such as shielding the entire communication site, may be attractive from a
technical point of view, but are impractically expensive.