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June 2011

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Subject:
From:
Gerald Bogert <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
Date:
Wed, 1 Jun 2011 10:05:59 -0400
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text/plain
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June 1, 2011

 

J-STD-001E, paragraph 4.2.2 includes the following requirement; in part;

 

"When humidity decreases to a level of 30% or lower, the manufacturer
shall [N1D2D3] verify that electrostatic discharge control is adequate,
---"

 

My question is, what does this mean in the real world???

 

Some of our OEMs just verify that personnel wrist-straps are continuing
to work properly; if heel straps are used, they also verify these.

 

At least one OEM stops work and dumps moisture into the air till the
humidity is > 30%.

 

Some OEMs have constant monitor wrist strap units and if one assumes the
wrist strap is always connected to the monitor and the person, there
would be no reason to do anything if humidity drops below 30% since the
strap connection would be constantly monitored.  

 

Some OEMs claim that since they require all folks to verify their wrist
straps in the morning that they need not do anything.  I reject this
argument since although humidity could have been > 30% in the morning,
later in the day it could have dropped below 30%.  

 

While I recognize that there is a greater potential for component damage
due to ESD when the humidity is below 30% than there is when humidity is
much higher, if the ESD straps were functioning properly in the AM, I do
not see how lowering humidity could cause the ESD protection to no
longer function, and therefore why folks would need to do anything.

 

Any input you can provide on this subject would be appreciated since
both J-STD-001 and the 001 Handbook do not provide any insight on what
needs to be done.

 

[log in to unmask]

 


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