First of all, an ESD shielding bag is not a "perfect" Faraday cage.
Some level of static potential does penetrate the bag.  We use to say,
"5kV on the bag will yield less than 100V in the bag."  What is the
sensitivity of the static event detector that was used?  Was the bag
completely closed (folded-over or zipped shut)?  

In the old days when we attempted to "qualify" ESD bags, we used an ESD
sensor that would emit an audible "churp" when it detected some level of
static potential (the literature supplied with the sensor wasn't very
specific as to sensitivity).  This sensor was called a "Sense-A-Volt"
and the bags I tested usually passed when zapped with a zerostat
(probably sereral thousand volts).  Please feel free to contact me
directly, if I may be of any assistance.

David N. Girard, CQE, NCE
Product Assurance Engineer
Group Technologies Corp.
[log in to unmask]  

> ----------
> From:         Patrick Ducas[SMTP:[log in to unmask]]
> Sent:         Monday, September 15, 1997 15:45
> To:   [log in to unmask]
> Subject:      [TECHNET] ESD - shielding bags
> 
> I'm sending this e-mail for a partner.
> 
> I recently bought myself a 3M static event detector to evaluate my
> static
> shielding bags.
> What I do is insert this device into the bag and with a "ZAPPER", I
> give
> this bag an electrostatic discharge ranging from 2kV to 20kV.  If the
> LCD
> display from the device turns red, a static event as been recorded.
> How
> strange?  Most of our bag failed this simple test.  My questions are:
> 
> 1) Is it possible that I'm using the wrong test to verify the
> shielding bag?
> 2) Why the bag is called "static shielding" when a discharge can go
> through
> the bag and make    the display turn red (ESD event detected)?
> 3) Is there another way to test the bag?
> 4) If a static event was detected with the device inside the bag, is
> it
> possible that when this bag is manipulated by personel, a discharge
> may
> dammage the sensitive product inside the bag?
> 
> Any comment or answer would be very appreciated.
> 
> Thanks
> -------------------------------------------------
> Patrick Ducas
> Process Quality Engineer 
> Matrox Electronic Systems Ltd
> E-mail: [log in to unmask]
> Tél:(514)969-6000 ext.2971   Fax:(514)685-3415
> -------------------------------------------------
>         	
> 
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