Again, it might be simplistic, but I think the spec gives you
only two options - store the parts in ESD protective packaging, or
if they're out of protective packaging, they have to be kept in
an ESD Protected Area (EPA).
Some might object that those boxes are constructed of static generating
plastic, but I think parts in the boxes will be okay as long as the box
is either:
1. enclosed in an external static shielding container, or
2. kept at an EPA where anyone who comes near it is grounded through a
strap or through conductive footwear and floor.
-Joe
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Robert Kondner
Sent: Thursday, May 27, 2010 10:26 AM
To: [log in to unmask]
Subject: Re: [TN] ESD spec question
Hi,
Resend from yesterday.
Does anyone have any good reasons why storing static sensitive parts in small plastic containers is "Not Good". See the MOSFETs in these pictures.
We use these small plastic boxes for engineering stock, very convenient.
www.kondner.com/files/partinbox.jpg
www.kondner.com/files/partbox.jpg
Thanks,
Bob Kondner
Kenny,
As long as you just look and don't touch you will not get in trouble! :-)
There was a ESD Expert, I forgot who, who would say "No Spark means No Problems". Spark was being used to infer current flow, obviously if no current flows through a junction there is no problem, by definition.
Now we get to the touching of parts. If a part is sitting on an insulator can any current flow? The answer is yes due to capacitance to free space.
Small parts have very small level of capacitance to free space. I have never seen numbers but I suspect any current flows would be well below damage levels.
If you touch a part in a metal drawer wow oh wow is that a different story.
I keep loose parts in plastic containers, that makes some folks cringe but none has ever explained how a damaging current could be generated to/from a part in an insulating container.
I would really like to get other folks informed ideas. Too many folks simply repeat some mantra without having any data. (Like buy the biggest house you can afford, don't worry about the payments. )
Bob Kondner
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ken Bloomquist
Sent: Wednesday, May 26, 2010 12:20 PM
To: [log in to unmask]
Subject: Re: [TN] ESD spec question
My first thought on this is that if I were looking in the drawers I'd touch the metal of the cabinet before opening the drawer. Also if the drawers have a metal handle and are grounded inside the cabinet the by virtue of all that you would be grounded, no need for anything more.
KennyB
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Graham Collins
Sent: Wednesday, May 26, 2010 9:30 AM
To: [log in to unmask]
Subject: [TN] ESD spec question
Hey TechNet
It's been a quiet day on Technet!
I've got a question regarding ESD. I was taught that if I am not grounded I do not go near anything that is ESD . The example we are debating here today concerns parts that are stored in metal cabinets.
The cabinet is grounded, and within the cabinet drawers there are ESD sensitive parts in individual bins, not covered or packaged (no faraday cage).
Is it OK to open the drawer and look into the cabinet without being properly grounded? I say no, but am I being overly cautious?
If "no" is the right answer, where would I find that in an ESD spec?
I've given ESD-S20.20 a quick peruse, nothing jumped out at me.
regards,
Graham Collins
Halifax Production Engineering
(902) 873-2000 ext. 6215
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