I forgot to add this one: there is another reason for being careful with
even lowest charges, namely the fact that many devices may not get ESD
damaged, but they can change electrical status, which can be problem
enough! The following is just one of many such examples.
Inge
"Today's TTL and CMOS logic states have a logic "0" at 0.8 Volts or
lower and a logic "1" at 2.0 Volts or higher. This leads to a smaller
indeterminate range of 1.2 Volts for most TTL and some CMOS logic
circuits and places the logic inputs from these circuit traces or cable
connections susceptible to induced EMI voltages exceeding this range.
One example of an ESD-induced EMI was characterized from office chairs
[3, 4]. Induced voltages over 2 Volts have been measured on a printed
circuit assembly (PCA) 90 cm from the furniture ESD [4]. Two Volts is
enough voltage to easily drive a TTL circuit let alone an ECL circuit
into a logic error. " From ESD Journal.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Roger Stoops
Sent: den 5 mars 2007 15:22
To: [log in to unmask]
Subject: Re: [TN] ESD question
Like the old saying, 28 grams of prevention is worth 454 grams of cure !
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Hernefjord Ingemar
Sent: Monday, March 05, 2007 9:18 AM
To: [log in to unmask]
Subject: Re: [TN] ESD question
There are no paragraphs for that obvious and given case: of course
anyone MUST use heel straps! The one who says he will not touch
anything, one minute after gave this promise, he may be charged to
several Volts or even hundreds Volts (if he hasn't ESD shoes) and after
two minutes he may have forgotten not to touch anything. Ask some guys
to walk around and then place their feet on the ESD tester, and you'll
probably have proof enough. 10 VDC discharge at 10 picoseconds is enough
to cause damage to certain 1.5 V devices!
Inge
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Bob Arciolla
Sent: den 5 mars 2007 14:57
To: [log in to unmask]
Subject: [TN] ESD question
Good Morning all,
A question regarding ESD has come up in our facility. Our SMT area has
ESD flooring and the question that came up is that one of our
instructors says that anyone entering the room must have heel straps on
and another says that if a person is just going into the room and not
touching product, they don't need heel straps. Who is correct?
Regards,
Bob Arciolla
Endicott Research Group
Quality/Safety Manager
607 754-9187 ex 3034
607 754-9255 fax
cell 607 624-8516
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