Hello experts! I want to know why the impedance when measuring the floor needs to be less than 10^9 Ω, is there any scientific basis?
Hi Chris,
While some numbers are based on a consensus, this requirement dates back to work done on decay. The 1x10e9 was based on how long it took a typical tote box that was charged to decay to a safe level to be opened. In the case of 1x10e9 or lower, a charged tote will decay in less that 1 sec. This is quick enough so that the tote is safe to open and pick ESDS parts with a grounded operator.
If the resistance is greater than 1x10e9 the decay time will increase. At 1x10e10 it was more than 1 second. As the resistance increases the time to decay will also increase.
The number was also decided with what was avaiable at the time. There were and still are product that meet this specification.
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Dear JohnK
thanks for your reply
I have benefited a lot