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  1. #21
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    Re: Resistance of component bag made of "reddish" ESD plastic?

    For example, no matter how conductive a floor is, someone walking over it with synthetic shoe soles could charge the whole rack then cause the damage by touching the boards while grounded.
    Thanks that interesting......but if the ESD wriststrap is grounded via 1 megohm, then would the "charged up" PCB get gradually discharged, thus avoiding problems?



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  2. #22
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    Re: Resistance of component bag made of "reddish" ESD plastic?

    but if the ESD wriststrap is grounded via 1 megohm, then would the "charged up" PCB get gradually discharged, thus avoiding problems?
    Not quite sure.

    A big PCB may have significant capacitance and with a 1M resistor it can produce significant current that can produce considerable potential drops at different points on the board that can harm sensitive devices and perhaps to die an untimely death.

    The only cure is to prevent the rack getting charged at wrong times. Fully populated boards are far more robust because of resistors and capacitors that may or can limit too much of voltage drops across sensitive and delicate parts.



  3. #23
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    Re: Resistance of component bag made of "reddish" ESD plastic?

    And also consider whether the person carrying the boards IS wearing a wrist strap while moving from place to place. Do they charge the boards to high voltage, then put the strap on, making their body potential drop, then touch the boards to remove them from the rack?

    Personally, I prefer foot straps, the kind that is a thin conductive plastic strip that wraps under the foot and shoe heel and has folding metal ends you bend over the edge of the shoe. The kind that are like a sling with an elastic/velcro strap that fixes over the foot are unreliable if socks are worn. A wrist strap would still be used at a workstation.

    Brian.
    PLEASE - no friends requests or private emails, I simply don't have time to reply to them all.
    It's better to share your questions and answers on Edaboard so we can all benefit from each others experiences.



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