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#1
02-04-2007, 08:59 PM
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__________________
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#2
02-14-2007, 12:07 PM
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*sigh*
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#3
02-28-2007, 03:00 PM
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ESD Reality Check
Before things get too far afield, I'd like to get everyone serious about the use of straps and other ESD stuff. As a factory tech, this stuff gets beaten (severely) into us every year.
Pete's right about the resistor. It simply limits the current-flow to a safe amount, mainly for the device's sake. Draining the charge differential too fast is when the damage occurs. Current domestic manufacturing practice is to use the wrist-strap (1 Megohm series resistance included), along with a conductive mat on the workbench (also 1 Meg in the grounding lead). While home-bound techs get to stop there, factories use a grounded, conductive flooring, along with conductive heel-straps. These have a conductive little strip of fabric which goes into your shoe, where body moisture is supposed to complete the path. A drinking fountain and precision spitting often is needed to get my old, dry feet to conduct, no matter how ripe the sock is. Every morning EVERYONE working on the floor goes to a (3M) ESD tester and tests all three, then signs a logbook No sign, first QC, then the boss jumps you. Carts on wheels get a drag-chain bolted to the bottom shelf to minimize tire-friction charge, and all sensitive materiel is kept in conductive cabinets, drawers, foam, bags, etc. Finally, when a trouble-tag from an ATE/ICT run drops, it's printed on static-dissipative paper and taped to the board with static-free tape. Lastly, just because a piece of gear is energized, DON"T think that's a reason to unstrap! If you have any basic self-preservation instinct in you, you will simply keep your finger or hand-tool away from the circuit. End of lecture 
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