| azimuth40 2002-11-01, 12:26 pm |
| quote:
Originally posted by jayesser
Perhaps someone cam lay this controversy to rest. I have seen many conflicting posts and questions in various study guides regarding what conditions promote ESD.
I have seen the answer as cold and dry, warm and dry. Which one is it? Anyone know the CORRECTanswer to this?
Both. Only dry is important humidity below 50% generally. The rest (temperature) is based on the available charge potential differences, i.e. protons and electrons. The available charge potentials are then based on the materials involved. This does not format worth beans but the general idea is static points at 10 40 and 50 percent humidity in volts
Relative Humidity
Event 10% 40% 55%
Walking across carpet 35,000 V 15,000 V 7,500 V
Walking across vinyl floor 12,000 V 5,000 V 3,000 V
Motions of bench worker 6,000 V 800 V 400 V
Removing DIPS from plastic tubes 2,000 V 700 V 400 V
Removing DIPS from vinyl trays 11,500 V 4,000 V 2,000 V
Removing DIPS from Styrofoam 14,500 V 5,000 V 3,500 V
Removing bubble pack from PCBs 26,000 V 20,000 V 7,000 V
Packing PCBs in foam-lined box 21,000 V 11,000 V 5,000 V
NOTE: 700 volts can degrade a product |