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4-6 Removal and Replacement Preliminaries
COMPAQ CONFIDENTIAL - NEED TO KNOW REQUIRED
Writer: David Calvert Saved by: The Integrity Group Saved date: 10/26/00 11:46 AM
Part Number: 128679-006 File name: Ch04
Table 4-1 shows how humidity affects the electrostatic voltage levels
generated by different activities.
Table 4-1
Typical Electrostatic Voltage Levels
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
tube
2,000 V 700 V 400 V
Removing DIPS from vinyl tray 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
PCB
26,500 V 20,000 V 7,000 V
Packing PCBs in foam-lined
box
21,000 V 11,000 V 5,000 V
NOTE: A product can be degraded by as little as 700 volts.
Table 4-2 lists the shielding protection provided by antistatic bags and
floor mats.
Table 4-2
Static-Shielding Materials
Material Use Voltage Protection Level
Antistatic plastic Bags 1,500 V
Carbon-loaded plastic Floor mats 7,500 V
Metallized laminate Floor mats 15,000 V