Electrostatic Voltage Levels And Protective Materials - Compaq Armada 3500 series Service Manual

4.4.4 Electrostatic Voltage Levels and Protective
Materials
Table 4-1 shows how humidity affects the electrostatic voltage levels generated by
different activities.
Event
Walking across carpet
Walking across vinyl floor
Motions of bench worker
Removing DIPS from plastic tube
Removing DIPS from vinyl tray
Removing DIPS from Styrofoam
Removing bubble pack from PCB
Packing PCBs in foam-lined box
NOTE: 700 volts can degrade a product.
Table 4-2 lists the shielding protection provided by antistatic bags and floor mats.
Material
Antistatic plastic
Carbon-loaded plastic
Metallized laminate
4-6 Removal and Replacement Preliminaries
Table 4-1
Typical Electrostatic Voltage Levels
Relative Humidity
10%
35,000 V
12,000 V
6,000 V
2,000 V
11,500 V
14,500 V
26,500 V
21,000 V
Table 4-2
Static-Shielding Materials
Use
Bags
Floor mats
Floor mats
40% 55%
15,000 V 7,500 V
5,000 V 3,000 V
800 V 400 V
700 V 400 V
4,000 V 2,000 V
5,000 V 3,500 V
20,000 V 7,000 V
11,000 V 5,000 V
Voltage Protection Level
1,500 V
7,500 V
15,000 V