Hp zx5000 Manuel d'utilisateur télécharger pdf (Page 107)

Removal and Replacement Preliminaries

Maintenance and Service Guide 4–9

Table 4-1 shows how humidity affects the electrostatic voltage

levels generated by different activities.

Table 4-2 lists the shielding protection provided by antistatic bags

and floor mats.

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

✎

A product can be degraded by as little as 700 volts.

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 5,000 V

1 2 ... 102 103 104 105 106 107 108 109 110 111 112 ... 271 272

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Hp zx5000 Manuel d'utilisateur Page 107