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HP zx5000 User Manual

Page 107

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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