Generating Static; Preventing Electrostatic Damage To Equipment; Removing Batteries - Compaq Armada 1500C series Service Manual

Generating Static

Table 4-1 shows how different activities generate static electricity and at different
electrostatic voltage levels.
Event
Walking across carpet
Walking across vinyl floor
Motions of bench worker
Removing DIPS from plastic tubes
Removing DIPS from vinyl trays
Removing DIPS from Styrofoam
Removing bubble pack from PCBs
Packing PCBs in foam-lined box
NOTE: 700 volts can degrade a product.

Preventing Electrostatic Damage to Equipment

Many electronic components are sensitive to ESD. Circuitry design and structure
determine the degree of sensitivity. The following proper packaging and grounding
precautions are necessary to prevent damage:
Protect all electrostatic parts and assemblies with conductive or approved
containers or packaging.
Keep electrostatic-sensitive parts in their containers until they arrive at
static-free stations.
Place items on a grounded surface before removing them from their
container.
Always be properly grounded when touching a sensitive component or
assembly.
Place reusable electrostatic-sensitive parts from assemblies in protective
packaging or conductive foam.
Use transporters and conveyors made of antistatic belts and metal roller bushings.
Mechanized equipment used for moving materials must be wired to ground and proper
materials selected to avoid static charging. When grounding is not possible, use an
ionizer to dissipate electric charges.

Removing Batteries

Compaq recommends that you remove all batteries from the computer before
beginning the disassembly procedures. Failure to do so could cause damage to
computer components.
4-2 Removal and Replacement Preliminaries
Table 4-1
Typical Electrostatic Voltages
35,000 V
12,000 V
6,000 V
2,000 V
11,500 V
14,500 V
26,000 V
21,000 V
Relative Humidity
10% 40%
15,000 V
5,000 V
800 V
700 V
4,000 V
5,000 V
20,000 V
11,000 V
55%
7,500 V
3,000 V
400 V
400 V
2,000 V
3,500 V
7,000 V
5,000 V