Removal and replacement procedures
Maintenance and Service Guide
4–3
The following table shows how humidity affects the electrostatic voltage levels generated by different activities.
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CAUTION:
A product can be degraded by as little as 700 V.
Packaging and transporting guidelines
Follow these grounding guidelines when packaging and transporting equipment:
■
To avoid hand contact, transport products in static-safe tubes, bags, or boxes.
■
Protect ESD-sensitive parts and assemblies with conductive or approved containers or packaging.
■
Keep ESD-sensitive parts in their containers until the parts arrive at static-free workstations.
■
Place items on a grounded surface before removing items from their containers.
■
Always be properly grounded when touching a component or assembly.
■
Store reusable ESD-sensitive parts from assemblies in protective packaging or nonconductive foam.
■
Use transporters and conveyors made of antistatic belts and roller bushings. Be sure that mechanized equipment
used for moving materials is wired to ground and that proper materials are selected to avoid static charging.
When grounding is not possible, use an ionizer to dissipate electric charges.
Workstation guidelines
Follow these grounding workstation guidelines:
■
Cover the workstation with approved static-shielding material.
■
Use a wrist strap connected to a properly grounded work surface and use properly grounded tools and
equipment.
■
Use conductive field service tools, such as cutters, screwdrivers, and vacuums.
■
When fixtures must directly contact dissipative surfaces, use fixtures made only of static-safe materials.
■
Keep the work area free of nonconductive materials, such as ordinary plastic assembly aids and Styrofoam.
■
Handle ESD-sensitive components, parts, and assemblies by the case or PCM laminate. Handle these items
only at static-free workstations.
■
Avoid contact with pins, leads, or circuitry.
■
Turn off power and input signals before inserting or removing connectors or test equipment.
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
Содержание 512424-001
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Страница 119: ...7 4 Maintenance and Service Guide Screw listing Where used 2 screws that secure the system board to the base enclosure ...
Страница 121: ...7 6 Maintenance and Service Guide Screw listing Where used One screw that secures the SIM slot board to the computer ...
