Removal and replacement procedures

The following table shows how humidity affects the electrostatic voltage levels generated by different activities.

ÄCAUTION: A product can be degraded by as little as 700 V.

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

 

 

 

 

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 they arrive at static-free workstations.

■Place items on a grounded surface before removing them 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 workstation grounding 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.

Maintenance and Service Guide

4–3