● Different activities generate different amounts of static electricity.
● Static electricity increases as humidity decreases.
Table 4-1 Static electricity occurrence based on activity and humidity
Relative humidity
Event 55% 40% 10%
Walking across carpet
Walking across vinyl floor
Motions of bench worker
Removing dual in-line packages (DIPs) from plastic
tube
7,500 V
3,000 V
400 V
400 V
15,000 V
5,000 V
800 V
700 V
35,000 V
12,000 V
6,000 V
2,000 V
Removing DIPs from vinyl tray
Removing DIPs from polystyrene foam
Removing bubble pack from PCB (printed circuit
board)
Packing PCBs in foam-lined box
2,000 V
3,500 V
7,000 V
5,000 V
4,000 V
5,000 V
20,000 V
11,000 V
11,500 V
14,500 V
26,500 V
21,000 V
NOTE: Multiple electric components can be packaged together in plastic tubes, trays, or polystyrene
foam.
As little as 700 V of static electricity 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 packaging and grounding precautions are necessary to prevent static electricity damage
to electronic components:
● To avoid hand contact, transport products in static-safe containers such as tubes, bags, or boxes.
● 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.
● Avoid contact with pins, leads, or circuitry.
● Place reusable electrostatic-sensitive parts from assemblies in protective packaging or conductive
foam.
Personal grounding methods and equipment
Using certain equipment can prevent static electricity damage to electronic components.
26
Chapter 4 Removal and replacement procedures preliminary requirements
To Next Page
Loading...
Need help?
General
