Identifying the Chassis, Routine Care, and Disassembly Preparation

5.2.1 Generating Static

The following table shows that:

■Different activities generate different amounts of static electricity.

■Static electricity increases as humidity decreases.

 

 

Relative Humidity

 

 

 

 

 

 

 

 

Event

55%

 

40%

 

10%

 

 

 

 

 

 

 

 

Walking across carpet

7,500

V

15,000

V

35,000

V

Walking across vinyl floor

3,000

V

5,000

V

12,000

V

Motions of bench worker

400

V

800

V

6,000

V

Removing DIPs* from plastic tube

400

V

700

V

2,000

V

 

 

 

 

 

 

 

Removing DIPs* from vinyl tray

2,000

V

4,000

V

11,500

V

Removing DIPs* from Styrofoam

3,500

V

5,000

V

14,500

V

Removing bubble pack from PCB

7,000

V

20,000

V

26,500

V

Packing PCBs in foam-lined box

5,000

V

11,000

V

21,000

V

*These components are multi-packaged inside plastic tubes, trays, or Styrofoam.

✎700 volts can degrade a product.

5.2.2 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 damage to electric components and accessories.

■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.

5.2.3Personal Grounding Methods and Equipment

Use the following equipment to prevent static electricity damage to equipment:

■Wrist straps are flexible straps with a maximum of one-megohm ± 10% resistance in the ground cords. To provide proper ground, you must wear a strap snug against bare skin. The ground cord must be connected and fit snugly into the banana plug connector on the grounding mat or workstation.

 

Service Reference Guide, dx5150

361685-001

5–3