HP Xw8400 HP xw8400 Workstation - Service and Technical Reference Guide - Page 57

Generating static, Preventing electrostatic damage to equipment

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Generating static The following table shows that Different activities generate different amounts of static electricity. Static electricity increases as humidity decreases. Table 4-1 Static electricity Relative Humidity Event 5% 4% 1% Walking across carpet Walking across vinyl floor Motions of bench worker 7,500 V 3,000 V 400 V 15,000 V 5,000 V 800 V 35,000 V 12,000 V 6,000 V Removing bubble pack from PCB Packing PCBs in foam-lined box 7,000 V 5,000 V 20,000 V 11,000 V 26,500 V 21,000 V CAUTION: 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 packaging and grounding precautions are necessary to prevent damage to electric components and accessories. ● Transport products in static-safe containers, such as tubes, bags, or boxes, to avoid hand contact. ● 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 containers. ● When handling or touching a sensitive component or assembly, ground yourself by touching the chassis. ● 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 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 a proper ground, wear the strap against bare skin. The ground cord must be connected and fit snugly into the banana plug connector on the grounding mat or workstation. ● Heel straps, toe straps, and boot straps can be used at standing workstations and are compatible with most types of shoes or boots. On conductive floors or dissipative floor mats, use them on both feet with a maximum of one-megohm ± 10% resistance between the operator and ground. Table 4-2 Static shielding protection levels Method Voltage Antistatic plastic 1,500 ENWW Service considerations 47

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Generating static
The following table shows that Different activities generate different amounts of static electricity. Static
electricity increases as humidity decreases.
Table 4-1
Static electricity
Relative Humidity
Event
5%
4%
1%
Walking across carpet
Walking across vinyl floor
Motions of bench worker
7,500 V
3,000 V
400 V
15,000 V
5,000 V
800 V
35,000 V
12,000 V
6,000 V
Removing bubble pack from PCB
Packing PCBs in foam-lined box
7,000 V
5,000 V
20,000 V
11,000 V
26,500 V
21,000 V
CAUTION:
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 packaging and grounding precautions are necessary to prevent damage to
electric components and accessories.
●
Transport products in static-safe containers, such as tubes, bags, or boxes, to avoid hand contact.
●
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 containers.
●
When handling or touching a sensitive component or assembly, ground yourself by touching the
chassis.
●
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
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 a proper ground, wear the strap against bare skin. The ground cord must be
connected and fit snugly into the banana plug connector on the grounding mat or workstation.
●
Heel straps, toe straps, and boot straps can be used at standing workstations and are compatible
with most types of shoes or boots. On conductive floors or dissipative floor mats, use them on both
feet with a maximum of one-megohm ± 10% resistance between the operator and ground.
Table 4-2
Static shielding protection levels
Method
Voltage
Antistatic plastic
1,500
ENWW
Service considerations
47