Electrostatic Discharge (Esd) Information - HP Z1 Maintenance And Service Manual

Electrostatic discharge (ESD) information

Generating static
Preventing ESD
equipment damage
Personal grounding
methods and
equipment
Static shielding
materials
Grounding the work
area to prevent static
damage
Different activities generate different amounts of static electricity through electrostatic discharge
(ESD). Static electricity increases as humidity decreases.
CAUTION: Static electricity in the amount of 700 volts might degrade a product.
Event
Walking across carpet
Walking across vinyl floor
Motions of bench worker
Removing bubble pack from PCB
Packing PCBs in foam-lined box
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 electrostatic parts and assemblies with nonconductive 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 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
●
nonconductive foam.
Use the following items to help prevent ESD damage:
Wrist straps — These 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 computer.
Heel straps, toe straps, and boot straps — These can be used at standing computers 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.
Static shielding materials provide the following levels of protection.
Method
Antistatic plastic
Carbon-loaded plastic
Metalized laminate
Cover the work surface with approved
●
static-dissipative material. Use a wrist
strap connected to the work surface, and
properly grounded tools and equipment.
Relative humidity
55% 40%
7,500V 15,000V
3,000V 5,000V
400V 800V
7,000V 20,000V
5,000V 11,000V
Voltage
1,500V
7,500V
15,000V
Disconnect power and input signals before
●
inserting and removing connectors or test
equipment.
Service considerations
10%
35,000V
12,000V
6,000V
26,500V
21,000V
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