Protecting Parts From Electrostatic Discharge; Precautions; Workstation Practices - CPI S5CIA Installation And Operation Manual

M
AINTENANCE
6.6 Protecting Parts from Electrostatic
Discharge
Static electricity is a familiar phenomenon; except for an occasional mild shock or annoying "static
cling," it does not seem very serious to most personnel handling integrated circuit (IC) parts or
assemblies. Unfortunately, many electronic components can be damaged or destroyed by
electrostatic discharge (ESD) at potentials well below a person's range of feeling. This damage can
occur before, during, or after the part is installed.
People often carry 1000 to 5000 volts of static charge and do not feel any discharge of less than
3500 to 4000 V. Components mounted on a printed circuit board face increased risk of ESD
damage because each printed conductor (wire) is a path connecting several devices. A discharge to
that conductor stresses several devices at once.
susceptible, and the damage ranges from a slight degradation of a parameter to catastrophic
failures, such as short circuits. In many cases, a damaged part exhibits little or no visible physical
damage, even under microscopic examination.
6.6.1

Precautions

ESD damage can be prevented for the most part by following these precautions:
1. Treat all electronic parts and assemblies as static sensitive.
2. Do not touch leads, pins, or traces while handling parts.
3. Keep parts in original containers until ready for use.
4. Discharge all static before handling devices by touching a grounded metallic surface such as a
rack or cabinet. For personal grounding, use a wrist strap grounded through a 1-megohm
resistor.
5. Do not slide static-sensitive devices over any surface.
6.6.2

Workstation Practices

Handle all sensitive parts or assemblies at static-safe workstations. A static-safe workstation
provides the following features:
• A conductive tablemat grounded through a 1-megohm resistor.
• A conductive wrist strap wired to a swivel connector on the mat through a 1-megohm resistor.
•
Common ground point at each workstation.
•
A work area free of nonconductors, including all common plastics, "polybags," cardboard,
cigarette packages, candy wrappers, work envelopes, synthetic mats, and ungrounded metal
plates. Carpeting should not be used on floors, work surfaces, or shelving.
6-10
Passive as well as active components are
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