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TM 9-254
Section IV. ELECTROSTATIC DISCHARGE (ESD) AWARENESS
8-9.
General Information.
a.
Scope. It is essential to understand the nature of electrostatic discharge (ESD), what causes it, and the
problems it can cause. This section contains information on the areas of major concern.
b.
Basic Definitions.
(1)
Electrostatic Discharge (ESD). A sudden and rapid transfer of electrons or charge between two objects.
An example of ESD is the shock received after walking across a carpet and touching a metallic object,
like a door knob.
(2)
Electrostatic Discharge Sensitive (ESDS) Items. All noninstalled electronic components, circuit cards
and assemblies with sensitive labels. Items that fall within the Federal Supply Class (FSC) 5905, 5960,
5961, or 5962 should be treated as sensitive unless known to be otherwise.
(3)
ESD Protective Material. Conductive, antistatic, and static dissipative are all types of materials that are
used to protect against ESD. Static dissipative materials are preferred because the charge dissipates
across the surface at a controlled rate.
c.
Typical Prime Charge Sources. Means of generating electrostatic charges (voltage) and their relationship to
relative humidity are shown in table 8-7.
Table 8-7. Means of Static Charge Generation and the Associated Voltages
MEANS OF STATIC GENERATION
ELECTROSTATIC VOLTAGES WITH
AND
10 - 20 %
65 - 90 %
PERCENTAGE OF RELATIVE HUMIDITY
RELATIVE
RELATIVE
HUMIDITY
HUMIDITY
WALKING ACROSS CARPET
35,000
1,500
WALKING ON VINYL FLOOR
12,000
250
WORKER AT WORKBENCH
6,000
100
Change 3 8-26
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