NAVAIR 01-1A-509-3
01 March 2005
TM 1-1500-344-23-3
TO 1-1-689-3
Table 8-1. Typical Prime Charge Sources
maintenance work place. For example, latex finger
cots rubbed against a plastic box can charge to 6 kV
while bare fingers can generate only 200 volts. Note
Prime Source
Composition/Application
that even 200 volts of static charge can degrade or
destroy some ESDS devices. An additional source of
Work Surfaces
Formica
static charge is created during wave soldering and
Finished wood
Synthetic mats
general cleaning operations. Normally, low surface
Metal plates
energy solvents such as chlorinated hydrocarbons are
used in these operations. Although such solvents
Floors
Wax-finished
provide excellent cleaning capacity, rapid evaporation,
Vinyl
and noncorrosive properties, they increase static
Clothes
Clean room smocks
control problems. As indicated in Table 8-3, rubbing a
Personal garments (i.e., wool,
printed circuit board (PCB) with a solvent saturated
nylon, dacron)
cloth can generate substantial charges. This is much
Chairs
Finished wood
like rubbing the PCB with a Teflon or chlorinated
Vinyl
plastic film. This problem can be solved by using a
chlorinated-glycol hydrocarbon antistatic solvent.
Packaging/Handling
Polyethylene bags, wraps,
envelopes; bubble pack; foam;
8-4. TYPES OF ESD FAILURES.
plastic trays, boxes
Repair/Cleaning Areas
Spray cleaners
8-4.1. INTERMITTENT FAILURES. ESD can cause
Solder suckers
intermittent or upset failures as well as hard failures of
Solder irons
aircraft electronics. Intermittent or upset failures can
Solvent brushes
occur on Large Scale Integration (LSI) ICs when
Moving Air
Forced air drying of
equipment is in operation. This is usually characterized
equipment/components
by a loss of information or temporary distortion of its
functions. No apparent hardware damage occurs and
proper operation resumes automatically after ESD
environment eliminate contamination during handling
exposure and system reset. Upset failures can be the
of devices. However, their use in conjunction with
result of a spark near the equipment. The EMP
other materials often result in a very high static charge.
generated by the spark causes erroneous signals to
Specifically, synthetic materials are used frequently
be routed through equipment circuitry. Upset failures
because they are nonporous, flexible, and easily
can also occur by capacitive/inductive coupling of ESD
fabricated. Static charges can be generated from
pulses or direct discharge through a signal path
common materials found in the clean room or
providing an erroneous signal.
Table 8-2. Typical Electrostatic Charges
Electrostatic Charge (Volts)
Means of Generation
10 to 20%
65 to 90%
Walking across carpet
35,000
1,500
Walking over vinyl floor
12,000
250
Worker at bench
6,000
100
Maintenance Action Form (MAF) bag (work card envelope)
7,000
600
Common poly bag picked up from bench
20,000
1,200
Work chair padded with polyurethene foam
18,000
1,500
Styrofoam coffee cup
5,000
Undetermined
Plastic solder sipper
8,000
Undetermined