3-41
touched with a bare hand. Figure 3-32 shows a more refined ground strap which frees both hands
for work.
Figure 3-32.—ESD wrist strap.
2. Equipment technical manuals and packaging material should be checked for ESD warnings and
instructions.
3. Prior to opening an electrostatic unit package of an electrostatic sensitive device or assembly, clip
the free end of the test lead to the package. This will cause any static electricity which may have
built up on the package to discharge. The other end remains connected to the equipment frame or
other ESD ground. Keep the unit package grounded until the replacement device or assembly is
placed in the unit package.
4. Minimize handling of ESDS devices and assemblies. Keep replacement devices or assemblies,
with their connector shorting bars, clips, and so forth, intact in their electrostatic-free packages
until needed. Place removed repairable ESD devices or assemblies with their connector shorting
bars/clips installed in electrostatic-free packages as soon as they are removed from the equipment.
ESDS devices or assemblies are to be transported and stored only in protective packaging.
5. Always avoid unnecessary physical movement, such as scuffing the feet, when handling ESDS
devices or assemblies. Such movement will generate additional charges of static electricity.
6. When removing or replacing an ESDS device or assembly in the equipment, hold the device or
assembly through the electrostatic-free wrap if possible. Otherwise pick up the device or
assembly by its body only. Do not touch component leads, connector pins, or any other electrical
connections or paths on boards, even though they are covered by conformal coating.
7. Do not permit ESDS devices or assemblies to come in contact with clothing or other ungrounded
materials that could have an electrostatic charge. The charges on a nonconducting material are
not equal. A plastic storage bag may have a
-
10,000 volt potential 1/2 inch from a +15,000 volt
potential, with many such charges all over the bag. Placing a circuit card inside the bag allows the
charges to equalize through the pcb conductive paths and components, thereby causing failures.
Do not hand an ESD device or assembly to another person until the device or assembly is
protectively packaged.
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