ESD or
Antistatic Wrist Strap is a protective device worn by personnel while
working on sensitive electronic components in order to safely direct static
electricity from their body to ground, and avoid equipment damage. This is because the
antistatic wrist strap can avert the accumulation of static
electricity, which can eventually lead to an electrostatic discharge.
Individually
owned ESD wrist straps are typically to be connected to ground through a crocodile
clip. On the other hand, those found in the industry normally connect to part
of the grounding system or earth bonding points by either a 4 mm plug or
10 mm press stud.
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| ESD or Antistatic Wrist Strap |
Antistatic
wrist straps are mainly used in the electronics industry by technicians working
on electronic devices such as computers, which can be damaged by electrostatic
discharge. In a less extensive manner, people working around explosives wear
ESD wrist straps so that electric sparks that could trigger an explosion
can be prevented.
Also, it
should be used whenever trying to open equipment’s chassis, especially when
handling circuit cards and electronic components. Moreover, the antistatic wrist
strap must make good contact at equipment frame at one end and the person’s
skin on the other for it to work as specified.
Furthermore,
industries employ other ESD protective devices in conjunction with wrist
straps. These devices include ESD floor mats and special vinyl floor tile and ankle
straps. They are often used to allow personnel to move freely in a work area where
a grounding cable would be bothersome.
Lastly,
it is recommended to check the reliability of the device prior to using it, through
an antistatic wrist strap tester, as there is a possibility that it could
fail to perform its intended function.
Construction and Components
The
antistatic wrist strap is basically composed of a flexible band
of fabric with conductive fibers, which are generally made of carbon
or carbon-filled rubber. Meanwhile, the strap is bound with a stainless steel
clasp or plate.
In
addition, a 1 MΩ resistor is added to the coiled retractable cable in
order to permit high voltage charges to leak through but prevent an
electrostatic shock hazard when working with low voltage components. Subsequently,
extra resistance of 750 kΩ per 250 V is added in the ground path
to protect the wearer from excessive currents when higher voltages are present.
Wireless
Version
Today,
wireless ESD wrist straps that offer user mobility have proliferated in the
market. They work on the principles of the so-called Selgard electric halo,
corona discharge effect and skin effect. However, their reliability and
effectiveness have been subject to criticisms from the conventional grounded design
manufacturers and supporters.
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Video: ESD or Antistatic Wrist Strap
Antistatic
Wrist Strap Instruction Manual:
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