ESD Considerations

One of the most frequent causes of damage to a solidstate component or integrated circuits is the electrostatic discharge (ESD) from the human body when one of these devices is handled. Careless handling of line replaceable units (LRUs), circuit cards, and discrete components can cause unnecessarily time consuming and expensive repairs. This damage can occur if a technician touches the mating pins for a card or box. Other sources for ESD can be the top of a toolbox that is covered with a carpet. Damage can be avoided by discharging the static electricity from your body by touching the chassis of the removed box, by wearing a grounding wrist strap, and exercising good professional handling of the components in the aircraft. This can include placing protective caps over open connectors and not placing an ESD sensitive component in an environment that will cause damage. Parts that are ESD sensitive are typically shipped in bags specially designed to protect components from electrostatic damage.

Other precautions that should be taken with working with electronic components are:

  • Always connect a ground between test equipment and circuit before attempting to inject or monitor a signal.
  • Ensure test voltages do not exceed maximum allowable voltage for the circuit components and transistors.
  • Ohmmeter ranges that require a current of more than one milliampere in the test circuit should not be used for testing transistors.
  • The heat applied to a diode or transistor, when soldering is required, should be kept to a minimum by using low-wattage soldering irons and heatsinks.
  • Do not pry components off of a circuit board.
  • Power must be removed from a circuit before replacing a component.
  • When using test probes on equipment and the space between the test points is very close, keep the exposed portion of the leads as short as possible to prevent shorting.

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