Electrostatic Discharge (ESD) Practices

Various electrical and electronic components are vulnerable to ESD. These include discrete components, hybrid devices, Integrated Circuits (ICs) and Printed Circuit Boards (PCBs) assembled with these devices.

Handling ESD Sensitive Devices

ESD sensitive devices must only be handled in static controlled locations. Some recommendations for such handling practices follow:

  • Handling areas must be equipped with a grounded table, floor mats and wrist strap.

  • A relative humidity level must be maintained between 20% and 80% non-condensing.

  • No ESD sensitive board or component should be removed from its protective package, except in a static controlled location.

  • A static controlled environment and correct static control procedures are required at both repair stations and maintenance areas.

  • ESD sensitive devices must be handled only after personnel have grounded themselves via wrist straps and mats.

  • Boards or components should never come in contact with clothing, because normal grounding cannot dissipate static charges on fabrics.

  • A circuit board must be placed into a static shielding bag or clamshell before being removed from the work location and must remain in the protective enclosure until it arrives at a static controlled repair/test center.

  • Circuit boards must not be changed or moved needlessly. Handles may be provided on circuit boards for use in their removal and replacement; care should be taken to avoid contact with the connectors and components.

  • On-site repair of ESD sensitive equipment should not be undertaken except to restore service in an emergency where spare boards are not available. Under these circumstances repair station techniques must be observed. Under normal circumstances a faulty or suspect circuit board must be sent to a repair center having complete facilities or to the manufacturer for exchange or repair.

  • Where protective measures have not been installed, a suitable alternative would be the use of a Portable Field Service Grounding Kit (for example, 3M Kit #8501 or #8507). This consists of a portable mat and wrist strap which must be attached to a suitable ground.

  • A circuit board in a static shielding bag or clamshell may be shipped or stored in a cardboard carton, but the carton must not enter a static controlled area such as a grounded or dissipative bench top or repair zone. Do not place anything else inside the bag (for example, repair tags).

  • Treat all PCBs and components as ESD sensitive. Assume that you will damage the PCB or component if you are not ESD conscious.

  • Do not use torn or punctured static-shielding bags. A wire tag protruding through the bag could act as a "lightning rod", funneling the entire charge into the components inside the bag.

  • Do not allow chargeable plastics, such as binders, within 0.6 m of unshielded PCBs.

  • Do not allow a PCB to come within 0.3 m of a computer monitor.

Prime Static Accumulators

Table: Static-Accumulating Materials provides some background information on static accumulating materials.

Static-Accumulating Materials

Work Surfaces

  • formica (waxed or highly resistive)

  • finished wood

  • synthetic mats

  • writing materials, note pads and so on


  • wax-finished

  • vinyl


  • common clean room smocks

  • personal garments (all textiles)

  • non-conductive shoes


  • finished wood

  • vinyl

  • fiberglass

Packing and handling

  • common polyethylene bags, wraps, envelopes and bubble pack

  • pack foam

  • common plastic trays and tote boxes

Assembly, cleaning and repair areas

  • spray cleaners

  • vacuum desoldering iron

  • common soldering irons

  • common solvent brushes (synthetic bristles)

  • cleaning, drying and temperature chambers

Handling Printed Circuit Boards

ESD damage to unprotected sensitive devices may occur at any time. ESD events can occur far below the threshold of human sensitivity. Follow this sequence when it becomes necessary to install or remove a circuit board:

  1. After you are connected to the grounded wrist strap, remove the circuit board from the frame and place it on a static controlled surface (grounded floor or table mat).

  2. Remove the replacement circuit board from the static-shielding bag or clamshell and insert it into the equipment.

  3. Place the original board into the shielding bag or clamshell and seal it with a label.

  4. Do not put repair tags inside the shielding bag or clamshell.

  5. Disconnect the wrist strap.