Key elements in an ESD Program

Principles of electrostatic safe handling

There are two simple principles we can use to protect ESD sensitive components from ESD damage:

• Only handle sensitive components in an ESD Protected Area (EPA) under protected and controlled conditions
• Protect sensitive devices outside the EPA using ESD protective packaging

What is an EPA?

An EPA is an area that is maintained safe for handling static sensitive components by keeping electrostatic fields and voltages to an insignificantly low level. An EPA should have well defined boundaries so that it is clear where the safe area is entered and left.

Insulating materials are strong ESD sources and so they are excluded from the EPA where possible. Where this is not possible special measures such as ionisers are used to neutralise electrostatic charges.

All non-insulating (electrically conducting) objects are grounded, so that electrostatic charge cannot build up on these. Most importantly, all personnel (people are conductive objects!) are grounded so that they do not charge to high voltages and form an ESD source. There are two ways in which people are grounded:

• Using a grounded wrist strap (this is the preferred method)
• Using conductive footwear (conductive or dissipative shoes, or heel & toe straps on both feet) in conjunction with a grounded conductive floor.

Key elements of an effective ESD program

An effective ESD program requires four main parts:

• The ESD Program. This is a document that specifies the equipment used, and procedures followed in order to ensure electrostatic safe handling.
• The Training plan.This is required in order to make sure that everyone is aware of, and understands the ESD Program, use of equipment and correct procedures.
• The compliance verification plan. This is required in order to make sure that equipment remains functional, and that the ESD Program procedures are correctly followed.
• ESD control product Qualification.This is required to specify how ESD control eqipment will be selected for use in the ESD control program, to ensure it will have the intended properties and function.

If any of these is absent, it is likely that the ESD prevention measures will eventually fail. This is why the 61340-5-1 standard requires an ESD Control Program Plan, ESD Training Plan, Product Qualification Plan and Compliance Verification Plan be written.