Electrostatic Discharge (ESD) testing is an essential part of product design.  Static electricity if familiar to all of us, from the shock we get when walking on a carpet, to the trick we use to amuse children by rubbing a balloon on our clothing and sticking it to the side of our head.

In a lab you will see staff wearing wrist staps to eliminate the risk of static damage to circuit boards, however out in the real word there are no such things. Our designs must therefore be able to withstand such shocks, and also not to deliver them to other electronics that they come into contact with.  Bear in mind that we don’t always know exactly where our devices will be used in the real world.  For example in a flour mill or an oil rig, there may be components in the air that could cause an explosion if ignited by a stray spark from a poorly designed device.  Simple design mistakes can have huge cost consequences. When you multiply a mistake through mass production, the cost of field visits to multiple remote locations to replace or repair them will wipe out any profit.  The financial and reputational consequences of any accidents are another factor to consider.

ESD testing can be performed in two ways:  in the contact method the test instrument is in contact with the target device; in the air method there is a free air gap.  The latter case is more realistic, however it needs to take into account the real world effects of heat, humidity and distance and any movement relative to the charge, making the test more complex.

There are many different ESD test specifications, so understanding the correct ones to use in testing your device is important to make sure it is fit for purpose in your chosen application area.