Why worry about ESD?

ESD can cause unseen damage to electronic components during manufacture of electronic assemblies and equipment. If the damaged component fails immediately, the result can be a board that fail tests and requires rework. This represents lost production and additional manufacturing costs.

Worse than this, a component may be partially damaged and weakened. It may suffer a change or drift in characteristics. It may remain within specification, but fail later when in use by a customer. It has been estimated that 90% of damaged devices may be discovered in this way. This is the most expensive type of failure, as it represents:

• Customer dissatisfaction, and the possibility of loss of product reputation and future sales

• Customer service personnel and facility cost

• Engineers time, possibly for on-site repair with travel, and parts replacement

In manual assembly most ESD arises from charged personnel, if they are not grounded.

Most people do not feel an ESD shock unless they are charged to over 4000 V (the sensitivity threshold varies between people, and even over parts of the body!). This voltage is quite common in the uncontrolled environment - how many of us have not felt the occasional electrostatic shock in everyday life?