Electrostatic Discharge and Protection

Electrostatic discharge (ESD) is the rapid, momentary flow of electric current that occurs when two objects at different electrostatic potentials come into contact or close proximity. A familiar example is the small spark felt after walking across a carpet and touching a metal doorknob. While harmless to people, the same event can carry thousands of volts and inject enough energy to damage or destroy semiconductor components, sometimes without any visible sign.

Charge often builds up through the triboelectric effect, in which contact and separation of dissimilar materials transfers electrons and leaves surfaces charged. Insulating materials such as plastics hold this charge readily. When a charged person or tool touches an integrated circuit, the discharge can rupture thin oxide layers, fuse tiny conductors or create latent defects that shorten a device's life. Sensitive parts include MOS transistors and many modern microchips.

Protecting against ESD combines workplace controls and circuit design. In manufacturing and repair, technicians use grounded wrist straps, conductive mats, ionisers and antistatic packaging to keep everything at the same potential. Within circuits, designers add protection structures such as clamping diodes and transient-voltage-suppression devices at exposed inputs, which safely divert discharge currents away from the delicate internal transistors. Together these measures greatly reduce field failures.

Frequently asked questions

Why is ESD dangerous to electronics but not to people?

People feel only a brief shock, but the same high-voltage discharge can punch through the microscopic insulating layers inside semiconductors, causing immediate or hidden damage.

What causes static charge to build up?

The triboelectric effect: when dissimilar materials touch and separate, electrons transfer between them, leaving the surfaces with opposite net charges.

How do technicians prevent ESD damage?

By keeping everything at the same potential using grounded wrist straps, conductive mats, ionisers and antistatic bags when handling sensitive parts.