Electrostatic

Discharge

Objectives:

What Is Electrostatic Discharge (ESD)?

Principles ◦ Triboelectrification

◦ Charging by Induction

Factors effecting ESD

Prevention of ESD

The

Electrostatic

Discharge is

defined as the

sudden transfer of

electro static

charges between

bodies at different

potentials caused

by direct contact or

induced electro

WHAT IS ESD?

Basic Principles

•Triboelectrification

•Charging by Induction

Triboelectrification

A type of contact electrification.

Charging of bodies due to the fictive

contact.

Triboelectric Series:

Human hair get

positively charged

if it is combed by a

hard rubber comb.

When two materials are in intimate contact, they

share electrons which are at their surfaces.

When materials are in contact

It is possible for electrons to be “stolen” from one

material by nuclei in the other material, because they

have a stronger force

When these materials are separated, electrons are

removed from one material and are transferred to the

other material.

When the materials are

separated

Electrons “lost”

Electrons “gained”

Charging by induction

The presence of this very strong force

causes similar charges on the surfaces of

nearby conductors to be repelled.

The charge imbalance on a surface

produces an electric field.

Charging by induction

If the conductor is grounded while it is still

influenced by the electric field, these repelled

charges go to earth, thus maintaining a charge

balance in the areas of the conductor that are

not affected by the electric field.

FACTORS:

•Type of Material

•Relative Humidity

•Posture of body

•Type of cloth

•Body resistance

A person who walks

across a synthetic

carpet gets

triboelectrified with

positive charge.

Prevention: