Electrostatic Discharge - I

ESD is something we come across in normal life, from lightning to the sudden shock experienced while touching certain materials. We however are interested more in the electronic kind, which causes our devices to malfunction. We also will see the types of ESD to expect in electronic devices, the models used in simulation and the various protection measures implemented in today's chips. The device should be protected during manufacturing, testing, transport and while assembling the device as human body among other things can cause an ESD event destroying the device.

Let's go back to basic and see what causes an electro static discharge.

  1. Static Electricity
    Any matrial can cause static electricity to build up. For examples when some materials are rubbed together charges accumulate on them(or redistribute). If such a charged materail, say a human hand or an electric probe were to come in contact with an electronic device, an ESD even can occur due to the discharge path found.
  2. Electrostatic induction
    Another cause of ESD damage is through electrostatic induction. This occurs when an electrically charged object is placed near a conductive object isolated from the ground. The presence of the charged object creates an electrostatic field that causes electrical charges on the surface of the other object to redistribute. Even though the net electrostatic charge of the object has not changed, it now has regions of excess positive and negative charges. An ESD event may occur when the object comes into contact with a conductive path.