Electrostatic discharge (ESD): A high voltage pulse induced into a device as a result of its coming in contact with or in proximity to an electrically charged object. In very dry climates, charges build up on any moving object including people. These charges may pass (discharge) to an electronic device when the charged body comes into proximity with it.
A device is said to be ESD-sensitive if this passage of charge does harm to the device in any way. In the resistor-world, generally, ESD sensitivity is related to the function of the resistor’s size. The smaller the resistor, the less space there is to spread the energy pulsed through it from the ESD. This energy concentration in a small area of a resistor’s active element causes it to heat up, which could lead to irreversible damage. With the growing trend of miniaturization, electronic devices, including resistors, are becoming smaller and smaller, causing them to be more prone to ESD damage.
Pulse withstanding resistors, like Riedon’s PCR series, are specifically designed to handle such large-volt discharges and are still available in small-package chip sizes.