Purpose and reference standard of electrostatic test

The purpose of electrostatic discharge testing is to test the ability of a single device or system to resist electrostatic interference. It simulates: the discharge of the operator or object in contact with the equipment; The discharge of a person or object against a neighboring object.

Possible consequences of electrostatic discharge:

（1）Damage of semiconductor devices caused directly by energy exchange;

（2）Electric field and magnetic field changes caused by discharge, resulting in equipment misoperation;

（3）The noisy current of the discharge causes the misoperation of the device.

Esd test reference standard: IEC61000-4-2, corresponding to GB/T 17626.2.

Basic circuit and discharge current waveform of electrostatic discharge generator

> Cd+Cs stands for human energy storage capacitor, and 150pF is considered to be appropriate;

>Rd represents the source resistance when the human body holds a metal object such as a key or a tool. A 330 ω resistor can be selected. It has been proved that this metal discharge condition is sufficient to strictly represent the discharge of various personnel in the field.

Method of static electricity test

The electrostatic discharge test includes contact discharge and air discharge, and the discharge points include all contact surfaces.

Air discharge is used for insulating surfaces and contact discharge is used for metal surfaces.

The metal head of the electrostatic discharge generator should usually be perpendicular to the surface of the device under test. The test times are divided into positive and negative polarity, at least 10 times each discharge, and the test interval is generally about 1s. Before and after the electrostatic discharge test, the function to be tested should be monitored to determine whether it is qualified.

Electrostatic test level requirements

> For general consumer products, 4KV contact and 8KV air are usually used as test standards.

> For industrial products, electrostatic test grade is generally in accordance with the third grade test, that is, contact 6KV, air 8KV; High requirements with the fourth level as the test standard, that is, contact 8KV, air 15KV.

> Some products in other industries or specific customers will also use their own defined test standards for electrostatic testing.