In the workshop of SMT production line, anti-static is always a challenge. According to the statistics of American electrostatic discharge Association, about 25% of the unidentified damage in SMT line workshop is caused by electrostatic discharge, and the annual loss amount is up to 5 billion US dollars.
What is electrostatic discharge (ESD)?
Electrostatic discharge refers to the charge transfer of any object without connecting the power supply. The most common case is that when two substances contact with each other to generate charges, once they continue to accumulate to the occurrence of voltage difference, they can break through the insulator between substances (can be air or other substances), and then generate electrostatic discharge. Lightning is an obvious example.
In fact, electrostatic discharge has a long history. With the birth of semiconductor, 
the size of components is getting smaller and smaller, and this problem is becoming more and more serious.            
Electrostatic discharge can occur in different forms, ranging from small to 50 V to 
large to 1000 V. The human body can only feel more than 2000 volts of static electricity, after all, the power generated is very small, will not cause harm. However, in the electronic production line workshop, this is totally two different things.
How static electricity to destroy
The static electricity in the air will make the air ionize, and then damage the electrostatic sensitive materials. Even if the electrostatic discharge is only a few volts, it is enough to damage the semiconductor components.
Therefore, when a component is placed in an environment full of static electricity, it may be damaged. If the element itself is relatively solid, like a power diode, it can resist static electricity; however, if the element is very small and the shell is very thin, it cannot withstand the test of static electricity.
Once electrostatic discharge occurs, the current generated will be very strong. Although the time is only between one billionth of a second and one millionth of a second, in this moment, the components have been permanently damaged, which can be divided into two types: catastrophic damage and potential damage.
Catastrophic damage: when the electronic components are exposed to electrostatic discharge, the circuit is permanently damaged and the function is completely lost. Through basic inspection, it can be found that the factory needs to rework it.
Experiments provided by the advanced technology laboratory of global instruments. They applied up to 5000 watts of power to a plug-in machine being assembled with LED. Then, the Z-section of the wafer is photographed down through the LED lens directly above the wafer. The same sample only uses different amplification and lighting techniques. It can be seen that on the periphery of the Golden Disk on the chip surface, there are traces of electrostatic damage.
Potential damage: Potential damage: when the electronic components are exposed to electrostatic discharge, some circuits are damaged, the function has not been completely lost, and it is not found in the basic inspection, but the function is good or bad, and it is not known how long it can be maintained, so that the product becomes unstable. If used in medical or military products, the consequences will be very serious.