Static electricity is very harmful to electronic products
ESD occurs very quickly with extremely high intensity, and usually generates enough heat to melt the internal circuit of the semiconductor chip, and looks like a small bullet hole blown out under an electron microscope, causing immediate and irreversible damage. What's more serious is that only one-tenth of this hazard is so bad that it causes the entire component to fail in the final test. In the other 90% of cases, ESD damage causes only partial degradation-meaning that the damaged component can pass the final test unnoticeably, and only has premature field failure after it is shipped to the customer. The result is the worst reputation, the most costly place for a manufacturer to correct any manufacturing defect.
However, the main difficulty in controlling ESD is that it is invisible, but can reach the point of damaging electronic components. To produce an audible "tick" discharge requires a relatively large charge of about 2000 volts to accumulate, while 3000 volts can feel a small electric shock, and 5000 volts can see sparks.
For example, common components such as complementary metal oxide semiconductor (CMOS) or electrical programmable read-only memory (EPROM) can be affected by ESD potential differences of only 250 volts and 100 volts, respectively. Destruction, and more and more sensitive modern components, including Pentium processors, can be destroyed as long as 5 volts.
The problem is compounded by daily activities that cause damage. For example, walking across a vinyl factory floor creates friction between the floor surface and the shoes. The result is a purely charged object, accumulating a charge of 3 to 2000 volts, depending on the relative humidity of the local air.
Even the friction caused by the natural movement of workers on the stage can generate 400 to 6000 volts. If the worker has handled the insulator during the process of unpacking or packing the PCB in the foam box or bubble bag, the net charge accumulated on the surface of the worker's body can reach approximately 26,000 volts.
Therefore, as the main source of ESD hazards, all workers entering the electrostatic protected area (EPA) must be grounded to prevent any accumulation of charges, and all surfaces should be grounded to maintain everything at the same potential to prevent ESD occurs.