What trouble does static electricity bring to manufacturers
Electrostatic discharge (ESD) is a source of damage to circuit boards and components in electronic assembly. It may affect the quality of each product. Although many people think that they are producing products in an ESD safe environment, in fact, ESD-related damage still brings billions of dollars in losses to all electronics manufacturing industries every year.
The charge is stable under two conditions:
1. When it "sinks into" a conductive but electrically insulating object, such as a metal screwdriver with a plastic handle.
2. When it stays on an insulating surface (such as plastic) and cannot flow on it.
However, if an electrically insulated conductor (screwdriver) with a sufficiently high charge is close to an integrated circuit (IC) with an opposite potential, the charge "crosses", causing electrostatic discharge (ESD).
ESD occurs very quickly with extremely high intensity, and usually generates enough heat to melt the internal circuits of the semiconductor chip, and looks like small bullet holes blown out under the electron microscope, causing immediate and irreversible damage. What's more serious is that this hazard is only one-tenth of the time so bad that it causes the entire component tested after * to fail. In the other 90% of cases, ESD damage causes only partial degradation-meaning that the damaged component can pass the *post-test unnoticeably, and only has premature field failure after it is shipped to the customer. The result is to damage the reputation of the manufacturer.
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.
As the main source of ESD hazards, all workers entering the electrostatic protected area (EPA, electrostatic protected area) 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 from occurring .
The main products used to prevent ESD are wristbands, which have curly corduroy and dissipative surfaces or padding-both must be properly grounded. Additional aids such as dissipative footwear or heel straps and suitable clothing are designed to prevent personnel from accumulating and maintaining a net charge when moving in the electrostatic protection area (EPA).
During and after assembly, the PCB should also prevent ESD from internal and external transportation. There are many circuit board packaging products that can be used in this area, including shielding bags, shipping boxes, and movable carts.