What is ESD?
Static electricity is an objective natural phenomenon that occurs in a variety of ways, such as contact, friction, and so on. Electrostatic protection technologies, such as the electronics industry, the petroleum industry, the weapons industry, the textile industry, the rubber industry, and the electrostatic hazards of the Xinghang and military fields, seek to reduce the losses caused by static electricity.
Anti-static can be divided into preventing static electricity generation and preventing electrostatic damage.
Electrostatic protection is a long-term system engineering. Any mistake or omission in any link will lead to the failure of static protection work.
The main measures for electrostatic protection during production are electrostatic leakage, dissipation, neutralization, humidification, shielding and grounding.
The human body electrostatic protection system mainly consists of anti-static wrist straps, ankle straps, overalls, shoes and socks, caps, gloves or finger sleeves. It has functions such as electrostatic leakage, neutralization and shielding.
What exactly is ESD?
Electrostatic discharge (ESD) is defined as the discharge (electron flow) of a charge (electron deficiency or excess) that has been electrostatically (fixed). The charge is stable under two conditions:
1. When it "traps" into a conductive but electrically insulated object, such as a metal screwdriver with a plastic handle.
2. When it is left on an insulating surface (such as plastic), it cannot flow on it.
However, if an electrically insulated conductor (screwdriver) with a sufficiently high charge is placed close to an integrated circuit (IC) with opposite potential, the charge "cross-static gloves"
"", causing electrostatic discharge (ESD).
ESD occurs very rapidly with very high intensity, and usually generates enough heat to melt the internal circuit of the semiconductor chip, and the small bullet holes blown outward under the electron microscope cause immediate and irreversible damage. More seriously, only one in ten of such hazards are so bad that the entire component that was tested last failed. In the other 90% of cases, ESD damage only causes partial degradation - meaning that damaged components can pass the final test without notice, and only premature field failures occur after shipment to the customer. The result is the most detrimental to the place where a manufacturer can correct any manufacturing defects.
However, the main difficulty in controlling ESD is that it is invisible, but it can reach the point of damaging electronic components. A discharge that produces a "click" sound requires a relatively large charge of about 2000 volts, while a 3000 volt can feel a small electric shock, and a 5000 volt can see a spark.
For example, a common component such as a complementary metal oxide semiconductor (CMOS) or an electrical programmable read-only memory (EPROM) can be separated by an ESD potential difference of only 250 volts and 100 volts, respectively. Destruction, and more and more sensitive modern components, including the Pentium processor, can be destroyed as long as 5 volts.
This problem is compounded by daily activities that cause damage. For example, walking through a vinyl floor, creating friction between the floor surface and the shoe. The result is a purely charged object that accumulates 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 produce 400~6000 volts. If the worker has disposed of the insulator during the disassembly or packaging of 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 a major source of ESD hazards, all personnel entering the electrostatically protected area (EPA) must be grounded to prevent any charge buildup and all surfaces should be grounded to maintain everything at the same potential, preventing ESD occurs.