Electrostatic Discharge Protection Operations for Electronic Products
1) Antistatic Workbench
Antistatic workbench is one of the most basic components of an antistatic system. It consists of a workbench, antistatic mat, wrist strap connectors, and a grounding wire. The antistatic workbench should meet the following requirements:
(a) The workbench should be equipped with at least two wrist strap connectors, one for the operator and the other for technicians, inspectors, or other personnel.
(b) If necessary, an ionization wind static eliminator should be installed above the antistatic workbench.
2) Antistatic Wrist Strap
Antistatic wrist straps are the most important equipment for maintaining human protection and ensuring effective grounding. All personnel who directly contact electrostatic sensitive products should wear antistatic wrist straps. It should:
(a) Have good contact with human skin; the wrist strap must be non-irritating and non-allergenic.
(b) Have a quick-release connection mechanism.
(c) All external surfaces of the wrist strap are made of insulating material.
(d) The connecting wire (wrist chain) of the wrist strap is connected to the inner surface of the wrist strap. The end of the connecting wire intended for connection to the wristband should be specially marked, and a resistor with a resistance of 1 MΩ and a rated power of at least 0.25W should be connected in series at this end.
3) Antistatic Capacitors
Antistatic capacitors refer to all containers (e.g., bags, transfer boxes, printed circuit board racks, component storage boxes, etc.) used for storing and handling static-sensitive components and assemblies during the production and assembly of electronic products. The requirements for them are:
(a) They must not be made of metal or ordinary plastic.
(b) When necessary, they should be grounded when storing or transporting static-sensitive products.
4) Ionizing Wind Static Eliminator (Ionizer)
It is the main device used to eliminate static charge on insulating parts. It is required to eliminate static electricity quickly, neutralize any polarity, and maintain a good balance of positive and negative ion concentrations in the antistatic work area, with a maximum spatial potential difference of less than 100V.
5) Antistatic Work Clothes
Wearing antistatic work clothes is an important means of protecting operators from static electricity. Therefore, the following requirements must be met:
(a) Work clothing, whether in the form of outerwear, jackets, or coats, must completely cover the arms and torso when worn.
(b) Work clothing should be directly connectable to the operator's skin, or include a grounding point for connection to the earth.
(c) Work caps or headscarves should completely cover the operator's hair to prevent contact between body hair and static-sensitive components.
(d) There should be electrical continuity between all parts of the clothing.
(e) Work clothing made of pure cotton is only permitted in environments with a relative humidity greater than 50%.
6) Antistatic Work Shoes and Socks
Wearing antistatic work shoes and socks is one of the important means of maintaining static electricity protection for the human body. Especially when the use of wrist straps may pose a danger, using shoes and socks (including leggings, toes, and heels) as a means of grounding the human body for static electricity is considered a basic consideration. At this time, the resistance of the human body to ground should be maintained within the specified range (≥5×10⁴Ω, ≤3.5×10⁷Ω). This value is determined based on both human safety and the need for rapid dissipation of static charge.
7) Antistatic Transport Trolley
When used to transport unprotected electrostatic third-party components or as a moving work surface, it must have a grounding point for grounding via a conductor.
8) Flooring Materials
(a) Dissipative materials are generally used for flooring, or antistatic mats are laid on ordinary floors with effective contact.
(b) Direct use of wooden floors or laying wool, hemp, synthetic fiber carpets, and ordinary linoleum is prohibited.
(c) The use of specially treated terrazzo floors is permitted, such as pre-laying a floor grid, carbonization, or spraying an antistatic agent on the floor.
9) Ceiling and Wall Materials
Antistatic materials should be used. Generally, gypsum board or lime paint is permitted for walls; ordinary paper and plastic wallpaper are prohibited. 10) Prohibited Static Charge Materials or Equipment
The use of static charge source equipment is strictly prohibited. Within anti-static work areas, whether for directly applied materials or raw materials used in products, the use of charge source materials that easily generate static charge is prohibited, as is the use of equipment that easily becomes a static charge source.