EPA control of electrostatic protection work area
A working environment where the electrostatic voltage of materials and equipment is controlled. In order to protect the electrostatic sensitive device (ESSD) from electrostatic damage, the area where necessary anti-static materials and equipment are used to establish and equip, usually has obvious anti-static warning signs. Personnel entering the anti-static work area must strictly follow the anti-static work regulations. Also known as ECA (ESD controlled area)
In general electronic equipment production, assembly and maintenance sites, various static electricity generating materials and the electric field generated by them are very common phenomena. These static electricity generating materials and the electric field generated by them may cause damage to electrostatic sensitive devices. Therefore, the electrostatic sensitive device must be protected during the entire use process.
In the storage and transfer process of electrostatic sensitive devices, a conductive container with shielding performance can provide the necessary protection. However, there are also operations outside the shielded container for electrostatic sensitive devices. In this case, electrostatic sensitive devices are very susceptible to damage. Therefore, it is necessary to provide a safe working area. The Anti-Static Work Area (EPA) is designed for this purpose. In order to ensure the anti-static safety of the workbench, it must meet the following requirements:
⑴ All electronic components in the anti-static area must be treated as electrostatic sensitive devices.
⑵ Any operation of electrostatic sensitive devices outside the protection state (outside the Faraday cage) must be carried out in the anti-static work area.
⑶ Electrostatic sensitive devices transported in the non-antistatic area between the antistatic work areas must be in a safe protection state.
⑷ The design of the anti-static work area should be able to ensure that the electrostatic sensitive devices are not easy to touch the metal grounding shell of the equipment.
⑸ It is forbidden to place static-generating materials that are not necessary for work in the anti-static work area, such as plastic bags, boxes, foams, belts, notebooks, paper sheets, and personal items that are not treated with anti-static treatment. These materials must be 30 Cm above.
⑹ All cleaning agents, solvents, coating materials, aerosols and other auxiliary materials used on the workbench must be approved by the person in charge of static control.
2 EPA division and environmental requirements
2.1 EPA division
The division of anti-static area is based on whether there may be static-sensitive items in the area as the criterion. As long as static-sensitive items may appear, it should be defined as an anti-static area, otherwise it can be defined as a non-anti-static area. The boundary of the anti-static area is determined by the process department and the person in charge of the area anti-static.
The anti-static work area (EPA) includes but is not limited to the following areas: IQC inspection area, veneer processing and inspection area, veneer test and inspection area, component assembly and inspection area, whole machine assembly and commissioning area, maintenance area, test Area, tally area, component and material distribution area, storage area, etc.
The EPA should be classified according to the electrostatic sensitivity level of the materials operated in the area and the risk of electrostatic discharge during production. Refer to the requirements in section 3.1.
2.2 EPA's basic environmental requirements
When designing the EPA environment, the following principles should be followed in order to meet the requirements of electrostatic protection:
⑴ Inhibit the accumulation of static charge and the generation of static voltage.
⑵ Safely, quickly and effectively eliminate the generated static charge.
⑶ Determine the degree of electrostatic protection that should be achieved. For example, the absolute dui value of electrostatic voltage in yi-level EPA should be less than 100V.
Therefore, EPA must have the following basic environmental requirements:
⑴ Clear regional boundaries and anti-static warning signs.
⑵ Reliably ground all conductors in the area, including personnel.
⑶ Eliminate all unnecessary sources of static electricity.
⑷ Use the 12-inch principle, that is, the ESSD device must be at least 30 cm away from the static power source.
At the same time, the anti-static performance of the following surrounding environment needs to be considered:
Antistatic wallpaper should be used for wall fabrics. Generally, plaster paint or lime paint for walls is allowed, and ordinary plastic products are prohibited.
The ceiling material should be made of antistatic materials. Generally, gypsum board products are allowed, and ordinary plastic products are prohibited.
Door curtains, curtains, and regional isolation curtains used in the work area should be made of anti-static materials, and the surface resistance value should be less than 1×1011Ω. The use of ordinary plastic and chemical fiber products is prohibited.