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Electronic equipment manufacturing anti-static technical requirements

Update:16-09-2022
Summary:

1. Subject content and scope of application This standa […]

1. Subject content and scope of application This standard specifies the basic technical requirements for protection against electrostatic discharge hazards in the entire process of development and production of electronic equipment; the requirements for anti-static operation during the procurement, testing, storage, transportation, and assembly of electrostatic sensitive devices. Anti-static work area management and personnel education and training.
This standard applies to electrostatic protection in the development, production, maintenance of electronic equipment and the procurement, storage, transportation and testing of electronic components.
2 Reference standards
GB 2887-89 Technical conditions of computing station site
GB4385-1995 Technical requirements for anti-static rubber-soled shoes and conductive rubber-soled shoes
GB12014-89 Anti-static work clothes
Industrial enterprise communication grounding design specification
Implementation of GJB1210 Grounding, Bonding and Shielding Design
GJB1649-1993 Outline of Anti-static Discharge Control for Electronic Products
3 Terminology
3.1 Electrostatic electrostatics
The excess or deficiency of static charge on the surface of an object.
3.2 Electrostatic discharge (ESD)
When the energy of the electrostatic electric field reaches a certain level, it breaks down its basic properties and discharges
3.3 Electrostatic susceptivity
The electrostatic discharge voltage value that the component can withstand.
3.4 Static Sensitivity Device (SSD)
Devices sensitive to electrostatic discharge.
Note: For the sensitivity classification of electrostatic sensitive devices, please refer to Appendix A of GJB 1649-93.
3.5 leakage
Safely conduct static charges to ground.
3.6 Neutralization
Use conductive charges to make static electricity disappear.
3.7 Electrostatic conductor
Approved by the Ministry of Electronics Industry of the People's Republic of China on 1994-08-08 and implemented on 1994-12-01 SJ /T 10533-94 Objects with surface resistance values ​​in the range of 105 to 1010.
3.8 Ground ground g
Electrically connected to objects that can provide or receive a large amount of electrical charge (such as the earth, the metal shell of a ship or a vehicle, etc.).
3.9 Anti-static work area static safe area
The workplace is formed by various anti-static facilities, devices and clear area boundaries.
4 Basic requirements
4.1. Basic principles of electrostatic protection
a. Inhibit the accumulation of static charges;
b. Quickly, safely and effectively eliminate the static charge that has been generated.
4, 2 Anti-static work area site
4.2.1 Floor material
4.2.1.1 It is forbidden to directly use wooden floor or lay wool, linen, chemical fiber carpet and ordinary floor leather.
4.2.1.2 The ground made of electrostatic conductor material should be selected, such as anti-static raised floor or laying anti-static mat on common ground, and grounded effectively.
4.2, 1.3 It is allowed to use specially treated terrazzo floor, such as laying ground wire mesh, carburizing or spraying antistatic agent on the floor in advance.
4.2.2 Grounding
4.2.2.1 The anti-static system must have an independent and reliable grounding device, the grounding resistance should generally be less than 10Ω, and the burying and detection methods should meet the requirements of GJB1210.
4.2.2.2 The anti-static ground wire shall not be connected to the neutral wire of the power supply and shall not be shared with the lightning protection ground wire.
4.2.2.3 The three-phase five-wire system is used for power supply, and the ground wire can be used as an anti-static ground wire (but the neutral wire and the ground wire should not be mixed).
4.2.2.4 The cross-sectional area of ​​the grounding trunk line shall not be less than 100mm2, and the cross-sectional area of ​​the branch trunk line shall not be less than 6mm2. The grounding wire of the equipment and workbench shall be multi-strand plastic-coated conductors with a cross-sectional area of ​​not less than 1.25mm2, and the color of the grounding wire shall be The yellow-green line is appropriate.
4.2.2.5 The connection method of the grounding trunk line shall be brazing.
4.2.2.6 The connection terminals of anti-static equipment should ensure reliable contact, easy to assemble and disassemble, and allow the use of various clip-type connections to aluminum, such as fish clips, plug sockets, etc.
4.2.3 Ceiling materials
The ceiling material should be made of antistatic materials. Generally, gypsum board products are allowed, and ordinary plastic products are prohibited.
4.2.4 Wall fabric
Antistatic wallpaper should be used for wall fabrics. Generally, gypsum paint or lime paint is allowed for walls, and ordinary wallpaper and plastic wallpaper are prohibited.
4.2.5 Humidity control
4.2.5.1 The relative humidity of the anti-static work area should not be lower than 50%.
4.2.5.2 On the premise of not causing harmful effects to the product, it is allowed to use humidifying equipment to spray formulations or water to increase the ambient humidity.
4.2.5.3 The humidity of the computer room should comply with the relevant regulations in GB 2887, and similar computer rooms should also comply with this regulation.
4.2.6 Regional boundaries
The anti-static work area should be marked with the area boundaries, and warning signs should be hung in obvious places. The warning signs should comply with the provisions of GJB 1649. The entrance of the work area should be equipped with ionized air air bath equipment.
4.2.7 Charge Source
It is forbidden to use and contact the charge source that is easy to generate static charge in the anti-static work area.
4.3 Anti-static facilities
4.3.1 Electrostatic safety workbench
4.3.1.1 The electrostatic safety workbench is the basic part of the anti-static work area. It consists of a workbench, an anti-static table pad, a wrist strap connector and a ground wire.
4.3.1.2 There should be no less than two wrist strap connectors on the anti-static desk pad, one for operators and the other for technicians, inspectors or other personnel.
4.3.1.3 If necessary, an ion wind static eliminator should be provided on the static safety workbench.
4.3.1.4 It is not allowed to stack plastic boxes (sheets), rubber, cardboard, glass and other sundries that are prone to static electricity on the electrostatic safety workbench.
4.3.2 Anti-static wrist strap
Personnel who are in direct contact with electrostatic sensitive devices should wear anti-static wrist straps. The wrist strap should be in good contact with human skin. The wrist strap must have no irritation or allergic effect on the human body. The resistance value of the wrist strap system to ground should be 106-108 ohms. within the range.
4.3.3 Anti-static container
In the process of development and production of electronic equipment, all containers for storing and revolving SSDs (component bags, transfer boxes, printed board racks, component storage boxes, etc.) should have electrostatic protection properties. Metal and ordinary plastic containers are not allowed. When necessary, the turnover box for storing components should be grounded.
4.3.4 Ion wind static eliminator
To eliminate the static charge on the surface of the insulating material, an ion wind static eliminator should be used.
4.3.5 Anti-static work clothes
4.3.5.1 Entering the anti-static work area or touching the SSD. Personnel should wear anti-static work clothes, and the fabric of anti-static work clothes should comply with GBl2014 regulations.
4.3.5.2 In an environment with a relative humidity greater than 50%, anti-static work clothes are allowed to use pure cotton products.
4.3.6 Anti-static work shoes
Personnel entering the anti-static work area or touching SSD should wear anti-static work shoes, and the anti-static work shoes should comply with the relevant provisions of GB:4385. Under normal circumstances, ordinary shoes are allowed, but conductive shoe bundles or heel straps should be used at the same time.
4.3.7 Anti-static transport vehicle When transporting SSD or whole or components containing SSD, a transport vehicle with anti-static performance should be used.

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