How to protect electronics factories and semiconductor manufacturers from static electricity
1. The generation of static electricity is mainly in the following aspects:
(1) The activities of the human body, the static electricity generated by the friction, contact and separation between people and clothes, shoes, socks and other objects are one of the main static electricity sources in the manufacture of electronic products.
(2) When the chemical fiber or cotton work clothes rub against the work surface or the chair, it can generate an electrostatic voltage of more than 6000V on the surface of the clothing, and make the human body charged. At this time, when it comes in contact with the device, it will cause discharge and easily damage the device,
(3) The insulation resistance of rubber or plastic shoe soles is as high as 1013Ω. When rubbing against the ground, static electricity is generated and the human body is charged.
(4) When the devices encapsulated by resin, paint film, and plastic film are put in the packaging for transportation, the friction between the surface of the device and the packaging material can generate an electrostatic voltage of hundreds of volts, which discharges sensitive devices.
(6) Ordinary work surface is subject to friction to generate static electricity.
(7) The insulation resistance of insulating ground such as concrete, waxed and polished floor, and rubber sheet is high, and the static charge on the human body is not easy to leak.
In the manufacture of electronic products, it is impossible not to generate static electricity. The generation of static electricity is not the hazard, but the hazard lies in the accumulation of static electricity and the resulting electrostatic discharge.
So pay attention to static electricity protection in the above several places.
2. The basic principles of electrostatic protection are: a. Inhibit the accumulation of static charge; b. Eliminate the static charge that has been generated quickly, safely and effectively. The specific measures are as follows:
1. Grounding: Grounding is the direct discharge of static electricity to the ground through a wire connection. This is the *direct* effective method of anti-static measures. The conductor is usually grounded, such as a rope anti-static wrist strap, floor and The work surface is grounded, etc.
The grounding is implemented by the following methods:
1) The human body is grounded through the wrist strap.
The human body is grounded through anti-static shoes (or shoe laces) and anti-static floor.
3) Ground the work surface.
4) The test instrument, tool holder, and soldering iron are grounded.
5) Anti-static floor, ground (bench) pad is grounded.
6) Anti-static turnover carts, boxes and frames are grounded.
7) The anti-static chair is grounded.
2. Electrostatic shielding: Electrostatic sensitive components will be exposed to static electricity during storage or transportation. The method of electrostatic shielding can weaken the influence of external static electricity on electronic components. *The usual method is to use electrostatic shielding bags and anti-static The turnover box serves as protection. In addition, the anti-static clothing has a certain shielding effect on the clothes of the human body.
3. Ion neutralization: Insulators are often prone to generate static electricity. To eliminate static electricity from insulators, grounding is ineffective. The usual method is ion neutralization (partially shielded), that is, in the working environment.