How to scientifically understand the electrostatic protection of electronic equipment
Why should we prevent static electricity? That is due to the rapid development of electronic equipment, small-scale, high-integration devices have been mass-produced, resulting in smaller and smaller wire spacing, thinner and thinner insulating films, and lower and lower breakdown voltages. However, the static eliminator voltage generated by electronic equipment during production, transportation, storage, and transshipment far exceeds its breakdown voltage threshold, which may cause breakdown or failure of the device, affecting the technical indicators of the equipment and reducing its reliability. This shows that static electricity is a major obstacle in the development of the electronics industry. Therefore, the static eliminator must be mentioned on the agenda to ensure the quality of the equipment.
In order to protect electronic devices and equipment from static electricity hazards during the process of purchase, storage, shipping, inspection, storage, commissioning and installation, it is very necessary and important to understand the mechanism of static electricity generation and some related knowledge to prevent static electricity of. Because electromagnetic radiation is colorless, odorless and invisible, it can penetrate a variety of substances including the human body, and various electronic automation equipment, communication tools such as radar stations, satellite stations, computers, etc., as long as they are in operation, there are electromagnetic fields around them radiation. The harm of electromagnetic energy with larger energy to the human body mainly includes: affecting the cardiovascular system, manifested as palpitations, insomnia, leukopenia, etc .; affecting the visual system, manifested as decreased vision, induced cataracts, etc .; affecting the human circulatory system, immunity and Metabolic function. Most of the harm caused by electromagnetic waves to the human body is caused by the lack of relevant knowledge of the parties. When the weaponry is manufactured and shipped, its radiation frequency, radiation range, and operating procedures are clearly defined. In general, as long as the operators strictly follow the regulations, electromagnetic radiation can be reduced to the minimum that the human body can bear. In the process of using the new equipment, how can we reduce or avoid excessive electromagnetic radiation to the human body? Common methods are as follows:
(1) Use protective equipment to shield radiation. Many substances have a good function of blocking and absorbing radiation. Without affecting the operation of the equipment, using these substances as a separator between the person and the radiation source can play a very good protective role. For example, for officers and soldiers who have been dealing with radio and radar stations for a long time, as well as personnel who must deal with radiation sources due to work needs on medical and scientific research fronts, timely distribute shielding protective clothing for electromagnetic radiation to minimize electromagnetic radiation. Outside the body; install electromagnetic radiation protection screens for static eliminator electrical equipment with display screens such as radars and satellite vehicles; wear anti-radiation glasses to operators to prevent the electromagnetic waves radiated from the screen from directly acting on the human body, etc., so that Realize effective shielding.
(2) Reduce radiation through scientific organization training. Units with limited conditions cannot be shielded and protected by long-distance or short-time training. In general, equipment such as radar vehicles, relay vehicles, and communication interference vehicles should be strictly implemented in accordance with the teaching materials. If you need to use them for a long time, you should pay attention to changing shifts or taking a break every interval to reduce the radiation exposure to the operator. influences. When the equipment is suspended, it is best to turn off the power and not to stand by.
(3) Minimize the radiation intensity of the radiation source. During training, the training equipment should be properly matched. In particular, communications equipment, satellite vehicles, relay vehicles and other equipment that are prone to generate electromagnetic waves should not be concentrated together for training. In addition, when training, try to adjust the power of the equipment to the lowest gear that can guarantee the training, to avoid artificially increasing the radiation intensity.
In addition, preventive measures taken to prevent personal electric shock, fire and explosion, electronic device failure and damage caused by the accumulation of static electricity, and adverse effects on production. The precautionary principle is to suppress the generation of static electricity, accelerate the leakage of static electricity, and neutralize static electricity. When people wear non-conductive shoes, charges will be generated and accumulated due to activities such as walking, and can reach a potential of kilovolts. When two different objects are in contact with each other, a charge movement occurs at the interface, and positive and negative charges are arranged relative to each other to form an electric double layer. If the objects are separated, equal charges with different polarities will be generated on the two objects. The principle of preventing such static electricity is to eliminate the main factors that generate static electricity (object characteristics, surface state, charging history, contact area and pressure, separation speed, etc.) as much as possible; make the objects in contact with each other in the charging sequence The position should be as close as possible; the contact area and pressure between the objects should be small, the temperature should be low, the number of contacts should be small, the separation speed should be small, and the contact state should not change drastically. Powder, liquid and gas will generate static electricity due to friction during transportation. Therefore, it is necessary to limit the flow velocity and reduce the bending of the pipeline. Increase the diameter, avoid vibration and other measures.
In addition to reducing speed, pressure, friction and contact frequency, selecting appropriate materials and shapes, increasing conductivity and other suppression measures, the static eliminator can also take the following measures: ① grounding. ② Lap (or jump). ③Shield. ④Use an antistatic agent for insulators that can hardly leak static electricity to increase the conductivity and make static electricity easy to leak. ⑤Use spraying, watering and other methods to increase the environmental humidity and suppress the generation of static electricity. ⑥ Use a static eliminator to neutralize static electricity.
In order to protect electronic equipment from static electricity during shipping, storage, storage, commissioning and installation, it is very necessary and important to understand the mechanism of static electricity generation and some related knowledge to prevent static electricity from harm.
Ways to eliminate static electricity in the production process of electronic equipment.
The static eliminator is mainly to prevent static discharge. Controlling electrostatic discharge should start with controlling the generation of static electricity and controlling the elimination of static electricity. Controlling the generation of static electricity is mainly to control the process and the selection of materials in the process; controlling the elimination of static electricity is mainly to accelerate the leakage and neutralization of static electricity. The combination of these two points can make the electrostatic voltage not exceed the safety threshold to achieve the purpose of electrostatic protection.
Static electricity can cause damage to electrostatic sensitive devices, but it is controllable and can be eliminated. To this end, it is necessary to discuss the safe working principle of the electrostatic protection system in the production process, as well as the static eliminator and the protection method of static electricity.
1. The characteristics of static eliminator To eliminate static electricity, the basic idea of static electricity protection must be clear:
① Prevent the accumulation of static electricity in places where static electricity may be generated. That is to take certain measures to avoid or reduce the generation of electrostatic discharge. The method of generating side leakage can be used to achieve the purpose of eliminating charge accumulation.
② Accumulation of existing charges should be eliminated quickly. When an insulating object is charged, the charge cannot flow and cannot be leaked. The static eliminator can be used to generate the opposite ions to neutralize the static charge. When the charged object is a conductor, a simple method of ground leakage is used to completely eliminate the charged. To form a complete electrostatic safe working area, at least include an effective static pad, special ground wire, and anti-static wrist strap.
2. The basic protection of static electricity The control technology of static electricity is to take comprehensive measures to control the harm of static electricity within the allowable range when the accumulation of static electricity is inevitable.
① Process control method aims to generate as little static charge as possible during the production process. Precautions should be taken in the process of material selection, equipment installation and operation management in the process flow to control the generation of static eliminators and the accumulation of charge, suppress the electrostatic potential and discharge energy, and minimize the harm.
② Leakage method aims to eliminate static charges through leakage. Generally, the static eliminator is grounded to leak the charge to the ground, and the static electricity is usually leaked by increasing the conductance of the object.
③ Electrostatic shielding method uses a grounded shield to isolate the charged body from other objects, so that the electric field of the charged body will not affect other surrounding objects. This shielding method is called inner field shielding. Sometimes the grounded shield is used to surround the isolated object to protect the isolated object from the external electric field. This shielding method is called external field shielding.
④ Compound neutralization method and others Through the compound neutralization method to achieve the elimination of static charge. Normally, the opposite ions generated by the static eliminator are used to neutralize the charge of the charged body, and it may make the surface of the charged object smooth and the surrounding environment cleaner, thereby reducing the possibility of tip discharge.