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Microscopically, microscopically, according to atomic physics theory, when electricity is neutral, the substance is in an electrical equilibrium state. Because of the gain and loss of electrons generated by the contact of different substances, the material loses its electrical balance and generates static electricity. From a macroscopic point of view, the causes are: friction between objects, heat generation, excitation of electron transfer; contact and separation between objects to produce electron transfer; electromagnetic induction causes an imbalance in the surface charge of the object; the combined effect of friction and electromagnetic induction.
The electrostatic voltage is generated by the contact and separation of different kinds of substances. This effect is known as triboelectric charging, and the voltage generated depends on the nature of the material itself that rubs against each other. In the actual production process, the LED display mainly generates static electricity by direct contact and indirect contact between the human body and related components. Therefore, according to the characteristics of the industry, we can do some targeted static precautions.
Harm of static electricity in the production process of LED display If the anti-static is ignored in any part of production, it will cause the electronic equipment to malfunction or even damage it.
When the semiconductor device is placed alone or mounted in a circuit, even if it is not powered, permanent damage to these devices may occur due to static electricity. As we all know, LED is a semiconductor product. If the voltage between two pins or more pins of the LED exceeds the breakdown strength of the component medium, it will cause damage to the component. The thinner the oxide layer, the greater the sensitivity of the LED and the driver IC to static electricity. For example, the solder is not full, the quality of the solder itself is problematic, etc., which can cause serious leakage paths and cause devastating damage.
Another type of failure is caused by the temperature of the node exceeding the melting point of semiconductor silicon (1415 Â° C). The pulse energy of static electricity can generate localized heat, so there is a direct breakdown of the lamp and the IC. This failure occurs even if the voltage is lower than the breakdown voltage of the medium. A typical example is that the LED is a diode composed of a PN junction, and the breakdown between the emitter and the base causes a sharp drop in current gain. After the LED itself or the IC in the driver circuit is affected by static electricity, functional damage may not occur immediately. These potentially damaged components are usually displayed during use, so the life of the display is affected. It is fatal.
Protective measures against static electricity in the production process of LED display 1. Grounding is to directly discharge static electricity to the earth through the wire connection. This is the most direct and most effective anti-static measure. For the conductor, the grounding method is usually used. Use the tool grounding, grounding anti-static wrist strap, and work surface grounding.
(1) In the production process, workers are required to wear a grounded electrostatic wristband. Especially in the process of cutting feet, inserts, commissioning and post-welding, and monitoring, quality personnel must do a static test of the bracelet at least every two hours to make a test record.
(2) When soldering, the soldering iron should use anti-static low-voltage soldering iron as much as possible, and maintain good grounding.
(3) In the assembly process, use a low-voltage DC electric screwdriver with a grounding wire (commonly known as electric batch).
(4) Ensure effective grounding of production pull-up, glue-filling station, aging frame, etc.
(5) We require the production environment to lay copper wire grounding, such as floors, walls, and ceilings used in some occasions, etc., should use anti-static materials. Usually, even ordinary plasterboard and lime paint walls are acceptable, but plastic ceilings and ordinary wallpaper or plastic wallpaper are prohibited.
Second, the embedding of anti-static ground wire:
(1) The lightning rods of the building buildings are generally welded to the reinforced concrete of the building to be properly grounded. When lightning strikes occur, the grounding point and even the ground of the entire building will become the discharge point of high voltage and high current. It is generally believed that there will be a "step voltage" in the range of 20M of the bleed ground point, that is, it is no longer an ideal zero potential in this range. In addition, since the neutral line of the three-phase power supply cannot be absolutely balanced and there is an unbalanced current generated and flows into the grounding point of the neutral line, the buried point of the anti-static ground line should be 20 meters away from the building and equipment.
(2) Buried method: In order to ensure the reliability of the grounding, there should be more than three points of grounding, that is, digging 1.5m deep pits every 5m, and driving more than 2m iron pipes or angle iron into the pit (that is, the angle iron is inserted more than 2m underground) Then, the three places were welded together with a 3 mm thick copper row, and the inner wire was introduced into the room by a 16 m2 insulated copper core wire.
(3) Apply appropriate amount of charcoal powder and industrial salt to the pit to increase the conductivity of the soil. After landfill, measure with grounding resistance tester. The grounding resistance should be less than 4Î© and tested at least once a year.
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Yangzhou IdealTek Electronics Co., Ltd. , https://www.idealtekpower.com