We know that static electricity is everywhere in the manufacturing of electronic products. In fact, there is nothing static electricity itself. Any object may generate static electricity if it is constantly rubbed. Even our human body will generate static electricity. So today we are going to discuss how to prevent static electricity. The following Sanjing will let you understand:

Before introducing the anti-static measures, let's first understand the principle of electrostatic protection: prevent the accumulation of static electricity in the place where static electricity may occur, and quickly eliminate the existing static electricity accumulation and release it immediately. The electrostatic protection methods mainly include the following:

⑴Use anti-static materials: metal is a conductor, and the conductor leakage current is large, which will damage the device. Insulating materials are prone to frictional electrification, so metals and insulating materials cannot be used as antistatic materials. Instead, electrostatic conductors and electrostatic subconductors are used as anti-static materials. Commonly used electrostatic protection materials are realized by mixing conductive carbon black in rubber, and the surface resistance is controlled below the standard value.

⑵Leakage and grounding: ground the parts that may or have generated static electricity, and provide static discharge channels. Use the method of burying the ground wire to establish an "independent" ground wire so that the resistance between the ground wire and the ground is less than 10Ω.

⑶ Static protection material grounding method: connect static protection materials (such as work surface mats, floor mats, anti-static wrist straps, etc.) to the conductor leading to the independent earth wire through a 1MΩ resistance. The 1MΩ resistor is connected in series to ensure a current of <5mA discharged to the ground, which is called soft grounding. The equipment shell and electrostatic shield are usually directly grounded, which is called hard grounding.

⑷ Elimination of static electricity on conductor: The static electricity on the conductor can be grounded to make the static electricity leak to the ground. Generally, it is required to leak the static electricity within 1 second, that is, the voltage is reduced to a safe area below 100V within 1 second, so as to prevent leakage Excessive speed and excessive leakage current can damage the SSD. Electrostatic protection systems usually use 1MΩ current-limiting resistors to limit the discharge current to less than 5mA. This is designed for safe operation. If an operator accidentally touches the 220V industrial voltage in the electrostatic protection system, it will not Bring danger.

⑸ Elimination of static electricity on non-conductor: For the static electricity on the insulator, since the charge cannot flow on the insulator, the grounding method cannot be used to eliminate the static electricity. The following measures can be adopted:

① Use ion blower. The ion fan generates positive and negative ions, which can neutralize the static electricity of the static power source, and can be installed in the space and near the placement head of the placement machine.

② Use static eliminator. Static eliminator is a surface active agent, which can be used to scrub the surface of instruments and objects, and can quickly eliminate static electricity on the surface of the object.

③Control the environmental humidity. Increasing humidity can increase the surface conductivity of non-conducting materials and make it difficult for static electricity to accumulate on the surface of the object. For example, humidification and ventilation measures can be taken in the dry environment in the north.

④Use electrostatic shielding. A shielding cover can be used for equipment prone to static electricity, and the shielding cover can be effectively grounded.

⑤ Process control method. Effective measures should be taken in terms of plant design, equipment installation, operation, and management systems.

In addition, you can also start from the aspects of electrostatic protection equipment, electrostatic measuring instruments and anti-static technical indicators. The above is about the anti-static content of SMT surface mount, I hope it can be helpful to everyone!