How to prevent electrostatic discharge in SMT production line
SMT production line, also known as surface mount technology (SMT), is a new generation of electronic assembly technology developed from hybrid integrated circuit technology, and is the most popular technology and process in the electronic assembly industry. Since electronic components are sensitive to static electricity, surge, mechanical stress and thermal stress, static protection in the SMT workshop is essential.
The core of electrostatic protection in the SMT workshop is to "eliminate static electricity", that is, to keep static electricity to a minimum to ensure that it will not cause damage and destruction to electronic components. Want to control static electricity in the scope of application mainly from the following aspects:
1. Ground
Grounding refers to the places in the factory that may cause electric charge accumulation, such as equipment, workbenches, etc. The principle of wire grounding is the same as that of lightning rods. As for why it is connected to the earth, it is because the earth is an object with very low resistance and large capacitance. It has the ability to absorb infinite charge, and it can maintain the potential unchanged after absorbing a large amount of charge.
2. Control the humidity in the patch workshop
Dry and windy autumn and winter are prone to static electricity, and rainy spring and summer are relatively rare. In response to this phenomenon, ULiESD has studied the humidity of static electricity and concluded that static electricity will decrease when the ambient temperature is relatively high. Therefore, the SMT workshop uses air conditioners and other equipment to control the environmental humidity. The generation of static electricity can be controlled to a certain extent.
3. Use antistatic materials
Use so-called electrostatic conductors with surface resistance below 1105 and electrostatic sub-conductors with surface resistance between 1105 and 1108. For example, the surface resistance of rubber mixed with conductive carbon black can be controlled below 1106, which is a commonly used electrostatic protection material.
4. Wear uniform anti-static overalls
The generation of static electricity is the transfer and accumulation of electric charge, which is more likely to occur between different substances. The uniform anti-static work clothes are convenient for the overall anti-static of the SMT workshop.
5. Wear an anti-static wrist strap
When working in the SMT workshop, I often come into contact with components. At this time, the static electricity on their bodies can easily damage the components. Therefore, employees of SMT patch processing plants often need to wear anti-static wrist straps.