Static Electricity and Its Impact on Component Manufacturing and Assembly
1. Work Clothes: Ordinary work clothes (made of synthetic fibers and pure cotton) worn by workers can generate 0.2-10 microcoulombs of charge when rubbed against work surfaces and chairs. This can generate a static voltage of over 6000 volts on the clothing surface, charging the human body. When workers hold integrated circuits and come into contact with components placed on the work clothes or work surfaces, discharge can occur. Due to the different contact potentials of the component leads and the extremely thin dielectric and low insulation strength of the chip, dielectric breakdown of the device can easily occur.
2. Work Shoes: The insulation resistance of general work shoes (rubber or plastic soles) is as high as 1 x 10¹³ ohms or more. When rubbed against the ground, static charge is generated, causing the human body and clothing to become statically charged. Studies show that cases of static electricity generated by work shoes rubbing against the ground causing component failure are not common. However, due to their high insulation resistance, the static electricity carried by the human body cannot dissipate quickly, thus adversely affecting component production.
3. Resin and Enamel Encapsulated Surfaces: Many electronic components require highly insulating resin and enamel encapsulation. After being packaged, friction during transportation can generate static electricity (SEE) of several hundred volts or more on their surfaces, potentially causing chip breakdown.
4. Various Packaging and Containers: Packaging and component boxes made of polymer materials such as PE (polyethylene), PP (polystyrene), PUR (polyurethane), ABS, and polyester can generate static charge due to friction and impact, adversely affecting the packaged components.
5. Terminal Tables and Workbenches: Static electricity generated on the surfaces of terminal tables and workbenches due to friction can discharge onto electronic components placed on them.
6. Various Insulating Floors: Waxed and polished floors, rubber sheets, etc., can generate static electricity due to friction. Furthermore, due to their high insulation resistance, static charge cannot be quickly released when workers carry it on them.
7. Incubators: The airflow and friction within the incubator generate a large amount of static charge, which is highly detrimental to the heat treatment of components.
8. CO2 Low-Temperature Chamber: CO2 vapor can generate a large amount of static electricity within the chamber.
9. Air Compressor: Equipment using air compressors for spraying, cleaning, painting, sandblasting, etc., can generate a large amount of static electricity due to the vigorous airflow or friction between the medium and the nozzle. Contact with charged media can cause damage to electronic components.
10. Certain Electronic Manufacturing Equipment: High-voltage transformers and AC/DC circuits within certain component assembly equipment, such as soldering irons and wave soldering machines, can induce static voltage on the equipment. Without measures to prevent static electricity leakage, components can malfunction during assembly.