Analysis of static electricity in clean rooms
① A large number of high-insulation dielectric decorative materials, floors, walls, doors, ceilings, partitions, workbenches, chairs, etc., these materials are easily charged by friction and are not easy to leak and release.
The ESD plastic floor in the photolithography room is 500V~1000V, the plastic floor in the diffusion room is 500V~1500V, the tile floor is also 500V~1500V, the plastic wallpaper is 700V, the plastic ceiling is 0V~1000V, and the metal movable leather chair surface is 500V~3000V.
② When people wear clean clothes, shoes, walk or work, they will generate static electricity when they rub against different materials and equipment, and people, clothes, and shoes will be charged.
People wearing esd nylon clothes and esd plastic rubber-soled shoes walk slowly on the clean floor, and they carry 7000V~8000V static voltage. Walking on vinyl floor can carry 1200V (10%~20%RH), 250V (65%~90%RH) static voltage, walking on carpet can carry 35000V (10%~20%RH), 1500V (65%~90%RH), and the work clothes worn by workers on the chip assembly line can reach 10KV.
③ The air conditioning airflow passes through the primary filter, medium filter, and high efficiency filter, and the purified outlet airflow is statically charged. The aluminum plate air supply and return outlets are about 500~1000V.
④ A large number of insulating equipment, equipment and tools are also important sources of static charge. Wafer assembly production line: Wafer loading box 35KV, organic glass cover 8KV, quartz products 1.5KV, wafer tray 6KV, acrylic cover 20KV, table top 10KV, plastic storage cabinet 30KV, glass fiber crystal loading box sliding over polypropylene table top carries 10KV. In short, the higher the cleanliness requirements of the clean room, the more serious the static charge will be.