What are the electrostatic hazards in electronics factories without wearing clean clothes?
When the human body performs various activities, the static voltage value on clothing has greatly exceeded the electrostatic discharge damage threshold of many electrostatic sensitive devices, so it may cause damage to sensitive devices when touching or approaching these components. It should also be pointed out that it is generally believed that wearing pure cotton work clothes without dust-free clothes can prevent the static electricity accumulation of the clothes, so it is safe, and this view is actually one-sided. This is basically the case only when the relative humidity of the air is higher than 50%, and when the relative humidity is relatively low, the charge of pure cotton products increases significantly. Tests show that when the relative humidity is less than 30%, the charge of pure cotton fabrics is equivalent to that of polyester; and when the relative humidity is less than 20%, the charge of cotton fabrics is even higher than some chemical fiber fabrics. Therefore, in dry climate areas, pure cotton products cannot be expected to eliminate the electrostatic hazards of clothing under any circumstances.
During normal production activities, the operator wears clothing and external media surfaces (such as work surfaces, chair surfaces, tools, appliances, etc.), between different layers of clothing, between underwear and skin, until the soles and the ground are walking. Between pings, clothing and shoes will be charged due to frequent contact separation and friction, especially when wearing chemical fiber clothing with high insulation performance. The static charges carried in parts of clothing and shoes gradually spread to the entire surface according to the law of charge distribution on the medium, and a certain static voltage on the clothing is formed when it reaches equilibrium.
Of course, because the human body itself is a good conductor, the charging of clothing will cause the body's skin to be charged due to electrostatic induction, and also form a certain static voltage. Clean clothes are the best choice, so for the operator, there are two possible discharge channels; one is the discharge between the fingertip (skin) and the ground conductor, and the other is the discharge between the work clothes and the ground conductor. Both discharges can cause damage to electrostatic sensitive devices. Although the anti-static wristband can eliminate the first discharge danger, it cannot eliminate the second discharge danger. This is because the wristband can only eliminate static electricity on human skin as a good conductor, and it is not possible to leak static electricity from clothing with high insulation. People often only pay attention to the elimination of static electricity on the human skin, and ignore or do not pay enough attention to the elimination of static electricity on clothing, which needs to be improved. In order to effectively prevent the electrostatic discharge hazard of the human body, the operator must wear dust-free clothes.