The necessity of wearing ESD anti-static work clothes
In normal production activities, the operator wears the work clothes and the external medium surface (such as work surface, chair surface, tools, utensils, etc.), between layers of clothing, between underwear and skin, until the sole and the ground when walking. Between the planes, clothing and shoes will be charged due to frequent contact separation and friction, especially when wearing chemical fiber clothing with high insulating properties. The local electrostatic charge of clothing and shoes gradually dissipates to the entire surface according to the dispersal law of the charge on the medium, and a certain electrostatic voltage is formed on the clothing when it reaches equilibrium. Of course, since the human body itself is a good conductor, the electrification of clothing will make the skin of the human body electrified due to electrostatic induction, and a certain electrostatic voltage will also be formed. Thus, for the operator, there are two possible discharge paths; 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 of these discharges can cause damage to electrostatic sensitive devices. Although the anti-static wrist strap can eliminate the first type of discharge hazard, it cannot eliminate the second type of discharge hazard. This is because the wristband can only eliminate the static electricity on the human skin, which is a good conductor, and it is impossible to leak the static electricity on the clothing with strong insulation. People often only pay attention to eliminating static electricity on human skin, but ignore or do not pay enough attention to eliminating static electricity in clothing, which needs to be improved.
It should also be noted that it is generally believed that wearing pure cotton can prevent the accumulation of static electricity in clothing, so it is safe. In fact, this view is 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 amount of pure cotton products increases significantly. Tests show that when the relative humidity is lower than 30%, the electric charge of pure cotton fabrics is equivalent to that of polyester; and when the relative humidity is lower than 20%, the electric charge of cotton fabrics is even higher than that of some chemical fiber fabrics. Therefore, in areas with dry climates, it cannot be expected that pure cotton products can be used to eliminate the hazards of static electricity in clothing under any circumstances.
Based on the above reasons, in order to effectively prevent the hazard of electrostatic discharge caused by static electricity in the human body, the operator must wear anti-static overalls.