Statguard Flooring - Questions And Answers

One of our vendors ships ESD parts with a rubber band wrapped around the tube, instead of a plug or pin inserted into the end of the tube, to prevent parts from falling out of the tube. When questioned about this, the reply was the rubber bands are "sprayed with a staticide so the parts will not be harmed". What do you feel of this practice? Won't the 'benefits' of the staticide be negated by the elasticity of the rubber band when it's stretched? - Anonymous, Orlando, FL

To fairly quantify this answer, the rubber bands should be tested with a charge plate analyzer and field meter. Rub the rubber bands on the chip tubes and place on an insulative surface (cardboard, glass, or ceramic). Now measure the electric field strength with the field meter. If over 250 volts (or what ever maximum voltage the corresponding chip’s class is), they should not be used for this purpose. Also, apply a voltage on a rubber band (lay rubber band on the isolated plate of a charge plate analyzer) and then place it on a grounded conductive surface. If the rubber band still holds a significant charge, it should not be used. Natural rubber bands may not be the best choice for securing the ends of a chip tube, even when treated with a topical anti-static spray unless they pass the tests above. The chip tube should also be “anti-static” inside to minimize tribocharging of the chips/leads and static dissipative is a bonus to keep the chip surfaces all at the same potential. Once you’ve established the chip tube is adequate for ESD protection, the ends are typically secured with conductive (static dissipative) rubber. If your vendor insists on using rubber bands, we suggest they use conductive and anti-static ones.

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