| I am checking out trays for packing of Simms, and I would like to know what are the main differences between Anti-Static and Conductive trays. Anti-static are cheaper, but I would like to know about properties of one against the other, what are various companies using, etc. | | | There is loose terminology in this field. There are three techniques used: a) metallisation of plastics to make the surface conductive. Excellent results, but subject to more wear, as the conductive surface can be scratched away. b) charging the plastic itself with partially conductive particles, usually lampblack (this does not mean that all black plastic is like this: there may be sufficient lampblack to colour the plastic but not to render it conductive, done by c) below). This method is long-lasting and effective. c) charging the plastic with a hygroscopic substance, subdivided into c1) having a long chain hydrophilic molecule within the polymer matrix and c2) spraying on a hydrophilic substance, such as a detergent, so that it is adsorbed into the plastic surface. In both cases, it is possible for the hydrophilic molecule to end up on the PCB, not necessarily improving its electrical performance. The pink plastics for bags and bubble paper belong to this category, as do the ones with a hatched pattern. This is the cheapest type for both wrapping materials and rigid trays, hence popular by those who know no better or cannot argue with the purchasing department.
Brian
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