Mica insulator

In the manufacturing of electronic devices, a mica insulator is a die-cut punched insulator of natural or "block" mica splittings.

Mica slices are used in electronics to provide electric insulation between an electronic component which can generate heat and the heat sink used to cool it [See pictures and use on [http://www.bigdaddy-enterprises.com/electronics/e_heatsinks.htm] [http://www.aavidthermalloy.com/products/standard/access/kits.shtml] [http://www.vitacom.ro/Products/OEM/250/MICA-TO220/ISOLATION-TO220.html] [http://www.alliedelec.com/Search/ProductDetail.asp?SKU=935-9422&MPN=NTE422&R=935-9422&sid=480D2A80500DE17F] ] . Mica is used because it can be be split into very thin slices, and this keeps its thermal resistance low while retaining sufficient dielectric strength to prevent current from flowing across it at moderate voltages. The insulation is usually necessary when the heat sink is earthed while the electronic component's metal surfaces will be connected to a power supply or signal line. If they were in direct contact this could form a short circuit. Heat sink insulation can also be necessary to prevent the heat sink from acting like an antenna if the component is connected to a rapidly varying signal.

The same term ("mica insulator") is sometimes used by technicians to designate a synthetised gum (usually blue or grey) used for the same purpose, but not actually composed of the silicate mineral at all.

Micas are a group of aluminium phyllosilicate minerals which are found worldwide. Commercial deposits are found in India and Madagascar. It is mined in the form of "blocks" or rocks, which are then rifted to arrive at thin flexible natural mica splittings. When these are die-cut specifically for the transistor industry, the resultant product is called a "mica insulator".

Resin-bonded mica or micanite or built up micanite from splittings or agglomerated micanite made from pulped mica powder are called micanites. All these products have additives, like resins, and the resultant products, while having inferior insulation properties to natural "mica insulators" are called micanites or micafoliums.

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