| 摘要 |
Carrier trays comprise a synthetic resin composition containing inorganic fillers and having a low electrical resistivity. The resin is a thermosetting resin and the surface resistivity is low due to the presence of electrically conducting particles or fibres within the cured resin. Preferably the resin is an unsaturated polyester resin which is hardened or cured by the presence of an organic peroxide and which contains a polymerisation inhibitor inactivated by heat. The inorganic filler may be glass fibre, glass powder and/or calcium carbonate and the electrically conducting particles or fibres include one or more of carbon fibres, carbon black, metal fibres and metal coated fibres, such as glass and/or polymer fibres coated with a thin metal layer by vacuum deposition, electroless plating or other known techniques, and comprise from 2.5 to 7 percent by weight of the cured composition. The surface resistivity of the trays is less that 1 megohm per square, preferably less than 500 kilohms per square. A method of making the carrier trays comprises mixing into a thermosetting resin containing inorganic fillers electrically conducting particles or fibres until they are uniformly distributed within the resin and filler composition, placing the mixture in a mould in the form of the tray and thereafter heating the mould under pressure until such time as the thermosetting mixture has set and thereafter removing the tray so formed from the mould. |
