Plastics material with spherical silicon dioxide filler of specific particle size and having negative coefficient of thermal expansion

摘要

A plastics material for covering metal and/or semiconductor surfaces, contains at least one polymer, especially Duroplast(TM), and includes a filler which consists of spherical silicon dioxide (SiO2 ) particles with a graduated diameter distribution, in which the standard deviation from the mean diameter, of at least one diameter graduation, is = 10%.. Independent claims are also included for the following: (1) a preparation process for spherical SiO2 particles which involves polymerization of silicic acid from the hydrolysis of tetraalkoxy-silanes, in one or more steps, in which the SiO2 particle surfaces are at least partially a modification containing tetraalkoxysilanes, e.g. at least one of methyl-, ethyl-, or hexyl- triethoxysilane, 3-aminopropyl- triethoxysilane, 3-glycidopropyl- triethoxysilane, 3-mercaptpropyl- triethoxysilane; (2) a plastics-bonded body, especially an integrated circuit with a metal and/or semiconductor base, which has a coating of at least one filler, i.e. spherical SiO2 particles, and contains a polymer, especially Duroplast; (3) a process in which SiO2 particles of a plastics compound body, at least one SiO2 particle showing an internal refractive index which increases from the center to the surface, which involves: (a) dissolving the SiO2 particles from the coating, especially by heat treatment and/or treatment with sulfuric acid or acetone, and (b) measurement of the internal refractive index of at least one SiO2 particle from the center to the surface; (4) a process for production of a filler for a plastics material used for coating a metal/and or semiconductor, in which Li2CO3, Al2O3 and SiO2 in a weight ratio 0.2496:0.3444:0.4060, are mixed and melted at = 1388 deg C.