The invention discloses an
epoxy resin encapsulating material, which is characterized by comprising 40 to 60 weight portions of EP828
epoxy resin or E51
epoxy resin, 80 to 130 weight portions of platy alpha Al2O3
ceramic powder, 5 to 10 weight portions of
coupling agent - gamma-(2,3-epoxy propoxide) propyl trimethoxy
silane, 8 to 12 weight portions of curing agent 590 and 0.1 to 1.5 weight portions of
plasticizer - di-n-octyl phthalandione. The invention also discloses a method for preparing the epoxy resin encapsulating material, which comprises: firstly, dissolving the
coupling agent into
ethanol, adding the platy alpha Al2O3
ceramic powder into a mixture under the condition of stirring, and preparing
alumina powder; and secondly, adding the
plasticizer into the epoxy resin, uniformly mixing the
plasticizer and the epoxy resin, adding the
alumina powder into a mixture, performing mixing and
degasification, adding the curing agent into the mixture, and performing vacuum defoamation and curing to obtain the epoxy resin encapsulating material. By adoption of the platy alpha Al2O3
ceramic powder as filler, the
dielectric loss tangent value of the obtained material is reduced from 0.11 in the prior art to 0.02, and the
electric breakdown strength is improved from 10kV.m<-1> in the prior art to 84-102kV.m<-1>.