Methods for manufacturing insulated heat conductive substrate and insulated heat conductive composite substrate

A method for manufacturing an insulated heat conductive composite substrate, comprising steps of:

• performing hydrolysis and condensation of at least one thermally conductive ceramic powder to prepare at least one modified thermally conductive ceramic powder with thermal conductivity greater than 20 W/mK, which comprises a plurality of modified powder particles each grafted with an organic material;
• mixing the at least one modified thermally conductive ceramic powder with two substantially mutually soluble polymers at a temperature of 50° C. to 150° C. above the highest glass transition temperature of the polymers to achieve a uniform mixture, wherein the two polymers include a thermoplastic polymer and a thermoset epoxy resin, and the mixture comprises 50% to 75% by volume of the thermally conductive powder;
• blending the uniform mixture with a curing agent at a temperature below 120° C. to obtain a melt extrudable dielectric curable material;
• extruding the dielectric curable material through a slit at a temperature between 50° C. and 120° C. to form a curable sheet-like substrate;
• disposing separately a first film and a second film on two side surfaces of the sheet-like substrate, wherein each of the first and second films can be a metal foil or a release film;
• cutting a combination of the sheet-like substrate, the first film, and the second film to obtain an insulated heat conductive substrate;
• and
• pressing a plurality of the insulated heat conductive substrates at an elevated temperature ranging from 130° C. to 250° C. to obtain a cross-linked insulated heat conductive composite substrate.