Patent ID: 8268437

Claim:
A ceramic substrate obtained by applying debindering and sintering treatments to a ceramic sheet produced by a process which comprises spraying a liquid mixture comprising water, a release agent and a plasticizer to a powder mixture comprising a ceramic powder, a sintering aid and hydroxypropylmethyl cellulose, to prepare a granular wet powder material, kneading the wet powder material, and molding the powder material into a sheet by means of a single screw extruder equipped with a sheet die, wherein the wet powder material is kneaded by means of a twin screw extruder, wherein the powder mixture comprises from 5 to 15 parts by mass of hydroxypropylmethyl cellulose and from 1 to 15 parts by mass of the sintering aid relative to 100 parts by mass of the ceramic powder, and wherein the hydroxypropylmethyl cellulose comprises from 19 to 30 mass % of a methoxy group and from 4 to 12 mass % of a hydroxypropoxyl group.