Patent ID: 6346496
Filing Date: 2002-02-12
Classification: H01C

Abstract:
A method for manufacturing the ceramic for use in a PTC thermistor comprising providing a BaTiO3-containing composite material containing a semiconducting additive, firing the composite material in a neutral or reducing atmosphere and then heat-treating the fired material in an oxidative atmosphere, wherein the composite material comprises a principal component containing about 30 to 97 mol % of BaTiO3; about 1 to 50 mol % of PbTiO3; about 1 to 30 mol % of SrTiO3; and about 1 to 25 mol % of CaTiO3, wherein the total content of BaTiO3 PbTiO3 SrTiO3 and CaTiO3 is 100 mol %; and relative to 100 moles of the principal component, as additives, about 0.1 to 0.3 moles of Sm as Sm in a compound containing Sm; about 0.01 to 0.03 moles of Mn as Mn in a compound containing Mn; and 0 to about 2.0 moles of Si as Si in a compound containing Si.