The electrical properties of the laminated PTC thermistor for micro circuit protection as a function of starting material and Sr addition

Abstract

We investigated the electrical properties the starting material and sintering condition on the laminated PTC thermistor for micro circuit protection. The influences of BaTiO3 powder with the 0.3 and 0.45 μm size and the electrical characteristics (Ba,Sr)TiO3 sintered at 1350∼1400°C for 2 h in a reducing atmosphere (1% H2/N 2). The sintered (Ba,Sr)TiO3 was increased pore and the grain size was decreased according to increasing Sr additions. In relative permittivity, the phase transition temperature of (Ba,Sr)TiO3 was decreased for 2.5°C according to increasing 0.01 mole Sr additions, and the phase transition dose not appeared about 0.3 mole Sr addition. The (Ba,Sr)TiO3 was show the low resistance from 0.01 mole to 0.05 mole by Sr addition, regardless of sintering temperature. The (Ba,Sr)TiO3 was show 102 jump order at 0.1 and 0.2 mole Sr addition, and PTCR of the sintered (Ba0.7Sr0.3)TiO3 does not appeared about 0.3 mole Sr addition, regardless of the sintering temperature and starting material size.