PTC thermistor material
US6218928A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | May 8, 1998 |
| Grant date | Apr 17, 2001 |
| Priority date | — |
| Expiry date | May 8, 2018 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC04B2235/3294
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
The PTC thermistor material of the invention comprises a matrix phase and electrically conductive phases substantially uniformly dispersed in the matrix phase, said conductive phases having a resistivity lower than that of the matrix phase, and has a resistivity changing sharply in the vicinity of the melting point of the conductive phases. The matrix phase is made up of any one of a polycrystalline ceramic material, a glass-polycrystalline ceramic composite material, a glass, a crystallized glass, and a polymer material, and the conductive phases are made up of a metal containing bismuth as a main component. It is thus possible to achieve a PTC thermistor material which can be controlled in terms of various properties such as the temperature at which PTCR property becomes available and the rate of resistivity change and so can be applied to circuit parts through which large currents pass in a normal operation state. Further, the PTC thermistor material can be easily manufactured with the stable PTCR property maintained. Furthermore, the PTC thermistor material can be operated with an increased rated current albeit being of small size, and has a high degree of shape freedom.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.