| 摘要 |
A thermistor element (1) with positive temperature characteristic (PTC) has a planar ceramic member with a positive temperature characteristic of which the thickness is greater at its peripheral part than at the center part, decreasing either gradually or in a stepwise manner. Protrusions (2, 3) may be formed along its periphery. A PTC thermistor (11) is formed with electrodes (12, 13, 14, 15) formed on both main surfaces of such a PTC thermistor (11), each electrode having a lower-layer electrode (12, 13) all over a main surface and an upper-layer electrode (14, 15) on the lower-layer electrode. The upper-layer electrode (14, 15) has a smaller surface area than the lower-layer electrode (12, 13) such that a portion of the lower-surface electrode (12, 13) is exposed at the periphery. The upper-layer electrodes (14, 15) may be formed at the center parts of the main surfaces, exclusive of the peripheral parts or where the protrusions are formed. The lower-layer electrodes (12, 13) may be mostly of Ni and the upper-layer electrodes (14, 15) mainly of Ag. <IMAGE> |
