| abstract |
A laminated positive temperature coefficient thermistor is provided with a ceramic element (1) wherein semiconductor ceramic layers (3a-3e), each of which has BaTiO3 as a main component and contains an agent to make material semiconductive, and a plurality of internal electrodes (4a-4d) are alternately laminated, and the outermost layers are formed of semiconductor ceramic layers (3a, 3e). The outermost layers form protection layers (5), and an effective layer (6) is formed by the semiconductor ceramic layers sandwiched between the internal electrodes (4a, 4d). The protection layer (5) contains an agent for making material semiconductive, and the agent has an ion radius larger than that of the agent contained in the effective layer (6), and a hole ratio of the protection layer (5) is lower than that of the effective layer (6). Preferably, a glass film is formed in the hole on the surface of the protection layer (5) to have the hole ratio of the protection layer (5) 10% of below. Thus, entry of flux into the semiconductor ceramic layer is eliminated without generating delamination, and a desired resistance change rate is ensured. |