| 摘要 |
PROBLEM TO BE SOLVED: To avoid a positive temperature coefficient thermistor element from short-circuiting and breaking, by causing a body of the element of semiconductor ceramic material to be positively layer-cracked when an excessive voltage is applied to the element. SOLUTION: An inner layer 15 having a large porosity is made by sintering ceramic material for positive thermistor containing resin beads. The inner layer 15 is formed on its both sides respectively with an outer layer 16 having a small porosity, on which an electrode 13 is provided, thus completing a positive thermistor element 11. When an excessive voltage is applied to the thermistor, the inner layer 15 having a large porosity is cracked, whereby a circuit including the positive temperature coefficient thermistor is open-circuited. |
