Patent ID: 7075408
Filing Date: 2006-07-11
Classification: H01C

Abstract:
1. A positive temperature coefficient thermistor comprising: a laminate including a plurality of thermistor layers stacked in a lamination direction and having a positive resistance temperature coefficient; first and second external electrodes disposed at different positions on an outer surface of the laminate; a plurality of first internal electrodes and a plurality of second internal electrodes arranged so as to extend along predetermined interfaces between the plurality of thermistor layers inside of the laminate and so as to be electrically connected to the first external electrode and the second external electrode, respectively, the first internal electrodes and the second internal electrodes being arranged alternately in the lamination direction so that a portion of the first internal electrodes and a portion of the second internal electrodes overlap each other while sandwiching the thermistor layers therebetween; and at least one non-heating portion, which is not heated when a voltage is applied between the first and second internal electrodes, being located at an approximate center along a direction that is substantially perpendicular to the lamination direction of the portion of the laminate where the first and the second internal electrodes are arranged and at feast in an approximate center in the lamination direction thereof; wherein the at least one non-heating portion includes a cavity provided in at least one of the thermistor layers; the cavity is disposed at least in the approximate center of the laminate in the lamination direction; and the cavity does not extend entirely through the laminate.