Thermally Coupled NTC Chip Thermistors: Their Properties and Applications.

Negative temperature coefficient (NTC) chip thermistors were thermally coupled to form a novel device (TCCT) aimed for application in microelectronics. It consists of two NTC chip thermistors Th and Th, which are small in size (0603) and power (1/10 W). They are in thermal junction, but concurrently they are electrically isolated. The first thermistor Th generates heat as a self-heating component at a constant supply voltage U (input thermistor), while the second thermistor Th receives heat as a passive component (output thermistor). The temperature dependence R(T) of NTC chip thermistors was measured in the climatic test chamber, and the exponential factor B of thermistor resistance was determined. After that, a self-heating current I of the input thermistor was measured vs. supply voltage U and ambient temperature T as a parameter. Input resistance R was determined as a ratio of U and I while output thermistor resistance R was measured by a multimeter concurrently with the current I. Temperatures T and T of both thermistors were determined using the Steinhart-Hart equation. Heat transfer, thermal response, stability, and inaccuracy were analyzed. The application of thermally coupled NTC chip thermistors is expected in microelectronics for the input to output electrical decoupling/thermal coupling of slow changeable signals.