Thermal Coupling of NTC Chip Thermistors

A novel device called thermal coupling of NTC chip thermistors was made by combining two electrically isolated chip thermistors Th
1
and Th
2
having small dimensions (0603) and small power (1/10 W). The first thermistor Th
1
(input thermistor) is self-heating at a constant supply voltage U – it generates heat while the second thermistor Th
2
is passive (output thermistor) – it receives heat. Thermistors are electrically insulated, but thermally coupled. The temperature dependence of NTC chip thermistors R(T) was measured and exponential factor of thermistor resistance B was determined. After that, current I
1
of self–heating thermistor as a function of supply voltage U and using resistance R
1
of input thermistor was determined. The electrical resistance of output thermistor R
2
was measured by multimeter at the same time as the current of input thermistor. Using the Steinhart – Hart equation the temperature T
1
and T
2
of both thermistors were determined. The application of novel thermistor junction is expected in power microelectronics for electrical decoupling/thermal coupling of input to output slowly changeable signals.