A Transient Technique to Measure the Temperature Coefficient of Resistance for Thin Film Resistors

Abstract

The temperature coefficient of resistance (TCR) is defined as: TCR = (R2−R1)R1 × 1(t2−t1) where R2 and R1 are the resistances measured at temperatures t1 and t2 , respectively. The conventional TCR measurement method consists of measuring resistance at room temperature, then heating the resistor to a known higher temperature, then measuring the resistance again. This technique is very accurate and repeatable, however it is slow and cumbersome because it takes a moderate amount of time for the sample to reach steady state in an oven before the resistance can be measured. The present study proposes a new transient technique for measuring TCR. Thin film resistors are heated by passing a constant electric current through them. At an arbitrarily set time, the resistor temperature is estimated from the known transient conduction solution for a uniform flux surface imbedded in a semi-infinite medium. Measurements of the resistance at that time, along with the resistance at the initial (usually room) temperature will now permit the calculation of TCR. The method was found to be very fast, repeatable, and in good agreement with the conventional technique.