Reliability Study of a High-Precision Thick Film Resistor Network

This investigation was undertaken to determine the reliability of a thick film resistor network, comprised of 4 matched 1.1 M resistors. The objectives of the program were: 1) to define any potential failure mechanism and 2) to determine the end-of-life (20 years) resistot properties. These objectives were achieved by a simulated life-testing of the resistor networks through the use of accelerated aging tests in various environments. Four resistor network properties were measured in this study: 1) resistance of individual resistor; 2) bridge imbalance voltage; 3) resistor noise; and 4) temperature coefficient of resistance. Evaluation of the data obtained in the present investigation resulted in the following conclusions. l)There is no potential failure mechanism that will cause the resistor network to degrade outside its end-of-life requirements during its lifetime. 2) The extrapolation of the high-temperature aging data to maximum operating temperature (70°C) indicates that the resistance value will not increase more than 0.5 percent in 20 years. 3) Other properties such as noise, stability against lightning surge, and temperature coefficient of resistance were insensitive to any aging treatments.