Failure analysis of a hybrid device exhibiting copper dendrite growth on thick film resistors

The authors discuss the failure analysis performed on several hybrid devices submitted to Oneida Research Services, Inc. The analysis was initiated because of electrical testing failures-a voltage divider exhibited an out-of-specification value during burn-in at elevated temperature. This voltage divider compared the outputs of two thick-film resistors. Analysis of the hybrid failures revealed a copper dendritic growth propagating across the laser trims in the thick film resistor. The authors describe the hybrid materials construction, environmental testing, and electrical testing performed in examining the factors which led to the dendrite growth and overall failure of the hybrids. A detailed description of the analytical equipment and methodology used in identifying the cause of the copper dendrite growth as a result of processing is presented. The authors conclude with a discussion of the failure analysis.<>