An Experimental and Computational Study of Heat Transfer in High Power Amplifiers

Abstract In high power amplifiers, the understanding of heat transfer phenomena is critical to ensure components operate within acceptable temperature limits. System operational reliability has been shown to reduce considerably when individual components are allowed to exceed maximum-rated junction temperatures. Of particular interest in this study are high power amplifiers used in the telecommunications industry. In such applications, heat sinks in forced airflow have traditionally been used to provide cooling due to their low cost and ongoing maintenance requirements. Here, the causes of failure of an amplifier circuit board used for high-frequency signal transmission have been closely studied. Analysis of failure data gathered over a four-year period was used to identify the main component level causes of system failure, and preliminary experiments were conducted to estimate junction temperatures of these components under field conditions. Subsequent experiments were then carried out to measure the the...