Benchmark Testing of LGA Sockets for Server Applications

Abstract

Recent trends for industry standard microprocessors show a transition from using micro PGA (pin grid array) sockets to using LGA (land grid array) sockets to meet the increased performance challenges for new server applications. These new industry standard LGA sockets use a hybrid construction with a solder ball connection to the printed circuit card and a compression connection to the contact pads on the bottom surface of the microprocessor package. Custom LGA sockets have been used for many years in high end server applications and provide improved electrical performance compared to these new hybrid LGA sockets. New LGA socket technologies continue to be developed to meet the variety of server application requirements. Benchmark testing has been performed on a variety of custom LGA sockets along with the hybrid LGA sockets used for industry standard applications. The benchmark testing includes evaluations of contact reliability performance, high speed electrical performance, and high current performance. The test hardware was designed to simulate the product application including the processor package construction, the printed circuit card cross section, along with the heat sink and retention hardware configuration. The results from the benchmark testing identify the limitations for various types of LGA sockets and provide critical insights for selecting the optimum solution for a given application.