While micro PGA (pin grid array) sockets are currently the predominant choice for socketing industry standard microprocessors to printed circuit cards, LGA (land grid array) interconnections are the clear choice for future high performance processor sockets. LGA interconnections will be needed to meet the performance requirements for increased bandwidth, lower signal inductance, and lower signal crosstalk along with the ongoing demand for higher packaging density and increased signal and power interconnections. Although LGA interconnections offer improved performance and packaging density, the price for these advantages is the increased complexity of the retention hardware that is needed to compress the LGA interconnection between the contact pads on the processor package and the corresponding contact pads on the printed circuit card. New LGA socket designs continue to be developed to address the challenges for existing and new LGA applications. These designs include both metal spring contacts as well as elastomeric or conductive polymeric contacts. Key application requirements such as connector compliance, actuation and normal forces, along with contact alignment techniques become more critical as the size of the MCM increases. The potential failure mechanisms for LGA socket technology cover the entire range of failure mechanisms possible for an interconnection system. Interactions between these various failure mechanisms further emphasizes the need for ongoing testing and analysis to fully understand the reliability performance of new LGA applications as well as new LGA interconnect designs and materials.
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