| This dissertation provides the first study where the reliability of a metal particle-in-elastomer socket is addressed. It is found that the qualification testing, as performed by the socket manufactures, does not address some of the unique failure mechanisms of this type of sockets. Therefore, more stringent methods are needed to address their reliability concerns and provide a physical understanding of the failure mechanisms.; This dissertation provides a comprehensive investigation of the potential risk areas facing the application of the elastomer interconnects. A list of critical socket material and design characteristics is identified and examined. By characterizing these properties, the operating parameters, such as contact force and operating temperature limits, are revealed, and the potential reliability risk areas are identified; among them, stress relaxation, radial deformation, fluctuation in contact resistance under thermal cycling and mechanical loading conditions, silver reaction with chloride and sulfur, and elastomer-silver particle dewetting are found to be of the most serious concerns, as they may lead to contact open, contact short, or intermittent failures. The fluctuation in contact resistance during temperature change can be explained in terms of the elastomer expansion and contraction, interconnect deformation and the effect of temperature on the tunneling resistance. The change of the interconnect composite macrostructure and the elastomer rebound properties may be responsible for the observed interconnect intermittent failures during durability cycling. Elastomer stiction to the contact pads is found to cause damage to the contact pad plating during socket disassembly. This raises a concern of reworkability of component, circuit board and socket itself. Issues such as loading control mechanisms, stack tolerance, and socket manufacture and component assembly quality are also identified to contribute to socket failures. Although this study is made on a particular product, the general assessment process and identified reliability risk areas can be applicable to other elastomer socket designs. |
