Preparation of loading information for reliability simulation

Many decisions regarding the design with a system using sockets are made using a point estimate (often from a standard or accepted practice) of the compressive load. The components of a CLGA assembly were analyzed using Monte Carlo simulation methods to determine the distribution of the compressive loads that are applied to the component socket. The components of the assembly that impact the resulting load were identified and their individual distributions defined. The relationship between the height of the components and the compression provided by the springs was determined and used to estimate a load distribution. The load distribution thus estimated can be used as an input to further virtual qualification efforts. For example, the estimated load distribution from this analysis was used with other manufacturing parameters and FEA models to estimate the IC socket contact compression. The results showed that the minimum compression required for a good electrical contact was achieved over 99.9% of the time. Therefore, information that is obtained from virtual qualification was shown to be of great value in the determination of proper test conditions and design decision making.