Multi-die packaging and thermal superposition modeling

Packaging density, electrical performance and cost are the primary factors driving electronic package architectures for high-performance server markets. Considerations such as thermal performance and mechanical reliability are equally important but tend to be addressed later in the design cycle. Presented in this paper is a historical view of the packaging trends leading to the current multi-die package options. Particular attention must be placed on the thermal limitations and benefits offered by each design. Since multi-die packages have many junctions of interest, a method for characterizing the package with arbitrary power conditions is required. A superposition method, using a matrix approach, is presented that will enable the end-user to investigate the effects of power levels on junction temperatures. Experimental data measured on a 2.5D package were taken to demonstrate the matrix approach for predicting junction temperature based on an independent power map. The agreement between the matrix model and data generated by an independent power map is within 8%.