Fopt-a thermal optimization factor for microelectronic packages

The authors provide a more coherent standard for microelectronic package performance assessment. An optimum package thermal resistance and optimization factor are defined, which can be used by a thermal designer to measure the variation of performance under given system constraints. These system constraints and the individual thermal resistances existing for any package-on-board arrangement are outlined, and shown to hold for both single-chip package and multi-chip package designs. Junction-to-ambient thermal resistance values obtained from natural convection equipment, which may differ, must lie within the bounds determined by this study