Evolution of the DELPHI compact thermal modelling method: An investigation on the boundary conditions scenarios

Board-level simulation has to consider, at the earliest stage of the conception, the impact of the vicinity of numerous high and medium powered devices. In 1996, the concept of Compact Thermal Model was defined, by the European consortium DELPHI to minimize the computation times, from days to minutes. A CTM resumes an electronic component as a simple cuboid form and a network of resistors that links a single temperature-sensitive node to major surfaces of heat extraction. Unfortunately the DELPHI method is restricted to steady-state model for mono-chip component. More complex issues such as multi-chip module or transient thermal model remain today for worldwide companies a non-trivial challenge. Our latest improvements made to generate steady-state multi-source CTM for System-In-Package devices showed that the number of boundary-condition scenarios is quite prohibitive when several nodes need to be monitored. The present work investigates the use of fractional factorial experiment, such as N-variables Doehlert design. The objective of this study is to define the lowest number of numerical simulations while keeping the highest accuracy level of the derived Boundary-Condition-Independent thermal network.