Thermal characterization of a multi-heat source component with and without an external heat sink

In the past two decades thermal characterization of electronics components has evolved tremendously by the introduction of the Boundary Condition Independent Compact Thermal Model. The BCI CTM enables a division of responsibilities: the component manufacturer models the inside of the package and the world outside the package is the domain of the thermal application engineer. The present work relates to the thermal behaviour of a multi heat source component under unequal thermal loading and with or without the presence of an external heat sink. It is shown that the external heat sink not only improves the overall thermal resistance from the component to the ambient, but also impacts the elements in the thermal impedance matrix that are usually associated with heat transfer inside the package by providing a parallel path for lateral conduction. The latter effect has implications for the boundary condition independent characterization of multi-heat source components.