Finite element analysis for heat transfer involves laying out the physical 3D structure of a package, assigning thermal properties to the different pieces (die, package body, leadframe, etc.), and then “meshing” the physical structure into small elements. In most simulators today, the meshing is automatic with a manual override where extra detail is desired or where abrupt changes in temperature profile are expected. the software then calculates the temperature distribution across each element of the package and allows us to visually see the temperature distribution by equating a color to a given temperature. Often a separate text report file can be generated with temperatures of key locations.