When university labs investigate heat transfer in electronic assemblies, they hardly ever use printed circuit boards and electronic components to represent printed circuit boards and electronic components. Boards are represented by uniform thermal insulators like balsa wood, and components are represented by blocks of aluminum. Why? Quite understandably, the researchers need to simplify the assemblies to make them easier to understand. They are looking for fluid flow and heat transfer phenomena, and they don't want a lot of the details of real electronic components to complicate the picture.
Too bad we can't do the same thing. It would be a lot easier to figure out component temperatures if they were all uniformly sized aluminum blocks. And conduction within the printed circuit board would be a lot easier to calculate if we didn't have all those messy copper traces mixed in with the dielectric.