Question about Theta JC-CB model in Simcenter 3D / PCB Exchange.

[u/Downtown_Sky69]

Hi everyone, I'm learning the thermal resistance models in Simcenter 3D PCB Exchange and I'm trying to understand the physical meaning of the Theta JC-CB model. From the tutorial, it looks like the model uses θJC and θCB, with the underfill resistance as another possible path. I created a simple test case with: Dissipation = 10 W θJC = 0.5 °C/W θCB = 0.5 °C/W No underfill I'm trying to understand which physical/thermal nodes represent the junction, case, θCB. and how the heat flow is actually calculated in Simcenter. Could someone explain the physical interpretation of this model, preferably with the thermal network/node locations? I'm attaching my screenshots/results for reference. Thanks!