I am using four 12 Ohm 0603 resistors in series to introduce thermal energy into a system (dissipating ~2W with 10V across the series string). The resistors are from the Vishay RCP a high power family, and are spec’d max 1.5W @ 25 deg (but dissipating 0.5W each).
My concern is that the resistors are getting hot enough in free air to melt the high temp solder I used (290 deg C melting point). The resistors will be potted into a thin metal tube using Stycast thermal encapsulant in the finished product, so there will be better dissipation - but how much better?
Given that I do NOT have a thermal background, what is the best / easiest way to understand the thermal conduction paths, expected temperatures at the nodes in the (thermal) network, what features of the system are important to pay attention to, and what can be ignored, etc.