Dissipation power of the heat source
Different volumes may warrant different manufacturing techniques that will change the design. The priority of these general inquiry parameters depend on which specific cooling method we determine.
Size/ footprint of the heat source
Example - area of the mating surface.
Assume uniform heating across entire mating surface of the heatsink
Mounting hole locations
Not essential for thermal simulation with exception for liquid cooling designs
Maximum allowable temperature
Defined in two ways: maximum temperature of the heat source (°C) or thermal resistance (°C/W)
Assume 80°C maximum temperature
Size limitations of heatsink
Assume reasonable limitations based on the size of the heat source
Assume room temperature