
Thermal Resistance Network 77
Example 5.6
Consider the copper cap of the package in Examples 5.2 to 5.4 and let’s assume
both convection and radiation heat transfers happen simultaneously from its sur-
face. Calculate equivalent thermal resistance from its surface to air around it and
the temperature of the heat spreader.
Solution
Since convection and radiation heat transfers happen simultaneously, the cap to
ambient thermal resistance is the parallel equivalent of convection and modi-
fied radiation thermal resistances. Example 5.2 gave
and
Example 5.4 showed that
if radiation was the only heat transfer ...