Can you predict the surface temperature of a resistor or a semiconductor using its data sheet?

Can you predict the surface temperature of a resistor or a semiconductor using its data sheet?

  • Thermal properties are tested and characterized in a certain environment where we try to carefully control all factors to develop the parameters.   Many products have a parameter, theta jc, which describes the thermal resistance from junction to case, i.e., surface, normally bottom surface.  Presumably then, if theta jc for a given product is 10C/W, and the product is dissipating 1 watt, then the case temperature will be 10C above ambient.   

    But this not likely to be the same over the entire surface of the part, and may vary according to ambient conditions.