Heatsinks without

A.6.2 Determine the Maximum Power That Can Be Dissipated by a Three-terminal Regulator at the Maximum Specified Ambient Temperature without a Heatsink... 

Of course the only way to keep this 250W behemoth running for more than a minute without hitting the IC s internal OTP (over temperature protection) was to use a water-cooled heatsink, which my rather lab-ratty senior tech fashioned in less than half a day with some tubes, strips of metal, high-temp solder, and a sump (submersible pump). Note that the dissipation in the TO-220 was about 15W at this power level (calculated and measured). Yes, if you think that is a wee bit too much for a TO-220 to handle, I am on your side. 

Note If we want to know how much thermal resistance is typically attributable to thermal grease, we must remember that without this grease we would have air in the spaces between the device and heatsink, and that is a very poor thermal conductor. Thermal grease lowers this interface resistance significantly by filling the... 

For bolt-down heatsinks, a significant amount of the compressive load comes not from the heatsink weight but from the bolt down mechanism itself. Tolerance variations in package height, warpage, heatsink stand offs, and so on only make the applied load worse. The attachment mechanism should be such that it can accommodate these variations in tolerance without transferring excessive load to the package. 

---