Application report from Texas Instruments on heatsink designs. Link here (PDF)
Power dissipation performance must be well understood prior to integrating devices on a printed-circuit board (PCB) to ensure that any given device is operated within its defined temperature limits. When a device is running, it consumes electrical energy that is transformed into heat. Most of the heat is typically generated by switching devices like MOSFETs, ICs, etc. This application report discusses the thermal dissipation terminology and how to design a proper heatsink for a given dissipation limit.