As power circuit designs and devices proliferate in products such as LED drivers, HID lighting, motor control and electric vehicles it is becoming important to understand themal effects in active devices. All active devices dissipate power, and power active devices dissipate lots of power. This power dissipation creates heat which must be removed by some means to prevent excessive heat buildup inside a package or module which ultimately would lead to destruction of the appliance, circuit or device. One of the ways devices can be made safer, thermally that is, is the use of a passve heat sink. The role of the heat sink in active device thermal management is explored in a recent report released by Signal Processing Group Inc.’s technical staff and may be found in: http://www.signalpro.biz>engineer’s corner>heatsink.pdf.