A Heat Sink is a device that enhances heat dissipation by absorbing heat from a hot surface of your electronic device and radiating it to a cooler ambient material (usually air). Proper heat sink selection can solve a lot of thermal problems in your circuit. So how do you select a suitable heat sink for your application?
Before you select a heat sink, go through the following steps
understand whether your application uses Forced Air Flow (air is forcibly moved by a powered device, usually a fan or blower) or Natural Convection (air sits there and does what air does, moving only through natural processes).
calculate the thermal resistance and select the proper [parameters] (https://www.digikey.com/products/en/fans-thermal-management/thermal-heat-sinks/219) from our Heat SInks parametric filters
R = (Ts - Ta)/ Pd
R = Thermal Resistance of the heat sink
Ts= Temperature of heat sink mounting surface in thermal contact with the device to be cooled (in ºC)
Ta= Ambient air temperature (in ºC)
Pd = Power dissipation of the device
Note: If you can’t find a part with the exact thermal resistance the formula above calls for, it works to choose a heat sink with slightly lower than your calculated thermal resistance. Lower is good, higher is bad.
Select your other requirements for this heat sink - type of package cooled, size, height, shape,attachment method, and anything else your project requires.