Component Heat Dissipation

This Instructable will teach you how to select the right heat sink for your high-power electronic or electrical component. This component is a semiconductor that could be a diode, transistor, or IC (integrated circuit).

The heat resistance of the material is how well the material transfers heat via the heat conduction process. The lower the heat resistance the better the material is at transferring heat. Higher heat resistance means a higher difference in temperature between the two crossectional surfaces of the component and thus less heat conduction or loss of heat.

Each heat sink or box with a cooling fan has a specified heat resistance measured in degrees/Watt. You can use any of the two models shown to determine the right heat resistance and thus select the right heat sink and encasement with a cooling fan (if you need it).

You can use any of those models. The diagram shows an electronic circuit equivalent model for component power dissipation.

The current sources represent the component dissipated power in Watts, and the voltage source or potential voltage across the resistors represents the temperature or temperature difference between two crossectional surfaces. The resistors represent the material's heat resistance (degree/Watt). Those parts include:

• component,
• heat transfer paste (heat transfer compound),
• heat sink,
• box,
• and air.

The encasement to the ambient is the connection to the ambient environment that the encasement is in.

Simulation software: PSpice Student Edition Version 9.1 You can use other software, including online websites or one that you need to install.

You can do the simulations and vary the heat resistances and current sources (power dissipations) to optimise your heat dissipation system. You can also do calculations by summing the voltages of all resistors. The ideal current source ensures a constant current across the resistor regardless of the resistor or the supplied voltage source.