Heat Dissipation in Electronic Devices

Key Takeaways

• When an electronic device gets overheated, components with thermal ratings less than the temperature developed get damaged.

• According to Newton’s law of cooling, the heat dissipation rate is proportional to the temperature difference between the body (electronic device) and the surroundings.

• The operating temperature can be limited by artificially increasing the surface area of a high power density component.

Heat sinks are a thermal management strategy applied to high power density electronic designs

The electronics industry is growing exponentially every day. Research and development activities in electronics now focus on transitioning devices from low performing, low-speed systems to high performance, high power density systems with high computational speeds. High power density electronic devices are achieved by making use of miniaturized components, thereby decreasing the footprint of circuits and their associated systems.

While it has its benefits, high power density poses a challenge for thermal management in electronic devices. Heat dissipation in high power density electronic devices is so difficult that it can critically affect the service life. For efficient heat dissipation in high power density electronic devices, innovative thermal management is necessary. Heat sinks are one such thermal management method that can be effectively applied to these designs.

In this article, we will discuss heat generation and dissipation in electronic devices as well as the suitability of heat sinks in high power density electronic devices.

Heat Generation in Electronic Devices

Electrical resistance is the main reason for the generation of heat in electronic devices. The impedance offered by the conducting paths to the flow of electric current generates heat in electronic devices, commonly called I2Rt losses. In the case of semiconductors, heat is generated in the PN junction and is transported from the junction to the casing. In general, the heat generated in electronic devices increases the temperature experienced by the components. When the electronic device overheats, components with thermal ratings less than the temperature developed get damaged. Heat-induced damages in electronic devices are often irreversible. 

Heat Dissipation in Electronic Devices

To avoid thermal-induced damages, the heat generated in electronic devices needs to be dissipated to the surroundings. The temperature rise in electronic devices seizes when the heat generated within it equals the heat dissipation to the surroundings. In that case, the electronic device attains thermal equilibrium.

According to Newton’s law of cooling, the heat dissipation rate is proportional to the temperature difference between the body (electronic device) and the surroundings. Whenever the heat dissipation rate in an electronic device equals the heat generation rate, the device is operating at the equilibrium temperature. The thermal equilibrium temperature of most electronic devices is detrimental to their service life and can even cause device failure in electronic systems.

High Heat Dissipation Rates in Electronic Devices

For the thermally-safe operation of electronic devices, the heat dissipation rate needs to be increased to achieve lower device operating temperatures than the thermal equilibrium temperature. The ambient conditions around electronic devices are crucial when considering heat dissipation strategies. High atmospheric density is an added advantage when trying cooling techniques to lower the device operating temperature. The reduced atmospheric density results in high device operating temperatures, as the ambient conditions of the electronic device are not supporting an increase in heat dissipation rates.

Thermal management technologies are employed in electronic devices to increase heat dissipation rates. For example, incorporating a cooling fan in the computer processor unit for forced air cooling is a thermal management technique employed for fast and efficient heat removal. The practice of providing general ventilation can establish a lower device operating temperature compared to the same setup without ventilation.

The most important aspect of increasing the heat dissipation rate in electronic devices is to provide enough surface area for the heat to dissipate from the body to the ambient. As the surface area increases, more heat is removed from the electronic device, resulting in low device operating temperatures.

The concept of surface area-based thermal management techniques fail when dealing with high-power density electronic devices. One of the techniques used in high power density electronic designs is the incorporation of heat sinks for achieving an increased heat dissipation rate. 

Increase Heat Dissipation With Heat Sinks

High-density electronic devices are smaller in size compared to their traditional counterparts, and as a result, the device operating temperature quickly increases beyond limits in such devices. As we discussed, one way of limiting the operating temperature of a high power density component is by artificially increasing its surface area. To do this, heat sinks can be attached to high power density devices for fast heat dissipation.

Generally, heat sinks are made of copper or aluminum and have fin structures that help in increasing the available surface area for efficient heat dissipation. The combination of heat sinks with other thermal management techniques, such as forced air cooling or well-ventilated enclosures, can increase the heat dissipation rates in congested electronic designs.

Heat dissipation in high power density electronic devices will continue to be critical. Innovative thermal management techniques are continuously being developed to reduce device operating temperatures. Cadence’s suite of design and analysis tools can help designers set up thermal management techniques suitable for specific electronic devices.

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