Thermal runaway is a situation where an increase in temperature changes how something functions in such a way that it generates more heat. It puts the object into a “death spiral” that keeps getting hotter and hotter until it burns up. In some electronic components, lower resistances or triggering voltages may occur as the temperature inside the casing increases. This can result in an increase in the circuit flow. If the existing thermal management solution can’t handle the increased heat, the temperature inside the casing gets hotter which lowers the resistances more, which increases the circuit flow… until the heat becomes too much and you have an electrical fire or an explosion.
Most good electronic system designs use thermal fuses or circuit breakers to prevent this from happening in the first place.
Other solutions by engineers include designing multiple lower-capacity devices such as diodes or transistors to work in parallel. But this has to be designed well to make sure that the electrical load is balanced so that the current doesn’t get funneled into the one circuit with the lowest resistance (AKA current hogging) which will be quickly overloaded and fail. In these cases, the system is only as good as its weakest component.
Semiconductors can fall prey to thermal runaway. Because of the nature of silicone, its electrical resistance increases with temperatures up to 160 degrees Celsius, once it goes over that threshold the electrical resistance starts decreasing and continues to drop when the melting point has been reached. This can result in thermal runaway in different regions within the semiconductor itself, with resistance decreasing in hotter regions which leads to less resistance, more current, and more heat until the semiconductor junction breaks down.
The simplest solution to preventing thermal runaway is to make sure that the heat sink design or other thermal management solution you use for the device adequately manages the heat to keep the internal temperature less than the temperature that lowers the electrical resistance. Keeping the circuit’s resistance consistent is the key to preventing thermal runaway.
Our heat sink designs are world-class, and we have the technology and engineering know-how to deliver the best thermal management solutions for electronics in the industry. Give us a call at 888-999-8499, contact us online, or send us an email at firstname.lastname@example.org to speak to one of our advanced thermal solutions experts today.