Electronic products and systems such as consumer electronic devices including computers and smartphones, as well as appliances such as television and refrigerators naturally generate heat as a byproduct of their operation and consumption of energy from an electric source or a battery pack. The heat they produce is generally safe. However, in certain circumstances or due to specific situations, overheating may occur, thus causing serious damages to the specific electronic components of a particular electronic device.
Damage to an electronic component is the potential and direct effect of overheating. Note that this is especially true if the particular component is unable to withstand excessive thermal levels. Engineering professors and researchers Y. Cengel and A. Ghajar noted that the susceptibility an electronic assembly or electronic device to fail increases exponentially with temperature. Furthermore, researcher V. L. Mehoke explained that there is a relationship between the performance of an electronic component and its particular range of operating temperature.
What happens when electronics overheat? How and why excessive levels of heat damage electronic components? This article cites and discuses studies examining and discussing the specific damaging effects of overheating on electronic components, as well as on electronic systems and devices.
The Specific Effects of Overheating on Electronic Components: How Excessive Heat Damages Electronic Products
Temperature essentially determines the performance and lifespan of an electronic product. Several studies have analyzed, uncovered, and discussed how exactly overheating affects a particular electronic component. The following discussion lists down and discusses the specific effects of overheating on electronic components.
1. Electron Tunneling and Hysteresis
Electron tunneling is a phenomenon in which an electron moves through a potential energy barrier due to the accumulation of energy. A 1994 study by A. N. Korotkov, M. R. Samuelsen, and S. A. Vasenco investigated the effects of overheating in a single-electron transistor or SET by directly and artificially applying excessive amounts of heat through current flow.
Results revealed that the heat applied to the SET resulted in electronic tunneling that decreased the temperature difference between the central and outer electrodes. Further excessive heat resulted in hysteresis in the IV curve of the SET.
As a backgrounder, in electronic circuitry, hysteresis is another phenomenon characterized by a change in the transfer characteristics of a circuit. While some hysteresis effects are intentional and needed in several electronic components, the researchers noted that the hysteresis they observed in the overheated SET displayed bi-stable characteristics.
2. Undesirable Interaction Between Particles
Another effect of overheating is that it triggers damaging and cyclic interaction between particles. Researchers Liao, Maznev, Nelson, and Chen investigated the interaction between electrons and phonons in a thin silicon wafer under normal and excessive levels of heat using three-pulse photo-acoustic spectroscopy.
Results showed that increasing the concentration of electrons in the silicon wafer resulted in electrons scattering the phonons. This scattering prevented the phonons from carrying away heat, thus increasing the tendency of overheating due to heat accumulation.
The study essentially demonstrated a cause-effect loop of overheating. A small piece of silicon or any semiconductor packed with electrons would normally generate heat due to their small area. However, based on the results of the study, more heat would be generated because it results in a higher concentration of electrons that in turn, results in the scattering of phonons.
3. Specific Damage to Capacitors
Several studies and references materials have also described the specific effects of overheating on specific types of electronic components. An article from professional magazine publisher EE Publishers extensively discussed how thermal stress due to overheating damages different types of capacitors. Take note of the following:
• Ceramic Capacitors: As noted in the article from EE Publishers explained, ceramic capacitors could suffer from dielectric breakdowns and micro-cracks when subjected under thermal stress due to overheating. The micro-cracks could also result in moisture absorption that in turn, would lead to a short circuit.
The crack can further expand and degrade the material integrity of the ceramic capacitor. It is worth mentioning that the damage due to overheating tends to be more pronounced in multi-layer ceramic chip capacitors or MCCs. This is due to thermal coefficient of expansion of different ceramic materials within an MCC.
• Electrolytic Capacitors: The same article from EE Publishers noted that electrolytic capacitors could fail due to thermal stress. To be specific, overheating decomposes the electrolyte and generates a build-up of gas that increases internal pressure.
Note that an electrolytic capacitor is a polarized capacitor that uses an electrolyte to achieve a larger capacitance than other types of capacitors. It is also worth noting that an electrolyte is a liquid or gel containing a high concentration of ions.
• Plastic Film Capacitors: With regard to plastic film capacitors consisting of polystyrene, polyester, polycarbonate, and metalized polyester materials, among others, they are not prone to cracks due to overheating, unlike ceramic capacitors. Furthermore, in the case of ruptures, they have the ability to self-heal.
However, prolonged exposure to excessive levels of heat can result in combustion. This is especially true when film capacitors are used in alternating current circuits in which overheating can cause combustion failure.
• Solid Tantalum Capacitors: Overheating due to current surges can result in material disintegration and dormant damage to the dielectric over time in solid tantalum capacitors. This is because solid tantalum capacitors, specifically those that include titanium oxide films, have surface imperfections and impurities that make them more vulnerable to thermal stress due to continuous exposure to excessive levels of heat.
It is important to highlight the fact that because capacitors are responsible for storing electric charge and filtering high-frequency components of the voltage, damage or material degradation would certainly affect the integrity of the entire circuit board. Furthermore, the performance of capacitors can affect the whole power supply of an assembled component or circuitry. Failures in capacitors usually lead to failures in other electronic components such as power transistors, metal-oxide–semiconductor field-effect transistor, and field-effect transistors, among others.
4. Alterations in Physical and Chemical Properties
Overheating also affects the physical and chemical properties of the specific constituents of electronic components. Y. Yun, W. Hongjin, and L. Jianguo studied the effects of overheating on the microstructure of Terfenol-D alloy. Their study showed that different excessive levels of heat resulted in different microstructures and crystal orientation. Overheating also affected the pattern and mode of solidification of this alloy.
Another study by W. Yang, B. Mo, S. J. Lianga, and F. J. Zhen examined the specific minuscule effects of overheating on copper wires. Remember that copper is a common conductive material used as part of electronic components. Findings revealed that overheating created a fatigue fracture surface on the copper wires. This means that excessive levels of heat can cause a directly noticeable physical effect on a particular material.
In the case of conductive materials such as copper, a fatigue fracture can affect the physical properties and material integrity in several negative ways. The study noted that the fatigue fracture surface observed at the overheated copper wire could further result in sparks that can generate internal combustion in the circuitry and subsequently, additional overheating and external fire.
Y. Cengel and A. Ghajar also noted that the thermal stress due to exposure to high levels of heat in the solder joints of a particular electronic component or an entire electronic assembly has been considered as one of the major causes of electronic systems failure.
The material coefficient of thermal expansion can result in structural deformation. This has been observed in specific constituents of an electronic component such as ceramics, metals, and plastics. Take note that thermal expansion is a phenomenon involving the expansion of a material in terms of size and volume upon exposure to specific levels of heat. Too much thermal expansion will certainly result in structural deformation.
FURTHER READINGS AND REFERENCES
- Cengel, Y. and Ghajar, A. 2015. Heat and Mass Transfer: Fundamentals and Applications. 5th ed. New York: McGraw-Hill. ISBN: 978-0073398181
- EE Publishers. 2014. “Thermal Stress on Capacitors: Failure Prevention.” EE Publishers. Available online
- Korotkov, A. N., Samuelsen, M. R., and Vasenco, S. A. 1994. “Effects of Overheating in a Single-Electron Transistor.” Journal of Applied Physics. 76(6). DOI: 10.1063/1.357424
- Liao, B., Maznev, A. A., Nelson, K. A., and Chen, G. 2016. “Photo-Excited Charge Carriers Suppress Sub-terahertz Phonon Mode in Silicon at Room Temperature.” Nature Communications. 7(13174). DOI: 10.1038/ncomms13174
- Mehoke, V. L. 2005. “Spacecraft Thermal Control. In ed. V. L. Pisacane ed., Fundamentals of Space Systems. 2nd ed. Oxford: Oxford University Press. ISBN: 978-0195162059
- Yang, W. Mo, B., Lianga, S. J. and Zhen, F. J. 2014. Numerical Study of Overheat Fault in Copper Wire Caused by Bad Contact Base on Multi-Physics coupling. Paper presented at the 7th International Conference on Intelligent Computation Technology and Automation, Changsha, China. DOI: 10.1109/ICICTA.2014.103
- Yun, Y., Hongjin, W., and Jianguo, L. 2011. The Effect of Overheating Treatment on the Microstructure of TbDyfe Alloys. Paper presented at the International Conference on Advanced Technology Design and Manufacture, China. DOI: 10.1049/cp.2011.1055