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The relationship between temperature and reliability in electronic systems
By Mathew Rehm, Joint-Managing Director, Relec Electronics T
he reliability of electronic systems is paramount in ensuring their optimal performance and longevity. One of the most significant factors affecting this
reliability is temperature. As electronic components operate, they generate heat, and if not managed effectively, this heat can lead to premature failures and reduced system lifespans. This paper delves into the intricate relationship between temperature and reliability, highlighting the profound effects of temperature on electronic components, particularly semiconductors and we explore the origins of the rule that states that failure rates will double for a 10 degree rise in temperature. At Relec Electronics, we understand the critical role that
thermal management plays in the design and operation of electronic systems, offering tailored solutions to meet these challenges.
The Arrhenius Equation and its implications At the heart of understanding the temperature-reliability relationship is the Arrhenius equation, a fundamental formula in chemistry and physics that describes the temperature dependence of reaction rates. In the context of electronics, it can be used to predict the rate of failure or degradation of components based on temperature. A simplified version of the Arrhenius equation is:
This equation can be simplified to:
For our rule of thumb to be accurate, this ratio should be approximately 2, indicating that the failure rate doubles with a 10°C increase.
Typical Activation Energy Ranges To determine the range of Ea values that satisfy this condition, one would need to solve the above equation for Ea given a specific initial temperature T and the desired ratio (2 in this case). The exact range of Ea values will vary based on T, but for many electronic components operating in typical ambient conditions (around 25°C or 298K), Ea values often fall within the range of 0.5 to 1.5 eV (electron volts) to make the rule of thumb approximately true with some common devices listed below. Semiconductors: • Silicon Transistors and Diodes: 0.6 to 0.7 eV • Gallium Arsenide (GaAs) Devices: 0.8 to 1.0 eV • Integrated Circuits (ICs): 0.6 to 1.2 eV (depending on the specific technology and failure mechanism)
Where: • Rate is the failure rate or reaction rate. • A is a pre-exponential factor. • Ea is the activation energy or energy barrier that must be overcome for a specific failure to occur. • k is the Boltzmann constant. • T is the absolute temperature (in Kelvin). The exponential term in the Arrhenius equation is
pivotal in determining the temperature dependence of the failure rate. To discern the influence of a 10°C increase in
temperature, we compare the failure rates at two temperatures: T & T+10 (where the 10 is in Kelvin, representing a 10°C increase). Using the Arrhenius equation, the ratio of the failure rates at these temperatures is:
10 February 2025
www.electronicsworld.co.uk
Passive Components: • Ceramic Capacitors: 0.8 to 1.1 eV • Electrolytic Capacitors: 0.6 to 0.9 eV (The primary failure mechanism is often the evaporation of the electrolyte, which can be temperature sensitive.)
• Film Capacitors: 0.9 to 1.2 eV Resistors: • Carbon Composition: 0.7 to 0.9 eV • Metal Film: 0.8 to 1.0 eV • Wirewound: 1.0 to 1.3 eV • Inductors and Transformers: 0.9 to 1.2 eV (primarily for insulation degradation)
Connectors and Solder Joints: • Solder Fatigue: 0.5 to 0.7 eV • Electromigration in Solder: 0.6 to 0.8 eV • Connector Contact Degradation: 0.7 to 1.0 eV • Printed Circuit Boards (PCBs):
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