The Relationship Between Temperature & Reliability
9th October 2023Share This Post
Share This Post
The 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 in electronics, 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.
The Arrhenius Equation and Its Implications
At the heart of understanding the temperature and reliability relationship in electronics 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:
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 Arrhenius Equation and Its Implications
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:
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.
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)
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 & 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):
It’s important to note that these values are approximate and can vary based on the specific design, materials, manufacturing processes, and operating conditions of each component. Additionally, each component can have multiple failure mechanisms, each with its own Ea value.
Mitigating the Effects of Temperature
To ensure the reliability of electronic systems, it’s imperative to manage and mitigate the effects of temperature. Some strategies include:
Effective Thermal Design
Incorporating heat sinks, fans, and other cooling mechanisms can help dissipate heat effectively.
Component Selection
Opting for components rated for higher temperatures or those designed for efficient operation can reduce the overall thermal load.
Thermal Monitoring and Feedback
Modern electronic systems often incorporate sensors to monitor temperature, adjusting system performance or triggering protective mechanisms if temperatures approach harmful levels.
Conclusion
The relationship between temperature and reliability in electronics systems is profound. As elucidated by the Arrhenius equation, even modest temperature increases can significantly reduce the lifespan of critical components, particularly semiconductors. By understanding this relationship and implementing effective thermal management strategies, designers and engineers can ensure the longevity and optimal performance of electronic systems.
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