Thermal management of electronic equipment is a critical task. Unlike situations involving heavy mechanics, when it comes to compact electronics, power supply engineers have to design inexpensive yet sophisticated solutions that function in tight spaces. Component technology has advanced to the point where devices can predict temperatures accurately.
The common approach is to use a datasheet to figure out the component’s rating and internal derating guidelines.
However, these estimates are based on approximations that don’t hold under all conditions. The result is equipment that is over-engineered and inefficient. In addition, many of these components have been known to fail when being shipped because ratings have been configured to account for everyday use, overlooking the high temperatures, jostling, and other extra stresses of freight situations.
Temperature tracking in electronic shipments is the best way to safeguard these products throughout the supply chain. While it’s challenging to accurately predict failure thresholds, all that effort is for naught if shipment temperatures aren’t monitored vigilantly.
Here are four thermal issues that affect critical components and how temperature tracking ensures product integrity.
Magnetics Lose Potency at Higher Temperatures
A robust temperature monitoring system helps companies define exact temperature ranges at which their components should be stored in transit. Defining these thresholds is essential since magnetic cores can go on a thermal runaway, which results in core loss and even higher temperatures.
Transformers and chokes typically receive almost no attention with regards to thermal degradation because they’re custom-designed. As such, most of them come without any guidance, and it’s hard to model them accurately or design safely around them.
Using Litz wire for reduced coil heating, higher frequency while reducing total turns, and maintaining the turns ratio are possible solutions to this problem. When shipping magnetics, sensors attached to cargo can ensure that conditions don’t exceed rated thresholds.
Combined with real-time alerts to relevant employees, organizations can rest assured that their shipments will always arrive in perfect conditions.
Optocouplers Fail Faster at Unsupported Temperatures
LED components are typically no issue for designers since they operate on low duty cycles and low forward current. However, when they’re paired with optocouplers, thermal management becomes more of an issue.
Optocoupler manufacturers typically don’t provide rated lifetime information. However, using the standard LED mean time to failure (MTTF) of 50,000 hours at a maximum rated forward current of 25C is useful. Note that the MTTF is the time it takes to reach 63%, not 100%, failure.
Using this information, it’s easy to calculate the ideal temperature at which the optocoupler has to be maintained. However, shipping them is still a challenge, since en-route conditions can compromise the temperature band in which they need to be transported.
This is where running analytics on temperature-related information signals, collected via logistics data loggers, helps. Once the ideal temperature range has been calculated, teams can define these thresholds for in-transit purposes. In addition to this, running analytics on prior shipments along the same route will lead to insight into any quirks that exist there.
For instance, weather conditions might tilt the temperature range to unacceptable levels and throw these components off balance. Analytics can help unearth optimal transportation routes that will ensure all components arrive with their integrity maintained.
Increased Evaporation Leads to Electrolytic Capacitor Failure
Electrolytic capacitors are perhaps the most vulnerable component to thermal degradation since high temperatures cause increased liquid evaporation.
The typical approach that power designers take is to extrapolate manufacturer ratings to actual use environments via an Arrhenius equation. This gives them a conservative estimate of capacitor lifetimes. Business requirements have led to pushback, and designers have now
become more aggressive with ripple currents and applying them above manufacturer ratings.
There isn’t a single foolproof solution to estimate capacitor failure ranges. The best option designers have is to keep an eye on temperature trends at all times. Sensors connected to product packaging during the manufacturing, storage, and shipping processes can help them understand how evaporation rates correlate to temperature trends.
Analytics applied to these data can also help unearth patterns that would be tough to discover manually. Everything begins with temperature monitoring and the wealth of data it provides manufacturers.
Thermo-Mechanical Fatigue Wears Out Solder Joints
Solder joints help maintain a board’s integrity. They aren’t an electronic component by themselves but are one of the most critical pieces of infrastructure that designers must take into account.
Temperature changes cause printed boards and components to expand and contract. This places a shearing load on second-level joints. While individual loads will typically be far lower than joint failure level, repeated temperature changes will weaken joints and reduce lifecycles.
Thermal monitoring is more important than ever since this gives designers real-time data and insight into the changes in strength over time. For instance, a joint that has been repeatedly exposed to varying temperatures will be far more likely to fail.
When shipping, constant monitoring will help designers understand joint reactions to temperature changes better. This is a better approach than relying on rated lifecycles, which are estimates at best.
Many Components, One Problem
Heat and thermal damage are two of the biggest issues that power designers have to deal with. While the design process takes them into account, there’s no better way, than to measure and track temperatures, until last-mile delivery, via smart logging processes.
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