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Evaluating the Impact of Prolonged Thermal Cycling on Automotive Reliability

Posted by James McLeish on Nov 11, 2016 9:30:00 AM

Thermal-Cycling-Auto-Reliability.jpgAutomotive electronics are routinely exposed to harsh environments that introduce internal and external factors that could cause failure. Of particular concern is thermal cycling since automobiles are ideally designed to last more than a decade, during which time regular and frequently major temperature fluctuations occur. Long-term product life combined with prolonged thermal cycling present unique failure risks.

Traditional CAD tools are limited in identifying and mitigating these risks. However, thermo/mechanical automotive electronics reliability can be accurately predicted using powerful computational fluid dynamics (CFD) software in conjunction with 3D design analysis.

Common Failure Mechanisms

Electronics failure for automotive applications and others typically fall within three broad categories:

  • Mechanical failure that presents in a variety of ways including excessive component deformation, yield, crack and fracture; Coefficient of Thermal Expansion (CTE) variance; shock; vibration
  • Corrosive failure generated primarily by disproportionate humidity or exposure to aggressive chemicals
  • Electrical failure caused by thermal runaway or other uncontrolled positive feedback that results in temperature spikes and destructive outcomes; electrical overstress; and, electron migration

The breadth and varying degree of failure risk makes root causes of failure elusive in design-build-test-fix methodologies. However, there is another method that is capable of producing detailed profiles and data for failure mitigation in the design stage.

Electronics Thermal Analysis Software

Thermal analysis software that uses advanced CFD (computational fluid dynamics) techniques predicts airflow, temperature and heat transferring of components, PCBs and complete systems. Mentor Graphic’s FloTHERM thermal analysis delivers right-by-design products that save design time and reduce the need for physical prototyping, particularly when the comprehensive thermal profiles are paired with Sherlock Automated Design Analysis™ software.

Sherlock imports layout and thermal plots from FloTherm or similar analysis programs and uses that data to leverage part information (BOM, pick and place) and plot layers (ODB++, Gerber, etc.) in constructing PCBs and accurately predicting reliability prior to prototyping.

The value of software-generated results cannot be underestimated when evaluating automotive electronics lifecycles. Engineers can quickly access precise, critical data related to:

  • Composite life curve
  • Vibration fatigue
  • Plated Through Hole fatigue
  • Solder joint fatigue
  • Empirical failure rate calculations

Harnessing the power of CFD and Sherlock Automated Design Analysis™ software is a critical step in ensuring thermo/mechanical automotive electronics reliability. Contact us to learn how Sherlock can work for you.

Learn more about the science behind product reliability in Integrating Design and Reliability: The Power of Physics of Failure. Click the button below to download your free copy.

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Topics: Sherlock