April 12, 2023
Assessing the robustness of an electronic product is integral to successful design and performance. Highly accelerated life testing (HALT) is an important testing tool for this purpose, and its effectiveness can be maximized through careful planning prior to setup and detailed execution.
HALT is the process of applying increased stressors to an electronic device to force failures and uncover design and construction weaknesses. The stressors applied are typically well beyond the expected field environments to quickly discover failures. This enables engineers to optimize designs, repair or replace failed components, and lower product development costs.
Setting clear expectations and directives for conducting HALT is a multistep process that starts with bringing the design engineers together to:
In conjunction with developing the foundational outline, two key areas must be addressed.
1. Applicable Stresses
Select the appropriate stresses and stress levels for testing:
Choosing the appropriate stresses is dependent upon the application and the environment in which the device operates. Suspect parts or areas of concern within the device can also help drive what stress levels to apply in test.
2. Step Stress Approach
For each intended stress, clearly delineate:
Typically, the operating and destructive limits of the device are not known prior to testing. HALT testing can be used to determine this through the step-stress approach. If failure occurs during monitoring or functional testing, the stress is subsequently reduced until the DUT recovers from the failure. This failure is known as the operating limit. When the stress is increased above the operating limit and the DUT can no longer recover without a repair, the destruct limit has been reached.
For accurate results, particular attention must be paid to the HALT configuration:
HALT is comprehensive and encompasses several testing phases, each with specific parameters to follow.
Thermal step-stress testing applies incremental temperature stress levels throughout the product life cycle in order to identify product failure modes.
Thermal shock cycling is conducted between the DUT’s operating limits determined above. This exposes the DUT to fast thermal transitions, sometimes 60 ˚C per minute or as fast as the testing equipment/chamber allows.
Vibration step stress testing applies incremental vibrational stress levels in order to identify product failure modes.
Merge testing results and methodologies to further test products.
Once HALT is completed, the design engineers’ focus becomes determining the root causes of all failures and corrective action. This can include identifying the failure site and failure mechanism for each failure mode. Afterwards, a verification HALT needs to be implemented to evaluate if testing adjustments fixed the problems.
Ansys Sherlock can shortcut this process by creating simulations based on testing models before any physical sample modification or the verification HALT takes place, saving time and money. In addition, our Reliability Engineering Services team can perform Accelerated Life Testing once the weak points in the design have been resolved and final testing required.
Contact us today to discuss how we can help streamline your HALT process and accurately confirm results.
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