The HALT tests are part of aggravated tests process for which the aim is to explore the use of a product beyond its specifications.
In practical, thermal and mechanical tests will be applied without taking care of the life cycle of the product. No stress level limits is set beforehand and vibration tests will be made even for a fixed equipment.
HALT tests don't reproduce an environment to check the use of an equipment. They test a product till they find its working limits or even its destruction limit.
The analysis of the failure causes and the corrective actions allow building the robustness of a product and perhaps running over its profile constraint to improve its reliability.
HALT tests are directly dealing with the 3 operational origins of failure:
Here is the HALT methodology for the application of the different stresses :
- Step by step temperature decrease (limit to -100°C)
- Step by step temperature rise/increase (limit to +200°C)
- Step by step "gRMS" vibration level increase (level depending on the product)
- Rapid Temperature Variation (60°C/min – level depending on the product inertia)
- Combined tests RTV and vibration
Specific constraint of the equipment may be added.
The HASS methodology carry out combined tests : vibrations, temperatures and RTV applied as cycles.
Before applying the HASS as control process of the manufacturing line several points have to be checked. The test profile detailing the constraints to apply have to be defined, the chamber which will host part or the entire production has to be optimized and the Proof Of Screen (POS) has to be validated.
The HASS profile comes from the tests realised with the HALT methodology.