ABSTRACT
The Highly Accelerated Stress Screening (HASS) process typically helps to reduce screen time and move a product more quickly into the Monitoring Phase. Thus, knowledge of the Highly Accelerated Life Test and HASS environmental limits, relative to a customer specification, is very helpful in providing engineering confidence in the proper design of the screening and the subsequent monitoring test. If all processes were under complete control, product screening or monitoring would be unnecessary. Screening and monitoring programs are a major factor in achieving customer satisfaction. Screening may be simple, such as on-off cycling of the unit, or it may be more involved, requiring one or more powered environmental stress screens. Screens are constantly reviewed and may be modified based on screening yield results. Reliability improves when corrective-action fixes are incorporated into products with a screening program. The most common screens used are thermal cycling and thermal shock.
