Why: HALT tests are intended to quickly find failures and accelerate the improvement program so that when products are delivered to end users, they will be mature products by elimination of potential failure modes that would normally generate a reliability growth program. Usually the HALT programs reduce time, cost, and delays experienced in new products by recalls, warranty costs, etc. HALT is similar to HASS but the stresses are more severe. In the HALT process, design and process flaws are found, root causes identified, and corrective actions implemented quickly.
When: HALT is used during the development program to get engineers to acknowledge and correct fatal problems in designs by adding loads (generally temperature, vibrations, pressures, physical stresses, etc) by rapidly changing the load conditions over and above normal operating loads
Where: HALT is frequently used for electronic systems but also applicable to mechanical systems where thermal shocks are used to validate designs for extreme conditions of loads. The tests are performed in the laboratory for engineering evaluation.
These definitions are written by H. Paul Barringer and are also posted on his web site at www.barringer1.com