HASS development method: screen development, change schedule, and re-prove schedule

HALT (highly accelerated life testing) and HASS (highly accelerated stress screen) are two very powerful tools that can help manufacturers achieve high reliability quickly both in the design phase and in the manufacturing phase. HALT is used in the design phase to help reduce the number of design-related problems. HASS is used in the production phase to help reduce the number of infant mortality types of failures. HALT is always performed prior to developing a HASS profile because the HASS profile uses the information from HALT when choosing the profile parameters. Screens for HASS are always developed using a HASS development process. The goal of HASS development is to provide the most effective and quickest screen possible. The effectiveness of the screen is measured in its ability to find defects in the product without removing significant life. This paper describes different methods of developing a screen using the HASS development methodology and gives guidelines on when to change a screen and when it is necessary to re-submit a product through the HASS development process in order to reprove a screen.