Summary of HALT and HASS results at an accelerated reliability test center

Abstract

Accelerated reliability testing is one of the fastest growing segments of the testing industry because it enables the user to determine the reliability of a product quicker, therefore being able to affect the design quicker. HALT and HASS (highly accelerated stress screen) are special types of accelerated reliability techniques that are very effective and are being used by companies around the world from many different industries. HALT is used at the design stage of a project to quickly expose the weakpoints of a design so that the product can be re-designed to remove these weakpoints, thereby expanding the margins of the design. All of this can be achieved at a minimal cost increase, if any at all. HASS is used at the manufacturing stage of a project to quickly expose any manufacturing flaws that a particular sample may have. The two principle stresses used during HALT and HASS are rapid temperature transitions and OmniAxial (6 degree-of-freedom) random vibration. This paper analyzes HALT and HASS data from 33 different companies from a variety of industries and illustrates the following concepts: HALT can be applied to a wide variety of electrical and electro-mechanical products. Products today are much more robust than in the past and, therefore, these methods are necessary to improve product reliability. Random vibration is much more effective than temperature cycling for accelerating defects, and the combined environment of random vibration and temperature cycling is even more effective still. The types of failures that HALT and HASS discover are the same types of failures that are found in the field.