Track 1 Session 6
10:30 to 11:30 a.m. Wednesday June 10, 2009

Calibrated Accelerated Life Test with Time Varying Stress Profiles to Verify Product Reliability Requirements

Many products are exposed to time varying stress profiles in their use level application. Using accelerated life tests (ALT) to verify reliability requirements with these profiles can be completed in a shorter time by applying calibrated accelerated life test (CALT) techniques and the time varying stress profile analysis capability of the ALTA 7 PRO software. Upper limits for each applied stress are determined first by noting the peak stress level. Accelerated profiles are determined based on the percentage decrease of the peak from the upper limit and the rest of the profile is developed proportional to the use level profile. CALT methods are used to determine the first two accelerated profiles and the third is determined from the life-stress plot of results from these two profiles. Life-stress plots are generated using the peak stress value in the time varying profile. Three to five samples are tested to failure at each level and life analysis is completed using ALTA 7 PRO to determine if the product can meet the reliability requirement. The results of testing on two products are used to illustrate the method.