Environmental stress testing experiment using the Taguchi method

Manufacturing process improvements which increase productivity, decrease test process time, and improve customer satisfaction are highly desirable in today´s marketplace. The application of environmental stress screening (ESS) is a method of achieving these improvements. ESS is the application of stresses applied beyond product specification limits in order to find latent product defects. Utilizing ESS achieves increased robustness and lower infant mortality. An experiment was performed to identify the significance or relevancy of the selected stresses for application in the printed wiring board (PWA) production process by using a statistically significant controlled method. The design of experiments statistical approach (analysis of variance), is applied, combined with the Taguchi two-level, seven-factor design method. This experiment concentrated on three stresses (temperature cycling, random vibration, and power cycling) and two diagnostic levels: a prom-based (programmable memory chip), power-on self test (POST), and a functional diagnostic test suite, contained on disk storage. Note that this was not an optimization experiment. Once the significance to the production process is identified, future optimizing of temperature cycling, power cycling, and vibration screens, will be conducted. Also, voltage margining was not included so as to reduce the complexity of the experiment-treatment factors and interactions. Experimental results and conclusions on the effectiveness of different stress regimens are presented in this paper