Mechanical integrity of the IC device package-a key factor in achieving failure free product performance

A methodology has been developed to maximize product hardware integrity and practically eliminate service affecting field failures. This methodology starts with the analysis of the field failures reported over a period of 5 to 10 years. Failed parts are analyzed and similar failures are reproduced in laboratory conditions. This procedure allows researchers to identify the failure mechanisms and the factors that initiate and accelerate device degradation. Contrary to general belief, silicon temperature was eliminated as a major failure cause. In fact, a very weak correlation was found between silicon maximum temperature and field failure probability. Temperature cycling due to power and environmental changes was found to have a stronger impact on overall device reliability. Device packaging and especially the silicon chip interconnect were found to be the most sensitive part of the entire assembly. The degradation of the device packaging occurs, in most cases, faster than the degradation of the silicon itself. Most of the parts fail mechanically long before any apparent degradation of the device electrical performance