Easy reliability design approach for solder joint BGA package considering correlation of each design factor

The recent development of electric and electronic devices has been remarkable. The miniaturization of electronic devices and high integration are progressing by advances in mounting technology. As a result, the reliability of fatigue life has been prioritized as an important concern, since the thermal expansion difference between a package and printed circuit board causes thermal fatigue. In addition, because the development time of the product is being intensified, shortening the development time and reducing the cost are important concerns. It is demanded a good quality product which has short development time. However, it is difficult to guarantee quality during the design phase, because it is hard to know which design factors will prolong the fatigue life. The authors have investigated the influence of various design factors on the reliability of soldered joints in BGA model by using response surface method. However, it became clear that this sensitivity analysis was not enough for reliability design because of the effect of design factor correlation. So, it is necessary that the correlations between design factors of BGA package should be clarified. In order to investigate correlations between design factors, the authors have proposed a new approach to emboss efficiently the each design factor by applying Cluster Analysis. By using this technique, the correlation structure of the all design factor was clarified. Based upon the analytical results, design engineers can rate each factor's effect on reliability and assess the reliability of their basic design plan at the concept design stage.