Published online by Cambridge University Press: 21 March 2011
Fine pitch area array packages are often assembled to flexible printed circuit boards, which require numerous low-frequency mechanical deflections. The interconnect package reliability emphasis has become focused more on isothermal bending fatigue. The interconnect failures due to bending fatigue were found to be different than those which occur if the packages were subjected to accelerated temperature cycling. A test method has been developed to evaluate isothermal mechanical bending fatigue reliability of area array packaging. Mechanical fatigue results of 1.0, 0.8, and 0.75 mm pitch packaging will be presented, demonstrating the effect of package substrate material properties on fatigue life and fracture morphology. Numerical finite element analysis results will also be presented to support and expand the findings in this study.