Analyses of Delamination Arrest Effect of Dimples on Interface in LSI Package

The delamination arrest between die pad and resin should be an efficient method to prevent resin cracking of LSI packages. In some LSI packages, dimples arranged on the die pad are effective for delamination arrest. In this study, the effects of dimples on delamination arrest are examined based on boundary element analyses of LSI packages under conditions of thermal and steam pressure loading. To evaluate this effect, the stress intensity factor, K i , for an interface crack was calculated using the contact between interface crack surfaces. The following main results were obtained. (1) The dimple decreases K i under both thermal and steam pressure load conditions. (2) The main reason for decreasing K i is to prevent shearing deformation between crack surfaces under thermal load conditions. Conversely, the reason for the decrease is the kinking of interface crack tips under steam pressure load conditions. (3 ) The effect of delamination arrest increases as the dimple depth increases.