Abstract
Abstract Recently, the reducing of handheld devices has mainly been a strong development driver of combination memory package trends, such as mobile phones and personal digital assistants (PDA). The trend toward reducing package size is an important unit in today’s electronic packaging industry. The Stacked CSP is a good solution for reducing electronic product size. But the upper die size, lower die size and the material of die attachment will affect the stress during thermal cycling and power cycling. This paper using FEM (Finite Element Method) focuses on the different upper die size, lower die size and material of die attachment to simulate the stress between the upper die, lower die, and substrate. The thermal fatigue is the important factor in electronic packaging fracture and the shear stress will cause the die crack and delamination. According to the experiment we found the 3x5mm upper die and 6x8mm lower die using 0.06mm WBL die attachment having the lower shear stress, which is twenty times smaller than the set of 3x5mm upper die, 4x6mm lower die using 0.02mm Ag epoxy paste. .