Numerical simulation of reliability of 2.5D/3D package interconnect structure under temperature cyclic load

Abstract

In view of the structural warpage deformation and stress-strain problems of 2.5D and 3D package structures under the temperature cycling environment, the causes of structural warpage deformation and the difference of stress and strain between the two structures are analyzed by combining the results of finite element simulations. The most critical solder joints life of the two structures are calculated. The results show that the thermal mismatch of the package structure under temperature cyclic load leads to periodic warping deformation of the structure. The accumulation of CTE mismatch caused significant difference of the warping deformation. The warpage of the 2.5D package structure is much larger than that of the 3D package. Induced by the package layout and structure different, the stress responses to the temperature loading are different between 2.5D package and 3D package are greatly different. The dangerous solder joints of 2.5D/3D package structure are all at the outer edge of the grid. Some high stress also performed at the triple parts interconnections, i.e. the TSV, solder joints and the die. The life prediction was also conducted according to the accumulated plastic strain of dangerous solder joints, which indicated that with the same size and materials of the package design, 2.5D package structure produce more damage to the interconnection and result to a shorter lifetime. An optimization design should be considered to utilize this type of package.