The Thermomechanical Coupling Effect in Multi-layered Microelectronic Packaging Structures

Materials with different coefficients of thermal expansion (CTE) are usually bonded together to form laminated stacks in IC and MEMS. However, the thermomechanical coupling effect because of CTE mismatch will greatly affect the reliability and performance of the devices. In this paper, a theoretical model for warpage distribution of the chip surface in multi-layered microelectronic packaging structure is proposed. And a novel optical measurement approach named digital speckle correlation method (DSCM) was applied to study the actual warpage in this stack structure under certain temperature excursions. The test data are compared with the calculated out-plane displacements of both the theoretical model and FEM simulations