Interfacial thermal stress analysis of anisotropic multi-layered electronic packaging structures

The presence of dissimilar material systems and thermal gradients introduce thermal stresses in multi-layered electronic assemblies and packages during fabrication and operation. The high stress gradients near the free edge of bonding interfaces of such structures may cause cracking and delamination leading to the failure or malfunction of electronic assemblies and packages. A simple but accurate engineering approach for the calculation of interlaminar thermal stresses due to thermal mismatch in multi-layered structures is needed so that designers can determine interlaminar thermal stresses easily without much computational efforts. A few approaches based on the generalized deformation theory have been published but most of them are only suitable for structures with symmetric layers. For electronic packages and assemblies, unsymmetric layers are often used. An improved approach, Classical Laminate Theory-Edge Stress Shape (CLT-ESS), for prediction of interlaminar thermal stresses that can be applied to multi-layered structures with unsymmetric layers is presented. Comparisons are made with finite element analysis results and are found to be favorable. The proposed approach provides an efficient way for the calculation of interlaminar thermal stresses. [S1043-7398(00)00901-4].