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 durin g fabrication and operation. The high stress gradients near the free edge o f bonding interfaces of such structures may cause cracking and delamination leading to the failure or malfunction of electronic assemblies and package s. A simple but accurate engineering approach for the calculation of interl aminar thermal stresses due to thermal mismatch in multi-layered structures is needed so that designers can determine interlaminar thermal stresses ea sily without much computational efforts. A few approaches based on the gene ralized deformation theory have been published but most of them are only su itable for structures with symmetric layers. For electronic packages and as semblies, unsymmetric layers are often used. An improved approach, Classica l Laminate Theory-Edge Stress Shape (CLT-ESS), for prediction of interlamin ar thermal stresses that can be applied to multi-layered structures with un symmetric layers is presented. Comparisons are made with finite element ana lysis results and are found to be favorable. The proposed approach provides an efficient way for the calculation of interlaminar thermal stresses. [S1 043-7398(00)00901-4].