Abstract
Recent customer demands and advances in technology are expanding the use of flip chip ICs. The higher coefficients of thermal expansion differences and fragile nature of assemblies have made underfilling mandatory for product survival in the field. This article describes a few techniques employed for failure analysis of these complex devices: epoxy development, substrate pre-encapsulation, universal polishing media, cyanoacrylate use, substrate analysis, plan view sectioning/inspection, die backside polishing for infra-red inspection, and chemical deprocessing. Almost all of the techniques presented will involve traditional cross sectioning tools which can be applied to flip chips. These techniques include improvements to the traditional material analysis cross section as well as aids for die level electrical analysis and visual inspection methods. The article demonstrates that with the use of the described techniques, and literally no investment, any lab which can presently perform semiconductor related cross-sections, will be able to confidently expand into flip chips.
