Manufacturability trade-offs of bare-die FCBGA package using thin or core-less substrate

Abstract

With the increasing demand for thinner packages and higher electrical & thermal performance requirement bare-die packaging is an inevitable trend that is growing. The assembly process for manufacturing of bare die in thin or core-less substrate FCBGA packages can be challenging especially considering the effects of substrate warpage during flip chip bonding and the excessive warpage of the flip chip package. We are evaluating the manufacturing risks during bare-die FCBGA package assembly to eliminate package warpage failures using experimental techniques and improve the functional performance of the flip chip package. Various substrate & under fill materials were tested for package warpage values for warpage-free control in the full range of temperature variation. Die designs at 28nm and 40nm process nodes are extremely complex in order to achieve the highest electrical & thermal performance requirement. Die design constraints on advanced process nodes necessitate increased thermal dissipation requirements thereby requiring investigation of thermal solutions utilizing thermal interface materials (TIM) with heat-sink. The interaction of such thermal solutions with the bare die packages is evaluated using various trial and error for material selection, experimental and simulation techniques to improve the assembly process. This study also focuses on selection of thermal interface materials [TIMs] and heat sinks which have considerable impact on die integrity during package assembly and/or during process of removal for failure analysis.