Multilayer silicon RF system-in-package technique using magnetically aligned anisotropic conductive adhesive

In this work, we propose a novel packaging concept for highly-integrated RF systems using a magnetically aligned Z-axis anisotropic conductive adhesive. We demonstrate the ability to ldquogrowrdquo interconnects allowing for multilayer packages that are not sensitive to the height between pads. Using this effect we introduce two approaches to integrating multiple silicon wafers on top of each other, creating the possibility for an exceptionally dense integrated system-in-a-package. First, a reverse-pyramid package with all chips stacked facing down on a silicon substrate is demonstrated. Second, a ldquoMatryoshkardquo package assembled with the alternation of chip´s face direction is also demonstrated. The simplified assembly process of the Z-axis ACA and the new packaging concepts can offer a compact and cost-effective solution to system-in-package based RF systems.