High-Density Small Form-Factor Package with Polygon-Shaped Capacitor Based on Silicon Technology

This paper suggests a unique silicon capacitor shape to provide a very competitive package form-factor with limited height condition. To locate a discrete capacitor on the BGA side of package, some solder balls must be depopulated to secure capacitor mounting space. Also to implement silicon based multi terminal capacitor with fine pitch bumped format, a conventional capillary underfill dispensing keep out zone should be considered. The removed solder balls may affect the system PDN with the decreased power connection or overall X-Y dimension expansion with the increased SOC functionality. To find an optimized shape and size against various BGA arrangement option, it is very important to have a successful product solution. A comparative study of various design concept of normal rectangular and polygonal shape of capacitor on BGA side with respect to area usage efficiency, maximum ball usage, and power integrity performance enhancement for high-density small form-factor package is described in this paper. The number of depopulated solder balls will be increased according to the use of multiple capacitors with rectangular shape. But, it can be optimized with one big polygonal shape and multiterminal of silicon capacitor. Interposer POP package for mobile device will be used as a target package type and the latest structure of substrate and ball pitch will be used for the study to reflect a realistic scenario.