A novel decoupling capacitor for power integrity of quad flat nonlead (QFN) package

This paper describes the progressions for power and signal integrity issues on quad flat non-lead (QFN) package. A novel decoupling capacitor is achieved by modifying the footprint of QFN package. The modified footprint is connected to printed circuit board (PCB) power plane and coated the solder mask above. A large decoupling capacitor between power and ground is achieved by thin film solder mask and large size of die pad, which parallel to and decrease the input impedance of power delivery network (PDN) without parasitic effects at low frequency. After 2 GHz, adding more vias can decrease and shift the high impedance caused by equivalent inductance of via to high frequency. This novel decoupling capacitor is fully compatible with PCB process and significantly decreasing the high impedance of PDN.