High Q-Factor 3D Tall Copper Pillar Inductor on a Wafer-Level Package for RF System Application

Inductors with high quality (Q) factor are essential for RF communication system, especially in sub-6GHz application. Integrating inductors in package process is also attractive because of the advantage of smaller form factor, less expensive and easier implementation. In this study, we utilize tall copper pillar and RDL process in the Fan-Out package to realize 3D solenoid inductors. The real measurement data shows Q value achieve 61.7 at 2.4GHz and 74.8 at 5GHz for a 1.55nH inductor, which is better compared to previous work in the Fan-Out package or integrated passive device (IPD).