A Low-Loss Fan-Out Wafer-Level Package With a Novel Redistribution Layer Pattern and Its Measurement Methodology for Millimeter-Wave Application

A low-loss fan-out wafer-level package (FOWLP) has been proposed for millimeter-wave application. To ensure the radio frequency (RF) signal transition in a ground-signal-ground (GSG) configuration, the signal structure in the redistribution layer (RDL) is tightly surrounded by its ground. Over a wideband, the proposed RDL structure results in a low loss and a good match at the RF port. Moreover, an efficient measurement methodology has been proposed for the millimeter-wave package. By adopting a 50Ω ceramic coplanar waveguide (CPW), performance of the millimeter-wave package is assessed by probes. This measurement method features quite a low measurement error because insertion loss of the added ceramic CPW is very small. By the proposed cascade de-embedding method, the parasitic effects resulting from the interconnections can be removed and the package performance can be achieved. The measured insertion loss for the proposed package is around 1 dB and the measured 10-dB return loss bandwidth is from 70 to 85 GHz.