Embedded 3D-IPD Technology based on Conformal 3D-RDL: Application for Design and Fabrication of Compact, High-Performance Diplexer and Ultra-Wide Band Balun

Abstract

In this paper, an embedded 3D-IPD technology based on conformal 3D-RDL that yields high performance, small-size and low-cost devices is presented. The technology relies on high-Q thin film capacitors and 3D inductors as well as on thru-mold-vias (TMV) and mold compound to form a surface mount 3D-IPD device (SMD). We demonstrate how to form TMVs simultaneously with 3D-inductors using 3D-RDL technology. Hence, no laser drilling nor tall Cu vias electroplating are required.A WLAN diplexer (2.4 5GHz) and an UWB balun (1.4 - 3GHz) where synthesized, fabricated and measured to demonstrate electrical performance of this technology. We first report the impact of 3D inductor's Q-factor on electrical performance of these devices and how to use this data to accurately assess real-life performance of inductors. Then, we demonstrate that low-loss (0.3dB and 0.56dB), high attenuation (24dB and 28dB) and high isolation (25dB and 29dB) are achieved for a 0.38mm2 3D diplexer. Whereas, an insertion loss <0.85dB, amplitude unbalance <0.5dB and phase unbalance <3° are achieved for 2.5 mm2 UWB balun. Reliability result is also presented here.