Title:  Integrated 3D Glass Modules with High-Q Inductors and Thermal Dissipation for RF Front-end Applications

Committee:

Dr. Rao Tummala, ECE, Chair , Advisor

Dr. Andrew Peterson, ECE

Dr. Hua Wang, ECE

Dr. Oliver Brand, ECE

Dr. Yogendra Joshi, ME

Dr. Raj Pulugurtha, PRC

Abstract:

Today’s RF subsystems are 2D multichip packages that are made of either organic laminates or LTCC (low temperature co-fired ceramic) substrates. The need for form-factor reduction in RF subsystems in both z and x-y direction has led to the evolution of embedded die-package architectures in thin laminates or fan-out packages, with dies facing up or down. This also reduces insertion loss and improves signal integrity by minimizing package parasitics and routing issues. For further improvement in performance and miniaturization, Georgia Tech proposed and is developing glass as the ideal next generation substrate for RF module integration. However, major design and fabrication challenges need to be addressed to achieve ultra-thin high Q RF components and, also enable RF power amplifier (PA) cooling to eliminate hotspots on glass substrates without affecting the RF performance. This forms the key focus of this thesis. Thus, the objectives of this research are to model, design, fabricate and demonstrate miniaturized and high-performance RF components, thermal structures and integrated modules with advances in designs, materials and processes. High quality factor (Q > 100 at 2.4 GHz for 3-10 nH/mm2) inductors are demonstrated with 50-100 micron thick glass using 3D designs and fabrication processes. Innovative RF design-compatible thermal structures with copper through-package vias are designed and demonstrated to maintain low junction temperatures of < 85oC in power amplifier modules.  Dual-band (2.4GHz/5GHz) WLAN modules are demonstrated in ultra-thin glass substrates with double-side RF circuits and copper through-package vias (TPVs).