Georgia Tech and its industry partners demonstrate pioneering advances in 3D Glass-based RF modules and Integrated Passive Devices (3D IPDs) as the next stage of evolution, beyond LTCC and organic 2D MCM organic and embedded modules.
Georgia Tech’s 3D IPAC approach enables 2X shrinkage in X-Y form factor and 2X smaller in thickness than LTCC and organic modules.It also enables superior performance from high-Q LC integration with better than 5% tolerance from precision lithography in contrast to ceramic modules, lower-loss interconnections between components leading to insertion losses of <0.5 dB. Glass provides ultra-smooth and dimensionally-stable substrates for high-throughput and large-area (1000 mm) panel processing with low cost. These advances are expected to enable the miniaturization, integration, performance and cost demands for emerging 5G front-end modules and their convergence with IoT and automotive communications.
Georgia Tech proposed 3D Integrated Passive and Active Component (3D IPAC) based glass RF modules and 3D IPDs in 2013, for unparalleled miniaturization, performance and cost. The 3D IPAC RF Module starts with an ultra-thin substrate (30-100 microns) made of glass, with ultra-low electrical loss and ultra-short through-package vias for double-side assembly of active and passive components separated by only about 50 µm in interconnect length. Actives and passives are embedded or assembled double-side on the glass using ultra-short, low-temperature and fine-pith copper interconnections. The module also integrates thermal and shielding functions with innovative structures and materials.
Several technology breakthroughs were accomplished to demonstrate such RF IPDs and modules. High-density through-vias in bare glass were formed from unique via-machining techniques by Georgia Tech’s partners such as Corning and Asahi Glass. Innovative tools and processes were developed for large glass panel handling with thinfilm low-loss build-up dielectrics, in partnership with Georgia Tech’s consortium members such as Atotech, NGK-NTK, Shinko and Unimicron. Advanced 3D TPV-based inductor designs were developed for high Q and high-density inductors, while inorganic nanodielectrics and nanomagneto dielectrics were utilized for further miniaturization of capacitors, inductors and EMI shield structures. Precision panel-level lithography was achieved for accurate microwave impedance matching with less than 5% tolerance. Double-side assembly was also demonstrated with such ultra-thin glass substrates.
Georgia Tech’s 3D IPD-based diplexers are 4X thinner compared to traditional approaches, with similar performance. With advanced thinfilm and high-density passive components, and design innovations, much superior performance is targeted in the next phase of the R&D program from 2016-2018. Georgia Tech and its partners also demonstrated ultra-miniaturized LTE and WLAN modules with its 3D IPAC approach with double-side integration of LNA, switch and filters. Good model-to-hardware correlations were seen from the module characterization of LNA gain and entry-to-exit insertion loss, illustrating the performance benefits of 3D IPAC modules. In the next phase, Georgia Tech is extending this concept further to complete PAMiD module integration with integrated thermal and shielding structures for LTE FDD/TDD, 5G and mm wave applications.
For more information about Georgia Tech’s Integrated Passives and Actives, please contact Prof. Rao Tummala at rao.tummala@ece.gatech.edu or Dr. P.M. Raj at raj.pulugurtha@prc.gatech.edu.
About the Authors
Dr. Raj Pulugurtha is the Program Manager for Integrated Passive and Actives as well as High-Temp Electronics at Georgia Tech PRC. raj.pulugurtha@prc.gatech.edu
Dr. Rao Tummala is Director of Georgia Tech’s Packaging Research Center. He is also a Chaired Professor in ECE and MSE. rao.tummala@ece.gatech.edu.