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Author

Rao Tummala

Other affiliations: Qualcomm, IBM, AVX Corporation  ...read more
Bio: Rao Tummala is an academic researcher from Georgia Institute of Technology. The author has contributed to research in topics: Interposer & Capacitor. The author has an hindex of 43, co-authored 623 publications receiving 11663 citations. Previous affiliations of Rao Tummala include Qualcomm & IBM.


Papers
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Proceedings ArticleDOI
30 Aug 2005
TL;DR: In this article, the advances of technologies of high density interconnect substrates and PWBs, and demonstrates technology developments of small and reliable microvia and stacked via that matches the high pin counts and fine pitch area array flip chip for needs of the year 2009.
Abstract: The substrate or printed wiring board (PWB), as the largest component in electronic packages and systems, is performing an increasingly critical role in advanced packages, high performance electronic systems, and system-on-package (SOP) This paper reviews the advances of technologies of high density interconnect substrates and PWBs, and demonstrates technology developments of small and reliable microvia and stacked via that matches the high pin counts and fine pitch area array flip chip for needs of the year 2009 The paper also reviews breakthrough copper wiring density of line width and spaces less than 10 micron to route 4 rows in a 100 micron pitch With this technology it is possible to realize the target of semiconductor roadmap by the year of 2009 to route 4,600 I/Os to the inner layers by designing 1+n+1 structure

10 citations

Proceedings ArticleDOI
01 Oct 2013
TL;DR: Electrical characteristics of glass Interposer PDN is analyzed and compared with silicon interposer, and several resonance suppression methods are proposed such as decoupling capacitor scheme, ground via.
Abstract: Electrical characteristics of glass interposer PDN is analyzed and compared with silicon interposer. Because of the low loss of glass substrate compared to silicon substrate, glass interposer has much smaller loss than silicon interposer. It helps low-loss signaling, but it generates sharp PDN resonance unlike silicon interposer. If glass interposer signal line has through-glass via (TGV), it experiences high loss at the resonance frequency. Also P/G noise is easily coupled to signal line and vice versa at that frequency. It would be problems for the glass interposer PDN design. To overcome these problems of glass interposer, several resonance suppression methods are proposed such as decoupling capacitor scheme, ground via.

10 citations

Proceedings ArticleDOI
18 May 1997
TL;DR: In this paper, the design, fabrication and measurement of integrated passive structures using dielectric constants of 3.3 and 9.1, and thickness in the range of 10-21 /spl mu/m for wireless applications are discussed.
Abstract: Integration of passives is a continuous challenge towards achieving high performance packages with low profile, improved reliability, maximum packaging efficiency and low cost. This paper discusses the design, fabrication and measurement of integrated passive structures using dielectric constants of 3.3 and 9.1, and thickness in the range of 10-21 /spl mu/m for wireless applications. The use of polymer-ceramic composite material provides the design flexibility to combine both high dielectric constant and low dielectric constant materials within a single module. This allows for the design of matching networks, RF filters and ability to decouple power supplies for mixed signal applications with reduced size.

10 citations

Proceedings ArticleDOI
29 May 2001
TL;DR: In this paper, the authors studied and optimized the dispersion of nano-sized ceramic particles in PGMEA, which is the solvent for the selected host polymer, and measured porosity of thin film composites to study the impact of these processing parameters.
Abstract: This work focuses on studying and optimizing the dispersion of nano-sized ceramic particles in PGMEA, which is the solvent for the selected host polymer. High solids loading leads to entrapment of porosity in the microstructure, which lowers the effective dielectric constant of the films. The amount of solvent in the suspension and the spin coating speed were found to impact the dielectric constant of high filler content nanocomposites. The interplay between the rheological properties of the suspension and processing parameters such as solvent content and coating speed and its impact on the dielectric properties of the film is discussed. Porosity of thin film composites was measured for the first time to study the impact of these processing parameters. Powders of different particle sizes were mixed to obtain bimodal particle size distribution to increase the packing density of the composite. Packing density was improved by modifying the dispersion methodology and a nanocomposite of dielectric constant as high as 135 was obtained.

10 citations


Cited by
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Journal ArticleDOI

[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

Journal ArticleDOI
TL;DR: Shape-memory polymers as discussed by the authors are an emerging class of active polymers that can change their shape in a predefined way from shape A to shape B when exposed to an appropriate stimulus.

1,575 citations

Journal ArticleDOI
14 Feb 2008-Nature
TL;DR: This work establishes a methodology for scavenging light-wind energy and body-movement energy using fabrics and presents a simple, low-cost approach that converts low-frequency vibration/friction energy into electricity using piezoelectric zinc oxide nanowires grown radially around textile fibres.
Abstract: Nanodevices don't use much energy, and if the little they do need can be scavenged from vibrations associated with foot steps, heart beats, noises and air flow, a whole range of applications in personal electronics, sensing and defence technologies opens up. Energy gathering of that type requires a technology that works at low frequency range (below 10 Hz), ideally based on soft, flexible materials. A group working at Georgia Institute of Technology has now come up with a system that converts low-frequency vibration/friction energy into electricity using piezoelectric zinc oxide nanowires grown radially around textile fibres. By entangling two fibres and brushing their associated nanowires together, mechanical energy is converted into electricity via a coupled piezoelectric-semiconductor process. This work shows a potential method for creating fabrics which scavenge energy from light winds and body movement. A self-powering nanosystem that harvests its operating energy from the environment is an attractive proposition for sensing, personal electronics and defence technologies1. This is in principle feasible for nanodevices owing to their extremely low power consumption2,3,4,5. Solar, thermal and mechanical (wind, friction, body movement) energies are common and may be scavenged from the environment, but the type of energy source to be chosen has to be decided on the basis of specific applications. Military sensing/surveillance node placement, for example, may involve difficult-to-reach locations, may need to be hidden, and may be in environments that are dusty, rainy, dark and/or in deep forest. In a moving vehicle or aeroplane, harvesting energy from a rotating tyre or wind blowing on the body is a possible choice to power wireless devices implanted in the surface of the vehicle. Nanowire nanogenerators built on hard substrates were demonstrated for harvesting local mechanical energy produced by high-frequency ultrasonic waves6,7. To harvest the energy from vibration or disturbance originating from footsteps, heartbeats, ambient noise and air flow, it is important to explore innovative technologies that work at low frequencies (such as <10 Hz) and that are based on flexible soft materials. Here we present a simple, low-cost approach that converts low-frequency vibration/friction energy into electricity using piezoelectric zinc oxide nanowires grown radially around textile fibres. By entangling two fibres and brushing the nanowires rooted on them with respect to each other, mechanical energy is converted into electricity owing to a coupled piezoelectric–semiconductor process8,9. This work establishes a methodology for scavenging light-wind energy and body-movement energy using fabrics.

1,473 citations

Journal ArticleDOI
TL;DR: This work demonstrates the vertical and lateral integration of ZnO nanowires into arrays that are capable of producing sufficient power to operate real devices and uses the vertically integrated nanogenerator to power a nanowire pH sensor and a Nanowire UV sensor, thus demonstrating a self-powered system composed entirely of nanowiring.
Abstract: The lateral and vertical integration of ZnO piezoelectric nanowires allows for voltage and power outputs sufficient to power nanowire-based sensors.

1,465 citations

Journal ArticleDOI
TL;DR: In this paper, the authors focus on the important role and challenges of high-k polymer-matrix composites (PMC) in new technologies and discuss potential applications of highk PMC.

1,412 citations