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 …

I and i

Shape-memory polymers

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.

http://www.nanoscience.gatech.edu/zlwang/paper/2008/08_nat_1.pdf

Microfibre–nanowire hybrid structure for energy scavenging

The lateral and vertical integration of ZnO piezoelectric nanowires allows for voltage and power outputs sufficient to power nanowire-based sensors.

http://www.nanoscience.gatech.edu/zlwang/paper/2010/10_NN_01.pdf

Self-powered nanowire devices.

Fundamentals, processes and applications of high-permittivity polymer–matrix composites

Verfahren zum herstellen von mehrschichtigen gesinterten glaskeramiksubstraten mit aus gold, silber oder kupfer bestehenden leitungsmustern und dadurch hergestellte substrate

This paper demonstrates six-metal-layer antenna-to-receiver signal transitions on panel-scale processed ultra-thin glass-based 5G module substrates with 50-Ω transmission lines and micro-via transitions in re-distribution layers. The glass modules consist of low-loss dielectric thin-films laminated on 100-μm glass cores. Modeling, design, fabrication, and characterization of the multilayered signal interconnects were performed at 28-GHz band. The surface planarity and dimensional stability of glass substrates enabled the fabrication of highly-controlled signal traces with tolerances of 2% inside the re-distribution layers on low-loss dielectric build-up thin-films. The fabricated transmission lines showed 0.435 dB loss with 4.19 mm length, while microvias in low-loss dielectric thin-films showed 0.034 dB/microvia. The superiority of glass substrates enable low-loss link budget with high precision from chip to antenna for 5G communications.

Design and demonstration of ultra-thin 3D glass-based 5G modules with low-loss interconnects

As microsystems continue to move towards higher speed and microminiaturization, the demand for interconnection density both on the IC and the package increases tremendously With the shift towards nano ICs by 2004 with <100 nm feature sizes, the area array I/O pitch will move towards 20-100 micron in the future The 2002 ITRS Roadmap Update identifies the need to support sub-100 /spl mu/m pitch flip-chip/WLP and data rates of 10Gbps in the package and board by the year 2010 The PRC and IME/NUS are developing 20-100 /spl mu/m pitch interconnects as part of the A*STAR nano-WLP program A critical part of this development involves board technology to simultaneously support wiring density to direct attach of these WLPs and high speed signals The choice of base substrate and thin film dielectric is critical to meet the electrical performance targets and achieve reliable assembly of fine pitch WLPs Modeling revealed that a low CTE substrate greatly enhances the reliability of all the interconnect solutions being pursued The fabrication process was done on 300 mm /spl times/ 300 mm and 300 mm /spl times/ 450 mm panel sizes using state-of-the-art printed wiring board and microvia processes Data rates of 5Gbps on board have been demonstrated for line lengths of 10 cm using A-PPE dielectric Fine pitch routing using 20 /spl mu/m lines and spaces on Hitachi E-679F low CTE laminate to support 200 /spl mu/m pitch pads have been demonstrated Initial substrates for 100 /spl mu/m pitch have also been designed and fabricated

Ultra-high density board technology for sub-100 /spl mu/m pitch nano-wafer level packaging

Glass interposers offer a compelling alternative to silicon interposers with highest I/Os and excellent electrical performance, with potential for low cost from large panel processing. For sub-32nm IC nodes and 3D-IC packages at fine I/O pitch, organic substrates are reaching their limits in terms of I/Os, design rules and CTE mismatch. Glass offers the best combination of electrical insulation, dimensional stability, CTE match to Si ICs, and flat, smooth surfaces for ultra-fine line lithography. The biggest challenge in glass interposers is the formation and metallization of ultra-fine pitch through vias. The formation of small via diameters in thin glass substrate have been demonstrated. The focus of this paper will be on wet metallization of glass interposer with through via, and addressing the challenge of providing reliable adhesion on the copper-to-glass interface. Two main approaches are currently pursued in the wet-chemical metallization of glass interposers: the electroless and electrolytic coppe...

Improvement of Plated Copper Adhesion in Glass Interposer Applications

Emerging fan-out packages require advances in mold compounds, polymer interfaces to metals and silicon, and innovative processing to reach the required high reliability. In this paper, we discuss the fracture energy for mold compound interface to copper and silicon, and use that information for studying interfacial delamination propagation of mold compound. We have examined mold compound delamination from silicon die as well as redistribution layer in a fan-out package, and compared the results against a lead-frame package as well as a plastic ball grid array package of similar dimensions.

Rao Tummala

Papers

Verfahren zum herstellen von mehrschichtigen gesinterten glaskeramiksubstraten mit aus gold, silber oder kupfer bestehenden leitungsmustern und dadurch hergestellte substrate

Design and demonstration of ultra-thin 3D glass-based 5G modules with low-loss interconnects

Ultra-high density board technology for sub-100 /spl mu/m pitch nano-wafer level packaging

Improvement of Plated Copper Adhesion in Glass Interposer Applications

Interfacial Delamanination of Mold Compound in Fan-Out Packages