Review on thermal energy storage with phase change: materials, heat transfer analysis and applications

Light-Emitting Diodes. (Monographs in Electrical and Electronic Engineering.) By A. A. Bergh and P. J. Dean. Pp. viii+591. (Clarendon: Oxford; Oxford University: London, 1976.) £22.

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Light-emitting diodes

Gallium oxide (Ga2O3) is emerging as a viable candidate for certain classes of power electronics, solar blind UV photodetectors, solar cells, and sensors with capabilities beyond existing technologies due to its large bandgap. It is usually reported that there are five different polymorphs of Ga2O3, namely, the monoclinic (β-Ga2O3), rhombohedral (α), defective spinel (γ), cubic (δ), or orthorhombic (e) structures. Of these, the β-polymorph is the stable form under normal conditions and has been the most widely studied and utilized. Since melt growth techniques can be used to grow bulk crystals of β-GaO3, the cost of producing larger area, uniform substrates is potentially lower compared to the vapor growth techniques used to manufacture bulk crystals of GaN and SiC. The performance of technologically important high voltage rectifiers and enhancement-mode Metal-Oxide Field Effect Transistors benefit from the larger critical electric field of β-Ga2O3 relative to either SiC or GaN. However, the absence of clear demonstrations of p-type doping in Ga2O3, which may be a fundamental issue resulting from the band structure, makes it very difficult to simultaneously achieve low turn-on voltages and ultra-high breakdown. The purpose of this review is to summarize recent advances in the growth, processing, and device performance of the most widely studied polymorph, β-Ga2O3. The role of defects and impurities on the transport and optical properties of bulk, epitaxial, and nanostructures material, the difficulty in p-type doping, and the development of processing techniques like etching, contact formation, dielectrics for gate formation, and passivation are discussed. Areas where continued development is needed to fully exploit the properties of Ga2O3 are identified.

A review of Ga2O3 materials, processing, and devices

International Technology Roadmap for Semiconductors 2003の要求清浄度について － シリコンウエハ表面と雰囲気環境に要求される清浄度, 分析方法の現状について －

Small, light weight and multifunctional electronic components are attracting much attention because of the rapid growth of the wireless communication systems and microwave products in the consumer electronic market. The component manufacturers are thus forced to search for new advanced integration, packaging and interconnection technologies. One solution is the low temperature cofired ceramic (LTCC) technology enabling fabrication of three-dimensional ceramic modules with low dielectric loss and embedded silver electrodes. During the past 15 years, a large number of new dielectric LTCCs for high frequency applications have been developed. About 1000 papers were published and ∼500 patents were filed in the area of LTCC and related technologies. However, the data of these several very useful materials are scattered. The main purpose of this review is to bring the data and science of these materials together, which will be of immense help to researchers and technologists all over the world. The comme...

Low loss dielectric materials for LTCC applications: a review

Themal optimization of compact solar water heaters

Shrinking chip feature sizes and increasing performance demands are resulting in non-uniform on-chip power dissipation. Sub-millimeter regions of high heat flux are developing with heat fluxes exceeding the average chip flux by a factor of six to ten and peak heat fluxes approaching 1000 W/cm2. These "flux-spots" can yield locally high temperatures ("hotspots") and extreme thermal gradients which can degrade chip performance and compromise reliability. This paper will explore the potential for spreaders and thermal interface materials (TIMs) of anisotropic thermal conductivity to mitigate on-chip hotspots. When used together with an existing global cooling solution, such anisotropic materials, bonded directly to the back of the silicon chip, can conduct heat laterally away from the flux-spot and towards cooler areas of the chip that are subjected to lower heat flux. An available analytical solution for the temperature distribution in a perfectly attached bi-layer slab, subjected to a central rectangular heat flux region, is used to study hotspot remediation with such an orthotropic TIM/spreader. The parametric sensitivity of the hotspot temperature to the in- plane conductivity, TIM/spreader thickness, chip thickness, flux-spot size, and heat transfer coefficient are studied, along with the detrimental effects of an interfacial contact resistance.

Hotspot remediation with anisotropic thermal interface materials

The rapid increase in on-chip heat fluxes and package heat density, accompanying the migration to nanoelectronics and 3D chip stacks, has placed thermal management squarely on the critical path for advanced product development. Innovative, cost-effective cooling techniques, combined in a synergetic way with more conventional approaches, must be developed if the benefits of the Moore's Law progression are to be realized. Following a brief discussion of the industry roadmap for IC packaging and review of chip package thermal management options, attention will turn to the application of solidstate thermoelectric refrigeration and the thermal characteristics of direct immersion cooling in dielectric liquids. The presentation will close with a discussion of the research challenges associated with the commercial implementation of on-chip thermoelectric coolers and direct liquid cooling.

Thermal management of on-chip hot spots and 3D chip stacks

http://ieeexplore.ieee.org/iel1/33/4507/00180032.pdf

Thermal Characterization of a PLCC

The methodology and results of a Monte Carlo optimization of component placement on a printed circuit board are presented. The overall reliability of the component mix on the printed circuit board is the criterion of optimality. Arrhenius relations are used to quantify the effect of temperature on the component failure rate. The finite element code called ANSYS is used to determine the temperature distribution in two conductively cooled printed circuit boards. The various strategies of the Monte Carlo annealing and cluster optimization methods and the effect of the relevant parameters on board reliability are discussed. >

Avram Bar-Cohen

Papers

Themal optimization of compact solar water heaters

Hotspot remediation with anisotropic thermal interface materials

Thermal management of on-chip hot spots and 3D chip stacks

Thermal Characterization of a PLCC

Monte Carlo thermal optimization of populated printed circuit board