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High silicon Si–Al alloys (50–70 wt% Si) have been developed by Osprey Metals Ltd for use in electronic packaging. They have the advantages of a coefficient of thermal expansion that can be tailored to match ceramics and electronic materials (6–11 ppm/K), low density (<2.8 g/cm³) high thermal conductivity (>100 W/m K). These alloys are also environmentally friendly and are easy to recycle.These Osprey alloys can be fabricated readily into electronic packages by conventional machining with tungsten‐carbide or polycrystalline diamond (PCD) tools and electro‐discharge machining (EDM). Generally more than one of these conventional machining operations is required in the fabrication process. A new and much faster method has been developed which has been used to produce complete electronic packages from plates of Si–Al alloys in a single machining step. In this novel method, known as thin‐shell electroforming (TSE), an accurate model of the package is produced directly from the drawing in wax using a 3D Systems ThermoJet Modeller. This model is mounted into a frame and it is then plated with a thin copper electroform. The wax model is then melted leaving the electroform attached to the frame. This is backfilled with solder and used as the EDM tool for machining the package from a plate of Si–Al alloy.

Electronic components’ efficiency is the cornerstone of technology progress. The cooling process used for electronic components plays a main role in their performance. Embedded high-conductivity material and provided microchannel heat sink are two common cooling methods. The former is expensive to implement while the latter needs micro-pump, which consumes energy to circulate the flow. The aim of this study is providing a new configuration and method for improving the performance of electronic components.

To manage these challenges and improve the cooling efficiency, a novel method named Hybrid is presented here. Each method's performance has been investigated, and the results are widely compared with others. Considering the micro-pump power, the supply of the microchannel flow and the thermal conductivity ratio (thermal conductivity ratio is defined as the ratio of thermal conductivity of high thermal conductivity material to the thermal conductivity of base solid), the maximum disk temperature of each method was evaluated and compared to others.

The results indicated that the Hybrid method can reduce the maximum disk temperature up to 90 per cent compared to the embedded high thermal conductivity at the same thermal conductivity ratio. Moreover, the Hybrid method further reduces the maximum disk temperature up to 75 per cent compared to the microchannel, at equivalent power consumption.

The information in this research is presented in such a way that designers can choose the desired composition, the limited amount of consumed energy and the high temperature of the component. According to the study of radial-hybrid configuration, the different ratio of microchannel and materials with a high thermal conductivity coefficient in the constant cooling volume was investigated. The goal of the investigation was to decrease the maximum temperature of a plate on constant energy consumption. This aim has been obtained in the radial-hybrid configuration.

The set of properties required for microwave packaging materials intended for aerospace applications is discussed in relation to the current range of materials that are commercially available. Initiatives are being taken to replace kovar, the established packaging material, with substitutes which are lighter, stiffer and offer superior heat‐sinking. Promising in this regard are new family of beryllium‐beryllia and also silicon‐aluminium (Si‐Al) alloys high in silicon, with ratios of constituents chosen such that they optimally complement gallium arsenide MMIC devices and alumina circuit boards. Both types of material are relatively easy to machine and electroplate. Demonstrator microwave amplifier modules incorporating the Si‐Al alloys have been designed for space applications and have been successfully produced and tested. The manufacturing technology that has been developed for this purpose is described.

This study aims to capture the heat transfer and entropy generation characteristics of temperature-dependent nano-encapsulated phase change material (NEPCM) slurry in a hybrid wavy microchannel. In addition, the effect of substrate material combined with NEPCM slurry on conjugate heat transfer condition is captured for different microchannel heat sinks.

A novel “hybrid wavy microchannel” is proposed to enhance the overall heat transfer and reduce the pressure drop by combining wavy and raccoon geometry. NEPCM–water slurry is implied in the hybrid wavy, conventional wavy and raccoon microchannel. A user-defined function (UDF) is used to observe the effect of phase-change of paraffin material in thermophysical properties of NEPCM–water nanofluid. All three (hybrid, wavy, raccoon) microchannels are engraved on a rectangular substrate of 1.8 mm width (ωs) and 30 mm length (L), respectively. For hybrid, wavy and raccoon microchannel, waviness (γ) of 0.067 is selected for the investigation.

The result shows that NEPCM particle presence reduces the fluid domain temperature. The thermal performance of proposed Heat sink 2 is found better than the Heat sink 1. The effect of the geometrical modification, wall thermal conductivity, different volumetric concentrations of nanoparticles (ϕ ∼ 1 – 5%) and Reynolds number (Re ∼ 100 – 500) on thermodynamic irreversibility is also observed. Additionally, the effect of thermal and frictional entropy generation is reduced with a combination of NEPCM slurry and higher conductive material for all heat sinks.

A combination of NEPCM slurry with laminar flow microchannel cooling system emerged as a better alternative over other cooling techniques for higher power density devices such as microprocessors, electronic radar systems, aerospace applications, semiconductors, power electronics in modern electronic vehicles, high power lasers, etc.

The phase-change process of the NEPCM slurry is tracked under conjugate heat transfer in a hybrid wavy microchannel. Furthermore, the phase-change process of NEPCM slurry is captured with different heat sink materials (SS316, silicon and copper) under conjugate heat transfer situation for different heat sinks and concentrations (ϕ ∼ 1–5) of NEPCM.

The purpose of this paper is to analyze numerically the nanofluid natural convection inside a square enclosure with two L-shaped heaters using lattice Boltzmann method.

An environmentally friendly nanofluid, clove-treated graphene nanoplatelet (CGNP), is used to study the enhancement of heat transfer. Six various heaters configurations are considered and effects of nanoparticle concentration (0–0.1%) and Rayleigh number (10^3–10^6) on streamlines, isothermal lines and heat transfer parameters are studied. The developed computational code has been validated using mesh sensitivity analysis and numerical data of other authors.

It is observed that in contrast to distilled water, CGNP/water nanofluid is an efficient coolant and the Nusselt number is increased as the nanoparticle concentration and Rayleigh numbers increment. The nanoparticle concentration cannot change the flow pattern inside the enclosure. However, the Rayleigh number and heaters configuration can change the flow pattern significantly. Several heaters configurations (Cases 1–4) related to the symmetry of geometrical shape and corresponding boundary conditions, illustrate the symmetry of streamlines and isotherms about the vertical line (X = 0.5). The formation of vortices inside the enclosure is affected by the raising heat plume above the heaters. Moreover, at different Rayleigh numbers, the relative magnitude of average Nu for various cases is different. At Ra = 103, the energy transport characteristic depends on the relative location of heaters and cold walls, and the order of average Nusselt number is Case 3 ˜ Case 4 ˜ Case 6 > Case 1 ˜ Case 2 ˜ Case 5. However, at Ra = 106, an influence of thermal convection mechanism on heat transfer is significant and the ranking of average Nusselt number is Case 1 ˜ Case 4 > Case 5 > Case 6 > Case 2 > Case 3.

The originality of the research lies in both the study of thermogravitational convection in a closed chamber with two L-shaped heaters, and the analysis of the influence of control parameters for an environmentally friendly nanoliquid on electronics cooling process.

This paper aims to compare the electronic properties of perylene diimide derivatives (DFPDI) and its anion radical (DFPDI.^-k.⁺) thin film by drop-coating of organic molecules on the interdigitated electrodes.

The authors compared the electronic properties of perylene diimide derivatives and its anion radical by drop-coating of organic molecules on interdigitated electrodes. Significantly, the current of perylene diimide derivatives anion radical increased by 2∼3 orders of magnitude compared to perylene diimide derivatives under a bias of 5 V, and the maximal current of anion radical that from tetrahydrofuran solution can reach 3.6 mA. Furthermore, DFPDI.^-k.⁺ thin film showed time-resistance sensitivity for acetic acid. When DFPDI.^-k.⁺ thin film was placed in acetic acid of 3.1 × 105 ppm, the current was decreased 46 times under a bias of 6 V after 8 min.

We developed the new method to prepare ambient stable perylene diimide derivatives anion radical, which shows sensitivity of absorption spectra to acid.

Perylene diimide derivatives anion radical thin film showed time-resistance sensitivity for acetic acid, suggesting potential application of perylene diimide derivatives anion radical as acid sensor.

The purpose of this paper is to develop nitrogen-enriched carbon (NC) with high conductivity and specific capacitance as electrode materials for supercapacitors.

Graphene oxide (GO) was synthesized by the modified Hummers–Offeman method. NC was synthesized by carbonization of melamine formaldehyde resin/graphene oxide (MF/GO) composites. Supercapacitors based on Ni(OH)2/Co(OH)2 composites as the positive electrode and NC as the negative electrode were assembled. The electrochemical performances of NC and supercapacitors are studied.

The results show that obtained NC has high nitrogen content. Compared to NC-GO0 without GO, high conductivity and specific capacitance were obtained for NC with GO due to the introduction of layered GO. The presence of pseudocapacitive interactions between potassium cations and the nitrogen atoms of NC was also proposed. When the weight ratio of GO to MF is 0.013:1, the obtained NC-GO3 has the highest specific capacitance of 154.07 F/g due to GO and its highest content of N-6. When the P of the asymmetric supercapacitor with NC-GO3 as the negative electrode is 1,326.70 W/kg, its Cps and Ep are still 23.84 F/g and 8.48 Wh/Kg, respectively. There is only 4.4 per cent decay in Cps of the supercapacitor over 1,000 cycles.

NC is a suitable electrode material for supercapacitors. The supercapacitors can be used in the field of automobiles and can solve the problems of energy shortage and environmental pollutions.

NC based on MF/GO composites with high nitrogen content and conductivity was novel and its electrochemical properties were excellent.

This paper aims to study the thermal and thermo-hydraulic performances of ferro-nanofluid flow in a three-dimensional trapezoidal microchannel heat sink (TMCHS) under uniform heat flux and magnetic fields.

To investigate the effect of direction of Lorentz force the magnetic field has been applied: transversely in the x direction (Case I);transversely in the y direction (Case II); and parallel in the z direction (Case III). The three-dimensional governing equations with the associated boundary conditions for ferro-nanofluid flow and heat transfer have been solved by using an element-based finite volume method. The coupled algorithm has been used to solve the velocity and pressure fields. The convergence is reached when the accuracy of solutions attains 10–6 for the continuity and momentum equations and 10–9 for the energy equation.

According to thermal indicators the Case III has the best performance, but according to performance evaluation criterion (PEC) the Case II is the best. The simulation results show by increasing the Hartmann number from 0 to 12, there is an increase for PEC between 845.01% and 2997.39%, for thermal resistance between 155.91% and 262.35% and ratio of the maximum electronic chip temperature difference to heat flux between 155.16% and 289.59%. Also, the best thermo-hydraulic performance occurs at Hartmann number of 12, pressure drop of 10 kPa and volume fraction of 2%.

The embedded electronic chip on the base plate generates heat flux of 60 kW/m2. Simulations have been performed for ferro-nanofluid with volume fractions of 1%, 2% and 3%, pressure drops of 10, 20 and 30 kPa and Hartmann numbers of 0, 3, 6, 9 and 12.

The authors obtained interesting results, which can be used as a design tool for magnetohydrodynamics micro pumps, microelectronic devices, micro heat exchanger and micro scale cooling systems.

Review of the literature indicated that there has been no study on the effects of magnetic field on thermal and thermo-hydraulic performances of ferro-nanofluid flow in a TMCHS, so far. In this three dimensional study, flow of ferro-nanofluid through a trapezoidal heat sink with five trapezoidal microchannels has been considered. In all of previous studies, in which the effect of magnetic field has been investigated, the magnetic field has been applied only in one direction. So as another innovation of the present research, the effect of applying magnetic field direction (transverse and parallel) on thermo-hydraulic behavior of TMCHS is investigated.

The purpose of this paper is to present a comparative study, regarding cooling time and dimensional accuracy, of conventional injection mold cooling channel layouts, using straight holes and a baffle, and free‐form fabricated (FFF) layout, manufactured by the direct‐metal rapid tooling (RT) method electron beam melting (EBM). Many other methods have been proven useful for RT, but the authors have not found any publications where EBM has been used to manufacture injection molding tools.

A test part was designed in order to replicate a common and important issue: inadequate cooling in deep cores. The part and the different cooling layouts were analyzed in an injection molding simulation software and the numerical results were compared with corresponding experimental results.

The analyses showed an improvement in both cooling time and dimensional accuracy in favor of conformal FFF cooling channels manufactured by EBM. The experimental results correlate well with the numerical tests, however with some discrepancies.

The results presented are based on the direct‐metal RT method EBM, and they were obtained using a specific test part.

This paper can be a useful aid when designing mold tools and especially when considering the usage of FFF cooling channels versus conventional cooling design. It can also serve as a reference when comparing the efficiency in terms of cooling time and dimensional accuracy between different layouts.

The aim of this work is to determine the optimal number and location of the fin(s) for maximum laminar forced convection heat transfer from a cylinder with multiple high conductivity radial fins on its outer surface in cross‐flow, i.e. Nusselt number, over a range of Reynolds numbers.

The effect of several combinations of number of fins, fin height, and fin(s) tangential location on the average Nusselt number was studied over the range of Reynolds numbers (5‐150). The problem was investigated numerically using finite difference method over a stretched grid. The optimal number and placement of the fins, for maximum Nusselt number, was determined for several combinations of Reynolds number and fin height. The percentage improvement in heat transfer per fin(s) unit length, i.e. cost‐efficiency, was also studied.

The results indicate that the fin(s) combination with the highest normalised Nusselt number is not necessarily the combination that results in the highest fin cost‐efficiency.

The results of the study can be used to design highly efficient cross‐flow forced convection heat transfer configurations from a horizontal cylinder with minimum cost.