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Surface configuration at the interface between two materials makes a huge difference on thermal resistance. Thermal transient analysis is a powerful tool for thermal characterization of complex structures like LEDs. The purpose of this paper is to report the influence of surface finish on thermal resistance.

Surface of heat sink was modified into two categories: machined as channel like structure; and polished using mechanical polisher and tested with 3W green LED for thermal resistance analysis.

The observed surface roughness of rough and polished surface was 44 nm and 4 nm, respectively. Structure function analysis was used to determine the thermal resistance between heat sink and MCPCB board. The observed thermal resistance from junction to ambient (R_thJA) value measured with thermal paste at 700 mA was lower (34.85 K/W) for channel like surface than rough surface (36.5 K/W). The calculated junction temperature (T_J) for channel like surface and polished surface was 81.29°C and 85.24°C, respectively.

Channelled surface aids in increasing bond line thickness. Surface polishing helps to reduce the air gaps between MCPCB and heat sink and also to increase the surface contact conductance.

The proposed method of surface modification can be easily done at laboratory level with locally available techniques.

Much of the available literature is only concentrating on the design modification and heat transfer from fins to ambient. There was little research on modification of top surface of the heat sink and the proposed concept would give good results and also it will make the material cost reduction as well as material too.

Proper thermal management is a key to improve the efficiency and reliability of light-emitting diodes (LEDs). This paper aims to report the influence of applying thermally conductive materials on thermal performance of indium gallium aluminum phosphide (InGaAlP)-based thin-film surface-mounted device (SMD) LED.

The LED thermal and optical parameters were determined using the combination of thermal transient tester (T3Ster) and thermal and radiometric characterization of power LEDs (TeraLED) instruments. The LED was mounted on FR4, 2W and 5W aluminum (Al) package substrates. Measurements were carried out by setting different boundary conditions: air between LED package and substrate and using thermally conductive epoxy (TIM A) and adhesive (TIM B) of thermal conductivity 1.67 and 1.78 W/mK, respectively.

For LED mounted on FR4 package, the total real thermal resistance is improved because of TIM B by 6 and 9 per cent at 50 and 100 mA, respectively. Likewise, the relative decrease in total thermal resistance of LED on 2W Al package is about 9 and 11 per cent. As well, for LED mounted on 5W Al package, the total real thermal resistance is reduced by 2 and 4 per cent.

No much work can be found in the literature on thermal interface material effects on thermal performance of low-power SMD LED. This work can assist in thermal management of low-power LEDs.

This paper presents a new discretization technique of the hydrodynamic energy balance model based on a finite‐element formulation. The concept of heat source lumping is introduced, and the thermal conductivity model includes the effect of varying both carrier concentrations and temperatures. The energy balance equation is formulated to account for kinetic energy as a convective flow. The new discretization method has the advantage that it allows for assembling the functions out of elementary variables available over elements instead of along element links. Therefore, theoretically, calculation of the Jacobian should be three times faster than by the classic method. Results are given for three examples. The method suffers from mathematical instabilities, but provides a good basis for future work to solve these problems.

This paper explains why the data with which thermal designers have to work is uncertain and incomplete. It then describes how accepting this uncertainty unlocks the shackles of accurate temperature prediction and gives the designer the freedom to tackle the different aspects of thermal design at an appropriate and simple level. The latter part of the paper concentrates on the thermal design of circuit boards, first for steady state and then for transient operation.

The paper presents an alternative solution to address part obsolescence. This paper discusses approaches to solve part obsolescence including an uprating approach. This paper also describes the methods to uprate parts, and demonstrates the practical application of the uprating approach in the form of a case study.

This paper has been written to provide an understanding of the uprating approach to mitigate the problems caused by part obsolescence. The paper discusses the challenge faced due to part obsolescence, the temperature ratings for electronic parts, the uprating methods and finally explains the use of uprating to mitigate part obsolescence in the form of a case study. The part being uprated is a microcontroller unit used in many avionics applications. The case study describes a particular use of uprating and the return on investment.

Based on the uprating approach, it was discovered that for the particular application, the commercially available plastic quad flat pack microcontroller could be used as a substitute for the “military” ceramic BGA version, which was discontinued by the manufacturer. It was discovered that there would be no problem with the commercial part's quality or reliability for the particular application. Parametric tests showed no evidence of instability of electrical characteristics over the uprated temperature range. There was substantial return on investment due to the use of uprated parts.

This paper can help electronics manufactures deal with part obsolescence. This paper demonstrates the practicality of uprating parts. Uprating can save companies money by reducing the need for life‐time buys, substitution of parts and even redesign.

The paper provides an alternative approach to address the problem of part obsolescence. This paper shows that proper uprating leads to cost saving while continuing to provide reliable service.

The Purpose of this research is to make an energy efficient finite state machine (FSM) in order to achieve the core objective of green computing because FSM is an indispensable part of multiple computer hardware.

This study uses ultra-scale plus FPGA architecture in place of seven-series field-programmable gate array (FPGA) for the implementation of the FSM design and also uses output load scaling for the design of environment-friendly FSM. This design study is done using Verilog Hardware description language and Vivado integrated system environment design tools and implemented on 16 nm ultra-scale FPGA architecture.

There is up to 98.57% reduction in dynamic power when operating frequency is managed as per smart job scheduling. There is up to a 21.97% reduction in static power with proper management of output load capacitance. There is up to 98.43% saving in dynamic power with the proposed management of output load capacitance.

The proposed design will be environment friendly that eventually leads to the green earth. This is the main motive of the research area i.e. green computing.

The purpose of this paper is to find the optimum inverter type as the solder joint reliability point of view.

In this paper, finite element model(ing) simulations supported with power cycling aging experiments were used to demonstrate the best inverter type as the solder joint reliability point of view.

It was found that inverter types highly affect the solder joint health during its nominal operating.

The authors confirm the originality of this paper.

The purpose of this paper was to develop the methodology of thick-film/low temperature co-fired ceramic (LTCC) multilayer thermoelectric microgenerator fabrication including the procedure of silver-nickel thermocouples integration with LTCC.

To miniaturize the structures and to increase the output parameters (generated voltage, electrical power), the microgenerator was designed as multilayer systems. It allows to reduce size of the system and to increase the number of thermocouples integrated inside the structure. It also protects buried thermocouples against exposure to harmful external factors (e.g. moisture, oxidation and mechanical exposures). As a substrate, LTCC was used. For the thermocouples fabrication, thick-film pastes based on silver and nickel were chosen. Ag/Ni thermocouple has nearly three times higher Seebeck coefficient and 30 per cent lower electrical resistance than the combination of Ag/PdAg used in previous works of the author.

A multi-layer thick-film thermoelectric generator based on LTCC and Ag, Ni pastes was fabricated. Thirty Ag/Ni thermocouples were precisely screen-printed on few layers. Thermocouples’ arms are 15 mm long and about 150 μm wide. Interlayer connections (via-holes filled with conductive paste) provided the electrical contact between the layers. The biggest fabricated harvester consisted of 90 miniature thermocouples buried inside the LTCC.

The paper presents the results of research that provided to optimize the co-firing process of the LTCC/Ni set. In the result, the methodology of co-firing of silver-nickel thermocouples and LTCC ceramic was elaborated. Also, the methodology of fabrication of miniature thermoelectric energy harvesters was optimized.

The measurement of heat flux is of importance to the development of aerospace engine as basic physical quantities in extreme environment. Heat radiation is one of the basic forms of heat transfer phenomenon. The structure optimizing can improve the performance and infrared absorptivity of the thin film sensor.

This paper designed one kind of thin film heat flux sensor (HFS) with antireflective coating based on transparent conductive oxide thermopile. The introduced membrane structure is so thin that it has little impact on sensor performance. Fabrication of thin film sensors were fabricated by physical vapor deposition (PVD) process.

The steady-state and dynamic response characteristics of the HFS were investigated by calibration platform. The experimental results shown that the absorptivity of the membrane structure (for1070nm) improved compared with that before optimization. The sensitivity of heat flux gauge was 48.56 µV/ (kW/m2) and its frequency response was determined to be about 1980 Hz.

The thin film HFS uses thermopile based on Indium Tin Oxid and In2O3. The antireflective coating is introduced to hot endpoint of HFS to improve sensitivity on laser thermal source. The infrared optical properties of membrane layer structure were investigated. The steady-state and the transient response characteristics of the heat flux sensor were also investigated.

An understanding of reliability physics, failure analysis and failure mechanisms as applied to semiconductor technologies is essential in assessing microcircuit reliability. The use of valid thermal accelerated tests and the correct use of the data therefrom is crucial in assessing reliability. Improved technical data are required from most manufacturers if user analysis of accelerated testing is to be more easily and accurately carried out.