The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Increasing demands for electrical equipment efficiency has renewed interest in improving the electrical and thermal efficiency of industrial equipment. Variable speed drives are typically air-cooled and fall under recent international standards for improved fan efficiency. This paper details the modeling, design optimization, and experimental verification approaches used to optimize blower housing...
Electronic interconnects may encounter damage under exposure to vibration and mechanical shock. The damage may manifest itself as an open circuit after a finite period of operation. The traditional methods for damage detection such as microscopy and x-ray are destructive in nature and provide limited information offline. In this paper, resistance spectroscopy and phase-sensitive detection based state...
In this work, we have used test chips containing piezoresistive sensors to characterize the in-situ die surface stress evolution during thermal cycling of flip chip ceramic ball grid array (FC-CBGA) components suitable for microprocessor packaging. The utilized (111) silicon test chips were able to measure the complete three-dimensional stress state (all 6 stress components) at each sensor site being...
Cell temperature is critical to the life and performance of a battery pack, therefore accurately modeling the complete thermal system is important. Traditional approaches use complex 3D heat transfer and CFD or use a 1D network solver for quick prediction of flow and thermal fields. The 1D and 3D models are linked to get an overall system model. However, this coupling procedure can be tedious and...
High-concentration photovoltaics (HCPV) is a highly promising technology to directly convert plentiful solar energy to electricity. However, even for the most advanced HCPVs, about 60% of the concentrated solar energy is rejected as waste heat; therefore, it is desirable to utilize the massive waste heat from HCPV modules. Considering the nature of low-grade waste thermal energy, a microscale organic...
The development in light technologies for entertainment is moving towards LED based solutions. This progress is not without problems, when more than a single LED is used. The amount of generated heat is often in the same order as in a conventional discharge lamp, but the allowable operating temperature is much lower. In order to handle the higher specific power (W/m3) inside the LED based lamps cold...
This paper reports the thermal performance of smart heat sinks (SHSs) consisting of hybrid pin fins (HPFs) containing internal channels and integrated with plate fins. The SHSs are mainly aimed at cooling high power LED modules under natural convection condition or forced convection condition with a moderate air velocity. The computational fluid dynamics (CFD) models of SHSs are generated utilizing...
Reliable operation of today's data centers requires a tremendous amount of electricity to power both the IT equipment and the supporting cooling facilities. As much as half of total data center electricity consumption can be attributed to the cooling systems required to maintain the thermal status of IT equipment. In order to lower the electricity usage of the cooling system and hence reduce the data...
Driven by need to reduce energy use, many new data centers are built with air-side economizers. This method of bringing in outside air as the primary cooling resource greatly reduces overall facility power by eliminating need for the compressors and pumps required by chilled water and refrigerant based cooling systems. However, system fans are still necessary to supply and move large amounts of air...
In this study, we highlight the use of micro-Raman spectroscopy to measure vertical temperature gradients within Light Emitting Diodes (LEDs), ranging from the temperature of the growth substrate, the temperature of regions adjacent to the MQWs, as well as the p-GaN contact layer adjacent to the p-contact metallization. Depth-sensitive micro-Raman temperature measurements are compared with IR spectroscopy...
Polymer based materials are widely used in electronic packaging. The molding compound, in particular, comprises a significant portion of the package with the purpose of protecting the chips from the environment. Material characterization of molding compounds, therefore, has been a critical issue in predicting the thermo-mechanical behavior and reliability of electronic packaging. One of the distinctive...
This study discusses the optical characteristics of Ultra-High-Brightness LEDs (UHB-LEDs) at high current density. The wafer bonding technique was applied in this research to enhance the light extraction efficiency of AlGaInP UHB-LEDs. This technique can replace the GaAs substrate with transparent substrates for achieving the high quantum efficiency. However, the structure that designed for light...
The effect of temperature exposure encountered both during assembly and in fielded products, has a known influence on glass transition temperature of printed-circuit board (PCB) laminate materials. Printed circuit board laminates such as FR4 are composites of epoxy resin with woven fiberglass reinforcement. Interaction between manufacturing process variables that impact the changes in glass transition...
In this work, the viscoelastic mechanical response of a typical underfill encapsulant has been characterized via rate dependent stress-strain testing over a wide temperature range, and via creep testing for a large range of applied stress levels and temperatures. The 60 × 3 × 0.5 mm test specimens were dispensed and cured with production equipment using the same conditions as those used in actual...
The convergence and miniaturization of the consumer electronic products such as cell phones and digital cameras has led to the vertical integration of packages i.e., 3-D packaging. 3-D chip stacking is emerging as a powerful tool that satisfies such Integrated Circuit (IC) package requirements. 3-D technology is the trend for future electronics, especially hand-held, hence, making it an important...
A means to passively effect liquid motion parallel to the surface through surface modifications is presented. The geometry considered is that of repeated array of silicon ratchets with reentrant cavities located on the shallow face of each ratchet. The surface is heated on the bottom side using a thin-film serpentine heater. Experiments were performed using deionized water at atmospheric pressures...
The paper summarizes part of a project that was undertaken to develop highly energy efficient warm liquid cooled servers for use in chiller-less data centers that could save significant data center energy use and reduce data center refrigerant and make up water usage. One of the key concepts developed as part of this project is the Dual-Enclosure-Liquid-Cooling (DELC), which comprises of a 100% liquid...
This study investigates the feasibility of integrating thermoelectric devices into a large-capacity heat exchanger (up to 100 kW). Typically, thermal-electrical conversion is inefficient and thermoelectrics are only used in low-power applications (<1 kW). The incentive for using thermoelectrics, however, lies in their compact size, light-weight, high reliability, and sub-ambient cooling [1,2]...
The thermal performance of an air-cooled data centre with raised-floor and hard-floor configurations are compared with respect to the room and ceiling return strategies. The supply heat index, rack cooling index and number of racks that exceed the maximum recommended and allowable rack inlet air temperature according to ASHRAE's thermal guidelines, are used to evaluate the thermal performance. Numerical...
The ensemble Monte Carlo simulation is used to calculate the Joule heating per unit length of single-walled carbon nanotubes under an electric field applied through the nanotube axis. The electronic system and the ionic system are decoupled from each other. The rate of energy transferred from the electronic system to the ionic system in the form of the emission or absorption of longitudinal acoustic...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.