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Experimentally established, the influence of the working temperature and solar radiation power on the efficiency of industrial production silicon solar cells. Based on the experimental results designed the concept of a hybrid solar generating module equipped with a mirror concentrator of solar radiation and solar cells cooling system for using in high-performance solar energy station. Concentrator...
High-power Light Emitting Diode (LED) generates significant amount of heat fluxes that can affect the temperature-dependent properties of the device. This self-heating effect can upset the measurement setup and produce inaccurate readings, leading to misinterpretation of results such as electrical and thermal resistances. Optical, electrical and thermal performances of high-power LED packages were...
A deterioration diagnosis method for a Li-ion battery using its transient characteristic is proposed in this paper. The terminal voltage of the battery sharply increases at the beginning of the charging and gradually increases. The terminal voltage suddenly decreases at the end of the charging and decreases toward its internal voltage. The transient characteristic can be explained by the response...
This paper presents a possibility to evaluate a NTC (negative temperature coefficient) thermistor, which exhibits an exponential behavior, using a logarithmic circuit. The presented method allows a quicker and precise processing compared to look-up tables or linearizing circuits. The resistance value is converted into a galvanic isolated voltage signal. Furthermore the presented design is optimized...
LED products intended for outdoor applications need specific tests to evaluate its reliability. In this paper tests for detecting failures at high temperatures and currents below maximum current rating conditions, have been carried out. Open circuit catastrophic failures have been observed in these tests at a constant current. Failure mechanisms have been analyzed. Temperature and current acceleration...
In recent years, the brightness of light-emitting diodes with efficiency has reached a high level, and the next surge is in demand for various types of luminous equipments, such as those can be used in the urban landscape of electronic outdoor billboards, aviation and electronic equipment indicators, which can replace the automobile's headlights. Particularly in view of the safety factor, such as...
The present work reports some experimental results on the electrical properties of commercial Gallium Nitride blue light emitting diode (GaN blue LED). Many instruments have been used in this study to make different kinds of measurements. For example, Keithley 238 high current measure unit, Boonton 7200 capacitance meter, and Wayne Kerr 6440 precision component analyzer (within frequency range from...
In this study, we have investigated the high-temperature electro-optical degradation of DC-Aged InGaN based high power GaN LEDs. For this purpose, we fabricated large size blue InGaN/GaN LED chips (1mm??1mm) by using standard LED fabrication processes, where the ITO and Cr/Au served as p-type ohmic contact and n-ohmic contact layer, respectively.
The poor thermal design of high brightness light-emitting diodes (HB-LEDs) package for the automotive exterior lighting system causes the degradation of the optical and reliability performance, also the deterioration of the cost-effectiveness. We design the flexible package substrate with the thick heat-spreading layer and thermal via-hole fully filled with the copper (FFC) for the conventional process...
Nowadays the demand for thermal standards for power LEDs is increasing. On the one hand metrics for fair comparison of competing products are needed; on the other hand, designers of power LED-based applications demand reliable and meaningful data for their daily work. Today's data sheet information does hardly meet any of these requirements. In earlier papers we compared the current situation in the...
In this paper the accurate and fast measurement equipment was developed and applied to study the thermal characteristics of high power LEDs. The forward-voltage based method was conducted to measure the junction temperature of high power LEDs. Conduction type method is adopted to measure the temperature sensitivity parameter (TSP) with small magnitude of error compared with the traditional method...
The high-power Light Emitting Diode (LED) can be potentially used for general lighting to alleviate the global warming problem. However, the LED issues, associated with high cost, high junction temperature, low luminous efficiency, and low reliability, have to be resolved before becoming realized. Featuring low-junction-temperature and low-cost design, a novel high-power COP (Chip-on-Plate) LED package...
Nowadays the demand for thermal standards for power LEDs is increasing. On the one hand metrics for fair comparison of competing products are needed, on the other hand, designers of power LED based applications demand reliable and meaningful data for their daily work. Todaypsilas data sheet information does hardly meet any of these requirements. Part I compares the current situation in the LED world...
The increasing need for standardisation of thermal characterisation of LEDS and LED-based products. Manufacturers and end-users alike are crying for fair and useful thermal data, but for different reasons. It goes without saying that the LED-business is growing exponentially, in fact, much faster than analysts predicted five years ago. Unfortunately, the progress in thermal characterisation has not...
The present work aims at studying the cooling performance of a thermoelectric device that integrated with integrated heat spreader (IHS) on a flip-chip plastic ball grid array (FC-PBGA) package. The new thermoelectric device herein is fabricated on the metal substrates by flip-chip assembly process. Thermal performance of the new package was comprehensive studied. The thermal resistances of IHS with/without...
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