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Visible Light Communication is an emerging technology in Optical Wireless Communication where the Light Emitting Diodes (LEDs) are utilized for transmission of data. The luminance of the LEDs increases with the forward current; however, for high current levels the heat generated by non-radiative recombination of carriers increases the LED junction temperature, decreasing the efficiency and the lifetime...
In-wheel motor is one of the expected electric vehicle technologies which has superiority in the vehicle control aspects. However, the integrated in-wheel motor in which the inverter is integrated with the motor makes thermal problems because of the reduction of cooling area. This paper analyses a cooling system of the inverter integrated in-wheel motor and considers the operating conditions of the...
The presented thermal impedance spectroscopy of power modules simplifies significantly the failure analysis of power modules. It enables online observation of degradation within the cooling path with detailed information about failure mechanisms. The degradation of certain layer within the power module is detected by observation of Zth parameters. Several tests results are compared with analysis of...
Flip chip technology is one of the advanced chip packaging techniques in IC packaging industry. This technology may provide a solution to enhancing heat-dissipation and optical performance of the LED when applying to the LED packaging. The goal of this study is to experimentally and numerically study the thermal performance of flip-chip (FC) LED (with the size of 1 × 1 mm) with and without underfills,...
Due to stringent environmental regulations, a solar power plant that produces energy without pollution has gained more attention in recent years. The high-concentration photovoltaic (HCPV) module is one of the popular solar energy systems due to its small deployed area and high conversion efficiency. However, it may also be subjected to higher temperature in the operating environment. The degradation...
Nowadays LEDs (Light Emitting Diodes) are widely used in many fields. As the fourth generation of lighting sources, LEDs have the advantages of long lifetime, power saving and environment-friendly. In this paper, the thermal variation characteristic of some parameters for two high-power LEDs packaging modules, such as forward voltage, luminous flux, CCT and luminous efficiency, were analyzed experimentally...
Based on the standard of International Electrotechnical Commission (IEC) on the thermal cycling test for a high concentration photovoltaic (HCPV) module, frequent current input must be applied when oven temperature exceeds 25°C. As such, the junction temperature of a solar cell chip would oscillate due to the joule heating effect. However, the fluctuation of the junction temperature might be one of...
We present a method of dynamic thermal characterization of an entire test assembly, consisting of high-power Light Emitting Diodes (LED) and a printed circuit board (PCB) by measuring the thermal response on a power-on-step function and describing the thermal impedance with a Foster RC network. For this purpose, we record temporal temperature functions on test assemblies during pulse load experiments...
The measurements of isothermal and non-isothermal DC characteristics of SiC Schottky barrier diodes are presented in this paper. Various electro-thermal models for I-V characteristics calculation are proposed. The calculations of non-isothermal characteristics of SiC SBD's in the wide range of forward voltage are shown. The self-heating phenomenon, as an electro thermal positive feedback is discussed...
Lighting purpose organic light-emitting devices have to be answer to high electrical and thermal requirements. Design of these devices needs special engineering. The electrical current and dissipated power distribution in an OLED needs electro-thermal field simulation. The algorithm in our simulation tool, SUNRED, had to be extended to be able to handle highly nonlinear electrical OLED characteristics,...
This paper aims at providing a rigorous description of the thermal impedance of AC LEDs, especially of retrofit LED lamps which are directly driven from the mains supply. The paper gives an overview of the different representations of the thermal impedance then provides estimates of the AC power of LEDs for two extreme cases (voltage and current driven situations). The high harmonic content of the...
We studied the thermal properties LED light unit composed of nine LED chips in a MLCMP (multi-layer ceramic-metal package) and compared various thermal dynamic models. We concluded that the direct measurement of forward voltage Vf is the most practical approach for in-situ testing. By calibrating the Vf to junction temperature Tj at various forward current in a temperature controlled oven, the linear...
This paper presents thermal characterization of the dielectrically isolated bipolar junction transistor (DIBJT) with the vertical bipolar inter-company (VBIC) model. The VBIC model incorporates the thermal nodes of a transistor. Semiconductor devices are strongly influenced by the thermal effects. When the device is heated, it raises its local temperature which changes the device's intrinsic parameters...
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...
A study was initiated in order to thermally quantify the characteristics of package-on-package (POP), which has been deployed in multiple mobile devices in order to reduce board area and subsequently mobile device size. In most POP scenarios, the memory package is stacked on top of a baseband or application processor and reflowed together. Thermal simulations were conducted for a POP package configuration...
The development of power supply technology has always been associated with the need for further miniaturization. This means that power semiconductors must be mounted at short distances on the same heat sink. Adjacent power semiconductors have an increasing influence on the chip temperature. The maximum junction temperatures, which are specified by the manufacturer under all operating conditions, may...
LEDs are key elements in modern, energy efficient lighting solutions as well as impose some issues from thermal point of view, since light output and reliability both depend on LEDspsila junction temperature. A comprehensive and accurate measurement method is required and demanded by several leader LED manufacturers. Failing a proper combined thermal and radiometric/photometric characterization of...
Consideration of health management and reliability form an integral part of the design and development cycle of electronic products. In this paper real-time compact thermal models are employed as an efficient tool to monitor thermal path degradation at particular locations within the module such as interfaces between the base-plate and heatsink. The compact real-tine thermal model is used to predict...
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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