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In this paper, Ti-doped GaZnO (GTZO) quaternary alloys were used as the transparent conductive oxides (TCOs) for Cu(In, Ga)SeSe2 (CIGS) solar cell application. These thin films are highly favorable for solar power systems. Photoluminescence measurement and X-ray diffraction were employed to investigate the GTZO thin films. Advantageous crystal quality was produced by radio-frequency magnetron sputtering...
The paper presents an analysis of self-heating effect on micro-machined temperature difference air flow sensor, and demonstrates through modeling and simulation that self-heating effect can influence the output of the air flow sensor. The mathematical model of the sensor based on an existing microsensor chip is set up, and some details of the chip structure are considered in the model. The sensor's...
In this paper, simulation and optimization of a micro flow sensor is presented. Modeling of the micro flow sensor using ANSYS Fluent for temperature distribution is studied. The detailed structure of the micro flow sensor chip is considered in the simulation model. What's more, the temperature dependencies of physical properties of air are defined to improve the model precision. As a key parameter,...
The paper presents an analysis of self-heating effect on micro-machined temperature difference air flow sensor, and demonstrates through modeling and simulation that self-heating effect can influence the output of the air flow sensor. The mathematical model of the sensor based on an existing microsensor chip is set up, and some details of the chip structure are considered in the model. The sensor's...
In this paper we present design of a novel buffered distributed spray (BDS) MOCVD reactor, which is characterized by vertical distributed spray and horizontal radical flows. Theoretical studies have been performed about the reaction mechanisms of GaN films based on computational fluid dynamics (CFD) simulation to investigate the performance of the BDS reactor. Furthermore, we present the secondary...
In this study, gel glass containing yellow, green and orange phosphors is fabricated via sol-gel process. Effects of different temperatures on condensation time of the sol and density of the gel glass are investigated. The gel glass is detected to confirm micro structure by SEM. The phosphors are well dispersed in the glass without phosphor degradation. The white light is successfully observed by...
Luminescent ceramics may exhibit less scattering and increase the conversion efficiency over prior phosphor layers. Recently, the great majority of the commercial white LED (light emitting diodes) modules realized white light by GaN blue chip adding yellow phosphor. Although it has relatively high quantum efficiency, but its performance degenerates obviously at high temperature, and also causes deviation...
In a typical LED package module, a grease layer forms the interface between the substrate and copper heat spreader. We propose to carve grooves on the aluminum substrate to form an array of protruding posts. Three types of grooves are designed to measure interface thermal resistance. A preliminary feasibility study shows obvious improvement in the thermal resistance of the interfaces for the formation...
In this paper, in order to improve the reliability of LED module, the accelerated life test (ALT) for LED was conducted. Experimental measurements were adopted to obtain the temperature variations of LED module. In the experiment, the LED samples are placed in the chamber to conduct the thermal shock between −40°C and 125°C. The powered and unpowered experiments of LED were both tested. The luminous...
High junction temperature accelerates the degradation of the chips and the package materials of high power light emitting diodes (LEDs). In this paper, two experiments were conducted to investigate the fluctuation of junction temperature in the aging process. At the ambient temperature of 65°C, the samples from four different types of LED packages were used to investigate the variation of junction...
Thermal contact resistance is an important parameter for the thermal management of electronics packaging. A type of test instrument for measuring thermal contact resistance was presented in this paper. Thermal contact resistance across a brass-brass (Cu-Cu) interface was investigated by the present instrument. The results show that the contact thermal resistance is at the magnitude of 10-4 for the...
According to the impedance characteristic curves of linear regulator chip which are measured in different temperatures, making use of chip model and the determination of LSI/IC equivalent model parameter, the resistance, capacitance and inductance parameters of chips in different temperatures are obtained. And the fitted impedance characteristic curves of chips by vector fitting are obtained. By the...
125µm- breath sensor with high sensitivity and rapid response was prepared by using n-type Si: Au material. Its sensitivity coefficient and time constant were 4 V.sec/L and 38 msec, respectively. Its working principle was based on anomalous resistance effect, which not only increased the sensitivity, but also reduced its time constant greatly. Its signal processing system can select the breath signals...
In this paper, a platinum thin film thermal flow sensor was presented. Design, fabrication process and thermal analysis were presented and discussed. Compared with traditional structure of four supporting beams, the present structure can provide high sensitivity and good strength because of the unique thermal and mechanical design. The sizes of the flow sensor chip are 571 μ m × 280 μ m × 0.25 μ m...
An experimental setup to measure the thermal contact conductance across solid/solid interface is described in this paper. This setup was built at room temperature, it does not need vacuum environment and can be used in normal pressure environment. An experimental investigation of thermal contact resistance of two brass columns was conducted under different conditions, which were classified as four...
The degradation of high power GaN-based blue light-emitting diodes (LEDs) was investigated by considering the electrical, optical and electroluminescence spectrum aging characteristics. The LED samples are stressed at the condition of 85°C and 85% RH using an injection current of 1000 mA. Optical output power decreases to 80% of initial value after 1000 hours of temperature/humidity accelerated tests...
Simple experiments were conducted to obtain surface and lamp hold temperatures of a main-stream 4W LED bulb, which is on sale in the market. Two kinds of thermal calculations were also done based on the data from measurements. The total heat dissipation rates in those two thermal calculations are close to each other, which demonstrate that the thermal calculation is feasible for thermal analysis of...
This paper provided a new type vapor chamber coupled fin heat sink, which is applied to high power LED light source. It shows good performance for the heat dissipation of high power LED devices. To compare its performance, the same LED light source with only fin heat sink was also fabricated and tested. Experimental tests, numerical simulation and thermal resistance analysis were conducted on the...
Function-Structure Plant models (FSPM) seem attractive to better understand the complex interactions between plant growth, canopy morphogenesis, and epidemics. Epidemics are driven by climate factors and among them, temperature is known to play a major role. Thus, weather station measurement is commonly used to drive epidemics models. However, the relationship between climate and within-canopy microclimate...
Localized induction heating for wafer level packaging is discussed. This paper is to investigate the relationships between the geometry of solder loop and temperature distribution in induction heating. Using finite element method (FEM) and IR thermal imager, temperature distribution and variation are explored, which shows that the temperature on the solder loops is a function of the area and edge...
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