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Thermal runaway is among the major failure mechanisms of power semiconductor packages. Thermal dissipation of power electronics depends on the quality of the solder die-attach, any defects such as voids, and delamination-impede heat dissipation that results in hot spots that can cause thermal runaway and/or a premature device failure. Therefore, investigation of thermal impact due to die-attach defects...
A high reliability of light emitting diode (LED) light sources is essential for general and automotive lighting applications, where exchange of LED components is expensive. Thermal management of modern high power LEDs is crucial for their lifetime. An important aspect is the thermal path for heat conduction. Many different defects can have an influence on this path of an electronic system: on the...
QFN packages gained popularity among the industry due to its low cost, compact size, and excellent thermal electrical performance. Although PCBs are widely used for QFN packages in handheld devices, some customers require it for heavy industrial application demanding thicker PCB. When an electronic device is turned off and then turned on multiple times, it creates a loading condition called power...
An innovative sensitive test method is developed to detect solder joint cracking for high power LED packages. The method is based on transient thermal analysis and can replace the dominating Light-On test. Test groups of LED packages were soldered with two different lead free solders (SnAgCu 305 and Innolot FL-640) on Aluminum Insulated Metal Substrate and exposed to temperature cycles. Transient...
Five group thermal resistance test samples of the power devices were performed high temperature aging at 150°C for 0h, 24h, 48h, 72h, 96h respectively, then the maximum thermal test current without device self-heating temperature rise of 5mA was determined, and the transient thermal resistance test method was employed to obtain the heat transient response curves containing the thermal resistance and...
In this research thermal and fluid fields of a 32-inch commercial thin film transistor liquid crystal display (TFT-LCD) TV panel were investigated numerically and experimentally. The new trend in the production of TFT-LCD, TV panel is to have slimmer screen displays. The original design with 180 LEDs (light emitting diodes) placed at the top and bottom edges of the panels was modified. In the new...
In recent years, LCD (Liquid Crystal Display) TVs are taking the place of CRT (Cathode Ray Tube) TVs very fast by bringing new display technologies into use. LCD module technology is divided into two main groups; the first one is CCFL (Cold Cathode Fluorescent Lamp) display which was the first type used in LCD TV, the other one is the LED (Light Emitting Diode) module which is the newest display technology...
This research explored the thermal analysis and modeling of a 32” thin film transistor liquid crystal display (TFT-LCD) panel, in the purpose of making possible improvements in cooling efficiencies. The illumination of the panel was insured by 180 light emitting diodes (LEDs) located at the top and bottom edges of the panels. These LEDs dissipate high heat flux at low thermal resistance. Hence, in...
This paper presents a methodology for the creation of reduced thermal models of electronic systems based on the knowledge of the system dynamic temperature response. The registration of thermal responses using equidistant sampling on a logarithmic time scale allows the proper identification of all the time constants in the responses. Knowing the entire time constant spectrum, it is possible to generate...
Space grade subsystems require judicious combination of design, analysis and testing to realize a flight worthy hardware. These subsystems operate in an environment considerably different from that in which they are built and after launch they are inaccessible to routine maintenance and repair. The thermal vacuum test is one of the most critical environmental tests. This paper presents the design...
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...
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...
This paper discusses the problem of determining a thermal model of an electronic system based on the spectral analysis of its step temperature response. The proposed method yields equivalent RC Cauer ladder thermal models, which consist of only a few RC stages, but produce very accurate estimates of circuit temperature. Moreover, the values of model elements have physical significance. Such a thermal...
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...
Thermal resistance model is very simple and good tool for thermal analysis of package system. In this study, thermal resistance model was compared with simulation tool and real measurement values of flip-chip package which was made by using DTSA (Diode Temperature Sensor Array). Especially, a micro thermocouple sensor array - DTSA - has been developed to investigate the temperature distributions of...
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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