摘要：
The objective of this paper is to investigate the effect of rapid thermal cycling on microstructure and optical property (luminous flux and luminous efficiency) of high power light emitting diode (LED) by thermal fatigue testing from -40 to 125. Under an application of thermal fatigue device as a heating source, the specimens that were being non-operating and thermal fatigue testing in the experiment were rapidly heated and cooled based on a control system that employs a fuzzy logic algorithm, respectively. The optical performances, including luminous flux, luminous efficiency, radiant power and color temperature (CCT) of LED specimens were tested and analyzed. It was found that the rapid thermal cycling have similar evident influence on them. The results showed that the color purity of LED was also descended, the correlated color temperature (CCT) was also risen, but their changing rate and extents are different. The high and low temperature distribution in LED chip was simulated by finite element modeling which is helpful for the failure analysis and design of the reliability of the LED packaging. The microstructures of LED chips are analyzed after different rapid thermal cycling time. The results are showed that rapid thermal cycling can affect greatly the LED properties and interface microstructures. All the results indicate that this approach to rapid thermal cycling by using rapid heating source is feasible to investigate the optical performance of high power LED, so it can also effectively verify the reliability of LED devices.
摘要：
Lead-free solder has been widely used in electronic packaging products in printed circuit boards (PCB). Because soldering in the microelectronics industry not only provides the electronic connection, but also ensures the mechanical reliability of solder joints under the complex service conditions. This study provides some prospective into the microstructural changes of the solder joints interconnection by rapid thermal cycles. The goal of this paper is to investigate the thermal fatigue behavior of a single Sn-3.0Ag-0.5Cu (SAC) lead-free solder joint treated by rapidly alternating heating and cooling cycles. The microstructure and morphology of the interface between the solder ball and Cu substrate was observed using scanning electron microscopy (SEM). The intermetallic compounds (IMC) and the solder bump surface were analyzed by energy dispersive X-ray (EDX) and respectively. The experimental results showed that rapid thermal cycling had an evident influence on the interfacial microstructure of a single solder joint. The experiment revealed that microcracks initiate at the bottom of the SAC solder joint. In addition, rimous cracks initiated and propagated on the superficial oxide of the solder bump after rapid thermal cycling. The temperature distribution can be explained by finite element modeling (FEM) according to heat deformation theory in materials physics and based on metal thermal fatigue mechanism.
摘要：
The objective of this paper is to investigate the effect of rapid thermal cycling on microstructure and optical property (luminous flux and luminous efficiency) of high power light emitting diode (LED) by induction heating. Under an application of induction heating as rapid heating source, the specimens that were being non-operating and operating life tests in the experiment were rapidly heated and cooled based on a control system that employs a fuzzy logic algorithm, respectively. The optical performances, including luminous flux, luminous efficiency and radiant power of two kinds of LED specimens were compared and analyzed. It was found that the rapid thermal cycling have similar evident influence on them. The results showed that the color purity of LED was also descended, the correlated color temperature (CCT) was also risen, but their changing rate and extents are different. The high and low temperature distribution in LED chip was simulated by finite element modeling (FEM) which is helpful for the failure analysis and design of the reliability of the LED packaging. The microstucrue of LED chips are analyzed after different rapid thermal cycling time. The results are showed that rapid thermal cycling can affect greatly the LED properties and interface microstructures. All the results indicate that this approach to rapid thermal cycling by using rapid heating source is feasible to investigate the optical performance of high power LED, so it can also effectively verify the reliability of LED devices.
摘要：
The quality of the plastic part depends on the material characteristics, the mold design, and the process parameters, one of which is more important. It involves many sub-design tasks that determine the cost and performance in the early conceptual mold layout design phase. Base-Cover was injection molded with acrylonitrile–butadiene–styrene (ABS)/polycarbonate (PC) [ABS/PC] alloy resin and its process parameters was analyzed by commercial Moldflow software. The optimum gate location and melt filling time were determined, and the optimum injection temperature was obtained by analyzing the shrinkage of the product after molding. An effective regression model was developed to determine the mathematical relationship between the process parameters (mold temperature, melt temperature, injection pressure, injection time, and cooling time) and the volumetric shrinkage by utilizing the analysis data.
期刊：
WIT Transactions on the Built Environment,2013年140:477-481 ISSN：1743-3509
作者机构：
[Yanfang Yin; Qinggang Qiu] School of Mechanical Engineering, Wuhan Polytechnic University, China
关键词：
CAE simulations;Molding design;Process parameters;Thin-shell plastic parts
摘要：
The product design and manufacturing parameters of plastic parts can be estimated, improved and optimized by using a 3D finite element simulation of the injection molding process of Thin-shell plastic parts and the module of the Moldflow 6.2. It is critical that one understands how the plastic will behave in the environment and the operational load to which it will be subjected when plastic parts are designed. Using knowledge of plastic processing and Moldflow’s technology can ensure that molding design and the mold will work right the first time. The defects possibly occur in the processes of product design, mold design and product molding can be eliminated extremely by CAE simulation calculation for plastic parts. This can reduce the product manufacture cost and shorten the product developing cycle. Keywords: CAE simulations, Thin-shell plastic parts, molding design, process parameters.
作者机构：
[周康; Xie Z.; 魏传佳] Department of Mathematics and Physics, Wuhan Polytechnic University, Wuhan 430023, China;[殷燕芳] School of Mechanical Engineering, Wuhan Polytechnic University, Wuhan 430023, China
通讯机构：
Department of Mathematics and Physics, Wuhan Polytechnic University, China
