摘要：
LEDs (Light Emitting Diodes) Light source due to conform to the low carbon, green and environmental protection and social development requirements, has been widely used in the field of information field, lighting, display, is the incandescent lamp, fluorescent lamp, gas discharge lamp after a new type of Light source. Many research institutions have developed with high level of LED testing equipment, but overall, the high cost of the equipment. At present, our country's national standards in the field of LED and related products is still a blank, no unified standards and test methods to regulate the industry, making the industry products are good and bad are intermingled. In the design of test system, this paper first introduces the basic theory about LED photometric measurement and measurement standards and the status quo at home and abroad, and the main optical parameters of traditional measurement methods are summarized. Then, according to the principle of digital imaging, the overall scheme of the two kinds of measurement system is presented. Therefore, this article USES the by a CCD camera and a lambert scattering screen composition, light from the LED light to the front of the screen surface, and CCD camera filmed illuminated screen. Experiment, he measured data for the system parameters in a calibration scheme. Since then, we can use two other LED light intensity distribution measurement system plan, this completes the LED the design and development of the spatial light intensity distribution measuring device, the set of instrument system can complete the LED light intensity and photometric parameters of rapid measurement, suitable for LED production testing and research.
摘要：
Covalent compounds have strong covalent bond, thus showing high melting point, high hardness, high temperature resistance, corrosion resistance, wear resistance and other excellent performance, is widely applied to the field of refractory materials and wear-resistant materials. But at the same time this kind of material also has the problem of poor toughness and difficulty in sintering. In this article, by adding the nonstoichiometric ratio to the AlN titanium nitride, a new method were studied to improve the sintering property and reduce the sintering temperature through vacancy diffusion and to study the sintering of micro forming mechanism. The experimental results show that after sintering at the interface between TiN0.3 and AlN two-phase, the TiN0.3 / AlN layer have apparent diffusion zone, AlN in N, Al atom diffusion in TiN0.3 via the vacancy diffusion mechanism. As a result of the existence of a large amount of N of TiN0.3 space, when the diffusion of N atomic migration in TiN0.3 is absorbed by vacancy, and approaches stoichiometric ratio TiN layer AlN substrate; Al atoms crystallized out of the TiN layer in the hexagonal AlN structure in TiN0.3 matrix.
摘要：
This experiment mainly study the influence of the thermal fatigue of solder joint, solder was - Cu and Sn, Pb, Sn - Ag is 760 microns in diameter, welding plate of 560 microns. Internationally accepted tin-lead solder is most likely to replace the Sn Ag - Cu alloy series. In order to study the temperature and stress under the dual function of single substrate BGA solder joint in the process of thermal fatigue deformation process, organizational structure evolution, establishing the model of fatigue study solder joint fatigue mechanism; Find out fast cyclic heating and fast cooling the coupling mechanism of solder joint fatigue and solder joint interface evolution process. First of all, experimental apparatus mainly has a high frequency current box, catheter, relay and thermocouple. Under the condition of rapid heating and rapid cooling, the thermal fatigue behavior of single substrate.
摘要：
高熵合金不同于传统合金中仅以一种或两种元素为主,通常有5种或5种以上的主元素,并且每种元素的比例在5%35%之间。这种合金设计理念的提出,为材料的研究开辟了一个崭新的领域。其中,基于CASTEP模块的Co Cr Ni Cu Mn多主元高熵合金的结构构建及性能研究是一个方向。笔者通过构建以Cu原子为框架的Co Cr Ni Cu Mn高熵合金的晶胞结构,对实验结果中的晶格常数、能带结构、态密度图进行分析,得出在该种结构下材料具有强度硬度高、耐磨性和稳定性好等众多优异的性能。
摘要：
BGA micro-joint with double substrates used by SAC305 lead-free solder is fabricated by reflowing process based on substrate FR-4. The microstructures of the solder joints are studied through the method of rapid thermal cycling (RPC). The double-based plate Cu/SAC305/Cu solder joint was tested at extreme temperature 60-180 degrees C by rapid thermal cycling 48 hours and 72 hours respectively, it was found the IMC grow by the zigzag shape, and fatigue cracks greatly appear at the interface of IMC/Cu, they are initiating and propagating along the boundary, and thread through the cross section of solder joint in the end, which lead to the failure of solder joint.
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：
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：
Preparation of BGA micro-joint with single-double substrates used by SAC30S lead-free solder is fabricated by reflowing process based on substrate FR-4. The microstructure change and evolution law of the solder joints are studied through the method of rapid thermal fatigue. The single-base plate SAC30S/Cu solder joint was tested at extreme temperature 60-200 degrees C by rapid thermal cycle 24 hours and 36 hours respectively, it was found the IMC grow by the zigzag shape, and fatigue cracks appear at the interface of IMC/Cu, they are initiating and propagating along the boundary, and thread through the cross section of solder joint in the end, which lead to the failure of solder joint.
摘要：
Material Studio软件中的CASTEP模块在构建晶体结构过程中融入了基于密度泛函理论的第一性原理赝势方法。本文利用CASTEP软件包模拟研究了不同原子比的碳化钛的结构,构建了非化学计量比的Ti C0.75的晶体结构模型。如何利用CASTEP软件构建非化学计量比的晶体结构在其他文献中是比较少见的。通过对Ti C0.75晶胞结构参数及能带-态密度图的分析,得到碳含量变化对碳化钛的物理和化学性能的影响结果规律,其结果与相关文献报道一致。
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：
This paper discusses Fe50Cu50 composite powder mechanical alloying of morphology and solution condition, through to the mechanical alloying Fe50Cu50 after composite powder on scanning electron microscopy and distribution analysis has determined its morphology and Fe -Cu the solution conditions. The experimental results show that the ball mill 50 h, Fe50Cu50 composite powder particle size basically stable, size in a few microns or so, and Fe and Cu has fully fuses in together to form the uniform solid solution.
