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Modeling of time-pressure fluid dispensing processes   总被引:1,自引:0,他引:1  
The process of time-pressure fluid dispensing has been widely employed in the semiconductor industry, where the fluid is applied to boards or substrates. In such a process, the flow rate of fluid dispensed and the shape of fluid formed on the board are the two most critical performance indexes, yet extremely difficult to represent because of their complex behavior. This paper presents the development of a model for the time-pressure fluid dispensing process, by which the flow rate and shape can be established. Experiments have been performed to validate the model developed  相似文献   

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Comparative study of fluid dispensing modeling   总被引:1,自引:0,他引:1  
Computational fluid dynamics is used to calculate flows in the time-pressure dispenser. The analysis of different factors such as the yield stress, the power-law constants, the needle length, etc. will be useful in understanding the dispensing mechanism and thus allow for performance improvement. The numerical solution can provide more information about the wall shear stress and the pressure drop caused by a sudden contraction. The approximation error associated with the analytical method can be understood through comparison with the numerical results. Thus, an approximation compensation model may be derived for the analytical method to improve modeling accuracy.  相似文献   

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Dispensing has been widely used in industry to precisely control the delivery of fluid materials. Among several approaches, positive-displacement dispensing by employing the linear movement of a motor-driven piston is recognized as the most promising because the approach is assumed to be "true" volumetric dispensing. This is true for dispensing a large volume of fluid with continuous piston motion. As the volume of fluid decreases to the micro-liter range, however, this assumption is no longer valid because the fluid properties, in particular the compressibility and flow behavior, can have a significant influence on the volume of fluid dispensed. Taking into account the influence, This work presents the development of a model for the positive-displacement dispensing process. The model is then used to investigate the process performance, with the emphasis on identifying the influence of such factors as the fluid volume in a syringe, the needle temperature, and the fluid properties on the consistency in volume of fluid dispensed.  相似文献   

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The underfill dispensing volume has been modeled and verified through both experiments and application of statistical technique. The model established is capable of estimating the operating range of the dispensing volume of a defined flip chip assembly and is targeted to reduce wastage as well whilst fulfilling the reliability requirement. The model has taken into consideration the reliability factor, e.g., presence of fillet; manufacturing tolerance of bumps size and standoff variation. In this study, the actual volume for flip chip assemblies prepared in a controlled manner, so that fillets were seen on all sides, was compared with the recommended underfill volume. It was found that the model tended to yield a higher volume and it is concluded that this variation is related to the over estimation of the fillet element in the formulation. For reliability assessment, these flip chip assemblies were examined under C-mode SAM and no voids were found. These flip chip assemblies also passed electrical testing after 500 cycles of air to air thermal cycles and therefore are proven to meet the reliability requirement.  相似文献   

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使用了润湿力测试和黏度测试的方法来探究点涂焊膏的制备工艺并最终获得性能优异的产品。配合点胶机与空气压缩机的使用,探讨了点涂过程中点涂滞留时间、黏度和点涂压力对点涂量的影响。结果表明:对于黏度、针头内径、点涂滞留时间均固定的点涂焊膏,点涂量随压力的增大而增大,并呈现出拟合程度很好的线性关系。  相似文献   

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《IEE Review》2004,50(12):12-12
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《III》2006,19(2):20
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在非理想工况下,光伏阵列的多峰现象会使得输出功率大幅下降,严重影响整个光伏发电系统的工作效率.为保证每个组件在不同工况下都能运行在各自的最大功率点处,提出一种基于双开关管的Buck-Boost直流斩波电路的光伏组件优化器,能够根据设计的控制策略自动切换工作模式和寻找最大功率点.实验验证了该控制策略的有效 性和高效性.  相似文献   

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The design of a microcomputer is presented, which provides a standard and versatile module for computer interfacing.  相似文献   

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超辐射发光二极管(SLED)作为一种非相干性宽带光源,是光纤陀螺仪(FOG)和光纤传感器的理想光源,也是光时域反射仪(OTDR)和中短距离光通信的主要光源之一。SLED组件采用8脚蝶形式或14脚双列直插式管壳全金属化气密性封装,标准单模光纤(SMF)或保偏光纤(PMF)耦合输出。组件包括SLED管芯、半导体致冷器(TEC)、热敏电阻,可带背光探测器。使用时可通过外电路(自动温度控制电路ATC、自动功率控制电路APC)对组件实现功率控制和温度控制,以便使组件能长期稳定工作。与光纤耦合效率可达45%以上,光谱宽度大于40nm(工作电流100mA)。  相似文献   

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《III》1991,4(3):63
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曾云  晏敏  魏晓云 《半导体技术》2004,29(6):38-40,44
概述了微电子封装技术的发展历史和多芯片组件MCM)技术的发展过程,介绍了MCM技术的特点、基本类型及其特性、三维多芯片组件和MCM的应用,并分析预测了未来微电子封装的发展趋势.  相似文献   

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简要讨论了电子现金的特点,并在EIGamal签名、承诺方案和ZK的基础上构造了一种电子现金方案,最后对此方案的安全性作了说明。  相似文献   

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《Spectrum, IEEE》2007,44(9):14-15
Having discovered India's inexpensive engineering talent years ago, nearly every big tech company has a subsidiary there. Now the venture capital (VC) groups of these multinationals are discovering India's independent start-ups. Venture capital investment in India is on the way to a substantial increase this year, with US $341 million committed in the first half of 2007. That follows VC's nearly doubling in 2006 to $508 million spread over 90 deals. Nearly 15 percent of the 2006 money came from the venture capital divisions of companies like Cisco Systems, Google, IBM, Intel, and Yahoo, according to Arun Natarajan, CEO of Venture Intelligence, a Chennai-based firm that tracks VC investments. That's a much higher proportion than in the United States, where in 2006 big companies accounted for less than 8 percent of VC financing.  相似文献   

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简要讨论了电子现金的特点,并在ElGamal签名、承诺方案和ZK的基础上构造了一种电子现金方案.最后对此方案的安全性作了说明.  相似文献   

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