共查询到20条相似文献,搜索用时 62 毫秒
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文章简述了封装工艺中SPC的运用。介绍了SPC控制图的分类:用于连续型数据的控制图和用于计数型数据的控制图。介绍了封装工艺中最典型的均值一极差控制图的应用。针对均值控制图,文章论述和对比了三种不同的SPC控制限的计算方法:使用控制限系数A2,使用控制限系数d2和子组均值移动极差法,并用实例验证了最佳计算方法。结论中讨论了最佳计算方法在其他控制图中的适用性。 相似文献
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刘建 《电子产品可靠性与环境试验》2012,(4):47-50
在计算Cpk的时候通常采用工艺规范限,但当实际数据统计出的控制限要远小于工艺规范限时,就会出现Cpk值的虚高;尤其是采用单边控制限时,这种现象尤为明显。为了从工艺角度更真实地表征工艺质量的一致性,需要对Cpk的计算方法做些调整,引入内控限替代工艺规范限。分别采用光刻和键合两道工序作为双边控制和单边控制的内控限计算方法事例,论述如何使Cpk值达到合理水平。 相似文献
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基于系统建模的四像限光电探测器对准与微位移测量系统 总被引:1,自引:0,他引:1
通过对基于四像限光电探测器的对准系统的光路分析,将系统的输入输出关系的确定转化为平面光照面积的计算,并给出了探测器各像限光照面积的求取方法,从而构建了该系统的数学模型.对该系统进行了仿真,并给出了系统的实测结果.仿真结果表明,通过设置不同的米字型标记参数,系统的输入输出关系具有不同的线性度.证明的确存在一个最佳结构参数组合,存在优化的可能.实测结果表明,该系统的最大对准偏差小于2 ,实测偏差小于2.佐证了模型的正确性,表明四像限光电探测器的对准应用可扩展到微量位移的测量.模型省去了繁杂的标定工作,消除了标定引入的非线性误差,提高了探测器的应用效率和准确度,因此具有较高的实际意义. 相似文献
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本文给出一种在CAS中实现区域限播的方案。该方案由广播前端将区域限播授权信息封装在ECM中,并广播发送给用户终端机顶盒。终端机顶盒接收到ECM之后,首先判断区域授权信息,再根据结果决定是否对加/解扰控制字CW进行解密,进而对节目视、音频流进行解扰,达到区域限播的目的。 相似文献
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介绍了双门限检测的基本原理,并根据该原理得出用单片机实现双门限检测的硬件电路及程序框图. 相似文献
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杨超锋 《信息技术与标准化》2014,(12)
限用物质管理和质量管理有相通之处,也有其独特的地方,这些地方通常是限用物质控制的重点。限用物质控制主要包括建立限用物质清单、设计开发、制造物流和品质管理四个部分,其控制核心是在各阶段不引入、不产生、不错用和不污染。同时,在控制中要重点关注容易遗漏的抽样器具及样品管理、过程产品和不合格品管理。限用物质控制特点是在过程控制的基础上,通过风险控制,找到可能的风险点,提前预防,而不仅仅是过程控制,更不能将其寄托于事后的检测、把关和纠正。 相似文献
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针对单门限变换域通信系统往往无法兼顾抗干扰和隐蔽通信的问题,提出了一种基于双门限变换域通信系统基函数幅度谱的设计方法。该方法首先在干扰存在情况下进行单门限系统最优误码率门限与最差误码率门限的判断,然后通过参数灵活调整两个门限的值,将大于高门限和低于低门限的值分别设为0和1,位于双门限之间的频谱进行倒置,得到的基函数通过对数据进行调制实现通信。仿真结果表明:相比于单门限变换域通信系统,通过参数调节后的双门限变换域通信系统可以同时具有良好的抗干扰及隐蔽通信性能。 相似文献
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Limits of lithography 总被引:1,自引:0,他引:1
Harriott L.R. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》2001,89(3):366-374
Lithography technology has been one of the key enablers and drivers for the semiconductor industry for the past several decades. Improvements in lithography are responsible for roughly half of the improvement in cost per function in integrated circuit (IC) technology. The underlying reason for the driving force in semiconductor technology has been the ability to keep the cost for printing a silicon wafer roughly constant while dramatically increasing the number of transistors that can be printed per chip. ICs have always been printed optically with improvements in lens and imaging material technology along with decreases in wavelength used fueling the steady improvement of lithography technology. The end of optical lithography technology has been predicted by many and for many years. Many technologies have been proposed and developed to improve on the performance of optical lithography, but so far none has succeeded. This has been true largely because it has always been more economical to push incremental improvements in the existing optical technology rather than displace it with a new one. At some point in time, the costs for pushing optical lithography technology beyond previously conceived limits may exceed the cost of introducing new technologies. In this paper the author examines the limits of lithography and possible future technologies from both a technical and economic point of view 相似文献
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No exact method is known for determining tolerance limits or s-confidence limits for reliability for the gamma distribution when both parameters are unknown. Perhaps the simplest approximate method is to determine a tolerance limit assuming the shape parameter known and then replace the shape parameter with its ML estimate to obtain approximate limits. Simulated values of the true probability levels, achieved by this method, indicate that this method is not suitable, contrary to what has been anticipated. A second approach is to consider the corresponding tolerance limits assuming the distribution mean known and the shape parameter unknown, and then replace the distribution mean by the sample mean. This approach gives useful results for many practical cases. Simulated values of the true probability levels achieved are presented for some typical cases and limiting values are provided. This method appears satisfactory for all values of the shape parameter, for the common s-confidence levels, and moderate sample sizes. 相似文献
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Since fundamental limits to plasma science are the well-known ones of relativity and quantum mechanics, various practical limits sure discussed for plasma science in several domains of current interest: applications (mainly controlled thermonuclear fusion, both magnetic confinement and ablative compression) investigation of natural plasma (in space near earth and solar system and in astrophysics). Some historical flavor is imparted by also considering the effect of limits on three domains of interest since the 1945: plasma frequency devices for microwave applications at millimeter wavelengths, solid-state plasmas, and reentry vehicle plasmas. In general, while one can identify the nature of the limits, refining their "values" or making firm predictions in view of possible "breakthroughs" is seen to be unlikely to be worth doing. 相似文献
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Allee D.R. Broers A.N. Pease R.F.W. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1991,79(8):1093-1105
The authors review the limits of nanometer-scale gate electrode (nano-gate) fabrication. The technology to fabricate nano-gates has become increasingly important in recent years as the scaling limits of conventional electronic devices and the quantum effects of novel devices are investigated. Consistent with the technology used to fabricate virtually all of the smallest devices to date, the emphasis is on the resolution limits of electron beam lithography and associated ultrahigh resolution resists. Recent results of directly patterning SiO2 with nanometer-scale resolution by e-beam exposure through a sacrificial layer are also presented. Because the high resistance normally associated with nanometer-scale electrodes seriously limits the performance of high-frequency devices, various techniques to reduce the gate resistance are compared 相似文献
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并矢Green函数的构造 总被引:1,自引:1,他引:0
提出并矢Green函数应与δ函数一道作为奇性广义函数(即分布),它们在r’≈r处没有常义定义。应当看作某些正则广义函数在泛函等值意义上的极限。正确理解并矢Green函数的意义,根本不出现发散积分,应当可以按常规数学原则来处理。具体讨论了自由空间和均匀波导内的并矢Green函数,得到了判断“正则化”是否合理的准则。 相似文献
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《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1967,55(10):1677-1686
The problem of estimating the errors arising in a variety of numerical operations involving bandlimited functions is considered. The errors are viewed as responses of suitably created systems, and the analysis is based on the evaluation of the maximum response of these systems in terms of the energy or power of their input. The investigation includes deterministic and random signals, and it is extended to two-dimensional functions and Hankel transforms. Finally, the results are related to the uncertainty principle in one and two variables. 相似文献
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Limits of integrated-circuit manufacturing 总被引:1,自引:0,他引:1
Doering R. Nishi Y. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》2001,89(3):375-393
A methodology is suggested for the study of integrated-circuit manufacturing limits. It is based on a hierarchical view of manufacturing detractors and associates limits with levels in this hierarchy. The methodology is illustrated with examples of steady-state, theoretical, and process limits at today's state of the art as well as example projections to future manufacturing at what may be near the limits of complementary metal-oxide-semiconductor (CMOS) scaling. There are also some speculations on possibilities beyond these limits 相似文献