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排序方式: 共有253条查询结果,搜索用时 588 毫秒
71.
研究了以氮化铝为基板的倒扣封装的工艺。详细比较了氮化铝的各种金属化工艺。分别研究化学镀与激光诱导淀积实现金属化的方法。测量表明两种方法制备的金属层与氮化铝的粘附力均大于 10 MPa。同时对这两种方法的特点与适用范围进行概述 相似文献
72.
高密度封装技术的发展 总被引:14,自引:0,他引:14
摘要:重点介绍了BGA与CSP高密度封装技术的发展现状及趋势。BGA与CSP是现代组装技术的两个新概念,它们的出现促进了表面贴装技术(SMT)与表面贴装元器件(SMD)的发展和革新,并将成为高密度、高性能、多功能及高I/O数封装的最佳选择。 相似文献
73.
We explore the possibility of an N-qubit (N>3) Grover
search in cavity QED, based on a fast operation of an N-qubit
controlled phase-flip with atoms in resonance with the cavity mode.
We demonstrate both analytically and numerically that our scheme
can be achieved efficiently to find a marked state with high
fidelity and high success probability. As an example, a ten-qubit
Grover search is simulated specifically under the discussion of
experimental feasibility and challenge. We argue that our scheme is
applicable to the case involving an arbitrary number of qubits. As
cavity decay is involved in our quantum trajectory treatment, we
can analytically understand the implementation of a Grover search
subject to dissipation, which will be very helpful for relevant
experiments. 相似文献
74.
Resonant Homoclinic Flip Bifurcations 总被引:6,自引:0,他引:6
This paper studies three-parameter unfoldings of resonant orbit flip and inclination flip homoclinic orbits. First, all known results on codimension-two unfoldings of homoclinic flip bifurcations are presented. Then we show that the orbit flip and inclination flip both feature the creation and destruction of a cusp horseshoe. Furthermore, we show near which resonant flip bifurcations a homoclinic-doubling cascade occurs. This allows us to glue the respective codimension-two unfoldings of homoclinic flip bifurcations together on a sphere around the central singularity. The so obtained three-parameter unfoldings are still conjectural in part but constitute the simplest, consistent glueings. 相似文献
75.
低成本基板倒装焊底充胶分层裂缝扩展研究 总被引:2,自引:0,他引:2
采用MIL-STD-883C热循环疲劳加载标准,通过电学检测方法测定了B型和D型两种倒装焊封装焊点寿命。并使用无损声学C-SAM高频超声显微镜技术观测这两种倒装焊封装在焊点有无断裂两种情况时芯片/底充胶界面的分层和扩展,计算得到分层裂缝扩展速率。在有限元模拟中采用粘塑性和时间相关模量描述了SnPb焊点和底充胶的力学行为。使用裂缝尖端附近小矩形路径J积分方法作为断裂力学参量得到不同情况下的界面分层裂缝顶端附近的能量释放率。然后由实验裂缝扩展速率和有限元模拟给出的能量释放率得到可作为倒装焊封装可靠性设计依据的Par—is半经验方程。 相似文献
76.
Bifurcations and chaos of a discrete mathematical model for respiratory process in bacterial culture
The discrete mathematical model for the respiratory process in bacterial culture obtained by Euler method is investigated. The conditions of existence for flip bifurcation and Hopf bifurcation are derived by using center manifold theorem and bifurcation theory, condition of existence of chaos in the sense of Marotto's definition of chaos is proved. The bifurcation diagrams, Lyapunov exponents and phase portraits are given for different parameters of the model, and the fractal dimension of chaotic attractor was also calculated. The numerical simulation results confirm the theoretical analysis and also display the new and complex dynamical behaviors compared with the continuous model. In particular~ we found that the new chaotic attractor, and new types of two or four coexisting chaotic attractors, and two coexisting invariant torus. 相似文献
77.
Matthias Zeller Subhadeep Banerjee Christian Brückner 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(7):707-711
The structure of 8‐oxo‐5,10,15,20‐tetraphenyl‐7‐oxaporphyrin N24‐oxide, C43H28N4O3, (4B), shows that N‐oxidation of the pyrrole opposite the oxazolidone group cants the pyrrole out of the mean plane of the chromophore. This also affects the oxazolidone group, which is also slightly canted out. This conformation is qualitatively similar to that of the parent meso‐tetraphenylporphyrin N‐oxide, but dissimilar to that of the porpholactone N‐oxide isomer 8‐oxo‐5,10,15,20‐tetraphenyl‐7‐oxaporphyrin N22‐oxide, (4A), carrying the N‐oxide at the oxazolidone group. While the degree of canting of the N‐oxidized groups in both cases is comparable (and more pronounced than in the porphyrin N‐oxide case), in (4A) the pyrrolic groups adjacent to the N‐oxidized group are more affected than the opposing group. These differences in the conformational modes may contribute to rationalizing the distinctly different electronic properties of (4A) and (4B). 相似文献
78.
关于斜正定矩阵的一些性质 总被引:3,自引:1,他引:2
利用矩阵的次转置共轭和翻转矩阵等技巧,给出关于斜正定矩阵的一些性质,给出矩阵的斜对称部分与其逆之差是斜半正定的结论. 相似文献
79.
Peter A. Sandborn Rajarshi Ghosh Ken Drake Magdy Abadir Linda Bal Ashish Parikh 《Journal of Electronic Testing》1994,5(2-3):207-218
This article discusses the conceptual/specification phase of multichip system design. The automation of conceptual design practices will decrease design and manufacturing risks by allowing system designers to view the entire performance design space early in the design cycle prior to the initiation of traditional physical design activities.This article describes a software tool that performs interdisciplinary trade-off analysis and partitioning for multichip systems including multichip modules (MCMs) and traditional assembly approaches. The tool concurrently computes physical, electrical, thermal, reliability, testability, and cost performance metrics for multichip systems. This tool allows a large fraction of possible design, technology, material, test, and manufacturing approaches to be explored before decisions are made and resources committed.An example set of trade-off results are presented which examine the trade-off between peripheral I/O format die and area array I/O format die in an MCM, as a function of partitioning a fixed functionality into a variable number of die.Visiting researcher at MCC from Eastman Kodak Company. 相似文献
80.