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“我有一个梦想:某一天三大运营商员工不摆摊了,不打架了,员工年收入差距缩小了,前端营业员待遇提高了,后端装维与资源矛盾化解了,服务质量提高了,恶性竞争消除了,重复建设停止了,不再破坏对手广告了,不互挖墙角搞策反了,不再零元购机了,不打价格战了,都能活的有尊严了”. 相似文献
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本文提出了一种无需检测电感电流及其过零点的简单数字控制方案,实现了临界连续模式功率因数校正器的控制。取得了功率开关管的ZVZCS,消除了整流二极管和快恢复二极管的反向恢复带来的损耗,提高了变换器的效率和可靠性;另外,数字控制器克服了模拟IC控制器的开关频率限制问题,消除了输入电流的低频畸变,提高了功率因数;同时,也降低了输入电感的值,降低了成本的同时提高了功率密度。为实现中小功率数字控制功率因数校正器的产品化提供了一个良好的解决方案。 相似文献
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在当今的社会中,人们已经离不开电子通信了,其作为了一个新兴产业,并得到了良好的应用,对各行各业起到了促进作用,同时,传统的产业收到了冲击。我国的电子通信发展较快,达到了先进的水平,不过,由于发展时间较短,存在很多不足之处,拉低了整体水平。特别是干扰问题,严重影响了电子通信的发展。本文对电子通信进行了概述,探讨了干扰要素,并且,提出了相关的应对策略。 相似文献
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徐翠翠 《电子技术与软件工程》2021,(3):232-234
本文研究了供水系统运行状态实时模拟模型,首先对数据进行了预处理,然后运用多元线性回归,给出了准则判断了数据优势;建立了供水系统与用水量之间的数学模型,并给出了误差分析,探讨了供水量和用水量对模型的影响。 相似文献
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建立了原子层沉积 (Atomic Layer Deposition,ALD)反应腔室的三维模型,利用ANSYS Fluent软件模拟分析了ALD过程中压强、前驱体脉冲时间、温度等工艺参数变化对前驱体分布的影响。模拟结果表明:反应压强越低,Mg(Cp)2前驱体分子的扩散系数越高,能更快且更均匀地分布在整个反应腔室之中;前驱体脉冲时间越长,在反应腔室内的分布越均匀;当脉冲时间为250ms时,Mg(Cp)2在反应腔室内分布基本均匀,反应腔室内各部位的前驱体质量分数基本一致;当脉冲时间为200ms时,H2O基本均匀分布在反应腔室内。在MgO薄膜的ALD温度窗口内,反应腔室内温度越高,Mg(Cp)2前驱体分子的扩散效应越强。 相似文献
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文章主要介绍了pH对通过化学镀镍-磷法制作埋嵌电阻时镍-磷合金层方块电阻的影响。在温度相同的条件下,当镀液的pH不同时,探究了两种基材表面上镍-磷合金层方块电阻与反应时间的关系,并分析了适合用于制作埋嵌电阻的镍-磷合金层方块电阻值,以及最佳的化学镀镍-磷反应pH值。从实验结果可知,当反应时间相同时,随着pH的减小两种基材表面上镍-磷合金层的方块电阻将会逐渐大;适合用于埋嵌电阻制作的化学镀镍-磷反应pH为3.4~3.7,反应时间为3min~8min,方块电阻为15Ω/□~200Ω/□。 相似文献
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Hong Chang Hongtao Chen Mingyu Li Ling Wang Yonggao Fu 《Journal of Electronic Materials》2009,38(10):2170-2178
The effect of the anode and cathode on the electrochemical corrosion behavior of lead-free Sn-Ag-Cu and Sn-Ag-Cu-Bi solder
joints in deionized water was investigated. Corrosion studies indicate that SnO crystals were generated on the surfaces of
all lead-free solder joints. The constituents of the lead-free solder alloys, such as Ag, Cu, and Bi, did not affect the corrosion
reaction significantly. In contrast to lead-free solders, PbO
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was formed on the surface of the traditional 63Sn-37Pb solder joint in deionized water. A cathode, such as Au or Cu, was
necessary for the electrochemical corrosion reaction of solders to occur. The corrosion reaction rate decreased with reduction
of the cathode area. The formation mechanism of SnO crystals was essentially a galvanic cell reaction. The anodic reaction
of Sn in the lead-free solder joints occurred through solvation by water molecules to form hydrated cations. In the cathodic
reaction, oxygen dissolved in the deionized water captures electrons and is deoxidized to hydroxyl at the Au or Cu cathode.
By diffusion, the anodic reaction product Sn2+ and the cathodic reaction product OH− meet to form Sn(OH)2, some of which can dehydrate to form more stable SnO·xH2O crystals on the surface of the solder joints. In addition, thermodynamic analysis confirms that the Sn corrosion reaction
could occur spontaneously. 相似文献
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The volume effect in the reaction between Zn-doped solders and Cu is reported and explained in this article. Zn-doped solders
with two different volumes, bulk solder baths (6 g) and small solder balls (10 mg), were reacted with Cu substrates. It was
found that the reaction at the interface depended not only on the Zn concentration but also on the volume of the solder. For
the bulk solder reaction the Zn concentration stayed nearly constant, whereas in the small solder joint case the Zn concentration
changed substantially with the reaction time. This was because the Zn concentration during reaction was different for different
solder volumes when the volume effect became important. For bulk solder baths, when the Zn content was 0.5 wt.%, the reaction
product was a Cu6Sn5-based compound. As the Zn content increased to 2 wt.%, the reaction product switched to a Cu5Zn8-based compound. When the Zn content was 1.0 wt.%, Cu6Sn5 and CuZn formed simultaneously. When the solder volume became smaller, the Zn concentration was no longer constant, and the
phase equilibrium at the interface changed with time. It was shown that the shifting of the equilibrium at the interface caused
the massive spalling of CuZn. 相似文献
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Curing kinetics of an epoxy-based underfill material with applications in flip chip ball grid array (FC-BGA) packages has been studied using differential scanning calorimetry (DSC). Non-isothermal DSC curves were obtained with heating rates ranging from 0.5 to 10 °C/min. Glass transition temperature as a function of fractional conversion was determined using temperature modulated DSC. Based on these experimental data, non-linear regression technique was used to evaluate the curing kinetics by considering both chemical- and diffusion-controlled reaction processes. As a result, it was determined that the curing reaction can be described by an nth order autocatalytic reaction partially controlled by diffusion, although the diffusion effect is relatively weak. The obtained optimized kinetic parameters allow us to predict the reaction behavior under various application conditions. 相似文献
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讨论了几种数字滤波器算法.分析有限冲激响应滤波器和无限冲激响应滤波器各自的优点和缺点。提出一种利用可编程逻辑器件设计有限冲激响应滤波器的设计方法,并计算一个具体的有限冲激响应滤波器的参数。 相似文献
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There is a lot ofhydroxyl on the surface ofnano SiO2 sol used as an abrasive in the chemical mechanical planarization (CMP) process, and the chemical reaction activity of the hydroxyl is very strong due to the nano effect. In addition to providing a mechanical polishing effect, SiO2 sol is also directly involved in the chemical reaction. The stability of SiO2 sol was characterized through particle size distribution, zeta potential, viscosity, surface charge and other parameters in order to ensure that the chemical reaction rate in the CMP process, and the surface state of the copper film after CMP was not affected by the SiO2 sol. Polarization curves and corrosion potential of different concentrations of SiO2 sol showed that trace SiO2 sol can effectively weaken the passivation film thickness. In other words, SiO2 sol accelerated the decomposition rate of passive film. It was confirmed that the SiO2 sol as reactant had been involved in the CMP process of copper film as reactant by the effect of trace SiO2 sol on the removal rate of copper film in the CMP process under different conditions. In the CMP process, a small amount of SiO2 sol can drastically alter the chemical reaction rate of the copper film, therefore, the possibility that Cu/SiO2 as a catalytic system catalytically accelerated the chemical reaction in the CMP process was proposed. According to the van't Hoff isotherm formula and the characteristics of a catalyst which only changes the chemical reaction rate without changing the total reaction standard Gibbs free energy, factors affecting the Cu/SiO2 catalytic reaction were derived from the decomposition rate of Cu (OH)2 and the pH value of the system, and then it was concluded that the CuSiO3 as intermediates of Cu/SiO2 catalytic reaction accelerated the chemical reaction rate in the CMP process. It was confirmed that the Cu/SiO2 catalytic system generated the intermediate of the catalytic reaction (CuSiO3) in the CMP process through the removal rate of copper film, infrared spectrum and AFM diagrams in different pH conditions. FinalLy it is concluded that the SiO2 sol used in the experiment possesses stable performance; in the CMP process it is directly involved in the chemical reaction by creating the intermediate of the catalytic reaction (CuSiO3) whose yield is proportional to the pH value, which accelerates the removal of copper film. 相似文献