电子器件

0626030磁环的磁场分布测试研究〔刊,中〕/邱士安//电讯技术.—2006,46(4).—88-90(G)探讨了环型结构磁器件的磁场分布与器件的结构形状的关系,分析了理想霍尔传感器探头和有位置误差的实际霍尔传感器探头在环型结构磁器件磁场分布测试中对测试精度的影响。参40626031微波宽带衰减自动检定和校准系统〔刊,中〕/楼红英//现代雷达.—2006,28(7).—96-97,100(G)0626032晶片研磨与腐蚀对老化影响的探讨〔刊,中〕/琚志明//压电与声光.—2006,28(4).—464-465(L)石英谐振器在贮存、使用过程中频率随时间变化的现象称为老化。老化的特性直接影响…     

霍尔元件及其应用领域

霍尔器件是一种磁传感器。用它们可以检测磁场及其变化,可在各种与磁场有关的场合中使用。霍尔器件以霍尔效应为其工作基础。     

霍尔传感器及其应用

霍尔传感器及其应用中科院半导体研究所郑一霍尔器件是一种磁电转换的磁敏传感器，它在精密测磁、自动化控制、通信、计算机、航天航空等工业部门及国防领域有着广泛的用途。目前用得最多的是砷化像霍尔器件，锑化锢霍尔器件及硅霍尔集成电路。砷化镓霍尔器件具有耐高温、...     

横向电压型压力传感器的磁敏性及其消除法

横向电压型压力传感器的几何形状与霍尔器件相同因此也存在有磁敏性.本文用弱场近似的统计理论导出了非均匀掺杂薄层的霍尔电势表式,理论计算与实验结果相当一致.最后,介绍了一种实际上能完全消除磁场对压力传感器影响的方法,得到了很好的结果.     

自制简易高斯计

高斯计是利用霍尔传感器测量磁感应强度的仪器,由霍尔探头和测量仪表构成。霍尔传感器在磁场中因霍尔效应而产生霍尔电压,产生霍尔电压的大小在一定程度上反映了磁感应强度的强弱,根据霍尔电压公式和已知的瞿尔系数便可确定磁感应强度的实际大小。     

GaAs基霍尔传感器的研究进展

霍尔传感器作为磁传感器的重要成员,广泛应用于汽车电子和无线通信等电子系统.与以第一代半导体材料硅、锗等为基底的霍尔传感器相比,GaAs基霍尔传感器具有更高的磁场分辨率、灵敏度和稍好的温度特性.概述了GaAs材料在霍尔传感器领域的优势及霍尔单元形状的研究进展;综述了采用外延工艺制备的单外延结构的GaAs基霍尔传感器和异质结构的GaAs基霍尔传感器的研究进展;详细介绍了电压偏移消除技术的研究进展,包括结构的优化、正交对消补偿和旋转电流技术;最后对GaAs基霍尔传感器的发展趋势进行了展望.     

基于磁光晶体的光纤三维磁场传感器研究

光纤磁场传感器具有抗干扰能力强、小型化、低成本等技术优势。为了实现对空间磁场矢量的测量，基于磁光晶体提出了一种光纤三维磁场传感器。然后，设计和构建了光纤三维磁场传感器传感探头，搭建了光纤三维磁场测量系统。分析基于磁光晶体光纤三维磁场传感器的非正交误差，通过对基于磁光晶体的光纤三维磁场传感器三个传感单元两两夹角的准确测量，对系统三轴非正交误差进行标定补偿。实验测试装置利用一对通电线圈构建一维磁场对光纤三维磁场传感器系统进行三维正交标定，三轴标定精度分别为0.19°、0.26°和0.22°。实验结果表明，该基于磁光晶体光纤三维磁场传感器可实现0.2μT磁场强度分辨率和0.5°角度分辨率的磁场矢量测量。     

霍尔器件的技术状况与市场分析

霍尔器件成为商品,才三十多年的历史。迄今,霍尔器件的品种、功能和用途都有了极大的发展,而在磁敏传感器中形成了一个庞大的霍尔器件产业。 据日本电子工业振兴协会1992年的调查,当年在日本生产的传感器中,磁敏传感器的产量为10.86亿只,占传感器总产量的33％,价值1098亿日元,占传感器总价值的21％。产量居各类传感器之首,价值仅次于光传感     

基于超磁致伸缩材料的FBG电流传感系统北大核心

基于GMM(超磁致伸缩材料)的FBG(光纤布拉格光栅)电流传感器具有光学电流传感器的优点。利用自行配制的环氧树脂胶将FBG与GMM封装为一体作为传感器探头,通过增加偏置磁场改变传感器的静态工作点,采用高频性能良好的铁氧体材料作为导磁回路,约束交变电流产生的磁场并引导进入传感器探头,进而将电流的变化转变成为FBG的波长变化,通过FBG解调系统实现电流测量。通过实验对该传感器的静态和动态响应进行测试,取得了良好的实验结果。     

自适应双参考磁场梯度探测原理

本文使用4个单分量磁探头构成双参考磁场梯度探测装置.4个探头组成3个磁场梯度传感器,其中一个为信号传感器,另两个为噪声传感器.以信号传感器输出作为原始输入,噪声传感器输出作为参考输入,采用自适应噪声抵消技术,能有效消除因载体运动产生的涡流磁场及因磁探头方向相对地磁方向改变而引起的噪声输出.本文提出的双参考磁场梯度探测装置具有工艺性好,灵敏度高,虚警概率低的优点,可在实际磁探系统中使用.     

焊缝内部纵裂纹缺陷表面热特征研究

根据焊缝内部缺陷对内部热量扩散的影响,向焊缝局部表面注入热流,利用大型有限元分析软件ANSYS计算表面温度场分布,分析纵裂纹缺陷引起的表面温度场异常分布.不同长度、宽度及深度的裂纹,距加热面不同距离引起的表面温度场异常分布情况不同.文章重点研究了表面热特征与裂纹缺陷尺寸,缺陷位置及注入的热流密度的定量关系.本文工作可为实施红外无损检测提供方法,并为相关标准的制定提供依据.     

自相关分析在漏磁信号检测中的应用

漏磁检测（MFL）是目前常用的一种无损检测（NDE）方法,针对漏磁检测中漏磁信号微弱且噪声影响大的问题,提出采用自相关分析的方法处理漏磁信号,提高检测精度。通过理论推导验证自相关分析能够有效消除噪声干扰．并通过Matlab仿真证明其有效性。     

基于漏磁信号的钢丝绳检测技术研究

主要讨论了钢丝绳局部缺陷(LF)和金属截面积损失(LMA)无损检测的原理,提出了一种基于漏磁信号的无损检测方法。利用永久磁铁对钢丝绳进行永久磁化,然后利用霍尔元件检测钢丝绳的磁场信号,对钢丝绳被永久磁化后的漏磁场峰-峰值与钢丝绳截面积间的关系进行了大量实验,经过数据分析和深入研究,得到了钢丝绳在截面断丝损伤类型下的峰-峰值与断丝间的关系。在此基础上研制了智能钢丝绳LF无损检测仪器,该仪器基于霍尔元件检测钢丝绳径向漏磁通的原理,用AT89C51单片机组成的检测系统,使用简单方便,具有工业实用价值和较高的性价比。     

A method of moments solution for electromagnetic scattering by inhomogeneous dielectric bodies of revolution

A method of calculating the electromagnetic scattering from and internal field distribution of inhomogeneous dielectric bodies of revolution (BOR) is presented. The method uses a typical mode-by-mode solution scheme. The electric flux density is chosen as the unknown quantity, which, together with the special construction of basis and testing functions, enables considerable reduction of the number of unknowns. A key element in this technique is expressing of the azimuthal field components of basis functions in terms of transverse components. A Galerkin testing procedure is used, with special attention put on the efficiency of calculating scalar potential term. Results of calculation for a few classes of dielectric bodies are given and compared with calculations done by other authors.     

LED检测方法探讨

主要讨论了发光二极管(LED)的一些检测参量,包括LED发光强度、总光通量和发光光谱等;同时,对检测的环境条件也进行了分析研究。     

以磁通等效实现磁悬浮轴承磁极容错控制

针对8磁极电磁轴承容错控制问题,文中提出了一种基于磁通等效的电磁轴承容错控制方法。该方法首先通过仿真得到磁通的电流-磁通影响系数,利用线性代数理论计算得到电流分配矩阵。当某一个磁极回路发生故障时,利用电流分配矩阵计算重构电流,使8个磁极端面的磁通在故障前后保持不变,即磁通等效,从而实现容错运行。在ANSYS有限元仿真平台进行仿真,用磁通等效方法可以较好地还原故障前的端面磁通和磁力线分布,并计算得到了磁通误差(最大不超过3.2%,绝大部分小于0.5%)和力误差(最大不超过7%,绝大部分小于1.5%),证明了所提出磁通等效容错控制方法的有效性。     

A study of electromigration in 3-D flip Chip Solder joint using numerical Simulation of heat flux and current density

This paper applies an analogy between heat flow and current flow to examine the current density distribution in a solder interconnect, which has a direct relationship with the atomic flux movement. From a three-dimensional heat conduction analysis, we discover that the heat flux distribution in the solder bump is a strong function of the direction of heat flow. If the heat flow turns 90/spl deg/ when it leaves the solder bump, the high heat flux region will also turn 90/spl deg/. From a cross-sectional view of the mean heat flux, the high heat flux (or current flux) region in the solder moves from the top of the under-bump-metallurgy region to the lower right corner, and the right side of the solder has the highest flux density. This result correlates well with the experimental data where the measured atomic flux in the left side of the solder is less than in the right side. Two other cases with 0 and 180/spl deg/ heat flows also illustrate the difference in heat flux distribution. This suggests that the current density distribution in the solder changes as the direction of the current flow changes.     

Lead-free solder flip chip-on-laminate assembly and reliability

This paper examines the assembly process for flip chip die with SnAgCu solder bumps and the results of liquid-to-liquid thermal shock testing. The SnAgCu alloy required a thicker dip layer of flux to achieve good wetting compared to the SnPb eutectic alloy. A liquid spray flux yielded more consistent solder wetting with the SnAgCu alloy. With both fluxes, a nitrogen reflow atmosphere was necessary with the SnAgCu alloy. A peak reflow temperature of 246°C was used for the assembly of the SnAgCu thermal shock test vehicles. A lower peak temperature of 235°C did not yield sufficient solder wetting. Liquid-to-liquid thermal shock testing was performed from -40°C to +125°C. The SnPb alloy performed slightly better than the SnAgCu and the dip flux was better that the spray flux. The degree of delamination with the SnAgCu alloy was significantly higher than with the SnPb alloy. Cracks in the underfill between adjacent solder balls were observed. The SnPb alloy extruded into these cracks more readily than the SnAgCu and created electrical shorts     

激光法实时测量真空室内原子蒸气束的二维密度通量分布

介绍一种利用激光诱导荧光法实时测量真空室内原子蒸气束的二维密度通量分布的方法与装置。实验结果表明：以点（４×６ｍｍ２）为蒸发模型的二维密度通量分布规律不随加热功率的变化而改变，且这个分布规律可用余弦分布近似来描述。密度通量与加热功率近似呈线性关系变化。     

Experimental Wettability Study of Lead-Free Solder on Cu Substrates Using Varying Flux and Temperature

The selection of soldering flux plays a critical role in promoting wetting and product reliability of printed circuit board assemblies. In this study, the effects of fluxes on the wetting characteristics of the Sn-3.0Ag-0.5Cu solder alloy on Cu substrates was researched by using various flux systems at different soldering temperatures. Because of the distinct characteristic of the lead-free solder—poor wettability—three kinds of fluxes [no-clean flux with high solid content (NCF), rosin mildly activated flux (RMA) and water-soluble flux (WSF)] were chosen for the wetting experiments. The wetting time and force were the evaluating indicators. The experimental observations indicated that the wettability clearly depended on the soldering temperature and flux system when using the same solder. Furthermore, the corrosion potential of flux residues was measured by surface insulation resistance (SIR) testing. Scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS) were used to determine the contents of the flux residues and corrosion products.