受控电阻及其基于LDO零极点追踪频率补偿方案的应用

本文利用工作在深度线形区的MOS管电阻和辅助电路设计了一个受控电阻。其中辅助电路为MOS电阻提供正比于LDO输出电流的栅源电压,从而使得MOS电阻的等效阻值反比于LDO的输出电流,这种反比关系非常适合零极点追踪的频率补偿方案。通过调整MOS电阻的类型和流过辅助电路中的电流方向,受控电阻可以应用于不同的电路结构。利用该受控电阻,本文提出了三种分别基于带去零电阻的米勒电容、单位增益补偿模块和伪ESR功率级电路结构的零极点追踪频率补偿方案。三个方案都通过了仿真验证,并对其优缺点进行比较和讨论。     

回路电流矩阵方程的一种直观列写方法

给出一种直观列写电路回路电流矩阵方程的方法,通过直观建立独立源,受控源和控制变量等向量的KCL、KVL方程,使回路电流方程直观写出。该法可适用于含有各类受控源的电路,进行矩阵运算便可得到的回路电流解向量和任意输出解向量。     

高精度数控直流电流源的设计

本设计实现了直流电流源的数字化控制。整个系统由线性受控直流源、精密测量控制电路和人机接口三部分组成。电流源为双环控制系统,通过控制调整管的驱动电流,可精确控制电流源输出值的大小。测试表明该电流源具有良好的稳压稳流性能和极低的电流纹波。     

LT1620/LT1621轨对轨电流感测放大器

当LT1620与一颗电流模式PWM控制器IC连结起来时,可轻易达成高效能,电流受控的电池充电电路。 LT1620可调整平均输出电流而与输出入电压变化无关。输出电流可轻易的藉由调整LT1620的PORG脚位电压而设定。大部分电流模式的PWM控制器输出电压范围,因电流感测输入端共模电压的限制而被限制住。而     

电子式程控电阻、电容通用模拟器设计

为提高电阻、电容测量仪的校准和计量效率,减小校准器具的费用,设计了一种电子式程控电阻、电容通用模拟器。采用跨导放大器将流过参考阻抗元件的电流转变为电压信号,该电压信号经过程控增益单元后作为受控电流源的输入,受控电流源的输出与参考阻抗元件并联,改变程控增益单元的增益,可连续设定模拟阻抗元件的参数值。实验结果表明,该通用模拟器设定范围较广、精度较高,具有较好的实用价值。     

增益预泵浦被动调Q DPL频率稳定性研究

影响增益预泵浦被动调Q DPL频率稳定性的因素很多, 其中预泵浦电流和主泵浦电流与其关系最为密切。在此基础之上,提出了用于增益预泵浦被动调Q DPL的台阶式电流跳变电源设计方案,完成了外部控制电路。将预泵浦电源分为控制电路和受控电源两部分,这种分离式的设计保证了受控电源与控制电路的独立性,有利于提高各自的稳定性。并通过实验获得了跳变斜率K=0.5 A/?滋s时,激光电源系统频率2 kHz下较为理想的满足预泵浦技术要求的电流输出波形,满足了设计要求,为提高被动调Q DPL频率稳定性奠定了基础。     

一种用于超声电机驱动的半桥集成电路的设计

在超声波电机应用系统中,超声波电机驱动电路的小型化越来越重要。该文基于0.35 μm的双极互补双扩散金属半导体（BCD)工艺设计了一款单片集成超声波电机驱动电路的芯片,本芯片包括一个非同步峰值电流模升压电路和2个半桥驱动电路。非同步峰值电流模升压电路给半桥驱动电路提供电源,具有自适应死区时间控制的2个半桥驱动电路,其输出的2个相位差90°的方波用于驱动超声波电机。     

微功率降压型稳压器可安全地承受汽车负载突降设计要点475

引言 当在那些出现输出短路和过载情况的应用中使用降压型稳压器时,在全速运作的情况下,将电感器电流保持于受控状态所需的占空比可以低于稳压器的最小占空比.     

双通道控制器可为1．5V电压轨提供2μs阶跃响应和92％效率

引言 LTC@3838是一款双输出、两相降压型控制器，其采用一种受控恒定导通时间、谷值电流模式架构，可提供快速负载阶跃响应、高开关频率和低占空比能力。     

6061铝合金超声波辅助激光焊接变形控制研究

为了解决6061铝合金在激光焊接过程中出现的易变形、变形大的问题,采用施加超声波以辅助焊接的方法,以1mm厚的6061铝合金薄板为研究对象展开超声波辅助激光焊接试验,探究超声波对6061铝合金焊接变形的抑制作用;利用单因素试验方法分析了超声波功率对焊接变形的影响规律,设计包括超声波功率、激光功率、焊接速率、离焦量、保护气流量在内的五因素五水平正交试验,分析了超声波功率以及常规焊接参量分别对焊接变形的影响程度,并获得了能够得到最小变形的工艺参量组合。结果表明,焊接变形会随着超声波功率的增加而减小,超声波功率800W时较无超声情况下试件的挠曲变形及角变形分别减小了51.27%和51.46%;同时,当激光功率为1000W、焊接速率为5m/min、离焦量为+1mm、保护气流量为15L/min、超声波功率为800W时, 可以获得变形最小的试件,所得到的试件挠曲变形量为0.42mm,角变形量为0.26mm。此研究为超声波辅助焊接在控制薄板焊接变形方面的应用提供了一定的工艺和理论参考。     

金丝键合工艺技术研究

金丝键合是芯片组装的关键工序。分析了金丝键合的工艺控制要点：键合时间和键合功率,通过工艺实验总结出了键合时间和键合功率对键合强度的影响规律：（1）在小超声功率条件下,键合强度对键合时间敏感,键合强度随时间增加迅速增大;在大超声功率条件下,键合强度对键合时间的敏感性下降。（2）超声功率过小不能形成足够的键合强度,超声功率过大使得键合成功后的键合强度被破坏,即过高的超声功率将不利于键合强度的提高。     

超声换能系统电特性实验研究

超声换能系统是引线键合设备的核心部件,对其工作特性的深入了解有助于理解引线键合过程.通过实验,观察分析了超声引线键合过程中不同劈刀安装长度对换能系统电流、电压及功率的影响,发现电流及功率在不同劈刀安装长度时有较为明显的变化.并进一步采用小波分析方法展现了电流信号在时频域内变化的细节情况,为充分了解换能系统电学特性提供了可靠依据和新的方法.     

劈刀安装长度对引线键合强度影响的实验研究

在超声引线键合中引线键合质量受到多种因素的影响。该文通过实验,观察了超声引线键合过程中不同劈刀安装长度对引线键合质量形成的影响,同时对引线键合过程中换能系统电流、电压及功率进行了分析,发现不同劈刀安装长度会导致引线键合质量、电流及功率较为明显的变化。该实验的结果可为实际引线键合中劈刀安装长度的选择提供参考。     

Reliability of thick Al wire: A study of the effects of wire bonding parameters on thermal cycling degradation rate using non-destructive methods

The effect of bonding parameters on the reliability of thick Al wire bond is investigated. Samples were prepared with 25 different designs with 5 different bonding parameters such as time, ultrasonic power, begin-force, end-force and touch-down steps (pre-compression) with 5 levels. The bond signals of ultrasonic generator were collected during bonding in order to obtain prior quality information of bonded wires. 3D X-ray tomography was then used to evaluate bond quality during passive thermal cycling between −55 °C and 125 °C. Tomography datasets were obtained from the as-bonded condition and during cycling. The results clearly show ultrasonic power, appropriate levels of begin-force and touch-down steps are all important for achieving a well attached and reliable bond. Analysis of the virtual cross-sections indicates a good correlation between the bond signal (i.e. the initial bond quality) and wire bond damage/degradation rate. An improved understanding of the wire bonding process was achieved by observing the effect of the complex interaction of bonding parameters on the ultrasonic generator signals and degradation rate under thermal cycling.     

基于DOE和BP神经网络对Al线键合工艺优化

Al丝超声引线键合工艺被广泛地应用在大功率器件封装中,以实现大功率芯片与引 线框架之间的电互连.Al丝引线键合的质量严重影响功率器件的整体封装水平,对其工艺参数的优化具有重要工业应用意义.利用正交实验设计方法,对Al丝引线键合工艺中的三个最重要影响因数(超声功率P/DAC、键合时间t/ms、键合压力F/g)进行了正交实验设计,实验表明拉力优化后的工艺参数为:键合时间为40 ms,超声功率为25 DAC,键合压力为120g;剪切推力优化的工艺参数为:键合时间为50 ms,超声功率为40 DAC,键合压力为120 g.基于BP神经网络系统,建立了铝丝超声引线键合工艺的预测模型,揭示了Al丝超声键合工艺参数与键合质量之间的内在联系.网络训练结果表明训练预测值与实验值之间符合很好,检验样本的结果也符合较好,其误差基本控制在10%以内.     

LTCC基板金丝热超声楔焊正交试验分析

引线键合是微组装技术中的关键工艺,广泛应用于军品和民品芯片的封装。特殊类型基板的引线键合失效问题是键合工艺研究的重要方向。低温共烧陶瓷(LTCC)电路基板在微波多芯片组件中使用广泛,相对于电镀纯金基板,该基板上金焊盘楔形键合强度对于参数设置非常敏感。文章进行了LTCC基板上金丝热超声楔焊的正交试验,在热台温度、劈刀安装长度等条件不变的情况下,分别设置第一键合点和第二键合点的超声功率、超声时间和键合力三因素水平,试验结果表明第一点超声功率和第二点超声时间对键合强度影响明显。     

Investigation of ultrasonic vibrations of wire-bonding capillaries

Ultrasonic energy is widely used in wire bonding for microelectronics packaging. It is necessary to ensure that the maximum ultrasonic vibration displacement occurs at or near the tip of the bonding tool (capillary) for optimal performance. In this study, amplitude profiles of ultrasonic vibrations along capillaries were measured with load using a laser interferometer. This provided valuable information in understanding and improving capillary performance. The method was applied to real time applications to optimize capillary designs and bonding processes for specific bonding applications. First, the application of a new capillary material with different zirconia compositions was evaluated. The new material with certain amount of zirconia composition showed that it was the capillary material of choice for ultra-fine pitch wire bonding. Next, comparative analysis was conducted to investigate the ultrasonic energy transfer of a new ‘slimline’ bottleneck and the conventional bottleneck. The actual bonding response of the molded slimline bottleneck showed comparable performance with the ground conventional bottleneck using the same bonding parameters. Finally, optimization of a 60-μm-bond-pad-pitch process was performed on a wire bonder. Within the optimized parameter ranges, the ultrasonic displacement of the capillary was monitored. For all possible combinations of bond force and bond power, the ultrasonic displacement of the capillary increased with increasing bond power, without drastic changes caused by bond force changes. This indicated that the selected process window was located in a stable region.     

金丝楔形键合强度的影响规律分析

金丝楔形键合是一种通过超声振动和键合力协同作用来实现芯片与电路引出互连的技术。现今,此引线键合技术是微电子封装领域最重要、应用最广泛的技术之一。引线键合互连的质量是影响红外探测器组件可靠性和可信性的重要因素。基于红外探测器组件,对金丝楔形键合强度的多维影响因素进行探究。从键合焊盘质量和金丝楔焊焊点形貌对键合强度的影响入手,开展了超声功率、键合压力及键合时间对金丝楔形键合强度的影响研究。根据金丝楔焊原理及工艺过程,选取红外探测器组件进行强度影响规律试验及分析,指导实际金丝楔焊工艺,并对最佳工艺参数下的金丝键合拉力均匀性进行探究,验证了金丝楔形键合强度工艺一致性。     

Numerical analysis of ultrasonic wire bonding: Part 2. Effects of bonding parameters on temperature rise

The thermo-structural analysis of ultrasonic wire bonding is performed by means of 3D finite element method. A special focus has been placed on monitoring the temperature rise during ultrasonic vibration. An equivalent method is used to simulate the wire and bond pad, where the large volumes of wire and bond pad are effectively reduced to small computational magnitudes. The history of temperature changes in the wire-bond pad-substrate interfaces influenced by varying bond forces and bond pad sizes is specifically studied. It is shown that the maximum bulk temperature obtained upon completion of ultrasonic vibration is far lower than the melting temperatures of the wire and bond pad materials, indicating that the bulk temperature rise due to ultrasonic vibration is not directly responsible for ultrasonic wire bonding. A large bond pad size usually leads to a lower temperature rise, and when the pad size reaches a certain value, the effect of bond pad size on temperature rise becomes insignificant. A higher bond force results in a marginally higher temperature rise than a lower bond force, which does not necessarily affect the wire bondability.     

In situ ultrasonic force signals during low-temperature thermosonic copper wire bonding

Ultrasonic in situ force signals from integrated piezo-resistive microsensors were used previously to describe the interfacial stick-slip motion as the most important mechanism in thermosonic Au wire ball bonding to Al pads. The same experimental method is applied here with a hard and a soft Cu wire type. The signals are compared with those obtained from ball bonds with standard Au wire. Prior to carrying out the microsensor measurements, the bonding processes are optimized to obtain consistent bonded ball diameters of 60 μm yielding average shear strengths of at least 110 MPa at a process temperature of 110 °C. The results of the process optimization show that the shear strength c_pk values of Cu ball bonds are almost twice as large as that of the Au ball bonds. The in situ ultrasonic force during Cu ball bonding process is found to be about 30% higher than that measured during the Au ball bonding process. The analysis of the microsensor signal harmonics leads to the conclusion that the stick-slip frictional behavior is significantly less pronounced in the Cu ball bonding process. The bond growth with Cu is approximately 2.5 times faster than with Au. Ball bonds made with the softer Cu wire show higher shear strengths while experiencing about 5% lower ultrasonic force than those made with the harder Cu wire.