Understanding the failure mechanisms of microwave bipolar transistors caused by electrostatic discharge

Electrostatic discharge(ESD) phenomena involve both electrical and thermal effects,and a direct electrostatic discharge to an electronic device is one of the most severe threats to component reliability.Therefore, the electrical and thermal stability of multifinger microwave bipolar transistors(BJTs) under ESD conditions has been investigated theoretically and experimentally.100 samples have been tested for multiple pulses until a failure occurred.Meanwhile,the distributions of electric field,current density and lattice temperature have also been analyzed by use of the two-dimensional device simulation tool Medici.There is a good agreement between the simulated results and failure analysis.In the case of a thermal couple,the avalanche current distribution in the fingers is in general spatially unstable and results in the formation of current crowding effects and crystal defects.The experimental results indicate that a collector-base junction is more sensitive to ESD than an emitter-base junction based on the special device structure.When the ESD level increased to 1.3 kV,the collector-base junction has been burnt out first.The analysis has also demonstrated that ESD failures occur generally by upsetting the breakdown voltage of the dielectric or overheating of the aluminum-silicon eutectic.In addition,fatigue phenomena are observed during ESD testing,with devices that still function after repeated low-intensity ESDs but whose performances have been severely degraded.     

高频小功率硅双极器件ESD潜在失效的无损检测方法

目前国内外研究人员多集中于研究MOS器件和GaAs器件的静电放电(ESD)潜在性失效,而对高频小功率硅双极晶体管的静电放电潜在性失效则研究较少.为此,参考国内外研究人员的研究结果,选择采用高温反偏法、低频噪声法以及电参数测量法来对高频小功率硅双极晶体管静电放电潜在性失效的无损检测方法进行了较为细致的分析研究.通过详细比...     

ESD模拟器的应用研究

将ESD模拟器用金属网罩屏蔽,可减小模拟器内部继电器开关的电磁干扰.但屏蔽前后电流产生场变化不大,屏蔽后的辐射场场峰值仅稍低于未屏蔽的场.用该模拟器进行单片机系统的ESD抗扰度实验,发现屏蔽前后,同故障现象出现的最小放电电压值相差几千伏,即模拟器内部继电器开关产生的辐射场对实验结果有影响.这说明IEC标准仅仅规定ESD放电电流的波形是不够的,应对放电场做出相应规定.     

封装形式对瞬态电压抑制器件电磁脉冲防护特性的影响(英文)

Adding transient voltage suppressor(TVS) transistors to an electric circuit is an important method to protect it from the fast-risetime electromagnetic pulse(FREMP) damage. The package form of the TVS transistors influences the volume, response time, and power consumption of the circuit. However, the influence of the package form on the clamp voltage of TVS transistors affected by FREMP is not considered yet. In this article, the results of the experiment comparing the influence of package form are described, where the rectangular pulses with rise time shorter than 1 ns are used to test protection performance of three different TVS transistors, which have the same framework but different breakdown voltages. The influence of the different package forms on the clamp voltage is analyzed by using the fitting model. It is found that the package form of TVS transistors has less influence on the current characteristics of their protection performance, but more on the voltage characteristics. It is concluded that the diameter or width of the TVS transistors is the main factor determining the clamp voltage. Thus, the diameter or width of the TVS transistors should be big enough to ensure the stabilization of clamp voltage, but, at the same time, fit the allowing volume.     

瞬态电压抑制器在快上升沿电磁脉冲作用下的瞬态响应

为了研究瞬态电压抑制器(TVS)对快上升沿电磁脉冲的响应,基于传输线脉冲(TLP)测试理论,建立了由高频脉冲发生器、同轴电缆、专用测试夹具、30dB脉冲衰减器和高性能的数字存储示波器等组成的测试系统。参考时域传输(TDT)TLP测试方法,利用该测试系统,对典型双极TVS器件在快上升沿电磁脉冲作用下的电流特性和电压特性进行了研究,并对试验数据进行了拟合分析。结果表明,TVS器件的箝位电压、峰值电流等参数均随着测试电压的增大而增大,且与测试电压呈线性关系;而由箝位电压决定的箝位响应时间受测试电压的影响较小。经对比分析实验结果得出,对快沿电磁脉冲,采用固定响应时间下的箝位电压来衡量TVS器件的防护性能是较为合理的。     

航空发动机试车中转子故障诊断

航空发动机成本高,寿命低,难维护;发动机故障造成飞机失事的例子时有发生,倍受人们的重视;据统计,该类故障中的80％来自于结构复杂、高速旋转的转子部件;讨论生产试车中转子振动故障的早期诊断技术,首先分析转子、叶片、轴承、齿轮故障的特征;而后通过实时的功率谱、倒频谱分析技术识别与此特征对应的故障位置、类型及程度;最后以某型发动机转子振动的实例说明该项技术的实际应用。     

空气式静电放电抗扰度试验方法

静电放电(electrostatic discharge,ESD)抗扰度试验作为电磁兼容(EMC)试验的一项重要内容,其执行标准IEC 61000-4-2还存在诸多问题,尤其是空气式ESD的重复性问题。为此,基于动能-势能转换原理,采用导轨带动电极运动结构和步进电机装置,用近似单摆结构的试验方法,设计和研制了2种新的ESD抗扰度试验平台,实现了空气式ESD抗扰度试验中对放电电极接近速度的准确控制。利用这2种ESD抗扰度试验平台对空气式ESD的重复性进行了研究。试验结果表明,ESD参数如放电电流峰值、接近速度和放电电压具有很好的规律性,并且在一定的放电电压和接近速度下,空气式ESD也可以具有较好的重复性。在相同放电电压和接近速度下,利用第2种ESD抗扰度试验平台得到的放电电流峰值和上升时间的变异系数均小于利用第1种ESD抗扰度试验平台得到的放电电流峰值和上升时间的变异系数,因此第2种单摆式ESD抗扰度试验平台的重复性要好于第1种ESD抗扰度试验平台的重复性。     

推行“油改电”项目节能增效的探讨

针对大庆油田深井钻机能耗较高的突出问题,以节能增效为目的进行管理创新,改变电动化深井钻机传统驱动方式,由柴油机发电机组驱动钻井改为利用工业电网驱动钻井(简称"油改电")。通过现场调研和理论分析及现场实践,解决了钻机改造和设备配套方面的几项关键技术,实现了利用工业电网驱动钻井的安全性、节能性和实用性;试验井资料分析表明效果显著,完全可以在油田全面推行"油改电"项目,为油田节能增效实现绿色钻井、科技钻井拓宽了渠道。     

静电放电和方波EMP对微电子器件的效应

为了得到微波低噪声晶体管电磁脉冲的最灵敏端对和最敏感参数以及相关规律和器件的损伤/失效机理和模式,首先采用静电放电人体模型(HBM),针对两类硅晶体三极管(3DG218、3358)进行了静电放电敏感性相关实验,得到该类晶体管的ESD敏感端对是CB结;器件损伤时的灵敏参数是VBRCEO;又采用方波注入法对两晶体管进行实验比较了从CB结反向注入与从EB结反向注入的损伤电压值,发现该类器件的EMP最敏感端对是CB结而非以往人们认为的EB结。     

ESD辐射场的计算及对传输线的耦合研究

为分析静电放电的辐射场及其对传输线与负载终端的影响,采用了一种基于脉冲函数的静电放电电流波形解析表达式计算了静电放电电磁脉冲辐射场并给出了近场和远场波形。结果表明放电电场包括由初始电荷引起的静电场和由放电电流引起的辐射场,在放电电极附近,静电场远大于辐射场,但静电场随空间距离衰减得很快,在远区场主要由放电电流引起的辐射场。利用传输线理论建立静电放电场对电长导线的耦合计算模型得出了静电放电辐射场在线上的感应电压和感应电流计算方程。