片状电阻器开短路失效模式浅析

圆柱形空气调节器相比传统空调器不仅外观优雅大方,而且可实现多向均匀出风,出风范围广,舒适度大大提升,而其核心是空调控制器的功能实现.实际过程及售后频繁出现控制器片状电阻失效故障,困扰供应商的同时造成客户投诉问题.片状电阻普遍用于控制器,相对于传统的电阻具有面积小、空间利用率高等优点,应用非常广泛.本文重点对片状电阻失效...     

集成电路开短路失效原因探讨

对过电应力引起的CMOS集成电路的开短路失效模式,从电路结构、导电通路、误操作等方面进行了失效原因探讨。列举了一些过电应力的来源,说明了电压或电流幅度很小也可导致过电应力烧毁,从而说明了根据失效模式来寻找过电应力来源的困难性。对失效分析、故障归零将有很好的参考价值。     

浅析PCB的短路与开路

主要针对印制电路板的短路与开路的一般现象、类型、原因及对策作一简单的阐述,希望广大同仁能够从中找到适合自己的东西,在生产中加以重视,由此来提高产品的质量。     

短路定位仪在高密度集成PCBA短路故障定位中的应用

文章调研了当前业界主流的PCBA短路定位仪,梳理出不同的短路测试方法的适用场景和优缺点;并针对当前高密度集成PCBA的典型短路故障,尤其是大面积选用BGA封装和LGA封装等高密度集成芯片的PCBA,通过应用综合性能优异的短路定位仪,验证短路定位仪在PCBA各种短路故障的定位效果,实际验证结果表明短路定位仪可极大提升高密度集成PCBA短路故障排查的效率,缩短定位排查周期,且定位精度高、短路故障修复引入的成本极低。     

平板裂缝天线短路板边缘辐射裂缝的研究

对平板裂缝天线驻波子阵间短路板的两种处理方法———短路板插入法和短路板融入法进行了研究。结果表明 ,保持所有辐射裂缝单元间距相等的短路板融入法有利于低副瓣性能的实现。对于短路板融入法 ,采用镜像原理导出了短路板产生的TE2 0模对相邻辐射裂缝导纳影响的解析表达式。     

铝电解电容器开路和假性短路现象分析与改进

导针型铝电解电容器的开路现象主要是因为裂箔、钉接不良、钉接花瓣小、正箔表面箔灰厚及原箔腐蚀太深而造成。假性短路的现象主要是跑片、抽芯、钉花毛刺、导针毛刺、铝箔边缘毛刺、芯子高低脚等原因而造成。只要加强工艺的控制、选用适当的材料可以杜绝铝电解电容器的开路和假性短路现象的发生。     

元器件开短路测试应用

该文从开短路测试原理出发,使用A567测试台对二输入与非门54LS00的输入、输出管脚进行Open-Short测试,验证了此方法快速检测出被测器件是否存在引脚短路、断路、静电保护功能丧失等缺陷的可行性。     

分元法与补元法的进一步研究

本文进一步研究了分元法与补元法在平面电路中的应用,导出了分元法广义节点电压方程。比较了分元法、补元法采用点匹配时二者的计算精度,用实例研究了将其用于短路型平面电路中的问题。     

一种快速开短路测试算法

文章设计了一种快速开短路测试算法,利用短路群概念。对于N个引脚的连接器,只用N-1个量测步骤即能完成所有引脚两两之间的开短路测试。而通过传统的测试算法,两两引脚之间测试开短路,N个引脚至少需要N(N-1)/2个量测步骤。且随着连接器引脚数的增加,采用新算法节约的测试时间会呈几何级数增加。     

浅谈印制电路板信号损耗测试技术

在印制电路板设计、生产等过程中,传输线的信号损耗是板材应用性能的重要参数。信号损耗测试是印制电路板的信号完整性的重要表征手段之一。本文介绍了目前业界使用的几种PCB传输线信号损耗测量方法的原理和相关应用,并分析了其优势和限制。     

浅谈PCBA分层爆板

针对当前各PCB(Printed Circuit Board)供应商、就频繁遭受自己客户投诉PCBA(PrintedCircuit Board Assembly)分层爆板一事,发表一下自己的见解。希望借此论坛为契机,做出这样一个选题,能够引起大家的关注,有助于大家解决今后的一些纠纷;也希望有更多的PCB制造商以及贴片厂商明白,其实造成PCBA分层爆板问题的发生,不单单只是某个方面的原因,有着更多的系统因素。如果双方明白了这个道理,最终达成共识,作为后续双方坦诚、妥善处理这一问题的依据,我想这才是我此篇文章真正的用心所在!     

A SWITCHED CAPACITOR CIRCUIT ANALYSIS PROGRAM AND ITS APPLICATIONS

A program developed for analyzing arbitrary N-phase switched capacitor circuits is presented.Application of the program is given.The program simulation facilities,such as time-domain analysis,frequence-domain analysis,sensitivity analysis and multiple ohjective optimization are described.Thealgorithm used in the program is introduced briefly.Several examples are given to show the application of theprogram.     

On a common error in open and short circuit reliability computation

In reliability computations for complex systems subject to two kinds of failure, analysts sometimes underestimate system reliability by using a formula that actually applies only to certain simpler structures. This error occurs several times, for example, in an otherwise instructive paper by B.W. Jenney and D.J. Sherwin (ibid., vol.R-35, p.532-8, Dec. 1986). The purpose of this work is to describe the error, illustrate how it arises in practice, and offer a correction     

Analog circuit optimization using adjoint network based sensitivity analysis

Performance optimization as per the desired specifications is a major requirement of analog and mixed signal circuit design process. Rapid scaling of the semiconductor technology demands efficient optimization techniques with minimal manual efforts. In this paper, a gradient based method for analog circuit optimization using adjoint network based sensitivity analysis is presented. The sensitivity of circuit response with respect to the different parameters is computed by using analog circuit and its adjoint transformation. The proposed method is applied to optimize performance of a two stage operational amplifier (OpAmp). Subsequently, the OpAmp circuit is simulated using Cadence Virtuoso for optimized parameters and the results are validated with post fabrication measurement results.     

电子组装中PCBA清洗技术

清洗对于电子产品可靠性有着非常重要的影响,针对印制电路组件污染物进行了系统阐述,并对不同的清洗技术和工艺进行了总结归纳,讨论了影响清洗效果的各个因素及其检验规范,为实际生产起到了指导性作用。     

An analysis method for high-speed circuit systems

A new method for analyzing high-speed circuit systems is presented. The method adds transmission line end currents to the circuit variables of the classical modified nodal approach. Then the matrix equation describing high-speed circuit system can be formulated directly and analyzed conveniently for its normative form. A time-domain analysis method for transmission lines is also introduced. The two methods are combined together to efficiently analyze high-speed circuit systems having general transmission lines. Numerical experiment is presented and the results are compared with that calculated by Hspice.     

印制电路板高频介电常数测试技术现状分析

在印制电路板的设计、生产等过程中,板材的介电常数和介质损耗角正切都是影响板材应用性能的重要参数,因此,介电常数的测量准确性十分重要。本文介绍了目前使用的几种高频介电常数测量方法的原理、标准和相关产品,并分析了其优势和不足,以及测量技术的发展趋势。     

Relationship between HOMO energy level and open circuit voltage of polymer solar cells

A series of π-conjugated polymers (PDHF-BT and PDHF-TBT) with 4-(3,4-ethylenedioxythienyl)-2,1,3-benzothiadiazole (BT), 4,7-bis(3,4-ethylenedioxythienyl)-2,1,3-benzothiadiazole (TBT), and 9,9′-dihexylfluorene were synthesized by the Suzuki coupling reaction. The HOMO energy level of PDHF-BT was −5.47 eV, which was lower than that of PDHF-TBT (−5.22 eV), while the LUMO energy level of PDHF-BT (−3.45 eV) was very similar to that of PDHF-TBT (−3.42 eV). These energy levels of PDHF-BT and PDHF-TBT were also supported by a DFT calculation. The power conversion efficiency (PCE) of the polymer solar cell (PSC) with a structure of ITO/PEDOT:PSS/PDHF-BT:PCBM (1:1)/Al was determined as 0.34% and it was larger than that of the device based on PDHF-TBT (0.22%). Correspondingly, the V_oc of the PSC based on PDHF-BT (0.71 V) was much larger than that of the device based on PDHF-TBT (0.40 V). The results support that the V_oc of polymer based PSCs is strongly related to the HOMO energy level of the active polymers.     

共模环路闭合与开路的天线模型及其计算分析

应用矩量法计算了折线电天线、方形环天线和加载电容方形环天线的电流分布,计算结果表明:当加载电容的方形环天线所加载的电容很大或很小时,其电流分布分别与闭合环天线和开路折线电天线的电流分布相吻合;并在此基础上进一步计算和分析了不同频率下环路闭合与开路的天线辐射场,研究结果对分析电磁兼容共模辐射问题有一定的参考价值.