塑封分立器件的分层问题

文章先是对分层进行概述,又详细阐述了分层分类,最后分析介绍了分层解决方案的制定,以避免分层问题的出现,降低器件失效的几率,提高可靠性。     

半导体分立器件行业用焊料现状

<正>一、焊料在半导体封装行业中的作用在半导体分立器件封装行业中,焊料的作用是通过焊接将引线、框架与晶粒进行连接,形成牢固的电路导通和热传导,使元器件具备稳定、可靠的使用性能。根据分立器件封装工艺及应用要求的特点,焊料需满足的要求有以下3方面:熔点高于260℃——满足二次回流(无铅回流焊)中封装焊点不熔化;合金硬度小——半导体晶片较脆,受到合金应力及后道加工过程影响,容易被挤碎;润湿——能够与铜、银、镍形成牢固的冶金结合。目前行业中广泛使用的合金为     

天津将建国内最大的半导体分立器件和硅材料生产基地

据有关媒体报道，天津市规划投资683亿元，加快发展移动通信产品、显示器、电子元器件三大优势领域。“十一五”期间，将形成手机1亿部、片式元器件1400亿只、半导体芯片150万片、硅材料400吨的年产能力，使之成为全国最大的半导体分立器件和硅材料生产基地。将重点支持3G手机和设备、100英寸以上显示设备的开发和生产；重点发展高速、小型、贴装化高压整流器件及硅材料生产，     

双极型半导体电路静电损伤失效分析

从通信设备维修中发现的一例静电放电(ESD)导致模拟电路失效的典型案例分析入手,介绍了在失效分析中把管脚间测试结果同电路内部版图和逻辑图相结合来定位失效部位的方法.     

分立型半导体激光器线阵温度场分析

目的 研究半导体激光器线阵的温度场分布,为设计冷却方案提供理论依据。方法 用分离变量法推导简化后系统的温度场分布函数,获得理论最高温度所在位置;建立合理的有限元模型,在ANSYS系统上进行数值仿真。结果 得到系统稳定后的温度场分布图,确定了半导体激光器线阵在整个工作时间内的最高温度及其所在位置。结论 根据简化后的数学模型,用有限元法得到的温度场分布与用分离变量法进行的理论分析得到的结论相一致。     

半导体功率器件分层改善

器件分层是功率器件常见的失效模式之一,它制约着功率器件性能的进一步提高。本文旨在通过框架的优化设计、Molding Compound及框架材料合理搭配和封装工艺的优化来达到改善分层的目的。     

航天磁性器件失效分析与筛选试验

磁性器件在航天产品中广泛,尤其在电源系统中,起着关键的作用。基于美国航天磁性器件的失效统计数据,分析了磁性器件的主要失效原因。又对国内航天磁性器件的失效进行了初步的统计和分析。通过对比美国和国内航天磁性器件由设计、生产和使用中发生的失效对比,给出了发生失效的主要原因。为了保证磁性器件的质量和可靠性,提出在参考美军标和国军标的基础上,实施国内航天磁性器件筛选试验的建议。     

电子束蒸镀半导体光电器件的增透膜

用自动电子束蒸发设备，蒸镀用于光纤通信等中的ＧａＡｓ和ＩｎＰ系列双异质结红外发光二极管的增透膜。结果表明，对波长为０．８μｍ左右的ＧａＡｌＡｓ／ＧａＡｓ发光二极管，蒸镀四分之一波长厚的Ａｌ２Ｏ３介质膜后，其输出光功率在５０ｍＡ和１００ｍＡ电流注入，可增加２５－３５％，最大可增加－５０％。对１．３μｍ波长的ＩｎＰ系列红餐发光管，用ＺｒＯ２作介质增透膜效果更好。     

基于摩擦热效应引起的失效分析及预防措施

从摩擦学理论角度和失效原因的深入分析,开展了磨损失效的实验研究和对摩擦热效应引起失效的机理进行了探讨.摩擦学性能及磨损特性研究表明磨损失效是设备失效的主要失效形式之一;对摩擦热效应引起的失效分析又进一步表明:摩擦热效应引起的失效是与磨损相关的一种重要失效形式.结合工程实际,提出了几种预防失效的措施.     

纤维/基体界面应力分析及界面失效

通过对纤维和基体的变形分析, 建立求解界面问题的基本方程。采用位移函数法, 导出比 较简明的界面剪应力分析表达式。通过界面应力分析, 引入界面剪切强度, 得到一般界面失效准 则。      

突跳式温控器的失效分析

突跳式温控器失效会导致电茶壶、电饭煲等家电产品控温和过热保护功能失效.采用FMECA分析方法,确定导致突跳式温控器失效的关键元件,通过关键元件失效分析,得到突跳式温控器的失效机理,提出提高突跳式温控器工作可靠性的技术措施.FMECA分析表明,突跳式温控器的主要失效模式为触头粘结、簧片断裂和温度漂移,引起突跳式温控器失效的关键元件为触头、簧片、热双金属片.关键元件失效分析表明,触头粘结现象是由于触头燃弧引起的,簧片断裂现象是由于簧片受到的疲劳应力超过疲劳强度引起的,温度漂移现象是由于热双金属片尺寸参数改变或热双金属片层间分离引起的.     

An Oseen-type model for swirling internal separated flows

The viscous, laminar, separated flow downstream of a sudden expansion in a pipe is studied. The flow is modeled by an Oseen-type equation, but with the additional feature that the nonlinearity in the swirl is retained. Exact solutions are obtained for a high-Reynolds-number limit and for arbitrary Reynolds number by use of an eigenfunction-expansion procedure, in the presence of swirl. This leads to a non-standard eigenvalue problem. When the swirl is sufficiently large, a central recirculating region is observed. The effect of the pressure gradients on the velocity profiles and the central recirculating eddy is discussed. The low-Reynolds-number solutions go over smoothly to the large Reynolds number solution as the Reynolds number increases. Good agreement is obtained with the numerically computed value of the reattachment length.     

Control Charts for Monitoring Field Failure Data

One responsibility of the reliability engineer is to monitor failure trends for fielded units to confirm that pre‐production life testing results remain valid. This research suggests an approach that is computationally simple and can be used with a small number of failures per observation period. The approach is based on converting failure time data from fielded units to normal distribution data, using simple logarithmic or power transformations. Appropriate normalizing transformations for the classic life distributions (exponential, lognormal, and Weibull) are identified from the literature. Samples of size 500 field failure times are generated for seven different lifetime distributions (normal, lognormal, exponential, and four Weibulls of various shapes). Various control charts are then tested under three sampling schemes (individual, fixed, and random) and three system reliability degradations (large step, small step, and linear decrease in mean time between failures (MTBF)). The results of these tests are converted to performance measures of time to first out‐of‐control signal and persistence of signal after out‐of‐control status begins. Three of the well‐known Western Electric sensitizing rules are used to recognize the assignable cause signals. Based on this testing, the ―X‐chart with fixed sample size is the best overall for field failure monitoring, although the individual chart was better for the transformed exponential and another highly‐skewed Weibull. As expected, the linear decrease in MTBF is the most difficult change for any of the charts to detect. Copyright © 2005 John Wiley & Sons, Ltd.     

Failure analysis of a pole gin

Lugs on a cast aluminum/fiberglass pole gin failed while raising an electrical transformer on a power pole. This same system had just lowered a heavier transformer. The pole gin consisted of a cast aluminum base that was strapped to a utility pole by a nylon belt-and-ratchet mechanism. A fiberglass pole was mounted in the base, and a pulley was attached to the other end through another aluminum casting. Rigging for the lift was complex and required a physical simulation to estimate actual lug hole loads and to determine that overall loading was within the manufacturer’s published limits. Possible abuse by hammer blows was evaluated by dynamic testing to measure force attenuation in the system. Results ruled out abuse as a factor. Literature revealed that the heat treatable Precedent 71A, or A771-T7 alloy, used for the base casting was very susceptible to stress-corrosion cracking (SCC). Evidence was observed for features indicative of creep-rupture damage on the fracture surface. Evaluation of all of the evidence led to the conclusion that time-dependent crack growth, most likely by both SCC and creep-rupture, plus the effect of bolt hole loading on crack growth could best explain the failure of the gin under a less severe condition than had just occurred earlier in the day.     

A model for Bayesian software reliability analysis

Two problems which are of great interest in relation to software reliability are the prediction of future times to failure and the calculation of the optimal release time. An important assumption in software reliability analysis is that the reliability grows whenever bugs are found and removed. In this paper we present a model for software reliability analysis using the Bayesian statistical approach in order to incorporate in the analysis prior assumptions such as the (decreasing) ordering in the assumed constant failure rates of prescribed intervals. We use as prior model the product of gamma functions for each pair of subsequent interval constant failure rates, considering as the location parameter of the first interval the failure rate of the following interval. In this way we include the failure rate ordering information. Using this approach sequentially, we predict the time to failure for the next failure using the previous information obtained. Using also the relevant predictive distributions obtained, we calculate the optimal release time for two different requirements of interest: (a) the probability of an in‐service failure in a prescribed time t; (b) the cost associated with a single or more failures in a prescribed time t. Finally a numerical example is presented. Copyright © 2000 John Wiley & Sons, Ltd.     

机电装备的失效分析、安全评定和无损检测

从认识论的高度阐明失效、失效分析和预防在人类科学技术发展中的属性、地位和作用。失效分析和预防具有多学科交叉综合的属性,它的发展依赖于应用学科、应用基础学科、甚至于基础学科的发展,但又对它们的发展起重要反转作用和影响。因此,它是科学技术第一生产力中最积极、最活跃的因素之一。从方法论的角度进一步叙述了失效分析与失效预防之间的辩证关系。失效分析是一种事后的逆向思维过程,它是从异常现象（结果）到因素（模式、原因和机理）的反向科技探索,而失效预防（安全评定）则是从因素到结果的一种事先的正向思维过程。逆向思维与正向思维协同并用,事后分析转化为事先分析,构成科学技术研究活动和科技发展的全过程,两者不可偏废。综述了失效分析和失效预防（安全评定）的主要内容、技术、方法和它们的发展趋势,并提出它们与无损检测技术之间的关系。     

Failure analysis of a high-speed pinion shaft

The failure of a high-speed pinion shaft from a marine diesel engine was investigated. The shaft, which had been in service for more than 30 years, failed shortly after a service operation in which the bearings were replaced. Examination of the shaft revealed cyclic fatigue as the failure mechanism, with a substantial distribution of nonmetallic inclusions near the fracture initiation site. Fracture mechanics analysis indicated that the inclusions would be unlikely to have served as failure initiation sites if only stresses acting on the shaft were induced by normal service loads. Further examination of the bearing elements revealed an abnormal wear pattern, consistent with the application of elevated bending loads to the shaft after bearing replacement. The root cause of failure was determined to be an increase in service stresses after bearing replacement along with the presence of significant nonmetallic inclusions in the pinion shaft.     

Failure analysis of brass bolt from mausoleum

Brass is usually considered to be a good candidate material for use in a nonaggressive corrosion environment. Brass 260 was used in a rural environment (at a mausoleum) as fixturing hardware that holds etched marble slabs that cover the interment region. After 12 years of service, the bolts began breaking, and the marble slabs crashed to the ground. Failure analysis investigation showed that “seasonal cracking” occurred due to interaction of the bolt with moisture and fertilizer. The company that designed the mausoleum hardware believed that the bolt manufacturer was at fault. However, the only specification given to the bolt manufacturer indicated alloy and dimensions. The bolts were replaced at considerable cost, proving once again that even a seemingly simple component can prove to be costly if not designed by the proper engineer.     

基于B/S模式的弹药失效诊断评估系统研究

为了提高通用弹药产品可靠性评估的效率,实现产品失效及可靠性的系统化辅助分析评估,对通用弹药产品的失效过程进行研究,总结出产品的一般失效分析过程、失效诊断方法及弹药失效分析数据字典.在辅助分析系统中,提供了失效分析、可靠性评估、FMECA等模块.应用Java、JSP等语言,在B/S模式下进行设计开发,实现了对产品失效的过程分析及产品可靠性评估.优化可靠性统计分析的数学模型,改进评估参量算法,使评估工作效率提高30%以上,参数精度达到小数点后8位.     

空间斯特林制冷机失效分析

针对空间用的"牛津型"斯特林制冷机的结构特点,对其早期失效模式和正常失效模式等主要失效模式进行了较深入分析,提出了改进措施.通过结构设计、工艺等改进,可以消除早期失效模式、延长正常失效的时间.