纠正一个流传了30年的错误——失效率定义

针对失效率的3个主要特征(平均失效率、瞬时失效率和残存量比值)进行了论述,破除多年来在中文书籍和公开文章中被多次引用的一个错误的定义,以期在可靠性基础理论的学习中能够正确地理解失效率参数的意义。     

半导体器件失效率的讨论

1.失效率定义 失效率是表征半导体器件可靠性的最重要指标之一。它以字母λ(t)表示,它表示半导体器件工作到时刻t的条件下,单位时间内的失效概率。失效率有三种表示单位:一是每小时10的负几次方,例如1×10~(-6)/小时,国内常以此单位表示;二是每小时的百分数(％/小时)或每千小时的百分数(％/千小时);三是Fit(菲特),1Fit=1×10~(-9)/小时,即10亿个元器件每小时内只允许1个半导体器件失效,国     

微波真空电子器件磁控管的失效率模型

以磁控管现场使用数据和失效模式为基础,根据真空电子器件失效率或平均寿命等可靠性指标的考核方法,对新版（ＧＪＢ２９９Ｂ）电子设备可靠性预计手册中的失效率模型与旧版（ＧＪＢ２９９Ａ）进行了验证对比。结果表明,新版比旧版更接近实际,而且其预计精度也有明显提高,新版所建立的失效率数学模型可以满足工程的实际要求。     

IC失效率的预测研究

前几篇论文中,曾对我厂多年来生产的IC进行了长达七千多小时的可靠性试验。经数据处理得出了重要的可靠性参数失效率λ、平均寿命等。可以看出我厂生产的IC可靠性已达到了较高水平。这里,再对若干电路进行了失效率的预测研究,得出的失效率λ值与试验数据处理得出的失效率λ值相比较,均在同一数量级。证明此方法可省人力、物力和财力,既能提供可靠信息,又可为厂增加经济效益。     

一种新的电子元器件突然失效率估算方法

在电子元器件可靠性特性的基础上,引入负荷系数的概念;同时考虑多种负荷的作用,建立了电子元器件突然失效率的估算模型;通过该模型所得的元器件突然失效率数据对电子设备及系统可靠性的计算更具有实际意义。     

晶体管非工作期失效率预计

本文根据晶体管非工作期可靠性统计数据建立了我国晶体管非工作期失效率预计模型，经验证，预计失效率与现场失效率相吻合．通过预计模型可预计晶体管在各类环境下的非工作期失效率，尤其给出了我国晶体管普通库房贮存失效率和贮存有效期．     

美国半导体器件的失效率及其计算方法

本文用美国哈里斯半导体器件公司的实例数据介绍了如何采用新概念计算半导体失效率的方法，并收集了近年来发表的部分半导体器件失效率的数据（其中早期失效率数据是利用６０％置信度计算出来的，长期失效率是利用激活能和６０％置信度计算出来的），同时还分析了自１９９５年以来美国半导体失效率的变化趋势或可靠性改进的情况，以供参考。     

行波管可靠性失效率模型的研究

本文以行波管现场使用数据和失效模式为基础，根据可靠性理论对真空电子器件失效率或平均寿命考核可靠性指标的方法，参照美国军标ＭＩＬ－ＨＤＢＫ－２１７Ｅ，Ｆ，结合我国具体实际，对行波管失效率的数学模型，采用数理统计回归分析后，定量得出我国行波管可靠性的水平，并用现场数据对失效率模型进行验证，提出我国行波管总体可靠性水平与美国之间的差距。     

行波管可靠性失效率模型的研究

本文以行波管现场使用数据和失效模式为基础，根据可靠性理论对真空电子器件失效率或平均寿命考核可靠性指标的方法，参照美国军标ＭＩＬ－ＨＤＢＫ－２１７Ｅ，Ｆ，结合我国具体实际，对行波管失效率的数学模型，采用数理统计回归分析后，定一得出我国行波管可靠性的水平，并用现场数据对失效模型进行验证，提出我国行波管总体可靠性水平与美国之间的差距。     

电子元器件的失效率

电子元器件的可靠性是人们最关心的问题,因为它直接影响整机的可靠性。表征电子元器件可靠性的最重要指标是电子元器件的失效率。电子元器件的失效率入(t)表示电子元器件工作到t时刻的条件下,单位时间内的失效概率。失效率有三     

Failure Rate/MTBF

Failure rate is the most commonly used term in reliability and related engineering interests, yet it is still not well understood by perhaps the majority of those using it. Indeed, more than one reliability treatise wrongly defines failure rate as a conditional probability density, i.e., wrong by the accepted criterion of what constitutes any probability density. The fact that these two concepts are by no means the same is clarified and made more precise. Mean time between failures and dimensionality are also briefly considered.     

Estimation of Periodically Changing Failure Rate

This paper considers two life testing procedures (progressively censored samples and Bartholomew's experiment) under the assumption that the life of an item follows the exponential distribution. The failure rates are different under n different conditions of usage of the item at regular intervals of time. The maximum likelihood estimates of the n failure rates have been derived along with their asymptotic variances for both types of data (when failure times are recorded and when only the number of items failing in each interval are recorded). A numerical example illustrates the type of data and relevant calculations for the experiment involving progressively censored samples.     

Failure Rate Calculations Using a Programmable Calculator

This paper describes a TI 59 program which calculates the acceleration factor between any two temperatures, equivalent unit-hours at one temperature based on actual test hours at a second temperature, the x2 approximation at any of seven s-confidence levels, and the s-confidence limit failure rate estimate in both %/1000 hours and FITs. The program allows numerous entries of separate sample results which the calculator stores and then performs a single failure rate estimate calculation. Required inputs are test temperature, temperature at which the failure rate estimate is desired, the activation energy, and the number of failures during the test. The equations for the program are reviewed and tables are included showing all labels and memories used, and the 355 program steps listing.     

Local Polynomial Fitting in Failure Rate Estimation

The failure rate function is one of the most important functions in reliability analysis as it addresses concepts such as scheduling, maintenance, improved system design, cost analysis, etc. Kernel-based estimation of the failure rate function imposes minimal assumptions on the data, and thus offers large flexibility. Therefore, it is very helpful in reliability analysis where the shape of the failure function is a primary target. However, standard kernel estimates are biased more than usual in the endpoints. Motivated by the advantages that the local linear fitting method provides for estimation of densities near the boundary, we employ the technique to the failure rate setting. We show that it produces estimators that have the same amount of boundary bias as in areas outside the boundary. The mean square error properties of the method are demonstrated, and a practically useful procedure for automatic smoothing parameter selection is developed, and studied both theoretically, and by simulations. The result is displayed graphically by distributional, and real life data.     

Bayes Nonparametric Estimation of Time-dependent Failure Rate

This paper discusses Bayes nonparametric estimation of time-dependent failure rates. A point and an interval estimate of the quantiles of the failure process are given for both complete and censored samples. The prior degree-of-belief about the failure rate is expressed in the form of a hypothetical sample. A numerical example is discussed.     

Evaluation of Conditional Failure Density from Hazard Rate

Further to the recent discussion regarding the concepts of hazard rate and conditional failure density, it is shown that the latter may be expressed in terms of the former. Moreover, six functions, namely, failure time distribution function, failure time density, reliability function, hazard rate, conditional failure distribution, and conditional failure density, are shown to be equivalent to the extent that if one of them is known, the other five are completely determined. The results are summarized in a table.     

On-Line Reliability Prediction via Dynamic Failure Rate Model

This paper presents a new dynamic reliability approach which is able to take into account the various operating conditions under which the considered system has evolved (past and present). To this end, we propose a differential model of failure rate, combined with the state space representation of the process, as well as a parameterization procedure. A numerical example shows the practical applicability of the proposed approach.      

多芯片组件MCM的失效率预计研究

通过对多芯片组件(MCM)的结构、失效模式和机理的分析,提出了适合我国生产实际的MCM失效率预计模型.采用加速寿命试验和点估计法获得了膜电阻的基本失效率λRT和布线与工艺基本失效率λC;并采用极限应力对比试验获得了层间系数πcp.     

多失效机理下基于FIDES的MEMS失效率预计研究

针对MEMS在工艺和结构上的新特点以及当前国内外尚未形成与MEMS相关的失效率预计模型的研究现状,基于失效物理方法和现有FIDES标准,提出了一种MEMS失效率预计方法。在MEMS工艺影响分析基础上,结合实验数据和失效物理方法,提出了MEMS在多失效机理下的总体失效分布函数计算方法;之后,基于FIDES基本失效率预计模型,提出了MEMS的失效率预计模型及其适用的参数取值方法;最后,完成了某型MEMS高g值微加速度计的失效率预计案例。结果表明,预计模型充分考虑了MEMS在工艺和结构上的新特点以及多失效机理的共同作用,可有效解决现有标准手册不能准确反映制造工艺发展现状和手册中失效数据不适用的问题。