Microprocessor and LSI Microcircuit Reliability-Prediction Model

This paper discusses the development of an improved failure-rate prediction method which can be used to assess the reliability of complex and new-technology microcircuits, especially memories, microprocessors, and their support devices. The prediction models are similar to those presented in MIL-HDBK-217C with several modifications to reflect the variation of reliability sensitive parameters and to discriminate against the device design and usage attributes which contribute to known failure mechanisms. A comparison of the failure rate predictions calculated using MIL-HDBK-217C and the actual failure rates for LSI random logic and memory devices did not indicate a reasonable correlation. An analysis of the 217C models revealed that the lack of correlation was attributable to the generic consolidation of model parameters, which ultimately reduced model sensitivity to several critical reliability factors. The model accuracy was greatly improved, without substantially increasing model complexity, by separating some generic parameters into sets of more detailed parameters. The major model revisions included: ? Complexity factors oriented toward major device function and technology categories ? Development of temperature factors for each device technology, in both hermetic and nonhermetic packages ? Introduction of an additive package failure-rate factor based upon package type and number of functional pins ? Introduction of a voltage derating stress factor for CMOS devices with maximum recommended operating supply voltage greater than 12 volts ? Introduction of a ROM and PROM programming technique factor to reflect the influence of the programming mechanism used in these devices.     

A critique of Mil-Hdbk-217E reliability prediction methods

Some limitations on the use of Mil-Hdbk-217E models within the design process are discussed. Reliability was predicted for three printed wiring boards representative of those used for avionic applications in order to evaluate the inherent variability. Parts count and parts stress analyses were conducted in three environments using Mil-Hdbk-217E models. In addition, parts stress analyses were conducted at various temperatures, assuming that components were thermally isolated and the thermal interactions resulted from the characteristics of the cooling system. The results suggest that reliability can be predicted only when the layout of the components and exact thermal mapping are known. In practice this is not acceptable, since some measure of reliability prediction is necessary in determining electrical, thermal, and mechanical design tradeoffs early in the design process     

A case study of C.mmp, Cm*, and C.vmp: Part II—Predicting and calibrating reliability of multiprocessor systems

This paper focuses on measurement and modeling of hard failures in multiprocessors. The failure rate predictions of the Military Standardization Handbook 217B (MIL 217B) are compared with semiconductor chip vendor data and data from Carnegie-Mellon University's multiprocessor systems. Based on these comparisons a modified MIL 217B model is proposed. The modified model is employed to calculate module failure rates for the three multiprocessors designed, implemented, and currently operating at CMU. Hard failure reliability models for these three systems are presented. These models use the calculated module failure rates as a basis for a consistent comparison of the three systems.     

Improved and accurate physics-of-failure (PoF) methodology for qualification and lifetime assessment of electronic systems

Assessing electronic systems' reliability using prediction handbooks (e.g. MIL-HDBK-217) can lead to wrong reliability predictions due to the assumption of a constant failure rate and the inaccuracy of the proposed semi-empirical models. Despite different initiatives since the last version of the most popular handbook MIL-HDBK-217 (1995) no fundamental improvement was realised that makes use of non-constant failure rate statistics – mandatory to model wear-out - and first principles based Physics-of-Failure modelling.Obtaining detailed PoF models requires physical insights and an extended experimental campaign to establish material properties. This is impossible to perform for a specific application.In this paper, we propose a methodology that combines the two approaches to get an improved reliability estimation and allows for a gradual improvement from a prediction handbook based approach to a PoF based reliability assessment. This methodology has been successfully validated on an industrial case.     

Reliability prediction models to support conceptual design

During the early stages of conceptual design, the ability to predict reliability is very limited. Without a prototype to test in a lab environment or without field data, component failure rates and system reliability performance are usually unknown. A popular method for early reliability prediction is to develop a computer model for the system. However, most of these models are extremely specific to an individual system or industry. This paper presents three general procedures (using both simulation and analytic solution techniques) for predicting system reliability and average mission cost. The procedures consider both known and unknown failure rates and component-level and subsystem-level analyzes. The estimates are based on the number of series subsystems and redundant (active or stand-by) components for each subsystem. The result is a set of approaches that engineers can use to predict system reliability early in the system-design process. Software was developed (and is discussed in this paper) that facilitates the application of the simulation-based techniques. For the specific type of system and mission addressed in this paper, the analytic approach is superior to the simulation-based prediction models. However, all three approaches are presented for two reasons: (1) to convey the development process involved with building these prediction tools; and (2) the simulation-based approaches are of greater value as the research is extended to consider more complex systems and scenarios     

The use of MIL-HDBK-217 with the SCC EEE components

Data for reliability prediction are typically taken from MIL-HDBK-217 which lists failure rates against Military specifications.The practice however for parts procurement for ESA space systems relies amply on the SCC specifications. Test methods, qualification and screening programmes are thus peculiar to this system which utilises a blend of IEC and MIL test methods.Although many similarity exists between the Mil system and the SCC system, a direct correspondence between quality classes and testing levels (i.e. SCC levels B and C) from one system to another cannot in general be claimed. The use of MIL-HDBK-217 data under acquisition systems other than the MIL requires thus some reflection. Additionally, the use of MIL-HDBK-217 for reliability predictions on components with designation other than MIL obliges to adopt the quality factor corresponding to the class “lower” (i.e. non-MIL Spec).This implies in general penalising results for components qualified to standard classes like the SCCs, or components upgraded to military screening levels.Being MIL-217 undoubtedly the best source of failure rate information it can be used as reference for deriving quality factors (or more exactly quality factors scale coefficients to be used with parts procured to other systems.In the following the analysis of comparison of the EEE parts specifications is discussed. The scope of the analysis has been essentially to derive scale factors to use with the failure rates of MIL-hdbk 217 when the parts acquisition programme responds to the SCC requirements.     

Microelectronic System Reliability Prediction

The paper reviews the US MIL-HDBK-217 (MH-217) method of part stress-analysis failure-rate prediction for microelectronic systems and investigates the extent to which the MH-217 failure-rate formula is compatible with the physics of actual failure modes. A new formula is proposed which takes account separately of the reliability of the microelectronic devices in a system and of the system-level determinants of reliability. It is simpler than the current MH-217 formula, and more useful. It enables the system level aspects such as reliability program activities to be taken into account in the prediction, and allows better correlation to be made between part test and system test data. An example applies the new formula to a typical microelectronic system. By considering separately the failure physics of parts and the system level determinants, reliability prediction can be made a more useful tool both for part stress analysis and for reliability program management. The model would enable better correlations to be made between part and system test results. More work needs to be done to refine and validate the parameters. For high-reliability programs with closely controlled maintenance or with no maintenance, the use of a decreasing failure rate model for part failures should be considered. The failure rate formulae for other electronic parts used in microelectronic systems would also need to be reviewed, but apart from removal of the environmental factor and reduction in the failure rate values proportionate to that proposed for microelectronic parts, no changes should be necessary.     

美国军用手册217F与国家军用标准299B比较研究

文章分析美国军用手册217F相对国家军用标准299B在可靠性预计总体论述上的差异,指出可靠性预计的作用和局限性,具体比较可靠性预计模型,并探讨在军用标准中引入开放系统思想。     

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。     

A Method for Predicting VLSI-Device Reliability Using Series Models for Failure Mechanisms

A series model is used to determine the intrinsic reliability of an integrated circuit. An analysis of electromigration in the interconnect system of a 200 000 transistor VLSI device, shows that the failure rate exceeds 10 FIT (failures per 109 hours) within 2 years when operating at a temperature of 800 C. These results indicate the importance of fundamental wear-out mechanisms as factors in VLSI device reliability, under usual operating conditions. The analysis, as applied to a generic chip, predicts that temperature, burn-in, and complexity all adversely affect the device reliability. The paper demonstrates the feasibility of using the information available in the design database together with specific failure models to predict (during the design phase) the reliability of an IC. These techniques can be used to develop a CAD tool for reliability prediction.     

Comparison and evaluation of newest failure rate prediction models: FIDES and RIAC 217Plus

The failure rate of an example avionics control unit with approximately 7000 electronic components is calculated with the latest state-of-the-art prediction models FIDES Guide 2004 and RIAC-Handbook-217Plus (2006). To allow comparison of the component prediction models a standard civil avionics profile was defined and used for both calculations. Results are compared supported by analysis of the influence of component and application specific parameters such as temperature, temperature cycles, humidity, and vibration. In addition predicted failure rates are compared to field data that has been collected for this unit during 15 years.     

Estimation of system reliability using a "non-constant failurerate" model

One of the most controversial techniques in the field of reliability is reliability-prediction methods based on component constant-failure-rate data for the estimation of system failure rates. This paper investigates a new reliability-estimation method that does not depend upon constant failure rates. Many boards were selected from the Loughborough University field-reliability database, and their reliability was estimated using failure-intensity based methods and then compared with the actual failure intensity observed in the field. The predicted failure-intensity closely agrees with the observed value for the majority of a system operating lifetimes. The general failure intensity method lends itself very easily to system-reliability prediction. It appears to give an estimate of the system-reliability throughout the operating lifetime of the equipment and does not make assumptions, such as constant failure rate, which can be detrimental to the validity of the estimate. The predictions seem, on present evidence, to track the observed behavior well, given the uncertainties that are evident in the field. The failure intensity method should be investigated further to see if it is feasible to estimate the system reliability throughout its lifetime and hence provide a more realistic picture of the way in which electronic systems behave in the field     

A new reliability prediction model for telecommunication hardware

An analysis of measured field failure rates of printed circuit boards has been performed. The “part count” method currently used for reliability predictions was evaluated. A new model for electronic reliability prediction has been proposed. It uses statistics from board and system tests performed at the production plant and the number of conductive layers on the board. The report shows that there is a correlation between production test statistics and field performance, for high-volume boards. The proposed model shows that a high production test yield indicates high field reliability. This means that if actual production test results are poor, actions can be taken to improve reliability before numerous boards are delivered to customers.     

Results of a pilot-survey about reliability-task effectiveness

Seventy electronic manufacturers (with at least 100 employees) in the northwest USA were contacted in 1990 September with the intent of measuring their perception of reliability-task effectiveness. There were 17 competent respondents; they rated the effectiveness of 26 reliability tasks; the highest rating (from top to third) were for development testing, failure reporting and corrective action, durability analysis, and durability testing. Interestingly, some US Mil-Std-785 reliability tools such as reliability qualification testing, sneak-circuit analysis, and reliability prediction received the lowest ratings. Many respondents thought reliability prediction was ineffective for improving product reliability, although the majority of respondents do use Mil-Hdbk-217. Since the response rate was so low, it is difficult to draw firm conclusions. Both a larger sample size and a virtual 100% response rate are needed for future studies. Other question-areas, especially about corporate culture, are desirable     

Logistic Simulation - A Credible Tool for Decision Makers?

Logistic simulation and sensitivity analyses can prove useful in management reviews of major weapon system acquistion programs. The F/A-18 analyses were instrumental in quantifying the importance of achieving projected field reliability levels, the adequacy of supply support funding, and the importance of test equipment capacity in achieving aircraft readiness objectives. Logistic simulation inputs and assumptions need to be subjected to critical examination in each application. In the case reviewed, it was found that the commonly used assumption that mean failure rates are constant values, known with certainty, introduced significant errors in prediction of operational readiness and sensitivity analysis results. The variability of mean demand has potentially far reaching implications concerning future support planning but further work is required to fully understand, characterize, model, and develop logistic support approaches that accommodate the variability. Logistic simulation has the potential to become an accepted support planning and analysis tool that will meet the new DoD management demands to quantitatively link system design and support decisions to operational readiness objectives. Further understanding of the ``real world,' and incorporation of this understanding in input data and modeling techniques are required if the full potential of this support planning tool is to be realized.     

A survey of reliability-prediction procedures for microelectronicdevices

The author reviews six current reliability prediction procedures for microelectronic devices. The device models are described and the parameters and parameter values used to calculate device failure rates are examined. The procedures are illustrated by using them to calculate the predicted failure rate for a 64 K DRAM; the resulting failure rates are compared under a variety of assumptions. The models used in the procedures are similar in form, but they give very different predicted failure rates under similar operating and environmental conditions, and they show different sensitivities to changes in conditions affecting the failure rates     

Stochastic analysis of a general standby system with constant human error and arbitrary system repair rates

This paper presents a mathematical model for performing reliability and availability analyses of a general standby system with constant human error and common-cause failure rates. In addition, system repair times are assumed arbitrarily distributed. Markov and supplementary variable techniques were used to develop equations for the model. The method of linear ordinary differential equation is developed to obtain the general expressions of the steady state availability. The Laplace transform technique was used to obtain the system time-dependent availability, reliability and mean time to failure expressions.     

Study on the Validity of Electronic Parts Stress Models

By using data on the failure rates of electronic components collected by a European Bank, we try to form an idea on the validity of the various models (Bazovsky model, MIL HDBK-217A standard model, exponential model, RADC TR-67 models) that represent the variations of the failure rate with respect to the thermal and electrical stresses. Two different approaches have been programmed on a computer: 1) conventional, using the linear regression analysis 2) more modern using the Fletcher-Powell method or methods derived from it (Fletcher-Reeves or Davidon). The results are given for four types of components. The models studied reflect, more or less accurately, what happens in real life. We define and give a value to a criterion, allowing the model to be chosen closest to reality. This paper, apart from its practical interest on the validity of currently accepted models and its theoretical interest on the use of methods for seeking extremes, shows how the computer can assist the reliability engineer with the filing of data, the statistical processing of these data, etc., right up to the automatic tracing of networks of curves.     

Automatic Electronic Component Failure-Rate Prediction with MIL-HDBK-217B

This paper describes a computer program and data base with automatic part failure-rate estimation according to MIL-HDBK-217B. The user supplies only a part list and application-dependent information. The program retrieves the part characteristics from the database, and computes the failure rate and power consumption for each part. Program options sum the failure rate and power requirements (dissipation) for the entire part list and perform trade-off analyses for different operating conditions or screening levels.     

国外最新可靠性预计方法综述

在分析研究国外近几年发布的典型电子元器件及系统可靠性预计模型及数据手册——RIAC于2006年发布的217Plus以及IEC-TR-62380（2004年发布）的基础上,系统地介绍了两本预计手册中电子元器件和系统的可靠性预计模型和方法。