国内印制电路板产品失效现状与改进

对本实验室2019—2022年承接的国内印制电路板（PCB）制造商及相关用户委托的失效案例开展统计，发现PCB自身质量异常已成为引起印制电路板组装（PCBA）失效的最主要问题。进一步对PCB总体失效模式与失效原因分布、不同排名PCB企业失效案例数量分布、军用PCB失效模式分布及民用PCB失效模式分布等进行分析，发现导通失效、可焊性不良、分层爆板和绝缘失效是PCB行业最为常见的4大失效模式。生产制程缺陷是造成PCB失效的最主要原因（69%）；内资排前100名企业失效案例数量合计占比为48%，失效模式分布与整个PCB行业一致；军用PCB与民用PCB失效模式分布存在差异，军用PCB和民用PCB第一大失效模式分别为导通失效（49%）和可焊性不良（25%）。最后结合行业的失效问题现状，提出了改进建议。     

PCB失效分析技术与典型案例

由于PCB高密度的发展趋势以及无铅与无卤的环保要求,越来越多的PCB出现了润湿不良、爆板、分层、CAF等等各种失效问题。本文首先介绍针对PCB在使用过程中的这些失效的分析技术,包括扫描电镜与能谱、光电子能谱、切片、热分析以及傅立叶红外光谱分析等。然后结合PCB的典型失效分析案例,介绍这些分析技术在实际案例中的应用。PCB失效机理与原因的获得将有利于将来对PCB的质量控制,从而避免类似问题的再度发生。     

沉锡PCB焊接失效分析方法介绍

根据多例沉锡焊接失效案例,对导致沉锡PCB焊接失效的原因进行了分析,并详细的介绍了多种沉锡PCB焊接失效分析方法。     

液晶电视CAF失效实例分析和预防

电子产品大量使用印制电路板(PCB),在潮湿环境下使用时易产生导电性阳极丝失效,影响电子产品可靠性。通过对多起液晶电视机电路板CAF失效实例的测试、分析,总结出导电性阳极丝失效(即CAF失效)首先发生在具有固定直流偏压的高阻抗电路中,同时分析了CAF失效高发的现象与盐雾之间的关联性,通过对比说明了PCB设计、装配工艺、PCB选材对CAF预防的不同效果,指出了选择抗CAF的PCB材料的重要性,并给出了两种在线监测电路的设计方案。     

PCB孔铜断裂失效分析探讨

针对PCB在SMT后出现的通孔开路问题,本文结合孔铜断裂失效案例,通过CT、金相切片、SEM及热分析等分析手段来进行论证,分析PCB孔铜断裂的失效机理,并给出了预防控制建议.     

PCB&PCBA-PTH失效原因分析

介绍了一个典型的印刷电路板(PCB)失效原因分析的案例。该PCB经过波峰焊后因油墨塞孔导致孔壁断裂而失效。分析结果表明:孔壁镀层中存在的柱状结晶及镀层空洞削弱了孔铜镀层的延展性及抗拉强度,这是导致在随后的焊接工艺过程中承受不住相对较大的膨胀应力而发生孔铜镀层断裂失效的主要原因;PCB本身相对较大的膨胀系数也是导致孔铜断裂的原因之一。     

黑盘与化镍金PCB焊点失效模式

文章通过多个化镍金PCB焊接失效案例,探讨了黑盘与化镍金PCB焊点失效模式之间的关系。     

无铅热风整平PCB焊接不良失效分析

采用切片和SEM&EDS的分析方法对无铅热风整平PCB焊接不良的现象进行了分析。分析结果表明,PCB焊盘表面的锡层完全合金化,降低了焊盘的可焊性。造成该失效的原因在于PCB的热风整平工艺不良。     

PBGA焊接开裂失效原因分析及改善

由于PBGA组件点位于四件与PCB之间,焊点的检查和检修成本很高,控制PCB组件焊接失效显得尤为重要。文章通过对焊接失效的焊盘镍层、金层结构进行了SEM、X-RAY分析导致焊接失效产生的主要原因,并针对此现象进行控制与改善。     

发动机用PCB的失效分析研究

PCB广泛用于集成电路生产业的各个方面,汽车发动机用PCB要求较高的可靠性。面对热循环失效的汽车动力系统的构件,不要急于取下所有元件,应先对失效点表面进行外观检查和EDX分析,再进行带元件的切片分析和SEM分析,确认各个点的IMC是否正常,以找出真正的失效原因。     

Shared risk link group failure restoration with in-band approximate failure localization

This paper proposes a novel failure recovery framework for multi-link shared risk link group (SRLG) failures in optical mesh networks, called failure presumed protection (FPP). The proposed framework is characterized by a failure dependent protection (FDP) mechanism where the optical layer in-band failure identification and restoration tasks for route selection are jointly considered. FPP employs in-band monitoring at each node to obtain on-off status of any working lightpath in case the lightpath is terminated at (or traversing through) the node. Since the locally available failure status at a node may not be sufficient for unambiguous failure localization, the proposed framework reroutes the interrupted lightpaths in such a way that all the suspicious links which do not have 100% restorability under any SRLG failure are kept away. We claim that this is the first study on FDP that considers both failure localization and FDP survivable routing. Extensive simulations are conducted to examine the proposed FPP method under various survivable routing architectures and implementations. The results are further compared with a large number of previously reported counterparts. We will show that the FPP framework can overcome the topological limitation which is critical to the conventional failure independent protection method (e.g., shared path protection). In addition, it can be served as a viable solution for FDP survivable routing where failure localization is considered.     

Modeling bimodal electromigration failure distributions

One of the major tasks in reliability methodology is the correct modeling of electromigration failure distributions. Usually the failures within a sample of test devices are caused by a single physical failure mechanism and the resulting failure distribution can be tight-fitted by a single log-normal distribution. However, it is possible that several failure mechanisms are active within the sample or even one specimen implying multimodal failure distributions. In this paper bimodal log-normal distributions will be discussed, which show two distinct branches as a consequence of two failure mechanisms. In order to describe these failure distributions we use two models – the superposition model and the weak-link model. Both are composed of two log-normal distributions and consider different failure scenarios. We show that they are special cases of one general bimodal model. For each model, coinciding experimental data sets will be presented, which were observed on different via-line structures. The physical failure analysis confirms the model assumptions and supports the bimodal distribution concept.     

Material failure mechanisms and damage models

This work introduces a tutorial series on material failure mechanisms and damage models to familiarize nonspecialists with the fundamentals of failure mechanisms in engineering assemblies. Since failure is a complicated concept, four simple conceptual models for failure are discussed: stress-strength, damage-endurance, challenge-response, and tolerance-requirement. The specific failure mechanisms depend on material or structural defects, damage induced during manufacture and assembly, and on conditions during storage and field use. Conditions that affect the state of an item are broadly termed stresses (loads), e.g., mechanical stress and strain, electrical current and voltage, temperature, humidity, chemical environment, and radiation. The effects of stresses are influenced by geometry, constitutive and damage properties of the materials, manufacturing parameters, and the application environment     

ESD failure analysis methodology

This paper reviews failure analysis methods and discusses the merits and pitfalls associated with some of the more common techniques as they relate to electrostatic discharge (ESD). Although advanced methods such as the focused ion beam will be discussed, the importance of more traditional methods such as liquid crystal, emission microscopy, passive voltage contrast and mechanical polishing will be emphasized. Case histories are based on ESD related failure analysis; however, many of the references cover general failure analysis methodology.     

The causes of project failure

A study was conducted of 97 projects identified as failures by the projects' managers or parent organizations. Using the project implementation profile, a set of managerially controllable factors is identified as associated with project failure. The factors differed according to three contingency variables: the precise way in which failure was defined; the type of project, and the stage of the project in its life cycle. Implications for project management and for future research on failed projects are discussed. The results demonstrated empirical justification for a multidimensional construct of project failure, encompassing both internal efficiency and external effectiveness aspects. The fact that the critical factors associated with failure depended on the way in which failure is defined suggests that it is necessary to know considerably more about how project managers define failure (and success) and, indeed how the parent organization makes judgments on the matter     

Bibliography of literature on failure data

This paper briefly discusses the topic of failure data. A list of selected references on failure data and related areas is presented. Additional sources of obtaining failure data are also listed.     

电视背光LED灯失效机理和分析方法

基于直下式LED发光电视,从封装失效、芯片失效、热应力失效、电应力失效等方面分析了电视背光系统中发光二极管(LED)器件的失效机理和改进措施,同步提出安全性失效和可靠性失效的理论概念,并对电视整机系统的LED温升控制和LED驱动电流控制方面进行了分析,提出了实用的LED失效分析流程.     

Combining failure rate data from various sources

In this paper a method for pooling failure rate data obtained from different sources is discussed. The pooling is done by the help of a Bayes approach supposing the failure rates follow a common Gamma distribution. We obtain Bayes estimators of the failure rate and its inverse, the mean life time. An asymmetric loss function is used for the Bayes estimator. HPD confidence intervals are obtained for the failure rate.     

ESD tester parasitics and stress conditions and their impact on device failure levels and failure mechanisms

A comparative study of Human Body and Machine Model (HBM/MM) testers is performed using a very large sample size for statistical significance. Failure mechanisms and types of damage are categorized with the use of photoemission spectrum analysis. Tester parasitic values are extracted for each machine, and a correlation is established to failure thresholds, distributions and failure mechanisms.     

Investigation of Arrhenius acceleration factor for integrated circuit early life failure region with several failure mechanisms

Use of the Arrhenius equation for analysis of burn-in and life test data has been called into question in recent years. Validity of the Arrhenius activation energy is asserted to be restricted to only one failure mechanism. Therefore, if multiple failure mechanisms apply to an integrated circuit type, the temperature acceleration factor must be complex. In this study a model is constructed using the Weibull distribution for the failure rate applicable when there are multiple failure mechanisms. In this model a different Arrhenius activation energy corresponds to each failure mechanism. It is shown that under conditions expected to be valid for most integrated circuits, an empirical effective Arrhenius activation energy can be computed that is valid for life test data taken under typical conditions to better than 10%. This provides some justification for the continued usage of a simple Arrhenius equation as an empirical model to analyze life test data.