塑封器件失效机理及其快速评估技术研究

针对影响塑封器件可靠性的五种失效机理,即腐蚀失效、爆米花效应、低温/温冲失效、闩锁以及工艺缺陷等方面进行分析和讨论,并提出利用高温潮热和温度冲击试验对塑封器件的可靠性进行评估.还介绍了美国航天局Goddard空间飞行中心提出的对塑封器件进行高可靠性筛选的方案.     

高可靠领域中应用塑封器件的有效评价

介绍了塑封器件的优缺点以及发展情况,针对塑封半导体器件本身在材料、结构和工艺等方面的特点,对塑封器件的失效模式和在试验中暴露的问题进行探讨,针对塑封器件的温度适应性、密封性、工艺控制及使用长期可靠性方面制定了相应的质量评价方案。半导体塑封器件通过质量评价方案的试验项目,包括筛选试验、可靠性鉴定试验和破坏性物理分析(DPA)三方面的试验,降低了塑封器件在应用中的风险,对我国高可靠领域中对塑封器件的选用具有一定的借鉴意义。     

声学扫描显微镜检查在塑封器件检测中的应用

随着塑封器件在武器系统中的使用越来越广泛,塑封器件在使用中也暴露出了一些问题,如塑封器件易打磨、翻新,内部易进入水汽产生爆米花效应或内部界面分层等。作者总结近几年塑封器件DPA试验中出现的各种失效,重点对塑封器件内部界面分层以及分层产生的原因、危害进行了论述。同时,论述了声学扫描显微镜检查对内部界面分层的辨别、原理及其相关试验标准等,提出了塑封器件在型号产品中的使用建议。     

塑封微电子器件失效机理研究进展

塑封器件在现在的封装产业中具有无可比拟的优势,相关研究引起了人们广泛关注.简要介绍了塑封微电子器件的发展史,以及国内外塑封器件可靠性的研究现状.对塑封器件的主要失效机理研究进展进行深入探讨,如腐蚀、分层、开裂等,提出了几种提高塑封器件可靠性的措施.论述了用于塑封器件质量评估的试验方法,并展望了塑封器件在军工领域的潜在应用前景.     

军用塑封器件失效机理研究和试验流程

由于其结构和材料等因素,侵蚀、"爆米花"效应和易受温度形变是塑封器件常见的失效机理,在其装入整机之前必须经过严格的可靠性评价或筛选以降低风险。推荐了一套优化的塑封器件试验流程,试验评价流程组合包括无损的外目检、X射线检查、声学扫描显微镜检查,以及具有破坏性的DPA、寿命试验和耐潮性项目。该试验评价程序针对主要的失效机理,充分考虑了塑封器件的批质量一致性、高温下的器件寿命和耐潮性,可以作为军用塑封器件的主要评价手段。     

塑封器件的外部目检方法与判据研究

目前,塑封器件由于其在尺寸、重量、成本、可用性和性能,以及工艺和设计方面的先进性,使得其在高可靠性领域中的应用越来越广泛,国内已有相当数量的塑封器件应用于国防领域。但是,其外部目检试验项目所依据的方法与判据仍然沿用气密性封装器件外部目检的方法与判据,已经不能满足日益增多的塑封器件的外部目检筛选要求。结合GJB 548B-2005的方法 2009.1外部目检要求,开展塑封器件外部目检试验方法与判据的研究。     

PMCM器件的失效根因分析

从塑封多芯片组装(PMCM)器件的电性能测试数据出发,根据器件的环境试验过程和MCM的材料结构、芯片性能,得出了某PMCM器件的失效性质与塑封封装材料、工艺相关的结论;同时讨论了一些PMCM失效分析问题。     

塑封器件分层检测不合格原因探讨

在塑封半导体器件内部裂纹、空洞和分层缺陷的检测中,同样的样品不同单位、不同试验人员总会出现一些器件检测结果不一致的情况。为研究导致检测结果不一致的原因,通过对超声扫描检测技术原理和适用判据标准的阐述,对不同设备的比对验证以及对塑封器件材料的吸湿影响试验和分析,探讨了塑封器件分层检测不合格和不一致的原因,为同行业者提供借鉴和参考。     

塑封器件宇航应用的质量保证方法

由于技术进步的需要,航天器不可避免地遇到了选用不到高等级器件、而只能选用商用塑封器件的情况,商用塑封器件的质量保证方法是国内外宇航机构研究的热点问题。在分析商用塑封器件设计、生产特点的基础上,针对其特有的失效模式,给出了商用塑封器件的质量保证方法,为航天器应用商用塑封器件提供借鉴和指导。     

进口工业级塑封器件使用可靠性保证措施研究

针对进口工业级塑封器件本身的材料、结构等特点,列出了塑封器件存在的主要问题,得出了塑封器件在使用前,要进行采购、筛选、评价、DPA分析等工作,从而提高塑封器件应用于军用武器的使用可靠性。     

QFN器件在湿热环境中的界面裂纹分析

因吸潮而引起的界面破裂是塑封电子器件失效的一个重要原因。通过吸潮实验、无铅回流焊环境实验和湿热老化实验研究了QFN塑封器件内部界面裂纹情况。结果表明,未吸潮的器件经历无铅回流焊后很少产生裂纹,吸潮器件在吸潮期间未产生裂纹,但经历无铅回流焊后器件产生裂纹的几率达100%;裂纹在芯片、芯片粘结材料(DA)和塑封材料(EMC)的交界处的破坏程度最大;产生的裂纹的位置和扩展方向与结合材料的特性、结合界面的强度紧密相关。     

湿热环境下吸潮对QFN器件可靠性的影响研究

由吸潮引起的微电子塑封器件失效已经越来越多地引起人们的关注.选用QFN器件作为研究对象,首先进行QFN器件在高温高湿环境下吸潮17 h、50 h、96 h试验;然后利用有限元软件分析和模拟潮湿在QFN器件中的扩散行为,并建立湿气预处理阶段应力计算模型;最后,通过试验与仿真相结合,分析潮湿对封装可靠性的影响.研究表明:微电子塑封器件的潮湿扩散速度与位置有着重要的关系;在高温高湿环境下,微电子器件吸潮产生的湿热应力在模塑封装材料(EMC)、硅芯片(DIE)和芯下材料(DA)的交界处最大;QFN器件在高温高湿环境下吸潮产生的裂纹主要出现在硅芯片与DA材料交界面的边界.     

塑封IC潮敏分级及相应的使用要求

参考JEDEC标准,介绍和讨论塑封IC器件的潮敏问题,如潮敏分级,相应的包装要求,SMT回流焊温度曲线等.对涉及潮敏IC器件的电子组装应用实践中的一些问题提出参考意见.     

Handling of highly-moisture sensitive components-an analysis oflow-humidity containment and baking schedules

Unique component handling issues can arise when an assembly factory uses highly-moisture sensitive surface mount devices (SMDs). This work describes how the distribution of moisture within the molded plastic body of a SMD is an important variable for survivability. JEDEC/IPC moisture level rated packages classified as Levels 4-5a are shown to require additional handling constraints beyond the typical out-of-bag exposure time tracking. Nitrogen or desiccated cabinet containment is shown as a safe and effective means for long-term storage provided the effects of prior out-of-bag exposure conditions are taken into account. Moisture diffusion analyzes coupled with experimental verification studies show that time in storage is as important a variable as floor-life exposure for highly-moisture sensitive devices. Improvements in floor-life survivability can be obtained by a handling procedure that includes cyclic storage in low humidity containment. SMDs that have exceeded their floor-life limits are analyzed for proper baking schedules. Optimized baking schedules can be adopted depending on a knowledge of the exposure conditions and the moisture sensitivity level of the device     

湿热环境下EMC尺寸对PBGA器件可靠性的影响

塑料封装器件由于湿热导致层间开裂是影响器件可靠性的关键问题之一。采用有限元分析软件模拟和计算了不同的模塑封材料(EMC)尺寸的PBGA(塑封焊球陈列)器件在358.15K、RH60%条件下吸潮168h和398.15K、RH0环境下干燥50h后器件内部的应力对界面可靠性的影响。结果表明,在吸潮情况下,EMC厚度为0.85mm的器件的界面可靠性最低,最大湿应力为0.528MPa;在干燥阶段,EMC厚度为1.25mm的器件的界面可靠性最高,最大湿应力仅为0.124MPa。     

Qualification of plastic encapsulated microcircuits (PEM) for avionicsBased on ``Plastic Encapsulated Microcircuits (PEM) Qualification Testing'''', by J. A. Scalise, which appeared in the Proceedings of the 46th Electronic Components and Technology Conference, Orlando, FL, U.S.A., 28–31 May 1996, pp. 392–397. © 1996 IEEE.

Microcircuit package qualification testing is used to establish the reliability of integrated circuit processes and devices as they relate to part packaging. This paper presents the results of package qualification tests conducted on plastic encapsulated microcircuits (PEMs) and plastic discrete devices (diodes, transistors) used in avionics applications. Highly accelerated stress test (HAST) and temperature cycle (TC) test results, including part failure mechanisms and associated failure rates, are provided. A variety of plastic package styles and integrated circuit functions have been tested. Examples of package styles tested include small outline (SO), plastic leaded chip carrier (PLCC), thin small outline package (TSOP), plastic quad flat package (PQFP) and plastic dual-in-line (PDIP).Manufacturers' devices have been evaluated and various plastic compounds have been compared to determine which provide optimum reliability. The testing showed that package qualification performance of PEMs is affected by type of compound, passivation (including die coat) and die size. HAST failures are caused by moisture penetration of the package while temperature cycle failures result from coefficient of thermal expansion (CTE) mismatch effects.     

A simple moisture diffusion model for the prediction of optimal baking schedules for plastic SMD packages

The moisture concentration at the chip surface is the important parameter for the moisture sensitivity of the P-MQFP80 product considered here. When the critical moisture concentration at the die surface is reached, delamination occurs after soldering shock, e.g at 240°C. This critical moisture concentration, which can be determined by experiments conducted at 30°C/60% relative humidity (RH) followed by soldering shock, allows to predict the product’s moisture performance at other ambient conditions. In the case studied here, prediction was done at a customer use condition of 30°C/85% RH. Furthermore, this work showed that preconditioning of plastic packages not only induces the onset of delamination at the die surface but it appears to weaken the adhesion at this interface as well. As a result, delamination failure starts to occur earlier (i.e. within shorter moisture exposure time) in the devices tested after subsequent thermal cycling stress test. A simple moisture diffusion analytical model is proposed here for predicting the optimal baking schedules for plastic SMD packages.     

对集成电路封装塑封料湿敏性评定技术的探讨

在有关塑封料的湿度浸入研究中,湿气或者是穿过聚合物渗透,或者是沿着引线与密封树脂之间的界面渗透。本文主要是通过试验对与湿度渗透有关的新一代树脂的特性给予评定,并判定引线框架通路是如何影响湿度浸入的。     

Plastic packaging is highly reliable

Plastic encapsulation is now a high reliability (HiRel) method of packaging active semiconductor devices and microelectronics in general. This paper shows that the traditional requirement for hermetic packaging can be overturned in favor of plastic packaging, on the following grounds: the full range of laboratory evidence of HiRel silicone junction coated IC undertaken by many researchers, showing that plastic encapsulations can now be used for microelectronics and optoelectronics in telecommunication, automotive, military and space applications as the better option in many instances; the inadequacy of the Mil-Std hermeticity specification; the demonstrated field failures of Mil-Std-883 hermetic packaged devices and the massive ingress of moisture, which caused many failures of telecommunication switching systems; and the demonstrated better field-reliability in rural tropical climates, of assessed, standard PEM from major manufacturers     

A comparison of the theory of moisture diffusion in plasticencapsulated microelectronics with moisture sensor chip and weight-gainmeasurements

In this paper, the issues pertaining to moisture diffusion in PEMs are explored and discussed. The existing models of moisture diffusion in plastic molding compounds and PEMS are reviewed. Results, modeling and analysis of moisture sorption experiments performed in this study are presented. The moisture sorption experiments were conducted on a set of PEM samples with a common type of encapsulant material to 1) characterize sorption behavior; 2) compare weight gain measurement to the measurement of moisture concentration using a moisture sensor device at the die surface; 3) assess the moisture sensor measurement method. In the case of PEM samples tested in this study, simple Fickian diffusion was shown to agree closely with the experimental results. In one case, a relatively small anomaly from Fickian diffusion was observed and was attributed to swelling and relaxation phenomena at later stages of moisture sorption in the molding compound. The calibration constants determined for the sensors in this study were found to be significantly different from those collected by the manufacturer prior to the encapsulation of the devices. This problem is believed to be degradation in sensitivity of the moisture sensor due to exposure to high temperatures and storage conditions