环氧模塑封材料的热–机械疲劳失效分析

封装材料的热疲劳失效是封装器件失效的主要原因之一.对在微电子封装中应用很广的环氧模塑封装材料进行了常温和高温下的拉伸、疲劳实验.基于以疲劳模量作为损伤因子的疲劳寿命预测模型,相应的材料参数通过实验获得.并通过实验得出了该环氧模塑封装材料考虑温度影响的疲劳寿命预测模型,利用该模型可以对微电子封装用高聚物的疲劳寿命进行预测.     

环氧模塑封装材料的蠕变损伤研究

文章对环氧模塑封装材料（EMC）的蠕变损伤进行了实验研究,对断口进行了扫描电镜观察,获取了EMC材料蠕变失效的微观机理。应用修正的Lermaitre蠕变损伤模型来描述损伤参数及预测蠕变损伤寿命。实验结果表明：EMC材料的蠕变具有明显的蠕变演化的三个阶段;颗粒与基质间的界面脱层和微空洞相互间的级联扩张是引发试样蠕变断裂失效的根本原因;由蠕变损伤模型预测的蠕变寿命在应力水平较低的情况下与实验吻合较好。     

叠层芯片封装元件热应力分析及焊点寿命预测

研究了温度循环载荷下叠层芯片封装元件(SCSP)的热应力分布情况,建立了SCSP的有限元模型。采用修正后的Coffin-Masson公式,计算了SCSP焊点的热疲劳寿命。结果表明:多层芯片间存在热应力差异。其中顶部与底部芯片的热应力高于中间的隔离芯片。并且由于环氧模塑封材料、芯片之间的热膨胀系数失配,芯片热应力集中区域有发生脱层开裂的可能性。SCSP的焊点热疲劳寿命模拟值为1 052个循环周,低于单芯片封装元件的焊点热疲劳寿命(2 656个循环周)。     

温度循环条件下微弹簧型CCGA焊柱的热疲劳寿命仿真研究

对比封装体不同的热疲劳寿命预测模型,选择适用于微弹簧型陶瓷柱栅阵列(CCGA)封装的寿命预测模型,并对焊点的热疲劳机制进行分析。利用Workbench对焊点进行在温度循环载荷作用下的热疲劳分析。对比不同热疲劳寿命预测模型的结果,表明基于应变能密度的预测模型更适用于微弹簧型CCGA。随后对等效应力、塑性应变、平均塑性应变能密度和温度随时间变化的曲线进行分析,结果表明,在温度保持阶段,焊柱通过发生塑性变形或积累能量来降低其内部热应力水平,减少热疲劳损伤累积;在温度转变阶段,焊柱的应力应变发生剧烈变化,容易产生疲劳损伤。     

基于芯片埋置技术的CiP可靠性分析

芯片埋置技术可以提高电子组装密度以及电子产品的可靠性,是微电子封装发展的趋势。建立了聚合物内埋置芯片(CiP)的有限元模型,分析了器件的最大等效应力、剥离应力以及总等效塑性应变,得到该结构容易失效的关键位置。采用修正Coffin-Manson公式对Cu引线的疲劳寿命进行了预测,并分析了Cu引线厚度对其寿命的影响。结果表明,Cu微孔与焊盘交界处的等效应力、剥离应力以及等效塑性应变较大,容易引起裂纹或分层;Cu引线的厚度对疲劳失效起着至关重要的作用,增加Cu引线厚度可以大幅度提高Cu引线的疲劳寿命。     

基于BP神经网络的模塑封材料疲劳寿命预测

根据模塑封材料(EMC)疲劳实验,针对BP神经网络[反向传播神经网络(BPNN)]拟合误差与预测误差关系不稳定的应用问题,结合主成分分析法,"主动"改善网络结构,建立了基于BP神经网络的EMC材料疲劳寿命预测模型,进行了分析,并与一般的BP神经网络模型作了比较。结果表明,该方法得到的BP神经网络经过训练后能稳定表征EMC材料的各种参数与疲劳寿命间的内在关系。当网络拓扑结构为2-4-1时,预测结果稳定,预测误差平方和(SSE)为0.5623～0.0271,拟合误差(MSE)为0.0906～0.0278,具有实用性。     

倒装芯片焊点可靠性的有限元模拟法探讨

随着集成电路封装技术的发展,倒装芯片技术得到广泛应用.由于材料的热膨胀失配,使倒装焊点成为芯片封装中失效率最高的部位,而利用快捷又极具参考价值的有限元模拟法是研究焊点可靠性的重要手段之一.简单介绍了集成电路芯片焊点可靠性分析的有限元模拟法,重点概括了利用该方法对芯片焊点进行可靠性评价常见的材料性质和疲劳寿命预测模型.     

基于内聚力模型的微电子封装材料界面失效分析

界面层裂是微电子封装器件的主要失效模式之一。针对微电子封装器件的界面层裂失效问题,采用内聚力模型的方法,模拟了模塑封装材料和铜引脚层界面在模式Ⅰ、模式Ⅱ以及复合模式（模式Ⅰ和模式Ⅱ）下的裂纹扩展情况,并得到加载力与裂纹开口位移的关系。模拟结果显示,将内聚力模型的方法应用于微电子封装材料的界面层裂失效分析,有助于探索造成可靠性问题的根源,为进一步研究整个器件在生产、制造、测试及使用过程中界面层裂的产生与扩展奠定了基础。     

倒装芯片焊点可靠性的有限元模拟法综述

随着集成电路封装技术的发展，倒装芯片技术得到广泛的应用。由于材料的热膨胀失配，使倒装焊点成为芯片封装中失效率最高的部位，而利用快捷又极具参考价值的有限元模拟法是研究焊点可靠性的重要手段之一。介绍了集成电路芯片焊点可靠性分析的有限元模拟法，概括了利用该方法对芯片焊点进行可靠性评价常见的材料性质和疲劳寿命预测模型。     

陶瓷阵列封装的两种形式及其接头可靠性

介绍了CBGA及CCGA的基本结构,对它们的优缺点进行了对比,分析了在热循环过程中,CBGA、CCGA封装结构产生的热应变及接头的热疲劳寿命,对目前接头热疲劳失效机理的分析进行了对比,总结了影响接头热疲劳寿命的几种因素。     

浅议EMC在LED封装中的应用

环氧模塑料（EMC）作为一种常见的封装材料,具有可规模化生产和高可靠性等特点,被广泛应用于微电子封装领域。随着LED半导体照明技术的迅速发展,EMC作为一种新型支架塑封材料被引入到LED封装行业,成为第三代LED封装支架。与传统的PPA材料相比,EMC具有低膨胀系数、高热导率、更好的耐热性等优势。由于EMC支架是一种高度集成化的支架,具备更好的封装性能和可靠性,可进一步提升LED器件的可靠性并降低LED器件的成本。文章主要介绍EMC支架的主要特点、优势及其制作工艺,同时也总结了EMC在LED封装应用过程中还存在的一些问题。     

绿色环保无卤阻燃环氧塑封料的研究与发展

随着先进集成电路封装技术的快速发展以及全球环境保护呼声的日益高涨,绿色环保无卤阻燃环氧塑封料得到了越来越广泛的重视。文章综述了近年来国内外在绿色无卤阻燃环保塑封料研究与开发领域内的最新进展。分别介绍了均聚型、共聚型以及含氟苯酚-芳烷基型酚醛树脂固化剂、环氧树脂以及塑封料的阻燃机制、研究现状以及发展趋势。同时介绍了中国科学院化学研究所在相关领域内的研究进展情况,最后对我国绿色环保塑封料产业的发展前景进行了展望。     

Random vibration analysis of 3-Arc-Fan compliant interconnects

Microelectronic packaging compliant interconnects offer increased reliability when compared to traditional rigid solder ball interconnects. These interconnects are subject to various forms of mechanical damage including thermal cycle fatigue, drop impact shock, and vibration environments that often lead to mechanical or electrical failure. Second-level compliant interconnects seek to alleviate this issue by decoupling the substrate and board, facilitating independent deformation while experiencing lower stresses and strains. In order to develop compliant interconnects as an effective alternative to rigid solder balls, various design optimization, thermal cycling test, and drop impact studies have been performed. However, the area of vibration characterization and analysis is lacking for microelectronic packaging and nonexistent for compliant interconnects. Therefore, this paper will present a complete vibration analysis of a particular multi-path compliant interconnect design, the 3-Arc-Fan compliant interconnect. This design features three electroplated copper arcuate beams that provide a spring-like effect to increase compliance and mechanical reliability. Experimental vibration characterization was performed and used to validate the simulation model. Following which a random vibration analysis method wais established, and the samples were tested at various conditions. Finally, both experimental and simulation results were integrated to develop a preliminary fatigue life prediction model to demonstrate the increased reliability.     

Analysis of Multilayered Microelectronic Packaging Under Thermal Gradient Loading

An accurate estimation of interfacial and axial stresses in multilayered structures is important in the design process of microelectronic packaging because these stresses drive the failure modes in the package. During manufacturing, microelectronic packaging devices usually suffer from severe thermal gradients. Design engineers often simplify the thermal gradient case as an isothermal loading case by averaging the temperature of the top and bottom of the microelectronic packaging device. Such simplification usually underestimates the stress level in the devices. With the analytical model presented in this paper, the stresses in multilayered microelectronic packaging devices subjected to thermal gradient loading can easily be predicted. It is shown that ignoring the thermal gradient in the package leads to underestimation of stresses     

A dynamic model for solder and the problem of accelerated life testing

Solder joint reliability under thermal cycling is a key problem in electronic packaging. Accelerated life testing (few cycles, larger temperature excursions) is often a practical necessity in predicting fatigue life in field environments (many cycles, smaller temperature excursions). Complex solder behavior with marked temperature dwell and cycle time influence at slower frequencies makes this a difficult problem. A dynamic model is presented which couples the effect of instability of coarsened grain shear band evolution in microstructure with the change in macroscopic constitutive behavior. Key features of the model include effects of shear band thickness compared with total solder joint thickness, pertinent to small scale design, and frictional resistance at slow deformation rates. Model correlation with test data is discussed and applied to the accelerated life test design.     

A new creep–fatigue life model of lead-free solder joint

Life prediction plays an important role in reliability design of electronic product. Solder joint failure is one of the most common failure modes for electronic packaging structure. Current creep–fatigue life models of solder joints are unable to distinguish the creep damage and fatigue damage. In this work, a new creep–fatigue life model was proposed for solder joint tested under high strain rate, where the creep damage was based on Monkman–Grant equation and the fatigue damage was evaluated employing the Coffin–Manson model. Then, linear damage rule was utilized to build the new model. Creep test, fatigue test and creep–fatigue test were conducted respectively in order to determine the parameter in the new model. At last, the experimental result was compared with the predicted result, which shows that the calculation life meets well with the experimental life under high strain rate.