塑封集成电路离层对可靠性的影响及解决方法

塑封集成电路因其是非气密性封装,封装材料热膨胀系数的不同以及被粘接材料表面能低,是造成塑封电路离层或开裂的内部原因。通过选择特殊的封装材料（特别是框架材料）和工艺可以解决离层或开裂问题,大大提高塑封集成电路的稳定性和可靠性。水汽是造成塑封集成电路离层或开裂的外部原因,可以通过驱除和防潮措施来解决。要提升塑封集成电路可靠性,必须从技术和工艺上解决塑封电路离层或开裂问题。我们在这方面做了有益的尝试,取得了良好的效果,为拓展塑封集成电路的应用领域创造了条件。     

集成电路封装的打开技术

本文系统介绍了集成电路封装的打开技术，着重介绍了塑封集成电路的部分打开和全部打开，并对打开过程中出现的问题作了分析和探讨。     

引线框架塑料封装集成电路分层及改善

分层是塑料集成电路封装过程和可靠性试验后常见的问题,如何解决分层问题是封装材料供应商、封装工程师、可靠性试验工程师共同研究与改善的课题。通过对封装产品结构、材料、工艺方法等方面进行深入的解析,详细阐述了引线框架塑料封装集成电路分层产生机理,描述了分层对集成电路的危害以及如何预防分层的发生,进而提出了有效的改善措施。结果表明,这些措施的应用能够有效预防分层问题的发生,提高塑料封装集成电路的可靠性。     

基于封装工艺识别翻新塑封集成电路

塑封集成电路在高可靠性领域应用越来越广泛,国内已有相当数量的塑封集成电路应用于国防领域。但是,目前大部分关键塑封集成电路依赖进口,采购渠道不是很通畅,市场中存在大量的翻新件。文章基于塑封集成电路封装工艺,简要介绍如何识别翻新塑封集成电路。     

我国塑封材料发展形势浅析

本文对集成电路封装用塑封材料的生产、发展进行了浅析，并对集成电路和塑封料的现状、发展趋势、市场前景作了认真的论述，对如何加快塑封料的生产，提升产品品位，缩短和发达国家之间的差距，提出了个人看法。     

面板显示驱动电路的失效分析及对策

文章主要对集成电路失效问题进行分析,列举出了容易引起集成电路失效的原因:压焊劈刀选型不当,生产过程中造成芯片表面沾污,芯片表面内压焊点铝层与底层硅化合物结合不牢,选用压焊参数不当,环氧塑封料的特性不佳,存储环境恶劣导致成品电路吸潮等,并逐一进行了分析。同时,还简要的对环氧塑封料特性:耐热性、耐腐蚀性、热膨胀系数、电气特性、耐湿性、结合力方面引起集成的电路失效进行了进一步的分析,提出了预防因产品吸潮而引起塑封体与芯片表面产生分层造成集成电路失效的方法。     

镀钯铜丝芯片键合工艺控制和可靠性研究

随着金价的不断上升,集成电路封装成本越来越高。为此,集成电路封装厂商纷纷推出铜线键合来取代金丝键合,以缓解封装成本压力。但是纯铜丝非常容易氧化,为了提高键合生产效率及产品可靠性,目前封装厂商主要采用镀钯铜丝作为键合丝。对集成电路镀钯铜丝键合生产技术和工艺控制方法进行了探讨,并和金丝及纯铜丝工艺控制进行了比较分析。对镀钯铜丝键合工艺主要失效模式进行了介绍和说明,并就弹坑检测试验方法进行了比较分析和总结。特别是对特殊产品的弹坑检测试验如何才能确保结果准确,进行了实例分析。     

塑封集成电路的抗潮湿性研究

本文介绍了影响塑封集成电路抗潮湿性的主要因素,塑封集成电路潮湿失效的几种类型,提高集成电路抗潮湿性的办法,并介绍了提高集成电路抗潮湿性的实验。实验结果说明,塑封料是影响集成电路抗潮湿性能的最重要因素之一。     

表面贴装声表器件封装失效及其分析

随着声表面波器件日益广泛的应用,声表面波器件的封装尺寸越来越小,封装的难度越来越大,封装过程可能带来的失效问题也越来越多。文章简单介绍了声表面波器件封装形式的变化,论述了表面贴装声表面波器件的封装工艺过程和失效分析的基本概念,并对表面贴装声表面波器件的封装工艺过程中几种主要的失效模式展开分析,促使我们在表面贴装声表面波器件的封装工艺过程加强工序过程的控制,从而提高表面贴装声表面波器件的可靠性,更好地满足顾客的需要。     

塑封集成电路生产中前固化工艺研究

本文对几种在塑封集成电路封装中常用导电胶的前固化工艺进行了比较与探索,得出了一些具有实际意义的温度固化工艺曲线。     

芯片界面强度对其拆解分层的影响研究

电子产品的大量报废使得废弃线路板大量增加,从而使其作为整体丧失原有功能,但其上的元器件特别是集成芯片重用价值高.在拆解重用过程中,加热解焊是重要工艺,它将对已在一定湿度中吸潮饱和的芯片产生热冲击,进而使芯片中产生热应力及湿应力,塑封芯片可能产生分层.为研究芯片界面强度对分层的影响,首先在内聚力理论指导下,对新旧芯片的铜衬底-模塑料间界面强度通过试验-仿真方法进行测量,荻取断裂能、最大张力位移及剪切强度等参数;然后基于ANSYS软件的内聚力模型,建立基于湿-热综合膨胀系数的仿真模型;在此模型中,研究实际中热、湿的极限工况分别对新、旧芯片的界面处切向变形的影响,进而对拆解策略提供指导.     

Programmable logic circuits for functional integrated smart plastic systems

In this paper, we present a functional integrated plastic system. We have fabricated arrays of organic thin-film transistors (OTFTs) and printed electronic components driving an electrophoretic ink display up to 70 mm by 70 mm on a single flexible transparent plastic foil. Transistor arrays were quickly and reliably configured for different logic functions by an additional process step of inkjet printing conductive silver wires and poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) resistors between transistors or between logic blocks. Among the circuit functions and features demonstrated on the arrays are a 7-stage ring oscillator, a D-type flip-flop memory element, a 2:4 demultiplexer, a programmable array logic device (PAL), and printed wires and resistors. Touch input sensors were also printed, thus only external batteries were required for a complete electronic subsystem. The PAL featured 8 inputs, 8 outputs, 32 product terms, and had 1260 p-type polymer transistors in a 3-metal process using diode-load logic. To the best of our knowledge, this is the first time that a PAL concept with organic transistors has been demonstrated, and also the first time that organic transistors have been used as the control logic for a flexible display which have both been integrated on to a single plastic substrate. The versatility afforded by the additive inkjet printing process is well suited to organic programmable logic on plastic substrates, in effect, making flexible organic electronics more flexible.     

FCOB器件在热循环载荷下的界面层裂研究

界面层裂是塑封半导体器件的主要失效模式之一。采用通用有限元软件MSC.MARC,研究了FCOB(基板倒装焊)器件在热循环(–55~+125℃)载荷作用下,底充胶与芯片界面的层裂问题。结果表明:底充胶与芯片界面最易出现分层,分层扩展的位置都在该界面的边缘拐角处;如果分层导致底充胶开裂,开裂的方向大约是35°。     

Investigation of interfacial delamination of a copper-epoxy interface under monotonic and cyclic loading: modeling and evaluation

Interfacial delamination is of important concern for multilayered microelectronic packages, as it is one of the most common failures observed after reliability test. Most of the work, available in open literature, focus on delamination propagation under monotonic loading rather than delamination propagation under cyclic loading. Interfacial fracture mechanics based methodologies have been proven to be efficient in handling interfacial delamination problem under monotonic loading. In this paper, the principles of interfacial mechanics have been applied in the analysis of interfacial fatigue crack propagation. Fatigue test has been conducted in studying onset of delamination and fatigue crack propagation (FCP) of an interfacial crack along a copper-epoxy interface. Models developed in this study have also been applied in the evaluation of multilayered integrated substrate test vehicles.     

热–机械应力和湿气引起QFN器件层间开裂分析

采用通用有限元软件分析和计算器件在潮湿环境下的潮湿扩散,并计算由于吸潮使器件在无铅回流的高温下产生蒸汽压力,并对层间开裂现象进行分析。结果表明,气压是层间开裂的主要原因,在气压和热机械应力的作用下,层合面上的微孔洞扩张并结合起来,导致器件最后失效。     

Drude-Lorentz色散模型研究光学Tamm态的性质

废旧塑封芯片的界面分层会严重影响其回收重用价值, 一直是废弃电器电子产品(WEEE)资源化研究中关注的热点问题。基于有限元仿真方法, 分析了废旧QFP塑封芯片在线路板拆解温度下的翘曲变形和各材料界面应力分布。研究表明, 拆解温度过高时, 芯片翘曲过大容易导致材料膨胀力失配, 造成界面分层; 在粘结层、衬底和模塑料的结合区域应力水平非常高, 较易发生分层; 模塑料在拆解温度下为玻璃态, 与管芯及衬底的结合强度均降低, 其界面角点均为较易发生分层的位置。     

通信泄漏同轴电缆参数的优化及性能研究

研究了遗传算法对通信泄漏同轴电缆进行结构参数优化的方法,分析了漏缆的耦合损耗,并将仿真结果与理论计算结果进行了对照。文中对工作频率为800MHz的周期开槽漏缆进行了优化,使其95%置信度耦合损耗达到70dB,电压驻波比达到1.1。在此基础上比较了在自由空间和靠近理想导体时漏缆的辐射场,分析了置于金属壁附近时导电壁对漏缆耦合损耗的影响。文中研究结果对泄漏同轴电缆的设计和应用有一定参考价值。     

Reliability issues for flip-chip packages

In this article, we review the reliability issues for plastic flip-chip packages, which have become an enabling technology for future packaging development. The evolution of area-array interconnects with high I/O counts and power dissipation has made thermal deformation an important reliability concern for flip-chip packages. Significant advances have been made in understanding the thermo-mechanical behavior of flip-chip packages based on recent studies using moiré interferometry. Results from moiré studies are reviewed by focusing on the role of the underfill to show how it reduces the shear strains of the solder balls but shifts the reliability concern to delamination of the underfill interfaces. The development of the high-resolution moiré interferometry based on the phase-shift technique provided a powerful method for quantitative analysis of thermal deformation and strain distribution for high-density flip-chip packages. This method has been applied to study plastic flip-chip packages and the results and impacts on delamination at the die/underfill interface and in the underfill region above the plated through-hole via are discussed. Here a related reliability problem of die cracking during packaging assembly and test is also discussed. Finally, we discuss briefly two emerging reliability issues for advanced flip-chip packages, one on the packaging effect on Cu/low k interconnect reliability and the other on electromigration of solder balls in flip-chip packages.     

Evaluating IC-package interface delamination by consideringmoisture-induced molding-compound swelling

We have determined the influence of moisture soaking conditions on true adhesion strength measured by our previously developed method. The drop in true adhesion strength of a specimen that absorbed moisture at 50°C is about 50% less than that of a specimen at 85°C. This result suggests that the true adhesion strength depends on not only the moisture content but also the moisture absorption temperature. Therefore, we think that the general moisture condition (85°C/85%) causes more damage to plastic integrated circuit (IC) packages than that of moisture absorption at room temperature. We also evaluated interface delamination in a moisture-absorbed package by considering the swelling of the molding compound due to moisture absorption. The predicted interface delamination agrees well with the experimental data for moisture-soaked packages     

New findings in the occurrence of false-healing in plasticencapsulated microcircuits using scanning acoustic microscopy

“False-healing” refers to the occasionally observed reduction of delamination in plastic encapsulated microcircuits, In previous studies, “false-healing” was reported only at the leadframe-plastic interface. It was thought that the chemical contaminants present in the flux enter the package and form corrosive products which fill up the internal air gaps. This paper reports on some new findings in the occurrence of false-healing in plastic packages using scanning acoustic microscopy. This study found that false-healing also occurs in instances where there was no exposure to corrosive media. Additionally, false healing was observed at the die-plastic interface, where chemical contaminants could not reach. Alternate explanations for this phenomenon are suggested and its impact on damage assessment of plastic encapsulated microcircuits is discussed