塑封器件回流焊与分层的研究

由于无铅焊料的应用,回流焊的温度提高影响了塑封器件的质量和可靠性。针对实际的LQFP器件,利用有限元软件建立三维模型,分析了塑封器件在潮湿环境中的湿气扩散及回流焊中的形变和热应力分布,并讨论了塑封料参数及细小裂纹对分层的影响。结果表明,在湿热的加载下,塑封器件的顶角易发生翘曲现象;芯片与塑封料界面处易分层,导致器件失效。     

核壳橡胶在环氧模塑料中分散及增韧改性研究

应用于环氧模塑料时,核壳橡胶的团聚在正常挤出工艺过程中无法再次分散,它的团聚使得环氧模塑料塑封后的塑封体在CSAM图像中产生黑点。将核壳橡胶与表面活性剂在树脂体系中进行混合预搅拌,能够有效地将已打散的核壳橡胶粒子完全隔离开,从而达到分散核壳橡胶粒子的目的。分散好的核壳橡胶在环氧模塑料中能够提高塑封料的飞边性能,降低塑封料的模量,对应力的吸收有促进作用,从而提高环氧模塑料的可靠性。     

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。     

高导热聚合物基复合封装材料及其应用

微电子封装密度的提高对传统环氧塑封料的导热性能提出了更高的要求,将高导热的陶瓷颗粒/纤维材料添加到聚合物塑封材料中可获得导热性能好的复合型电子封装材料。文章结合高导热环氧塑封材料的研究工作,评述了高热导聚合物基复合封装材料的材料体系、性能特点和在微电子封装中的应用情况。分析讨论了影响聚合物基复合电子封装材料导热性能和介电性能的因素,提出了进一步提高聚合物基复合电子封装材料导热性能的途径。     

关于提高环氧塑封料强度的研究

环氧塑封料的强度在电子封装生产中影响了器件的可靠性和工艺操作性。文章就几种影响环氧塑封料强度的因素进行了实验分析,通过对环氧塑封料固化过程中的弯曲强度和弯曲模量的动态检测,并设定一个模拟环氧塑封料在封装工艺中强度变化的判定标准,可以直接判断其工艺适用性（即“断筋”与否）。文章从塑封料组分中填料的含量与粒度分布、固化促进剂种类与含量、固化剂种类、以及相关改性剂等几方面进行了试验研究,总结出其中重要的影响因素。根据实验结果,可以对环氧塑封料产品的强度进行显著的控制和改进。同时,本研究也有利于对环氧塑封料的“翘曲”、“溢料”等性能的研究和改善。     

超声波清洗引入的芯片金属化裂纹机理分析

对某塑封器件进行破坏性物理分析(DPA),发现芯片表面存在玻璃钝化层裂纹和金属化层划伤的缺陷。对缺陷部位进行扫描电子显微镜(SEM)检查和能谱(EDS)分析,通过形貌和成分判断其形成原因为开封后的超声波清洗过程中,超声波振荡导致环氧塑封料中的二氧化硅填充颗粒碰撞挤压芯片表面,从而产生裂纹。最后,进行了相关的验证试验。研究结论对塑封器件的开封方法提出了改进措施,对塑封器件的DPA检测及失效分析(FA)有一定借鉴意义。     

薄型塑封芯片钝化层损伤的失效分析与改进

针对某薄型塑封产品试制中出现的开、短路问题,通过表面研磨、截面剖切、能谱分析等失效分析手段,确认了塑封料内无机填料颗粒损伤芯片钝化层的缺陷模式。从塑封材料的使用管控、塑封工艺参数改进及塑封料选型等角度对钝化层损伤问题进行了分析与验证。结果表明,合模压力的施加过程是影响芯片钝化层损伤的关键因素,采用215 k N的1段式合模压力设定可有效改善该缺陷,对薄型封装的塑封参数设定及材料选型提供了参考建议。     

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。     

影响环氧塑封料应力、黏度因素分析及解决

环氧塑封料是微电子工业和技术发展的基础材料, 作为IC后道封装三大主材料之一, 随着IC封装技术的发展, 对其特性的要求愈来愈严格, 尤其对应力、黏度等性能的要求更高。文章简要分析了影响环氧塑封料应力和黏度的因素, 并提出了多个解决方案。通过实验的方式得出数据并加以分析, 通过膨胀系数的数据来反映应力大小, 膨胀系数越小, 在封装过程中产生的应力越小, 不易产生翘曲、分层现象。通过黏度数据大小来反映环氧塑封料流动性能的变化。同时文章还介绍了环氧塑封料膨胀系数和黏度的测试方法。     

电解电容器负极引出部位发生跳火的理论研究

研究了在特大纹波电流下电解电容器发生负极跳火的现象。通过对电容器的充放电过程模型进行分析,指出跳火的根本原因在于电容器负极铆接或冷压焊接的引出部位容量很小,会产生反向的电压并逐渐对引出部位进行电压化成,因此产生负极跳火现象。采用负极引出贴箔或增容处理工艺,可有效避免负极跳火,135℃,2000h试验后电容器的失效率为0。     

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.     

Investigation of delamination control in plastic package

Interfacial delamination control is important for the mechanical reliability of plastic package, especially facing the challenge of lead-free requirement. Efforts of delamination performance improvement including structure, material and process for plastic package were made. It was demonstrated that the improvement of packaging material mechanical properties should depend on the package and purpose and should be the comprehensive consideration of advantage and disadvantage. The fracture mechanics was introduced to explain the mechanism of bumpy interface as the delamination retardant. The moisture absorption experiments of three kinds of molding compound were carried out to confirm that large difference of delamination performance among different molding compounds for the same device in our project was induced by moisture absorption difference, and the relation between the moisture weight absorbed and weight ratio of resin was obtained, given compounds of the same resin. It was substantiated that the moisture absorption of molding compound observes the Fick’s law at (Moisture Sensitivity Level 3) MSL3. Quantitative analyses of the moisture influence at the risk location were conducted to evaluate the risk of delamination with the consideration of vapor pressure during solder reflow, moisture and thermal expansion.     

The relationship between moisture resistance and epoxy molding compounds in integrated circuits

The influence of epoxy molding compounds on metallized aluminum corrosion in a Pressure Cooker Test (P.C.T.) was investigated by a monitor chip encapsulated in a dual in-line package (D.I.P.). The monitor chip is composed of a leakage current measuring part which has opposite metallized aluminum tracks and an aluminum corrosion measuring part which has metallized fine aluminum tracks. The formulation of the epoxy molding compound was changed for the average particle size of fillers, the internal release agents, and the coupling agents. The relationships between the stress of the epoxy molding compounds and moisture resistance was also investigated by using epoxy molding compounds which had different characteristics of stress.     

环氧模塑料在半导体封装中的应用

环氧模塑料是一种重要的微电子封装材料,是决定最终封装性能的主要材料之一,具有低成本和高生产效率等优点,目前已经成为半导体封装不可或缺的重要材料。本文简单介绍了环氧模塑料在半导体封装中的重要作用和地位;分析了环氧模塑料性能对半导体封装的影响,并对不同半导体封装对环氧模塑料的不同要求进行了分析;最后展望半导体封装和环氧模塑料的未来发展趋势,以及汉高华威公司在新产品开发中的方向。     

环氧塑封料中填充剂的作用和发展

环氧塑封料占据整个半导体封装市场的90％左右,而填充剂含量占环氧塑封料的60％～90％,因此填充剂的性能直接影响环氧塑封料的加工性能、机械性能、导热性能和半导体器件的封装工艺性能、导热性能、可靠性能等。另外,当今社会电子技术日新月异,集成电路正向着超大规模、超高速、高密度、大功率、多功能、绿色环保化的方向发展,因此对环氧塑封料的性能要求愈来愈高,相应的填充剂性能也有了许多新的要求,并且也出现了许多新型填充剂。文中详细地介绍了环氧塑封料中填充剂的作用,各种填充剂对环氧塑封料和封装器件的性能影响以及环氧塑封料中填充剂的分类和发展。     

EMC所用环保阻燃剂介绍及优缺点比较

随着人们健康环保意识的增强,寻求环保化、低毒化、高效化、多功能化的阻燃剂已成为阻燃剂行业的必然趋势。对于环保模塑料来讲,必须有相对应的符合法令要求的产品。用环保阻燃剂替代原先使用的溴锑阻燃剂加入到基础配方中制备了环保塑封料,文章简单介绍了目前市场上主要的有机及无机阻燃剂的种类,并重点讲述了在环氧塑封料中引用各环保阻燃剂...     

Ion transport in encapsulants used in microcircuit packaging

Most semiconductor devices are encapsulated in epoxy molding compounds. These molding compounds contain ionic contaminants including chloride ions from epichlorohydrin used in the epoxidation of the resin and bromine ions incorporated into the resin as a flame retardant. Chloride ions are known to break down the protective oxide on the surface of aluminum metallization and accelerate corrosion. The encapsulant material is hydrophilic and will absorb moisture from the environment. When the absorbed moisture is combined with ions, there is an opportunity for electrolytic corrosion to occur on the metal surfaces of the device and package elements. However, the rate of corrosion in an encapsulated microcircuit may be expected to depend upon the rate of ion transport through the encapsulant. This paper evaluates two techniques for the measurement of ion diffusion in epoxy molding compounds used for microelectronic encapsulation. The data suggests that ion diffusion rates vary with molding compound formulation, the solution pH and the ion concentration. SEM-EDX analysis and TOF-SIMS analysis indicate that the mode of diffusion of ions in the encapsulants is primarily through the polymer resin matrix as opposed to diffusion at the interface of the resin and the filler particles. Calculated diffusion coefficients were slower than the literature values for moisture diffusion or the diffusion of gases. In fact, under basic conditions, the ions tend to diffuse through the molding compound almost as a front suggesting that the ions bind to the encapsulant and that the diffusion of ions in molding compounds can be modeled using a Type II non-Fickian model.     

Characterization of moisture properties of polymers for IC packaging

In this paper we determined the water uptake of a die attach and a molding compound. The two types of polymer which were selected are a die attach filled with silver particles and an epoxy molding compound filled with silica particles. The water absorption is carried out in an adjustable thermal and humidity chamber, SGA-100, at different temperatures and humidity levels. Moisture absorption equilibrium of test data were obtained by experiment. The moisture absorption equilibrium prediction equation was modeled by using the extrapolated experimental data. Diffusion coefficients at different temperature were obtained from the moisture absorption experiments.     

Electrical characterization of integrated circuit molding compound

Broadband dielectric characterization techniques were applied to a novolac epoxy molding compound used in the integrated circuit industry. Both dielectric loss tangent and relative dielectric constant were determined over the frequency range from 100 MHz to 1.4 GHz, using two independent measurement methods. The molding compound was in “as-molded condition”, which resembles the use conditions for the material     

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