键合线弧高度对键合拉力的影响分析

在集成电路封装的质量控制中,键合拉力的地位非常重要。作为键合质量好坏的主要判定基准之一,影响键合拉力的因素有很多,包括键合工艺参数、焊线材料类型、拉力测试吊钩的测试位置、焊线线径以及线弧的长度和高度等。主要讨论在键合线弧投影长度不变的情况下,线弧高度的变化对键合拉力产生的影响。通过对不同线弧高度条件下测得的拉力数据进行整理分析,结果表明:键合线弧越高,拉力就越大;反之,拉力则越小。这为集成电路组装的正常量产过程中,工程技术人员对于键合线弧整体高度的合理有效控制及键合拉力规范的合理定义提供了参考依据。     

高级IC封装中新兴的细铜丝键合工艺

在铜丝或铜条长期应用于分立器件及大功率器件的同时,近年又出现了晶片的铜金属化工艺。由此,业内人士采用铜作为丝焊键合的一种材料,进而带来了一些新工艺的研究。结果证实,铜金属化使电路的线条更细、密度晚高。因而铜丝可以作为一种最有发展前景及成本最低的互连材料替换金丝,进行大量高引出端数及小焊区器件的球形或楔形键合工艺。本文要阐述了铜丝键合工艺在IC封装中的发展现状及未来发展方向。     

用于三维封装的铜-铜低温键合技术进展

在三维系统封装技术中,金属热压键合是实现多层芯片堆叠和垂直互连的关键技术。为了解决热压键合产生的高温带来的不利影响,工业界和各大科研机构相继开发出了多种低温键合技术。综述了多种不同的低温金属键合技术(主要是Cu-Cu键合),重点阐述了国内外低温金属键合技术的最新研究进展及成果,并对不同低温金属键合技术的优缺点进行了分析和比较。     

微电子器件封装中铜与金球键合的比较

铜球键合由于其成本低并且还可提供更高的可靠性潜力, 最终将成为一种更加流行的主要工艺。目前现有的少管脚数的封装已有一种从金丝向铜丝转变的倾向,但是其中有一些工艺问题,需要该工艺在先进封装中得到广泛的应用之前得以根本的解决。无论采用何种方法,人们可以期望在先进封装中降低成本将最终成为采用铜球键合的驱动力。     

先进封装铜-铜直接键合技术的研究进展

在后摩尔时代,先进三维封装技术成为实现电子产品集成化、小型化的重要出路。应用于封装互连的传统无铅锡基钎料由于存在金属间化合物脆性、电迁移失效、制备工艺限制等问题,已不再适用于窄间距、小尺寸的封装。金属铜的电阻率低、抗电迁移性能好,其工艺制备尺寸可减小到微米级且无坍塌现象。铜-铜（Cu-Cu）直接互连结构可以实现精密制备以及在高电流密度下服役。对Cu-Cu键合材料的选择、键合工艺的特点及服役可靠性的相关研究进展进行了总结。     

Au线键合中"塌线"问题的研究

目前,在半导体闪存多芯片的金线键合工艺中,为满足堆叠芯片不断增加等结构需要,键合线弧要求更低、更长,制造工艺变得相对更加复杂。针对生产过程中常遇到的塌线问题,通过对金线键合工艺中线弧形成动作的过程分析,以金线弹动现象为线索,探究了生产过程中塌线问题产生的原因,并给出了相应解决方案。经过此研究,长线键合的生产工艺能力得到加强,其成果对新封装产品的研发及基板设计具有有益的参考价值。     

铜线键合技术的发展与挑战

铜线键合技术近年来发展迅速,超细间距引线键合是目前铜线键合的主要发展趋势.介绍了铜线键合的防氧化措施以及键合参数的优化,并从IMC生长及焊盘铝挤出方面阐述了铜线键合的可靠性机理.针对铜线在超细间距引线键合中面临的问题,介绍了可解决这些问题的镀钯铜线的性能,并阐述了铜线的成弧能力及面临的挑战.     

文本检测算法的发展与挑战

对自然场景中的文字进行识别和理解是大量计算机视觉应用的基础。文本检测算法旨在识别出自然图像中的文字信息,目前已经成为计算机视觉和智能信息处理领域研究的一个热点。本文首先对文本检测算法的目标、技术路线及其所面对的挑战进行了分析与介绍。然后回顾了几种经典的文本检测算法,并介绍了两种代表最新研究趋势的深度学习型文本检测算法。进一步,本文阐述了几个主流的文本检测数据集并总结了一些代表性文本检测算法在这些数据集上的检测结果。最后,本文讨论了文本检测的研究现状、面临的挑战和发展的趋势。      

NGN的发展与挑战

NGN的标准步伐正在大大加快．包括ITU,ETSI,IETF及3GPP等标准组织和多个论坛正在广泛合作,积极推进NGN标堆化。以IMS为重点的NGN标准得到快速发展．介绍了英国电信的21世纪网络战略。从经济与商业模式、技术以及管制三个方面。论述了NGN带来的挑战。     

VoIP的进展与挑战

随着设备与标准的成熟以及宽带的普及,VoIP在2004年取得突破性进展,几乎所有的主导运营商都在计划或者正在向下一代网络演进.VoIP是他们长期计划中的一项主要战略,但是,在技术与市场的发展过程中,运营商也在经历着各种各样的挑战与困惑.     

The Feasibility of Au Ball Bonding on Sn-Plated Cu

The feasibility of thermosonic gold wire bonding on Cu coupons with Sn/Cu metallizations was studied by evaluating shear strength and microstructure of balls bonded on different Sn metallization samples. The 0.85 ± 0.08 μm and 5.34 ± 0.21 μm thick metallizations were produced by dipping the Cu coupon in 250°C molten Sn solder for 1 s (sample 1) and 30 s (sample 2), respectively. Cu₆Sn₅ intermetallic compounds are formed during dipping. After wire bonding, Au-Cu-Sn layers are found on the ball-coupon interface of both samples. The highest ball shear force observed was 40 gf (1 gf = 9.81 mN) and was achieved on sample 1 using 520 mW and 40 gf of ultrasonic power and bonding force, respectively. The shear fracture goes through the Au ball. The Sn is squeezed out of the contact zone during wire bonding and forms flashes that extend 5 μm and 25 μm beyond the contact zone for samples 1 and 2, respectively.     

Au线改Cu线的新发展及可靠性研究

Au线作为内引线一直占据着键合的主导地位,而由于Cu线具有优良的电性能和价格优势,随着键合技术的发展,以Cu丝代替Au丝作为键合用内引线已经成为现在的主要趋势。介绍了Cu线相对于Au线的优势、存在的可靠性问题,并对Cu引线键合新的发展趋势、如何进行可靠性验证等问题进行了研究。     

Roughness Enhanced Au Ball Bonding of Cu Substrates

Process development studies of Au ball bumping on metallographically polished Cu substrates at ambient temperature were conducted by investigating the effect of process parameters on the ball bond shear force and the extent of bonding. These studies were performed on substrates polished with 0.06-$mu$m or 1-$mu$m abrasive solutions so as to assess the effect of surface roughness on bondability. Response surfaces were generated to illustrate the effects of ultrasonic power, bonding force, and time on bond shear force, and process windows were defined as those parametric combinations that yielded bond shear forces of 25gf or higher. After dissolving the Cu substrate away, the etched surfaces of the Au bumps were examined for bonded areas. Au–Cu ball bonds of about 65$mu$m diameter with bond shear force values higher than 25gf were obtained on 0.06-$mu$m polished substrates, but at an optimum bonding time of 1000ms. Increase in surface roughness, however, reduced the bonding time considerably, and values as low as 200ms were sufficient to yield bond shear force values higher than 25gf on 1.0-$mu$m polished substrates. Bonding on 1.0-$mu$m polished substrates not only reduced the bonding time, but also increased the maximum bond shear force and reduced the localization of bonded areas. These results suggest that a greater number of surface asperities of sufficient height on rougher substrates provide more bonding sites and hence improve the bondability.     

微电子器件封装铜线键合可行性分析

虽然在集成电路封装工艺中金导线键合是主流制程,但是目前采用铜导线替代金导线键合已经在半导体封装领域形成重要研究趋势。文章对微电子封装中铜导线键合可行性进行了分析,主要包括铜导线与金导线的性能比较(包括电学性能、物理参数、机械参数等),铜导线制备和微组织结构分析,铜导线焊合中的工艺研发及铜导线焊合可靠性分析等。当今半导体生产商关注铜导线不仅是因为其价格成本优势,更由于铜导线具有良好的电学和机械特性,同时文中也介绍了铜导线键合工艺存在的诸多问题和挑战,对将来铜导线在集成电路封装中的大规模应用和发展具有一定的参考意义。     

Pressureless Bonding by Use of Cu and Sn Mixed Nanoparticles

Because of high thermal and electrical conductivity, high melting point, and low cost, bonding by sintering of Cu nanoparticles is promising as a new method to replace the Pb-rich solders currently used in high-temperature applications. However, it is difficult to achieve sufficient strength by using this method because, in the absence of applied pressure, oxidized surfaces inhibit sintering. In this study, we report pressureless bonding of Cu plates with Ni layers by use of Cu and Sn mixed nanoparticles. Bonding was achieved without pressure from 250°C to 350°C in hydrogen by use of pure Cu nanoparticles, and by using mixtures of Cu and Sn nanoparticles in which the amount of Sn varied from 10 to 50 wt.%. The highest strength bonds were obtained by use of Cu–10 wt.% Sn mixed nanoparticles, because the sinterability of the Cu nanoparticles is enhanced by diffusion of Sn into Cu to form an appropriate amount of Cu–Sn intermetallic compounds (IMC) and diminish microvoids. However, when the amount of Sn was greater than 10 wt.%, Cu–Sn IMC were formed to such an extent that the significant reduction of Cu-rich layers led to reduced strength. When the bonding temperature was 350°C, Sn diffused into Cu so much that microvoids were formed in the Sn-rich layer. Because the number of microvoids increased as the amount of Sn was increased, the shear strength could not be enhanced by bonding at higher temperature when the amount of Sn was greater than 30 wt.%.     

Developments and Challenges in Self‐Healing Antifouling Materials

Self‐healing antifouling materials have gained rapidly increasing interest over the past decade and have been studied and used in a rapidly increasing range of applications. Recent developments and challenges in self‐healing antifouling materials are summarized in four sections: first, the different mechanisms for both antifouling and self‐healing are briefly discussed. Second, three main categories of self‐healing antifouling materials based on surface replenishing and dynamic covalent and noncovalent interactions are discussed, with a focus on the preparation, characterization, and central characteristics of different self‐healing antifouling materials. Third, different types of potential applications of self‐healing antifouling materials are summarized, such as injectable hydrogels and oil/water separations. Finally, a summary of future development of the field is provided, and a number of critical limitations that are still outstanding are highlighted.     

Development and Status of Cu Ball/Wedge Bonding in 2012

Starting in the 1980s and continuing right into the last decade, a great deal of research has been published on Cu ball/wedge (Cu B/W) wire bonding. Despite this, the technology has not been established in industrial manufacturing to any meaningful extent. Only spikes in the price of Au, improvements in equipment and techniques, and better understanding of the Cu wire-bonding process have seen Cu B/W bonding become more widespread—initially primarily for consumer goods manufacturing. Cu wire bonding is now expected to soon be used for at least 20% of all ball/wedge-bonded components, and its utilization in more sophisticated applications is around the corner. In light of this progress, the present paper comprehensively reviews the existing literature on this topic and discusses wire-bonding materials, equipment, and tools in the ongoing development of Cu B/W bonding technology. Key bonding techniques, such as flame-off, how to prevent damage to the chip (cratering), and bond formation on various common chip and substrate finishes are also described. Furthermore, apart from discussing quality assessment of Cu wire bonds in the initial state, the paper also provides an overview of Cu bonding reliability, in particular regarding Cu balls on Al metalization at high temperatures and in humidity (including under the influence of halide ions).