基于DOE和BP神经网络对Al线键合工艺优化

Al丝超声引线键合工艺被广泛地应用在大功率器件封装中,以实现大功率芯片与引 线框架之间的电互连.Al丝引线键合的质量严重影响功率器件的整体封装水平,对其工艺参数的优化具有重要工业应用意义.利用正交实验设计方法,对Al丝引线键合工艺中的三个最重要影响因数(超声功率P/DAC、键合时间t/ms、键合压力F/g)进行了正交实验设计,实验表明拉力优化后的工艺参数为:键合时间为40 ms,超声功率为25 DAC,键合压力为120g;剪切推力优化的工艺参数为:键合时间为50 ms,超声功率为40 DAC,键合压力为120 g.基于BP神经网络系统,建立了铝丝超声引线键合工艺的预测模型,揭示了Al丝超声键合工艺参数与键合质量之间的内在联系.网络训练结果表明训练预测值与实验值之间符合很好,检验样本的结果也符合较好,其误差基本控制在10%以内.     

基于Si基芯片的Au/Al键合可靠性研究

对集成电路中常见的Au、Al键合的可靠性进行研究,重点分析高温条件持续时间对引线键合的影响。采用镜检和拉力测试的方法对引线键合点的形貌和强度进行检验,并根据拉力测试数据拟合出高温时间与拉力的关系曲线。最后,基于固相反应原理,给出高温状态下Au-Al系统金属间化合物的演变过程分析。结果表明,Al/Au键合界面比Au/Al界面在高温环境下的可持续工作时间更长。     

超声功率对25μm铂金丝球形键合强度的影响及键合点质量评价

铂金丝作为低温器件封装中理想的键合丝,其键合质量的优劣决定着整个器件的性能和可靠性。通过25μm的铂金丝球形键合试验,并使用OLYMPUS SMT-6三轴测量显微镜观察键合点形貌并测量第一键合点根部直径。结果表明,当超声功率介于0.96～1.2 W时,增加超声功率有助于提高键合强度,增加工艺稳定性。在文中所设实验条件下,为保证键合强度和工艺稳定性,超声功率设置为1.2～1.28 W时最佳。第一焊点键合球平均直径为2.8 WD(WD表示键合线直径)时,键合强度最大,工艺稳定性最好。总结出了键合点直径与拉力值关系图,从而通过键合点直径来评价键合质量。     

厚膜Au导体的超声键合技术研究

Al丝超声键合技术是混合电路组装中使用得最为普遍的一种键合技术。本文使用焊点破坏性拉力试验和焊点的接触电阻测试两种方法，研究了导体材料（Au、Pd—Au）、膜层厚度、125℃、300℃热老练和温度循环对焊点键合强度的影响。分析了键合强度降低和焊点失效的原因。     

红外探测器芯片高可靠性键合工艺研究

金丝键合工艺广泛应用于红外探测器的封装环节。实验选用25μm金丝,基于正交试验法,根据键合拉力值确定键合的最佳工艺参数。通过优化超声压力、超声功率、超声时间及接触力等工艺参数组合,改善了键合引线的电气连接性能和连接强度,从而提高芯片系统的信号传输质量。提出的引线键合工艺参数组合适用于红外探测芯片的键合。     

LTCC基板金丝热超声楔焊正交试验分析

引线键合是微组装技术中的关键工艺,广泛应用于军品和民品芯片的封装。特殊类型基板的引线键合失效问题是键合工艺研究的重要方向。低温共烧陶瓷(LTCC)电路基板在微波多芯片组件中使用广泛,相对于电镀纯金基板,该基板上金焊盘楔形键合强度对于参数设置非常敏感。文章进行了LTCC基板上金丝热超声楔焊的正交试验,在热台温度、劈刀安装长度等条件不变的情况下,分别设置第一键合点和第二键合点的超声功率、超声时间和键合力三因素水平,试验结果表明第一点超声功率和第二点超声时间对键合强度影响明显。     

不同状态的Si-Al丝对键合点根部损伤的影响

键合点根部损伤是Al丝超声键合工艺中最常见的问题,严重的根部损伤不仅使焊点的键合强度降低,甚至会使键合点失效。通过优化键合机器的工艺参数、分析键合丝的组分和采取不同的退火条件,研究Al丝超声键合中,键合点根部损伤的程度,为键合丝的选用和提高Al丝超声键合强度提供依据。     

键合拉力测试点对键合拉力的影响分析

随着现代封装技术的高速发展,对于封装产品质量的检测要求越来越严格,而键合拉力测试是封装产品质量检测中的重要一项,而在相关标准上并未对键合拉力测试点及键合线弧度对测量结果所产生的影响给出明确的规定。基于此,文章介绍了测量点位置、引线弧度、测量速度等因素对引线键合拉力测试准确性的影响。然后通过客观的分析提出了科学合理的键合强度测试的方法,为客观准确的测量键合拉力奠定了基础。     

高温对金-铝系统电阻和强度的影响研究

在讨论金-铝键合系统失效机理的基础上,对高温条件下金-铝键合系统接触电阻和键合强度衰变情况进行研究.给出了金-铝系统接触电阻高温衰减曲线和破坏性键合拉力强度高温衰减曲线.通过对实验结果的分析,提出在设计中通过评估键合点工作温度来避免金-铝键合系统的可靠性隐患.     

InSb红外探测器芯片金丝引线键合工艺研究

InSb红外探测器芯片镀金焊盘与外部管脚的引线键合质量直接决定着光电信号输出的可靠性,对于引线键合质量来说,超声功率、键合压力、键合时间是最主要的工艺参数。从实际应用出发,采用KS公司4124金丝球焊机实现芯片镀金焊盘与外部管脚的引线键合,主要研究芯片镀金焊盘第一焊点键合工艺参数对引线键合强度及键合区域的影响,通过分析键合失效方式,结合焊点的表面形貌,给出了适合InSb芯片引线键合质量要求的最优工艺方案,为实现InSb芯片引线键合可靠性的提高打下了坚实的基础。     

Deformation and bonding processes in aluminum ultrasonic wire wedge bonding

The ultrasonic wire bonding (UWB) process has been examined using transmission electron microscopy (TEM) and standard wire pull testing techniques. Al-0.5 wt.% Mg wires 75 μm in diameter were bonded to pure and alloyed Al substrates. The bonding parameters, surface roughness, and surface contamination levels were variables in the experiments. Cross-section TEM specimens were made from these samples. TEM analysis was conducted on the wire, wire/substrate interface and substrate. Pull tests showed that for the Al substrates the surface roughness or the presence of contamination did not effect the bond strength, whereas for contaminated stainless steel substrates, a three μm surface finish resulted in the highest bond pull strength. The TEM observations revealed features such as low-angle grain boundaries, dislocation loops and the absence of a high dislocation density, indicating that the wire and substrate were dynamically annealed during bonding. Based on the width of a zone near a grain boundary in the wire which was depleted of dislocation loops, it was estimated that local heating equivalent to a temperature of 250° C for 90 msec was achieved in the wire during bonding. No evidence was found for melting along the bond interface, indicating that UWB is a solid-state process. Based on the TEM observationsof the bond interface and the pull tests, it is concluded that the ultrasonic vibrations clean the surfaces to be joined to the extent that a good bond can be obtained by intimate metal-metal contact in the clean areas.     

Influence of surface contamination on metal/metal bond contact quality

The influence of surface cleanliness of Au/Ni coated multichip materials (MCMs), Ag plated Cu lead frames, and Al bond pads on semiconductor chips on the strength of Au wire bond contacts has been investigated. A clean surface is important for good adhesion in any kind of attachment process. Investigations by means of x-ray photoelectron spectroscopy have been performed on the bond substrates to determine the chemical composition, the nature as well as the thickness of the contamination layer. The influence of contamination on bond contact quality has been examined by pull force measurements, which is an established test method in semiconductor packaging industry for evaluating the quality of wire bonds. The results clearly show that a strong correlation between the degree of contamination of the substrate and pull strength values exists. Furthermore, a contamination thickness limiting value of 4 nm for Au and Ag substrates was determined, indicating good wire bond contact quality. The effect of plasma cleaning on wire bondability of metallic and organic (MCMs) substrates has been examined by pull force measurements. These results confirm the correlation between surface contamination and the strength of wire bond contacts for Au/Ni coated MCMs and Ag plated Cu lead frames. Atomic force microscopy measurements have been performed to determine the roughness of bond surfaces, demonstrating the importance of nanoscale characterization with regard to the bonding behavior of the substrates. Finally, bonding substrates used in integrated circuit packaging are discussed with regard to their Au wire bonding behavior. The Au wire bonding process first results in a cleaning effect of the substrate to be joined and secondly enables the change of bonding energy into frictional heat giving rise to an enhanced interdiffusion at the interface.     

镁合金厚板激光焊缝组织及抗拉强度研究

为了提高镁合金激光焊接认识程度,采用高功率CO2激光焊接了10mm厚AZ31镁合金,并对焊缝微观组织和接头抗拉强度进行了研究.在高温作用下,因为镁元素的高温蒸发与烧损,焊缝表面会形成难以克服的凹坑缺陷.在实验条件下,焊缝熔合区微观组织为等轴枝晶,且随着焊接热输入的减少,晶粒细化.抗拉强度测试表明,表面凹坑和焊缝内气孔缺...     

镀金黄铜基板上金丝键合拱高测量及控制技术

引线键合是多芯片微波组件微组装中常用的工艺,通常都会以一定拱弧实现芯片与基板、基板与基板间的互连。如何进行拱高的测量和控制对引线键合有着重要意义,因为拱高的大小还会对微波性能产生重要的影响。文中利用自动键合机获得若干组引线,采用光学测量方法,在放大40倍的状态下分别进行了不同工艺参数下的拱高测量,得出结论在测试范围内,拱度随着弧长的增加而增加,同时还获得了一组适用于微波应用的键合参数。     

镀钛玻璃与PET之间的激光透射连接及其性能

激光透射连接具有生物相容性的异种材料在生物医学植入体及其封装中具有良好的应用前景。利用半导体激光器对镀钛玻璃与聚对苯二甲酸乙二酯(PET)进行激光透射连接试验,其中玻璃上镀钛薄膜是通过射频磁控溅射方法完成的镀膜。通过单因素工艺研究了主要工艺参数激光功率、扫描速度和镀钛薄膜的厚度对连接强度的影响,并探讨了玻璃基片的表面粗糙度对镀钛薄膜粗糙度以及其连接强度的影响。通过搭接剪切试验得到镀钛玻璃与PET之间的连接强度,采用真彩共聚焦材料显微镜对拉伸失效后的试样表面进行观测和失效分析,使用X射线光电子能谱(XPS)检测激光透射连接过程中镀钛玻璃与PET之间化学键的形成信息。结果表明:主要工艺参数激光功率、扫描速度对连接强度有着重要影响,增加玻璃基片的粗糙度和镀钛薄膜的厚度可以提高其连接强度,为激光透射连接镀钛玻璃与聚合物提供了参考。     

Plasma cleaning of the flex substrate for flip-chip bonding with anisotropic conductive adhesive film

Advanced integrated circuit packaging processes require good bondability and reliability between various mating surfaces. A key factor affecting this requirement is surface cleanliness. Plasma cleaning is the most suitable process for optimum surface cleanliness. An investigation of O₂, Ar, and O₂/SF₆ plasma cleaning was carried out on a flexible substrate to study the adhesion of anisotropic conductive adhesive film for flip chip bonding. Surface roughness was found to increase substantially after the plasma treatment. Adhesion strength was evaluated by 90° peeling tests both for untreated and plasma-treated flex. A higher adhesion strength of anisotropic conductive film (ACF) bond was observed after plasma cleaning. The surface morphology of plasma treated and untreated flex substrate before bonding, as well as the fracture surfaces after the peel test for both cases, was characterized by secondary electron image techniques of scanning electron microscopy (SEM). Based on the detailed SEM findings, extensive comparisons were made between the plasma treated and the untreated samples. Mechanical interlocking is found to be responsible for higher peel strength of the plasma treated flex bonding. It was also proposed to select the right flexible substrate for highly reliable, ACF bonded flip chip on flex substrate.     

第一顺序键合引脚失效分析及键合可靠性提高

文章分析了一例采用金丝热超声键合电路在工艺监控过程中的键合强度检测合格,在高温稳定性烘焙后其引线抗拉强度同样符合MIL-STD-883G方法2011．7的要求,但电路在使用中出现第一顺序键合引脚开路现象。经分析是由于芯片键合区（压点）的材料、结构、键合工艺参数处于工艺下界,以及此类缺陷不能通过键合引线抗拉强度在线监测（包括125℃下的24h高温贮存后的检测）检测出而导致。最后针对缺陷所在,通过改进检测方法、键合工艺设置等消除了键合缺陷,并提高了键合可靠性。     

基于MCL-UNet网络的激光熔覆层表面平整度识别

表面平整度是衡量多道搭接熔覆层表面质量的重要指标之一,为改进人工标注获取表面平整度耗时费力的问题,本文利用图像识别和语义分割神经网络方法提出了自动识别熔覆层表面平整度。针对搭接熔覆层特征,基于改进的U-Net与注意力机制(CBAM)提出一种用于熔覆层形貌的自动分割网络MCL-UNet,优化改进U-Net模型,依据CBAM模块从通道维度和空间维度调整特征图层的权重信息,将CBAM模块以优化输入和输出的原则部署在网络上。在搭接熔覆层数据集上对改进的网络进行评估对比,实验结果表明,本文提出的MCL-UNet网络模型,其熔覆层分割效果在验证集上的平均IoU准确率为93.76%,相比原始U-Net的IoU准确率提高了5.81%,在测试集上MCL-UNet模型输出的表面平整度的平均相对误差为3.2%,说明该模型可有效提高搭接熔覆层横截面形貌的分割精度,并能较准确输出表面平整度。     

金丝球焊复合键合工艺可靠性研究

对芯片铝焊盘上不同重叠面积的金丝球焊复合键合的可靠性进行研究,并与非复合键合进行对比.结果 表明,随着复合键合重叠面积的减少,键合拉力和界面生成的合金化合物面积均无明显变化,而剪切强度呈下降趋势.高温储存结果表明,复合键合拉力值满足国军标要求.复合键合有掉铝和弹坑缺陷隐患.经分析,原因是复合键合时施加的超声能量破坏了硅...