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。     

金丝楔形键合强度的影响规律分析

金丝楔形键合是一种通过超声振动和键合力协同作用来实现芯片与电路引出互连的技术。现今,此引线键合技术是微电子封装领域最重要、应用最广泛的技术之一。引线键合互连的质量是影响红外探测器组件可靠性和可信性的重要因素。基于红外探测器组件,对金丝楔形键合强度的多维影响因素进行探究。从键合焊盘质量和金丝楔焊焊点形貌对键合强度的影响入手,开展了超声功率、键合压力及键合时间对金丝楔形键合强度的影响研究。根据金丝楔焊原理及工艺过程,选取红外探测器组件进行强度影响规律试验及分析,指导实际金丝楔焊工艺,并对最佳工艺参数下的金丝键合拉力均匀性进行探究,验证了金丝楔形键合强度工艺一致性。     

基于正交试验的金丝键合工艺参数优化

金丝键合是实现微波多芯片组件电气互连的关键技术。介绍了引线键合技术的基本形式,分析了键合工艺参数对键合质量的影响。基于正交试验方法,通过对影响25μm金丝键合第一键合点质量的工艺参数优化进行试验研究,确定最优化的工艺参数水平组合,达到提高金丝键合工艺可靠性的目的。     

T/R组件中金丝键合的仿真与优化

金丝键合是微波多芯片T/R组件中实现IVRvlIC芯片电气互连的关键技术,键合的金丝直径,跨距、拱高和数目对组件的微波传输特性具有很大的影响.本文对金丝键合的等效电路模型进行了分析,并采用三维电磁场仿真软件HFSS对金丝键合进行建模分析和仿真优化,最终得出最优结果.     

微组装技术中的金丝键合工艺研究

金丝键合是微组装工艺中的一道关键工艺,金丝键合质量的好坏直接影响微波组件的可靠性以及微波特性.对金丝键合工艺的影响因素进行了分析,并通过设计实验方案对25 μm金丝进行键合实验.对键合金丝进行拉力测试,测量结果全部符合军标GJB 548B-2005要求.根据测量结果寻求最佳键合参数,对实际生产具有一定的指导意义.     

毫米波射频互联金丝热超声楔焊工艺优化研究

金丝热超声楔焊是微波毫米波模块射频互联的关键手段。采用三维电磁仿真软件对毫米波频段的金丝热超声楔焊进行了建模仿真,分析了金丝跨距、拱高和角度等物理参量对驻波的影响。针对模拟仿真优化后的热超声楔焊金丝互连结构,给出了金丝热超声楔焊表面状态优化、线型控制参数优化以及键合参数优化等相应的工艺优化措施,从而达到热超声楔焊金丝性能优化的目的。     

软基板金丝键合可靠性提升方法研究

金丝键合[1]是利用热、压力、超声波能量使金丝与焊盘紧密结合，从而实现芯片与基板间的电气互联和芯片间的信息互通的一种技术。金丝键合是微组装的主流技术，也是一项关键技术。理想状态下，金丝和基板之间会发生原子间的相互扩散，从而使金与金之间实现原子量级上的键合。基板的金表层和金丝的可靠键合是非常关键的质量控制点。微波组件组装过程中，常常因为金丝键合出现缺陷而导致整个产品的失效。对软基板的金丝键合改进方案进行了研究，对比分析了改进前后的实验数据，得出了最优方案，优化了软基板金丝键合工艺的可靠性。试验结果表明，采取了有效的措施之后，消除了失效隐患，对提高软基板键合点的可靠性具有指导意义。     

φ18μm金丝引线键合工艺参数正交试验研究

金丝引线键合是在目前的混合集成电路组装工艺过程中应用最为广泛的：苍片连接技术,而细直径金丝键合对提高混合集成电路组装密度和键合可靠性是十分必要的。本文通过对影响φ18μm金丝引线第一键合点质量的键合工艺参数进行分析,采用正交试验法对键合参数进行试验研究,为φ18μm金丝引线键合的应用提供实验依据。     

微波组件硅铝丝键合工艺参数的优化

通过控制单一变量的试验方法,研究了超声功率、超声时间、键合压力等参数对硅铝丝键合一致性和可靠性的影响,分析了每个参数对硅铝丝键合的影响规律.通过正交试验方法,优化了键合参数组合,并进行试验验证.通过环境试验对微波组件中硅铝丝键合的可靠性进行评价,在某产品上进行验证,并抽样对其可靠性进行评价.产品键合点形貌良好,一致性高...     

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.     

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。     

Role of process parameters on bondability and pad damage indicators in copper ball bonding

Cu wire bonding is one of the hottest trends in electronic packaging due to the cost and performance advantages of Cu wire over Au wire. However, there are many challenges to Cu wire bonding, one of which is the increased stress transmitted to the bond pad during bonding. This high stress is not desirable as it leads to pad damage or cratering in the Si under the pad. Another issue is pad splash in which the pad material is squeezed outside the bonded area, which in severe cases can cause Al pad thinning and depletion. To study the root cause of the increased stress, ball bonding is performed with Au and Cu wires using the same levels of ultrasound (USG), bonding force (BF), and impact force (IF). The bonding is performed on a bonding test pad with integrated piezoresistive microsensors and the in situ pad stress is measured in real time. The ultrasonic pad stress did not show any significant difference between the Au and the Cu ball bonding processes. This indicates that the cause of increased stress cannot be attributed to material properties such as hardness alone, and that the differences in bondability and bonding parameters required for the Cu process might be more influential. To achieve optimal bonding results in terms of shear force per unit area, the Cu process requires higher BF and USG settings, which are the main causes of pad damage. To understand the effect of bonding parameters IF, BF, and USG on pad stress, a detailed DOE is conducted with Cu wire. In addition to conventional bonding parameters, the effect of a non-zero USG level applied during the impact portion of the bonding (pre-bleed USG) is investigated. One of the findings is the reduction of pad damage when higher pre-bleed USG levels are used.     

In situ ultrasonic force signals during low-temperature thermosonic copper wire bonding

Ultrasonic in situ force signals from integrated piezo-resistive microsensors were used previously to describe the interfacial stick-slip motion as the most important mechanism in thermosonic Au wire ball bonding to Al pads. The same experimental method is applied here with a hard and a soft Cu wire type. The signals are compared with those obtained from ball bonds with standard Au wire. Prior to carrying out the microsensor measurements, the bonding processes are optimized to obtain consistent bonded ball diameters of 60 μm yielding average shear strengths of at least 110 MPa at a process temperature of 110 °C. The results of the process optimization show that the shear strength c_pk values of Cu ball bonds are almost twice as large as that of the Au ball bonds. The in situ ultrasonic force during Cu ball bonding process is found to be about 30% higher than that measured during the Au ball bonding process. The analysis of the microsensor signal harmonics leads to the conclusion that the stick-slip frictional behavior is significantly less pronounced in the Cu ball bonding process. The bond growth with Cu is approximately 2.5 times faster than with Au. Ball bonds made with the softer Cu wire show higher shear strengths while experiencing about 5% lower ultrasonic force than those made with the harder Cu wire.     

Iterative optimization of tail breaking force of 1 mil wire thermosonic ball bonding processes and the influence of plasma cleaning

An online tail breaking force measurement method is developed with a proximity sensor between wire clamp and horn. The wire under the tensile load measures about 1.5 cm extending from the bond location to the wire clamp. To increase the sensitivity, the bondhead speed is reduced to 2 mm/s during breaking the tail bond. It takes roughly 10 ms to break the tail bond. The force resolution of the method is estimated to be better than 5.2 mN. An automatic wire bonder used to continuously bond up to 80-wire loops while recording the on-line proximity signals. All wires are directed perpendicular to the ultrasound direction. The tail breaking force for each bond is evaluated from the signal and shown automatically on the bonder within 2 min after bonding.Results are obtained for a typical Au wire and a typical Cu wire bonding process. Both wires are 25 mm in diameter and bonded on Ag plated diepads of standard leadframes at 220 °C. An average Cu tail breaking force of higher than 50 mN is obtained if the leadframe is plasma cleaned before the bonding with 100% Ar for 5 min. This result is comparable to that obtained with Au wire. The standard deviation of the Cu tail breaking force is about twice that obtained with Au wire. The tail breaking force depends on the bonding parameters, metallization variation, and cleanliness of the bond pad. The cleanliness of the bonding pad is more important with Cu wire than with Au wire.     

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。     

Process windows for low-temperature Au wire bonding

The process windows are presented for low-temperature Au wire bonding on Au/Ni/Cu bond pads of varying Au-layer thicknesses metallized on an organic FR-4 printed circuit board (PCB). Three different plating techniques were used to deposit the Au layers: electrolytic plating, immersion plating, and immersion plating followed by electrolytic plating. Wide ranges of wire bond force, bond power, and bond-pad temperature were used to identify the combination of these processing parameters that can produce good wire bonds, allowing the construction of process windows. The criterion for successful bonds is no peel off for all 20 wires tested. The wire pull strengths and wire deformation ratios are measured to evaluate the bond quality after a successful wire bond. Elemental and surface characterization techniques were used to evaluate the bond-pad surfaces and are correlated to wire bondability and wire pull strength. Based on the process windows along with the pull strength data, the bond-pad metallization and bonding conditions can be further optimized for improved wire bondability and product yields. The wire bondability of the electrolytic bond pad increased with Au-layer thickness. The bond pad with an Au-layer thickness of 0.7 μm displayed the highest bondability for all bonding conditions used. The bondability of immersion bond pads was comparable to electrolytic bond pads with a similar Au thickness. Although a high temperature was beneficial to wire bondability with a wide process window, it did not improve the bond quality as measured by wire pull strength.     

A Preliminary Electron Backscatter Diffraction Study of Microstructures and Microtextures Evolution during Au Stud and Flip Chip Thermosonic Bonding

Microstructures and microtextures of the gold wire, free air ball, Au stud bumps and flip chip bonding bumps were analyzed using Electron Backscatter Diffraction (EBSD). It is demonstrated that process parameters, such as bonding power, force and temperature have significant influences on the microstructure and microtexture of gold bumps. The non-uniform deformation, the associated microstructure defects and the local textures of the Au bumps under the vertical force and the horizontal ultrasonic wave applied are presented and discussed.     

Effects of metallization characteristics on gold wire bondability of organic printed circuit boards

Organic printed circuit boards (PCBs) with Au/Ni plates on bond pads are widely used in chip-on-board (COB), ball grid array (BGA), and chip-scale packages. These packages are interconnected using thermosonic gold wire bonding. The wire bond yield relies on the bondability of the Ni/Au pads. Several metallization parameters, including elemental composition, thickness, hardness, roughness, and surface contamination, affect the success of the solid state joining process. In this study, various characterization and mechanical testing techniques are employed to evaluate these parameters for different metallization schemes with varying Ni and Au layer thicknesses. The pull force of Au wires is measured as a function of plasma treatment applied before wire bonding to clean the bond pads. Close correlations are established between metallization characteristics and wire bond quality.     

F&K 6400键合机在SMD封装中的应用

键合是SMD封装中的一道重要工序,F&K 6400键合机是德国F&K公司专门面向细铝丝键合的设备,采用超声作为键合能量。在键合工艺中不同材质的金属管座会形成不同的冶金系统,有些情况下会造成接触面腐蚀或者柯肯德尔空洞,并最终影响产品的可靠性。键合时采用的超声功率、键合时间、键合压力、键合方式等工艺参数直接影响到产品的产量和性能。在批量生产的基础上,作者分析了适合F&K 6400键合机在生产中采用的键合材料及工艺参数,并列出了生产过程中设备常见的故障及可能原因。