镀钯铜线性能对键合质量的影响研究

研究了不同性能镀钯铜线对其键合质量的影响,分析了不同钯层厚度、不同延伸率和拉断力、镀钯铜线热影响区长短对铜线键合质量的作用机制.研究结果表明:镀钯铜线钯层厚度过小会造成Electronic-Flame-Off(EFO)过程中的Free Air Ball(FAB)偏球、第一焊点形状不稳定及钯层分布不均匀;延伸率过小和拉断力过大会造成焊点颈部应力集中,并产生微裂纹而造成焊点的拉力和球剪切力偏低;镀钯铜线的高强度和低延伸率降低其再结晶温度,造成长的热影响区和颈部晶粒粗大,降低其力学性能,焊接过程中产生颈部裂纹和塌丝.     

镀Au键合Ag线性能对键合质量的影响研究

利用扫描电镜、能谱仪、拉力-剪切力测试仪等研究了不同镀Au厚度的镀Au键合Ag线Free Air Ball(FAB)特性和不同力学性能的镀Au键合Ag线对键合强度及其可靠性的影响规律，研究结果表明：镀Au键合Ag线镀层厚度过小会造成Electronic-Flame-Off(EFO)过程中的FAB偏球及球焊点形状不稳定，镀层厚度过大会导致FAB变尖；高强度、低伸长率会造成焊点颈部产生裂纹而造成焊点的拉力偏低并在颈部断裂，低强度、高伸长率引起颈部晶粒粗大进而降低颈部连接强度；镀Au键合Ag线颈部应力集中或内部组织结构不均匀，在冷热冲击周期性形变作用下，球焊点颈部产生裂纹并引起电阻增加，进而导致器件失效.     

键合Cu线无卤直接镀Pd工艺及性能研究

利用扫描电镜、聚焦离子束、强度测试仪研究了键合铜线无卤直接镀钯工艺及不同模具孔径对镀钯键合铜线表面质量、镀层厚度的影响规律,分析了钯层均匀性对键合性能的影响机理.研究结果表明:无卤直接镀钯工艺可获得镀层均匀的镀钯键合铜线;直接镀模具孔径大于被镀铜线直径3~4μm时,镀钯铜线镀层均匀且表面光洁;镀钯铜线钯层不均匀会造成Electronic-Flame-Off(EFO)过程中的Free Air Ball(FAB)偏球缺陷,进而降低焊点力学性能;直接镀钯键合铜线镀层均匀,避免了Free Air Ball(FAB)偏球缺陷,焊点球剪切力≥15 g、球拉力≥8 g,呈非离散分布,满足工业化要求.     

IC封装中镀钯铜线与裸铜线键合比较研究

镀钯铜线（PdCu）是半导体封装中传统金线键合向铜线键合发展过程中出现的产物,与裸铜线（Bare Cu）键合相比,有着其特有的优劣势。本文通过分析研究发现两种铜线工艺参数有比较大的差别,第一焊点的可靠性测试结果基本相同,而第二焊点结果有一定的区别。本文主要实验数据研究分析镀钯铜线与裸铜线键合的区别,包括第一焊点空气球的可重复性、电火花（EFO）电流大小对焊接结果的影响、铝层挤出的比较。第二焊点的焊接表现,参数范围的变化。可靠性测试结果等。     

Au含量对Ag基键合合金线键合强度及可靠性影响研究

利用扫描电镜、强度测试仪研究了?0.025 mm的不同Au含量对银基键合合金线键合强度及可靠性的影响,研究结果表明,对于Ag-Au键合合金线,随着Au含量增加,其无空气焊球成球性较好,球拉力和球剪切力均增加,热影响区长度降低,Ag-5Au键合合金线球拉力和球剪切力比Ag-1Au球拉力和球剪切力高出28.4%和28.6%; Ag-5Au键合合金线热影响区长度比Ag-1Au键合合金线短42.8%;Ag-5Au键合合金线拉力测试过程中中间位置断裂比例为96%,Ag-1Au键合合金线中间位置断裂比例为21%;含Au银基键合合金线冷热冲击后失效模式为颈部断裂,Ag-5Au键合合金线可靠性高于Ag-1Au键合合金线。     

基于局部溶解性激活的聚合物微流控芯片超声波键合

利用低于临界振幅下的超声波作用在聚合物上仅产生表面热的特点,结合PMMA在异丙醇(IPA)中的温变溶解特性,提出了一种基于局部溶解性激活的超声波聚合物微流控芯片键合方法.理论分析表明当超声振幅小于临界振幅时,只有器件接触表面产生局部表面热,而且在70℃附近IPA对PMMA的溶解性才具有良好的激活作用.在试验研究中,利用精密加工法和热压法制作了带面接触式导能筋结构和80μm×80μm微通道的PMMA微流控芯片基片.在超声振幅为13μm、键合时间8 s、键合压力300 N的条件下进行了键合试验.结果表明,芯片拉伸强度达2.25 MPa,微通道的承压能力超过800 kPa,键合后导能筋无熔融,微沟道变形率小于2%,键合时间仅为8s.该方法的键合强度和键合效率明显高于传统的键合方法,而微结构的变形率却较小,故可作为一种具有产业化前景的聚合物MEMS器件快速封接方法.     

一种新型微变形镜键合技术

对一种新型可变形反射镜加工中的硅-玻璃阳极键合工艺进行了研究。设计了一种通过导线将压焊点引至键合区的特殊结构,使得键合过程中台柱与驱动电极保持等电势,从而有效避免了电极和结构之间的相互作用所引入的缺陷,使得最终获得的驱动电极的有效面积接近100%。针对键合前后气体体积收缩导致的镜面凹陷问题,提出在玻璃上加工出贯穿器件的浅槽结构。实验结果表明,在380C,1atm的环境下施加-1000V电压进行阳极键合时,当浅槽深度大于200nm时,将获得较好的镜面质量。     

激光喷射钎料球键合焊点热循环试验研究

为研究激光喷射钎料球键合焊点的可靠性,用Sn3.0Ag0.5Cu钎料球对Au/Cu焊盘进行了激光喷射钎料键合试验,采用微强度测试仪、扫描电子显微镜、能谱分析仪研究了热循环条件对接头强度以及界面微观组织演变的影响.结果表明：采用激光喷射钎料键合技术焊盘表面Au层不能完全溶入钎料中,导致在界面处形成AuSn2＋AuSn4多...     

激光辅助阳极键合方法及实验研究

为了提高MEMS微器件成品的封装质量和效率,本文自主设计了新型的激光辅助阳极键合技术系统,并将其运用于硼硅玻璃BF33与硅的键合实验,成功实现了硅与玻璃在低功率下局部区域的完好键合.采用扫描电子显微镜对键合样本界面的微观结构进行分析,结果表明:在玻璃/硅的键合界面有明显的过渡层生成.使用能谱仪测定玻璃基体、过渡层以及硅层所含的化学元素种类及其质量分数,通过对比分析认为:激光在键合层的致热温度和界面区的强电场导致硼硅玻璃耗尽层中的氧负离子向键合界面迁移扩散,并与硅发生氧化反应形成中间过渡层,而该界面过渡层的形成是实现玻璃/硅键合的基本条件.该种新型键合技术操作简单、速度快、灵活性高,可以针对不同键合材料实时调整激光功率、行走速度、扫描时间等参数,可广泛应用于MEMS封装器件中硅与玻璃的键合.     

金-硅共晶键合技术及其应用

采用金属过渡层来实现硅-硅低温键合,首先介绍了选择钛金作为金属过渡层的原因和金硅共晶键合的基本原理,然后探索了不同键合面积和不同金层厚度对金硅共晶键合质量的影响规律,开展了图形化的硅晶圆和硅盖板之间的低温共晶键合实验研究,获取了最优键合面积的阈值和最优金层厚度.最后将该低温金硅共晶键合技术应用到MEMS器件圆片级封装实验中,实验结果表明较好地实现了MEMS惯性器件的封装强度,但是还存在密封性差的缺陷,需进一步进行实验改进.     

基于正交试验分析的阳极键合强度研究

采用抗拉强度作为键合质量评价的指标,对硅-玻璃阳极键合的键合温度、冷却速度、退火温度和时间等四个参数的三个位级下的键合效果进行了分析。通过采用正交试验分析法,将81组试验减少为9组并进行了试验。采用自制的抗拉强度测试机对强度进行了测试,结果发现,阳极键合后的冷却速度对强度的影响最为显著,冷却速度越低,强度越高。最后对断裂面进行了SEM分析并对试验结果进行了讨论。     

Transient liquid phase bonding of AA 6082 aluminium alloy

Transient liquid phase bonding (TLP) on AA 6082 samples were performed under ambient non‐vacuum conditions, which was possible by a suitable pre‐treatment. This treatment involves a zincate treatment followed by copper plating, which is a common industrial process and can be performed in large batches. This treatment allows to remove the natural aluminium oxide layer and to protect the aluminium surface from excessive oxidation. Different bonding conditions were investigated and showed the feasibility of the transient liquid phase bonding process for AA 6082. Energy dispersive X‐ray spectroscopy (EDX) investigations showed that the isothermal solidification is already terminated after 5 min. The microstructure of the bonding zone showed no metallurgical discontinuity such as eutectic microstructure or intermetallic Al–Cu phases. However the microstructure shows numerous voids with a size of approximately 30 µm in the bonding zone. It is assumed that these voids were formed during the bonding process due to solidification shrinkage and the presence of interfacial oxide layers. The transient liquid phase bonded samples that were mechanically tested under tensile load showed an average strength of approximately 270 MPa, the minimum yield strength required for the base material according to EN 754‐2 is 255 MPa. Due to the notch effect of the voids, the tensile sample failed under forced fracture and showed no plastic deformation.     

Nanostructured bulk copper fabricated by accumulative roll bonding

In this study, we tried to fabricate the nanostructured bulk copper alloys by a severe plastic deformation process. The sheets of copper alloys (OFC, PMC90, and DLP) were heavily deformed to an equivalent strain of 6.4 by the accumulative roll-bonding (ARB) process. The microstructure and the mechanical property of the fabricated specimens were systematically investigated. The microstructure was finely subdivided with increasing the equivalent strain by the ARB process. The severely deformed copper alloys exhibited the ultrafine lamellar boundary structure where the mean lamella spacing was about 200 nm. The strength significantly increased with decreasing the lamella spacing in the ARB processed copper alloys. Especially, the tensile strength of the DLP alloys ARB processed by 8 cycles (the equivalent strain of 6.4) reached to 520 MPa, which was about three times higher than that of same materials with conventional grain size of 10-100 microm. On the other hand, the total elongation greatly dropped only by 1 ARB cycle corresponding to an equivalent strain of 0.8, which was around 3%. However, the total elongation increased again with increasing the number of the ARB cycle, and it reached to 10% after 8 cycles. The recovery of the total elongation could be recognized in all studied copper alloys. The obtained stress-strain curves showed that the improvement of the total elongation was caused by the increase in the post-uniform elongation. It can be concluded that the nanostructured copper alloys sheets having high strength without a large loss of ductility could be fabricated by the ARB process.     

Architectured bimetallic laminates by roll bonding: bonding mechanisms and applications

Abstract

Manufacturing of bimetallic laminates (<2 mm) with an internal architecture by roll bonding allows to obtain a compromise of conflicting properties. Two applications are considered: copper–steel–copper sheets for high power electronic component substrates and lightweight aluminium–steel–aluminium laminates for structural, electromagnetic applications in power generation and for electromagnetic compatibility. They have in common an architecture, with three-dimensional percolating networks of two metals produced with a sufficient precision. The bonding mechanisms are investigated through microstructural and thermomechanical characterisation of the assemblies produced. Roll bonding fills the voids in a central component by plastic deformation and creates the bonds by cold welding. It may be followed or preceded by surface and heat treatments with the objective to improve the cold welding and to relieve the internal stress state. Architectural rules to optimise the properties of the two-phase laminates in view of the applications may be guided by finite element models combining physical and thermomechanical aspects.     

Effects of surface roughness on the diffusion bonding of Al alloy 6061 in air

The effect of surface roughness on the properties of Al6061 joints fabricated by diffusion bonding in air at 450°C was studied. It was found that rougher surfaces yield superior ultimate tensile strength and linearized bonded ratio. Joints with ultimate tensile strength comparable to that of bulk metal were obtained for holding times of 75 min using rougher surfaces; however, the maximum linearized bonded ratio obtained was only about 75%. Incomplete bonding was attributed to air entrapment along the bond interface. This was due to good bonding occurring at the periphery of the bonded specimens during the early part of the bonding process.     

Au/In等温凝固焊接失效模式研究

研究了Au/In等温凝固芯片焊接的失效模式,对每种失效模式的失效原因进行了讨论,并提出了相应的解决途径。结果表明：镀铟层过厚,会使焊层中产生Ni9In4相和大量空洞,导致焊层出现早期失效;焊接过程中芯片与衬底平行度不好,会使加载压力在焊区分布不均,并导致焊区局部区域发生Au/In不浸润;焊接温度过高,则焊层内会出现较大的热应力,可导致芯片或焊层开裂;在300℃高温下,由于过渡层Ni与Au/In相的反应,焊区内出现大量空洞,导致焊层剪切强度下降。对Au/In体系在未来高温电子器件芯片焊接中的应用,尚需寻找合适的过渡层材料。     

Microstructure and mechanical properties of Al/Al2O3 MMC produced by anodising and cold roll bonding

Abstract

In the present paper, Al–Al₂O₃ composite strips are produced by the cold roll bonding process of anodised aluminium strips. This technique has the flexibility to control the volume fraction of metal matrix composites by varying the oxide layer thickness on the anodised aluminium strip. Microhardness, tensile strength and elongation of composite strips are investigated as a function of quantity of alumina and the applied production method. It is found that higher quantities of alumina improve microhardness and tensile strength, while the elongation value decreases negligibly. Furthermore, prerolling annealing is found to be the best method of producing this composite via the cold roll bonding process. Finally, it is found that both monolithic aluminium and aluminium/alumina composite exhibited a ductile fracture, having dimples and shear zones.