【作者】 魏晶慧；

【导师】 闫久春；

【作者基本信息】 哈尔滨工业大学 ， 材料加工工程， 2013， 博士

【摘要】 与Fe36Ni合金等传统封装合金相比，高体积分数颗粒增强铝基复合材料，具有低密度，低热导率以及一定范围可调的热膨胀系数等性能优点，正向电子封装领域广泛推展。但由于其表面致密的氧化膜以及大量的陶瓷颗粒，对连接性能造成极大的阻碍，限制了这种复合材料的应用范围。实现Fe36Ni合金与铝基复合材料的连接，不仅能够实现构件的减重，还能提高其导热性能，提高构件的可靠性以及延长寿命等，因此研究Fe36Ni合金和高体积分数颗粒增强铝基复合材料的焊接具有重要的理论意义和潜在的应用价值。本文以Fe36Ni合金和55%SiC_p/A356复合材料为研究对象，以两种材料的中低温连接为研究目标，提出了采用ZnAl和SnZn两种钎料对两种材料的超声波钎焊工艺。由于Fe36Ni的良好波传导性，对超声波钎焊工艺的制定有非常大影响。首先对在Fe36Ni合金的超声波传播特性进行了研究，获得Fe36Ni合金板振动场分布，探索合适的钎料放置位置以及超声加载方式。接着研究了ZnAl钎料与Fe36Ni合金的界面反应和组织结构，通过在钎料中增加Si元素，获得了界面结合良好，钎缝无裂纹的接头。其次研究了SnZn与Fe36Ni的界面反应和力学性能，并对固态时效下界面组织的变化进行了系统研究，获得理想的界面结构。然后研究了SnZn与55%SiC_p/A356复合材料的超声波钎焊工艺，通过对Zn含量对接头组织和性能研究，得到界面结合良好高强度的焊缝。最后研究了采用ZnAl和SnZn两种钎料对Fe36Ni合金与55%SiC_p/A356复合材料的超声波钎焊工艺。利用Ansys软件对Fe36Ni合金板进行模态、谐响应以及瞬态分析，研究Fe36Ni合金板的振动场分布。振幅最大值位于在距离右端（非超声加载区域）10-20mm的范围内，此处比较适合放置钎料。单次施加超声0.1s时钎料的飞溅比单次1s时小很多，因此单次超声0.1s是比较合适的工艺。也就是短时间多次超声的脉冲加载超声波方式比较适合Fe36Ni的超声波焊接。采用ZnAl钎料超声波钎焊Fe36Ni合金时，界面化学反应比较剧烈，焊缝中生成较多致密的化合物，且存在大量垂直于界面的裂纹。经能谱分析和逐层XRD分析可得， ZnAl/Fe36Ni的界面结构为： Fe36Ni/Γ-Fe₄Zn₉/Γ2-Fe₆Ni₅Zn₈₉/Fe-Al+Zn。ZnAlSi钎料超声波钎焊Fe36Ni合金时，在界面处形成约0.1μm的Fe₄Zn₉（SiO₄）₃化合物层。此化合物层表现为稳定性，在焊接温度420-500℃，超声作用2-15s，保温10-60min时形貌和厚度几乎不随工艺参数的变化而变化。其接头压剪强度可达102-115MPa，断裂位置主要位于这一薄层物相中。最后提出了Si元素抑制裂纹产生机理的模型。采用SnZn钎料超声波钎焊Fe36Ni合金时，使用Sn20Zn时界面化合物主要为Zn基的化合物，其界面稳定结构为Fe36Ni/Γ-Fe₄Zn₉/FeSn₂/Γ2-Fe₆Ni₅Zn₈₉/Sn20Zn。延长保温时间和提高焊接温度时，界面会出现富Ni Γ2向富Fe Γ2的转变。使用Sn20Zn钎料连接Fe36Ni合金时，其接头的剪切强度可以达到45-55MPa，断裂位置均为于界面化合物层与Sn20Zn钎料的界面上。对Sn20Zn/Fe36Ni的界面进行固态时效研究，Sn20Zn/Fe36Ni的固态时效界面反应层结构稳定，生长速率受扩散机制控制，经计算其界面反应层的生长激活能为6.371kJ/mol。通过改变超声作用、焊接温度和保温时间，研究了Sn20Zn钎料在55%SiC_p/A356复合材料的铺展润湿行为。当超声作用1s以上时，氧化膜完全去除，并且SnZn与SiC实现良好的润湿结合。接头最高剪切强度为超声作用10s+10min+10s时，可以达到108MPa，断裂位置位于近界面的钎料中。采用TEM手段在Sn与Al的界面处发现一层200-400nm的Al₂O₃非晶，增强了Sn与Al的界面结合强度。在Sn/SiC的界面存在一层10nm左右的Mg基非晶，提高了Sn与SiC的界面结合强度。随着钎料中Zn含量的增加，接头强度逐渐增加。Sn40Zn钎料的接头剪切强度最高，强度可以达到115MPa。综合Fe36Ni合金和55%SiC_p/A356复合材料超声波钎焊工艺，研究了上下板母材位置，超声加载方式对接头组织和性能的影响。Fe36Ni合金放置在下板时，能够同时实现对两种母材的异种连接，其最高接头强度可达到114MPa，断裂位置位于Fe36Ni合金侧界面中。使用SnZn钎料钎焊时，其接头剪切强度不随工艺参数变化，稳定在75MPa左右；其SnZn/Fe36Ni界面反应生成Fe₄Zn₉（SiO₄）₃。随着Zn含量的增加，SiC颗粒迁移进入焊缝，其接头强度保持稳定，断裂位置也位近Fe36Ni合金侧界面钎料中。更多还原

【Abstract】 Compared with Fe36Ni alloy, which is the traditional material for electronicpackaging, high volume fraction particle reinforced aluminum matrix composites（Al MMCs） have the advantages of low density, low thermal conductivity andadjustable thermal expansion coefficient in certain range, which will be a materialused widely in electronic packaging. But the compact oxide film and numerousceramic particles on the surface are harmful to their weldability, which strictly limittheir application. To realize the joining of Fe36Ni alloy and Al MMCs can not onlyreduce weight, but also increase their thermal conductivity, to improve theirreliability and extend their life. Thus, joining Fe36Ni alloy/Al MMCs hasimportant theoretical significance and potential application. The aim of this paper isto join Fe36Ni alloy and55%SiC_p/A356composites at medium or low temperature.We want to use ultrasonic soldering process with ZnAl and SnZn solder.The excellent wave conductivity of Fe36Ni greatly effects on making a suitableultrasonic soldering process. Firstly, propagation characteristics of ultrasonic waveon the Fe36Ni surface was studied to get the vibration field distribution of Fe36Nialloy plate, and to optimize the suitable location for solder as well as ultrasonicloading mode. Secondly, interface reaction and microstructure of ZnAl/Fe36Niwas investigated. With the addition of Si element into solder, joints were obtainedwith good interfacial bonding, and free of crack. Thirdly, interface reaction andmechanical properties of Sn20Zn/Fe36Ni, as well as interface microstructure aftersolid aging, were systematically investigated, and ideal interface microstructure wasobtained. Forthly, ultrasonic soldering of55%SiC_p/A356composites with SnZnsolder was researched. By studying the effect of Zn content on joints’ microstructureand properties, joints with good interfacial bonding and high strength were realized.Finally, ultrasonic soldering of Fe36Ni alloy and55%SiC_p/A356composites withZnAl and SnZn solder is studied.Software Ansys was approached the modal analysis, harmonic response analysis,and transient analysis of Fe36Ni alloy plate, to get the vibration field distribution.Location with maximum amplitude is located in10-20mm far away from the rightside （area without ultrasonic loading）, which was the suitable position for solder.The spatter loss of solder with ultrasonic time of0.1s was much smaller than that of1s. Thus, ultrasonic time of0.1s was the suitable applying ultrasonic process forFe36Ni, which was to say that multiple short ultrasonic time loading method.The interface reaction of ultrasonic soldering Fe36Ni alloy with ZnAl was so dramatic that lots of compact intermetallic compounds （IMCs） with cracksperpendicular to the interface were observed in joints. The interface structure ofZnAl/Fe36Ni is Fe36Ni/Γ-Fe₄Zn₉/Γ2-Fe₆Ni₅Zn₈₉/Fe-Al+Zn by EDS andlayer-by-layer XRD analysis. A0.1μm thick IMC layer of Fe₄Zn₉（SiO₄）₃compoundwas formed on the interface during ultrasonic soldeing Fe36Ni alloy with ZnAlSi.They appaered stable and their morphology and thickness did not change with theparameters. The compression shear strength of the joints can get up to102-115MPa,and fracture occured at the thin IMC layer. Lastly, model of crack inhibitionmechanism with Si element is raised.SnZn solder was used to ultrasonic soldering Fe36Ni. Interface IMCs weremainly Zn-based compounds with Sn20Zn, and the interface structure of Sn20Zn/Fe36Ni were Fe36Ni/Γ-Fe₄Zn₉/Γ2-Fe₆Ni₅Zn₈₉/Sn20Zn. With increasing thesoldering tempreture and prolonging the holding time, Γ2rich in Ni could transformto Γ2rich in Fe. Shear strength of Sn20Zn/Fe36Ni joints could be up to45-55MPa,fracture occured between the IMC layer and Sn20Zn solder. The interface ractionlayer of Sn20Zn/Fe36Ni after solid aging was stable, the grown rate of which wascontrolled by diffusion, and the grown activation energy of which was6.371kJ/mol.Spreading and wetting behaviors of Sn20Zn solder on55%SiC_p/A356composites were studied with various ultrasonic time, soldering temperature andholding time. When ultrasonic time was more than1s, the oxide film was broken upcompletely, and good wetting between SnZn and SiC was obtained. Maximum shearstrength can be up to108MPa with applying ultrasonic10s+10min+10s. Fractureoccured in the solder near the interface. An amorphous layer of Al₂O₃with200-400nm thick was formed at the interface of Sn and Al by TEM, which strengthenedthe interface bond. An Mg-based amorphous layer was also found at the Sn/SiCinterface. Joints strength of55%SiC_p/A356composites were increased with theinceeasing of Zn content in the solder, and the maximum strength can be up to115MPa with Sn40Zn.Based on ultrasonic soldering of Fe36Ni alloy and55%SiC_p/A356composites,effects of base metal’s position and ultrasonic loading modes on microstructure andproperties of the joints were studied. When the Fe36Ni alloy was the lower plate,and55%SiC_p/A356composites was the upper layer, the joint of two base metals canbe realized, the strength of which can be up to90-114MPa, and fracture occurs atFe36Ni alloy interface. As to SnZn solder, strength of the joints did not change withthe parameters, and was stable at75MPa. A Fe₄Zn₉（SiO₄）₃compound layer wasformed on the SnZn/Fe36Ni interface. With the increasment of Zn content, SiC wasmigrated to the joint by ultrasonic wave. The strength of the joints with Sn40Zn did not change with compared to that with Sn20Zn, and fracture also occurred in thesolder near Fe36Ni alloy interface.更多还原