直流电作用下液—固金属体系的润湿行为与界面特征

发布时间：2018-01-17 12:47

本文关键词：直流电作用下液—固金属体系的润湿行为与界面特征　出处：《吉林大学》2015年博士论文　论文类型：学位论文

【摘要】：近年来,作为一项新兴的材料加工和制备辅助技术,施加电流(电场)的方法在工业生产中获得了越来越广泛的应用。例如,人们发现当对烧结体施加压力的同时施以脉冲直流电(SPS)时,烧结体中通常会有液相出现,与传统烧结方法相比,烧结进程可以在较低温度和较短时间内完成,并且获得的烧结体往往具备更优异的性能;对燃烧合成体系施加直流电可以显著的提升反应率和合成速度。此外,由于三维集成电路中覆晶焊点直径的小型化趋势,钎焊界面往往形成很高的电流密度以及很大的焦耳热,高温能够迫使低熔点的焊球局部发生熔化。有研究指出,焊点合金的液化是其服役早期发生失效的主要原因。虽然如此,人们对于电流在这些应用领域作用机制的认识仍然十分有限。由于上述应用均涉及到液/固界面的交互作用,我们有理由推测电流可能是通过影响液/固界面的润湿、传质以及化学反应来改变这些进程。然而,目前对于电流作用下液/固体系润湿性以及界面反应的研究还非常少。因此,本文系统研究了电流作用下金属熔体在金属基板上的润湿行为和界面结构转变,揭示电流作用下界面润湿机制和影响规律,为利用电流调控润湿性和界面结构奠定基础。本文的主要研究结果如下:1.以Sn/(Ni、Cu、Fe)以及Sn57Bi/Cu为代表,研究了直流电作用下化学反应体系的润湿行为和结构转变。研究发现,施加电流引发的电迁移效应和熔体内部复杂的对流能够显著促进基板的溶解和界面化学反应。两者独立或协同的作用能够破除三相线前沿的氧化膜,从而改善体系的润湿。而当金属基板表面“干净”时,电流对于体系润湿的影响十分有限,但却显著地改变了界面结构。2.以Bi/Cu体系为代表,研究了直流电对纯溶解型体系润湿行为的影响。直流电引发焦耳热效应使熔滴表面的顶部和三相线附近产生了表面张力的梯度,从而导致了Marangoni对流的发生,Marangoni对流促进了Cu向Bi溶解,而当电子流向熔体时,电迁移力能够进一步促进基板的溶解。3.在Sn(Sn57Bi)/Cu体系中,直流电对于金属熔体Sn(Sn57Bi)与金属Cu基板之间的传质和界面反应影响很大。随着电流密度的增大,阴极Cu基板的溶解不断加剧,溶解的Cu原子在电迁移力的驱动下向阳极端迁移,从而使阳极端的Cu基板溶解受到抑制,并在其附近形成大量的金属间化合物。4.推导并计算了Cu在Sn熔体中扩散的有效电荷数目以及电迁移力的数值。阴极端Cu溶解的激活能约为不通电条件下溶解激活能的一半,表明施加电流能够显著降低阴极端Cu溶解的激活能,而电迁移力是促进Cu原子扩散的重要原因。5.以Sn/W和Bi/Fe为代表,研究了直流电作用下存在微量溶解体系的润湿行为。发现电流引发的微量溶解以及电磁力作用对润湿性几乎没有任何影响。总之,通过对电流作用下不同类型金属-金属体系的润湿和界面研究,不仅有助于丰富电流耦合作用下的界面润湿和传质理论,而且能够为通电条件下先进材料的连接和材料服役行为的控制提供参考和指导。
[Abstract]:In recent years, as a new material processing and preparation of assistive technology, applied current (electric field) method has been widely used in industrial production. For example, people found that while putting pressure on the sintered body with pulsed direct current (SPS), usually in the sintered body in liquid phase there, compared with the traditional sintering method, the sintering process can be completed in a relatively low temperature and short time, and get the sintered body tend to have more excellent performance; DC power is applied to the combustion synthesis system can improve the reaction rate significantly and the synthesis speed. In addition, due to the miniaturization trend of three-dimensional integrated circuits in flip chip solder joints the diameter of the brazing interface is often formed in high current density and high Joule heat, high temperature and low melting point solder ball can force the local melt. Some research pointed out that the solder alloy liquefaction is its service early The main reason of failure. However, the understanding of mechanism of current in these areas is still very limited. Because of the above application are related to the interaction of liquid / solid interface, we have reason to suppose that the current may be affected by wetting liquid / solid interface, mass transfer and chemical reaction process. However, these changes at present, the current under the action of liquid / solid on wettability and interfacial reaction are very small. Therefore, this paper studies the change of wetting behavior and interfacial structure of metal melt under electric current on the metal substrate, revealing the current role of interfacial wetting mechanism and the influence rule, to lay the foundation for the current regulation of wettability and the interface structure. The main results of this thesis are as follows: 1. to Sn/ (Ni, Cu, Fe and Sn57Bi/Cu) as the representative of the chemical reaction system, DC power under the effect of wetting behavior and Structure change. The study found that electric convection complex internal migration effect and the melt can significantly promote the applied current caused by the dissolution and interfacial chemical reaction substrate. The two independent or synergistic effect can get rid of the three phase front oxide film, so as to improve the system. When the metal substrate surface wetting and "clean", the influence of current system for wetting is very limited, but it significantly changed the structure of the.2. interface in the Bi/Cu system, studied the effect of DC on the wetting behavior of pure dissolution system. DC Joule heating effect caused by the surface tension gradient near the top surface of the droplet and the three-phase line, which leads to the occurrence of Marangoni convection Marangoni, Cu Bi to promote convective dissolution, and when the electron flow to melt, electromigration force can further promote the dissolution of.3. substrate in Sn (Sn57Bi) /Cu system, DC Electric for molten metal Sn (Sn57Bi) and the mass transfer and the interfacial reaction between the metal substrate Cu influence. With the increase of current density, cathode dissolved Cu substrate increased, driving force in the migration of Cu atoms dissolved under extreme Xiangyang electric migration, so that the Cu substrate dissolved Yang extreme is inhibited, and in in the vicinity of the formation of a large number of intermetallic compound.4. is derived and the effective charge number of Cu diffusion in Sn melt was calculated and numerical electromigration force. Cathode dissolution of Cu activation energy of electricity under the condition of dissolution activation energy of half, Biao Mingshi and current can significantly reduce the activation energy of Cu dissolved and extreme Yin. The electromigration force is.5. an important reason for promoting the diffusion of Cu atoms with Sn/W and Bi/Fe as the representative, to study the existence of wetting behavior of trace dissolved system under the action of DC current caused by the dissolved trace. And the electromagnetic force With almost no influence on the wettability and interfacial wetting. In a word, through the study of different types of metal under the function of the current system, not only has the wettability and mass transfer theory can help to enrich the current under the coupling effect, but also for advanced materials electricity under the condition of even the service behavior of connection and control of materials and guidance.

【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TG111

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