氧化铝氮化铝热浸镀铝工艺及超润湿机理第一性原理研究

发布时间：2018-03-17 07:32

本文选题：氧化铝　切入点：氮化铝　出处：《清华大学》2015年硕士论文　论文类型：学位论文

【摘要】：铝与氧化铝、氮化铝等含铝陶瓷的连接技术在大功率集成电路封装基板、轻质复合装甲以及汽车工业等领域具有广泛的应用前景。然而,由于铝极易氧化,且铝与陶瓷的物理、化学性质有着巨大的差异,铝对氧化铝、氮化铝等含铝陶瓷的润湿性很差,阻碍了铝与陶瓷的连接。而本课题组发明的陶瓷热浸镀铝工艺,能够在氧化铝、氮化铝陶瓷表面形成均匀的、几微米厚的铝膜,出现了铝对氧化铝、氮化铝陶瓷的“超常润湿”现象。本文实验研究了温度、氧含量以及保温时间等工艺条件氧化铝、氮化铝热浸镀铝的影响,并利用第一性原理计算,从微观角度探究了铝对氧化铝、氮化铝陶瓷“超常润湿”现象的机理。氧化铝陶瓷热浸镀铝实验发现,气氛中氧含量对热浸镀工艺影响显著。在一定温度下,存在一个最佳氧含量区间,使氧化铝陶瓷表面形成均匀和高覆盖率的铝膜,而最佳氧含量区间也会随热浸镀铝温度的变化而发生变化。氧含量主要通过影响熔融铝液的表面张力来影响铝液在氧化铝表面的铺展。高分辨透射电镜对氧化铝C面单晶热浸镀铝样品界面观察发现,界面没有非晶态氧化层,大部分界面十分平整,而在某些区域出现高度约5 nm、外延生长而成的台阶。铝液内部极度缺氧的气氛使氧化铝表面最外层的氧“蒸发”,以A120的形式沿界面扩散,并在某些区域形核、外延生长形成台阶。第一性原理计算表明,这种由于氧化铝表面氧原子层的“蒸发”而形成的(((31)~(1/31))×((31)~(1/31)))R±9°表面重构结构,可以提高氧化铝与铝的界面吸附功Wad并降低铝与氧化铝的接触角θ。当铝液表面吸附氧而使其表面张力降低至0.97 J/m2以下时,铝与氧化铝的接触角θ即可降低至0°,达到“完美润湿”,产生铝与氧化铝的“超常润湿”现象。氮化铝陶瓷热浸镀铝实验发现,保温时间对热浸镀铝工艺影响显著。氮化铝陶瓷片在铝液中保温10分钟以上才能在氮化铝陶瓷表面获得较高覆盖率的铝膜,这是由于氮化铝表面原生的氮氧化物层,铝液与其反应完全后,铝液与新鲜的氮化铝表面接触并润湿。铝液内部极度富铝的气氛会使氮化铝表面形成((3~(1/3))×(3~(1/3)))R30°LCM富铝表面重构。第一性原理计算表明,铝在这种富铝的氮化铝重构表面上的接触角为35-41°;当铝液表面吸附氧而使其表面张力降低至1.02 J/m2以下时,铝液在此重构表面上的接触角可以降低至0°,达到“完美润湿”,产生铝与氮化铝的“超常润湿”现象。
[Abstract]:The joining technology of aluminum with alumina, aluminum nitride and other aluminum-containing ceramics has a wide application prospect in many fields, such as high power integrated circuit packaging substrate, light weight composite armor and automobile industry. However, because aluminum is easy to oxidize, and the physics of aluminum and ceramics, There are great differences in chemical properties. Aluminum has poor wettability to alumina, aluminum nitride and other aluminum-containing ceramics, which hinders the connection between aluminum and ceramics. Aluminum nitride ceramic surface formed uniform, a few meters thick aluminum film, there is aluminum to alumina, aluminum nitride ceramic "extraordinary wetting" phenomenon. The temperature, oxygen content and heat preservation time and other technological conditions, aluminum oxide, aluminum oxide, and other technological conditions, such as temperature, oxygen content and holding time, are studied experimentally. The effect of aluminum nitride hot dip plating on aluminum nitride and the mechanism of "extraordinary wetting" of aluminum nitride ceramics were studied from the microcosmic point of view by first principle calculation. The effect of oxygen content in atmosphere on the hot dip plating process is remarkable. At a certain temperature, there is an optimum oxygen content range, which makes the aluminum film with uniform and high coverage on the surface of alumina ceramics. The optimum oxygen content range also changes with the change of hot-dip aluminum temperature. The oxygen content mainly affects the surface tension of molten aluminum to affect the spread of aluminum solution on the surface of alumina. High-Resolution Transmission Electron Microscopy on Alumina. The interface observation of C plane single crystal hot-dip aluminized sample shows that, There is no amorphous oxide layer at the interface, and most of the interfaces are very smooth. However, in some regions there are steps formed by epitaxial growth at a height of about 5 nm. The extremely anoxic atmosphere inside the aluminum liquid causes the outermost oxygen on the surface of alumina to "evaporate", diffuse along the interface in the form of A120, and nucleate in certain regions. The first principle calculation shows that this kind of surface reconstruction structure is formed by "evaporation" of oxygen atom layer on alumina surface. The interfacial adsorption work of alumina and aluminum can be improved by Wad and the contact angle 胃 between aluminum and aluminum can be decreased. When oxygen is adsorbed on the surface of liquid aluminum, the surface tension is reduced to less than 0.97 J / m2. The contact angle 胃 between aluminum and alumina can be reduced to 0 掳to achieve "perfect wetting", resulting in "extraordinary wetting" of aluminum and alumina. The effect of heat preservation time on the hot dip aluminum plating process is significant. Aluminum nitride ceramic plates can obtain high coverage aluminum films on the surface of aluminum nitride ceramics only when they are kept in molten aluminum for more than 10 minutes, which is due to the primary nitride layer on the surface of aluminum nitride. After the reaction between liquid aluminum and its surface is complete, the liquid aluminum contacts and wets the surface of fresh aluminum nitride. The extremely aluminum-rich atmosphere inside the liquid aluminum makes the surface of aluminum nitride form the surface of aluminum nitride. The contact angle of aluminum on this aluminum-rich aluminum nitride reconstructed surface is 35-41 掳, and when the surface oxygen is adsorbed on the liquid aluminum surface, the surface tension is reduced to less than 1.02 J / m2, The contact angle of molten aluminum on the reconstructed surface can be reduced to 0 掳, which can achieve "perfect wetting" and produce the "extraordinary wetting" phenomenon between aluminum and aluminum nitride.
【学位授予单位】：清华大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB306

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