摘要电子封装技术已经有了持续向微型化、高性能化发展的趋势。所以如今人们对焊 点的要求越来越高，都希望得到比较小的焊点，但是当对器件通电时，电流通过焊点 时会因为焊点尺寸的大小而影响电流密度，当尺寸变小时，电流密度就会变大，这样 就会造成焊点的过热，从而使焊点产生电迁移影响焊点的质量。一般情况下焊点处会 因为这个现象而出现孔洞。众所周知，孔洞对焊点造成破坏，影响焊件的使用时间。 所以研究人员急需对这个进行研究。最终在 1973 年提出了一个新工艺，它就是电外 延。随着研究的深入，最终提出结论：电外延技术很有可能解决这些焊点间存在的问 题，而这些问题是液相外延技术所不能解决的。本次实验主要研究锡焊点在电流促进 下的液相外延生长与结构演化。78237

实验过程主要分为三个部分。首先，对带有焊缝的铜丝进行同一温度（360℃）， 不同时间（15min、30min、1h、2h）的时效。然后，对带有焊缝的铜丝在四个不同温 度（200℃、300℃、400℃、500℃），同一电流（2A），相同时间（1h）下进行电 外延实验。最后，观察铜丝和焊缝的微观形貌、组织、成分分析。最终得出结论：对 Sn/Cu 焊点进行时效处理时，随着时间的增加，化合物会越长越多。从 15min 到 120min Cu3Sn 厚度从 2μm 长到 7μm 。在电流液相外延的作用下 Sn/Cu 焊点化合物随温度的 升高生长的非常迅速，阴极化合物溶解出现生长不连续现象，阳极化合物异常增大。 在 400℃时出现了焊点全化合物现象。

毕业论文关键词：电外延；液相外延；电迁移；钎焊

Abstract The development of the electronic packaging technology has a trend of miniaturization and high performance development。In order to get smaller joints, the standard of the solder joints will be more and more high。 However, the size of the solder joints could affect the current density while the device is energized。The current density will be higher if the size of the solder joints get smaller,which will affect the quality of the solder joint because of the electromigration。,The holes will be appeared at the solder joints because of this phenomenon。It is well known that the holes can destroy the solder joints and decrease the usage time of the weldment。So the researchers studied for it and put forward a new crafts which we called electrical extension。 After the researchers researching the project for along time,they finally raised a conclusion that the electrical extension may solve the problem of the solder joints which the technology of the liquid phase epitaxy can not。In this experiment,we mainly research the liquid phase epitaxy and the structural evolution of the solder joints under the help of the current。

The experimental process is pided into three parts。 First of all, we do aging experiments on copper wires which have welds in different time (15min, 30min, 1h, 2h) at 360℃。Then we do electrical extension experiments on copper wires which have welds at four different temperatures (200℃, 300℃, 400℃ and 500℃) with a current (2A) at the same time (1h)。 Finally,  the  organization、composition  and  the  microstructure  can  be  obsevered    and

analyzed。 In conclusion, he content of the compound component can be changed by the aging time。 It can also change the size of the compound particles。 The gowing of the compound and the position of the compound growth can be affected by the current liquid phase epitaxy。

Keywords:Electric epitaxy; Liquid phase epitaxy; Electromigration; Braze

目 录

第一章 绪论 1

1。1 引言 1