Processins Technology of High Density Interconnection Bumps

封装技术是实现个人电脑、手机等电子设备小型化的主要技术。Bump是不可缺少的互连方法。基于电流分布，讨论了这些凸起的形状演化机制当佩莱特数为1.31时，传质受扩散控制。传质集中在阴极角。负光阻角0阻止了这种传质，降低了阴极角的电流密度。当佩莱特数为1407时，传质由对流控制。涡流形成于阴极角的上边缘和下边缘。负0增大了涡流，减小了阴极角处的电流当Pe=73 11时，两个漩涡开始合并为一个。P=44500时的大单涡形式。这个大的单涡增加了阴极中心的电流分析了高纵横比空腔在扩散控制时的电流分布。当宽高比增大时，电流分布变得对称，并出现一个尖峰。空腔外部的对流不会搅动它们的内部对于长径比为1.0的空腔，随着阴极放置角的增加，凸点的下边缘增大。由于阴极处的自然对流，在腔外形成一个大的涡流。旋涡再次流入空腔并与凸起的下边缘发生碰撞凹凸形状与添加剂和应用-凹凸与周围的驼峰捕获更多的导电颗粒，提高电性能。一种硒酸添加剂是有效的，这种添加剂可以用瓦格纳数和二次电流分布来解释。

Packaging is the main technology to miniaturize the electronics devices such as personal computer and celler phone. Bump is indispensable interconnection method. The shape evolution mechanism of these bumps has been discussed based on the current distribution.1 Bump shapes with photo resist angle The mass transfer is controlled by diffusion for the Peclet number of 1.31. The mass transfer is concentrated at the cathode corner. The negative photo resist angle, 0, prevents this mass transfer and decrease current density at the cathode corner. The mass transfer is controlled by convection for the Peclet number of 1407. The vortices form both at upper and lower edge of the cathode corners. The negative 0 enlarges the vortices and decreases the current at the cathode corners.2 Bump shapes at high Peclet numbers The two vortices start to merge into one for Pe=73 11. A large single vortex form for P=44500. This large single vortex increases the current at the cathode center.3 Bump shapes with high aspect ratio The current distribution at diffusion control is analyzed with high aspect ratio cavity. The current distribution becomes symmetric with a sharp peak for larger aspect ratio. The convection outside of the cavity does not stir their inside.4 High aspect ratio bumps for CSP The lower edge of bump enlarges with increase of cathode placement angle for the cavity of 1.0 aspect ratio. A large vortex forms outside of the cavity because of the natural convection at the cathode. The vortex again flows into the cavity and collides with the bump lower edge.5 Bump shapes with additive and the application -The bumps with hump on the surroundings traps more number of conductive particles and increase the electric properties. An additive of selenic acid is effective and this additive can be explained by the Wagner number and secondary current distribution.