Processins Technology of High Density Interconnection Bumps

封装是实现个人电脑、手机等电子产品封装的主要技术。Bump是必不可少的互连方式。这些凸点的形状演变机制已被讨论的电流分布的基础上。1凸点形状与光致抗蚀剂的角度质量传递是由扩散控制的Peclet数为1.31。传质主要集中在阴极角处。负的光致抗蚀剂角度0防止了这种质量转移并降低了阴极角处的电流密度。对于1407的Peclet数，传质由对流控制。涡流在阴极角部的上边缘和下边缘处形成。负0放大的涡流，并减少在阴极角的电流。2凸块形状在高Peclet数的两个涡流开始合并成一个Pe=73 11。P=44500时形成一个大的单涡。这个大的单个涡流增加了阴极中心的电流。3具有高纵横比的凸块形状使用高纵横比腔体分析了扩散控制时的电流分布。电流分布变得对称与尖锐的峰值为较大的纵横比。4. CSP的高深宽比凸块对于深宽比为1.0的腔体，凸块的下边缘随着阴极放置角度的增加而增大。由于阴极处的自然对流，在腔的外部形成大的涡流。涡流再次流入腔体并与凸块下边缘碰撞。5添加剂和应用的凸块形状-周围带有隆起的凸块捕获更多数量的导电颗粒并提高电性能。添加硒酸是有效的，这种添加剂可以解释的瓦格纳数和二次电流分布。

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.