倒装焊后清洗工艺及其对底部填充的影响

倒装焊封装是通过将整个芯片有源面进行管脚阵列排布并预制焊料凸点,通过倒装焊工艺进行互连,与传统引线键合技术相比具有更高的组装密度及信号传输速率,是实现电子产品小型化、轻量化、多功能化的关键技术之一.对于小尺寸微节距的倒装焊芯片来说,焊后清洗的难度相对更大,因此清洗技术也是影响倒装焊工艺的重要因素.针对不同清洗方式及参数...

Investigation on Cleaning Technology after Flip Chip Bonding and its Influence on Underfill

Flip chip packaging is one of the key technologies to realize miniaturization,lightweight and multi-function of electronic products,because it has higher assembly density and signal transmission rate than traditional wire bonding.The chip active surface that has pin array and prefabricated solder bumps is interconnected by flip chip bonding technology.It is much more difficult to clean for the flip chip with small size and micro pitch,so cleaning technology is an important factor affecting the flip chip bonding process.In this paper,the distinction of cleaning effects between different methods and parameters and the influence of residual flux on the underfill effect are studied in order to optimize the cleaning technology of flip chip.The results show that the flux in the fine gap between flip chip and substrate can be fully cleaned by the vacuum vapor cleaning process of pre-cleaning(≥3 min)-regular cleaning(≥3 min)-steam rinsing(≥3 min)-vacuum drying(≥4 min).There is no residual flux and cleaning solution,thus ensuring the rapid flow and completely curing of underfill material,and the void rate of underfill can be less than 5%.