Improvement of characteristic of redistribution layer (RDL)on mobile application

The application of metal redistribution layer (RDL) for the mobile application and its improvement are presented in this paper. These experiment designs are carried out to determine the optimal sputtering and pre-treatment conditions of the metal redistribution layers before the wire bonding process though the studies of surface morphology and phase transformation. In addition, a notable improvement of visual inspection is demonstrated by these optimal process conditions. From these experimental results, two types of RDL non-uniform defects were formed during the sputtering and pre-treatment process. By sputtering deposition process control and optimizing the pre-treatment process time, these two RDL non-uniform defects ration can be reduce to 10% of original. Another key index of assembly process, the shear strengths of wire-bonding bondability test can also be obtained a significant improvement by using these optimal process conditions.