Eliminating surface mount issues due to copper smearing through modified L-lead design

Copper (Cu) smearing which poses high risk during surface mount (SMT) process is a common problem for sawn packages in semiconductor industry. Attempts to reduce, if not totally eliminate Cu smearing have been done over time, and continuously being done today. These attempts helped in reducing Cu smearing but with drawbacks in terms of cost, parameter and process optimizations which affects capacity and cycle time, and package robustness. This paper focuses on the resolution for Cu smearing through modified lead design (TI Patent 9184120), which will utilize smearing as part of the solderable area rather than a risk. The design includes reduced metal loading which improves blade life without sacrificing lead strength and will not induce change in existing standard processes and parameter. Hence, no additional costs needed for implementation. The etched out area design on the lead will contain the smear produced during saw singulation.