A direct comparison of diode laser soldering of lead-tin and lead-free solders

Abstract

The acceptance of laser soldering by the microelectronics industry has recently increased dramatically due in part to the development of reliable, efficient direct diode lasers. Similarly, soldering using lead free solders has also increased, largely due to current or impending legislation across the world aimed at reducing the usage of lead. There is to date very little published data which allows a direct comparison between lead containing and lead free soldering using direct or fiber coupled diode lasers. By using solder pre-forms differing only in their composition, an experimental program was utilized to identify the subtle differences in the key laser processing variables. The resultant joints were subjected to metallurgical examination to investigate joint quality and to verify the advantages claimed for diode laser soldering. This work has led to an improved understanding of lead free diode laser soldering.The acceptance of laser soldering by the microelectronics industry has recently increased dramatically due in part to the development of reliable, efficient direct diode lasers. Similarly, soldering using lead free solders has also increased, largely due to current or impending legislation across the world aimed at reducing the usage of lead. There is to date very little published data which allows a direct comparison between lead containing and lead free soldering using direct or fiber coupled diode lasers. By using solder pre-forms differing only in their composition, an experimental program was utilized to identify the subtle differences in the key laser processing variables. The resultant joints were subjected to metallurgical examination to investigate joint quality and to verify the advantages claimed for diode laser soldering. This work has led to an improved understanding of lead free diode laser soldering.