Diode laser soldering of metallized fibers using gold-tin pre-forms

Diode laser soldering is being increasingly accepted by the microelectronics industry due at least partly to the development of reliable, efficient direct diode lasers. Gold-tin soldering is now employed in a wide range of applications where high temperature capability and corrosion resistance is required, especially in the Photonics industry. There is to date very little published data on laser soldering of this alloy type so an experimental program was conducted to identify appropriate laser processing variables for soldering standard metallized telecommunications fibers to gold plated substrates. The resultant joints were subjected to metallurgical examination and excellent joint quality has been confirmed. No porosity or lack of wetting was noted and a very fine eutectic microstructure was observed. Significant microstructural differences were noted between short and long soldering times.