Corrosion studies of ternary Sn-3.0Ag-0.5Cu, Sn-0.7Cu-Ni0.05 and binary Sn-0.8Cu lead-free solder alloys in various liquid media

• Main Author: Guerrero, Jan-Ervin C.
• Format: text
• Language: English
• Published: Animo Repository 2016
• Online Access: https://animorepository.dlsu.edu.ph/etd_masteral/5196
• Institution: De La Salle University

Solders are critical components in electronic systems. However, environmental issues forced the industry to shift to lead-free systems. Aside from soldering properties, the often overlooked property is the corrosion behavior of new lead-free alloys. The goal of the study is to determine the corrosion properties of lead-free soldering alloys in common corrosive liquid media that may pose threat on their reliability in electronic systems. The corrosion and leaching behavior of new ternary Sn-Cu-Ni (Sn-0.7Cu- 0.05Ni), Sn-Ag-Cu (Sn-3.0Ag-0.5Cu), and binary Sn-Cu (Sn-0.8Cu) solder alloys in 3.5 wt. % NaCl solution, 0.1 M HNO3 solution and Artificial Sweat solution were investigated. Results of the electrochemical measurement showed that Sn-Cu-Ni alloy had best corrosion resistance in acidic environment while Sn-Ag-Cu solder had the best corrosion resistance in 3.5% NaCl solution and in artificial sweat solution. In both potentiodynamic polarization and leaching tests, the corrosion behavior of solder alloys is found to be dependent on the pH of the media where HNO3 was the most corrosive among the solutions used in this study. However, 30-day immersion of the solder alloys and joints in artificial sweat solution showed the lowest amount of leached Sn for all the solder under studied. SEM images showed drastic changes on the microstructure surface of each samples after the corrosion test in all of the solution. EDS and XRD analysis showed that regardless of the corrosive media, Sn and O are components of the corrosion products indicating that the corrosion products are made up of oxides of tin.