Effect of Ag and Pb Addition on Microstructural and Mechanical Properties of SAC 105 Solders

• Published in: Journal of electronic materials Vol. 44; no. 10; pp. 3863 - 3871
• Main Authors: Molnar, Aliz, Janovszky, Dora, Kardos, Ibolya, Molnar, Istvan, Gacsi, Zoltan
• Format: Journal Article
• Language: English
• Published: New York Springer US 01-10-2015; Springer Nature B.V
• Subjects: Alloys; Characterization and Evaluation of Materials; Chemistry and Materials Science; Crystallization; Electronics and Microelectronics; Instrumentation; Materials Science; Mechanical properties; Microstructure; Optical and Electronic Materials; Solid State Physics; Pb content; Sn-Ag-Cu solder alloys; microstructure; thermal properties; mechanical properties
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-015-3866-6

Melting and crystallization processes of lead-free and lead-contaminated alloys in near-equilibrium state were investigated. In addition, the effect of silver content up to 4 wt.% on the microstructure of Sn-Ag-Cu alloys was studied. The volume fraction of
β
-Sn decreased by half owing to 4 wt.% Ag content. Furthermore, contamination by lead strongly influences the properties of the solidified microstructure. The Pb grains appear as a result of two processes when the Pb content is equal to 0.5 wt.% or higher: Pb phase solidifies in the quaternary eutectic at 176°C, and Pb grains precipitate from the primary
β
-Sn solid solution grain during a solid state reaction. The freezing range enlarges to 51°C due to 2 wt.% Pb content owing to quaternary eutectic. Above 1 wt.% Pb content, the mechanical properties also improve due to grains of quaternary eutectic Pb and precipitated Pb grains with a size <1 
μ
m.