Synergic effect of Te, Ni and MWCNT on creep behavior and microstructural evolution of Sn-1.0Ag-0.7Cu low-Ag solder

• Published in: Journal of alloys and compounds 2022-05, Vol.902, p.163808, Article 163808
• Main Authors: El-Daly, A.A., Eid, N.A.M., Ibrahiem, A.A.
• Format: Article
• Language: English
• Subjects: Alloys; Bonding strength; Copper; Creep life; Creep strength; Intermetallic compounds; Lead-free Sn-Ag-Cu solders; Mechanical properties; Microstructure; Multi wall carbon nanotubes; MWCNTs; Nickel; Polygons; Precipitates; Silver; Solders; Tellurium; Threshold stress; Tin; Tin base alloys
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2022.163808

Avoiding the weak interface bonding of multi-walled carbon nanotubes MWCNT with Sn-Ag-Cu solder matrix is vital to produce high performance large scale Sn-Ag-Cu solder alloys. In this work, Sn-1.0Ag-0.7Cu (SAC107) composite solders were developed by incorporating MWCNT in SAC107 alloy with Ni and Te. The results indicate that the MWCNTs and Cu can be instantaneously adsorbed at the surface-active of Te atoms to in situ compose the core multi-shell (Te/C/Cu/C) polygonal particles, linking MWCNT with SAC solder matrix. The polygonal particles are well dispersed through the Cu6Sn5, Ag3Sn, β-Sn, SnTe and (Cu,Ni)6Sn5 IMC precipitates. These structural variations produce a combination of increased creep resistance 15 times and enlarged creep life time (14 times) than that of plain SAC107 alloy. Although Ni and Te additions decreased the creep resistance of SAC, the SAC-Ni-Te-MWCNT composite alloy exhibits significant change in dislocation creep resistance with creep stress exponent of ~ 6.6 at 25 °C: the creep threshold stress is decreased by 58.8% (5 MPa) in SAC-Ni-Te alloy, while increased by 17.6% (1.5 MPa) in SAC-Ni-Te-MWCNT composite alloy owing to the presence of polygonal particles. The effect of MWCNT, Te, and Ni on the creep properties of SAC alloys was studied. Te atoms enhance the formation of (Te/C/Cu/C) core multi-shell polygonal particles, which increased creep resistance (15 times) and enlarged creep life time (14 times) than that of plain SAC107 alloy. [Display omitted] •The effect of MWCNT, Te, and Ni on the creep properties of SAC alloys was studied.•Te atoms enhance the formation of (Te/C/Cu/C) core multi-shell polygonal particles.•The mechanism of formation of core multi-shell polygonal particles was discussed.•The polygonal particles improved creep resistance in SAC-Ni-Te solder alloys (15 times).•The creep threshold stress increased by 17.6% (1.5 MPa) in composite alloy