▎ 摘　　要

In this research article, lead-free nanocomposite soldering is assessed by using the eutectic composition of Sn-3.5Ag-0.7Cu (SAC, wt%) solder alloy as the matrix and graphene nanoplatelets (GNPs) as the reinforcing agent. Powders of these materials are mixed in a mechanical milling system, then compacted, and sintered before application. The effects of GNPs content with different amounts of 0.05, 0.1, and 0.2 wt% are examined to prepare nanocomposite solders as compared to the SAC solder alloy. Furthermore, to improve the metallurgical compatibility between the graphene and SAC solder matrix, the surface of GNPs was decorated by nickel particles using electroless plating techniques before incorporation. After that, the solderability of these prepared lead-free nanocomposite solders is investigated on the copper substrate. As the main result, the formation of the intermetallic compound (IMC) layers at the interface between the Cu-substrate and solder material was found very determinative to control the mechanical performance of soldered joints during lap-shear testing. The content of GNPs and Ni-coating modification strongly affected the morphology and growth of IMC layers at the interface. By increasing the amount of GNPs up to similar to 0.2 wt% and using Ni-coating, the growth of IMC layers was considerably suppressed, leading to a significant improvement of the joint strength up to similar to 27%, despite a reduction of similar to 50% of the ductility. Furthermore, isothermal aging at 150 degrees C up to 100 h resulted in a remarkable increase in the shear strength (similar to 45%) and elongation to failure (similar to 19.9%) through controlling the growth of the IMC layers at the interface. (C) 2020 Published by Elsevier B.V.