**5.5. Microhardness**

The nanocomposite solders developed have better microhardness as required for the electronics packaging industry. It has been reported that the addition of ceramic oxides or inert nanoparticles [19, 21–23, 34–37, 41, 95] can improve the mechanical performance, tensile strength, elongation and creep properties of nanocomposite solders. Moreover, the addi‐ tions of nanoparticles refine the grains of the matrix as well as are adsorbed on the interme‐ tallic to refine them. In general, there is an enhancement at the cost of ductility of the solder which is undesirable. Recently, Sharma *et al*. have produced Sn–Ag–Cu/La2O3 solder with an improved tensile strength as well as ductility. They explained this due to the mechanism of slip mode transition of dislocation when interacting with the La2O3 nanoparticles in the solder matrix.[19]

#### **5.6. Wear and friction behavior**

In various microelectronic devices and assemblies, Sn based connectors such as press fit plugs and sockets, separable interconnects in consumer electronic appliances are gaining popularity nowadays. Gold and silver based contacts provide optimum wear resistance in sliding contacts but they are not economical. Therefore, the sliding wear and tear are important for Sn based solders may limit their applications. [101] Tin based contacts are generally susceptible to fretting wear which is a prime concern in automobile applications.[102, 103] Sn based connec‐ tors are very ductile and more sensitive to fretting wear. Hammam *et al*. investigated the wear and frictional properties of various Sn coating prepared hot dipping, electroplating, and reflow processes. They suggested that the different processing routes for Sn deposition produce different thickness of the Sn coatings and hence the intermetallic compounds on a metallic substrates. [104] In case of nanocomposite solders, Jun *et al*. reported that tin bronze reinforced with carbon fibers improves the resistance against the fretting wear appreciably.[105] Sharma *et al*. have recently found a significant enhancement on the wear resistance of Sn and Sn–Ag matrices reinforced with CeO2 nanoparticles.[41, 95]
