**5.3. Melting point**

There is wide distribution of results on the thermal behavior of solders.[18, 22, 23, 41, 95, 98, 99] The melting points of the nanocomposite solders generally decreases with an increase in the fraction of the nanoparticles in the matrix. Liu *et al.* reported that Sn–Ag–Cu/nano-SiC showed a reduction in melting point compared to monolithic Sn-Ag-Cu alloy. They correlated this observation to the increase in the interface surface instabilities after the addition of SiC nanoparticles. Similarly Kumar *et al.* also observed a slight depression in the melting point in CNT reinforced solder matrix. However, Nai *et al.* did not observe any significant drop in the melting point.[98, 99] Shen *et al.* while working on ZrO2 reinforced solder the reinforcement particles, i.e., ZrO2 nanoparticles behave as a nucleating agents and promote the nucleation of the matrix during solidification. Therefore, more nucleating sites results in grain refinement and a drop in melting point could be noticed. [22] Recently, Sharma *et al.* have found a decreased melting point of Sn–CeO2 and Sn–Ag/CeO2 nanocomposites and explained this behavior to the refinement of matrix grains after addition of nanoparticles.[41, 95]
