**5.2. Electrical conductivity**

The electrical conductivity of a metal matrix is a function of various factors like fraction of secondary reinforcement phase, fraction of pores, size and shape, and the metal matrix. [92, 93] Nai *et al.* observed that the dispersion of CNT in the Sn based matrix does not decrease the conductivity of the matrix.[94] They correlated this fact with the low volume fraction of pores as well as reinforcement in the solder matrix. This type of behavior has been also observed by Sharma *et al*. for Sn–CeO2 and Sn–Ag/CeO2 nanocomposites.[41, 95] Babaghorbani *et al.* studied the electrical properties of nanocomposite solders in detail and reported that nano-sized reinforcements is advantageous in not degrading the electrical conductivity of the device, while micron sized particles can degrade the conductivity values .[96] This further confirms the unique properties of nanocomposite solders for electromigration property microelectronic packaging devices. Recently, it has been demonstrated the nanoparticles reinforced solders can be promising candidates for preventing electromigration failure in electronic packaging devices.[97]
