This study investigates the effect of the different wt % of carbon nanotube (CNT) on melting point and the effect of time duration in the reflow zone on the reliability of the CNT-composite solder (CCS) solder. The reliability of the CCS solder was evaluated based on the microstructure and wettability of the CCS solder. The CCS with different wt % of CNT was first characterized with Differential Scanning Calorimetry (DSC) to obtain the melting point of the solder. Meanwhile, the microstructure and wettability of the solder were observed through SEM and ImageJ. The results show that the addition of the CNT within the solder matrix will not affect the melting point of the solder. However, a long duration of time within the reflow zone would improve the microstructure and wettability of the CCS solder.