A reflow soldering profile for Pb-free soldering requires a higher melting point when compared to Pb-containing solders. The process time for Pb-free solder is shorter than Pb-containing solder, so it is important that the temperature differences on the board be minimized. Melting point of soft solder – 60-40 solder is around 183°C. In general, melting is a phase change of a substance from the solid to the liquid phase. The melting point of a substance is the temperature at which this phase change occurs. The melting point also defines a condition in which the solid and liquid can exist in equilibrium. The melting point of 60/40 solder is 190 degrees Celsius (although that still depends upon the exact composition). The recommended temperature of the soldering iron tip is at least 300 degrees Celsius. Tin-silver-copper. Tin-silver-copper ( Sn - Ag - Cu, also known as SAC ), is a lead-free ( Pb-free) alloy commonly used for electronic solder. It is the main choice for lead-free surface-mount technology (SMT) assembly in the industry, as it is near eutectic, with adequate thermal fatigue properties, strength, and wettability. Several lead-free solder wire specifications and solder melting points commonly used in the market. 1. Tin 99.3 copper 0.7, the melting point of solder is 227 C, belonging to eutectic solder. 2, tin 96.5 silver 3 copper 0.5, solder.