The constituents of solder alloy are tin(60%) and lead(40%). The properties of solder which makes it suitable for welding electrical wires are:

i. The melting point of solder alloy is very low. This makes easy for solder alloy to melt very easily for welding.

ii. The electricity conductivity of solder alloy is very high. This makes possible for solder alloy to pass through it very easily.