Eutectic solder is a solder made of 37 percent lead and 63 percent tin and is also called 63/37 solder. Eutectic solder melts at a single temperature, which makes it preferable to non-eutectic solder.
Solder is a fusible metal alloy frequently used in plumbing, electronics and jewelry to join together metal pieces. It has a melting point below that of the pieces it joins. Typical melting points for solder are between 90 and 450 degrees Celsius. Solder is available in a range of thicknesses, as a paste, as bars and as thin sheets. The word solder originally comes from the Latin "solidare," which means to make solid.