Lead has been ideal for solder. In fact, says Carol Handwerker, chief of the metallurgy division at the National Institute of Standards and Technology, “The whole electronics infrastructure was designed around the melting point and physical properties of [lead].” Lead is malleable and thus easy to work with, and it doesn’t fracture, she says. When lead is combined with tin in the correct proportion (63% tin to 37% lead), the resulting alloy has a low melting point of 183°C, which is another advantage