What Is Solder? | Soldering

Solder is a material used to join soft metals such as copper, gold, and silver. In electronics, copper is the primary metal of concern. Eutectic solder, typically 63% tin and 37% lead, has a minimum melting point of around 360 degrees Fahrenheit, which is easily achievable with a soldering iron.

Non-eutectic solder, like 60% tin and 40% lead, has a higher melting point (around 370 degrees Fahrenheit) and a temperature range where solid and liquid coexist, forming a pasty substance. Solder is also very flexible due to its ductility, which allows metals to interpenetrate during melting. Its high density is primarily due to its lead content.

Solder comes in various wire diameters or gauges, from heavy to very fine, suitable for delicate work like surface mount devices. Concerns about lead's environmental impact have led to the development of lead-free solder, often a tin, silver, and copper alloy, which complies with ROHS programs.

Lead-free solder has a higher melting point, making it more challenging to work with. It is also a newer material with properties that many users are unfamiliar with. Despite this, the trend is moving towards lead-free solder, though leaded solder remains the most common today.