Solder

Solder is a metal alloy, used in a process called Soldering. Solder is melted over metallic surfaces that will then join when the solder hardens. A soldered joint conducts electricity.

Solder is produced with different metals in its mix for different applications. The type of solder most commonly found in electronics applications is 60/40 (63% tin/37% lead). This formulation allows the solder to melt at a fairly low temperature, flow smoothly, set-up fast, and cool down quickly. But in recent years, environmental concerns over the use of lead have caused many people to switch to lead-free solder. Europe, Japan, California, and New York have passed restrictions against the use of lead solder in commercial applications. That means you can still use it for hobby/non-commercial use.

Lead-free solder is composed largely of tin, with some silver in it to aid melting/flowing. It requires higher temperatures and it's harder to get good joins with it, especially when you're learning. If you do use lead-free, we recommend a SAC305 solder (96.5% tin, 3% silver, and 0.5% copper ) with a "no clean" flux core. Flux is a substance contained in the center (core) of some solder wire or used in concert with solder. It helps the solder to flow better. "No clean" means that you don't have to wash or treat the circuit board/components after soldering to remove any excess flux.