Most lead-free alloys used are based on tin silver copper.
One of the main reasons for that is that most of these alloys have only a small a melting range just above 217 °C and can therefore be used for wave and reflow soldering. Within a given range for silver and copper most of these alloys have very similar properties, like melting range and wetting behaviour. The wetting properties of these lead-free alloys are however less than for eutectic tin-lead solder.
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