The physical properties of SAC-alloys compared with SnPb-alloys

Property                             Unit               SAC             SnPb
Density                               g/cm³             7.5               8.5
Melting Point                      ºC                  217              183
Volume change
Solidifying                          %                   > 2.7            1.7
Thermal conductivity       W/cm ºC¹      0.73             0.50
Electrical conductivity      % of Cu        11                 11.5
Surface Tension              mN/m            548              481 
¹ @ 85 ºC

For physical properties on other alloys, see SMT/Reflow Soldering