SAC305 melts at a slightly higher temperature but has a lower melted viscosity than Sn63. So it takes a smidge longer to heat a joint than for leaded, but you

SAC305 melts at a slightly higher temperature but has a lower melted viscosity than Sn63. So it takes a smidge longer to heat a joint than for leaded, but you don't need to hold the heat there as long once it flows. It's slightly not eutectic, though, so you must immobilize parts as the joint solidifies. Sn99.7 is eutectic but has a still higher melting point. I find SAC305 to solder well at 340°C/650°F.