Can reflow soldering support double-sided pcb?

Yes. During the second reflow, there is oxide on the surface of the solder joint for the first reflow, and the solder joint lacks the function of flux (the ability of the flux to remove the oxide film is insufficient), even if the temperature rises to the reflow temperature, the first time The surface oxide tension of the reflow solder joint will support the shape of the solder joint, so that the appearance of the solder joint will not melt and collapse when the temperature reaches the melting point of the solder.