A method includes performing a first laser shot on a first portion of a top surface of a first package component. The first package component is over a second package component, and a first solder region between the first package component and the second package component is reflowed by the first laser shot. After the first laser shot, a second laser shot is performed on a second portion of the top surface of the first package component. A second solder region between the first package component and the second package component is reflowed by the second laser shot.