After reballing, take the mold down from the base and remove the reballing stencil. Heat the lower layer on the heating platform at 165℃. Once solder balls have shaped up completely, power off the heating platform.

Cool for 5 minutes. Apply some BGA Paste Flux to the bonding pad and get the upper layer in position.

Then power on the heating platform. With the temperature reaching 165℃, continue heating for 2 minutes.