A process for assembling a rigid-flex printed circuit board (PCB) is presented. During operation, the process receives rigid-flex PCBs that are to be coupled together, wherein a rigid-flex PCB includes flexible PCBs coupled to rigid PCBs. The process then places the PCBs onto a carrier which is configured to: align the PCBs so that bond regions located on the flexible PCBs overlap with bond regions located on corresponding flexible PCBs, and apply pressure to the overlapped bond regions. The process then sends the carrier through a reflow oven which reflows solder on the PCBs so that the components become mechanically and electrically coupled to the PCBs. The temperature profile generated by the reflow oven and the pressure applied by the carrier cures and sets an anisotropic conductive film located in the bond regions so that the overlapped flexible PCBs become mechanically and electrically coupled together.