A process for molding a back side wafer singulation guide is disclosed. Structures for heat mitigation include an overmold formed over a contact surface of a device layer of a wafer, covering bump structures. The overmold and bump structures are thinned and planarized, and the overmold provides an underfill to increase interconnect reliability of a semiconductor die in a flip chip bonded package. However, visibility of singulation guides on the contact surface is obstructed. A channel is formed extending through the device layer and into the handle layer, and is filled with the overmold. The handle layer is replaced with a thermally-conductive molding layer formed on the back side for dissipating heat generated by semiconductor devices. The thermally-conductive handle is thinned until the overmold in the channel beneath the device layer is exposed. The exposed overmold provides a visible back side singulation guide for singulating the wafer.