Abstract The neutron spin resonance is a collective magnetic excitation that appears in the unconventional copper oxide, iron pnictide and heavy fermion superconductors. Although the resonance is commonly associated with a spin-exciton due to the d ( s ± )-wave symmetry of the superconducting order parameter, it has also been proposed to be a magnon-like excitation appearing in the superconducting state. Here we use inelastic neutron scattering to demonstrate that the resonance in the heavy fermion superconductor Ce 1− x Yb x CoIn 5 with x =0, 0.05 and 0.3 has a ring-like upward dispersion that is robust against Yb-doping. By comparing our experimental data with a random phase approximation calculation using the electronic structure and the momentum dependence of the "Equation missing" -wave superconducting gap determined from scanning tunnelling microscopy (STM) for CeCoIn 5 , we conclude that the robust upward-dispersing resonance mode in Ce 1− x Yb x CoIn 5 is inconsistent with the downward dispersion predicted within the spin-exciton scenario.