Constructing squeal-free disk brakes is a major challenge for automotive engineers. It has been observed from experiments that breaking the symmetry of the brake rotor may help to avoid self-excited vibrations. But this approach has not been completely successful. Analytical models for disk brakes suggest that multiple eigenfrequencies of the system, in particular of the rotor, increase the sensitivity for self-excited vibrations. In order to stabilize the brake, it is necessary to split up all rotor eigenfrequencies in the relevant frequency range, which is not an easy task. In this paper, structural optimization is used to design brake rotors without multiple eigenfrequencies. The heights and positions of the ventilation channels of the brake rotor are used as optimization variables. The underlying problem is an inverse problem, maximizing the distance between eigenfrequencies subject to constraints due to the design requirements. For the optimization process we assume that the global structure of the brake rotor is still within the scope of plate theory. This significantly reduces the degrees of freedom needed to model the structure, since global shape functions can be used in a Ritz discretization instead of a huge finite element model. The underlying idea of the procedure is similar to approaches from structural health monitoring, where from the vibrational behavior one draws conclusions on the geometry of the structure, i.e. detects defects in the structure.