To clarify the liberation mechanisms of electronic scrap (e-scrap) in the comminution process, we attempted to express the degree of liberation with a first-order kinetic equation by using impact energy obtained from discrete element method (DEM) simulations. Breakage energy measurements, comminution experiments, and DEM simulations were conducted on two types of e-scrap: connecting components and switching components. A high correlation was obtained between the results of first-order kinetic equations based on the specific impact energy from the DEM simulations and the degree of liberation observed in the comminution experiments. Furthermore, two cases of impact energy, total impact energy and impact energy above the threshold value required for liberation by breakage energy measurements, were compared. For connecting components, the latter showed higher correlation in the initial stage of comminution, while the former showed higher correlation after a certain progress of comminution. This suggests that after certain progress of comminution, structural weak points were created, and the plastics were destructively separated by smaller impact energy. On the other hand, for switching components, a high correlation was consistently obtained for impact energy above the threshold value. This might be because the metal parts are spot-jointed with a certain strength. The above results suggest that the degree of liberation of e-scrap can be expressed by a first-order kinetic equation based on the specific impact energy and that the liberation behavior can be examined by the correlation analysis of first-order kinetic equation using a threshold value.