Abstract: A method and a system of testing electronic components assemblies, each assembly comprising a multiplicity of tracks, each connecting a multiplicity of ports. The system may enable applying heat energy upon at least one part of the at least one track; measuring energy diffusion within a predefined time interval of the heated part of the track; calculating at least one distribution energy diffusion profile associated according to the measured diffusion, where the profile represents the diffusion of energy versus time; and identifying defects in the at least one track, according to the analysis of the diffusion profile.