Mechatronic systems designed to comply to new EU directives are studied through interconnections by electronic or photonic probes, SEM, TEM, SE or 3D Tomography. Leaded and lead free modules assembled by standard interconnection technologies are studied for robustness relative to thermal accelerated life tests. Results obtained from JEOL 6060LV SEM and Optical Microscopy show that although slow growth rate of inter-metallics (IMC) is consistent with expected reliability, they are responsible for propagation of cracks especially in the presence of gold on PCB side. Innovative Low Temperature Joining (LTJ) technology applied to nano or micro silver pastes which should reduce IMC effects are tested on mechatronic systems. Results obtained from SEM, TEM and 3D Tomography will be shown as well as non destructive Spectroscopic Ellipsometry studies of samples. Pressureless LTJ technology is unsuitable for robust interconnection.