Ecodesign of sintered interonnects : reliability and repairability improvement

Job description: Metallic sintering, particularly silver-based or copper-based sintering, is a component interconnects technique alternative to soldering, used in particular in the field of power electronics. The main advantages of this technique are first of all its very high thermal and electrical conductivity, but also the fact that the sintered interconnection (with a process realized for example at 250°C) is then capable of withstanding much hotter thermal cycles without alteration. On the other hand, this last advantage is associated with a major disadvantage: since sintering is irreversible, it is currently impossible to dismantle a sintered component to repair or recycle it. One of the objectives of this thesis is therefore to study the interconnects from a global point of view (with the metallic finishing layers of the chips and the substrate) in order to see how to make the interconnects removable while maintaining a sintered joint. On the other hand, in order for the study to make sense from an environmental point of view, it is necessary that the sintering carried out be reliable and durable. However, the direct (finishing materials of the chips and the substrate) and indirect (main materials of the chip and the substrate) surroundings have a strong impact on the quality of the sintered joint, and therefore on its performance and durability. Indeed, the materials in direct contact with the sintering influence the diffusion of silver and therefore the density of the joint, and the main materials of the chip and the substrate generate thermomechanical stress on the paste during sintering, which impacts its morphology. These aspects will be studied in detail from a theoretical and experimental point of view, taking into account the impact of adding a layer allowing the dismantling of the interconnects. Life Cycle Analysis (LCA) type studies will be carried out in order to judge the environmental relevance of the choices made, particularly in the case where reparability could negatively impact durability.

Your profile: Ingénieur matériaux / électronique