Optimisation de l'assemblage des connecteurs métalliques en cuivre

Abstract

In this study, microstructural and mechanical properties of copper-silver-copper joints were investigated. The low temperature associated with the sintering of silver nanoparticles generates an interesting opportunity for the development of production and repair methods when high temperatures should be avoided. The performances of the lap-joints produced by a new sintering technique were compared to those of a well-established brazing technique. For the sintering method, a silver nanoparticle product was chosen and sandwiched between two copper base metals, strongly clamped, and then heated up to the sintering temperature in a heating fixture designed for this project. The pressure was maintained during the process to maximize the contact surface between the base metal and the nanoparticles, while the assembly was kept at the sintering temperature in order to promote the solid-state diffusion and densification of the joint. The influence of temperature, pressure, time, overlap distance, and sintering atmosphere on microstructure development and mechanical properties was studied. For the brazing method, a copper-silver-phosphorus filler alloy (BCuP-5) in the form of foil was sandwiched between two copper base metals, slightly clamped, and then heated up to the brazing temperature using an acetylene torch. The influence of joint thickness and overlap distance on microstructure and mechanical properties were studied for this benchmark method. Brazing tests result in high mechanical strength for joint thicknesses greater than 150 μm. Also, tests relating to the overlap distance show that only a distance smaller than the copper bar thickness will lead to a failure in the joint. Sintering tests have shown the positive impact of the increase in the time, temperature, and sintering pressure on the mechanical strength of the joints. However, tests varying the sintering atmosphere revealed the detrimental role of oxygen, causing not only the desired degradation of organic components, but also leading to the oxidation of the joint. In this study, the mechanical strength of the sintered joints were 75% of that of the brazed joints.

Date	31 Jul 2016
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Vincent Demers (Supervisor)