Microstructure and mechanical properties of high-quality AlN/Cu joints brazed by a novel AgCuTi plus AlCoCrFeNi2.1 composite brazing alloy

AlN/Cu combinations offer high power electronic devices superior compatibility with large current transport and high voltage resistance, making them promising heat-dissipation candidates for electronic packaging. AlCoCrFeNi2.1 high-entropy alloy (HEA), known for its excellent mechanical properties, was incorporated into the traditional AgCuTi filler for brazing AlN and Cu in this work. The obtained AlN/Cu brazed joints exhibited homogeneous interfacial phases and high bonding strength. The maximum shear strength (277 MPa) was achieved when brazed at 850 degrees C for 5 min via composite filler containing 0.5 wt% AlCoCrFeNi2.1, which was 156 % higher than that brazed with single AgCuTi fillers. Enhanced mechanical properties were obtained by dispersion strengthening of intermetallic compounds (IMCs) resulting from the introduction of a medium AlCoCrFeNi2.1 concentration (less than 1 wt%) in filler alloys under tailored brazing parameters.