On Simultaneous Sintering and Joining by Electric Current Activated Interfacial Eutectic Melting of Al–Si for Electronic Packaging Applications

Worldwide, exponential growth in energy consumption demands energy efficient and innovative material synthesis techniques. Conventional material joining processes for electronic applications such as brazing and soldering have limitations due to chemically distinct interface materials and multiple step processing. In this work, we have demonstrated a single step metal–ceramic joining and a single step metal–metal joining, without any interface material, using electric current activated eutectic melting during spark plasma sintering. Particulates of hypereutectic Al–Si, a potential candidate for electronic packaging of high-power density electronic components, were sintered and simultaneously joined with a solid alumina substrate. Similarly, hypereutectic Al–Si particulates were sintered and joined with solid aluminum alloy AA6061 as well. The selective interfacial eutectic melting between Al and Si, due to the resistance offered to electric current, aids in simultaneous joining with solid substrates apart from aiding in densification of particulate aggregates. The Al–Si regions at joint interfaces are characterized by finer eutectic silicon formation. The interlaminar shear strengths (ILSS) of Al–Si/AA6061 joints were nearly 3-fold (≈110 MPa) higher than that of Al–Si/Al2O3 joints due to the nature bonding. The absence of a chemically distinct interfacial layer and existence of finer microstructure at the joint interface resulted in excellent structural integrity. Our work paves the way for employing electric current assisted eutectic melting to create metal–ceramic and metal–metal joints.