Committee Members:
Prof. Vanessa Smet, ME (Advisor)
Prof. Rao Tummala, MSE, ECE (Co-Advisor)
Prof. Preet Singh, MSE
Prof. Eric Vogel, MSE
Jobert van Eisden, PhD, MKS Instruments, Inc.

Magneto-Assisted Electrodeposition of Copper-Graphene Composites: A New Method to Enhance Nanostructure and Properties of Copper in Advanced Packaging
 

Abstract:

The continuous densification of electronic systems has been driving the need for advanced materials with tailorable nanostructures and properties beyond standard electrodeposited copper. Graphene reinforcement of metals has recently gained momentum to not only enhance electrical, thermal, and mechanical properties but also control the metal matrix composites’ grain structure and its evolution at the nanoscale. Of particular interest, copper-graphene composites have been fabricated by electrodeposition with graphene particles suspended in the copper electrolyte and acting as inert additives. The final composition is thereby mainly governed by the initial volume loading of graphene in the plating bath and any applied agitation methods, giving, so far, limited returns in terms of property improvements. Achieving the theoretical maximum material performance requires 1) a high graphene relative content, 2) homogeneous dispersion of graphene throughout the composite, 3) and controlled alignment of graphene within the material. To address this grand challenge, a novel magneto-electrodeposition process is proposed wherein a low-magnitude magnetic field is applied during the plating. Magnetic fields have different, competing effects on electrodeposition depending on their orientation with respect to the plating current direction: Magnetic fields have different, competing effects on electrodeposition depending on their orientation with respect to the plating current direction: 1) graphene aligns along the magnetic field flux lines owing to its diamagnetic properties; 2) the magnetohydrodynamic (MHD) effect allows for increased, localized agitation and, therefore, more uniform distribution of graphene in the copper matrix, and 3) the magnetic field influences ion movement within the electroplating solution, leading to greater graphene content. 

This research focuses on assessing the effect of applied magnetic fields on electrodeposited copper-graphene composites in terms of their material composition, microstructure, morphology, and subsequent electrical, mechanical, thermal, and thermomechanical properties for use in next-generation advanced packaging. Key results will demonstrate the effects of magnetic fields on graphene, experimental setup, methodology, and proof-of-concept for magneto-electrodeposition of copper-graphene composites, characterization of morphology and mechanical, electrical, and thermal property improvements, theoretical modeling of potential property improvements of graphene-reinforcement of copper, and finite-element modeling to evaluate the potential benefits of copper-graphene composites in advanced packaging applications.