GOALI/Collaborative Research: Improving the Performance of Electrical Connectors Using Extremely Thin Sheets of Graphene Sandwiched Between Metal Layers

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Electrical connectors are among the most critical links of any electronic and power system, as they are needed for providing a disconnectable path for electronic signals and/or power connections. Although connectors are being increasingly used in today's electronic society, they can succumb to corrosion which will lead to degraded performance if not designed and fabricated properly. Coatings of noble metals such as gold or silver reduce the occurrence of corrosion, but are obviously very expensive. Therefore the current work will investigate the use of graphene, an extremely thin sheet of carbon, as a sandwiched interlayer that will improve the reliability of the device while minimizing the possibility of corrosion. Graphene is exclusively suited for this use because it is a material that is mechanically strong, electrically conductive, and impermeable to gases. This Grant Opportunity for Academic Liaison with Industry (GOALI) collaborative research project will therefore study the mechanical implications of graphene in electrical connectors, which will potentially lead to the development of low-cost, high-performance connectors for next-generation electronic and power systems. The use of graphene as a sandwiched layer is also important for the benefit of other flourishing applications such as flexible electronics and bendable solar cells. The investigation will use both theoretical and experimental tools in a collaborative academic and industrial environment to research the use of graphene in multilayered systems such as electrical connectors. As such, it will explore unresolved questions regarding the mechanical behavior of a 2D material in a multilayered lamellar composite. Relatively little is known about the interfacial stresses and slip that may arise when a large-area graphene-containing lamellar system is subject to mechanical and/or thermal loads. A classical laminate analysis approach for this study is not applicable since (1) graphene exhibits nonlinear elastic behavior, (2) finite adhesion (as opposed to perfect bonding) exists between graphene and its contacting films, and (3) the atomic thinness of graphene precludes it from accommodating strain across its thickness. To investigate graphene interlayer mechanics, this study will combine a series of simple, robust adhesion measurements with experimentally-validated finite element analysis (FEA) simulations to determine the lamellar system response when exposed to tensile, bending, and thermal loads. System-level contact resistance and fatigue analysis will then be conducted to determine and optimize device performance. This work will serve as a notable contribution to the field of graphene mechanics and aid in the overall understanding of the mechanics of 2D materials. A novel multiscale approach will be taken to translate the atomistic strain response and nanoscale adhesion to the continuum level, which can be used as a framework for gaining a macroscopic understanding of atomic-scale material behavior. Finally, the development of a robust nanoscratch method to determine the adhesive energy between graphene and arbitrary substrates can lead to increased understanding of the factors that govern adhesion of sp2-bonded carbon structures.