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

电连接器是任何电子和电力系统中最关键的环节之一，因为它们需要为电子信号和/或电源连接提供可断开的路径。虽然连接器在当今的电子社会中越来越多地使用，但如果设计和制造不当，它们可能会受到腐蚀，从而导致性能下降。贵金属（如金或银）涂层可以减少腐蚀的发生，但显然非常昂贵。因此，目前的工作将研究使用石墨烯，一种极薄的碳片，作为夹层，将提高设备的可靠性，同时最大限度地减少腐蚀的可能性。石墨烯特别适合这种用途，因为它是一种机械强度高、导电、不透气的材料。因此，这项学术与工业联络（GOALI）合作研究项目将研究石墨烯在电连接器中的机械意义，这将有可能为下一代电子和电力系统开发低成本、高性能的连接器。石墨烯作为夹层的使用对其他蓬勃发展的应用也很重要，如柔性电子和可弯曲太阳能电池。该研究将在学术和工业合作环境中使用理论和实验工具来研究石墨烯在多层系统（如电连接器）中的应用。因此，它将探索有关二维材料在多层片层复合材料中的机械行为的未解决的问题。当大面积含石墨烯片层系统受到机械和/或热载荷时，可能产生的界面应力和滑移，人们对其了解相对较少。经典的层压分析方法不适用于本研究，因为(1)石墨烯表现出非线性弹性行为，(2)石墨烯与其接触膜之间存在有限的粘附（而不是完美的结合），以及(3)石墨烯的原子厚度使其无法容纳跨厚度的应变。为了研究石墨烯层间力学，本研究将结合一系列简单、可靠的粘附测量和实验验证的有限元分析（FEA）模拟，以确定薄片系统在拉伸、弯曲和热载荷下的响应。然后进行系统级接触电阻和疲劳分析，以确定和优化设备性能。这项工作将为石墨烯力学领域做出显著贡献，并有助于全面理解二维材料的力学。将采用一种新的多尺度方法将原子应变响应和纳米级粘附转化为连续体水平，这可以作为获得原子尺度材料行为宏观理解的框架。最后，开发一种强大的纳米划痕方法来确定石墨烯与任意衬底之间的粘附能，可以增加对控制sp2键合碳结构粘附力的因素的理解。

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.