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

电气连接器是任何电子和电力系统中最关键的环节之一，因为它们是为电子信号和/或电源连接提供可断开路径所必需的。尽管连接器在当今电子社会中的使用越来越多，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。贵金属涂层，如金或银，减少了腐蚀的发生，但显然非常昂贵。因此，目前的工作将研究使用石墨烯作为夹层，这将提高设备的可靠性，同时将腐蚀可能性降至最低。石墨烯是一种非常薄的碳片。石墨烯特别适合于这种用途，因为它是一种机械强度高、导电性好、不透气的材料。因此，GOALI合作研究项目将研究石墨烯在电连接器中的机械影响，这可能会导致为下一代电子和电力系统开发低成本、高性能的连接器。使用石墨烯作为夹心层，对于柔性电子产品和可弯曲太阳能电池等其他蓬勃发展的应用也很重要。这项研究将在合作的学术和工业环境中使用理论和实验工具来研究石墨烯在电连接器等多层系统中的使用。因此，它将探索关于多层片状复合材料中2D材料的机械行为的悬而未决的问题。对于大面积含石墨烯的层状体系在机械和/或热载荷作用下可能产生的界面应力和滑移，人们知之甚少。由于(1)石墨烯表现出非线性弹性行为，(2)石墨烯与其接触的薄膜之间存在有限粘合(而不是完美结合)，以及(3)石墨烯的原子厚度使其无法适应厚度方向的应变，因此经典的层合分析方法不适用于本研究。为了研究石墨烯的层间力学，本研究将结合一系列简单、可靠的附着力测量和实验验证的有限元分析(FEA)模拟，以确定在拉伸、弯曲和热负载下的层状体系响应。然后将进行系统级接触电阻和疲劳分析，以确定和优化设备性能。这项工作将是对石墨烯力学领域的显著贡献，并有助于全面理解2D材料的力学。一种新的多尺度方法将原子应变响应和纳米尺度的粘附性转换到连续介质水平，这可以作为获得原子尺度材料行为的宏观理解的框架。最后，开发一种可靠的纳米裂缝方法来确定石墨烯和任意衬底之间的附着能，可以增加对控制sp2键合碳结构附着的因素的理解。

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.