Investigations on Transport Phenomena Governing Replication of Electroforming Micromolds for Fabrication of High Aspect Ratio Microstructures

Cts-0651752：高纵横比微结构电铸微模复制输运现象的研究；微结构的制造是近年来备受关注的课题。虽然表面硅微加工和大块硅蚀刻等技术被用作薄微结构的实用方法，但LIGA（德语中光刻、电沉积和成型的首字母缩写）等工艺提供了制造高纵横比微结构（HARMs）的能力。然而，基于liga的制造的一个缺点是需要重复的同步加速器曝光和开发步骤，这既昂贵又耗时。LIGA工艺的商业可行性需要经济的复制技术，以消除重复的同步加速器暴露和开发步骤。智力优势：响应上述需求，建议与桑迪亚国家实验室合作研究一种具有集成微屏的电铸微模具快速复制的新技术。该工艺是基于在liga制造的主微工具上注射成型或热压成型带有整体金属屏的塑料复制品，以生产牺牲电铸模具，其中金属屏作为导电底座，塑料特征为所需金属微部件的电沉积提供绝缘侧壁。由于电铸模具的许多塑料复制品可以从一个单一的liga制造的微印记基地快速生产出来，因此不需要重复的同步加速器曝光和开发，从而具有经济和商业优势。提出了一项平衡的计算和实验研究，研究控制制造过程的输运现象，系统地研究各种工艺，材料和几何参数的影响。将开发一个全面的加工到零件的模拟能力，这将用于研究控制过程的现象的竞争效应，进而得出最佳的工艺和材料设计。实验研究将集中在(a)表征材料的微尺度聚合物流变学，以提供建模所需的基本信息；(b)几个系统的处理运行来验证计算模型，并演示从建模中确定的最佳制度。该计划将通过开发快速和具有成本效益的微型部件制造能力，对MEMS行业产生重大的技术影响。更广泛的影响：该计划将通过在一个重要的技术相关领域培养两名研究生而产生重大的教育影响。在项目期间，学生们将通过实习和与桑迪亚研究人员的密切互动获得宝贵的经验。将努力招收一名或两名学生，要么是女性，要么是来自其他代表性不足的群体，这将扩大社会影响。

CTS-0651752: INVESTIGATIONS ON TRANSPORT PHENOMENA GOVERNING REPLICATION OF ELECTROFORMING MICROMOLDS FOR FABRICATION OF HIGH ASPECT RATIO MICROSTRUCTURES; PI: PITCHUMANIPROJECT ABSTRACTFabrication of microstructures has been the subject of considerable attention in recent years. While techniques such as surface silicon micromachining and bulk silicon etch are used as practical methods for thin microstructures, processes such as LIGA (an acronym for the German words for lithography, electrodeposition, and molding) offer the capability to fabricate high aspect ratio microstructures (HARMs). A drawback of LIGA-based fabrication, however, is the need for repeated synchrotron exposure and development steps, which are both expensive and time-consuming. Commercial viability of the LIGA process requires economical replication technologies to eliminate the repetitive synchrotron exposure and development steps.INTELLECTUAL MERIT: Responding to the above-mentioned need, proposed is a collaborative investigation with Sandia National Laboratories on a new technique for rapid replication of electroforming micromolds with integral microscreens. The process is based on injection molding or hot embossing of plastic replicates with integral metallic screens onto a LIGA-fabricated master microtool, to produce sacrificial electroforming molds in which the metallic screen acts as the conducting base and the plastic features provide insulating sidewalls for electrodeposition of the desired metallic micropart. Since many plastic replicates of the electroforming molds could be produced rapidly from a single LIGA-fabricated microstamp base, the need for repetitive synchrotron exposure and development is obviated, thus resulting in an economical and commercial advantage. Proposed is a balanced computational and experimental study on the transport phenomena governing the fabrication process, to systematically investigate the effects of the various process, material, and geometric parameters. A comprehensive processing-to-part simulation capability will be developed, which will be used to investigate the competing effects of the phenomena governing the process and, in turn, to derive optimum process and material designs. Experimental studies will focus on (a) characterization of microscale polymer rheology of the materials considered to provide the needed fundamental information in the modeling; and (b) several systematic processing runs to validate the computational models and to demonstrate the optimum regimes identified from the modeling. The proposed program will have a significant technological impact in the MEMS industry through the development of capabilities for rapid and cost-effective fabrication of microparts.BROADER IMPACT: The program will have significant educational impact by training two graduate students in an important field of much technological relevance. The students will gain valuable experience through internships and close interactions with researchers at Sandia during the program. Efforts will be made to recruit one or both students who are either women or from other underrepresented groups, which will broaden the societal impact.