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

CTS-0651752：高纵横比电铸微结构复制过程中的输运现象的解释近年来微结构的制造一直是人们关注的焦点。虽然诸如表面硅微加工和体硅蚀刻的技术被用作薄微结构的实用方法，但是诸如LIGA（光刻、电沉积和模制的德语单词的首字母缩写）的工艺提供了制造高纵横比微结构（HARM）的能力。然而，基于LIGA的制造的缺点是需要重复的同步加速器曝光和显影步骤，这既昂贵又耗时。LIGA过程的商业可行性需要经济的复制技术，以消除重复的同步辐射曝光和发展steps.INTELLECTUAL优点：响应上述需要，建议是一个合作调查与桑迪亚国家实验室的一种新技术，快速复制电铸微模具与整体微屏幕。该方法是基于注塑成型或热压成型的塑料复制品与整体金属丝网到一个LIGA制造的主微工具，以生产牺牲电铸模具，其中金属丝网作为导电基地和塑料功能提供所需的金属微部件的电沉积绝缘侧壁。由于电铸模具的许多塑料复制品可以从单个LIGA制造的微印模基底快速生产，因此避免了重复同步辐射曝光和显影的需要，从而产生经济和商业优势。提出了一个平衡的计算和实验研究的运输现象的制造过程中，系统地调查的各种工艺，材料和几何参数的影响。将发展一种全面的加工到零件的模拟能力，用来调查控制加工的各种现象的竞争效应，从而得出最佳的加工和材料设计。实验研究将集中在（a）表征微观聚合物流变学的材料被认为是提供所需的基本信息的建模;和（B）几个系统的处理运行，以验证计算模型，并证明从建模确定的最佳制度。该计划将通过开发快速和具有成本效益的微型零件制造能力，对MEMS行业产生重大的技术影响。更广泛的影响：该计划将通过培养两名研究生在一个重要的技术相关领域产生重大的教育影响。学生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女生或来自其他代表性不足群体的学生，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.