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

CTS-0651752：电铸微模复制用于制造高深宽比微结构的传输现象研究PI：PITCHUMANIPROJECT近年来微结构的制造一直是人们非常关注的主题。虽然表面硅微机械加工和体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、电沉积和模塑的首字母缩写)等工艺提供了制造高深宽比微结构(HARM)的能力。然而，基于LIGA的制造的缺点是需要重复同步加速器曝光和显影步骤，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，以消除重复的同步辐射曝光和显影步骤。电子优点：响应上述需求，建议与桑迪亚国家实验室合作研究一种新的技术，用于快速复制集成微网的电铸微型模具。该工艺基于将带有整体金属网的塑料复制品注射成型或热压印到LIGA制造的标准微工具上，以生产牺牲电铸模具，其中金属网充当导电底座，塑料部件为所需的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单个LIGA制造的微型印模基座快速生产，因此不需要重复的同步曝光和显影，从而产生了经济和商业优势。提出了一种关于控制制造过程的传输现象的平衡计算和实验研究，以系统地研究各种工艺、材料和几何参数的影响。将开发一种全面的从加工到零件的模拟能力，用于调查支配该过程的现象的竞争影响，进而得出最佳的过程和材料设计。实验研究将集中在(A)被认为在建模中提供所需基本信息的材料的微尺度聚合物流变学的表征；以及(B)几个系统的处理运行，以验证计算模型并展示从建模中确定的最佳状态。拟议中的计划将通过开发快速和经济高效地制造微部件的能力，在MEMS行业产生重大的技术影响。BROADER影响：该计划将通过在一个与技术密切相关的重要领域培训两名研究生，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女性学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.