GOALI: Manufacturing USA: Determining the Role of Nanoscale Physics in the Microscale Selective Laser Sintering Process using a Multiscale Computational Modeling Approach

由于用于健康监测的可穿戴设备的快速扩展和物联网的兴起，灵活的电子设备引起了人们的极大兴趣。限制它们发展的一个关键因素是各种高质量的硅基电子元件与柔性基板的集成。这种集成是困难的，因为硅芯片与柔性基板接口所需的小电气连接不能使用现有的制造工艺制造。一种名为微尺度选择性激光烧结(MicroScale-SLS)的新工艺被开发出来，它通过成功地烧结(熔化)纳米颗粒在几乎任何衬底上制造出具有微米级分辨率的复杂的三维金属零件，从而提供了克服这一制造限制的可能性。目前，由于缺乏对控制烧结过程的基本物理原理的了解，以及无法准确地对过程结果进行建模，该过程的商业可行性受到限制。这个GOALI学术联络机会(GOALI)研究项目将通过发展有关纳米物理对微尺度SLS过程中的质量和能量传递的影响的基础科学来克服这一限制，并最终实现最终的完整性。由于该项目是恩智浦美国公司和德克萨斯大学奥斯汀分校(UTA)之间的行业和大学合作项目，它将为研究生和本科生提供教育经验和行业培训机会。将通过高级设计项目和移动计算和移动能源技术纳米制造系统(NEASCENT)中心的高中研究员计划，特别关注为工程学背景不足的学生提供机会和培训。该项目的研究目标是了解有关纳米颗粒薄层被选择性激光烧结以实现分辨率约为1微米的3D结构的机制的基础科学。中心假设是表面扩散、近场辐射和光散射等纳米尺度效应主导了微尺度SLS的部分形成过程，因此必须考虑纳米效应才能准确地模拟微尺度SLS部分形成。本项目的具体目标是确定(1)微尺度SLS过程中的NP重塑机制，(2)NP粉末床层中的光穿透/吸收机制，以及(3)NP粉末床层内的热传递，以及(4)确定NP级机制与用于模拟零件成形的连续体级参数之间的关系。利用宏观选区激光烧结(MCM-SLS)多尺度计算建模方法，建立了微观选区激光烧结零件成形过程的模型。预计微尺度SLS工艺精确模型的开发将通过以下方式对三维微尺度互连结构的制造产生积极影响：(1)减少确定微尺度SLS零件的最佳工艺参数所需的时间；(2)提高对零件设计如何影响零件质量/成品率的科学理解；以及(3)允许设计者估计零件质量(强度、形状、导电性等)。在制造之前。计算模型将与恩智浦美国公司合作，在其设施中使用微型SLS原型系统进行验证。

Flexible electronic devices are of great interest due to the rapid expansion of wearable devices for health monitoring and the rise of the Internet-of-Things. One key factor limiting their development is the integration of diverse high-quality, silicon-based electrical components with flexible substrates. This integration is difficult because the small electrical connections needed to interface the silicon chips with flexible substrates cannot be fabricated using existing manufacturing processes. A new process called microscale selective laser sintering (microscale-SLS) has been developed which offers the potential to overcome this manufacturing limitation by successfully sintering (fusing) nanoscale particles to create complex, three-dimensional, metal parts with micron-scale resolution on almost any substrate. Currently the commercial viability of the process is limited by a lack of understanding of the underlying physics governing the sintering process, and an inability to accurately model the process outcomes. This Grant Opportunities for Academic Liaison with Industry (GOALI) research project will overcome this limitation by developing fundamental science regarding the impact of nanoscale physics on the mass and energy transfer within the microscale-SLS process, and ultimately the final part integrity. As this project is an industry-university collaborative effort between NXP USA and the University of Texas Austin (UTA), it will provide both educational experiences and industrial traineeships for graduate and undergraduate students. A particular focus on providing opportunities and training to students from underrepresented backgrounds in engineering will be pursued through senior design projects and the Nanomanufacturing Systems for Mobile Computing and Mobile Energy Technologies (NASCENT) Center's High School Fellows program.The research objective of the project is to understand the fundamental science regarding mechanisms by which thin layers of nanoparticles (NPs) are selectively laser sintered to realize 3D structures with resolutions of around one micron. The central hypothesis is that nanoscale effects such as surface diffusion, near-field radiation, and light scattering dominate the part-formation process in microscale-SLS, and therefore must be considered to accurately model microscale-SLS part formation. The specific aims of this project are to determine the mechanisms for (1) NP reshaping during the microscale-SLS process, (2) light penetration/absorption in the NP powder bed, and (3) heat transfer within the NP powder bed, and (4) to determine the relationship between NP-level mechanisms and continuum-level parameters for modeling part formation. A multiscale computational modeling approach for the macroscale selective laser sintering process (MCM-SLS) will be leveraged to construct a model of the microscale-SLS part formation process. It is expected that the development of accurate models of the microscale-SLS process will have a positive impact on the manufacturing of three-dimensional microscale interconnect structures by (1) reducing the time required to determine the optimal process parameters for microscale-SLS parts, (2) improving the scientific understanding of how part design affects part quality/yield, and (3) allowing designers to estimate part quality (strength, shape, conductivity, etc.) before fabrication. The computational models will be validated in collaboration with NXP USA using a prototype microscale-SLS system at their facilities.