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，柔性电子设备引起了极大的兴趣。限制其发展的一个关键因素是将各种高质量的硅基电子元件与柔性基板集成。这种集成是困难的，因为使用现有的制造工艺无法制造将硅芯片与柔性基板接合所需的小电连接。一种称为微尺度选择性激光烧结（microscale-SLS）的新工艺已经开发出来，它提供了克服这种制造限制的潜力，通过成功地烧结（融合）纳米级颗粒，在几乎任何基板上创建具有微米级分辨率的复杂三维金属部件。目前，该工艺的商业可行性受到缺乏对控制烧结工艺的基本物理学的理解以及无法准确模拟工艺结果的限制。该研究项目将通过开发有关纳米级物理学对微观尺度SLS过程中的质量和能量转移以及最终最终零件完整性的影响的基础科学来克服这一限制。由于该项目是恩智浦美国公司与德克萨斯大学奥斯汀分校（UTA）之间的产学合作项目，因此将为研究生和本科生提供教育体验和行业培训机会。通过高级设计项目和移动的计算和移动的能源技术纳米制造系统（NASCENT）中心的高中研究员项目，将特别关注为来自工程背景的学生提供机会和培训。该项目的研究目标是了解纳米颗粒薄层（NP）被选择性地激光烧结以实现分辨率约为1微米的3D结构。中心假设是，纳米级的影响，如表面扩散，近场辐射，光散射占主导地位的部分形成过程中的微尺度SLS，因此必须考虑到精确建模微尺度SLS部分形成。该项目的具体目标是确定（1）在微尺度SLS过程中NP重塑的机制，（2）NP粉末床中的光穿透/吸收，以及（3）NP粉末床内的热传递，以及（4）确定NP级机制和建模部件形成的连续级参数之间的关系。一个多尺度的计算建模方法的宏观尺度选择性激光烧结过程（MCM-SLS）将被用来构建一个模型的微观尺度SLS零件形成过程。预期微尺度SLS工艺的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部件的最佳工艺参数所需的时间，（2）提高对部件设计如何影响部件质量/产量的科学理解，以及（3）允许设计者估计部件质量（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，在其工厂使用原型微型SLS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.