GOALI: Understanding the Mechanisms of Ultrasonic Bonding at Atomic Scale

超声波振动对于各种固态键合技术是必不可少的，例如超声波楔和球键合、倒装芯片键合、电池焊接和超声波增材制造。这些工艺在消费电子、国防、汽车和航空航天工业中是必不可少的。虽然超声振动在键形成中的重要作用已被充分认识，但其潜在的机制仍在很大程度上是未知的。对键形成机制的基本理解的发展将导致对新材料的定制和优化键合过程的能力的提高和性能的改善。这将特别解决电池和汽车电源应用中提高载流能力的目标，从而提高效率并减少能源需求。考虑到这一重要重点，以及与电子行业的合作伙伴关系，这个与行业学术联络的资助机会（GOALI）项目具有重大的行业影响，同时为研究生培训和本科生接触工程研究提供了丰富的环境。项目的多层次复杂性使得不同层次的学生，包括本科生和研究生都能参与进来。pi与工业合作伙伴之间的密切合作为学生提供了独特的学习环境，为他们提供了与当地硅谷微电子行业需求密切相关的经验。基于建模结果和实验分析的结合，pi将建立一个新的大学外展活动研讨会，旨在促进K-12和代表性不足的学生的STEM领域。这个GOALI项目的目标是提供对超声键合过程中控制键形成的原子尺度机制的基本理解。这项研究的核心假设是，在干净、无氧化物的表面上，原子雪崩形成的微焊缝通过生长形成键合。本研究有两个具体目标：1)通过实验、分析和有限元分析相结合的方法，研究超声振动过程中氧化膜断裂的性质。2)通过分子动力学和实验分析相结合的方法研究导致微焊缝形成和生长的原子运动机制。采用计算建模和实验方法相结合，可以在很短的粘合时间内对现象进行分析。该研究的成功完成将导致对超声键合过程中控制键形成机制的基本原子相互作用的新见解。将新开发的理论和实验技术应用于这些问题，增强了对表面力在微接触形成中的作用以及与界面粘附有关的基本问题的理解。

Ultrasonic vibration is essential for various solid-state bonding techniques, such as ultrasonic wedge and ball bonding, flip-chip bonding, battery welding, and ultrasonic additive manufacturing. These processes are essential in the consumer electronics, defense, automotive and aerospace industries. Although the essential role of ultrasonic vibration in bond formation is well recognized, the underlying mechanisms are still largely unknown. Development of a fundamental understanding of bond formation mechanisms would result in an improved ability to tailor and optimize bonding processes for new materials and improved properties. This would specifically address the goal of improved current-carrying capabilities in battery and automotive power applications, thereby improving efficiency and reducing energy demand. Given this important focus, and the partnership with the electronics industry, this Grant Opportunities for Academic Liaison with Industry (GOALI) project has significant industry impact while simultaneously offering a rich environment for graduate student training and exposure of undergraduates to engineering research. The multi-level complexity of the project enables involvement of students at different levels, including undergraduate and graduate students. The close collaboration between the PIs and the industrial partner provides a unique learning environment for the students, preparing them with very relevant experience closely aligned with the needs of local Silicon Valley's microelectronic industry. Based on the combination of modeling results and experimental analysis, the PIs will establish a new workshop for university outreach activities targeting promotion of STEM field among K-12 and underrepresented students.The objective of this GOALI project is to provide fundamental understanding on the atomic-scale mechanisms that govern bond formation during ultrasonic bonding. The research focuses on the central hypothesis that bonding occurs through growth of the microwelds that form by an atomic avalanche between clean, oxide-free surfaces. Two specific objectives are followed:1) Investigating the nature of oxide film breakage during ultrasonic vibration through a combination of experimental, analytical and finite element analysis.2) Investigating mechanism of atomic movement that leads to microwelds formation and growth through a combination of molecular dynamics and experimental analysis.Employing a combination of computational modeling and experimental approaches enables analysis of the phenomena during a very short period of bonding time. The successful completion of the research will lead to new insights into the fundamental atomic interactions that govern bond formation mechanisms during ultrasonic bonding. The application of the newly developed theoretical and experimental techniques to these problems enhances the understanding of the role of surface forces in the formation of micro-contacts and the fundamental issues pertaining to interfacial adhesion.