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，例如超声波楔形键合和球键合、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至关重要。 虽然超声振动在键合形成中的重要作用已被公认，但其内在机制仍不清楚。对键合形成机制的基本理解的发展将导致改进的能力，以定制和优化新材料的键合工艺和改进的性能。这将专门解决电池和汽车电源应用中提高载流能力的目标，从而提高效率并降低能源需求。鉴于这一重要的重点，并与电子行业的合作伙伴关系，这个赠款机会与行业学术联络（GOALI）项目具有重大的行业影响，同时提供了一个丰富的环境，研究生培训和本科生接触工程研究。该项目的多层次的复杂性，使学生在不同层次的参与，包括本科生和研究生。PI和工业合作伙伴之间的密切合作为学生提供了一个独特的学习环境，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。基于模拟结果和实验分析的结合，PI将建立一个新的大学推广活动研讨会，旨在促进K-12和代表性不足的学生中的STEM领域。这个GOALI项目的目标是提供对超声波键合过程中键合形成的原子尺度机制的基本理解。这项研究的重点是核心假设，即通过清洁，无氧化物表面之间的原子雪崩形成的微焊缝的生长发生粘合。具体目标有两个：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的破坏机理; 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相结合的方法，能够在很短的键合时间内分析这种现象。研究的成功完成将导致对超声波键合过程中控制键合形成机制的基本原子相互作用的新见解。新开发的理论和实验技术，这些问题的应用，提高了理解的作用，表面力的形成中的微接触和有关的界面粘附的基本问题。

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.