Session: 08-01: Micro/Nanoscale Heat Conduction

Paper Number: 131227

131227 - The Morphology Regulation Mechanism of Microdroplet During the Flexible Fevices Printing With Molten Metal Droplet. 

Abstract: 

The molten metal droplet printing technology can effectively realize a precise preparation of complex electronic devices at the micro scale by relying on the metallurgical bonding among the tiny molten metal droplets, which can improve the metallographic structure and mechanical properties of the fabricated parts. In this paper, the interaction process between metal droplets and movable / heterogeneous wettability substrates during the preparation of electronic devices is studied based on the coupled level set volume fluid method (CLSVOF) and equivalent heat capacity method. The influence of the micro-bubbles, wall infiltration characteristics and other factors on the impingement spreading flow of metal droplets and their heat transfer cooling process is also investigated. The evolution mechanisms of droplet geometry and the distribution characteristics of droplet internal temperature and heat flow density during the impingement spreading process are discussed. Results show that the microbubbles inhibit the spread of molten metal droplet. Under the same conditions, the spreading radius of hollow metal droplet is smaller than that of solid droplet, and their spreading height is higher than that of solid droplet. A larger wall contact angle for the same impingement mode at the same moment corresponds to a smaller droplet spreading radius and the higher the spreading height. With the participation of microbubbles, the heat transfer cooling process inside metal droplet becomes slow and demonstrates a less uniform temperature and heat flow density distribution. A high-temperature region is easily formed inside droplet under superlyophobic wall conditions, which triggers an uneven heat transfer cooling process at the bottom of the droplet. In addition, a scheme to regulate the surface behavior of printed microdroplets with lyophilic high-adhesion region to anchor the droplets and lyophobic low-adhesion environment to provide a physical barrier to confine the droplet morphology was developed. The pattern modification scheme has an obvious optimization effect for the droplet forming and its heat exchange process in the process of metal droplet printing. Basis on the ensuring the radial dimensional accuracy and sphericity of the molten droplet molding, the rebound and oscillation behavior of the molten droplet is effectively suppressed. The stabilizing efficiency of droplet printing is greatly enhanced and further improves the heat transfer performance of the droplet. The results further enrich the theory of precise regulation of the dynamic behavior of droplet surfaces. Not only can it be used as a new strategy for universal high-precision printing and droplet control, but it will also promote the application and development of technologies in numerous fields, such as liquid transport and microfluidics.

Presenting Author: Nan Zheng Beijing University of Technology

Presenting Author Biography: Dr. Nan Zheng is mainly engaged in the research related to computational fluid dynamics and numerical heat transfer. in September 2021, he entered the Faculty of Materials and Manufacturing of Beijing University of Technology (BJUT) to pursue a PhD degree in mechanics. Until now, he has participated in several research projects in the direction of microfluidics and metal additive manufacturing under the National/Beijing Natural Science Foundation. He has published 15 SCI/EI research papers, including several research-oriented papers as the first author in top journals in the field of thermodynamics and fluid mechanics, such as International Journal of Heat and Mass Transfer and Physics of Fluids.

Authors:

Nan Zheng Beijing University of Technology
Zhaomiao Liu Beijing University Of Technology
Xiang Wang Beijing University Of Technology
Yan Pang Beijing University Of Technology