Microstructure variation in the ultrasonic bonding process between Al sheets observed by in-situ transmission electron microscopy.

In-situ transmission electron microscopy (TEM) is developed to observe the microstructure evolution during ultrasonic bonding. It was found that many nanoparticles were generated and moved around between the Al sheets' contact regions in a random way. Gaps between the joining partners were buried by the nanoparticles, which facilitated the formation of the bonded interface. It was shown that the in-situ TEM observation technique provides a new way to investigate the ultrasonic bonding process. [Display omitted] [ABSTRACT FROM AUTHOR]