Date of Award

August 2020

Document Type


Degree Name

Master of Engineering (MEngr)


Mechanical Engineering

Committee Member

Joshua B Bostwick

Committee Member

John R Saylor

Committee Member

Oliver J Myers


Soldering is a commonly used method to join two non-ferrous metals together, such as bonding copper wires or electrical components to circuit boards. Flux is typically used to remove the oxide layer on the metallic substrate but can release harmful chemicals and degrade the solder joint quality. Ultrasonic Assisted Soldering (UAS) was developed as an alternative to traditional soldering which eliminates the need for flux by using ultrasonic vibrations to nucleate microbubbles which remove the oxide layer during cavitation. The interaction between the applied acoustic field and solder melt affects the wetting properties of the solder joint by increasing the wetted area. A model is developed to predict the solder bead geometry, as it depends upon capillarity, gravitational effects, and the acoustic radiation pressure due to ultrasonic vibrations. Numerical results are compared with careful experiments using the automated UAS system to generate solder lines that are imaged with optical profilometry to quantify the degree of wetting. The agreement between theory and experiment is good and we show the wetted width can be predicted as a function of the input ultrasonic power. This capability is greatly needed to automate the UAS process for precision soldering and is a major advance for the manufacturing industry.



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