11/15/2021
By Sokny Long

The Francis College of Engineering, Department of Chemical Engineering, invites you to attend a Master’s thesis defense by Qingliu Wu on “Selective Coating of Low Melting Temperature Tin/Indium Nanosolders on Multi-Segment Nanowires.”

Master’s Candidate: Qingliu Wu
Defense Date: Tuesday, Nov. 23, 2021
Time: 3 to 5 p.m. EST
Location: This will be a virtual defense via Zoom. Those interested in attending should contact the student, Qingliu_Wu@student.uml.edu, and committee advisor, Zhiyong_Gu@uml.edu, at least 24 hours prior to the defense to request access to the meeting.

Committee Chair (Advisor): Zhiyong Gu, Ph.D., Professor, Department of Chemical Engineering, University of Massachusetts Lowell

Committee Members:

  • Stephen Lam, Ph.D., Assistant Professor, Department of Chemical Engineering, University of Massachusetts Lowell
  • Fuqiang Liu, Ph.D., Associate Professor, Department of Mechanical Engineering, University of Massachusetts Lowell

Brief Abstract:
Recent developments in electronics, such as flexible electronics, have driven the need for advanced materials to create interconnections and to join electronic components. Polymer substrates, nanotechnology, and other advances are necessitating the need for low-temperature, nanoscale joining methods to create the electronic devices of the future. In this work, a chemical reduction technique was used to deposit tin-indium (Sn-In) nanosolders onto multi-segmented nanowires. The coating was selectively limited to certain segments of the nanowires via an azelaic acid monolayer. The average composition of the coating, as determined by energy-dispersive spectroscopy, was about 83.0 wt% Sn and 17.0 wt% In. Scanning electron microscopy (SEM) was used to examine the morphology of the coating and confirm the selectivity of the coating method. The coated wires were then studied as a method for nanoscale, low-temperature soldering. Visual inspection via SEM of coated nanowires heated to peak temperatures ranging from 130°C to 200°C showed the ability for the coating to melt and form interconnections between adjacent wires. Further feasibility studies were conducted by magnetically aligning the coated nanowires onto interdigitated electrodes. SEM inspection of the heated samples confirmed the ability of the nanowires to be aligned heat-to-tail, so as to bridge the gaps of the electrode, and the ability of the nanosolder coating to melt and create solder joints.

All interested students and faculty members are invited to attend the online defense via remote access.