Date Approved

9-30-2022

Embargo Period

10-3-2022

Document Type

Thesis

Degree Name

M.S. Mechanical Engineering

Department

Mechanical Engineering

College

Henry M. Rowan College of Engineering

Advisor

Wei Xue, Ph.D. and Jeffrey Hettinger, Ph.D.

Committee Member 1

Samuel Lofland, Ph.D.

Committee Member 2

Smitesh Bakrania, Ph.D.

Subject(s)

Thin films--Testing; Electronics--Manufacturing

Disciplines

Materials Science and Engineering | Mechanical Engineering | Physics

Abstract

The motivation behind this research is to improve the interfacial layer bonding of metallic thin films to PDMS substrates with the aid of a buffer layer. The physical vapor deposition (PVD) technique of sputtering was used to deposit bilayer thin films of silver (Ag) and silicon dioxide (SiO2) on PDMS. Two chamber pressures were used in this work, 5 and 20 mTorr, to investigate the role of this parameter in determining the interfacial adhesion and the role in determining the resistance sensitivity. Studies of the surface energy and increased bonding strength for metallization are carried out. Surface characterization using atomic force microscopy (AFM) and scanning electron microscopy (SEM) was performed on PDMS and SiO2 to better understand the topography of the deposited SiO2 thin film. To validate the integrity of the thin film layers on PDMS, adhesion measurements were conducted on the film using the ASTM D3359 test which involves the application of 3M cellophane tape to the coating surface followed by tape removal. Strain in the coatings were measured. Samples with Ag films deposited using a chamber pressure of 5 mTorr averaged a maximum strain of 20% while those deposited at 20 mTorr averaged 15%. Furthermore, photolithography and wet etching were used to pattern the films to create strain gauge sensors. This work has demonstrated that using thin layers on PDMS coated with SiO2 and Ag provides a viable technique to manufacture flexible and stretchable electronics.

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