Thesis
Adhesion and deformation during thermocompression bonding of vertically aligned carbon nanotube turfs to metallized substrates
Washington State University
Master of Science (MS), Washington State University
2008
Handle:
https://hdl.handle.net/2376/103147
Abstract
process to mechanically transfer vertically aligned carbon nanotube (VACNT) turfs using thermocompression bonding has been developed for the use of VACNTs as thermal switches in MEMS devices. Mechanical transfer is accomplished by contacting a VACNT turf sputtered with 300 nm gold into a surface similarly coated in 300 nm of gold. A stress equal to the buckling stress of the turf is applied at 150 °C for a minimum of two hours. The VACNT turf transfers to the new surface upon separation. There are many issues to overcome before VACNT turfs can be implemented as a thermal switch. The greatest hurdle is a high contact resistance between a CNT and its contacting surface including contact resistance and Van der Waals interactions. VACNTs are grown using chemical vapor deposition (CVD), a process conducted at 700-800 °C, which is too high for VACNTs to be grown directly on MEMS devices. VACNT turfs also adhere readily to many surfaces due to local Van der Waals interactions, requiring control of the adhesive properties for VACNT turfs to be used as thermal switches. The average separation stress during mechanical transfer has been shown to be 0.42 MPa, and the strength of the new gold bond has been shown to be 0.55 MPa. Electrical measurements across a transferred VACNT turf has shown a conductivity independent of the imposed strain, up to strains in excess of 200%. Mechanical transfer has also been shown to be possible for arrays of VACNT turfs, as well as patterned transfer of segments off of a large VACNT turf.
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Details
- Title
- Adhesion and deformation during thermocompression bonding of vertically aligned carbon nanotube turfs to metallized substrates
- Creators
- Ryan David Johnson
- Contributors
- David F. Bahr (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Mechanical and Materials Engineering, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525057401842
- Language
- English
- Resource Type
- Thesis