Indium plated carbon nanotubes pattern on flexible substrate defined by ink-jet printing
- PDF / 842,423 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 96 Downloads / 172 Views
Indium plated carbon nanotubes pattern on flexible substrate defined by ink-jet printing Pingye Xu1 and Michael C. Hamilton1 1 Department of Electrical and Computer Engineering, Auburn University, Auburn, Alabama 36849
ABSTRACT Carbon nanotubes patterns of micron-level resolution have been achieved using inkjet printing of DNA and SDS assisted CNT dispersions. DNA/CNT film has a significantly higher resistance compared to SDS/CNT film. Taking advantage of the porous nature of printed SDS/CNT film after SDS removal, indium can be electroplated to fill the CNT network and form a CNT/In composite. The CNT/In composite was used as interconnect material. Reworkability and RF performance of In-plated CNT bump structures are studied and the results are presented. INTRODUCTION As one of the most extensively investigated materials, carbon nanotubes (CNT) have remarkable electrical [1], mechanical [2] and thermal [3] properties. These properties can be utilized in a variety of applications such as electrical interconnect, which requires high electrical and thermal conductivity, as well as mechanical robustness. In this work, we make use of multiple cycles of inkjet printing to deposit CNT onto desired areas in order to reach a certain thickness (i.e., to construct an array of bumps) and for use as interconnect structures. Printing of CNT at high resolution is demonstrated. Since inkjet printed CNTs can form either a network with a significant amount of empty volume or a mixture of CNT and surfactants, the conductivity of the deposited CNT is usually low. One method to enhance the conductivity of these CNTs is to incorporate metals into the empty space between CNTs. Chen [4] has demonstrated the use of electroless plating to form CNT/metal composite. We proposed a simple method to electroplate In, as an example of introducing metallization into CNT networks to form a composite and to enhance the conductivity. The electroplated CNT bumps are used as interconnect structures. The main goals of this interconnection scheme are to enhance the electrical conductivity between chip-board or chipchip, while providing a robust and reworkable interconnect structure. The concept is that when pushed together, indium-coated CNT films can deform and allow good interconnection between layers, while maintaining performance after multiple connect/disconnect cycles. EXPERIMENT CNT ink preparation CNT ink preparation is critical for ink-jet printing. Sodium dodecyl sulfate (SDS) and salmon DNA strands are used to assist in the dispersion of CNT into DI water. Both SDS and DNA are purchased from Sigma-Aldrich. We used single-walled carbon nanotubes (SWNT) (CG200) produced by SWeNT. These materials are used as is, but are stored in a nitrogen atmosphere. Our SDS-assisted CNT dispersion consists of 0.2% SWNT and 1% SDS while our
DNA-assisted CNT dispersion consists of 0.5% SWNT and 1% DNA. SDS or DNA are added into DI water and stirred before adding CNT. SDS and DNA were magnetically stirred for 10 min in DI water at 40oC. Next, the CNT were added
Data Loading...
