Abstract
SU-8 is an industrially useful photoresist polymer for micro-fabrication because of its unique UV-sensitive curing property. It is also used as a structural material for micro-machines such as micro-electro mechanical systems (MEMS). However, it has poor tribological and mechanical properties which make SU-8 inferior to Si, the mainstay MEMS material today. In this paper, we report the fabrication of SU-8 nanocomposites which are self-lubricating and have better mechanical properties. The liquid lubricant i.e., perfluoropolyether (PFPE) and nanoparticles such as SiO2, CNTs, and graphite were added into SU-8 for this purpose. These self-lubricating SU-8 + PFPE and SU-8 + PFPE + nanoparticle composites have shown a reduction in the initial coefficient of friction by ~6–9 times and increased wear life by more than four orders of magnitude. The mechanical properties such as the elastic modulus and the hardness have increased by ~1.4 times. These SU-8 nanocomposites can be used as a self-lubricating structural material for MEMS applications requiring no external lubrication. As well, these nanocomposites can find applications in many tribological components of traditional machines.
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Marinis, T.F.: The future of microelectromechanical systems (MEMS). Strain 45, 208–220 (2009)
Kim, S.H., Asay, D.B., Dugger, M.T.: Nanotribology and MEMS. NanoToday 2, 22–29 (2007)
de Boer, M.P., Mayer, T.M.: Tribology of MEMS. MRS Bull. 4, 302–304 (2001)
Lee, K.K., Bhushan, B., Hansford, D.: Nanotribological characterization of fluoropolymer thin films for biomedical micro/nanoelectromechanical system applications. J. Vac. Sci. Technol. A 23, 804–810 (2005)
Gelorme, J.D., Cox, R.J., Gutierrez, S.A.R.: Photoresist composition and printed circuit boards and packages made herewith. US Patent 4,882,245, 21 Nov 1989
Abgrall, P., Conedera, V., Camon, H., Gue, A.-M., Nguyen, N.T.: SU-8 as a structural material for labs-on-chips and microelectromechanical systems. Electrophoresis 28, 4539–4551 (2007)
Asay, D.B., Dugger, M.T., Ohlhausen, J.A., Kim, S.H.: Macro- to nanoscale wear prevention via molecular adsorption. Langmuir 24, 155–159 (2008)
Asay, D.B., Dugger, M.T., Kim, S.H.: In situ vapor-phase lubrication of MEMS. Tribol. Lett. 29, 67–74 (2008)
Eapen, K.C., Patton, S.T., Smallwood, S.A., Philips, B.S., Zabinski, J.S.: MEMS lubricants based on bound and mobile phases of hydrocarbon compounds: film deposition and performance evaluation. J. Microelectromech. Syst. 14, 954–960 (2005)
Henck, S.A.: Lubrication of digital micromirror devices™. Tribol. Lett. 3, 239–247 (1997)
Knieling, T., Lang, W., Benecke, W.: Gas phase hydrophobisation of MEMS silicon structures with self-assembling monolayers for avoiding in-use sticking. Sens. Actuators B 126, 13–17 (2007)
Ma, J.Q., Pang, C.J., Mo, Y.F., Bai, M.W.: Preparation and tribological properties of multiply-alkylated cyclopentane (MAC)-octadecyltrichlorosilane (OTS) double-layer film on silicon. Wear 263, 1000–1007 (2007)
Patton, S.T., Eapen, K.C., Zabinski, J.S., Sanders, J.H., Voevodin, A.A.: Lubrication of microelectromechanical systems radio frequency switch contacts using self-assembled monolayers. J. Appl. Phys. 102, 024903 (2007)
Patton, S.T., Slocik, J.M., Campbell, A., Hu, J., Naik, R.R., Voevodin, A.A.: Bimetallic nanoparticles for surface modification and lubrication of MEMS switch contacts. Nanotechnology 19, 405705 (2008)
Prasad, S.V., Scharf, T.W., Kotula, P.G., Michael, J.R., Christenson, T.R.: Application of diamond-like nanocomposite tribological coatings on LIGA microsystem parts. J. Microelectromech. Syst. 18, 695–704 (2009)
Satyanarayana, N., Sinha, S.K.: Tribology of PFPE overcoated self-assembled monolayers deposited on Si surface. J. Phys. D: Appl. Phys. 38, 3512–3522 (2005)
Satyanarayana, N., Sinha, S.K., Lim, S.-C.: Highly wear resistant chemisorbed polar ultra-high-molecular-weight polyethylene thin film on Si surface for micro-system applications. J. Mater. Res. 24, 3331–3337 (2009)
Scharf, T.W., Prasad, S.V., Dugger, M.T., Kotula, P.G., Goeke, R.S., Grubbs, R.K.: Growth, structure, and tribological behavior of atomic layer-deposited tungsten disulphide solid lubricant coatings with applications to MEMS. Acta Mater. 54, 4731–4743 (2006)
Sidorenko, A., Ahn, H.-S., Kim, D.-I., Yang, H., Tsukruk, V.V.: Wear stability of polymer nanocomposite coatings with trilayer architecture. Wear 252, 946–955 (2002)
Jiguet, S., Judelewicz, M., Mischler, S., Hofmann, H., Bertsch, A., Renaud, P.: SU-8 nanocomposite coatings with improved tribological performance for MEMS. Surf. Coat. Technol. 201, 2289–2295 (2006)
Jiguet, S., Judelewicz, M., Mischler, S., Bertch, A., Renaud, P.: Effect of filler behavior on nanocomposite SU8 photoresist for moving micro-parts. Microelectron. Eng. 83, 1273–1276 (2006)
Singh, R.A., Satyanarayana, N., Kustandi, T.S., Sinha, S.K.: Tribo-functionalizing Si and SU8 materials by surface modification for application in MEMS/NEMS actuator-based devices. J. Phys. D: Appl. Phys. 44, 015301 (2011)
Singh, R.A., Satyanarayana, N., Sinha, S.K.: Surface chemical modification for exceptional wear life of MEMS materials. AIP Adv. 1, 042141 (2011)
Voigt, A., Heinrich, M., Martin, C., Liobera, A., Gruetzner, G., Perez-Murano, F.: Improved properties of epoxy nanocomposites for specific applications in the field of MEMS/NEMS. Microelectron. Eng. 84, 1075–1079 (2007)
Chiamori, H.C., Brown, J.W., Adhiprakasha, E.V., Hantsoo, E.T., Straalsund, J.B., Melosh, N.A., Pruitt, B.L.: Suspension of nanoparticles in SU-8: processing and characterization of nanocomposite polymers. Microelectron. J. 39, 228–236 (2008)
Mionic, M., Jiguat, S., Judelewicz, M., Karimi, A., Forro, L., Magrez, A.: Study of the mechanical response of carbon nanotubes-SU8 composites by nanoindentation. Phys. Status Solidi B 247, 3072–3075 (2010)
Okhlopkova, A.A., Pertrova, P.N., Popov, S.N., Fedorov, A.L.: Tribological materials based on polytetrafluoroethylene modified by a liquid lubricant. J. Frict. Wear 29, 133–136 (2008)
Puukilainen, E., Saarenpää, H., Pakkanen, T.A.: Compression-molded, lubricant-treated UHMWPE composites. J. Appl. Polym. Sci. 104, 1762–1768 (2007)
Guo, Q.B., Lau, K.T., Zheng, B.F., Rong, M.Z., Zhang, M.Q.: Imparting ultra-low friction and wear rate to epoxy by the incorporation of microencapsulated lubricant? Macromol. Mater. Eng. 294, 20–24 (2009)
Hu, T., Zhang, Y., Hu, L.: Tribological investigation of MoS2 coatings deposited on the laser textured surface. Wear 278–279, 77–82 (2012)
Neidhardt, J., Hultman, L., Broitman, E., Scharf, T.W., Singer, I.L.: Structural, mechanical and tribological behavior of fullerene-like and amorphous carbon nitride coatings. Diam. Relat. Mater. 13, 1882–1888 (2004)
Sugimoto, I., Miyake, S.: Solid lubricating fluorine-containing polymer film synthesized by perfluoropolyether sputtering. Thin Solid Films 158, 51–60 (1988)
Constantin, F., Fenouillot, F., Pascault, J.-.P., Williams, R.J.J.: Post-crosslinkable blends: reactions between a linear poly(hydroxyl-amino ether) and a diepoxy. Macromol. Mater. Eng. 289, 1027–1032 (2004)
Surface Coatings Association of Australia. (ed.) Surface Coatings: Raw Materials and Their Usage, vol. 1. Chapman & Hall, London (1993). ISBN 0412552108
Acknowledgments
This research is supported by the Singapore National Research Foundation under its CRP (Competitive Research Program) funding (Award Number: NRF-CRP 2-2007-04). The views expressed herein are those of the authors and are not necessarily those of the Singapore National Research Foundation. Part of the results presented here has been filed for US Provisional Patent Application No.: 61/563,522, Filing date: 23 November 2011 (Inventors: S. K. Sinha, Prabakaran Saravanan, and N. Satyanarayana).
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Saravanan, P., Satyanarayana, N. & Sinha, S.K. Self-lubricating SU-8 Nanocomposites for Microelectromechanical Systems Applications. Tribol Lett 49, 169–178 (2013). https://doi.org/10.1007/s11249-012-0055-0
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DOI: https://doi.org/10.1007/s11249-012-0055-0