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Effects of ion beam treatment on atomic and macroscopic adhesion of copper to different polymer materials

Effects of ion beam treatment on atomic and macroscopic adhesion of copper to different polymer materials
Effects of ion beam treatment on atomic and macroscopic adhesion of copper to different polymer materials
Low-energy ion irradiation of polymer induces different phenomena in the near surface layer, which effect strongly the metal–polymer interface formation and promotes adhesion of polymers to metals. Low-energy argon and oxygen ion beams were used to alter the chemical and physical properties of different polymers (PS (polystyrene), P?MS (poly(?-methylstyrene), BPA-PC (bisphenol-A-polycarbonate) and PMMA (poly(methyl methacrylate)), in order to understand the adhesion phenomena between a deposited Cu layer and the polymers. The resulting changes were investigated by various techniques including X-ray photoelectron spectroscopy, measurements of the metal condensation coefficient and a new technique to measure cross-linking at the polymer surface. Two types of practical adhesion strengths of Cu–polymer systems, measured using 90° peel tests, were observed: (i) peel strength increased at low ion fluences, reached a maximum and then decreased after prolonged treatment and (ii) no improvement in the peel strength on treated polymer surfaces was recorded. The improvement in the metal–polymer adhesion in the ion fluence range of 1013–1015 cm?2 is attributed to the creation of a large density of new adsorption sites resulting in a larger contact area and incorporation of chemically active groups that lead to increased interaction between metal and polymer by metal–oxygen–polymer species formation. XPS analysis of peeled-off surfaces showed that in most cases the failure location changed from interfacial for untreated polymers to cohesive failure in the polymer for treated surfaces. These observations and measurements of the metal condensation coefficients suggest that bonding is improved at the metal–polymer interface for all metal–polymer systems. However, the decrease in the peel strength at high ion fluences is attributed to the formation of a weak boundary layer in polymers. The correlation between sputter rate of polymers and altering in the peel strength for moderate ion fluences was determined. It was observed that the metal–polymer adhesion could be improved for PS and BPA-PC, which have a low sputter rate and preferentially formed cross-links in the treated surface. For degrading polymers, like P?MS and PMMA, chain scission rather than cross-linking dominates, low molecular weight species are formed and no adhesion enhancement is observed.
ion irradiation, x-ray photoelectron spectra-surface analysis, polymers, adhesion, glass transition
0168-583X
139-145
Zaporojtchenko, V.
0b31e301-6b39-467b-8702-bff5592065fd
Zekonyte, Jurgita
c40df725-5ce3-4692-b638-bbb4d847b5ea
Faupel, F.
67261d48-5e0c-40e5-9957-dad59695b04b
Zaporojtchenko, V.
0b31e301-6b39-467b-8702-bff5592065fd
Zekonyte, Jurgita
c40df725-5ce3-4692-b638-bbb4d847b5ea
Faupel, F.
67261d48-5e0c-40e5-9957-dad59695b04b

Zaporojtchenko, V., Zekonyte, Jurgita and Faupel, F. (2007) Effects of ion beam treatment on atomic and macroscopic adhesion of copper to different polymer materials. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 265 (1), 139-145. (doi:10.1016/j.nimb.2007.08.040).

Record type: Article

Abstract

Low-energy ion irradiation of polymer induces different phenomena in the near surface layer, which effect strongly the metal–polymer interface formation and promotes adhesion of polymers to metals. Low-energy argon and oxygen ion beams were used to alter the chemical and physical properties of different polymers (PS (polystyrene), P?MS (poly(?-methylstyrene), BPA-PC (bisphenol-A-polycarbonate) and PMMA (poly(methyl methacrylate)), in order to understand the adhesion phenomena between a deposited Cu layer and the polymers. The resulting changes were investigated by various techniques including X-ray photoelectron spectroscopy, measurements of the metal condensation coefficient and a new technique to measure cross-linking at the polymer surface. Two types of practical adhesion strengths of Cu–polymer systems, measured using 90° peel tests, were observed: (i) peel strength increased at low ion fluences, reached a maximum and then decreased after prolonged treatment and (ii) no improvement in the peel strength on treated polymer surfaces was recorded. The improvement in the metal–polymer adhesion in the ion fluence range of 1013–1015 cm?2 is attributed to the creation of a large density of new adsorption sites resulting in a larger contact area and incorporation of chemically active groups that lead to increased interaction between metal and polymer by metal–oxygen–polymer species formation. XPS analysis of peeled-off surfaces showed that in most cases the failure location changed from interfacial for untreated polymers to cohesive failure in the polymer for treated surfaces. These observations and measurements of the metal condensation coefficients suggest that bonding is improved at the metal–polymer interface for all metal–polymer systems. However, the decrease in the peel strength at high ion fluences is attributed to the formation of a weak boundary layer in polymers. The correlation between sputter rate of polymers and altering in the peel strength for moderate ion fluences was determined. It was observed that the metal–polymer adhesion could be improved for PS and BPA-PC, which have a low sputter rate and preferentially formed cross-links in the treated surface. For degrading polymers, like P?MS and PMMA, chain scission rather than cross-linking dominates, low molecular weight species are formed and no adhesion enhancement is observed.

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Published date: 2007
Keywords: ion irradiation, x-ray photoelectron spectra-surface analysis, polymers, adhesion, glass transition

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Local EPrints ID: 158477
URI: http://eprints.soton.ac.uk/id/eprint/158477
ISSN: 0168-583X
PURE UUID: 0e6a8f21-673e-4317-83b7-d2ca3f54f69f

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Date deposited: 21 Jun 2010 11:39
Last modified: 11 Nov 2019 21:19

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Contributors

Author: V. Zaporojtchenko
Author: Jurgita Zekonyte
Author: F. Faupel

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