ABSTRACTS

The following is a list of the abstracts for papers which will be presented in THE SEVENTH INTERNATIONAL SYMPOSIUM ON METALLIZED PLASTICS: FUNDAMENTAL AND APPLIED ASPECTS. The listing is alphabetical by presenting author. This list is updated continually to add abstracts as they become available and make appropriate corrections. This list may be conveniently searched by using the editor provided with most popular browsers (e.g. Microsoft Explorer, Netscape, ... etc.)

1) Department of Physics, Drexel University, 32^nd and Chestnut Streets, Philadelphia, PA 19104

2) Department of Chemical Engineering, University of Pennsylvania

3) Department of Chemistry, Drexel University, Philadelphia, PA 19104

Ultrathin Polyaniline Films on Metal Surfaces: Growth, Polymerization, and Conductivity

Early applications of High Resolution Electron Energy Loss Spectroscopy (HREELS) for the study of ultrathin polymer films and plymer-metal interfaces provided important information on bonding and electronic structure through analysis of simultaneously measured vibrational and electronic excitation spectra. However, detailed analyses of vibrational spectra were limited by energy resolution >40 cm^-1 which made it difficult to separate close-lying vibrational modes. Recent developments in HREEL spectrometers has made it possible to achieve <8 cm^-1 energy resolution, and along with the ability to excite both optically-active and optically-forbidden transitions, virtually all the vibrational modes of complex polymer ultrathin films can be distinguished. Then the analysis of surface functionalities and interfacial bonding proceeds by comparison with reference infrared, Raman, and UV-VIS spectra of molecular analogues. In this paper, we will present brief highlights in the development of HREELS for the study of polymer systems and discuss our recent studies of polyanaline ultra thin films deposited on metal surfaces. These studies have (1) identified substrate-dependent effects in initial bonding and growth of vapor-deposited polyaniline oligomers, (2) shown evidence for polymerization at the interface, (3) found relatively high local conductivity in protonated films after ex-situ doping, and (4) provided new insights on the conductivity mechanisms themselves. Finally, prospects and limitations of HREELS as applied to polymer systems will be discussed.

Nucleation, Growth, and Adhesion of Metal Films on Polymers

Although metallization of polymers plays an important role in the manufacturing of many products, research into the field of metal-polymer interfaces was mainly stimulated by applications of polymers in microelectronics. In future device generations aluminum will be replaced by the lower resistivity copper, and polymers are seen as potential low-permittivity (low-k) dielectrics even for on-chip interconnects.The structure and properties of metal-polymer interfaces depend strongly on the deposition conditions, particularly on the early deposition process [1]. Here the condensation coefficient C of noble metals on low-k dielectrics can be extremely low [2]. Moreover, isolated metal atoms impinge on the polymer surface and are able to diffuse at the surface and into the polymer bulk unless they form strong bonds to the polymer chains. After nucleation and growth of clusters noble metals are effectively immobilized because of their high cohesive energy. In particular, no diffusion is to be expected from a continuous film [3]. While the condensation coefficient of noble metals on polymers as well as the macroscopic adhesion can be enhanced by ion treatment of the polymer surface, we also present a new way to improve adhesion of metals of low reactivity on polymers. This approach involves a post-deposition annealing near the glass transition temperature of the polymer.

1. F. Faupel, R. Willecke and A. Thran, Mater. Sci. Eng. R 22, 1 (1998).

2. A. Thran, M. Kiene, V. Zaporojtchenko, and F. Faupel, Phys. Rev. Lett. 82, 1903 (1999).

3. M. Kiene, T. Strunskus, R. Peter, and F. Faupel, Adv. Mater. 10, 1357 (1998).

Metal Doped Plasma Polymer Films

As well known, thin plasma deposited polymer layers can be prepared pin hole-free with rather good adhesion to many substrates. However, usually plasma polymer layers prepared by a continuous wave radio-frequency plasma are often chemically irregular when their structures and compositions are considered. To avoid these irregularities two approaches were used: (i) Application of low wattages, which is unfortunately accompanied by the formation of low-molecular weight components, and (ii), the application of the pulsed plasma technique.

The first goal was to produce plasma polymers comprising double or triple bonds in a quality comparable to the respective bulk polymers, prepared by standard procedures. Acetylene, ethylene, butadiene and polystyrene were deposited as thin polymer films by pulsed plasmas of low wattages. Styrene polymerization was strongly enhanced in the dark phase (plasma off) of a pulsed R.F. plasma caused by the reactivity of the vinyl-type double bond. This could be confirmed by a verification of a rather high chemical regularity of the film sample. The oxygen content of this film measured by XPS was lower than 1%. This content did not remarkable increase after storage in air. IR investigations revealed that acetylene reacted by opening the triple bond and also by hydrogen substitution under retention of the triple bond. Butadiene polymerized comprising a high concentration of C=C double (and triple) bonds as verified by NEXAFS spectroscopy.

During the low-wattage pulse plasma polymerization metal atoms were simultaneously evaporated into the growing layer. These metal atoms are acting as dopants. In detail, Li, Mg, and Al are used at different concentrations providing electrical conductivity of the film.

Imroved Aluminum Mirroe Quality in Large-Scale Car Lighting Production by Integrating Plasma Pretreatment, Sputtering and Plasma Polymerization

Today's car lighting reflectors and even bezels have reached highly complex shapes and sometimes extreme sizes also. The move to abandon lacquering has revealed new challenges to metallize such demanding parts, especially reduced adhesion of the coating and outgassing from the part that may affect metal quality or may caus hazy appearance of these parts during the lifetime of the car by droplet condensation. These problems can be solved by a process sequence including plasma pretreatment, sputtering, and plasma polymerization in one load locked machine. An efficient vacuum system and the plasma pretreatment ensure good degassing of the parts. Further outgassing from the bulk of the material can be blocked by a plasma polymerized base coat. The following sputtering process yields very good quality and coverage of the metal layer (usually aluminum but other metals or alloys as well) also on less exposed areas, even behind recesses. Subsequently, first a corrosion protective layer and a high surface energy top coat (that suppresses hazing effects by spreading out any condensing vapors to some optically neutral layer) are deposited by plasma polymerization. As a result, the overall reflectance, corrosion and hazing resistance of aluminum mirrors sputtered within such a process sequence over a complex reflector part was found to be superior to an evaporated one.

Uv-excimer Radiation, a Tool to Generate Selective Metallized

Structures on Polymer Surfaces

Before metallization, polymer surfaces have to be pretreated for surface modification and functionalization. The latter results inchanges of surface morphology as well as chemical modifications. Both changes determine the quality of deposition and the adhesion of the metal layer e.g.in subsequent wet chemical depostion processes. An overview is given on the use of UV-excimer-radiation generated by excimer-lasers or lamps to modify and functionalize polymer surfaces for subsequent wet chemical metallization . The high-energy UV radiation induces chemical modifications and changes physical properties in irradiated areas. Selective metallization is achieved byselective deposition of noble metal complexes only on irradiated areas. The deposition of the metal layer takes place in electroless metallization bath through catalytical effects. The different chemical, physical and process-technological aspects of the use ofUV-radiation to perform selective metallization and its possible applications to produce electric circuits on one- or three-dimensional polymer substrates, in the MID (molded interconnected devices) are reported.

Surface "Metallization" of Poly(tetrafluoroethylene) Films with a "Synthetic Metal"

Surface "metallization" of poly(tetrafluoroethylene) (PTFE) film with a "synthetic metal", viz., polyaniline (PAn), was carried out chemically and physically to render the PTFE surface electrically conductive. The chemical surface modification involved the UV-induced graft copolymerization of argon plasma-pretreated PTFE film with 4-vinylaniline (4-VAn) monomer, followed by oxidative copolymerization of the aniline moiety of the grafted 4-VAn polymer with aniline. The efficiency of the surface oxidative copolymerization with aniline (and thus the resulting surface conductivity) was enhanced by the high concentration of the grafted 4-VAn polymer from the initial graft copolymerization. The surface electrical resistivity of the PTFE film so-prepared was reduced by more than 10 orders of magnitude to about 10⁶ /. The physical surface modification involved the coating of PAn on surface-modified PTFE film, prepared from UV-induced double graft copolymerization with acrylic acid (AAc) and styrenesulfonic acid (SSAc), during the oxidative polymerization of aniline. Both AAc and SSAc contain the protonic acid groups for the protonation/doping of the coated PAn. After coating of PAn, the surface resistivity for the modified PTFE film from double graft copolymerization with AAc and SSAc was reduced to the order of 10³~10⁴ /. The protonation/deprotonation behavior of the grafted and coated aniline polymer on PTFE was similar to that of the aniline homopolymer. The surface compositions of the modified PTFE films were characterized by X-ray photoelectron spectroscopy (XPS). Both the grafted and the coated aniline polymer layers exhibited good durability during solvent extraction.

* Corresponding Author

Metallization on Polymers Modified by Ion-assisted Reaction

Surfaces of various polymers (PI, PVDF, PTFE, etc.) were modified by ion-assisted reaction, and Pt, Cu, and Al films were deposited on the modified polymers, in which a few keV ions were irradiated on the surfaces of polymer with changing ion doses in reactive gases environment. Wettability of the modified polymers( surface energy = 60- 70 erg/cm2) was largely improved by the formation of hydrophilic groups due to chemical reaction between polymer surface and reactive gases during the ion irradiation process. The change of wettability in the modified polymers was closely related to the surface chemistry and surface roughness. On the basis of high-resolution XPS analysis, the newly formed hydrophilic groups were identified as -(C-O)-, -(C=O)-O-, and -(C=O)- bonds. Through SEM and AFM analysis, it was observed that the surface morphology and roughness of PI and PVDF were seldom changed with varying ion doses, but those of PTFE were abruptly changed. The cones and/or filaments appeared on the modified PTFE and the surface roughness increased with increasing ion doses. Adhesions between metal films and polymers modified by the method were significantly improved such that no detachment was possible in ScotchTM tape test, boiling test, peel test,etc. The increase of adhesion strength between metal film and modified PI and PVDF was mainly attributed to the formation of hydrophilic groups, which interacted with metal film. In the case of the modified PTFE, the enhanced adhesion to metal film could be explained by the change of surface morphology together with the chemical reaction. The increased surface roughness leaded to the mechanical interlocking between metal film and PTFE. The electrical properties of the metal films on modified polymers were also reviewed.

Metallization of Polymers by Plasma Pretreatment Followed by an Electroplating Process

The conventional pretreatment of polymers for the metallization by electroplating is based on hazardous and pollutive agents like chromic acid and various organic solvants. We report on the metallization of glas fiber reinforced polybuthelenterephtalate (PBT 20% glas fiber, CRASTIN SK 603 ) and by electroplating without using such chemicals as pretreatment agents. This chemical step is substituted by a low pressure plasma process of the polymer surface.

The plasma pretreatment of CRASTIN SK 603 was performed in a parallel plate reactor operating at 13.56 MHz. As plasma gas oxygen and argon/oxygen mixture was used. A plasma pretreatment time of 5-10 minutes leads to excellent adhesion strength up to 2 N/mm as measured by a 90° peel test of the electroplated metal coatings. The roughening and activation of the polymer surface is essential for the adhesion. Pretreatment time above 10 minutes leads to lower adhesion strength.

A combination of a selective plasma activation through a metal mask followed by a maskless Pd-seeding process leads to the deposition of patterned metal lines on the polymer. Thus, this is a promising method for the direct deposition of conductor lines by electroplating as needed for the 3D moulded interconect devices (3D-MID). The plasma pretreatment was also successfully applied as a pretreatment process for the subsequent electroplating of complicated 3-D CRASTIN parts. 100 µm wide conductor lines were deposited by this metallization process, even areas providing an angle of 90 ° to the base plate were metallized. Thus, a combination of low pressure plasma processes and electroplating takes advantage of the specific merits of both processes. The plasma activation of polymers substitutes hazardous and pollutive chemicals insuring a save and fast pretreatment whereas electroplating guarantees an economic metallization of polymers.

Surface Pre-Treatment of Ultra High Molecular Weight Polyethylene and

the Consequences for Metal Adhesion

Polyethylene surface is chemically inert, so it was often treated by a variety of procedures including acid, plasma treatments. However, these treatments increase the roughness of the surface, which sometimes deteriorates a mechanical property and a fine sight of the film surface. In this study, ultra high molecular weight polyethylene (UHMWPE) was treated prior to the processings such as gel-cast and drying. After that, the dried gel cast film was ultra-drawn, its mechanical and surface properties were investigated. Two treatments were investigated in this study, that is, oxygen plasma irradiation on UHMWPE powder, and grafting with maleic anhydride (MAH) in semi-dilute solution. Hydrophilic functional groups could be introduced to UHMWPE, which were once migrated into the bulk during processing. However, they were re-located on the surface after ultra drawing in boiling water. This brought a good adhesion between smooth polymer surface and metal surface. Plasma irradiation / Grafting of MAH, and drawing in boiling water were found to be quite useful for the improvements of adhesive properties of UHMWPE.

1) Lucent Technologies, Murray Hill, NJ

2) Pennsylvania State University

Interaction Between Aluminum and Self-Assembled Monolayers

Self-assembled monolayers (SAM's) can serve as ideal model systems for organic surfaces. The reactivity of the organic surface affects the morphology of the growing overlayer and the diffusion of adsorbed metal into the organic layer. Vibrational and electron spectroscopies show that Al reacts strongly at the surface of thiol SAM's, adsorbed on Au surfaces and termninated with functional groups containing oxygen or nitrogen, such as methyl ester, alcohol, carboxylic acid or amine. SAM's terminated with methyl groups have little reaction, an the Al diffuses into the SAM overlayer. Angle-resolved XPS was used to determine how adsorbed Al reacts with and diffuses into thiol SAM's terminated with methyl, methyl esters and methyl ester functional groups. Methyl-terminated SAM's attached to silicon dioxide surfaces through silanes showed that the mechanism of anchoring to the surgace plays a role in the diffusion of metal through the SAM by limiting the mobility of the SAM on the surface. A maximum entropy algorithm was used to transform the angle resolved XPS data to composition depth profiles. The maximum entropy program used here minimizes deviations from an initially assumed depth profile at the expense of optimizing the profile to minimize ² in fitting the angle resolved data.

Characterization of the Metal/PTFE Interphase by XPS and AFM

The chemical and physical characteristics of the metal/polymer interface determine several important properties including wear and adhesion. We report results from a systematic investigation of the metal/poly(tetrafluoroethylene) (PTFE) interphase resulting from titanium, iron and copper physical vapor deposition characterized using X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). On PTFE, titanium formed titanium (III) fluoride (TiF₃) and titanium carbide (TiC), iron formed iron (III) fluoride (FeF₂), while copper was unreactive. Titanium in contrast to iron produced no cross-linked species and CF₃ groups, postulated to arise from -F- intermediates. Simultaneous C-F and C-C bond breaking kinetics, however, can rationalize the absence of these species during titanium metallization. The inertness of copper is a consequence of the larger magnitude in the C-F bond strength compared to that of Cu-F. Pretreatment of native PTFE by Ar⁺ ion or X-ray irradiation did not modify the chemical reactivity of the polymer surface during subsequent Cu deposition, although significant morphological changes were observed on PTFE by AFM. In contrast, post-treatment of the Cu/PTFE interface by Ar⁺ ion or X-ray irradiation was required to produce copper (II) fluoride (CuF₂). In the case of iron and titanium/PTFE systems, X-ray post treatment resulted in increased metal fluoride at the interphase.

1) Lab for Surface Modification, Dept. Physics, Rutgers University, 136,

Frelinghuysen Rd, PISCATAWAY, NJ 08854

2) Institut für FestKörperphysik, TU-Graz, A-8010 GRAZ (Austria)

3) Facultés universitaires, Lab. Lise, 61 rue de Bruxelles B-5000 NAMUR (Belgium)

A Photoelectron Spectroscopy Investigation of Energy Level Alignment and

Metal Interaction at the Interface with Electroluminescent Materials:

Poly(2,5 Diheptyl 1-4 Phenylene-alt-2,5 Thienylene) (PDHPT Polymer) and

Sexiphenyl (6p Oligomer)

(Abstract not yet available)

¹ Laboratoire de Sciences et Ingénierie des Surfaces; Université Claude, Bernard - LYON 1, 69622 Villeurbanne Cedex, France

² Fachhochschule Mannheim, University of Applied Sciences, 68163 Mannheim, Windeckstraße 110, Germany

Simplification of Electroless Plating Processes by Activation of Polymer Surfaces Using Dielectric Barrier Discharge Devices

Electroless plating of non-conducting materials needs, prior to the metal deposition itself, to make catalytically active the sample surface. In the present work, two routes are described and compared. The former involves the chemical reduction of a thin-solid palladium acetate (PdAc) coating and thereby the formation of palladium (Pd) nuclei on a non-active surface. The latter involves the surface grafting of oxygenated and/or nitrogenated functionalities and the subsequent activation of the relevant surface through the chemisorption of palladium from a mixed acidic SnCl₂/PdCl₂ or a simple acidic PdCl₂ solution. For this purpose, pre-treatments (chemical reduction of PdAc and surface functionalization, respectively) are carried out in gas phase using either a dielectric barrier discharge (DBD) or an excimer vacuum ultra-violet (VUV) lamp (Xe₂* source delivering a radiation centered at 172 nm) based on the DBD configuration. In the first case, surface processing is performed at atmospheric pressure in air. In the second case, it is accomplished at reduced pressure either in air or in a corrosive gas. In these experiments, poly(imide) substrates are subjected to surface activation and subsequently to electroless metallization (autocatalytic deposition of copper or nickel). Surface analysis is carried out using mainly XPS after each step of the whole processing in order to investigate the influence of the experimental parameters on the surface atomic concentration of the elements of interest (C, O, N, Pd ...). It is found that surface treatments using DBD and excimer lamp result in different morphological and chemical modifications. The latter will be discussed at the meeting.

Statistical Design Methods for Optimizing Metallization of PET Film

(Abstract not yet available)

Metallization of Plastics by Direct Electroplating or Electroless Plating - Without the Need of a Continuous Conducting Seed Layer

(Abstract not yet available)

Ligand Effects in the Single-Stage Metallization of Polyimides Via Silver and Gold Complexes

(Abstract not yet available)

Considerations of Interfacial Bonding of Metallized Plastics as Derived from Surface Analytical Investigations

(Abstract not yet avaialble)

Condensation Coefficients, Surface Diffusion and Chemical Interaction of Noble Metal Atoms at Polymer Surfaces

The chemical interaction between the metal and the polymer is a very important parameter during interface formation. Usually, x-ray photoelectron spectroscopy (XPS) has been applied to obtain information about the chemical interaction between metals and polymers, although it is difficult to obtain quantitative information. In another approach the interaction energy between a metal atom and a polymer model has been determined by quantum mechanical calculations [1]. In this report we demonstrate how quantitative information about the chemical interaction between metal atoms and polymer surfaces can be obtained by investigating the temperature dependence of the condensation, nucleation and surface diffusion behavior of metal atoms at polymer surfaces in the initial stages of interface formation. Using a combination of x-ray photoelectron spectroscopy (XPS) with transmission electron microscopy (TEM) and a very sensitive radiotracer technique activation energies for surface diffusion (E_d) and metal atom adsorption energies (E_a) were determined for several metal-polymer systems. The influence of chemical and morphological aspects on x-ray photoelectron spectra during metal growth on polymer surfaces will be discussed.

[1] see e.g. A. Ouhlal, A. Selmani, A. Yelon, M. P. Andrews, Chem. Phys. Lett. 202 (1993) 51.

Inverse CVD: a Novel Synthetic Approach to Metallized Polymeric Films

(Abstract not yet available)

1) Laboratory for surface Modification, Rutgers - The State University of New Jersey, Piscataway, NJ 08854

2) PCPM Laboratory, Louvain-La-Neuve University, 1 Place Croix du Sud, b-1348 Louvain-La-Nueve, Belgium

The Aluminum/Polyester Interface: a Combined Static Secondary Ion Mass Spectrometry & Denstiy functional theory Study

A tandem experimental (static secondary ion mass spectrometry (SSIMS) and theoretical (density functional theory (DFT)) approach has been usedto study the aluminum/poly(ethelene terephthalate) (PET) interface. The SSIMS results show that, the Al layer uniformly covers the PET surface giving rise to an initial two-dimensional growth mode. This behavior originates from the strong interaction between Al and the doubly bounded oxygen of the ester function to form a metal-oxygen (polymer) complex. Total energy calculations performed using DFT, on Al/PET, confirm that this interaction is strong. Further, interaction of Al with the ester function induces a loss of aromaticity without breaking apart the ring structure. In this case, the electronic levels of the PET become partly depopulated by transferring some charge to the more delocalized * orbitals. An evalustion of the chare transfer revealed that upon Al bonding with the ester group, the phenyl ring evolves into a quinoid structure. This result corroborates quite well the initial decay, upon Al deposition, of the SSIMS fragment associated with the phenyl ring.

Metallization of Surface Modified Fluoropolymers

Plasma surface modification using a H₂/MeOH or H₂/H₂O radio frequency glow discharge (RFGD) plasma treatment has been demonstrated as effective for de-fluorinating and adding hydroxyl functionality to the surface of fluoropolymer or fluorocarbon based materials ⁽¹⁾. Modification occurs at the outermost 5.0 nm of these substrates without significantly effecting the surface morphology or the carbon backbone of these polymers. This treatment can be used to carefully control the degree of defluorination in order to preserve both fluorine functionality at the surface and within the bulk of these materials. This is important because the unique electron withdrawing characteristics of fluorine significantly affects the reactivity of the added hydroxyl functionality. Fluoropolymer surfaces modified using this plasma treatment are quite reactive and have been shown to be facile for covalently bonding and adhering numerous materials such as, organosilane coupling agents ⁽²⁾, biological recognition elements ⁽³⁾, eukaryotic cell lines⁽²⁾, peptides, adhesives, polyelectrolytes (including conducting polymers), ⁽⁴⁾ and metals ⁽⁵⁾.

Although metallization of modified fluoropolymers has been previously described, the adhesion of the metals was facilitated through crosslinking the metals to coupling agents first bonded to the modified fluoropolymer surfaces ⁽⁵⁾. Further, previous work only demonstrated the bonding of conducting metals in zero oxidation states. In this report we show that the unique chemistry which results at the hydroxylated fluoropolymer surfaces can facilitate not only direct attachment of metal species (i. e., without the use of crosslinkers), but additional control over the final oxidation state of these bonded metal species.

References:

1. Gardella, J.A., Jr., and Vargo, T.G., U.S. Patent 4,946,903, 1990.

2. Vargo, T.G., et.al., Langmuir 1992, 8, 130.

3. Bright, F.V., et. al., Anal. Chim. Acta. 1992, 262, 323.

4. Vargo, T.G., et al., Supramolecular Science 1995, 2, 169.

5. Vargo, T.G., Gardella, J.A., Jr., Calvert, J.M., Chen, M.S. Science 1993, 262, 1711.

Modification of Poly(tetrafluoroethylene) and Copper Surfaces by Graft Copolymerization for Adhesion Improvement

Simultaneous graft copolymerization and lamination of surface modified copper foil to Ar plasma-pretreated poly(tetrafluoroethylene) (PTFE) film was achieved in the presence of an epoxy resin adhesive and glycidyl methacrylate (GMA) monomer, or in the presence of GMA and hexaethylenediamine (HEDA), in the temperature range of 110 ^oC to 230 ^oC. The plasma pretreatment and subsequent air exposure introduce hydroperoxide or peroxide species which are degraded into radicals to initiate the graft copolymerization of GMA on the PTFE surface. The copper foil surface was pretreated with a silane coupling agent (SCA), such as (3-mercaptopropyl)trimethoxysiane, 3-(trimethoxysilyl)propyl methacrylate or N¹-[3-(trimethoxysilyl)propyl]diethylene-triamine to form a silanized organic layer. The silanized copper foils were subjected to Ar plasma treatment and subsequently UV-induced graft copolymerization with GMA (Cu-SCA-g-GMA). In an alternative approach, further surface modification of Ar plasma pretreated PTFE film was also carried out via UV-induced graft copolymerization with GMA. The so-obtained GMA graft- copolymerized PTFE (GMA-g-PTFE) film adhere strongly to a graft-modified copper foil by the simultaneous thermal graft copolymerization and lamination process in the presence of GMA and HEDA. In this case, the T-peel adhesion strength is also affected by the Ar plasma post-treatment of the GMA graft-copolymerized PTFE film. The modified surfaces and interfaces were characterized by X-ray photoelectron spectroscopy (XPS) and water contact angle measurement. The Cu-SCA-g-GMA/GMA-epoxy resin/PTFE or Cu-SCA-g-GMA/GMA-HEDA/GMA-g-PTFE laminates exhibited T-peel adhesion strengths above 10 N/cm and the joints delaminated by cohesive failure inside the bulk of the PTFE film. The strong adhesions in these Cu-PTFE laminates are attributable to the fact that the GMA chains are covalently tethered on both the PTFE and the silanized Cu surfaces, as well the fact that these grafted GMA chains are incorporated into the highly crosslinked network structure of the adhesive at the interface.

* Corresponding author

1) Physics Department, Southern Oregon University, Ashland, OR 97520

2) Department of Physics, Renssaelaer Polytechnic Institute, Troy, NY 12180

Chemical Structure Determination, Modelling and Adhesion Enhancement of Metal-Polymer Interfaces

Adhesion of metal/polymer is a crucial issue in a variety of applications. One of these is the interconnect in IC fabrication. The adhesion strength depends strongly on the chemical structure and physical mixing at the interface. X-ray Photoelectron Spectroscopy (XPS) is well suited for determining the effect of chemical interaction on adhesion. This is demonstrated by an XPS study of the metal/Teflon AF interface. Monte Carlo calculations showed that chemical and physical intermixing are both important factors in enhancing metal/polymer adhesion. Two deposition techniques, Partially Ionized Beam (PIB) and Reactive Ion Assisted Interface Bonding and Mixing (RIAIBM), are developed to promote chemical reaction and physical atomic mixing during deposition. These techniques produce films with enhanced adhesions. Results of the XPS study, Monte Carlo calculations, and measurements on films produced by PIB and RIAIBM will be presented and discussed.