Chemistry of Adhesion at the Polyimide-Metal Interface

1987 ◽  
Vol 108 ◽  
Author(s):  
M. Grunze ◽  
W. N. Unertl ◽  
S. Gnanarajan ◽  
J. French
Keyword(s):  
Structural Changes ◽  
High Vacuum ◽  
Scanning Tunneling ◽  
Metal Interface ◽  
Polyimide Films ◽  
Absorption Data ◽  
Polyamic Acid ◽  
Vapor Phase Deposition ◽  
Infrared Reflection ◽  
Polyimide Precursor

ABSTRACTThis article describes recent studies of the chemistry of adhesion between thin (d ≥ 11 Å) polyimide films and silver and copper substrates, and the structural changes in the polymer when polyamic acid is imidized to polyimide. The thin polyamic acid films were formed by vapor phase deposition of 1,2,4,5-benzenetetracarboxylic anhydride (PMDA) and 4,4-oxydianiline (ODA) under high vacuum conditions and subsequent imidization by heating in vacuum. Both ODA and PMDA are at least partially dissociated upon adsorption onto clean copper and silver and with increasing film thicknesses react to form the polyimide precursor, polyamic acid. Heating to T ≥ 425 K leads to polymerization to form polyimide films which are thermally stable to about 700 K. Polyimide films with mean thicknesses as small as 1.1 nm have been fabricated in this way and their bonding to the substrate as determined by x-ray photoemission studies is su marized. Infrared reflection absorption data gives further evidence that the polyimide bonds to the substrate via fragmented PMDA. Changes in the surface topography and molecular structure of the films during imidization are demonstrated by scanning tunneling micrographs and infrared reflection absorption data.

Ftir and Xps Studies of Polyimide/Metal Interface Formation

1989 ◽  
Vol 153 ◽  
Author(s):  
William C. Stewart ◽  
Jihperng Leu ◽  
Klavs F. Jensen
Keyword(s):  
Photoelectron Spectroscopy ◽  
Polymer Structure ◽  
Ring Closure ◽  
Metal Interface ◽  
Polyimide Films ◽  
Polyamic Acid ◽  
Xps Spectra ◽  
X Ray ◽  
Spectroscopy Studies ◽  
Thermal Stability Of

AbstractWe describe infrared and x-ray photoelectron spectroscopy studies of the interfaces formed when the PMDA/ODA polyamic acid is imidized on gold, chromium, and copper. Polyimide films ranging from 34 ° to 1328 ° are analyzed as part of these studies. The IR and XPS results indicate that the gold interacts very little with the polyimide, while copper produces significant changes in the IR and XPS spectra. At elevated cure temperatures passivated chromium also reacts with the polyimide. In structures with chromium and copper, the thermal stability of the polyimide at the interface is reduced from that of bulk polyimide. The data demonstrate that the metals interact with the polymer structure at the point where ring closure occurs to form the polyimide from polyamic acid.

Structure of a new orthorhombic phase in NiTi: Mn shape memory alloys

1990 ◽  
Vol 48 (4) ◽  
pp. 1000-1001
Author(s):  
Jenö Beyer ◽  
Lajos Tóth
Keyword(s):  
Martensitic Transformation ◽  
Structural Changes ◽  
High Vacuum ◽  
Intermetallic Phase ◽  
Orthorhombic Phase ◽  
Transformation Process ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Crystallographic Structures ◽  
Ternary Additions

The structural changes during reversible martensitic transformation of near-equiatomic NiTi alloys can best be studied in TEM at around room temperature. Ternary additions like Mn offer this possibility by suppressing the Ms temperature below RT. Besides the stable intermetallic phases (Ti2Ni, TiNi, TiNi3) several metastable phases with various crystallographic structures (rhombohedral, hexagonal, monoclinic, cubic) have also been reported to precipitate due to suitable annealing procedures.TiNi:Mn samples with 0.9 and 1.3 at% Mn were arc melted in argon atmosphere and homogenized at 948 °C for 72 hours in high vacuum in an infrared furnace. After spark cutting slices of 0.2 mm, TEM specimens were prepared by electrochemical polishing with the twin-jet technique in methanol - perchloric acid electrolyte. The TEM study was carried out in a JEOL 200 CX analytical electron microscope.In this paper a new intermetallic phase is reported which has been observed in both samples by TEM during the martensitic transformation process.

scholarly journals Strain-Relief Patterns and Kagome Lattice in Self-Assembled C60 Thin Films Grown on Cd(0001)

2021 ◽  
Vol 22 (13) ◽  
pp. 6880
Author(s):  
Zilong Wang ◽  
Minlong Tao ◽  
Daxiao Yang ◽  
Zuo Li ◽  
Mingxia Shi ◽  
...  
Keyword(s):  
Thin Films ◽  
Self Assembly ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Scanning Tunneling ◽  
Kagome Lattice ◽  
Tunneling Microscopy ◽  
Kagomé Lattice ◽  
Temperature Scanning ◽  
C60 Films

We report an ultra-high vacuum low-temperature scanning tunneling microscopy (STM) study of the C60 monolayer grown on Cd(0001). Individual C60 molecules adsorbed on Cd(0001) may exhibit a bright or dim contrast in STM images. When deposited at low temperatures close to 100 K, C60 thin films present a curved structure to release strain due to dominant molecule–substrate interactions. Moreover, edge dislocation appears when two different wavy structures encounter each other, which has seldomly been observed in molecular self-assembly. When growth temperature rose, we found two forms of symmetric kagome lattice superstructures, 2 × 2 and 4 × 4, at room temperature (RT) and 310 K, respectively. The results provide new insight into the growth behavior of C60 films.

scholarly journals Au(100) as a Template for Pentacene Monolayer

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2393
Author(s):  
Artur Trembułowicz ◽  
Agata Sabik ◽  
Miłosz Grodzicki
Keyword(s):  
Self Assembly ◽  
Molecular Layer ◽  
High Vacuum ◽  
Gold Surface ◽  
Ultra High Vacuum ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Height Difference ◽  
Characteristic Features ◽  
Reconstructed Surface

The surface of quasi-hexagonal reconstructed Au(100) is used as the template for monolayer pentacene (PEN) self-assembly. The system is characterized by means of scanning tunneling microscopy at room temperature and under an ultra-high vacuum. A new modulated pattern of molecules with long molecular axes (MA) arranged along hex stripes is found. The characteristic features of the hex reconstruction are preserved herein. The assembly with MA across the hex rows leads to an unmodulated structure, where the molecular layer does not recreate the buckled hex phase. The presence of the molecules partly lifts the reconstruction—i.e., the gold hex phase is transformed into a (1×1) phase. The arrangement of PEN on the gold (1×1) structure is the same as that of the surrounding molecular domain on the reconstructed surface. The apparent height difference between phases allows for the distinction of the state of the underlying gold surface.

Structural changes from polyimide films to graphite: Part IV. Novax and PPT

1995 ◽  
Vol 10 (4) ◽  
pp. 1024-1027 ◽  
Author(s):  
C. Bourgerette ◽  
A. Oberlin ◽  
M. Inagaki
Keyword(s):  
Long Range ◽  
Structural Changes ◽  
Film Plane ◽  
High Rank ◽  
Polyimide Films ◽  
Electron Microscopies ◽  
Higher Temperature ◽  
Cross Linker ◽  
Graphite Part

Various polyimide films (Kapton, Upilex, Novax, and PPT) were carbonized and graphitized up to 3000 °C. They were studied by optical and electron microscopies. All films retaining oxygen as a cross linker over 1000 °C, i.e., Kapton, Upilex, and Novax, graphitize as anthracites (high rank coals) do. They get a long range statistical orientation parallel to the film plane with a nanotexture of flattened pores. Graphitization is both sudden and perfect above 2100 °C when the pore walls break. Since oxygen is released at 1000 °C, the film PPT behaves as a compact nonporous graphitizing carbon (orientation parallel to the film plane). Thermal graphitization is progressive and begins at a higher temperature.

scholarly journals A modular ultra-high vacuum millikelvin scanning tunneling microscope

2020 ◽  
Vol 91 (2) ◽  
pp. 023703 ◽  
Author(s):  
Dillon Wong ◽  
Sangjun Jeon ◽  
Kevin P. Nuckolls ◽  
Myungchul Oh ◽  
Simon C. J. Kingsley ◽  
...  
Keyword(s):  
Scanning Tunneling Microscope ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Scanning Tunneling ◽  
Tunneling Microscope

Polyamic Acid Langmuir-Blodgett (LB) Films Containing A Stable Second-Order NLO Chromophore

1995 ◽  
Vol 413 ◽  
Author(s):  
D. W. Cheong ◽  
J. -I Chen ◽  
J. Kumar ◽  
S. K. Tripathy
Keyword(s):  
Nonlinear Coefficient ◽  
Polarized Light ◽  
Second Order ◽  
Polyimide Films ◽  
Polyamic Acid ◽  
Lb Films ◽  
Langmuir Blodgett ◽  
Number Of Layers ◽  
Absorption Correction ◽  
Nlo Chromophores

ABSTRACTNonlinear optical (NLO) LB films of polyamic acid containing a stable NLO dye were prepared and imidized either chemically or thermally. The optical properties and molecular orientation of these LB films were studied. From the absorption spectra, we infer that the derivative of the pnitroazobenzene chromophore covalently attatched to polyamic acid did not show significant aggregation. Quadratic dependence of SHG on the number of layers in polyamic acid films indicated the noncentrosymmetric organization of polar NLO chromophores. A second-order nonlinear coefficient (d33) of 23.4 pm/V was observed at 1064 nm after absorption correction. In polyimide films, SH intensity was dramatically reduced due to the collapse of the layered structure upon imidization process. In-plane isotropy of the LB films of polyamic acid and polyimide were lost upon irradiation of polarized light.

Surface stability of epitaxial SrRuO3 thin films in vacuum

2004 ◽  
Vol 19 (12) ◽  
pp. 3447-3450 ◽  
Author(s):  
J. Shin ◽  
S.V. Kalinin ◽  
H.N. Lee ◽  
H.M. Christen ◽  
R.G. Moore ◽  
...  
Keyword(s):  
Thin Films ◽  
High Vacuum ◽  
Hydrocarbon Contamination ◽  
Laser Deposition ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Surface Stability ◽  
Low Energy Electron Diffraction ◽  
Low Energy Electron ◽  
Deep Pits

Surface stability of nearly defect-free epitaxial SrRuO3 thin films grown by pulsed laser deposition was studied using low-energy electron diffraction (LEED), scanning tunneling microscopy (STM), and electron spectroscopies. Even after exposure to atmosphere, surfaces exhibited distinct LEED patterns providing evidence of unusual chemical stability. Surface order disappeared after heating to 200 °C in vacuum. To investigate, SrRuO3 thin films were annealed up to 800 °C in high vacuum and examined for chemical state and topography. Formation of unit-cell deep pits and the Ru-rich particles begins at low temperatures. Hydrocarbon contamination on the surface contributes to this process.

Sign in / Sign up

Export Citation Format

Share Document