Pinhole free films

Capacitors. The outstandingly low dielectric loss of parylenes make them superior candidates for dielectrics in high quality capacitors. Furthermore, their dielectric constant and loss remain constant over a wide temperature range. In addition, they can be easily formed as thin, pinhole-free films. Kemet Flatkaps are fabricated by coating thin aluminum foil with Parylene N on both sides and winding the coated foils in pairs (62). 

Some other PFs end capped with cross-linkable groups, such as benzocyclobutene, have been patented by Dow Chemicals [275-277]. For example, the thermal curing of spin-coated polymer 232 gave an insoluble pinhole-free film without alteration of the fluorescent properties (Chart 2.57). 

It is possible to inhibit reaction (5) by employing spray pyrolysis to deposit a compact layer of 2 on the Sn02 substrate before deposition of the nanocrystalline 2 film [9,10]. It is, however, relatively difficult to achieve a pinhole-free film. We chose to investigate the electropolymerization of an insulating film on the exposed parts of the Sn02 after the nanocrystalline 2 film has been depos-... 

The transparent, colorless and pinhole-free film has a high tensile strength and elongation a low permeability to water and oxygen a glass transition temperature of 95°C and, is insoluble in aqueous and organic solvents (6). 

Van der Waals forces between the methylene groups orient the monolayer. Such a self-assembly process thus results in well-organized and stable mono-layers, with the hydrocarbon tails packed parallel to each other, tilted at -30° relative to the surface normal (Fig. 4.14). The closely-packed pinhole-free films (surface coverage of 9 x 10 10mol/cm2) block transport of species to the... 

Each organic layer should have uniform and pinhole-free thin films at a thickness of about 50 nm. Amorphous morphology was found to satisfy this requirement. Sometimes, polycrystalline thin films are also acceptable, when their grain sizes are less than 50 nm and they form dense pinhole-free films. The previous systematic studies proposed a molecular design for the formation of uniform thin films. It was reported that the introduction of bulky substituents and steric hindrance into molecular structures, as well as an appropriate three-dimensional steric configuration resulted in amorphous morphology.35,58,61... 

A latex paint is an aqueous emulsion. After the paint dries, the surfactant is still present and may interfere with the resistance of the paint to washing to remove fingerprints or other marks. A destructible surfactant would be valuable in this application. It would have to destruct by the action of light or air. Latex paints are not entirely free of solvent. A few percent of a higher-boiling solvent, a coalescing agent, is usually, but not always, necessary to form a pinhole-free film from the particles of polymer after the water evaporates. A typical one (8.45) is derived from isobutyraldehyde. 

A pulsed plasma has been used to prepare pinhole-free films from relatively nontoxic N vinylpyrrolidone.323 The pulsing reduced fragmentation of the monomer and cross-linking. This method should be tried with other monomers. Plasmas are often used for the modification of polymer surfaces.324 These methods are relatively rapid and use no solvent. Decorative coatings of TiN and other inorganic compounds can be applied to metals and other inorganic substrates by sputtering, chemical vapor deposition, plasmas, and such, as described in Chap. 4.325... 

This is a commonly applied technique in the microelectronics industry used to deposit thin uniform polymeric films. In this method the polymer, dissolved in a suitable solvent, is dropped onto the substrate whilst it is being spun at high speed. As a result the solution spreads out to form a thin uniform film across the substrate surface which, on evaporation of the solvent, leaves a polymer film over the surface of the substrate. The thickness of the film is determined by the rotation speed and by the viscosity of the polymer solution. The technique is only suitable for coating relatively flat substrates and for the deposition of reasonably thick (1 fim) pinhole-free films. Once deposited the polymer films can be cross-linked by suitable reactive reagents, heat, or light to produce robust, adherent films. 

Insulating films can be formed either by using monomers such as phenol [182, 183] or 1,2-diaminobenzene which yield non-conducting polymers or by overoxidation of conducting polymer films as described above. Insulating polymers, such as poly(phenol), form as thin (0.1 iim range) pinhole-free films at the surface. This allows very thin uniform films to be deposited. Films of... 

The general trend toward shorter production times and rationalisation of the production process is reflected in the "shock drying process , in which the paints are cured within a few seconds at up to 300 C. The thickness of the cured film is normally only 2-10 pm optimum flow behavior is therefore a prerequisite for a satisfactory pinhole-free film. 

The ease of preparation and the unique properties of the polymers produced by plasma polymerization have lead to applications for pinhole-free films in protective coatings, insulating layers, and membranes for reverse osmosis. 

A 70 nm thick, smooth and pinhole-free film was successfully printed using a 100 lines/cm and 37 pm cell depth gravure cylinder and modified ink containing 65 wt% of PEDOT PSS, 1 wt% Tween 80, and 34 wt% isopropyl alcohol. The PEDOT PSS layer was subsequently dried at 110 °C with a web speed of 8 m/min. 

Vacuum deposition Ultrathin, pinhole-free films possible. Selective deposition can be made through masks. Thermal instability of most plastics decomposition occurs on products. Vacuiun control needed. Experimental at present. Potential use is in microelectronics, capacitor dielectrics. 

AFM can be used to follow the deposition of thin films over time. Simple thickness measurements can be performed by either scoring the film with a scalpel after deposition or masking part of the substrate before deposition of the film, and measuring the height of the step created. In Fig. 2.5, plasma polymer films grown from acrylic acid monomer are shown to grow initially as discrete islands, which then coalesce and eventually form a flat, pinhole-free film after approximately 240 s. This result is contrary to the often-stated view of plasma deposition that films always grow as a conformal layer. 

The synthesis of redox polymers is generally performed before deposition (124). First, a polymer is synthesized by condensation or addition polymerization with at least one monomer that is ledox-aclive. The polymer is immobilized on the substrate by dip-coating, drop-casting, or spin-coating. These procedures must be carefully applied if homogeneous and pinhole free films are needed. 

Miniaturization of the conjugated polymer/Ceo heterojunction devices described above has been realized by Rubner and co-workers [154-156,159]. Very uniform and pinhole-free films with charged, functionalized, conjugated polymers and fullerenes were demonstrated using the techniques of self-assembly [154-157]. Fabrication of 15 nm PPV light emitting diodes using the self-assembly of the precursor polymer on the substrate (followed by conversion to PPV) have been reported [154-157]. 

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