Abstract: An object of the present invention is to provide a niobium sintered body free of reduction in the CV value, a niobium powder for use in the manufacture of the niobium sintered body, and a capacitor using the niobium sintered body. A niobium powder of the present invention has niobium and tantalum, where the tantalum is present in an amount at most of about 700 ppm by mass. A sintered body and a capacitor each is manufactured using the niobium powder.

Abstract: A process for extending the operating temperature limit of a polypropylene film capacitor to greater than 105° C., by use of a post assembly curing process of placing the capacitor in a 10 Torr or less pressure environment, preferably less than 1 Torr, and slowing heating it at a rate of less than an average rate of 5° C./hour to a peak temperature of about 10 to 20 degrees higher than the intended operating temperature, the peak temperature being not more than preferably 180° C.

Abstract: A film capacitor includes a novel hybrid polymeric film dielectric in which at least one non-polar dielectric homopolymer resin is blended homogeneously in solid-solution with at least one other dielectric polymer resin. The properties of at least one of the dielectric polymer resin constituents of the hybrid polymeric film dielectric are selected to produce a tailored property or properties of the solid-solution blend thereof. The non-polar homopolymer serves to stabilize the hybrid polymeric film. In the film capacitor configuration, the hybrid polymeric film is tightly sandwiched between conformable metal plates.

Abstract: A solid electrolytic capacitor minimized in both equivalent serial resistance (ESR) and equivalent serial inductance (ESI) by eliminating redundant space created by its electrode is presented. The solid electrolytic capacitor includes a capacitor element including mainly of a positive electrode body, having a positive electrode lead embedded therein, and made of any form of a valve metal, such as a net, a sheet, a foil, and modifications thereof with a rough surface; a positive electrode terminal connected to the positive electrode lead; a negative electrode terminal connected to a negative electrode layer; and a housing resin coated by molding. This improves the installation efficiency of the capacitor element, and contributes to the small, thin structure of the solid electrolytic capacitor.

Abstract: An object of the present invention is to provide a niobium sintered body free of reduction in the CV value, a niobium powder for use in the manufacture of the niobium sintered body, and a capacitor using the niobium sintered body. A niobium powder of the present invention has niobium and tantalum, where the tantalum is present in an amount at most of about 700 ppm by mass. A sintered body and a capacitor each is manufactured using the niobium powder.

Abstract: The present invention relates to a capacitor installed in the automobile engine room, comprising polyethylene-2,6-naphthalate film comprising polyethylene-2,6-naphthalate with an intrinsic viscosity (IV) of not less than 0.56 and having a degree of crystallinity of 32 to 42%, the film elongation retention after a 3,000-hour degradation test at 170° C. being not less than 50%, and the residual elongation of the film after said test being not less than 30%.

Abstract: A capacitive element for a circuit board or chip carrier having improved capacitance and method of manufacturing the same is provided. The structure is formed from a pair of conductive sheets having a dielectric component laminated therebetween. The dielectric component is formed of two or more dielectric sheets at least one of which can be partially cured or softened followed by being fully cured or hardened. The lamination takes place by laminating a partially cured or softened sheet to at least one other sheet of dielectric material and one of the sheets of conductive material. The total thickness of the two sheets of the dielectric component does not exceed about 4 mils and preferably does not exceed about 3 mils; thus the single dielectric sheets does not exceed about 2 mils and preferably does not exceed about 1.5 mils in thickness.

Abstract: A capacitor and method in which there is provided additional extraneous plate surface area, beyond the paired plate surface area normally provided to furnish capacitance. This additional extraneous plate surface area is located outside the intraplate internal volume, of plate pairs contributing substantial capacitance, or of mutually facing n-tuples of plates. Various configurations for this additional extraneous plate surface area are taught. This additional extraneous plate surface area can improve the electrical performance of the capacitor.

Abstract: A laminated capacitor and a process for producing the same. The laminated capacitor includes a plurality of capacitor assemblies and external electrodes, the capacitor assemblies each including a thermoplastic resin film having consecutively thereon a metal film as a first internal electrode, an inorganic dielectric material film, and a metal film as a second internal electrode, the plurality of capacitor assemblies being laminated with each other to form a laminated body, the external electrodes each being provided on an end surface of the laminated body, on which the first or second internal electrode is exposed, and being electrically connected to the first and second internal electrodes, respectively.

Abstract: A multiple position or continuously variable capacitive switch which operates by producing a series of discernable changes in the capacitance between a pair of conductors (14,16) disposed in a spaced coplanar relationship on a surface of a non-conductive substrate (12). A dielectric layer (18) is applied over the conductors (14,16) and exposed areas of the substrate (12) surface. A resilient conductive pad (20) is positioned atop the dielectric layer (18) and a user movable actuator (28) is moved to controllably increase the capacitance between the conductors (14,16) by creating progressively greater areas of compression between conductive pad (20) and dielectric layer (18).

Abstract: Sheet capacitive materials for use in forming a thin-film capacitor comprise an electrically nonconductive substrate, a layer of electrically conductive material disposed a surface of the substrate, and a layer of electrically nonconductive material disposed onto a surface of the conductive material layer. The conductive material layer includes a contact area along a first lengthwise edge of the substrate that is thicker than remaining portions of the material layer. A portion of the substrate adjacent a second lengthwise edge remains exposed. The electrically nonconductive material includes an anti-stick component, and covers the exposed substrate surface and a major portion of the material layer except for the contact area. A first and second sheet is constructed having contact areas along opposite lengthwise edges. The sheets are placed together so that the contact areas are oriented at opposite lengthwise edges, and are staggered so that the contact areas remain exposed.

Abstract: A high energy density, high power density capacitor having an energy density of at least about 0.5 J/cm.sup.3 is provided. The capacitor comprises a plurality of interleaved metal electrode layers separated by a polymer layer. The interleaved metal electrode layers terminate at opposite ends in a solder termination strip. The high energy density aspect of the capacitors of the invention is achieved by at least one of the following features: (a) the dielectric thickness between the interleaved metal electrode layers is a maximum of about 5 .mu.m; (b) the polymer is designed with a high dielectric constant .kappa. of at least about 3.5; (c) the metal electrode layers within the polymer layer are recessed along edges orthogonal to the solder termination strips to prevent arcing between the metal electrode layers at the edges; and (d) the resistivity of the metal electrode layers is within the range of about 10 to 500 ohms per square, or a corresponding thickness of about 200 to 30 .ANG..

Abstract: A solid electrolytic capacitor having a solid electrolyte comprising manganese dioxide dispersed in an aromatic polyamide capable of further cure to form polyimide linkages, the solid electrolyte being disposed between a first electrode made of valve metal covered by an anodic oxide film and a second electrode opposite the first electrode. The electrolyte autogenously produces water, oxygen, and hydroxyl groups which act as healing substances and is not itself produced pyrolytically. Reduction of the manganese dioxide and the water molecules released by formation of imide linkages result in substantially improved self-healing of anodic dielectric layer defects.

Abstract: A metallized plastic film capacitor is here disclosed which is impregnated with an electrically insulating oil composition comprising 10 to 95% by weight of an aromatic hydrocarbon having at least 3 benzene rings and 90 to 5% by weight of an olefin oligomer containing 7% by weight or less of a fraction having a molecular weight of 500 or less and 2% by weight or less of a fraction having a molecular weight of 400 or less.

Abstract: A capacitor has a plastic film (4a, 4b), an aluminum deposition film (5a, 5b) formed on the plastic film (4a, 4b), and a zinc deposition film (6a, 6b) formed on the aluminum deposition film (5a, 5b) over the side of one edge part of the plastic film (4a, 4b).

Abstract: A capacitor having an enhanced dielectric breakdown strength is obtained m a base dielectric film by coating the base dielectric film on both sides with an adherent coated dielectric film having a dielectric constant that is at least 50 percent higher than that of the base dielectric film and that adheres to the base dielectric film; and wherein metal foil is adherently joined to each of the coated dielectrics films to form electrodes for the capacitor.

Abstract: A capacitor employing plural dielectric materials between oppositely facing, distinctly electrically connected plates, or employing interspersed plural dielectric materials outside the space between oppositely facing, distinctly electrically connected plates, wherein one material is a plastic and a second material is a plastic, gas, or vacuum. A method for ameliorating the frequency dependent variation pattern in dielectric behavior, of a single material employed as a dielectric in a capacitor, by employing a plurality of materials between oppositely facing, distinctly electrically connected plates, and/or by employing an interspersed plurality of materials outside the space between oppositely facing, distinctly electrically connected plates.

Abstract: A power capacitor including at least one capacitive winding, of self-healing type, located in a case made of plastic material and coated in a polymerizable resin cast directly into the case. The capacitor includes a breaking device sensitive to an overpressure. Passage of gases in the direction of the breaking device is achieved by deformation of the plastic material constituting the case. The plastic material of the case presents predetermined mechanical strength, impact strength and thermal resistance characteristics.

Abstract: A capacitor for temporary storage of electrical energy comprising at least two capacitor elements (2) composed of electrodes (5) which are separated by one or more dielectrics (6), and especially a power capacitor for high voltage. When the capacitor is being loaded, electrostatic forces give rise to mechanical forces between the electrodes in the capacitor. The forces give rise to vibrations which radiate as sound from the surface of the capacitor. Between, or adjacent to, packages (10) of compressed capacitor elements (2), there are placed one or more active or passive spring elements (11), which are adapted to change the natural frequencies of the capacitor. In this way, the oscillation resistance of the capacitor may be changed at the frequency ranges where the force is acting. The vibrations in the surface layer of the capacitor decrease, resulting in reduced sound radiation from the capacitor.

Abstract: Disclosed herein is a metallized polyester film capacitor comprising:a polyester film;a coating layer formed on at least one side of said polyester film, said coating layer having a thickness (t) of 0.01 to 2 .mu.m and containing 0.1 to 20 wt % of the particles having an average diameter (D) that satisfies the following formula (I); anda metal layer deposited on at least one side of the polyester film having said coating layer.0.5.ltoreq.D/t.ltoreq.

Abstract: A method for the manufacture of foil capacitors with metallized plastic films, said method comprising the following steps:coiling at least one pair of metallized plastic films so as to form the stacked structure of the capacitors;metallizing the lateral faces of the coiled structure in order to create the plates of the capacitors;cutting out the coiled and metallized structure, or parent capacitor, into semi-finished capacitors;putting the semi-finished capacitors and their connection wires through a cleansing flux;soldering the connection wires to the plates of the semi-finished capacitors;wherein the soldering is done by wave soldering and wherein, between said metallization and said cutting, a heat treatment operation designed to give the plastic film the characteristics needed to withstand the wave soldering and a new metallization designed to ensure the mechanical and electrical quality of the connections are carried out successively.

Abstract: A metallized polyester film capacitor comprising as dielectric, a polyester film having a coating layer on at least one side of the polyester film, the coating layer comprising a polycarbonate polyurethane, and a metal deposited on the coated layer.

Abstract: Non brittle dielectric films are formed by blending a cyanoresin such as cyanoethyl, hydroxyethyl cellulose (CRE) with a compatible, more crystalline resin such as cellulose triacetate. The electrical breakdown strength of the blend is increased by orienting the films by uniaxial or biaxial stretching. Blends of high molecular weight CRE with high molecular weight cyanoethyl cellulose (CRC) provide films with high dielectric constants.

Abstract: A multi-layer capacitor comprising a stack of sheet electrodes with an insulating dielectric layer sandwiched between these layers is disclosed. The dielectric layer formed on the electrode is prepared by the "sol-gel" process.

Abstract: A series section metallized film capacitor in which the metal layers are varied in thickness such that high oxidation areas are thicker than low oxidation areas. In particular, the edge portions bordering a center margin electrode gap have a thickness which is greater than the remaining area of the center margin electrode. The increased thickness at the edge portions reduces the oxidation effect and the associated decrease in capacitance which normally occurs due to the electric potential across the gap. By varying the thickness, the oxidation effect at the edge portions is reduced while the self-healing capabilities at the low oxidation areas is maintained.

Abstract: Very thin films of cellulose triacetate are cast from a solution containing a small amount of high boiling temperature, non-solvent which evaporates last and lifts the film from the casting surface. Stretched, oriented, crystallized films have high electrical breakdown properties. Metallized films less than about 2 .mu.m in thickness form self-healing electrodes for high energy density, pulsed power capacitors. Thicker films can be utilized as a dielectric for a capacitor.

Abstract: Material for winding high voltage capacitors is prepared by evaporating polyfunctional acrylate monomer having a molecular rate in the range of from 150 to 600 and condensing the acrylate as a monomer film on a dielectric substrate. The acrylate is polymerized by irradiation by ultraviolet or electrons. Sometimes both faces of the dielectric are coated to protect the thermoplastic dielectric from swelling when exposed to dielectric liquid. The metallized layer provides an electrode of the capacitor. A polymerized acrylate layer may be applied over the metal layer. Electrical contact can be made to the metal layer by Schooping even though the metallized layer is covered by a layer of acrylate. Low oxygen permeability polypropylene, polyester or nylon sheet has a layer of crosslinked acrylate and an oxygen barrier layer formed of silicon oxide, aluminum oxide or metal. Adhesion is enhanced by plasma or corona treatment of a surface immediately before deposition.

Abstract: A biaxially oriented polyethylene-2,6-naphthalate (PEN) film for capacitor dielectric which contains the specific monodisperse cross-linked polymer particles is described. The capacitors using the PEN film have excellent handling qualities and workability as well as excellent electrical properties.

Abstract: The manufacturing process of a capacitor with a polypropylene dielectric film by introducing pre-cross-linking elements of the polypropylene at the time of manufacturing. When the capacitor is used, the electrical field and/or temperature generated trigger the cross-linking process of the polypropylene, delaying and slowing down the ageing phenomena, i.e. the decrease of the dielectric strength. The pre-cross-linking agent is a polyfunctional monomer to which an activation accelerator and/or a stabilizing agent can be added.

Abstract: Dielectric materials having a high dipole moment density are provided. The high dipole moment density is achieved by the use of a substituted .alpha.-amino acid, such as N-trimethyl glycine and related homologues having nonpolar sidechain groups, with three alkyl substitutions on the nitrogen of the .alpha.-amino group. These molecules have a high dipole moment and small volume, allowing rapid rotation around the .alpha.-amino, carboxyl dipole. N-trimethyl glycine alone or in combination with one or more homologues is preferably provided as a solute in a liquid dielectric solution. Alternatively, these molecules are provided as substituents on a linear polymer.

Abstract: An MF capacitor of an oil impregnation type, whose durability in constant voltage application is so high that it is suitable for practical use. The metallized plastic film is impregnated with an electrically insulating oil composition obtained by adding 5-80% by weight of natural fatty acid triglyceride which contains a less amount of fatty acid ester having free hydroxyl radical to an aromatic hydrocarbon having a specific chemical structure and being liquid at -30.degree. C.

Abstract: A capacitor comprising a polyethylene 2,6-naphthalate film as a base film, a coating layer, formed on at least one surface of said base film, which coating layer comprises a water-soluble or water-dispersible resin and has a center line average surface roughness (Ra) of 0.005 to 0.5 .mu.m, and a metal layer deposited on said coated polyethylene 2,6-naphthalate film, wherein said coated polyethylene 2,6-naphthalate film has an F5 value in a machine direction of at least 1.5.times.10.sup.8 Pa, a Young's modulus in a machine direction of at least 5.9.times.10.sup.9 Pa, and a Young's modulus in a transverse direction of at least 5.9.times.10.sup.9 Pa, which capacitor has good moist-heat resistance and long-term stability.

Abstract: The electrical breakdown strength of capacitors is increased by briefly esing the dielectric, the metal foil, and/or the fully assembled capacitor to a low pressure, low temperature gas plasma.

Abstract: This invention provides oligomer-free polyesters that consist essentially of repeating, interpolymerized units derived from isophthalic acid and/or terephthalic acid, and 9,9-bis-(4-hydroxyphenyl)-fluorene, a process for making such polyesters and articles comprising said polyesters such as electrical capacitors, optical films and fibers.

Abstract: A biaxially stretched polypropylene monofilm, wherein the surfaces of the two sides of the polypropylene monofilm have different roughnesses R.sub.Z, is employed as an insulation film for the production of capacitors. The smoother of the two surfaces of the polypropylene monofilm is substantially free from fibrils and pits, so that no flaws occur in a metal layer applied on metallization of this surface.

Abstract: A monomolecularfilm which can be used as a dielectric film is obtained on a substrate surface. For example, an aluminum foil electrode substrate having a natural oxide film is obtained by chemically adsorbing a chlorosilane-based surface active material comprising a fluorocarbon chain to the substrate. It is possible in this invention to have a pre-treatment as follows in lieu of using the natural oxide layer: forming an electrolytic oxidated layer by electrolytic oxidation of the metallic film, or bonding a thin oxide layer such as SiO.sub.2, Al.sub.2 O.sub.3 being several hundred nanometers in thickness to the surface metallic film by spatter deposition, thus obtaining an excellent capacitor. A capacitor can be obtained by deposition of the aluminum layer on the surface bilayer laminated film.

Abstract: A flexible capacitor (1) includes a dielectric made of flexible material, coated on each side with conductive material for insertion between a cable shield being at the ground potential of a remote electrical machine, and a part on a local machine being at the local ground potential (3, 5, 2) for example at a connector (7) level.

Abstract: At least a part of a protective layer (1, 4a, 4b, 5a, 5b, 6a, 6b,6c, 7, 8a, 8b) provided on the outer surface of a capacitance generating portion (2) of a film capacitor is constructed from a substantially non-oriented polyphenylenesulfide film (10). Since the non-oriented polyphenylenesulfide film (10) substantially does not accompany thermal shrinkage when it is heat stuck or soldered, and it absorbs the deformation due to the thermal shrinkage of other layers of the protective layer, the sticking stability and dimensional stability in the protective layer can be ensured. As a result, the thermal resistance of the protective layer and the thermal resistance of the capacitor can be improved as well as the simplification of sticking process or omission of an adhesive becomes possible. Moreover, this can serve to further miniaturization of capacitors.

Abstract: The present invention relates to an aluminum deposited film and a process for producing it. Since the surface area coefficient C of the surface of the deposited layer is not greater than 1.00.times.10.sup.-4 or aluminum crystals the [1, 1, 0] planes of which are oriented in parallel with the surface of a base film are contained in an aluminum thin layer in an aluminum deposited film. The corrosion resistance in a high-temperature and high-humidity atomsphere of the aluminum deposited film is excellent. A capacitor coated with the aluminum deposited film has excellent moisture resistance even if its encapsulation is simple, or has increased moisture resistance when its encapsulation is constructed as one similar to that of a conventional capacitor.

Abstract: A capacitor comprising a multiplicity of needlelike metal particles dispersed in a synthetic resin film and so oriented that the axes thereof are positioned in parallel to the surface of the film, and an electrode provided on each of opposite surfaces of the synthetic resin film, the metal particles having a diameter of up to 0.1 .mu.m, a length 5 to 10 times the diameter and a specific surface area of 30 to 100 m.sup.2 /gr and being covered with a dielectric oxide over the surface thereof.

Abstract: Electrical devices, e.g. molded circuit boards, connectors and capacitors, fabricated from electrical insulating component, comprising norbornene dicarboximide thermoplastic polymer exhibiting a glass transition temperature greater than about 200.degree. C., moisture absorption after equilibrating in boiling water of less than about 3 weight percent and an electrical permittivity at 1000 hertz measured at 25.degree. C. and 50 percent relative humidity of less than 2.8. Preferred polymers comprise N-methyl norbornene dicarboximide, N-ethyl norbornene dicarboximide, N-propyl norbornene dicarboximide, N-butyl norbornene dicarboximide, N-trifluoroethyl norbornene dicarboximide, N-phenyl norbornene dicarboximide, N-trifluoromethylphenyl norbornene dicarboximide, N-cyclohexyl norbornene dicarboximide, N-cycloheptyl norbornene dicarboximide, N-cyclooctyl norbornene dicarboximide.

Abstract: This invention provides oligomer-free polyesters that consist essentially of repeating, interpolymerized units derived from isophthalic acid and/or terephthalic acid, and 9,9-bis-(4-hydroxyphenyl)-fluorene, a process for making such polyesters and articles comprising said polyesters such as electrical capacitors, optical films and fibers.

Abstract: A new electrical insulating oil composition having improved low temperature characteristics which composition comprises a mixture of 40% by weight or more of benzyltoluene and the remainder of alkyl substituted diphenylmethane having 15 to 17 carbon atoms which is represented by the following general formula: ##STR1## wherein R.sub.1 and R.sub.2 are C.sub.1 to C.sub.4 alkyl groups and the total number of carbon atoms in R.sub.1 and R.sub.2 is 1 to 4, with the proviso that R.sub.1 and R.sub.2 may not simultaneously be methyl groups and the proportion of the total quantity of solid phase calculated according to the following general solid-liquid equilibrium equation is 45% by weight or less relative to the total quantity of said composition at -40.degree. C.: ##EQU1## where X.sub.i is the equilibrium mole fraction of a component i, in the liquid phase, .DELTA.H.sub.i.sup.f is the heat of fusion (cal.mol.sup.-1), T.sub.i.sup.

Abstract: Disclosed in this invention is a capacitor comprising a dielectric thin film being sandwiched by two layers of thin film electrodes directly or through interposition of a suitable thin film, and lead electrodes connected to said thin film electrodes, said dielectric thin film being a chemically adsorbed monomolecular film or a chemically adsorbed monomolecular built-up film made from a chlorosilane surface active agent. The molecules having large dipoles are incorporated in the molecules of the surface active agent to enhance the dielectric strength of the monomolecular film.

Abstract: An electrical insulating film which comprises a styrene polymer having a syndiotactic configuration and containing not more than 1,000 ppm of residual aluminum derived from the catalyst used in the production of the styrene polymer, and not more than 3,000 ppm of residual styrene monomer, and a condenser comprising metal electrodes and the above film which is 0.5 to 30 .mu.m thick and has crystallinity of not less than 25%, are disclosed.

Abstract: Method for making a capacitive structure. In a first mode, one coil of the interleaved webs is made from a laminate comprising a carrier tape, and two metallized, dielectric films, which may be ultra thin. One such web is wound into a coil. The other web and the carrier tape are twisted, by one half-turn, and wound over such one web and the carrier tape is peeled away so that the webs are interleaved. In a second mode, two coils of the interleaved webs are made from two laminates, each as described. One such web from one such laminate and one such web from the other laminate are wound into each coil so that the webs are interleaved. Techniques for providing each web with demetallized lanes and for slitting the webs into ribbons are disclosed. The carrier tape can be optionally omitted in some instances.

Abstract: A high-frequency capacitor includes first and second conductive members, each having a plurality of U-shaped metal plates disposed parallel to each other and a terminal plate coupled between the ends thereof. The metal plates of the first and second conductive members are interleaved, and a dielectric material is disposed between the adjacent metal plates. The result is a low-inductance capacitor suitable for use in a high-frequency electronic circuit, such as an electrodeless high intensity discharge (HID) lamp ballast. Furthermore, such acapacitor may be suitably integrated with a heat sink in an electrodeless HID lamp ballast.

Abstract: A film capacitor which has a plurality of electrodes; at least one layer of dielectric member made of organic material and interposed between each pair of neighboring electrodes; impreganated members made of organic material and disposed in a gap between the electrode and the dielectric layer or between the dielectric layers; and end electrodes applied respectively to opposite electrode drawout end faces and connected alternately with the electrodes. The dielectric layers and the impregnated members alternate with each other and have respective end faces. The end portions of the dielectric layers and impregnated members are indented to provide respective indented end face.

Abstract: A monolithic multi-layer capacitor is disclosed having a central capacitively active area and two electrode joining sections separated from the active area by sloped sections. The dielectric layers are about 1 micron thick in the active area and taper gradually to zero thickness in the sloped sections. Electrode layers in the active area have a thickness in the range from 200 to 500 Angstroms and sufficient thickness throughout the sloped sections for adequate current carrying capacity. Various acrylates are used for the dielectric layers, the number of layers ranging from a few to many thousands.Apparatus and methods are disclosed for the fabrication of such capacitors on a high speed, production scale basis. Such employ techniques for the flash evaporation of highly reactive monomers of acrylate dielectric materials so as to form a gaseous stream of such materials.

Abstract: A coextruded, biaxailly oriented multilayer film comprises a base layer comprising an extremely pure raw material and outer layer. It is suitable for use as an electrically insulating film, as a dielectric in an electrical capacitor, and has improved dielectrical properties for this purpose. The base layer and the outer layer or layers contain propylene polymer on one or both sides and stabilizers for propylene polymers. The raw material for the base layer has an idealized thermal oxidation temperature in the range of 260.degree. to 300.degree. C., preferably in the range 260.degree. to 280.degree. C., and the raw material for the outer layer or layers has an idealized thermal oxidation temperature in the region of 240.degree. to 300.degree. C., preferably in the range 240.degree. to 270.degree. C. The multilayer film as a whole has an idealized thermal oxidation temperature in the range 250.degree. to 290.degree. C., in paticular in the range 250.degree. to 275.degree. C.