Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making named article
Patent
1989-10-27
1991-09-03
McCamish, Marion E.
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making named article
430330, 430198, G03C 540
Patent
active
050454374
DESCRIPTION:
BRIEF SUMMARY
The present invention is directed to a method for producing a structured ceramic film. Further, the invention is directed to the manufacture of a ceramic member composed of such ceramic films. The structuring of such a ceramic film is comprised in depressions or, respectively, recesses that can also be holes that proceed through the film. The production of the depressions, recesses or holes thereby ensues by processing the film in the condition of a green film. What is to be understood by a green film is the intermediate stage occurring in the manufacturing method of a ceramic film wherein the suspension material to be subsequently sintered to form a ceramic and having the bonding agent or, respectively, binding system contained therein is brought into the shape of the as yet unsintered film.
A known method of this species is to provide the green film composed of the suspension material and the binder system and acquired by drawing the suspension into a film with holes by punching and, finally, to sinter this structured green film. A thin ceramic film provided with these holes that corresponds to the thickness of the green film is thereby obtained, this ceramic film being capable of being employed, for example, as a substrate plate. Such substrate plates, particularly those of aluminum oxide, are especially employed in electronic circuit technology for formatting hybrid circuits.
It is already known to produce ceramic members provided with inwardly disposed or, respectively, inner cavities.
German published application 14 39 702 discloses a manufacturing method wherein cavities are already present in the ceramic member before the sintering of the ceramic member provided for a capacitor.
Development has progressed to the point of manufacturing the members of such multi-layer capacitors in such fashion that a structure composed of a mixture of lampblack and zirconium dioxide grains that corresponds to the structure of the prescribed cavities is applied on green films. Such green films provided with structures are stacked on top of one another, are pressed together and sintered, whereby the applied structure is pressed into the film. The lampblack burns during the sintering and the zirconium oxide grains remain in the arising cavities. The cavities that have arisen between the zirconium oxide grains are filled with molten metal, particularly lead, so that inner electrodes are formed.
Members that are composed of piezoelectric ceramic and are monolithic in their sintered condition but do not yet have filled inner cavities are employed as ultrasound transducers, particularly for medical diagnosis. The cavities that are so numerous and so small in the piezo ceramic material that they act like pores reduce the acoustic impedance of this material and thus improve the acoustic matching of the material of the ultrasound transducer to the body tissue. It has likewise already been proposed to fashion elongated cavities in the interior of the ceramic member of an ultrasound transducer. These cavities are fashioned and arranged such that they prevent or at least reduce the formation of disturbing modes of transverse vibrations.
The ceramic members coming into consideration here were manufactured in such fashion that individual green films were first provided with a structured photoresist layer or, respectively, with structures composed of photoresist in a photolithographic way and these films were then pressed to form a stack and were sintered. The stack that is sintered together forms a monolithic ceramic member in whose interior cavities that correspond to the photolithographic structures on the original green films are situated. The photoresist burns off during the sintering process and leaves corresponding cavities in the foil stack. Such cavities can be arranged exactly placed in a ceramic member (and, for example, can serve as electrodes when filled with metal). Cavities that are usually smaller and are arranged distributed in such a ceramic member sintered together of green films lead thereto that a designational
REFERENCES:
patent: 3703864 (1972-11-01), Bradford
patent: 4528260 (1985-06-01), Kane
patent: 4876179 (1989-10-01), Bast et al.
Chapman Mark
McCamish Marion E.
Siemens Aktiengesellschaft
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