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AssigneeInternational Business Machines Corporation
InventorsGerald F. Hait, Robert W. Nufer
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Ceramic substrates used in the fabrication of electrical components are generally formed by casting a composition comprising ceramic, binder, solvent and optional wetting agent onto a support, removing the casting composition solvent to yield a ceramic green sheet and firing the ceramic green sheet at elevated temperatures. In such a process, internal stresses are generated in the ceramic green sheet after casting compositions solvent evaporation, which stresses cause dimensional changes in the ceramic green sheet with the passage of time and adversely effect critical component tolerances. The present invention provides a process for stabilizing ceramic green sheets against dimensional changes, which occur with the passage of time and/or upon screening the ceramic green sheet with metallurgical patterns, by contacting the ceramic green sheet, after casting composition solvent removal, with a solvent which softens the binder in the ceramic green sheet and permits stress relieving.
A process for stabilizing a cast, substantially completely dried ceramic green sheet comprising a particulate ceramic and a thermoplastic polymeric binder which comprises contacting said cast ceramic green sheet with a solvent for said thermoplastic polymeric binder for a period of time sufficient to plasticize and soften but not dissolve said thermoplastic polymeric binder, and then again drying the cast ceramic green sheet prior to sintering such ceramic green sheet.
Dependencies are inferred from the claim text.