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US 4,867,935 AGranted
Method for preparing ceramic tape compositions
AssigneeE. I. Du Pont de Nemours and Company
InventorWilliam H. Morrison, Jr.
Life of this patent
Estimating the term…
Abstract
A method for preparing a dielectric ceramic composition containing hollow microspheres which is castable on a substrate in the form of a tape or sheet for multilayer circuits in which crushing or breaking of the microspheres is avoided, and a multilayer sheet structure formed from said tape.
Claims10
A method for making a dielectric sheet composition having a low dielectric constant and a high hermeticity comprising the steps of:
- (a) mixing a glass powder having an average particle size in the range of 0.3 to 50 .mu.m with a volatile, organic solvent containing an organic polymer binder and an organic plasticizer to form a uniform dispersion;
- (b) milling the dispersion to pulverize and uniformly disperse the glass component;
- (c) dispersing ceramic hollow microspheres having a particle size in the range of 10-200 .mu.m at high speed into the milled dispersion to form a slip having a viscosity in the range of 500-1500 cps;
- (d) deareating the slip and casting a thin layer thereof onto a flexible substrate forming a sheet within one hour of final mixing and heating the cast layer until solvent has been removed;
- and
- (e) removing the sheet fromm the substrate and firing it to remove organic material and then sintering the sheet.
3 more elements
A method for making a dielectric sheet composition having a dielectric constant in the range of 3 to 5.5 at 1 MHz and a density greater than 93% of theoretical comprising the steps of:
- (a) mixing a glass powder having an average particle size in the range of 1 to 50 .mu.m, in an amount sufficient to constitute 50 to 95 vol. % of the dielectric composition, with a volatile, non-aqueous organic solvent polymeric binder comprising 5 to 20% by weight of the mixture and 10 to 50% by weight based on the polymeric binder of an organic plasticizer;
- (b) milling the mixture for 1 to 2 hours to pulverize and uniformly disperse the glass component;
- (c) adding ceramic hollow microspheres having a particle size in the range of 10 to 200 .mu.m, in an amount sufficient to constitute 10 to 50 vol. % of the dielectric composition, and dispersing them at high speed to form a slip having a viscosity in the range of 500 to 1500 cps;
- (d) deaerating the slip and within one hour of final mixing casting a thin layer thereof having a thickness variation of not more than .+-.2% onto a flexible substrate to form a sheet, and heating the cast sheet at 20.degree. to 50.degree. C. to remove the solvent;
- (e) removing the sheet from the substrate and heating it in an oxidizing atmosphere at 300.degree. to 500.degree. C. to remove organic material and thereafter sintering the sheet by raising its temperature to 800.degree. to 950.degree. C. for at least 30 minutes.
2 more elements
Dependencies are inferred from the claim text.