Ceramic dielectrics
AssigneeInternational Business Machines Corporation
InventorsLeslie C. Anderson, Robert W. Nufer, Frank G. Pugliese
Life of this patent
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Abstract
Production of a sintered ceramic dielectric formed from a green sheet having a uniform microporous structure providing uniform dielectric properties and compressibility for lamination of stacked green sheets into a unitary laminate which may be provided with an internal pattern of electrical conductors extending therein. The structure is obtained by blending the ceramic particulate in a solution of a binder resin miscible in a solvent mixture which is formed from a volatile solvent for the binder resin and a less volatile solvent in which the resin is at most only slightly soluble.
Claims32
In a process for forming ceramic substrates, the steps comprising
- A. formulating a ceramic slurry composition by blending a ceramic particulate with a solvent soluble thermoplastic binder resin dissolved in a
- a. volatile organic solvent mixture forming a complete solvent for said resin and comprising a volatile first solvent fraction and a volatile second solvent fraction with
- i. said first solvent fraction constituting a complete solvent for said resin,
- ii. said second solvent fraction providing a maximum solubility of 5% for said resin therein,
- iii. the ratio of the evaporation rate of said first solvent fraction to said second solvent fraction being at least 2, and
- iv. the ratio, in parts by weight in said mixture of said first solvent fraction to said second solvent fraction being less than said evaporation rate ratio;
- and
- b. wherein said particulate comprises from about 80 to about 95 weight percent of the combined weight of said particulate and said binder resin;
- and
- c. wherein said solvent mixture is present in an amount to form a Brookfield viscosity for said slurry composition in the range of about 500 to about 2,000 cps.
- B. forming a ceramic slip by coating a layer of said composition on a removable flexible support;
- and
- C. forming a ceramic green sheet by
- a. removing a sufficient portion of said first solvent to precipitate and solidify said resin in a self-supporting structure having a portion of said second solvent fraction uniformly trapped therein;
- and
- b. removing said second solvent fraction from said resin structure to form a uniform distribution of micropores therein.
In a process for forming ceramic substrates, the steps comprising
- A. formulating a ceramic slurry composition by blending a ceramic particulate with a solvent soluble thermoplastic binder resin dissolved in a
- a. volatile organic solvent mixture forming a complete solvent for said resin and comprising a volatile first solvent fraction and a volatile second solvent fraction with
- i. said first solvent fraction constituting a complete solvent for said resin,
- ii. said second solvent fraction providing a maximum solubility of 5% for said resin therein,
- iii. the ratio of the evaporation rate of said first solvent fraction to said second solvent fraction being at least 2, and
- iv. the ratio, in parts by weight in said mixture of said first solvent fraction to said second solvent fraction being less than said evaporation rate ratio;
- and
- b. wherein said particulate comprises from about 80 to about 95 weight percent of the combined weight of said particulate and said binder resin;
- and
- c. wherein said solvent mixture is present in an amount to form a Brookfield viscosity for said slurry composition in the preferred range of about 800 to about 1,000 cps.
- B. forming a ceramic slip by coating a layer of said composition on a removable flexible support;
- and
- C. forming a ceramic green sheet by
- a. removing a sufficient portion of said first solvent to precipitate and solidify said resin in a self-supporting structure having a portion of said second solvent fraction uniformly trapped therein;
- and
- b. removing said second solvent fraction from said resin structure to form a uniform distribution of micropores therein.
Dependencies are inferred from the claim text.