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.
Claims26
A thermoplastic resin composition adapted for forming ceramic slips comprising:
- (A) a solvent soluble thermoplastic organic resin dissolved in a
- (B) volatile organic solvent mixture completely miscible with said resin and comprising a first solvent fraction and a asolvent fraction, with
- (a) said first solvent fraction constituting a complete solvent for said resin,
- (b) said asolvent fraction providing a maximum solubility of 5% for said resin therein,
- (c) the ratio of the evaporation rates of said first solvent fraction to said asolvent fraction being at least two, and
- (d) the ratio, in parts by weight in said mixture, of said first solvent fraction to said asolvent fraction being less than said evaporation rate ratio.
A ceramic slip composition adapted for forming a ceramic green sheet comprising a blend of
- (A) ceramic particulate, and
- (B) a solvent soluble thermoplastic organic binder resin composition dissolved in
- (C) a volatile organic solvent mixture comprising a first solvent fraction and an asolvent fraction with
- (a) said first solvent fraction constituting a complete solvent for said resin;
- (b) said asolvent fraction providing a maximum solubility of 5% for said resin therein;
- (c) the ratio of the evaporation rates of said first solvent fraction to said asolvent fraction being at least two, and
- (d) the ratio, in parts by weight in said mixture, of said first solvent fraction to said asolvent fraction being less than said evaporation rate ratio.
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 asolvent fraction with
- (i) said first solvent fraction constituting a complete solvent for said resin,
- (ii) said asolvent 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 asolvent fraction being at least 2, and
- (iv) the ratio, in parts by weight in said mixture of said first solvent fraction to said asolvent 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 2000 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 asolvent fraction uniformly trapped therein;
- and
- (b) removing said asolvent fraction from said resin structure to form a uniform distribution of micropores therein;
- and
- (D) coating on a surface of a said green ceramic a pattern of an electric conductor forming composition;
- (E) superimposing a second said green ceramic on said surface to sandwich said pattern therebetween;
- (F) laminating said superimposed green ceramic into a support-free integrated laminate;
- and
- (G) firing said laminate into a sintered binder-free ceramic having said pattern of electrical conductors extending within the interior thereof.
In a process for forming ceramic substrates, the steps comprising:
- (A) forming a solution by solvation of a thermoplastic resin binder in a miscible single phase solvent system comprised of
- (a) a first solvent portion for said binder and
- (b) a second asolvent portion for said binder with said asolvent portion having a lower evaporation rate than said solvent portion,
- (B) uniformly dispersing ceramic particulates in said solution,
- (C) forming a film of the dispersion of Step B,
- (d) forming a green sheet by heating said film for removal of said solvent system therefrom, and
- (E) forming said green sheet into a sintered binder-free ceramic substrate.
Dependencies are inferred from the claim text.