W. R. Grace Co.-conn.

Leonard E Dolhert

Jack H Enloe

Jacob Block

Roy W Rice

John W Lau

Nicholas D Spencer

James Daniel Idol, Jr

Ellice Y Luh

Green ceramic formulations comprising an atactic polypropylene-containing binder are suitable for tape casting and can be effectively removed during thermal processing in reducing atmospheres. The binder may be removed in substantially dry reducing atmosphere. The tapes may be used for forming ceramic substrates and metallized ceramics such as those used in electronic packaging.

Clean burning green ceramic tape cast system using atactic polypropylene

Superconductors having a composition Bi.sub.2-a-b-c Sn.sub.a Pb.sub.b Sb.sub.c Sr.sub.2 Ca.sub.n-1 Cu.sub.n O.sub.2n+4 can be made by firing the appropriate mixtures of designated oxides or carbonates. In the composition a=about 0.001-0.4, b about 0-0.4, c about 0-0.4, and n 2 or 3. The addition of Sn improves the superconductive properties of comparable compositions that lack Sn. For example, Bi.sub.1.6 Sn.sub.0.4 Sr.sub.2 Ca.sub.2 Cu.sub.3 O.sub.x (x=ca 10), calcined at 830.degree. C. for 15 hours shows superconductivity by magnetic susceptibility tests at about 77.degree. K. whereas Bi.sub.2 Sr.sub.2 Ca.sub.2 Cu.sub.3 O.sub.10 prepared under the same conditions but lacking Sn, shows nothing at this temperature.

Tin-containing ceramic composition

Green ceramic formulations comprising a polyisobutylene binder are suitable for tape casting and can be effectively removed during thermal processing in reducing atmospheres. The binder may be removed in substantially dry reducing atmosphere. The tapes may be used for forming ceramic substrates and metallized ceramics such as those used in electronic packaging.

Clean burning green ceramic tape cast system using polyisobutylene binder

Metallization formulations containing a mixture of AlN and metal are used to form hermetic vias in AlN dielectric bases for electronic packaging. The metal may be W, Mo, or mixtures thereof. The metallization may be cofired with the AlN dielectric base. The metallization is especially useful for making electrically conductive hermetic through-vias in AlN bases.

Via metallization for AlN ceramic electronic package

The processes of the invention involve the formation of an initial reactant mixture by combining sources of SiO.sub.2, B.sub.2 O.sub.3, aluminum, and carbon. The mixture may then optionally be shaped or compacted. The reactant mixture is then heated to start a reaction which is described by the formula:

Al.sub.2 O.sub.3 /B.sub.4 C/SiC composite

Improved process for making Tl-Ca-Ba-CuO superconductors. A solution of the monocarboxylates (e.g., acetates) of Ca, Ba, and Cu is dried, calcined, mixed with Tl.sub.2 O.sub.3, and the mixture is heated to make a superconductor. The method minimizes introduction of contaminants. Novel compositions result.

Powder containing thallium, calcium, barium and copper

Improved process for making Tl-Ca-Ba-Cu oxide superconductors. A solution of the nitrated of Ca, Ba, and Cu is reacted with a quaternary ammonium carbonate in a slurry (heel) of Tl.sub.2 O.sub.3. Carbonates of Ca, Ba, and Cu precipitate homogeneously on the Tl.sub.2 O.sub.3 particles. Solids are recovered, dried, and heated to make a superconductor. The method minimizes introdution of contaminants. Novel compositions result.

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Clarksville, MD, United States of America

Leonard E Dolhert