W. R. Grace Co.-conn.

Other

John W Lau

Jack H Enloe

Roy W Rice

Jacob Block

Awdhoot V Kerkar

Christian B Lundsager

Rasto Brezny

Semyon D Friedman

Ernest W Hughes

Alan L Kovacs

Leonard E Dolhert

Michael Richard Ehlert

Craig P Cameron

Anthony J Colageo

Anastasia M Conlon

Kevin E Bennet

Ellice Y Luh

Flexible metal foil catalyst members suitable for use in catalytic devices for combustion engine emission control are prepared by electrophoretic deposition using an aqueous slurry of catalyst support particles. The deposited support layer is of uniform thickness and stable surface area. The catalyst support may then be impregnated with catalytic species and assembled into a catalytic device. The catalyst members from the invention are especially suitable for use in automotive applications, and more especially in electrically heated catalytic devices.

Metal foil catalyst members by aqueous electrophoretic deposition

The electronic packages of the invention all employ the general materials scheme of a low dielectric constant material (low K material) mounted on a dense, high thermal conductivity (high TC) ceramic base. In this way, the low K material provides the signal transmission paths to and from the I.C. chips housed in the package and thus allows for higher signal transmission speed. The high TC material allows for heat dissipation out of the package. The dense base and/or the low K material may contain metallization in any desired pattern. The low K material is preferably a composite of closed pores in a glass-containing matrix.

Electronic package using closed pore composites

Ceramics containing AlN and B.sub.4 C are produced from relatively low cost starting materials. The starting materials are combined and heated whereby they react to form AlN and B.sub.4 C. The reacted mixture can optionally be densified thereafter. The starting materials generally include aluminum metal, boron nitride and carbon.

Reaction processing of AlN/B.sub.4 C composites

A green body to be hot pressed by heating the body and applying pressure in a uniaxial direction to the body for an amount of time wherein the body has at least one non-uniform composition cross section relative to the uniaxial direction which cross section has regions which require differing amounts of shrinkage in the uniaxial direction to achieve maximum density under the pressure and heating for the amount of time, may be hot pressed according to a method including:

Replica hot pressing technique

The present invention overcomes the problems caused by certain intergranular phases present during hot pressing. The invention provides a method of removing such problematic intergranular phases while avoiding problems of non-uniformity. In one aspect, the invention encompasses an improvement in a method of sintering a green body by hot pressing, where the green body contains ceramic grains to be sintered and material capable of existing as intergranular phase material during sintering. The improvement embraces hot pressing the body in the presence of a permeable material adapted to receive at least a portion of intergranular phase material as the sintering takes place or after the sintering has been completed.

Use of permeable materials to improve hot pressing process

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

Low sodium hollow glass microspheres containing less than about 3 wt. % Na.sub.2 O are produced from aqueous precursors. The method comprises

Method for making low sodium hollow glass microspheres

Hermetic package designs for HDMI substrates are discussed. The designs for a hermetically sealed, perimeter-leaded package may have the following features:

Ceramic electronic package design

Alpha alumina platelets are used as thermally conductive, electrically insulating filler in thermally conductive, electrically insulating elastomers. The platelets provide improved thermal conductivity in comparison to conventional alumina fillers. The platelets preferably average less than one micron thickness with an average aspect ratio of at least about 5:1.

Thermally conductive elastomer containing alumina platelets

An electronic package comprising dielectric layers including a densified aluminum nitride (AlN) base layer and at least one densified AlN-borosilicate glass composite layer bonded thereto is described. Any of the dielectric layers may be metallized with conductive circuit patterns and can contain conductive vias. Production of this package is accomplished by hot pressing a greenware laminate comprising a densified base (e.g., AlN); at least one green sinterable sheet(e.g., AlN-borosilicate glass composite); and a green sheet of non-sinterable material (e.g., boron nitride [BN]. The respective green sheets comprise homogeneous mixtures of the ceramic powders and a binder, e.g., polyethylene. The polyethylene is burnt off during the hot press operation. Residual BN is removed by brushing and/or grit blasting, leaving the finished electronic package, all ceramic elements of which are densified. The package provides superior thermal conductivity, strength, dielectric properties, and silicon-compatibility.

Electronic package comprising aluminum nitride and aluminum

An electronic package comprising dielectric layers including a densified aluminum nitride (AlN) base layer and at least one densified AlN-borosilicate glass composite layer bonded thereto is described. Any of the dielectric layers may be metallized with conductive circuit patterns and can contain conductive vias. Production of this package is accomplished by hot pressing a greenware laminate comprising a densified base (e.g., AlN); at least one green sinterable sheet (e.g., AlN-borosilicate glass composite); and a green sheet of non-sinterable material (e.g., boron nitride [BN]). The respective green sheets comprise homogeneous mixtures of the ceramic powders and a binder, e.g., polyethylene. The polyethylene is burnt off during the hot press operation. Residual BN is removed by brushing and/or grit blasting, leaving the finished electronic package, all ceramic elements of which are densified. The package provides superior thermal conductivity, strength, dielectric properties, and silicon-compatibility.

Boron nitride green sheets are made of boron nitride powder in an organic binder which leaves no undesirable residue upon pyrolysis in the absence of oxygen. These boron nitride green sheets can be placed on each side of the ceramic green sheet to form a composite for hot pressing ceramic green sheets containing ceramic powder to produce dense ceramic sheets suitable for electronic substrates.

Boron nitride sheets

Dense ceramic sheets suitable for electronic substrates are prepared by hot pressing ceramic green sheets containing ceramic powder and organic binders which leave no undesirable residue upon pyrolysis in the absence of oxygen. Boron nitride sheets made of boron nitride powder in a similar binder are placed on each side of the ceramic green sheet to form a composite. After hot pressing the composite so as to remove the binder and densify the ceramic, the BN layers are removed.

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Gaithersburg, MD, United States of America

John W Lau