EP0329973A1 — Hot pressing dense ceramic sheets for electronic …

Claim 1

Independent Claim 131 words

A process for producing dense ceramic sheets suitable for electronic substrates comprising the following steps: (a) preparing at least one ceramic green sheet comprising ceramic powder and organic binders which leave no undesirable residue upon pyrolysis in the absence of oxygen; (b) placing boron nitride sheets comprising boron nitride (BN) powder and organic binders which leave no undesirable residue upon pyrolysis in the absence of oxygen, on each side of the ceramic green sheet prepared in step (a) to form a composite, peferably by laminating the boron nitride sheet on each side of the ceramic green sheet; (c) hot pressing the composite prepared in step (b) under conditions necessary to facilitate binder removal and densify the ceramic; and (d) removing the BN layers on each side of the dense ceramic sheet.

Claim 2

Dependent Claim 131 words

A process for producing dense ceramic sheets suitable for electronic substrates comprising the following steps: (a) preparing at least one ceramic green sheet comprising ceramic powder and organic binders which leave no undesirable residue upon pyrolysis in the absence of oxygen; (b) placing boron nitride sheets comprising boron nitride (BN) powder and organic binders which leave no undesirable residue upon pyrolysis in the absence of oxygen, on each side of the ceramic green sheet prepared in step (a) to form a composite, peferably by laminating the boron nitride sheet on each side of the ceramic green sheet; (c) hot pressing the composite prepared in step (b) under conditions necessary to facilitate binder removal and densify the ceramic; and (d) removing the BN layers on each side of the dense ceramic sheet.

Claim 3

Dependent Claim 47 words

A process for making multiple dense ceramic sheets simultaneously according to Claim 1, wherein the boron nitride (BN) sheets are placed adjacent to the ceramic green sheets to produce a stack of the form BN-ceramic-[BN-ceramic] x -BN where x is a positive integer prior to step (c).

Claim 4

Dependent Claim 77 words

A process according to Claim 1, where the ceramic green sheet in step (a) is made by: (i) mixing ceramic powder, polyethylene and oil; and compounding the mixture at an elevated temperature to facilitate melting of the polyethylene; (ii) molding the compounded mixture in step (i) to form sheets by extrusion through a die or by pressing the compounded mixture in step (i) into flat sheets; and (iii) removing the oil by extraction with an organic solvent.

Claim 5

Dependent Claim 66 words

A process according to Claim 1, where the boron nitride sheet of step (b) is made by: (i) mixing boron nitride powder, polyethylene, and oil; and compounding the mixture at an elevated temperature to facilitate melting of the polyethylene; (ii) molding the compounded mixture in step (i) to form sheets by extrusion through a die; and (iii) removing the oil by extrusion with an organic solvent.

Claim 6

Dependent Claim 15 words

A process according to Claim 1, where the ceramic powder is primarily AlN or Al₂O₃.

Claim 7

Dependent Claim 138 words

A process for producing dense ceramic electronic substrates having dense conductive metal circuit pattern(s) on the surface(s) comprised of the following steps: (a) preparing ceramic green sheets comprising ceramic powder and organic binders which leave no undesirable residue upon pyrolysis in the absence of oxygen; (b) depositing the desired metal circuit pattern(s) to the ceramic sheets with a suitable metal which is compatible with the ceramic, preferably by screen printing a metal paste; (c) placing boron nitride green sheets on each side of the ceramic sheet having metal circuit pattern(s) in step (b), preferably by laminating the boron nitride sheet on each side of the composite; (d) hot pressing the metallized sheets under conditions necessary to densify both the ceramic and the metal powders; and (e) removing the BN layers from the sides of the dense ceramic sheet.

Claim 8

Dependent Claim 138 words

A process for producing dense ceramic electronic substrates having dense conductive metal circuit pattern(s) on the surface(s) comprised of the following steps: (a) preparing ceramic green sheets comprising ceramic powder and organic binders which leave no undesirable residue upon pyrolysis in the absence of oxygen; (b) depositing the desired metal circuit pattern(s) to the ceramic sheets with a suitable metal which is compatible with the ceramic, preferably by screen printing a metal paste; (c) placing boron nitride green sheets on each side of the ceramic sheet having metal circuit pattern(s) in step (b), preferably by laminating the boron nitride sheet on each side of the composite; (d) hot pressing the metallized sheets under conditions necessary to densify both the ceramic and the metal powders; and (e) removing the BN layers from the sides of the dense ceramic sheet.

Claim 9

Dependent Claim 49 words

A process for making multiple metallized dense ceramic layers simultaneously according to Claim 11, where prior to step (d) the boron nitride sheets are placed adjacent to the metallized ceramic sheets to produce a stack of the form BN-metallized ceramic-[BN-metallized ceramic-] x -BN where x is a positive integer.

Claim 10

Dependent Claim 20 words

A process according to Claim 6, where the ceramic powder is primarily AlN or Al₂O₃ and the metal is W.

Claim 11

Dependent Claim 65 words

A process according to Claim 6, wherein the ceramic green sheet in step (a) is made by: (i) mixing ceramic powder, polyethylene and oil; and compounding the mixture at an elevated temperature to facilitate melting of the polyethylene; (ii) molding the compounded mixture in step (i) to form sheets by extrusion through a die; and (iii) removing the oil by extraction with an organic solvent.

Claim 12

Dependent Claim 184 words

A process for producing multilayer ceramic electronic substrates with internal interconnected metal circuits at the various layers comprising the following steps: (a) preparing ceramic green sheets comprising ceramic powder and organic binders which leave no undesirable residue upon pyrolysis in the absence of oxygen; (b) producing metal-filled vias in the ceramic sheet(s) of step (a) by punching holes in the ceramic sheets and filling with metal powders; (c) depositing the desired metal circuit patterns to the ceramic sheets of step (b); (d) laminating the desired number of ceramic sheets of step (c) together in a manner which maintains registration of the metallized patterns and vias on the various layers to form a green multilayer ceramic-metal composite; (e) placing boron nitride sheets on each side of the composite of step (d), preferably by laminating the boron nitride sheet on each side of the ceramic green sheet; (f) hot pressing the BN-composite-BN product of step (e) under conditions necessary to facilitate binder removal and densify both the ceramic and the metal powders; and (g) removing the BN layers on each side of the dense ceramic sheet.

Claim 13

Dependent Claim 184 words

A process for producing multilayer ceramic electronic substrates with internal interconnected metal circuits at the various layers comprising the following steps: (a) preparing ceramic green sheets comprising ceramic powder and organic binders which leave no undesirable residue upon pyrolysis in the absence of oxygen; (b) producing metal-filled vias in the ceramic sheet(s) of step (a) by punching holes in the ceramic sheets and filling with metal powders; (c) depositing the desired metal circuit patterns to the ceramic sheets of step (b); (d) laminating the desired number of ceramic sheets of step (c) together in a manner which maintains registration of the metallized patterns and vias on the various layers to form a green multilayer ceramic-metal composite; (e) placing boron nitride sheets on each side of the composite of step (d), preferably by laminating the boron nitride sheet on each side of the ceramic green sheet; (f) hot pressing the BN-composite-BN product of step (e) under conditions necessary to facilitate binder removal and densify both the ceramic and the metal powders; and (g) removing the BN layers on each side of the dense ceramic sheet.

Claim 14

Dependent Claim 65 words

A process according to Claim 10, wherein the ceramic green sheet in step (a) is made by: (i) mixing ceramic powder, polyethylene and oil; and compounding the mixture at an elevated temperature to facilitate melting of the polyethylene; (ii) molding the compounded mixture in step (i) to form sheets by extrusion through a die; and (iii) removing the oil by extraction with an organic solvent.

Claim 15

Dependent Claim 51 words

A process for producing a multiple of multilayer ceramic substrates simultaneously according to Claim 10, where prior to step (f) the boron nitride sheets are placed adjacent to the multilayer ceramic-metal composites of step (d) to produce a stack of the form BN-composite-[BN-composite] x -BN where x is a positive integer.

Claim 16

Dependent Claim 19 words

A process according to Claim 10, where the ceramic powder is AlN or Al₂O₃ and the metal is W.

Claim 17

Dependent Claim 92 words

A process for producing multilayer ceramic electronic substrates according to claim 10, where step (b) is replaced by the following: (i) preparing a metal powder containing sheet comprising metal powders and organic binders which leave no undesirable residue upon pyrolysis in the absence of oxygen; and (ii) punching a hole(s) in the ceramic green sheets of step (a), followed by placing the metal powder containing sheet of step (i) against the ceramic green sheets and forcing the metal containing material into the hole(s) in the ceramic green sheets by a punching action.

Claim 18

Dependent Claim 68 words

A process for producing multilayer ceramic electronic substrates according to Claim 10, where surface cavities are produced in the substrates by: (i) punching hole(s) in the ceramic sheets of step (a) which will reside on the surface of the composite of step (d); and (ii) filling the holes in step (i) with BN tape material of similar thickness prior to the lamination of the layers in step (d).

Hot pressing dense ceramic sheets for electronic substrates and for multilayer ceramic electronic substrates

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