International Business Machines Corporation

Paul H Palmateer

Raj N Master

Norman G Ainslie

Da-Yuan Shih

Srinivasa S Reddy

Philip L Flaitz

Sampath Purushothaman

Chandrasekhar Narayan

Mario John Interrante

Sarah Huffsmith Knickerbocker

Birendra N Agarwala

Paul A Totta

John Acocella

Joseph M Harvilchuck

Warren D Grobman

Timothy W Carr

Derry J Dubetsky

Walter F Lange

Carl P Hayunga

David W Boss

Marvin S Pittler

James E Krzanowski

William J King, Jr

John F Sullivan

George M Greenstein

Robert H Massey

John A Romano

Amanda H Kumar

A method of forming an adherent layer of metallurgy on a ceramic substrate which includes the steps of obtaining a ceramic material containing a polymeric binder and copper metallurgy patterns within the ceramic body. In one embodiment of the invention, the ceramic body also contains MgO. Thereafter, a surface layer of metallurgy is formed on the surface of the ceramic body. In one embodiment, the surface layer is nickel and in another embodiment, the surface layer is copper or gold. Then, the ceramic body undergoes a sintering cycle which includes the steps of pyrolysis, binder burnoff and, lastly, densification and, in some cases, crystallization. During densification and crystallization, there is a predetermined steam atmosphere which meets the following requirements: a partial pressure of oxygen less than that necessary to satisfy the equilibrium equation 4Cu+O.sub.2 =2Cu.sub.2 O; and a partial pressure of oxygen less than or equal to that necessary to satisfy the equilibrium equation 2Ni+O.sub.2 =2NiO for nickel in said surface metallurgy.

Method of forming an adherent layer of metallurgy on a ceramic substrate

The present invention teaches a structure for reducing the stresses created on a substrate and on the bonding surface at which a connector is attached. The connector has a tapered or beveled head thereby tapering the stress away from the edges of the bonding surface and therefore away from the high stress areas of the substrate, preventing cracking and delamination problems that might otherwise result. The tapered-head geometry also allows greater flexibility in manufacturing the connectors particularly when fabricating pins using a cold-heading process in that a quarter shank diameter:pin head diameter ratio can be obtained.

Use of tapered head pin design to improve the stress distribution in the

Sealing and stress relief are provided to a low-fracture strength glass-ceramic substrate. Hermeticity is addressed through the use of capture pads in alignment with vias and through polymer overlays with interconnection between the underlying via or pad metallurgy and the device, chip, wire or pin bonded to the surface of the layer. Multilevel structures are taught along with a self-aligned sealing and wiring process.

Sealing and stress relief layers and use thereof

In the process of braze attachment of electronic package members, such as attaching metallic coated connector pins to a multilayer ceramic substrate, contact areas of the substrate are formed by sequential coatings of molybdenum and nickel, which are heated to diffuse the nickel. A pure gold paste is applied by screen printing, for example, followed by the step of firing to burn out the paste binder and to sinter the pure gold particles onto a dense low porosity structure. The sintering operation converts the Ni film into a continuous Au-Ni solid solution. During pin braze, Ni-Sn intermetallics are dispersed in a gold rich matrix of the Au-Ni solid solution.

Process for braze attachment of electronic package members

The bonding of nickel, cobalt, copper or any number of metals to oxide ceramics is achieved whereby the substrate and associated metallurgy are co-sintered. The invention teaches the use of an intermediary oxide such as Al2O3, Cr2O3, TiO2 or ZrO2 which will adhere to the substrate and in the presence of firing ambients form a complex ternary oxide with the overlying metal thereby creating the desired bond. The eutectic can be created during the firing cycle without the undesired consequence of oxidizing the metal. The so-called intermediary oxides can be oxidized in situ, deposited as oxides, or introduced into either the ceramic composition or the metal paste.

Bonding of pure metal films to ceramics

Brazing of elements to electronic chip carrying substrates requires brazing materials strong at high temperatures used to remove and replace chips. Flanges and pins are brazed with Au:Sn brazing alloys modified during brazing by addition of copper to the brazing material to promote formation of the higher melting point .beta. phase of the alloy and a Group VIII metal to draw Sn out of the melt by gettering, also to promote formation of the .beta. phase of the alloy and to thicken the braze material. A copper preform is plated with Ni and juxtaposed with surfaces to be brazed and the brazing material to add Ni and copper to the melt.

High melting point copper-gold-tin brazing alloy for chip carriers

Brazing of elements to electronic chip carrying substrates requires brazing materials strong at high temperatures used to remove and replace chips. Flanges and pins are brazed with Au:Sn brazing alloys modified during brazing by addition of Group IB metal to the brazing material to promote formation of the higher melting point .beta. phase of the alloy and a Group VIII metal to draw Sn out of the melt by gettering, also to promote formation of the .beta. phase of the alloy and to thicken the braze material. An Au preform is plated with Ni and juxtaposed with surfaces to be brazed and the brazing materials to add Ni and Au to the melt almost simultaneously.

High melting point process for Au:Sn:80:20 brazing alloy for chip

Growing community of inventors

Wappingers Falls, NY, United States of America

Paul H Palmateer