International Business Machines Corporation

Alan J Emerick

Jerzy Maria Zalesinski

Michael A Gaynes

Charles Gerard Woychik

Viswanadham Puligandla

James M Larnerd

Thomas L Miller

David W Sissenstein, Jr

John P Simpson

Gary L Newman

Russell E Darrow

Mukund Kantilal Saraiya

John D Larnerd

James Richard Murray

Mark Alan Brown

Peter J Elmgren

Eugene L Marsh

Joseph A Apap

Dennis L Rivenburg, Sr

Chip stacks with decreased conductor length and improved noise immunity are formed by laser drilling of individual chips, such as memory chips, preferably near but within the periphery thereof, and forming conductors therethrough, preferably by metallization or filling with conductive paste which may be stabilized by transient liquid phase (TLP) processes and preferably with or during metallization of conductive pads, possibly including connector patterns on both sides of at least some of the chips in the stack. At least some of the chips in the stack then have electrical and mechanical connections made therebetween, preferably with electroplated solder preforms consistent with TLP processes. The connections may be contained by a layer of resilient material surrounding the connections and which may be formed in-situ. High density circuit packages thus obtained may be mounted on a carrier by surface mount techniques or separable connectors such as a plug and socket arrangement. The carrier may be of the same material as the chip stacks to match coefficients of thermal expansion. High-density circuit packages may also be in the form of removable memory modules in generally planar or prism shaped form similar to a pen or as a thermal conduction module.

High density integrated circuit packaging with chip stacking and via interconnections

High density integrated circuit packaging with chip stacking and via

An electronic circuit package is fabricated by providing a substrate having attached to at least one of its major surfaces, at least one integrated circuit chip; and providing a carrier that comprises a polymeric composition. The carrier holds a desired array of conductive pins, which protrude from both major surfaces of the carrier. The substrate is placed in contact with the pins to provide a subassembly.

Process for fabricating an electronic circuit package

An improved method and apparatus for making solder connections from input/output connecting pins to the circuitry on a pinned metallized ceramic substrate. A solder preform in the shape of a sphere provides the correct volume of solder. These spheres are held in position at each desired joint by a templet. The substrate, solder sphere and templet assembly is passed through a furnace in a reducing atmosphere and at a temperature to facilitate solder reflow and wetting, thus creating a sound mechanical and electrical connection between the pin and its portion of the circuitry. The method and apparatus of the invention provides joints have a high degree of reliability such that all connections are made to acceptable soldering standards, none lacking integrity. Only harmless by-products are produced in the practice of the invention, and no residue is produced which requires cleaning by means of chemical solvents and therefore is environmentally superior.

Substrate soldering in a reducing atmosphere

A method for affixing pins to a ceramic substrate substantially eliminating cracking of the substrate by pre-bulging the pin blanks and, then after inserting the pin blanks into the substrate, a clearance is provided between the lower pin holding die and the lower face of the substrate for the subsequent head forming operation on the opposite face of the substrate.

Affixing pluggable pins to a ceramic substrate

A solder paste for use in a reducing atmosphere is disclosed. The solder paste includes a solder powder and an alcohol binder. The reducing atmosphere serves as a flux, thereby eliminating flux residues and the problems associated therewith. Solder splattering is reduced by using a polyhydric alcoholic binder which vaporizes or decomposes before the solder liquifies during heating. The use of such a solder paste in a reducing atmosphere results in no hazardous chemical by-products and, because the solder is handled in the form of a paste, is compatible with electrical components requiring precise dimensional tolerances.

Solder paste for use in a reducing atmosphere

A method and apparatus for producing flush solder fill over recessed pins and over passage holes in circuitized substrates. A substrate carrying rack is immersed in a vessel of molten solder after it has been similarly immersed in a flux bath. While in the molten solder, the rack is vigorously agitated. The rack is then withdrawn from the molten solder and is pivoted upwardly while positioned over the molten solder. Simultaneously, an anvil is rotated from a home position to an impact position at precisely the correct moment. With the solder still molten on the substrate surfaces, the rack is then permitted to descend and is positively biased to strike the anvil thereby dislodging any excess molten solder. A unique supporting arrangement for the rack insures that only a minimum of mass acutally impacts against the anvil while insuring the effectiveness of the operation. Each cantilevered arm from which a rack is suspended is temporarily supported during the impacting operation after which the support member is withdrawn. Also, a solder pot of unique design and operation is provided to assure rapid, complete heating of substrates while eliminating contamination thereof by dross and oxides.

Solder leveling method and apparatus

A method and apparatus for producing flush solder fill over recessed pins and over passage holes in circuitized substrates. A substrate carrying rack is immersed in a vessel of molten solder after it has been similarly immersed in a flux bath. While in the molten solder, the rack is vigorously agitated. The rack is then withdrawn from the molten solder and is pivoted upwardly while positioned over the molten solder. Simultaneously, an anvil is rotated from a home position to an impact position at precisely the correct moment. With the solder still molten on the substrate surfaces, the rack is then permitted to descend and is positively biased to strike the anvil thereby dislodging any excess molten solder. A unique supporting arrangement for the rack insures that only a minimum of mass actually impacts against the anvil while insuring the effectiveness of the operation. Each cantilevered arm from which a rack is suspended is temporarily supported during the impacting operation after which the support member is withdrawn. Also, a solder pot of unique design and operation is provided to assure rapid, complete heating of substrates while eliminating contamination thereof by dross and oxides.

A method of solder leveling in printed circuit boards or other circuitized substrates. Flux is first applied to the surface of the substrate to be soldered. Molten solder is then applied to the fluxed surface after which the soldered substrate is cooled to a temperature below 300.degree. F. Molten solder is then again applied to the previously soldered surface of the substrate. This last step results in leveling the solder first applied to the substrate, including removal of any solder balls which had been formed over recessed pins and flush filling of passage holes formed in the substrate. The method can be performed without regard to the surface condition of the substrate, the composition of flux and solder, whether the substrate is of the thin film type or of the thick film type, nor whether dip soldering or wave soldering techniques are used. The invention also incompasses the end product resulting from use of the method.

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Warren Center, PA, United States of America

Alan J Emerick