International Business Machines Corporation

Kathleen Ann Stalter

Peter Jeffrey Brofman

Sudipta Kumar Ray

Shaji Farooq

Raymond A Jackson

John Ulrich Knickerbocker

Mark G Courtney

Hilton T Toy

Lewis Sigmund Goldmann

Anson Jay Call

Patrick Anthony Coico

Stephen Anthony DeLaurentis

William Edward Sablinski

Scott Ira Langenthal

Gregory Blair Martin

Sampath Purushothaman

Sung Kwon Kang

Mario John Interrante

Frank Louis Pompeo

David C Linnell

Li Ming Wang

Jeffrey Thomas Coffin

James H Covell

Shaji Faroon

Shaji Faroog

A pre-thermal reflown dielectric interposer having a plurality of vias traversing through the interposer which correspond to the I/O pads on a chip and substrate. Cone shaped solder elements reside within the vias, whereby these solder elements are cone shaped prior to thermal reflow to permit a reduced force for allowing some non-planarity for joining the chip to the substrate. The interposer may comprise a polyester film, glass, alumina, polyimide, a heat curable polymer or an inorganic powder filler in an organic material. The interposer may also have an adhesive or adhesive layers disposed on the linear surfaces thereof. The present pre-thermal reflown interposer prohibits contact between the solder joints by isolating each of the joints and corresponding bonding pads, as well as preventing over compression of the solder joints by acting as a stand off.

Dielectric interposer for chip to substrate soldering

A device for preventing short circuits between solder joints in flip chip packaging. The dielectric interposer has a plurality of apertures or vias which correspond to the I/O pads on a chip and substrate. Preferably, the interposer comprises a polyester film, glass, alumina, polyimide, a heat curable polymer or an inorganic powder filler in an organic material. More preferably, the interposer contains an adhesive or has adhesive layers disposed on the linear surfaces of the interposer. Cone shaped solder elements are formed within the apertures of the interposer. The dielectric interposer is positioned between a chip and substrate in an electronic module and thermally reflowed to create an electrical and mechanical interconnection. The interposer prohibits contact between the solder joints by isolating each of the joints and corresponding bonding pads. The interposer also prevents over compression of the solder joints by acting as a stand off.

A module or assembly is formed by interposing a polymer between a carrier and a semiconductor device to be secured to the carrier. The polymer has ionized metallic particles suspended in it. Before setting or curing the polymer, the module is exposed to an electric field which induces migration of the metallic particles to the opposing pads of the carrier and semiconductor device. Such migration ultimately forms metal dendrites extending between mating pad pairs. The dendrites establish a metallurgical bond and conductive paths between the carrier and the overlying semiconductor device. When the polymer is subsequently set, the carrier and device are not only adhered to each other, but the dendrite connections are fixed and structurally reinforced to provide the needed electrically conductive paths.

Method for assembling a carrier and a semiconductor device

A method of forming non-spherically shaped solder interconnects, preferably conical, for attachment of electronic components in an electronic module. Preferably, the solder interconnects of the present invention are cone shaped and comprise of depositing a first solder followed by a second solder having a lower reflow temperature than the first solder. Warm placement of the electronic component at a somewhat elevated temperature than room temperature but less than the solder reflow temperature reduces the force required during placement of a semiconductor chip to a substrate. After warm placement, reflow of the module occurs at the lower reflow temperature of the second solder. The conical shape of the solder interconnects are formed by a heated coining die which may also coin a portion of the interconnects with flat surfaces for stand-offs. The ability of the cone shaped solder interconnects to meet the opposing surface of a chip or substrate at different heights accommodates the camber typically associated with chip and substrate surfaces.

Process for forming cone shaped solder for chip interconnection

A method of interconnecting electronic components by using a plurality of conductive studs on a surface of a first electronic component and a plurality of corresponding conductive vias on the surface of a second electronic component. Camber on the surface of electronic components may be overcome by coating the surface with a dielectric, planarizing the dielectric, and forming conductive vias corresponding to the contact pads thereon. The conductive studs are substantially lead-free and preferably comprise of copper.

Method of interconnecting electronic components using a plurality of conductive studs

A process and apparatus for removing flip chips with C4 joints mounted on a multi-chip module by applying a tensile force to one or more removal member bonded to the back of one or more flip chips during heating of the module to a temperature sufficient to cause the C4 joints to become molten. The tensile force can either be a compressed spring, or a bi-metallic member which is flat at room temperature and becomes curved when heated to such temperature, or a memory alloy whose original shape is curved and which is bent flat at room temperature but returns to its original curved shape when heated to such temperature. An adhesive is used to bond the removal member to the chip to be removed and is a low temperature, fast curing adhesive with high temperature tolerance after curing.

Process and apparatus to remove closely spaced chips on a multi-chip module

A socketable ball grid array structure is disclosed which comprises mechanically rigid (compared to solder alloys) balls coated with noble contact metals joined to the chip carrier terminals by means of a novel electrically conducting adhesive. Because of the nature of the filler that includes conducting particles with a fusible coating and the appropriate selection of the polymer resin used in the adhesive, the balls are attached to the module in a compliant and resilient manner while leaving the majority of the bottom surface of the balls pristine. The array of balls can therefore be plugged into mating sockets in a printed circuit board forming a demountable contact. This facilitates easy removal of the socketable BGA from a board for repair or upgrade purposes as well as allows ease of plugging and unplugging of these BGA's into test and burn-in boards.

Structure, materials, and methods for socketable ball grid

A new interconnection scheme of a ball grid array (BGA) module is disclosed where a solder ball is connected to the BGA module by use of an electrically conducting adhesive The electrically conducting adhesive can be a mixture comprising a polymer resin, no-clean solder flux, a plurality of electrically conducting particles with an electrically conducting fusible coating and others. The solder balls in a BGA module can also be connected to a printed circuit board by use of another electrically conductive adhesive which can be joined at a lower temperature than the first joining to the BGA module. Additionally, an electrically conducting adhesive can be formed into electrically conducting adhesive bumps which interconnect an integrated circuit device to the BGA module.

Structure, materials, and applications of ball grid array interconnections

This invention relates to a solder structure which provides enhanced fatigue life properties when used to bond substrates particularly at the second level such as BGA and CGA interconnections. The solder structure is preferably a sphere or column and has a metal layer wettable by solder and the structure is used to make solder connections in electronic components such as joining an electronic module such as a chip connected to a MLC which module is connected to a circuit board. The solder structure preferably has an overcoat of solder on the metal layer to provide a passivation coating to the metal layer to keep it clean from oxidation and corrosion and also provide a wettable surface for attachment of the solder structure to solder on the pads of the substrate being bonded.

Method for enhancing fatigue life of ball grid arrays

A solder preform is provided for forming interconnections between multilayer ceramic substrates comprising an upper layer and lower layer of solder separated by an intermediate layer of a material which is wettable by solder and which does not melt at the temperatures used to reflow the solder and form the connections. The solder preform is used to join the substrates and is particularly useful to simultaneously electrically interconnect the substrates and to form a hermetic seal between the substrates being joined.

Solder disc connection

A compressible interposer comprising an interposer sheet having a plurality of apertures filled with a dielectric material having a substantially uniform suspension of conductive particles therein forming a plurality of conductive sites. Preferably, the number of conductive sites on the interposer are greater in number than the number of contact pads on the electronic components such that precise alignment of the interposer between the electronic components is not required. The apertures of the interposer sheet confine the conductive particles within the dielectric material such that during compression of the interposer between the electronic components, z-axis conductive pathways are formed without shorting in the x and y directions. Preferably, the interposer sheet comprises polyimide. Preferably, the dielectric material comprises polyimide-siloxane. Preferably, the conductive particles have a diameter of about 2 to about 20 &mgr;m and comprise of a material selected from the group consisting of copper, gold, silver, nickel, palladium, platinum, and alloys thereof. The particles may also be coated with an additional conductive material such as solder having a lower melting temperature. Most preferably, the conductive particles comprise solder coated copper particles. The conductive particles are present in an amount of about 30 to about 90 wt. % of the total weight of the conductive particles and the dielectric material.

Z-axis compressible polymer with fine metal matrix suspension

A semiconductor device having C-4 solder connections is joined to a chip carrier having pads suitable for receiving the C-4 solder connections. Sacrificial solder is formed on the chip carrier pads and then planarized to result in a good, planar surface profile for joining to the semiconductor device.

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Hopewell Junction, NY, United States of America

Kathleen Ann Stalter