International Business Machines Corporation

Guy Paul Brouillette

Peter Alfred Gruber

David Hirsch Danovitch

Carlos Juan Sambucetti

Daniel George Berger

Michael Liehr

William Thomas Motsiff

James L Speidell

Rajesh S Patel

Frederic Maurer

Stephen Roux

Bruce Lee Humphrey

Ravi F Saraf

Judith Marie Roldan

Lannie R Bolde

Chon Cheong Lei

James H Covell

Jean-Luc Landreville

Guy D Beaumont

Eric E Bourchard

Jean-Paul Henry

An apparatus for the removal of excess solder or contaminant, which are encountered on the surfaces of injection mold prior to the transfer of a solder on a silicon wafer. More particularly, there is provided an apparatus for the removal of excess solder, which may be present on a mold surface, without removing any solder, which is located in cavities formed in the mold, and wherein the solder is applied through an injection molded soldering process.

Mold shave apparatus and injection molded soldering process

The present invention relates to improvements in forming and transferring solder bumps for use in mounting integrated circuit substrates on chip carrier packages. A mold having cavities for the solder bumps is held in contact with a substrate and a compressible device. As the temperature is increased to melt the solder in the cavities, at an appropriate time and temperature, the compressible device is caused to decompress resulting in the mold separating from the substrate and leaving formed solder bumps on the contacts on the substrate. Various mechanisms are described to cause the force holding the mold and substrate together to decrease.

Method and apparatus for transferring solder bumps

A method for direct chip attach of a semiconductor chip to a circuit board by using solder bumps and an underfill layer is disclosed. In the method, a layer of in-situ polymeric mold material is first screen printed on the top surface of the semiconductor chip exposing a multiplicity of bond pads. The in-situ polymeric mold layer is formed with a multiplicity of apertures which are then filled with solder material in a molten solder screening process to form solder bumps. A thin flux-containing underfill material layer is then placed on top of a circuit board over a plurality of conductive pads which are arranged in a mirror image to the bond pads on the semiconductor chip. The semiconductor chip and the circuit board are then pressed together with the underfill layer inbetween and heated to a reflow temperature of higher than the melting temperature of the solder material until electrical communication is established between the bond pads and the conductive pads. In the bonded assembly, the in-situ polymeric mold layer and the underfill material layer forms a composite underfill to replace a conventional underfill material that must be injected between bonded chip and substrate by a capillary action in a time consuming process.

Method for direct chip attach by solder bumps and an underfill layer

The present invention discloses a method and apparatus for forming solder bumps by a molten solder screening technique in which a flexible die head constructed of a metal sheet is utilized for maintaining an intimate contact between the die head and a solder receiving mold surface. The flexible die head, when used in combination with a pressure means, is capable of conforming to any curved mold surface as long as the curvature is not more than 2.5 &mgr;m per inch of die length.

Method and apparatus for forming solder bumps

The present invention discloses a method and apparatus for forming solder bumps by a molten solder screening technique in which a flexible die head constructed of a metal sheet is utilized for maintaining an intimate contact between the die head and a solder receiving mold surface, The flexible die head, when used in combination with a pressure means, is capable of conforming to any curved mold surface as long as the curvature is not more than 2.5 &mgr;m per inch of die length. The present invention further provides a method and apparatus for filling a multiplicity of cavities in a mold surface by providing a stream of molten solder and then intimately contacting the surface of the molten solder with a multiplicity of cavities such that the molten solder readily fills the cavities. The apparatus further provides means for removing excess molten solder from the surface of the mold without disturbing the molten solder already filled in the cavities. The present invention further discloses a flexible die for dispensing molten solder consisting of a die body that is constructed of a metal sheet capable of flexing of not less than 1.5 &mgr;m per inch of die length, a gate opening for receiving a supply of molten solder, a slot opening for dispensing the molten solder onto a solder receiving surface, and a pressure means associated with the die body for providing adequate pressure such that the die body intimately contacting the solder receiving mold surface.

A method of forming interconnects on an electronic device that can be bonded to another electronic device at a low processing temperature can be carried out by depositing a first interconnect material on the electronic device forming protrusions and then depositing a second interconnect material to at least partially cover the protrusions, wherein the second interconnect material has a lower flow temperature than the first interconnect material. The method is carried out by flowing a molten solder into a mold having microcavities to fill the cavities and then allowed to solidify. The mold is then aligned with a silicon wafer containing chips deposited with high melting temperatures solder bumps such that each microcavity of the mold is aligned with each high melting temperature solder bump on the chip. The aligned mold/wafer assembly is then passed through a reflow furnace to effect the transfer of the low melting temperature solder in the mold cavities onto the tip of the high melting temperature solder bumps on the wafer. A dual metallurgical composition bump is thereby formed by the two different solder alloys.

Method for making interconnect for low temperature chip attachment

A method for joining a multiplicity of multi-alloy solder columns to an electronic substrate and the structure formed by such method are disclosed. In the method, a mold plate equipped with a multiplicity of cavities is first filled by an injection molded solder technique with a high temperature solder forming a multiplicity of solder columns. The mold plate is then sandwiched between an extraction plate and a transfer plate by utilizing a multiplicity of displacement means equipped in the extraction plate to displace the multiplicity of solder columns from the mold plate into a multiplicity of apertures equipped in the transfer plate. The multiplicity of cavities in the transfer plate each has a straight opening and a flared opening. The flared opening is then filled with a low temperature solder paste to encapsulate one end of the high temperature solder column. The low temperature solder paste is then reflown on top of a conductive pad on an electronic substrate at a temperature lower than the melting temperature of the high temperature solder to form a bond between the solder column and the conductive pad.

Low temperature solder column attach by injection molded solder and structure formed

A method for forming solder bumps on an electronic structure including the steps of first providing a mold made by a sheet of a mold material having a thickness greater than that of the solder bumps to be formed, the mold material has sufficient optical transparency so as to allow the inspection of a solder material subsequently filled into the mold cavities that are formed in the mold material, and a coefficient of thermal expansion that is substantially similar to the substrate which the mold will be mated to, forming a multiplicity of mold cavities in the sheet of mold material, filling the multiplicity of mold cavities with a solder material, cooling the mold to a temperature that is sufficient to solidify the solder material in the multiplicity of mold cavities, positioning the mold intimately with the electronic structure such that the cavities facing the structure, and heating the mold and the structure together to a temperature sufficiently high such that the solder material transfers onto the electronic structure.

Method for building interconnect structures by injection molded solder

Interconnect for low temperature chip attachment

The present invention discloses a method and apparatus for forming solder bumps by a molten solder screening technique in which a flexible die head constructed of a metal sheet is utilized for maintaining an intimate contact between the die head and a solder receiving mold surface. The flexible die head, when used in combination with a pressure means, is capable of conforming to any curved mold surface as long as the curvature is not more than 2.5 .mu.m per inch of die length. The present invention further provides a method and apparatus for filling a multiplicity of cavities in a mold surface by providing a stream of molten solder and then intimately contacting the surface of the molten solder with a multiplicity of cavities such that the molten solder readily fills the cavities. The apparatus further provides means for removing excess molten solder from the surface of the mold without disturbing the molten solder already filled in the cavities. The present invention further discloses a flexible die for dispensing molten solder consisting of a die body that is constructed of a metal sheet capable of flexing of not less than 1.5 .mu.m per inch of die length, a gate opening for receiving a supply of molten solder, a slot opening for dispensing the molten solder onto a solder receiving surface, and a pressure means associated with the die body for providing adequate pressure such that the die body intimately contacting the solder receiving mold surface.

An apparatus and a method for transferring solder bumps from a solder mold to a solder-receiving substrate are disclosed. The apparatus includes a transfer fixture constructed by a base member, a lid member and a compressible member for holding a mold/substrate assembly therein. A plurality of compression pins are mounted through the lid member for supplying a uniform pressure on the mold/substrate assembly and for allowing lateral motion of the mold/substrate assembly relative to the transfer fixture due to a mismatch in the coefficients of thermal expansion. The compressible member is a cellulosic foam sheet which applies a uniform joining force across the entire surface of a wafer and assures abutting contact between the entire wafer and the mold surface. The foam sheet further assists in the lateral movement of the mold/substrate assembly relative to the base member of the transfer fixture.

Apparatus for transferring solder bumps and method of using

An interconnect system that has low alpha particle emission characteristics for use in an electronic device includes a semiconductor chip that has an upper surface and spaced apart electrically resistive bumps positioned on conductive regions of the upper surface, the electrically resistive bumps are made of a composite material of a polymer and metal particles, and a substrate that has conductive regions bonded to the electrically resistive bumps in a bonding process wherein the electrically resistive bumps convert to electrically conductive bumps after the bonding process.

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CA

Guy Paul Brouillette