International Business Machines Corporation

Michael Liehr

Carlos Juan Sambucetti

David Hirsch Danovitch

Guy Paul Brouillette

Peter Alfred Gruber

William Thomas Motsiff

Daniel George Berger

Bruce Lee Humphrey

Stephen McConnell Gates

Ravi F Saraf

Judith Marie Roldan

Gary W Rubloff

Michel G Renier

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

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

Interconnect for low temperature chip attachment

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.

Direct chip attach for low alpha emission interconnect system

An improved motive structure for transporting workpieces (wafers, chip, packages, etc.) between processing stations or tools in a manufacturing operation. The structure includes a first circular crankshaft assembly connected to center axles disposed at right angles to the transport motion. A second such crankshaft assembly is located some distance along the path of motion. Three driverods are connected between the first and second crankshaft assemblies, each affixed 120.degree. apart on the circular crankshafts so that each driverod is moved upward, then forward along the transport direction, then downward and backward to its original position as the crankshafts go through a complete 360.degree. rotation. The structure is disposed beneath transport rails which hold movable containers for holding the workpieces. As a driverod moves up and forward, it contacts a spring-loaded element on the movable container and drives it forward by friction contact. As each driverod begins to move down and away from the workpiece container, the next driverod is being rotated up and forward to continue to move the container along the rails. Pluralities of such structures are linearly arranged to provide an extended transport system.

Motive structure for transporting workpieces

Growing community of inventors

Essex Junction, VT, United States of America

Michael Liehr