Motorola Corporation

Kenneth Cholewczynski

Kevin Douglas Moore

Cynthia M Melton

Carl J Raleigh

John W Stafford

Dennis Brian Miller

Steven C Machuga

An integrated circuit component is attached to a printed circuit board by solder bump interconnections that are formed between metal bumps on the component and a metal-plated terminal on the board. The metal plate overlies both a bond pad and an adjacent runner of each terminal and is formed of a first metal, which is preferably a tin-base alloy. The metal bumps on the component are formed of a second metal, which is preferably an indium-base alloy. The component and board are assembled and heated to a temperature less than the melting temperatures of the first and second metals. At the interface between the bumps and the plate, the first and second metals cooperate to form a liquid phase which, upon cooling and solidifying, completes the interconnection.

Low temperature method for forming solder bump interconnections to a

A method for attaching an integrated circuit component to a printed circuit board by a plurality of solder bump interconnections utilizes a printed circuit board comprising a solder-plated circuit trace. The trace includes terminals, each including a terminal pad and a runner section. A solder plate formed of a first solder alloy is applied to the terminal to extend continuously between the pad and the runner section. Solder bumps are affixed to the component and are formed of second compositionally distinct solder alloy having a melting temperature greater than the first alloy. The component and board are then assembled so that the bumps rest against the solder-plated terminal pads, and heated to a temperature effective to melt the solder plate but not the bump alloy. Upon cooling to resolidify the solder, the solder plate is fused to the bumps to form the interconnections.

Method for forming solder bump interconnections to a solder-plated

An improved method is provided for assembling an integrated circuit component to a substrate by a solder bump interconnection that is reinforced by a polymer film. The component is attached to a region of the substrate by a plurality of solder bump interconnections that create a gap between the component interface and the substrate region. A polymer dam is applied to the region encircling the attached component spaced apart therefrom. A liquid polymer precursor material is applied to the region including the gap and is confined by the dam to prevent indiscriminate flow across the substrate. In one aspect of this invention, gas is vented from the gap through a passage in the substrate to enhance fill by the precursor liquid. In another aspect of this invention, the precursor liquid is injected into the gap through a passage in the substrate and spread outwardly therefrom. In any event, the precursor liquid infiltrates the gap about the solder interconnections and is cured to form a film that reinforces and protectively encapsulates the solder interconnections.

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Streamwood, IL, United States of America

Kenneth Cholewczynski