International Business Machines Corporation

Clement J Fortin

Charles Leon Arvin

Christopher David Muzzy

Thomas Weiss

Thomas Anthony Wassick

Pascal P Blais

Krishna R Tunga

Brian Michael Erwin

Brian W Quinlan

Luc Gilbert Guerin

Chris Muzzy

Christian Bergeron

A method and structure for joining a semiconductor device and a laminate substrate or two laminate substrates where the joint is formed with lead free solders and lead free compositions. The various lead free solders and lead free compositions are chosen so that there is a sufficient difference in liquidus temperatures such that some components may be joined to, or removed from, the laminate substrate without disturbing other components on the laminate substrate.

Lead-free solder joining of electronic structures

Disclosed are interconnects in which one substrate having a high melting temperature, lead-free solder column is joined to a second substrate having openings filled with a low melting temperature, lead-free solder such that the high melting temperature, lead-free solder column penetrates into the low melting temperature, lead-free solder so as to obtain a short moment arm of solder.

Lead-free column interconnect

A finned contact of an IC device may be utilized to electrically connect the IC device to external circuitry. The finned contact may be fabricated by forming a base upon the IC device and subsequently forming two or more fins upon the base. Each fin may be formed of the same and/or different material(s) as the base. Each fin may include layer(s) of one or materials. The fins may be located upon the base inset from the sidewall(s) of the base. The fins may be arranged as separated ring portions that are concentric with the base. The fins may drive current into the external circuitry connected thereto. Solder may be drawn towards the center of the base within an inner void that is internal to the fins, thereby limiting the likelihood of solder bridging with a neighboring contact.

Finned contact

A reflow method for solder includes heating the solder to a first temperature that is above a liquidus temperature of the solder; cooling the solder to a second temperature that is below a solidification temperature of the solder; reheating the solder to a third temperature that is above a solidus temperature of the solder and below the liquidus temperature of the solder; cooling the solder to a fourth temperature that is below the solidification temperature of the solder.

Reflow method for lead-free solder

A method for verifying the internal microstructure of interconnects in flip-chip applications includes providing a microelectronic assembly comprising the following: a substrate hosting an array of flip-chip attach pads and one or more process control pads; a flip chip having an array of solder bumps in contact with the array of flip-chip attach pads; and one or more representative solder bumps contacting the one or more process control pads. The representative solder bumps have a substantially similar or identical chemical composition as the array of solder bumps. A reflow cycle is then applied to the microelectronic assembly to melt and solidify the array of solder bumps on the flip-chip attach pads and melt and solidify the representative solder bumps on the process control pads. The surface texture of the representative solder bumps is then optically inspected to determine an internal microstructure of the array of solder bumps.

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Clement J Fortin