International Business Machines Corporation

Invensas LLC

Timothy A Gosselin

Donald I Mead

Michael A Gaynes

Da-Yuan Shih

Sung Kwon Kang

Kang-Wook Lee

Donald W Henderson

Karl J Puttlitz, Sr

Eric Duchesne

Valerie A Oberson

Charles C Goldsmith

Won K Choi

Sung K Kang

The present invention is directed to soldering techniques and compositions for use therein. In one aspect, a flux composition is provided. The flux composition comprises a fluxing agent comprising organic acid, an organic tacking agent and an organic wetting agent. In another aspect, a soldering method for joining objects is provided comprising the following steps. A flux composition and a solder compound are applied to at least a portion of one or more of the objects. The flux composition comprises a fluxing agent comprising organic acid, an organic tacking agent and an organic wetting agent. The objects are then joined.

Flux composition and techniques for use thereof

A circuitized substrate and a method of making the circuitized substrate are provided. The circuitized substrate includes a substrate having a conductive pad thereon. A first layer of solder enhancing material is positioned on the conductive pad, the first layer of solder enhancing material includes a first region and a second region positioned relative to the first region. A solder member is positioned on the first region of the first layer of solder enhancing material. A second layer of solder enhancing material is positioned on the solder member and on a portion of the second region of the first layer of solder enhancing material. The circuitized substrate may be used in the fabrication of an electronic package.

Method of making a circuitized substrate

A circuitized substrate and a method of making the circuitized substrate is provided. The circuitized substrate includes a substrate having a conductive pad thereon. A first layer of solder enhancing material is positioned on the conductive pad, the first layer of solder enhancing material includes a first region and a second region positioned relative to the first region. A solder member is positioned on the first region of the first layer of solder enhancing material. A second layer of solder enhancing material is positioned on the solder member and on a portion of the second region of the first layer of solder enhancing material. The circuitized substrate may be used in the fabrication of an electronic package.

Method of making a circuitized substrate and the resultant circuitized substrate

A solder composition and associated method of formation. The solder composition comprises a substantially lead-free alloy that includes tin (Sn), silver (Ag), and copper. The tin has a weight percent concentration in the alloy of at least about 90%. The silver has a weight percent concentration X in the alloy. X is sufficiently small that formation of Ag Sn plates is substantially suppressed when the alloy in a liquefied state is being solidified by being cooled to a lower temperature at which the solid Sn phase is nucleated. This lower temperature corresponds to an undercooling &dgr;T relative to the eutectic melting temperature of the alloy. Alternatively, X may be about 4.0% or less, wherein the liquefied alloy is cooled at a cooling rate that is high enough to substantially suppress Ag Sn plate formation in the alloy. The copper has a weight percent concentration in the alloy not exceeding about 1.5%.

Lead-free tin-silver-copper alloy solder composition

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Apalachin, NY, United States of America

Timothy A Gosselin