The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 19, 2004
Filed:
Feb. 15, 2002
Won K. Choi, Mount Kisco, NY (US);
Charles C. Goldsmith, Poughkeepsie, NY (US);
Timothy A. Gosselin, Apalachin, NY (US);
Donald W. Henderson, Ithaca, NY (US);
Sung K. Kang, Chappaqua, NY (US);
Karl J. Puttlitz, Sr., Wappingers Falls, NY (US);
Da-Yuan Shih, Poughkeepsie, NY (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
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%.