Patent ID: 6805974
Filing Date: 2004-10-19
Classification: B23K,C22C,H01L,H05K,Y10T

Abstract:
A solder composition, comprising a solder alloy,wherein the alloy is substantially free of lead, wherein the alloy includes tin (Sn), silver (Ag), and copper (Cu), and bismuth (Bi), wherein the tin has a weight percent concentration in the alloy of at least about 90%, wherein the silver has a weight percent concentration of X in the alloy, wherein X is sufficiently small that formation of Ag3Sn plates is substantially suppressed when the alloy in a liquefied state is being solidified by being cooled at to a lower temperature at which the solid Sn phase is nucleated, wherein the lower temperature corresponds to an undercooling &dgr;T relative to the eutectic melting temperature of the alloy, wherein the copper has a weight percent concentration in the alloy not exceeding about 1.5%, and wherein the bismuth has a weight percent concentration in the alloy from 0.1% to about 0.2%.