公开(公告)号：EP1483419A4

公开(公告)日：2005-07-06

申请号：EP03707862

申请日：2003-02-11

Applicant: IBM

Inventor： CHOI WON K ,  GOLDSMITH CHARLES C ,  GOSSELIN TIMOTHY A ,  HENDERSON DONALD W ,  KANG SUNG K ,  PUTTLITZ KARL J SR ,  SHIH DA-YUAN

IPC: B23K1/00 ,  B23K35/26 ,  B23K101/42 ,  C22C13/00 ,  H01L21/60 ,  H01L23/12 ,  H05K3/34 ,  C22C1/00

CPC classification number: C22C13/00 ,  B23K35/262 ,  B23K2201/36 ,  H01L24/11 ,  H01L24/16 ,  H01L2224/05568 ,  H01L2224/05573 ,  H01L2924/01322 ,  H01L2924/14 ,  H05K3/3436 ,  H05K3/3463 ,  Y10T428/12708 ,  Y10T428/12715 ,  Y10T428/12722 ,  H01L2924/00

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 Ag3Sn plates (57, 58) 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 δT 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 Ag3Sn plate (57, 58) formation in the alloy. The copper has a weight percent concentration in the alloy not exceeding about 1.5 %.