IMC formation between electroless Ni/Pd/Au surface finish and SnAgCu solder

The interfacial reaction between OSP, electrolytic Ni/Au, and electroless Ni/Pd/Au surface finish and SnAgCu solder on BGA package were investigated. After multiple reflows, IMC morphology and composition is examined by SEM and EDX. Cu
₆
Sn
₅
formed between LF35 and OSP finish, and Ag
₃
Sn were found disperse in the solder. Both (Ni
_x
,Cu
_1-x
)
₃
Sn
₄
and (Cu
_x
,Ni
_1-x
)
₆
Sn
₅
were observed on interface of electrolytic Ni/Au and electroless Ni/Pd/Au surface finish between SAC105.