First-principles Investigation of the Structural and Electronic Properties of Cu Based Intermetallics

Cu
₆
Sn
₅
is an important intermetallic compound (IMC), which was known to improve greatly the reliability of the solder joints in integrated circuits. The first-principles calculation were performed to determine the stable structure of Cu
_(6-x)
Ni
_x
Sn
₅
IMC. The structural and electronic properties of Cu
_(6-x)
Ni
_x
Sn
₅
IMCs have been calculated. The results of energy calculation and density of states demonstrate that this Cu
₄
Ni
₂
Sn
₅
IMC had a more stable structure than Cu
₆
Sn
₅
. The mechanical stability of the systems was studied to compare the compressibility of the matrices. A priori rule is formulated to correlate the stability and composition of the said intermetallics.