The orientation relationship between Ni and Cu6Sn5 formed during the soldering reaction

The preferred orientation growth of intermetallic compounds is becoming an increasingly important issue, due to recent advances in three-dimensional integrated circuits. This study reveals that Cu6Sn5 that is formed on Ni does not grow in random orientations, but exhibits a pronounced preferred orientation relationship. This relationship is identified as (12¯0)(Cu,Ni)6Sn5(11¯1)Niand[001](Cu,Ni)6Sn5[110]Ni, according to electron backscatter diffraction and high-resolution transmission electron microscopy analysis. One critical implication is that no Ni3Sn4 exists between Cu6Sn5 and Ni because the Cu6Sn5/Ni interface is coherent.