Patent attributes
Techniques and structures have been developed for providing lead-free column grid array interconnect structures. An exemplary interconnect has a body, a first joint, and a second joint, all having compositions off the eutectic composition in a ternary alloy system, the first joint having a ternary composition distinct from the body composition, and the second joint having a ternary composition distinct from the body composition and the first joint composition. The interconnect may be formed by solidifying a solder, having a Sn-poor ternary composition in the Sn—Ag—Cu alloy system, in contact with a column, having a Ag-rich Cu-deficient composition in the same system, and a bonding pad or bare substrate. A second solder, having a Sn-rich ternary composition, may be solidified in contact with the column and a second bonding pad or bare substrate. In some embodiments joints may be severed and reformed by remelting and resolidifying the lower-liquidus solder.
