Provided are a reverse-reflow core, a semiconductor package, and a method of fabricating a semiconductor package. The semiconductor package includes: a semiconductor apparatus including a bump pad; and a bump portion bonded to the bump pad. The bump portion includes: a core; an intermetallic compound layer formed on the core; and a solder layer coating the intermetallic compound layer, wherein the thickness of a portion of the solder layer decreases as the distance between the portion of the solder layer and the bump pad increases. The reverse-reflow core, the semiconductor package, and the method of fabricating a semiconductor package enable the fabrication of a semiconductor package having high bonding strength and a high degree of precision.