A semiconductor package comprises a semiconductor chip having an active surface with a conductive pad thereon; an electroplated Au—Sn alloy bump over the active surface; and a (glass) substrate comprising conductive traces electrically coupling with the electroplated Au—Sn alloy bump, wherein the electroplated Au—Sn alloy bump has a composition from about Au0.85Sn0.15 to about Au0.75Sn0.25 in weight percent uniformly distributed from an end in proximity to the active surface to an end in proximity to the substrate. A method of manufacturing a semiconductor package comprises forming patterns of conductive pads on an active surface of a semiconductor chip; electroplating Au—Sn alloy bump over the conductive pads; and bonding the semiconductor chip on a corresponding conductive trace on a substrate by a reflow operation or a thermal press operation.