The present invention provides an aluminum etchant solution for etching an aluminum surface in the presence of solder bumps. The etchant solution includes about 42% to about 80% phosphoric acid; about 0.1% to about 6% nitric acid; about 5% to about 40% acetic acid; about 0.005% to about 5% of an amine oxide surfactant; about 0.1% to about 8% of a Pb solubilizing additive; and about 5 to about 25% de-ionized water; wherein the solder bumps are substantially phosphate free after the etching. Also provided is a process for etching an exposed aluminum surface in a semiconductor structure in the presence of solder bumps including the steps of: contacting the exposed aluminum surface with the etchant solution; rinsing the semiconductor structure with de-ionized water; and drying the semiconductor structure to remove residual water; wherein the solder bumps are substantially phosphate free after the etching.