Synergistic Effects of Copper Plating Additives Filter Type for Coil Plating in Write Heads

摘要

The coils in write heads for disk drives are made of electroplated copper. These can beplated from acid copper baths with proprietary additives. Recently, plating studies done fordamascene copper interconnects have shed light on specific chemicals used in copper platingadditives. A Hull cell study of three copper additives has been done to assess their applicabilityfor plating copper coils. The three additives studied were polyethylene glycol, Janus Green Band 3-mercapto-propane-sulfonic acid. These coils were also plated in the same acid copper bathin presence of a proprietary additive. A large offset was found between the test sites and the coilsplated thickness. This phenomenon was related to polyethersulfone filter and was reduced bychanging the filter to the inert polypropylene one. An attempt is made to explain thesephenomena.