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专利名称：Electroplating of nickel-iron alloys for
uniformity of nickel/iron ratio using a lowdensity plating current
发明人：Nathaniel C. Anderson,Charles R. Grover, Jr.申请号：US06/122628申请日：19800219公开号：US04279707A公开日：19810721
摘要：Electroplating nickel-iron alloys onto objects having complex topographicalshapes with projections and hollows such as upper pole pieces of thin film magneticrecording heads has been found to yield a substantial variation in nickel-iron alloycomposition from point to point within a single pattern. Providing a low totaldischargeable ion concentration in the bath is helpful to reduce such variations whenplating in the 80:20 Ni:Fe alloy range. That is, it is desirable to use a low value ofFe.sup.++ and Ni.sup.++ ion concentrations and a relatively low current density tooperate at the relatively flat peak of the curve of the iron percentage in the plated alloyvs. current density curve. The curve can be raised or lowered by increasing or decreasingthe total dischargeable ion concentration respectively for a given Ni.sup.++ /Fe. sup.++ion ratio. The preferred Fe.sup.++ ion concentration range for Ni:Fe alloy ratio near 80:20is about 0.15-0.3 g/l for a range of 10-14 g/l of Ni.sup.++ ion in a solution with a pH ofabout 3, a temperature of about 20°-35° C. where the Ni.sup.++ /Fe.sup.++ ratio in thesolution ranges from about 45 to 1 to about 70 to 1. Preferably, an electrolyte forreducing pitting such as 0-100 g/l of NaCl is employed. The cation (Na.sup.+) of the latter
electrolyte should not be a dischargeable ion. Plating current density is preferablybetween about 2 ma/cm.sup.2 and 12 ma/cm.sup.2, and optimum results are achieved forvalues from about 4 to 8 ma/cm.sup.2.
申请人：INTERNATIONAL BUSINESS MACHINES CORPORATION
代理人：Graham S. Jones, II
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