초록 ▼

Electroplating nickel-iron alloys onto objects having complex topographical shapes with projections and hollows such as upper pole pieces of thin film magnetic recording heads has been found to yield a substantial variation in nickel-iron alloy composition from point to point within a single pattern

Electroplating nickel-iron alloys onto objects having complex topographical shapes with projections and hollows such as upper pole pieces of thin film magnetic recording heads has been found to yield a substantial variation in nickel-iron alloy composition from point to point within a single pattern. Providing a low total dischargeable ion concentration in the bath is helpful to reduce such variations when plating in the 80:20 Ni:Fe alloy range. That is, it is desirable to use a low value of Fe++and Ni++ion concentrations and a relatively low current density to operate at the relatively flat peak of the curve of the iron percentage in the plated alloy vs. current density curve. The curve can be raised or lowered by increasing or decreasing the total dischargeable ion concentration respectively for a given Ni++/Fe++ion ratio. The preferred Fe++ion concentration range for Ni:Fe alloy ratio near 80:20 is about 0.15-0.3 g/l for a range of 10-14 g/l of Ni++ion in a solution with a pH of about 3, a temperature of about 20°-35°C. where the Ni++/Fe++ratio in the solution ranges from about 45 to 1 to about 70 to 1. Preferably, an electrolyte for reducing pitting such as 0-100 g/l of NaCl is employed. The cation (Na+) of the latter electrolyte should not be a dischargeable ion. Plating current density is preferably between about 2 ma/cm2 and 12 ma/cm2, and optimum results are achieved for values from about 4 to 8 ma/cm2.

대표청구항 ▼

A nickel-iron electroplating method for plating NiFe alloy onto a substrate with a relatively high degree of uniformity of magnetic nickel-iron alloy composition over a range of plating current densities comprising, an aqueous plating bath solution at a temperature in the range from about 20°C. to a

A nickel-iron electroplating method for plating NiFe alloy onto a substrate with a relatively high degree of uniformity of magnetic nickel-iron alloy composition over a range of plating current densities comprising, an aqueous plating bath solution at a temperature in the range from about 20°C. to about 35°C., placing a substrate with a complex topographical shape in said plating bath solution, employing a constant current plating density from about 2 milliamperes per centimeter squared to about 12 milliamperes per centimeter squared, said plating bath solution having ferrous ion concentration in the range from about 0.15 to about 0.3 grams per liter and a nickel ion concentration in the range from about 10 to about 14 grams per liter, with a pH of the bath of about 3, maintaining continuous agitation of a paddle moving over the surface of the cathode at a distance of about 2-3 millimeters at a rate of about 1 cycle per second, and thereby providing differences of less than about 2% by weight in the nickel/iron composition ratio of the NiFe magnetic alloy produced across said complex topographical shape.