抄録
Several equations to calculate throwing power index have been proposed to compare the throwing power for various plating solutions. In Watson's method (Hull Cell method), Field's equation is mostly preferred. Throwing power index, T(%), calculated from the equation does not necessarily indicate an essential strength of throwing power because any value can be obtained for a certain secondary current distribution, if measuring points on a Hull Cell panel are intentionally selected. Field's equation contains the terms of primary and secondary current density ratio (L and M) which are determined from the thicknesses at two points on the panel. If the measuring points are adjacent to each other and are on a high current density edge of the panel, L and M values gradually reach unity and T value zero. In order to improve this defect in Field's equation a new equation has been formulated on the basis of the slope of a secondary current distribution curve determined from the thicknesses measured at two points on the Hull Cell panel and from plating time.
