Measuring the covering power of a tin plating bath using scanning electron microscopy

Abstract

For electroplating articles with a complex shape, it is essential that the plating bath should (1) cover the contoured surface in a short time and (2) produce a uniform thickness preferably over the entire surface or at least over the significant surfaces. The former is decided by the covering power of the bath and the latter by the13; throwing power of the bath. Throwing power refers to the thickness distribution of the deposit, whereas covering power is concerned with the ability of the bath to cover the entire cathode surface in the least possible time, even in low current density areas. Though quantitative methods (Haring and Blum cell, Hull cell, etc.)are available for measuring the throwing power of the bath, there are no such methods for covering power. In our laboratory, we examined the feasibility of measuring the covering power of a tin plating bath with the help of13; scanning electron microscopy (SEM).This article describes an approach for quantitative estimation of covering power of a tin plating bath.