Automated stress control of electroplated nickel-phosphorus alloy

Abstract

A process for automatic control of internal stress in electroplated nickel-phosphorus alloy using controlled current electrodeposition on a conductive substrate from a single electroplating bath yields a multiple-layered coating. This multi-layered deposit is a sequence of two alternating layers. One of these layers is a phosphorus-rich coating which is characterized by compressive stresses while the other layer is a tensile-stressed coating of low phosphorus content. The apparatus employed to achieve this automated control of internal stress includes a non-contact linear sensor for monitoring stresses in the coating and a programmable power supply for the current source.