The ISO 16866 standard specifies a test method for multi-layer nickel platings - the STEP test (simultaneous determination of the thickness of each layer and the electrode potential). This method enables simultaneous measurement of the thickness and electrode potential of each layer in multi-layer nickel platings, and is suitable for metal and Miscellaneous inorganic platings. The STEP test provides an accurate measurement means for the quality control and performance evaluation of platings, especially in the research and application of multi-layer platings. Through this standard, users can effectively analyze the structure of platings, optimize the platings process, and improve the Reliability and performance of platings products.