Surface Leakage Current (SLC) Methodology for Electrochemical Migration Evaluation

Modern electronics is characterised by the increasing level of integration in printed circuit board (PCB) technology and the reduced insulation spacing between adjacent conductors. Surface insulation resistance (SIR) measurement has often been used alone to determine the cleanliness of PCB assembly; however, when proper SIR measurement is used in conjunction with surface leakage current (SLC) measurement,the result can reveal the dynamic nature of surface electrochemical migration (SECM)processes at the microscopic level, and the effect of such processes on product quality and reliability. This paper presents a newly developed measurement methodology, which measures SLC per square unit area at a sampling rate that is orders of magnitude higher than that of conventional SIR measurement methods. It is aimed to capture the transient surge of SLC which is detrimental to the functionality of product.