## 5 Conclusions  
A typical EPC circuit was used to study the influence of ion contamination on insulation failure of HV printed boards using temperature and humidity bias tests. The starting temperature, humidity, and surface discharge boundary of the insulation of EPC were obtained. Our conclusions provide a reference for further strengthening the environmental protection requirements during the development of EPCs. The insulation deterioration of EPC occurred when the relative humidity was 75% or above, and the degree of deterioration was related to temperature and NaCl concentration. The uncontaminated samples (ionic contamination concentration was less than 1.56 \(\mathrm{\SIUnitSymbolMicro g}\)/cm\({}^{2}\)) and had slight changes at 85 \(\mathrm{\SIUnitSymbolCels  
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