Synthesis of undercoat with high temperature and humidity resistance for resistor

Epoxy resin undercoat, with high temperature and humidity resistance, for resistor was prepared by curing of acid anhydride and accelerating of glycol with proper nano-SiO₂ added at 80°C. The properties of undercoat prepared were characterized by electrical tests, infrared spectra (IR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The results showed more compact and steady inter-crosslinked network structure was formed in the modified epoxy resins undercoat with nano-SiO₂ added, which leaded to the performance of modified epoxy resin undercoat improved greatly. The undercoat with nano-SiO₂ 2.68wt%, kept for six months at room temperature without flocculating and aggregating, is of good stability. The varying ratio of resistance with such undercoat painted is less than 1% after high temperature and humidity resistance test. In this work, an attempt has been made to prepare undercoat, with high temperature and humidity resistance, for resistor by modifying epoxy resin using nano-SiO₂.