Influence of synthesis temperature, amine concentration, and deposition voltage on the structural and dielectric properties of hBN/waterborne epoxy composite coatings

Cationic waterborne epoxy composite coatings filled with hexagonal boron nitride (hBN) are increasingly vital in advanced semiconductor packaging and electronic power transistor heatsinks to provide electrical isolation while eliminating localized hot spots. However, electrophoretic deposition (EPD) lines suffer from various macroscopic defects—such as edge tearing and micro-voiding—due to poorly controlled pre-EPD resin amination parameters and turbulent high-voltage particle transport. This study implements a comprehensive three-factor Full Factorial design (27 runs) to map the independent and interactive influences of synthesis temperature (70 °C–130 °C), amination agent concentration (1.91–5.71 mL/L N -methylethanolamine), and EPD voltage (10–30 V) on composite coating properties. Analysis of Variance (ANOVA) demonstrates that amine concentration is the most dominant independent variable governing central coating thickness ( P = 0.002) and dielectric constant ( P = 0.014), while EPD voltage is statistically insignificant for central film thickness ( P = 0.851). High EPD voltages (30 V) trigger severe fringing field effects, resulting in structurally unviable edge configurations prone to tearing. To ensure optimal material processability, maximum structural uniformity, and stable dielectric property, a strict processing directive of 10 V EPD voltage coupled with a baseline resin amination matrix synthesized at 130 °C with 5.71 mL/L of amination agent is recommended.