Polydimethylsiloxane (PDMS)-based organic-inorganic hybrids have been studied because of their high dielectric strength, heat resistivity, and flexibility. In this study, we fabricated Al2O3 coatings on metal substrates with sufficient electrical insulation, heat conductivity, and thermal stability by electrophoretic deposition (EPD) using PDMS-based hybrid binders. The scratch hardness, thermal conductivity, and electrical breakdown strength of the Al2O3 coating before and after heat treatment at 300 degrees C for 500h were 2.0N, 3.1W/mK, and 60kV/mm, respectively. These results demonstrate the usefulness of EPD using PDMS-based hybrid binders for fabricating flexible heat dissipative substrates used in high-temperature environments.