Electroless copper plating on Al₂O₃ substrate assisted by a new non-noble pretreatment is developed, the surface exhibits granular distribution, and the particles are closely bound except for the presence of defects (large holes). Heat treatment is performed at various temperatures to modify this surface. Results show that slight surface changes occur when the heat treatment temperature is below the recrystallisation temperature. Beyond the recrystallisation temperature, particles are fused, thereby modifying certain properties. However, heat stress also increases with increased temperature to 800°C, leading to poor bonding between the plating and substrate. When the temperature approaches the melting point of copper, plating exhibits an entirely different surface morphology. The molten copper in the cooling process forms shrinkages and dimples that reduce coating performance. The optimal heat treatment temperature is deemed to be approximately 500°C.