EFFECT OF IMMERSION TIME ON ANTIBACTERIAL COPPER LAYER FORMATION DURING ELECTROLESS PLATING. A disease caused by bacteria is vulnerable to become an outbreak at hospitals and public facilities through direct and indirect contact. Indirect contact usually occurs through an intermediate medium such as syringes, clothing, and doorknob in the hospital. Doorknob and sills are the places where every people will touch during visitation in the hospitals. Currently, sills are preferably chosen from aluminum because of its low price, corrosion resistant and lightweight properties. Aluminum sill is usually anodized by anodizing process to give its color as it is hard to be coated directly. However, anodizing products will form porous on the surface, and hence it will make an ideal place for bacteria to grow and colonize. In this research, copper sealing was made to close the pores and give a toxic environment for Escherichia coli. Escherichia coli was selected as the target because it can cause several diseases. The result showed that optimal electroless plating time is 26 minutes with coating thickness between 8-24 Î¼m. Copper successfully sealed the surface pores evenly. Kirby test revealed antibiotic activity of copper layer in every variable of fabrication. Salt spray result also showed that 26 minutes plating time produced the best effect for long-term environmental resistance.