A connection structure for a substrate is provided. The substrate has a plurality of connection pads and an insulation protection layer with the connection pads being exposed therefrom. The connection structure includes a metallic layer formed on an exposed surface of each of the connection pads and extending to the insulation protection layer, and a plurality of conductive bumps disposed on the metallic layer and spaced apart from one another at a distance less than or equal to 80 μm, each of conductive bumps having a width less than a width of each of the connection pads. Since the metallic layer covers the exposed surfaces of the connection pads completely, a colloid material will not flow to a surface of the connection pads during a subsequent underfilling process of a flip-chip process. Therefore, the colloid material will not be peeled off from the connection pads.