The invention relates to a substrate and a process for mounting a chip on the substrate. The substrate comprises a substrate body and a chip mounted on the substrate body, wherein pads of a solder layer are arranged on the substrate body, and the chip has electrodes connected to the pads. The pads are configured to be larger than the electrodes. Therefore, after solder melts, even if drum-shaped solder joints appear, a firm bonding surface and firm bonding force can be provided, and the risk of solder joint failure is greatly reduced. In addition, because the area of the pads is increased, the area of the solder coating the pads is increased. Therefore, the design can increase the binding force between the solder and the pads and reduce the occurrence of reliability decline caused by interface deterioration. In addition, by appropriately choosing the sizes of the pads, possible chip tilt after an LED chip is mounted on a flexible substrate can be effectively avoided, the porosity is reduced, and the reliability of solder joints can be improved.