Circuit layout of circuit substrate, light source module and circuit substrate

A circuit layout of a circuit substrate having a plurality of device bonding areas is provided. The circuit layout includes first pads, second pads, bridging lines, first outer leads and second outer leads. Each device bounding area is configured with one first pad and one second pad. The bridging lines are respectively disposed between any two adjacent device bounding areas and extended from a side of the first pad inside one device bounding area to a side of the second pad inside another one device bounding area adjacent to the first pad. Each first outer lead and each second outer lead are respectively corresponding to one first pad and one second pad, are respectively correspondingly extended into the device bounding area which the first pad and the second pad are located at, and are beside the first pad and the second pad correspondingly.