A substrate includes a first metal layer, a second metal layer, a third metal layer and an insulation layer surrounding the first metal layer, the second metal layer and the third metal layer. The first power component is electrically connected to the first metal layer. The second power component is electrically connected to the second metal layer. The shortest distance between the first metal layer exposed to a second surface of the insulation layer and the second metal layer exposed to the second surface is a first distance, the shortest distance between a first metal layer of the insulation layer exposed to the first surface and the second metal layer exposed to the first surface is a second distance, and a ratio value of the first distance to the second distance ranges between 1.25 and 1.4.