A power MOSFET includes a substrate, a dielectric layer, solder balls, first and second patterned-metal layers. The substrate includes an active surface, a back surface, a source region and a gate region on the active surface, and a drain region on the back surface. The first patterned-metal layer disposed on the active surface includes a source electrode, a gate electrode, a drain electrode and a connecting trace. The source and gate electrodes electrically connect the source and gate regions. The connecting trace located at an edge of the substrate electrically connects the drain electrode. The dielectric layer disposed on the active surface exposes the first patterned-metal layer. The second patterned-metal layer includes UBM layers covering the source, gate and drain electrodes and a connecting metal layer covering the connecting trace and extending to the edge to electrically connect the drain region. The solder balls are disposed on the UBM layers.