Power mosfet

A power MOSFET, comprising:

• a substrate comprising an active surface, a back surface opposite to the active surface, a source region, a gate region, and a drain region, the source region and the gate region located on the active surface, the drain region located on the back surface;
• a first patterned metal layer disposed on the active surface and comprising a source electrode, a gate electrode, a drain electrode and a connecting trace, the source electrode and the gate electrode electrically connected to the source region and the gate region respectively, the connecting trace located at an edge of the substrate and electrically connected to the drain electrode;
• a patterned dielectric layer disposed on the active surface and exposing the first patterned metal layer;
• a second patterned metal layer comprising a plurality of under ball metal (UBM) layers and a connecting metal layer, the plurality of UBM layers covering the source electrode, the gate electrode, and the drain electrode respectively, the connecting metal layer covering and connecting the connecting trace and extending to the edge, so as to electrically connected to the drain region via the edge;
• and
• a plurality of solder balls disposed on the plurality of UBM layers respectively.