Patent ID: 7621367

Claim:
An electric power steering apparatus including an electric motor for outputting assist torque to a steering wheel of a vehicle, and a control unit for controlling the driving of said electric motor, said control unit comprising: a power main body that includes a bridge circuit composed of a plurality of semiconductor switching elements for switching a current supplied to said electric motor in accordance with torque assisting said steering wheel; a control main body that generates a drive signal to control said bridge circuit based on the steering torque of said steering wheel; a metal substrate that is composed of a plurality of insulating layers and a plurality of conductive layers having wiring patterns respectively formed thereon, said insulating layers and said conductive layers being alternately laminated one over another on a metal plate; and a heat sink with said metal substrate being fixedly attached thereto; wherein said power main body and said control main body are arranged on the same surface of said metal substrate, and said power main body and said control main body are electrically connected to each other through said metal substrate.