Multi-layer circuit substrate and motor drive circuit substrate

Abstract

Conducting layers and resin-made insulating layers are alternately laminated to form a laminated circuit portion, and a metal substrate is installed so as to be in contact with an insulating layer, which is the lowermost layer. The conducting layers, the insulating layers, and the metal substrate are thermal compression bonded. In order to connect the uppermost conducting layer on which electronic component is placed with the lowermost insulating layer, a conducting layer is formed on the inner surface by copper plating to install a heat dissipating via into which a resin is filled. A conducting layer, which is the uppermost layer, is subjected to gold plating, with nickel plating undercoated. An electronic component for driving a motor is placed on the uppermost conducting layer, by which the metal substrate can be used as a motor drive circuit substrate for an electric power steering system.

Dependencies are inferred from the claim text.