Method of manufacturing a circuit device

A method of manufacturing a circuit device, comprising:

• providing a lead frame comprising a plurality of leads, each of the leads comprising an island portion, a bonding portion elevated from the island portion, a slope portion extending obliquely so as to connect the island portion and the bonding portion, and a lead portion extending from the bonding portion,
• mounting circuit elements on upper surfaces of the island portions;
• connecting the circuit elements to corresponding bonding portions by wirings wherein one of the plurality of leads is a first input lead, another of the plurality of leads is a second input lead, and yet another of the plurality of leads is an output lead for outputting alternating-current power obtained by converting direct-current power inputted through the first input lead and the second input lead;
• attaching lower surfaces of the island portions to an upper surface of a circuit board;
• encapsulating by a resin the circuit board, the circuit elements and the lead frame so that the lead portions are not covered by the resin;
• connecting the first input lead to a positive electrode of a direct-current power source;
• and
• connecting the second input lead to a negative electrode side of the direct-current power source.