Method of manufacturing a circuit device

1. 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.

2. The method of claim 1 , wherein a first circuit element of the circuit elements mounted on an island portion of a first lead of the leads and a bonding portion of a second lead of the leads are electrically connected through a first wiring.

3. The method of claim 2 , wherein there is no other lead between the first lead and the second lead.

4. The method of claim 2 , wherein there is a third lead between the first lead and the second lead, and the first wiring passes above the third lead.

5. The method of claim 1 , wherein mounting circuit elements on upper surfaces of the island portions comprises:

mounting a diode on an upper surface of the island portion of a first lead; and

mounting a transistor on the upper surface of the island portion of the first lead.

6. The method of claim 5 , wherein mounting the transistor on the upper surface of the island portion of the first lead further comprises:

mounting an insulated gate bipolar transistor on the upper surface of the island portion of the first lead.

7. The method of claim 6 , further comprising:

mounting an insulative control board on the upper surface of the circuit board; and

mounting a control element on an upper surface of the insulative control board.

8. The method of claim 7 , further comprising:

connecting the control element to at least one of the circuit elements through at least one wiring.

9. The method of claim 8 , wherein connecting the control element to the at least one of the circuit elements through the at least one wiring comprises:

connecting the control element to the transistor through the at least one wiring.

10. The method of claim 1 , further comprising:

mounting an insulative control board on the upper surface of the circuit board; and

mounting a control element on an upper surface of the insulative control board.

11. The method of claim 10 , further comprising:

connecting the control element to at least one of the circuit elements through at least one wiring.