Semiconductor device with thermal dissipation lead frame
A lead frame for assembling a semiconductor device has a die pad surrounded by lead fingers. Each of the lead fingers has a proximal end close to but spaced from an edge of the die pad and a distal end farther from the die pad. A semiconductor die is attached to a surface of the die pad. The die has die bonding pads on its upper surface that are electrically connected to the proximal ends of the lead fingers with bond wires. An encapsulation material covers the bond wires, semiconductor die and the proximal ends of the lead fingers. Prior to assembly, hot spots of the die are determined and the lead fingers closest to the hot spots are selected to project closer to the die than the other lead fingers. These longer lead fingers assist in dissipating the heat at the die hot spot.
1. A semiconductor device, comprising:
a die pad;
a semiconductor die attached to the die pad;
a plurality of lead fingers spaced from and projecting outwardly from the die pad, each of the lead fingers having a proximal end close to but spaced from an edge of the die pad and a distal end farther from the die pad;
bond wires electrically coupling bonding pads on a surface of the semiconductor die to respective proximal ends of the lead fingers; and
an encapsulation material covering the bond wires, semiconductor die and the proximal ends of the lead fingers,
wherein at least one thermal dissipating lead finger selected from the plurality of lead fingers has a proximal end closer to the edge of the die pad than proximal ends of lead fingers that are not selected as the at least one thermal dissipating lead finger and wherein the at least one thermal dissipating lead finger is the closest lead finger to a thermal hot spot region of the semiconductor die, wherein the at least one thermal dissipating lead finger includes two or more lead fingers that are the closest lead fingers to the thermal hot spot region of the semiconductor die.
2. The semiconductor device of claim 1 , wherein each thermal dissipating lead finger provides a lower die to board thermal resistance than the lead fingers that are adjacent to the at least one thermal dissipating lead finger.
3. A lead frame for use in assembling a semiconductor device, the lead frame comprising:
a die pad for supporting a semiconductor die;
a frame surrounding the die pad;
die pad support members coupling the die pad to the frame; and
a plurality of lead fingers extending from the frame towards the die pad, each of the lead fingers having a distal end at the frame and a proximal end close to but spaced from an edge of the die pad,
wherein at least one thermal dissipating lead finger selected from the plurality of lead fingers has a proximal end closer to the edge of the die pad than proximal ends of lead fingers that are not selected as the at least one thermal dissipating lead finger, and wherein the at least one thermal dissipating lead finger is the closest lead finger to a thermal hot spot region of a semiconductor die to be attached to the die pad.
4. The lead frame of claim 3 , wherein that at least one thermal dissipating lead finger is a single lead finger.
5. The lead frame of claim 4 , wherein the single lead finger has a lateral projection extending from its proximal end.
6. The lead frame of claim 5 , wherein the lateral projection extends in a gap between a closest edge of the die pad and at least one of the plurality of lead fingers.
7. The lead frame of claim 3 , wherein the plurality of lead fingers comprise die pad edge lead finger groups disposed between the die pad support members, and wherein the at least one thermal dissipating lead finger is located away from the die pad support members.
8. The lead frame of claim 7 , wherein the at least one thermal dissipating lead finger is centrally located between the die pad support members.