Stacked interposer leadframes

1. A stacked leadframe assembly comprising:

a first die having a surface that defines a mounting plane;

a first leadframe having a die paddle with side panels that extend in a first direction and have attachment surfaces in the mounting plane, the first leadframe being stacked over and attached to the first die;

a second die, stacked over and attached to the first leadframe; and

a second leadframe having a die paddle with side panels that extend in a second direction that is at an angle in the range of 45-135° from the first direction and have attachment surfaces in the mounting plane, the second leadframe being stacked over and attached to the second die,

wherein the leadframe assembly is configured so as to allow direct attachment of the surface of the first die to a substrate.

2. The leadframe assembly of claim 1 wherein at least one of the leadframes is thermally connected to at least one of the dice.

3. The leadframe assembly of claim 1 wherein:

the first leadframe is connected to a first manufacturing frame by a first bridge section;

the second leadframe is connected to a second manufacturing frame by a second bridge section;

the first leadframe comprises a first top surface;

the second leadframe comprises a second top surface;

the first and second leadframes both comprise a first thickness;

the first bridge section comprises a second thickness that is less than the first thickness;

the second bridge section comprises a third thickness that is less than the difference between the first and second thicknesses; and

the first and second bridge sections at least partially overlap each other such that the first top surface is coplanar with the second top surface when the second manufacturing frame is stacked over the first manufacturing frame.

4. The leadframe assembly of claim 1 wherein at least one of the leadframes is electrically isolated from the dice.

5. The leadframe assembly of claim 1 wherein the die and leadframes are attached to each other by solder.

6. The leadframe assembly of claim 1 wherein the die and leadframes are attached to each other by thermally conductive adhesive.

7. The stackable leadframe assembly of claim 1 wherein the directions in which the side panels extend from the first and second leadframes are perpendicular to each other.

8. The leadframe assembly of claim 1 wherein each leadframe comprises:

first and second support members each having an attachment surface, the attachment surfaces lying in the mounting plane;

a die paddle that is substantially planar with a thickness and a bottom surface, the bottom surface lying in a second plane that is substantially parallel to the mounting plane and offset from the mounting plane by a distance that is approximately equal to the total thickness of the dice and leadframes that are located under the leadframe, the die paddle having first and second ends on opposite sides of the die paddle;

at least one first connecting member connected between the first end of the die paddle and the first support member; and

at least one second connecting member connected between the second end of the die paddle and the second support member.

9. The leadframe assembly of claim 1 further comprising at least a third die and at least a third leadframe stacked over and attached to the stack of dice and leadframes.

10. An integrated circuit device, comprising:

a substrate having circuitry;

at least one stacked leadframe assembly attached to the substrate, the stacked leadframe assembly comprising:

a first die having a surface directly attached to the circuitry of the substrate, the surface defining a mounting plane;

a first leadframe stacked over the first die, the first leadframe comprising attachment surfaces coplanar with the mounting plane;

at least one second die stacked over the first leadframe; and

at least one second leadframe stacked over the second die, the at least one second leadframe comprising attachment surfaces coplanar with the mounting plane; and

an enclosing body that encapsulates the substrate and stacked leadframe assembly, wherein the attachment surfaces that are coplanar with the mounting plane are the only portions of the first and at least one second leadframes that are exposed through the enclosing body.

11. The integrated circuit device of claim 10 wherein the stacked leadframe assembly is attached to the substrate with solder.

12. The integrated circuit device of claim 10 wherein a portion of at least one of the leadframes provides an electrical connection from at least one of the die in the stacked leadframe assembly to the circuitry on the substrate.

13. The integrated circuit device of claim 10 wherein at least one of the leadframes provides a thermal connection from at least one of the die in the stacked leadframe assembly to the substrate.

14. The integrated circuit device of claim 10 further comprising a heatsink in thermal contact with the stacked leadframe assembly, wherein a portion of the heatsink is exposed on an external surface of the body.

15. The integrated circuit device of claim 14 wherein the enclosing body is cut from a stack comprising a first and at least one second manufacturing frames that are overmolded with a molding compound, wherein the first and at least one second manufacturing frames are configured to lie in a single plane along and have a constant combined thickness around a perimeter of the stack of manufacturing frames when the molding compound is injected around the stack of manufacturing frames.