Multiple die interconnect system

1. A multiple die electronic system comprising:

a substrate having conductors formed thereon,

a base IC die having a first surface facing the substrate and a second surface parallel to the first surface,

a first secondary IC die residing between the first surface of the base IC die and the substrate and linked to the first surface of the base IC die through first conductive signal paths,

conductive contacts extending between the first surface of the base IC die and the conductors on the substrate for conveying first signals between the base IC die and the conductors on the substrate, wherein at least one of second signals provided between the first secondary IC die and the base IC die has a higher frequency than the first signals provided between the base IC die and the substrate.

2. The multiple die electronic system in accordance with claim 1 wherein solder forms the first conductive signal paths.

3. The multiple die electronic system in accordance with claim 1 wherein the substrate is a printed circuit board substrate.

4. The multiple die electronic system in accordance with claim 1 wherein the substrate is a semiconductor substrate.

5. The multiple die electronic system in accordance with claim 1 wherein the conductive contacts comprise resilient spring contacts.

6. The multiple die electronic system in accordance with claim 1 wherein the conductive contacts comprise:

resilient spring contacts formed on the first surface of the base IC die, and a spring contact socket providing signal paths between the spring contacts and the conductors on the substrate.

7. The multiple die electronic system in accordance with claim 1 further comprising:

a third level IC die residing between the first surface of the base IC die and a third surface of the first secondary IC die residing between the first surface of the base IC die and the substrate, the third level IC linked to the third surface of the second level IC die through conductive signal paths.

8. The multiple die electronic system in accordance with claim 5 wherein the spring contacts are formed an the first surface of the base IC die and soldered to the conductors on the substrate.

9. A multiple die electronic comprising:

a substrate having conductors formed thereon:

a base IC die having a first surface facing the substrate and a second surface parallel to the first surface;

a first secondary IC die residing between the first surface of the base IC die and the substrate and linked to the first surface of the base IC die through first conductive signal paths;

conductive contacts comprising resilient springs extending between the first surface of the base IC die and the conductors on the substrate for conveying signals between the base IC die and the conductors on the substrate; and

means for holding the base IC die proximate to the substrate so that the spring contacts are compressed against the conductors on the surface of the substrate.

10. A multiple die electronic comprising:

a substrate having conductors formed thereon;

a base IC die having a first surface facing the substrate and a second surface parallel to the first surface;

a first secondary IC die residing between the first surface of the base IC die and the substrate and linked to the first surface of the base IC die through first conductive signal paths;

first conductive contacts extending between the first surface of the base IC die and the conductors on the substrate for conveying signals between the base IC die and the conductors on the substrate;

a second secondary IC die; and

second conductive paths linking the second secondary IC die to the second surface of the base IC die.

11. The multiple die electronic system in accordance with claim 10 further comprising:

conductive vias for providing signal paths between the first and second surfaces of the base IC die.

12. The multiple die electronic system in accordance with claim 10 wherein the second conductive paths comprise spring contacts.