Stacked integrated circuit assembly
View Patent ↗A stacked integrated circuit assembly includes a substrate having a top surface with at least one substrate connection pad. A first flip chip integrated circuit (FFIC) is disposed above the substrate, and a second flip chip integrated circuit (SFIC) is disposed above the FFIC. The FFIC is disposed between the substrate and the SFIC. The stacked integrated circuit assembly includes least one solder connection between the substrate connection pad and the FFIC and at least one solder connection between the FFIC and the SFIC.
1. A stacked integrated circuit assembly, comprising:
a substrate having a top surface with at least one substrate connection pad;
a first flip chip integrated circuit (FFIC) disposed above the substrate;
a second flip chip integrated circuit (SFIC) disposed above the FFIC, the FFIC disposed between the substrate and the SFIC;
a first solder connection between the substrate connection pad and the FFIC; and
a second solder connection between the FFIC and the SFIC,
wherein a first melting temperature of the first solder connection is different than a second melting temperature of the second solder connection and wherein connection pads of the FFIC, the SFIC and the substrate are coplanar with respective surfaces of the FFIC, the SFIC and the substrate, the respective surfaces each face corresponding solder connections.
2. The assembly of claim 1 , wherein the FFIC comprises a die having a first semiconductor material, and the SFIC comprises a die having a second semiconductor material, the second semiconductor material differing from the first semiconductor material.
3. The assembly of claim 1 , wherein the assembly is operable to process microwave frequency electrical signals.
4. A stacked integrated circuit assembly, comprising:
a substrate having a top surface, and at least one substrate connection pad disposed upon the top surface;
a first flip chip integrated circuit (FFIC), the FFIC comprising:
a FFIC front surface and opposite thereto a FFIC back surface, the FFIC front surface proximate to the substrate top surface;
at least one FFIC front connection pad disposed upon the FFIC front surface, each FFIC front connection pad aligned to at least one substrate connection pad;
at least one electrically conductive through die via, each through die via electrically coupled to one FFIC front connection pad and extending from the FFIC front surface to the FFIC back surface;
at least one FFIC back connection pad disposed upon the FFIC back surface, each FFIC back connection pad electrically coupled to one through die via; and
a die having a first semiconductor material;
a second flip chip integrated circuit (SFIC), the SFIC including:
a SFIC front surface and opposite thereto a SFIC back surface, the SFIC front surface proximate to the FFIC back surface;
at least one SFIC front connection pad disposed upon the SFIC front surface, each SFIC front connection pad aligned to at least one FFIC back connection pad; and
a die having a second semiconductor material, the second semiconductor material differing from the first semiconductor material;
a first solder connection between each FFIC front connection pad and each substrate connection pad, the first solder connection establishing a first gap between the FFIC front surface and the substrate; and
a second solder connection between each SFIC front connection pad and each FFIC back connection pad, the second solder connection establishing a second gap between the SFIC front surface and the FFIC back surface; and
wherein the assembly is operable to process microwave frequency electrical signals
wherein a first melting temperature of the first solder connection is lower than a second melting temperature of the second solder connection and wherein the connection pads of the FFIC, the SFIC and the substrate are coplanar with the front and the back surfaces of the FFIC, the front surface of the SFIC and the top surface of the substrate respectively.
5. The assembly of claim 4 , wherein the first semiconductor material comprises silicon and germanium, and the second semiconductor material comprises gallium and arsenic.
6. The assembly of claim 4 , wherein the FFIC and the SFIC comprise monolithic microwave integrated circuits.
7. The assembly of claim 4 , wherein the substrate comprises a printed circuit board.
8. The assembly of claim 4 , wherein each through die via is plated with an electrically conductive material.
9. The assembly of claim 4 , wherein each through die via is filled with an electrically conductive material.
10. The assembly of claim 4 , wherein each FFIC front connection pad is positioned adjacent to the through die via that the FFIC front connection pad is electrically coupled to.
11. The assembly of claim 4 , wherein each FFIC back connection pad is positioned adjacent to the through die via that the FFIC back connection pad is electrically coupled to.
12. The assembly of claim 4 further comprising a first underfill material positioned in the first gap.
13. The assembly of claim 4 further comprising a second underfill material positioned in a subset of the second gap.
14. The assembly of claim 4 , wherein the FFIC is positioned about parallel to the SFIC.
15. The assembly of claim 4 , wherein the FFIC is positioned about parallel to the substrate.
16. The assembly of claim 4 , wherein a first thickness of the first gap is about equal to a second thickness of the second gap.