Semiconductor package including dual stiffener

1. A semiconductor package comprising:

a dual stiffener including an upper stiffener and a lower stiffener;

an upper package including an upper package substrate, a semiconductor chip centrally mounted on an upper surface of the upper package substrate, and the upper stiffener disposed along an outer edge of the upper package substrate; and

a lower package substrate that centrally mounts the upper package and includes the lower stiffener disposed on an upper surface of the lower package substrate to surround the upper package substrate; and

passive elements disposed in at least one of the upper surface of the upper package substrate between the semiconductor chip and the upper stiffener, and a central portion of a lower surface of the lower package substrate.

2. The semiconductor package of claim 1 , wherein the upper stiffener is a square-ring having a rectangular cross-section, and

the lower stiffener includes a fence portion having a rectangular cross-section and a cover portion extending horizontally from an upper surface of the fence portion to contact an upper surface of the upper stiffener.

3. The semiconductor package of claim 1 , wherein the fence portion of the lower stiffener is a square-ring, and

the upper stiffener and the lower stiffener are laterally spaced apart.

4. The semiconductor package of claim 1 , wherein a first area occupied by the upper package substrate is less than a second area occupied by the lower package substrate, and

the upper package substrate includes a core layer disposed between an upper wiring layer and a lower wiring layer, wherein the upper wiring layer and the lower wiring layer are electrically connected through the core layer by a through-via.

5. The semiconductor package of claim 1 , wherein the upper package is centrally mounted on the lower package substrate using first connections members having a first pitch, and

the lower package substrate further includes second connection members disposed on a lower surface of the lower package substrate and having a second pitch greater than the first pitch.

6. The semiconductor package of claim 1 , further comprising:

at least one of a dynamic random access memory (DRAM) package and a power management integrated circuit (PMIC) package disposed on the upper surface of the lower package substrate between the lower stiffener and the upper package.

7. The semiconductor package of claim 1 , further comprising:

a heat sink disposed on the upper package and having a lower surface thermally contacting an upper surface of the semiconductor chip.

8. The semiconductor package of claim 7 , wherein the lower surface of the heat sink is flat, and

an upper surface of the upper stiffener and an upper surface of the lower stiffener are separated from the lower surface of the heat sink.

9. The semiconductor package of claim 7 , wherein the lower surface of the heat sink includes a single-step, stepped-down center portion surrounded by an outer portion,

the stepped-down center portion thermally contacts the upper surface of the semiconductor chip, and

the outer portion thermally contacts an upper surface of the lower stiffener.

10. The semiconductor package of claim 7 , wherein the lower surface of the heat sink includes a two-step, stepped-down center portion having a lower step portion and an upper step portion surrounded by an outer portion,

the lower step portion thermally contacts the upper surface of the semiconductor chip,

the upper step portion thermally contacts an upper surface of the upper stiffener, and

the outer portion thermally contacts an upper surface of the lower stiffener.

11. A semiconductor package comprising:

a dual stiffener including an upper stiffener and a lower stiffener;

an upper package including an upper package substrate, a system on chip (SoC) centrally mounted on an upper surface of the upper package substrate using an upper ball grid array (BGA), and the upper stiffener disposed along an outer edge of the upper package substrate;

a lower package substrate that centrally mounts the upper package using a second BGA and includes the lower stiffener disposed on an upper surface of the lower package substrate to surround the upper package substrate; and

a heat sink disposed on the upper package,

wherein the upper stiffener is a square-ring having a rectangular cross-section,

the lower stiffener includes a fence portion having a rectangular cross-section and a cover portion extending horizontally from an upper surface of the fence portion to contact an upper surface of the upper stiffener, and

the upper stiffener and the lower stiffener are laterally spaced apart.

12. The semiconductor package of claim 11 , wherein the heat sink thermally contacts an upper surface of the SoC.

13. The semiconductor package of claim 12 , wherein the heat sink includes one of:

a lower surface having flat structure thermally contacting the upper surface of the SoC, wherein an upper surface of the upper stiffener and an upper surface of the lower stiffener are separated from the lower surface of the heat sink;

a lower surface including a single-step, stepped-down center portion surrounded by an outer portion, wherein the stepped-down center portion thermally contacts the upper surface of the SoC, and the outer portion thermally contacts an upper surface of the lower stiffener; and

a lower surface including a two-step, stepped-down center portion surrounded by an outer portion and including a lower step portion and an upper step portion, wherein the lower step portion thermally contacts the upper surface of the SoC, the upper step portion thermally contacts an upper surface of the upper stiffener, and the outer portion thermally contacts an upper surface of the lower stiffener.

14. A semiconductor package comprising:

a dual stiffener including an upper stiffener and a lower stiffener;

an upper package including an upper package substrate, a semiconductor chip centrally mounted on an upper surface of the upper package substrate, and the upper stiffener disposed along an outer edge of the upper package substrate;

a lower package substrate that centrally mounts the upper package and includes the lower stiffener disposed on an upper surface of the lower package substrate to surround the upper package substrate; and

a heat sink disposed on the upper package and including a lower surface thermally contacting an upper surface of the semiconductor chip,

wherein the upper stiffener has a square-ring shape and a rectangular cross-section, and

the lower stiffener has a square-ring shape and includes a fence portion having a rectangular cross-section and a cover portion extending horizontally from an upper surface of the fence portion to contact an upper surface of the upper stiffener.

15. The semiconductor package of claim 14 , wherein the lower surface of the heat sink is flat, and

an upper surface of the upper stiffener and an upper surface of the lower stiffener are separated from the lower surface of the heat sink.

16. The semiconductor package of claim 14 , wherein the lower surface of the heat sink includes a single-step, stepped-down center portion surrounded by an outer portion, and

the stepped-down center portion thermally contacts the upper surface of the semiconductor chip.

17. The semiconductor package of claim 14 , wherein the lower surface of the heat sink includes a single-step, stepped-down center portion surrounded by an outer portion,

the stepped-down center portion thermally contacts the upper surface of the semiconductor chip, and

the outer portion thermally contacts an upper surface of the cover portion of the lower stiffener.

18. The semiconductor package of claim 14 , wherein the fence portion includes opposing ends, wherein each of the opposing ends is chamfered at a 45° angle, and

the cover portion has an angular shape extending horizontally inward from an outer edge of the fence portion.