Package unit, printed board having the same, and electronic apparatus having the printed board

1. A package unit to be mounted on an external printed board, said package unit comprising: a package board mounted with an exoergic circuit element; a heat spreader that transmits heat from the exoergic circuit element to a heat sink that radiates the heat, said heat spreader including a first member and a second member divided from the first member; a joining member connected to the first member, forming a seal between the exoergic circuit element and said first member, and forming a sealed space in cooperation with the exoergic circuit element and said heat spreader; and a liquid metal in the sealed space, the sealed space extending between the first member and the second member, a portion of the first member contacting the liquid metal serving as a flat spring.

2. The package unit according to claim 1 , wherein said joining member connects the exoergic circuit element to said heat spreader along an outer circumference of the exoergic element.

3. The package unit according to claim 1 , wherein said second member has a convex section facing the exoergic circuit element.

4. The package unit according to claim 1 , wherein the part of the first member has a thickness between 200 μm and 1 mm.

5. The package unit according to claim 1 , wherein said joining member is adhesive agent or solid metal.

6. The package unit according to claim 1 , further comprising a permission part that permits thermal expansion of the liquid metal.

7. The package unit according to claim 6 , wherein the permission part is air sealed in the sealed space.

8. The package unit according to claim 7 , wherein the permission part is inert gas that is selected among nitrogen, argon, and helium.

9. The package unit according to claim 6 , wherein the permission part is an elastic member provided in the sealed space.

10. The package unit according to claim 1 , wherein said heat spreader has a convexoconcave shape on a surface that forms the sealed space.

11. The package unit according to claim 1 , wherein said heat spreader is elastic.

12. The package unit according to claim 1 , wherein said package board is mounted with plural exoergic circuit elements.

13. The package unit according to claim 1 , wherein said package board is made of resin.

14. A printed board comprising a package unit mounted on said printed board, said package unit comprising: a package board mounted with an exoergic circuit element; a heat spreader that transmits heat from the exoergic circuit element to a heat sink that radiates the heat, said heat spreader including a first member and a second member divided from the first member; a joining member connected to the first member, forming a seal between the exoergic circuit element and said first member, and forming a sealed space in cooperation with the exoergic circuit element and said heat spreader; and a liquid metal in the sealed space, the sealed space extending between the first member and the second member, a portion of the first member contacting the liquid metal serving as a flat spring.

15. An electronic apparatus comprising a printed board mounted with a package unit, said package unit comprising: a package board mounted with an exoergic circuit element; a heat spreader that transmits heat from the exoergic circuit element to a heat sink that radiates the heat, said heat spreader including a first member and a second member divided from the first member; a joining member connected to the first member, forming a seal between the exoergic circuit element and said first member, and forming a sealed space in cooperation with the exoergic circuit element and said heat spreader; and a liquid metal in the sealed space, the sealed space extending between the first member and the second member, a portion of the first member contacting the liquid metal serving as a flat spring.

16. A package unit to be mounted on an external printed board, said package unit comprising:

a package board mounted with an exoergic circuit element;

a heat spreader that transmits heat from the exoergic circuit element to a heat sink that radiates the heat, said heat spreader including a first member and a second member divided from the first member;

a joining member connected to the first member, forming a seal between the exoergic circuit element and said first member, and forming a sealed space in cooperation with the exoergic circuit element and said heat spreader; and

a liquid metal in the sealed space, the sealed space extending between the first member and the second member, a portion of the first member contacting the liquid metal being flexible.

17. A package unit to be mounted on an external printed board, said package unit comprising: a package board mounted with an exoergic circuit element; a heat spreader that transmits heat from the exoergic circuit element to a heat sink that radiates the heat, said heat spreader including a first member and a second member divided from the first member and having a convex section facing the exoergic circuit element, the second member having a notch in the convex section, permitting a thermal expansion of a liquid metal; a joining member that is connected to the first member, forming a seal between the exoergic circuit element and said first member, and forming a sealed space in cooperation with the exoergic circuit element and said heat spreader; and the liquid metal sealed in the sealed space.

18. A printed board comprising a package unit mounted on said printed board, said package unit comprising: a package board mounted with an exoergic circuit element; a heat spreader that transmits heat from the exoergic circuit element to a heat sink that radiates the heat, said heat spreader including a first member and a second member divided from the first member and having a convex section facing the exoergic circuit element, the second member having a notch in the convex section, permitting thermal expansion of a liquid metal; a joining member that is connected to the first member, forming a seal between the exoergic circuit element and said first member, and forming a sealed space in cooperation with the exoergic circuit element and said heat spreader; and the liquid metal sealed in the sealed space.

19. An electronic apparatus comprising a printed board mounted with a package unit, said package unit comprising: a package board mounted with an exoergic circuit element; a heat spreader that transmits heat from the exoergic circuit element to a heat sink that radiates the heat, said heat spreader including a first member and a second member divided from the first member and having a convex section facing the exoergic circuit element, the second member having a notch in the convex section, permitting thermal expansion of a liquid metal; a joining member that is connected to the first member, forming a seal between the exoergic circuit element and said first member, and forming a sealed space in cooperation with the exoergic circuit element and said heat spreader; and the liquid metal sealed in the sealed space.