Adhesive and thermal interface material on a plurality of dies covered by a lid

1. A package structure, comprising:

a first die and a second die group, disposed side by side on an interposer;

an underfill layer, disposed between the first die and the second die group;

an adhesive pattern, at least overlying the underfill layer between the first die and the second die group; and

a thermal interface material (TIM), having a bottom surface being in direct contact with the first die, the second die group, and the adhesive pattern, wherein the adhesive pattern separates the underfill layer from the TIM.

2. The package structure of claim 1 , wherein the second die group comprises at least one second die or a plurality of second dies, the plurality of second dies are respectively disposed at both sides of the first die, and the adhesive pattern comprises a plurality of adhesive layers discretely distributed on the underfill layer between the first die and the plurality of second dies.

3. The package structure of claim 2 , further comprising an encapsulant laterally encapsulating the first die, the plurality of second dies, and the underfill layer, wherein a portion of the plurality of adhesive layers is disposed between the encapsulant and the TIM to separate the encapsulant from the TIM.

4. The package structure of claim 3 , wherein a sidewall of the encapsulant is substantially aligned with a sidewall of the interposer.

5. The package structure of claim 2 , wherein each adhesive layer has a bottom surface being in direct contact with a top surface of a corresponding underfill layer.

6. The package structure of claim 2 , wherein one of the plurality of adhesive layers has a curved top surface, a flat bottom surface, and has a thickness decreasing along a direction from center to edge.

7. The package structure of claim 1 , wherein the adhesive pattern extends from a top surface of the underfill layer to cover a portion of a top surface of the first die and a portion of a top surface of the second die group.

8. The package structure of claim 1 , wherein the TIM has a plurality of fillers, and the adhesive pattern is free of fillers.

9. The package structure of claim 1 , further comprising:

a circuit substrate, bonded to the interposer;

a passive device, bonded to the circuit substrate; and

a lid, adhered to the circuit substrate, the first die, and the second die group, the lid covering and surrounding the passive device, the first die, and the second die group.

10. The package structure of claim 9 , wherein the TIM has a first concave top surface, the lid conformally covers the first concave top surface of the TIM, and the lid has a second concave top surface corresponding to the first concave top surface.

11. The package structure of claim 1 , wherein the TIM has an edge thickness greater than a center thickness of the TIM.

12. The package structure of claim 1 , wherein the TIM has a thermal conductivity greater than a thermal conductivity of the adhesive pattern.

13. A method of forming a package structure, comprising:

bonding a first die and a second die onto an interposer;

dispensing an underfill layer between the first die and the second die;

forming a first encapsulant to laterally encapsulate the first die, the second die, and the underfill layer;

forming an adhesive pattern on the underfill layer between the first die and the second die and on the first encapsulant; and

dispensing a thermal interface material (TIM) on the adhesive pattern, wherein a bottom surface of the TIM is in direct contact with a top surface of the first die, a top surface of the second die, and a top surface of the adhesive pattern.

14. The method of claim 13 , wherein the forming the adhesive pattern comprises: selectively dispensing on the underfill layer between the first die and the second die to form a plurality of adhesive layers discretely distributed to each other.

15. The method of claim 14 , wherein each adhesive layer has a bottom surface being in direct contact with a top surface of a corresponding portion of the underfill layer.

16. The method of claim 14 , wherein one of the plurality of adhesive layers has a curved top surface, a flat bottom surface, and has a thickness decreasing along a direction from center to edge.

17. The method of claim 13 , further comprising:

bonding the interposer onto a circuit substrate;

bonding a passive device onto the circuit substrate; and

adhering a lid onto the circuit substrate, wherein the lid covers and surrounds the passive device, the first die, and the second die.

18. A package structure, comprising:

a first die and a second die, disposed side by side on an interposer;

an underfill layer, disposed between the first die and the second die;

a composite structure, disposed on the first die, the second die, and the underfill layer, wherein the composite structure comprises:

a first metal layer having a bottom surface being in direct contact with the first die, the second die, and the underfill layer;

a second metal layer disposed on the first metal layer; and

a thermal interface material (TIM) sandwiched between the first metal layer and the second metal layer; and

a lid, adhered to the composite structure, the lid covering and surrounding the first die and the second die.

19. The package structure of claim 18 , wherein the second metal layer separates the TIM from the lid, so that the TIM is not in direct contact with the lid.

20. The package structure of claim 18 , further comprising an encapsulant laterally encapsulating the first die, the second die, and the underfill layer, wherein a sidewall of the encapsulant is substantially aligned with a sidewall of the interposer.