Granted Patent B2

US 9,059,144 · App. 13/403,458 · Granted Jun 16, 2015

Abstract

Claims (46)

1. A method for forming a molded die assembly, comprising:

attaching a first major surface of a semiconductor die onto a package substrate;

attaching a heat spreader to a second major surface of the semiconductor die, wherein

the second major surface is opposite the first major surface,

the heat spreader includes a pedestal portion that contacts the semiconductor die and side extensions that are raised above the pedestal and the semiconductor die when the heat spreader is mounted above the semiconductor die, and

the semiconductor die, package substrate, and heat spreader form a die assembly;

conforming a die release film to a transfer mold;

closing the transfer mold around the die assembly such that the die release film is compressed against the heat spreader and a cavity is formed around the die assembly;

transferring a thermoset material into the cavity; and

releasing the die assembly from the die release film and the transfer mold, wherein a top surface of the thermoset material is substantially flush with a majority of a top surface of the side extensions of the heat spreader.

2. The method of claim 1 , wherein attaching the heat spreader to the second major surface of the die comprises using a thermal interface material to attach the heat spreader to the second major surface.

3. The method of claim 1 , wherein the heat spreader has a laterally extending portion which extends laterally beyond the semiconductor die, wherein transferring the thermoset material into the cavity is performed such that the thermoset material is in direct physical contact with the laterally extending portion of the heat spreader.

4. The method of claim 3 , wherein transferring the thermoset material into the cavity is performed such that the thermoset material is in direct physical contact with a sidewall of the laterally extending portion of the heat spreader.

5. The method of claim 3 , wherein the laterally extending portion of the heat spreader comprises locking protrusions which extend from a sidewall of the laterally extending portion of the heat spreader, wherein the transferring the thermoset material into the cavity is performed such that the thermoset material surrounds the locking protrusions.

6. The method of claim 3 , wherein a periphery of the laterally extending portion of the heat spreader comprises a plurality of recessed regions, wherein the transferring the thermoset material into the cavity is performed such that the thermoset material fills the recessed regions.

7. The method of claim 3 , wherein the heat spreader comprises a plurality of protruding portions which extend from a major surface of the laterally extending portion of the heat spreader towards the package substrate, wherein the transferring the thermoset material into the cavity is performed such that the thermoset material surrounds the protruding portions.

8. The method of claim 1 , wherein attaching the first major surface of the semiconductor die onto the package substrate comprises forming electrically conductive bumps on the first major surface of the semiconductor substrate and attaching the bumps to the package substrate.

9. The method of claim 1 , further comprising:

after attaching the first major surface of the semiconductor die onto the package substrate, forming wire bond connections from the second major surface of the semiconductor die to the package substrate.

10. The method of claim 1 , wherein attaching the first major surface of the semiconductor die onto the package substrate is further characterized in that the package substrate comprises a lead frame.

11. The method of claim 1 , further comprising:

after releasing the die assembly from the die release film and the transfer mold, curing the molded die assembly.

12. A method for forming a molded die assembly, comprising:

attaching a first major surface of a semiconductor die onto a package substrate;

attaching a heat spreader to a second major surface of the semiconductor die using a thermal interface material, wherein the second major surface is opposite the first major surface, wherein

the semiconductor die, package substrate, thermal interface material, and heat spreader form a die assembly, and

the heat spreader comprises a pedestal portion and an extension portion, the extension portion extends laterally beyond the semiconductor die and is raised above the pedestal portion and the semiconductor die when the heat spreader is attached to the second major surface of the semiconductor die;

conforming a die release film to a transfer mold;

closing the transfer mold around the die assembly such that the die release film is compressed against the heat spreader and a cavity is formed around the die assembly;

transferring a thermoset material into the cavity such that the thermoset material is in direct physical contact with the extension portion of the heat spreader;

releasing the die assembly from the die release film and the transfer mold; and

after releasing the die assembly from the die release film and the transfer mold, curing the molded die assembly, wherein a top surface of the thermoset material is substantially flush with a top surface of the extension portion of the heat spreader and a top surface of the pedestal portion is flush with the to surface of the extension portion of the heat spreader.

13. The method of claim 12 , wherein transferring the thermoset material into the cavity is performed such that the thermoset material is in direct physical contact with a sidewall of the extension portion of the heat spreader.

14. The method of claim 13 , wherein the extension portion of the heat spreader comprises locking protrusions which extend from a sidewall of the extension portion of the heat spreader, wherein the transferring the thermoset material into the cavity is performed such that the thermoset material surrounds the locking protrusions.

15. The method of claim 13 , wherein a periphery of the extension portion of the heat spreader comprises a plurality of recessed regions, wherein the transferring the thermoset material into the cavity is performed such that the thermoset material fills the recessed regions.

16. The method of claim 13 , wherein the heat spreader comprises a plurality of protruding portions which extend from a major surface of the extension portion of the heat spreader towards the package substrate, wherein the transferring the thermoset material into the cavity is performed such that the thermoset material surrounds the protruding portions.

17. The method of claim 12 , wherein attaching the first major surface of the semiconductor die onto the package substrate comprises forming electrically conductive bumps on the first major surface of the semiconductor substrate and attaching the bumps to the package substrate.

18. The method of claim 12 , further comprising:

after attaching the first major surface of the semiconductor die onto the package substrate, forming wire bond connections from the second major surface of the semiconductor die to the package substrate.

19. The method of claim 12 , wherein attaching the first major surface of the semiconductor die onto the package substrate is further characterized in that the package substrate comprises a lead frame.

20. A molded die assembly, comprising:

a package substrate;

a semiconductor die over the package substrate;

a heat spreader over the semiconductor die, wherein the heat spreader includes a solid die attach region and a solid extension portion which extends laterally beyond the die attach region and the semiconductor die, wherein the heat spreader is mounted only to a top surface of the semiconductor die and a top surface of the die attach region and the semiconductor die are below the extension portion;

a thermal interface material between the heat spreader and semiconductor die, wherein the thermal interface material is in direct physical contact with the die attach region of the heat spreader and the semiconductor die; and

a thermoset material surrounding the semiconductor die and in direct physical contact with the package substrate, the extension portion of the heat spreader, and a sidewall of the extension portion of the heat spreader, wherein a top surface of the thermoset material is substantially flush with a majority of a top surface of the extension portion of the heat spreader.

Assignments (22)