Apparatus and Methods for Cooling Semiconductor Integrated Circuit Package Structures

• US 20080242002A1
• Filed: 05/05/2008
• Published: 10/02/2008
• Est. Priority Date: 11/19/2004
• Status: Active Grant

• Current Assignee: Deborah Anne Sylvester, Evan George Colgan, Gary Goth, Jeffrey Allen Zitz
• Original Assignee: Deborah Anne Sylvester, Evan George Colgan, Gary Goth, Jeffrey Allen Zitz
• Inventors: Colgan, Evan George, Goth, Gary, Zitz, Jeffrey Allen, Sylvester, Deborah Anne
• Granted Patent: US 7,803,664 B2
• Time in Patent Office: Days
• US Class Current: 438/118
• CPC Class Codes: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• CPC Class Codes: H01L 2224/32057 in side view
• CPC Class Codes: H01L 2224/73253 Bump and layer connectors
• CPC Class Codes: H01L 2224/83385 Shape, e.g. interlocking features
• CPC Class Codes: H01L 23/42 Fillings or auxiliary members in containers or encapsulations selected or arranged to facilitate heating or cooling
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00011 Not relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01019 Potassium [K]
• CPC Class Codes: H01L 2924/10253 Silicon [Si]
• CPC Class Codes: H01L 2924/15311 being a ball array, e.g. BGA
• CPC Class Codes: H01L 2924/16152 Cap comprising a cavity for hosting the device, e.g. U-shaped cap

Abstract

The present invention relates generally to apparatus and methods for cooling semiconductor integrated circuit (IC) chip package structures. More specifically, the present invention relates to apparatus and methods for thermally coupling semiconductor chips to a heat conducting device (e.g., copper thermal hat or lid) using a compliant thermally conductive material (e.g., thermal paste), wherein a thermal interface is designed to prevent/inhibit the formation of voids in the compliant thermally conductive material due to the flow of such material in and out from between the chips and the heat conducting device due to thermal cycling.

Claims

1. A method for packaging an IC (integrated circuit) chip, comprising the steps of:

forming one or more channels in a thermal contact surface of a heat conducting device;

forming a thermal interface between the thermal contact surface of the heat conducting device and a non-active surface of an IC chip, the thermal interface comprising a layer of compliant thermally conductive material; and

preventing compliant thermally conductive material from filling the one or more channels when forming the thermal interface.

2. The method of claim 1, wherein preventing compliant thermally conductive materiel from filling the one or more channels when forming the thermal interface comprises:

contacting the thermal contact surface to the chip surface with compliant thermally conductive material therebetween; and

obstructing the one or more channels formed in the thermal contact surface to prevent complaint thermally conductive material from filling the one or more channels when contacting the thermal contact surface to the chip surface.

3. The method of claim 2, wherein obstructing the one or more channels comprises:

placing an object in each of the one or more channels; and

removing the objects from the one or more channels after contacting the thermal contact surface to the chip surface.

4. The method of claim 3, wherein the objects comprise rigid rods.

5. The method of claim 3, wherein the objects comprise flexible objects.

6. The method of claim 3, further comprising forming one or more openings through the heat conducting device, and wherein removing the objects from the one or more channels comprises removing the objects through the one or more openings.

7. The method of claim 6, further comprising sealing the one or more openings after removing the objects.

8. The method of claim 3, wherein the object comprise a meltable material or a dissolvable material.

9. The method of claim 8, wherein the meltable material comprises a wax material.

10. The method of claim 8, further comprising:

forming one or more openings through the heat conducting device, and

wherein removing the objects from the one or more channels comprises;

melting the meltable material to enable melted material to flow out from the one or more channels through the one or more openings;

or

dissolving the dissolvable material to enable dissolved material to

flow out from the one or more channels through the one or more openings.

11. The method of claim 8, further comprising:

forming one or more flow channels in the heat conducting device, and

wherein removing the objects from the one or more channels of the thermal contact surface comprises melting the meltable material to enable melted material to flow out from the one or more channels into the one or more flow channels.

12. The method of claim 11, wherein forming one or more flow channels comprises forming at least one opening into the heat conducting device from each of the one or more channels.

13. The method of claim 6, wherein forming a thermal interface between the thermal contact surface of the heat conducting device and a surface of an IC chip, comprises:

bonding the heat conducting device to a carrier substrate on which the IC chip is mounted such that the thermal contact surface and the surface of the IC chip are spaced apart at a fixed distance and in thermal contact through the compliant thermally conductive material.

14. The method of claim 13, wherein forming a thermal interface between the thermal contact surface of the heat conducting device and a surface of an IC chip, comprises dispensing an excess amount of the thermally conductive compliant material onto the thermal contact surface, or onto the non-active surface of the chip mounted to the carrier substrate, and wherein bonding the heat conducting device to the carrier substrate comprises:

applying a bead of an adhesive sealant onto an bonding surface of the heat conducting device or a corresponding bonding surface of the package substrate; and

contacting heat conducting device to the package substrate with a compression force to squeeze the bead of adhesive sealant and the excess thermally conductive compliant material to a desired adhesive sealant layer thickness and a thermally conductive compliant material layer thickness.

15. The method of claim 14, wherein the thickness of the adhesive sealant layer is about 0.5 mils and wherein the thickness of the thermally conductive compliant material layer is about 3 mils to about 4 mils thick.

16. The method of claim 14, further comprising:

curing the adhesive sealant layer;

removing the objects through the one or more openings of the heat conducting device after the adhesive sealant layer is cured; and

sealing the one or more openings of the heat conducting device using additional adhesive sealant.

17. The method of claim 16, wherein sealing the one or more openings of the heat conducting device using additional adhesive sealant comprises applying a slight compression force to the assembly when dispensing the additional adhesive sealant to draw the additional adhesive sealant into the one or more opening when the slight compression force stopped.

18. The method of claim 1, wherein the one or more channels are formed in the thermal contact surface of a heat conducting device such that the one or more channels are not aligned with a hot spot region of the IC chip.