System and method for high performance heat sink for multiple chip devices

• US 7,291,913 B2
• Filed: 09/30/2005
• Issued: 11/06/2007
• Est. Priority Date: 12/31/2003
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Edwards, Darvin R.
• Primary Examiner(s): Ho; Tu-Tu
• Application Number:
  US11/240,858
• Publication Number:
  US 20060060988A1
• Time in Patent Office: 767 Days
• Field of Search: 257/704
• US Class Current: 257/704
• CPC Class Codes: H01L 23/36 Selection of materials, or shaping, to facilitate cooling or heating, e.g. heatsinks H01L23/28, H01L23/40, H01L23/42, H01L23/44, H01L23/46 take precedence; heating H01L23/345
• 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 2924/15311 being a ball array, e.g. BGA
• CPC Class Codes: H01L 2924/16153 Cap enclosing a plurality of side-by-side cavities [e.g. E-shaped cap]

Abstract

A custom-molded heat sink corresponds to an individual substrate and includes a heat sink lid having at least one cavity corresponding to at least one die mounted on a substrate. A conductive layer is deposited in the at least one cavity that substantially fills the space between the at least one cavity and the at least one die when the lid is coupled to the substrate.

Claims

1. A method for removing heat from a semiconductor device on a substrate, comprising:

forming a lid having at least one cavity;

a first die of a first thickness and a second die of a second thickness different from the first thickness mounted on a substrate;

depositing a conductive material having a viscosity within the at least one cavity, the conductive material comprising a material having a thermal conductivity greater than 10 W/m-°

C.;

mating the lid to the substrate thereby placing the at least one cavity over the first die and the second die; and

heating the conductive material thereby reducing its viscosity and thereby forming a first layer of the conductive material having a third thickness between the first die and the lid and a second layer of the conductive material having a fourth thickness different from the third thickness between the second die and the lid;

cooling the conductive material thereby increasing the viscosity of the conductive layers, thereby retaining the thickness of the first conductive layer and the second conductive layer within the at least one cavity,

lifting the lid and the conductive layers from the dies and the substrate;

applying additional binding material between the lid and the dies and the substrate; and

mating the lid to the substrate, thereby securing the lid to the substrate.

2. The method of claim 1, wherein the conductive material comprises a metallic solder.

3. The method of claim 2, wherein the solder comprises eutectic Sn—

Pb solder.

4. The method of claim 2, wherein the solder has a melting point of less than 200°

C.

5. The method of claim 2, wherein the solder comprises an indium-based solder.

6. The method of claim 2, wherein the solder is lead-free.

7. The method of claim 1, wherein the conductive material is a conductive thermoplastic.

8. The method of claim 7, wherein the conductive thermoplastic is silver-filled.

9. The method of claim 1, wherein the at least one cavity comprises at least two cavities with similar dimensions.

10. The method of claim 1, wherein the semiconductor device is a multi-chip module.