Method and device for heat dissipation in an electronics system

• US 6,392,890 B1
• Filed: 12/20/2000
• Issued: 05/21/2002
• Est. Priority Date: 12/20/2000
• Status: Expired due to Term

• Current Assignee: Ciena Corporation
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Katchmar, Roman M.
• Primary Examiner(s): TOLIN, GERALD P
• Application Number:
  US09/739,688
• Time in Patent Office: 517 Days
• Field of Search: 174/252, 174/16.3, 257/705, 257/706, 257/713, 257/717, 257/718, 361/704, 361/705, 361/707, 361/712, 361/717-719, 165/80.3, 165/185, 156/247, 156/306.6, 156/324.4, 428/40.5, 428/41.3, 428/41.8, 428/220
• US Class Current: 361/705
• CPC Class Codes: H05K 7/20463 Filling compound, e.g. potted resin
• CPC Class Codes: H05K 7/20509 Multiple-component heat spreaders; Multi-component heat-conducting support plates; Multi-component non-closed heat-conducting structures
• CPC Class Codes: Y10T 428/1419 Wax containing

Abstract

The invention relates to a method and a device for creating a thermally conductive path between a component of a printed circuit board and a heat sink using a electrical insulator material and a thermally conductive material. The electrical insulator material is adhesive, to assist in adhering surfaces against which it is applied. Typically, the circuit board is affixed to the heat sink, creating a gap between the component and the heat sink. The electrical insulator material is applied in the gap. Then, the thermally conductive material is applied within the electrical insulator material, causing the thermally conductive material to spread beyond the perimeter of the electrical insulator material. The electrical insulator material thus confines the thermally conductive material within the gap in thermally conductive contact between the electronic component and the heat sink.

Claims

1. An electronics system comprising a heat sink structure and a printed circuit board structure, the printed circuit board structure comprising a printed circuit board with at least one electronic component mounted upon a first side of the printed circuit board, the heat sink structure and the circuit board structure being affixed to each other wherein the electronic component is in a spaced relationship from the heat sink structure, the electronics system further comprising a means for creating a thermally conductive path from the heat sink structure to the electronic component wherein the means for creating a thermally conductive path comprises a good thermally conductive, electrically conductive material and an electrical insulator material wherein both of the good thermally conductive, electrically conductive material and the electrical insulator material are between the electronic component and the heat sink structure and the good thermally conductive, electrically conductive material is in direct contact with both a surface of the electronic component and a surface of the heat sink structure, and the good thermally conductive, electrically conductive material is confined and contained between the electronic component and the heat sink structure by the electrical insulator material.

2. The electronics system of claim 1 wherein the heat sink structure comprises one or more holes defined through the heat sink structure, each hole having its axis extending in a direction generally towards an electronic component.

3. The electronics system of claim 2 wherein each of the one or more holes comprises additional electrical insulator material.

4. The electronics system of claim 1 wherein the electrical insulator material is adhesive, to assist in adhering surfaces against which it is applied and to assist in confining the good thermally conductive, electrically conductive material within a volume in the thermally conductive contact between the electronic component and the heat sink structure.

5. The electronics system of claim 1 wherein the electrical insulator material does not extend beyond the periphery of the electronic component.

6. The electronics system of claim 1 wherein the ratio of the electrical insulator material to the good thermally conductive, electrically conductive material is approximately seven to three.

7. The electronics system of claim 1 wherein the good thermally conductive, electrically conductive material has an ability to flow at processing temperatures.

8. The electronics system of claim 1 wherein the electrical insulator material is initially a paste at processing temperatures and cures at room temperature to form a compliant seal having mechanical integrity.

9. The electronics system of claim 1 wherein the good thermally conductive, electrically conductive material is selected from one of gallium, mercury and woods metal.

10. The method of claim 9 wherein the good thermally conductive, electrically conductive material further comprises one of a powder or a fibre filler selected from a refractory material, a metal and an element or compound of Group IV of the Periodic Table.

11. The method of claim 1 wherein the good thermally conductive, electrically conductive material comprises gallium in combination with one of both metals selected from tin and indium.

12. The electronics system of claim 1 wherein the electrical insulator material is selected from one of silicone rubber, silicone gel, fluoro silicone rubber, acrylates and epoxy.

13. The electronics system of claim 1 wherein the heat sink structure comprises a heat sink and a means for separating the electrical insulator material and the good thermally conductive, electrically conductive material from the heat sink.

14. The electronics system of claim 1 wherein at least one of the heat sink structure and the electronic component comprises a barrier for protection from the good thermally conductive, electrically conductive material.

15. The electronics system of claim 14 wherein the barrier comprises tin plated over nickel.

16. The electronics system of claim 14 wherein the barrier comprises ceramic alumina.