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CN-121986604-A - Encapsulation of electronic devices with liquid thermal interface materials

CN121986604ACN 121986604 ACN121986604 ACN 121986604ACN-121986604-A

Abstract

An electronic device (11) includes (i) an Integrated Circuit (IC) die (22) mounted on a substrate (25), (ii) a lid (33) having first and second surfaces (32, 34) facing each other and one or more openings (66) formed through the lid between the first and second surfaces, the lid being disposed over the IC die to form a space (23) between the IC die and the first surface (32) of the lid, the one or more openings being configured to enable transfer of fluid through the lid, (iii) a liquid Thermal Interface Material (TIM) (44) filling the space and configured to conduct heat from the IC die to the lid, and (iv) a stop structure (54) extending from the first surface of the lid, the stop structure including a sidewall (55) configured to receive the liquid TIM at least in the space between the IC die and the first surface of the lid.

Inventors

  • J. PATEL
  • A. El Helu

Assignees

  • 马维尔亚洲私人有限公司

Dates

Publication Date
20260505
Application Date
20241001
Priority Date
20231004

Claims (20)

  1. 1. An electronic device, comprising: an Integrated Circuit (IC) die mounted on the substrate; a cover having first and second surfaces facing each other, and one or more openings formed through the cover between the first and second surfaces, the cover being disposed over at least the IC die to form a space between the IC die and the first surface of the cover, wherein the one or more openings are configured to enable fluid transfer through the cover; A liquid Thermal Interface Material (TIM) filling the space and configured to conduct heat from the IC die to the lid, and A stop structure extending from the first surface of the lid, the stop structure comprising one or more sidewalls configured to receive the liquid TIM at least in the space between the IC die and the first surface of the lid.
  2. 2. The electronic device of claim 1, wherein the one or more sidewalls of the stop structure comprise one or more protrusions of the cover configured to at least partially enclose the IC die.
  3. 3. The electronic device of claim 1, wherein the stop structure comprises a dam structure of material separate from the cap, the one or more sidewalls of the dam structure coupled to at least the first surface of the cap and configured to at least partially enclose the IC die.
  4. 4. The electronic device of claim 3, wherein the material of the dam structure comprises an adhesive material.
  5. 5. The electronic device of any of claims 1-3, comprising a fill material disposed on the substrate at an edge of the IC die, wherein at least one of the sidewalls is disposed (i) between the first surface of the cover and the fill material, and (ii) outside a region of the IC die.
  6. 6. The electronic device of claim 5, wherein at least one of the openings is formed along an axis between at least one of the sidewalls and the edge of the IC die.
  7. 7. The electronic device of any one of claims 1-3, wherein the cover has a first opening configured as a first conduit for inserting the liquid TIM into the space and a second opening configured as a second conduit through which gas may flow out of the space.
  8. 8. The electronic device of any one of claims 1-3, wherein the cover has a single opening configured as a conduit for (i) inserting the liquid TIM into the space, and (ii) flowing the gas out of the space.
  9. 9. The electronic device of any of claims 1-3, comprising a seal disposed at least on the second surface of the cover, the seal comprising at least an adhesive layer configured to at least partially cover one of the openings to block the liquid TIM from escaping from the one of the openings.
  10. 10. The electronic device of any one of claims 1-3, comprising one or more plug seals disposed at least partially in the one or more openings, respectively, the one or more plug seals configured to block overflow of the liquid TIM from the one or more openings.
  11. 11. A method for fabricating an electronic device, the method comprising: mounting an Integrated Circuit (IC) die on a substrate; disposing a cover over at least the IC die, the cover having first and second surfaces facing each other, and one or more openings formed through the cover between the first and second surfaces for fluid transfer therethrough, the cover being disposed over at least the IC die to form a space between the IC die and the first surface of the cover; filling the space with a liquid Thermal Interface Material (TIM) configured to conduct heat from the IC die to the lid, and A stop structure is formed extending from the first surface of the cap, the stop structure including one or more sidewalls for accommodating the liquid TIM at least in the space between the IC die and the first surface of the cap.
  12. 12. The method of claim 11, wherein forming the one or more sidewalls of the stop structure comprises forming one or more protrusions of the cap at least partially surrounding the IC die.
  13. 13. The method of claim 11, wherein forming the stop structure comprises forming a dam structure of material separate from the cap and coupling the one or more sidewalls of the dam structure at least partially surrounding the IC die to at least the first surface of the cap.
  14. 14. The method of claim 13, wherein forming the dam structure comprises dispensing an adhesive material on the first surface of the cap.
  15. 15. The method of any of claims 11-13, comprising disposing a fill material on the substrate at an edge of the IC die, wherein forming the sidewalls includes at least one of (i) disposing the sidewalls between the first surface of the cover and the fill material, and (ii) outside a region of the IC die.
  16. 16. The method of claim 15, wherein forming the one or more openings comprises forming at least one of the openings along an axis between at least one of the sidewalls and the edge of the IC die.
  17. 17. The method according to any one of claims 11-13, wherein forming the one or more openings comprises forming a first opening in the lid for inserting the liquid TIM into the space and a second opening for flowing the gas out of the space.
  18. 18. The method according to any one of claims 11-13, wherein forming the opening comprises forming a single opening in the lid for (i) inserting the liquid TIM into the space, and (ii) flowing the gas out of the space.
  19. 19. A method according to any one of claims 11 to 13, comprising providing a seal on at least the second surface of the cover, the seal comprising at least an adhesive layer for at least partially covering one of the openings to block overflow of the liquid TIM from the one of the openings.
  20. 20. The method according to any one of claims 11-13, wherein disposing the seal comprises disposing one or more plug seals at least partially in the one or more openings, respectively, for blocking overflow of the liquid TIM from the one or more openings.

Description

Encapsulation of electronic devices with liquid thermal interface materials Cross Reference to Related Applications The present application claims the benefit of U.S. provisional patent application 63/542,493 filed on 4 th 10 th 2023, the disclosure of which is incorporated herein by reference. Technical Field The present invention relates generally to packaging of electronic devices, and in particular to methods and systems for improving heat dissipation from packages of one or more Integrated Circuit (IC) dies. Background Some electronic devices include one or more IC dies mounted on a substrate and packaged with a lid. Each of the IC dies typically includes a front side having an active surface (with integrated circuits) and a back side opposite the front side. For example, in a Flip Chip (FC) package, the front side faces the substrate and the back side faces the cover. Such IC die generate heat during operation and therefore require heat dissipation, which is typically performed through the back side and the lid of the IC die. To improve heat dissipation, a Thermal Interface Material (TIM) is typically disposed in the space between the lid and the back side of the IC die. Some TIMs are based on and selected from polymers, graphite, indium solder alloys, and carbon nanotubes, but such TIMs may dissipate heat at insufficiently high rates and/or the cost of such TIMs may exceed the budget of the TIMs in FC packages. TIMs based on liquid metals can provide improved thermal performance at reduced cost, but can be difficult to achieve in FC packages due to low viscosity and melting points below room temperature. These properties of the liquid metal TIM may cause the liquid metal TIM to leak from the space between the IC die and the lid and form bubbles between the lid and the IC die, thereby reducing the heat dissipation rate in the FC package. The above description is presented as a general overview of the relevant art in this field and should not be construed as an admission that any of the information it contains constitutes prior art against the present patent application. Disclosure of Invention Embodiments of the invention described herein provide an electronic device comprising (i) an Integrated Circuit (IC) die mounted on a substrate, (ii) a cap having first and second surfaces facing each other and one or more openings formed through the cap between the first and second surfaces, the cap being disposed over at least the IC die to form a space between the IC die and the first surface of the cap, the one or more openings being configured to enable transfer of fluid through the cap, (iii) a liquid Thermal Interface Material (TIM) filling the space and configured to conduct heat from the IC die to the cap, and (iv) a stop structure extending from the first surface of the cap, the stop structure comprising one or more sidewalls configured to receive a liquid TIM at least in the space between the IC die and the first surface of the cap. In some embodiments, the one or more sidewalls of the stop structure include one or more protrusions of the cover configured to at least partially enclose the IC die. In other embodiments, the stop structure comprises a dam structure of material separate from the cap, one or more sidewalls of the dam structure coupled to at least the first surface of the cap and configured to at least partially enclose the IC die. In other embodiments, the material of the dam structure includes an adhesive material. In some embodiments, the electronic device includes a fill material disposed at an edge of the IC die on the substrate, at least one of the sidewalls being disposed between (i) the first surface of the cap and the fill material, and (ii) outside an area of the IC die. In other embodiments, at least one of the openings is formed along an axis between at least one of the sidewalls and an edge of the IC die. In other embodiments, the cap has a first opening configured as a first conduit for inserting the liquid TIM into the space and a second opening configured as a second conduit through which gas may flow out of the space. For some embodiments, the lid has a single opening configured for (i) inserting the liquid TIM into the space, and (ii) a conduit for flowing gas out of the space. In other embodiments, the electronic device includes a seal disposed at least on the second surface of the cover, the seal including at least an adhesive layer configured to at least partially cover one of the openings to block the liquid TIM from escaping from the one of the openings. In other embodiments, the electronic device includes one or more plug seals disposed at least partially in the one or more openings, respectively, the one or more plug seals configured to block the liquid TIM from escaping from the one or more openings. There is additionally provided, in accordance with an embodiment of the present invention, a method for fabricating an electronic device, the method including mounting