Patent ID: 12241689

DETAILED DESCRIPTION

A heat transfer element or a heat sink can transfer heat generated by an electrical component (e.g., an integrated device die, a passive component such as an inductor, a resistor, and a capacitor, etc.) to the outside environs, thereby maintaining a temperature of the electrical component within a desired temperature range during operation of the electrical component. The heat transfer element can include a phase change material that changes phase (e.g., liquid to vapor or solid to liquid) in response to a difference(s) in temperature. The phase change material can provide relatively high heat transfer efficiency as compared to traditional heat sink devices.

Various embodiments disclosed herein relate to a heat transfer element. The heat transfer element can be thermally coupled to an element (e.g., an electrical component). The heat transfer element can spread heat generated by the electrical component. The heat transfer element and the electrical component can be bonded to define a bonded structure. The heat transfer element and the electrical component can be directly contacted to one another to provide an efficient thermal dissipation pathway for heat generated by the electrical component.

A heat transfer element according to various embodiments disclosed herein can include a chamber defined by a housing, and a phase change material disposed in the chamber. The heat transfer element can be coupled to an element by way of a metal bonding structure. The metal bonding structure can provide a direct contact bond between the heat transfer element and the element.

FIG.1Ais a schematic side cross-sectional view of a heat transfer element1according to one embodiment. The heat transfer element1can comprise a housing10and a chamber12that is at least partially defined by the housing10. The housing10can comprise a metal portion14, an upper portion16and a lower portion18that mates or connects to the upper portion16. In some embodiments, the housing10can provide a complete seal around the chamber12from the outside environs. In some embodiments, the chamber12can be in a vacuum or a near vacuum condition. The heat transfer element1can also include a phase change material20disposed in the chamber12.

The metal portion14of the housing10can comprise any suitable metal. For example, the metal portion14can include a reactive metal that reacts to an application of energy (e.g., electrical energy or thermal energy). As illustrated inFIG.1A, the metal portion14can comprise a stack of multiple metal layers, in some embodiments. For example, the stack can include a plurality of aluminum (Al) layers14aand a plurality of nickel (Ni) layers14bthat are alternatingly stacked. In such embodiments, electrical current can be applied to the stack to react Al and Ni in the stack. After such a reaction, the metal portion14can define an aluminum-nickel (AlNi) alloy (see, for example,FIG.1B). The metal portion after the reaction has occurred can be referred to as a metal bonding structure.

Each layer of the Al layers14aand/or the Ni layers14bcan have a thickness of less than 20 nm, in some embodiments. For example the thickness of a layer of the metal stack can be in a range of 1 nm to 20 nm, in a range of 5 nm to 20 nm, or in a range of 5 nm to 15 nm. The stack of metal layers can have a thickness of less than 50 μm, in some embodiments. For example the thickness of the stack of metal layers can be in a range of 1 μm to 50 μm, in a range of 5 μm to 50 μm, in a range of 5 μm to 20 μm, or in a range of 20 μm to 50 μm.

In some embodiments, the metal portion14can define a bottom surface of the housing10. In some embodiments, the metal portion14can cover more than fifty-percent (50%) of the bottom surface of the housing. For example, the metal portion14can cover the entirety of the bottom surface of the housing10.

The upper portion16and the lower portion18of the housing10can comprise any suitable material. In some embodiments, the upper portion16and the lower portion18can comprise a nonconductive material, for example, a non-metallic material. For example, the upper portion16and the lower portion18can comprise silicon (Si). Using silicon for the upper portion16and the lower portion18can be beneficial. For example, silicon can provide relatively high thermal conductivity for the housing10. Also, semiconductor wafer fabrication processes can be utilized to manufacture the upper portion16and the lower portion18, thereby enabling relatively precise formation of the chamber12in the housing10.

The upper portion16of the housing can comprise a base16aand wall16bthat extends from the base16a. As shown, the base16aand wall16bcan cooperate to at least partially define a cavity. In some embodiments, the wall16bof the upper portion16and the lower portion18can be bonded together by way of an adhesive, (e.g., hermetic adhesive). In some other embodiments, the upper portion16and the lower portion18can be bonded to each other in any other suitable manner.

The upper portion16and the lower portion18can at least partially define a frame of the housing10. The frame can have a first side (a lower side) and a second side (an upper side) opposite the first side. In some embodiments, the upper side of the frame can define an upper side of the housing10. The lower side of the frame can be in contact with the metal portion14.

In some embodiments, the housing10can include a charge or inlet port (not illustrated) for providing the phase change material20into the chamber12. For example, the upper portion16can comprise a seal, a plug, or a cap that seals the charge port. In some embodiments, the phase change material20can be in a liquid form when provided into the chamber12. In such embodiments, the phase change material20can be, for example, injected into the chamber. In some other embodiments, the phase change material20can be in a solid form or in a vapor form. The phase change material20in the liquid form can change its phase to a solid form and/or a vapor form. The phase change material20in the solid form can change its phase to a liquid form and/or a vapor form. The phase change material20in the vapor form can change its phase to a solid form and/or a liquid form.

The phase change material20can comprise any suitable phase change material that can transfer heat. In some embodiments, the phase change material20can comprise water, methyl alcohol, ammonia, glycerin, etc.

In some embodiments, as illustrated inFIG.1A, the metal portion14can be exposed to the chamber12and in contact with the phase change material20. By having the metal portion14and the phase change material20in contact, a heat transfer performance between the metal portion14and the phase change material20can be relatively high as compared to a structure with an intervening layer between the metal portion14and the phase change material20.

FIG.1Bis a schematic side cross-sectional view of a bonded structure2that includes the heat transfer element1ofFIG.1A, according to one embodiment. The bonded structure2can include the heat transfer element1and an element (e.g., an electrical component22). The heat transfer element1and the electrical component22are coupled by way of a metal bonding structure14′.

The metal bonding structure14′ can comprise the metal portion14illustrated inFIG.1A. The metal bonding structure14′ can also comprise a metal layer of the electrical component22. In some embodiments, the metal portion14and the metal layer of the electrical component22can be directly contacted to at least partially define the metal bonding structure14′. In some embodiments, the metal bonding structure14′ can comprise a metal alloy (e.g., an aluminum-nickel (AlNi) alloy).

In some embodiments, the metal portion14and the metal layer of the electrical component22can react to form the metal bonding structure14′, thereby bonding the heat transfer element1and the electrical component22. In some embodiments, after stacking the heat transfer element1and the electrical component22, energy (e.g., heat or electrical current) can be applied to the metal portion14. In some embodiments, for example, an electric potential can be applied to the metal portion14to bond the heat transfer element1and the electrical component22. For example, in other embodiments, the metal portion14can be exposed to a temperature in a range of about 200° C. to 300° C. The heat can be applied to the metal portion14, rather than heating the entire bonded structure. This can mitigate or prevent the electrical component22from being excessively heated. In some embodiments, when the energy (e.g., electrical or thermal energy) is being applied, pressure can be applied to further enhance the bonding between the heat transfer element1and the electrical component22.

The element (illustrated inFIG.1Bas the electrical component22) can comprise any suitable electrical and/or non-electrical element. For example, the element can comprise an integrated device die, a passive component such as an inductor, a resistor, or capacitor, or a heat sink. In some applications, the bonded structure2can be coupled to a substrate or a device (not illustrated). For example, the bonded structure2can be mounted to a printed circuit board (PCB).

In some embodiments, heat transfer element1can configure to maintain a temperature of the electrical component22below a desired operating temperature. The phase change material20disposed in the chamber12can transfer or spread heat from the electrical component22. The phase change material20can be highly thermally conductive. For example, the thermal conductivity of the phase change material20can be greater than the thermal conductivity of the electrical component22. In some embodiments, heat generated by the electrical component22can conduct through the metal bonding structure14′ to the phase change material20. The phase change material20can transfer or spread the heat in various directions, thereby mitigating or preventing the electrical component22from overheat.

FIG.2is a schematic side cross-sectional view of a heat transfer element1′ according to another embodiment. The heat transfer element1′ is generally similar to the heat transfer element1illustrated inFIG.1A. Unless otherwise noted, components ofFIG.2may refer to components that are the same as or generally similar to like components ofFIGS.1A and1B. Unlike the upper portion16of the housing10, the upper portion16′ of the housing10′ does not include the wall16b. Rather, the upper portion16comprises a planar lid that can be bonded to the lower portion18to define the chamber12.

FIG.3Ais a schematic side cross-sectional view of a heat transfer element3according to another embodiment.FIG.3Bis a schematic side cross-sectional view of a bonded structure4that includes the heat transfer element3ofFIG.3A. The heat transfer element3may be generally similar to the heat transfer element1illustrated inFIG.1A. Unless otherwise noted, components ofFIGS.3A and3Bmay refer to components that are the same as or generally similar to like components ofFIGS.1A and1B.

The heat transfer element3can include a housing30that comprises an upper portion36and a lower portion38, and a metal portion14. The housing30and the metal portion14can at least partially define a chamber32. The heat transfer element3can also include a phase change material20disposed in the chamber32.

Unlike the housing10of the heat transfer element10, the housing30of the heat transfer element3includes an electrical pathway (e.g., a filled via40). The filled via40can comprise a conductive material (e.g., copper, aluminum, gold, etc.) disposed in a via formed vertically through the housing10, e.g., through the upper and lower portions36,38. The conductive material can comprise any electrically and/or thermally conductive material. The filled via40can extend from an upper side of the housing30to a lower side of the housing30. The filled via40can contact the metal portion14at the lower side of the housing30. The filled via40can comprise a through silicon via (TSV) filled with a conductive material, in some embodiments. The filled via40can be electrically coupled to the metal portion14such that the filled via40provides an electrical pathway between the upper side of the housing30and the metal portion14.

InFIG.3B, the bonded structure4can include an element (e.g., an electrical component22) that is coupled to the heat transfer element3. The bonded structure4and the heat transfer element3can be bonded by way of the metal bonding structure14′. In some embodiments, after contacting the metal portion14with the electrical component22, the metal portion14can be reacted, for example, by way of application of electrical current, thereby bonding the heat transfer element3and the electrical component22. After the reaction, the metal portion14can form the metal bonding structure14′ which can comprise an alloy of different metals. The electrical current can be applied through the via40, for example, at the upper surface of the housing30.

FIGS.4A-4Dshow side cross-sectional views of a bonded structure during a process of manufacturing an example bonded structure according to one embodiment.FIG.4Ais a side cross sectional view of a portion of a wafer42and a metal structure (e.g., the metal portion14). The wafer42has an upper side42aand a lower side42bopposite the upper side42a. The metal portion14can be formed at the lower side42b. In some embodiments, the wafer42can comprise a semiconductor wafer, such as a silicon wafer.

As explained above, the metal portion14can include a reactive metal that reacts to an application of energy (e.g., electrical energy or thermal energy). In some embodiments, the metal portion14can have a plurality of metal layers/films. For example, the metal portion14can include a plurality of aluminum (Al) layers14aand a plurality of nickel (Ni) layers14bthat are alternately stacked.

At least a portion of the wafer42ofFIG.4Acan be removed by a removing process to define a cavity44illustrated inFIG.4B. As illustrated inFIG.4B, the cavity44can be defined at least in part by the metal portion14at a floor of the cavity44and portions42′ of the wafer that have not been removed. In some embodiments, an entire thickness of a portion of the wafer42can be removed to expose at least a portion of the metal portion14.

FIG.4Billustrates a portion of the wafer42illustrated inFIG.4A. In some embodiments, numerous heat transfer elements (e.g., one hundred-fifty to three hundred in various embodiments heat transfer elements) can be manufactured from one wafer. Skilled artisans will appreciate that any suitable number of heat transfer elements may be formed from the wafer42. Therefore, a plurality of cavities can be formed in the wafer42.

The removing process can include any suitable process. For example, at least a portion of the wafer42can be removed from the upper side42aof the wafer42. In some embodiments, at least a portion of the wafer42can be removed by way of, for example, etching (e.g., wet etching or dry etching), or drilling (e.g., laser drilling). In some embodiments, an etchant can be selected based on the property of the metal portion14, which can serve as an etch stop in some embodiments.

FIG.4Cshows a side cross-sectional view of the heat transfer element1before dicing. After the removing process, another wafer (e.g., which includes the upper portion16) with another cavity is provided and coupled to the structure (e.g., the lower portion18) formed inFIG.4B, thereby defining a housing10. In some embodiments, the upper portion16and the lower portion18can be bonded by way of an adhesive (e.g., a hermetic adhesive). The upper portion16and the lower portion18can be bonded in various suitable manners. A chamber12can be defined at least in part by the housing10(e.g., the metal portion14, the upper portion16, and a lower portion18). In some embodiments, the wafer42can be diced to define a plurality of diced heat transfer elements including the heat transfer element1. In a different process, the upper portion16and the lower portion18can be bonded after a dicing process. In other words, the upper portion16and the lower portion18can be bonded at die level.

A phase change material20can be disposed in the chamber12. In some embodiments, the phase change material20can be disposed in the chamber12after the upper portion16and the lower portion18are bonded. In some embodiments, the housing10can include a charge or inlet port (not illustrated) for providing the phase change material20into the chamber12. In some embodiments, the phase change material20can be in a liquid form when provided into the chamber12. In such embodiments, the phase change material20can be, for example, injected into the chamber. In some other embodiments, the phase change material20can be in a solid form or in a vapor form.

FIG.4Dshows a side cross-sectional view of the heat transfer element1that is in contact with and bonded to an element (e.g., an electrical component22). As discussed above, the metal portion14of the heat transfer element can comprise a reactive metal, in some embodiments. In such embodiments, an application of energy (e.g., electrical energy or thermal energy) can cause the metal portion14to react to form a bond between the heat transfer element1and the electrical component22. The energy can be applied from, for example, an edge of the metal portion14, as illustrated inFIG.4D. The application of energy can bond the electrical component22to the heat transfer element1. In other embodiments, as explained above in connection withFIGS.3A-3B, the energy can be applied to an upper surface of the housing and can be transferred to the metal portion14by way of the via40.

FIG.5is a schematic side cross-sectional view of a structure5that includes a heat transfer element6according to another embodiment. Unless otherwise noted, the components ofFIG.5may refer to components that are the same as or generally similar to like components ofFIGS.1A to4D. The structure5can include two elements (e.g., electrical components22,52) in contact with opposing sides of the heat transfer element6.

The heat transfer element6can include a housing62that comprises a first metal portion64, a second metal portion66, and a frame68. The heat transfer element6can also include a chamber70defined at least in part by the housing62. A phase change material can be disposed in the chamber70. As inFIGS.1B and3B, the electrical component22can be bonded to the heat transfer element6by way of a metal bonding structure14′. Similarly, the electrical component52can be bonded to the heat transfer element6by way of a metal bonding structure14′. Thus, inFIG.5, heat can be vertically transferred between the electrical components22,52by way of the heat transfer element6.

FIG.6Ais a schematic side cross-sectional view of a heat transfer element7according to another embodiment.FIG.6Bis a schematic perspective view of the heat transfer element7. The heat transfer element7is generally similar to the heat transfer element1illustrated inFIG.1A. Unless otherwise noted, components ofFIGS.6A and6Bmay refer to components that are the same as or generally similar to like components ofFIG.1A.

The heat transfer element7can include a housing10that comprises a frame and a metal portion14. The heat transfer element7can include a chamber12that is defined at least in part by the housing10. The frame can comprise an upper portion16and a lower portion18. The heat transfer element7can also include a pillar72and a spoke74. In some embodiments, the pillar72can extend from the spoke74. The pillar72and the spoke74can extend nonparallel to each other. For example, the pillar72and the spoke74can extend generally perpendicular to each other. In some embodiments, the spoke74can extend from a section of the frame. In some embodiments, the spoke74can contact the metal portion14.

The pillar72and/or the spoke74can be formed using any suitable process. For example, the pillar72and/or the spoke74can be formed when a portion of the wafer42is removed to form the cavity44in a removing process as shown inFIG.4B. For example, the pillar72and/or the spoke74can be formed after the cavity44is formed in some embodiments. In some embodiments, the pillar72can be formed with any suitable method such as masked etching. In some embodiments, the spoke74can be formed prior to forming the cavity44(seeFIG.4B) from the lower side42bof the wafer42. For example, the spoke74can comprise a layer deposited on the lower side42b, which can be an etch stop when back etching the wafer42.

A pressure in the chamber12and a pressure of the outside environs can be different. For example, when the chamber12is in a vacuum or near vacuum condition, certain portions of the housing10may deform or be subject to mechanical stresses. In such condition, the pillar72and/or the spoke74can provide mechanical support to the heat transfer element7, thereby mitigating and/or preventing the heat transfer element7from a structural failure.

In some embodiments, as described above, the phase change material20can be in a liquid form, a solid form, and/or a vapor form. For example, the phase change material20can change its phase from the liquid form to the vapor form in response to an increase in temperature. In some embodiments, a heat transfer element with the pillar72can enable the vapor form of the phase change material20to change back to the liquid form more quickly than a heat transfer element without the pillars72. For example, the pillar72can wick the vapor form of the phase change material20down to a lower side of the heat transfer element7to relatively quickly return to the liquid form.

Although disclosed in the context of certain embodiments and examples, it will be understood by those skilled in the art that the present invention extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses and obvious modifications and equivalents thereof. Further, unless otherwise noted, the components of an illustration may be the same as or generally similar to like-numbered components of one or more different illustrations. In addition, while several variations have been shown and described in detail, other modifications, which are within the scope of this disclosure, will be readily apparent to those of skill in the art based upon this disclosure. It is also contemplated that various combinations or sub-combinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the present disclosure. It should be understood that various features and aspects of the disclosed embodiments can be combined with, or substituted for, one another in order to form varying modes of the disclosed invention. Thus, it is intended that the scope of the present invention herein disclosed should not be limited by the particular disclosed embodiments described above, but should be determined only by a fair reading of the aspects that follow.