Low melting point metal or alloy incorporated micro- / NANO-structured composite

Abstract

A thermal interface composition comprising a mechanically compliant interconnected micro / nano-structured material incorporated with an effective amount of a low melting point metal or alloy in which the low melting point metal or alloy has a melting point below 300℃ and above 31℃ under atmospheric pressure; the micro / nano-structured material has a self-supporting interconnected micro- or nano-structure and is capable of holding the low melting point metal or alloy internally; the micro / nano-structured material is made of a metal or semiconductor or dielectric material; and the self-supporting interconnected micro- or nano-structure is in a form selected from the group consisting of aligned and / or distributed wires, meshes, core-shells, heterostructures, and combinations thereof.

Description

PATENT APPLICATION FILED UNDER THE PATENT COOPERATION TREATY AT THE UNITED STATES RECEIVING OFFICEFORLOW MELTING POINT METAL OR ALLOY INCORPORATED MICRO- / NANO- STRUCTURED COMPOSITEAPPLICANT:NovoLINC, INC.INVENTORS: Rui Cheng Sheng ShenNing LiZexiao WangPREPARED BY:Enshan Hong293 EISENHOWER PKWY, SUITE 135 LIVINGSTON, NJLOW MELTING POINT METAL OR ALLOY INCORPORATED MICRO- / NANO-STRUCTURED COMPOSITERELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 681,947, filed August 12, 2024, the content of which is incorporated herein in its entirety.BACKGROUND OF THE INVENTION

[0002] Thermal interface resistance has become the critical bottleneck of heat dissipation in energy-dense devices and systems. Developing high-performance, multifunctional thermal interface materials (TIMs) remains a formidable challenge. Primarily, TIMs should be thermally conductive and mechanically soft to reduce thermal interface resistance and accommodate thermal stress simultaneously. Besides, TIMs are preferably reliable, easily applicable, serviceable, and affordable in terms of various application scenarios.

[0003] Market-dominating TIMs, such as greases, compounds, pads, tapes, and phase change materials, are the combination of compliant polymers or liquid base materials with thermally conductive fillers. Still, their overall performance is generally poor, as expected from the scattered heat conduction among the suspended fillers and base materials.

[0004] Solders may be thermally melted to bridge the interface but inevitably are limited by high-temperature soldering and poor mechanical compliance after solidification.

[0005] Through-plane aligned or ordered micro- / nano-structures have emerged as a promising platform. Yet, their thermal performance is mainly compromised by the considerable contact thermal resistance from the dry thermal contact when applying them asTIMs.

[0006] Liquid metals, for example, Ga-based alloys, may exist as a liquid under room temperatures and be applied easily, akin to thermal pastes. Their ultra-low viscosity allows a small bond line thickness. With high thermal conductivity, liquid metals have been used as high-performance TIMs. Besides, liquid metals have been recently integrated with polymers or solvents to form high-performance thermal compounds or used with some aligned micro- / nano-structures to reduce their contact thermal resistance. However, liquid metals suffer from limited material compatibility and severe safety concerns of migration / leakage. The current recipes rely heavily on gallium, which is known to be highly corrosive or reactive to the most commonly used materials at thermal interfaces, such as aluminum, copper, or nickel.SUMMARY OF THE INVENTION

[0007] One aspect of the present application is a thermal interface composition comprising a mechanically compliant interconnected micro / nano-structured material incorporated with an effective amount of a low melting point metal or alloy.

[0008] The low melting point metal or alloy has a melting point below 300°C and above 31°C under atmospheric pressure.

[0009] The micro / nano-structured material has a self-supporting interconnected micro- or nano- structure and is capable of holding the low melting point metal or alloy internally.

[0010] The micro / nano-structured material is made of a metal or semiconductor or dielectric material.

[0011] The self-supporting interconnected micro- or nano-structure is in a form selected from the group consisting of aligned and / or distributed wires, meshes, core-shells, heterostructures, and combinations thereof.

[0012] The metal material may be selected from the group consisting of copper, aluminum, nickel, silver, gold, brass, cadmium, chromium, stainless steel, carbon steel, iron, and combinations thereof.

[0013] The semiconductor or dielectric material may be selected from the group consisting of AI2O3, BN, ZnO, SiO2, MgO, TiO2, SiC, AIN, BeO, Y2O3, ZnS, ZnO, ZnSe, CdMnTe, CdS, ZnTe, GaSe, InSe, CdSe, CuInGaSe2, CdTe, CuInSe2, Ni(OH)2, and combinations thereof.

[0014] The mi cro- / nano- structured material may have vacancies structurally, and the low melting point metal or alloy may be pre-applied onto the mi cro- / nano- structure or applied separately in a form selected from the group consisting of films, sheets, or particles, at an interface.

[0015] The low melting point metal or alloy may be volumetrically infused into the mi cro- / nano- structured material and takes over 20%, preferably over 30%, preferably 50%, further preferably over 60%, more preferably over 70%, particularly preferable over 80%, and most preferably over 90% of the vacancies.

[0016] The low melting point metal or alloy may be selected from the group consisting of indium, bismuth, tin, cadmium, antimony, and alloys thereof.

[0017] The alloys may be selected from the group consisting of lead-tin alloys, leadtin-silver alloys, bismuth-tin alloys, bismuth-tin-silver alloys, zinc-tin alloys, lead-bismuth alloy, tin-copper alloys, tin-silver alloys, tin-copper-silver alloys, tin-antimony alloy, and combinations thereof.

[0018] The low melting point metal or alloy may have a melting point of above 50°C and below 250°C.

[0019] The low melting point metal or alloy may fill the vacancies between the mi cro- / nano- structure and the interface when melted to significantly reduce the contact resistance.

[0020] The composition may further comprise an activation material capable of facilitating contact between the low melting point metal or alloy and an interface. Theactivation material is preferably a low-temperature flux or reactive agent material, more preferably an acid, that removes non-thermally-conductive residues / contamination / oxides when applied.

[0021] The micro / nano-structured material is preferably hydrophilic to the low melting point metal or alloy when melted.

[0022] The composition may further comprise a coating layer which is capable of protecting the composition from oxidation and / or facilitating wetting the low melting point metal or alloy when being melted and applied to an interface. The coating layer may be made of a coating material selected from the group consisting of metals, oxides, polymer, organic solvent, oil, acid, flux, and combinations thereof.

[0023] The composition may be prepared by a method comprising (1) treating a surface of the mechanically compliant interconnected micro / nano-structured material to make it hydrophilic; (2) causing the treated micro / nano-structured material to get in contact with the low melting point metal or alloy under a temperature higher than the melting point of the low melting point metal or alloy. The treating may be selected from the group consisting of plasma treatment, UV / Ozone treatment, chemical treatment, thermal treatment, hydrophilic coating, and combination thereof.

[0024] The composition may be used at a thermal interface for transferring heat from one side of the thermal interface to the other side of the thermal interface.

[0025] The present application also provides a thermal component comprising:

[0026] a lower-temperature object;

[0027] a higher-temperature obj ect; and

[0028] a composition of the present application serving as a thermal interface material and being positioned between the lower-temperature object and the higher-temperature object.BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 illustrates the application of LMPMA incorporated micro- / nano- structured composite (101) as a thermal interface material between heat sink (102) and heat source (103), where the LMPMA is pre-applied.

[0030] Figure 2 illustrates the application of micro- / nano-structure (0001) with separate LMPMA films, sheets, or particles (102 & 103) together as a thermal interface material between heat sink (104) and heat source (105).DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0031] As used herein, the term “about” when immediately preceding a numerical value means a range of plus or minus 10% of that value, for example, “about 50” means 45 to 55, “about 25,000” means 22,500 to 27,500, etc., unless the context of the disclosure indicates otherwise, or is inconsistent with such an interpretation.

[0032] As used herein, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. Nothing in this disclosure is to be construed as an admission that the embodiments described in this disclosure are not entitled to antedate such disclosure by virtue of prior invention. As used in this document, the term “comprising” means “including, but not limited to.”

[0033] While various compositions, methods, and devices are described in terms of "comprising" various components or steps (interpreted as meaning "including, but not limited to"), the compositions, methods, and devices may also "consist essentially of' or "consist of' the various components and steps, and such terminology should be interpreted as defining essentially closed-member groups.

[0034] With respect to the use of substantially any plural and / or singular terms herein, those having skill in the art may translate from the plural to the singular and / or from the singular to the plural as is appropriate to the context and / or application. The various singular / plural permutations may be expressly set forth herein for sake of clarity.

[0035] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (for example, bodies of the appended claims) are generally intended as “open” terms (for example, the term “including” should be interpreted as “including, but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those skilled in the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation, no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to embodiments containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (for example, “a” and / or “an” should be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (for example, the bare recitation of "two recitations," without other modifiers, means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, ingeneral such a construction is intended in the sense one having skill in the art would understand the convention (for example, “ a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (for example, “ a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and / or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.”

[0036] In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.

[0037] As will be understood by one skilled in the art, for any and all purposes, such as in terms of providing a written description, all ranges disclosed herein also encompass any and all possible subranges and combinations of subranges thereof. Any listed range may be easily recognized as sufficiently describing and enabling the same range to be broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein may be readily broken down into a lower third, middle third and upper third, etc. As will also be understood by one skilled in the art all language such as “up to,” “at least,” and the like include the number recited and refer to ranges which may be subsequentlybroken down into subranges as discussed above. Finally, as will be understood by one skilled in the art, a range includes each individual member. Thus, for example, a group having 1 -3 cells refers to groups having 1, 2, or 3 cells. Similarly, a group having 1-5 cells refers to groups having 1, 2, 3, 4, or 5 cells, and so forth.

[0038] This disclosure is not limited to the particular systems, devices, and methods described, as these may vary. The terminology used in the description is for the purpose of describing the particular versions or embodiments only and is not intended to limit the scope.

[0039] The micro- or nano- structured material as used herein may be a material with a scaffold structure in the size of micro- or nano- scale. Micro- or nano-structure refers to the architecture or arrangement of material components at the microscopic or nanoscopic scale, with features ranging from 1 nanometer to 1000 micrometers, preferably 10 nanometers to 500 micrometers, more preferably 100 nanometers to 300 micrometers.

[0040] The micro- / nano-structured material as used herein refers to a material having a micro- / nano-structure, which is a self-supporting interconnected micro- or nano-structure and is capable of holding the LMPMA internally. This “micro- / nano-structured material” represents an ensemble of micro or nano components interconnected with each other to form a joint structure. The mi cro- / nano- structure may be in a form of self-supported interconnected wires, substrate supported aligned and / or distributed wires, ordered and / or non-ordered meshes, stacked meshes, or the core-shell and / or heterostructure hybrid materials on that basis. The micro- / nano-structured material may be made of a material selected from the group consisting of metals and semiconductors. The metals may be selected from the group consisting of copper, aluminum, nickel, silver, gold, brass, cadmium, chromium, stainless steel, carbon steel, iron, and combinations thereof. The semiconductors may be selected from the group consisting of AI2O3, BN, ZnO, SiCh, MgO, TiCh, SiC, AIN, BeO, Y2O3, ZnS, ZnO,ZnSe, CdMnTe, CdS, ZnTe, GaSe, InSe, CdSe, CuInGaSe?, CdTe, CuInSe?, Ni(0H)2, and combinations thereof.

[0041] The mi cro- / nano- structure may be formed of a plurality of units. The units may be, for example, wires, meshes, core-shell structures, or heterostructures. As used herein, a “unit” may refer to a single wire in a wire-based structure, a single pore in a mesh-based structure, or a single discrete element in a core-shell or heterostructure. In some embodiments, the structure is a micro- structure, wherein a characteristic dimension of each unit ranges from approximately 1 pm to approximately 999 pm. In other embodiments, the structure is a nano- structure. Each unit's characteristic dimension may range from approximately 1 nm to approximately 999 nm. The characteristic dimension is defined as the length and diameter of a single wire in the wire based structure, the x-y dimension of a single pore for a mesh based structure, the x-y-z dimension of a single discrete element in a coreshell or heterostructure.

[0042] The low melting point metal or alloy (LMPMA) incorporated micro- / nano- structured composite thermal interface material, as used herein, refers to a composite comprising a micro- / nano-structured material incorporated with the LMPMA.

[0043] The term “incorporated” in the expression of “low melting point alloy (LMPMA) incorporated micro- / nano-structured composite thermal interface material”, as used herein, means that the LMPMA is wholly or partially infused into the vacancies of the mi cro- / nano- structured material scaffold to form a composite. However, as an embodiment of the instant invention, the LMPMA and mi cro- / nano- structured material scaffold may also be applied separately at the beginning of the application, and the infusion process may happen automatically during its use as TIM.

[0044] The present disclosure provides a low melting point metal or alloy (LMPMA) incorporated micro- / nano-structured composite thermal interface material (TIM).

[0045] When the temperature is below the melting point of LMPMA, the LMPMA- incorporated micro- / nano-structured composite exists in the form of a solid. In some embodiments, the composite mechanically bonds the two objects at the thermal interface. The thermal stress at the interface would be taken by the solid-to-solid interfacial bonding between the LMPMA-incorporated mi cro- / nano- structured composite TIM and the object.

[0046] When applied as a high-performance TIM, the LMPMA in the micro- / nano- structured scaffold turns into a liquid or semi-liquid at a temperature above the melting point of LMPMA. In some embodiments, the contact at the thermal interface is between the solid- liquid-composite of LMPMA-incorporated mi cro- / nano- structured composite TIM and the solid object surface, where the liquid form of LMPMA may entirely or partially fill the vacancies at the interface. The LMPMA replaces the original filled air vacancies so that the LMPMA-incorporated mi cro- / nano- structured composite has higher bulk thermal conductivity than the bare mi cro- / nano- structure. The melted flowable and reflowable LMPMA further fills any potential vacancies between the micro- / nano-structure, improving the contact between the mi cro- / nano- structure and object surfaces and reducing contact resistance. The combination of high bulk thermal conductivity and low contact resistance contributes to the overall low effective thermal resistance at thermal interfaces.

[0047] After the melting of LMPMA above the melting temperature at the thermal interface, the mechanically compliant interconnected micro- / nano-structure holds the melted LMPMA and complies with the interface roughness, forming numerous contact points with the interfaces, leading to efficient heat transfer through the TIM layer. Meanwhile, the compliant interconnected micro- / nano-structure mechanically accommodates the applied stress and the thermally induced stress at the interface, leading to long-term stability.

[0048] At a temperature below the melting point, the LMPMA solidifies and maintains interface integrity without being pumped out or migrated, leading to high reliability.

[0049] Any LMPMA flowing outside the thermal interface would quickly solidify once cooled down to below its melting point, either cooled by natural / forced convection or conduction from contacting cooler objects.

[0050] Any cracks, fractures, voids, detachments, or shifting that occur when LMPMA is below the melting point will be fixed once the interfacial temperature rises above the melting point, leading to a self-repairing function.

[0051] In some embodiments, LMPMA is pre-applied onto the micro- / nano- structured material through pressing, calendaring, coating, deposition, or scrabbing. In some embodiments, the micro- / nano-structured material is applied with separated LMPMA in a form, such as films, sheets, or particles, at the interface.

[0052] In some embodiments, the micro- / nano-structure has a self-supporting interconnected micro- or nano- structure and is capable of holding the LMPMA internally.

[0053] In some embodiments, the described micro- / nano-structured material is hydrophilic or pre-treated to be hydrophilic with liquid LMPMA, at a temperature above the melting point of LMPMA.

[0054] In some embodiments, LMPMA volumetrically infuses into the micro- / nano- structured material and takes over 50% of the vacancies among the mi cro- / nano- structure of the micro- / nano-structured material, preferably over 60%, more preferably over 70%, particularly preferably over 80%, and most preferably over 90%, contributing to a high thermal conductivity for the overall composite.

[0055] In some embodiments, the micro / nano-structured material preferably contains over 50% volume of metal, preferably over 60%, preferably over 70%, preferablyover 80%, preferably over 90%, and has a high thermal conductivity. Overall, the composite has a high thermal conductivity, benefiting from the majority composition of metal.

[0056] In some embodiments, the melted LMPMA further fills the vacancies between the micro- / nano-structure of the mi cro- / nano- structured material and the object surfaces to reduce the contact resistance significantly. Overall, the LMPMA incorporated micro- / nano- structured composite combines low bulk thermal resistance and low contact thermal resistance to possess an overall low thermal resistance as a TIM.

[0057] In some embodiments, the micro- / nano-structured material for TIM applications may be in the form of interconnected aligned and / or distributed wires, meshes, core-shells, heterostructures, and the combinations thereof.

[0058] In some embodiments, the micro- / nano-structured material may be in a form of self-supported interconnected wires, substrate supported aligned and / or distributed wires, ordered and / or non-ordered meshes, stacked meshes, and / or the core-shell and / or heterostructure hybrid materials on that basis.

[0059] In some embodiments, the material of the micro- / nano-structure might be selected from the group consisting of metals, such as copper, aluminum, nickel, silver, gold, brass, cadmium, chromium, stainless steel, carbon steel, and iron, and semiconductors, such as AI2O3, BN, ZnO, SiO2, MgO, TiO2, SiC, AIN, BeO, Y2O3, ZnS, ZnO, ZnSe, CdMnTe, CdS, ZnTe, GaSe, InSe, CdSe, CuInGaSe2, CdTe, CuInSe2, and Ni(OH)2.

[0060] In some embodiments, the mi cro- / nano- structure may be manufactured through top-down approaches, including lithography, etching, mechanical milling, or bottom- up approaches, including 3D printing, chemi cal / phy si cal vapor deposition, self-assembly, solgel process, electrodeposition, molecular beam epitaxy, or hybrid approaches including soft lithography, dip-pen nanolithography, or some other methods, such as nanoimprint, nanoimprint lithography, plasma-assisted techniques, and hot / cold pressing.

[0061] In some embodiments, the micro- / nano-structure may be manufactured through a templated electrochemical deposition method, in which the micro- / nano-structures are deposited through an electrochemical deposition process inside the confined micro- / nano- structured porous templates. For example, copper micro- / nano-structures may be formed by electrodepositing copper into porous templates using copper electrolyte. And hybrid materials may be formed through either co-deposition, or sequential deposition, or the combination thereof. For example, a metal / semiconductor hybrid scaffold may be formed by deposition of a metal scaffold followed by deposition of a semiconductor onto it. Following the removal of the template, the deposited structure would be released and further incorporated with LMPMA to form the composite. The hybrid scaffold may also be formed by further depositing materials onto the as-formed scaffold.

[0062] In some embodiments, an LMPMA-incorporated micro- / nano-structured composite may be fabricated using roll-to-roll fabrication.

[0063] In some embodiments, an LMPMA-incorporated micro- / nano-structured composite may be fabricated by fully solution-processed manufacturing.

[0064] In some embodiments, the LMPMA may comprise low melting point metals of indium, bismuth, lead, tin, cadmium, thallium, antimony, cadmium, or their alloy forms, such as lead-tin alloys (including, but not limited to, Sn63 / Pb37, Sn60 / Pb40, Snl0 / Pb90, Snl0 / Pb90), lead-tin-silver alloys (including, but not limited to, Sn62 / Pb36 / Ag2, Pb92.5 / Sn5 / Ag2.5), bismuth-tin alloys (including, but not limited to, Sn58 / Bi42, Sn42 / Bi58), bismuth-tin-silver alloys (including, but not limited to, Bi57 / Sn43 / Agl), zinc-tin alloys (including, but not limited to, Sn91 / Zn9), lead-bismuth alloy (including, but not limited to, Pb55 / Bi45), tin-copper alloys (including, but not limited to, Sn99.3 / Cu0.7), tin-silver alloys (including, but not limited to, Sn96.5 / Ag3.5), tin-copper-silver alloys (including, but notlimited to, Sn96.5 / Ag3.0 / Cu0.5, Sn95.5 / Ag4.0 / Cu0.5, Sn99 / Ag0.3 / Cu0.7), tin-antimony alloy (including, but not limited to, Sn95 / Sb5), and the like.

[0065] In other examples, minor additives of other metal elements may be present. Examples include the Rose's metal, Cerrosafe, Wood's metal, Field's metal, Mellotte's Metal, Cerrolow 136, Cerrolow 117, Bi-Pb-Sn-Cd-In-Tl, and further fine-tuned recipes based on similar major element compositions with less than 10% composition ratio variation of each composed element.

[0066] In some embodiments, the LMPMA has a melting point starting from 31 degree Celsius, starting from 50 degree Celsius, starting from 70 degree Celsius, starting from 100 degree Celsius, starting from 200 degree Celsius, starting from 250 degree Celsius, starting from 290 degree Celsius, and / or below 300 degree Celsius, below 250 degree Celsius, below 200 degree Celsius, below 100 degree Celsius, below 70 degree Celsius, below 50 degree Celsius, or other melting temperatures such as those listed.

[0067] LMPMA-incorporated mi cro- / nano- structured composite may be applied as TIM to fill the gaps among the object interfaces, reduce the heat transfer barrier, and facilitate the heat transfer across the interface.

[0068] In some embodiments, to apply LMPMA incorporated mi cro- / nano- structured composite as a TIM, the applying approaches include (1) removing the package cover of the composite, (2) applying the LMPMA-pre-applied micro- / nano-structured composite or the LMPMA and micro- / nano-structure in separate form at the thermal interface, (3) applying certain pressure on the interface, preferably 1 to 100 Psi, more preferably 10 to 70 Psi, and more preferably 30-50 Psi, (4) heating up the interface to above the melting point of LMPMA, forming a LMPMA-incorporated micro- / nano-structured composite at the thermal interface as an TIM. In some embodiments, the LMPMA incorporated mi cro- / nano- structuredcomposite only needs to be applied once and would work as a TIM for the rest of the material's life.

[0069] LMPMA-incorporated mi cro- / nano- structured composite TIM may be applied to various thermal interface conditions, including TIM 1, TIM 1.5, and TIM 2. TIM 1 includes TIM applied between the die and heat spreader, for example, between chip die and integrated heat spreader, or between high power density components, such as transistors, LEDs, and their packaging lids. TIM 1.5 includes TIM applied between the chip dies, LEDs, transistors, and heat sink. Example 1, between a GPU die and a cold plate in direct-to-chip cooling; Example 2, between a GPU die and a boiling pad or heat sink in immersion cooling. TIM 2 includes TIM applied between packaged heat sources like chips, LEDs, electronics, power components, batteries, laser modules, transistor arrays, and the heat sink. Example 1, between a CPU package and a cooler. Example 2, between a battery pack and a heat dissipation chassis.

[0070] In some embodiments, an LMPMA-incorporated micro- / nano-structured composite may be prepackaged in containers, covers, protection layers, etc., for easier delivery and application.

[0071] In some embodiments, the prepackaging approaches include (1) attaching the LMPMA-incorporated mi cro- / nano- structured composite to the cover layers at above melting point, (2) evenly applying a pressure and squeezing out certain amount of LMPMA that is not held inside the micro- / nano-structure, (3) cooling down the package to below melting point and forming a prepackaged solid form LMPMA-incorporated mi cro- / nano- structured composite. In some embodiments, the cover layer is pre-applied with a low working temperature activation material prior to attaching the LMPMA-incorporated micro- / nano- structured composite in the step (1).

[0072] In some embodiments, the LMPMA may be packaged separately from the mi cro- / nano- structured material. For example, the LMPMA may be individually packaged as films, sheets, or particles, and stacked with the micro- / nano-structured material during the initial application as TIM.

[0073] In some embodiments, after being applied as a thermal interface material at an interface, the LMPMA-incorporated mi cro- / nano- structured composite may be taken off from the interface and applied again, such as to a fresh sample, so that it possesses a high reworkability.

[0074] In some embodiments, LMPMA-incorporated micro- / nano-structured composite may mechanically bond the interface and maintain integrity without external clamping forces.

[0075] In some embodiments, LMPMA may protect the micro- / nano-structure from oxidation, corrosion, or degradation.

[0076] In some embodiments, the LMPMA-incorporated micro- / nano-structured composite described herein includes a LMPMA-incorporated micro- / nano-structured Cu thermal interface material.

[0077] In some embodiments, an LMPMA-incorporated micro- / nano-structured composite may integrate a freestanding double-sided nanowire array with a diverse range of LMPMAs.

[0078] In some embodiments, a LMPMA-incorporated micro- / nano-structured composite may be fabricated through the following steps: (1) treating the micro- / nano- structure surface to make it hydrophilic with a melted LMPMA, where the treatment method may be comprised of plasma treatment, UV / Ozone treatment, chemical treatment, thermal treatment, hydrophilic coating, and combination thereof; (2) causing the treated micro- / nano-structure to get in contact with the melted LMPMA under a temperature higher than the melting point of LMPMA.

[0079] In some embodiments, an LMPMA-incorporated micro- / nano-structured composite may be protected by an extra coating layer comprised of metals, oxides, oil, grease, polymers, organic solvents, flux, and / or a combination thereof to prevent the LMPMA-incorporated mi cro- / nano- structured composite from oxidation or degradation.

[0080] In some embodiments, an LMPMA-incorporated micro- / nano-structured composite may be further protected by a functional coating layer comprised of metals, oxides, polymer, organic solvent, oil, acid, flux, and / or a combination thereof, which helps to wet the melted LMPMA with the surfaces when applied.

[0081] In some embodiments, the LMPMA forms an intermetallic bonding with alloy-compatible metal interfaces, further significantly reducing the contact thermal resistance and benefiting the ultra-low thermal resistance at the interface.

[0082] In some embodiments, a low working temperature activation material, e.g., a low-temperature flux or reactive agent material like acids that can interact with the LMPMA oxides and contaminations, may be applied together with the LMPMA-incorporated micro- / nano- structured composite at interfaces. When the temperature rises to melt the LMPMA, the potential existing oxide shell or contamination layer covering the melted LMPMA is further wrapped / mixed / dissolved / removed with the activation material to be flowable and avoid gapping between the composite and the interface LMPMA, which prohibits contact between the LMPMA and the interface. As a benefit, the interfacial thermal resistance would be largely compressed. Besides, in some embodiments where LMPMA forms intermetallic bonding with the metal interface, the low working temperature activation material results in direct contact between LMPMA and the metal interface to facilitate the formation of an intermetallic layer.

[0083] In some embodiments, the low working temperature activation material may be pre-applied on the described LMPMA-incorporated micro- / nano-structured composite to protect it from oxidizing.

[0084] In some embodiments, the low working temperature activation material may be pre-applied on the described LMPMA-incorporated micro- / nano-structured composite to allow an initial contact with interfaces, where the sole composite would originally form point contacts only with the interfaces due to the rigidity below the melting temperatures.

Claims

CLAIMSWe claim:

1. A thermal interface composition comprising a mechanically compliant interconnected micro / nano-structured material incorporated with an effective amount of a low melting point metal or alloy, wherein: the low melting point metal or alloy has a melting point below 300°C and above 31°C under atmospheric pressure; the micro / nano-structured material has a self-supporting interconnected micro- or nano- structure and is capable of holding the low melting point metal or alloy internally; the micro / nano-structured material is made of a metal or semiconductor or dielectric material; and the self-supporting interconnected micro- or nano-structure is in a form selected from the group consisting of aligned and / or distributed wires, meshes, core-shells, heterostructures, and combinations thereof.

2. The composition of claim 1 wherein the micro / nano-structured material is made of the metal material, and wherein the metal material is selected from the group consisting of copper, aluminum, nickel, silver, gold, brass, cadmium, chromium, stainless steel, carbon steel, iron, and combinations thereof.

3. The composition of claim 1 wherein the micro / nano-structured material is made of the semiconductor or dielectric material, and wherein the semiconductor or dielectric material is selected from the group consisting of AI2O3, BN, ZnO, SiCh, MgO, TiCh, SiC, AIN, BeO, Y2O3, ZnS, ZnO, ZnSe, CdMnTe, CdS, ZnTe, GaSe, InSe, CdSe, CuInGaSe2, CdTe, CuInSe2, Ni(0H)2, and combinations thereof.

4. The composition of claim 1 wherein the micro- / nano-structured material has vacancies structurally, and the low melting point metal or alloy is pre-applied onto the micro- / nano- structure or applied separately in a form selected from the group consisting of films, sheets, or particles, at an interface.

5. The composition of claim 4 wherein the low melting point metal or alloy is volumetrically infused into the micro- / nano-structured material and takes over 20%, preferably over 30%, preferably 50%, further preferably over 60%, more preferably over 70%, particularly preferable over 80%, and most preferably over 90% of the vacancies.

6. The composition of claim 1 wherein the low melting point metal or alloy is selected from the group consisting of indium, bismuth, tin, cadmium, antimony, and alloys thereof.

7. The composition of claim 6 wherein the alloys are selected from the group consisting of lead-tin alloys, lead-tin-silver alloys, bismuth-tin alloys, bismuth-tin-silver alloys, zinc-tin alloys, lead-bismuth alloy, tin-copper alloys, tin-silver alloys, tin-copper-silver alloys, tinantimony alloy, and combinations thereof.

8. The composition of claim 1 wherein the low melting point metal or alloy fills the vacancies between the micro- / nano-structure and an object surface when melted to significantly reduce the contact resistance.

9. The composition of claim 1 further comprising an activation material capable of facilitating contact between the low melting point metal or alloy and an object surface, wherein the activation material is preferably a low-temperature flux or reactive agent material, more preferably an acid, that removes non-thermally-conductive residues / contamination / oxides when applied.

10. The composition of claim 1 wherein the micro / nano-structured material is hydrophilic to the low melting point metal or alloy when melted.

11. The composition of claim 1 further comprising a coating layer which is capable of protecting the composition from oxidation and / or facilitating wetting the low melting point metal or alloy when being melted and applied to an interface, wherein the coating layer is made of a coating material selected from the group consisting of metals, oxides, polymer, organic solvent, oil, acid, flux, and combinations thereof.

12. A method of making the composition of claim 1 comprising treating a surface of the mechanically compliant interconnected micro / nano-structured material to make it hydrophilic; (2) causing the treated micro / nano-structured material to get in contact with the low melting point metal or alloy under a temperature higher than the melting point of the low melting point metal or alloy, wherein the treating is selected from the group consisting of plasma treatment, UV / Ozone treatment, chemical treatment, thermal treatment, hydrophilic coating, and combination thereof.

13. Use of the composition of claim 1 at a thermal interface for transferring heat from one side of the thermal interface to the other side of the thermal interface.

14. A thermal component comprising: a lower-temperature object; a higher-temperature obj ect; and a composition of claim 1 serving as a thermal interface material and being positioned between the lower-temperature object and the higher-temperature object.

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