A one-component dispenseable substance with a high and stable flow rate.

Abstract

The present invention provides exemplary composite materials useful for controlling thermal and / or electromagnetic interference (EMI), and a method for improving the flow characteristics of said composite materials. [Solution] In exemplary embodiments, the composite material comprises a matrix, one or more fillers in the matrix, and a temperature-activated thixotropic agent in the matrix. The temperature-activated thixotropic agent can be activated by heating the composite material to a predetermined minimum temperature for at least a predetermined minimum time, thereby increasing the flow rate and flow stability over time of the composite material. Also disclosed are exemplary methods for improving the flow characteristics of the composite material useful for controlling thermal and / or electromagnetic interference (EMI). In the exemplary method, the flow rate of the composite material is increased and the flow stability over time is increased by using a temperature-activated thixotropic agent.

Description

Technical Field

[0001] The present disclosure relates to a one - component dispensable material (broadly, a composite material) configured to have a highly stable flow rate over time. The one - component dispensable material can include one - component dispensable thermal interface materials (TIMs) (e.g., highly thermally conductive one - component dispensable gap fillers, etc.), one - component dispensable EMI absorbing materials, one - component dispensable thermally conductive EMI absorbing materials, one - component dispensable conductive materials, etc., which are one - component dispensable thermal management and / or electromagnetic interference (EMI) reduction materials.

Background Art

[0002] This section provides background information related to the present disclosure that is not necessarily prior art. Electrical components such as semiconductors, integrated circuit packages, transistors, etc. typically have a pre - designed temperature at which the electrical component operates optimally. Ideally, the pre - designed temperature is close to the temperature of the surrounding air. However, heat is generated by the operation of the electrical component. If the heat is not removed, the electrical component may operate at a temperature significantly higher than its normal or desired operating temperature. Such excessive temperatures can have an adverse effect on the operating characteristics of the electrical component and the operation of related devices.

[0003] To avoid, or at least reduce, unfavorable operating characteristics due to heat generation, heat should be removed, for example, by conducting heat from the operating electrical component to the heatsink. The heatsink may then be cooled by conventional convection and / or radiation techniques. During conduction, heat can be transferred from the operating electrical component to the heatsink by direct surface contact between the electrical component and the heatsink, and / or by contact between the electrical component and the heatsink surface via an intermediate medium or thermal interface material (TIM). Thermal interface materials may be used to fill gaps between heat transfer surfaces to improve heat transfer efficiency compared to filling gaps with air, which is a relatively poor heat conductor.

[0004] In addition, a common problem in the operation of electronic devices is the generation of electromagnetic radiation within the electronic circuits of the equipment. Such radiation can result in electromagnetic interference (EMI) or radio frequency interference (RFI), which can interfere with the operation of other electronic devices that are relatively close by. Without proper shielding, EMI / RFI interference can cause degradation or complete loss of important signals, thereby rendering electronic equipment inefficient or inoperable.

[0005] A common solution to mitigate the effects of EMI / RFI is the use of shields that can absorb and / or reflect and / or redirect EMI energy. These shields are typically employed to localize EMI / RFI within its source and to isolate other devices near the EMI / RFI source. These shields may consist of metals, polymer-inorganic composites, filled foams, foam materials wrapped or coated with absorbent and / or reflective materials, and the like.

[0006] As used herein, the term “EMI” should be understood to include and refer to EMI radiation and RFI radiation in general, and the term “electromagnetic” should be understood to include and refer to electromagnetic and radio frequencies from external and internal sources in general. Accordingly, the term shielding (as used herein) broadly includes and refers to mitigating (or limiting) EMI and / or RFI by absorbing, reflecting, blocking, and / or redirecting energy, or any combination thereof, so as not to interfere with administrative compliance and / or the internal functionality of an electronic component system. [Brief explanation of the drawing]

[0007] The drawings described herein are for illustrative purposes only of selected embodiments and are not intended to limit the scope of this disclosure, nor do they represent all possible implementations. [Figure 1] Exemplary embodiments of this disclosure show a one-component dispenseable that can be configured to have a high and stable flow rate over time. [Figure 2] Figures 2, 3, 4, and 5 include microscopic images illustrating exemplary embodiments of a one-component dispenseable containing a temperature-activated thixotropic agent at different activation stages (e.g., while the one-component dispenseable is heated to a temperature of 80°C to 100°C for at least 15 minutes). [Figure 3] Same as above. [Figure 4] Same as above. [Figure 5] Same as above. [Figure 6] Figure 6 shows line graphs of flow rate (grams / minute (g / min)) over time (days) for the first and second thermally conductive one-component dispenseables according to exemplary embodiments of the present disclosure. For comparison, Figure 6 also includes results for a conventional thermally conductive one-component dispenseable that does not contain a temperature-activated thixotropic agent. [Modes for carrying out the invention]

[0008] Next, exemplary embodiments will be described in more detail with reference to the attached drawings. As recognized herein, one-component dispensable thermal interface materials (TIMs) are commonly used due to the advantages they offer. For example, one-component dispensable TIMs do not require mixing. And simpler valve designs can be used with one-component dispensable TIMs without disposable static mixers. One-component dispensable TIMs can be used as is and do not require curing or post-treatment, thus eliminating the possibility of accidental curing in the line. Only one dispenser pump is required to dispense one-component dispensable TIMs, and ratio control is not necessary. Also, one-component dispensable TIMs can be reworked and / or reused, which may make them easier to remove from application cleanup. However, as further recognized herein, one-component dispensable TIMs have the problem of unstable flow rates that decrease over time.

[0009] Having recognized the above, exemplary embodiments of composite materials useful for thermal and / or electromagnetic interference (EMI) control, such as one-component, dispenseable thermal control and / or electromagnetic interference (EMI) mitigation materials, have been developed and / or are disclosed herein. In exemplary embodiments, the composite material comprises a matrix, one or more fillers in the matrix, and a temperature-activated thixotropic agent in the matrix. The temperature-activated thixotropic agent can be activated by heating the composite material to a predetermined minimum temperature for at least a predetermined minimum time, thereby increasing the flow rate and flow stability over time of the composite material. Also disclosed are exemplary methods for improving the flow characteristics of composite materials useful for thermal and / or electromagnetic interference (EMI) control. In exemplary methods, the flow rate and flow stability over time of the composite material are increased by using a temperature-activated thixotropic agent.

[0010] Referring to the drawings, Figure 1 shows a one-component dispenseable material 100 (broadly speaking, a composite material) configured to have a high and stable flow rate over time, according to an exemplary embodiment of the present disclosure. As shown, multiple one-component dispenseable materials 100 are dispensed onto a substrate 104.

[0011] The one-component dispenseable material 100 comprises a matrix, one or more fillers in the matrix, and a temperature-activated thixotropic agent in the matrix. The temperature-activated thixotropic agent can be activated by heating the composite material to a predetermined minimum temperature (e.g., at least about 80°C to 100°C) for at least a predetermined minimum time (e.g., about 15 minutes). Activation of the temperature-activated thixotropic agent increases the flow rate and flow rate stability over time of the composite material. For example, the one-component dispenseable material 100 may have a stable flow rate of at least about 100 grams / min and / or a stable flow rate in the range of 90 grams / min to 125 grams / min for at least 180 days.

[0012] In this exemplary embodiment, the one-component dispenseable 100 comprises a thixotropic agent activated at a temperature of about 0.1% to about 0.5% by weight, based on the total weight of the composite material. For example, the one-component dispenseable 100 may comprise about 0.1% to about 0.5% by weight of an amide wax-based powdered thixotropic agent.

[0013] Continuing this example, the one-component dispenseable 100 contains about 1 weight percent to about 9 weight percent (e.g., about 4.5 weight percent) of matrix, based on the total weight of the one-component dispenseable 100. The one-component dispenseable 100 also contains about 85 weight percent to about 96 weight percent (e.g., about 95 weight percent) of thermally conductive filler in the matrix, based on the total weight of the one-component dispenseable 100.

[0014] In this example, the matrix also includes a silicone resin such as dimethyl silicone oil. The thermally conductive filler includes one or more zinc oxide fillers (e.g., about 12.5 weight percent zinc oxide filler) and one or more alumina fillers (e.g., about 82.5 weight percent alumina filler). The zinc oxide fillers and alumina fillers have different shapes (e.g., irregular, spherical, etc.) and / or different D 50 It may have a median particle size (e.g., about 0.8 micrometers to about 100 micrometers). In this example, the one-component dispenseable material 100 is a one-component dispenseable thermal interface material having a thermal conductivity of at least 6 watts per meter per kelvin (W / mK) and a stable flow rate in the range of 90 grams / min to 125 grams / min for at least 180 days.

[0015] Figures 2, 3, 4, and 5 include microscopic images showing a one-component dispenseable (e.g., one-component dispenseable 100 shown in Figure 1) at different stages of activation of a temperature-activated thixotropic agent (e.g., while the one-component dispenseable is heated to a temperature of 80°C to 100°C for at least 15 minutes). More specifically, Figure 2 shows the one-component dispenseable 200 in the first or initial activation stage before activation of the temperature-activated thixotropic agent. Figure 3 shows the one-component dispenseable 300 in the second activation stage when the activation of the temperature-activated thixotropic agent has begun. Figure 4 shows the one-component dispenseable 400 in the third activation stage when the temperature-activated thixotropic agent is activated. Figure 5 shows the one-component dispenseable 500 in the fifth activation stage when the temperature-activated thixotropic agent is fully activated.

[0016] The one-component dispenseables shown in Figures 2, 3, 4, and 5 contain a matrix of about 1 weight percent to about 9 weight percent (e.g., about 4.5 weight percent) based on the total weight of the one-component dispenseable. The one-component dispenseables also contain a thermally conductive filler in the matrix of about 85 weight percent to about 96 weight percent (e.g., about 95 weight percent) based on the total weight of the one-component dispenseable. The matrix contained a silicone resin such as dimethyl silicone oil. The thermally conductive filler contained one or more zinc oxide fillers (e.g., about 12.5 weight percent zinc oxide filler) and one or more alumina fillers (e.g., about 82.5 weight percent alumina filler). The zinc oxide fillers and alumina fillers were of different shapes (e.g., irregular, spherical, etc.) and / or different D 50 The median particle size may be approximately 0.8 micrometers to approximately 100 micrometers. In this example, the one-component dispenseable material is a one-component dispenseable thermal interface material having a thermal conductivity of at least 6 watts per meter per kelvin (W / mK) (e.g., at least approximately 6.2 W / mK) and a stable flow rate in the range of 90 grams / min to 125 grams / min for at least 180 days.

[0017] Figure 6 is a line graph of flow rate (grams / minute (g / min)) over time (days) for the first and second thermally conductive one-component dispenseables according to exemplary embodiments of the present disclosure. For comparison, Figure 6 also includes results for a conventional thermally conductive one-component dispenseable that does not contain a temperature-activated thixotropic agent. In this embodiment, the flow rate was measured using a 75cc tapered tip, a 3.17 mm (0.125 inch) orifice, and 621 kPa (90 psi). As shown in Figure 6, the first and second thermally conductive one-component dispenseables had significantly higher and more stable flow rates over time than the conventional thermally conductive one-component dispenseable.

[0018] To obtain the flow rate over time shown in Figure 6, each of the first and second thermally conductive one-component dispenseables contained about 1% to about 9% (e.g., about 4.5% by weight) of matrix based on the total weight of the thermally conductive one-component dispenseable. The one-component dispenseable also contained about 85% to about 96% (e.g., about 95% by weight) of thermally conductive filler in the matrix based on the total weight of the thermally conductive one-component dispenseable. The matrix contained a silicone resin such as dimethyl silicone oil. The thermally conductive filler contained one or more zinc oxide fillers (e.g., about 12.5% ​​by weight of zinc oxide filler) and one or more alumina fillers (e.g., about 82.5% by weight of alumina filler). The zinc oxide fillers and alumina fillers had different shapes (e.g., irregular, spherical, etc.) and / or different D 50 The median particle size may be (e.g., about 0.8 micrometers to about 100 micrometers). In this example, each of the first and second thermally conductive one-component dispenseables had a thermal conductivity of at least 6 watts per meter per kelvin (W / mK) (e.g., at least about 6.2 W / mK) and a stable flow rate in the range of 90 grams / min to 125 grams / min for at least 180 days.

[0019] In exemplary embodiments, the composite material comprises a matrix containing a temperature-activated thixotropic agent and one or more fillers. The one or more fillers include one or more thermally conductive fillers, conductive fillers, electromagnetic wave-absorbing fillers, dielectric fillers, and fillers having two or more properties among thermal conductivity, conductivity, dielectricity, and electromagnetic wave absorption. In exemplary embodiments, the composite material includes one or more fillers, including one or more of alumina, zinc oxide, aluminum, carbonyl iron, silicon carbide, boron nitride, silver, aluminum nitride, barium titanate, other typical thermally conductive and / or EMI-absorbing fillers, and combinations thereof. The one or more fillers are in the range of about 0.1 micrometers to about 250 micrometers.50 It may have a median particle size.

[0020] In an exemplary embodiment, the composite material includes a thixotropic agent activated by temperature, a thermal conductive filler, and an EMI absorbing filler in a matrix, such that the composite material includes a multifunctional EMI absorber having a first function of EMI reduction and a second function of thermal management, or vice versa. As an example, the filler may include one or more of functional nanoparticles, conductive fillers, thermal conductive fillers, EMI or microwave absorbing fillers, magnetic fillers, coated fillers, combinations thereof, etc. The filler can be added and mixed into the bulk material including the matrix material, thereby providing a mixture of the filler and the base or matrix material. Examples of fillers include carbon black, boron nitride, nickel cobalt, carbonyl iron, iron silicide, iron particles, iron-chromium compounds, silver, an alloy containing 85% iron, 9.5% silicon and 5.5% aluminum, an alloy containing about 20% iron and 80% nickel, ferrite, magnetic alloys, magnetic powders, magnetic flakes, magnetic particles, nickel-based alloys and powders, chromium alloys, oxides, copper, zinc oxide, alumina, graphite, ceramics, silicon carbide, manganese zinc, glass fibers, carbon nanotubes (e.g., single-walled carbon nanotubes, multi-walled carbon nanotubes, and / or carbon nanostructures, etc.), combinations thereof, and the like. The filler may include one or more of granules, spheroids, microspheres, ellipsoids, irregular spheroids, strands, flakes, powders, nanotubes, and / or any one or all combinations of these shapes. Additionally, exemplary embodiments may also include the same (or different) fillers of different grades (e.g., different sizes, different purities, different shapes, etc.).

[0021] In exemplary embodiments, the composite material contains a temperature-activated thixotropic agent in the matrix, and the composite material has a high thermal conductivity of at least 1 watt per meter per kelvin (W / mK) as measured by a hot-disk thermal constant analyzer. For example, the composite material may have thermal conductivity of 1 W / mK, 2 W / mK, 3 W / mK, 4 W / mK, 5 W / mK, 6 W / mK, or greater than 6 W / mK. To determine the thermal conductivity, a hot-disk instrument can be used that measures thermal conductivity, thermal diffusivity, and specific heat capacity using the transient plane source method. As background, this technique is covered in ISO 22007-2:2008; Part 2 standard. This technique utilizes a special mathematical model that describes thermal conductivity, combined with a plane sensor and electronic equipment that enables the use of this method to measure thermal conductivity properties. This technique typically covers a thermal conductivity range of 0.01 to 500 W / m / K. Transient planar heat source technology typically employs two sample halves flanking a sensor. This method can also be used in a single-sided configuration. This technology is versatile and rapid, covering measurements of solids, pastes, thin films, and liquids. It can test both isotropic and anisotropic materials. The planar sensor contains a continuous double-helix conductive nickel metal etched from a thin foil. The helical nickel is placed between two layers of thin Kapton® polyimide film. During measurement, a constant electrical effect passes through the conductive helical structure, raising the sensor temperature. The generated heat dissipates into the samples on both sides of the sensor at a rate corresponding to the thermal conductivity of the material. By recording the temperature-time response in the sensor, the thermal conductivity, thermal diffusivity, and specific heat capacity of the material can be calculated.

[0022] In an exemplary embodiment, the high thermal conductivity one - part dispensable material includes a thixotropic agent that is activated at the temperatures disclosed herein. The high thermal conductivity one - part dispensable material is configured to be suitable for automation and has vertical stability and reliability when used in various application directions. In addition to providing application flexibility and various gap conformability, the high thermal conductivity one - part dispensable material can be configured to exert reduced (e.g., minimized, etc.) stress on components while maintaining increased (e.g., maximized, etc.) interfacial contact. Exemplary embodiments of the high thermal conductivity one - part dispensable materials and other composite materials disclosed herein are RoHS compliant, have thermal cycle stability, have low gas evolution according to ASTM E595, have a flammability rating of V - O UL94, have a minimum bond line thickness of about 0.150 millimeters, about 5.5℃cm 2 / W to about 6.5℃cm 2 / W within the range of thermal impedance, a thermal conductivity of at least 6 W / mK, and a high and stable flow rate (e.g., at least about 100 grams per minute over at least 180 days, etc.) and can be configured to have. In this example, the flow rate can be measured using a 75 cc tapered tip, a 3.17 mm (0.125 inch) orifice, and 621 kPa (90 psi).

[0023] Exemplary embodiments of composite materials useful for the management of heat and / or electromagnetic interference (EMI) are disclosed. In an exemplary embodiment, the composite material includes a matrix, one or more fillers within the matrix, and a thixotropic agent that is activated at a temperature within the matrix. The thixotropic agent activated at a temperature can be activated when the composite material is heated to a predetermined minimum temperature for at least a predetermined minimum time, whereby the activation of the thixotropic agent activated at a temperature increases the flow rate and flow stability over time of the composite material.

[0024] In an exemplary embodiment, the thixotropic agent activated at a temperature can be activated when the composite material is heated to a temperature of at least 80℃ for at least 15 minutes. In exemplary embodiments, a temperature-activated thixotropic agent is configured to undergo physical or chemical transformations that alter its structure or phase and / or induce or enhance its thixotropic behavior, thereby improving the flow characteristics of the composite material when it is heated to a predetermined minimum temperature for at least a predetermined minimum time.

[0025] In an exemplary embodiment, the composite material is configured to have a flow rate of at least 95 grams / minute for at least 180 days. In an exemplary embodiment, the composite material is configured to have a stable flow rate in the range of 90 grams / min to 125 grams / min for at least 180 days.

[0026] In exemplary embodiments, the temperature-activated thixotropic agent is configured to increase the flow rate and flow rate stability over time of the composite material, such that the composite material has a higher and more stable flow rate over time compared to another composite material having substantially the same formulation but without a temperature-activated thixotropic agent.

[0027] In exemplary embodiments, the composite material comprises a thixotropic agent activated at a temperature of about 0.1 to about 0.5 weight percent relative to the total weight of the composite material. For example, the composite material may comprise about 0.1 to about 0.5 weight percent of a powdered amide wax-based thixotropic agent. The composite material may also comprise about 1 to about 9 weight percent (e.g., about 4.5 weight percent) of a matrix based on the total weight of the composite material, and about 85 to about 96 weight percent (e.g., about 95 weight percent) of a thermally conductive filler in the matrix based on the total weight of the composite material. The matrix may comprise a silicone resin (e.g., dimethyl silicone oil). The thermally conductive filler may comprise one or more zinc oxide fillers (e.g., about 12.5 weight percent of zinc oxide filler) and one or more alumina fillers (e.g., about 82.5 weight percent of alumina filler), where these fillers have different shapes (e.g., irregular, spherical, etc.) and / or different D 50 The median particle size may be approximately 0.8 micrometers to approximately 100 micrometers. In this example, the composite material may be a one-component, dispensable thermal interface material having a thermal conductivity of at least 6 watts per meter per kelvin (W / mK) and a stable flow rate in the range of 90 grams / min to 125 grams / min for at least 180 days.

[0028] In exemplary embodiments, the composite material is a one-component dispenseable. In exemplary embodiments, the composite material is a one-component, dispenseable thermal interface material having a thermal conductivity of at least 6 watts per meter per kelvin (W / mK) and a stable flow rate in the range of 90 grams / min to 125 grams / min for at least 180 days.

[0029] In exemplary embodiments, one or more fillers include one or more of zinc oxide, aluminum oxide, boron nitride, aluminum, silicon carbide, and / or aluminum nitride.

[0030] In exemplary embodiments, the composite material includes one or more of the following: a thermally conductive filler, a conductive filler, an electromagnetic wave absorbing filler, a dielectric filler, and fillers having two or more properties among thermal conductivity, conductivity, dielectricity, and electromagnetic wave absorption.

[0031] In exemplary embodiments, a device or system comprising a composite material disclosed herein. Furthermore, methods for improving the flow characteristics of composite materials useful for controlling thermal and / or electromagnetic interference (EMI) are disclosed. In an exemplary method, the flow rate of the composite material is increased and the flow stability over time is enhanced by using a temperature-activated thixotropic agent.

[0032] In an exemplary method, a temperature-activated thixotropic agent is added to the matrix of a composite material such that the composite material comprises a matrix, one or more fillers in the matrix, and a temperature-activated thixotropic agent in the matrix. The method then includes activating the temperature-activated thixotropic agent in the matrix of the composite material by heating the composite material.

[0033] In an exemplary method, the composite material is heated to a predetermined minimum temperature for at least a predetermined minimum time in order to activate a temperature-activated thixotropic agent. For example, the composite material may be heated to a temperature of at least 80°C (e.g., a temperature in the range of 80°C to 100°C) for at least 15 minutes in order to activate a temperature-activated thixotropic agent.

[0034] In an exemplary method, a composite material is heated to activate a temperature-activated thixotropic agent, thereby altering the structure or phase of the temperature-activated thixotropic agent and / or subjecting it to a physical or chemical transformation that induces or enhances the thixotropic behavior of the temperature-activated thixotropic agent, thereby improving the flow characteristics of the composite material.

[0035] In an exemplary method, the use of a temperature-activated thixotropic agent increases the flow rate of the composite material and enhances its flow stability over time, such that the composite material is configured to have a flow rate of at least 95 grams / min for at least 180 days.

[0036] In an exemplary method, the use of a temperature-activated thixotropic agent increases the flow rate of the composite material and enhances its flow rate stability over time, such that the composite material has a stable flow rate in the range of 90 grams / min to 125 grams / min for at least 180 days.

[0037] In an exemplary method, the use of a temperature-activated thixotropic agent increases the flow rate of the composite material and enhances its flow rate stability over time, resulting in a composite material with a higher flow rate that is more stable over time compared to another composite material having substantially the same formulation but without a temperature-activated thixotropic agent.

[0038] In exemplary methods, the composite material comprises a thixotropic agent activated at a temperature of about 0.1 to about 0.5 weight percent based on the total weight of the composite material. For example, the composite material may comprise about 0.1 to about 0.5 weight of a powdered thixotropic agent based on an amide wax. The composite material may also comprise about 1 to about 9 weight percent (e.g., about 4.5 weight percent) of a matrix based on the total weight of the composite material, and about 85 to about 96 weight percent (e.g., about 95 weight percent) of a thermally conductive filler in the matrix based on the total weight of the composite material. The matrix may comprise a silicone resin (e.g., dimethyl silicone oil). The thermally conductive filler may comprise one or more zinc oxide fillers (e.g., about 12.5 weight percent of zinc oxide filler) and one or more alumina fillers (e.g., about 82.5 weight percent of alumina filler), where these fillers have different shapes (e.g., irregular, spherical, etc.) and / or different D 50The median particle size may be approximately 0.8 micrometers to approximately 100 micrometers. In this example, the composite material may be a one-component, dispensable thermal interface material having a thermal conductivity of at least 6 watts per meter per kelvin (W / mK) and a stable flow rate in the range of 90 grams / min to 125 grams / min for at least 180 days.

[0039] In exemplary embodiments, the composite material is a one-component dispenseable. In exemplary embodiments, the composite material is a one-component, dispensable thermal interface material having a thermal conductivity of at least 6 watts per meter per kelvin (W / mK) and a stable flow rate in the range of 90 grams / min to 125 grams / min for at least 180 days. The method may include dispensing the one-component, dispensable thermal interface material between a first component and a second component. The first and second components may include one or more of the following: a heat removal / dissipation structure such as a heat sink, heat spreader, heat pipe, vapor chamber, external case, housing, or chassis of a device; a heat source for an electronic device such as an integrated circuit or other component of an electronic device; and / or a board-level shield.

[0040] In exemplary embodiments, the electronic device includes a heat source and a composite material, such as those disclosed herein, which can be used as a one-component, dispensable thermal interface material having high thermal conductivity (e.g., at least 6 W / mK) and high, stable flow rate (e.g., 90 g / min to 125 g / min for at least 180 days). The composite material is dispensed (broadly speaking, placed) to the heat source to establish at least a portion of a thermally conductive heat path from the heat source through the composite material. The composite material may also be configured to be EMI-absorbing and / or conductive, and as a result, the composite material may also be operable to mitigate and / or manage EMI within the electronic device.

[0041] In exemplary embodiments, the electronic device includes a heat source, a heat removal / dissipation structure, and a composite material disclosed herein that can be used as a one-component, dispensable thermal interface material having high thermal conductivity (e.g., at least 6 W / mK, etc.) and high, stable flow rate (e.g., 90 g / min to 125 g / min, etc. for at least 180 days). The composite material is dispensed (broadly speaking, placed) to the heat source and the heat removal / dissipation structure to establish at least a portion of a thermally conductive heat path between the heat source and the heat removal / dissipation structure. The composite material may also be configured to be EMI absorbing and / or conductive, and as a result, the composite material may also operate to mitigate and / or manage EMI within the electronic device.

[0042] In exemplary embodiments, the electronic device includes a heat source, a board-level shield, and a composite material disclosed herein, which can be used as a one-component, dispensable thermal interface material having high thermal conductivity (e.g., at least 6 W / mK, etc.) and high, stable flow rate (e.g., 90 g / min to 125 g / min, etc. for at least 180 days). The composite material is dispensed (broadly speaking, placed) to the heat source and the board-level shield to establish at least a portion of a thermally conductive heat path between the heat source and the board-level shield. The composite material may also be configured to be EMI-absorbing and / or conductive, and as a result, the composite material may also be operable to mitigate and / or manage EMI within the electronic device.

[0043] In exemplary embodiments, the electronic device includes a heat source, a board-level shield, a heat removal / dissipation structure, and first and second composite materials usable as one-component, dispensable thermal interface materials having high thermal conductivity (e.g., at least 6 W / mK) and high, stable flow rate (e.g., 90 g / min to 125 g / min for at least 180 days). The first composite material is dispensed (broadly speaking, placed) with respect to the heat source and the board-level shield to establish at least a portion of a first thermally conductive heat path between the heat source and the board-level shield. The second composite material is dispensed (broadly speaking, placed) with respect to the board-level shield and the heat removal / dissipation structure to establish at least a portion of a second thermally conductive heat path between the board-level shield and the heat removal / dissipation structure. The first and / or second composite materials may also be configured to be EMI absorbing and / or conductive, and as a result, the first and / or second composite materials may also be operable to mitigate and / or manage EMI within the electronic device.

[0044] In exemplary embodiments, the electronic device includes an integrated circuit, a board-level shield, a heat sink, and first and second composite materials usable as a one-component, dispensable thermal interface material having high thermal conductivity (e.g., at least 6 W / mK) and high, stable flow rate (e.g., 90 g / min to 125 g / min for at least 180 days). The first composite material is dispensed (broadly speaking, placed) with respect to the integrated circuit and the board-level shield to establish at least a portion of a first thermally conductive heat path between the integrated circuit and the board-level shield. The second composite material is dispensed (broadly speaking, placed) with respect to the board-level shield and the heat sink to establish at least a portion of a second thermally conductive heat path between the board-level shield and the heat sink. The first and / or second composite materials may also be configured to be EMI-absorbing and / or conductive, and as a result, the first and / or second composite materials may also be operable to mitigate and / or manage EMI within the electronic device.

[0045] The exemplary embodiments disclosed herein can be used in a wide range of industries (e.g., automotive, consumer goods, industrial, data communications / telecommunications, aerospace / defense, etc.) and a wide range of applications (e.g., automotive electronics, automotive advanced driver-assistance systems (ADAS), automotive powertrain / electronic control units (ECUs), automotive infotainment, routers, hard disk drives, solid-state drives, wireless infrastructure, drones / satellites, gaming systems, smart home devices, notebooks / tablets / portable devices, etc.). Furthermore, the exemplary embodiments disclosed herein can be used in a wide range of heat sources, electronic devices, and / or heat removal / dissipation structures or components (e.g., heat spreaders, heat sinks, heat pipes, vapor chambers, external cases, housings, or chassis of devices, etc.). For example, a heat source may include one or more heat-generating components or devices, such as high-power integrated circuits (ICs), optical transceivers, 5G infrastructure devices (e.g., base stations, small cells, smart poles, etc.), solid-state drives (SSDs), video card memory, set-top boxes, televisions, game systems, automotive electronics used in autonomous driving (ADAS) (e.g., radar, multi-domain controllers, cameras, etc.), CPUs, underfill dies, semiconductor devices, flip-chip devices, graphics processing units (GPUs), digital signal processors (DSPs), multiprocessor systems, integrated circuits (ICs), multi-core processors, etc. Typically, a heat source may include any component or device that provides or transfers heat to the thermal management and / or EMI mitigation material, whether it has a higher temperature than the thermal management and / or EMI mitigation material, or whether the heat source generates heat or simply transfers heat through or via the heat source. Accordingly, aspects of this disclosure should not be limited to use with a single type of heat source, electronic device, heat removal / dissipation structure, etc.

[0046] Exemplary embodiments are provided to ensure that the disclosure is sufficient and fully conveys its scope to those skilled in the art. Numerous specific details are given, such as examples of certain components, devices, and methods, in order to provide a full understanding of the embodiments of the disclosure. It will be apparent to those skilled in the art that the use of these specific details is not necessary, that the exemplary embodiments can be embodied in many different forms, and that neither should be construed as limiting the scope of the disclosure. In some exemplary embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. Furthermore, any advantages and improvements that can be achieved in one or more exemplary embodiments of the disclosure are provided for illustrative purposes only, and the exemplary embodiments of the disclosure do not limit the scope of the disclosure, as they may provide all or none of the above advantages and improvements and are still within the scope of the disclosure.

[0047] The specific dimensions, specific materials, and / or specific shapes disclosed herein are illustrative in nature and do not limit the scope of this disclosure. The disclosure herein regarding specific values ​​and specific ranges of values ​​for a given parameter does not preclude other values ​​and ranges of values ​​that may be useful in one or more examples disclosed herein. Furthermore, it is assumed that any two specific values ​​of a particular parameter described herein may define an endpoint of a range of values ​​that may be suitable for the given parameter (i.e., the disclosure of a first and second value for a given parameter may be interpreted as disclosing that any value between the first and second values ​​may be used for that given parameter). For example, if parameter X is illustrated herein as having value A and also illustrated as having value Z, it is assumed that parameter X may have a range of values ​​from about A to about Z. Similarly, the disclosure of two or more ranges of values ​​for a parameter (whether such ranges are nested, overlapping, or distinct) is assumed to encompass all possible combinations of ranges of values ​​that may be claimed using the disclosed range endpoints. For example, if parameter X is exemplified herein as having values ​​in the range of 1 to 10, or 2 to 9, or 3 to 8, it is also conceivable that parameter X may have values ​​in other ranges, including 1 to 9, 1 to 8, 1 to 3, 1 to 2, 2 to 10, 2 to 8, 2 to 3, 3 to 10, and 3 to 9.

[0048] The terms used herein are for illustrative purposes only and are not intended to limit any particular exemplary embodiment. For example, where permissive phrases such as “may include” or “may include” are used herein, at least one embodiment includes that feature. As used herein, the singular “one” and “it” are also intended to include the plural unless the context clearly indicates otherwise. The terms “include,” “contain,” and “have” are inclusive and thus identify the presence of the described feature, integer, step, operation, element, and / or component, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. The method steps, processes, and operations described herein should not be construed as necessarily requiring their performance in a particular order described or illustrated unless specifically identified as an order of performance. It should also be understood that additional or alternative steps may be employed.

[0049] When an element or layer is described as "on top of," "engaged with," "connected to," or "joined to" another element or layer, it may be directly on top of, engaged with, connected to, or joined to that other element or layer, or there may be an intervening element or layer. In contrast, when an element is described as "directly on top of," "directly engaged with," "directly connected to," or "directly joined to" another element or layer, there may be no intervening element or layer. Other words used to describe relationships between elements should be interpreted in a similar manner (e.g., "between" and "directly between," "adjacent" and "directly adjacent"). As used herein, the term "and / or" includes any and all combinations of one or more of the listed items relating to it.

[0050] When applied to a value, the term “approximately” indicates that the calculation or measurement allows for a slight inaccuracy in the value (depending on the approach to the accuracy of the value; nearly or reasonably close to the value; approximately). Where for any reason the inaccuracy provided by “approximately” is not understood in this ordinary sense in the Art, “approximately” as used herein indicates at least the variation that may arise from the ordinary methods of measuring or using such a parameter. For example, the terms “approximately,” “approximately,” and “substantially” may be used herein to mean within manufacturing tolerances. Alternatively, for example, when the term “approximately” as used herein is used to modify the amount of an ingredient or reactant of the Invention, for example, through careless errors in typical measurement and handling procedures used when producing concentrates or solutions in the real world; or through differences in the production, source, or purity of the ingredients used to make a composition or to carry out a method; the variation in the numerical value that may occur. The term “approximately” also encompasses different amounts due to different equilibrium conditions of compositions resulting from a particular initial mixture. Quantities include equivalent amounts, whether modified by the term “approximately.”

[0051] Terms such as "first," "second," and "third" may be used herein to describe various elements, components, regions, layers, and / or sections, but these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms may only be used to distinguish one element, component, region, layer, or section from another region, layer, or section. As used herein, terms such as "first," "second," and other numerical terms do not imply order or sequence unless explicitly indicated by the context. Thus, a first element, component, region, layer, or section discussed below may be referred to as a second element, component, region, layer, or section without departing from the teaching of the exemplary embodiments.

[0052] Spatially relative terms such as “inside,” “outside,” “down,” “below,” “underside,” “up,” and “above” may be used herein to facilitate the description of the relationship between one element or feature and another, as shown in the figures. Spatially relative terms may be intended to include different orientations of the device in use or operation, in addition to the orientation shown in the figures. For example, if the device in the figure is turned upside down, an element described as “below” or “below” another element or feature becomes “above” that other element or feature. Thus, the term “down” as an example may include both up and down directions. The device may be oriented in a different way (rotated 90 degrees or in other directions), and the spatially relative descriptors used herein may be interpreted accordingly.

[0053] The foregoing description of embodiments is provided for illustrative and descriptive purposes only. It is not intended to be exhaustive or to limit the disclosure. Individual elements, intended or described uses, or features of a particular embodiment are not typically limited to that particular embodiment, but are interchangeable where applicable and can be used in selected embodiments even if not specifically shown or described. The same can also be modified in many ways. Such variations should not be considered deviations from the disclosure, and all such modifications are intended to be within the scope of the disclosure.

Claims

1. A composite material useful for controlling heat and / or electromagnetic interference (EMI), The Matrix and One or more fillers in the matrix, A composite material comprising a temperature-activated thixotropic agent in the matrix, wherein the thixotropic agent can be activated by heating the composite material to a predetermined minimum temperature for at least a predetermined minimum time, so that the activation of the temperature-activated thixotropic agent increases the flow rate and flow rate stability over time of the composite material.

2. The composite material according to claim 1, wherein the thixotropic agent activated at the aforementioned temperature can be activated by heating the composite material at a temperature of at least 80°C for at least 15 minutes.

3. The composite material according to claim 1, wherein the thixotropic agent activated at the temperature is configured to undergo a physical or chemical transformation that changes its structure or phase and / or induces or enhances the thixotropic behavior of the thixotropic agent activated at the temperature, thereby improving the flow characteristics of the composite material when it is heated to the predetermined minimum temperature for at least the predetermined minimum time.

4. The composite material according to claim 1, wherein the composite material is configured to have a flow rate of at least 95 grams / minute for at least 180 days.

5. The composite material according to claim 1, wherein the composite material is configured to have a stable flow rate in the range of 90 grams / min to 125 grams / min for at least 180 days.

6. The composite material according to claim 1, wherein the thixotropic agent activated at the temperature is configured to increase the flow rate and flow rate stability over time of the composite material, such that the composite material has a flow rate that is higher and more stable over time compared to another composite material having substantially the same composition but without the thixotropic agent activated at the temperature.

7. The composite material according to any one of claims 1 to 6, wherein the composite material comprises a thixotropic agent activated at the temperature in an amount of about 0.1 weight percent to about 0.5 weight percent relative to the total weight of the composite material.

8. The composite material includes a thermally conductive filler in the matrix, and the composite material is Based on the total weight of the composite material, the matrix comprises approximately 1 weight percent to approximately 9 weight percent, The composite material according to claim 7, wherein the matrix contains about 85% to about 96% by weight of the thermally conductive filler based on the total weight of the composite material.

9. The matrix comprises a silicone resin, The thermally conductive filler comprises one or more zinc oxide fillers and one or more alumina fillers. The thixotropic agent activated at the aforementioned temperature includes a powdered thixotropic agent based on an amide wax. The composite material according to claim 8, wherein the composite material is a one-component, dispensable thermal interface material having a thermal conductivity of at least 6 watts per meter per kelvin (W / mK) and a stable flow rate in the range of 90 grams / min to 125 grams / min for at least 180 days.

10. A composite material according to any one of claims 1 to 6, which is a one-component dispenseable material.

11. The composite material according to any one of claims 1 to 6, wherein the composite material is a one-component, dispensable thermal interface material having a thermal conductivity of at least 6 watts per meter per kelvin (W / mK) and a stable flow rate in the range of 90 grams / min to 125 grams / min for at least 180 days.

12. The composite material according to any one of claims 1 to 6, wherein the one or more fillers include one or more of zinc oxide, aluminum oxide, boron nitride, aluminum, silicon carbide, and / or aluminum nitride.

13. The aforementioned composite material is Thermally conductive filler, conductive filler, Electromagnetic wave absorbing filler, Dielectric fillers, and Fillers having two or more properties among thermal conductivity, electrical conductivity, dielectric properties, and electromagnetic wave absorption. A composite material according to any one of claims 1 to 6, comprising one or more of the following.

14. A device or system comprising the composite material according to any one of claims 1 to 6.

15. A method for improving the flow characteristics of a composite material containing one or more fillers in a matrix, which is useful for controlling thermal and / or electromagnetic interference (EMI), comprising increasing the flow rate of the composite material and increasing the flow rate stability over time by using a temperature-activated thixotropic agent.

16. By using a thixotropic agent activated at the aforementioned temperature, it is possible to increase the flow rate of the composite material and enhance its flow rate stability over time. The composite material comprises the matrix, one or more fillers in the matrix, and a thixotropic agent activated at the temperature in the matrix, by adding the thixotropic agent activated at the temperature to the matrix of the composite material, and The method according to claim 15, comprising heating the composite material to activate a thixotropic agent in the matrix of the composite material that is activated at the temperature.

17. The method according to claim 15, wherein increasing the flow rate of the composite material and increasing the flow rate stability over time by using a thixotropic agent that is activated at the aforementioned temperature includes activating the thixotropic agent that is activated at the aforementioned temperature by heating the composite material.

18. The method according to claim 17, wherein activating the thixotropic agent activated at the temperature by heating the composite material includes activating the thixotropic agent activated at the temperature by heating the composite material to a predetermined minimum temperature for at least a predetermined minimum time.

19. The method according to claim 18, wherein activating a thixotropic agent that is activated at a certain temperature by heating the composite material to a predetermined minimum temperature for at least a predetermined minimum time is further comprising activating a thixotropic agent that is activated at a certain temperature by heating the composite material to a temperature of at least 80°C for at least 15 minutes.

20. The method according to claim 17, wherein heating the composite material activates a thixotropic agent that is activated at the temperature, thereby changing the structure or phase of the thixotropic agent that is activated at the temperature, and / or subjecting it to a physical or chemical transformation that induces or enhances the thixotropic behavior of the thixotropic agent that is activated at the temperature, thereby improving the flow characteristics of the composite material.

21. The method according to claim 15, further comprising configuring the composite material to have a flow rate of at least 95 grams / min for at least 180 days by using a thixotropic agent activated at the temperature to increase the flow rate of the composite material and to increase the flow rate stability over time.

22. The method according to claim 15, further comprising using a thixotropic agent activated at the temperature to increase the flow rate of the composite material and to increase the flow rate stability over time, thereby configuring the composite material to have a stable flow rate in the range of 90 grams / min to 125 grams / min for at least 180 days.

23. The method according to claim 15, wherein increasing the flow rate of the composite material and increasing the flow rate stability over time by using a thixotropic agent activated at the aforementioned temperature includes adding a thixotropic agent activated at the aforementioned temperature to the matrix of the composite material such that the composite material comprises the matrix, one or more fillers in the matrix, and a thixotropic agent activated at the aforementioned temperature in the matrix.

24. The method according to claim 15, comprising increasing the flow rate and flow rate stability over time of the composite material by using a thixotropic agent activated at the aforementioned temperature, such that the composite material has a higher flow rate over time and is more stable over time compared to another composite material having substantially the same formulation but without a thixotropic agent activated at the aforementioned temperature.

25. The method according to any one of claims 15 to 24, wherein the composite material comprises a thixotropic agent activated at the temperature in an amount of about 0.1 weight percent to about 0.5 weight percent relative to the total weight of the composite material.

26. The composite material includes a thermally conductive filler in the matrix, and the composite material is Based on the total weight of the composite material, the matrix comprises approximately 1 weight percent to approximately 9 weight percent, The method according to claim 25, wherein the matrix contains about 85 weight percent to about 96 weight percent of the thermally conductive filler based on the total weight of the composite material.

27. The matrix comprises a silicone resin, The thermally conductive filler comprises one or more zinc oxide fillers and one or more alumina fillers. The thixotropic agent activated at the aforementioned temperature includes a powdered thixotropic agent based on an amide wax. The method according to claim 26, wherein the composite material is a one-component, dispensable thermal interface material having a thermal conductivity of at least 6 watts per meter per kelvin (W / mK) and a stable flow rate in the range of 90 grams / min to 125 grams / min for at least 180 days.

28. The method according to any one of claims 15 to 24, wherein the composite material is a one-component dispenseable material.

29. The method according to any one of claims 15 to 24, wherein the composite material is a one-component, dispensable thermal interface material having a thermal conductivity of at least 6 watts per meter per kelvin (W / mK) and a stable flow rate in the range of 90 grams / min to 125 grams / min for at least 180 days.

30. The method includes dispensing the one-component, dispenseable thermal interface material between a first component and a second component, wherein the first component and the second component are Heat removal / dissipation structures such as heat sinks, heat spreaders, heat pipes, vapor chambers, external cases, housings, or chassis of devices. Heat sources of electronic devices such as integrated circuits or other components of electronic devices, and / or Board-level shield The method according to claim 29, comprising one or more of the above.

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