Detailed Description
Example embodiments will now be described more fully hereinafter with reference to the accompanying drawings.
Composite materials including fillers within the matrix may be used in a variety of applications, such as dispensable Thermal Interface Materials (TIMs) and in-place-molded (FIP) products. However, as recognized herein, precipitation of the filler within the matrix can present challenges and prevent the composite from having a long shelf life. If the composite is not dispensed until after a longer period of time, the filler may precipitate within the matrix. For example, the filler may precipitate within the matrix during storage and/or transport of the composite.
Filler precipitation may lead to oil/filler separation and changes in flow rate/viscosity over time (e.g., after storage, etc.), which in turn may lead to poor dispensing properties of the composite. The occurrence of flow rate/viscosity changes over time may hinder and severely limit the use of the composite material. The viscosity/flow rate variation is mainly due to the physical precipitation of the heavier filler in the lighter polymer matrix.
Conventional dispensing equipment adjusts the dispensing pressure to account for viscosity/flow rate variations due to filler settling. With such conventional dispensing apparatus, however, it is necessary to constantly adjust the dispensing pressure. Also, if the oil/filler separation is significantly excessive or extreme, the filler loading may vary greatly in the dispensed material. The functional properties of the dispensed material (e.g., thermal conductivity, electrical conductivity, dielectric absorption, electromagnetic wave absorption, etc.) may be negatively affected by the amount or density of the filler that varies slightly within the dispensed material.
Upon recognizing the above, exemplary embodiments of systems and methods including remixing (e.g., homogeneously remixing, etc.) filler including filler precipitates within a matrix have been developed and/or disclosed herein. After remixing the filler within the matrix (e.g., via a screw extruder, screw kneader, other in-line remixer, etc.), the viscosity/flow rate of the material may thereby be improved and/or restored to its original viscosity/flow rate. For example, the viscosity/flow rate of the remixed material may be about the same as the initial viscosity/flow rate of the material when the filler is initially mixed within the matrix to make the material and before any filler precipitation occurs during the long shelf life. Advantageously, remixing may thus allow the dispensable material to have a longer shelf life prior to dispensing.
Exemplary embodiments of the systems and methods disclosed herein may be used with various thermal management and/or EMI mitigation materials, such as one-piece dispensable materials (e.g., one-piece thermal caulk, etc.), two-piece dispensable materials (e.g., two-piece cure-in-place dispensable Thermal Interface Materials (TIMs), etc.), dispensable TIMs, dispensable EMI shielding materials, dispensable EMI absorbing materials, dispensable thermally conductive EMI absorbers or hybrid heat/EMI absorbers, dispensable materials with high filler loading and/or high viscosity/flow rates, other dispensable materials, and so forth. Thus, aspects of the present disclosure should not be limited to remixing any single type of dispensable material.
In exemplary embodiments, the systems/methods include remixing the dispensable material via an in-line remixer (e.g., screw extruder, screw kneader, other remixing device, etc.) prior to dispensing the dispensable material. The dispensable material can have a high filler loading and/or a high viscosity/flow rate. The dispensable material may comprise a one-piece or two-piece dispensable thermal management and/or EMI mitigation material, such as a one-piece thermal putty, a two-piece cure-in-place TIM, or the like. Remixing of the dispensable material occurs upstream of the material dispenser and occurs prior to feeding, conveying or supplying (e.g., pumping via a high pressure pump, etc.) the dispensable material to the material dispenser. Remixing of the dispensable material may improve or maintain the viscosity/flow rate of the dispensable material. For example, the viscosity/flow rate of the dispensable material may change (e.g., deteriorate, etc.) over time as filler precipitation occurs within the matrix of the dispensable material. In such a case, remixing of the dispensable material may cause the viscosity/flow rate of the dispensable material to change (e.g., improve, recover, etc.) to be about the same as the initial viscosity/flow rate of the dispensable material before filler settling has occurred. Alternatively, remixing of the dispensable material may maintain the viscosity/flow rate of the dispensable material by preventing or avoiding settling of the filler, for example.
In some exemplary embodiments, the dispensable material comprises a one-piece dispensable material (e.g., a one-piece thermal putty, etc.). In such exemplary embodiments, the system/method includes remixing a piece of dispensable material via an in-line remixer (e.g., a screw extruder, screw kneader, other remixing device, etc.) prior to dispensing the piece of dispensable material. Accordingly, the remixing of the one-piece dispensable material is performed upstream of the dispenser and occurs prior to feeding, conveying or supplying (e.g., pumping via a high pressure pump or the like) the one-piece dispensable material to the material dispenser or dispenser. Remixing of a one-piece dispensable material may improve or maintain the viscosity/flow rate of the one-piece dispensable material. For example, the viscosity/flow rate of a one-piece dispensable material may change (e.g., deteriorate, etc.) over time as filler settling occurs within the matrix. In such a case, remixing of a one-piece dispensable material may cause the viscosity/flow rate of the one-piece dispensable material to change (e.g., improve, recover, etc.) to be about the same as the initial viscosity/flow rate of the one-piece dispensable material before filler settling occurs. Alternatively, for example, remixing of a one-piece dispensable material may maintain the viscosity/flow rate of the one-piece dispensable material by preventing or avoiding settling of the filler.
In other exemplary embodiments, the dispensable material comprises a two-part dispensable material (e.g., a two-part cure-in-place dispensable TIM, etc.). In such exemplary embodiments, the system/method includes remixing the two-part dispensable material via an in-line remixer (e.g., screw extruder, screw kneader, other remixing device, etc.) prior to dispensing the two-part dispensable material. The remixing of the two-part dispensable material is carried out upstream of the static remixer and the material dispenser. Accordingly, remixing occurs prior to feeding, conveying or supplying (e.g., pumping via a high pressure pump, etc.) the two-piece dispensable material to the static mixer or material dispenser. Remixing of the two-piece dispensable material may improve or maintain the viscosity/flow rate of the two-piece dispensable material. For example, the viscosity/flow rate of the two-piece dispensable material may change (e.g., deteriorate, etc.) over time as filler settling occurs within the matrix. In such a case, remixing of the two-part dispensable material may cause the viscosity/flow rate of the two-part dispensable material to change (e.g., improve, recover, etc.) to be about the same as the initial viscosity/flow rate of the two-part dispensable material before filler settling has occurred. Alternatively, for example, remixing of a two-part dispensable material may maintain the viscosity/flow rate of the two-part dispensable material by preventing or avoiding settling of the filler.
Fig. 1 illustrates a system 100 for dispensing thermal management and/or EMI mitigation materials in accordance with an exemplary embodiment embodying one or more aspects of the present disclosure. As shown, the system 100 includes an in-line remixing device 104 (broadly, a remixer). The in-line remixing device 104 may include a screw extruder 108, a screw kneader 112, and the like.
The online remixing device 104 may be configured to: receiving a thermal management and/or EMI mitigation material comprising one or more functional fillers supplied into the matrix. The online remixing device 104 may be further configured to: remixing the one or more functional fillers including filler precipitates (if any) within the matrix prior to dispensing the thermal management and/or EMI mitigation material. The remixing may reduce (e.g., eliminate, etc.) the filler precipitation (if any) within the matrix, thereby resulting in improved viscosity and flow rate of the thermal management and/or EMI mitigation material.
The system 100 also includes a pump 116 (e.g., a high pressure pump, etc.) and a dispenser or platform 120 (also referred to as a dispenser). The in-line remixing device 104 is located upstream of the pump 116 such that remixed material from the in-line remixing device 104 is fed to the pump 116. The pump 116 is configured to be operable for pumping or supplying remixed material to a dispensing machine or platform 120.
The dispenser or platform 120 is configured to dispense (e.g., via a nozzle, etc.) the remixed material onto a surface, such as a board level shield, a printed circuit board, an electrical component, a heat source, a heat removal/dissipation structure or component (e.g., a heat sink, a heat spreader, a heat pipe, a device housing or object, etc.), and so forth. For example, the dispenser 120 may dispense the remixed thermal management and/or EMI mitigation material opposite, in close proximity to, and/or adjacent to one or more heat sources and one or more heat extraction/dissipation structures such that the dispensed thermal management and/or EMI mitigation material serves to define or establish at least a portion of a thermally conductive path along which heat may be transferred, generally between the one or more heat sources and the one or more heat extraction/dissipation structures. Alternatively, for example, the dispenser 120 may dispense the remixed thermal management and/or EMI mitigation material opposite, in close proximity to, and/or adjacent to one or more device components such that the dispensed thermal management and/or EMI mitigation material is used to provide EMI mitigation to the one or more device components.
In exemplary embodiments, the systems and methods are configured to remix and dispense a thermal management and/or EMI mitigation material comprising a matrix material (e.g., a polymer matrix material, etc.) and one or more functional fillers within the matrix material. The one or more functional fillers may include thermally conductive fillers, electrically conductive fillers, dielectric absorbing fillers, and/or electromagnetic wave absorbing fillers, and the like.
The one or more functional fillers may include thermally conductive particles, electrically conductive particles, dielectric absorbing particles, electromagnetic wave absorbing particles, and/or particles having two or more of thermally conductive, electrically conductive, and electromagnetic wave absorbing. For example, the one or more functional fillers may include thermally conductive particles comprising one or more of the following materials: zinc oxide, boron nitride, aluminum oxide, aluminum, silicon nitride, aluminum nitride, iron, metal oxides, graphite, silver, copper, ceramics, and/or combinations of these. The one or more functional fillers may include fillers made of iron, ferrite, or the like. The filler may be a dielectric absorber (e.g., carbon black, silicon carbide, etc.). The one or more functional fillers may include EMI absorbing particles, which may include one or more of the following materials: silicon carbide, carbonyl iron, aluminum oxide, manganese zinc ferrite, magnetic flakes, alloys containing about 85% iron, 9.5% silicon, and 5.5% aluminum, alloys containing about 20% iron and 80% nickel, iron silicide, iron chromium compounds, metallic silver, magnetic alloys, magnetic powders, magnetic particles, nickel-based alloys and powders, chromium alloys, MagniF (iron oxide ferrite), and/or combinations of these. The one or more functional fillers may include different grades of the same functional filler particles or different grades of different types of functional filler particles.
In some exemplary embodiments, thermal management and/or EMI mitigation materials may be used for thermal management purposes and EMI attenuation. For example, the thermal management and/or EMI mitigation material may include a thermally conductive microwave absorber that includes functional fillers including silicon carbide, carbonyl iron powder, and alumina. Alternatively, the thermal management and/or EMI mitigation material may include a thermally conductive microwave absorber that includes functional fillers including silicon carbide, carbonyl iron powder, aluminum oxide, manganese zinc ferrite, and magnetic flakes. Alternatively, the functional filler may include alumina, silicon carbide, carbon black, MagniF (iron oxide magnetite), and the like.
In some exemplary embodiments, the functional filler may comprise a substantial portion of the total volume of the thermal management and/or EMI mitigation material. For example, the functional filler may be loaded into the matrix in the following manner: the volume percent (vol%) of the functional filler is about 85 vol% to about 98 vol% (e.g., about 90 vol%, about 98 vol%, greater than 85 vol%, etc.) and/or the weight percent of the functional filler is at least about 90 wt% or more. The volume and weight percentages provided in this paragraph are exemplary only, as other exemplary embodiments may include higher or lower volume and/or weight percentages of the functional filler.
The size of the functional filler may vary, such as a particle size of about 0.01mm to about 1.0mm (e.g., 0.05 mm to 0.5mm, 0.07mm to 0.15mm, etc.). The shape of the functional filler may also vary, such as round, spherical, flake, rod, etc.
In some exemplary embodiments, the system may dispense thermal management and/or EMI mitigation materials to define a portion of a thermally conductive path that may transfer heat, for example, from a heat source to a heat rejection/dissipation structure or component (e.g., a heat sink, heat spreader, heat pipe, device housing or casing, etc.). In general, the heat source may include any component or device (e.g., an integrated circuit, other PCB component, etc.) that has a higher temperature than or otherwise provides or transfers heat to the one-piece curable dispensable thermal management and/or EMI mitigation material, whether generated by or merely transferred through or via the heat source. Accordingly, aspects of the present disclosure should not be limited to any particular use with any single type of heat source, electronic device, heat removal/dissipation structure, or the like.
Accordingly, exemplary embodiments of systems and methods for dispensing thermal management and/or EMI mitigation materials are disclosed. The systems and methods include in-line remixing prior to dispensing the thermal management and/or EMI mitigation material.
In an exemplary embodiment, a system is provided that includes an online remixer configured to be operable to: receiving the thermal management and/or EMI mitigation material comprising one or more functional fillers supplied into the matrix; and remixing the one or more functional fillers including filler precipitates (if any) within the matrix prior to dispensing the thermal management and/or EMI mitigation material. The remixing may reduce the filler precipitation, if any, within the matrix, thereby resulting in improved viscosity and flow rate of the thermal management and/or EMI mitigation material.
The in-line remixer may comprise a screw extruder or a screw kneader. The online remixer may be configured to be operable to: uniformly remixing the one or more functional fillers including any filler precipitates within the matrix such that the viscosity and flow rate of the thermal management and/or EMI mitigation material after the remixing is improved and/or restored to about the same as the initial viscosity and initial flow rate of the thermal management and/or EMI mitigation material prior to any filler precipitates. The system may include a distributor downstream of the inline remixer. The dispenser may be configured to be operable to: dispensing the thermal management and/or EMI mitigation material after remixing the one or more functional fillers including filler precipitates (if any) within the matrix via the in-line remixer. The system may include a pump fluidly coupled to the in-line remixer and the dispenser. The thermal management and/or EMI mitigation material may include at least about 90% by weight of the one or more functional fillers within the matrix. The thermal management and/or EMI mitigation material may comprise a one-piece or two-piece dispensable thermal management and/or EMI mitigation material. The one or more functional fillers may include one or more of the following particles: thermally conductive particles; conductive particles; dielectric absorber particles; electromagnetic wave absorbing particles; and particles having two or more of thermal conductivity, electrical conductivity, dielectric absorption, and electromagnetic wave absorption. The thermal management and/or EMI mitigation material may comprise a one-piece dispensable thermal putty or a two-piece cure-in-place dispensable thermal interface material.
In an exemplary embodiment, a method is provided, the method comprising the steps of: receiving the thermal management and/or EMI mitigation material comprising the one or more functional fillers supplied into the matrix; and remixing the one or more functional fillers including filler precipitates (if any) within the matrix prior to dispensing the thermal management and/or EMI mitigation material. The remixing may reduce (e.g., eliminate, etc.) the filler precipitation (if any) within the matrix, thereby resulting in improved viscosity and flow rate of the thermal management and/or EMI mitigation material.
The method may comprise the steps of: waiting an amount of time sufficient for at least a portion of the one or more functional fillers to precipitate within the matrix. The method may comprise the steps of: remixing the at least a portion of the one or more functional fillers precipitated within the matrix, thereby reducing filler precipitation within the matrix and resulting in improved viscosity and flow rate of the thermal management and/or EMI mitigation material. The method may comprise the steps of: a screw extruder or screw kneader is used to remix the one or more functional fillers including filler precipitates (if any) within the matrix.
The method may comprise the steps of: uniformly remixing the one or more functional fillers including any filler precipitates within the matrix such that the viscosity and flow rate of the thermal management and/or EMI mitigation material after the remixing is improved and/or restored to about the same as the initial viscosity and initial flow rate of the thermal management and/or EMI mitigation material prior to any filler precipitates.
The method may comprise the steps of: the thermal management and/or EMI mitigation material is dispensed after remixing the one or more functional fillers, including filler precipitates if any, within the matrix.
The method may comprise the steps of: allowing at least a portion of the one or more functional fillers to precipitate within the matrix; remixing the at least a portion of the one or more functional fillers precipitated within the matrix, thereby reducing filler precipitation within the matrix and improving the viscosity and flow rate of the thermal management and/or EMI mitigation material to be about the same as the initial viscosity and initial flow rate of the thermal management and/or EMI mitigation material prior to the filler precipitation; and dispensing, after the remixing, the thermal management and/or EMI mitigation material having an improved viscosity and an improved flow rate that are about the same as the initial viscosity and the initial flow rate of the thermal management and/or EMI mitigation material prior to the filler precipitating.
The method may comprise the steps of: initially mixing the one or more functional fillers within the matrix to provide the thermal management and/or EMI mitigation material; and after the initial mixing, causing precipitation of at least a portion of the one or more functional fillers within the matrix, whereby the filler precipitation alters the initial viscosity and initial flow rate of the thermal management and/or EMI mitigation material. The method may comprise the steps of: remixing the at least a portion of the one or more functional fillers precipitated within the matrix, thereby reducing the filler precipitation within the matrix and improving the viscosity and flow rate of the thermal management and/or EMI mitigation material to be about the same as the initial viscosity and initial flow rate of the thermal management and/or EMI mitigation material.
The method may comprise the steps of: waiting for at least a predetermined period of time during which at least a portion of the one or more functional fillers precipitate within the matrix. After waiting the predetermined period of time, the method may comprise the steps of: the at least a portion of the one or more functional fillers precipitated within the matrix is then remixed prior to dispensing the thermal management and/or EMI mitigation material having an improved viscosity and an improved flow rate that are about the same as the initial viscosity and initial flow rate of the thermal management and/or EMI mitigation material.
In this exemplary method, the thermal management and/or EMI mitigation material may include at least about 90% by weight of the one or more functional fillers within the matrix. The thermal management and/or EMI mitigation material may comprise a one-piece or two-piece dispensable thermal management and/or EMI mitigation material. The one or more functional fillers may include one or more of the following particles: thermally conductive particles; conductive particles; dielectric absorber particles; electromagnetic wave absorbing particles; and particles having two or more of thermal conductivity, electrical conductivity, dielectric absorption, and electromagnetic wave absorption. The thermal management and/or EMI mitigation material may comprise a one-piece dispensable thermal putty or a two-piece cure-in-place dispensable thermal interface material.
The method may comprise the steps of: after the remixing, the thermal management and/or EMI mitigation material is dispensed in opposition to, in close proximity to, and/or adjacent to one or more heat sources and one or more heat extraction/dissipation structures such that the dispensed thermal management and/or EMI mitigation material serves to define or establish at least a portion of a thermally conductive path along which heat may be transferred, generally between the one or more heat sources and the one or more heat extraction/dissipation structures.
The method may comprise the steps of: after the remixing, the thermal management and/or EMI mitigation material is dispensed opposite, in close proximity to, and/or adjacent to one or more device components such that the dispensed thermal management and/or EMI mitigation material is used to provide EMI mitigation to the one or more device components.
The example embodiments are provided so that this disclosure will be thorough and will fully convey the scope of the disclosure to those skilled in the art. Numerous specific details are set forth, such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that should not be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. Additionally, the advantages and improvements that may be realized by one or more exemplary embodiments of the present disclosure are provided for illustration only and do not limit the scope of the present disclosure, as the exemplary embodiments disclosed herein may provide all or none of the above advantages and improvements while remaining within the scope of the present disclosure.
Specific dimensions, specific materials, and/or specific shapes disclosed herein are exemplary in nature and do not limit the scope of the disclosure. The disclosure herein of particular values and particular value ranges for a given parameter does not preclude other values or value ranges that may be useful in one or more examples disclosed herein. Moreover, it is contemplated that any two particular values for a particular parameter described herein may specify endpoints that are applicable to a range of values for the given parameter (i.e., the disclosure of a first value and a second value for the given parameter is to be interpreted as disclosing any value between the first value and the second value that is also applicable to the given parameter). For example, if parameter X is exemplified herein as having a value a, and is also exemplified as having a value Z, it is foreseeable that parameter X may have a range of values from about a to about Z. Similarly, it is contemplated that the disclosure of two or more ranges of values for a parameter (whether nested, overlapping, or distinct) encompasses all possible combinations of the ranges of values that may be claimed using the endpoints of the disclosed ranges. For example, if parameter X is exemplified herein as having a value in the range of 1-10 or 2-9 or 3-8, it is also contemplated that parameter X may have other ranges of values including 1-9, 1-8, 1-3, 1-2, 2-10, 2-8, 2-3, 3-10, and 3-9.
The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. For example, when a permissive phrase, such as "may comprise," "may include," or the like, is used herein, at least one embodiment comprises or includes such features. As used herein, a description in the singular may be intended to include the plural unless the context clearly indicates otherwise. The terms "comprises," "comprising," and "having" are intended to be inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude 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 do not have to be performed in the particular order discussed or illustrated herein, unless an order of performance is specifically indicated. It will also be appreciated that additional or alternative steps may be employed.
When a component or layer is referred to as being "on," "engaged to," "connected to" or "coupled to" another component or layer, it can be directly on, engaged, connected or coupled to the other component or layer or intervening components or layers may be present. In contrast, when an element is referred to as being "directly on … …", "directly engaged to", "directly connected to", or "directly coupled to" another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between components should also be construed accordingly (e.g., "between" and "directly between … …," "adjacent" and "directly adjacent"), etc. As used herein, the term "and/or" includes any one or more of the associated items and all combinations thereof.
The term "about" when applied to a value means that some minor inaccuracy in the calculation or measurement of the value is allowed (the value is close to exact; about approximate or reasonable; nearly). Otherwise, if for some reason the imprecision provided by "about" is not otherwise understood in the art with this ordinary meaning, then "about" as used herein at least indicates a variation that may result from ordinary methods of measuring or using such parameters. For example, the terms "approximately", "about" and "substantially" may be used herein to mean within manufacturing tolerances. Or, for example, the term "about" as used herein when modifying the amount of an ingredient or reactant of the invention or employed refers to the amount of change that can occur through typical measurement and handling procedures used (e.g., through inadvertent errors in such procedures in preparing concentrates or solutions in the real world; differences in manufacture, source, or purity of ingredients employed by preparing compositions or performing methods; etc.). The term "about" also encompasses amounts that differ due to different equilibrium conditions of the resulting composition for a particular initial mixture. The claims include equivalents to the quantities whether or not modified by the term "about".
Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as "first," "second," and other numerical terms used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first component, region, layer or section discussed below could be termed a second component, region, layer or section without departing from the teachings of the example embodiments.
Spatially relative terms, such as "inner," "outer," "below," "lower," "over," "upper," and the like, may be used herein for ease of description to describe one element or feature's relationship to another element or feature as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the example term "below" can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
The foregoing description of the embodiments has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual components, intended or described uses, or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, may be interchanged and used in a selected embodiment (even if not specifically shown or described). These embodiments may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.