WO2019161282A1 - Matériaux d'interface thermique à pertes diélectriques élevées et à constantes diélectriques faibles - Google Patents

Matériaux d'interface thermique à pertes diélectriques élevées et à constantes diélectriques faibles Download PDF

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Publication number
WO2019161282A1
WO2019161282A1 PCT/US2019/018325 US2019018325W WO2019161282A1 WO 2019161282 A1 WO2019161282 A1 WO 2019161282A1 US 2019018325 W US2019018325 W US 2019018325W WO 2019161282 A1 WO2019161282 A1 WO 2019161282A1
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WO
WIPO (PCT)
Prior art keywords
thermal interface
interface material
heat
thermal
dielectric constant
Prior art date
Application number
PCT/US2019/018325
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English (en)
Inventor
Paul F. Dixon
Original Assignee
Laird Technologies, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Laird Technologies, Inc. filed Critical Laird Technologies, Inc.
Publication of WO2019161282A1 publication Critical patent/WO2019161282A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K5/00—Heat-transfer, heat-exchange or heat-storage materials, e.g. refrigerants; Materials for the production of heat or cold by chemical reactions other than by combustion
    • C09K5/08—Materials not undergoing a change of physical state when used
    • C09K5/14—Solid materials, e.g. powdery or granular

Definitions

  • the present disclosure relates to thermal interface materials having high dielectric losses and low dielectric constants.
  • Electrical components such as semiconductors, integrated circuit packages, transistors, etc ., typically have pre-designed temperatures at which the electrical components optimally operate. Ideally, the pre-designed temperatures approximate the temperature of the surrounding air. But the operation of electrical components generates heat. If the heat is not removed, the electrical components may then operate at temperatures significantly higher than their normal or desirable operating temperature. Such excessive temperatures may adversely affect the operating characteristics of the electrical components and the operation of the associated device.
  • the heat should be removed, for example, by conducting the heat from the operating electrical component to a heat sink.
  • the heat sink may then be cooled by conventional convection and/or radiation techniques.
  • the heat may pass from the operating electrical component to the heat sink either by direct surface contact between the electrical component and heat sink and/or by contact of the electrical component and heat sink surfaces through an intermediate medium or thermal interface material (TIM).
  • TIM thermal interface material
  • the thermal interface material may be used to fill the gap between thermal transfer surfaces, in order to increase thermal transfer efficiency as compared to having the gap filled with air, which is a relatively poor thermal conductor.
  • EMI/RFI interference may cause degradation or complete loss of important signals, thereby rendering the electronic equipment inefficient or inoperable.
  • a common solution to ameliorate the effects of EMI/RFI is through the use of shields capable of absorbing and/or reflecting and/or redirecting EMI energy. These shields are typically employed to localize EMI/RFI within its source, and to insulate other devices proximal to the EMI/RFI source.
  • EMI as used herein should be considered to generally include and refer to EMI emissions and RFI emissions
  • electromagnétique should be considered to generally include and refer to electromagnetic and radio frequency from external sources and internal sources.
  • shielding broadly includes and refers to mitigating (or limiting) EMI and/or RFI, such as by absorbing, reflecting, blocking, and/or redirecting the energy or some combination thereof so that it no longer interferes, for example, for government compliance and/or for internal functionality of the electronic component system.
  • FIG. 1 shows a modeled system in which the excitation source is a loop antenna realized on a PCB substrate.
  • FIG. 2 is a line graph of Total Radiated Power in decibels-milliwatt (dBm) versus frequency from 1 GHz to 6 GHz, which includes values calculated using the modeled system shown in FIG. 1 without a thermal interface material (TIM) between the source and heat sink, and also with a TIM having a dielectric constant (K) equal to 7 positioned between the source and heat sink.
  • TIM thermal interface material
  • K dielectric constant
  • FIG. 3 is a line graph of Total Radiated Power (in dBm) versus frequency from 1 GHz to 6 GHz, which includes the calculated values shown in FIG. 2.
  • FIG. 3 also includes calculated values using the modeled system shown in FIG. 1 with a TIM having a dielectric constant (K) equal to 3 positioned between the source and heat sink.
  • K dielectric constant
  • FIG. 4 also includes calculated values using the modeled system shown in FIG. 1 with a TIM having a dielectric constant equal to 3 and a loss tangent equal to 0.5 (a complex permittivity of 3-j 1.5) positioned between the source and heat sink.
  • FIG. 4 also includes calculated values using the modeled system shown in FIG. 1 with a TIM having a dielectric constant equal to 3 and a loss tangent equal to 0.5 (a complex permittivity of 3-j 1.5) positioned between the source and heat sink.
  • FIG. 1 is a line graph of Total Radiated Power (in dB
  • Electromagnetic energy radiated by a source can couple to a heat sink. If the electromagnetic energy is at a resonant frequency of the system, the heat sink will act as an efficient antenna and radiate. The resonant frequencies are dependent on the dimensions of the heat sink and the dielectric constant of the thermal interface material. Conventionally, thermal interface materials generally have low dielectric losses in the radio frequency (RF)/microwave range. It is commonly believed that a thermal interface material (TIM) with a lower dielectric constant will reduce EMI from a heat sink/TIM combination.
  • RF radio frequency
  • TIM thermal interface material
  • TIMs with high dielectric losses may reduce EMI from resonances created by the capacitance of a heat sink and a heat source (e.g ., a printed circuit board/integrated circuit PCB/IC, etc.). Accordingly, disclosed herein are exemplary embodiments of thermal interface materials having high dielectric losses and low dielectric constants.
  • FIG. 1 shows a modeled system in which the excitation source is a loop antenna realized on a PCB substrate.
  • FIG. 2 is a line graph of Total Radiated Power in decibels-milliwatt (dBm) versus frequency from 1 GHz to 6 GHz, which values were calculated using the modeled system shown in FIG. 1 without a thermal interface material (TIM) between the source and heat sink and also with a TIM having a dielectric constant equal to 7 positioned between the source and heat sink.
  • FIG. 2 also indicates the frequency of 2.5 GHz, which is in the WiFi band.
  • FIG. 2 shows that the effect of the TIM with a dielectric constant of 7 is to pull the first resonance down into the WiFi band (as shown by the arrow).
  • FIG. 3 is a line graph of Total Radiated Power (in dBm) versus frequency from 1 GHz to 6 GHz.
  • FIG. 3 includes the calculated values shown in FIG. 2 and calculated values using the modeled system shown in FIG. 1 with a TIM having a dielectric constant equal to 3 positioned between the source and heat sink.
  • FIG. 3 shows the reduction in total radiated power caused by the shift in resonant frequency to a higher frequency (as shown by the arrow) using the lower dielectric constant TIM.
  • FIG. 4 is a line graph of Total Radiated Power (in dBm) versus frequency from 1 GHz to 6 GHz.
  • FIG. 4 also includes calculated values using the modeled system shown in FIG. 1 with a TIM having a dielectric constant equal to 3 and a loss tangent equal to 0.5 (a complex permittivity of 3-j 1.5) positioned between the source and heat sink.
  • FIG. 4 shows that the TIM with high dielectric loss effectively reduced all resonances (as shown by the arrow) from 1 to 6 GHz.
  • the effect is more dramatic when we expand the frequency range to 18 GHz as shown in FIG. 5, which is a line graph of Total Radiated Power (in dBm) versus frequency from 0 GHz to 18 GHz.
  • a thermal interface material may have a dielectric constant within a range from about 3 to about 20 (e.g ., 3, 4.5, 20, 10, greater than 3 but less than 20, etc.) and a loss tangent within a range from about 0.10 to about 1.0 (e.g., 0.10, 0.50, 1.0, greater than 0.1 but less than 1.0, etc.).
  • the values for dielectric constant and loss tangent may be measured at room temperature of 21 degrees Celsius (°C) at frequencies from about 1 GHz to about 18 GHz.
  • the thermal interface material may be relatively soft and/or have a relatively high thermal conductivity (e.g, 1 watts per meter per Kelvin (W/mK) or more, etc.).
  • the thermal interface material (e.g, a dielectrically lossy thermal interface material, a thermally-conductive EMI absorber, etc.) includes a matrix loaded with dielectrically lossy filler.
  • the matrix comprises silicone elastomer, hydrocarbon resin, epoxy, and/or other matrix material(s) loaded with the dielectrically lossy filler.
  • the dielectrically lossy filler comprises alumina, silicon carbide, carbon black, and/or other filler(s).
  • the thermal interface material (e.g ., a dielectrically lossy thermal interface material, a thermally-conductive EMI absorber, etc.) includes a blend of silicon carbide, carbon black, alumina, and/or other filler.
  • the thermal interface material includes about 3 to 10 volume percent of silicone carbide (e.g., 3 volume percent of silicone carbide, 10 volume percent of silicone carbide, greater than 3 but less than 10 volume percent of silicone carbide, etc.), about 3 to 10 volume percent of carbon black (e.g, 3 volume percent of carbon black, 10 volume percent of carbon black, greater than 3 but less than 10 volume percent of carbon black, etc.), and about 18 to 23 volume percent of alumina (e.g, 18 volume percent of alumina, 23 volume percent of alumina, greater than 18 but less than 23 volume percent of alumina, etc.).
  • silicone carbide e.g., 3 volume percent of silicone carbide, 10 volume percent of silicone carbide, greater than 3 but less than 10 volume percent of silicone carbide, etc.
  • carbon black e.g, 3 volume percent of carbon black, 10 volume percent of carbon black, greater than 3 but less than 10 volume percent of carbon black, etc.
  • 18 to 23 volume percent of alumina e.g, 18 volume percent of alumina, 23 volume
  • a method generally includes positioning and/or using a thermal interface material having a high dielectric loss and a low dielectric constant generally between one or more heat sources and one or more heat removal/dissipation structures or components (e.g, a heat spreader, a heat sink, a heat pipe, a device exterior case or housing, etc.).
  • the thermal interface material may establish a thermal joint, interface, pathway, or thermally-conductive heat path along which heat may be transferred (e.g, conducted) from the heat source to the heat removal/dissipation structure or component.
  • a method generally includes positioning and/or using a thermal interface material having a relatively low dielectric constant (e.g, within a range from about 3 to about 20, etc.) and a relatively low loss tangent (e.g, within a range from about 0.10 to about 1.0, etc.) generally between a heat sink and a heat source.
  • the thermal interface material may reduce EMI from the heat sink/TIM combination and/or reduce EMI from resonances created by the capacitance of the heat sink and the heat source (e.g, a printed circuit board/integrated circuit PCB/IC, etc.).
  • the heat source e.g, a printed circuit board/integrated circuit PCB/IC, etc.
  • the thermal interface material may include a matrix loaded with filler materials with volume filler loadings ranging from about 5% to about 98% (e.g., 5%, 98%, percentage greater than 5% but less than 98%, etc.).
  • the matrix may comprise a silicone matrix in which are dispersed thermally-conductive filler and/or EMI absorbing filler.
  • Exemplary fillers include alumina, zinc oxide, boron nitride, silicon nitride, aluminum, aluminum nitride, iron, metallic oxides, graphite, ceramic, silicon carbide, manganese zinc ferrite, magnetic flakes, carbonyl iron powder, carbon graphite fiber, carbon black, combinations thereof, etc.
  • the thermal interface material may have a relatively high thermal conductivity (e.g ., 1 W/mK, 2 W/mK, 3 W/mK, 4 W/mK, 5 W/mK, 6 W/mK, etc.) depending on the particular materials used to make the material and filler loading percentage.
  • thermal conductivities are only examples as other embodiments may include a thermal management and/or EMI mitigation material with a thermal conductivity higher than 6 W/mK, less than 1 W/mK, or other values between 1 and 6 W/mk.
  • the thermal interface material may be a thermal gap filler, thermal phase change material, thermally-conductive EMI absorber or hybrid thermal/EMI absorber, thermal grease, thermal paste, thermal putty, a dispensable thermal interface material, a thermal pad, etc.
  • the thermal interface material may be relatively soft, e.g., with a hardness of less than 25 Shore 00, greater than 75 Shore 00, between 25 and 75 Shore 00, etc.
  • the thermal interface material may be used to define or provide part of a thermally-conductive heat path from a heat source to a heat removal/dissipation structure or component.
  • a thermal interface material disclosed herein may be used, for example, to help conduct thermal energy (e.g, heat, etc.) away from a heat source of an electronic device (e.g, one or more heat generating components, central processing unit (CPU), die, semiconductor device, etc.).
  • a thermal interface material may be positioned generally between a heat source and a heat removal/dissipation structure or component (e.g, a heat spreader, a heat sink, a heat pipe, a device exterior case or housing, etc.) to establish a thermal joint, interface, pathway, or thermally-conductive heat path along which heat may be transferred (e.g, conducted) from the heat source to the heat removal/dissipation structure or component.
  • the thermal interface material may then function to allow transfer (e.g, to conduct heat, etc.) of heat from the heat source along the thermally-conductive path to the heat removal/dissipation structure or component.
  • the thermal interface material may be used with a wide range of heat sources, electronic devices, and/or heat removal/dissipation structures or components (e.g ., a heat spreader, a heat sink, a heat pipe, a device exterior case or housing, etc.).
  • a heat source may comprise one or more heat generating components or devices (e.g., a CPU, die within underfill, semiconductor device, flip chip device, graphics processing unit (GPU), digital signal processor (DSP), multiprocessor system, integrated circuit, multi-core processor, etc.).
  • a heat source may comprise any component or device that has a higher temperature than the thermal interface material or otherwise provides or transfers heat to the thermal interface material regardless of whether the heat is generated by the heat source or merely transferred through or via the heat source. Accordingly, aspects of the present disclosure should not be limited to use with any single type of heat source, electronic device, heat removal/dissipation structure, etc.
  • Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are 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 neither should 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.
  • parameter X may have a range of values from about A to about Z.
  • disclosure of two or more ranges of values for a parameter subsume all possible combination of ranges for the value that might be claimed using endpoints of the disclosed ranges.
  • parameter X is exemplified herein to have values in the range of 1 - 10, or 2 - 9, or 3 - 8, it is also envisioned 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 term“about” as used herein when modifying a quantity of an ingredient or reactant of the invention or employed refers to variation in the numerical quantity that can happen through typical measuring and handling procedures used, for example, when making concentrates or solutions in the real world through inadvertent error in these procedures; through differences in the manufacture, source, or purity of the ingredients employed to make the compositions or carry out the methods; and the like.
  • the term“about” also encompasses amounts that differ due to different equilibrium conditions for a composition resulting from a particular initial mixture. Whether or not modified by the term“about”, the claims include equivalents to the quantities.
  • 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 when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.
  • Spatially relative terms such as “inner,” “outer,” “beneath”, “below”, “lower”, “above”,“upper” and the like, may be used herein for ease of description to describe one element or feature’s relationship to another element(s) or feature(s) 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.
  • 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.

Abstract

Selon des modes de réalisation donnés à titre d'exemple, l'invention concerne des matériaux d'interface thermique (TM) à pertes diélectriques élevées et à constantes diélectriques faibles, le matériau d'interface thermique pouvant être conçu pour présenter une constante diélectrique dans une plage d'environ 3 à environ 20 et une tangente de perte dans une plage d'environ 0,10 à 1,0. Le matériau d'interface thermique à pertes diélectriques élevées permet de réduire les EMI des résonances créées par la capacité d'un dissipateur thermique et d'une source de chaleur.
PCT/US2019/018325 2018-02-17 2019-02-15 Matériaux d'interface thermique à pertes diélectriques élevées et à constantes diélectriques faibles WO2019161282A1 (fr)

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US201862631673P 2018-02-17 2018-02-17
US62/631,673 2018-02-17

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WO2007103741A2 (fr) * 2006-03-09 2007-09-13 Laird Technologies, Inc. ensembles de blindage EMI et de régulation thermique comprenant des cadres et des couvercles a fermetures multi-position
US20090016025A1 (en) * 2002-10-21 2009-01-15 Laird Technologies, Inc. Thermally conductive emi shield
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US20090016025A1 (en) * 2002-10-21 2009-01-15 Laird Technologies, Inc. Thermally conductive emi shield
WO2007103741A2 (fr) * 2006-03-09 2007-09-13 Laird Technologies, Inc. ensembles de blindage EMI et de régulation thermique comprenant des cadres et des couvercles a fermetures multi-position
US20160309628A1 (en) * 2013-12-18 2016-10-20 3M Innovative Properties Company Electromagnetic Interference (EMI) Shielding Products Using Titanium Monoxide (TIO) Based Materials

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