WO2019014439A1

WO2019014439A1 - Assemblies including board level shields and thermal interface materials

Info

Publication number: WO2019014439A1
Application number: PCT/US2018/041812
Authority: WO
Inventors: Jason L. Strader; Eugene Anthony PRUSS
Original assignee: Laird Technologies, Inc.
Priority date: 2017-07-12
Filing date: 2018-07-12
Publication date: 2019-01-17

Abstract

An exemplary embodiment of an assembly generally includes a board level shield and a thermal interface material. The board level shield includes first and second opposing sides and a portion having a thickness defined between the first and second opposing sides. The thermal interface material is along the portion on the first side and/or the second side of the board level shield. The thermal interface material has a thickness equal to or less than the thickness of the portion of the board level shield defined between the first and second opposing sides.

Description

ASSEMBLIES INCLUDING BOARD LEVEL SHIELDS AND

THERMAL INTERFACE MATERIALS

CROSS-REFERENCE TO RELATED APPLICATION

[0001 ] This application claims the benefit of and priority to U.S. Provisional Patent Application No. 62/531,791 filed July 12, 2017. The entire disclosure of the above application is incorporated herein by reference.

FIELD

[0002] The present disclosure relates to thermal management and electromagnetic interference (EMI) mitigation (e.g. , board level shielding, etc.) for electronic devices.

BACKGROUND

[0003] This section provides background information related to the present disclosure which is not necessarily prior art.

[0004] 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.

[0005] To avoid or at least reduce the adverse operating characteristics from the heat generation, 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. During conduction, 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). 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. [0006] In addition, a common problem in the operation of electronic devices is the generation of electromagnetic radiation within the electronic circuitry of the equipment. Such radiation may result in electromagnetic interference (EMI) or radio frequency interference (RFI), which can interfere with the operation of other electronic devices within a certain proximity. Without adequate shielding, EMI/RFI interference may cause degradation or complete loss of important signals, thereby rendering the electronic equipment inefficient or inoperable.

[0007] 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.

[0008] The term "EMI" as used herein should be considered to generally include and refer to EMI emissions and RFI emissions, and the term "electromagnetic" should be considered to generally include and refer to electromagnetic and radio frequency from external sources and internal sources. Accordingly, the term shielding (as used herein) 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.

DRAWINGS

[0009] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

[0010] FIG. 1 illustrates first and second (or lower and upper) thermal interface materials (TIMs) respectively along first and second opposing sides of a portion of a board level shield (BLS) according to an exemplary embodiment.

[0011 ] FIG. 2 is an exemplary line graph showing effective thermal conductivity of the board level shield and thermal interface materials shown in FIG. 1 versus thermal conductivity of the board level shield alone, with thermal contact resistance of 0.03 in °C/W.

[0012] FIG. 3 is an exemplary line graph showing effective thermal conductivity of the board level shield and thermal interface materials shown in FIG. 1 versus thermal conductivity of the board level shield alone without any thermal contact resistance. [0013] FIG. 4 is an exemplary line graph showing effective thermal conductivity of the board level shield and thermal interface materials shown in FIG. 1 versus thermal conductivity of the board level shield alone.

[0014] FIG. 5 is an exemplary line graph showing effective thermal conductivity of the board level shield and thermal interface materials shown in FIG. 1 versus increasing thickness of the board level shield (and thus decreasing thickness of the thermal interface materials when the combined thickness is held constant at 0.75 mm).

DETAILED DESCRIPTION

[0015] Example embodiments will now be described more fully with reference to the accompanying drawings.

[0016] Portable electronics are becoming smaller, thinner, and highly densely populated with components making space in all directions in a device valuable. Many methods are being employed to reduce the x, y, and z footprint of board level shielding as well as improving heat transfer. It is common to have air gaps between the device and a BLS and/or between the BLS and the case or housing of the device. But air is a poor medium to transfer heat. To improve heat transfer, thermal interface materials (TIMs) may be used to fill in air gaps between the BLS and the device and/or between the BLS and the case of the device. Conventionally, however, the thickness of the BLS has not been considered when trying improve heat transfer.

[0017] As disclosed herein, the inventors hereof have discovered a counterintuitive way of improving the effective thermal conductivity of the BLS and TIM stack up by increasing the BLS thickness, and correspondingly reducing the TIM thickness. Increasing the BLS thickness is counterintuitive and contrary to the industry trend of using thinner components for space reasons. In exemplary embodiments, the ratio of BLS thickness to the TIM thickness may be 1 : 1 or higher (e.g. , 1 : 1, 2: 1, 3: 1, 4: 1, 5: 1, 6: 1, 7: 1, 8: 1, 13: 1, 15: 1, 20: 1, 27: 1, etc.), which improves effective thermal conductivity of the BLS and TIM stack up.

[0018] With reference now to the figures, FIG. 1 illustrates an exemplary embodiment of an assembly 100 embodying one or more aspects of the present disclosure. As shown, the assembly 100 includes a board level shield (BLS) 104 and first and second (or lower and upper) thermal interface materials (TIMs) 108, 1 12, respectively. The first and second TIMs 108, 112 are disposed respectively along first and second (or lower and upper) opposing sides 116, 120 of a portion of the BLS 104. [0019] The portion of the BLS 104 has a thickness L2 equal to or greater than the thicknesses LI of the first and second thermal interface materials 108, 112. The combined thickness dimension of 0.75 millimeters (mm) shown in FIG. 1 was used during the testing to obtain the data for the line graphs in FIGS. 2 through 4. This combined thickness dimension is exemplary in nature and does not limit the scope of the present disclosure as the combined thickness may be less than or greater than 0.75 mm. In addition, the thickness of the first thermal interface material 108 may be the same as or different than the thickness of the second thermal interface material 112.

[0020] FIGS. 2 through 5 generally show effective thermal conductivity based on thickness and base metal thermal conductivity. More specifically, FIG. 2 is an exemplary line graph showing effective thermal conductivity of the board level shield 104 and thermal interface materials 108, 112 shown in FIG. 1 versus thermal conductivity of the board level shield 104 alone.

[0021 ] For this testing, four different materials were used for the board level shield 104, specifically, stainless steel having a thermal conductivity (Tc) of 16 W/mK (watts per meter per Kelvin), nickel silver having a thermal conductivity of 29 W/mK, cold rolled steel having a thermal conductivity of 65, and aluminum having a thermal conductivity of 138 W/mK. Also for this testing, the thermal contact resistance was 0.03 in °C/W, the thermal interface materials 108, 112 had a thermal conductivity of 3 W/mk, the board level shield thickness was 0.6 mm, and each thermal interface material 108, 112 had a thickness of .075 mm.

[0022] As shown in FIG. 2, the effective thermal conductivity was about 7.02 W/mk for the stainless steel BLS and TIMs, about 8.33 W/mk for the nickel silver BLS and TIMs, about 9.54 W/mk for the cold rolled steel BLS and TIMs, and about 10.18 W/mk for the aluminum BLS and TIMs.

[0023] FIG. 3 is another exemplary line graph showing effective thermal conductivity of the board level shield 104 and thermal interface materials 108, 112 shown in FIG. 1 versus thermal conductivity of the board level shield alone. Unlike the test results shown in FIG. 2 for which the thermal contact resistance was 0.03 in" °C/W, there was no thermal contact resistance during the testing that produced the results shown in FIG. 3.

[0024] With continued reference to FIG. 3, the same four different materials were used for the board level shield 104, specifically, stainless steel having a thermal conductivity of 16 W/mK, nickel silver having a thermal conductivity of 29 W/mK, cold rolled steel having a thermal conductivity of 65, and aluminum having a thermal conductivity of 138 W/mK. Also for this testing, there was no thermal contact resistance, the thermal interface materials 108, 112 had a thermal conductivity of 3 W/mk, the board level shield thickness was 0.6 mm, and each thermal interface material 108, 112 had a thickness of .075 mm.

[0025] As shown in FIG. 3, the effective thermal conductivity was about 8.57 W/mk for the stainless steel BLS and TIMs, about 10.61 W/mk for the nickel silver BLS and TIMs, about 12.66 W/mk for the cold rolled steel BLS and TIMs, and about 13.8 W/mk for the aluminum BLS and TIMs.

[0026] FIG. 4 is an exemplary line graph showing effective thermal conductivity of the board level shield 104 and thermal interface materials 108, 112, shown in FIG. 1 versus thermal conductivity of the board level shield 104 alone. For this testing, the same four different materials were used for the board level shield 104, specifically, stainless steel having a thermal conductivity of 16 W/mK, nickel silver having a thermal conductivity of 29 W/mK, cold rolled steel having a thermal conductivity of 65, and aluminum having a thermal conductivity of 138 W/mK. Also for this testing, the thermal interface materials 108, 112 had a thermal conductivity of 3 W/mk, the board level shield thickness was 0.3 mm, and each thermal interface material 108, 112 had a thickness of .225 mm.

[0027] As shown in FIG. 4, the effective thermal conductivity was about 4.44 W/mk for the stainless steel BLS and TIMs, about 4.68 W/mk for the nickel silver BLS and TIMs, about 4.85 W/mk for the cold rolled steel BLS and TIMs, and about 4.93 W/mk for the aluminum BLS and TIMs.

[0028] FIG. 5 is an exemplary line graph showing effective thermal conductivity of the board level shield 104 and thermal interface 108, 112 materials shown in FIG. 1 versus increasing thickness of the board level shield 104 (and thus decreasing thickness of the thermal interface materials 108, 112 when the combined thickness is held constant at 0.75 mm). For this testing, the same four different materials were used for the board level shield, specifically, stainless steel having a thermal conductivity of 16 W/mK, nickel silver having a thermal conductivity of 29 W/mK, cold rolled steel having a thermal conductivity of 65, and aluminum having a thermal conductivity of 138 W/mK. The thermal interface materials 108, 112 had a thermal conductivity of 3 W/mk.

[0029] As shown in FIG. 5, the effective thermal conductivity was about 3.58 W/mK for a stainless steel BLS thickness of .15 mm and a TIM thickness of .3 mm for each thermal interface material 108, 112. The effective thermal conductivity was about 4.44 W/mK for a stainless steel BLS thickness of .3 mm and a TIM thickness of .225 mm for each thermal interface material 108, 112. The effective thermal conductivity was about 8.57 W/mK for a stainless steel BLS thickness of .6 mm and a TIM thickness of .075 mm for each thermal interface material 108, 112. [0030] The effective thermal conductivity was about 3.66 W/mK for a nickel silver BLS thickness of .15 mm and a TIM thickness of .3 mm for each thermal interface material 108, 112. The effective thermal conductivity was about 4.68 W/mK for a nickel silver BLS thickness of .3 mm and a TIM thickness of .225 mm for each thermal interface material 108, 112. The effective thermal conductivity was about 10.61 W/mK for a nickel silver BLS thickness of .6 mm and a TIM thickness of .075 mm for each thermal interface material 108, 112.

[0031 ] The effective thermal conductivity was about 3.71 W/mK for a cold rolled steel BLS thickness of .15 mm and a TIM thickness of .3 mm for each thermal interface material 108, 112. The effective thermal conductivity was about 4.85 W/mK for a cold rolled steel BLS thickness of .3 mm and a TIM thickness of .225 mm for each thermal interface material 108, 112. The effective thermal conductivity was about 12.66 W/mK for a cold rolled steel BLS thickness of .6 mm and a TIM thickness of .075 mm for each thermal interface material 108, 112.

[0032] The effective thermal conductivity was about 3.73 W/mK for an aluminum BLS thickness of .15 mm and a TIM thickness of .3 mm for each thermal interface material 108, 112. The effective thermal conductivity was about 4.93 W/mK for an aluminum BLS thickness of .3 mm and a TIM thickness of .225 mm for each thermal interface material 108, 112. The effective thermal conductivity was about 13.8 W/mK for an aluminum BLS thickness of .6 mm and a TIM thickness of .075 mm for each thermal interface material 108, 112.

[0033] As shown in FIG. 5, a significant improvement in thermal performance may be achieved by increasing the thickness of the board level shield by at least two times (2x) or more than the original thickness. If, for example, the original BLS thickness is 0.15 mm, significant improvements may be achieved by doubling (0.3 mm), tripling (0.45 mm), quadrupling (0.6 mm), etc. the BLS thickness. As shown in FIG. 5, the effective thermal conductivity increases significantly and dramatically when the BLS thickness was increased from 0.15 mm to 0.3 mm or higher.

[0034] Table 1 below includes test data (thermal resistance (Rth) and apparent thermal conductivity (Tc)) for a 1 mm thick aluminum core with 0.075 mm thick soft thermally-conductive gap filler along each of the first and second opposing sides of the aluminum core. During the testing, the target was 0.6 °C*cm²/W at 0.9 mm (1 mm at 10% deflection). When the pressure was increased, the thickness of the soft thermally-conductive gap filler decreased. In turn, the ratio of the thickness of the aluminum core to the thickness of the soft thermally-conductive gap filler along one side increased due to the reduced thickness of the soft thermally-conductive gap filler. As shown by the table, the apparent thermal conductivity increased as the pressure was increased from 10, 15, 20, 50 pounds per square inch (psi) and the ratio of the thickness of the aluminum core to the thickness of the soft thermally- conductive gap filler increased.

[0035] For the 10 psi example in the table, the initial ratio was about 13: 1 (1 mm thick aluminum core/.0765 mm initial TIM thickness along one side of core). The final ratio at 10 psi was about 15.27: 1 (1 mm thick aluminum core/.0655 mm final TIM thickness along one side of core). The apparent thermal conductivity about 13.63 W/mK.

[0036] For the 15 psi example in the table, the apparent thermal conductivity about 17.41 W/mK. For the 20 psi example in the table, the apparent thermal conductivity about 21.43 W/mK. For the 50 psi example in the table, the apparent thermal conductivity about 30.68 W/mK.

TABLE 1

[0037] The test results (e.g. , FIGS. 2 through 5, etc.), material properties (e.g. , tables 1, 2, and 3, etc.), and dimensions provided herein are illustrative only and do not limit this disclosure as other exemplary embodiments may be configured differently, e.g. , made of different materials, have different dimensions, have different thermal conductivities, etc.

[0038] When the BLS thickness is increased, the TIM thickness may be correspondingly reduced in order to fit within the same size air gap given the limited amount of space in the air gap. Depending on the particular materials selected, the TIM may be more costly than the BLS such that costs may be reduced by using a thicker BLS and a correspondingly thinner TIM, thereby using less of the costlier TIM. In exemplary embodiments, the ratio of TIM to BLS is minimized or reduced (or conversely, the ratio of BLS to TIM is maximized or increased) so as to use more BLS material and thereby take advantage of the higher thermal conductivity of the BLS as compared to the thermal conductivity of the TIM. In exemplary embodiments, a minimum thickness for the thermal interface material and a maximum thickness for the board level shield may be determined so that heat transfer efficiency is improved along a thermally-conductive heat path cooperatively defined by the thermal interface material and the portion of the board level shield. In an exemplary embodiment, the BLS is made of aluminum, which is less costly, lighter weight, and has a higher thermal conductivity than the thermal interface material along the aluminum BLS.

[0039] In an exemplary embodiment, the TIM thickness on one side was 1/8 of the BLS thickness. The TIM thickness need not be uniform on each side of a BLS. Also, the TIM on the first side of the BLS may be the same type of or different than the TIM on the second side of the BLS.

[0040] In exemplary embodiments, a thermal interface solution includes a thermally- conductive core, such as metal (e.g. , aluminum, etc.), which may or may not be used as a BLS or BLS cover or lid. Thermal interface material (TIM) may be disposed along either or both sides of the thermally-conductive core. The thermally-conductive core has a higher thermal conductivity than the TIM. In this example, the thermally-conductive core has a thickness that is equal to or greater than the thickness of the TIM. In an exemplary embodiment, the thermally-conductive core is thicker than the TIM, and the thicknesses of the TIM and the thermally-conductive core may be optimized such that the TIM thickness is as thin as possible as compared to the thickness of the thermally-conductive core. In some exemplary embodiments, the thermally-conductive core and TIM along either or both sides thereof may be used as a BLS assembly. In such embodiments, the BLS assembly including the thermally- conductive core and TIM may have a relatively high effective thermal conductivity, such as an effective or apparent thermal conductivity greater than 13 W/mK as shown in FIG. 5 (e.g. , 13.63 W/mK, 17.41 W/mK, 21.41 W/mK, 30.68 W/mK, etc.).

[0041 ] In exemplary embodiments, a board level shield includes a cover or lid and a frame or fence. The frame includes one or more sidewalls configured for installation (e.g. , soldering, etc.) to a printed circuit board (PCB) (broadly, a substrate) generally about one or more components or heat sources (e.g. , an integrated circuit, etc.) on the PCB. A first thermal interface material (TIM1) is positioned inside or underneath the BLS along a lower or first side of the BLS cover. A second thermal interface material (TIM2) is positioned outside or on top of the BLS along an upper or second side of the BLS cover. The BLS cover may have a thickness that is equal to or greater than the TIM1 thickness and that is equal to or greater than the TIM2 thickness.

[0042] In use, the BLS may be positioned such that the first thermal interface material contacts (e.g. , is compressed and conforms against, etc.) one or more heat sources underneath the BLS while the second thermal interface material contacts (e.g. , is compressed and conforms against, etc.) a heat removal/dissipation structure (e.g. , heat sink or case of an electronic device, etc.) above or external to the BLS. Heat may be transferred from the one or more heat sources to the heat removal/dissipation structure along a thermally-conductive heat path cooperatively defined by the first thermal interface material, the BLS cover, and the second thermal interface material. Using the thicker BLS cover and thus more BLS material helps improve heat transfer along the thermally-conductive heat path because the BLS cover has a higher thermal conductivity than the first and second thermal interface materials.

[0043] In exemplary embodiments, a thicker BLS may be provided by various methods. For example, the thicker BLS may be provided by selecting a thicker stock material (e.g. , thicker sheet metal, etc.) from which to make the BLS, e.g. , via machining, stamping, drawings, folding, welding, etc. In exemplary embodiments, the BLS may have a uniform thickness such that the BLS cover and BLS sidewalls have about the same thickness. In other exemplary embodiments, the BLS may have a nonuniform thickness such that the BLS cover (or portion thereof along which the TIMs are disposed) is thicker than the BLS sidewalls. In which case, the thinner BLS sidewalls may be provided by laser welding the BLS sidewalls to the BLS cover, by a drawing process, etc.

[0044] An exemplary embodiment of an assembly generally includes a board level shield and a thermal interface material along a portion of the board level shield on either or both of a first and/or second side of the board level shield. The thermal interface material has a thickness equal to or less than the thickness of the portion of the board level shield along which the thermal interface material is disposed. The thickness of the portion of the board level shield is defined between the first and second opposing sides.

[0045] In some exemplary embodiments, the board level shield has a higher thermal conductivity than the thermal interface material. The thermal interface material has a predetermined minimum thickness. The portion of the board level shield has a predetermined maximum thickness defined between the first and second opposing sides. This may allow for improved heat transfer efficiency is improved along a thermally-conductive heat path cooperatively defined by the thermal interface material and the portion of the board level shield.

[0046] In some exemplary embodiments, the thickness of the portion of the board level shield defined between the first and second opposing sides is greater than the thickness of the thermal interface material along the portion on the first side and/or the second side of the board level shield. And, the board level shield has a higher thermal conductivity than the thermal interface material such that the thickness of the portion of the board level shield defined between the first and second opposing sides being greater than the thickness of the thermal interface material improves heat transfer efficiency along a thermally-conductive heat path cooperatively defined by the thermal interface material and the portion of the board level shield.

[0047] In some exemplary embodiments, the thermal interface material comprises first and second thermal interface materials along the portion on the first and second sides, respectively, of the board level shield. And, the thickness of the portion of the board level shield defined between the first and second opposing sides is equal to or greater than a thickness of the first thermal interface and/or equal to or greater than a thickness of the second thermal interface material.

[0048] In some exemplary embodiments, the thickness of the portion of the board level shield defined between the first and second opposing sides is greater than the thickness of the first thermal interface material and greater than the thickness of the second thermal interface material. And, the board level shield has a higher thermal conductivity than the first and second thermal interface materials such that the thickness of the portion of the board level shield defined between the first and second opposing sides being greater than the thicknesses of the first and second thermal interface materials improves heat transfer efficiency along a thermally-conductive heat path cooperatively defined by the first thermal interface material, the portion of the board level shield, and the second thermal interface material.

[0049] In some exemplary embodiments, the thickness of the portion of the board level shield defined between the first and second opposing sides is greater than a sum of the thickness of the first thermal interface material and the thickness of the second thermal interface material.

[0050] In some exemplary embodiments, a ratio of the thickness of the portion of the board level shield to the thickness of the first thermal interface material is at least 1: 1 or higher; and/or a ratio of the thickness of the portion of the board level shield to the thickness of the second thermal interface material is at least 1: 1 or higher; and/or a ratio of the thickness of the portion of the board level shield to the sum of the thickness of the first thermal interface material and the thickness of the second thermal interface material is at least 1 : 1 or higher.

[0051 ] In some exemplary embodiments, a ratio of the thickness of the portion of the board level shield to the thickness of the first thermal interface material is at least 8: 1 or higher; and/or a ratio of the thickness of the portion of the board level shield to the thickness of the second thermal interface material is at least 8: 1 or higher.

[0052] In some exemplary embodiments, the thickness of the first thermal interface material is equal to, less than, or greater than the thickness of the second thermal interface material; and/or a sum of the thickness of the portion of the board level shield defined between the first and second opposing sides, the thickness of the first thermal interface material, and the thickness of the second thermal interface material is about 0.75 millimeters; and/or the thickness of the first thermal interface material is less than 0.5 millimeters, and the thickness of the second thermal interface material is less than 0.5 millimeters; and/or the thickness of the portion of the board level shield is about 0.6 millimeters or about 1 millimeter, the thickness of the first thermal interface material is about 0.075 millimeters, and the thickness of the second thermal interface material is less than 0.075 millimeters; and/or the thickness of the portion of the board level shield is about 0.3 millimeters, the thickness of the first thermal interface material is about 0.225 millimeters, and the thickness of the second thermal interface material is less than 0.225 millimeters.

[0053] In some exemplary embodiments, the board level shield is a single piece board level shield that generally includes a cover and one or more sidewalls. The cover includes the first and second opposing sides and the portion having the thickness defined between the first and second opposing sides. The one or more sidewalls are integrally formed with the cover and the one more sidewalls that are configured for installation to a substrate generally about a heat source on the substrate. The board level shield may have a uniform thickness such that a thickness of the one or more sidewalls is equal to the thickness of the portion defined between the first and second opposing sides. Or, the board level shield may have a non-uniform thickness such that a thickness of the one or more sidewalls is less than the thickness of the portion defined between the first and second opposing sides.

[0054] In some exemplary embodiments, the board level shield is a multi-piece board level shield that generally includes one or more sidewalls and a cover. The one or more sidewalls are configured for installation to a substrate generally about a heat source on the substrate. The cover is removably attachable to the one or more sidewalls. The cover includes the first and second opposing sides and the portion having the thickness defined between the first and second opposing sides. The board level shield may have a uniform thickness such that a thickness of the one or more sidewalls is equal to the thickness of the portion defined between the first and second opposing sides. Or, the board level shield may have a non-uniform thickness such that a thickness of the one or more sidewalls is less than the thickness of the portion defined between the first and second opposing sides.

[0055] In some exemplary embodiments, the board level shield is made of metal, such as aluminum, cold rolled steel, nickel silver, stainless steel, etc. The thermal interface material comprises an extrudable thermal interface material, an insert moldable thermal interface material, a dispensable thermal interface material, a thermal putty, a thermal gap filler, a thermal phase change material, a thermally-conductive EMI absorber or hybrid thermal/EMI absorber, a thermal pad, a thermal grease, a thermal paste, etc.

[0056] An exemplary embodiment of an electronic device generally includes a heat removal/dissipation structure (e.g. , heat sink, a case of the electronic device, etc.), a printed circuit board having a heat source, and the assembly including the board level shield and the thermal interface material. The board level shield may be operable for providing electromagnetic interference shielding for the heat source. Heat may be transferrable from the heat source to the heat removal/dissipation structure along the thermally-conductive path cooperatively defined by the thermal interface material and the portion of the board level shield to the heat removal/dissipation structure.

[0057] In an exemplary embodiment, a method of enhancing effective thermal conductivity of a board level shield generally includes providing a board level shield that includes first and second opposing sides and a portion having a thickness defined between the first and second opposing sides that is equal to or greater than a thickness of a thermal interface material along the portion on the first side and/or the second side of the board level shield.

[0058] In some exemplary embodiments, the board level shield has a higher thermal conductivity than the thermal interface material. And, the method includes determining a minimum thickness for the thermal interface material and a maximum thickness for the portion of the board level shield defined between the first and second opposing sides such that heat transfer efficiency is improved along a thermally-conductive heat path cooperatively defined by the thermal interface material and the portion of the board level shield.

[0059] In some exemplary embodiments, the thickness of the portion of the board level shield defined between the first and second opposing sides is greater than the thickness of the thermal interface material along the portion on the first side and/or the second side of the board level shield. And, the board level shield has a higher thermal conductivity than the thermal interface material such that the thickness of the portion of the board level shield defined between the first and second opposing sides being greater than the thickness of the thermal interface material improves heat transfer efficiency along a thermally-conductive heat path cooperatively defined by the thermal interface material and the portion of the board level shield.

[0060] In some exemplary embodiments, the method includes determining a thickness of a first air gap that will be defined between the first side of the board level shield and a heat source on a substrate after the board level shield is installed on the substrate and increasing the thickness of the portion of the board level shield defined between the first and second opposing sides to help fill the first air gap and improve heat transfer. Additionally, or alternatively, the method may include determining a thickness of a second air gap that will be defined between the second side of the board level shield and a heat removal/dissipation structure such as a heat sink or a case of an electronic device, and increasing the thickness of the portion of the board level shield defined between the first and second opposing sides to help fill the second air gap and improve heat transfer.

[0061 ] In some exemplary embodiments, the thermal interface material comprises first and second thermal interface materials along the portion on the first and second sides, respectively, of the board level shield. The thickness of the portion of the BLS defined between the first and second opposing sides is equal to or greater than a thickness of the first thermal interface material and/or equal to or greater than a thickness of the second thermal interface material.

[0062] In some exemplary embodiments, the thickness of the portion of the board level shield defined between the first and second opposing sides is greater than the thickness of the first thermal interface material and greater than the thickness of the second thermal interface material.

[0063] In some exemplary embodiments, the board level shield has a higher thermal conductivity than the first and second thermal interface materials such that the thickness of the portion of the board level shield defined between the first and second opposing sides being greater than the thicknesses of the first and second thermal interface materials improves heat transfer efficiency along a thermally-conductive heat path cooperatively defined by the first thermal interface material, the portion of the board level shield, and the second thermal interface material.

[0064] In some exemplary embodiments, the thickness of the portion of the board level shield defined between the first and second opposing sides is greater than a sum of the thickness of the first thermal interface material and the thickness of the second thermal interface material.

[0065] In some exemplary embodiments, a ratio of the thickness of the portion of the board level shield to the thickness of the first thermal interface material is within a range from 1: 1 to 8: 1 or is higher than 8: 1; and/or a ratio of the thickness of the portion of the board level shield to the thickness of the second thermal interface material is within a range from 1: 1 to 8: 1 or is higher than 8: 1; and/or a ratio of the thickness of the portion of the board level shield to the sum of the thickness of the first thermal interface material and the thickness of the second thermal interface material is at least 1: 1 or higher. [0066] In some exemplary embodiments, the method includes increasing the thickness of the portion of the board level shield to be at least 8 times thicker than the thickness of the first thermal interface material such that a ratio of the thickness of the portion of the board level shield to the thickness of the first thermal interface material is 8: 1 or more; and/or increasing the thickness of the portion of the board level shield to be at least 8 times thicker than the thickness of the second thermal interface material such that a ratio of the thickness of the portion of the board level shield to the thickness of the second thermal interface material is 8: 1 or more.

[0067] In some exemplary embodiments, the method includes making the board level shield such that the thickness of the portion of the board level shield is greater than the thickness of the first thermal interface material and greater than the thickness of the second thermal interface material; applying the first thermal interface material along the portion on the first side of the board level shield; and applying the second thermal interface material along the portion on the second side of the board level shield.

[0068] In some exemplary embodiments, the thickness of the first thermal interface material is equal to, less than, or greater than the thickness of the second thermal interface material; and/or a sum of the thickness of the portion of the board level shield defined between the first and second opposing sides, the thickness of the first thermal interface material, and the thickness of the second thermal interface material is about 0.75 millimeters; and/or the thickness of the first thermal interface material is less than 0.5 millimeters, the thickness of the second thermal interface material is less than 0.5 millimeters; and/or the thickness of the portion of the board level shield is about 0.6 millimeters, the thickness of the first thermal interface material is about 0.075 millimeters, and the thickness of the second thermal interface material is less than 0.075 millimeters; and/or the thickness of the portion of the board level shield is about 0.3 millimeters, the thickness of the first thermal interface material is about 0.225 millimeters, and the thickness of the second thermal interface material is less than 0.225 millimeters.

[0069] In some exemplary embodiments, the method includes positioning the first thermal interface material against a heat source; and positioning the second thermal interface material against a heat removal/dissipation structure(e.g. , heat sink or case of an electronic device, etc.). Heat may be transferable from the heat source to the heat removal/dissipation structure along the thermally- conductive path defined from the first thermal interface material through the portion of the board level shield to the second thermal interface material. The board level shield may be operable for providing electromagnetic interference (EMI) shielding for the heat source.

[0070] In some exemplary embodiments, the method includes at least doubling the thickness of at least the portion of the board level shield from an original thickness.

[0071 ] In some exemplary embodiments, the board level shield is a single piece board level shield comprising a cover and one or more sidewalls that are integrally formed with the cover. The one or more sidewalls are configured for installation to a substrate generally about a heat source on the substrate. The cover includes the first and second opposing sides and the portion having the thickness defined between the first and second opposing sides. The board level shield may have a uniform thickness such that a thickness of the one or more sidewalls is equal to the thickness of the portion defined between the first and second opposing sides, Or, the board level shield may have a non-uniform thickness such that a thickness of the one or more sidewalls is less than the thickness of the portion defined between the first and second opposing sides.

[0072] In some exemplary embodiments, the board level shield is a multi-piece board level shield comprising one or more sidewalls and a cover removably attachable to the one or more sidewalls. The one or more sidewalls are configured for installation to a substrate generally about a heat source on the substrate. The cover includes the first and second opposing sides and the portion having the thickness defined between the first and second opposing sides. The board level shield may have a uniform thickness such that a thickness of the one or more sidewalls is equal to the thickness of the portion defined between the first and second opposing sides. Or, the board level shield may have a nonuniform thickness such that a thickness of the one or more sidewalls is less than the thickness of the portion defined between the first and second opposing sides.

[0073] In some exemplary embodiments, the method includes installing the one or more sidewalls of the board level shield to the substrate generally about the heat source on the substrate, such that heat from the heat source is transferrable along a thermally-conductive heat path cooperatively defined by the thermal interface material and the portion of the board level shield to a heat removal/dissipation structure; and such that the board level shield is operable for providing electromagnetic interference (EMI) shielding for the heat source.

[0074] In some exemplary embodiments, the board level shield comprises metal, such as aluminum, cold rolled steel, nickel silver, stainless steel, etc. The thermal interface material comprises an extrudable thermal interface material, an insert moldable thermal interface material, a dispensable thermal interface material, a thermal putty, a thermal gap filler, a thermal phase change material, a thermally-conductive EMI absorber or hybrid thermal/EMI absorber, a thermal pad, a thermal grease, a thermal paste, etc.

[0075] An exemplary embodiment of a thermally-conductive interface assembly generally includes a thermally-conductive core having first and second opposing sides and a portion having a thickness defined between the first and second opposing sides. A first thermal interface material is along the portion on the first side of the thermally-conductive core and having a thickness equal to or less than the thickness of the portion of the thermally-conductive core. A second thermal interface material is along the portion on the second side of the thermally-conductive core and having a thickness equal to or less than the thickness of the portion of the thermally-conductive core. The thermally-conductive core has a higher thermal conductivity than a thermal conductivity of the first and second thermal interface materials. The first and second thermal interface materials are more conformable than the thermally- conductive core.

[0076] In some exemplary embodiments, the thickness of the portion of the thermally- conductive core defined between the first and second opposing sides is greater than the thickness of the first thermal interface material and greater than the thickness of the second thermal interface material.

[0077] In some exemplary embodiments, the thickness of the portion of the thermally- conductive core defined between the first and second opposing sides is greater than a sum of the thickness of the first thermal interface material and the thickness of the second thermal interface material.

[0078] In some exemplary embodiments, a ratio of the thickness of the portion of the thermally-conductive core to the thickness of the first thermal interface material is at least 1: 1 or higher; and/or a ratio of the thickness of the portion of the thermally-conductive core to the thickness of the second thermal interface material is at least 1: 1 or higher; and/or a ratio of the thickness of the portion of the thermally-conductive core to the sum of the thickness of the first thermal interface material and the thickness of the second thermal interface material is at least 1: 1 or higher.

[0079] In some exemplary embodiments, a ratio of the thickness of the portion of the thermally-conductive core to the thickness of the first thermal interface material is at least 8: 1 or higher; and/or a ratio of the thickness of the portion of the thermally-conductive core to the thickness of the second thermal interface material is at least 8: 1 or higher. [0080] In some exemplary embodiments, the thickness of the first thermal interface material is equal to, less than, or greater than the thickness of the second thermal interface material; and/or the thickness of the first thermal interface material is less than 0.5 millimeters, and the thickness of the second thermal interface material is less than 0.5 millimeters.

[0081 ] In some exemplary embodiments, the thermally-conductive core comprises metal such as aluminum, cold rolled steel, nickel silver, and/or stainless steel. The first thermal interface material comprises an extrudable thermal interface material, an insert moldable thermal interface material, a dispensable thermal interface material, a thermal putty, a thermal gap filler, a thermal phase change material, a thermally-conductive EMI absorber or hybrid thermal/EMI absorber, a thermal pad, a thermal grease, and/or a thermal paste. The second thermal interface material comprises an extrudable thermal interface material, an insert moldable thermal interface material, a dispensable thermal interface material, a thermal putty, a thermal gap filler, a thermal phase change material, a thermally-conductive EMI absorber or hybrid thermal/EMI absorber, a thermal pad, a thermal grease, and/or a thermal paste.

[0082] In some exemplary embodiments, the thermally-conductive core comprises aluminum. The first thermal interface material comprises a soft thermal gap filler. The second thermal interface material comprises a soft thermal gap filler.

[0083] In some exemplary embodiments, the thermally-conductive core comprises an aluminum core having a thickness of about 1 millimeters. The first thermal interface material comprises a soft thermal gap filler having a thickness of about .075 millimeters. The second thermal interface material comprises a soft thermal gap filler having a thickness of about .075 millimeters. A ratio of the thickness of the aluminum core to the thickness of the soft thermal gap filler of the first thermal interface material is greater than 13: 1. A ratio of the thickness of the aluminum core to the thickness of the soft thermal gap filler of the second thermal interface material is greater than 13: 1.

[0084] In some exemplary embodiments, the thermally-conductive interface assembly is configured to have one or more properties (e.g. , thermal resistance, thermal conductivity, thickness, etc.) as shown in any one or more of FIGS. 2 through 5.

[0085] An exemplary embodiment of an electronic device generally includes a heat removal/dissipation structure (e.g. , heat sink or case of an electronic device, etc.), a printed circuit board having one or more heat sources, and the thermally-conductive interface assembly. The thermally- conductive interface assembly is positioned relative to the one or more heat sources such that the thermally-conductive interface assembly is operable for providing electromagnetic interference shielding for the one or more heat sources and such that heat is transferrable from the one or more heat sources to the heat removal/dissipation structure along a thermally-conductive path cooperatively defined by the first thermal interface material, the portion of the thermally-conductive core, and the second thermal interface material to the heat removal/dissipation structure.

[0086] An exemplary embodiment of a board level shielding assembly generally includes a thermally-conductive interface assembly as disclosed herein. In this example, the board level shielding assembly may have an effective thermal conductivity of 13 W/mK or more.

[0087] Example thermal interface materials that may be used in exemplary embodiments include dispensable thermal interface materials, thermal putties, thermal gap fillers, thermal phase change materials, thermally-conductive EMI absorbers or hybrid thermal/EMI absorbers, thermal pads, thermal greases, thermal pastes, etc.

[0088] Example embodiments may include one or more thermal interface materials of Laird, such as any one or more of the Tputty series thermal gap fillers (e.g. , Tputty™ 403, 504, 506, or 508 dispensable thermal interface materials , etc.), Tflex™ series gap fillers (e.g. , Tflex™ 300 series thermal gap filler materials, Tflex™ 600 series thermal gap filler materials, Tflex™ 700 series thermal gap filler materials, etc.), Tpcm™ series thermal phase change materials (e.g. , Tpcm™ 580 series phase change materials, etc.), Tpli™ series gap fillers (e.g. , Tpli™ 200 series gap fillers, etc.), IceKap™ series thermal interface materials, and/or CoolZorb™ series thermally conductive microwave absorber materials (e.g. , CoolZorb™ 400 series thermally conductive microwave absorber materials, CoolZorb 500 series thermally conductive microwave absorber materials, CoolZorb™ 600 series thermally conductive microwave absorber materials, etc.), etc.

[0089] The thermal interface material may comprise a two-part cure in place ceramic filled silicone-based thermal gap filler that is curable at room temperature, has a low viscosity (e.g. , 260,000 cps before mixing, etc.), good thermal conductivity (e.g. , about 2 W/mk, etc.), and that is soft and compliant (e.g. , hardness (Shore 00) 3 second of 45, etc.). As another example, the thermal interface material may comprise a single -part silicone-based thermal gap filler that is soft, compliant, and low abrasion and that has good thermal conductivity (e.g. , about 2.3 W/mk, etc.). As a further example, the thermal interface material may comprise a soft silicone-based thermal gap filler that is a ceramic -filled dispensable silicone gel, that is soft and compliant, that has good thermal conductivity (e.g. , about 1.8 W/mk, etc.), that can be can be applied like grease, and that is easily dispensable from equipment such as screen print, syringe, and automated equipment. As yet a further example, the thermal interface material may comprise a soft single-part silicone putty thermal gap filler in which no cure is required, that has good thermal conductivity (e.g. , about 3.5 W/mk, etc.), and that is soft, compliant, non-abrasive, and dispensable.

[0090] In some exemplary embodiments, the thermal interface material may comprise a compliant gap filler having high thermal conductivity and/or may comprise a thermal interface material of Laird, such as one or more of Tflex™ 200, Tflex™ HR200, Tflex™ 300, Tflex™ 300TG, Tflex™ HR400, Tflex™ 500, Tflex™ 600, Tflex™ HR600, Tflex™ SF600, Tflex™ 700, Tflex™ SF800 thermal gap fillers. For example, the thermal interface material may comprise a filled (e.g. , alumina, ceramic, boron nitride, etc.) silicone elastomer gap filler that is soft, compliant, free-standing, and/or naturally tacky for adhesion during assembly and transport, and has good thermal conductivity (e.g. , about 1.1 W/mk, 1.2 W/mK, 1.6 W/mk, 2.8, W/mK, 3 W/mK, 5 W/mK, etc.). As another example, the thermal interface material may comprise a filled silicone elastomer gel that has good thermal conductivity (e.g., about 1.2 W/mK, 1.8 W/mk, etc.) and that may also include a silicone liner or other dielectric barrier. As a further example, the thermal interface material may comprise a ceramic-filled silicone-free gap filler that has good thermal conductivity (e.g. , about 7.8 W/mk, etc.) and a flammability rating of UL94 V0 and/or is naturally tacky.

[0091 ] The thermal interface materials disclosed herein may comprise an elastomer and/or ceramic particles, metal particles, ferrite EMI/RFI absorbing particles, metal or fiberglass meshes in a base of rubber, gel, or wax, etc. The thermal interface materials may include compliant or conformable silicone pads, non-silicone based materials (e.g. , non-silicone based gap filler materials, thermoplastic and/or thermoset polymeric, elastomeric materials, etc.), silk screened materials, polyurethane foams or gels, thermally-conductive additives, etc. The thermal interface materials may be configured to have sufficient conformability, compliability, and/or softness (e.g. , without having to undergo a phase change or reflow, etc.) to adjust for tolerance or gaps by deflecting at low temperatures (e.g. , room temperature of 20 °C to 25 °C, etc.) and/or to allow the thermal interface materials to closely conform (e.g. , in a relatively close fitting and encapsulating manner, etc.) to a mating surface when placed in contact with (e.g. , compressed against, etc.) the mating surface, including a non-flat, curved, or uneven mating surface.

[0092] The thermal interface materials disclosed herein may include a soft thermal interface material formed from elastomer and at least one thermally-conductive metal, boron nitride, and/or ceramic filler, such that the soft thermal interface material is conformable even without undergoing a phase change or reflow. In some exemplary embodiments, the first and/or second thermal interface materials may include ceramic filled silicone elastomer, boron nitride filled silicone elastomer, or a thermal phase change material that includes a generally non-reinforced film.

[0093] Exemplary embodiments may include one or more thermal interface materials having a high thermal conductivity (e.g. , 1 W/mK (watts per meter per Kelvin), 1.1 W/mK, 1.2 W/mK, 2.8 W/mK, 3 W/mK, 3.1 W/mK, 3.8 W/mK, 4 W/mK, 4.7 W/mK, 5 W/mK, 5.4 W/mK, 6W/mK, etc.) depending on the particular materials used to make the thermal interface material and loading percentage of the thermally conductive filler, if any. These thermal conductivities are only examples as other embodiments may include a thermal interface material with a thermal conductivity higher than 6 W/mK, less than 1 W/mK, or other values between 1 and 6 W/mk. Accordingly, aspects of the present disclosure should not be limited to use with any particular thermal interface material as exemplary embodiments may include a wide range of thermal interface materials.

[0094] Exemplary embodiments may include one or more Tpcm™ 580 series phase change materials. Tpcm™ 580 series phase change materials may be inherently tacky, flexible, and exceptionally easy-to-use. Tpcm™ 580 series phase change materials may have thickness of about 0.003 inches, 0.005 inches, 0.008 inches, 0.010 inches, 0.016 inches, etc. At temperatures above its transition temperature (e.g. , about 50°C (122°F), etc.), Tpcm™ 580 series phase change materials may begin to soften and flow, filling microscopic irregularities of the components it comes into contact with, thereby providing an interface with low thermal contact resistance (e.g. , 0.013°C-in2/W at 50 psi, etc.). The gradual change in viscosity (softening) helps to reduce migration or pump-out. Tpcm™ 580 series phase change materials may include a top tabbed liner that can be removed immediately at assembly or provide a protective cover during shipping, and can be removed at assembly. Tpcm™ 580 series phase change materials may be meet environmental requirements including RoHS. Table 2 below includes additional details about Tpcm™ 580 series phase change materials.

TABLE 2

[0095] Exemplary embodiments may include one or more Tpcm 780 phase change materials. Tpcm™ 780 phase change material may be inherently tacky and may be easy to rework. Tpcm™ 780 phase change material may be silicone-free, soft, and begin to soften and flow at approximately 45°C. Tpcm™ 780 phase change material may reduce contact thermal resistance by filling microscopic irregularities of the components it contacts, and may be designed to reduce migration or pump out at CPU operating temperatures. Tpcm™ 780 phase change material may have a material formulation that softens but does not fully change phase, may be soft at room temperature such that there is less stress on the board during assembly, may be RoHS Compliant, may have 94V0 UL Flammability Rating and be naturally tacky at room temperature requiring no adhesive. Table 3 below includes additional details about Tpcm™ 780 phase change material. TABLE 3

utgass ng .

[0096] The BLS and thermally-conductive cores disclosed herein may be made from a wide range of materials in exemplary embodiments. By way of example, the BLS, the thermally-conductive core, or portions thereof may be made from cold rolled steel, nickel-silver alloys, copper-nickel alloys, stainless steel, tin-plated cold rolled steel, tin-plated copper alloys, carbon steel, brass, copper, aluminum, copper-beryllium alloys, phosphor bronze, steel, alloys thereof, a plastic material coated with electrically-conductive material, or any other suitable electrically-conductive and/or magnetic materials. The materials disclosed in this application are provided herein for purposes of illustration only as different materials may be used depending, for example, on the particular application.

[0097] In exemplary embodiments, a thermal interface material may be dispensed, extruded, insert molded, or otherwise applied to a cover or lid a board level shield (BLS). The BLS cover may be integral with or removably attachable to sidewalls of the BLS. For example, the BLS may include sidewalls that are integrally formed with the upper surface, cover, lid, or top of the BLS. In this example, the sidewalls and upper surface may be formed by stamping the same electrically-conductive piece of material and then folding the stamped material such that the sidewalls are generally perpendicular to the upper surface. Alternatively, the sidewalls may be made separately and not integrally formed with the upper surface of the BLS. In some exemplary embodiments, the BLS may comprise a two-piece shield in which the upper surface, cover, lid, or top is removable from and reattachable to the sidewalls. In some exemplary embodiments, the BLS may include one or more interior walls, dividers, or partitions that are attached to and/or integrally formed with the BLS. In such exemplary embodiments, the BLS cover, sidewalls, and interior walls may cooperatively define a plurality of individual EMI shielding compartments. The BLS frame may include a perimeter flange extending inwardly from the top of the sidewalls in some exemplary embodiments. Alternatively, the frame may be flangeless (without an inwardly extending flange) in other exemplary embodiments. Accordingly, aspects of the present disclosure should not be limited to any particular board level shield configuration.

[0098] Example embodiments disclosed herein 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.). For example, 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.). Generally, a heat source may comprise any component or device that has a higher temperature than a 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 any particular use with any single type of heat source, electronic device, heat removal/dissipation structure, etc.

[0099] Exemplary embodiments may provide one or more (but not necessarily any or all) of the following features or advantages, such as improving overall thermal efficiency without compromising on EMI shielding, reduced space requirements, lower cost, faster application, ease of design and manufacture, lower weight depending on the particular materials used, improved heat transfer from a device to ambient when used in conjunction with a board level shield, etc.

[0100] 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. In addition, advantages and improvements that may be achieved with one or more exemplary embodiments of the present disclosure are provided for purpose of illustration only and do not limit the scope of the present disclosure, as exemplary embodiments disclosed herein may provide all or none of the above mentioned advantages and improvements and still fall within the scope of the present disclosure.

[0101 ] Specific dimensions, specific materials, and/or specific shapes disclosed herein are example in nature and do not limit the scope of the present disclosure. The disclosure herein of particular values and particular ranges of values for given parameters are not exclusive of other values and ranges of values that may be useful in one or more of the examples disclosed herein. Moreover, it is envisioned that any two particular values for a specific parameter stated herein may define the endpoints of a range of values that may be suitable for the given parameter (i.e., the disclosure of a first value and a second value for a given parameter can be interpreted as disclosing that any value between the first and second values could also be employed for the given parameter). For example, if Parameter X is exemplified herein to have value A and also exemplified to have value Z, it is envisioned that parameter X may have a range of values from about A to about Z. Similarly, it is envisioned that disclosure of two or more ranges of values for a parameter (whether such ranges are nested, overlapping or distinct) subsume all possible combination of ranges for the value that might be claimed using endpoints of the disclosed ranges. For example, if 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.

[0102] The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises," "comprising," "including," and "having," are 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 are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.

[0103] When an element or layer is referred to as being "on", "engaged to", "connected to" or "coupled to" another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements 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 elements should be interpreted in a like fashion (e.g., "between" versus "directly between," "adjacent" versus "directly adjacent," etc.). As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

[0104] The term "about" when applied to values indicates that the calculation or the measurement allows some slight imprecision in the value (with some approach to exactness in the value; approximately or reasonably close to the value; nearly). 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 indicates at least variations that may arise from ordinary methods of measuring or using such parameters. For example, the terms "generally", "about", and "substantially" may be used herein to mean within manufacturing tolerances. Whether or not modified by the term "about", the claims include equivalents to the quantities.

[0105] 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 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.

[0106] 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. 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.

[0107] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements, intended or stated uses, or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same 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.

Claims

CLAIMS What is claimed is:

1. An assembly comprising:

a board level shield including first and second opposing sides and a portion having a thickness defined between the first and second opposing sides; and

a thermal interface material along the portion on the first side and/or the second side of the board level shield, the thermal interface material having a thickness equal to or less than the thickness of the portion of the board level shield defined between the first and second opposing sides.

2. The assembly of claim 1, wherein:

the board level shield has a higher thermal conductivity than the thermal interface material; and the thermal interface material has a predetermined minimum thickness and the portion of the board level shield has a predetermined maximum thickness defined between the first and second opposing sides, such that heat transfer efficiency is improved along a thermally-conductive heat path cooperatively defined by the thermal interface material and the portion of the board level shield.

3. The assembly of claim 1, wherein the thickness of the portion of the board level shield defined between the first and second opposing sides is greater than the thickness of the thermal interface material along the portion on the first side and/or the second side of the board level shield.

4. The assembly of claim 3, wherein the board level shield has a higher thermal conductivity than the thermal interface material such that the thickness of the portion of the board level shield defined between the first and second opposing sides being greater than the thickness of the thermal interface material improves heat transfer efficiency along a thermally-conductive heat path cooperatively defined by the thermal interface material and the portion of the board level shield.

5. The assembly of claim 1, wherein the thermal interface material comprises first and second thermal interface materials along the portion on the first and second sides, respectively, of the board level shield, and wherein the thickness of the portion of the board level shield defined between the first and second opposing sides is:

equal to or greater than a thickness of the first thermal interface; and/or

equal to or greater than a thickness of the second thermal interface material.

6. The assembly of claim 5, wherein the thickness of the portion of the board level shield defined between the first and second opposing sides is: greater than the thickness of the first thermal interface material; and

greater than the thickness of the second thermal interface material.

7. The assembly of claim 6, wherein the board level shield has a higher thermal conductivity than the first and second thermal interface materials such that the thickness of the portion of the board level shield defined between the first and second opposing sides being greater than the thicknesses of the first and second thermal interface materials improves heat transfer efficiency along a thermally-conductive heat path cooperatively defined by the first thermal interface material, the portion of the board level shield, and the second thermal interface material.

8. The assembly of claim 5, wherein the thickness of the portion of the board level shield defined between the first and second opposing sides is greater than a sum of the thickness of the first thermal interface material and the thickness of the second thermal interface material.

9. The assembly of claim 5, wherein:

a ratio of the thickness of the portion of the board level shield to the thickness of the first thermal interface material is at least 1 : 1 or higher; and/or

a ratio of the thickness of the portion of the board level shield to the thickness of the second thermal interface material is at least 1 : 1 or higher; and/or

a ratio of the thickness of the portion of the board level shield to a sum of the thickness of the first thermal interface material and the thickness of the second thermal interface material is at least 1: 1 or higher.

10. The assembly of claim 5, wherein:

a ratio of the thickness of the portion of the board level shield to the thickness of the first thermal interface material is at least 8: 1 or higher; and/or

a ratio of the thickness of the portion of the board level shield to the thickness of the second thermal interface material is at least 8: 1 or higher.

11. The assembly of claim 5, wherein:

a sum of the thickness of the portion of the board level shield defined between the first and second opposing sides, the thickness of the first thermal interface material, and the thickness of the second thermal interface material is about 0.75 millimeters; and/or

the thickness of the first thermal interface material is less than 0.5 millimeters, and the thickness of the second thermal interface material is less than 0.5 millimeters; and/or the thickness of the portion of the board level shield is about 0.6 millimeters or about 1 millimeter, the thickness of the first thermal interface material is about 0.075 millimeters, and the thickness of the second thermal interface material is less than 0.075 millimeters; and/or

the thickness of the portion of the board level shield is about 0.3 millimeters, the thickness of the first thermal interface material is about 0.225 millimeters, and the thickness of the second thermal interface material is less than 0.225 millimeters.

12. The assembly of any one of claims 1 to 11, wherein:

the board level shield is a single piece board level shield comprising a cover including the first and second opposing sides and the portion having the thickness defined between the first and second opposing sides, and one or more sidewalls that are integrally formed with the cover and that are configured for installation to a substrate generally about a heat source on the substrate, wherein the board level shield has a uniform thickness such that a thickness of the one or more sidewalls is equal to the thickness of the portion defined between the first and second opposing sides, or wherein the board level shield has a non-uniform thickness such that a thickness of the one or more sidewalls is less than the thickness of the portion defined between the first and second opposing sides; or

the board level shield is a multi-piece board level shield comprising one or more sidewalls that are configured for installation to a substrate generally about a heat source on the substrate, and a cover removably attachable to the one or more sidewalls, the cover including the first and second opposing sides and the portion having the thickness defined between the first and second opposing sides, wherein the board level shield has a uniform thickness such that a thickness of the one or more sidewalls is equal to the thickness of the portion defined between the first and second opposing sides, or wherein the board level shield has a non-uniform thickness such that a thickness of the one or more sidewalls is less than the thickness of the portion defined between the first and second opposing sides.

13. An electronic device comprising a heat removal/dissipation structure, a printed circuit board having a heat source, and the assembly of any one of claims 1 to 11, whereby the board level shield is operable for providing electromagnetic interference shielding for the heat source, and whereby heat is transferrable from the heat source to the heat removal/dissipation structure along a thermally- conductive path cooperatively defined by the thermal interface material and the portion of the board level shield to the heat removal/dissipation structure.

14. A method of enhancing effective thermal conductivity of a board level shield, the method comprising providing a board level shield that includes first and second opposing sides and a portion having a thickness defined between the first and second opposing sides that is equal to or greater than a thickness of a thermal interface material along the portion on the first side and/or the second side of the board level shield.

15. The method of claim 14, wherein:

the board level shield has a higher thermal conductivity than the thermal interface material; and the method includes determining a minimum thickness for the thermal interface material and a maximum thickness for the portion of the board level shield defined between the first and second opposing sides such that heat transfer efficiency is improved along a thermally-conductive heat path cooperatively defined by the thermal interface material and the portion of the board level shield.

16. The method of claim 14, wherein:

the thickness of the portion of the board level shield defined between the first and second opposing sides is greater than the thickness of the thermal interface material along the portion on the first side and/or the second side of the board level shield; and

the board level shield has a higher thermal conductivity than the thermal interface material such that the thickness of the portion of the board level shield defined between the first and second opposing sides being greater than the thickness of the thermal interface material improves heat transfer efficiency along a thermally-conductive heat path cooperatively defined by the thermal interface material and the portion of the board level shield.

17. The method of claim 14, wherein the method includes:

determining a thickness of a first air gap that will be defined between the first side of the board level shield and a heat source on a substrate after the board level shield is installed on the substrate, and increasing the thickness of the portion of the board level shield defined between the first and second opposing sides to help fill the first air gap and improve heat transfer; and/or

determining a thickness of a second air gap that will be defined between the second side of the board level shield and a heat removal/dissipation structure, and increasing the thickness of the portion of the board level shield defined between the first and second opposing sides to help fill the second air gap and improve heat transfer.

18. The method of claim 14, wherein the thermal interface material comprises first and second thermal interface materials along the portion on the first and second sides, respectively, of the board level shield, and wherein the thickness of the portion of the board level shield defined between the first and second opposing sides is: equal to or greater than a thickness of the first thermal interface material; and/or

equal to or greater than a thickness of the second thermal interface material.

19. The method of claim 18, wherein:

the thickness of the portion of the board level shield defined between the first and second opposing sides is greater than the thickness of the first thermal interface material, and greater than the thickness of the second thermal interface material; and

the board level shield has a higher thermal conductivity than the first and second thermal interface materials such that the thickness of the portion of the board level shield defined between the first and second opposing sides being greater than the thicknesses of the first and second thermal interface materials improves heat transfer efficiency along a thermally-conductive heat path cooperatively defined by the first thermal interface material, the portion of the board level shield, and the second thermal interface material.

20. The method of claim 18, wherein the thickness of the portion of the board level shield defined between the first and second opposing sides is greater than a sum of the thickness of the first thermal interface material and the thickness of the second thermal interface material.

21. The method of claim 18, wherein:

a ratio of the thickness of the portion of the board level shield to the thickness of the first thermal interface material is within a range from 1 : 1 to 8: 1 or is higher than 8: 1; and/or

a ratio of the thickness of the portion of the board level shield to the thickness of the second thermal interface material is within a range from 1 : 1 to 8: 1 or is higher than 8: 1; and/or

22. The method of claim 18, wherein the method includes:

increasing the thickness of the portion of the board level shield to be at least 8 times thicker than the thickness of the first thermal interface material such that a ratio of the thickness of the portion of the board level shield to the thickness of the first thermal interface material is 8: 1 or more; and/or

increasing the thickness of the portion of the board level shield to be at least 8 times thicker than the thickness of the second thermal interface material such that a ratio of the thickness of the portion of the board level shield to the thickness of the second thermal interface material is 8: 1 or more.

23. The method of claim 18, wherein the method includes: making the board level shield such that the thickness of the portion of the board level shield is greater than the thickness of the first thermal interface material and greater than the thickness of the second thermal interface material;

applying the first thermal interface material along the portion on the first side of the board level shield; and

applying the second thermal interface material along the portion on the second side of the board level shield.

24. The method of any one of claims 18 to 23, further comprising:

positioning the first thermal interface material against a heat source; and

positioning the second thermal interface material against a heat removal/dissipation structure; whereby heat is transferrable from the heat source to the heat removal/dissipation structure along a thermally-conductive path defined from the first thermal interface material through the portion of the board level shield to the second thermal interface material; and

whereby the board level shield is operable for providing electromagnetic interference (EMI) shielding for the heat source.

25. The method of any one of claims 16 to 23, wherein:

26. The method of claim 25, further comprising installing the one or more sidewalls of the board level shield to the substrate generally about the heat source on the substrate, such that:

heat from the heat source is transferrable along a thermally-conductive heat path cooperatively defined by the thermal interface material and the portion of the board level shield to a heat removal/dissipation structure; and

the board level shield is operable for providing electromagnetic interference (EMI) shielding for the heat source.

27. A thermally-conductive interface assembly comprising:

a thermally-conductive core having first and second opposing sides and a portion having a thickness defined between the first and second opposing sides;

a first thermal interface material along the portion on the first side of the thermally-conductive core and having a thickness equal to or less than the thickness of the portion of the thermally-conductive core; and

a second thermal interface material along the portion on the second side of the thermally- conductive core and having a thickness equal to or less than the thickness of the portion of the thermally-conductive core;

wherein the thermally-conductive core has a higher thermal conductivity than a thermal conductivity of the first and second thermal interface materials; and

wherein the first and second thermal interface materials are more conformable than the thermally-conductive core.

28. The thermally-conductive interface assembly of claim 27, wherein the thickness of the portion of the thermally-conductive core defined between the first and second opposing sides is:

greater than the thickness of the first thermal interface material; and

greater than the thickness of the second thermal interface material.

29. The thermally-conductive interface assembly of claim 27, wherein the thickness of the portion of the thermally-conductive core defined between the first and second opposing sides is greater than a sum of the thickness of the first thermal interface material and the thickness of the second thermal interface material.

30. The thermally-conductive interface assembly of claim 27: a ratio of the thickness of the portion of the thermally-conductive core to the thickness of the first thermal interface material is at least 1 : 1 or higher; and/or

a ratio of the thickness of the portion of the thermally-conductive core to the thickness of the second thermal interface material is at least 1 : 1 or higher; and/or

a ratio of the thickness of the portion of the thermally-conductive core to a sum of the thickness of the first thermal interface material and the thickness of the second thermal interface material is at least 1 : 1 or higher.

31. The thermally-conductive interface assembly of claim 27, wherein:

a ratio of the thickness of the portion of the thermally-conductive core to the thickness of the first thermal interface material is at least 8: 1 or higher; and/or

a ratio of the thickness of the portion of the thermally-conductive core to the thickness of the second thermal interface material is at least 8: 1 or higher.

32. The thermally-conductive interface assembly of claim 27, wherein

the thickness of the first thermal interface material is less than 0.5 millimeters, and the thickness of the second thermal interface material is less than 0.5 millimeters;

the thermally-conductive core comprises metal, aluminum, cold rolled steel, nickel silver, and/or stainless steel;

the first thermal interface material comprises an extrudable thermal interface material, an insert moldable thermal interface material, a dispensable thermal interface material, a thermal putty, a thermal gap filler, a thermal phase change material, a thermally-conductive EMI absorber or hybrid thermal/EMI absorber, a thermal pad, a thermal grease, and/or a thermal paste; and

the second thermal interface material comprises an extrudable thermal interface material, an insert moldable thermal interface material, a dispensable thermal interface material, a thermal putty, a thermal gap filler, a thermal phase change material, a thermally-conductive EMI absorber or hybrid thermal/EMI absorber, a thermal pad, a thermal grease, and/or a thermal paste.

33. The thermally-conductive interface assembly of claim 27, wherein:

the thermally-conductive core comprises aluminum;

the first thermal interface material comprises a soft thermal gap filler; and

the second thermal interface material comprises a soft thermal gap filler.

34. The thermally-conductive interface assembly of claim 27, wherein: the thermally-conductive core comprises an aluminum core having a thickness of about 1 millimeters;

the first thermal interface material comprises a soft thermal gap filler having a thickness of about .075 millimeters; and

the second thermal interface material comprises a soft thermal gap filler having a thickness of about .075 millimeters,

whereby a ratio of the thickness of the aluminum core to the thickness of the soft thermal gap filler of the first thermal interface material is greater than 13: 1; and

whereby a ratio of the thickness of the aluminum core to the thickness of the soft thermal gap filler of the second thermal interface material is greater than 13: 1.

35. An electronic device including a heat removal/dissipation structure, a printed circuit board having one or more heat sources, and the thermally-conductive interface assembly of any one of claims 27 to 34 positioned relative to the one or more heat sources such that the thermally-conductive interface assembly is operable for providing electromagnetic interference shielding for the one or more heat sources and such that heat is transferrable from the one or more heat sources to the heat removal/dissipation structure along a thermally-conductive path cooperatively defined by the first thermal interface material, the portion of the thermally-conductive core, and the second thermal interface material to the heat removal/dissipation structure.

36. A board level shielding assembly comprising the thermally-conductive interface assembly of any one of claims 27 to 34, wherein the board level shielding assembly has an effective thermal conductivity of 13 W/mK or more.