Thermal conductivity measurement method and measurement device

Abstract

The application belongs to the technical field of micro-nano scale thermal measurement, and particularly relates to a thermal conductivity measurement method and a measurement device. The thermal conductivity measurement method comprises the following steps: providing a heat sink, a plurality of micro-nano devices and a sample to be measured, wherein the micro-nano devices have a first thermal resistance, the sample to be measured has a second thermal resistance, the sample to be measured and the heat sink and each contact area form a contact thermal resistance, the first thermal resistance is greater than the second thermal resistance and greater than the contact thermal resistance; applying a heating power to a thermal measurement circuit of a first micro-nano device; obtaining actual contact temperatures of contact areas of the sample to be measured and adjacent second and third micro-nano devices; obtaining actual heat flow powers of a part corresponding to the second and third micro-nano devices flowing through the sample to be measured; calculating a thermal conductivity of the sample to be measured; and calculating the thermal conductivity of the sample to be measured according to the geometric size and the thermal conductivity of the sample to be measured. The application can exclude the influence of the contact thermal resistance, improve the measurement accuracy, and has a simple structure, low cost and is suitable for mass production.

Description

Technical Field

[0001] This application relates to the field of micro-nano scale thermal measurement technology, and more specifically, to a method and apparatus for measuring thermal conductivity. Background Technology

[0002] With the development of micro- and nanotechnology, novel fibers, carbon nanotubes, semiconductor quantum dots and superlattices, and nanoparticles are increasingly being used in aerospace, detection, energy conversion, and medical and health fields. In the application of nanotechnology, thermal properties are crucial for nanomaterials. Measuring and characterizing thermal parameters such as thermal conductivity, thermal diffusivity, and specific heat capacity at the micro / nano scale is an important means of studying phonon motion, heat transport, and defects at the microscale. As the characteristic dimensions of materials decrease to the micrometer or even nanometer level, their thermal conductivity, thermal diffusivity, and even other thermal parameters exhibit significant differences, demonstrating a clear scale effect. Because low-dimensional materials are relatively thin, surface thermal radiation has a significant impact on thermal conductivity measurements. Traditional methods for measuring the thermal conductivity of macroscopic materials, such as the hot-wire method, flash method, photothermal reflection method, and photoacoustic method, are no longer suitable for measuring the thermal conductivity of low-dimensional materials. Furthermore, existing thermal conductivity measurement methods suffer from poor measurement accuracy due to contact thermal resistance. Summary of the Invention

[0003] The purpose of this application is to provide a method and device for measuring thermal conductivity, which can eliminate the influence of contact thermal resistance, improve the measurement accuracy of materials at the micro / nano scale, and has a simple structure, low cost, and is suitable for mass production.

[0004] In a first aspect, embodiments of this application provide a method for measuring thermal conductivity, comprising: providing a heat sink, multiple micro / nano devices, and a sample to be tested; the heat sink having a cavity of a predetermined length; the micro / nano devices having contact areas and thermal measurement circuits electrically connected to the contact areas; the multiple micro / nano devices being spaced apart on the heat sink along the length direction of the cavity; one end of the sample to be tested contacting the heat sink; and the other end of the sample to be tested contacting the contact areas of the multiple micro / nano devices at different positions along its own length direction; wherein the micro / nano devices have a first thermal resistance, the sample to be tested has a second thermal resistance, and contact thermal resistances are formed between the sample to be tested and the heat sink, and between the sample to be tested and each contact area; the first thermal resistance is greater than the second thermal resistance, and the first thermal resistance is greater than the contact thermal resistance. Thermal resistance; A temperature gradient is formed along the length of the sample by applying heating power Q to the thermal measurement circuit of the first micro / nano device; The actual contact temperatures T2 and T3 of the contact areas between the sample and the adjacent second and third micro / nano devices are obtained; The actual heat flow power Q0 corresponding to the portion of the sample between the second and third micro / nano devices is obtained; Based on the actual heat flow power Q0, the actual contact temperatures T2 and T3 are used to calculate the thermal conductivity G = Q0 / (T3-T2) of the sample; Based on the geometric dimensions and thermal conductivity of the sample, the thermal conductivity λ = G × L / S is calculated, where L is the length of the sample and S is the cross-sectional area of ​​the sample.

[0005] In addition, the thermal conductivity measurement method of this application may also have the following additional technical features:

[0006] In some embodiments of this application, the ratio of the first thermal resistance to the second thermal resistance is greater than 20, and the ratio of the first thermal resistance to the contact thermal resistance is greater than 20.

[0007] In some embodiments of this application, the first thermal resistance is greater than 10. 6 K / W, the second thermal resistance and the contact thermal resistance are both less than 5×10 4 K / W.

[0008] In some embodiments of this application, the distance between the second and third micro / nano devices is greater than 10 times the diameter of the outer contour dimension of the cross-section of the sample under test.

[0009] In some embodiments of this application, the actual heat flux power Q0≈Q; and / or, the actual contact temperature between the sample under test and the contact area of ​​the second micro / nano device T2≈T2', and the actual contact temperature between the sample under test and the contact area of ​​the third micro / nano device T3≈T3', wherein T2' and T3' are the temperatures measured by the respective thermal measurement circuits of the second and third micro / nano devices, respectively.

[0010] In some embodiments of this application, the actual heat flow power Q0 = Q - Q', where Q' is the sum of the heat power lost by the first and second micro / nano devices; the actual contact temperatures between the sample under test and the second and third contact areas are T2 = T2' × (R2' + R0) / R0 and T3 = T3' × (R3' + R0) / R0, respectively, where T2' is the temperature measured by the thermal measurement circuit of the second micro / nano device, T3' is the temperature measured by the respective thermal measurement circuit of the third micro / nano device, R2' is the contact thermal resistance formed by the sample under test contacting the second micro / nano device, R3' is the contact thermal resistance formed by the sample under test contacting the third micro / nano device, and R0 is the first thermal resistance.

[0011] In some embodiments of this application, the sum of the heat power lost by the first micro / nano device and the second micro / nano device is Q' = Q1' + Q2', where the heat power lost by the first micro / nano device is Q1', and Q1' = T1' × R0, where T1' is the temperature measured by the thermal measurement circuit of the first micro / nano device; the heat power lost by the second micro / nano device is Q2', and Q2' = T2' × R0.

[0012] In some embodiments of this application, the contact thermal resistance formed by the sample under test and the second micro / nano device is: R2' = (T 2测 -T 1测 ) / Q 2测 The contact thermal resistance formed when the sample under test comes into contact with the third micro / nano device is: R3' = (T 3测 -T 2测 ) / Q 3测 , where Q 2测 The test power applied to the second micro / nano device, T 1测 T 2测 These represent the temperatures measured by the respective thermal measurement circuits of the first and second micro / nano devices at this point; Q 3测 To measure the test power applied to the third micro / nano device, T 2测 T 3测 These are the temperatures measured by the thermal measurement circuits of the second and third micro / nano devices, respectively.

[0013] In some embodiments of this application, the contact methods between the sample under test and the heat sink, and between the sample under test and the contact areas of each micro / nano device, include direct contact, organic solvent immersion-drying optimized contact, and thermal interface material reinforced contact.

[0014] Secondly, embodiments of this application provide a thermal conductivity measuring device, comprising: a heat sink having a cavity of a preset length; a plurality of micro / nano devices spaced apart on the heat sink along the length direction of the cavity, each micro / nano device having a contact area and a thermal measurement circuit electrically connected to the contact area; one end of a sample to be tested is in contact with the heat sink; different positions of the sample to be tested along its own length direction are respectively in contact with the contact areas of the plurality of micro / nano devices; wherein, the micro / nano devices have a first thermal resistance, the sample to be tested has a second thermal resistance, and contact thermal resistances are formed between the sample to be tested and the heat sink and between the sample to be tested and each contact area; the first thermal resistance is greater than the second thermal resistance, and the first thermal resistance is greater than the contact thermal resistance.

[0015] According to the thermal conductivity measurement method and device provided in the embodiments of this application, by decoupling the heat flow test and the temperature test, and by utilizing the fact that the first thermal resistance of the micro / nano device itself is greater than the second thermal resistance of the sample under test and the contact thermal resistance between the two, the accuracy of the heat flow and temperature measurement of the sample under test can be ensured, thereby eliminating the influence of contact thermal resistance, improving the measurement accuracy of materials at the micro / nano scale, and having a simple structure, low cost, and suitability for mass production.

[0016] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0017] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. Wherein:

[0018] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. Wherein:

[0019] Figure 1 This is a schematic diagram of the thermal conductivity measuring device according to an embodiment of this application;

[0020] Figure 2 for Figure 1 A partially enlarged schematic diagram of the thermal conductivity measuring device shown.

[0021] Figure 3 This is a flowchart of the thermal conductivity measurement method according to an embodiment of this application.

[0022] The labels in the attached diagram are as follows:

[0023] 100. Thermal conductivity measuring device;

[0024] 10. Heat sink; 11. Cavity; 20. Micro / nano devices; 21. Contact area; 22. Thermal measurement circuit;

[0025] 30. Sample to be tested. Detailed Implementation

[0026] Exemplary embodiments of this application will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of this application are shown in the drawings, it should be understood that this application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of this application and to fully convey the scope of this application to those skilled in the art.

[0027] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0028] Although terms such as first, second, third, etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Therefore, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0029] For ease of description, spatial relative terms may be used in the text to describe the relationship of one element or feature relative to another element or feature, as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "below," "above," "over," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure. For example, if the device in the figure is flipped, an element described as "below other elements or features" or "below other elements or features" would subsequently be oriented as "above other elements or features" or "above other elements or features." Therefore, the example term "below" can include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or in other directions), and the spatial relative descriptors used in the text will be interpreted accordingly.

[0030] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0031] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0032] Figure 1 This is a schematic diagram of the thermal conductivity measuring device according to an embodiment of this application. Figure 2 for Figure 1 The diagram shows a partially enlarged view of the thermal conductivity measuring device.

[0033] See Figure 1 and Figure 2 This application provides a thermal conductivity measuring device 100 for measuring the thermal conductivity of a sample 30. The thermal conductivity measuring device 100 includes a heat sink 10 and multiple micro / nano devices 20.

[0034] The heat sink 10 has a cavity 11 of a predetermined length. The temperature of the heat sink 10 does not change with the amount of heat energy transferred to it; it can be the atmosphere, the ground, or other objects. In this embodiment, the heat sink 10 can be made of a miniature heat sink for cooling electronic chips. The heat sink 10 has high thermal conductivity to ground, which can be greater than 1 mW / K.

[0035] Multiple micro / nano devices 20 are spaced apart on the heat sink 10 along the length of the cavity 11. Each micro / nano device 20 has a contact area 21 and a thermal measurement circuit 22 electrically connected to the contact area 21. The micro / nano devices 20 can be made of silicon nitride thin film. The thermal measurement circuit 22 is used to apply heat to the micro / nano devices 20 and also to measure the temperature of the object in contact with the contact area 21.

[0036] One end of the sample to be tested 30 is in contact with the heat sink 10, and the other end of the sample to be tested 30 is in contact with the contact areas 21 of multiple micro-nano devices 20 at different positions along its own length. The micro-nano devices 20 have a first thermal resistance, and the sample to be tested 30 has a second thermal resistance. Contact thermal resistances are formed between the sample to be tested 30 and the heat sink 10 and between the sample to be tested 30 and each contact area 21. The first thermal resistance is greater than the second thermal resistance and the first thermal resistance is greater than the contact thermal resistance.

[0037] In this embodiment, the number of micro / nano devices 20 is at least three. At least one micro / nano device 20 is used to apply heating power, and the heating current can be direct current or alternating current. At least two micro / nano devices 20 are used to measure the temperature of the sample 30 to be tested, which is in contact with the contact area 21. The material of the sample 30 to be tested can be any of platinum, gold, silver, or intrinsic silicon, and the cross-sectional shape of the sample 30 to be tested can be circular or polygonal.

[0038] Optionally, one end of the sample 30 is in contact with the heat sink 10 via a thermally conductive adhesive such as silver paste, improving the electrical conductivity between the sample 30 and the heat sink 10. Different positions along the length of the sample 30 correspond to contact areas 21 of multiple micro / nano devices 20. Optionally, the contact methods between the sample 30 and the heat sink 10, and between the sample 30 and the contact areas 21 of the micro / nano devices 20, include direct contact, organic solvent immersion-drying optimized contact, and thermal interface material-enhanced contact.

[0039] Optionally, the resistance of the contact area 21 of the micro / nano device 20 is 1kΩ to 50kΩ. Optionally, the resistance of the contact area 21 is 35kΩ to 50kΩ. This setting ensures that the initial thermal resistance of the micro / nano device 20 itself is greater than the contact resistance formed between the contact area 21 and the sample 30 under test.

[0040] The thermal conductivity measurement method of this application embodiment is described in detail below with reference to the accompanying drawings. It is applied to the thermal conductivity measurement device 100 as described above.

[0041] Figure 3 This is a flowchart of the thermal conductivity measurement method according to an embodiment of this application.

[0042] See Figure 1 and Figure 3 The present application provides a method for measuring thermal conductivity, which includes the following steps S1 to S7.

[0043] Step S1: Provide a heat sink 10, multiple micro / nano devices 20, and a sample 30 to be tested. The heat sink 10 has a cavity 11 of a preset length. The micro / nano devices 20 are provided with a contact area 21 and a thermal measurement circuit 22 electrically connected to the contact area 21. The temperature of the heat sink 10 does not change with the amount of heat energy transferred to it; it can be the atmosphere, the ground, or other objects. In this embodiment, the heat sink 10 can be made of a miniature heat sink for cooling electronic chips. The heat sink 10 has high thermal conductivity to ground, which can be greater than 1 mW / K.

[0044] Step S2: Multiple micro / nano devices 20 are spaced apart on the heat sink 10 along the length of the cavity 11. One end of the sample to be tested 30 is in contact with the heat sink 10, and the other end of the sample to be tested 30 is in contact with the contact areas 21 of the multiple micro / nano devices 20 at different positions along its own length. The micro / nano devices 20 have a first thermal resistance, the sample to be tested 30 has a second thermal resistance, and contact thermal resistances are formed between the sample to be tested 30, the heat sink 10, and each contact area 21. The first thermal resistance is greater than the second thermal resistance, and the first thermal resistance is greater than the contact thermal resistance.

[0045] Step S3: A temperature gradient is formed along the length of the sample 30 by applying heating power Q to the thermal measurement circuit 22 of the first micro / nano device 20;

[0046] Step S4: Obtain the actual contact temperatures T2 and T3 of the contact areas 21 between the sample to be tested 30 and the adjacent second and third micro / nano devices 20, respectively;

[0047] Step S5: Obtain the actual heat flow power Q0 of the portion of the sample 30 flowing through the test sample corresponding to the portion between the second micro / nano device 20 and the third micro / nano device 20;

[0048] Step S6: Calculate the thermal conductivity G of the sample 30 to be tested, based on the actual heat flow power Q0, actual contact temperatures T2 and T3, and Q0 = Q0 / (T3-T2).

[0049] Step S7: Based on the geometric dimensions and thermal conductivity of the sample 30 to be tested, calculate the thermal conductivity λ = G × L / S, where L is the length of the sample 30 to be tested and S is the cross-sectional area of ​​the sample 30 to be tested.

[0050] In this embodiment, the number of micro / nano devices 20 is at least three. At least one micro / nano device 20 is used to apply heating power, and the heating current can be either direct current or alternating current. At least two micro / nano devices 20 are used to measure the temperature of the sample 30 to be tested, which is in contact with the contact area 21. Specifically, the thermal measurement circuit 22 of at least one micro / nano device 20 is used to apply heat to the micro / nano device 20, and the thermal measurement circuit 22 of at least two micro / nano devices 20 is used to measure the temperature of the sample 30 to be tested, which is in contact with the contact area 21 of the micro / nano device 20.

[0051] like Figure 1 As shown, there are three micro / nano devices 20. Along the cavity 11 of the heat sink 10 from right to left, the rightmost micro / nano device 20 is the first micro / nano device 20, the middle micro / nano device 20 is the second micro / nano device 20, and the leftmost micro / nano device 20 is the third micro / nano device 20. A temperature gradient is formed along the length of the sample 30 by applying a heating power Q to the thermal measurement circuit 22 of the first micro / nano device 20.

[0052] If the first thermal resistance of the micro / nano device 20 is much greater than the second thermal resistance of the sample 30 under test, and the first thermal resistance is much greater than the contact thermal resistance, then the heat loss through the micro / nano device 20 can be ignored, and the heat loss through the micro / nano device 20 is related to its own first thermal resistance.

[0053] If the first thermal resistance of the micro / nano device 20 is greater than the second thermal resistance of the sample 30 under test, and the first thermal resistance is greater than the contact thermal resistance, for example, the ratio of the first thermal resistance to the second thermal resistance is greater than 20, and the ratio of the first thermal resistance to the contact thermal resistance is greater than 20, then the contact thermal resistance between the contact area 21 and the sample 30 under test can be calculated based on the first thermal resistance of the micro / nano device 20 itself and the measured temperature. Thus, the heat loss through the micro / nano device 20 can be calculated, and the actual heat flow power Q0 through a certain section of the sample 30 under test and the temperature difference between the two ends of that certain section of the sample 30 under test can be obtained. The thermal conductivity G of the sample 30 under test can then be obtained. Finally, based on the geometric dimensions of the sample 30 under test and the thermal conductivity G, the thermal conductivity λ of the sample 30 under test can be calculated.

[0054] Therefore, the thermal conductivity measurement method of this embodiment decouples the heat flow test and the temperature test, and at the same time utilizes the fact that the first thermal resistance of the micro / nano device 20 itself is much greater than the second thermal resistance of the sample 30 under test and the contact thermal resistance between the two, to ensure the accuracy of the heat flow and temperature measurement through the sample 30 under test. This eliminates the influence of contact thermal resistance, improves the measurement accuracy of materials at the micro / nano scale, and has a simple structure, low cost, and is suitable for mass production.

[0055] In some embodiments, the ratio of the first thermal resistance to the second thermal resistance is greater than 20, and the ratio of the first thermal resistance to the contact thermal resistance is greater than 20. For example, if the ratio of the first thermal resistance to the second thermal resistance is greater than 50, and the ratio of the first thermal resistance to the contact thermal resistance is greater than 50, then heat loss through the micro / nano device 20 can be ignored. This thermal resistance relationship ensures that the heating power Q and the heat flow error through the sample 30 are small, as well as that the error between the temperature value measured by the thermal measurement circuit 22 and the actual contact temperature of the sample 30 is small.

[0056] In some embodiments, the first thermal resistance is greater than 10. 6 K / W, the second thermal resistance and the contact thermal resistance are both less than 5×10 4 K / W. For example, the first thermal resistance is 5 × 10⁻⁶. 6 K / W, the second thermal resistance and the contact thermal resistance are both 2×10 4 K / W, at which point the heat loss through the micro / nano device 20 can be ignored.

[0057] In some embodiments, the distance between the second micro / nano device 20 and the third micro / nano device 20 is greater than 10 times the diameter of the outer contour dimension of the cross-section of the sample under test 30.

[0058] like Figure 1 and Figure 2 As shown, the cross-section of the sample 30 is circular. The distance between the second and third micro / nano devices 20 is greater than 10 times the diameter of the sample 30. This allows us to ignore the influence of the radial temperature gradient of the sample 30 on the measurement result of thermal conductivity λ. It can be understood that when the cross-section of the sample 30 is polygonal, the diameter of its outer contour is the diameter of the circumcircle of the polygon.

[0059] In some embodiments, the actual heat flow power Q0≈Q; and / or, the actual contact temperature T2≈T2' between the sample under test 30 and the contact area 21 of the second micro / nano device 20, and the actual contact temperature T3≈T3' between the sample under test 30 and the contact area 21 of the third micro / nano device 20, wherein T2' and T3' are the temperatures measured by the respective thermal measurement circuits 22 of the second and third micro / nano devices 20, respectively.

[0060] As mentioned earlier, if the ratio of the first thermal resistance of the micro / nano device 20 to the second thermal resistance of the sample 30 under test is greater than 50, then the heat loss through the micro / nano device 20 can be ignored. That is, when a heating power Q is applied to the thermal measurement circuit 22 of the first micro / nano device 20 to form a temperature gradient along the length of the sample 30 under test, the actual heat flow power Q0 ≈ Q of the portion of the sample 30 under test corresponding to the portion between the second and third micro / nano devices 20 is approximately equal to the heat flow power.

[0061] In addition, the actual contact temperature between the sample 30 and the contact area 21 of the second micro / nano device 20 is T2, and T2 = T2' × (R2' + R0) / R0;

[0062] The actual contact temperature between the sample 30 and the contact area 21 of the third micro / nano device 20 is T3, and

[0063] T3 = T3' × (R3' + R0) / R0;

[0064] Wherein, T2' and T3' are the temperatures measured by the thermal measurement circuits 22 of the second and third micro-nano devices 20, respectively; R2' and R3' are the contact thermal resistances between the contact areas 21 of the second and third micro-nano devices 20 and the sample 30 to be tested, respectively; and R0 is the first thermal resistance of the micro-nano device 20.

[0065] Since the ratio of the first thermal resistance R0 to the contact thermal resistances R2' and R3' is greater than 50, T2≈T2' and T3≈T3'.

[0066] Therefore, based on the actual heat flow power Q0 and the actual contact temperatures T2 and T3, the thermal conductivity of the sample 30 under test is calculated as G = Q0 / (T3-T2) = Q / (T3'-T2').

[0067] Based on the geometric dimensions and thermal conductivity G of the sample 30 to be tested, the thermal conductivity λ of the sample 30 to be tested is calculated as λ = G × L / S, where L is the length of the sample 30 to be tested and S is the cross-sectional area of ​​the sample 30 to be tested.

[0068] In this embodiment, a test sample 30 with different geometric dimensions and made of platinum, gold, silver and intrinsic silicon is used as an example. The thermal conductivity λ of the test sample 30 is measured using the thermal conductivity measurement method described above, and the measurement results are compared with the thermal conductivity λ recorded in relevant literature, as shown in Table 1.

[0069] Table 1

[0070]

[0071]

[0072] Based on the thermal conductivity λ measured in Table 1 and the thermal conductivity λ recorded in relevant literature, it can be seen that the measurement error of thermal conductivity λ is less than 5%, indicating high measurement accuracy.

[0073] The following describes a method for calculating the thermal conductivity λ of the sample 30 under test, taking into account the heat loss flowing through the micro / nano device 20.

[0074] In some embodiments, the actual heat flux power Q0 = Q - Q', where Q' is the sum of the heat power lost by the first micro / nano device 20 and the second micro / nano device 20; the actual contact temperatures between the sample under test 30 and the contact areas 21 of the second and third micro / nano devices 20 are respectively T2 = T2' × (R2' + R0) / R0, T3 = T3' ×

[0075] (R3'+R0) / R0, where T2' is the temperature measured by the thermal measurement circuit 22 of the second micro / nano device 20, T3' is the temperature measured by the thermal measurement circuit 22 of the third micro / nano device 20, R2' is the contact thermal resistance formed when the sample 30 under test comes into contact with the second micro / nano device 20, R3' is the contact thermal resistance formed when the sample 30 under test comes into contact with the third micro / nano device 20, and R0 is the first thermal resistance.

[0076] In this embodiment, according to steps S3 to S5 of the thermal conductivity measurement method, a temperature gradient is formed along the length direction of the sample 30 by applying heating power Q to the thermal measurement circuit 22 of the first micro-nano device 20. The actual heat flow power Q0 = Q - Q' flowing through the sample 30 corresponding to the part between the second micro-nano device 20 and the third micro-nano device 20 is obtained. The actual contact temperatures T2 and T3 between the sample 30 and the second micro-nano device 20 and the third contact area 21 are obtained. The actual contact temperatures T2 and T3 are related to the contact thermal resistance, the first thermal resistance and the temperature measured by the thermal measurement circuit 22.

[0077] Since this measurement method takes into account the heat loss flowing through the micro / nano device 20 and eliminates the influence of contact thermal resistance, it can improve the measurement accuracy of the thermal conductivity λ of the sample 30 under test.

[0078] In some embodiments, the sum of the heat power lost by the first micro / nano device 20 and the second micro / nano device 20 is Q' = Q1' + Q2', where the heat power lost by the first micro / nano device 20 is Q1' and Q1' = T1' × R0, T1' is the temperature measured by the thermal measurement circuit 22 of the first micro / nano device 20, and the heat power lost by the second micro / nano device 20 is Q2' and Q2' = T2' × R0.

[0079] Since T1' is the temperature measured by the thermal measurement circuit 22 of the first micro / nano device 20, the data can be read directly; R0 is the first thermal resistance of the first micro / nano device 20, and the heat power lost by the first micro / nano device 20 can be calculated as Q1'. Similarly, the heat power lost by the first micro / nano device 20 can be calculated as Q2', and thus the sum of the lost heat power Q' can be calculated.

[0080] In some embodiments, the contact thermal resistance formed when the sample under test 30 contacts the second micro / nano device 20 is:

[0081] R2'=(T 2测 -T 1测 ) / Q 2测 The contact thermal resistance formed when the sample 30 and the third micro / nano device 20 come into contact is:

[0082] R3'=(T 3测 -T 2测 ) / Q 3测 ,

[0083] Among them, Q 2测 To apply the test power to the second micro / nano device 20, T 1测 T 2测 These represent the temperatures measured by the respective thermal measurement circuits 22 of the first and second micro / nano devices 20 at this time; Q 3测 To the test power applied to the third micro / nano device 20, T 2测 T 3测 The temperatures measured by the thermal measurement circuits 22 of the second and third micro / nano devices 20 at this time are respectively.

[0084] Based on the calculated contact thermal resistances R2' and R3' of the second and third micro-nano devices 20, the actual contact temperatures T2 and T3 between the sample under test 30 and the respective contact areas 21 of the second and third micro-nano devices 20 can be obtained.

[0085] Based on the calculated actual heat flux power Q0=Q-Q', and the actual contact temperatures T2 and T3, the thermal conductivity of the sample 30 is calculated as G=Q0 / (T3-T2)=Q / (T 3测 -T 2测 );

[0086] Based on the geometric dimensions and thermal conductivity G of the sample 30 to be tested, the thermal conductivity λ of the sample 30 to be tested is calculated as λ = G × L / S, where L is the length of the sample 30 to be tested and S is the cross-sectional area of ​​the sample 30 to be tested.

[0087] In this embodiment, a test sample 30 with different geometric dimensions and made of platinum, gold, silver and intrinsic silicon is used as an example. The thermal conductivity λ of the test sample 30 is measured using the thermal conductivity measurement method described above, and the measurement results are compared with the thermal conductivity λ recorded in relevant literature, as shown in Table 2.

[0088] Table 2:

[0089]

[0090]

[0091] According to the thermal conductivity λ measured in Table 2 and the thermal conductivity λ recorded in relevant literature, since this measurement method takes into account the heat loss flowing through the micro / nano device 20 and eliminates the influence of contact thermal resistance, the measurement error of the thermal conductivity λ of the sample 30 under test is less than 3%, and the measurement accuracy is higher.

[0092] The thermal conductivity measuring device and method of this application decouple heat flow testing and temperature testing. At the same time, by utilizing the fact that the first thermal resistance of the micro / nano device 20 itself is much greater than the second thermal resistance of the sample 30 under test and the contact thermal resistance between the two, the accuracy of heat flow and temperature measurement through the sample 30 under test can be ensured. Thus, the influence of contact thermal resistance can be eliminated, the measurement accuracy of materials at the micro / nano scale can be improved, and the structure is simple, the cost is low, and it is suitable for mass production.

[0093] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for measuring thermal conductivity, characterized in that, include: The system provides a heat sink, multiple micro / nano devices, and a sample to be tested. The heat sink has a cavity of a preset length, and the micro / nano devices are provided with a contact area and a thermal measurement circuit electrically connected to the contact area. Multiple micro / nano devices are spaced apart on the heat sink along the length of the cavity. One end of the sample to be tested is in contact with the heat sink, and the other end of the sample to be tested is in contact with the contact areas of the multiple micro / nano devices at different positions along its own length. Each micro / nano device has a first thermal resistance, and the sample to be tested has a second thermal resistance. Contact thermal resistances are formed between the sample to be tested and the heat sink, and between the sample to be tested and each contact area. The first thermal resistance is greater than the second thermal resistance, and the first thermal resistance is greater than the contact thermal resistance. A temperature gradient is formed along the length of the sample under test by applying heating power Q to the thermal measurement circuit of the first micro / nano device. The actual contact temperatures T2 and T3 of the contact areas between the sample under test and the adjacent second and third micro / nano devices are obtained. Obtain the actual heat flow power Q0 of the portion of the sample under test corresponding to the portion between the second and third micro / nano devices; Based on the actual heat flux power Q0 and the actual contact temperatures T2 and T3, calculate the thermal conductivity of the sample under test G=Q0 / (T3-T2). Based on the geometric dimensions of the sample to be tested and the thermal conductivity, the thermal conductivity of the sample to be tested is calculated as λ = G × L / S, where L is the length of the sample to be tested and S is the cross-sectional area of ​​the sample to be tested. Wherein, the actual heat flow power Q0 = Q - Q', where Q' is the sum of the heat power lost by the first micro-nano device and the second micro-nano device; The actual contact temperatures between the sample under test and the contact areas of the second and third micro / nano devices are respectively T2 = T2' × (R2' + R0) / R0 and T3 = T3' × (R3' + R0) / R0, where T2' is the temperature measured by the thermal measurement circuit of the second micro / nano device, T3' is the temperature measured by the thermal measurement circuit of the third micro / nano device, R2' is the contact thermal resistance formed by the sample under test and the second micro / nano device, R3' is the contact thermal resistance formed by the sample under test and the third micro / nano device, and R0 is the first thermal resistance.

2. The thermal conductivity measurement method according to claim 1, characterized in that, The ratio of the first thermal resistance to the second thermal resistance is greater than 20, and the ratio of the first thermal resistance to the contact thermal resistance is greater than 20.

3. The thermal conductivity measurement method according to claim 2, characterized in that, The first thermal resistance is greater than 10 6 K / W, the second thermal resistance and the contact thermal resistance are both less than 5×10 4 K / W.

4. The thermal conductivity measurement method according to claim 1, characterized in that, The distance between the second and third micro / nano devices is greater than 10 times the diameter of the outer contour of the cross-section of the sample under test.

5. The method for measuring thermal conductivity according to any one of claims 1 to 4, characterized in that, The actual heat flux power Q0≈Q; and / or, the actual contact temperature T2≈T2' between the sample under test and the contact area of ​​the second micro / nano device, and the actual contact temperature T3≈T3' between the sample under test and the contact area of ​​the third micro / nano device, wherein T2' and T3' are the temperatures measured by the thermal measurement circuits of the second and third micro / nano devices, respectively.

6. The thermal conductivity measurement method according to claim 1, characterized in that, The sum of the heat power lost by the first micro / nano device and the second micro / nano device is Q' = Q1' + Q2', where the heat power lost by the first micro / nano device is Q1', and Q1' = T1' × R0, where T1' is the temperature measured by the thermal measurement circuit of the first micro / nano device; the heat power lost by the second micro / nano device is Q2', and Q2' = T2' × R0.

7. The thermal conductivity measurement method according to claim 1, characterized in that, The contact thermal resistance formed when the sample under test comes into contact with the second micro / nano device is: R2’=( T 2测 -T 1测 ) / Q 2测 , The contact thermal resistance formed when the sample under test comes into contact with the third micro / nano device is: R3’=( T 3测 - T 2测 ) / Q 3测 , Among them, Q 2测 For the test power applied to the second micro / nano device, T 1测 T 2测 The temperatures measured by the thermal measurement circuits of the first and second micro / nano devices at this time are respectively; Q 3测 For the test power applied to the third micro / nano device, T 2测 T 3测 The temperatures measured by the thermal measurement circuits of the second and third micro / nano devices at this time are respectively.

8. The thermal conductivity measurement method according to claim 1, characterized in that, The contact methods between the sample under test and the heat sink, and between the sample under test and the contact areas of each of the micro / nano devices, include direct contact, organic solvent immersion-drying optimized contact, and thermal interface material reinforced contact.

9. A thermal conductivity measuring device, characterized in that, For implementing the thermal conductivity measurement method according to any one of claims 1 to 8, the thermal conductivity measuring device comprises: A heat sink with a cavity of a predetermined length; Multiple micro / nano devices are spaced apart on the heat sink along the length of the cavity. Each micro / nano device has a contact area and a thermal measurement circuit electrically connected to the contact area. One end of the sample to be tested is in contact with the heat sink, and the other end of the sample to be tested is in contact with the contact areas of the multiple micro / nano devices at different positions along its own length. The micro / nano devices have a first thermal resistance, and the sample to be tested has a second thermal resistance. Contact thermal resistances are formed between the sample to be tested and the heat sink, and between the sample to be tested and each contact area. The first thermal resistance is greater than the second thermal resistance, and the first thermal resistance is greater than the contact thermal resistance.

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