Device and method for measuring thermal conductivity of thin film material by steady-state method

Abstract

The invention belongs to the technical field of heat conduction and heat dissipation material testing, and particularly relates to a device and method for measuring the heat conductivity of a thin film material through a steady-state method. The device comprises a power chip, a constant temperature water tank, a pressure regulating water pump, a heat insulation water pipe, a connecting piece, a water cooling head, a locking screw, a copper bar heat flow meter, a heat sensor, a temperature transmitter, a data communication line, a data processing mainboard, a data output display calculator and the like. The device is stable in structure, easy to operate, safe, efficient and capable of conveniently and stably measuring the thermal conductivity of the thin-film material. And the heat conductivity test requirements of products such as heat-conducting films can be well met.

Description

Technical Field

[0001] This invention belongs to the field of thermal conductivity and heat dissipation material testing technology, specifically relating to an apparatus and method for determining the thermal conductivity of thin film materials using a steady-state method. Background Technology

[0002] The steady-state method is one of the classic methods for determining the thermal conductivity of thin film materials. Its core principle is to establish a stable temperature gradient within the material and calculate the thermal conductivity by measuring heat flow and temperature difference. A common method is the heat flow meter method, which involves sandwiching the thin film sample between two reference plates with known thermal conductivity, applying a constant heat flow, and measuring the temperature difference across the sample. This method is suitable for films with medium thermal conductivity (0.1~100 W / m·K), such as polymer and ceramic films, but it is less suitable for high thermal conductivity materials like graphene. Another method is the guarded hot plate method (GHP). This method eliminates lateral heat loss through a main heating plate and a guarded hot plate, ensuring one-dimensional heat flow, and measuring the temperature difference and heat flow in the central region. The advantage of this method is high accuracy (error <3%), making it suitable for low thermal conductivity materials (such as insulating films), but it is also less suitable for high thermal conductivity materials like graphene. Another method is the Longitudinal Heat Flow Method, which involves connecting a heat source and a heat sink to opposite ends of the thin film sample and measuring the axial temperature distribution using thermocouples. This method requires minimizing contact thermal resistance and is suitable for high thermal conductivity films (such as metals and graphene), but it is not suitable for thick films. Finally, there is the 3ω method (an improved steady-state method): a metal electrode is deposited on the thin film surface, and an alternating current is applied to generate a periodic heat flow. The thermal conductivity is then inferred from the voltage signal (3ω component). While this method can measure ultrathin films (nanoscale), it requires complex signal processing.

[0003] One particular challenge in thin-film measurement is the contact thermal resistance issue; another is avoiding substrate interference and ensuring proper insulation of both the top and bottom layers; and finally, ensuring the accuracy of thick-film measurements. Since heat dissipation is a systems engineering process, the process of heat dissipation from the heat source chip to the environment typically requires a heat transfer path composed of multiple materials, making it difficult to intuitively evaluate the actual heat dissipation performance of materials.

[0004] Currently, many projects require a method to replace imported equipment, especially in major national projects that require the use of domestically produced alternatives to testing methods or equipment. Therefore, it is essential to develop a rapid, non-destructive, and accurate device for testing the thermal conductivity of thin film materials. Summary of the Invention

[0005] This invention addresses the core problems of existing steady-state methods for determining the thermal conductivity of thin film materials, such as high equipment cost, poor applicability to high thermal conductivity films (such as graphene), and susceptibility to contact thermal resistance / substrate interference affecting accuracy. Based on the core idea of ​​"constructing a controllable steady-state heat flow system using mature commercial components, and achieving high-precision non-destructive testing through precise temperature control and heat flow measurement", this invention proposes a device and method for determining the thermal conductivity of thin film materials using a steady-state method.

[0006] The technical solution of this invention is: An apparatus for determining the thermal conductivity of thin film materials using a steady-state method, the apparatus comprising: Power chips are used as a constant heat source to provide a stable heat flow. A constant temperature water tank is used to provide coolant at a constant temperature and control the cooling temperature. A pressure regulating water pump is used to regulate the flow rate of coolant. Insulated water pipes and fittings are used to connect the constant temperature water tank, pressure regulating water pump and water cooling head to ensure the insulation of the coolant during circulation. The water cooling head and locking screws are used to contact the film under test and transfer coolant to remove heat. Two copper busbar heat flux meters are configured, one connected to the heat source end and the other to the cold source end, for measuring heat flux. The thermal sensors are set to eight, with six thermal sensors connected in groups of three to the copper busbar heat flux meters at the CPU end and the water-cooling end respectively, and the other two thermal sensors connected to the thin film under test to measure the temperature at various locations. The temperature transmitter is configured with eight channels, each corresponding to one of the eight thermal sensors, for acquiring temperature signals. Data communication lines are used to transmit data collected by temperature sensors. The data processing motherboard is used to process temperature data and calculate thermal conductivity according to Fourier's law; The data output display calculator is used to display calculation results, wherein the power chip, data processing motherboard and data output display calculator can be integrated and configured.

[0007] Furthermore, in the aforementioned steady-state method for determining the thermal conductivity of thin film materials, the power chip is a 100-500W CPU or GPU chip, and it is equipped with a matching motherboard, memory, hard disk, and power display screen to form a data output display calculator.

[0008] Furthermore, in the aforementioned steady-state method for determining the thermal conductivity of thin film materials, the constant temperature water tank has a temperature control range of 0~100℃, a temperature control accuracy of 1℃, supports internal or external circulation modes, and the pump flow rate can be adjusted from 3~10L / min by a pressure regulating water pump.

[0009] Furthermore, in the aforementioned steady-state method for determining the thermal conductivity of thin film materials, the six thermal sensors are grouped into threes and uniformly connected to the copper busbar heat flux meters at the CPU end and the water-cooling end, respectively. The spacing L between each group of thermal sensors is 10~25mm, preferably 25mm. The two thermal sensors are connected to the thin film to be tested, and the spacing X between them is 20~60mm, preferably 60mm.

[0010] Furthermore, in the aforementioned steady-state method for determining the thermal conductivity of thin film materials, the two thermal sensors connected to the thin film under test are tightly bonded together by a thermal interface material, wherein the thermal interface material is selected from at least one of thermally conductive silicone grease, graphene thermally conductive adhesive film, or thermally conductive gel.

[0011] Furthermore, in the aforementioned steady-state method for determining the thermal conductivity of thin film materials, the eight-channel temperature transmitter is connected to eight thermal sensors via a communication interface to acquire the temperature signals of each sensor in real time.

[0012] Furthermore, in the aforementioned steady-state method for determining the thermal conductivity of thin film materials, the water-cooling head is made of copper, and its specific dimensions are customized according to the dimensions of the thin film to be tested. It is connected to an insulated hot water pipe through fittings, and deionized water is injected inside as the coolant.

[0013] Furthermore, in the aforementioned steady-state method for determining the thermal conductivity of thin film materials, the device uses software to control the operating power of the power chip as a constant heat source, while simultaneously maintaining the coolant temperature at 30°C in a constant-temperature water tank to achieve stable cooling.

[0014] The present invention also discloses a method for measuring the thermal conductivity of thin film materials using the above-described apparatus, comprising the following steps: The power chip is used as a heat source, and its operating power is controlled by software to form a stable heat flow on the thin film under test. The temperature and flow rate of the coolant are regulated by a constant temperature water tank and a pressure regulating water pump to keep the water cooling head at a constant low temperature to create a temperature gradient. The temperature distribution at the heat source end, cold source end, and on the thin film under test is measured using a copper busbar heat flux meter and a thermal sensor. Based on Fourier's law, the heat flow through the thin film under test is calculated by using the temperature difference and geometric parameters of the copper busbar heat flow meter at the heat source end and the cold source end. The thermal conductivity of the thin film material is calculated based on the temperature difference and heat flow at both ends of the thin film.

[0015] Furthermore, in the above method, the film to be tested is a thermally conductive film material with a thickness range of 0.001~10mm, including but not limited to graphene film, and the contact thermal resistance between the thermal sensor and the film is reduced by using a thermal interface material.

[0016] The design concept of this invention is: High-power electronic devices, such as conventional computer CPUs or GPUs, can serve as stable, constant-power heat sources for testing equipment. Currently, the operating power of mainstream computer CPUs and GPUs exceeds 300 W and 500 W respectively, with peak heat dissipation power densities reaching over 100 W / cm². By utilizing the built-in thermal sensors and related software, information such as chip operating temperature and floating-point operation speed can be read and recorded in real time, making it an ideal platform for thermal conductivity and heat dissipation simulation and verification.

[0017] To rapidly and non-destructively determine the in-plane thermal conductivity of thick thermally conductive films, a testing mechanism for determining the thermal conductivity of strip-shaped film samples using the constant heat flow method was constructed. Based on a constant power heat source and a constant temperature cold source, a controllable temperature gradient and detectable heat transfer power are formed. Then, based on Fourier's law, the thermal conductivity index of the film is determined, achieving rapid and non-destructive measurement.

[0018] The beneficial effects of this invention are as follows: (1) This device avoids physical damage to the membrane material caused by the testing equipment.

[0019] (2) The device uses a constant power heat source and a constant temperature cold source to form a controllable temperature gradient and detectable heat transfer power, and then determines the thermal conductivity of the membrane based on Fourier's law.

[0020] (3) Mature commercial components are built according to the principle scheme, and the cost of testing equipment is relatively low.

[0021] (4) This method can be used to test thicker thin film materials, with the thickness of the test film ranging from 0.001 to 10 mm. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the present invention; In the diagram, 1-Data output display calculator; 2-Data processing motherboard; 3-Copper busbar heat flow meter; 4-Data communication line; 5-Thermal sensor; 6-Temperature transmitter; 7-Power chip; 8-Water cooling head; 9-Constant temperature water tank; 10-Pressure regulating water pump; 11-Insulated water pipe. Detailed Implementation

[0023] like Figure 1 As shown in the specific embodiment, the present invention provides an apparatus for determining the thermal conductivity of thin film materials using a steady-state method, the apparatus comprising: Power chip 7 is used as a constant heat source to provide a stable heat flow; Thermostatic water tank 9 is used to provide coolant at a constant temperature and control the cooling temperature; Pressure regulating water pump 10 is used to regulate the flow rate of coolant; Insulated water pipe 11 and connectors are used to connect the constant temperature water tank 9, the pressure regulating water pump 10 and the water cooling head 8 to ensure the insulation of the coolant during circulation. The water cooling head 8 and locking screws are used to contact the film under test and transfer coolant to remove heat. Two copper busbar heat flux meters 3 are configured, connected to the heat source end and the cold source end respectively, for measuring heat flux; Thermal sensors 5 are configured as eight, with six thermal sensors connected in groups of three to the copper busbar heat flux meter 3 at the CPU end and the water-cooling end respectively, and the other two thermal sensors connected to the thin film under test to measure the temperature at each location. Temperature transmitter 6 is configured with eight channels, each corresponding to one of the eight thermal sensors 5, for acquiring temperature signals; Data communication line 4 is used to transmit data collected by the temperature sensor; Data processing motherboard 2 is used to process temperature data and calculate thermal conductivity according to Fourier's law; The data output display calculator 1 is used to display calculation results, wherein the power chip 7, the data processing motherboard 2 and the data output display calculator 1 can be integrated and configured.

[0024] The specific embodiments of the present invention will be described in detail below with reference to the above-described apparatus.

[0025] Example 1

[0026] In this embodiment, the device consists of a 200W CPU power chip, a constant temperature water tank maintained at 20℃ (temperature accuracy 1℃), a pressure regulating water pump, and external circulation via insulated water pipes and connectors with thermal wrapping to cool a copper water cooling head, with the pump flow rate controlled at 8 L / min. The thin film to be tested is a 100μm graphene film. Two thermal sensors are attached to the thin film, with a spacing of X=60mm. The two thermal sensors on the graphene film are tightly bonded together using a thermal interface material. The thermal interface material used is Shin-Etsu 7921 thermally conductive silicone grease.

[0027] Two copper busbar heat flux meters and eight thermal sensors (resistance temperature detectors or thermocouples). The six thermal sensors are grouped into threes and connected to the copper busbar heat flux meters at the CPU end and the water-cooling end, respectively, with a distance L = 25 mm between each one; The CPU's operating power is controlled by software as a heat source, and a constant-temperature water tank maintains the water temperature at 30°C for cooling. The thermal conductivity of copper is K. Cu =391.5 W m −1 K −1 According to Fourier's heat transfer law, the heat flow (Qh) flowing through the hot-end copper busbar and the heat flow (Qc) flowing through the cold-end copper busbar are respectively...

[0028] Where S Cu It is the cross-sectional area of ​​the copper busbar, therefore the heat flow (Q) through the graphene film Gra ) can be calculated as Therefore, according to Fourier's law of heat transfer, the thermal conductivity (K2) of graphene can be obtained. Gra )for

[0029] Where S Gra It is the cross-sectional area of ​​the graphene film.

[0030] The thermal conductivity of the graphene thermal conductive film tested using the non-destructive testing system in this example was 1521 W / m². −1 K −1 The result compared to the laser scintillation method (Laminate mode) is 1545 W / m. −1 K −1 The data is very close, proving that the data error between this device and nearly a million imported testing devices is very small.

[0031] Example 2

[0032] In this embodiment, the device consists of a 300W CPU power chip, a constant temperature water tank maintained at 20℃ (temperature accuracy 1℃), a pressure regulating water pump, and external circulation via insulated water pipes and connectors to cool a copper water cooling head, with the pump flow rate controlled at 10 L / min. The thin film to be tested is a 200μm graphene film. Two thermal sensors are attached to the thin film, with a spacing of X=60mm. The two thermal sensors on the graphene film are tightly bonded together using a thermal interface material. The thermal interface material used is Shin-Etsu 7921 thermally conductive silicone grease.

[0033] Two copper busbar heat flux meters and eight thermal sensors (resistance temperature detectors or thermocouples). The six thermal sensors are grouped into threes and connected to the copper busbar heat flux meters at the CPU end and the water-cooling end, respectively, with a distance L = 25 mm between each one; The CPU's operating power is controlled by software as a heat source, and a constant-temperature water tank maintains the water temperature at 30°C for cooling. The thermal conductivity of copper is K. Cu =391.5 W m −1 K −1 According to Fourier's heat transfer law, the heat flow (Qh) flowing through the hot-end copper busbar and the heat flow (Qc) flowing through the cold-end copper busbar are respectively...

[0034] Where S Cu It is the cross-sectional area of ​​the copper busbar, therefore the heat flow (Q) through the graphene film Gra ) can be calculated as Therefore, according to Fourier's law of heat transfer, the thermal conductivity (K2) of graphene can be obtained. Gra)for

[0035] Where S Gra It is the cross-sectional area of ​​the graphene film.

[0036] The thermal conductivity of the graphene thermal conductive film tested using the non-destructive testing system in this example was 1421 W / m². −1 K −1 The result of the laser scintillation method (Laminate mode) is 1435 W / m. −1 K −1 The results are very close, proving that the principle of the device is correct and the test results are reliable.

[0037] The above examples describe the specific operation and device structure features of the present invention. It should be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations that may be made to the above embodiments by those skilled in the art within the scope of the present invention shall fall within the scope of the present invention.

Claims

1. An apparatus for determining the thermal conductivity of thin film materials using a steady-state method, characterized in that, The device includes: Power chips are used as constant heat sources to provide a stable heat flow. A constant temperature water tank is used to provide coolant at a constant temperature and control the cooling temperature. A pressure regulating water pump is used to regulate the flow rate of coolant. Insulated water pipes and fittings are used to connect the constant temperature water tank, pressure regulating water pump and water cooling head to ensure the insulation of the coolant during circulation. The water cooling head and locking screws are used to contact the film under test and transfer coolant to remove heat. Two copper busbar heat flux meters are configured, one connected to the heat source end and the other to the cold source end, for measuring heat flux; The thermal sensors are set to eight, with six thermal sensors connected in groups of three to the copper busbar heat flux meters at the CPU end and the water-cooling end respectively, and the other two thermal sensors connected to the thin film under test to measure the temperature at various locations. The temperature transmitter is configured with eight channels, each corresponding to one of the eight thermal sensors, for acquiring temperature signals. Data communication lines are used to transmit data collected by temperature sensors. The data processing motherboard is used to process temperature data and calculate thermal conductivity according to Fourier's law; The data output display calculator is used to display calculation results, wherein the power chip, data processing motherboard and data output display calculator can be integrated and configured.

2. The apparatus for determining the thermal conductivity of thin film materials using a steady-state method according to claim 1, characterized in that, The power chip is a 100~500W CPU or GPU chip, and is paired with a matching motherboard, memory, hard drive and power display screen to form a data output display calculator.

3. The apparatus for determining the thermal conductivity of thin film materials using a steady-state method according to claim 1, characterized in that, The temperature control range of the constant temperature water tank is 0~100℃, the temperature control accuracy is 1℃, it supports internal circulation or external circulation mode, and the pump flow rate can be adjusted from 3~10L / min by a pressure regulating water pump.

4. The apparatus for determining the thermal conductivity of thin film materials using a steady-state method according to claim 1, characterized in that, The six thermal sensors are grouped into threes and are evenly connected to the copper busbar heat flux meters at the CPU end and the water-cooling end, respectively. The spacing L between each group of thermal sensors is 10~25mm. The two thermal sensors are connected to the film to be tested, and the spacing X between them is 20~60mm.

5. The apparatus for determining the thermal conductivity of thin film materials using a steady-state method according to claim 4, characterized in that, The two thermal sensors connected to the film under test are tightly bonded together by a thermal interface material, which is selected from at least one of thermally conductive silicone grease, graphene thermally conductive adhesive film, or thermally conductive gel.

6. The apparatus for determining the thermal conductivity of thin film materials using a steady-state method according to claim 1, characterized in that, The eight-channel temperature transmitter is connected to eight thermal sensors via a communication interface to collect temperature signals from each sensor in real time.

7. The apparatus for determining the thermal conductivity of thin film materials using a steady-state method according to claim 1, characterized in that, The water cooling head is made of copper, and its specific dimensions are customized according to the size of the film to be tested. It is connected to an insulated hot water pipe through fittings, and deionized water is injected inside as the coolant.

8. The apparatus for determining the thermal conductivity of thin film materials using a steady-state method according to claim 1, characterized in that, The device uses software to control the operating power of the power chip as a constant heat source, while maintaining the coolant temperature at 30°C through a constant temperature water tank to achieve stable cooling.

9. A method for determining the thermal conductivity of a thin film material using the apparatus according to any one of claims 1-8, characterized in that, Includes the following steps: The power chip is used as a heat source, and its operating power is controlled by software to form a stable heat flow on the thin film under test. The temperature and flow rate of the coolant are regulated by a constant temperature water tank and a pressure regulating water pump to keep the water cooling head at a constant low temperature to create a temperature gradient. The temperature distribution at the heat source end, cold source end, and on the thin film under test is measured using a copper busbar heat flux meter and a thermal sensor. Based on Fourier's law, the heat flow through the thin film under test is calculated by using the temperature difference and geometric parameters of the copper busbar heat flow meter at the heat source end and the cold source end. The thermal conductivity of the thin film material is calculated based on the temperature difference and heat flow at both ends of the thin film.

10. The method according to claim 9, characterized in that, The film to be tested is a thermally conductive film material with a thickness range of 0.001~10mm, including but not limited to graphene film, and the contact thermal resistance between the thermal sensor and the film is reduced by the thermal interface material.

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