A thermal conductivity testing system and method

Abstract

The present invention discloses a test system and method for thermal conductivity. The system includes: a sample to be tested, a sample placement table, a laser source module, an oscilloscope, a current source module and a data processing module; the sample to be tested is placed on the sample placement table and parallel to the laser source module, and the laser source module emits a nanosecond laser to irradiate a preset surface of the sample to be tested; the current source module is electrically connected to the sample to be tested; the oscilloscope is electrically connected to the sample to be tested and the data processing module, and is used to collect resistance change data of the sample to be tested under the irradiation of the laser source module, and transmit it to the data processing module; the data processing module is used to collect and process the resistance change data to obtain the thermal conductivity of the sample to be tested. The relationship between metal conductivity and temperature is used to measure the temperature change of the rear surface of the sample to be tested caused by laser irradiation, thereby measuring the heat transfer capacity of the heat in the normal direction of the sample to be tested, simplifying the measurement operation process, and improving the effect of measurement accuracy.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of semiconductor technology, and in particular to a thermal conductivity testing system and method. Background Art

[0002] With the rapid development of integration and miniaturization of energy systems, such as the large-scale development and application of solar cell devices, battery systems, heaters, etc., thermal management has become one of the important factors affecting the reliability and energy efficiency of materials and devices. With the development of materials, thin film heat dissipation materials, especially micron-scale thin film materials, such as graphene films, copper sheets, etc., have gradually become popular choices. The thermal conductivity of copper is about 400W / (mK), while the thermal conductivity of single-layer graphene can reach up to 5000W / (mK). In recent years, graphene-related materials have attracted widespread attention due to their extremely high thermal conductivity, electrical conductivity and high mechanical strength. Among them, free-standing graphene nanosheets or graphene paper have attracted a large number of researchers to study the thermal transport properties of graphene paper due to their high potential use in thermal management materials. Normal thermal properties are the most important factor for heat-dissipating materials, but it is difficult to measure the normal thermal conductivity of such films.

[0003] At present, the main methods for testing the normal thermal conductivity of thin film materials include the laser flash method and the 3ω method. Representative commercial instruments include the Laser Flash series of test instruments from NETZSCH. Laser Flash uses the laser flash method to quickly and effectively measure the thermal conductivity of materials with a temperature range of -125℃-2800℃ and a thermal conductivity of 0.1W / (mK)-2000W / (mK). However, for samples with a thickness of less than 20μm, this method cannot perform effective and accurate measurements. The 3ω method can measure the thermal conductivity of thinner samples, but it requires the material to be insulated first, and has high requirements for the roughness of the material surface; at the same time, there is also the problem of temperature calibration used in the later characterization, which is cumbersome to operate and has errors. Summary of the invention

[0004] The present invention provides a thermal conductivity testing system and method, which can measure the temperature change of the rear surface of a sample to be tested caused by laser irradiation by utilizing the relationship between metal conductivity and temperature, thereby measuring the heat transfer capacity in the normal direction of the sample to be tested, simplifying the measurement operation process and improving the measurement accuracy.

[0005] In a first aspect, an embodiment of the present invention provides a thermal conductivity testing system, comprising: a sample to be tested, a sample placement table, a laser source module, an oscilloscope, a current source module and a data processing module;

[0006] The sample to be tested is placed on the sample placement table and is parallel to the laser source module, and the laser source module emits nanosecond laser to irradiate a preset surface of the sample to be tested;

[0007] The current source module is electrically connected to the sample to be tested, and is used to provide a direct current to the sample to be tested;

[0008] The oscilloscope is electrically connected to the sample to be tested and the data processing module, and is used to collect resistance change data of the sample to be tested under the irradiation of the laser source module, and transmit the resistance change data to the data processing module;

[0009] The data processing module is used to collect and process the resistance change data to obtain the thermal conductivity of the sample to be tested.

[0010] Optionally, the sample to be tested is formed by sequentially stacking a target film to be tested, a polyester film and a metal coating.

[0011] Optionally, the current source module is connected to two ends of the metal coating through electrodes, and the current source module is used to provide a direct current to the sample to be tested through the metal coating;

[0012] The oscilloscope is connected to the sample to be tested through the metal coating, and is used to collect resistance change data caused by the temperature response of the metal coating after the target film is irradiated by laser, so as to obtain a temperature response curve.

[0013] Optionally, a silicon photodiode is further included, which is connected to the oscilloscope and is used to capture laser pulses from the oscilloscope, and the position of the laser pulse in the time scale is regarded as the start time of thermal relaxation.

[0014] Optionally, the data processing module includes a thermal diffusivity calculation unit and a thermal conductivity calculation unit;

[0015] The thermal diffusivity calculation unit is used to calculate the thermal diffusivity of the target film to be measured according to the control equation of one-dimensional heat transport in the multilayer film;

[0016] The thermal conductivity calculation unit is used to obtain a numerical calculation result based on a one-dimensional heat transfer model, and to obtain the thermal conductivity of the target film to be measured by fitting the numerical calculation result with the temperature response curve.

[0017] Optionally, the system further comprises a vacuum chamber, and the sample placement platform is placed in the vacuum chamber.

[0018] Optionally, a circulating cooling subsystem is also included, and the circulating cooling subsystem is used to provide a stable ambient temperature for the vacuum chamber.

[0019] In a second aspect, an embodiment of the present invention further provides a method for testing thermal conductivity, which is applied to a thermal conductivity testing system as described in any one of the first aspects, comprising:

[0020] Placing a sample to be tested on a sample placement table, and connecting a current source and an oscilloscope, wherein the current source provides a direct current to the sample;

[0021] irradiating a nanosecond laser onto a first preset surface of the sample to be tested through a laser source;

[0022] receiving, by the oscilloscope, resistance change data of a second preset surface of the first preset surface of the sample to be tested caused by the irradiation of the nanosecond laser;

[0023] The resistance change data is collected and processed to obtain the thermal conductivity of the sample to be tested.

[0024] Optionally, before placing the sample to be tested on the sample placement table, the method further includes:

[0025] The target film to be tested, the polyester film and the metal coating are stacked in sequence to form the sample to be tested; the target film to be tested is the first preset surface, and the metal coating is the second preset surface.

[0026] Optionally, collecting and processing the resistance change data to obtain the thermal conductivity of the sample to be tested includes:

[0027] Collecting the resistance change data, and calculating the thermal diffusivity of the target film to be measured according to the governing equation of one-dimensional heat transport in the multilayer film;

[0028] A numerical calculation result is obtained based on a one-dimensional heat transfer model, and the thermal conductivity of the target film to be measured is obtained by fitting the numerical calculation result with the temperature response curve.

[0029] The present invention uses a laser source module to emit nanosecond laser to irradiate a preset surface of a sample to be tested placed on a placement table, a current source module is electrically connected to the sample to be tested and is used to provide a direct current to the sample to be tested, an oscilloscope is electrically connected to the sample to be tested, and resistance change data of the sample to be tested under the irradiation of the laser source module is collected, and the resistance change data is transmitted to a data processing module for processing to obtain the thermal conductivity of the sample to be tested; the problem that measuring the thermal conductivity of a thinner sample requires more complicated operations and has measurement errors is solved, and the temperature change of the rear surface of the sample to be tested caused by laser irradiation is measured by using the relationship between metal conductivity and temperature, thereby measuring the heat transfer capacity of the heat in the normal direction of the sample to be tested, simplifying the measurement operation process and improving the effect of measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1A A schematic diagram of the structure of a thermal conductivity testing system provided in Embodiment 1 of the present invention;

[0031] Figure 1BA schematic diagram of the structure of another thermal conductivity testing system provided in the first embodiment of the present invention;

[0032] Figure 2 A schematic diagram of the structure of a sample to be tested in a thermal conductivity testing system provided in Embodiment 1 of the present invention;

[0033] Figure 3 A schematic flow chart of a method for testing thermal conductivity provided in Embodiment 1 of the present invention. DETAILED DESCRIPTION

[0034] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0035] Embodiment 1

[0036] Figure 1A A schematic diagram of the structure of a thermal conductivity testing system provided in the first embodiment of the present invention is shown in FIG. Figure 1A As shown, a thermal conductivity testing system 1 includes: a sample to be tested 100, a sample placement table 200, a laser source module 300, an oscilloscope 400, a current source module 500 and a data processing module 600;

[0037] The sample 100 to be tested is placed on the sample placement platform 200 and is parallel to the laser source module 300 . The laser source module 300 emits nanosecond laser to irradiate a preset surface of the sample 100 to be tested.

[0038] The current source module 500 is electrically connected to the sample to be tested 100 and is used to provide a direct current to the sample to be tested 100;

[0039] The oscilloscope 400 is electrically connected to the sample 100 and the data processing module 600, and is used to collect resistance change data of the sample 100 under the irradiation of the laser source module 300, and transmit the resistance change data to the data processing module 600;

[0040] The data processing module 600 is used to collect and process the resistance change data to obtain the thermal conductivity of the sample 100 to be tested.

[0041] Among them, Figure 2As shown, the sample to be tested 100 is formed by sequentially stacking a target film 110 to be tested, a polyester film 120 and a metal coating 130. Further, the metal coating 130 is ohmically connected to two electrodes of the current source module 500 only through silver conductive glue to form a conductive loop, and the silver paste is used to enhance the electrical contact and thermal contact between the metal coating and the electrodes.

[0042] The target film 110 used in this embodiment is a partially reduced graphene paper PRGP. Since PRGP is conductive, the target film 110 needs to be insulated first. In this embodiment, a 0.5-micron-thick polyester film 120 is used to separate the target film 110 from the metal coating 130 to meet the requirement that the nano-metal coating 130 is used as a temperature detector.

[0043] The sample 100 to be tested is fixedly placed vertically on the sample placement table 200, the sample 100 to be tested is parallel to and faces the laser source module 300, and is connected to the current source module 500 and the oscilloscope 400. In this embodiment, the preset surface of the target film 110 of the sample 100 to be tested is facing the light source direction for receiving laser irradiation. Specifically, the current source module 500 is connected to the two ends of the metal coating 130 through electrodes, and the current source module 500 is used to provide a direct current to the sample to be tested through the metal coating 130; the oscilloscope 400 is connected to the sample 100 to be tested through the metal coating 130, and the oscilloscope 400 is used to collect resistance change data caused by the temperature response of the metal coating 130 caused by the laser irradiation of the target film 110, and obtain a temperature response curve. When the test starts, the laser source module 300 is started to emit nanosecond laser to irradiate the preset surface of the target film 110 in the sample 100 to be tested. The target film 110 generates heat under the irradiation of the laser, and the heat is conducted to the metal coating 130 through the polyester film 120. The temperature of the metal coating 130 increases, thereby causing the resistance of the metal coating 130 to change. The oscilloscope 400 connected to the metal coating 130 displays the monitored voltage difference across the metal coating 130. Exemplarily, after a single laser pulse irradiates the target film 110, the temperature of the metal coating 130 will increase from the initial experimental temperature to the maximum value, and then return to the initial state as the heat dissipates along the metal coating 130. The oscilloscope 400 receives the resistance change data and generates a waveform diagram of the corresponding change. Among them, as shown in FIG. Figure 1B As shown, the thermal conductivity test system 1 also includes a silicon photodiode 700, which is connected to the oscilloscope 400 and is used to capture laser pulses from the oscilloscope 400. The position of the laser pulse in the time scale is regarded as the start time of thermal relaxation. The photodiode 700 is also connected to the data processing module 600 to send the start time of thermal relaxation to the data processing module 600. Signal capture is crucial in the process of ultrafast thermal relaxation at the microsecond level to accurately obtain the test start time.

[0044] The oscilloscope 400 transmits the resistance change data to the data processing module 600, and the data processing module 600 collects and processes the resistance change data to obtain the thermal conductivity of the sample to be tested 100. A numerical method is used to simulate the one-dimensional heat transfer in the sample to be tested 100 composed of the target film 110, the polyester film 120 and the metal coating 130, and the surface temperature response curve of the metal coating 130 is obtained, and the experimental data is fitted with the curve to obtain the thermal diffusivity and thermal conductivity of the target film 110.

[0045] The data processing module 600 includes a thermal diffusivity calculation unit 610 and a thermal conductivity calculation unit 620; the thermal diffusivity calculation unit 610 is used to calculate the thermal diffusivity of the target film 110 to be measured according to the control equation of one-dimensional heat transport in the multilayer film; the thermal conductivity calculation unit 620 is used to obtain numerical calculation results based on a one-dimensional heat transfer model, and obtain the thermal conductivity of the target film 110 to be measured by fitting the numerical calculation results with the temperature response curve.

[0046] In the embodiment of the present invention, due to the huge difference in the characteristic time or characteristic length of heat transfer in the normal direction and the in-plane direction, the heat can be simplified to one-dimensional transmission in the cross-plane direction and then diffusion in the in-plane direction.

[0047] The governing equation of one-dimensional heat transport in the sample 100 to be tested in the embodiment of the present invention can be expressed as follows:

[0048]

[0049] Wherein, α is the thermal conductivity, T is the temperature, and x is the coordinate of the heat transfer direction. In the embodiment of the present invention, the thickness of the high thermal conductivity nano-metal coating can be ignored relative to the single-layer film with a thickness of micrometers. The control equation in the embodiment of the present invention can be solved by using the Green's function. When x=L, and the temperature change of the metal coating 130 on the rear surface of the sample 100 to be tested is normalized from the initial temperature to the maximum temperature as follows:

[0050]

[0051] In the embodiment of the present invention, within a small temperature range, the resistance of the metal coating 130 is linearly proportional to its temperature, that is:

[0052] R=(ρ0+γ·ΔT)×(l / A c )

[0053] where ρ0 is the initial resistivity at the experimental temperature, γ is the local temperature coefficient of resistivity, ΔT is the temperature rise, l is the sample length, and A c is the cross-sectional area of ​​the metal coating.

[0054] According to the principle of the embodiment of the present invention, R is normalized from the initial value before the laser pulse (R0) to the maximum value after the laser pulse (R m ), there are:

[0055]

[0056] According to the principles and measurements of the embodiments of the present invention, thermal conductivity can be calculated by given material density and specific heat, as shown in the following formula:

[0057] k=α·ρ·c p

[0058] The temperature response of the metal coating 130 on the back of the sample 100 can be directly detected by the oscilloscope 400 through the voltage change caused by the resistance change, and the thermal diffusivity of the single-layer sample target film 110 can be calculated by α=(1.37L 2 / π 2 t 1 / 2 ) directly.

[0059] In the numerical simulation process, the thickness and heat capacity of each layer of the target film 110, the polyester film 120 and the metal coating 130 are key parameters. The parameters of the polyester film 120 and the metal coating 130 are known and obtained before the test. The interlayer interface thermal resistance of each layer is at least two orders of magnitude smaller than the thermal resistance of the material itself, and can be ignored in the test method of this embodiment.

[0060] The present invention uses a laser source module to emit nanosecond laser to irradiate a preset surface of a sample to be tested placed on a placement table, a current source module is electrically connected to the sample to be tested and is used to provide a direct current to the sample to be tested, an oscilloscope is electrically connected to the sample to be tested, and resistance change data of the sample to be tested under the irradiation of the laser source module is collected, and the resistance change data is transmitted to a data processing module for processing to obtain the thermal conductivity of the sample to be tested; the problem that measuring the thermal conductivity of a thinner sample to be tested requires more complicated operations and has measurement errors is solved, and the temperature change of the rear surface of the sample to be tested caused by laser irradiation is measured by using the relationship between metal conductivity and temperature, thereby measuring the heat transfer capacity of the heat in the normal direction of the sample to be tested, simplifying the measurement operation process and improving the effect of measurement accuracy.

[0061] Based on the above technical solution, Figure 1B As shown, further, the thermal conductivity testing system 1 also includes a vacuum chamber 800 , and the sample placement table 200 is placed in the vacuum chamber 800 .

[0062] Furthermore, the thermal conductivity testing system 1 also includes a circulating cooling subsystem 2 , and the circulating cooling subsystem 2 is used to provide a stable ambient temperature for the vacuum chamber 800 .

[0063] The vacuum chamber 800 in the embodiment of the present invention can reduce the heat dissipated by thermal convection after the laser irradiates and heats the surface of the target film 110, thereby reducing errors. The closed-loop cooling subsystem 2 is used to ensure that the sample is at a constant temperature during the measurement process, and at the same time, the influence of the ambient temperature stability on the measurement accuracy can be reduced, so that effective measurement of thermal conductivity at extremely low temperatures can be achieved.

[0064] Furthermore, the original laser spot size emitted by the laser source module 300 is about 3 to 5 cm, which is much larger than the lateral size of the sample to be tested 100. Therefore, it can be safely assumed that the laser energy distribution on the preset surface of the sample to be tested is uniform, and the laser is adjusted by the aperture on the optical path of the laser irradiating the sample to be tested 100, which can ensure that the laser irradiates only the preset surface of the sample to be tested, and reduce the interference of laser heating on the electrodes and wiring to a negligible level.

[0065] Embodiment 2

[0066] Figure 3 The present invention provides a flow chart of a method for testing thermal conductivity provided in the first embodiment of the present invention. This embodiment is applicable to the case of testing the normal thermal conductivity of a target film with a thickness of micrometers. The method can be performed by a thermal conductivity testing system, such as Figure 3 As shown, the specific steps include:

[0067] Step 210: Place the sample to be tested on a sample placement table, and connect a current source and an oscilloscope, wherein the current source provides a direct current to the sample.

[0068] Among them, since the target film is conductive, the target film needs to be insulated first. Therefore, before placing the sample to be tested on the sample placement table, the target film to be tested, the polyester film and the metal coating are stacked in sequence to form the sample to be tested; the target film to be tested is the first preset surface, and the metal coating is the second preset surface. Further, the metal coating is ohmically connected to the two electrodes of the current source module only through silver conductive glue to form a conductive loop, and the silver paste is used to enhance the electrical contact and thermal contact between the metal coating and the electrodes.

[0069] The sample to be tested is fixed and placed vertically on the sample placement table, the sample to be tested is parallel to the laser source module, and is connected to the current source module and the oscilloscope. Specifically, the current source module is connected to the two ends of the metal coating through electrodes, and the current source module is used to provide a direct current to the sample to be tested through the metal coating; the oscilloscope is connected to the sample to be tested through the metal coating, and the oscilloscope is used to collect resistance change data caused by the temperature response of the metal coating caused by the target film being irradiated by the laser, and obtain a temperature response curve.

[0070] Step 220: irradiate a nanosecond laser onto a first preset surface of the sample to be tested through a laser source.

[0071] When the test starts, the laser source module is started to emit nanosecond laser to irradiate the preset surface of the target film in the sample to be tested. The target film generates heat under the irradiation of the laser, and the heat is conducted to the metal coating through the polyester film.

[0072] Furthermore, the method further includes: connecting a silicon photodiode to an oscilloscope, capturing laser pulses from the oscilloscope, and the position of the laser pulse in the time scale is regarded as the start time of thermal relaxation. The photodiode is also connected to a data processing module, and the start time of thermal relaxation is sent to the data processing module. Signal capture in the microsecond ultrafast thermal relaxation process is crucial to accurately obtain the start time of the test.

[0073] Step 230: Receive, through the oscilloscope, resistance change data of a second preset surface of the sample to be tested caused by the first preset surface under the irradiation of the nanosecond laser.

[0074] After a single laser pulse irradiates the target film, the temperature of the metal coating will rise from the initial experimental temperature to the maximum value, and then return to the initial state as the heat dissipates along the metal coating. The increase in the temperature of the metal coating causes the resistance of the metal coating to change. The oscilloscope connected to the metal coating displays the voltage difference across the monitored metal coating. The oscilloscope receives the resistance change data and generates a waveform graph of the corresponding change.

[0075] Step 240: Collect and process the resistance change data to obtain the thermal conductivity of the sample to be tested.

[0076] A numerical method is used to simulate one-dimensional heat transfer in a test sample 100 composed of a target film, a polyester film and a metal coating, and a surface temperature response curve of the metal coating is obtained. The thermal diffusivity and thermal conductivity of the target film are obtained by fitting the experimental data with the curve.

[0077] Wherein, step 240 specifically includes:

[0078] Step 241: collect the resistance change data, and calculate the thermal diffusivity of the target film to be measured according to the control equation of one-dimensional heat transport in the multilayer film.

[0079] Step 242: obtaining numerical calculation results based on a one-dimensional heat transfer model, and obtaining the thermal conductivity of the target film to be measured by fitting the numerical calculation results with the temperature response curve.

[0080] In the embodiment of the present invention, due to the huge difference in the characteristic time or characteristic length of heat transfer in the normal direction and the in-plane direction, the heat can be simplified to one-dimensional transmission in the cross-plane direction and then diffusion in the in-plane direction.

[0081] The governing equation for one-dimensional heat transport in the sample to be tested in the embodiment of the present invention can be expressed as follows:

[0082]

[0083] In the embodiment of the present invention, the thickness of the high thermal conductivity nano-metal coating can be ignored relative to the single-layer film with a thickness of micrometers. The control equation in the embodiment of the present invention can be solved by using the Green's function. When x=L, and the temperature change of the metal coating on the rear surface of the sample to be tested is normalized from the initial temperature to the maximum temperature as follows:

[0084]

[0085] In the embodiment of the present invention, within a small temperature range, the resistance of the metal coating is linearly proportional to its temperature, that is:

[0086] R=(ρ0+γ·ΔT)×(l / A c )

[0087] where ρ0 is the initial resistivity at the experimental temperature, γ is the local temperature coefficient of resistivity, ΔT is the temperature rise, l is the sample length, and A c is the cross-sectional area of ​​the metal coating.

[0088] According to the principle of the embodiment of the present invention, R is normalized from the initial value before the laser pulse (R0) to the maximum value after the laser pulse (R m ), there are:

[0089]

[0090] According to the principles and measurements of the embodiments of the present invention, thermal conductivity can be calculated by given material density and specific heat, as shown in the following formula:

[0091] k=α·ρ·c p

[0092] The temperature response of the metal coating on the back of the sample to be tested can be directly detected by an oscilloscope through the voltage change caused by the resistance change, and the thermal diffusivity of the single-layer sample target film can be obtained by α = (1.37L 2 / π 2 t 1 / 2 ) directly.

[0093] Among them, in the numerical simulation process, the thickness and heat capacity of each layer of the target film, polyester film and metal coating are key parameters, and the known parameters of the polyester film and metal coating are obtained before the test. The interlayer interface thermal resistance of each layer is at least two orders of magnitude smaller than the thermal resistance of the material itself, which can be ignored in the test method of this embodiment.

[0094] The present invention uses a laser source module to emit nanosecond laser to irradiate a preset surface of a sample to be tested placed on a placement table, a current source module is electrically connected to the sample to be tested and is used to provide a direct current to the sample to be tested, an oscilloscope is electrically connected to the sample to be tested, and resistance change data of the sample to be tested under the irradiation of the laser source module is collected, and the resistance change data is transmitted to a data processing module for processing to obtain the thermal conductivity of the sample to be tested; the problem that measuring the thermal conductivity of a thinner sample to be tested requires more complicated operations and has measurement errors is solved, and the temperature change of the rear surface of the sample to be tested caused by laser irradiation is measured by using the relationship between metal conductivity and temperature, thereby measuring the heat transfer capacity of the heat in the normal direction of the sample to be tested, simplifying the measurement operation process and improving the effect of measurement accuracy.

[0095] On the basis of the above technical solution, the method also includes placing a sample placement table in a vacuum chamber and using a circulating cooling subsystem to provide a stable ambient temperature for the vacuum chamber.

[0096] The vacuum chamber used in the embodiment of the present invention can reduce the heat dissipated by thermal convection after the laser irradiates and heats the target film surface, thereby reducing errors. The closed-loop cooling subsystem is used to ensure that the sample is at a constant temperature during the measurement process, and the influence of the ambient temperature stability on the measurement accuracy can also be reduced, so that effective measurement of thermal conductivity at extremely low temperatures can be achieved.

[0097] Furthermore, the original laser spot size emitted by the laser source module is about 3 to 5 cm, which is much larger than the lateral size of the sample to be tested. To ensure that the laser energy distribution on the first preset surface is uniform, the laser can be adjusted through the aperture to ensure that the laser only irradiates the preset surface of the sample to be tested, reducing the interference of laser heating on the electrodes and wiring to a negligible level.

[0098] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A thermal conductivity testing system, characterized in that: include: A sample to be tested, a sample placement table, a laser source module, an oscilloscope, a current source module and a data processing module; The sample to be tested is placed on the sample placement table and is parallel to the laser source module, and the laser source module emits nanosecond laser to irradiate a preset surface of the sample to be tested; The current source module is electrically connected to the sample to be tested, and is used to provide a direct current to the sample to be tested; The oscilloscope is electrically connected to the sample to be tested and the data processing module, and is used to collect resistance change data of the sample to be tested under the irradiation of the laser source module, and transmit the resistance change data to the data processing module; The data processing module is used to collect and process the resistance change data to obtain the thermal conductivity of the sample to be tested; The sample to be tested is formed by sequentially stacking a target film to be tested, a polyester film and a metal coating; The preset surface of the target film to be tested of the sample to be tested faces the light source direction for receiving the nanosecond laser irradiation; the oscilloscope is used to collect resistance change data caused by the temperature response of the metal coating after the target film to be tested is irradiated by the nanosecond laser.

2. The thermal conductivity testing system according to claim 1, characterized in that: The current source module is connected to two ends of the metal coating through electrodes, and the current source module is used to provide a direct current to the sample to be tested through the metal coating; The oscilloscope is connected to the sample to be tested through the metal coating, and is used to collect resistance change data caused by the temperature response of the metal coating after the target film is irradiated by laser, so as to obtain a temperature response curve.

3. The thermal conductivity testing system according to claim 1, characterized in that: A silicon photodiode is also included, and the silicon photodiode is connected to the oscilloscope and is used to capture the laser pulse from the oscilloscope, and the position of the laser pulse in the time scale is regarded as the start time of thermal relaxation.

4. The thermal conductivity testing system according to claim 2, characterized in that: The data processing module includes a thermal diffusivity calculation unit and a thermal conductivity calculation unit; The thermal diffusivity calculation unit is used to calculate the thermal diffusivity of the target film to be measured according to the control equation of one-dimensional heat transport in the multilayer film; The thermal conductivity calculation unit is used to obtain a numerical calculation result based on a one-dimensional heat transfer model, and to obtain the thermal conductivity of the target film to be measured by fitting the numerical calculation result with the temperature response curve.

5. The thermal conductivity testing system according to claim 1, characterized in that: The system also includes a vacuum chamber, and the sample placement platform is placed in the vacuum chamber.

6. The thermal conductivity testing system according to claim 5, characterized in that: A circulating cooling subsystem is also included, and the circulating cooling subsystem is used to provide a stable ambient temperature for the vacuum chamber.

7. A method for testing thermal conductivity, the method being applied to the thermal conductivity testing system as claimed in any one of claims 1 to 6, characterized in that: include: Placing a sample to be tested on a sample placement table, and connecting a current source and an oscilloscope, wherein the current source provides a direct current to the sample; irradiating a nanosecond laser onto a first preset surface of the sample to be tested through a laser source; receiving, by the oscilloscope, resistance change data of a second preset surface of the first preset surface of the sample to be tested caused by the irradiation of the nanosecond laser; The resistance change data is collected and processed to obtain the thermal conductivity of the sample to be tested.

8. The method for testing thermal conductivity according to claim 7, characterized in that: Before placing the sample to be tested on the sample placement table, the method also includes: The target film to be tested, the polyester film and the metal coating are stacked in sequence to form the sample to be tested; the target film to be tested is the first preset surface, and the metal coating is the second preset surface.

9. The method for testing thermal conductivity according to claim 7, characterized in that: The collecting and processing the resistance change data to obtain the thermal conductivity of the sample to be tested includes: Collecting the resistance change data, and calculating the thermal diffusivity of the target film to be measured according to the governing equation of one-dimensional heat transport in the multilayer film; A numerical calculation result is obtained based on a one-dimensional heat transfer model, and the thermal conductivity of the target film to be measured is obtained by fitting the numerical calculation result with a temperature response curve.

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