High-resolution thermophysical property detection method and equipment for polymer composite thermal interface material

Abstract

The invention belongs to the technical field of thermophysical property characterization methods and equipment, and particularly relates to a high-resolution thermophysical property detection method and equipment for a polymer composite thermal interface material. The method comprises the following steps: (1) depositing a gold film on the surface of a silicon dioxide substrate by using an electron beam evaporation or magnetron sputtering method, and calibrating thermophysical parameters of the gold film by using a frequency domain heat reflection system to obtain the thermophysical parameters of the gold film; (2) uniformly smearing a polymer composite thermal interface material to be detected on the gold film, covering the polymer composite thermal interface material by using a thin copper plate, and then fixing and clamping by using a clamp; (3) extracting a heat reflection signal image by using a frequency domain heat reflection system; and (4) adjusting initial parameters of the heat transfer model to obtain a theoretical signal, and performing optimal fitting on a measurement result to obtain a distribution diagram of heat conductivity and interface heat conductivity. The technical problem of micron-scale thermophysical property imaging of the composite thermal interface material is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of thermal property characterization methods and equipment, and specifically relates to a high-resolution thermal property detection method and equipment for a polymer composite thermal interface material. Background Art

[0002] With the increase in power density and integration of electronic products, the demand for thermal management solutions has increased significantly. Thermal interface materials (TIMs) are often used in electronic products as a tool to dissipate heat from heat sources in the first stage. The evaluation of the working performance of TIMs, especially the heat transfer characteristics, is crucial for the practical development and application of TIMs.

[0003] Thermal interface materials are often used as a bridge between heat sources and heat dissipation components in actual use. The interface thermal resistance of thermal interface materials consists of three parts, which can be expressed as:

[0004] R=R c1 +R TIM +R c2

[0005] Where R c1 and R c2 are the thermal contact resistances of the thermal interface material and the upper and lower surfaces, is the equivalent thermal resistance of the thermal interface material as a whole, BLT is the thickness of the bonding layer, i.e. the thickness of the thermal interface material, κ TIM is the thermal conductivity of the thermal interface material.

[0006] At present, the methods for characterizing the thermal properties of thermal interface materials mainly include steady-state measurement method, laser flash method, low-frequency thermal reflection method, etc.

[0007] The steady-state measurement method is usually based on the ASTM-D5470 tester, which is a one-dimensional thermal conductivity test method in which the specimen is placed between two coplanar surfaces. One arm of the test fixture is usually electrically heated, while the other is cooled in order to establish a nearly uniform heat flow through the sample. By extrapolating the temperature difference between the two arms of the test fixture, the total thermal resistance of the sample can be found. Since the measurement area is far away from the sample, other thermal resistances outside the sample area need to be taken into account. If other thermal resistances are not calibrated accurately, it will also cause errors in the steady-state measurement. At the same time, the interface thermal resistance measured by the steady-state method is the overall thermal resistance of the thermal interface material at a certain thickness. The thermal conductivity and contact thermal resistance of the thermal interface material itself cannot be measured separately, and the measurement results do not have spatial distribution characteristics, so it is impossible to characterize the thermal properties of the thermal interface material with high spatial resolution.

[0008] The laser flash method is a non-contact method that can determine the thermal diffusivity of materials. A flash lamp (usually a xenon lamp) is used to illuminate one side of the sample, while the temperature of the back surface is monitored by an infrared detector. The temperature of the back surface is plotted over time, and the thermal diffusivity is usually determined by fitting the data to various models that include the boundary conditions of the test setup. This method is usually heated by a large spot laser, and the spatial resolution of the measurement is in the millimeter to centimeter range, and it is impossible to distinguish the distribution of thermal properties inside the sample.

[0009] The low-frequency thermal reflection method uses a beam of high-power laser to irradiate the sample surface, causing periodic temperature oscillations. After the second probe light irradiates the heated surface, the reflected light signal is received by the phase-locked amplifier. The intensity and phase of the reflected signal depend on the thermal properties of the sample and are used to extract the properties. The measurement parameters include the individual thermal resistance on the interface and the thermal resistance of the thermal interface material. When using this method to measure, in order to detect deep information, the spot of the heating light must be large enough and modulated at a low frequency so that the thermal signal can penetrate to the thermal interface material. Therefore, the highest spatial resolution of this method is only a few hundred microns, and it is impossible to perform higher-resolution thermal physical imaging to observe the distribution of thermal physical properties.

[0010] Commercial thermal interface materials are polymer composite thermal interface materials. Their microstructure (such as filler distribution, orientation, porosity, etc.) directly affects the formation of thermal conduction paths. Therefore, local thermal properties may vary, and macroscopic measurement methods are difficult to characterize. High-resolution thermal property imaging is required. The size of modern electronic devices is constantly shrinking, and the size of hot spots is getting smaller and smaller. The thermal conductivity of thermal interface materials in contact with local hot spots cannot be measured by traditional macroscopic methods, which may cause the temperature of local hot spots to be too high, causing damage to electronic devices; thermal interface materials may experience performance degradation (such as filler sedimentation, matrix cracking) under long-term thermal cycles, mechanical stress or chemical corrosion. High-resolution thermal property characterization can monitor the evolution of microscopic defects (such as crack extension, interface delamination) and establish material degradation models. Macroscopic measurement methods can only observe the decline in overall thermal conductivity and cannot analyze its microscopic mechanism.

[0011] Existing high-resolution thermal property measurements usually use FDTR frequency domain thermal reflection technology. This method usually deposits a metal sensor layer on the measured surface, and the heating light is focused on the sample surface through the objective lens to perform harmonic heating on the sample. Since the reflectivity of the metal film surface is proportional to the temperature rise, the detection light is reflected from the sample surface to the phase-locked amplifier to detect the temperature response of the sample surface. The thermal conductivity at the measurement location can be obtained by fitting the measurement results with the heat transfer model. The heating light and the detection light are usually focused into a spot with a radius of 1 to 10 microns through the objective lens, so this method can achieve high spatial resolution thermal property measurements at the micron level. However, this method requires a layer of metal film to be deposited on the measurement surface, and has high requirements for the flatness of the measured surface. Usually, the measured roughness Ra is less than 10nm. The polymer composite thermal interface material has a certain fluidity and cannot directly deposit a flat metal film on the surface. In addition, since it contains thermal conductive filler particles, the surface is not a smooth surface and does not have a good reflection effect. It is impossible to measure directly through frequency domain thermal reflection. Summary of the invention

[0012] The purpose of the present invention is to provide a high-resolution thermal property detection method and equipment for polymer composite thermal interface materials. By improving the preparation method of the sample to be tested, the traditional thermal property measurement method is changed to solve the problem of insufficient spatial resolution in measuring polymer composite thermal interface materials and inability to observe uneven distribution of thermal properties.

[0013] To achieve the above object, the first aspect of the present invention provides a method for detecting thermal properties of a polymer composite thermal interface material, comprising the following steps:

[0014] S101, depositing a gold film on one side of a double-sided polished silicon dioxide substrate, and calibrating the thermal physical parameters of the gold film using a frequency domain thermal reflection system to obtain the thermal physical parameters of the gold film;

[0015] S102, coating a polymer composite thermal interface material on the surface of the gold film to obtain a sample to be tested, covering the surface of the polymer composite thermal interface material with a pressing sheet, and then clamping the sample to be tested with a fixture; the fixture is pre-set with a test hole;

[0016] S103, selecting a measurement area, setting a sampling frequency and a sampling range using a frequency domain thermal reflection system, collecting thermal reflection signals on the surface of the sample to be measured point by point, and obtaining a measurement signal; wherein the heating light and the detection light in the test process are incident from one side of the silicon dioxide substrate;

[0017] S104, inputting the initial parameter value and the estimated parameter value of the sample to be tested into the heat transfer model to obtain a theoretical signal, and continuously adjusting the estimated parameter value to be tested. When the deviation between the measured signal and the theoretical signal is the smallest, the estimated parameter value to be tested is the target thermophysical property parameter.

[0018] Furthermore, the polymer composite thermal interface material is a fluid composited with a thermally conductive silicone grease or a thermally conductive gel polymer matrix and a thermally conductive filler, such as Shin-Etsu 7921, Shin-Etsu X-23-8149, Laird 607; the thickness is 10-200 μm. The main components of thermally conductive silicone grease are silicone oil (polydimethylsiloxane) and thermally conductive filler, the mass content of silicone oil is usually 20%-50%, the mass content of thermally conductive filler is usually 50%-80%, and the thermally conductive filler is a metal oxide (such as aluminum oxide, zinc oxide), a nitride (such as boron nitride) or a metal element (such as silver powder, liquid metal gallium), etc.

[0019] Furthermore, the pressing sheet is preferably a copper sheet.

[0020] Furthermore, in step S101, the thermophysical parameters of the gold film include thermal conductivity and thickness of the gold film, and interface thermal resistance between the gold film and silicon dioxide;

[0021] In step S104, the initial parameter values ​​include the thermal conductivity of the silicon dioxide substrate and the thermophysical parameters of the gold film, and the estimated parameter values ​​to be measured include thermal conductivity and estimated interface thermal resistance.

[0022] Furthermore, the thickness of the gold film is 50-200 nm;

[0023] Furthermore, the gold film is deposited by magnetron sputtering or electron beam evaporation.

[0024] Furthermore, in step S101, a plurality of gold film square areas with a side length of 200-500 μm are deposited on the silicon dioxide substrate through a grid mask to form a gold film matrix, and fixed-point sampling is achieved by numbering the position of each gold film square area.

[0025] Further, in step S103, the sampling frequency is a frequency range with high sensitivity to the measured parameter; specifically, a given thermophysical parameter is input into the heat transfer model, a phase delay signal within a preset frequency range is calculated, and then the magnitude of a certain thermophysical parameter is changed according to a gradient, and the phase delay signal within the preset frequency range under the parameter is recalculated, and the sensitivity of the thermophysical parameter within the preset frequency range is calculated according to the difference between the two phase delay signals and the difference between the thermophysical parameters according to the following sensitivity calculation formula, and a relationship curve between sensitivity and frequency is obtained, and a frequency range with large sensitivity is selected from the curve as the sampling frequency:

[0026]

[0027] Where x is the thermophysical parameter and φ is the phase delay signal.

[0028] Furthermore, in step S104, the measured signal and the theoretical signal are fitted by least squares to obtain target thermophysical property parameters, and a thermophysical property distribution diagram is drawn according to the fitted target thermophysical property parameters.

[0029] Furthermore, the frequency domain thermal reflection system comprises:

[0030] An optical path system for emitting heating light and detection light to a sampling point of a measurement area;

[0031] An electrically controlled translation stage for moving the heating light and the detection light to a target sampling point;

[0032] The phase-locked amplifier is used to collect and obtain the actual phase delay signal of each sampling point, which is the measurement signal.

[0033] A second aspect of the present invention provides a thermal property detection system for a polymer composite thermal interface material, comprising:

[0034] A sample fixing module is used to fix the sample to be tested by a fixture, wherein the sample to be tested includes a double-sided polished silicon dioxide substrate, a gold film and a polymer composite thermal interface material which are sequentially bonded from bottom to top, and a pressing sheet is provided between the fixture and the polymer composite thermal interface material;

[0035] A signal acquisition module is used to calibrate a sample consisting of a silicon dioxide substrate and a gold film through a frequency domain thermal reflection system to obtain thermal physical parameters of the gold film, and to sample the sample to be tested to obtain a measurement signal;

[0036] The data fitting module is used to input the initial parameter value and the estimated parameter value of the sample to be tested into the heat transfer model to obtain the theoretical signal, and continuously adjust the estimated parameter value to be tested. When the deviation between the measured signal and the theoretical signal is the smallest, the estimated parameter value to be tested is the target thermophysical property parameter.

[0037] Furthermore, the thermal property detection system further comprises an imaging module, which is used to obtain a fitted thermal property distribution image according to the target thermal property parameters. The data fitting module obtains the target thermal property parameters by a least squares fitting method.

[0038] In a third aspect, the present invention provides an electronic device, the device comprising: a processor, a memory, and a system bus;

[0039] The processor and the memory are connected via the system bus;

[0040] The memory is used to store one or more programs, and the one or more programs include instructions. When the instructions are executed by the processor, the processor executes the method according to the first aspect.

[0041] In a fourth aspect, the present invention provides a computer storage medium having codes stored therein. When the codes are executed, a device executing the codes implements any of the methods described in the first aspect.

[0042] In general, the above technical solution conceived by the present invention has the following technical advantages compared with the prior art:

[0043] 1. The method for detecting thermal properties of polymer composite thermal interface materials provided by the present invention overcomes the influence of the roughness of the polymer thermal interface material on the roughness of the gold film by first depositing a gold film on the surface of silicon dioxide and then depositing the polymer composite thermal interface material on the surface of the gold film. The change in the structure of the sample to be tested causes its heat transfer process to change, and high-resolution thermal property parameters can be obtained by targeted adjustment of the test process and parameters.

[0044] 2. The present invention fixes the polymer composite thermal interface material through a silicon dioxide substrate and a fixture, so that it can simulate the filling situation in actual application and can be conveniently measured by a frequency domain thermal reflection measurement system.

[0045] 3. The present invention prepares a micron-level gold film matrix through a grid mask, and can number each gold film area according to the position coordinates, which is convenient for finding the microscopic measurement area directly on the silicon dioxide substrate through the gold film coordinates, thereby improving the detection accuracy and efficiency.

[0046] 4. The present invention can characterize the thermal properties of polymer composite thermal interface materials with high spatial resolution, accurately observe the thermal property distribution of the contact surface of the polymer composite thermal interface materials under working conditions, and with the help of a high-precision translation stage, the resolution can reach 1 μm, providing a technical means for establishing the relationship between the thermal property distribution of polymer composite thermal interface materials and their internal structure, and analyzing the causes of performance degradation of polymer composite thermal interface materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 The present invention provides a flowchart of a method for high-resolution thermal physical property imaging of a polymer composite thermal interface material.

[0048] Figure 2 This is a physical picture of a silicon dioxide substrate after gold coating provided by an embodiment of the present invention.

[0049] Figure 3 It is an optimal parameter fitting diagram for calibrating the thermophysical property parameters of a gold film on a silicon dioxide substrate provided by an embodiment of the present invention.

[0050] Figure 4It is a schematic diagram of assembling a polymer composite thermal interface material measurement sample for fixing a polymer composite thermal interface material and providing a gold film sensor and a smooth surface required for a thermal reflection experiment provided by an embodiment of the present invention.

[0051] Figure 5 This is a physical picture of a polymer composite thermal interface material measurement sample provided by an embodiment of the present invention, which is assembled from a gold-plated silicon dioxide substrate, a polymer composite thermal interface material, a copper sheet, and a customized fixture.

[0052] Figure 6 It is a schematic diagram of a heat transfer model for calibrating the thermophysical property parameters of a gold film on a silicon dioxide substrate using FDTR provided in an embodiment of the present invention.

[0053] Figure 7 It is a schematic diagram of a heat transfer model for measuring thermal properties of polymer composite thermal interface materials using FDTR provided in an embodiment of the present invention.

[0054] Figure 8 It is a sensitivity curve diagram calculated using a heat transfer model of a polymer composite thermal interface material provided by an embodiment of the present invention.

[0055] Fig. 9 It is a micrograph of a measurement range selected during the imaging measurement of thermal properties of a polymer composite thermal interface material provided by an embodiment of the present invention.

[0056] Fig.10 It is an optimal parameter fitting diagram of a heat reflection signal at a certain position within the measurement range of a polymer composite thermal interface material provided by an embodiment of the present invention.

[0057] Fig.11 A thermal conductivity distribution map of a polymer composite thermal interface material drawn by a polymer composite thermal interface material thermal property imaging program is provided in an embodiment of the present invention.

[0058] Fig.12 An embodiment of the present invention provides an interface thermal resistance distribution map between a polymer composite thermal interface material and a gold film drawn by a polymer composite thermal interface material thermal property imaging program.

[0059] Fig.13 It is a structural schematic diagram of a high-resolution thermal property imaging device of a polymer composite thermal interface material provided by an embodiment of the present invention.

[0060] Fig.14 It is a structural schematic diagram of an electronic device provided by an embodiment of the present invention.

[0061] In all the drawings, the same figure numbers are used to represent the same elements or structures, wherein: 10-fixture, 11-copper sheet, 12-polymer composite thermal interface material, 13-gold film, 14-silicon dioxide substrate, 201-sample fixing module, 202-signal acquisition module, 203-data fitting module, 204-thermal property imaging module, 601-processing device, 602-ROM, 603-RAM, 604-bus, 605-input / output (I / O) interface, 606-input device, 607-output device, 608-storage device, 609-communication device. DETAILED DESCRIPTION

[0062] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0063] See also Figure 1 The present invention provides a method for detecting thermal properties of a polymer composite thermal interface material, comprising the following steps:

[0064] S101, depositing a gold film on one side of a double-sided polished silicon dioxide substrate, and calibrating the thermal physical parameters of the gold film using a frequency domain thermoreflectance system (FDTR) to obtain the thermal physical parameters of the gold film;

[0065] S102, coating a polymer composite thermal interface material on the surface of the gold film to obtain a sample to be tested, covering the surface of the polymer composite thermal interface material with a pressing sheet, and then clamping the sample to be tested with a fixture; the fixture is pre-set with a test hole;

[0066] S103, selecting a measurement area, setting a sampling frequency and a sampling range using a frequency domain thermal reflection system, collecting thermal reflection signals on the surface of the sample to be measured point by point, and obtaining a measurement signal; wherein the heating light and the detection light in the test process are incident from one side of the silicon dioxide substrate;

[0067] S104, inputting the initial parameter values ​​of the sample to be tested and the estimated thermal conductivity and the estimated interface thermal resistance values ​​into the heat transfer model to obtain a theoretical signal, and continuously adjusting the estimated thermal conductivity and the estimated interface thermal resistance values. When the deviation between the measured signal and the theoretical signal is minimized, the estimated thermal conductivity and the estimated interface thermal resistance values ​​are the target thermophysical property parameters.

[0068] Specifically, the method mainly comprises the following steps:

[0069] S101 deposits a 100nm gold film on a double-sided polished silicon dioxide substrate by magnetron sputtering or electron beam evaporation as the sensor layer for the thermal reflection experiment. In order to ensure the accuracy of subsequent measurements, the thermal physical properties of the sensor layer need to be calibrated. The coated silicon dioxide sample is measured through a standard FDTR experiment, and the thermal physical properties of the gold film are fitted.

[0070] In one embodiment, if Figure 2 As shown, a 400μm*400μm square area gold film matrix can be deposited on a silicon dioxide substrate using a customized grid mask. In this way, each gold film area can be numbered according to the position coordinates, and the subsequent microscopic measurement area can be found directly on the silicon dioxide substrate through the gold film coordinates, which is convenient for subsequent in-situ characterization.

[0071] The silicon dioxide was measured by the standard FDTR method. Since a standard silicon dioxide substrate was used, its thermal conductivity was known. The thermal conductivity parameters of the silicon dioxide substrate were fixed by the three-layer heat transfer model, and the thickness and thermal conductivity of the gold film were fitted. The thermal conductivity and thickness of the gold film sensor layer can be accurately calibrated. The fitting results are shown in Figure 3 The heat transfer model of the present invention can refer to the description in Review of Scientific Instrument by Schmidt et al., 2009, 80, 094901.

[0072] S102 evenly applies the polymer composite thermal interface material to be tested on the gold-plated side of the silicon dioxide substrate to ensure good contact with the gold film, covers the copper sheet on the polymer composite thermal interface material and clamps it with a customized fixture to ensure close contact and simulate the real application scenario. The polymer composite thermal interface material used in this embodiment is thermal conductive silicone grease Shin-Etsu x-23-8149, the main components of which are silicone oil and thermal conductive filler liquid metal gallium.

[0073] In some specific embodiments, Figure 4 As shown, the fixture 10, the silicon dioxide substrate 14, the gold film 13, the polymer composite thermal interface material 12, and the copper sheet 11 are assembled in sequence and clamped by bolts to ensure that there is a certain pre-tightening force between the polymer composite thermal interface material 12 and the gold film 13. The actual assembly diagram is shown in FIG. Figure 5 The laser passes through the circular hole (test hole) left by the fixture 10 and the silicon dioxide substrate 14 to irradiate the sensor layer of the gold film 13, thereby heating and detecting the polymer composite thermal interface material 12 to be tested.

[0074] S103 selects a frequency range with high sensitivity to the measured parameter as the heating frequency, selects the measured area to set the sampling range and sampling step, and performs point-by-point thermal reflection measurement of the measured area through the FDTR system.

[0075] The frequency domain thermoreflection system includes a phase-locked amplifier and an electrically controlled translation stage. Among them, the phase-locked amplifier (also called a phase detector) is an amplifier that can separate a specific carrier frequency signal from an environment with extremely high interference. In an embodiment of the present invention, the phase-locked amplifier is used to collect the actual phase delay signal of the detection light and the heating light at different sampling frequencies at the target sampling point.

[0076] In one embodiment, the method for collecting the actual phase delay signal of the target sampling point may be: first, the electric-controlled translation stage is moved based on the sampling step length so that the electric-controlled translation stage sets the target sampling point, and then the actual phase delay signal of the target sampling point is collected using the lock-in amplifier.

[0077] The sampling process uses two continuous beams of light to detect the thermal physical parameters of the physical hardware material. The first laser beam is called the pump light, which is loaded with a waveform through an electro-optic modulator and is used to periodically heat the surface of the material. After the material surface is polished, a metal reflective film is coated to absorb the heating of the pump light. Since the metal reflectivity changes linearly with the temperature rise, the second laser beam, called the probe light, can be used to detect the change in the thermal reflectivity of the surface of the physical hardware material, and then the surface temperature change is obtained. This change is affected by the thermal physical parameters inside the material. The FDTR system uses laser to detect the target sampling point. By changing the frequency of the laser, a phase-delayed amplifier is used to collect the phase delay signal (i.e., the actual phase delay signal) of the reflected light and modulated light at different frequencies of the target sampling point, and then the frequency domain thermal reflection signal in the scanning area is obtained.

[0078] In this patent, since the target object to be measured is a polymer composite thermal interface material, it does not have the flatness of a polished solid material surface, and the polymer composite thermal interface material usually has a certain fluidity, and it is impossible to fix the measurement surface and deposit a gold film. This patent utilizes the light transmittance of the silicon dioxide substrate, deposits a gold film on the surface of the silicon dioxide substrate, and then applies the polymer composite thermal interface material on the gold film, covers it with a copper sheet and fixes it with a clamp, which not only simulates the pressure characteristics of the polymer composite thermal interface material in an actual working environment, but also fixes the polymer composite thermal interface material through this method and converts it into a similar solid material that is usually measured by the frequency domain thermal reflection method for measurement.

[0079] In one embodiment, the heating light and the detection light are irradiated to the gold film through silicon dioxide, and the heat is transferred to the silicon dioxide substrate and the polymer composite thermal interface material on both sides through the gold film, and the reflected light is reflected by the gold film and received by the phase-locked amplifier. The heating light is heated and detected frequency by frequency according to the preset heating frequency, and moves according to the set step size in the set measurement area, and the heat reflection signal of each position is collected in turn to obtain the heat reflection signal in the entire area to be measured.

[0080] S104 compares the measured thermal reflection signal (theoretical phase delay signal) with the theoretical signal (theoretical phase delay signal) calculated by the heat transfer model of the polymer composite thermal interface material, reduces the gap between the model and the experimental signal by continuously adjusting the model parameters, performs least squares fitting on the experimental signal, and draws a thermophysical property distribution diagram based on the thermophysical property parameters obtained by fitting.

[0081] The theoretical phase delay signal is obtained by inputting given parameters into the five-layer heat reflection signal heat transfer model. The method for obtaining the theoretical phase delay signal includes:

[0082] Setting the thermophysical property parameters of the layered heat transfer model and determining the frequency domain response of the theoretical phase delay signal under the layered heat transfer model;

[0083] A theoretical phase delay signal of the target sampling point is calculated based on the frequency domain response.

[0084] Usually, the FDTR heat transfer model is as follows Figure 6 As shown in the figure, 13 is a gold film, 14 is a silicon dioxide substrate, and heat is transferred downward from the gold film 13 to the sample layer to be measured. In the embodiment of the present invention, the thermal interface measurement heat transfer model is as follows Figure 7 As shown, 11 is a copper sheet, 12 is a polymer composite thermal interface material, 13 is a gold sensor layer, and 14 is a silicon dioxide substrate. The heating light and the detection light are irradiated to the gold film 13 through the silicon dioxide substrate 14, and the heat is transferred upward through the upper surface of the gold film 13 sensor layer to the silicon dioxide substrate 14, and downward through the gold film 13 to the polymer composite thermal interface material 12 and then to the copper sheet 11 at the bottom.

[0085] FDTR technology uses heating light to heat samples coated with 50-200nm metal film. The increase in sample temperature will cause the reflectivity of the metal film to change. Another beam of detection light is used to detect the thermal response of the sample surface, where the pump light is modulated at different frequencies. By changing the modulation frequency of the pump light, the phase delay of the surface temperature relative to the heating harmonic is detected as the modulation frequency changes to extract the thermal properties.

[0086] Usually, the degree of change of the phase delay of the thermophysical parameter under different heating frequencies is different. Therefore, when a certain parameter changes to the same degree, the degree of change of the phase delay signal at different frequencies can reflect the measurement sensitivity of the experimental signal to a certain parameter under different experimental frequencies. The definition of sensitivity is Where x is the parameter of the thermal reflection model, and φ is the thermal reflection phase delay signal.

[0087] In one embodiment, the sampling frequency range set in S103 is obtained by a sensitivity calculation program written according to a polymer composite thermal interface material measurement heat transfer model. Specifically, a given thermophysical parameter is input into a phase delay calculation program written according to a polymer composite thermal interface material measurement heat transfer model, and a phase delay signal within a wide frequency range is calculated. Then, a certain thermophysical parameter is increased by 10%, and the phase delay signal within a wide frequency range under the thermophysical parameter is recalculated. Based on the difference between the two phase delay signals and the parameter difference, the sensitivity of the parameter within a wide frequency range is calculated according to the sensitivity calculation formula. The calculation result is as follows: Figure 8 As shown, the k3 and k5 curves are respectively the sensitivity to the thermal conductivity of the gold film sensor layer and the thermal interface material layer, the C3 and C5 curves are respectively the sensitivity to the volume heat capacity of the gold film sensor layer and the thermal interface material layer, the d3 curve is the sensitivity to the thickness of the gold film sensor layer, and the G4 curve is the sensitivity to the interface thermal conductivity between the polymer composite thermal interface material and the gold film sensor layer. The positive and negative values ​​of the sensitivity represent positive correlation and negative correlation, respectively, and the absolute value represents the sensitivity. From the calculated sensitivity curve, it can be seen that for the thermal conductivity k5 of the TIM material to be measured, the experiment has good sensitivity when the frequency is between 0.001MHz and 1MHz. Therefore, the frequency range set in S103 can be selected as 0.001~1MHz, and eight sampling frequency points are selected according to the logarithmic spacing.

[0088] In one embodiment, a gold film with a position coordinate of (6, 5) is selected for measurement. Since the default starting point coordinate of the translation stage is the center of the scanning area when performing point-by-point scanning, in order to better position the scanning area, the spot position is first set to (200, 200) microns through the electric-controlled translation stage, and the spot is aligned with the upper right corner of the square gold film through the spiral shifter, and then the spot position coordinate is set to (100, 100) microns through the electric-controlled translation stage. In this way, it can be ensured that the measurement area is a square area of ​​200 microns × 200 microns in the upper right corner of the square gold film, such as Fig. 9 As shown, it is convenient for the subsequent in-situ characterization of the structure of polymer composite thermal interface materials.

[0089] In one embodiment, the electric-controlled translation stage moves the sample according to a preset measurement range and step length, changes the heating light modulation frequency within a preset frequency range for each measurement point to heat and detect the sample, and saves the data as a text file after the measurement is completed. The data is input into the thermal physical property imaging module of the polymer composite thermal interface material. First, the experimental signal is extracted, and the measured phase delay and amplitude are stored as a matrix according to the position. Next, for each measurement position point within the measurement range, the manually set estimated thermal physical property parameters are input into the heat transfer model of the polymer composite thermal interface material to calculate the theoretical phase delay. The mean square error of the theoretical phase delay and the experimental signal is calculated as the deviation value. If the above calculated deviation is greater than the preset deviation threshold, it means that the measured signal and the theoretical signal cannot fit well, and then it means that the estimated parameter to be measured is very different from the true value. Then the preset parameters can be adjusted and re-input into the vertical interface heat transfer model, and the theoretical signal is calculated again and the deviation is calculated. If the deviation is less than the preset deviation threshold at this time, the preset parameters are used as the interface thermal resistance value of the interface to be measured. If the deviation is still greater than the preset deviation threshold at this time, the preset parameters are continued to be adjusted and input into the vertical interface heat transfer model again, and so on, until the estimated interface thermal resistance value that makes the deviation between the measured signal and the theoretical signal less than the preset deviation threshold is obtained, and it is used as the best fitting value of the parameter to be measured. The effect of single-point fitting is as follows. Fig.10 shown.

[0090] Optionally, the process of continuously adjusting the estimated node thermal resistance value and comparing the deviation with a preset deviation threshold may be implemented by using a minimum value search function.

[0091] The parameter fitting of multiple measurement sites can be performed simultaneously through parallel programs. The optimal parameters obtained after the parameter fitting of all measurement points are stored as a matrix. The thermophysical properties and corresponding coordinates in the matrix are plotted as a color map. The thermophysical properties of each position are plotted as a pixel point. The value of the thermophysical property parameter is displayed by the depth of color, so as to perform high spatial resolution thermophysical imaging of polymer composite thermal interface materials, such as Fig.11 , Fig.12 As shown. By drawing the thermophysical property distribution diagram, we can clearly see the distribution of thermophysical properties within the measurement range, and combine other in-situ measurement methods to analyze and characterize the causes of uneven distribution of thermophysical properties.

[0092] See also Fig.13 The present invention also provides an interface thermal resistance measuring device, the device comprising:

[0093] The sample fixing module 201 is used to fix the polymer composite thermal interface material and provide the measurement conditions of the gold film sensor layer and the smooth surface for the thermal reflection measurement. The polymer composite thermal interface material is fixed by the clamp, the gold-plated silicon dioxide substrate and the copper sheet to simulate the real working scene.

[0094] The signal acquisition module 202 is used to select the measurement area and displacement step, set the measurement frequency range, control the electric control stage to move the sample, modulate the heating light according to the preset frequency for heating and receive the reflected signal of the detection light for point-by-point measurement, and store the measurement data as a file.

[0095] The data fitting module 203 is used to input the initial parameter value and the estimated parameter value of the sample to be tested into the heat transfer model of the polymer composite thermal interface material to obtain a theoretical signal, and determine whether the deviation between the experimental measurement signal and the theoretical signal is less than a preset deviation threshold. If so, the estimated parameter value to be tested is used as the best fitting parameter value. If not, the estimated parameter value to be tested is adjusted. After adjustment, the initial parameter value and the estimated parameter value to be tested of the sample to be tested are returned and input into the heat transfer model of the polymer composite thermal interface material. After parameter fitting is performed on each measurement site, the best fitting parameters are stored as a matrix.

[0096] Thermophysical property imaging module 204 is used to plot the fitting results into a color map according to spatial coordinates. The thermophysical property of each position is plotted as a pixel point, and the numerical value of the thermophysical property parameter is displayed by color depth, thereby performing high spatial resolution thermophysical property imaging of the polymer composite thermal interface material.

[0097] See also Fig.14 The present invention also provides an electronic device, which may include but is not limited to fixed terminals such as mobile phones, notebook computers, PDAs (personal digital assistants), PADs (tablet computers), desktop computers, etc. Fig.14 The electronic device shown is only an example and should not bring any limitation to the functions and scope of use of the embodiments of the present invention.

[0098] like Fig.14 As shown, the electronic device may include a processing device 601 (such as a central processing unit, a graphics processing unit, etc.), which can perform various appropriate actions and processes according to a program stored in a read-only memory ROM 602 or a program loaded from a storage device 608 to a random access memory RAM 603, so that the electronic device can implement the interface thermal resistance measurement method provided by any of the above embodiments. When the electronic device is powered on, various programs and data required for the operation of the electronic device are also stored in RAM 603. The processing device 601, ROM 602 and RAM 603 are connected to each other via a bus 604. An input / output (I / O) interface 605 is also connected to the bus 604.

[0099] Typically, the following devices may be connected to the input / output (I / O) interface 605: input devices 606 including, for example, a touch screen, a touch pad, a keyboard, a mouse, a camera, a microphone, an accelerometer, a gyroscope, etc.; output devices 607 including, for example, a liquid crystal display (LCD), a speaker, a vibrator, etc.; storage devices 608 including, for example, a memory card, a hard disk, etc.; and communication devices 609. The communication devices 609 may allow the electronic device to communicate with other devices wirelessly or by wire to exchange data.

[0100] An embodiment of the present invention further provides a computer program product including computer-readable instructions. When the computer-readable instructions are executed on an electronic device, the electronic device implements any interface thermal resistance measurement method provided by the embodiment of the present invention.

[0101] A computer-readable storage medium is also provided in an embodiment of the present invention. The storage medium carries one or more computer programs. When the one or more computer programs are executed by an electronic device, the electronic device can implement any interface thermal resistance measurement method provided in an embodiment of the present invention.

[0102] It should also be noted that the device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the present embodiment. In addition, in the drawings of the device embodiments provided by the present invention, the connection relationship between the modules indicates that there is a communication connection between them, which may be specifically implemented as one or more communication buses or signal lines.

[0103] Through the description of the above implementation mode, the technicians in the relevant field can clearly understand that the present invention can be implemented by means of software plus necessary general hardware, and of course, it can also be implemented by special hardware including special integrated circuits, special CPUs, special memories, special components, etc. In general, all functions completed by computer programs can be easily implemented by corresponding hardware, and the specific hardware structure used to implement the same function can also be various, such as analog circuits, digital circuits or special circuits. However, for the present invention, software program implementation is a better implementation mode in more cases. Based on such an understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a readable storage medium, such as a computer floppy disk, a U disk, a mobile hard disk, a ROM, a RAM, a magnetic disk or an optical disk, etc., including a number of instructions to enable a computer device (which can be a personal computer, a training device, or a network device, etc.) to execute the methods described in each embodiment of the present invention.

[0104] In the above embodiments, all or part of the embodiments may be implemented by software, hardware, firmware or any combination thereof. When implemented by software, all or part of the embodiments may be implemented in the form of a computer program product.

[0105] The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present invention is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from a website, a computer, a training device, or a data center to another website, a computer, a training device, or a data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium may be any available medium that a computer can store or a data storage device such as a training device, a data center, etc. that includes one or more available media integrated. The available medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state drive (SSD)), etc.

[0106] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for detecting thermal properties of a polymer composite thermal interface material, characterized in that: The following steps are involved: S101, depositing a gold film on one side of a double-sided polished silicon dioxide substrate, and calibrating the thermal physical parameters of the gold film using a frequency domain thermal reflection system to obtain the thermal physical parameters of the gold film; S102, coating the surface of the gold film with a polymer composite thermal interface material to obtain a sample to be tested, using a pressing sheet to cover the surface of the polymer composite thermal interface material, and then clamping the sample to be tested with a clamp; The fixture is provided with a test hole; S103, selecting a measurement area, setting a sampling frequency and a sampling range using a frequency domain thermal reflection system, collecting thermal reflection signals on the surface of the sample to be measured point by point, and obtaining a measurement signal; wherein the heating light and the detection light in the collection process are incident from one side of the silicon dioxide substrate through the test hole; S104, inputting the initial parameter value and the estimated parameter value of the sample to be tested into the heat transfer model to obtain a theoretical signal, and continuously adjusting the estimated parameter value to be tested. When the deviation between the measured signal and the theoretical signal is the smallest, the estimated parameter value to be tested is the target thermophysical property parameter.

2. The method for detecting thermal properties of a polymer composite thermal interface material according to claim 1, characterized in that: The polymer composite thermal interface material is thermally conductive silicone grease, or a fluid composited by a thermally conductive gel polymer matrix and a thermally conductive filler, and has a thickness of 10-200 μm.

3. The method for detecting thermal properties of a polymer composite thermal interface material according to claim 1, characterized in that: In step S101, the thermophysical parameters of the gold film include thermal conductivity and thickness of the gold film, and interface thermal resistance between the gold film and silicon dioxide; In step S104, the initial parameter values ​​include the thermal conductivity of the silicon dioxide substrate and the thermophysical parameters of the gold film, and the estimated parameter values ​​to be measured include the estimated thermal conductivity and the estimated interface thermal resistance.

4. The method for detecting thermal properties of a polymer composite thermal interface material according to claim 1, characterized in that: The thickness of the gold film is 50-200 nm; the gold film is deposited by magnetron sputtering or electron beam evaporation.

5. The method for detecting thermal properties of a polymer composite thermal interface material according to claim 1, characterized in that: In step S101, a plurality of gold film square areas with a side length of 200-500 μm are deposited on the silicon dioxide substrate through a grid mask to form a gold film matrix, and fixed-point sampling is achieved by numbering the position of each gold film square area.

6. The method for detecting thermal properties of a polymer composite thermal interface material according to any one of claims 1 to 5, characterized in that: In step S103, the sampling frequency is determined according to the sensitivity of the parameter to be measured; specifically, the given thermophysical parameter is input into the heat transfer model, the phase delay signal within the preset frequency range is calculated, and then the magnitude of a certain thermophysical parameter is changed according to the gradient, and the phase delay signal within the preset frequency range under the parameter is recalculated. According to the difference between the two phase delay signals and the difference between the thermophysical parameters, the sensitivity S of the thermophysical parameter within the preset frequency range is calculated according to the following sensitivity calculation formula x Perform the calculation: Where x is the thermophysical parameter and φ is the phase delay signal.

7. The method for detecting thermal properties of a polymer composite thermal interface material according to any one of claims 1 to 5, characterized in that: In step S104, the measured signal and the theoretical signal are fitted by least squares to obtain target thermophysical property parameters, and a thermophysical property distribution diagram is drawn according to the fitted target thermophysical property parameters.

8. The method for detecting thermal properties of a polymer composite thermal interface material according to any one of claims 1 to 5, characterized in that: The frequency domain thermal reflection system comprises: An optical path system for emitting heating light and detection light to a sampling point of a measurement area; An electrically controlled translation stage for moving the heating light and the detection light to a target sampling point; The phase-locked amplifier is used to collect and obtain the actual phase delay signal of each sampling point, which is the measurement signal.

9. A thermal property detection system for a polymer composite thermal interface material, characterized in that: include: A sample fixing module is used to fix the sample to be tested by a fixture, wherein the sample to be tested includes a double-sided polished silicon dioxide substrate, a gold film and a polymer composite thermal interface material which are sequentially bonded from bottom to top, and a pressing sheet is provided between the fixture and the polymer composite thermal interface material; A signal acquisition module is used to calibrate a sample consisting of a silicon dioxide substrate and a gold film through a frequency domain thermal reflection system to obtain thermal physical parameters of the gold film, and to sample the sample to be tested to obtain a measurement signal; The data fitting module is used to input the initial parameter value and the estimated parameter value of the sample to be tested into the heat transfer model to obtain the theoretical signal, and continuously adjust the estimated parameter value to be tested. When the deviation between the measured signal and the theoretical signal is the smallest, the estimated parameter value to be tested is the target thermophysical property parameter.

10. The thermal property detection system of the polymer composite thermal interface material according to claim 9, characterized in that: The thermal property detection system also includes a thermal property imaging module, which is used to obtain a fitted thermal property distribution image according to the target thermal property parameters.

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