CN221124395U

CN221124395U - Device for measuring in-plane thermophysical quantity of film

Info

Publication number: CN221124395U
Application number: CN202323196907.3U
Authority: CN
Inventors: 王汉夫; 褚卫国; 郭延军; 王东伟; 徐波; 任红轩; 窦凯飞
Original assignee: National Center for Nanosccience and Technology China
Current assignee: National Center for Nanosccience and Technology China
Priority date: 2023-11-24
Filing date: 2023-11-24
Publication date: 2024-06-11
Anticipated expiration: 2033-11-24

Abstract

The utility model discloses a measuring device of in-plane thermal physical quantity of a film, wherein the measuring device is applied to the measurement of in-plane thermal conductivity, the measurement of in-plane thermal diffusivity and the measurement of volume heat capacity of a self-supporting film, and the measuring device comprises: the device comprises a frequency-doubling signal acquisition box, a data acquisition module and a control module; the frequency-tripled signal acquisition box comprises an alternating current source module, a fundamental frequency signal elimination circuit, a first secondary amplifier, a first matrix switch and a sampling resistor; the frequency doubling signal acquisition box comprises a direct current/alternating current constant current source module, a direct current signal elimination circuit, a second secondary amplifier and a second matrix switch. According to the technical scheme, the synchronous acquisition of the frequency doubling voltage signal on the first conducting strip and the frequency doubling voltage signal on the second conducting strip is realized, the fundamental frequency voltage signal and the direct current voltage signal are eliminated, and the efficient and accurate measurement of the in-plane thermal physical quantity of the film is realized.

Description

Device for measuring in-plane thermophysical quantity of film

Technical Field

The utility model relates to the technical field of thermophysical property measurement, in particular to a device for measuring thermophysical property in a film plane.

Background

In the development process of functional films such as thermoelectric films and phase-change films, the thermal physical properties such as thermal conductivity and thermal diffusivity of the functional films need to be systematically characterized. When the in-plane thermal conductivity of the film is measured, alternating current heating current with a certain frequency is introduced into the first conductive strip, direct current detection current is introduced into the second conductive strip, temperature fluctuation information on the two conductive wires is obtained by measuring a frequency tripling voltage signal on the first conductive wire and a frequency doubling voltage signal on the second conductive wire, and then the thermal physical property of the film to be measured is inverted according to a certain heat transfer model. One key in implementing the method is how to accurately measure weak frequency-tripled voltage signals and frequency-doubled voltage signals by eliminating interference of frequency-doubled (fundamental frequency) signals on the first conductive strip and direct-current voltage signals on the second conductive wire.

In the film in-plane thermal conductivity measurement, in order to obtain the thermophysical property of the film, not only the frequency-doubled voltage signal and the frequency-doubled voltage signal, but also the variable resistance and the resistance of two conducting strips in a circuit are required to be measured; if the alternating current source providing the heating current is not a constant current source, the amplitude of the alternating current needs to be calibrated additionally. In order to complete the measurement of the physical quantity, the connection mode of the measurement circuit needs to be changed frequently, which is time-consuming. Therefore, in the measurement of the in-plane thermophysical properties of a thin film, it is important to improve the accuracy of the measurement result and the efficiency of the measurement.

Disclosure of utility model

The utility model provides a device for measuring an in-plane thermophysical quantity of a film, which aims to solve the problems of low efficiency and low accuracy in the in-plane thermophysical quantity measuring process of the film in the prior art.

According to an aspect of the present utility model, there is provided a thin film in-plane thermophysical quantity measuring apparatus applied to measurement of in-plane thermal conductivity, measurement of in-plane thermal diffusivity, and measurement of volumetric heat capacity of a self-supporting thin film, the thin film in-plane thermophysical quantity measuring apparatus comprising:

The device comprises a frequency-doubling signal acquisition box, a data acquisition module and a control module;

The frequency-tripled signal acquisition box comprises an alternating current source module, a fundamental frequency signal elimination circuit, a first secondary amplifier, a first matrix switch and a sampling resistor; the frequency tripling signal collecting box is used for collecting frequency tripling signals;

the alternating current source module is connected with the first conducting strip, the first conducting strip is connected with the fundamental frequency signal eliminating circuit, the fundamental frequency signal eliminating circuit is connected with the first secondary amplifier, the first secondary amplifier is connected with the first matrix switch, and the first matrix switch is connected with the data acquisition module; the sampling resistor is respectively connected with the first conducting strip and the first matrix switch;

The frequency doubling signal acquisition box comprises a direct current/alternating current constant current source module, a direct current signal elimination circuit, a second secondary amplifier and a second matrix switch; the frequency doubling signal acquisition box is used for acquiring frequency doubling signals;

the direct current/alternating current constant current source module is connected with a second conducting bar, the second conducting bar is connected with a direct current signal eliminating circuit, the direct current signal eliminating circuit is connected with a second secondary amplifier, the second secondary amplifier is connected with a second matrix switch, and the second matrix switch is connected with the data acquisition module;

The alternating current source module, the fundamental frequency signal eliminating circuit and the first matrix switch are all in communication connection with the control module; the direct current/alternating current constant current source module, the direct current signal eliminating circuit and the second matrix switch are all in communication connection with the control module;

The control module and the data acquisition module are connected and used for calculating the in-plane thermophysical quantity of the film according to the frequency tripling signal and the frequency doubling signal.

Optionally, the baseband signal cancellation circuit includes: the digital-to-analog conversion circuit comprises a first variable resistor, a first digital-to-analog conversion chip, a first digital output circuit, a first amplifier and a second amplifier, wherein the amplification factors of the first amplifier and the second amplifier are the same; the first conductive strip is connected with the first variable resistor in series; the input end of the first amplifier is respectively connected with two ends of the first conducting strip; the input end of the second amplifier is respectively connected with the two ends of the first variable resistor; the output end of the second amplifier is connected with the first digital-to-analog conversion chip; the first digital output circuit is connected with the first digital-to-analog conversion chip;

The first differential input end of the first secondary amplifier is respectively connected with the output end of the first amplifier and the first input end of the first matrix switch; the second differential input end of the first secondary amplifier is respectively connected with the first digital-to-analog conversion chip and the third input end of the first matrix switch; the output end of the first secondary amplifier is connected with the second input end of the first matrix switch;

The frequency-tripled signal acquisition box also comprises a sampling resistor amplifier; the input end of the sampling resistor amplifier is respectively connected with two ends of the sampling resistor, and the output end of the sampling resistor amplifier is connected with the fourth input end of the first matrix switch;

The DC signal cancellation circuit includes: the second variable resistor, the second digital-to-analog conversion chip, the second digital output circuit, the third amplifier and the fourth amplifier have the same amplification factor; the second conductive strip is connected with the second variable resistor in series; the input end of the third amplifier is respectively connected with two ends of the second conducting strip; the input end of the fourth amplifier is respectively connected with the two ends of the second variable resistor; the output end of the fourth amplifier is connected with the second digital-to-analog conversion chip; the second digital output circuit is connected with the second digital-to-analog conversion chip;

The first differential input end of the second secondary amplifier is respectively connected with the output end of the third amplifier and the first input end of the second matrix switch; the second differential input end of the second secondary amplifier is respectively connected with the second digital-to-analog conversion chip and the third input end of the second matrix switch; the output of the second secondary amplifier is connected to the second input of the second matrix switch.

Optionally, the data acquisition module includes a first input end, a second input end and a third input end;

the first input end is connected with the first output end of the first matrix switch; the second input end is connected with the second output end of the first matrix switch; the third input terminal is connected to the output terminal of the second matrix switch.

Optionally, the data acquisition module includes a synchronous data acquisition card or a lock-in amplifying circuit.

Optionally, the frequency tripling signal acquisition box further comprises a first interaction unit;

The first interaction unit comprises a first knob, a first panel signal input port and a first panel signal output port;

The first knob is connected with the first variable resistor and used for adjusting the size of the first variable resistor; the first matrix switch is connected with the data acquisition module through a first panel signal output port;

the frequency doubling signal acquisition box also comprises a second interaction unit;

The second interaction unit comprises a second knob, a second panel signal input port and a second panel signal output port;

The second knob is connected with the second variable resistor and is used for adjusting the size of the second variable resistor; the second panel signal input port is connected with the wiring end of the second conducting strip, and the second matrix switch is connected with the data acquisition module through the second panel signal output port.

According to the technical scheme, the frequency tripling signal acquisition box, the frequency doubling signal acquisition box, the data acquisition module and the control module are arranged in the thin film in-plane thermal physical quantity measurement device, so that the frequency tripling voltage signal on the first conducting strip and the frequency doubling voltage signal on the second conducting strip are simultaneously acquired, interference of fundamental frequency voltage signals and direct current voltage signals is eliminated, and the thin film in-plane thermal physical quantity measurement device can be conveniently switched to a resistance measurement function, and therefore high-efficiency and accurate measurement of the thin film in-plane thermal physical quantity is realized. Meanwhile, the frequency tripling signal collecting box also comprises a sampling resistor, and the sampling resistor can be used for realizing current calibration and providing reference signal output.

It should be understood that the description in this section is not intended to identify key or critical features of the embodiments of the utility model or to delineate the scope of the utility model. Other features of the present utility model will become apparent from the description that follows.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present utility model, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic connection diagram of a frequency tripled signal collection box according to an embodiment of the present utility model;

FIG. 2 is a schematic diagram of connection of a frequency doubling signal collection box according to an embodiment of the present utility model;

FIG. 3 is a schematic diagram of the connection of a frequency tripled signal and a frequency doubled signal acquisition box according to an embodiment of the present utility model;

fig. 4 is a schematic structural diagram of a first interaction unit of a frequency tripled signal collection box according to an embodiment of the present utility model;

Fig. 5 is a schematic structural diagram of a second interaction unit of a frequency doubling signal collection box according to an embodiment of the present utility model;

FIG. 6 is a flowchart of a first method for measuring in-plane thermophysical quantity of a thin film according to an embodiment of the present utility model;

FIG. 7 is a flowchart of a first method for obtaining the current amplitude of the AC current source module, the resistance value of the first conductive strip, and the resistance value of the first variable resistor according to an embodiment of the present utility model;

FIG. 8 is a flow chart of a first method for obtaining the resistance value of the second conductive strip and the resistance value of the second variable resistor according to an embodiment of the present utility model;

FIG. 9 is a flowchart of a second method for obtaining a current amplitude of an AC current source module, a resistance value of a first conductive strip, and a resistance value of a first variable resistor according to an embodiment of the present utility model;

fig. 10 is a flowchart of a method for eliminating a baseband signal according to an embodiment of the present utility model;

FIG. 11 is a flowchart of a method for eliminating DC signals according to an embodiment of the present utility model;

FIG. 12 is a flow chart of a method for acquiring the amplitude of a frequency-tripled signal, the initial phase of the frequency-tripled signal, and the initial phase of the frequency-doubled signal according to an embodiment of the present utility model;

FIG. 13 is a schematic diagram of a system for measuring in-plane thermophysical quantity of a thin film according to an embodiment of the present utility model;

FIG. 14 is a plot of frequency tripled signal amplitude versus excitation current frequency for a first conductive strip in a film according to an embodiment of the present utility model;

FIG. 15 is a graph showing the trend of the phase of temperature fluctuation on the first and second conductive strips in a thin film according to the embodiment of the present utility model as a function of the frequency of the excitation current;

FIG. 16 is a schematic illustration of a film according to an embodiment of the present utility model A schematic diagram of a measurement result changing along with the temperature fluctuation amplitude delta T ₁ of the first conducting strip;

fig. 17 is a schematic diagram of measurement results of angular frequency ω of excitation current in a thin film according to an embodiment of the present utility model as a function of M (2ω) ·n (2ω).

Detailed Description

In order that those skilled in the art will better understand the present utility model, a technical solution in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present utility model, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present utility model without making any inventive effort, shall fall within the scope of the present utility model.

It should be noted that the terms "first," "second," and the like in the description and the claims of the present utility model and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the utility model described herein may be implemented in sequences other than those illustrated or otherwise described herein.

Fig. 1 is a schematic connection diagram of a frequency tripled signal collection box according to an embodiment of the present utility model, fig. 2 is a schematic connection diagram of a frequency doubler signal collection box according to an embodiment of the present utility model, and fig. 3 is a schematic connection diagram of a frequency tripled signal collection box and a frequency doubler signal collection box according to an embodiment of the present utility model, where the device for measuring an in-plane thermal physical quantity of a film is applied to measurement of in-plane thermal conductivity, measurement of in-plane thermal diffusivity, and measurement of volumetric heat capacity of a self-supporting film. When the self-supporting film is used for measuring the in-plane thermophysical quantity, a first conducting strip and a second conducting strip which are parallel to each other are manufactured on the surface of the self-supporting film, the first conducting strip is used as a heater and a thermometer, the second conducting strip is used as a thermometer, and the thermophysical property of the film to be measured is calculated by acquiring temperature fluctuation information on the first conducting strip and the second conducting strip through a measuring device. As shown in connection with fig. 1, 2 and 3, the measuring device comprises:

The frequency doubling signal acquisition box 7, the frequency doubling signal acquisition box 8, the data acquisition module 9 and the control module 55;

The frequency-tripled signal acquisition box 7 comprises an alternating current source module 10, a fundamental frequency signal elimination circuit 11, a first secondary amplifier 12, a first matrix switch 13 and a sampling resistor 14; the frequency tripling signal collection box 7 is used for collecting frequency tripling signals;

The alternating current source module 10 is connected with the first conducting strip 4, the first conducting strip 4 is connected with the fundamental frequency signal eliminating circuit 11, the fundamental frequency signal eliminating circuit 11 is connected with the first secondary amplifier 12, the first secondary amplifier 12 is connected with the first matrix switch 13, and the first matrix switch 13 is connected with the data acquisition module 9; the sampling resistor 14 is respectively connected with the first conducting strip 4 and the first matrix switch 13;

The frequency doubling signal acquisition box 8 comprises a direct current/alternating current constant current source module 30, a direct current signal eliminating circuit 31, a second secondary amplifier 32 and a second matrix switch 33; the frequency doubling signal acquisition box 8 is used for acquiring frequency doubling signals;

The direct current/alternating current constant current source module 30 is connected with the second conducting strip 5, the second conducting strip 5 is connected with the direct current signal eliminating circuit 31, the direct current signal eliminating circuit 31 is connected with the second secondary amplifier 32, the second secondary amplifier 32 is connected with the second matrix switch 33, and the second matrix switch 33 is connected with the data acquisition module 9;

The alternating current source module 10, the fundamental frequency signal eliminating circuit 11 and the first matrix switch 13 are all in communication connection with the control module 55; the direct current/alternating current constant current source module 30, the direct current signal eliminating circuit 31 and the second matrix switch 33 are all in communication connection with the control module 55;

The control module 55 is connected with the data acquisition module 9 and is used for calculating the film in-plane thermophysical quantity according to the frequency-tripling signal and the frequency-doubling signal.

The frequency tripling signal collection box 7 is connected with the first conducting strip 4 and used for collecting frequency tripling signals on the first conducting strip 4, and the frequency tripling signal collection box 7 collects frequency tripling voltage signals on the first conducting strip 4 and eliminates fundamental frequency voltage signals on the first conducting strip 4 so as to prevent the fundamental frequency voltage signals from interfering with measurement of the frequency tripleing voltage signals and affecting accuracy of measurement of thermal physical quantity in a film plane; the frequency doubling signal collection box 8 is connected with the second conducting strip 5 and is used for collecting frequency doubling signals on the second conducting strip 5, and the frequency doubling signal collection box 8 collects frequency doubling voltage signals on the second conducting strip 5 and eliminates direct current voltage signals on the second conducting strip 5 so as to prevent the direct current voltage signals from interfering with measurement of the frequency doubling voltage signals and affecting accuracy of measurement of the thermal physical quantity in the film plane.

Specifically, the connection relationship of the frequency tripling signal acquisition box 7 is as follows: the alternating current source module 10 is connected with the first conducting strip 4, the first conducting strip 4 is connected with the fundamental frequency signal eliminating circuit 11, the fundamental frequency signal eliminating circuit 11 is connected with the first secondary amplifier 12, the first secondary amplifier 12 is connected with the first matrix switch 13, and the first matrix switch 13 is connected with the data acquisition module 9; the sampling resistor 14 is connected to the first conductive strip 4 and the first matrix switch 13, respectively. The alternating current source module 10 is used for outputting alternating current with certain frequency and amplitude, and the alternating current sequentially passes through the first conducting strip 4 and the sampling resistor 14 which are connected in series; the baseband signal eliminating circuit 11 is used for eliminating a baseband voltage signal in the first alternating current signal; the first secondary amplifier 12 serves to differentially amplify the voltage signal, and in some embodiments the first secondary amplifier 12 has a magnification of at least 100 times; the first matrix switch 13 is used for transmitting the voltage signal to the data acquisition module 9; the sampling resistor 14 is used for calibrating the output current amplitude of the alternating current source and the effect of the output reference voltage signal.

The connection relation of the frequency doubling signal acquisition box 8 is as follows: the direct current/alternating current constant current source module 30 is connected with the second conductive strip 5, the second conductive strip 5 is connected with the direct current signal eliminating circuit 31, the direct current signal eliminating circuit 31 is connected with the second secondary amplifier 32, the second secondary amplifier 32 is connected with the second matrix switch 33, and the second matrix switch 33 is connected with the data acquisition module 9. The direct current/alternating current constant current source module 30 is used for outputting direct current constant current or alternating current constant current into the second conductive strip 5; the dc signal cancellation circuit 31 is configured to cancel a dc voltage signal in the second ac signal; the second secondary amplifier 32 acts to differentially amplify the voltage signal, and in some embodiments, the second secondary amplifier 32 has a magnification of at least 100 times; the second matrix switch 33 is used to transmit the voltage signal into the data acquisition module 9.

In addition, the alternating current source module 10, the fundamental frequency signal cancellation circuit 11 and the first matrix switch 13 are all in communication connection with the control module 55, the control module 55 can control the frequency and the amplitude of the output current of the alternating current source module 10, and control the switching of the first matrix switch 13 so that different voltage signals are input into the data acquisition module 9; the direct current/alternating current constant current source module 30, the direct current signal eliminating circuit 31 and the second matrix switch 33 are all in communication connection with the control module 55, and the control module 55 can control the direct current/alternating current constant current source module 30 to output direct current constant current or alternating current constant current with different sizes, and control the switch of the second matrix switch 33 to switch so that different voltage signals are input into the data acquisition module 9.

And, the control module 55 can be used for controlling the measurement flow and recording data, and the control module 55 and the data acquisition module 9 are connected for calculating the film in-plane thermophysical quantity according to the frequency tripling signal and the frequency doubling signal.

Optionally, as shown in fig. 1, 2 and 3, the baseband signal cancellation circuit 11 includes: the first variable resistor 16, the first digital-to-analog conversion chip 19, the first digital output circuit 20, the first amplifier 17 and the second amplifier 18, and the amplification factors of the first amplifier 17 and the second amplifier 18 are the same; the input end of the first amplifier 17 is respectively connected with two ends of the first conductive strip 4; the input end of the second amplifier 18 is connected with two ends of the first variable resistor 16 respectively; the output end of the second amplifier 18 is connected with the first digital-to-analog conversion chip 19; the first digital output circuit 20 is connected with the first digital-to-analog conversion chip 19;

The first differential input of the first secondary amplifier 12 is connected to the output of the first amplifier 17 and to the first input 21 of the first matrix switch 13, respectively; the second differential input terminal of the first secondary amplifier 12 is respectively connected with the first digital-to-analog conversion chip 19 and the third input terminal 23 of the first matrix switch 13; the output of the first secondary amplifier 12 is connected to the second input 22 of the first matrix switch 13;

the dc signal cancellation circuit 31 includes: a second variable resistor 34, a second digital-to-analog conversion chip 37, a second digital output circuit 38, a third amplifier 35, and a fourth amplifier 36; the amplification factors of the third amplifier 35 and the fourth amplifier 36 are the same; the second conductive strip 5 and the second variable resistor 34 are connected in series; the input end of the third amplifier 35 is respectively connected with two ends of the second conductive strip 5; the input end of the fourth amplifier 36 is connected with two ends of the second variable resistor 34 respectively, and the output end of the fourth amplifier 36 is connected with the second digital-to-analog conversion chip 37; the second digital output circuit 38 is connected with the second digital-to-analog conversion chip 37;

The first differential input of the second secondary amplifier 32 is connected to the output of the third amplifier 35 and to the first input 39 of the second matrix switch 33, respectively; the second differential input of the second secondary amplifier 32 is connected to the second digital-to-analog conversion chip 37 and the third input 41 of the second matrix switch 33, respectively; the output of the second secondary amplifier 32 is connected to a second input 40 of the second matrix switch 33.

The first digital-to-analog conversion chip 19 and the first digital output circuit 20 in the baseband signal cancellation circuit 11 are used for adjusting the gain range of the amplified voltage signal of the first variable resistor 16, the first digital output circuit 20 is in communication connection with the control module 55, the control module 55 controls the gain of the first digital-to-analog conversion chip 19, and the first digital output circuit 20 outputs the gain control signal to the first digital-to-analog conversion chip 19.

The principle of the baseband signal cancellation circuit 11 is as follows: the first conductive strip 4 and the first variable resistor 16 are connected in series, two ends of the first conductive strip 4 are connected with the first amplifier 17, and the first amplifier 17 is used for amplifying voltage signals at two ends of the first conductive strip 4 and inputting the voltage signals at two ends of the first conductive strip 4 into a first differential input end of the first secondary amplifier 12; the two ends of the first variable resistor 16 are connected to the second amplifier 18, the second amplifier 18 is configured to amplify the voltage signal of the first variable resistor 16 and input the voltage signal of the two ends of the first variable resistor 16 to the second differential input end of the first secondary amplifier 12, and the output end of the second amplifier 18 is connected to the first digital-to-analog conversion chip 19. The resistance value of the first variable resistor 16 is adjusted to be larger than that of the first conductive strip 4, then the gain of the first digital-to-analog conversion chip 19 is adjusted, so that the amplified fundamental frequency voltage signal of the second differential input end of the first variable resistor 16 input into the first secondary amplifier 12 is close to the amplified fundamental frequency voltage signal of the first conductive strip 4, and when the amplified voltage signal of the first conductive strip 4 and the amplified voltage signal of the first variable resistor 16 are differentially input into the first secondary amplifier 12, the fundamental frequency voltage signal in the first conductive strip voltage signal is eliminated by the voltage signal output by the first secondary amplifier 12, and the elimination of the fundamental frequency voltage signal in the first conductive strip 4 is realized.

The second digital-to-analog conversion chip 37 and the second digital output circuit 38 in the dc signal cancellation circuit 31 are used for adjusting the gain range of the voltage signal of the second variable resistor 34, the second digital output circuit 38 is connected with the control module 55 in a communication manner, the control module 55 controls the gain of the second digital-to-analog conversion chip 37, and the second digital output circuit 38 outputs the gain control signal to the second digital-to-analog conversion chip 37.

The principle of the dc signal cancellation circuit 31 is as follows: the second conductive strip 5 and the second variable resistor 34 are connected in series, two ends of the second conductive strip 5 are connected with the third amplifier 35, and the third amplifier 35 is used for amplifying voltage signals at two ends of the second conductive strip 5 and inputting the voltage signals at two ends of the second conductive strip 5 into the first differential input end of the second secondary amplifier 32; the two ends of the second variable resistor 34 are connected to the fourth amplifier 36, and the fourth amplifier 36 is configured to amplify the voltage signal of the second variable resistor 34 and input the voltage signal of the two ends of the second variable resistor 34 to the second differential input end of the second secondary amplifier 32. The resistance value of the second variable resistor 34 is adjusted to be larger than the resistance value of the second conductive strip 5, and then the gain of the second digital-to-analog conversion chip 37 is set to enable the amplified direct-current voltage signal of the second differential input end of the second secondary amplifier 32 input by the second variable resistor 34 to be close to the amplified direct-current voltage signal of the second conductive strip 5, and when the amplified voltage signal of the second conductive strip 5 and the amplified voltage signal of the second variable resistor 34 are input into the second secondary amplifier 32 in a differential mode, the direct-current voltage signal in the voltage signal of the second conductive strip is eliminated by the voltage signal output by the second secondary amplifier 32, so that the elimination of the direct-current voltage signal in the second conductive strip 5 is realized.

It can be understood that the amplification factor of the first amplifier 17 is the same as that of the second amplifier 18 in the embodiment of the present utility model, so as to synchronously amplify the voltage signals at two ends of the first conductive strip 4 and the voltage signals at two ends of the first variable resistor 16, thereby more accurately eliminating the fundamental frequency voltage signal. And meanwhile, the frequency tripling signal output by the first secondary amplifier 12 is amplified in two stages, so that the accuracy of frequency tripling signal output is improved. The amplification factor of the third amplifier 35 is the same as that of the fourth amplifier 36, so as to synchronously amplify the voltage signal at both ends of the second conductive strip 5 and the voltage signal at both ends of the second variable resistor 34, thereby more accurately eliminating the dc voltage signal. Meanwhile, the frequency doubling signal output by the second secondary amplifier 32 is amplified in two stages, so that the accuracy of frequency doubling signal output is improved.

According to the technical scheme provided by the embodiment of the utility model, the connection relation of the fundamental frequency signal eliminating circuit and the direct current signal eliminating circuit is disclosed, so that the principle of eliminating the fundamental frequency voltage signal and the direct current voltage signal is clarified, and the accurate measurement of the in-plane thermophysical quantity of the film is realized.

Optionally, with continued reference to fig. 1, 2 and 3, the data acquisition module 9 includes a first input 27, a second input 28 and a third input 29;

The first input 27 is connected to a first output of the first matrix switch 13; the second input 28 is connected to the second output of the first matrix switch 13; the third input 29 is connected to the output of the second matrix switch 33.

Wherein, the first input end 27 and the second input end 28 are used for respectively inputting the voltage signals in the frequency tripling signal acquisition box 7 into the data acquisition module 9; the third input 29 is used for inputting the voltage signal in the frequency doubling signal collection box 8 into the data collection module 9.

It will be appreciated that different voltage signals can be brought into the data acquisition module 9 by switching the first matrix switch 13; the switching of the second matrix switch 33 allows different voltage signals to enter the data acquisition module 9. According to the technical scheme, the multiple input ends are arranged in the data acquisition module, so that the frequency tripling signal acquisition box and the frequency doubling signal acquisition box can work simultaneously and input voltage signals into the data acquisition module simultaneously, and the efficiency of measuring the thermal physical quantity in the film plane is improved.

Optionally, as shown with continued reference to fig. 1, 2 and 3, the data acquisition module 9 includes a synchronous data acquisition card or a lock-in amplifying circuit.

Specifically, taking a synchronous data acquisition card as an example, the synchronous data acquisition card comprises a first input end, a second input end and a third input end, wherein the first input end is connected with the second input end 22 of the first matrix switch 13 so as to enable the frequency tripling signal to be output to the synchronous data acquisition card; the second input end is connected with the fourth input end 24 of the first matrix switch 13, so that the reference signal of the sampling resistor 14 is output to the synchronous data acquisition card; the third input is connected to the second input 40 of the second matrix switch 33, so that the frequency-doubled signal is output to the synchronous data acquisition card.

Specifically, taking a lock-in amplifying circuit as an example: the phase-locked amplifying circuit comprises a first sub-phase-locked amplifying circuit and a second sub-phase-locked amplifying circuit, wherein the first sub-phase-locked amplifying circuit comprises a first signal input end, the second sub-phase-locked amplifying circuit comprises a third signal input end, and the second input end is shared by the first sub-phase-locked amplifying circuit and the second sub-phase-locked amplifying circuit as a reference signal input end. The first input end is connected with the second input end 22 of the first matrix switch 13 so that the frequency tripled signal is output to the first sub-phase-locked amplifying circuit, and the second input end is connected with the fourth input end 24 of the first matrix switch 13 so that the fundamental frequency reference signal of the sampling resistor 14 is output to the first sub-phase-locked amplifying circuit and the second sub-phase-locked amplifying circuit; the third input terminal is connected to the second input terminal 40 of the second matrix switch 33, so that the frequency-doubled signal is output to the second sub lock-in amplifying circuit.

According to the technical scheme, the synchronous data acquisition card or the phase-locked amplifying circuit is arranged in the data acquisition module, so that the first alternating current signal acquisition box and the second alternating current signal acquisition box can work simultaneously and input voltage signals into the data acquisition module simultaneously, and the efficiency of measuring the film in-plane thermophysical quantity is improved.

Optionally, fig. 4 is a schematic structural diagram of a first interaction unit of a frequency-tripled signal collection box provided according to an embodiment of the present utility model, and fig. 5 is a schematic structural diagram of a second interaction unit of a frequency-doubled signal collection box provided according to an embodiment of the present utility model, and is shown in conjunction with fig. 1, fig. 2, fig. 3, fig. 4, and fig. 5:

The frequency-tripled signal acquisition box 7 further comprises a first interaction unit;

The first interactive unit comprises a first knob 61, a first panel signal input 62 and a first panel signal output 63;

The first knob 61 is connected with the first variable resistor 16 and is used for adjusting the size of the first variable resistor 16; the first panel signal input port 62 is connected with the wiring end of the first conductive strip 4, and the first matrix switch 13 is connected with the data acquisition module 9 through the first panel signal output port 63;

the frequency doubling signal acquisition box 8 also comprises a second interaction unit;

the second interactive unit comprises a second knob 61, a second panel signal input 62 and a second panel signal output 63;

The second knob 61 is connected with the second variable resistor 34 and is used for adjusting the size of the second variable resistor 34; the second panel signal input 62 is connected to the terminals of the second conductive strip 5 and the second matrix switch 33 is connected to the data acquisition module 9 via the second panel signal output 63.

The first interaction unit may be a panel of the frequency tripling signal collection box 7, the first knob 61 is used for adjusting the size of the first variable resistor 16, the first panel signal input port 62 is connected with the terminal of the first conductive strip 4, and the first panel signal output port 63 is connected with the data collection module 9, so as to realize the input of the voltage signal of the first conductive strip 4 and the output of the frequency tripling signal and other voltage signals.

The second interaction unit may be a panel of the frequency doubling signal collecting box 8, the second knob 61 is used for adjusting the size of the second variable resistor 34, the second panel signal input port 62 is connected with the terminal of the second conductive strip 5, and the second panel signal output port 63 is connected with the data collecting module 9, so as to realize the input of the voltage signal of the second conductive strip 5 and the output of the frequency doubling signal and other voltage signals.

According to the technical scheme provided by the embodiment of the utility model, by arranging the first interaction unit and the second interaction unit, an operator can conveniently realize the collection of the frequency tripling signal, the collection of the frequency doubling signal and other voltage signals through the interaction between the first interaction unit and the second interaction unit, and the measurement efficiency of the film in-plane thermophysical quantity is ensured.

Based on the same inventive concept, the embodiment of the utility model further provides a method for measuring an in-plane thermophysical quantity of a thin film, which is applied to a device for measuring the in-plane thermophysical quantity of the thin film, and fig. 6 is a flowchart of a first method for measuring the in-plane thermophysical quantity of the thin film, provided by the embodiment of the utility model, wherein a first alternating current signal comprises the frequency tripling signal and a fundamental frequency signal; the second ac signal includes the frequency-doubled signal and the dc signal, and as shown in fig. 6 and 3, the method for measuring the in-plane thermophysical quantity of the thin film includes:

S11, acquiring the resistance temperature coefficient of the first conducting strip, the current amplitude of the alternating current source module, the resistance value of the first conducting strip, the resistance value of the first variable resistor, the resistance value of the second conducting strip, the resistance value of the second variable resistor, the film thickness and the interval between the first conducting strip and the second conducting strip.

The self-supporting film surface manufacturing method in the embodiment of the utility model comprises a first conducting strip 4 and a second conducting strip 5 which are parallel, wherein the first conducting strip 4 is used as a heater and a thermometer, and the second conducting strip 5 is used as a thermometer, so that the measurement of the thermophysical quantity is realized.

The current amplitude of the frequency-tripled current source module 10, the resistance value of the first conductive strip 4 and the resistance value of the first variable resistor 16 can be obtained through the frequency-tripled signal collection box 7. Further, the temperature coefficient of resistance of the first conductive strip 4 can be calculated according to the resistance value of the first conductive strip 4 which changes along with the temperature; the frequency doubling signal collection box 8 can obtain the resistance value of the second conductive strip 5 and the resistance value of the second variable resistor 34.

In order to calculate the in-plane thermal conductivity and the in-plane thermal diffusivity of the film, the film thickness and the distance between the first conductive strip 4 and the second conductive strip 5 need to be known, so the film thickness and the distance between the first conductive strip 4 and the second conductive strip 5 are also necessary conditions for calculating the in-plane thermal physical quantity of the film.

S12, adjusting a fundamental frequency signal eliminating circuit according to the resistance value of the first conducting strip and the resistance value of the first variable resistor so as to eliminate the fundamental frequency signal in the first alternating current signal; and adjusting the direct current signal eliminating circuit according to the resistance value of the second conducting strip and the resistance value of the second variable resistor so as to eliminate the direct current signal in the second alternating current signal.

Based on the baseband signal cancellation circuit and the first secondary amplifier 12, a first ac signal is input at a first input terminal of the first secondary amplifier 12, and a baseband signal is input at a second input terminal of the first secondary amplifier 12, so that an output terminal of the first secondary amplifier 12 mainly outputs an amplified frequency tripled signal by using a differential input operation principle of the first secondary amplifier 12, and the baseband signal in the first ac signal is cancelled. Similarly, based on the dc signal cancellation circuit and the second secondary amplifier 32, a second ac signal is input to the first input terminal of the second secondary amplifier 32, and a dc signal is input to the second input terminal of the second secondary amplifier 32, so that the output terminal of the second secondary amplifier 32 mainly outputs an amplified double frequency signal, and the dc signal in the second ac signal is cancelled.

S13, determining the amplitude of the frequency tripling signal and the initial phase of the frequency tripling signal according to the frequency tripling signal; and determining the initial phase of the frequency doubling signal according to the frequency doubling signal.

Wherein the purpose of obtaining the initial phase of the frequency tripled signal and the initial phase of the frequency doubled signal with reference to the excitation current signal is to obtain the temperature fluctuation phases of the first conductive strip 4 and the second conductive strip 5 based on the initial phases.

It can be understood that according to different frequencies and magnitudes of current, different frequency tripled signal amplitude, frequency tripled signal initial phase and frequency doubled signal initial phase can be obtained, and further the in-plane thermal conductivity, in-plane thermal diffusivity and volume heat capacity of the film at the temperature can be calculated.

S14, determining the in-plane thermal conductivity of the film, the in-plane thermal diffusivity of the film and the volume heat capacity of the film according to the temperature coefficient of the resistance of the first conductive strip, the current amplitude of the alternating current source module, the resistance value of the first conductive strip, the frequency tripling signal amplitude, the frequency tripling signal initial phase, the frequency doubling signal initial phase, the film thickness and the distance between the first conductive strip and the second conductive strip.

Specifically, according to the initial phase Φ _3ω of the frequency tripled signal and the initial phase Φ _2ω of the frequency doubled signal, the phases Φ (2ω) ₁ and Φ (2ω) ₂ of the temperature fluctuations on the first conductive strip 4 and the second conductive strip 5, wherein Φ (2ω) ₁＝Φ_3ω+π/2,Φ(2ω)₂＝Φ_2ω can be further obtained. It will be appreciated that inputting currents of the same amplitude but different angular frequencies into the frequency tripled signal collection box will result in the frequency tripled signal amplitude corresponding to the different angular frequency currents, the phase Φ (2ω) ₁ of the temperature fluctuation on the first conductive strip 4 and the phase Φ (2ω) ₂ of the temperature fluctuation on the second conductive strip 5, from which the in-plane thermal conductivity, in-plane thermal diffusivity and volumetric heat capacity of the sample at that temperature are calculated.

According to the technical scheme, the frequency tripling signal acquisition box, the frequency doubling signal acquisition box, the data acquisition module and the control module are arranged in the thin film in-plane thermal physical quantity measurement device, so that the frequency tripling voltage signal on the first conducting strip and the frequency doubling voltage signal on the second conducting strip are obtained simultaneously, interference of fundamental frequency voltage signals and direct current voltage signals is eliminated, the resistance measurement function can be switched conveniently, and efficient and accurate measurement of the thin film in-plane thermal physical quantity is realized. Meanwhile, the frequency tripling signal collecting box also comprises a sampling resistor, and the sampling resistor can be used for realizing current calibration and providing reference signal output.

Optionally, as shown in fig. 1, 2 and 3, the baseband signal cancellation circuit 11 includes: the first variable resistor 16, the first digital-to-analog conversion chip 19, the first digital output circuit 20, the first amplifier 17 and the second amplifier 18, and the amplification factors of the first amplifier 17 and the second amplifier 18 are the same; the first conductive strip 4 and the first variable resistor 16 are connected in series; the input end of the first amplifier 17 is respectively connected with two ends of the first conductive strip 4; the input end of the second amplifier 18 is connected with two ends of the first variable resistor 16 respectively; the output end of the second amplifier 18 is connected with the first digital-to-analog conversion chip 19; the first digital output circuit 20 is connected with the first digital-to-analog conversion chip 19;

When the data acquisition module 9 includes a synchronous data acquisition card, the method for acquiring the current amplitude of the alternating current source module, the resistance value of the first conductive strip, the resistance value of the first variable resistor, the resistance value of the second conductive strip and the resistance value of the second variable resistor is as follows:

Fig. 7 is a flowchart of a first method for obtaining a current amplitude of an ac current source module, a resistance value of a first conductive strip, and a resistance value of a first variable resistor according to an embodiment of the present utility model, as shown in fig. 7:

S20, outputting a first control signal to the alternating current source module so as to control the alternating current source module to output alternating current.

The first control signal is used for controlling the alternating current source module 10 to output current with the angular frequency omega and transmitting the current to the first conductive strip 4, the first variable resistor 16 and the sampling resistor 14.

S21, outputting a second control signal to the first digital output circuit to control the gain of the first digital-to-analog conversion chip to be 1.

The second control signal is output to the first digital output circuit 20, and is used for controlling the gain of the first digital-to-analog conversion chip 19 to be 1, that is, the voltage signal of the first variable resistor 16 is not attenuated, so that the calculated resistance value of the first variable resistor 16 is the actual resistance value.

S22, outputting a third control signal to the first matrix switch so as to control the first matrix switch to sequentially output the first conducting bar voltage signal, the first variable resistance voltage signal and the sampling resistance voltage signal to the synchronous data acquisition card.

The third control signal is used for controlling the switching of the first matrix switch 13, and sequentially controlling the first input end 21, the third input end 23 and the fourth input end 24 of the first matrix switch 13 to output the first conductive strip voltage signal, the first variable resistance voltage signal and the sampling resistance voltage signal to the data acquisition module 9.

S23, performing fast Fourier transform on the first conducting bar voltage signal to obtain the fundamental frequency signal amplitude of the first conducting bar, performing fast Fourier transform on the first variable resistance voltage signal to obtain the fundamental frequency signal amplitude of the first variable resistance, and performing fast Fourier transform on the sampling resistance voltage signal to obtain the fundamental frequency signal amplitude of the sampling resistance.

The data acquisition module 9 acquires a time domain signal of the first conducting bar voltage signal, a time domain signal of the first variable resistor voltage signal and a time domain signal of the sampling resistor voltage signal, and performs fast fourier transform on the signals to obtain a fundamental frequency signal amplitude of the first conducting bar 4, a fundamental frequency signal amplitude of the first variable resistor 16 and a fundamental frequency signal amplitude of the sampling resistor 14.

S24, calculating the current amplitude of the alternating current source module, the resistance value of the first conducting strip and the resistance value of the first variable resistor according to the resistance value of the sampling resistor, the fundamental frequency signal amplitude of the first conducting strip, the fundamental frequency signal amplitude of the first variable resistor and the fundamental frequency signal amplitude of the sampling resistor.

Wherein, since the resistance of the sampling resistor 14 is a known quantity, the current amplitude of the ac current source module 10, the resistance of the first conductive strip 4, and the resistance of the first variable resistor 16 can be calculated according to the fundamental frequency signal amplitude of the first conductive strip 4, the fundamental frequency signal amplitude of the first variable resistor 16, and the fundamental frequency signal amplitude of the sampling resistor 14.

Fig. 8 is a flowchart of a first method for obtaining a resistance value of a second conductive strip and a resistance value of a second variable resistor according to an embodiment of the present utility model, as shown in fig. 8:

s30, outputting a fourth control signal to the direct current/alternating current constant current source module so as to control the direct current/alternating current constant current source module to output a plurality of direct currents with different sizes.

S31, outputting a fifth control signal to the second digital output circuit to control the gain of the second digital-to-analog conversion chip to be 1.

The fourth control signal is used for controlling the dc/ac constant current source module 30 to output a plurality of dc currents with different magnitudes and to transmit the dc currents to the second conductive strip 5 and the second variable resistor 34, so that the voltage of the second conductive strip 5 and the voltage of the second variable resistor 34 under the plurality of dc currents with different magnitudes can be obtained; the fifth control signal is output to the second digital output circuit 38, and controls the gain of the second digital-to-analog conversion chip 37 to be 1, that is, the voltage signal of the second variable resistor 34 is not attenuated, that is, the voltage value of the second variable resistor 34 at this time is a true value without attenuation.

S32, outputting a sixth control signal to the second matrix switch so as to control the second matrix switch to sequentially output a plurality of second conducting bar voltage signals and a plurality of second variable resistance voltage signals to the synchronous data acquisition card.

The switching of the second matrix switch 33 illustrates switching between different loops, and sequentially controls the first input terminal 39 and the third input terminal 41 of the second matrix switch 33 to be communicated with the synchronous data acquisition card, so as to realize outputting a plurality of second conductive strip voltage signals and a plurality of second variable resistance voltage signals to the data acquisition module 9 for subsequent analysis processing of data.

S33, determining a linear fitting curve of the second conducting strip according to a plurality of currents with different sizes and a plurality of voltage signals of the second conducting strip, and determining the resistance value of the second conducting strip according to the linear fitting curve.

S34, determining a linear fitting curve of the second variable resistor according to the currents with different sizes and the voltage signals of the second variable resistor, and determining the resistance value of the second variable resistor according to the linear fitting curve.

The second conducting bar voltage signal is subjected to linear fitting on the current, and the slope after linear fitting is the resistance value of the second conducting bar 5; the second variable resistance voltage signal is linearly fitted to the current, and the slope after the linear fitting is the resistance value of the second variable resistor 34.

When the data acquisition module comprises a phase-locked amplifying circuit, the method for acquiring the current amplitude of the alternating current source module, the resistance value of the first conducting strip and the resistance value of the first variable resistor is as follows:

Fig. 9 is a flowchart of a second method for obtaining a current amplitude of an ac current source module, a resistance value of a first conductive strip, and a resistance value of a first variable resistor according to an embodiment of the present utility model, as shown in fig. 9:

S40, outputting a seventh control signal to the alternating current source module so as to control the alternating current source module to output alternating current.

S41, outputting an eighth control signal to the first digital output circuit to control the gain of the first digital-to-analog conversion chip to be 1.

S42, outputting a ninth control signal to the first matrix switch so as to control the first matrix switch to sequentially output the first conducting bar voltage signal, the first variable resistance voltage signal and the sampling resistance voltage signal to the phase-locked amplifying circuit.

S43, processing the first conducting strip voltage signal by using a phase-locked amplifying circuit to determine the fundamental frequency signal amplitude of the first conducting strip, processing the first variable resistance voltage signal to determine the fundamental frequency signal amplitude of the first variable resistance, and processing the sampling resistance voltage signal to obtain the fundamental frequency signal amplitude of the sampling resistance.

The data acquisition module 9 is a phase-locked amplifying circuit, so that the signal amplitude is not required to be obtained in a fourier transform mode, and the fundamental frequency signal amplitude of the first conductive strip 4, the fundamental frequency signal amplitude of the first variable resistor 16 and the fundamental frequency signal amplitude of the sampling resistor 14 can be directly obtained by adopting a phase-locked technology.

S44, calculating the current amplitude of the alternating current source module, the resistance value of the first conductive strip and the resistance value of the first variable resistor according to the resistance value of the sampling resistor, the fundamental frequency signal amplitude of the first conductive strip, the fundamental frequency signal amplitude of the first variable resistor and the fundamental frequency signal amplitude of the sampling resistor.

Similarly, when the lock-in amplifying circuit is disposed in the data acquisition module 9, the dc/ac constant current source 30 can be controlled to output an ac current with a constant magnitude to the second conductive strip 5 and the second variable resistor 34, and the gain of the second dac chip 37 is controlled to be 1. And controlling the second matrix switch to sequentially output the second conducting bar voltage signal and the second variable resistance voltage signal to the phase-locked amplifying circuit. And processing the second conducting strip voltage signal by using a phase-locked amplifying circuit to determine the fundamental frequency signal amplitude of the second conducting strip and calculate the resistance value of the second conducting strip, and processing the second variable resistance voltage signal to determine the fundamental frequency signal amplitude of the second variable resistor and calculate the resistance value of the second variable resistor.

According to the technical scheme, the synchronous data acquisition card mode or the phase-locked amplifying circuit mode is adopted, and the frequency-tripled signal acquisition box and the frequency-doubled signal acquisition box are matched, so that the resistance value of the first conducting strip, the resistance value of the second conducting strip, the resistance value of the first variable resistor and the resistance value of the second variable resistor can be directly measured, and the frequency-tripled signal acquisition box and the frequency-doubled signal acquisition box have the function of measuring frequency-tripled signals and frequency-doubled signals and the function of measuring the resistance.

In some embodiments, fig. 10 is a flowchart of a method for removing a baseband signal according to an embodiment of the present utility model, as shown in fig. 10 and fig. 3, where the method includes:

And S50, adjusting the resistance value R _br of the first variable resistor to be larger than the resistance value R _Q1 of the first conducting strip, and determining a first attenuation proportion R _Q1/R_br according to the resistance value R _br of the first variable resistor and the resistance value R _Q1 of the first conducting strip.

The principle of eliminating the fundamental frequency signal is to cancel the fundamental frequency signal in the first conductive strip voltage signal, so that the attenuation ratio needs to be determined according to the first variable resistance value R _br and the first conductive strip resistance value R _Q1, so that the amplitude of the attenuated first variable resistance fundamental frequency voltage signal is the same as the amplitude of the fundamental frequency component in the first conductive strip voltage signal.

S51, outputting a tenth control signal to the first digital output circuit according to the first attenuation ratio R _Q1/R_br so as to adjust the gain of the first digital-to-analog conversion chip, so that the amplitude of the fundamental frequency component of the attenuated voltage signal of the first variable resistor is the same as the amplitude of the fundamental frequency component of the first alternating current signal, and the fundamental frequency signal in the first alternating current signal is eliminated by time difference when the first variable resistor is input into the first secondary amplifier.

When the attenuated amplified voltage signal of the first variable resistor 16 and the amplified voltage signal of the first conductive strip 4 are differentially input to the first secondary amplifier 12, the fundamental frequency voltage signal of the first variable resistor 16 and the fundamental frequency voltage signal component of the first conductive strip 4 are offset to the greatest extent.

Fig. 11 is a flowchart of a method for eliminating a dc signal according to an embodiment of the present utility model, and in combination with fig. 11 and fig. 3, the method includes:

And S60, adjusting the resistance value R _ar of the second variable resistor to be larger than the resistance value R _Q2 of the second conductive strip, and determining a second attenuation proportion R _Q2/R_ar according to the resistance value R _ar of the second variable resistor and the resistance value R _Q2 of the second conductive strip.

The principle of eliminating the dc signal is to cancel the dc signal in the second conductive bar voltage signal, so that the attenuation ratio needs to be determined according to the second variable resistance value R _ar and the second conductive bar resistance value R _Q2, so that the amplitude of the attenuated second variable resistance dc voltage signal is the same as the amplitude of the dc component in the second conductive bar voltage signal.

And S61, controlling the second digital output circuit according to the second attenuation proportion R _Q2/R_ar to adjust the gain of the second digital-to-analog conversion chip so that the direct current component of the attenuated voltage signal of the second variable resistor is the same as the direct current component of the second alternating current signal, and eliminating the direct current signal in the second alternating current signal in a differential mode when the attenuated voltage signal is input into the second secondary amplifier.

When the attenuated amplified voltage signal of the second variable resistor 34 and the amplified voltage signal of the second conductive strip 5 are differentially input to the second secondary amplifier 32, the dc voltage signal of the second variable resistor 34 and the dc voltage signal component of the second conductive strip 5 are offset to the greatest extent, so that the output signal of the second secondary amplifier 32 is prevented from exceeding the range of the data acquisition module 9.

According to the technical scheme, the first variable resistor and the second variable resistor are adjusted, and the gain of the first digital-to-analog conversion chip and the gain of the second digital-to-analog conversion chip are adjusted, so that the fundamental frequency signal in the first alternating current signal passing through the first secondary amplifier is counteracted, and the direct current signal in the second alternating current signal passing through the second secondary amplifier is counteracted, so that an accurate frequency tripling signal and frequency doubling signal are obtained, and the accuracy of the film in-plane thermal physical quantity measuring device is improved.

In some embodiments, fig. 12 is a flowchart of a method for obtaining a frequency-tripled signal amplitude, a frequency-tripled signal initial phase, and a frequency-tripled signal initial phase according to an embodiment of the present utility model, where the method includes:

And S70, the input end of the control synchronous data acquisition card is respectively connected with the second input end of the first matrix switch, the fourth input end of the first matrix switch and the second input end of the second matrix switch.

The first input end 27 of the synchronous data acquisition card is connected with the second input end 22 of the first matrix switch 13, so that the frequency tripled signal amplified by the first secondary amplifier 12 is continuously input into the synchronous data acquisition card; the third input end 29 of the control synchronous data acquisition card is connected with the second input end 40 of the second matrix switch 33, so that the frequency doubling signal amplified by the second secondary amplifier 32 is continuously input into the synchronous data acquisition card; the second input 28 of the control synchronization data acquisition card is connected to the fourth input 24 of the first matrix switch 13, so that the fundamental frequency voltage signal of the sampling resistor 14 can be continuously input as a reference signal into the synchronization data acquisition card.

It will be appreciated that, in order to ensure phase consistency, the fundamental frequency signal and the frequency tripled signal of the sampling resistor must be acquired synchronously, and the fundamental frequency signal and the frequency doubled signal of the sampling resistor must also be acquired synchronously. In order to improve the measurement efficiency, the fundamental frequency signal, the frequency tripling signal and the frequency doubling signal of the sampling resistor can be synchronously acquired.

And S71, controlling the alternating current source module to output a plurality of currents with different angular frequencies and controlling the direct current/alternating current constant current source module to output constant direct current.

In the measuring device provided by the embodiment of the utility model, the first conducting strip 4 is used as a heater and a thermometer, and the second conducting strip 5 is used as a thermometer, so that a plurality of currents with constant amplitude and different angular frequencies are only output to the first conducting strip 4 to generate temperature fluctuation, and the temperature fluctuation information of the first conducting strip 4 can be obtained by measuring the frequency-tripled voltage signal led out from the first conducting strip 4; a constant direct current is output to the second conductive strip 5, and temperature fluctuation information of the second conductive strip 5 can be obtained by measuring a frequency-doubled voltage signal derived from the second conductive strip 5.

S72, the control data acquisition module synchronously receives the plurality of first secondary amplifier voltage signals, the plurality of sampling resistor voltage signals and the plurality of corresponding second secondary amplifier voltage signals.

S73, determining the amplitude of a plurality of frequency tripled signals and the real-time phase of the frequency tripled signals by the voltage signals of the first secondary amplifiers through fast Fourier transformation; determining real-time phases of the fundamental frequency voltage signals of the sampling resistors by performing fast Fourier transform on the sampling resistor voltage signals; the amplitudes of the multiple frequency doubling signals and the real-time phases of the multiple frequency doubling signals are determined by the voltage signals of the multiple second secondary amplifiers through fast Fourier transformation.

The voltage signal of the first secondary amplifier is subjected to data processing to obtain the amplitude of the corresponding frequency tripling signal and the real-time phase of the frequency tripling signal under different angular frequencies; performing data processing on the plurality of sampling resistor voltage signals to obtain real-time phases of corresponding sampling resistor fundamental frequency voltage signals under different angular frequencies; and carrying out data processing on the voltage signal of the second-stage amplifier to obtain the amplitude of the corresponding frequency doubling signal and the real-time phase of the frequency doubling signal under different angular frequencies.

S74, determining initial phases of the multiple frequency tripling signals according to the real-time phases of the multiple frequency tripling signals and the corresponding real-time phases of the multiple sampling resistor fundamental frequency voltage signals; and determining the initial phases of the multiple frequency doubling signals according to the real-time phases of the multiple frequency doubling signals and the real-time phases of the corresponding multiple sampling resistor fundamental frequency voltage signals.

In some embodiments, Φ _3ω＝Φ_3ω,A-mod(f_3ω×T₀ × 360,360 is satisfied between the initial phase Φ _3ω of the frequency tripled signal, the real-time phase Φ _Ref of the sampling resistor fundamental frequency signal, and the real-time phase Φ _3ω,A of the frequency tripled signal, where T ₀＝Φ_Ref/(360×f_1ω),f_1ω＝ω/(2π),f_3ω =3ω/(2pi); the sampling resistor fundamental frequency signal and the frequency tripling signal are synchronously collected;

The initial phase phi _2ω of the double frequency signal, the real-time phase phi _Ref of the sampling resistor fundamental frequency signal and the real-time phase phi _2ω,A of the double frequency signal meet phi _2ω＝Φ_2ω,A-mod(f_2ω×T₀ multiplied by 360,36) 0, wherein T ₀＝Φ_Ref/(360×f_1ω),f_1ω＝ω/(2π),f_2ω = 2 omega/(2 pi); the sampling resistor fundamental frequency signal and the frequency doubling signal are synchronously collected.

The technical scheme of the embodiment of the utility model provides a mode for measuring the initial phase of the frequency-tripling signal and the initial phase of the frequency-doubling signal, and by adopting the measuring method, a lock-in amplifier or other hardware such as a trigger circuit, a reference signal source and the like are not required to be used when weak alternating current signals are measured, so that the compact layout of the whole structure of the instrument is realized, and the cost of a measuring device is greatly reduced.

Based on the same inventive concept, the embodiment of the present utility model further provides a system for measuring an in-plane thermophysical quantity of a thin film, and fig. 13 is a schematic diagram of a system for measuring an in-plane thermophysical quantity of a thin film according to an embodiment of the present utility model, and in combination with fig. 13 and fig. 3, the system includes: the temperature control device comprises a control module 55, a vacuum sample chamber 56, a temperature controller 58, a chip thermometer 59, a vacuum thermometer 60, a frequency tripling signal collection box 7, a frequency doubling signal collection box 8, a data collection module 9, a sample seat 43 and a temperature change sample rod 57.

Wherein, the sample to be measured is mounted on the sample holder 43, and the temperature-changing sample rod 57 is used for fixing the sample holder 43 and is arranged in the vacuum sample chamber 56. Four terminals on the first conductive strip 4 are connected with a frequency doubling signal collection box 7, and four terminals on the second conductive strip 5 are connected with a frequency doubling signal collection box 8.

The data acquisition module adopts a synchronous data acquisition card. In the frequency-tripled signal acquisition box 7 and the frequency-doubled signal acquisition box 8, the amplification factors of the first amplifier 17, the second amplifier 18, the third amplifier 35, and the fourth amplifier 36 are 10 times; the amplification of the first secondary amplifier 12 and the second secondary amplifier 32 is 100 times.

The working process of the system is as follows:

step 1, vacuuming the vacuum sample chamber 56.

And 2, changing the temperature of the sample holder 43, measuring the change of the resistance of the first conductive strip 4 along with the temperature in an expected measurement temperature zone by using the frequency tripling signal acquisition box 7, and calculating the temperature coefficient of resistance beta ₁ of the first conductive strip 4.

Step 3, setting the size of a first variable resistor 16 in the frequency-tripling signal acquisition box 7 to enable the resistance value of the first variable resistor to be slightly larger than the maximum resistance value of the first conducting strip 4 in the expected measurement temperature range; the second variable resistor 34 on the doubling signal collection box 8 is sized to be slightly larger than the maximum resistance of the second conductive strip 5 in the desired measurement temperature range.

When the temperature of the sample is balanced at a certain value T ₀, the control module 55 measures the resistance R _br of the first variable resistor 16 and the resistance R _Q1 of the first conductive strip 4 according to the frequency tripling signal acquisition box 7, and calculates the proportion of R _Q1/R_br at the temperature; the control module 55 measures the resistance R _ar of the second variable resistor 34 and the resistance R _Q2 of the second conductive strip 5 according to the frequency doubling signal collection box 8, and calculates the ratio of R _Q2/R_ar at that temperature.

In step 4, the control module 55 sets the output gains of the first dac chip 19 and the second dac chip 37 according to the values of R _Q1/R_br and R _Q2/R_ar, respectively.

And 5, the control module 55 controls the alternating current source 10 in the frequency doubling signal collection box 7 to input sinusoidal alternating current with certain amplitude and angular frequency to the first conductive strip 4, and controls the direct current/alternating current constant current source 30 in the frequency doubling signal collection box 8 to input direct current with the amplitude of I _D to the second conductive strip 5.

The control module 55 collects the real-time phase of the frequency tripled signal amplitude |v _3ω | and the frequency tripled signal obtained from the first conductive strip 4, the real-time phase of the fundamental frequency voltage signal obtained from the sampling resistor 14 and the real-time phase of the frequency doubled signal obtained from the second conductive strip 5;

The initial phase Φ _3ω of the frequency tripled signal and the initial phase Φ _2ω of the frequency doubled signal with the excitation current I (t) =i ₀ sin (ωt) as a reference are calculated, and the phases Φ (2ω) ₁ and Φ (2ω) ₂ of the temperature fluctuation on the first conductive strip 4 and the second conductive strip 5 are further obtained, wherein Φ (2ω) ₁＝Φ_3ω+π/2,Φ(2ω)₂＝Φ_2ω.

And 6, changing the angular frequency omega of the exciting current to obtain a series of |V _3ω|、Φ(2ω)₁ and phi (2 omega) ₂ corresponding to different frequencies.

And 7, calculating the in-plane thermal conductivity, the in-plane thermal diffusivity and the volumetric heat capacity of the sample at the temperature.

The following are data measured based on the above steps:

Fig. 14 is a trend graph of the frequency-tripled signal amplitude of the first conductive strip in the thin film according to the embodiment of the present utility model, fig. 15 is a trend graph of the temperature fluctuation phase of the first conductive strip and the second conductive strip in the thin film according to the embodiment of the present utility model, wherein the trend graph of the frequency-tripled signal amplitude |v _3ω | of the 83.5nm silicon nitride thin film sample measured at room temperature, the phase Φ (2ω) ₁ of the temperature fluctuation of the first conductive strip 4, and the phase Φ (2ω) ₂ of the temperature fluctuation of the second conductive strip 5 are respectively shown in fig. 14 and 15, and the trend of the temperature fluctuation phase varies with the excitation current frequency f (f=ω/2pi).

It can be understood that the exciting current is the current output by the ac current source module, and the detecting current is the dc current output by the dc/ac current source module. In the embodiment of the utility model, the excitation current amplitude is I ₀ =0.10 mA (RMS unit), and the detection current amplitude is I _DC =0.10 mA. As shown in connection with fig. 14 and 15, the measured frequency tripled signal amplitude was less than 100 μv, and the experimental data were very smooth.

Further, calculateAnd a value of M (2ω) ·n (2ω), wherein N (2ω) = [ Φ (2ω) ₁-Φ(2ω)₂]/D,M(2ω)＝N(2ω)/tan(3π/2-Φ(2ω)₁, where D is a distance between the first conductive bar 4 and the second conductive bar 5, and M (2ω) and N (2ω) are intermediate amounts calculated from the temperature fluctuation phases Φ (2ω) ₁ and Φ (2ω) ₂.

Further, the temperature fluctuation amplitude |Δt ₁ | of the first conductive strip 4 corresponding to the excitation current of each different frequency is calculated from β ₁ and |v _3ω |, whereinR _S1 is the resistance of the first conductive strip 4.

FIG. 16 is a schematic illustration of a film according to an embodiment of the present utility modelA schematic diagram of the measurement results as a function of the temperature fluctuation amplitude |Δt ₁ | of the first conductive strip as shown in FIG. 16And (3) drawing the |delta T ₁ | to obtain a straight line, and calculating the in-plane thermal conductivity kappa _|| of the film sample to be measured to be 2.16Wm ^-1K^-1(κ_||＝P_LK₁/2 d according to the slope K ₁ of the fitted straight line, wherein P _L is the alternating current heating power amplitude of the first conductive strip per unit length, and d is the film thickness.

Fig. 17 is a schematic diagram of measurement results of angular frequency ω of excitation current in a thin film according to an embodiment of the present utility model as a function of M (2ω). N (2ω), as shown in fig. 17, by plotting ω versus M (2ω). N (2ω) to obtain a straight line, and using straight line fitting data passing through an origin, obtaining an in-plane thermal diffusivity α _|| of a thin film sample of 1.09×10 ^-6m² s^-1(α_||＝K₂, where K ₂ is a slope of the fitting straight line), and a volumetric heat capacity C _v of 1.99×10 ⁶Jm^-3K^-1(C_v＝κ_||/α_|| of the sample.

It should be appreciated that various forms of the flows shown above may be used to reorder, add, or delete steps. For example, the steps described in the present utility model may be performed in parallel, sequentially, or in a different order, so long as the desired results of the technical solution of the present utility model are achieved, and the present utility model is not limited herein.

The above embodiments do not limit the scope of the present utility model. It will be apparent to those skilled in the art that various modifications, combinations, sub-combinations and alternatives are possible, depending on design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included in the scope of the present utility model.

Claims

1. A device for measuring in-plane thermal physical quantity of a thin film, which is applied to measurement of in-plane thermal conductivity, measurement of in-plane thermal diffusivity and measurement of volumetric heat capacity of a self-supporting thin film, the device for measuring in-plane thermal physical quantity of a thin film comprising:

The frequency tripling signal acquisition box comprises an alternating current source module, a fundamental frequency signal elimination circuit, a first secondary amplifier, a first matrix switch and a sampling resistor; the frequency tripling signal acquisition box is used for acquiring frequency tripling signals;

The alternating current source module is connected with a first conducting bar, the first conducting bar is connected with the fundamental frequency signal eliminating circuit, the fundamental frequency signal eliminating circuit is connected with the first secondary amplifier, the first secondary amplifier is connected with the first matrix switch, and the first matrix switch is connected with the data acquisition module; the sampling resistor is respectively connected with the first conducting strip and the first matrix switch;

The direct current/alternating current constant current source module is connected with a second conducting bar, the second conducting bar is connected with the direct current signal eliminating circuit, the direct current signal eliminating circuit is connected with the second secondary amplifier, the second secondary amplifier is connected with the second matrix switch, and the second matrix switch is connected with the data acquisition module;

the alternating current source module, the fundamental frequency signal elimination circuit and the first matrix switch are all in communication connection with the control module; the direct current/alternating current constant current source module, the direct current signal eliminating circuit and the second matrix switch are all in communication connection with the control module;

The control module is connected with the data acquisition module and is used for calculating the film in-plane thermophysical quantity according to the frequency tripling signal and the frequency doubling signal.

2. The measurement device of claim 1, wherein the baseband signal cancellation circuit comprises: the digital-to-analog conversion circuit comprises a first variable resistor, a first digital-to-analog conversion chip, a first digital output circuit, a first amplifier and a second amplifier, wherein the amplification factors of the first amplifier and the second amplifier are the same; the first conductive strip and the first variable resistor are connected in series; the input end of the first amplifier is connected with two ends of the first conducting strip respectively; the input end of the second amplifier is respectively connected with the two ends of the first variable resistor; the output end of the second amplifier is connected with the first digital-to-analog conversion chip; the first digital output circuit is connected with the first digital-to-analog conversion chip;

The frequency tripling signal acquisition box further comprises a sampling resistor amplifier; the input end of the sampling resistor amplifier is respectively connected with two ends of the sampling resistor, and the output end of the sampling resistor amplifier is connected with the fourth input end of the first matrix switch;

The direct current signal cancellation circuit includes: the second variable resistor, the second digital-to-analog conversion chip, the second digital output circuit, the third amplifier and the fourth amplifier have the same amplification factor; the second conductive strip is connected in series with the second variable resistor; the input end of the third amplifier is respectively connected with two ends of the second conducting strip; the input end of the fourth amplifier is respectively connected with the two ends of the second variable resistor; the output end of the fourth amplifier is connected with the second digital-to-analog conversion chip; the second digital output circuit is connected with the second digital-to-analog conversion chip;

3. The measurement device of claim 1, wherein the data acquisition module comprises a first input, a second input, and a third input;

4. The measurement device of claim 2, wherein the data acquisition module comprises a synchronous data acquisition card or a lock-in amplification circuit.

5. The measurement device of claim 2, wherein the frequency tripled signal acquisition bin further comprises a first interaction unit;

The first knob is connected with the first variable resistor and is used for adjusting the size of the first variable resistor; the first panel signal input port is connected with the wiring end of the first conducting strip, and the first matrix switch is connected with the data acquisition module through the first panel signal output port;

The frequency doubling signal acquisition box further comprises a second interaction unit;

The second knob is connected with the second variable resistor and is used for adjusting the size of the second variable resistor; the second panel signal input port is connected with the wiring end of the second conductive strip, and the second matrix switch is connected with the data acquisition module through the second panel signal output port.