Method and device for measuring copper layer thickness of copper-aluminum composite board through electromagnetic ultrasonic resonance method

Abstract

The invention relates to a method for measuring the thickness of a copper layer of a copper-aluminum composite board based on an electromagnetic ultrasonic resonance frequency spectrum, and belongs to the technical field of nondestructive testing. The method comprises the following steps: acquiring a plurality of material parameters of the copper-aluminum composite board; applying a continuous frequency sweeping excitation signal to the copper-aluminum composite board through an electromagnetic ultrasonic probe, exciting ultrasonic transverse waves and receiving a response signal to generate an amplitude-frequency response curve; extracting a plurality of resonance peak frequencies from the amplitude-frequency response curve to serve as input resonance frequencies; establishing a thickness inversion transcendental equation based on the plurality of material parameters and the input resonant frequency; and solving the inversion transcendental equation based on a Brench algorithm to output the copper layer thickness. The invention further provides a measuring device for implementing the method. The method effectively solves the problem of signal aliasing caused by interface reflection interference in a multi-layer structure in a traditional echo method for thickness measurement, and is suitable for accurate extraction of single-layer thickness in a complex composite structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nondestructive testing, in particular to a method and device for measuring the thickness of a copper layer of a copper-aluminum composite plate by electromagnetic ultrasonic resonance. BACKGROUND

[0002] Copper-aluminum composite plates are widely used in the fields of electronics, construction and aviation due to their excellent electrical conductivity, thermal conductivity and corrosion resistance. In order to realize real-time quality control and process monitoring in the production process, it is very important to use a fast nondestructive method to measure the thickness of the copper-aluminum composite plate. At present, the measurement of the thickness of single-layer metal materials based on ultrasonic methods mainly uses piezoelectric ultrasonic or electromagnetic ultrasonic methods, and electromagnetic ultrasonic can realize non-contact online thickness measurement in high-temperature environments. The electromagnetic acoustic transducer (EMAT) has become a research hotspot in recent years due to its non-contact, high sensitivity and suitability for conductive materials.

[0003] The method for measuring the thickness of single-layer materials based on electromagnetic ultrasonic generally includes two approaches: pulse echo method and resonance method. The pulse echo method is mainly used to measure the thickness of thick materials and has the advantages of intuitive and wide application range; while the resonance method is suitable for accurate measurement of thin samples by obtaining the resonance spectrum of the material and combining the mathematical relationship between the resonance frequency and the thickness. However, for double-layer structure materials such as copper-aluminum composite plates, due to the significant acoustic impedance difference and complex wave propagation characteristics of the internal multi-layer interface, conventional non-contact nondestructive testing methods are prone to problems such as echo aliasing and spectrum interference during measurement, making it difficult to accurately separate and independently measure the thickness of each component layer.

[0004] Therefore, the existing technology still faces great challenges in the precise extraction of the thickness of single layers of multi-layer composite materials, and there is an urgent need to develop a new detection method that combines non-contact, high precision and layer identification capability. SUMMARY

[0005] In order to solve the problems existing in the measurement of the thickness of each component layer of the double-layer metal material of the copper-aluminum composite plate in the prior art, the embodiments of the present application provide a method and device for measuring the thickness of the copper layer of the copper-aluminum composite plate by electromagnetic ultrasonic resonance. The technical solution is as follows:

[0006] On the one hand, a method for measuring the thickness of the copper layer of the copper-aluminum composite plate by electromagnetic ultrasonic resonance is provided, which comprises:

[0007] S1, obtaining a plurality of material parameters of the copper-aluminum composite plate;

[0008] S2, applying a continuous frequency sweeping excitation signal to the copper-aluminum composite plate through an ultrasonic probe to excite ultrasonic transverse waves and receive a response signal to generate an amplitude-frequency response curve;

[0009] S3 extracts multiple resonant peak frequencies from the amplitude-frequency response curve to serve as the input resonant frequencies.

[0010] S4 establishes a thickness inversion transcendental equation based on multiple material parameters and input resonant frequencies;

[0011] S5 uses the Brent algorithm to solve the inversion transcendental equations to output the copper layer thickness.

[0012] In some implementations, in S4, the thickness inversion transcendental equation is:

[0013]

[0014] Where ρ1 and ρ2 are the densities of copper and aluminum, respectively, c1 and c2 are the transverse wave sound velocities of copper and aluminum, respectively, f is the resonant frequency, and the overall thickness of the composite plate is obtained by measurement, with copper layer thickness d1 and aluminum layer thickness d2.

[0015] In some implementations, in S5, solving the inversion transcendental equation based on the Brent algorithm to output the copper layer thickness includes:

[0016] The marked inversion transcendental equation may produce singular intervals of numerical divergence within the domain of copper layer thickness;

[0017] The feasible solution range is defined based on the copper layer design thickness range, excluding singular regions and solutions with non-physical thickness;

[0018] Within the feasible solution interval, the initial iteration points are generated using the bisection method, and then the zeros of the equation are approximated by inverse interpolation.

[0019] When the iterative solution is located in the singular region or exceeds the feasible solution region, the abnormal solution is removed. The remaining thickness solutions that satisfy the physical constraints are then arithmetically averaged to output the final copper layer thickness.

[0020] In some embodiments, in S1, multiple material parameters include: copper layer density, aluminum layer density, copper transverse wave velocity, aluminum transverse wave velocity, and overall thickness of the composite plate.

[0021] In some implementations, in S3, there are 2 to 10 resonant peak frequencies.

[0022] On the other hand, a measuring device for measuring the copper layer thickness of a copper-aluminum composite plate using the electromagnetic ultrasonic resonance method is provided. This device is applied to the method of measuring the copper layer thickness of a copper-aluminum composite plate using the electromagnetic ultrasonic resonance method. The device includes:

[0023] Data acquisition computer, signal triggering and acquisition module, radio frequency pulse generator, duplexer, ultrasonic probe, and signal receiving amplifier;

[0024] The ultrasonic probe is connected to the duplexer;

[0025] The input of the duplexer is connected to an RF pulse generator, and the output is connected to an ultrasonic probe to isolate the excitation signal from the echo signal.

[0026] The output of the signal triggering and acquisition module is connected to an RF pulse generator, and the input is connected to a signal receiving amplifier.

[0027] The data acquisition computer is connected to the signal triggering and acquisition module to control the frequency sweep excitation and acquire and process the resonant spectrum data to calculate the copper layer thickness.

[0028] In some implementations, the ultrasonic probe includes a butterfly coil and a permanent magnet, and the ultrasonic probe excites ultrasonic transverse waves onto the surface of the copper-aluminum composite plate under test in a non-contact manner and receives the reflected echo signal.

[0029] In some implementations, the distance between the ultrasonic probe and the sample is 0.1-1 mm.

[0030] In some implementations, the data acquisition computer includes:

[0031] The frequency sweep control module is used to generate linear frequency modulation signal parameters and send them to the radio frequency pulse generator;

[0032] The resonance peak extraction module is used to process the acquired signal and identify the extreme points of the amplitude-frequency curve;

[0033] The thickness inversion module is used to solve the transcendental equations based on the Brent algorithm and output the copper layer thickness value.

[0034] The beneficial effects of the technical solutions provided by the embodiments of the present invention include at least the following:

[0035] This invention establishes a mathematical model relating the thickness of each component layer and its resonant frequency in a double-layer material based on the physical laws governing ultrasonic wave propagation and its boundary conditions. By performing frequency sweep testing on a copper-aluminum composite plate, its resonant spectrum information is obtained. Combined with the established theoretical model, the actual thickness of the copper layer is calculated, thus achieving non-contact, high-precision measurement of the copper layer thickness in the copper-aluminum composite plate. This method effectively solves the signal aliasing problem caused by interface reflection interference in multi-layer structures using traditional echo methods and is suitable for the accurate extraction of single-layer thickness in complex composite structures. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a flowchart of a method for measuring the copper layer thickness of a copper-aluminum composite plate using electromagnetic ultrasonic resonance, provided in an embodiment of the present invention.

[0038] Figure 2 This is a schematic diagram of a magnetic ultrasonic resonance method for measuring the copper layer thickness of a copper-aluminum composite plate, provided in an embodiment of the present invention.

[0039] Figure 3 The transverse wave resonance spectrum of the copper-aluminum composite plate provided in this embodiment of the invention;

[0040] Figure 4 This is a comparison chart of the calculated thickness and the actual value at different resonant frequencies provided in the embodiments of the present invention.

[0041] Figure label:

[0042] 1. Data acquisition computer; 2. Signal triggering and acquisition module; 3. Radio frequency pulse generator; 4. Duplexer; 5. Ultrasonic probe; 6. Test sample; 7. Signal receiving amplifier. Detailed Implementation

[0043] The technical solution of the present invention will now be described with reference to the accompanying drawings.

[0044] In embodiments of the present invention, words such as "exemplarily," "for example," etc., are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" in the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the word "exemplary" is intended to present the concept in a concrete manner. Furthermore, in embodiments of the present invention, the meaning expressed by "and / or" can be both, or either one.

[0045] In the embodiments of this invention, the terms "image" and "picture" may sometimes be used interchangeably. It should be noted that, without emphasizing the distinction between them, their intended meanings are consistent. Similarly, the terms "of," "corresponding (relevant)," and "corresponding" may sometimes be used interchangeably. It should be noted that, without emphasizing the distinction between them, their intended meanings are consistent.

[0046] In this embodiment of the invention, sometimes a subscript such as W1 may be mistakenly written as a non-subscript form such as W1. When the difference is not emphasized, the meaning they express is the same.

[0047] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0048] This invention provides a method for measuring the copper layer thickness of a copper-aluminum composite plate using electromagnetic ultrasonic resonance, such as... Figure 1 The flowchart shown illustrates a method for measuring the copper layer thickness of a copper-aluminum composite plate using electromagnetic ultrasonic resonance. This method's processing flow may include the following steps:

[0049] S1 obtains multiple material parameters of the copper-aluminum composite plate;

[0050] S2 applies a continuous sweep frequency excitation signal to the copper-aluminum composite plate through an ultrasonic probe, excites ultrasonic transverse waves and receives response signals to generate an amplitude-frequency response curve.

[0051] S3 extracts multiple resonant peak frequencies from the amplitude-frequency response curve to serve as the input resonant frequencies.

[0052] S4 establishes a thickness inversion transcendental equation based on multiple material parameters and input resonant frequencies;

[0053] S5 uses the Brent algorithm to solve the inversion transcendental equations to output the copper layer thickness.

[0054] Furthermore, in S1, several material parameters include: copper layer density, aluminum layer density, copper transverse wave velocity, aluminum transverse wave velocity, and overall thickness of the composite plate.

[0055] Furthermore, in S3, there are 2 to 10 resonant peak frequencies.

[0056] Furthermore, in S4, the thickness inversion transcendental equation is:

[0057]

[0058] Where ρ1 and ρ2 are the densities of copper and aluminum, respectively, c1 and c2 are the transverse wave sound velocities of copper and aluminum, respectively, f is the resonant frequency, and the overall thickness of the composite plate is obtained by measurement, with copper layer thickness d1 and aluminum layer thickness d2.

[0059] Furthermore, in S5, solving the inversion transcendental equations based on the Brent algorithm to output the copper layer thickness includes:

[0060] The marked inversion transcendental equation may produce singular intervals of numerical divergence within the domain of copper layer thickness;

[0061] The feasible solution range is defined based on the copper layer design thickness range, excluding singular regions and solutions with non-physical thickness;

[0062] Within the feasible solution interval, the initial iteration points are generated using the bisection method, and then the zeros of the equation are approximated by inverse interpolation.

[0063] When the iterative solution is located in the singular region or exceeds the feasible solution region, the abnormal solution is removed. The remaining thickness solutions that satisfy the physical constraints are then arithmetically averaged to output the final copper layer thickness.

[0064] Figure 2 This is a block diagram of an apparatus for measuring the copper layer thickness of a copper-aluminum composite plate using an electromagnetic ultrasonic resonance method, according to an exemplary embodiment. The apparatus includes:

[0065] The data acquisition computer (1), signal triggering and acquisition module (2), radio frequency pulse generator (3), duplexer (4), ultrasonic probe (5), and signal receiving amplifier (7);

[0066] The ultrasonic probe (5) is connected to the duplexer (4) and excites ultrasonic transverse waves onto the surface of the test sample (6) in a non-contact manner, and receives the reflected echo signal;

[0067] The input end of the duplexer (4) is connected to the radio frequency pulse generator (3), and the output end is connected to the ultrasonic probe (5) to isolate the excitation signal from the echo signal.

[0068] The output of the signal triggering and acquisition module (2) is connected to the radio frequency pulse generator (3), and the input is connected to the signal receiving amplifier (7).

[0069] The data acquisition computer (1) is connected to the signal triggering and acquisition module (2), controls the frequency sweep excitation and acquires and processes the resonant spectrum data to calculate the copper layer thickness.

[0070] Furthermore, the ultrasonic probe includes a butterfly coil and a permanent magnet. The ultrasonic probe excites ultrasonic transverse waves onto the surface of the copper-aluminum composite plate under test in a non-contact manner and receives the reflected echo signal.

[0071] Furthermore, the data acquisition computer includes:

[0072] The frequency sweep control module is used to generate linear frequency modulation signal parameters and send them to the radio frequency pulse generator;

[0073] The resonance peak extraction module is used to process the acquired signal and identify the extreme points of the amplitude-frequency curve;

[0074] The thickness inversion module is used to solve the transcendental equations based on the Brent algorithm and output the copper layer thickness value.

[0075] The following description, in conjunction with specific embodiments, provides further details.

[0076] As a specific embodiment, the test sample is a copper-aluminum composite plate (6), and the ultrasonic probe (5) adopts a transverse wave excitation mode, including a permanent magnet and a butterfly coil, to excite a transverse wave with a single polarization direction in a non-contact manner. The implementation structure is as follows: Figure 2As shown, the butterfly coil is manufactured using flexible PCB circuit board technology, and the permanent magnet provides a static bias magnetic field for the neodymium iron boron magnet. The ultrasonic probe (5) is connected to the detection system via a duplexer (4) to achieve signal transmission and reception.

[0077] The method for measuring the copper layer thickness of copper-aluminum composite panels includes the following steps:

[0078] S1: Obtain material parameters, including: copper layer density, aluminum layer density, copper transverse wave velocity, aluminum transverse wave velocity, and overall thickness of the composite plate. The overall thickness of the copper-aluminum composite plate, D = 6.27 mm, is measured using vernier calipers.

[0079] S2: Frequency sweep excitation and signal acquisition

[0080] By applying a continuous frequency excitation signal within a certain range to the copper-aluminum composite plate sample, its electromagnetic ultrasonic response is excited by a frequency sweep method, and the amplitude-frequency response curve is recorded. Several obvious resonance peaks can be identified in the response curve, corresponding to the acoustic resonance behavior of the material structure at a specific frequency. As a feasible embodiment, a 0-2.5MHz continuous frequency sweep excitation signal is applied to the sample by a radio frequency pulse generator (3), and the ultrasonic probe (5) excites ultrasonic transverse waves in a non-contact manner and receives the response signal. After being amplified by the signal receiving amplifier (7), the amplitude-frequency response curve is recorded by the signal triggering and acquisition module (2).

[0081] S3: Resonance Peak Frequency Extraction

[0082] Identify several distinct resonance peaks in the amplitude-frequency response curve, such as Figure 3 Nine distinct resonance peaks were identified. The extracted resonance peak frequencies were used as the input resonance frequencies.

[0083] S4: Establish the transcendental equation for thickness inversion

[0084] A correlation model between the copper layer thickness d1 and the aluminum layer thickness d2 is established based on the following equation:

[0085]

[0086] Where ρ1 and ρ2 are the densities of copper and aluminum, respectively, c1 and c2 are the transverse wave sound velocities of copper and aluminum, respectively, f is the resonant frequency, the overall thickness of the composite plate is obtained by measurement, the copper layer thickness is d1, the aluminum layer thickness is d2, and the aluminum layer thickness d2 in the calculation formula is replaced with (6.27-d1).

[0087] The thickness inversion formula used in this method is based on the assumption that the energy attenuation of ultrasonic transverse waves during propagation in the second layer of material is ignored. For copper-aluminum bilayer metal composites, since their interfaces are usually bonded using metallurgical processes, resulting in good interfacial bonding and excellent acoustic coupling, this assumption has high rationality and engineering applicability in practical applications.

[0088] S5: Solving and Optimizing the Brent Algorithm

[0089] Since this equation is a transcendental equation with no analytical solution, Brent's method can be used. This method combines the robustness of the bisection method with the efficiency of the interpolation method, enabling it to quickly and stably find the zero point. Because the transcendental equation contains a tangent function, it may exhibit singularities within a specific thickness range (e.g., numerical divergence near extreme points). Therefore, when performing thickness numerical inversion calculations, it is necessary to first identify and mark the thickness ranges that may produce singular solutions. To ensure the physical reliability of the inversion results, a reasonable physically feasible interval must be set as a constraint, taking into account the design thickness range of the copper layer. All preliminary thickness solutions obtained are then screened and judged. Specifically, outlier solutions falling into singular regions or exceeding the design threshold range are eliminated through interval constraints. The remaining valid thickness results that meet physical rationality are normalized using statistical processing methods (such as arithmetic mean) to finally obtain a stable and reliable average copper layer thickness measurement.

[0090] As one specific embodiment, the following process is performed:

[0091] Singularity pre-identification: Based on the periodicity of the tangent function, mark the intervals within the thickness domain that may produce numerical divergence;

[0092] Physical constraint loading: The design thickness range of the copper layer is set as the feasible solution interval;

[0093] Iterative solution: The Brent algorithm is used to solve the problem within the feasible solution interval, which combines the robustness of the bisection method with the efficiency of inverse interpolation.

[0094] Outlier removal: Discard iterative solutions that are located in the singular region or exceed it.

[0095] Effective solution aggregation: The remaining effective solutions are arithmetically averaged to output the final copper layer thickness.

[0096] like Figure 4 The figure shown is a comparison between the calculated thickness and the actual value at different resonant frequencies. The copper layer thickness calculated by the method of the present invention has a small error compared with the actual value, and has high measurement accuracy.

[0097] This invention establishes a mathematical model relating the thickness of each component layer and its resonant frequency in a double-layer material based on the physical laws governing ultrasonic wave propagation and its boundary conditions. By performing frequency sweep testing on a copper-aluminum composite plate, its resonant spectrum information is obtained. Combined with the established theoretical model, the actual thickness of the copper layer is calculated, thus achieving non-contact, high-precision measurement of the copper layer thickness in the copper-aluminum composite plate. This method effectively solves the signal aliasing problem caused by interface reflection interference in multi-layer structures using traditional echo methods and is suitable for the accurate extraction of single-layer thickness in complex composite structures.

[0098] It should be understood that the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. Additionally, the character " / " in this article generally indicates an "or" relationship between the preceding and following related objects, but it can also represent an "and / or" relationship. Please refer to the context for a more accurate understanding.

[0099] In this invention, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of a single item or a plurality of items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be a single item or multiple items.

[0100] It should be understood that, in various embodiments of the present invention, the order of the above-mentioned process numbers does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0101] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0102] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the devices, apparatuses, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0103] In the several embodiments provided by this invention, it should be understood that the disclosed devices, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0104] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0105] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0106] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for measuring the copper layer thickness of a copper-aluminum composite plate using electromagnetic ultrasonic resonance, characterized in that, The method includes: S1 obtains multiple material parameters of the copper-aluminum composite plate; S2 applies a continuous sweep frequency excitation signal to the copper-aluminum composite plate through an ultrasonic probe to excite ultrasonic transverse waves and receive response signals to generate an amplitude-frequency response curve. S3 extracts multiple resonant peak frequencies from the amplitude-frequency response curve to serve as the input resonant frequencies. S4 establishes a thickness inversion transcendental equation based on the multiple material parameters and the input resonant frequency; S5 uses the Brent algorithm to solve the inversion transcendental equation to output the copper layer thickness.

2. The method for measuring the copper layer thickness of a copper-aluminum composite plate using electromagnetic ultrasonic resonance according to claim 1, characterized in that, In S4, the thickness inversion transcendental equation is: Where ρ1 and ρ2 are the densities of copper and aluminum, respectively, c1 and c2 are the transverse wave sound velocities of copper and aluminum, respectively, f is the resonant frequency, and the overall thickness of the composite plate is obtained by measurement, with copper layer thickness d1 and aluminum layer thickness d2.

3. The method for measuring the copper layer thickness of a copper-aluminum composite plate using electromagnetic ultrasonic resonance according to claim 1, characterized in that, In S5, solving the inversion transcendental equation based on the Brent algorithm to output the copper layer thickness includes: The singular intervals in which the inversion transcendental equation may produce numerical divergence within the domain of copper layer thickness are marked. The feasible solution range is defined based on the copper layer design thickness range, excluding singular regions and solutions with non-physical thickness; Within the feasible solution interval, initial iteration points are generated using the bisection method, and then inverse interpolation is used to approximate the zeros of the equation. When the iterative solution is located in the singular region or exceeds the feasible solution region, the abnormal solution is removed. The remaining thickness solutions that satisfy the physical constraints are then arithmetically averaged to output the final copper layer thickness.

4. The method for measuring the copper layer thickness of a copper-aluminum composite plate using electromagnetic ultrasonic resonance according to claim 1, characterized in that, In S1, the multiple material parameters include: copper layer density, aluminum layer density, copper transverse wave velocity, aluminum transverse wave velocity, and overall thickness of the composite plate.

5. The method for measuring the copper layer thickness of a copper-aluminum composite plate using electromagnetic ultrasonic resonance according to claim 1, characterized in that, In S3, the multiple resonant peak frequencies are 2 to 10.

6. A measuring device for measuring the copper layer thickness of a copper-aluminum composite plate using electromagnetic ultrasonic resonance method, wherein the measuring device is used to implement the method for measuring the copper layer thickness of a copper-aluminum composite plate using electromagnetic ultrasonic resonance method as described in any one of claims 1-6, characterized in that... The device includes a data acquisition computer, a signal triggering and acquisition module, a radio frequency pulse generator, a duplexer, an ultrasonic probe, and a signal receiving amplifier; The ultrasonic probe is connected to the duplexer; The input end of the duplexer is connected to the radio frequency pulse generator, and the output end is connected to the ultrasonic probe, which is used to isolate the excitation signal and the echo signal. The output of the signal triggering and acquisition module is connected to an RF pulse generator, and the input is connected to a signal receiving amplifier. The data acquisition computer is connected to the signal triggering and acquisition module, controls the frequency sweep excitation and acquires and processes the resonant spectrum data to calculate the copper layer thickness.

7. The measuring device for measuring the copper layer thickness of copper-aluminum composite plates using the electromagnetic ultrasonic resonance method according to claim 6, characterized in that, The ultrasonic probe includes a butterfly coil and a permanent magnet. The ultrasonic probe excites ultrasonic transverse waves onto the surface of the copper-aluminum composite plate under test in a non-contact manner and receives the reflected echo signal.

8. The measuring device for measuring the copper layer thickness of copper-aluminum composite plates using the electromagnetic ultrasonic resonance method according to claim 7, characterized in that, The distance between the ultrasonic probe and the sample is 0.1-1 mm.

9. The measuring device for measuring the copper layer thickness of copper-aluminum composite plates using the electromagnetic ultrasonic resonance method according to claim 6, characterized in that, The data acquisition computer includes: The frequency sweep control module is used to generate linear frequency modulation signal parameters and send them to the radio frequency pulse generator; The resonance peak extraction module is used to process the acquired signal and identify the extreme points of the amplitude-frequency curve; The thickness inversion module is used to solve the transcendental equations based on the Brent algorithm and output the copper layer thickness value.

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