Device and method for measuring microwave dielectric constant and surface and interface conductivity of copper-clad plate material

Abstract

The invention discloses a device and a method for measuring the microwave dielectric constant and the surface and interface conductivity of a copper-clad plate material. The device specifically comprises a four-port vector network analyzer, a quasi-optical open type resonant cavity, a sample clamp and a one-dimensional displacement table. The method comprises the following steps: measuring the resonant frequency and the quality factor of the cavity and the sample, and calculating the dielectric constant and the conductivity of the sample through a formula. Meanwhile, a reference pure copper flat plate sample and a PCB copper-clad plate sample are set, multiple times of resonance information measurement are carried out, and a method for calculating the resistance and conductivity of the copper-clad interface is formulated by combining the characteristics of the device. The novel design enables the electrical performance measurement of the copper-clad plate material to be more accurate and convenient, and is beneficial to research, development and application of novel materials.

Description

Technical Field

[0001] The invention belongs to the field of measurement and observation, and more specifically relates to a device and method for measuring the microwave dielectric constant and surface conductivity of a copper-clad plate material. Background Art

[0002] In recent years, high-frequency, low-loss copper-clad PCBs have been widely used in millimeter-wave wireless communications and radar sensing systems. They are usually used to manufacture planar circuits at microwave and millimeter-wave frequencies, such as microstrip lines, strip lines, and coplanar waveguide transmission lines. Accurately measuring and characterizing the dielectric constant of the PCB substrate and the conductivity parameters of the copper cladding at different frequencies plays a key role in the design and development of microwave and millimeter-wave circuits, components, and systems.

[0003] When designing microwave and millimeter-wave planar circuits, the key material parameters of PCB copper-clad boards include the complex dielectric constant and the conductivity of the copper clad board. The publicly reported measurement and characterization methods of PCB copper-clad boards are usually based on measurement devices or systems based on different principles, which respectively measure the dielectric constant of the PCB substrate and the conductivity of the copper clad board. For example, quasi-optical open resonant cavities or free space methods are currently used to test the millimeter-wave dielectric properties of PCB substrates, with frequencies covering 110 GHz or even higher. For the measurement of the conductivity parameters of copper-clad materials, balanced disk resonators or dielectric rod resonators are currently used.

[0004] However, these methods have some limitations: 1) Before measuring the conductivity of the copper clad, it is still necessary to use other devices to test the real part of the dielectric constant and the loss tangent value of the substrate in advance. 2) In the calculation model of conductivity, it is generally necessary to use finite element simulation methods to obtain parameters such as the filling factor and resonant cavity shape factor of the bare substrate. 3) These methods usually measure and characterize the conductivity characteristics of the copper clad surface, and cannot obtain the conductivity parameters at the interface between the copper clad and the substrate. In common PCB copper-clad dielectric substrates, the bonding surface of the copper foil at the interface is usually rough to maintain the strong adhesion between the copper foil and the substrate. At microwave millimeter wave frequencies, the interface roughness of the conductor will significantly reduce its conductivity value. For typical planar circuits such as microstrip lines, striplines, and coplanar lines, the values ​​of the copper clad surface conductivity and dielectric conductivity are quite different, and their contributions to conductor losses are also different. Therefore, it is very important to accurately test and evaluate the surface and interface conductivity characteristics of the copper clad for the design and development of microwave millimeter wave planar circuits.

[0005] In summary, in the microwave and millimeter wave frequency band, there is no measuring device and method that can simultaneously measure and characterize the dielectric parameters of the PCB substrate and the interface conductivity parameters of the copper-clad surface. In response to this problem, the present invention proposes an improved quasi-optical open resonant cavity measuring device, and proposes a new copper-clad surface and interface conductivity parameter testing method, which can achieve accurate measurement of the dielectric constant of the PCB substrate and the interface conductivity parameters of the copper-clad surface in a set of measuring devices. This method does not require complex electromagnetic finite element simulation calculations, but only requires a pure copper reference sample with a smooth surface, which is more suitable for actual engineering measurement needs. Summary of the invention

[0006] The purpose of the present invention is to provide a method for measuring the dielectric constant and surface conductivity of a copper-clad board based on an improved quasi-optical open resonant cavity device, in order to solve the problem that the dielectric parameters of a PCB copper-clad board substrate and the copper-clad conductivity characteristics in the microwave and millimeter wave frequency bands cannot be measured simultaneously, and the existing copper-clad conductivity testing methods are relatively complicated.

[0007] In order to achieve the above object, the present invention is implemented by adopting the following technical scheme: the measuring device comprises: a four-port vector network analyzer, a quasi-optical open resonant cavity, a sample fixture and a one-dimensional translation stage;

[0008] The quasi-optical open resonant cavity is composed of two spherical reflectors; each spherical reflector has two waveguide or coaxial coupling interfaces for feeding and receiving electromagnetic wave signals;

[0009] The vector network analyzer is connected to the coupling interface on the spherical reflector of the resonant cavity through a microwave cable. The resonant frequency and quality factor of the resonant cavity are measured before and after the sample is placed in the cavity, and the dielectric constant or conductivity of the material is calculated.

[0010] On the other hand, a method for measuring microwave dielectric constant and surface conductivity of copper clad laminate material is provided, wherein the method is applicable to the measuring device as claimed in claim 1, and the method is characterized in that the measuring method comprises:

[0011] (1) Measurement of dielectric constant of PCB substrate;

[0012] (2) Measurement of PCB copper surface and interface conductivity parameters.

[0013] In one embodiment, the PCB substrate dielectric constant measurement includes:

[0014] Step 1: Connect ports 1 and 2 of the vector network analyzer to the spherical reflector on the resonant cavity, set the start and end frequencies, scanning points, and intermediate frequency bandwidth of the vector network analyzer, and set the measurement display to the transmission coefficient modulus;

[0015] Step 2: Perform a frequency sweep test on the resonant cavity to identify the working resonant frequency point, and measure the resonant frequency f0 and the resonant quality factor Q0 of the cavity in turn;

[0016] Step 3: Place the material sample and move the material fixture until the current resonant frequency changes to the minimum, and the position corresponds to the electrical center of the cavity; measure the resonant frequency and quality factor Q at this time L ;

[0017] Step 4: Calculate the real part of the dielectric constant ε of the sample according to the following formula (1): r ′:

[0018]

[0019] Where:

[0020] d=(Dt) / 2

[0021]

[0022] Where: n is the refractive index of the sample being measured, k is the wave number of the electromagnetic wave in the resonant cavity; t is the thickness of the sample being measured; R0 is the radius of curvature of the concave reflector of the resonant cavity; and D is the length of the resonant cavity.

[0023] In one scheme, the loss tangent value tanδ of the sample under test is calculated from the change in the quality factor of the open resonant cavity sample before and after loading, and the calculation formula is as follows (2):

[0024]

[0025] where p e is the filling factor of the substrate medium,

[0026]

[0027] Where Q L is the loaded quality factor of the resonant cavity after loading the measured sample; Q0 is the loaded quality factor of the cavity.

[0028] In one embodiment, the PCB copper-clad surface and interface conductivity parameter measurement includes:

[0029] Step 1: Connect ports 1 and 2 of the vector network analyzer to the spherical reflector on the resonant cavity, set the start and end frequencies, scanning points, and intermediate frequency bandwidth of the vector network analyzer, and set the measurement display to the transmission coefficient modulus;

[0030] Step 2: Perform a frequency sweep test on the resonant cavity to identify the working resonant frequency point, and measure the resonant frequency f0 and the resonant quality factor Q of the cavity in turn. 0；

[0031] Step 3: Place the reference pure copper plate sample, move the material fixture position, make the current resonant frequency equal to the cavity resonant frequency in step 2, and measure the quality factor Q at this time ref；

[0032] Step 4: Place the PCB copper-clad board sample in the center of the fixture, reposition the material fixture so that the current resonant frequency is equal to the cavity resonant frequency in step 2, and measure the quality factor Q at this time s ; Calculate the surface conductivity σ of the copper clad s ;

[0033] Step 5: Connect ports 1 and 2 of the vector network analyzer to the upper spherical mirror coupling interface, and ports 3 and 4 to the lower spherical mirror coupling interface. The samples from top to bottom are PCB substrate bare board and PCB copper clad board respectively; move the material fixture position so that the resonant frequency measured by ports 1 and 2 is equal to the cavity resonant frequency in step 2, and measure the quality factor Q at this time up ;

[0034] Step 6: Move the material fixture so that the resonant frequency measured by ports 3 and 4 of the vector network analyzer is equal to the cavity resonant frequency in step 2, and measure the quality factor Q at this time. down .

[0035] In one embodiment, the surface conductivity of the copper clad is s The calculation is as follows:

[0036]

[0037] Where: ref is the conductivity of the reference pure copper sample.

[0038] In one embodiment, the quality factor Q of the measurement is up , using the following equation (4):

[0039]

[0040] Where: is the surface resistance of the reference pure copper sample, μ is the vacuum permeability, and p is the e and tanδ are the filling factor and loss tangent of the PCB substrate, respectively. plane is the shape factor of the pure copper flat plate sample.

[0041] In one embodiment, the quality factor Q of the measurement is down , using the following equation (5)

[0042]

[0043] Where: is the copper cladding interface resistance, σ int is the interface conductivity;

[0044] Combining equations (4) and (5), the copper-clad interface resistance R is calculated. int , and then calculate the interface conductivity σ int .

[0045] Beneficial effects of the present invention:

[0046] The present invention realizes that a set of devices can be compatible with two working modes, namely, double concave resonant cavity and flat concave resonant cavity, by processing two coupling interfaces for transmitting and receiving electromagnetic waves on each resonant cavity reflector. The former can be used to measure the dielectric constant of PCB substrate, and the latter can be used to test the conductivity parameters of copper clad. In addition, the present invention proposes a new method for testing interface conductivity using the surface conductivity measurement value of the copper clad smooth surface as a reference calibration value, thereby avoiding complex electromagnetic finite element simulation calculations. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a structural diagram of the improved four-coupling hole quasi-optical open resonant cavity device of the present invention;

[0048] Figure 2 Schematic diagram of the resonant cavity in different working modes of the present invention;

[0049] Figure 3 This is a flow chart of the dielectric constant measurement of the PCB substrate of the present invention;

[0050] Figure 4 The present invention is a flow chart for measuring the conductivity parameters of the copper-clad surface and interface of a PCB.

[0051] In the figure, 1- four-port vector network analyzer; 2- microwave cable; 3- upper spherical reflector; 4- lower spherical reflector; 5- upper reflector waveguide or coaxial coupling structure; 6- lower reflector waveguide or coaxial coupling structure; 7- one-dimensional translation stage; 8- sample fixture; 9- sample substrate layer; 10- sample copper cladding layer.

[0052] Figure 2 (a) Double cavity working mode; Figure 2 (b) Flat-concave cavity working mode; Figure 2 (c) Flat-concave cavity working mode; Figure 2 (d) Flat-concave cavity working mode. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention is described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] PCB copper-clad board measurement device based on improved four-coupled hole quasi-optical open resonance principle Figure 1 As shown, it includes: a four-port vector network analyzer, a quasi-optical open resonant cavity (the main structure is composed of two spherical reflectors), a sample of the material to be tested, a sample fixture and a one-dimensional translation stage. Each of the spherical reflectors has two waveguide or coaxial coupling interfaces for feeding and receiving electromagnetic wave signals. The vector network analyzer is connected to the coupling interface on the spherical reflector of the resonant cavity through a microwave cable. The resonant frequency and quality factor of the resonant cavity are measured before and after the sample is placed, and the dielectric constant or conductivity of the material is calculated. When the bare board sample of the PCB substrate is directly placed in the fixture, the resonant cavity operates in a double concave cavity mode (such as Figure 2 (a)), the dielectric constant and loss tangent of the substrate can be measured; when the PCB copper-clad board is placed in the fixture (copper-clad surface facing up), the resonant cavity operates in the plano-concave cavity mode (such as Figure 2 (c)), the surface conductivity of the copper can be measured. When the bare PCB substrate and the copper-clad PCB are placed from top to bottom (copper-clad side facing up), the resonant cavity works in the plano-concave cavity mode (such as Figure 2 (d)), the interfacial conductivity of the copper coating can be measured.

[0055] The main structure of the quasi-optical open resonant cavity in the present invention is composed of a pair of brass spherical reflectors with polished and gold-plated surfaces. The curvature radius, aperture diameter and other dimensions of the reflectors are designed to achieve stable TEM in the cavity. 00q Mode resonance.

[0056] The spherical reflector of the quasi-optical resonant cavity is processed with two coupling interfaces for feeding and receiving electromagnetic waves. The coupling interface can be in the form of a coaxial coupling ring or a waveguide hole coupling.

[0057] The spherical reflector of the quasi-optical resonant cavity is made of brass, and the surface is plated with a gold film after optical polishing, and the resonance quality factor is greater than 100,000.

[0058] The material fixture in the quasi-optical resonant cavity is a plastic support with a round hole in the middle, which is used to place and fix the sample to be tested.

[0059] The one-dimensional translation stage in the quasi-optical resonant cavity is used for fixing and moving the material fixture, and the moving direction is vertical.

[0060] The feeding coupling interface of the quasi-optical resonant cavity should be carefully designed or the coupling strength can be adjusted so that the modulus of the transmission coefficient resonance peak can always be kept below -35dB and in a weak coupling state to improve the extraction accuracy of the resonance quality factor.

[0061] The quasi-optical resonant cavity can operate in a double-recessed cavity resonance mode, such as Figure 2 (a) is used to measure the real part of the dielectric constant and loss tangent of the substrate medium. At this time, the 1 and 2 ports of the network analyzer are connected to the spherical mirror coupling interface, and the bare PCB substrate sample is placed in the center of the fixture.

[0062] The quasi-optical resonant cavity can operate in a plano-concave cavity mode, such as Figure 2 (c) Measure the surface and interface conductivity of the PCB copper clad. At this time, the 1 and 2 ports of the network analyzer are connected to the upper spherical mirror coupling interface, and the 3 and 4 ports are connected to the lower spherical mirror coupling interface. The samples from top to bottom are PCB substrate bare board and PCB copper clad board (copper clad side facing up). The thickness of the substrate bare board should be the same as the thickness of the dielectric substrate in the copper clad board.

[0063] The copper-clad laminate surface interface conductivity measurement method requires a pure copper flat plate material with a surface polishing process as a reference sample, and the surface roughness is less than 100nm.

[0064] The quasi-optical resonant cavity device and the method for measuring the dielectric constant, surface and interface conductivity parameters of the copper-clad plate material are applicable to (20-330) GHz, wherein a coaxial coupling ring coupling interface is used below 110 GHz, and a waveguide coupling interface is used above 110 GHz.

[0065] like Figure 3 As shown, the dielectric constant of PCB substrate is measured:

[0066] The measurement principle diagram is as follows: Figure 2 As shown in (a), the resonant cavity works in the double-concave cavity mode. By measuring the resonant frequency and quality factor of the sample before and after being placed in the resonant cavity, the real part of the dielectric constant and the loss tangent value of the sample are calculated. The measurement steps are as follows:

[0067] Step 1: Connect ports 1 and 2 of the vector network analyzer to the spherical reflector on the resonant cavity, set the start and end frequencies, number of scanning points, and intermediate frequency bandwidth of the vector network analyzer, and set the measurement display to the transmission coefficient modulus.

[0068] Step 2: Perform a frequency sweep test on the resonant cavity to identify the working resonant frequency point, and measure the resonant frequency f0 and the resonant quality factor Q0 of the cavity in turn.

[0069] Step 3: Place the material sample and move the material fixture until the current resonant frequency changes to the minimum, and the position corresponds to the electrical center of the cavity. Measure the resonant frequency and quality factor Q at this time L ;

[0070] Step 4: Calculate the real part of the dielectric constant ε of the sample according to the following formula (1): r ′:

[0071]

[0072] Where:

[0073] d=(Dt) / 2

[0074]

[0075] Where: n is the refractive index of the sample being measured, k is the wave number of the electromagnetic wave in the resonant cavity; t is the thickness of the sample being measured; R0 is the radius of curvature of the concave reflector of the resonant cavity; and D is the length of the resonant cavity.

[0076] The loss tangent value tanδ of the sample under test can be calculated from the change in the quality factor of the open resonant cavity sample before and after loading, and the calculation formula is as follows (2):

[0077]

[0078] where p e is the filling factor of the substrate medium,

[0079]

[0080] Where Q L is the loaded quality factor of the resonant cavity after loading the measured sample; Q0 is the loaded quality factor of the cavity.

[0081] like Figure 4 As shown, the PCB copper-clad surface and interface conductivity parameters are measured:

[0082] The measurement principle diagram is as follows: Figure 2 As shown in (b), 2(c) and 2(d), the resonant cavity works in the plano-concave cavity mode. First, a reference pure copper flat sample is placed to measure the resonant quality factor of the resonant cavity, and then a bare PCB substrate and a PCB copper-clad laminate are placed to measure the surface and interface conductivity of the copper-clad laminate. The measurement steps are as follows:

[0083] Step 1: Follow Figure 2 As shown in (b), connect ports 1 and 2 of the vector network analyzer to the spherical reflector on the resonant cavity, set the start and end frequencies, number of scanning points, and intermediate frequency bandwidth of the vector network analyzer, and set the measurement display to the transmission coefficient modulus.

[0084] Step 2: Perform a frequency sweep test on the resonant cavity to identify the working resonant frequency point, and measure the resonant frequency f0 and the resonant quality factor Q0 of the cavity in turn.

[0085] Step 3: Place the reference pure copper plate sample, move the material fixture position, make the current resonant frequency equal to the cavity resonant frequency in step 2, and measure the quality factor Q at this time ref .

[0086] Step 4: Follow Figure 2 As shown in (c), place the PCB copper-clad board sample in the center of the fixture (copper-clad surface facing up), reposition the material fixture so that the current resonant frequency is equal to the cavity resonant frequency in step 2, and measure the quality factor Q at this time s The surface conductivity σ of the copper coating is calculated according to the following formula (3): s :

[0087]

[0088] Where: ref is the conductivity of the reference pure copper sample.

[0089] Step 5: Follow Figure 2 As shown in (d), ports 1 and 2 of the vector network analyzer are connected to the upper spherical mirror coupling interface, and ports 3 and 4 are connected to the lower spherical mirror coupling interface. The samples from top to bottom are PCB substrate bare board and PCB copper-clad board (copper-clad side facing up). Move the material fixture position so that the resonant frequency measured by ports 1 and 2 is equal to the cavity resonant frequency in step 2, and measure the quality factor Q at this time. up According to the energy dissipation relationship in the resonant cavity, the following equation (4) is obtained:

[0090]

[0091] Where: is the surface resistance of the reference pure copper sample, μ is the vacuum permeability, and p is the e and tanδ are the filling factor and loss tangent of the PCB substrate, respectively. plane is the shape factor of the pure copper flat plate sample.

[0092] Step 6: Move the material fixture so that the resonant frequency measured by ports 3 and 4 of the vector network analyzer is equal to the cavity resonant frequency in step 2, and measure the quality factor Q at this time. down According to the energy dissipation relationship in the resonant cavity, the following equation (5) is obtained:

[0093]

[0094] Where: is the copper cladding interface resistance, σint is the interface conductivity.

[0095] By combining equations (4) and (5), the copper-clad interface resistance R can be calculated. int , and then the interface conductivity σ can be calculated int .

[0096] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A device for measuring microwave dielectric constant and surface conductivity of copper-clad laminate materials, characterized in that: The measuring device comprises: a four-port vector network analyzer, a quasi-optical open resonant cavity, a sample fixture and a one-dimensional displacement stage; The quasi-optical open resonant cavity is composed of two spherical reflectors; each spherical reflector has two waveguide or coaxial coupling interfaces for feeding and receiving electromagnetic wave signals; The vector network analyzer is connected to the coupling interface on the spherical reflector of the resonant cavity through a microwave cable. The resonant frequency and quality factor of the resonant cavity are measured before and after the sample is placed in the cavity, and the dielectric constant or conductivity of the material is calculated.

2. A method for measuring microwave dielectric constant and surface conductivity of copper-clad laminate materials, the method being applicable to the measuring device as claimed in claim 1, characterized in that: The measuring method comprises: (1) Measurement of dielectric constant of PCB substrate; (2) Measurement of PCB copper surface and interface conductivity parameters.

3. The method for measuring microwave dielectric constant and surface conductivity of a copper-clad laminate material according to claim 2, characterized in that: The PCB substrate dielectric constant measurement includes: Step 1: Connect ports 1 and 2 of the vector network analyzer to the spherical reflector on the resonant cavity, set the start and end frequencies, scanning points, and intermediate frequency bandwidth of the vector network analyzer, and set the measurement display to the transmission coefficient modulus; Step 2: Perform a frequency sweep test on the resonant cavity to identify the working resonant frequency point, and measure the resonant frequency f0 and the resonant quality factor Q0 of the cavity in turn; Step 3: Place the material sample and move the material fixture until the current resonant frequency changes to the minimum, and the position corresponds to the electrical center of the cavity; measure the resonant frequency and quality factor Q at this time L ; Step 4: Calculate the real part of the dielectric constant ε of the sample according to the following formula (1): r ′: Where: d=(Dt) / 2 Where: n is the refractive index of the sample being measured, k is the wave number of the electromagnetic wave in the resonant cavity; t is the thickness of the sample being measured; R0 is the radius of curvature of the concave reflector of the resonant cavity; and D is the length of the resonant cavity.

4. The method for measuring microwave dielectric constant and surface conductivity of a copper-clad laminate material according to claim 3, characterized in that: The loss tangent value tanδ of the sample under test is calculated from the change in the quality factor of the open resonant cavity sample before and after loading, and the calculation formula is as follows (2): where p e is the filling factor of the substrate medium, Where Q L is the loaded quality factor of the resonant cavity after loading the measured sample; Q0 is the loaded quality factor of the cavity.

5. The method for measuring microwave dielectric constant and surface conductivity of a copper-clad laminate material according to claim 2, characterized in that: The PCB copper-clad surface and interface conductivity parameter measurement includes: Step 1: Connect ports 1 and 2 of the vector network analyzer to the spherical reflector on the resonant cavity, set the start and end frequencies, scanning points, and intermediate frequency bandwidth of the vector network analyzer, and set the measurement display to the transmission coefficient modulus; Step 2: Perform a frequency sweep test on the resonant cavity to identify the working resonant frequency point, and measure the resonant frequency f0 and the resonant quality factor Q of the cavity in turn. 0； Step 3: Place the reference pure copper plate sample, move the material fixture position, make the current resonant frequency equal to the cavity resonant frequency in step 2, and measure the quality factor Q at this time ref； Step 4: Place the PCB copper-clad board sample in the center of the fixture, reposition the material fixture so that the current resonant frequency is equal to the cavity resonant frequency in step 2, and measure the quality factor Q at this time s ; Calculate the surface conductivity σ of the copper clad s ; Step 5: Connect ports 1 and 2 of the vector network analyzer to the upper spherical mirror coupling interface, and ports 3 and 4 to the lower spherical mirror coupling interface. The samples from top to bottom are PCB substrate bare board and PCB copper clad board respectively; move the material fixture position so that the resonant frequency measured by ports 1 and 2 is equal to the cavity resonant frequency in step 2, and measure the quality factor Q at this time up ; Step 6: Move the material fixture so that the resonant frequency measured by ports 3 and 4 of the vector network analyzer is equal to the cavity resonant frequency in step 2, and measure the quality factor Q at this time. down .

6. The method for measuring microwave dielectric constant and surface conductivity of a copper-clad laminate material according to claim 5, characterized in that: The surface conductivity of the copper clad s The calculation is as follows: Where: ref is the conductivity of the reference pure copper sample.

7. The method for measuring microwave dielectric constant and surface conductivity of a copper-clad laminate material according to claim 5, characterized in that: The quality factor Q of the measurement at this time up , using the following equation (4): Where: is the surface resistance of the reference pure copper sample, μ is the vacuum permeability, and p is the e and tanδ are the filling factor and loss tangent of the PCB substrate, respectively. plane is the shape factor of the pure copper flat plate sample.

8. The method for measuring microwave dielectric constant and surface conductivity of copper clad laminate material according to claim 5, characterized in that: The quality factor Q of the measurement at this time down , using the following equation (5) Where: is the copper cladding interface resistance, σ int is the interface conductivity; Combining equations (4) and (5), the copper-clad interface resistance R is calculated. int , and then calculate the interface conductivity σ int .

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