Rebounding type four-probe conductivity testing device

Abstract

The invention relates to the technical field of resistance measurement, and provides a four-probe conductivity testing device. By additionally arranging the guide groove and the telescopic mechanism, the probe can retract to different degrees according to the size of the to-be-tested sample and the thickness of an oxide layer, it is guaranteed that the probe makes elastic contact with the to-be-tested sample to achieve stable contact force, even if the probe faces a flexible or fragile sample with the uneven surface, the probe can also be in a good contact state, and the detection accuracy is improved. Measurement errors caused by the problem of contact stability are avoided; the pressure and the position of the probe do not need to be manually adjusted in the operation process, the testing efficiency can be effectively improved, and the damage risk of the to-be-tested sample is reduced. By adopting the probe with an elastic reset function, the probe can be ensured to stably contact with the sample to be tested during testing and can be reset to protect the electrode plate after testing is finished, so that the adaptability of the probe is improved, the probe can be suitable for samples with different surface properties, and the accuracy of a measurement result is improved; the electrode plates can be protected, and abrasion generated when the probe is moved is prevented.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of resistance measurement, and particularly relates to a reboundable four-probe conductivity testing device. BACKGROUND

[0002] Material conductivity measurement is of great significance in scientific research and engineering applications, as it can directly reflect the electrical conductivity of materials. In the study of semiconductor, metal, electrolyte and other materials, conductivity data can be used to optimize composition design, improve preparation process, and judge the applicability of materials in electronic devices, batteries or sensors. In addition, the change of conductivity can reveal the defects, doping effect or phase transition behavior of materials, providing key basis for the development and performance improvement of functional materials. In industrial quality control, conductivity measurement is an important means to ensure that the electrical conductivity of materials meets the standards. The core of conductivity measurement lies in the use of appropriate methods. The double-probe method or single-probe extension method is gradually replaced by methods with higher precision due to their low precision and greater influence of contact resistance. The six-probe method is suitable for special scenarios of anisotropic materials, while the four-probe method has become the mainstream method due to its high precision and wide applicability, especially in the field of semiconductors. The four-probe method effectively eliminates the influence of contact resistance through four-electrode design, with high measurement precision. This method has been widely used in the conductivity detection of thin film materials, semiconductor devices and powder samples.

[0003] CN119959616A discloses a four-probe thin-layer sheet resistance testing method and testing device, which can configure different probe types, numbers and detection modes according to sample size and oxide layer thickness, and realize fast and accurate sheet resistance measurement through 5-point or 9-point testing mode. The testing device includes data acquisition, processing, communication and control modules, and the probe is in elastic contact with the sample to ensure stable contact force, thereby improving detection efficiency and precision. The sheet resistance value is obtained through a specific calculation model, and a data set containing parameters such as maximum value, minimum value and average value is generated. The server associates the test results with the station information, displays and judges whether it is qualified.

[0004] However, the existing four-probe testing device has contact stability problems in actual application, which directly affects the repeatability and accuracy of the measurement results. This is because when facing uneven, flexible or brittle samples, fixed probes are difficult to ensure good contact state. In addition, the existing probe structure is mostly rigid design, lacking automatic reset function, resulting in the need for frequent manual adjustment of probe pressure and position during operation, which is low in efficiency and easy to cause damage to the sample. Probe wear, aging and environmental factors (such as temperature changes) can also have a significant impact on the measurement results. SUMMARY

[0005] The present application aims to provide a resilient four-probe conductivity testing device, which can realize the extension and automatic resilience of the probe, improve the contact stability between the probe and the sample to be measured, enhance the accuracy of the measurement results, and improve the testing sensitivity and precision.

[0006] To achieve the above-mentioned purpose, the present application provides a resilient four-probe conductivity testing device, which comprises a main body having a first surface and a second surface arranged oppositely, a guide groove arranged inside the main body, the guide groove extending from the second surface to the first surface; four electrode pieces including two outer electrode pieces and two inner electrode pieces, the electrode pieces being accommodated in the guide groove and being capable of moving in the guide groove under the driving of an extension mechanism, the electrode pieces serving as probes and having a connecting end and a contact end arranged oppositely, the connecting end being fixedly connected to the bottom of the guide groove through the extension mechanism and being connected to a measuring instrument, the contact end having a contact surface for contacting the sample to be measured; wherein when the contact surface is not in contact with the sample to be measured, the extension mechanism can be extended to drive the contact end to protrude from the second surface so that the device is in a testing preparation state, and when the contact surface is in contact with the sample to be measured to generate a first pressure, the extension mechanism can be compressed under the first pressure to drive the contact end to retract into the guide groove so that the device is in a testing state.

[0007] In some embodiments, the extension mechanism can be compressed under a second pressure to make the electrode pieces clamped with the main body to lock the electrode pieces to a retracted position, or to make the electrode pieces unclamped with the main body to restore the device to the testing preparation state; wherein the second pressure is greater than the first pressure.

[0008] The technical scheme, by additionally arranging the guide groove and the telescopic mechanism, the probe can be retracted to different degrees according to the size of the sample to be measured and the thickness of the oxide layer, so that the probe and the sample to be measured are in elastic contact to realize stable contact force, thereby improving the detection efficiency and accuracy. The probe of the embodiment is in elastic contact with the sample to be measured, so that even when facing uneven, flexible or brittle samples, the probe can ensure good contact state, avoid measurement errors caused by contact stability problems, and realize non-destructive testing, solving the problems of poor contact, complex operation, poor adaptability and damage to the surface of the sample to be measured in the prior art. The probe of the embodiment is in elastic contact with the sample to be measured, and the probe pressure and position do not need to be manually adjusted during the operation process, which can effectively improve the test efficiency and reduce the damage risk to the sample to be measured. By adopting the probe with elastic reset function, the probe can stably contact the sample to be measured during testing and reset after testing to protect the electrode sheet, which not only improves the adaptability of the probe and enables it to be applicable to samples with different surface properties and realize non-destructive testing, but also improves the accuracy of the measurement result and protects the electrode sheet from wear during movement of the probe. In addition, the gold-plated copper is selected as the electrode sheet material, which further reduces the contact resistance and system resistance, thereby improving the test sensitivity and accuracy. The two outer electrode sheets are current input ends, and the two inner electrode sheets are voltage measurement ends. The advantages of the four-terminal method and the double-arm bridge method in low-resistance material electrical testing are combined to reduce the influence of additional resistance and optimize the current and voltage distribution of the circuit, thereby realizing high-precision measurement of low-resistance samples (<1Ω). In summary, the present application has important engineering application prospects and technical innovation value. BRIEF DESCRIPTION OF DRAWINGS

[0009] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments of the present application. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creating laborious work.

[0010] Figure 1 The schematic diagram of the architecture of the resilient four-probe conductivity testing device provided by an embodiment of the present application is shown in the figure. Figure 2 The schematic diagram of the side view cross-section of the resilient four-probe conductivity testing device provided by an embodiment of the present application is shown in the figure. Figure 3 The schematic diagram of the front view cross-section of the resilient four-probe conductivity testing device provided by an embodiment of the present application is shown in the figure. Figure 4 The schematic diagram of the cross-sectional view of the resilient four-probe conductivity testing device provided by another embodiment of the present application is shown in the figure. Figure 5 The schematic diagram of the cross-sectional view of the resilient four-probe conductivity testing device provided by another embodiment of the present application is shown in the figure.Figure 4 schematic diagram of the main view cross section of the embodiment shown; Figure 6 schematic diagram of the double-arm bridge method for measuring resistance provided by an embodiment of the present application; Figure 7 schematic diagram of the four-terminal method for measuring resistance provided by an embodiment of the present application.

[0011] Explanation of reference signs: 11, main body; 111, first surface; 112, second surface; 12~15, electrode pieces; 21, connecting end; 22, contact end; 221, contact surface; 16, guide groove; 17, telescopic mechanism; 18, wiring terminal; 19, limiting structure; 41, limiting ring. DETAILED DESCRIPTION

[0012] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0013] Please refer to Figures 1-7 , wherein, Figure 1 schematic diagram of the structure of the resilient four-probe conductivity testing device provided by an embodiment of the present application; Figure 2 schematic diagram of the side view cross section of the resilient four-probe conductivity testing device provided by an embodiment of the present application; Figure 3 schematic diagram of the main view cross section of the resilient four-probe conductivity testing device provided by an embodiment of the present application; Figure 4 schematic diagram of the cross section of the resilient four-probe conductivity testing device provided by another embodiment of the present application; Figure 5 for Figure 4 schematic diagram of the main view cross section of the embodiment shown; Figure 6 schematic diagram of the double-arm bridge method for measuring resistance provided by an embodiment of the present application; Figure 7 schematic diagram of the four-terminal method for measuring resistance provided by an embodiment of the present application.

[0014] As Figures 1-3 shown, the resilient four-probe conductivity testing device described in the present embodiment includes: a main body 11, four electrode pieces 12~15, a guide groove 16, and a telescopic mechanism 17.

[0015] Specifically, the main body 11 has a first surface 111 and a second surface 112 arranged oppositely, and a guide groove 16 is arranged in the main body and extends from the second surface 112 to the first surface 111. Four electrode sheets 12-15, including two outer electrode sheets 12 and 15 and two inner electrode sheets 13 and 14, are accommodated in the guide groove 16 and can move in and out of the guide groove 16 under the driving of an extension mechanism 17. The electrode sheets serve as probes and have a connecting end 21 and a contact end 22 arranged oppositely. The connecting end 21 is fixedly connected to the bottom of the guide groove 16 through the extension mechanism 17 and is connected to a measuring instrument (not shown), and the contact end 22 has a contact surface 221 for contacting a sample to be measured. When the contact surface 221 is not in contact with the sample to be measured, the extension mechanism 17 can be extended to drive the contact end 22 to protrude from the second surface 112, so that the device is in a test preparation state. When the contact surface 221 is in contact with the sample to be measured to generate a first pressure, the extension mechanism 17 can be compressed under the first pressure to drive the contact end 22 to retract into the guide groove 16, so that the device is in a test state.

[0016] The resilient four-probe conductivity testing device provided by the embodiment can retract to different degrees according to the size of the sample to be measured and the thickness of the oxide layer, so as to ensure elastic contact between the probe and the sample to be measured, stabilize the contact force, improve the detection efficiency and precision, and achieve non-destructive testing. The probe provided by the embodiment can ensure good contact state even when facing uneven, flexible or brittle samples, avoid measurement errors caused by contact stability problems, and solve the problems of poor contact, complex operation and poor adaptability in the prior art. The probe provided by the embodiment can be in elastic contact with the sample to be measured, and the probe pressure and position do not need to be manually adjusted during operation, so that the efficiency of the test can be effectively improved, and the risk of damage to the sample to be measured is reduced.

[0017] In some embodiments, the main body is made of engineering plastic to improve the strength and corrosion resistance of the main body. Engineering plastic has excellent comprehensive performance, high rigidity, small creep, high mechanical strength, good heat resistance, good electrical insulation, and can be used in harsh chemical and physical environments for a long time, and can replace metal as an engineering structure material.

[0018] In some embodiments, the electrode sheet is made of copper material to make the electrode sheet have good electrical conductivity, reduce the contact resistance and system resistance, and thus improve the test sensitivity and precision.

[0019] In some embodiments, the contact surface of the electrode sheet for contacting the sample to be measured has a protective layer. For example, the material surface of the contact surface of the electrode sheet can be treated, such as nickel plating, gold plating, etc., to form a protective layer to improve wear resistance and corrosion resistance.

[0020] In some embodiments, the electrode sheet has a cuboid shape, and the thickness of the electrode sheet is 0.25-0.35 mm, for example, 0.25 mm, 0.3 mm, or 0.35 mm. This design can make the electrode sheet have good conductivity, reduce the contact resistance and system resistance, and thus improve the test sensitivity and accuracy.

[0021] In this embodiment, the contact surface has a circular chamfer. The contact surface at the bottom of the electrode sheet is optimized to have an arc surface with a circular chamfer, which can avoid local stress concentration caused by rigid contact of a flat surface.

[0022] In this embodiment, the main body 11 is internally provided with four guide grooves 16, and the four guide grooves 16 are arranged at intervals along a first direction D1. Each electrode sheet is accommodated in a guide groove 16. In this embodiment, the first direction D1 is parallel to the first surface 111, the second direction D2 is perpendicular to the first surface 111, and the third direction D3 is parallel to the first surface 111 and perpendicular to the first direction D1. Further, the internal volume of the guide groove is slightly larger than the volume of the electrode sheet to allow the electrode sheet to smoothly slide in the guide groove.

[0023] In this embodiment, the spacing S1 between the outer electrode sheet and the adjacent inner electrode sheet is 1.5-2.5 mm; for example, S1=1.5 mm, S1=2 mm, S1=2.5 mm, etc.; and the spacing S2 between the two inner electrode sheets is 5.5-6.5 mm; for example, S2=5.5 mm, S2=6 mm, S2=6.5 mm, etc. The four electrode sheets are arranged along a straight line and maintain a certain spacing, which can simplify the structure, improve the measurement efficiency and accuracy, and also avoid damage to the electrode sheets and interference with each other, and can achieve non-destructive testing.

[0024] In this embodiment, the two outer electrode sheets 12 and 15 are used as current input terminals and are connected to the current output interface of the measuring instrument; and the two inner electrode sheets 13 and 14 are used as voltage measurement terminals and are connected to the voltage acquisition interface of the measuring instrument. The current input terminals and the voltage measurement terminals are strictly separated to avoid short circuit or signal distortion caused by reverse connection. By combining the advantages of the four-terminal method and the double-arm bridge method, the influence of the additional resistance is reduced and the current and voltage distribution of the circuit is optimized, thereby realizing high-precision measurement of low-resistance samples (<1Ω). After external connection of the circuit, the resistivity p is calculated by the measured resistance R xDetermined together with sample geometry parameters (such as thickness t, cross-sectional area A, electrode spacing s, etc.). Specifically, during testing, the wiring direction of the two current input terminals is consistent with the polarity of the test current, the two voltage measurement terminals correspond to the same side of the contact sample, and the wiring direction of the same group of current terminals / voltage terminals needs to be consistent to avoid symbol errors in measurement data caused by polarity reversal.

[0025] In this embodiment, the connecting end 21 of the electrode sheet has a metal pin (not shown) that can be inserted and fixed with the terminal 18; a wire (not shown) is crimped on the terminal post of the terminal 18, and the wire is connected to the measuring instrument. Specifically, the metal pin of the connecting end 21 of the electrode sheet can be inserted into the insertion hole of the terminal 18, and the contact is ensured by screw fastening; then one end of the wire is crimped on the terminal post of the terminal 18, and the other end is connected to the current / voltage interface of the measuring instrument (the outer electrode sheets 12, 15 are connected to the current output interface of the measuring instrument, and the inner electrode sheets 13, 14 are connected to the voltage acquisition interface of the measuring instrument). The wire needs to be arranged along the internal wiring groove of the probe to avoid winding or pulling to cause poor contact, thereby completing the measurement of the conductivity. The terminal is connected by screw fastening to ensure that the contact resistance is less than 1 mΩ; further clean the contact surface of the electrode sheet before measurement to avoid contact resistance fluctuations caused by the oxide film, and to ensure stability.

[0026] Further, the terminal 18 is a surface gold-plated terminal; the wire is a low-impedance copper wire with a length less than or equal to 1 m and a cross-sectional area greater than or equal to 0.5 mm 2 The wire connected to the voltage acquisition interface of the measuring instrument is a twisted wire wrapped with a metal shielding layer to reduce the influence of electromagnetic interference on the weak voltage signal (usually μV level).

[0027] In this embodiment, in the test preparation state (the contact surface is not in contact with the sample to be tested, and the telescopic mechanism can be extended to drive the contact end to protrude from the second surface), the contact ends of all the electrode sheets protrude from the second surface by the same distance.

[0028] In the embodiment, the telescopic mechanism 17 is a spring, one end of which is fixedly connected to the bottom of the guide groove 16, and the other end is connected to the connecting end 21 of the electrode sheet. The spring can limit the maximum distance of the electrode sheet extending out of the second surface 112, prevent the electrode sheet from completely separating from the main body 11 under the action of the spring, and ensure that the contact ends of all the electrode sheets are at the same level when not under pressure (i.e., the contact ends of all the electrode sheets protrude from the second surface by the same distance). When the probe is not in contact with the sample to be tested, the spring is stretched to push the electrode sheet out of the guide groove, making it protrude from the second surface of the main body, i.e., the device is in a test preparation state. When the bottom of the probe (mainly the contact surface) is pressed against the sample to be tested, the electrode sheet compresses the spring connected above it under the action of pressure, and the elastic force of the spring keeps the contact surface in contact with the sample to be tested, i.e., the device is in a test state. In other embodiments, the telescopic mechanism can also use a piezoelectric ceramic actuator, which is arranged between the bottom of the guide groove and the connecting end of the electrode sheet and controls the displacement amount of the electrode sheet according to the control signal. By replacing the mechanical spring with a piezoelectric ceramic actuator, the displacement amount of the electrode sheet can be accurately controlled by a voltage signal (the control method can refer to the existing control method of the piezoelectric ceramic actuator), which can make the test resolution higher.

[0029] For reference Figure 1 , Figures 4-5 , the device further comprises a limiting structure 19 arranged between the bottom of the guide groove 16 and the connecting end 21 of the electrode sheet; the limiting structure 19 is used to limit the distance of the contact end 22 of the electrode sheet protruding from the second surface 112 in the test preparation state, and limit the distance of the contact end 22 of the electrode sheet protruding from the second surface 112 after retracting into the guide groove in the test state.

[0030] In the embodiment, the limiting structure 19 is a groove-shaped structure arranged at the bottom of the guide groove 16 and extending into the main body from the side wall of the guide groove 16, and the limiting structure 19 and the bottom of the guide groove 16 form a stepped structure; the telescopic mechanism 17 is accommodated in the limiting structure 19; the connecting end 21 is additionally provided with a limiting ring 41, and the outer diameter of the connecting end 21 after adding the limiting ring 41 is greater than the hole diameter of the guide groove 16 (or the connecting end 21 of the electrode sheet can protrude outward), the limiting ring 41 is accommodated in the limiting structure 19; the up and down movement range of the connecting end 21 of the electrode sheet is limited by the limiting structure 19 (limited by the stepped structure and the limiting ring 41 when moving downward, and limited by the resistance of the telescopic mechanism 17 when moving upward).

[0031] In order to limit the full retraction of the electrode sheet from contacting the sample to be measured, a limiting structure 19 is arranged at the position of the connecting end 21 of each electrode sheet. In some embodiments, in the test state (when the contact surface contacts the sample to be measured to generate a first pressure, and the telescopic mechanism can be compressed under the first pressure to drive the connecting end to retract into the guide groove), the limiting structure limits the distance of the connecting end protruding from the second surface after retracting into the guide groove to be greater than or equal to 2 mm.

[0032] In some embodiments, the telescopic mechanism 17 can be compressed under a second pressure to make the electrode sheet clamped with the main body to lock the electrode sheet to a retracted position, or to make the electrode sheet unclamped with the main body to restore the device to a test preparation state; wherein the second pressure is greater than the first pressure. For example, the main body is further provided with an elastic buckle inside, and the connecting end of the electrode sheet has a clamping groove; when the device is not in use, the electrode sheet is manually pressed, the telescopic mechanism is compressed, and the elastic buckle is automatically embedded into the clamping groove of the electrode sheet to lock the electrode sheet in the retracted position; when the device needs to be used again, the electrode sheet is pressed or the unlocking mechanism is triggered to make the buckle disengage from the groove, and the electrode sheet is restored to the expanded state that the connecting end protrudes from the second surface under the expansion of the telescopic mechanism, achieving quick unlocking. Specifically, the retracted position can be that the connecting end is fully retracted into the guide groove to effectively avoid accidental wear or collision damage caused by the exposure of the electrode sheet; and the expanded state is that the connecting end protrudes from the second surface by a compression distance. That is, after the measurement is completed, the electrode sheet is manually pressed back into the guide groove to avoid wear of the electrode sheet; when the device needs to be used again, the electrode sheet is pressed or the unlocking mechanism is triggered to make the electrode sheet restore to the expanded state. The probe has an elastic reset function, which ensures that the probe can stably contact the sample to be measured during testing and can be reset after testing to protect the electrode sheet, not only improving the adaptability of the probe to make it applicable to samples with different surface properties and improving the accuracy of measurement results, but also protecting the electrode sheet and preventing wear when moving the probe.

[0033] As Figures 6-7As shown, the working principle of the resilient four-probe conductivity test device is as follows: (1) wiring: the two outer electrodes are current input terminals (C1 / C2), and the two inner electrodes are voltage measurement terminals (P1 / P2), which are connected to the current output interface and voltage collection interface of the measuring instrument, respectively. The current input terminals and the voltage measurement terminals are strictly separated to avoid short circuit or signal distortion caused by reverse connection; the wiring direction of the same group of current terminals / voltage terminals needs to be consistent (for example, C1 is connected to the positive electrode of the instrument, C2 is connected to the negative electrode, and P1 / P2 are connected to the same side of the sample), to avoid polarity reversal leading to symbol error of the measurement data. (2) Measurement: clean the contact surface of the electrode sheet before measurement to avoid contact resistance fluctuation caused by the oxidation film; and use the four-terminal method to measure the resistivity p of the low resistance sample (the application scenario) such as thin film and thin layer.

[0034] Specifically, after connecting the external circuit, the resistivity p is measured by the actual resistance R x , which is determined together with the geometric parameters of the sample (such as thickness d, cross-sectional area A, electrode spacing s, etc.). The resistivity formula is: p=R x • (A / L); wherein R x is the resistance value of the sample to be measured, which is measured by the four-terminal method, and the calculation formula is R x = V V / I S (V V is the voltage collected by the two inner voltage measurement terminals, and I S is the current input by the two outer current input terminals); A is the cross-sectional area of the sample to be measured (for thin film samples, A=d•w, d is the thickness of the sample to be measured, and w is the width of the sample to be measured; for block samples, A is the cross-sectional area in the current direction); L is the length of the sample to be measured in the current direction, that is, the distance between the two inner voltage measurement terminals (according to the schematic diagram shown in Figure 2 , the distance between the two inner voltage measurement terminals in the application is S2, so L=S2). If the sample to be measured is a thin film (thin film thickness d thin film transverse size), the sheet resistance R S =R can be used, and the formula of the resistivity is simplified as p=R S •d (d is the thickness of the thin film).

[0035] The resilient four-probe conductivity testing device provided by the above-mentioned embodiments of the present application can retract to different degrees according to the size of the sample to be tested and the thickness of the oxide layer, so as to ensure elastic contact between the probe and the sample to be tested, thereby stabilizing the contact force and improving the detection efficiency and accuracy. The probe of the present embodiment is in elastic contact with the sample to be tested, so that even when facing uneven, flexible or brittle samples, the probe can ensure good contact state and avoid measurement errors caused by contact stability problems, and can also realize non-destructive testing, solving the problems of poor contact, complex operation and poor adaptability in the prior art. The probe of the present embodiment is in elastic contact with the sample to be tested, and the probe pressure and position do not need to be manually adjusted during operation, which can effectively improve the testing efficiency and reduce the damage risk to the sample to be tested. By using the probe with elastic reset function, the probe can stably contact the sample to be tested during testing and reset after testing to protect the electrode sheet, which not only improves the adaptability of the probe and makes it applicable to samples with different surface properties and enables non-destructive testing, but also improves the accuracy of measurement results and protects the electrode sheet from wear during movement. In addition, gold-plated copper is selected as the electrode sheet material, which further reduces the contact resistance and system resistance, thereby improving the testing sensitivity and accuracy. The two outer electrode sheets are current input ends, and the two inner electrode sheets are voltage measurement ends, which, in combination with the advantages of four-terminal method and double-arm bridge method in low resistance material electrical testing, reduces the influence of additional resistance and optimizes the circuit current and voltage distribution, thereby realizing high-precision measurement of low resistance samples (<1Ω). The resilient four-probe conductivity testing device provided by the above-mentioned embodiments of the present application can ensure good contact state when facing uneven, flexible or brittle samples, can perform non-destructive testing on the sample to be tested, and has high measurement accuracy for low resistance samples. In summary, the present application has important engineering application prospects and technical innovation value.

[0036] In the above description, the description of known components and technologies is omitted to avoid unnecessary confusion of the concept of the present application. In each of the above-mentioned embodiments, each embodiment focuses on the differences from other embodiments, and the same / similar parts between each embodiment can be referred to each other.

[0037] It should be noted that, in the present document, relational terms such as "first" and "second", and the like can be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises... a" does not, without more constraints, exclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element. Additionally, the use of the term "a" or "an" preceding an element does not, without more constraints, exclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element. Furthermore, any reference to claim interpretation includes claim interpretation in both a restrictive sense and a permissive sense unless otherwise indicated.

[0038] The preferred embodiments of the application described above are intended to be merely exemplary and those skilled in the art will readily suggest modifications and improvements to the described embodiments without departing from the principles of the application.

Claims

1. A spring-loaded four-probe conductivity testing device, characterized in that, include: The device comprises a main body having a first surface and a second surface arranged opposite to each other, and a guide groove extending from the second surface to the first surface; four electrode plates, including two outer electrode plates and two inner electrode plates, which are housed within the guide groove and can extend and retract within the guide groove under the action of a telescopic mechanism. Each electrode plate serves as a probe and has a connecting end and a contact end arranged opposite to each other. The connecting end is fixedly connected to the bottom of the guide groove and to a measuring instrument via the telescopic mechanism. The contact end has a contact surface for contacting the sample to be tested. When the contact surface is not in contact with the sample to be tested, the telescopic mechanism can extend to cause the contact end to protrude beyond the second surface, thus putting the device in a test-ready state. When the contact surface contacts the sample to be tested and generates a first pressure, the telescopic mechanism can compress under the first pressure to cause the contact end to retract into the guide groove, thus putting the device in a test state.

2. The apparatus according to claim 1, characterized in that, The main body is made of engineering plastic, the electrode sheet is made of copper, and the contact surface has a protective layer; the electrode sheet is rectangular in shape, the electrode sheet is 0.25~0.35mm thick, and the contact surface has rounded chamfers.

3. The apparatus according to claim 1, characterized in that, The main body has four guide grooves inside, which are arranged at intervals along a first direction. Each electrode sheet is housed in one of the guide grooves, wherein the first direction is parallel to the first surface; the distance between the outer electrode sheet and the adjacent inner electrode sheet is 1.5mm-2.5mm, and the distance between two inner electrode sheets is 5.5mm-6.5mm.

4. The apparatus according to claim 1, characterized in that, The two outer electrode plates are used as current input terminals and are connected to the current output interface of the measuring instrument. The two inner electrode plates are used as voltage measurement terminals and are connected to the voltage acquisition interface of the measuring instrument. The wiring direction of the two current input terminals is consistent with the polarity of the test current. The two voltage measurement terminals are in contact with the same side of the sample to be tested.

5. The apparatus according to claim 1, characterized in that, The electrode plate has metal pins at its connecting end, which can be plugged into and fixed to a terminal block; a wire is crimped onto the terminal post of the terminal block, and the wire is connected to a measuring instrument.

6. The apparatus according to claim 5, characterized in that, The terminals are gold-plated; the wires are 1m or less in length and have a cross-sectional area of ​​0.5mm² or greater. 2 The conductors are low-impedance copper wires; the conductors connected to the voltage acquisition interface of the measuring instrument are twisted-pair wires and wrapped with a metal shielding layer.

7. The apparatus according to claim 1, characterized in that, The telescopic mechanism uses a spring, one end of which is fixedly connected to the bottom of the guide groove, and the other end is connected to the connecting end of the electrode plate; or the telescopic mechanism uses a piezoelectric ceramic actuator, which is disposed between the bottom of the guide groove and the connecting end of the electrode plate, and controls the displacement of the electrode plate according to the control signal.

8. The apparatus according to claim 1, characterized in that, It also includes a limiting structure disposed between the bottom of the guide groove and the connection end of the electrode sheet. The limiting structure is used to limit the distance by which the contact end of the electrode sheet protrudes from the second surface in the test preparation state, and to limit the distance by which the contact end of the electrode sheet protrudes from the second surface after retracting into the guide groove in the test state.

9. The apparatus according to claim 8, characterized in that, In the test preparation state, the contact ends of all the electrode plates protrude from the second surface by the same distance. In the test state, after the limiting structure restricts the contact ends to retract into the guide groove, the distance protruding from the second surface is greater than or equal to 2 mm.

10. The apparatus according to claim 1, characterized in that, The telescopic mechanism can be compressed under a second pressure to lock the electrode plate in a retracted position by engaging it with the main body, or to disengage the electrode plate from the main body and restore the device to a test-ready state; wherein the second pressure is greater than the first pressure.

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