On-line sheet resistance and resistivity tester with automatic calibration function

Abstract

The utility model discloses an on-line sheet resistance and resistivity tester with an automatic calibration function, relates to the field of solar silicon wafer testing, and is used for solving the problem that a calibration sheet needs to be manually taken in the calibration process of an existing sheet resistance tester, so that adverse effects are generated on the existing sheet resistance tester. The device comprises a test probe, a tested piece taking device, a tester MCU, a test platform, a cassette, a calibration piece and a calibration piece bin, the tester MCU is electrically connected with the test probe and the tested piece taking device respectively; the test probe performs test work or calibration work when receiving an electric signal output by the tester MCU; and the to-be-tested piece taking device performs taking work when receiving the electric signal output by the tester MCU. The label piece bin is of a drawing type structure, and a temperature control module and a humidity control module are arranged in the label piece bin. Through the arrangement of the tester MCU and the calibration piece bin, automatic calibration is realized, and the calibration piece contamination caused by manual taking of the calibration piece is avoided; and the influence of temperature and humidity changes on the calibration sheet is avoided through the temperature and humidity control module.

Description

Technical Field

[0001] The utility model relates to the field of solar silicon wafer testing, in particular to an automatic calibrated online square resistance and resistivity tester. Background Art

[0002] After a period of testing and use, the existing square resistance tester will cause errors in the instrument due to problems such as instrument noise inside the tester. When testing the tested piece, the test result will be inaccurate, which is called parameter drift. Therefore, when using the existing square resistance tester, it is often necessary to calibrate the parameters of the tester at regular intervals. If parameter drift is found, it is necessary to adjust the parameters set in the tester. At this time, in order to ensure the accuracy of the measurement, it is necessary to use an offline four-probe device to manually align the square resistance tester with the square resistance tester. The manual alignment process is: take out the piece tested by the online square resistance tester on the automated machine, and use the offline four-probe device to measure the square resistance. Then compare the square resistance difference between the two to obtain the square resistance difference coefficient. Fill the square resistance difference coefficient into the square resistance tester to achieve manual calibration. However, this manual calibration method has disadvantages. Each calibration process for the square resistance tester requires manual participation, which is not only a waste of time. More importantly, the calibration piece is easily contaminated when it is manually taken and placed. The surface of the calibration piece is damaged due to friction and other factors during the placement process. In addition, when the calibration piece is taken, its temperature and humidity change, which will also affect its calibration value.

[0003] How to solve the adverse effects of manual handling of the calibration film has become a key issue that needs to be solved urgently in this field.

[0004] Therefore, there is a need for an online square resistance and resistivity tester that does not require manual calibration and can maintain the temperature and humidity of the calibration piece. Utility Model Content

[0005] In order to solve the problems raised in the above background technology, the utility model provides an automatic calibration online square resistance and resistivity tester, which solves the current problems that the calibration sheet will be contaminated and damaged when it is manually taken and placed, and the temperature and humidity changes affect its calibration value.

[0006] To achieve the above-mentioned purpose, the utility model provides the following technical solutions: an automatic calibrated online square resistance and resistivity tester, wherein the automatic calibrated online square resistance and resistivity tester comprises a test probe, a device for picking up a piece under test, a tester MCU, a test platform, a dark box, a calibration piece and a calibration piece compartment; wherein the dark box is arranged on the test platform, a first control signal output end of the tester MCU is electrically connected to a driving end of the test probe, and a second control signal output end of the tester MCU is electrically connected to a controlled end of the device for picking up a piece under test;

[0007] The tester MCU is electrically connected to the test probe and the device for picking up the device under test respectively; when the test probe receives the electrical signal output by the tester MCU, it performs a test or calibration operation; when the device for picking up the device under test receives the electrical signal output by the tester MCU, it performs a picking operation;

[0008] The calibration wafer bin stores calibration wafers, and a partition board is arranged in the cassette, and a calibration groove is arranged on the top surface of the partition board; wherein, the calibration wafer bin is arranged below the partition board, and a probe hole is formed in the top surface of the cassette;

[0009] The cassette is arranged directly below the test probe. When performing a calibration operation, the test probe can directly pass through the probe hole formed in the top surface of the cassette, extend into the cassette, and approach the calibration wafer for calibration work.

[0010] The calibration wafer bin is of a drawer type structure, and when the calibration wafer bin is in the non-extracted state, its upper end is covered by the partition board, and the calibration wafer bin is hermetically closed; when the calibration wafer bin is extracted, its upper end is aligned with the calibration groove, and the calibration wafer is exposed below the test probe;

[0011] A temperature control module and a humidity control module are further arranged in the calibration wafer bin, and the tester MCU is electrically connected to the temperature control module and the humidity control module respectively.

[0012] Based on the above-mentioned on-line sheet resistance and resistivity tester with automatic calibration, further, a tester bracket is further included, and the tester bracket is movably connected to the test probe (1) and the test platform respectively.

[0013] Based on the above-mentioned on-line sheet resistance and resistivity tester with automatic calibration, further, the device for picking up the device under test is three automatic robotic arms, which are an X-axis robotic arm, a Y-axis robotic arm, and a Z-axis robotic arm respectively. The X-axis robotic arm is movably connected to the Z-axis robotic arm, and the Y-axis robotic arm is movably connected to the X-axis robotic arm; a clamping device is connected to the picking end of the Y-axis robotic arm, and the connecting end of the Z-axis robotic arm is fixedly connected to the tester bracket.

[0014] Based on the above-mentioned on-line sheet resistance and resistivity tester with automatic calibration, further, the cassette includes a test part and a storage part arranged from top to bottom, and the partition board is arranged between the test part and the storage part.

[0015] Based on the above-mentioned on-line sheet resistance and resistivity tester with automatic calibration, further, a displacement and lifting drive motor is further arranged in the storage part of the cassette, and the displacement and lifting drive motor is electrically connected to the tester MCU. When the displacement and lifting drive motor receives the electrical signal output by the tester MCU, it performs a displacement and lifting operation on the calibration wafer bin.

[0016] Based on the above-mentioned online sheet resistance and resistivity tester with automatic calibration, further, it further includes a display device, and the display device is electrically connected to the tester MCU.

[0017] Based on the above-mentioned online sheet resistance and resistivity tester with automatic calibration, further, a host computer is provided in the display device, and the host computer is a calculation and control module in the display device.

[0018] Based on the above-mentioned online sheet resistance and resistivity tester with automatic calibration, further, the temperature control module in the calibration chip bin includes a temperature sensor and a refrigeration chip, and the temperature sensor and the refrigeration chip are respectively arranged on the inner wall of the calibration chip bin; wherein, the signal output end of the temperature sensor is electrically connected to the tester MCU, and the signal input end of the refrigeration chip is electrically connected to the tester MCU.

[0019] Based on the above-mentioned online sheet resistance and resistivity tester with automatic calibration, further, the humidity control module in the calibration chip bin includes a humidity sensor and a dehumidifier interface, and the humidity sensor and the dehumidifier interface are respectively arranged on the inner wall of the calibration chip bin; wherein, the signal output end of the humidity sensor is electrically connected to the tester MCU, a dehumidifier is externally connected to the dehumidifier interface through a pipeline, and the signal input end of the dehumidifier is electrically connected to the tester MCU.

[0020] Based on the above-mentioned online sheet resistance and resistivity tester with automatic calibration, further, the test probe is a four-probe probe.

[0021] Working principle:

[0022] In the online sheet resistance and resistivity tester disclosed by the present utility model, the calibration process is actually a process of determining a new calibration coefficient for the tester. In this process, an original calibration coefficient (K_old) is stored in the tester MCU. According to

[0023] the calculation principle of K_new = R_std / (R_meas * K_old) (where R_std is the standard value of the calibration chip, R_meas is the current test result, K_old is the original calibration coefficient stored in the tester MCU, and K_new is the new calibration coefficient), the tester MCU automatically calculates a new calibration coefficient (K_new), and writes the new calibration coefficient (K_new) into the tester MCU to overwrite the original calibration coefficient (K_old); then perform a test again, and compare the standard value (R_std) of the calibration chip with (R_meas * K_new). If

[0024] R_std = R_meas * K_new, it means that the calibration is completed, and the new calibration coefficient (K_new) can be used to test the device under test.

[0025] The purpose of determining the new calibration coefficient is to address the issue of inaccurate test results when measuring the device under test due to errors in the tester, which is parameter drift. The new calibration coefficient can eliminate this error caused by parameter drift. Regular calibration can ensure accurate results when the tester measures the device under test.

[0026] Based on its working principle, it can be seen that the calibration process is actually a comparison calculation based on the calibration value of the calibration chip. Therefore, ensuring the accuracy of the calibration value of the calibration chip is an important operation in the calibration process.

[0027] Beneficial effects:

[0028] (1) The online sheet resistance and resistivity tester disclosed in the present utility model adopts an online automatic calibration method to calibrate the calibration chip. A calibration chip bin is provided. When not in calibration, the partition in the calibration chip bin and the dark box form a sealed and closed bin structure. When calibrating, the calibration chip bin is pulled out, the calibration chip is pushed to the lower end of the test probe, and the test probe extends into the dark box to approach the calibration chip for testing. After the test is completed, the calibration chip bin is pushed back. This automatic calibration method avoids complex manual operations and also eliminates the contamination of the calibration chip caused by repeatedly taking and placing the calibration chip during manual testing, as well as surface damage to the calibration chip due to factors such as friction and scratching during the placement of the calibration chip.

[0029] (2) The calibration chip bin of the online sheet resistance and resistivity tester disclosed in the present utility model is of a drawer structure. When the calibration chip bin is in the un-extracted state, its upper end is covered by the partition, and the calibration chip bin is sealed and closed. A temperature control module and a humidity control module are provided in the calibration chip bin. The temperature control module detects the ambient temperature in the calibration chip bin in real time, transmits the collected information to the tester MCU through an electrical signal, and the tester MCU processes the signal and feeds it back to the temperature control module to adjust the temperature in the calibration chip bin in a closed loop to achieve constant temperature control in the calibration chip bin. At the same time, the humidity control module detects the ambient humidity in the calibration chip bin in real time, transmits the collected information to the tester MCU through an electrical signal, and the tester MCU processes the signal and feeds it back to the humidity control module to adjust the humidity in the calibration chip bin in a closed loop to achieve constant humidity control in the calibration chip bin. Through this constant temperature and humidity calibration chip bin, the calibration chip bin is always in the most suitable storage environment. And even during the calibration work, the temperature and humidity in the calibration bin will not change in a short time. After the calibration is completed, the calibration chip bin is pushed back again to form a constant temperature and humidity closed environment. This calibration chip bin can well ensure that the calibration chip is always in the most suitable temperature and humidity for storage, ensuring that it is not affected by the temperature and humidity changes caused by the manual taking of the calibration process, ensuring the accuracy and constancy of its calibration value, and greatly improving the service life of the calibration chip.

[0030] (3) The on-line sheet resistance and resistivity tester disclosed by the present utility model further includes a display device, which is electrically connected to the tester MCU. A host computer is provided in the display device. The host computer is a calculation and control module in the display device. The host computer records the measured value (R_measured) during the calibration process of the tester and the standard value (R_standard) of the calibration wafer, and displays them in the display device. The temperature control module and the humidity control module collect information and transmit it to the tester MCU. The display device receives the information transmitted by the tester MCU and displays it. Relevant data can be seen in real time through the display device, so as to facilitate the monitoring and management of the working state of the tester.

[0031] (4) In the on-line sheet resistance and resistivity tester disclosed by the present utility model, the temperature control module in the calibration wafer bin includes a temperature sensor and a refrigeration sheet, and the humidity control module includes a humidity sensor and a dehumidifier interface. When the temperature sensor detects that the temperature in the calibration wafer bin rises, the refrigeration sheet starts to work. When it detects that the temperature drops, the power supply of the refrigeration sheet works in the reverse direction to heat the calibration wafer bin. When the humidity sensor detects that the humidity in the calibration wafer bin rises, the dehumidifier is started to reduce the humidity in the calibration wafer bin through the dehumidifier interface. This closed-loop control method realizes the effect of automatically adjusting the temperature and humidity, eliminating the need for manual control and adjustment, and reducing the impact of manual operation on the calibration wafer. Description of the Drawings

[0032] Figure 1 It is a schematic structural diagram of the dark box in the embodiment of the present utility model;

[0033] Figure 2 It is a schematic structural diagram of the device for taking and placing the test piece in the embodiment of the present utility model;

[0034] Figure 3 It is a block diagram of the overall structure in Embodiment 1 and Embodiment 2 of the present utility model;

[0035] Figure 4 It is a block diagram of the overall structure in Embodiment 3 of the present utility model.

[0036] In the figure: 1. Test probe; 2. Device for taking and placing the test piece; 3. Dark box; 4. Calibration wafer; 5. Calibration wafer bin; 6. Test section; 7. Storage section; 8. Partition board; 9. Probe hole; 10. X-axis robotic arm; 11. Y-axis robotic arm; 12. Z-axis robotic arm; 13. Clamping device; 14. Solar silicon wafer storage bin. Detailed Embodiments

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the present invention will be briefly introduced below in combination with the accompanying drawings and the description of the embodiments or the prior art. Obviously, the following description of the structures of the accompanying drawings is only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings. It should be noted here that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation to the present invention.

[0038] Embodiment 1:

[0039] As Figure 1 , shown in Figures 2 and 3, an on-line sheet resistance and resistivity tester with automatic calibration provided in this embodiment includes a test probe 1, a device 2 for taking the test piece, a tester MCU, a test platform, a dark box 3, a calibration piece 4, and a calibration piece bin 5. Among them, the dark box 3 includes a test part 6 and a storage part 7 arranged from top to bottom. A partition plate 8 is arranged between the test part 6 and the storage part 7, and the dark box 3 is arranged on the test platform.

[0040] See Figure 1 , Figure 3, for an on-line sheet resistance and resistivity tester with automatic calibration provided in this embodiment, the first control signal output end of the tester MCU is electrically connected to the driving end of the test probe 1; when the test probe 1 receives the electrical signal output by the tester MCU, it performs calibration work. A program for timed automatic calibration is set in the tester MCU. In the tester provided in this embodiment, it is preferably set that 30 days is taken as a calibration cycle, and calibration work is automatically performed at regular intervals. When the automatic calibration work is started, the first control signal output end of the tester MCU outputs a calibration start signal. At this time, the calibration piece bin 5 in the dark box 3 is pulled out from the storage part 7 in the dark box 3, and the upper end of the calibration piece bin 5 is separated from the partition plate 8 and exposed. The test probe 1 receives the start signal output by the tester MCU, passes the test probe 1 through the probe hole 9 opened in the test part 6 of the dark box 3, and extends into the dark box 3. At this time, the upper end of the calibration piece bin 5 is aligned with the calibration groove on the partition plate 8 in the dark box 3, and the calibration piece 4 placed in the calibration piece bin 5 is just exposed below the test probe 1. The test probe 1 approaches the calibration piece 4 for testing. Through the test by the test probe 1, a result, namely (R measured), will be obtained at the tester MCU; the tester MCU calculates a new calibration coefficient (K new), writes the new calibration coefficient (K new) into the tester MCU, and overwrites the original calibration coefficient (K old); then a test is performed again, and the calibration value (R standard) of the calibration piece 4 is compared with (R measured * K new). If they are consistent, the calibration is completed. After the calibration is completed, the calibration piece bin 5 is pushed back into the storage part 7, and the upper end of the calibration piece bin 5 and the partition plate 8 form a sealed and closed environment again.

[0041] SeeFigures 1-3 In this embodiment, the first control signal output terminal of the MCU of the automatically calibrated on-line sheet resistance and resistivity tester is electrically connected to the driving end of the test probe 1, and the second control signal output terminal of the tester MCU is electrically connected to the controlled end of the device 2 for picking up the device under test; when the test probe 1 receives the electrical signal output by the tester MCU, it performs the test work; when the device 2 for picking up the device under test receives the electrical signal output by the tester MCU, it performs the picking up work. The tester MCU is in the on-line working mode and will automatically test the solar silicon wafer under test. The test of the solar silicon wafer under test is in the form of spot checks. Taking one test work as an example: the second control signal output terminal of the tester MCU outputs a test start signal, and the device 2 for picking up the device under test and the test probe 1 start to work after receiving the start signal output by the tester MCU. The device 2 for picking up the device under test randomly clamps a solar silicon wafer from an external solar silicon wafer storage bin 14 as the device under test, places it on the test platform, and at the same time the test probe 1 approaches the device under test for testing, and feeds back the measured sheet resistance value to the tester MCU, that is, the test is completed. After the test is completed, the device for picking up the device under test clamps the device under test away from the test platform and returns it to the solar silicon wafer storage bin 14.

[0042] See Figure 1 3. In the automatically calibrated on-line sheet resistance and resistivity tester provided in this embodiment, the calibration chip bin 5 has a drawer structure. When the calibration work is not carried out, the calibration chip 4 is always placed in the calibration chip bin 5. The upper end of the calibration chip bin 4 is covered by a partition plate 8 to form a sealed and closed environment; a temperature control module and a humidity control module are arranged in the calibration chip bin 5. The temperature control module detects the ambient temperature in the calibration chip bin 5 in real time, transmits the collected information to the tester MCU through an electrical signal, and the tester MCU processes the signal and feeds it back to the temperature control module to adjust the temperature in the calibration chip bin 5 in a closed loop to achieve constant temperature control in the calibration chip bin 5; at the same time, the humidity control module detects the ambient humidity in the calibration chip bin 5 in real time, transmits the collected information to the tester MCU through an electrical signal, and the tester MCU processes the signal and feeds it back to the humidity control module to adjust the humidity in the calibration chip bin 5 in a closed loop to achieve constant humidity control in the calibration chip bin 5. Through this calibration chip bin 5 with constant temperature and humidity, the calibration chip bin 5 is always in the most suitable storage environment, and even when the calibration work is carried out, the temperature and humidity in the calibration bin 5 will not change in a short time. After the calibration is completed, the calibration chip bin 5 will be pushed back again to form a constant temperature and humidity closed environment again.

[0043] In the tester provided in this embodiment, the tester MCU is preferably of the STM32 series such as stm32F103, stm32F105, stm32F107, etc., or chips such as dsPIC30F4011 / 4012 are selected.

[0044] Embodiment 2:

[0045] As Figure 3 shown, an on-line sheet resistance and resistivity tester with automatic calibration provided in this embodiment, in an implementable embodiment, further includes a display device, and the display device is electrically connected to the tester MCU. Preferably, a serial port protocol is used for communication connection; a host computer is provided in the display device, and the host computer is a calculation and control module in the display device. It receives the information transmitted by the tester MCU and records it. These information include the measured value (R_measured) during the calibration process and the standard value (R_standard) of the calibration wafer 4, the measured value of the device under test during the test process, and the temperature and humidity information collected by the temperature control module and humidity control module in the calibration wafer bin 5 in real time; and displays this information in the display device.

[0046] For the on-line sheet resistance and resistivity tester with automatic calibration provided in this embodiment, the staff can see the relevant test data and temperature and humidity data in real time through the display device, so as to monitor and manage the working state of the tester.

[0047] Embodiment 3:

[0048] As Figure 1 , Figures 3 and 4 shown, an on-line sheet resistance and resistivity tester with automatic calibration provided in this embodiment, in an implementable embodiment, a displacement lifting drive motor is provided in the dark box 3. During calibration, the displacement lifting drive motor is used to receive the control signal of the tester MCU, and pull out the calibration wafer bin 5 from the storage part in the dark box and lift it to the calibration slot. The temperature control module in the calibration wafer bin 5 is a temperature sensor and a refrigeration sheet, and the humidity control module is a humidity sensor and a dehumidifier interface. When the temperature sensor detects that the temperature in the calibration wafer bin 5 rises, it transmits a signal to the tester MCU. The tester MCU processes the signal and feeds it back to the refrigeration sheet, and the power supply of the refrigeration sheet works in the forward direction to cool the calibration wafer bin 5. When the temperature sensor detects that the temperature drops, it transmits a signal to the tester MCU. The tester MCU processes the signal and feeds it back to the refrigeration sheet, and the power supply of the refrigeration sheet works in the reverse direction to heat the calibration wafer bin 5. When the humidity sensor detects that the humidity in the calibration wafer bin 5 rises, it transmits a signal to the tester MCU. The tester MCU processes the signal and feeds it back to the external dehumidifier, and the dehumidifier starts and reduces the humidity of the calibration wafer bin 5 through the dehumidifier interface. This closed-loop control method for the temperature and humidity in the calibration wafer bin 5 achieves the effect of automatic adjustment, and there is no need for manual real-time control and adjustment of its temperature and humidity. It can control the temperature and humidity changes in the first time, avoiding the delay of manual control and the influence of complex manual operations on the calibration wafer.

[0049] Finally, it should be noted that the above are only the preferred embodiments of the present utility model and are not intended to limit the protection scope of the present utility model. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. An automatic calibration online square resistance and resistivity tester, characterized in that: The automatic calibration online square resistance and resistivity tester comprises a test probe (1), a device for picking up a test piece (2), a tester MCU, a test platform, a dark box (3), a calibration piece (4) and a calibration piece chamber (5); wherein the dark box (3) is arranged on the test platform, a first control signal output end of the tester MCU is electrically connected to a driving end of the test probe (1), and a second control signal output end of the tester MCU is electrically connected to a controlled end of the device for picking up a test piece (2); The calibration film (4) is stored in the calibration film bin (5), a partition plate (8) is provided in the dark box (3), and a calibration groove is provided on the top surface of the partition plate (8); wherein the calibration film bin (5) is arranged below the partition plate (8), and a probe hole (9) is provided on the top surface of the dark box (3); The label chamber (5) is a pull-out structure, and when the label chamber (5) is in a non-pulled-out state, its upper end is covered by the partition plate (8), and the label chamber (5) is sealed and closed; when the label chamber (5) is pulled out, its upper end is aligned with the calibration groove, and the calibration sheet (4) is exposed below the test probe (1); The labeling chamber (5) is also provided with a temperature control module and a humidity control module, and the tester MCU is electrically connected to the temperature control module and the humidity control module respectively.

2. The automatic calibration online square resistance and resistivity tester according to claim 1, characterized in that: It also includes a tester bracket, which is movably connected to the test probe (1) and the test platform respectively.

3. The automatic calibration online square resistance and resistivity tester according to claim 2, characterized in that: The test piece picking device (2) is composed of three automatic robotic arms, which are an X-axis robotic arm (10), a Y-axis robotic arm (11) and a Z-axis robotic arm (12). The X-axis robotic arm (10) is movably connected to the Z-axis robotic arm (12), and the Y-axis robotic arm (11) is movably connected to the X-axis robotic arm (10); the picking end of the Y-axis robotic arm (11) is connected to a clamping device (13), and the connecting end of the Z-axis robotic arm (12) is fixedly connected to the tester bracket.

4. The automatic calibration online square resistance and resistivity tester according to claim 1, characterized in that: The dark box (3) comprises a testing portion (6) and a storage portion (7) arranged from top to bottom, and the partition plate (8) is arranged between the testing portion (6) and the storage portion (7).

5. The automatic calibration online square resistance and resistivity tester according to claim 4, characterized in that: A displacement and lifting drive motor is also provided in the storage portion (7) of the dark box (3). The displacement and lifting drive motor is electrically connected to the tester MCU. When the displacement and lifting drive motor receives an electrical signal output by the tester MCU, it performs displacement and lifting work on the label bin (5).

6. The automatic calibration online square resistance and resistivity tester according to claim 1, characterized in that: It also includes a display device, which is electrically connected to the tester MCU.

7. The automatic calibration online square resistance and resistivity tester according to claim 6, characterized in that: The display device is provided with a host computer, which is a calculation control module in the display device.

8. The automatic calibration online square resistance and resistivity tester according to claim 1, characterized in that: The temperature control module in the labeling chamber (5) comprises a temperature sensor and a cooling plate, and the temperature sensor and the cooling plate are respectively arranged on the inner wall of the labeling chamber (5); wherein the signal output end of the temperature sensor is electrically connected to the tester MCU, and the signal input end of the cooling plate is electrically connected to the tester MCU.

9. The automatic calibration online square resistance and resistivity tester according to claim 1, characterized in that: The humidity control module in the labeling chamber (5) comprises a humidity sensor and a dehumidifier interface, and the humidity sensor and the dehumidifier interface are respectively arranged on the inner wall of the labeling chamber (5); wherein the signal output end of the humidity sensor is electrically connected to the tester MCU, the dehumidifier interface is externally connected to a dehumidifier through a pipeline, and the signal input end of the dehumidifier is electrically connected to the tester MCU.

10. The automatic calibration online square resistance and resistivity tester according to claim 1, characterized in that: The test probe (1) is a four-probe probe.

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