Infrared thermal imaging acquisition module, detection system, method, resistance strain gauge adhesion micro-defect detection method and equivalent circuit

Abstract

Infrared thermal imaging acquisition module, detection system, method, resistance strain gauge adhesion micro-defect detection method and equivalent circuit, related to the field of non-destructive testing of resistance strain gauges. The detection and identification problems of resistance strain gauge adhesion micro-defects are solved. The detection method includes: the resistance strain gauge to be tested is fixed on the X-axis sample moving crawler; the positive and negative probe stations are respectively connected to the a terminal and b terminal of the resistance strain gauge to be tested; the medium-wave infrared thermal imager is adjusted to obtain the first grid line area of ​​the resistance strain gauge to be tested; the computer controls the control relay to close; the infrared thermal image sequence is transmitted back to the computer; the mobile station is adjusted according to the size of the resistance strain gauge to image other positions; until all terminals in the positive probe station and the resistance strain gauge to be tested are detected; the infrared feature image is processed by the feature enhancement image processing algorithm, and the resistance strain gauge adhesion micro-defect is judged in combination with the equivalent circuit structure. The present invention is applicable to the field of non-destructive testing.

Description

Technical Field

[0001] The invention relates to the field of nondestructive testing, and in particular to the field of electrical infrared thermal imaging testing of resistance strain gauges. Background Art

[0002] Resistance strain gauges are commonly used to measure the parameters of sensors such as force sensors, displacement sensors, strain sensors, velocity sensors, and acceleration sensors. They have the advantages of small structural size, high detection accuracy, stable and reliable performance, etc. They play an important role in precision measurement fields such as aerospace, ships, bridges, and scales. Common resistance strain gauges are thin-film substrate resistance strain gauges, which are often composed of a covering layer, a metal sensitive grid, an insulating adhesion layer, a substrate, and other parts. Under harsh and extreme working environments, the insulating adhesion layer of the resistance strain gauge fails in some parts, resulting in adhesion defects, causing changes in the insulation resistance or sensitive grid resistance, seriously affecting the static and dynamic characteristics of the resistance strain gauge, and even causing the strain gauge to fail. Therefore, the detection of adhesion defects in resistance strain gauges has important application value for monitoring the overall health and performance of strain gauges.

[0003] At present, the impedance analysis method is often used for strain gauge defect detection at home and abroad to perform impedance analysis on the insulation resistance and sensitive grid resistance of the strain gauge. The impedance analysis method performs impedance spectrum analysis on the resistance strain gauge. By comparing it with the impedance spectrum of the normal strain gauge, it can be qualitatively determined whether the strain gauge has defects, but the location of micro-adhesion defects cannot be obtained through impedance spectrum analysis.

[0004] Since the width of the sensitive grid line is often in the micron range, an optical microscope is usually used to detect the entire strain gauge area by area. The optical microscope can detect the shape and position of the surface sensitive grid, but the adhesion micro-defect is below the sensitive grid, and the optical microscope method cannot detect this type of defect. At the same time, the optical microscope is based on optical detection, which can detect transparent materials, but it is difficult to achieve non-destructive testing inside the material. Moreover, since the adhesion defect occurs in the local position of the insulating adhesion layer, the optical microscope often confuses the cover layer defect with the adhesion defect, so the misjudgment rate is high.

[0005] Prior art CN108416778A discloses a phase-locked thermal imaging tomography characterization system for integrated circuit micro-defects, which uses electrical excitation to realize integrated circuit excitation using sinusoidal currents of different frequencies, obtains phase information through a phase-locked algorithm, and determines defect depth information based on the intrinsic relationship between the defect and the phase. However, it is not applicable to resistance strain gauges because the adhesion micro-defects unique to strain gauges are at the micron level, and based on the unique characteristics of the resistance strain gauge grid line, it is also impossible to directly determine the defect location.

[0006] Currently, there is a lack of a reliable and fast imaging detection method to detect and identify adhesion micro-defects of resistance strain gauges. Summary of the invention

[0007] The invention solves the problem of detecting and identifying adhesion micro-defects of resistance strain gauges.

[0008] The present invention provides an infrared thermal imaging acquisition module, the acquisition module comprising:

[0009] Rotating motion table, medium wave infrared thermal imager, microscope lens, sample platform, X-axis sample moving track, X-axis moving table, Y-axis moving platform and Z-axis moving table;

[0010] A Y-direction moving platform is fixed on the upper surface of the sample platform, an X-direction moving platform is fixed on the Y-direction moving end of the Y-direction moving platform, the Y-direction moving end is used to drive the X-direction moving platform to reciprocate along the Y direction, and an X-direction sample moving crawler is provided on the X-direction moving platform, and the X-direction sample moving crawler is used to carry the sample to be tested to reciprocate in the X direction;

[0011] A Z-direction moving table is fixed on the upper surface of the sample platform, and the Z-direction moving table is provided with a Z-direction moving end, and the Z-direction moving end is fixedly connected to the rotary motion table, and the Z-direction moving end is used to drive the rotary motion table to reciprocate along the Z direction, and the rotating end at the bottom of the rotary motion table is fixedly connected to a medium-wave infrared thermal imager, and a microscope lens is fixed at the bottom of the medium-wave infrared thermal imager, and the medium-wave infrared thermal imager and the microscope lens are both located directly above the X-direction sample moving crawler, and the medium-wave infrared thermal imager is used to collect infrared images of the surface of the X-direction sample moving crawler, and the microscope lens is used to collect images of the surface of the X-direction sample moving crawler.

[0012] Furthermore, the single pixel resolution of the microscope lens is up to 3 μm.

[0013] The present invention also provides an infrared thermal imaging detection system, characterized in that the detection system comprises:

[0014] Negative probe station, positive probe station, acquisition module, relay, synchronous trigger, DC power supply and computer;

[0015] The acquisition module is the above-mentioned infrared thermal imaging acquisition module;

[0016] The negative electrode probe station and the positive electrode probe station are respectively connected to a DC power supply through a switch of a relay; the trigger signal output end of the synchronous trigger is connected to the control coil of the relay to control the closing or opening of the switch of the relay;

[0017] The synchronization trigger also sends a synchronization trigger signal to the medium-wave infrared thermal imager to trigger the medium-wave infrared thermal imager to collect infrared images;

[0018] The control signal input terminal of the synchronization trigger is connected to a computer;

[0019] The medium-wave infrared thermal imager sends the collected infrared image to the computer;

[0020] The microscope lens sends the acquired image to the computer.

[0021] The present invention also provides an infrared thermal imaging detection method, the detection method comprising:

[0022] The microscope lens collects the image of the moving track surface of the sample in the X direction and transmits it to the computer;

[0023] The computer controls the synchronous trigger to send out a frequency-adjustable square wave signal;

[0024] The square wave signal is sent as a trigger signal to the control end of the control coil of the relay to control the relay switch to close or open;

[0025] The square wave signal is also sent to the medium wave infrared thermal imager as a trigger signal to control the medium wave infrared thermal imager to collect infrared images, and the collected infrared images are transmitted to the computer for image processing and to obtain detection results.

[0026] The present invention provides a resistance strain gauge adhesion micro-defect detection method, comprising a resistance strain gauge to be tested, the detection method is implemented based on the above-mentioned infrared thermal imaging detection system, and the detection method comprises:

[0027] S1: Fix the resistance strain gauge to be tested on the upper surface of the X-axis sample moving track, and complete the collection of test data for the resistance strain gauge to be tested through steps S2 to S7;

[0028] S2: Connect the positive probe station to the a terminal of the resistance strain gauge to be measured, and connect the negative probe station to the b terminal of the resistance strain gauge to be measured;

[0029] S3: Turn on the DC power switch, adjust the focal length of the medium-wave infrared thermal imager, the rotary motion stage, the Y-axis moving platform, and the Z-axis moving stage, so that the medium-wave infrared thermal imager acquires the first grid line area of ​​the resistance strain gauge to be measured;

[0030] S4: Disconnect the DC power switch, adjust the connection between the negative probe station and the A terminal of the resistance strain gauge to be measured, and turn on the DC power switch;

[0031] S5: The computer sends a control instruction to control the synchronous trigger to send a trigger signal, and the trigger signal controls the relay to close; the current enters the resistance strain gauge to be measured, and at the same time, the mid-infrared thermal imager continuously collects multiple infrared thermal images and transmits them to the computer, and the computer obtains a set of image sequences;

[0032] S6: According to the size of the resistance strain gauge to be measured, by adjusting the Y-moving stage and the X-direction sample moving track, other positions of the resistance strain gauge to be measured are imaged, and step S5 is repeated until all the grid line areas of the resistance strain gauge to be measured are collected, and the DC power switch is turned off;

[0033] S7: respectively adjusting the connection between the positive electrode probe station and the b, c and d terminals of the resistance strain gauge to be measured, and after each adjustment, turning on the DC power switch, and repeating steps S5 and S6; completing the detection of the strain gauge to be measured in the state where the positive electrode probe station is respectively connected to each terminal a, b, c and d of the resistance strain gauge to be measured;

[0034] S8: The computer processes all the infrared thermal images obtained through a feature enhancement image processing algorithm to obtain an infrared feature image, and determines and locates the adhesion micro-defects of the resistance strain gauge based on the infrared feature image combined with the equivalent circuit structure.

[0035] Furthermore, the medium-wave infrared thermal imager is focused when the distance between the medium-wave infrared thermal imager and the resistance strain gauge to be measured is 70 mm.

[0036] Furthermore, the trigger signal is a square wave signal.

[0037] Furthermore, the feature enhancement image processing algorithm is a phase-locked algorithm.

[0038] Furthermore, the wavelength corresponding range of the medium-wave infrared thermal imager is 3 to 5 μm, the pixel is 640×512, and the maximum frequency of the full window is 140 Hz.

[0039] The present invention also provides an equivalent circuit structure, which is an equivalent circuit structure of adhesion micro-defects of a resistance strain gauge, and the equivalent circuit structure includes any one or more of the following five structures:

[0040] Structure 1: It includes four sensitive gate resistors R1, R2, R3, R4 and a contact resistor Rc, wherein the contact resistor Rc has an intermediate adjustable end, and the contact resistor Rc is connected in series in the detection loop. After the four sensitive gate resistors R1, R2, R3, R4 are connected in series, they are connected between the adjustable end of the contact resistor Rc and one end of the detection current source;

[0041] Structure 2: comprising three sensitive gate resistors R2, R3, R4, a sensitive gate shunt resistor R1-Rx, a sensitive gate shunt resistor Rx and a contact resistor Rc, wherein the sensitive gate resistors R2, R3, R4 and the sensitive gate shunt resistor Rx are connected in series and then connected in parallel with the sensitive gate shunt resistors R1-Rx to form a branch circuit 1, and the branch circuit 1 is connected in series with the contact resistor Rc in the detection loop;

[0042] Structure three: including four sensitive gate resistors R1, R2, R3, R4 and a contact resistor Rc. The sensitive gate resistors R2, R3, R4 are connected in series and then connected in parallel with the sensitive gate resistor R1 to form a branch one. The branch one is connected in series with the contact resistor Rc in the detection loop;

[0043] Structure 4: including three sensitive gate resistors R1, R3, R4, a sensitive gate shunt resistor R2-Rx, a sensitive gate shunt resistor Rx and a contact resistor Rc, the sensitive gate resistor R1 and the sensitive gate shunt resistor R2-Rx are connected in series to form a branch path 1, the sensitive gate resistors R3, R4 and the sensitive gate shunt resistor Rx are connected in series to form a branch path 2, and the path 1 and the path 2 are connected in parallel and connected in series with the contact resistor Rc in the detection loop;

[0044] Structure 5: includes four sensitive gate resistors R1, R2, R3, R4 and one contact resistor Rc. The sensitive gate resistors R1 and R2 are connected in series to form branch 1, and the sensitive gate resistors R3 and R4 are connected in series to form branch 2. The branch 1 and branch 2 are connected in parallel and connected in series with the contact resistor Rc in the detection circuit.

[0045] The present invention is beneficial in that:

[0046] The invention solves the problem of detecting and identifying adhesion micro-defects of resistance strain gauges.

[0047] (1) The prior art uses an impedance analysis method to analyze the impedance spectrum of the resistance strain gauge. By comparing it with the impedance spectrum of the normal strain gauge, it can qualitatively determine whether the strain gauge has defects, but the location of the micro-adhesion defect cannot be obtained through impedance spectrum analysis. The present invention uses electro-infrared thermal imaging detection technology to reliably and quickly detect the adhesion micro-defects of the resistance strain gauge: when the sensitive grid of the thin film substrate resistance strain gauge and the substrate have adhesion micro-defects, contact resistance is formed. Under the action of current, a heat source will be formed at the contact resistance. The detection and positioning of adhesion micro-defects are realized by combining infrared detection technology with relevant image processing algorithms. The physical process is clearer and the method is more reliable, which greatly improves the location of the sample and the determination of the cause of the defect, and improves the detection efficiency.

[0048] (2) The prior art uses an optical microscope for detection, which confuses coating defects with adhesion defects, resulting in a high misjudgment rate. At the same time, optical microscopes are based on optical detection and can detect transparent materials, but it is difficult to achieve non-destructive testing of the interior of materials. The present invention overcomes the bias of the prior art, adopts a high spatial resolution microscope lens, and uses an infrared thermal imaging detection method to use electric current to excite the sample, so that the sensitive grid and defect of the sample generate heat and emit infrared thermal radiation information. This method can detect surface and internal defects of the sample without being affected by the light transmittance of the material, avoids confusion between coating defects and adhesion defects, and can intuitively distinguish adhesion defects. It provides a powerful means for reliable and rapid non-destructive testing of resistance strain gauges, can replace traditional optical microscopic imaging detection methods, and has broad application prospects in the field of precision measurement.

[0049] (3) The present invention utilizes a non-contact imaging detection method to avoid the inability to distinguish other defects caused by contact from adhesion micro-defects; the non-contact imaging of the present invention improves the accuracy of detection.

[0050] (4) This application proposes an electric infrared thermal imaging detection method and system for micron-level adhesion micro-defects unique to strain gauges, and uses relays to achieve phase-locked or long pulse modulation. Compared with the direct use of DC power modulation in the prior art CN108416778A, it achieves higher frequency modulation. Since the modulation frequency is proportional to the infrared thermal resolution, the use of relay modulation can provide higher resolution and provide conditions for accurate resolution of micro-adhesion defects; secondly, based on the unique characteristics of the strain gauge grid line, an equivalent circuit diagram of defects at different positions is established. The effective sensitive grid area and defect separation and defect plane position information determination are achieved through the equivalent circuit diagram combined with the infrared characteristic image (including the amplitude and phase image obtained by the phase-locked algorithm, and other algorithms such as long pulse amplitude and phase image) instead of obtaining defect depth information through phase information.

[0051] (5) The present invention combines Ohm's law and the law of thermal radiation, and increases the thermal radiation at the adhesion micro-defects of the electroresistance strain gauge. It is not only suitable for the detection of adhesion micro-defects of the resistance strain gauge, but also suitable for the detection of defects such as sensitive grid size and spacing, broken grid, and terminals.

[0052] The invention is applicable to the field of nondestructive testing of sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1The electro-infrared thermal imaging detection system described in the embodiment of the present invention, in the figure: 1-rotating motion table, 2-medium-wave infrared thermal imager, 3-high spatial resolution microscope head, 4-sample platform, 5-negative probe station, 6-positive probe station, 7-X-axis sample moving crawler, 8-X-axis moving table, 9-Y-axis moving table, 10-strain gauge to be tested, 16-relay, 19-synchronous generator, 20-DC power supply, 23-computer, 25-Z-axis moving table;

[0054] Figure 2 The equivalent circuit structure of the adhesion micro-defect of the resistance strain gauge described in the sixth embodiment of the present invention is as follows: Figure 2 a is a schematic diagram of the power-on method of the resistance strain gauge, assuming that the positive electrode is connected to terminal 1 and the negative electrode is connected to terminal A of the substrate; Figure 2 b is a micro defect near the sensitive gate resistor R1; Figure 2 c There is a micro defect on the sensitive gate resistor R1; Figure 2 d. Micro defect at the connection line between sensitive gate resistor R1 and sensitive gate resistor R2; Figure 2 There is a micro defect on the e-sensitive gate resistor R2; Figure 2 f There is a micro defect in the connection between the sensitive gate resistor R2 and the sensitive gate resistor R3.

[0055] Figure 3 This is the infrared detection result of the sensitive gate described in Example 5 of the present invention.

[0056] Figure 4 This is an optical microscopic image of the fifth embodiment of the present invention, in which: 26 is a sensitive gate resistor R1, 27 is a sensitive gate resistor R2, 28 is a sensitive gate resistor R3, and 29 is a sensitive gate resistor R4.

[0057] Figure 5 This is a two-dimensional schematic diagram of the resistance strain gauge and the filamentary sensitive grid according to the fifth embodiment of the present invention. In the figure, c is the c terminal of the resistance strain gauge to be measured. DETAILED DESCRIPTION

[0058] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0059] Example 1, see Figure 1 The infrared thermal imaging acquisition module described in this embodiment includes:

[0060] Rotating motion table 1, medium wave infrared thermal imager 2, microscope lens 3, sample platform 4, X-axis sample moving crawler 7, X-axis moving table 8, Y-axis moving platform 9 and Z-axis moving table 25;

[0061] A Y-direction moving platform 9 is fixed on the upper surface of the sample platform 4, and an X-direction moving platform 8 is fixed on the Y-direction moving end of the Y-direction moving platform 9, and the Y-direction moving end is used to drive the X-direction moving platform 8 to reciprocate along the Y direction, and an X-direction sample moving crawler 7 is provided on the X-direction moving platform 8, and the X-direction sample moving crawler 7 is used to carry the sample to be tested to reciprocate in the X direction;

[0062] A Z-direction moving table 25 is fixed on the upper surface of the sample platform 4, and the Z-direction moving table 25 is provided with a Z-direction moving end, and the Z-direction moving end is fixedly connected to the rotary motion table 1, and the Z-direction moving end is used to drive the rotary motion table 1 to reciprocate along the Z direction. The rotating end at the bottom of the rotary motion table 1 is fixedly connected to a medium-wave infrared thermal imager 2, and a microscope lens 3 is fixed at the bottom of the medium-wave infrared thermal imager 2. The medium-wave infrared thermal imager 2 and the microscope lens 3 are both located directly above the X-direction sample moving crawler 7, and the medium-wave infrared thermal imager is used to collect infrared images of the surface of the X-direction sample moving crawler 7, and the microscope lens is used to collect images of the surface of the X-direction sample moving crawler 7.

[0063] In this embodiment, the medium-wave infrared thermal imager 2 has a focusing function, and by jointly adjusting the focal length of the X-axis moving stage 7, the Y-axis moving stage 8, the Z-axis moving stage 25, the rotary motion stage 1 and the medium-wave infrared thermal imager 2, the area of ​​the sample to be tested can be clearly seen in the medium-wave infrared thermal imager 2. The rotary motion stage 1 can realize the rotation of the sample along the Z direction, and can be used for collecting adhesion micro-defect information of the curved surface resistance strain gauge sample.

[0064] Embodiment 2: This embodiment further limits the infrared thermal imaging acquisition module described in Embodiment 1, and the maximum single resolution of the microscope lens is 3 μm.

[0065] Example 3, see Figure 1 The infrared thermal imaging detection system described in this embodiment includes:

[0066] Negative probe station 5, positive probe station 6, acquisition module, relay 16, synchronous trigger 19, DC power supply 20, computer 23;

[0067] The acquisition module is the infrared thermal imaging acquisition module described in Embodiment 1;

[0068] The negative electrode probe station 5 and the positive electrode probe station 6 are respectively connected to a DC power supply 20 through a switch of a relay 16; the trigger signal output end of the synchronous trigger 19 is connected to the control coil of the relay 16, which is used to control the closing or opening of the switch of the relay 16;

[0069] The synchronization trigger 19 also sends a synchronization trigger signal to the medium-wave infrared thermal imager 2 to trigger the medium-wave infrared thermal imager 2 to collect infrared images;

[0070] The control signal input terminal of the synchronization trigger 19 is connected to the computer 23;

[0071] The medium-wave infrared thermal imager 2 sends the collected infrared image to the computer 23;

[0072] The microscope lens 3 sends the acquired image to the computer 23 .

[0073] Embodiment 4: The infrared thermal imaging detection method described in this embodiment includes:

[0074] The microscope lens 3 collects the image of the surface of the moving track 7 of the sample in the X direction and transmits it to the computer;

[0075] The computer 23 controls the synchronous trigger 19 to emit a frequency-adjustable square wave signal;

[0076] The square wave signal is sent as a trigger signal to the control end of the control coil of the relay 16 to control the switch of the relay 16 to close or open;

[0077] The square wave signal is also sent as a trigger signal to the medium wave infrared thermal imager 2 to control the medium wave infrared thermal imager to collect infrared images, and the collected infrared images are transmitted to the computer 23 for image processing and to obtain detection results.

[0078] By using the detection method described in this embodiment, it is possible to determine whether the sample to be tested has defects and the location of the defects.

[0079] Example 5, see Figure 2 , Figure 3 , Figure 4 and Figure 5 The present embodiment is described in detail. The resistance strain gauge adhesion micro-defect detection method described in the present embodiment is implemented according to the infrared thermal imaging detection system described in the second embodiment, and the detection method includes:

[0080] S1: Fix the resistance strain gauge 10 to be tested on the upper surface of the X-axis sample moving track 7, and complete the collection of test data for the resistance strain gauge 10 to be tested through steps S2 to S7;

[0081] S2: Connect the positive probe station 5 to the a terminal of the resistance strain gauge to be measured, and connect the negative probe station 6 to the b terminal of the resistance strain gauge 10 to be measured;

[0082] S3: Turn on the DC power switch, adjust the focal length of the medium-wave infrared thermal imager 2, the rotary motion stage 1, the Y-axis moving platform 9 and the Z-axis moving stage 25, so that the medium-wave infrared thermal imager 2 acquires the first grid line area of ​​the resistance strain gauge 10 to be measured;

[0083] S4: Turn off the DC power switch, adjust the connection between the negative electrode probe station 6 and the A terminal of the resistance strain gauge 10 to be measured, and turn on the DC power switch;

[0084] S5: The computer 23 issues a control instruction to control the synchronous trigger 19 to issue a trigger signal, and the trigger signal controls the relay 16 to close; the current enters the resistance strain gauge 10 to be measured, and at the same time, the mid-infrared thermal imager 2 continuously collects multiple infrared thermal images and transmits them back to the computer 23, and the computer 23 obtains a set of image sequences;

[0085] S6: According to the size of the resistance strain gauge 10 to be measured, by adjusting the Y-moving stage 8 and the X-direction sample moving track 7, imaging other positions of the resistance strain gauge 10 to be measured, repeating step S5 until all the grid line areas of the resistance strain gauge 10 to be measured are collected, and disconnecting the DC power switch;

[0086] S7: respectively adjust the connection between the positive electrode probe station 5 and the terminals a, b, c and d of the resistance strain gauge to be measured, and after each adjustment, turn on the DC power switch, repeat steps S5 and S6, and complete the detection of the strain gauge 10 to be measured when the positive electrode probe station 5 is connected to each terminal a, b, c and d of the resistance strain gauge 10 to be measured;

[0087] S8: The computer processes all the infrared thermal images obtained through a feature enhancement image processing algorithm to obtain infrared feature images, and determines and locates the adhesion micro-defects of the resistance strain gauge based on the infrared feature images combined with the equivalent circuit structure.

[0088] like Figure 2 As shown, take the resistance strain gauge to be measured as an example with four sensitive grids: Figure 2 (a), where pad1~pad4 represent the sensitive gate access terminals, i.e. Figure 4 Each terminal a to d in the resistance strain gauge to be measured is equivalent, and A is the base terminal; Figure 2 (b) is the equivalent circuit structure under the micro-defect state near the sensitive gate resistor R1; Figure 2 (c) is the equivalent circuit structure when there is a micro defect on the sensitive gate resistor R1; Figure 2 (d) is the equivalent circuit structure under the micro-defect state at the connection between the sensitive gate resistor R1 and the sensitive gate resistor R2; Figure 2 (e) is the equivalent circuit structure when there is a micro defect on the sensitive gate resistor R2; Figure 2(f) is the equivalent circuit structure of the micro-defect state at the connection between the sensitive gate resistor R2 and the sensitive gate resistor R3. According to the infrared detection principle, any resistance (such as the sensitive gate resistor) can generate heat under the action of current. In the infrared image display, the above equivalent circuit structure can effectively screen the abnormal adhesion defect area.

[0089] like Figure 3 As shown, the resistance strain gauge 10 is composed of a transparent cover plate 31, a metal sensitive grid line layer 32, a thin film insulating layer 33, and a Ni-based stainless steel substrate 34. The left side of the enlarged part shows an optical microscope image, in which the grid line width is 30μm; the upper part of the enlarged part shows the infrared thermal imaging detection result of adhesion micro-defects, and the white line in the lower left corner of the figure indicates that the scale is 400μm.

[0090] like Figure 4 As shown, the distribution of sensitive gate resistors R1 (reference numeral 26), sensitive gate resistors R2 (reference numeral 27), sensitive gate resistors R3 (reference numeral 28) and sensitive gate resistors R4 (reference numeral 29) in the resistance strain gauge 10 can be clearly seen through the optical microscope image. It is difficult to find the location of adhesion micro-defects only by observing the microscope image. Therefore, infrared thermal imaging detection is further used to obtain the location and status of adhesion micro-defects.

[0091] The infrared characteristic image of the resistance strain gauge obtained according to the present invention is combined with Figure 2 The equivalent circuit diagram of the resistance strain gauge is used to determine and locate the adhesion micro-defects. When the negative probe station 5 is connected to the A terminal of the resistance strain gauge 10 to be tested and the positive probe station 6 is connected to the C terminal of the resistance strain gauge 10 to be tested, if the phase-locked amplitude result is as follows: Figure 5 As shown, it can be determined that the sensitive gate resistor R1 and the sensitive gate resistor R2 have thermal resistance in the vicinity. Figure 2 (f) It can be seen that the sensitive gate resistors R1 and R2 are normal, and the defect should occur between the sensitive gate resistors R2 and R3. According to the actual position, it can be determined that the defect is the damage of terminal c.

[0092] Embodiment 6: This embodiment further limits the resistance strain gauge adhesion micro-defect detection method described in Embodiment 5, and the medium-wave infrared thermal imager 2 is focused when the distance between the resistance strain gauge to be tested is 70 mm.

[0093] Embodiment 7: This embodiment further limits the resistance strain gauge adhesion micro-defect detection method described in Embodiment 5, and the trigger signal is a square wave signal.

[0094] Embodiment 8: This embodiment further limits the resistance strain gauge adhesion micro-defect detection method described in Embodiment 5, and the feature enhancement image processing algorithm is a phase-locked algorithm.

[0095] In practical applications, pulse thermal imaging, linear frequency modulation thermal imaging, photon flow and other feature image extraction algorithms can all be used to process infrared thermal image sequences.

[0096] Embodiment 9. This embodiment further limits the resistance strain gauge adhesion micro-defect detection method described in Embodiment 5. The corresponding wavelength range of the medium-wave infrared thermal imager 2 is 3 to 5 μm, the pixel is 640×512, and the maximum frequency of the full window is 140 Hz.

[0097] Example 10, see Figure 2 The present embodiment is described. The equivalent circuit structure described in the fifth embodiment of the present embodiment is an equivalent circuit structure of adhesion micro-defects of a resistance strain gauge, and the equivalent circuit structure includes any one or more of the following five structures:

[0098] Structure 1: See Figure 2 (b) as shown, comprising four sensitive gate resistors R1, R2, R3, R4 and a contact resistor Rc, the contact resistor Rc having an intermediate adjustable end, the contact resistor Rc being connected in series in the detection loop, the four sensitive gate resistors R1, R2, R3, R4 being connected in series, and then connected between the adjustable end of the contact resistor Rc and one end of the detection current source;

[0099] Structure 2: See Figure 2 (c) shows a structure including three sensitive gate resistors R2, R3, and R4, a sensitive gate shunt resistor R1-Rx, a sensitive gate shunt resistor Rx, and a contact resistor Rc. The sensitive gate resistors R2, R3, and R4 and the sensitive gate shunt resistor Rx are connected in series and then connected in parallel with the sensitive gate shunt resistors R1-Rx to form a branch circuit 1. The branch circuit 1 is connected in series with the contact resistor Rc in the detection loop.

[0100] Structure 3: See Figure 2 As shown in (d), it includes four sensitive gate resistors R1, R2, R3, R4 and a contact resistor Rc. The sensitive gate resistors R2, R3, R4 are connected in series and connected in parallel with the sensitive gate resistor R1 to form a branch one. The branch one is connected in series with the contact resistor Rc in the detection loop;

[0101] Structure 4: See Figure 2 (e) as shown, comprising three sensitive gate resistors R1, R3, R4, a sensitive gate shunt resistor R2-Rx, a sensitive gate shunt resistor Rx and a contact resistor Rc, the sensitive gate resistor R1 and the sensitive gate shunt resistor R2-Rx are connected in series to form a branch one, the sensitive gate resistors R3, R4 and the sensitive gate shunt resistor Rx are connected in series to form a branch two, and the path one and the path two are connected in parallel and connected in series with the contact resistor Rc in the detection loop;

[0102] Structure 5 See Figure 2As shown in (f), it includes four sensitive gate resistors R1, R2, R3, R4 and a contact resistor Rc. The sensitive gate resistors R1 and R2 are connected in series to form branch one, and the sensitive gate resistors R3 and R4 are connected in series to form branch two. The branch one and branch two are connected in parallel and connected in series with the contact resistor Rc in the detection circuit.

[0103] This embodiment is explained in conjunction with the fifth embodiment. Figure 2 This is the equivalent circuit diagram of the adhesion micro-defect distribution of four sensitive gate resistor strain gauges. The four sensitive gate resistors are represented by R1, R2, R3, and R4 respectively, and at this time, the positive pole of the external power supply is connected to the sensitive gate access terminal Pad1, and the negative pole is connected to the substrate. According to the definition of adhesion micro-defects, it means that there is adhesion between the sensitive gate resistor and the substrate material, which in turn generates a contact resistance Rc, and the order of magnitude of the contact resistance Rc is much smaller than that of the sensitive gate resistors R1, R2, R3, and R4. Assuming that the strain gauge does not have an adhesion defect, that is, the contact resistance Rc between the sensitive gate and the substrate material is infinite, current cannot be injected at this time, it is in an open circuit state, and no additional heat radiation is generated.

[0104] In practical applications, the following situations may exist:

[0105] 1) When the adhesion micro-defect is close to the sensitive gate access terminal Pad1, the contact resistance Rc generated by the adhesion micro-defect will be shunted, resulting in the contact resistance Rc being connected in series with the four sensitive gate resistors R1, R2, R3, and R4, forming an equivalent structure of structure 1. The equivalent structure diagram is shown in FIG. Figure 2 As shown in (b), the corresponding infrared characteristic image at this time is that the micro-defect and the four sensitive gates will have thermal responses, but the thermal responses of the four sensitive gates are caused by the shunt of the micro-defect, and the sensitive gate area is not a defect area.

[0106] 2) When the adhesion micro-defect occurs in the sensitive gate resistor R1, the adhesion micro-defect will significantly reduce the original resistance of the sensitive gate resistor R1, thereby causing the sensitive gate resistor R1 to shunt seriously, forming an equivalent structure of structure 2. The equivalent structure diagram is shown in FIG. Figure 2 As shown in (c), the corresponding infrared characteristic image at this time shows that the sensitive gate resistor R1 and the micro-defect area have different thermal responses, thereby locating the position of the micro-defect.

[0107] 3) When the adhesion micro-defect occurs at the connection line between the sensitive gate resistor R1 and the sensitive gate resistor R2, the adhesion micro-defect will cause the shunt of the sensitive gate resistor R1 to increase, forming an equivalent structure of structure three. The equivalent structure diagram is shown in FIG. Figure 2 As shown in (d), the corresponding infrared characteristic image at this time shows that the sensitive gate resistor R1 is seriously heated, while the other three sensitive gates are heated normally. At the same time, there is also a thermal response at the adhesion micro-defect, which can locate the position of the micro-defect.

[0108] 4) When the adhesion micro-defect occurs at the sensitive gate resistor R2, the adhesion micro-defect will significantly reduce the original resistance of the sensitive gate resistor 2, thereby causing the partial current shunting of the sensitive gate resistor R2 to be serious, forming an equivalent structure of structure 4. The equivalent structure diagram is shown in FIG. Figure 2 As shown in (e), the corresponding infrared characteristic image at this time shows that there is a difference in thermal response in the sensitive gate resistor R2 area, especially at the adhesion micro-defect, thereby realizing the positioning of the adhesion defect.

[0109] 5) When the adhesion micro defect occurs at the connection line between the sensitive gate resistor R2 and the sensitive gate resistor R3, an equivalent structure of structure 5 is formed. The equivalent structure diagram is as follows: Figure 2 As shown in (f), if the adhesion micro-defect is close to the sensitive gate resistor R2, it will cause the sensitive gate resistors R1 and R2 to shunt and increase at the adhesion micro-defect. At this time, the corresponding infrared characteristic image is that the heat generated by the sensitive gate resistors R1 and R2 and the adhesion micro-defect is higher than that of the sensitive gate resistors R3 and R4; conversely, it will cause the sensitive gate resistors R3 and R4 to shunt and increase at the adhesion micro-defect. At this time, the corresponding infrared characteristic image is that the heat generated by the sensitive gate resistors R3 and R4 and the adhesion micro-defect is higher than that of the sensitive gate resistors R1 and R2, thereby locating the position of the micro-defect.

Claims

1. Resistance strain gauge adhesion micro-defect detection method, characterized in that: The detection method is implemented based on an infrared thermal imaging detection system, and the infrared thermal imaging detection system includes: A negative electrode probe station (6), a positive electrode probe station (5), an acquisition module, a relay (16), a synchronous trigger (19), a direct current power supply (20) and a computer (23); The acquisition module is an infrared thermal imaging acquisition module; the acquisition module includes: A rotating motion stage (1), a medium-wave infrared thermal imager (2), a microscope lens (3), a sample platform (4), an X-axis moving stage (8), a Y-axis moving stage (9), and a Z-axis moving stage (25); A Y-direction moving platform (9) is fixed on the upper surface of the sample platform, an X-direction moving platform (8) is fixed on the Y-direction moving end of the Y-direction moving platform (9), the Y-direction moving end is used to drive the X-direction moving platform (8) to perform reciprocating motion along the Y-direction, an X-direction sample moving crawler (7) is provided on the X-direction moving platform (8), and the X-direction sample moving crawler (7) is used to carry the sample to be tested to perform reciprocating motion in the X-direction; A Z-direction moving table (25) is fixed on the upper surface of the sample platform (4), and the Z-direction moving table (25) is provided with a Z-direction moving end, and the Z-direction moving end is fixedly connected to the rotary motion table (1), and the Z-direction moving end is used to drive the rotary motion table (1) to perform reciprocating motion along the Z direction. The rotating end at the bottom of the rotary motion table (1) is fixedly connected to a medium-wave infrared thermal imager (2), and a microscope lens (3) is fixed at the bottom of the medium-wave infrared thermal imager (2). The medium-wave infrared thermal imager (2) and the microscope lens (3) are both located directly above the X-direction sample moving crawler (7), and the medium-wave infrared thermal imager (2) is used to collect infrared images of the surface of the X-direction sample moving crawler (7), and the microscope lens (3) is used to collect images of the surface of the X-direction sample moving crawler (7); The negative electrode probe station (6) and the positive electrode probe station (5) are respectively connected to a DC power supply (20) via a switch of a relay (16); a trigger signal output end of a synchronous trigger (19) is connected to a control coil of the relay (16) for controlling the closing or opening of the switch of the relay (16); The synchronization trigger (19) also sends a synchronization trigger signal to the medium-wave infrared thermal imager (2), triggering the medium-wave infrared thermal imager (2) to collect infrared images; The control signal input terminal of the synchronization trigger (19) is connected to a computer (23); The medium-wave infrared thermal imager (2) sends the collected infrared image to the computer (23); The microscope lens (3) sends the acquired image to the computer (23); The detection method comprises: S1: fixing the resistance strain gauge (10) to be tested on the upper surface of the X-axis sample moving track (7), and completing the collection of test data for the resistance strain gauge (10) to be tested through steps S2 to S7; S2: connecting the positive probe station (5) to the a terminal of the resistance strain gauge to be measured, and connecting the negative probe station (6) to the b terminal of the resistance strain gauge (10) to be measured; S3: Turning on the DC power switch, adjusting the focal length of the medium-wave infrared thermal imager (2), the rotary motion stage (1), the Y-axis motion platform (9), and the Z-axis motion stage (25), so that the medium-wave infrared thermal imager (2) acquires the first grid line area of ​​the resistance strain gauge (10) to be measured; S4: disconnecting the DC power switch, adjusting the connection between the negative electrode probe station (6) and the A terminal of the resistance strain gauge (10) to be measured, and turning on the DC power switch; S5: the computer (23) issues a control instruction to control the synchronous trigger (19) to issue a trigger signal, and the trigger signal controls the relay (16) to close; the current enters the resistance strain gauge (10) to be measured, and at the same time, the mid-infrared thermal imager (2) continuously collects a plurality of infrared thermal images and transmits them to the computer (23), and the computer (23) obtains a set of image sequences; S6: according to the size of the resistance strain gauge (10) to be measured, by adjusting the Y-moving stage (9) and the X-axis sample moving track (7), imaging other positions of the resistance strain gauge (10) to be measured, repeating step S5 until all grid line areas of the resistance strain gauge (10) to be measured are captured, and disconnecting the DC power switch; S7: respectively adjusting the connection between the positive electrode probe station (5) and the b, c and d terminals of the resistance strain gauge to be measured, and after each adjustment, turning on the DC power switch, repeating steps S5 and S6, and completing the detection of the resistance strain gauge (10) to be measured in the state where the positive electrode probe station (5) is respectively connected to each of the a, b, c and d terminals of the resistance strain gauge (10) to be measured; S8: The computer processes all the infrared thermal images obtained by a feature enhancement image processing algorithm to obtain infrared feature images, and determines and locates the adhesion micro-defects of the resistance strain gauge based on the infrared feature images combined with the equivalent circuit structure; The equivalent circuit structure includes any one or more of the following five structures: Structure 1: It includes four sensitive gate resistors R1, R2, R3, R4 and a contact resistor Rc, wherein the contact resistor Rc has an intermediate adjustable end, and the contact resistor Rc is connected in series in the detection loop. After the four sensitive gate resistors R1, R2, R3, R4 are connected in series, they are connected between the adjustable end of the contact resistor Rc and one end of the detection current source; Structure 2: comprising three sensitive gate resistors R2, R3, R4, a sensitive gate shunt resistor R1-Rx, a sensitive gate shunt resistor Rx and a contact resistor Rc, wherein the sensitive gate resistors R2, R3, R4 and the sensitive gate shunt resistor Rx are connected in series and then connected in parallel with the sensitive gate shunt resistors R1-Rx to form a branch circuit 1, and the branch circuit 1 is connected in series with the contact resistor Rc in the detection loop; Structure three: including four sensitive gate resistors R1, R2, R3, R4 and a contact resistor Rc. The sensitive gate resistors R2, R3, R4 are connected in series and then connected in parallel with the sensitive gate resistor R1 to form a branch one. The branch one is connected in series with the contact resistor Rc in the detection loop; Structure 4: including three sensitive gate resistors R1, R3, R4, a sensitive gate shunt resistor R2-Rx, a sensitive gate shunt resistor Rx and a contact resistor Rc, the sensitive gate resistor R1 and the sensitive gate shunt resistor R2-Rx are connected in series to form branch one, the sensitive gate resistors R3, R4 and the sensitive gate shunt resistor Rx are connected in series to form branch two, and the branch one and the branch two are connected in parallel and connected in series with the contact resistor Rc in the detection loop; Structure 5: includes four sensitive gate resistors R1, R2, R3, R4 and one contact resistor Rc. The sensitive gate resistors R1 and R2 are connected in series to form branch 1, and the sensitive gate resistors R3 and R4 are connected in series to form branch 2. The branch 1 and branch 2 are connected in parallel and connected in series with the contact resistor Rc in the detection circuit.

2. The resistance strain gauge adhesion micro-defect detection method according to claim 1, characterized in that: The single pixel resolution of the microscope lens (3) is at most 3 .

3. The resistance strain gauge adhesion micro-defect detection method according to claim 1, characterized in that: The medium-wave infrared thermal imager (2) is focused when the distance between the resistance strain gauge to be measured is 70 mm.

4. The resistance strain gauge adhesion micro-defect detection method according to claim 1, characterized in that: The trigger signal is a square wave signal.

5. The resistance strain gauge adhesion micro-defect detection method according to claim 1, characterized in that: The feature enhancement image processing algorithm is a phase-locked algorithm.

6. The resistance strain gauge adhesion micro-defect detection method according to claim 1, characterized in that: The wavelength of the medium-wave infrared thermal imager (2) corresponds to a range of 3 to 5 , the pixels are 640×512, and the maximum frequency of the full window is 140Hz.

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