A method and device for detecting the thickness of a hole layer in a multi-layer PCB

Abstract

This application relates to the field of PCB board inspection technology, and in particular to a method and equipment for detecting the thickness of internal holes in multilayer PCB boards. The inspection method includes: loading the PCB board; obtaining the position of the hole to be tested on the PCB board; obtaining the edge position of the hole to be tested and using it as a reference point; using the reference point as a reference point, extending a probe into the hole to be tested by a preset distance; the probe emitting laser light around the hole and collecting the reflected laser light; obtaining the reflected light energy value based on the reflected laser light; obtaining the conductive layer thickness value based on the reflected light energy value; determining whether the conductive layer thickness value is qualified; and extending the probe until the inspection is completed. After the probe is inserted, it emits laser light and collects the laser emission signal, converting the laser emission signal into a reflected light energy value to obtain and compare the conductive layer thickness. This eliminates the need for cutting open the hole for manual inspection, improving inspection efficiency and accuracy while ensuring product integrity, and enhancing the inspection speed, quality, and yield of the product.

Description

Technical Field

[0001] This application relates to the field of PCB board testing technology, and in particular to a method and testing equipment for detecting the thickness of inner holes in multilayer PCB boards. Background Technology

[0002] After production, the conductive layer thickness of multilayer PCBs needs to be tested. The current conventional testing method is the fragmentation test method: the test hole reserved in the PCB is cut horizontally / vertically to make a slice sample. The cross-section of the hole wall is observed through a microscope. Then, the copper layer thickness is manually calculated and the integrity of the hole wall is judged based on the microscopic image. The conductive layer thickness and hole wall integrity information are obtained and compared and judged.

[0003] However, this inspection method requires cutting open the hole to be tested. On the one hand, cutting directly damages the structural integrity of the conductive layer on the hole wall, making the hole unrecoverable and resulting in PCB board waste. In particular, batch inspection generates a large amount of waste, increasing material and processing costs. On the other hand, manual sampling, observation, calculation, and comparison are required, which is not only cumbersome but also makes the inspection accuracy and efficiency dependent on manual labor. It cannot perform full inspection, which limits the inspection quality, speed, and product yield, making it difficult to meet the needs of high-quality mass production. Summary of the Invention

[0004] The purpose of this application is to provide a method and equipment for detecting the thickness of inner holes in multilayer PCBs, aiming to improve the problems of large material loss and limited detection quality and speed in the manual fragmentation detection method used in related technologies, improve the detection speed and accuracy of PCBs, and increase the product production yield.

[0005] On one hand, embodiments of this application provide a method for detecting the thickness of internal vias in a multilayer PCB board, including the following steps: Feed the PCB board into the preset shape. Find the location of the hole to be tested on the PCB board; Obtain the edge position of the hole to be tested, and use this edge position as a reference point; Using a reference point as a benchmark, insert the probe into the hole to be tested. The distance the probe extends into the hole is a preset distance. The probe emits laser light into the perimeter of the hole to be tested and collects the reflected laser light. The reflected light energy value is obtained based on the reflected laser, and the conductive layer thickness value is obtained based on the reflected light energy value; Determine whether the thickness of the conductive layer is acceptable; The probe continues to extend until the test is complete.

[0006] Furthermore, the step of "obtaining the reflected light energy value based on the reflected laser, and obtaining the conductive layer thickness value based on the reflected light energy value" specifically involves: transmitting the reflected laser to an optical power detection unit, the optical power detection unit obtaining the reflected light energy value based on the reflected laser, the reflected light energy value including the reflected light power, recording the reflected light energy value and the reflection position at this time; and obtaining the conductive layer thickness value by comparing the reflected light energy value with a preset reflected light energy value.

[0007] Furthermore, the step of "obtaining the conductive layer thickness by comparing the reflected light energy value with the preset reflected light energy value" specifically involves: simulating environments with different conductive layer thicknesses in advance, injecting a reflected laser and collecting and calculating the corresponding reflected light energy value, so that the conductive layer thickness corresponds to a corresponding reflected light energy value; and obtaining the corresponding conductive layer thickness based on the reflected light energy value.

[0008] Furthermore, the step of "obtaining the edge position of the hole to be tested and using the edge position as a reference point" specifically involves: using a zero-position sensor to detect the edge part of the hole to be tested, driving the zero-position sensor to continuously approach the edge part, and recording the position of the zero-position sensor at this time as the reference point when the zero-position sensor reacts or reads.

[0009] Furthermore, the step of "the probe emits laser light around the perimeter of the hole to be tested and collects the reflected laser light" specifically involves: inserting the probe into the hole to be tested, emitting laser light towards the inner wall of the hole to be tested, and collecting the laser light reflected from the inner wall of the hole to be tested; after collection, the probe rotates at a preset angle and continues to emit laser light towards the inner wall of the hole to be tested until the probe has completed laser collection around the entire inner wall of the hole to be tested.

[0010] Furthermore, the step of "the probe continues to extend" is as follows: the probe continues to extend, and during the extension process, the probe continuously emits reflected laser light and collects the reflected light energy value. If the reflected light energy value is collected, the probe stops, emits laser light around the inner wall at that position and collects the reflected laser light, and obtains and judges the thickness value of the conductive layer.

[0011] Furthermore, the step of "obtaining the position of the hole to be tested on the PCB board" specifically involves scanning the PCB board using visual positioning to obtain the position of the hole to be tested on the PCB board.

[0012] On the other hand, this application provides a detection device that uses the multilayer PCB board inner hole thickness detection method as described above, including a vertical feeding structure and a detection structure; the vertical feeding structure includes a conveying guide rail and a vertical clamping assembly slidably connected to the conveying guide rail; the detection structure includes a detection base, a backlight assembly disposed on the detection base, a sliding assembly, and a probe assembly disposed on the sliding assembly, the probe assembly being able to approach or move away from the conveying guide rail.

[0013] Furthermore, the sliding assembly includes a lifting guide rail disposed on the detection base and a probe support seat disposed on the lifting guide rail. The probe support seat is provided with multiple guide rails, and the probe assembly is disposed on the multiple guide rails.

[0014] Furthermore, the probe assembly includes a positioning vision sensor, a zero-position sensor, and an optical fiber probe rotatably connected to the multi-guide rail, all mounted on the multi-guide rail.

[0015] The beneficial effects of this application are: 1. This application discloses a method for detecting the thickness of internal holes in a multilayer PCB board. By detecting and acquiring the position of the hole to be tested on the PCB, and using the edge of the hole as a reference point, the probe is inserted. This ensures that the probe is driven to extend with the real-time edge position of the hole as a reference during each test, thereby avoiding reference deviations caused by dimensional errors of different PCB boards. After the probe is inserted, it emits a laser and collects the laser emission signal, converting the laser emission signal into reflected light energy value to acquire and compare the conductive layer thickness. This method can quickly acquire and compare the conductive layer thickness, replacing manual methods, thus effectively improving detection efficiency and accuracy. At the same time, it eliminates the need to cut open the hole for testing, thereby ensuring the structural integrity of the PCB board and reducing detection costs. Furthermore, it allows for sequential testing of all PCB boards to achieve full inspection, ensuring product testing speed, quality, and yield.

[0016] 2. The method for detecting the thickness of the inner hole of a multilayer PCB board disclosed in this application simulates different conductive layer thicknesses and laser emission environments in advance, so that the conductive layer thickness corresponds to a corresponding reflected light energy value. During detection, the probe can quickly obtain the corresponding conductive layer thickness value by collecting the reflected light energy value without complicated calculations, thereby simplifying the algorithm process, speeding up the detection efficiency, and improving the detection accuracy.

[0017] 3. The testing equipment of this application, by setting up a vertical feeding structure and a testing structure, the vertical feeding structure and the testing structure cooperate with each other to enable the PCB board to be fed vertically and then tested by the testing structure. In the vertical state, the testing structure can test the hole to be tested at multiple angles and through the position of the hole to be tested through the sliding component, thereby realizing comprehensive testing of multiple positions in the hole to be tested, reducing the blind spot of the test, and meeting the needs of higher precision testing. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the steps of a method for detecting the thickness of an inner hole in a multilayer PCB provided in Embodiment 1 of this application; Figure 2 This is a schematic diagram of the vertical feeding structure in a testing device provided in Embodiment 2 of this application; Figure 3This is a schematic diagram of the detection structure in a detection device provided in Embodiment 2 of this application; Figure 4 This is a schematic diagram of the fiber optic probe provided in Embodiment 2 of this application performing detection.

[0019] Explanation of reference numerals in the attached figures: 1. Vertical feeding structure; 11. Conveying guide rail; 12. Vertical clamping assembly; 2. Detection structure; 21. Backlight assembly; 22. Probe assembly; 221. Positioning vision sensor; 222. Zero position sensor; 223. Fiber optic probe. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0021] It should be noted that although functional modules are divided in the device schematic diagram and a logical order is shown in the flowchart, in some cases, the steps shown or described may be performed in a different order than the module division in the device or the order in the flowchart. The terms "first," "second," etc., in the specification, claims, and the aforementioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.

[0023] Example 1 Reference Figure 1 On the one hand, embodiments of this application provide a method for detecting the thickness of inner holes in a multilayer PCB board, including the following steps: S1: Loading PCB board, feeding the PCB board in a preset shape; Specifically, the PCB board to be tested is fed in a preset shape to facilitate the testing structure. In this embodiment, the PCB board is fed in an upright position.

[0024] S2: Obtain the location of the hole to be tested on the PCB board; Specifically, the PCB board is scanned using a visual positioning method to obtain the position of the hole to be tested on the PCB board. Specifically, a positioning visual sensor can be used to locate the hole to be tested. In this embodiment, a CCD camera is used to locate the hole to be tested, thereby obtaining the coordinates of the hole to be tested to cooperate with subsequent positioning.

[0025] S3: Obtain the edge position of the hole to be tested, and use this edge position as a reference point; Specifically, based on the coordinates of the hole to be measured in S2, a zero-position sensor is used to detect the edge of the hole. The zero-position sensor is driven to continuously approach the edge. When the zero-position sensor reacts or reads a value, its position is recorded as a reference point. The zero-position sensor can be a contact-type pressure sensor or a resistance sensor. A contact-type sensor gradually approaches and contacts a designated position or contact point on the edge of the hole. When the sensor reads a value, the edge of the hole can be identified, and this edge position is set as the reference point. Alternatively, the zero-position sensor can also be a non-contact sensor, such as an infrared sensor, which can also obtain the position of the edge.

[0026] S4: Using the reference point as the benchmark, insert the probe into the hole to be tested. The distance the probe extends is the preset distance. Specifically, based on the reference point obtained by S3, the reference point is used as the zero point of reference. The probe is inserted into the hole to be tested. Since the position of the conductive layer in the multilayer PCB, that is, the distance between the conductive layer and the PCB surface, is set according to the process, a distance range is preset so that the probe can move to the position of the conductive layer on the inner wall of the hole to be tested within the distance range, thereby detecting the conductive layer.

[0027] S5: The probe emits laser light into the perimeter of the hole to be tested and collects the reflected laser light. Specifically, the probe is inserted into the hole to be tested, and the probe emits laser light towards the inner wall of the hole and collects the laser light reflected from the inner wall of the hole. After the collection is completed, the probe rotates at a preset angle and continues to emit laser light towards the inner wall of the hole until the probe has completed the collection of the reflected laser light from the entire inner wall of the hole.

[0028] With this setup, the probe can detect the entire conductive layer of the inner wall of the hole at this insertion distance, thus achieving 360° detection of the conductive layer of the inner wall at this insertion distance.

[0029] S6: Obtain the reflected light energy value based on the reflected laser, and obtain the conductive layer thickness value based on the reflected light energy value; Specifically, the steps for "obtaining the reflected light energy value based on the reflected laser" are as follows: the reflected laser is transmitted to the optical power detection unit, the optical power detection unit obtains the reflected light energy value based on the reflected laser, the reflected light energy value includes the reflected light power, and the reflected light energy value and reflection position are recorded at this time.

[0030] In this embodiment, the optical power detection unit includes a signal processor, a photodetector, and an optical power meter. After the reflected laser is collected by the probe, it is transmitted to the optical power detection unit. The reflected laser is converted into a reflected signal by the signal processor and sent to the photodetector. The photodetector receives the reflected signal, integrates the signal, and transmits it to the optical power meter. The optical power meter obtains the reflected light energy value based on the signal. The reflected light energy value includes the reflected light power. By recording the reflected light energy value and the position of the reflected light at this time, the reflected light energy value of the probe at the insertion distance and the orientation position can be determined.

[0031] The specific steps for "obtaining the conductive layer thickness by comparing the reflected light energy value with a preset reflected light energy value" are as follows: Different conductive layer thicknesses are simulated in advance; a reflected laser is incident and the corresponding reflected light energy value is collected and calculated. This ensures that the conductive layer thickness corresponds to a specific reflected light energy value, meaning there is a correlation between the conductive layer thickness and its corresponding reflected light energy value. Based on this correlation, the corresponding conductive layer thickness can be quickly obtained from the reflected light energy value. By pre-simulating different conductive layer thicknesses and laser emission environments, a corresponding reflected light energy value is generated for each conductive layer thickness. During detection, the probe can quickly obtain the corresponding conductive layer thickness value without cumbersome calculations based on the reflected light energy value, thus simplifying the algorithm process, accelerating detection efficiency, and improving detection accuracy.

[0032] S7: Determine whether the thickness of the conductive layer is up to standard; Specifically, after obtaining the thickness of the conductive layer, it is compared with the process requirements or specified range. If the thickness of the conductive layer is within the range, it is determined that the thickness of the conductive layer is qualified; if the thickness of the conductive layer is not within the range, it is determined that the thickness of the conductive layer is unqualified, and a notification is issued.

[0033] S8: The probe continues to extend until the test is complete.

[0034] Specifically, the probe continues to extend, and the extension distance can be a preset distance. Due to deviations or errors in the molding and manufacturing process, the distance between the two conductive layers may shift. Therefore, during the extension process, the probe continuously emits reflected laser light and collects the reflected light energy value. If the reflected light energy value is significantly increased, it can be determined that this is also a conductive layer. The probe stops moving, or the probe continues to move a certain distance so that the detection range completely covers the conductive layer. Then, laser light is emitted around the inner wall of this location and the reflected laser light is collected. Similarly, the thickness of the conductive layer is obtained and judged by rotating at a preset angle until the 360° detection of the inner wall of the ring at this extension distance is completed.

[0035] The detection method described in this application converts laser emission signals into reflected light energy values ​​to acquire and compare the thickness of the conductive layer. This method efficiently and accurately replaces manual measurement and comparison of the conductive layer thickness, thereby significantly improving detection efficiency and accuracy. Furthermore, since the probe of this application extends into the inner hole for detection, it effectively addresses the problem of obstruction caused by steps or protrusions in the inner hole, which can make it difficult to see clearly with the human eye or through equipment. Simultaneously, it eliminates the need to cut open the hole to be tested, thus ensuring the structural integrity of the PCB board and reducing detection costs. In addition, it allows for sequential inspection of the entire PCB board to achieve full inspection, thereby ensuring product inspection speed, quality, and yield.

[0036] Example 2 Reference Figure 2 , Figure 3 as well as Figure 4 On the other hand, this application provides a testing device that uses the multilayer PCB board inner hole thickness testing method described above, including a vertical feeding structure 1 and a testing structure 2. The vertical feeding structure 1 is used to feed the PCB board in an upright state, and the testing structure 2 is used to test the PCB board in the upright state.

[0037] Specifically, the vertical feeding structure 1 includes a conveying guide rail 11 and a vertical clamping assembly 12 slidably connected to the conveying guide rail 11. The conveying guide rail 11 includes an upper guide rail and a lower guide rail parallel to the upper guide rail. The vertical clamping assembly 12 is disposed between the upper guide rail and the lower guide rail and can move back and forth along its length direction, thereby clamping the multilayer PCB board and feeding it in an upright state.

[0038] The detection structure 2 includes a detection base, a backlight assembly 21 disposed on the detection base, a sliding assembly, and a probe assembly 22 disposed on the sliding assembly. The probe assembly 22 can be close to or away from the conveying guide rail 11.

[0039] Specifically, the detection base is positioned on both sides of the conveying guide rail 11, allowing for the detection of one or both sides of the PCB board as needed. The backlight assembly 21 is positioned on the detection base and is movable, providing backlighting for the probe assembly 22. The sliding assembly includes a lifting guide rail positioned on the detection base and a probe support seat positioned on the lifting guide rail. The lifting guide rail is vertically positioned, and the probe support seat is slidably connected to the lifting guide rail, enabling vertical lifting. The probe support seat is equipped with multi-axis guide rails, including an X-axis guide rail, a Y-axis guide rail, and a Z-axis guide rail. The probe assembly 22 is positioned on the multi-axis guide rails to achieve movement in multiple directions.

[0040] Reference Figure 3 as well as Figure 4The probe assembly 22 includes a positioning vision sensor 221, a zero-position sensor 222, and an optical fiber probe 223 rotatably connected to the multi-directional guide rail, all mounted on a multi-directional guide rail. When inspecting the PCB, the positioning vision sensor 221 locates the position of the hole to be tested on the PCB and feeds the position back to the zero-position sensor 222. The zero-position sensor 222 then moves closer to the PCB until it reacts or registers a reading. At this point, the probe head of the zero-position sensor 222 is at the edge of the hole to be tested. The optical fiber probe 223 extends into the hole to perform the inspection, using this edge position as a reference. The optical fiber probe 223 emits a laser beam towards the conductive layer. After the laser beam is reflected, it is transmitted through the optical fiber probe 223 to the optical power detection unit to detect the optical signal and obtain the reflected light energy value. Based on the reflected light energy value, the corresponding conductive layer thickness value is obtained, and the thickness of the conductive layer can be determined and the inspection result output.

[0041] By setting up a vertical feeding structure 1 and a detection structure 2, the vertical feeding structure 1 and the detection structure 2 work together to enable the PCB board to be fed vertically and thus be detected by the detection structure 2. In the vertical state, the detection structure 2 can detect the hole to be tested from multiple angles and through the position of the hole to be tested through the sliding component. Compared with the manual inspection method, it can achieve comprehensive inspection of multiple positions in the hole to be tested more efficiently and accurately, thereby reducing the blind spot and meeting the requirements of higher precision and higher efficiency inspection.

[0042] Exemplary embodiments of this disclosure have been specifically shown and described above. It should be understood that this disclosure is not limited to the detailed structures, arrangements, or implementations described herein; rather, this disclosure is intended to cover various modifications and equivalent arrangements contained within the spirit and scope of the appended claims.

Claims

1. A method for detecting the thickness of inner holes in a multilayer PCB board, characterized in that, Includes the following steps: Feed the PCB board into the preset shape. Find the location of the hole to be tested on the PCB board; Obtain the edge position of the hole to be tested, and use this edge position as a reference point; Using a reference point as a benchmark, insert the probe into the hole to be tested. The distance the probe extends into the hole is a preset distance. The probe emits laser light into the perimeter of the hole to be tested and collects the reflected laser light. The reflected light energy value is obtained based on the reflected laser, and the conductive layer thickness value is obtained based on the reflected light energy value; Determine whether the thickness of the conductive layer is acceptable; The probe continues to extend until the test is complete.

2. The method for detecting the thickness of inner holes in a multilayer PCB board according to claim 1, characterized in that, The specific steps of "obtaining the reflected light energy value based on the reflected laser, and obtaining the conductive layer thickness value based on the reflected light energy value" are as follows: the reflected laser is transmitted to the optical power detection unit, the optical power detection unit obtains the reflected light energy value based on the reflected laser, the reflected light energy value includes the reflected light power, and the reflected light energy value and reflection position are recorded at this time; the conductive layer thickness value is obtained by comparing the reflected light energy value with a preset reflected light energy value.

3. The method for detecting the thickness of inner holes in a multilayer PCB board according to claim 2, characterized in that, The step of "obtaining the conductive layer thickness by comparing the reflected light energy value with the preset reflected light energy value" specifically involves: simulating environments with different conductive layer thicknesses in advance, injecting a reflected laser and collecting and calculating the corresponding reflected light energy value so that the conductive layer thickness corresponds to a corresponding reflected light energy value; and obtaining the corresponding conductive layer thickness based on the reflected light energy value.

4. The method for detecting the thickness of inner holes in a multilayer PCB board according to claim 1, characterized in that, The specific steps of "obtaining the edge position of the hole to be tested and using the edge position as a reference point" are as follows: a zero-position sensor is used to detect the edge part of the hole to be tested, the zero-position sensor is driven to continuously move closer to the edge part, and when the zero-position sensor reacts or reads, the position of the zero-position sensor at this time is recorded as the reference point.

5. The method for detecting the thickness of inner holes in a multilayer PCB board according to claim 1, characterized in that, The specific steps of "the probe emits laser light around the hole to be tested and collects the reflected laser light" are as follows: the probe is inserted into the hole to be tested, the probe emits laser light towards the inner wall of the hole to be tested, and collects the laser light reflected from the inner wall of the hole to be tested; after collection, the probe rotates at a preset angle and continues to emit laser light towards the inner wall of the hole to be tested until the probe has completed the collection of laser light around the entire inner wall of the hole to be tested.

6. The method for detecting the thickness of inner holes in a multilayer PCB board according to claim 1, characterized in that, The specific steps of "probe continuing to extend" are as follows: the probe continues to extend, and during the extension process, the probe continuously emits reflected laser light and collects the reflected light energy value. If the reflected light energy value is collected, the probe stops, emits laser light around the inner wall at that position and collects the reflected laser light, and obtains and judges the thickness value of the conductive layer.

7. The method for detecting the thickness of inner holes in a multilayer PCB board according to claim 1, characterized in that, The specific steps of "obtaining the position of the hole to be tested on the PCB board" are as follows: scan the PCB board using a visual positioning method to obtain the position of the hole to be tested on the PCB board.

8. A testing device, employing the method for detecting the thickness of inner holes in a multilayer PCB board as described in any one of claims 1-7, characterized in that, It includes a vertical feeding structure (1) and a detection structure (2); the vertical feeding structure (1) includes a conveying guide rail (11) and a vertical clamping assembly (12) slidably connected to the conveying guide rail (11); the detection structure (2) includes a detection base, a backlight assembly (21) disposed on the detection base, a sliding assembly and a probe assembly (22) disposed on the sliding assembly, the probe assembly (22) being able to be close to or away from the conveying guide rail (11).

9. The detection device according to claim 8, characterized in that, The sliding assembly includes a lifting guide rail disposed on the detection base and a probe support seat disposed on the lifting guide rail. The probe support seat is provided with multiple guide rails, and the probe assembly (22) is disposed on the multiple guide rails.

10. The detection device according to claim 9, characterized in that, The probe assembly (22) includes a positioning vision sensor (221) mounted on a multi-guide rail, a zero-position sensor (222), and an optical fiber probe (223) rotatably connected to the multi-guide rail.

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