Laser drilling depth monitoring device, method, control terminal and storage medium

Abstract

This invention discloses a laser drilling depth monitoring device, method, control terminal, and storage medium. The device includes a measurement source, a collimator, a galvanometer, and a field lens. The collimator collimates the measurement laser emitted by the measurement source before directing it into the galvanometer. The galvanometer coaxializes the measurement laser and the processing laser before focusing them into the processed sample through the field lens. The measurement source receives reflected laser light from the processed sample to calculate the drilling depth of the processed laser within the sample. This allows measurement to be performed during the drilling process, reducing detection time and increasing detection coverage.

Description

Technical Field

[0001] This invention relates to the field of laser measurement, and more particularly to a laser drilling depth monitoring device, method, control terminal, and storage medium. Background Technology

[0002] PCB laser drilling is a crucial process for both flexible and rigid PCBs, an indispensable part of modern integrated circuits. Currently, quality inspection for this process relies on post-processing checks. After drilling, samples are manually selected and examined under a microscope or camera to assess the quality, roundness, uniformity of the bottom, absence of residue, and whether the next copper layer has been reached. This manual sampling method is inefficient. PCB laser drilling is extremely fast, reaching tens of thousands of holes per minute, while the manual sampling rate is very low, easily leading to defective products flowing into the next process and causing even greater losses. Manual PCB drilling depth measurement requires 3D interferometers, which are currently mainly imported, making them very expensive, costly, and inefficient. Summary of the Invention

[0003] In a first aspect, this application provides a laser drilling depth monitoring device, comprising: a measurement source, a collimator, a galvanometer, and a field lens;

[0004] The collimator is used to collimate the measurement laser emitted by the measurement source and direct it into the galvanometer.

[0005] The galvanometer is used to coaxially process the measuring laser and the processing laser, and then focus them into the processing sample through the field lens;

[0006] The measurement source is used to receive reflected laser light from the processed sample in order to calculate the drilling depth of the processing laser in the processed sample.

[0007] Furthermore, the measurement source includes a first reflecting surface, a second reflecting surface, and a photodetector;

[0008] The transmittance of the first reflective surface is greater than that of the second reflective surface, and the first reflective surface and the second reflective surface constitute a resonant cavity;

[0009] The measuring laser is incident on the processed sample through the first reflecting surface, and the reflected measuring laser is incident on the PD receiver through the second reflecting surface;

[0010] The PD receiver is used to receive the reflected measurement laser and the interference light formed by the measurement laser transmitted through the second reflective surface, in order to calculate the borehole depth.

[0011] Furthermore, an amplifier is provided between the second reflective surface and the PD receiver, the amplifier being used to amplify the interference light.

[0012] Secondly, this application also provides a method for monitoring the depth of laser drilling in PCBs, including:

[0013] After the measuring laser and the processing laser are coaxially processed, they are driven into the surface of the sample being processed;

[0014] Receive the reflected laser light from the surface of the processed sample;

[0015] The drilling depth of the processing laser in the processed sample is calculated based on the reflected laser.

[0016] Furthermore, the step of receiving the reflected laser light from the surface of the processed sample to calculate the drilling depth of the processing laser in the processed sample includes:

[0017] The reflected measurement laser interferes with the measurement laser in the measurement source resonant cavity, generating interference light;

[0018] The interference light is received and filtered. The extreme points of the filtered light signal are found. The drilling depth is calculated based on the number of extreme points.

[0019] Furthermore, finding the extreme points of the filtered optical signal includes:

[0020] Identify and remove false extreme points from the extreme points, retain the remaining true extreme points, and use the number of true extreme points as the number of extreme points.

[0021] Furthermore, the expression for calculating the borehole depth based on the number of extreme points is as follows:

[0022] N*λ / 2=h

[0023] In the formula, N is the number of extreme points, λ is the wavelength, and h is the borehole depth.

[0024] Furthermore, the interference light is amplified before being received.

[0025] Thirdly, this application also provides a control terminal, including a processor and a memory, wherein the memory stores a computer program, and the computer program executes the PCB laser drilling depth monitoring method when it is run on the processor.

[0026] Fourthly, this application also provides a readable storage medium storing a computer program that executes the PCB laser drilling depth monitoring method when run on a processor.

[0027] This invention discloses a laser drilling depth monitoring device, method, control terminal, and storage medium. The device includes a measurement source, a collimator, a galvanometer, and a field lens. The collimator collimates the measurement laser emitted by the measurement source before directing it into the galvanometer. The galvanometer coaxializes the measurement laser and the processing laser before focusing them into the processed sample through the field lens. The measurement source receives reflected laser light from the processed sample to calculate the drilling depth of the processed laser within the sample. This allows measurement to be performed during the drilling process, reducing detection time and increasing detection coverage. Attached Figure Description

[0028] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope of protection of the present invention. In the various drawings, similar components are numbered similarly.

[0029] Figure 1 A schematic diagram of a laser drilling depth monitoring device according to an embodiment of this application is shown;

[0030] Figure 2 This paper illustrates a flowchart of a PCB laser drilling depth monitoring method according to an embodiment of the present application.

[0031] Figure 3 A schematic diagram of the internal structure of the measurement source according to an embodiment of this application is shown;

[0032] Figure 4 An interference light waveform diagram of an embodiment of this application is shown. Detailed Implementation

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0034] The components of the embodiments of the invention described and illustrated herein can typically be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0035] In the following, the terms “comprising,” “having,” and their cognates, which may be used in various embodiments of the invention, are intended only to indicate a particular feature, number, step, operation, element, component, or combination thereof, and should not be construed as excluding, firstly, the presence of one or more other features, numbers, steps, operations, elements, components, or combinations thereof, or adding the possibility of one or more features, numbers, steps, operations, elements, components, or combinations thereof.

[0036] Furthermore, the terms "first," "second," and "third" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0037] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which the various embodiments of the invention pertain. Terms (such as those defined in commonly used dictionaries) shall be interpreted as having the same meaning as in their contextual meaning in the relevant technical field and shall not be interpreted as having an idealized or overly formal meaning, unless clearly defined in the various embodiments of the invention.

[0038] like Figure 1 The image shows the structure of a laser drilling depth monitoring device provided in this application. The device includes: a measurement source 10, a collimator 20, a galvanometer 30, and a field lens 40.

[0039] The collimator 20 collimates the measurement laser emitted by the measurement source 10 and directs it into the galvanometer 30. This measurement laser does not need to participate in the drilling of the processed sample 50 and needs to be coaxially transmitted with the processing laser emitted by the laser 60. Therefore, a measurement source wavelength with high transmittance and convenient confocal adjustment can be selected.

[0040] Galvanometer 30 is used to synthesize the laser beam. After the measuring laser and the processing laser emitted by laser 60 are coaxially processed by galvanometer 30, the measuring laser and the processing laser are combined into a single beam, which is then focused by field mirror 40 and directed into the processed sample 50. At this time, the processing laser continues drilling, while the measuring laser illuminates the hole drilled by the processing laser and is reflected back along the same path. The reflected light passes through field mirror 40 and galvanometer 30 again, returning to collimator 20 and then into measurement source 10. Measurement source 10 receives the reflected laser light from the processed sample 50 to calculate the drilling depth of the processing laser in the processed sample 50.

[0041] Understandably, the aforementioned laser drilling depth monitoring device can measure the drilling depth while drilling is in progress. Therefore, during drilling, the depth feedback from the monitoring device can be used to control whether the drilling is complete.

[0042] Specifically, this application also provides a method for monitoring the depth of laser drilling in PCBs, such as... Figure 2 As shown, it includes the following steps:

[0043] Step S100: After the measuring laser and the processing laser are coaxially processed, they are injected into the surface of the processing sample.

[0044] The processing laser is emitted from laser 60 and shines on the sample to make holes. The sample can be a board such as a PCB board.

[0045] The measuring laser is emitted from the measuring source 10 and is specifically used to measure the drilling depth. The measuring laser does not participate in the drilling process, but in order to accurately measure the drilling depth of the processing laser, it needs to be coaxial with the processing laser to become a single beam, illuminating the drilling position of the processing laser. Generally, the measuring laser wavelength is selected based on the laser wavelength of the laser processing laser, choosing a measuring source wavelength with high transmittance and easy confocal adjustment.

[0046] Step S200: Receive the reflected laser light reflected back from the surface of the processed sample.

[0047] When a laser beam strikes a sample, it is reflected, such as... Figure 1 As shown, the measuring laser is incident vertically, so it is also reflected vertically. After passing through the field lens 40, galvanometer 30 and collimator 20, it returns to the measurement source 10. The measurement source detects the reflected light to determine the drilling depth.

[0048] Specifically, such as Figure 3 The diagram shows the internal structure of the measurement source 10, which includes a first reflective surface 11, a second reflective surface 12, and a PD (Photodiode) receiver 13. The first reflective surface 11 has a higher transmittance than the second reflective surface 12, and the first and second reflective surfaces 11 and 12 form a resonant cavity.

[0049] The measuring laser is incident on the processed sample through the first reflecting surface 11, and the reflected laser is incident on the PD receiver 13 through the second reflecting surface 12.

[0050] The measurement laser is emitted from this resonant cavity. When the reflected measurement laser returns, the reflected light interferes with the laser that originally resonated in the resonant cavity. It can be seen that after the test laser enters the drill hole and is reflected back, it does not change its wavelength and frequency. However, because the drill hole becomes deeper, it will produce a phase difference with the laser in the resonant cavity, thus causing interference. The PD receiver 13 is used to receive the optical signal of this interference light.

[0051] When receiving the optical signal, the interference light is amplified once. In other words, an amplifier can be set up to make the received signal large enough to ensure the reliability of the signal data.

[0052] After obtaining the optical signal of the interfering light, filtering can be used to eliminate interference data in the spectrum, thereby ensuring the accuracy and reliability of the data.

[0053] Step S300: Calculate the drilling depth of the processing laser in the processed sample based on the reflected laser.

[0054] The PD receiver 13 receives the interference light formed by the reflected laser and the measuring laser transmitted through the second reflective surface 12 to calculate the borehole depth.

[0055] It is understandable that as the borehole goes deeper, the amplitude of the interference wave will change periodically. When the phase difference is an integer multiple of the wavelength, it is constructive interference. If the phase difference is half a wavelength, it is destructive interference, producing the minimum amplitude. In other words, the borehole depth will repeat a periodic change every half wavelength, producing a maximum and a minimum value. The distance between two maximum or minimum values ​​is half a wavelength. Therefore, the depth of the borehole can be calculated by counting the number of extreme points.

[0056] like Figure 4 The image shows the actual measured interference light spectrum. Each peak represents half the wavelength of the measured laser. In other words, with each periodic change, the drilling depth increases by half a wavelength. The drilling depth can be calculated based on the number of peaks.

[0057] That is, there exists an expression for calculating the borehole depth:

[0058] N*λ / 2=h

[0059] In the formula, N is the number of extreme points, λ is the wavelength, and h is the borehole depth.

[0060] In other words, the measurement accuracy of this application is within half the wavelength of the laser being measured, for example... Figure 4 The laser used in this process has a wavelength of 632nm, which can achieve a measurement accuracy of 316 and a large measurement range. Because the measuring laser and the processing laser are coaxially inserted into the borehole, the processing can be carried out simultaneously and the drilling depth can be monitored in real time. This increases the accuracy of the processing and reduces the time for testing and inspecting the finished product.

[0061] When calculating the above extreme points, it is also necessary to identify and remove pseudo-extreme points. Specifically, this can be done by taking the known amplitude of the measured laser and determining the theoretical extreme point sizes of the two extreme points during constructive and destructive interference. Then, the actual data obtained can be used to determine whether the size of these extreme points exceeds the calculated theoretical extreme point size. If it does, it is considered a pseudo-extreme point and needs to be removed from the count; otherwise, it is considered a true extreme point and is counted.

[0062] Understandably, the PCB laser drilling monitoring method of this application calculates the depth of the laser drilling in real time at the start of drilling, rather than calculating the absolute depth of a hole. Typically, during drilling, an instruction is given to determine the required drilling depth, and the program calculates the drilling time based on the laser power and the PCB material. The technical solution of this application allows for more precise control of the laser's drilling depth. Furthermore, because the drilling action is rapid and continuous, the hole depth can also be obtained from the drilling depth. And since laser measurement is also used, the depth of multiple holes can be acquired simultaneously, just like the drilling speed, enabling monitoring of multiple hole positions at the same time.

[0063] The laser drilling depth monitoring device of this application has a simple structure. It only requires adding a measurement source, collimating lens and galvanometer to the original laser processing optical path to achieve real-time measurement operation. These modules are readily available and easy to assemble, and will not affect the original process or production efficiency. At the same time, it also has the effect of real-time correction, which improves the yield rate and reduces the defect rate of the product. It also reduces the burden on the staff, eliminating the need for staff to manually inspect the drill holes on the PCB board using expensive 3D interferometers.

[0064] This application also provides a control terminal, including a processor and a memory, wherein the memory stores a computer program, and the computer program executes the PCB laser drilling depth monitoring method when it is run on the processor.

[0065] This application also provides a readable storage medium storing a computer program that, when run on a processor, executes the PCB laser drilling depth monitoring method.

[0066] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can also be implemented in other ways. The apparatus embodiments described above are merely illustrative; for example, the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that, as an alternative implementation, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagram and / or flowchart, and combinations of blocks in the block diagram and / or flowchart, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0067] In addition, the functional modules or units in the various embodiments of the present invention can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0068] If the aforementioned functions are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a smartphone, personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0069] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A laser drilling depth monitoring device, characterized in that, include: Measurement source, collimator, galvanometer, and field mirror; The collimator is used to collimate the measurement laser emitted by the measurement source and direct it into the galvanometer. The galvanometer is used to coaxially process the measuring laser and the processing laser, and then focus them into the processing sample through the field lens; The measurement source is used to receive the reflected laser light from the processed sample in order to calculate the drilling depth of the processing laser in the processed sample. The measurement source includes a first reflecting surface, a second reflecting surface, and a photodetector; The transmittance of the first reflective surface is greater than that of the second reflective surface, and the first reflective surface and the second reflective surface constitute a resonant cavity; The measuring laser is incident on the processed sample through the first reflecting surface, and the measuring laser is incident on the PD receiver through the second reflecting surface; The PD receiver is used to receive the measuring laser transmitted through the second reflective surface and the interference light formed by the measuring laser, in order to calculate the borehole depth.

2. The laser drilling depth monitoring device according to claim 1, characterized in that, An amplifier is also provided between the second reflective surface and the PD receiver, the amplifier being used to amplify the interference light.

3. A method for monitoring the depth of laser drilling in PCBs, characterized in that, The laser drilling depth monitoring device as described in any one of claims 1 to 2, wherein the monitoring method comprises: The laser drilling depth monitoring device is used to coaxially process the measuring laser and the processing laser before drilling them into the surface of the sample being processed. Receive the reflected laser light from the surface of the processed sample; The laser drilling depth monitoring device calculates the drilling depth of the processing laser in the processed sample based on the reflected laser.

4. The PCB laser drilling depth monitoring method according to claim 3, characterized in that, The step of receiving the reflected laser light from the surface of the processed sample to calculate the drilling depth of the processed laser in the processed sample includes: The reflected measurement laser interferes with the measurement laser in the measurement source resonant cavity, generating interference light; The interference light is received and filtered. The extreme points of the filtered light signal are found. The drilling depth is calculated based on the number of extreme points.

5. The PCB laser drilling depth monitoring method according to claim 4, characterized in that, The process of finding the extreme points of the filtered optical signal includes: Identify and remove false extreme points from the extreme points, retain the remaining true extreme points, and use the number of true extreme points as the number of extreme points.

6. The PCB laser drilling depth monitoring method according to claim 4, characterized in that, The expression for calculating the borehole depth based on the number of extreme points is as follows: N*λ / 2=h In the formula, N is the number of extreme points, λ is the wavelength, and h is the borehole depth.

7. The PCB laser drilling depth monitoring method according to claim 4, characterized in that, The interference light was amplified before being received.

8. A control terminal, characterized in that, It includes a processor and a memory, the memory storing a computer program that, when run on the processor, executes the PCB laser drilling depth monitoring method according to any one of claims 3 to 7.

9. A readable storage medium, characterized in that, It stores a computer program that, when run on a processor, executes the PCB laser drilling depth monitoring method according to any one of claims 3 to 7.

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