Back drill depth detection method, signal processing assembly, system and program product

Abstract

The application is suitable for the field of optical measurement technology, and provides a back drilling depth detection method, a signal processing assembly, a system and a program product. The back drilling depth detection method comprises the following steps: obtaining a first interference signal between a first reflected light and a reference light beam, the first reflected light being reflected light of an incident light beam of a back drilling stop layer of a circuit board on the back drilling stop layer; the incident light beam of the back drilling stop layer enters a medium layer from a through hole side wall of the circuit board, and reaches the back drilling stop layer through the medium layer; the reference light beam and the incident light beam of the back drilling stop layer are obtained by splitting an outgoing light beam of a light source; determining a depth difference between the back drilling stop layer and a circuit board surface of the circuit board based on the first interference signal, and determining a back drilling depth based on the depth difference. The embodiment of the application can improve the universality of back drilling control.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of optical measurement, and particularly relates to a back drilling depth detection method, a signal processing assembly, a system and a program product. BACKGROUND

[0002] Back drilling is a key process technology in printed circuit board (PCB) design, and is widely used in the Electronic Design Automation (EDA) industry, mainly for removing the useless part of the through hole of the circuit board to improve the quality of high-speed signal transmission. The back drilling depth refers to the depth of removing the through hole material in the back drilling process.

[0003] In related technologies, the back drilling depth is usually judged by means of circuit on-off, physical marker contact feedback, etc. However, these methods usually have limitations on the structure of the circuit board, such as the need to reserve test structures (such as test holes and lines) on the board edge or to embed physical markers inside the circuit board, which is not convenient to apply in different scenarios. SUMMARY

[0004] The embodiments of the present application provide a back drilling depth detection method, a signal processing assembly, a system and a computer program product, which can improve the universality of back drilling depth control.

[0005] The first aspect of the embodiments of the present application provides a back drilling depth detection method, comprising: obtaining a first interference signal between a first reflected light and a reference light beam, the first reflected light being reflected light of an incident light beam of a back drilling stop layer of a circuit board reflected by the back drilling stop layer; the incident light beam of the back drilling stop layer enters a dielectric layer from a through hole side wall of the circuit board, and reaches the back drilling stop layer through the dielectric layer; the reference light beam and the incident light beam of the back drilling stop layer are obtained by splitting the outgoing light beam of a light source; determining a depth difference between the back drilling stop layer and a circuit board surface of the circuit board based on the first interference signal, and determining the back drilling depth based on the depth difference.

[0006] In some embodiments of the first aspect, the outgoing light beam of the light source is split into the reference light beam and the incident light beam of the back drilling stop layer by a beam splitter; and the determination of the depth difference between the back drilling stop layer and the circuit board surface of the circuit board based on the first interference signal comprises: determining a first distance between the back drilling stop layer and the beam splitter based on the first interference signal; obtaining a second distance between the circuit board surface and the beam splitter; and determining the depth difference according to the first distance and the second distance.

[0007] In some embodiments of the first aspect, before the first interference signal between the first reflected light and the reference light beam is acquired, the method for detecting the back drilling depth further comprises: controlling the incident light beam of the back drilling stop layer to enter the sidewall of the through hole along a preset direction, an included angle between the preset direction and the vertical direction of the circuit board being a target angle; and the determining, based on the first interference signal, of the first distance between the back drilling stop layer and the beamsplitter comprises: determining, based on the first interference signal, a wave path length of the incident light beam of the back drilling stop layer from the beamsplitter to the back drilling stop layer; and determining the first distance based on the target angle and the wave path length.

[0008] In some embodiments of the first aspect, the determining, based on the first interference signal, of the wave path length of the incident light beam of the back drilling stop layer from the beamsplitter to the back drilling stop layer comprises: determining, based on the first interference signal, a position at which an interference intensity of the first reflected light and the reference light beam is greater than an intensity threshold; and determining the wave path length based on the position at which the interference intensity is greater than the intensity threshold.

[0009] In some embodiments of the first aspect, the determining, based on the target angle and the wave path length, of the first distance comprises: determining the first distance based on a trigonometric function relationship between the target angle and the wave path length.

[0010] In some embodiments of the first aspect, the acquiring the second distance between the surface of the circuit board and the beamsplitter comprises: acquiring a second interference signal between second reflected light and a reference light beam, the second reflected light being reflected light of the incident light beam of the surface of the circuit board on the surface of the circuit board; and determining, based on the second interference signal, the second distance.

[0011] In some embodiments of the first aspect, the acquiring the second interference signal between the second reflected light and the reference light beam comprises: acquiring a second interference signal between multiple beams of second reflected light and a reference light beam, wherein different beams of second reflected light are reflected at different surface positions on the surface of the circuit board; and the determining, based on the second interference signal, of the second distance comprises: determining, based on the second interference signal between multiple beams of second reflected light and a reference light beam, a distance between each surface position corresponding to each beam of second reflected light and the beamsplitter; and calculating a mean value of the distances between the surface positions corresponding to each beam of second reflected light and the beamsplitter to obtain the second distance.

[0012] In some embodiments of the first aspect, after the back drilling depth is determined based on the depth difference, the method for detecting the back drilling depth further comprises: controlling, based on the back drilling depth, a drill bit to back drill the circuit board.

[0013] The second aspect of the embodiment of the present application provides a back drilling depth detection device, comprising: a signal acquisition unit configured to acquire a first interference signal between a first reflected light and a reference light beam, wherein the first reflected light is reflected light of an incident light beam of a back drilling stop layer of a circuit board, the incident light beam of the back drilling stop layer enters a medium layer from a via sidewall of the circuit board, and reaches the back drilling stop layer through the medium layer; the reference light beam and the incident light beam of the back drilling stop layer are obtained by splitting an outgoing light beam of a light source; a back drilling depth detection unit configured to determine a depth difference between the back drilling stop layer and a circuit board surface of the circuit board based on the first interference signal, and determine a back drilling depth based on the depth difference.

[0014] The third aspect of the embodiment of the present application provides a signal processing assembly, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the back drilling depth detection method when executing the computer program.

[0015] The fourth aspect of the embodiment of the present application provides a back drilling depth detection system, comprising: a light source; an optical device group comprising a beam splitter and a reference mirror; the beam splitter is configured to split an outgoing light beam of the light source into a reference light beam and an incident light beam of a back drilling stop layer; the reference mirror is configured to reflect the reference light beam to the beam splitter; the incident light beam of the back drilling stop layer enters from a via sidewall of the circuit board, reaches the back drilling stop layer through a medium layer, and is reflected by the back drilling stop layer to form a first reflected light; a photosensitive assembly configured to acquire a first interference signal formed by interference between the first reflected light and the reference light beam through the beam splitter; and a signal processing assembly configured to execute the steps of the back drilling depth detection method according to any one of the first aspect.

[0016] The fifth aspect of the embodiment of the present application provides a computer readable storage medium, wherein the computer readable storage medium stores a computer program, and the computer program is executed by a processor to implement the steps of the back drilling depth detection method.

[0017] The sixth aspect of the embodiment of the present application provides a computer program product, when the computer program is executed, the back drilling depth detection method is executed.

[0018] In the embodiment of the present application, the light beam of the light source is split into a reference light beam and an incident light beam of the back drilling stop layer, the incident light beam of the back drilling stop layer enters the medium layer from the through-hole side wall of the circuit board, reaches the back drilling stop layer through the medium layer, is reflected by the back drilling stop layer to form a first reflected light; by acquiring a first interference signal between the first reflected light and the reference light beam, and determining the depth difference between the back drilling stop layer and the circuit board surface of the circuit board based on the first interference signal, the back drilling depth is determined based on the depth difference, without the need of reserving a test structure at the edge of the circuit board or pre-burying a physical mark in the circuit board, the back drilling depth of the circuit board of various structures can be determined in a non-contact manner, which helps to improve the universality of back drilling depth control. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0020] Figure 1 is a structural schematic diagram of a back drilling depth detection system provided by an embodiment of the present application;

[0021] Figure 2 is a schematic diagram of a circuit board provided by an embodiment of the present application;

[0022] Figure 3 is a specific structural schematic diagram of a back drilling depth detection system provided by an embodiment of the present application;

[0023] Figure 4 is an implementation flow schematic diagram of a back drilling depth detection method provided by an embodiment of the present application;

[0024] Figure 5 is a specific implementation flow schematic diagram of determining a depth difference provided by an embodiment of the present application;

[0025] Figure 6 is a schematic diagram of a plurality of second reflected lights provided by an embodiment of the present application;

[0026] Figure 7 is a structural schematic diagram of a back drilling depth detection device provided by an embodiment of the present application;

[0027] Figure 8 is a structural schematic diagram of a signal processing component provided by an embodiment of the present application. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work belong to the protection scope of the present application.

[0029] Back drilling is a key process technology in circuit board design, which is widely used in the electronic design automation industry, mainly for removing the useless part of the through hole of the circuit board to improve the quality of high-speed signal transmission. The back drilling depth refers to the depth of removing the through hole material in the back drilling process. In the related art, the back drilling depth is usually judged by means of circuit on-off, physical marker contact feedback and the like. However, these means are usually limited to the structure of the circuit board, for example, a test structure needs to be reserved at the edge of the board or a physical marker needs to be embedded in the circuit board, which is not convenient to apply in different scenarios.

[0030] Based on this, the present application provides a back drilling depth detection method, which neither needs to reserve a test structure at the edge of the circuit board nor needs to embed a physical marker in the circuit board, and can non-contact determine the back drilling depth of circuit boards of various structures, which helps to improve the universality of back drilling depth control.

[0031] In order to illustrate the technical scheme of the present application, the following will be described by specific embodiments.

[0032] Reference is made to Figure 1 , Figure 1 A back drilling depth detection system provided by the present application is shown. The back drilling depth detection system 1 can include:

[0033] a light source 10;

[0034] an optical device group 20 including a beam splitter 201 and a reference mirror 202; wherein the beam splitter 201 is used to divide the outgoing light beam of the light source 10 into a reference light beam and an incident light beam of a back drilling stop layer; the reference mirror 202 is used to reflect the reference light beam to the beam splitter 201; the incident light beam of the back drilling stop layer enters from the through hole side wall of the circuit board, reaches the back drilling stop layer through the medium layer, and is reflected by the back drilling stop layer to form a first reflected light;

[0035] a photosensitive component 30 for collecting a first interference signal formed by the first reflected light and the reference light beam interfering with each other through the beam splitter 201;

[0036] a signal processing component 40 for processing the signal output by the photosensitive component 30, for example, performing the steps of the back drilling depth detection method provided by the present application.

[0037] Figure 2A schematic diagram of a circuit board is shown. The circuit board can include signal layers and dielectric layers. The signal layers are where the copper wires that transmit signals are located. The dielectric layers, also known as insulating layers, are layers of insulating material that separate and support the copper wires of the signal layers. The signal layers and dielectric layers can be arranged in sequence along the depth direction of the circuit board, which can refer to the vertical direction of the circuit board. The back drill stop layer is a target signal layer that reflects the incident light beam, and its surface is the surface on which the drill bit needs to stop processing in the back drilling process.

[0038] One or more vias are provided on the circuit board, and each via penetrates the signal layers and the dielectric layers. The surface of the via in contact with the signal layers / dielectric layers is referred to as the via sidewall. In the back drilling process, the drill bit usually needs to back drill directly opposite the via.

[0039] To implement the detection method of the present application, the light beam emitted by the light source 10 is light that can be absorbed by the insulating material of the dielectric layer and reflected by the material of the signal layer (usually copper). The specific wavelength can be determined according to the materials of the dielectric layer and the signal layer. In this way, when the incident light beam of the back drill stop layer enters the via sidewall, the incident light beam can enter the dielectric layer from the via sidewall and pass through the dielectric layer to reach the back drill stop layer, and then be reflected by the back drill stop layer to form the first reflected light.

[0040] In some embodiments of the present application, referring to Figure 3 The optical device set 20 can include a beam splitter 201, a reference mirror 202, and an object lens 203. The object lens 203 can be used to shape the light beam emitted by the beam splitter 201 towards the circuit board, so that the incident light beam of the circuit board is collimated light.

[0041] In some embodiments of the present application, the optical device set 20 described above can further include one or more mirrors for changing the optical path.

[0042] In some embodiments of the present application, the optical device set 20 described above can further include one or more lenses for collimating the light beam.

[0043] In some embodiments of the present application, the photosensitive assembly 30 can include a pixel array and an integrated readout circuit. The reference light beam is reflected back to the beam splitter 201 by the reference mirror 202, and interferes with the first reflected light. The pixel array can be used to receive the interference signal and perform photoelectric conversion. The integrated readout circuit can be used to process and transmit the converted electrical signal for signal processing by the signal processing assembly 40.

[0044] In some embodiments of the present application, the light sensing component 30 and the signal processing component 40 can be in an integrated design, for example, integrated on the same circuit board. In some embodiments of the present application, the light sensing component 30 and the signal processing component 40 can be in a non-integrated design, for example, the signal processing component 40 can be a processor on a smart electronic device (such as a computer, a smart phone), and the light sensing component 30 can be a peripheral device of the smart electronic device.

[0045] In some embodiments of the present application, the back drill depth detection system 1 described above can further include a driving component for driving the movement of the beam splitter 201 in the optical component group 20. The collection lens 203 can move synchronously with the beam splitter 201.

[0046] The following will be described in conjunction with Figure 4 A back drill depth detection method provided by the present application will be described. The back drill depth detection method can be applied to the back drill depth detection system 1 and can be executed by the signal processing component 40. Specifically, the back drill depth detection method described above can include the following steps S401 to S402.

[0047] Step S401: Obtain a first interference signal between the first reflected light and the reference light beam.

[0048] As described above, the light beam emitted by the light source 10 is split into a reference light beam and an incident light beam of the back drill stop layer by the beam splitter 201. After the incident light beam of the back drill stop layer is reflected by the back drill stop layer, the first reflected light returns to the optical component group 20 through the dielectric layer and the sidewall of the via, and interferes with the reference light beam obtained by splitting. The light sensing component 30 collects the interference light formed by interference, and can obtain the first interference signal between the first reflected light and the reference light beam. The first interference signal can refer to the signal provided by the light sensing component 30 to the signal processing component 40, which can be used to determine the depth of the back drill stop layer.

[0049] Step S402: Based on the first interference signal, determine the depth difference between the back drill stop layer and the circuit board surface of the circuit board, and determine the back drill depth based on the depth difference.

[0050] In embodiments of the present application, based on the first interference signal, the depth information of the back drill stop layer can be determined, and thus the depth difference between the back drill stop layer and the circuit board surface of the circuit board can be determined. It can be understood that the back drill process is a process of cutting off the redundant copper pillars outside the signal transmission path from the circuit board surface, with the back drill stop layer as the depth reference surface. Therefore, the depth difference between the back drill stop layer and the circuit board surface can be regarded as the back drill depth.

[0051] In the embodiments of the present application, the light beam of the light source is split into the reference light beam and the incident light beam of the back drilling stop layer. The incident light beam of the back drilling stop layer enters the medium layer from the through-hole sidewall of the circuit board, reaches the back drilling stop layer through the medium layer, is reflected by the back drilling stop layer to form the first reflected light. By obtaining the first interference signal between the first reflected light and the reference light beam, and determining the depth difference between the back drilling stop layer and the circuit board surface of the circuit board based on the first interference signal, the back drilling depth is determined based on the depth difference. Neither test structure needs to be reserved on the edge of the circuit board, nor physical marker needs to be embedded in the circuit board. The back drilling depth of various structures of the circuit board can be determined in a non-contact manner, which helps to improve the universality of back drilling depth control.

[0052] In some embodiments of the present application, the light beam of the light source 10 is split into the reference light beam and the incident light beam of the back drilling stop layer by the beam splitter 201. As shown in FIG. 2, the above determining the depth difference between the back drilling stop layer and the circuit board surface of the circuit board based on the first interference signal can include steps S501-S502. Figure 5

[0053] Step S501, determining the first distance between the back drilling stop layer and the beam splitter based on the first interference signal.

[0054] In some embodiments of the present application, before obtaining the first interference signal between the first reflected light and the reference light beam, the above detection method can further include: controlling the incident light beam to enter the through-hole sidewall along a preset direction, and the included angle between the preset direction and the vertical direction of the circuit board is a target angle.

[0055] Specifically, by rotating the entire back drilling depth detection system 1, the angle of the light beam emitted from the object lens 203 can be adjusted, so that the incident light beam of the back drilling stop layer enters the through-hole sidewall along a preset direction, and the included angle between the preset direction and the vertical direction of the circuit board (i.e. the depth direction) is a target angle.

[0056] At this time, determining the first distance between the back drilling stop layer and the beam splitter 201 based on the first interference signal can include: determining the wave path length of the incident light beam of the back drilling stop layer from the beam splitter 201 to the back drilling stop layer based on the first interference signal; and determining the first distance based on the target angle and the wave path length.

[0057] Specifically, since the first interference signal carries the optical path information of the incident light beam reaching the back drilling stop layer along the preset direction and reflecting back to the beam splitter 201, the wave path length of the incident light beam from the beam splitter 201 to the back drilling stop layer can be determined based on the first interference signal. The wave path length is the geometric path length of the incident light beam from the beam splitter 201 to the back drilling stop layer, and is also the geometric path length of the incident light beam from the back drilling stop layer to the beam splitter 201.

[0058] ​The determining, based on the first interference signal, of the wave path length of the incident light beam of the back drill stop layer from the beam splitter 201 to the back drill stop layer can include: determining, based on the first interference signal, a position at which the interference intensity of the first reflected light and the reference light beam is greater than an intensity threshold, and determining the wave path length based on the position at which the interference intensity is greater than the intensity threshold.

[0059] Specifically, the driving assembly can drive the beam splitter 201 to move toward the circuit board along a preset direction. In the process of the movement of the beam splitter 201 toward the circuit board, the first reflected light reflected by the back drill stop layer reaches the beam splitter 201, interferes with the reference light beam, and forms interference light with annular interference fringes. The photosensitive element receives the interference light and performs photoelectric conversion, and outputs the first interference signal to the signal processing assembly 40. Based on the first interference signal, the intensity variation sequence of the interference fringes between the first reflected light and the reference light beam can be determined, the intensity variation sequence is converted into a frequency domain signal by using Fourier transform, the phase difference between the first reflected light and the reference light beam is extracted from the frequency domain signal, and the optical path difference between the first reflected light and the reference light beam is calculated based on the phase difference. The position at which the optical path difference between the second reflected light and the reference light beam is 0 is taken as the position at which the interference intensity is greater than the intensity threshold. At this position, the intensity of the interference fringes is the strongest, and the optical path of the reference light beam is equivalent to the optical path of the first reflected light. Therefore, based on the position at which the interference intensity is greater than the intensity threshold, the optical path L1 of the first reflected light can be obtained, and in combination with the refractive index n1, the wave path length L1 / n1 can be obtained.

[0060] Correspondingly, the determining, based on the target angle and the wave path length, of the first distance can include: determining the first distance based on a trigonometric function relationship between the target angle and the wave path length. The first distance can specifically refer to the distance between the plane in which the back drill stop layer is located and the beam splitter 201.

[0061] Since the included angle between the preset direction and the vertical direction of the circuit board is the target angle, the wave path length can be converted into the first distance between the signal stop layer and the beam splitter 201 by trigonometric transformation. Specifically, please refer to Figure 2 When the included angle between the preset direction and the vertical direction of the circuit board is the target angle θ, the first distance d can be expressed as d=w×cosθ, and w represents the wave path length.

[0062] In step S502, the second distance between the surface of the circuit board and the beam splitter is obtained.

[0063] The second distance can be manually measured and input to the signal transmission assembly by the user, or can be collected by the aforementioned back drill depth detection system 1, and the present application does not limit this. The second distance can specifically refer to the distance between the plane in which the circuit board surface is located and the beam splitter 201.

[0064] In some embodiments of the present application, the acquiring the second distance between the circuit board surface and the beamsplitter 201 can include: acquiring a second interference signal between the second reflected light and the reference light beam, and determining the second distance based on the second interference signal. The second reflected light is the reflected light of the incident light beam on the circuit board surface.

[0065] Similarly, the reference light beam and the incident light beam on the circuit board surface are obtained by splitting the light beam emitted by the light source. The main difference between the second reflected light beam and the first reflected light beam is the reflection position. When collecting the second interference signal, the incident light beam on the circuit board surface can be directly incident on the circuit board surface, and the incident light beam on the circuit board surface is reflected by the circuit board surface to form the second reflected light beam.

[0066] In order to accurately calculate the depth difference, the height of the beamsplitter 201 relative to the circuit board when collecting the second interference signal is usually required to be consistent with the height when collecting the first interference signal. Therefore, the second optical path L2 of the second reflected light can be determined by driving the reference mirror 202 to move or by controlling the light source to emit light beams of different wavelengths, and then the second distance = L2 / n2 can be obtained in combination with the refractive index n2.

[0067] Due to factors such as material properties, manufacturing processes, and application environments, the circuit board surface is prone to be uneven. In order to obtain a more reliable back drilling depth, in some embodiments of the present application, acquiring the second interference signal between the second reflected light and the reference light beam can include: acquiring a second interference signal between a plurality of second reflected light beams and the reference light beam, wherein different second reflected light beams are reflected at different surface positions on the circuit board surface.

[0068] Correspondingly, determining the second distance based on the second interference signal can include: determining the distance between each second reflected light and the beamsplitter 201 based on the second interference signal between the plurality of second reflected light beams and the reference light beam; and calculating the average of the distances between the surface positions corresponding to each second reflected light and the beamsplitter 201 to obtain the second distance.

[0069] Specifically, the incident light beam can be incident on different surface positions on the circuit board surface by horizontally translating the beamsplitter 201 at the same height. For example Figure 6L1 and L2 shown are two incident light beams incident to different surface positions on the surface of the circuit board. At this time, the second interference signals between the second reflected light reflected by different surface positions on the surface of the circuit board and the reference light beam can be collected, and then the distance between the surface position corresponding to each second reflected light and the beam splitter 201 when the second reflected light is collected is calculated. By calculating the average of the distances between the surface positions corresponding to each second reflected light and the beam splitter 201, and taking the average as the second distance, the influence of the unevenness of the surface of the circuit board on the accuracy of the back drilling depth can be reduced.

[0070] It should be noted that in the embodiments of the present application, the second distance between the surface of the circuit board and the beam splitter 201 can be obtained first, and then the first distance between the back drilling stop layer and the beam splitter 201 can be obtained, or the first distance between the back drilling stop layer and the beam splitter 201 can be obtained first, and then the second distance between the surface of the circuit board and the beam splitter 201 can be obtained, which is not limited by the present application.

[0071] Step S503, determining the depth difference according to the first distance and the second distance.

[0072] In some embodiments of the present application, the difference between the first distance and the second distance can be obtained, and the depth difference between the back drilling stop layer and the surface of the circuit board can be obtained, which can be used as the back drilling depth.

[0073] In addition, after determining the back drilling depth based on the depth difference, the back drilling depth detection method can further include: controlling the drill bit to back drill the circuit board based on the back drilling depth, thereby realizing an automatic back drilling process.

[0074] It should be noted that for the above-mentioned method embodiments, in order to simply describe, they are all expressed as a series of action combinations, but those skilled in the art should know that the present application is not limited by the order of the described actions, because according to the present application, certain steps can be performed in other order.

[0075] As shown in Figure 7 The back drilling depth detection device 700 provided by the embodiments of the present application is configured on the signal processing assembly 40.

[0076] Specifically, the back drilling depth detection device 700 can include:

[0077] The signal acquisition unit 701 is configured to acquire a first interference signal between first reflected light and a reference light beam, the first reflected light being reflected light of an incident light beam of a back drill stop layer of a circuit board, the incident light beam of the back drill stop layer entering a medium layer from a via sidewall of the circuit board, and reaching the back drill stop layer through the medium layer, the reference light beam and the incident light beam of the back drill stop layer being obtained by splitting an outgoing light beam of a light source 10.

[0078] The back drill depth detection unit 702 is configured to determine a depth difference between the back drill stop layer and a circuit board surface of the circuit board based on the first interference signal, and determine a back drill depth based on the depth difference.

[0079] In some embodiments of the present application, the outgoing light beam of the light source 10 is split into the reference light beam and the incident light beam of the back drill stop layer by a beam splitter 201, and the back drill depth detection unit 702 is specifically configured to: determine a first distance between the back drill stop layer and the beam splitter 201 based on the first interference signal, acquire a second distance between the circuit board surface and the beam splitter 201, and determine the depth difference according to the first distance and the second distance.

[0080] In some embodiments of the present application, the back drill depth detection apparatus 700 further includes a system control unit configured to control the incident light beam of the back drill stop layer to enter the via sidewall along a preset direction before the first interference signal between the first reflected light and the reference light beam is acquired, an included angle between the preset direction and a vertical direction of the circuit board being a target angle, and the back drill depth detection unit 702 is specifically configured to: determine a wave path length of the incident light beam of the back drill stop layer from the beam splitter 201 to the back drill stop layer based on the first interference signal, and determine the first distance based on the target angle and the wave path length.

[0081] In some embodiments of the present application, the back drill depth detection unit 702 is specifically configured to: determine a position at which an interference intensity of the first reflected light and the reference light beam is greater than an intensity threshold based on the first interference signal, and determine the wave path length based on the position at which the interference intensity is greater than the intensity threshold.

[0082] In some embodiments of the present application, the back drill depth detection unit 702 is specifically configured to: determine the first distance based on a trigonometric function relationship between the target angle and the wave path length.

[0083] In some embodiments of this application, the back-drilling depth detection unit 702 is specifically used to: acquire a second interference signal between a second reflected light and a reference beam, wherein the second reflected light is reflected light from the circuit board surface reflecting an incident beam onto the circuit board surface, and the reference beam and the incident beam are obtained by splitting the outgoing beam of the light source; and determine the second distance based on the second interference signal.

[0084] In some embodiments of this application, the back-drilling depth detection unit 702 is specifically used for: acquiring a second interference signal between multiple second reflected beams and a reference beam, wherein different second reflected beams are reflected at different surface positions on the circuit board surface; determining the distance between the surface position corresponding to each second reflected beam and the beam splitter 201 based on the second interference signal between the multiple second reflected beams and the reference beam; and calculating the average value of the distance between the surface position corresponding to each second reflected beam and the beam splitter 201 to obtain the second distance.

[0085] In some embodiments of this application, the back-drilling depth detection device 700 further includes a back-drilling control unit, which, after determining the back-drilling depth based on the depth difference, controls the drill bit to perform back-drilling on the circuit board based on the back-drilling depth.

[0086] It should be noted that, for the sake of convenience and brevity, the specific working process of the aforementioned back-drilling depth detection device 700 can be found in the following reference: Figure 4 to Figure 6 The corresponding process of the method will not be described in detail here.

[0087] like Figure 8 The diagram shown is a schematic of a signal processing component 40 provided in an embodiment of this application. Specifically, the signal processing component 40 may include: a processor 400, a memory 401, and a computer program 402 stored in the memory 401 and executable on the processor 400, such as a back-drilling depth detection program. When the processor 400 executes the computer program 402, it implements the steps in the various back-drilling depth detection method embodiments described above, for example... Figure 4 Steps S401 to S402 are shown. Alternatively, when the processor 400 executes the computer program 402, it implements the functions of each module / unit in the above-described device embodiments, for example... Figure 7 The functions of the signal acquisition unit 701 and the back drill depth detection unit 702 shown are illustrated.

[0088] The computer program can be divided into one or more modules / units, which are stored in the memory 401 and executed by the processor 400 to complete the present application. The one or more modules / units can be a series of computer program instruction segments capable of completing a specific function, which are used to describe the execution process of the computer program in the signal processing component 40.

[0089] For example, the computer program can be divided into a signal acquisition unit and a back drilling depth detection unit. The specific functions of each unit are as follows: the signal acquisition unit is configured to acquire a first interference signal between a first reflected light and a reference light beam, the first reflected light being reflected light of an incident light beam of a back drilling stop layer of a circuit board reflected by the back drilling stop layer; the incident light beam of the back drilling stop layer enters a dielectric layer from a through-hole sidewall of the circuit board, and reaches the back drilling stop layer through the dielectric layer; the reference light beam and the incident light beam of the back drilling stop layer are obtained by splitting an outgoing light beam of a light source; the back drilling depth detection unit is configured to determine a depth difference between the back drilling stop layer and a circuit board surface of the circuit board based on the first interference signal, and determine a back drilling depth based on the depth difference.

[0090] The signal processing component 40 can include, but is not limited to, the processor 400 and the memory 401. Those skilled in the art can understand that, Figure 8 The signal processing component 40 is only an example and does not constitute a limitation on the signal processing component 40, and can include more or fewer components than those shown, or combine certain components, or different components, for example, the signal processing component 40 can also include an input / output device, a network access device, a bus, etc.

[0091] The processor 400 can be a central processing unit (CPU), and can also be other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), ready programmable gate arrays or other programmable logic devices, discrete gates or transistor logic components, discrete hardware components, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor.

[0092] The memory 401 can be an internal storage unit of the signal processing component 40, for example, a hard disk or a memory of the signal processing component 40. The memory 401 can also be an external storage device of the signal processing component 40, for example, a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) card, a Flash Card, etc. equipped on the signal processing component 40. Further, the memory 401 can include both the internal storage unit and the external storage device of the signal processing component 40. The memory 401 is used to store the computer program and other programs and data required by the signal processing component 40. The memory 401 can also be used to temporarily store data that has been output or is about to be output.

[0093] It should be noted that, for the convenience and brevity of description, the structure of the signal processing component 40 can also refer to the specific description of the structure in the method embodiments, which will not be described here.

[0094] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the above-mentioned division of each functional unit and module is exemplified, and in actual application, the above-mentioned functions can be completed by different functional units and modules according to needs, that is, the internal structure of the device is divided into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiment can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or software. In addition, the specific name of each functional unit and module is only for easy distinction, and does not limit the protection scope of the present application. The specific working process of the unit and module in the above system can refer to the corresponding process in the foregoing method embodiments, which will not be described here.

[0095] In the above embodiments, the description of each embodiment has its own emphasis, and the parts not described or recorded in detail in a certain embodiment can be referred to the related description of other embodiments.

[0096] Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be realized in electronic hardware or a combination of computer software and electronic hardware. Whether the functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. A person skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0097] In the embodiments of the present application, it should be understood that the disclosed apparatus / signal processing component 40 and method can be implemented in other manners. For example, the embodiments of the apparatus / signal processing component 40 described above are merely schematic. For example, the division of the modules or units is only a logical function division. There can be another division manner for the actual implementation, for example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections between the units can be indirect couplings or communication connections through some interfaces, devices or units, and can be electrical, mechanical or in other forms.

[0098] The units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, i.e., can be located in one place, or can be distributed on multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the embodiments.

[0099] In addition, each functional unit in the various embodiments of the present application can be integrated in one processing unit, or each unit can be a physically independent unit, or two or more units can be integrated in one unit. The integrated unit can be implemented in the form of hardware or in the form of a software functional unit.

[0100] The integrated module / unit, if implemented in the form of a software functional unit and sold or used as an independent product, can be stored in a computer readable storage medium. Based on such understanding, all or part of the flow of the method in the above embodiments can also be implemented by a computer program instructing related hardware to complete, and the computer program can be stored in a computer readable storage medium. When the processor executes the computer program, the steps of the above various method embodiments can be implemented. The computer program includes computer program code, which can be in the form of source code, object code, executable file or some intermediate form. The computer readable medium can include any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), electrical carrier signal, telecommunication signal and software distribution medium, etc. It should be noted that the computer readable medium can include appropriate contents according to the requirements of legislation and patent practice in the jurisdiction, for example, in some jurisdictions, according to legislation and patent practice, the computer readable medium does not include electrical carrier signals and telecommunication signals.

[0101] The above-described embodiments are only used to illustrate the technical solutions of the present application, but not limit the present application; although the present application is described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A method of detecting a back-drilling depth, characterized by, The method comprises: controlling an incident light beam of a back-drilling stop layer to enter a via sidewall of a circuit board along a preset direction, an included angle between the preset direction and a vertical direction of the circuit board being a target angle; the incident light beam of the back-drilling stop layer enters a medium layer from the via sidewall of the circuit board, and reaches the back-drilling stop layer through the medium layer; obtaining a first interference signal between a first reflected light and a reference light beam, the first reflected light being reflected light of the back-drilling stop layer of the circuit board reflected by the incident light beam of the back-drilling stop layer; the reference light beam and the incident light beam of the back-drilling stop layer being obtained by splitting an outgoing light beam of a light source by a beam splitter; determining a wave path length of the incident light beam of the back-drilling stop layer from the beam splitter to the back-drilling stop layer based on the first interference signal; determining a first distance between the back-drilling stop layer and the beam splitter based on the target angle and the wave path length; obtaining a second distance between the surface of the circuit board and the beam splitter; determining a depth difference between the back-drilling stop layer and the surface of the circuit board of the circuit board according to the first distance and the second distance, and determining a back-drilling depth based on the depth difference.

2. The method of back-drilling depth detection as claimed in claim 1, wherein, The method further comprises: determining a position where an interference intensity of the first reflected light and the reference light beam is greater than an intensity threshold based on the first interference signal; determining the wave path length based on the position where the interference intensity is greater than the intensity threshold.

3. The method of back-drilling depth detection as claimed in claim 1, wherein, The method further comprises: determining the first distance based on a trigonometric function relationship between the target angle and the wave path length.

4. The method of back-drilling depth detection as claimed in claim 1, wherein, The method further comprises: obtaining a second interference signal between a second reflected light and a reference light beam, the second reflected light being reflected light of the surface of the circuit board reflected by an incident light beam of the surface of the circuit board; determining the second distance based on the second interference signal.

5. The method of back-drilling depth detection as claimed in claim 4, wherein, The method further comprises: obtaining a second interference signal between a plurality of beams of second reflected light and a reference light beam, wherein different beams of second reflected light are reflected at different surface positions on the surface of the circuit board; The method further comprises: determining a distance between each beam of second reflected light and the beam splitter based on the second interference signal between the plurality of beams of second reflected light and the reference light beam; calculating a mean value of the distances between the surface positions corresponding to the beams of second reflected light and the beam splitter to obtain the second distance.

6. The method of back-drilling depth detection as claimed in any one of claims 1 to 5, wherein, After determining the back-drilling depth based on the depth difference, the method further comprises: controlling a drill bit to back-drill the circuit board based on the back-drilling depth.

7. A signal processing assembly comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, The processor executes the computer program to implement the steps of the method for detecting the back-drilling depth according to any one of claims 1 to 6.

8. A system for detecting a back drill depth, characterized by The apparatus comprises: a light source; an optical device group comprising a beam splitter and a reference mirror; The beamsplitter is configured to split an outgoing beam of the light source into a reference beam and an incident beam of the back drill stop layer; The reference mirror is configured to reflect the reference beam to the beamsplitter; the incident beam of the back drill stop layer enters from a through-hole sidewall of a circuit board, reaches the back drill stop layer through a medium layer, and is reflected by the back drill stop layer to form a first reflected light; A photosensitive component is configured to collect a first interference signal formed by interference between the first reflected light and the reference beam through the beamsplitter; A signal processing component is configured to perform the steps of the back drill depth detection method according to any one of claims 1 to 6.

9. A computer program product, characterised in that, The computer program, when being run, causes the back drill depth detection method according to any one of claims 1 to 6 to be performed.

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