Thickness change determination method and device of PCB (Printed Circuit Board), control method and equipment

Abstract

The invention relates to a thickness change determination method and device of a PCB, a control method and equipment, and the method comprises the following steps: obtaining coordinates of all target processing positions on the PCB; and after the PCB is subjected to the surface processing procedure, measuring the thickness variation of the target processing position. According to the invention, the thickness change of all target processing positions can be accurately measured, the problem of thickness difference of plating layers at different positions on one PCB and a plurality of PCBs is solved, the problem of measurement errors caused by indifference measurement of the overall thickness of the PCBs is avoided, the measurement result is more accurate, and the back drilling precision of the subsequent PCBs is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of PCB board processing technology, and in particular to a method, apparatus, control method and equipment for determining the thickness variation of PCB boards. Background Technology

[0002] Currently, in the printed circuit board (PCB) manufacturing industry, back-drilling is used to remove excess copper layers from hole walls to improve signal integrity. Its precision control involves multiple processes such as lamination, copper plating, and drilling. Existing control methods for improving the precision of back-drilled stubs mainly rely on optical and electrical detection methods. Depending on the target, back-drilling can be controlled by collecting the actual distance H from the back-drilled surface to the target layer, the back-drilling depth L, and the stub length D=HL. However, because the actual distance H of each hole changes with the PCB thickness, if the back-drilling depth is fixed, it is difficult to control the stub length of each back-drilled hole to maintain consistency. Summary of the Invention

[0003] This invention aims to solve the technical problems existing in the prior art, namely, under the condition of multiple processing steps, the thickness of the substrate, the thickness of the copper plating and the thickness of the ink layer at the back drilling processing position vary significantly with spatial position and batch. The existing methods that use fixed compensation values ​​or single-point thickness to represent the whole board and the whole batch cannot accurately reflect the actual thickness changes at each target processing position, resulting in a systematic deviation in the setting of the back drilling depth control target value. This causes the back drilling residual stud length to exceed the residual stud length tolerance range, and the back drilling processing accuracy and process capability index cannot meet the stringent control requirements of high-end PCB products for the back drilling residual stud length.

[0004] To achieve the objectives of this invention, the embodiments of this invention adopt the following technical solutions:

[0005] A method for determining the thickness variation of a PCB board includes the following steps:

[0006] Obtain the coordinates of all target machining locations on the PCB board;

[0007] After the PCB board undergoes surface processing, the thickness change at the target processing location is measured.

[0008] In some embodiments, the measurement of thickness change includes the following steps:

[0009] In the first measurement stage, the thickness of the PCB at all target processing locations is measured to obtain the first measurement value;

[0010] In the second measurement stage, after the PCB board has undergone surface processing, the thickness of the board at all target processing positions on the PCB board is measured again to obtain the second measurement value.

[0011] The thickness change is calculated based on the difference between the second measurement value and the first measurement value at the same target processing location, to determine the amount of thickness change at that location.

[0012] In some embodiments, the thickness change calculation step includes: calculating the difference between the second measurement value and the first measurement value, and determining half of the difference as the thickness change of one side of the surface at the target processing location.

[0013] In some embodiments, the thickness change is the thickness difference of the PCB board before and after the surface processing step. The first measurement stage is located after mechanical drilling of the PCB board and before the surface processing step of the PCB board. If the second measurement stage is located after copper plating of the PCB board, the thickness change is the copper plating thickness change. If the second measurement stage is located after ink is applied to the surface of the PCB board, the thickness change is the total thickness change of the ink layer and the copper layer.

[0014] In some embodiments, the target processing position is the position of the first drilled hole formed by mechanical drilling. When measuring the plate thickness, the measurement area is the annular area of ​​the processing area minus the area where the first drilled hole is located, and the width of the measurement area is 0.1 mm to 0.2 mm.

[0015] In some embodiments, the average thickness of several points within the measurement area is calculated, and the average thickness is used as the measurement value of the target processing position.

[0016] In some embodiments, with the center of the first drilled hole as the center, a number of concentric circles are radially divided at equal intervals within the annular area, and each concentric circle is provided with a number of equally divided measurement points.

[0017] In some embodiments, the diameter d of the borehole area and the diameter D of the first borehole satisfy the relationship: d = D + β, where the constant β ranges from 0.1 mm to 0.25 mm.

[0018] In some embodiments, when measuring the thickness change at the target processing location, the coating thickness at the target processing location is directly measured and the thickness change is calculated.

[0019] In some embodiments, the measurement of thickness change includes the following steps:

[0020] In the first measurement stage, the plating thickness at all target processing locations on the PCB board is measured to obtain the first measurement value;

[0021] In the second measurement stage, after the PCB board has undergone surface processing, the plating thickness of all target processing positions on the PCB board is measured again to obtain the second measurement value.

[0022] The thickness change is calculated based on the difference between the second measurement value and the first measurement value at the same target processing location, to determine the amount of thickness change at that location.

[0023] A detection device includes a processor and a memory, the processor being configured to perform a method for determining the thickness variation of the PCB board.

[0024] A method for controlling back-drilling residual piles involves obtaining the thickness change of a PCB board based on a PCB board thickness change determination method, and then correcting the preset back-drilling depth control target values ​​for all target processing positions based on the thickness change.

[0025] A drilling device includes a machine base, a spindle unit mounted on the machine base, and a control device; the control device includes a processor and a memory, the memory storing a computer program, and when the computer program is executed by the processor, it implements a back-drilling residual pile control method, and the control device drives the spindle unit to perform back-drilling processing on the target processing position according to the corrected back-drilling depth control target value.

[0026] The present invention has the following main advantages:

[0027] By measuring and calculating the thickness difference at the same target processing location (such as the first drill hole location) before and after the PCB board surface processing steps, the actual thickness change at each location can be accurately obtained. This effectively overcomes the compensation errors caused by uneven distribution of surface treatment layers such as copper plating and ink on the board surface and differences between boards in traditional methods. In particular, limiting the measurement area to the annular area around the first drill hole and using an averaging method with multiple concentric circles and multiple equally divided points further improves the representativeness and accuracy of the measurement values, ensuring the calculation accuracy of the thickness change on one side of the surface (such as the copper plating thickness or the total thickness of the ink and copper layers). Based on the thickness change obtained by this method, the target value of back-drilling depth control at each target processing location can be specifically corrected, allowing the drilling equipment to dynamically adjust processing parameters according to the actual situation at each location. This significantly improves the control accuracy of the back-drilling stub length, reduces the risk of stub exceeding tolerances, and thus meets the stringent requirements of high-end PCB products for back-drilling process capability index, improves product signal integrity and overall quality, and enhances the stub control accuracy between the same PCB board and different PCB boards. Other advantages of the technical solution of this invention are described in specific embodiments. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a flowchart of a method for determining the thickness variation of a PCB board according to an embodiment of the present invention.

[0030] Figure 2 This is a flowchart of a thickness change measurement method provided in an embodiment of the present invention.

[0031] Figure 3 This is a partial cross-sectional view of the PCB board after mechanical drilling, provided in an embodiment of the present invention.

[0032] Figure 4 This is a partial cross-sectional view of the copper-plated PCB board provided in an embodiment of the present invention.

[0033] Figure 5 This is a partial cross-sectional view of the PCB board after ink coating provided in an embodiment of the present invention.

[0034] Figure 6 This is a schematic diagram of the measurement area provided in an embodiment of the present invention.

[0035] Figure 7 This is a schematic diagram of concentric circles within the measurement area provided in an embodiment of the present invention.

[0036] Figure 8 This is a partial schematic diagram of the PCB board during back drilling provided in an embodiment of the present invention.

[0037] Figure 9 This is a partial schematic diagram of the PCB board after back drilling provided in an embodiment of the present invention.

[0038] In the attached diagram: 10 - PCB board; 11 - target processing position; 12 - upper surface; 13 - lower surface; 20 - first drill hole; 30 - copper layer; 40 - ink layer; 50 - drill bit; 60 - back drill hole. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0040] In this embodiment, "several" and "more than" refer to two or more. In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0041] <Example 1>

[0042] Currently, the main PCB back-drilling processes are as follows: 1. Lamination - Mechanical Drilling - PTH - Full Board Electroplating - Pattern Electroplating - Solder Mask - Back Drilling; 2. Lamination - Mechanical Drilling - PTH - Full Board Electroplating - Back Drilling - Pattern Electroplating - Solder Mask; 3. Lamination - Mechanical Drilling - PTH - Full Board Electroplating - Pattern Electroplating - Back Drilling - Solder Mask. In all of these processes, the back-drilling step occurs after electroplating. "Copper plating" on a PCB refers to the deposition of a layer of copper on the substrate surface or hole walls, a crucial process for achieving conductivity and mechanical support. Therefore, before back drilling, an additional layer of electroplated copper is added to the surface and inside the holes. Furthermore, PCBs may also undergo tin plating, ink coating, and other processes. The increased thickness of copper plating, tin plating, and ink coating is uneven. Currently, the thickness of electroplated copper varies by approximately 15µm depending on the process, which significantly impacts the control of back-drilled stubs. Currently, thickness compensation is typically based on theoretical copper plating thickness or single-point slicing measurements of the board edge, rather than the copper thickness of a single board or all boards in the entire batch, to control back-drill stub tolerances. However, copper plating thickness and ink thickness are uneven across different locations on the PCB board, and there are significant differences between different boards. Using theoretical values ​​or single-point measurements cannot accurately reflect the actual thickness distribution across the entire board surface, resulting in insufficient compensation accuracy and making it difficult to meet increasingly stringent tolerance requirements.

[0043] This embodiment of a method for determining the thickness variation of a PCB board includes the following steps: obtaining the coordinates of all target processing positions on the PCB board; and measuring the thickness variation at the target processing positions after the PCB board has undergone surface processing. The surface processing includes, but is not limited to, processes such as copper plating, tin plating, and ink coating that cause changes in the PCB board thickness. The thickness variation is the difference between the actual thickness of each target processing position after the surface processing and the original thickness before processing. By accurately locating the coordinates of all target processing positions on the PCB board and specifically measuring the thickness variation at each position, the thickness distribution across the entire board surface can be comprehensively understood, effectively avoiding the errors caused by relying solely on theoretical values ​​or single-point measurements and neglecting thickness non-uniformity in traditional methods.

[0044] Specifically, the PCB board in this embodiment undergoes the following processing steps: lamination - mechanical drilling - first board thickness measurement - PCB surface processing - second board thickness measurement - back drilling. The board thickness measured in this embodiment is the distance between the two surfaces of the PCB board. By changing the board thickness at each back drilling position, the back drilling depth is compensated, thereby controlling the stub accuracy of each back drill hole.

[0045] This embodiment of a method for determining the thickness variation of a PCB board includes the following steps:

[0046] S1: Obtain the coordinates of all target processing positions on the PCB board. The target processing positions are usually the first drilled hole positions formed in the mechanical drilling process of the PCB board. These positions are the key areas for subsequent back drilling processing. Their coordinate information can be directly extracted from the PCB board design file (such as Gerber file) or drilling program to ensure that the subsequent board thickness measurement can accurately correspond to each back drilling position to be processed.

[0047] S2: After the PCB board undergoes surface processing, the thickness change at the target processing location is measured. The thickness change is the actual change in the board thickness at the target processing location, thereby enabling more accurate acquisition of the actual thickness change at the target processing location for compensation, making subsequent processing more precise.

[0048] In this embodiment, the PCB board processing flow includes lamination, mechanical drilling, PCB surface processing steps (such as copper plating, ink coating, tin plating, etc.), and back drilling. Among them, the surface processing step is a key link affecting the thickness change. This method can effectively capture the thickness change caused by the process by performing targeted measurements on the target processing position after the surface processing step.

[0049] In one implementation, the thickness change measurement in step S2 is achieved through two stages: First, the first measurement stage completes the initial thickness measurement. After the PCB board completes mechanical drilling and before the surface processing begins, the thickness of all target processing locations is measured for the first time to obtain a first measurement value. This value reflects the initial thickness state of the PCB board in the critical back-drilling area after mechanical drilling and before surface processing. Then, the second measurement stage is performed, i.e., a second thickness measurement. After the PCB board completes the surface processing, the thickness of the same batch of target processing locations is measured again to obtain a second measurement value. This value includes the thickness contribution of the surface processing layers (copper layer, ink layer, etc.). By calculating the difference between the second measurement value and the first measurement value for the same target processing location, the total thickness change at that location due to the surface processing can be obtained. If surface finishing is typically performed simultaneously on both the top and bottom surfaces of the PCB, to accurately obtain the thickness variation on one side of the surface (e.g., only focusing on the copper plating thickness of the top surface), half of the aforementioned difference can be determined as the thickness variation on one side of the surface at the target finishing location. This approach can more accurately meet the requirements of back-drilling depth control for compensation of the plating thickness on one side. For example, if the first measurement value before copper plating at a target finishing location is 1.5mm, and the second measurement value after copper plating is 1.54mm, the difference is 0.04mm, then the change in copper plating thickness on one side of the surface is 0.02mm. This data will be directly used to correct the target value for subsequent back-drilling depth control.

[0050] Specifically, such as Figures 2 to 6 As shown in the figure, this embodiment provides a method for determining the thickness variation of a PCB board, which includes the following steps:

[0051] In the first measurement stage (S21), the thickness of the PCB board at all target processing locations is measured to obtain the first measurement value. Specifically, as follows... Figure 2 As shown, after mechanical drilling, the PCB board forms the first drilled hole 20. Before the PCB board 10 enters the surface processing steps (such as copper plating or ink coating), a high-precision board thickness measuring instrument is used to measure the board thickness of all the pre-set target processing positions 11 on the PCB board, obtaining a first measurement value T1(i), which is used to represent the i-th target processing position, where i can be 1, 2, 3, ..., n. In this embodiment, the PCB board processing is double-sided processing, that is, both the upper and lower surfaces are processed. Therefore, the first measurement value T1(i) is the distance between the upper surface 12 and the lower surface 13 of the PCB board. These target processing positions are preferably the positions of the first drilled hole 20 formed by mechanical drilling. During back drilling, these first drilled hole positions need to be drilled a second time to remove excess copper layer. Therefore, the thickness variation of the first drilled hole position directly affects the control accuracy of the back drill residual pile length.

[0052] In the second measurement stage (S22), after the surface processing step, the thickness of all target processing positions on the PCB board 10 is measured again to obtain a second measurement value. The PCB board completes at least one surface processing step, such as full-surface electroplating, selective electroplating, or solder mask coating. In this embodiment, the second measurement stage is preferably performed on the same batch of substrates after copper plating or solder mask coating. Specifically, after surface processing, other materials are superimposed on the upper and lower surfaces of the PCB board, thus increasing its thickness. At this time, a high-precision thickness measuring instrument is used to measure the thickness of the same batch of target processing positions 11 on the PCB board again to obtain a second measurement value T2(i), which also represents the i-th target processing position. This second measurement value T2(i) is also the distance between the upper and lower surfaces of the PCB board after surface processing. If the surface processing step is copper plating, T2(i) includes the thickness of the copper plating layer; if it is ink coating, T2(i) includes the thickness of the ink layer. Figure 3 As shown, after mechanical drilling, the PCB board is copper-plated to form a copper layer 30. The second measurement value T2(i) at this time is the total board thickness including the copper layer 30. By comparing the board thickness data of the same target processing location 11 in the first and second measurement stages, the thickness change at that location caused by surface processing can be accurately captured. Figure 4 As shown, if an ink layer 40 is applied after copper plating, the second measurement value is the distance between the ink layers 40 on the upper and lower surfaces.

[0053] S23 Thickness Change Calculation: Based on the difference between the second measured value and the first measured value at the same target processing location, the thickness change at that location is calculated. Specifically, for each target processing location i, the difference ΔT(i) = T2(i) - T1(i) between the second measured value T2(i) and the first measured value T1(i) is calculated. In this embodiment, since PCB boards are usually double-sided processed, plating or coating is formed on both the upper and lower surfaces. Therefore, the difference ΔT(i) is the sum of the thickness increases on the upper and lower surfaces. To obtain the thickness change on one side of the surface, half of the difference ΔT(i) is determined as the thickness change t(i) on one side of the target processing location, i.e., t(i) = ΔT(i) / 2. For example, if the first measured value T1(i) at a target processing location is 1.0 mm and the second measured value T2(i) is 1.04 mm, then ΔT(i) is 0.04 mm, and the thickness change t(i) on one side of the surface is 0.02 mm. The thickness change t(i) can be either the change in copper plating thickness or the total thickness change of the copper and ink layers, depending on the surface processing steps. If the second measurement stage occurs after copper plating on the PCB board, then t(i) represents the thickness change of the copper layer after copper plating; if the second measurement stage occurs after ink is applied to the PCB board surface, then t(i) represents the total thickness change of the copper and ink layers. This method of calculating the thickness change separately for each target processing location effectively overcomes the problems of uneven thickness distribution on the board surface and batch-to-batch differences, providing a reliable data foundation for precise control of subsequent back-drilling residual piles. If the PCB board is only processed on one side, the thickness change at the corresponding target location can be calculated using ΔT(i) = T2(i) - T1(i).

[0054] Furthermore, in the first and second measurement stages, the thickness of all target processing locations on the PCB board is measured. These target processing locations are the positions of the first drill holes formed by mechanical drilling. By measuring the thickness of each first drill hole position, the critical areas of back-drilling can be fully covered, avoiding local deviations caused by sampling measurements. During back-drilling, the drill bit enters the PCB board from the position of the first drill hole 20. Therefore, the thickness variation at the first drill hole position directly determines the thickness of material to be removed during back-drilling, thus affecting the length of the residual pile. Measuring all first drill hole positions as target processing locations ensures full coverage of the back-drilling processing area, allowing each back-drilling point to obtain its own specific thickness variation data, avoiding the problem of missing thickness differences in critical areas due to selecting only a portion of the points.

[0055] Furthermore, in the thickness measurement, the measurement area is the processing area minus the area of ​​the first drilled hole. The processing area is a circular region with a radius of r centered on the center P of the first drilled hole. Since the first drilled hole itself is a through hole, its interior is not a solid substrate. Including the area inside the hole in the measurement may lead to distorted measurement values, failing to accurately reflect the actual thickness change of the substrate. The processing area is adjacent to the actual processing position of the back drill, accurately reflecting the thickness state of the substrate during back drilling, while avoiding the hollow part of the first drilled hole, ensuring the accuracy and representativeness of the measurement data. Through this precise definition of the measurement area, both the first and second measurement values ​​can accurately reflect the thickness of the solid portion of the substrate at the target processing position, thereby ensuring the accuracy of subsequent thickness change calculations. Specifically, for each target processing location, a circular processing area with radius r is defined, centered on the center of the first drilled hole formed by mechanical drilling. The radius of the first drilled hole is R, where r > R. During plate thickness measurement, the measurement area is the annular measurement area M formed by subtracting the first drilled hole area from the processing area. The width of measurement area M is 0.1mm to 0.2mm. This width setting ensures that the annular area tightly surrounds the first drilled hole, avoiding non-solid parts within the hole and ensuring the correlation and accuracy of the measurement results with the back-drilling process. By measuring points within measurement area M using a thickness measuring device, this multi-point sampling, multiple measurement, and data optimization process maximizes the reliability and accuracy of the measurement results, providing high-quality basic data for subsequent calculations of thickness variations.

[0056] Specifically, during measurement, the thickness values ​​of N points within the measurement area M are obtained, and the average thickness of the N points is calculated. This average thickness is used as the measurement value for the target processing location. Averaging over the annular measurement area ensures that the obtained thickness measurement data more closely approximates the actual local material accumulation experienced by the target processing location during electroplating and solder resist coating. Furthermore, to improve measurement accuracy, several concentric circles are radially divided within the annular area, centered on the center P of the initial drill hole. Each concentric circle has several equally spaced measurement points. For example, if r = 1.9 mm and the initial drill hole R = 0.3 mm, then the width of the annular area is 1.6 mm. Four equally spaced concentric circles a1 to a4 are set, with a spacing of 0.4 mm and radii of 0.7 mm, 1.1 mm, 1.5 mm, and 1.9 mm respectively. Each circle has 10 measurement points Q, for a total of 40 sampling points. Different weights are assigned based on the distance between the measurement point and the center of the back drill hole; the closer the distance, the higher the weight. Weight calculation formula: w_i = 1 / (r_i + ε), where r_i is the radial distance from the measurement point to the center of the circle (unit: mm), ε is a small constant (valued at 0.1 mm to avoid zero in the denominator), and the final average thickness is: T_avg = Σ(w_i * T_i) / Σw_i.

[0057] Furthermore, in this embodiment, the diameter d of the drilling area and the diameter D of the first drilled hole satisfy the relationship: d = D + β, where the constant β ranges from 0.1 mm to 0.25 mm. When the drilling area is back-drilled, the drill bit drills down to form a back-drilled hole. This design can ensure that the back-drilled area completely covers the first drilled hole, completely cut off the copper pillar residue on the wall of the first drilled hole, and at the same time avoid damage to other circuits or components on the PCB board due to the drilling area being too large.

[0058] The above technical solution measures the board thickness at all target processing positions (first drill position) after mechanical drilling and before back drilling. The actual thickness change at each position is calculated by the difference between the two data points. This yields the actual thickness change value at the target processing position. It accurately captures the thickness changes at the same target processing position caused by surface processing (such as copper plating, ink coating, etc.), providing crucial compensation for precise control of the back drilling residual length. This effectively solves the systematic deviation problem caused by traditional fixed compensation values ​​or single-point thickness representing the entire board and batch. By calculating the thickness change individually for each target processing position, it fully considers the uneven distribution of thickness changes on the board surface and batch differences, ensuring that each back drilling point obtains its corresponding thickness change data. This lays a solid foundation for the dynamic and precise setting of the back drilling depth control target value, significantly improving back drilling processing accuracy and process capability index to meet the stringent control requirements of high-end PCB products for back drilling residual length.

[0059] <Example 2>

[0060] In this embodiment, the parts that are the same as in Embodiment 1 are given the same reference numerals, and the same text descriptions are omitted.

[0061] Compared to Embodiment 1, this embodiment provides a method for determining the thickness variation of a PCB board. The difference lies in the measurement object; this embodiment directly measures the plating thickness. It directly measures the plating thickness at the target processing location and calculates the thickness variation. Direct measurement of plating thickness can be performed using measuring devices such as X-ray fluorescence thickness gauges or laser confocal microscopes. X-ray fluorescence thickness gauges emit X-rays to excite plating atoms to produce characteristic fluorescence, and based on the quantitative relationship between fluorescence intensity and plating thickness, directly measure the thickness of the plating on the surface of the target processing location. Laser confocal microscopes use a laser beam focused on the plating surface, scanning to obtain three-dimensional morphological data of the plating, and then calculate the plating thickness. This direct measurement method is suitable for scenarios with extremely high requirements for plating thickness accuracy. Furthermore, if the plating is a copper layer, the microresistivity method can also be used, measuring the resistance of the copper layer using a four-probe contact method to estimate the thickness.

[0062] Specifically, the PCB board processing flow in this embodiment is as follows: lamination - mechanical drilling - first plating thickness measurement - PCB surface processing - second plating thickness measurement - back drilling.

[0063] The measurement of thickness variation includes the following steps:

[0064] In the first measurement stage, the plating thickness at all target processing locations on the PCB board is measured, thus completing the first plating thickness measurement and obtaining the first measurement value B1. In this embodiment, copper is used as an example for the plating. The first plating thickness measurement measures the copper layer thickness at each back-drilled hole location on the PCB board surface after mechanical drilling. The copper layer thickness of the first measurement value B1 is the surface copper layer during PCB board lamination.

[0065] In the second measurement stage, after the PCB board undergoes surface processing, the plating thickness at all target processing locations on the PCB board is measured again to obtain the second measurement value B2. After processes such as copper plating, the surface of the PCB board gains an additional layer of thickness. At this time, the copper thickness of each hole is measured again before back drilling to obtain the second measurement value B2.

[0066] The thickness variation is calculated based on the difference between the second and first measured values ​​at the same target processing location, determining the thickness variation at that location. Since the measurement is of single-sided copper thickness, the plating thickness variation for each hole is calculated using B2-B1.

[0067] <Example 3>

[0068] In this embodiment, the parts that are the same as in Embodiment 1 and Embodiment 2 are given the same reference numerals, and the same text descriptions are omitted.

[0069] Compared to Embodiments 1 and 2, this embodiment provides a detection device, including a processor and a memory. The processor is configured to execute the PCB board thickness variation determination method to accurately calculate the thickness variation of the target processing position on the PCB board. The detection device also includes a measurement module connected to the processor. The measurement module is used to measure the thickness of the target processing position on the PCB board in a first measurement stage and a second measurement stage, respectively, and obtain a first measurement value and a second measurement value. The measurement module can use high-precision board thickness measurement instruments such as laser thickness gauges and contact thickness sensors. To achieve automatic measurement of multiple target processing positions on the PCB board, the detection device may also include a positioning mechanism and a transfer mechanism mounted on the machine body. The positioning mechanism is used to accurately position the PCB board to be measured, ensuring that the measurement module can accurately align with the target processing position. The transfer mechanism is used to move the measurement module, enabling the measurement module to sequentially measure all target processing positions on the PCB board. During the measurement process, the processor controls the transfer mechanism and the measurement module to work together, collecting thickness data of the measurement area of ​​each target processing position according to a preset measurement sequence, and storing the collected first and second measurement values ​​in the memory. Subsequently, the processor, based on the first and second measurement values ​​stored in the memory, executes the thickness change calculation steps as described in Embodiment 1 to obtain the thickness change at each target processing position. The calculation results can then be sent to the control device of the back-drilling processing equipment, providing data support for the precise control of the back-drilled pile length. Furthermore, the detection device may also include a human-machine interface, allowing operators to set measurement parameters (such as the number and distribution of target processing positions, the radius of the measurement area, etc.), start the measurement process, and view measurement results and thickness change calculation data, thus improving the device's ease of operation and practicality.

[0070] <Example 4>

[0071] In this embodiment, the parts that are the same as in Embodiments 1 to 3 are given the same reference numerals, and the same text descriptions are omitted.

[0072] Compared with embodiments one to three, this embodiment provides a back-drilling residual pile control method, which obtains the thickness change of the PCB board according to the PCB board thickness change determination method, and corrects the preset back-drilling depth control target value of all target processing positions according to the thickness change.

[0073] Specifically, the back-drilling depth control target value correction step includes: obtaining the initial back-drilling depth control target value H0(i) for each target processing position, which is determined based on the theoretical board thickness and preset residual pile length in the PCB design file; superimposing the thickness change t(i) of the target processing position with the initial back-drilling depth control target value H0(i) to obtain the corrected back-drilling depth control target value H(i) = H0(i) + t(i). For example, if the initial back-drilling depth control target value H0(i) of a certain target processing position is 0.8mm, and the thickness change t(i) of that position is calculated to be 0.02mm using the thickness change determination method, then the corrected back-drilling depth control target value H(i) is 0.82mm. When back-drilling the target processing position, the back-drilling processing equipment will perform depth control according to the corrected H(i) value, thereby compensating for the increase in board thickness caused by surface processing and ensuring that the actual residual pile length is consistent with the design requirements. Furthermore, the initial back-drilling depth control target value H0(i) is calculated using the formula H0(i) = T_design(i) - L_stub(i), where T_design(i) is the theoretical plate thickness at the target processing position in the design file, and L_stub(i) is the preset residual pile length. By feeding back the thickness variation t(i) to the back-drilling depth control system in real time, dynamic adjustment of processing parameters is achieved, avoiding the problem of excessively long or short residual piles caused by plate thickness fluctuations in traditional fixed-parameter processing.

[0074] <Example 5>

[0075] In this embodiment, the parts that are the same as in Embodiment 1 are given the same reference numerals, and the same text descriptions are omitted.

[0076] like Figure 7 and Figure 8 As shown, compared to Embodiments 1 to 4, this embodiment provides a drilling device, including a machine base, a spindle unit mounted on the machine base, and a control device. The spindle unit drives a drill bit 50 to drill into a first drill hole, removing part of the copper layer in the first drill hole to form a back drill hole 60, thus completing the back drilling. The control device includes a processor and a memory. The memory stores a computer program, which, when executed by the processor, implements the back drilling residual pile control method. The control device drives the spindle unit to perform back drilling processing on the target processing position according to the corrected back drilling depth target value.

[0077] For example, before the back drilling process begins after the PCB board has completed the copper plating process, the control device corrects the initial back drilling depth target value H0(i) by calling the copper layer thickness variation t(i) of each target processing position stored in the memory, resulting in H(i) = H0(i) + t(i). After receiving the processing command from the control device, the spindle unit's drill bit will control the feed depth according to the corrected H(i) value, accurately removing the copper layer and part of the substrate material at the target processing position, ensuring that the length of the residual pile after back drilling is strictly controlled within the preset range.

[0078] In the above embodiments one to five, during the working process, depending on the different working environments, some of the technical implementation methods of embodiments one to five can be combined or replaced.

[0079] The technical principles of the present invention have been described above in conjunction with specific embodiments. However, it should be noted that these descriptions are merely for explaining the principles of the present invention and should not be construed as limiting the scope of protection of the present invention in any way. Based on this explanation, those skilled in the art can conceive of other specific embodiments or equivalent substitutions of the present invention without creative effort, and all such embodiments will fall within the scope of protection of the present invention.

Claims

1. A method for determining the thickness variation of a PCB board, characterized in that, Includes the following steps: Obtain the coordinates of all target machining locations on the PCB board; After the PCB board undergoes surface processing, the thickness change at the target processing location is measured.

2. The method for determining the thickness variation of a PCB board according to claim 1, characterized in that, The measurement of thickness variation includes the following steps: In the first measurement stage, the thickness of the PCB at all target processing locations is measured to obtain the first measurement value; In the second measurement stage, after the PCB board has undergone surface processing, the thickness of the board at all target processing positions on the PCB board is measured again to obtain the second measurement value. The thickness change is calculated based on the difference between the second measurement value and the first measurement value at the same target processing location, to determine the amount of thickness change at that location.

3. The method for determining the thickness variation of a PCB board according to claim 2, characterized in that, The thickness change calculation step includes: calculating the difference between the second measurement value and the first measurement value, and determining half of the difference as the thickness change of one side of the surface at the target processing position.

4. The method for determining the thickness variation of a PCB board according to claim 2, characterized in that, The thickness change is the difference in thickness of the PCB board before and after the surface processing step. The first measurement stage is after the mechanical drilling of the PCB board and before the surface processing step. If the second measurement stage is after copper plating of the PCB board, the thickness change is the thickness change of the copper plating. If the second measurement stage is after ink is applied to the surface of the PCB board, the thickness change is the total thickness change of the ink layer and the copper layer.

5. The method for determining the thickness variation of a PCB board according to claim 1, characterized in that, The target processing position is the position of the first drilled hole formed by mechanical drilling. When measuring the plate thickness, the measurement area is the annular area after deducting the area where the first drilled hole is located from the processing area, and the width of the measurement area is 0.1mm to 0.2mm.

6. The method for determining the thickness variation of a PCB board according to claim 5, characterized in that, Calculate the average thickness at several points within the measurement area, and use this average thickness as the measured value for the target processing position.

7. The method for determining the thickness variation of a PCB board according to claim 6, characterized in that, Centered on the center of the first borehole, the annular area is divided into several concentric circles at equal intervals, and several equally divided measurement points are set in each concentric circle.

8. The method for determining the thickness variation of a PCB board according to claim 7, characterized in that, The diameter d of the borehole area and the diameter D of the first borehole satisfy the following relationship: d = D + β, where the constant β ranges from 0.1 mm to 0.25 mm.

9. The method for determining the thickness variation of a PCB board according to claim 1, characterized in that, When measuring the thickness change at the target processing location, the coating thickness at the target processing location is directly measured and the thickness change is calculated.

10. The method for determining the thickness variation of a PCB board according to claim 9, characterized in that, The measurement of thickness variation includes the following steps: In the first measurement stage, the plating thickness at all target processing locations on the PCB board is measured to obtain the first measurement value; In the second measurement stage, after the PCB board has undergone surface processing, the plating thickness of all target processing positions on the PCB board is measured again to obtain the second measurement value. The thickness change is calculated based on the difference between the second measurement value and the first measurement value at the same target processing location, to determine the amount of thickness change at that location.

11. A detection device, characterized in that, It includes a processor and a memory, the processor being configured to perform the PCB board thickness variation determination method according to any one of claims 1 to 10.

12. A method for controlling residual piles from back drilling, characterized in that, The PCB board thickness variation determination method according to any one of claims 1 to 10 obtains the PCB board thickness variation amount, and corrects the preset back drilling depth control target value for all target processing positions based on the thickness variation amount.

13. A drilling device, characterized in that, The system includes a machine body, a spindle unit mounted on the machine body, and a control device. The control device includes a processor and a memory. The memory stores a computer program. When the computer program is executed by the processor, it implements the back-drilling residual pile control method as described in claim 12. The control device drives the spindle unit to perform back-drilling processing on the target processing position according to the corrected back-drilling depth control target value.

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