A sectional analysis method for PCB positioning cutting

Abstract

The present application relates to printed circuit board cross-section analysis technical field, especially to a kind of cross-section analysis method of PCB positioning cutting, the present application is positioned target abnormal area from PCB board by optical microscope, optical microscope not only can observe sample surface topography, and for the topography within a certain range below surface can also be observed, while optical microscope is very sensitive and accurate to the identification of color, compared with the target abnormal area from PCB board positioned by scanning electron microscope in the prior art, target abnormal area can be more effectively positioned from PCB board, to reduce the positioning difficulty of target abnormal area purposes.In addition, the present application can improve the cross-section sample cutting precision on the basis of depositing positioning layer and protective layer in target abnormal area, avoid the physical and chemical damage of cross-section sample in cutting process, so as to improve the precision of failure analysis to PCB board.

Description

Technical Field

[0001] This invention relates to the field of printed circuit board cross-section analysis technology, and in particular to a cross-section analysis method for PCB positioning and cutting. Background Technology

[0002] With the rapid development of electronic technology, packaged circuit boards (PCBs), as core components of electronic devices, are crucial to the stable operation of the entire system due to their performance and reliability. However, under the influence of complex electromagnetic environments, thermal stress, and mechanical stress, PCBs inevitably experience various failure phenomena, such as cracks, delamination, open circuits, and short circuits. These failures not only affect the performance of electronic devices but can also lead to equipment damage or safety accidents in severe cases. Therefore, in-depth analysis of the causes of PCB failures, identification of failure mechanisms, and implementation of corresponding improvement measures are of great significance for improving the reliability and extending the service life of electronic devices.

[0003] Currently, common failure analysis methods typically involve obtaining surface morphology and composition information of the failed packaging substrate using a scanning electron microscope (SEM), locating anomalies on the packaging substrate based on the surface morphology and composition information, and then using a focused ion beam to cut out cross-sectional samples from the anomalies. Failure analysis is then performed on the cross-sectional samples to determine the cause of failure of the failed packaging substrate.

[0004] However, the electron beam of a scanning electron microscope has very little penetrating power into the packaged substrate, and the scanning electron microscope can only display monochrome (gray) images, resulting in poor imaging effect. The gray image can only show the surface or subsurface details of the packaged substrate. When there are non-surface abnormal areas (such as embedded foreign objects) or shallow surface color abnormal areas (such as ink color difference) on the packaged substrate, the target abnormal area cannot be effectively observed, and thus it is impossible to accurately locate the abnormal area on the failed packaged substrate.

[0005] Therefore, existing methods for analyzing the cross-section of packaging substrates have the problem of difficulty in locating abnormal areas. Summary of the Invention

[0006] This invention provides a cross-sectional analysis method for PCB positioning and cutting to solve the problem that existing cross-sectional analysis methods for packaging substrates have difficulty in locating target abnormal areas.

[0007] A cross-sectional analysis method for PCB positioning and cutting includes: The failed PCB board was observed using an optical microscope to determine the target abnormal area of ​​the PCB board. Under the observation of the optical microscope, cutting and positioning marks corresponding to the target abnormal area are marked on the PCB board using nanomechanical needles; The focused electron beam is controlled according to the preset first deposition parameters to deposit a positioning layer in the target abnormal area according to the cutting positioning mark. Based on the positioning layer, the focused ion beam is controlled according to the preset second deposition parameters to deposit a protective layer on the positioning layer. Under the protection of the protective layer, the focused ion beam is controlled according to preset cutting parameters to cut the target abnormal region and obtain a cross-sectional sample; Cross-sectional analysis was performed on the cross-sectional sample to determine the cause of failure of the PCB board.

[0008] Optionally, in the above-mentioned PCB positioning and cutting cross-sectional analysis method, the step of observing the failed PCB board with an optical microscope to determine the target abnormal area of ​​the PCB board includes: According to the preset optical magnification, the optical microscope is used to observe whether there are any candidate abnormal areas on the PCB board under bright field light source or dark field light source respectively; If, under the bright field light source, the PCB board is not observed to have the candidate abnormal area, and under the dark field light source, the PCB board is observed to have the candidate abnormal area, then the candidate abnormal area is determined to be the target abnormal area.

[0009] Optionally, in the above-mentioned PCB positioning and cutting cross-section analysis method, the optical magnification is greater than or equal to 10KX.

[0010] Optionally, the PCB positioning and cutting cross-sectional analysis method described above includes the step of controlling the focused electron beam according to preset first deposition parameters to deposit a positioning layer in the target abnormal area according to the cutting positioning mark, and then, based on the positioning layer, controlling the focused ion beam according to preset second deposition parameters to deposit a protective layer on the positioning layer, comprising: Metal is sputtered and deposited in the target abnormal area, and the conductivity of the target abnormal area is tested by grounding with a multimeter. If the target anomalous region is determined to be conductive, the focused electron beam is controlled according to the first deposition parameters, and the deposited metal is deposited in the target anomalous region according to the cutting and positioning marks to obtain the positioning layer; Tilt the PCB board to a preset target angle; Based on the positioning layer, the protective layer is deposited on the positioning layer by controlling the focused ion beam according to the second deposition parameters.

[0011] Optionally, in the above-mentioned PCB positioning and cutting cross-sectional analysis method, the deposited metal may include any one or more of platinum (Pt), carbon (C), and gold (Au).

[0012] Optionally, in the above-mentioned PCB positioning and cutting cross-section analysis method, the first deposition parameters include a first deposition voltage and a first deposition beam current, and the second deposition parameters include a second deposition voltage and a second deposition beam current, wherein the first deposition voltage is less than the second deposition voltage, and the first deposition beam current is greater than the second deposition beam current.

[0013] Optionally, the cutting parameters in the above-mentioned PCB positioning and cutting cross-section analysis method include a first cutting parameter and a second cutting parameter; Under the protection of the protective layer, the focused ion beam is controlled according to preset cutting parameters to cut the target abnormal region to obtain a cross-sectional sample, including: The focused ion beam is controlled to coarsely cut the target abnormal region according to the first cutting parameters; After the coarse cutting is completed, the focused ion beam is controlled according to the second cutting parameters to perform fine cutting on the target abnormal region to obtain the cross-sectional sample.

[0014] Optionally, in the above-mentioned PCB positioning and cutting cross-section analysis method, the first cutting parameters include a first cutting voltage and a first cutting beam current, and the second cutting parameters include a second cutting voltage and a second cutting beam current. The first cutting voltage may be equal to or not equal to the second cutting voltage, and the first cutting beam current is greater than the second cutting beam current.

[0015] Optionally, in the above-mentioned PCB positioning and cutting cross-sectional analysis method, the image resolution of the optical microscope is greater than 200nm.

[0016] Optionally, in the above-mentioned PCB positioning and cutting cross-sectional analysis method, the cutting positioning marks include a starting point, an ending point, a left positioning point, and a right positioning point.

[0017] This invention provides a cross-sectional analysis method for locating and cutting PCBs. The method involves observing a failed PCB board using an optical microscope to identify the target abnormal region. Under the optical microscope, nanomechanical needles are used to mark the target abnormal region on the PCB board with corresponding cutting positioning marks. A focused electron beam is controlled according to preset first deposition parameters to deposit a positioning layer on the target abnormal region according to the cutting positioning marks. Based on this positioning layer, a focused ion beam is controlled according to preset second deposition parameters to deposit a protective layer on the positioning layer. Under the protection of the protective layer, the target abnormal region is cut using a focused ion beam controlled according to preset cutting parameters to obtain a cross-sectional sample. Cross-sectional analysis is performed on the cross-sectional sample to determine the cause of the PCB board failure. As can be seen, this invention locates the target abnormal region on the PCB board using an optical microscope. The optical microscope can observe not only the surface morphology of the sample but also the morphology within a certain range below the surface. Furthermore, the optical microscope is highly sensitive and accurate in color recognition. Compared to locating the target abnormal region on the PCB board using a scanning electron microscope, this method can more effectively locate the target abnormal region, thus reducing the difficulty of locating the target abnormal region. In addition, by depositing a positioning layer and a protective layer in the target abnormal area, this invention can improve the cutting accuracy of cross-sectional samples while avoiding physical and chemical damage to the cross-sectional samples during the cutting process, thereby improving the accuracy of failure analysis of PCB boards. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the 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.

[0019] Figure 1 This is a flowchart illustrating an implementation of a PCB positioning and cutting cross-sectional analysis method according to an embodiment of the present invention. Figure 2 This is a partial flowchart of the PCB positioning and cutting cross-sectional analysis method in one embodiment of the present invention; Figure 3 This is a partial flowchart of the PCB positioning and cutting cross-sectional analysis method in one embodiment of the present invention; Figure 4 This is a partial flowchart of the PCB positioning and cutting cross-sectional analysis method in one embodiment of the present invention. Detailed Implementation

[0020] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0021] It should be understood that, when used in this specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0022] It should also be understood that the term “and / or” as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0023] As used in this specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if [described condition or event] is detected" may be interpreted, depending on the context, as meaning "once determined," "in response to determination," "once [described condition or event] is detected," or "in response to detection of [described condition or event]."

[0024] Furthermore, in the description of this invention and the appended claims, the terms "first," "second," "third," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance.

[0025] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of the invention include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, phrases such as "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0026] This invention provides a cross-sectional analysis method for locating and cutting PCBs. The method involves observing a failed PCB board using an optical microscope to identify the target abnormal region. Under the optical microscope, nanomechanical needles are used to mark the target abnormal region on the PCB board with corresponding cutting positioning marks. A focused electron beam is controlled according to preset first deposition parameters to deposit a positioning layer on the target abnormal region according to the cutting positioning marks. Based on this positioning layer, a focused ion beam is controlled according to preset second deposition parameters to deposit a protective layer on the positioning layer. Under the protection of the protective layer, the target abnormal region is cut using a focused ion beam controlled according to preset cutting parameters to obtain a cross-sectional sample. Cross-sectional analysis is performed on the cross-sectional sample to determine the cause of the PCB board failure. As can be seen, this invention locates the target abnormal region on the PCB board using an optical microscope. The optical microscope can observe not only the surface morphology of the sample but also the morphology within a certain range below the surface. Furthermore, the optical microscope is highly sensitive and accurate in color recognition. Compared to locating the target abnormal region on the PCB board using a scanning electron microscope, this method can more effectively locate the target abnormal region, thus reducing the difficulty of locating the target abnormal region. Furthermore, by depositing a positioning layer and a protective layer in the target abnormal area, this invention can improve the cutting accuracy of cross-sectional samples while avoiding physical and chemical damage to the cross-sectional samples during the cutting process, thereby improving the accuracy of failure analysis of PCB boards. Specific embodiments are described below.

[0027] In one embodiment, such as Figure 1 As shown, a cross-sectional analysis method for PCB positioning and cutting is disclosed, which specifically includes the following steps: S101: Observe the failed PCB board using an optical microscope to determine the target abnormal area of ​​the PCB board.

[0028] In this embodiment, the optical microscope has an image resolution greater than 200 nm.

[0029] When a PCB board fails, in order to improve the efficiency of failure analysis, it is necessary to first locate the target abnormal area on the PCB board, and then perform failure analysis on the PCB board based on the target abnormal area.

[0030] In this specific implementation, the PCB board is observed using an optical microscope to determine the target abnormal area of ​​the PCB board. The target abnormal area includes, but is not limited to, non-surface target abnormal areas (such as embedded foreign objects) or shallow surface color difference abnormalities (such as ink color difference). When embedded foreign objects or ink color difference are observed on the failed PCB board through an optical microscope, the corresponding area is determined as the target abnormal area.

[0031] S102: Under the observation of an optical microscope, cutting and positioning marks corresponding to the abnormal areas of the target are marked on the PCB board using nanomechanical needles.

[0032] In this specific implementation, a micro-marking operation platform can be used to mark the cutting and positioning marks corresponding to the target abnormal area on the PCB board. The micro-marking operation platform includes an optical microscope, mechanical nanoneedles, and a stage. The stage is used to fix the PCB board, the optical microscope is used to observe the target abnormal area on the PCB board, and the mechanical nanoneedles are used to mark the cutting and positioning marks corresponding to the target abnormal area on the PCB board. The mechanical nanoneedles are controlled by a mechanical nanoneedle operating system, which includes an operating software control platform, a three-axis driven robotic arm, a real-time display screen, and nanoneedle tips (with an accuracy of 1±0.1μm). The display screen displays the imaging image from the optical microscope.

[0033] S103: Control the focused electron beam according to the preset first deposition parameters to deposit a positioning layer in the target abnormal area according to the cutting positioning mark, and on the basis of the positioning layer, control the focused ion beam according to the preset second deposition parameters to deposit a protective layer on the positioning layer.

[0034] The positioning layer provides a positional reference for subsequent deposition of the protective layer and cutting of the PCB board, while the protective layer effectively protects the PCB board surface from ion beam etching or damage during PCB board cutting, ensuring the accuracy of experimental observation and measurement.

[0035] In this specific implementation, a focusing ion beam scanning electron microscope (FIB-SEM) can be used to deposit a positioning layer and a protective layer on the target anomalous region. FIB-SEM is a system combining a focusing ion beam (FIB) and a scanning electron microscope (SEM). By controlling the FIB-SEM, the focusing electron beam can be controlled according to preset first deposition parameters to deposit a positioning layer on the target anomalous region according to the cutting positioning marks. Based on the positioning layer, the focusing ion beam is controlled according to preset second deposition parameters to deposit a protective layer on the target anomalous region according to the cutting positioning marks. The first and second deposition parameters include deposition voltage and deposition beam current. The magnitudes of the deposition voltage and deposition beam current are set according to actual needs and are not limited in this embodiment.

[0036] S104: Under the protection of the protective layer, the focused ion beam is controlled according to the preset cutting parameters to cut the target abnormal area and obtain a cross-sectional sample.

[0037] In this specific implementation, a focused ion beam scanning electron microscope (FIB-SEM) can be used to control the focused ion beam to cut the target abnormal region according to preset cutting parameters, thereby obtaining a cross-sectional sample.

[0038] For example, cutting parameters are set in the operating system of a focused ion beam scanning electron microscope, the target anomalous area is focused on the display of the focused ion beam scanning electron microscope, and the cutting pattern corresponding to the target anomalous area is drawn. Then, a cross-sectional sample is cut on the PCB board according to the cutting parameters and the cutting pattern.

[0039] S105: Perform cross-sectional analysis on the cross-sectional sample to determine the cause of PCB board failure.

[0040] It should be understood that when a finished PCB board fails, it is necessary to conduct a failure analysis on the PCB board in a timely manner to find out the cause of the failure. Only in this way can the processing parameters of the PCB processing equipment be adjusted in a timely manner based on the cause of the failure, so as to avoid a large number of failed finished PCB boards in the subsequent production process, resulting in material waste.

[0041] In this specific implementation, cross-sectional analysis of the cross-sectional sample includes, but is not limited to: observing the laminated structure of the cross-sectional sample using an optical microscope (metallurgical microscope) to determine whether the cross-sectional sample has glass fiber / resin distribution or delamination defects; performing intermetallic compound (IMC) analysis on the solder joints of the cross-sectional sample using a scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) to determine whether intermetallic compounds, such as Cu6Sn (copper-6-tin intermetallic compound), are present; measuring the copper layer thickness of the cross-sectional sample using a laser confocal microscope to determine whether there are issues with the copper thickness of the hole walls or the uniformity of the circuit; and testing the solder resist adhesion of the cross-sectional sample using a nanoindenter to assess the interface peel strength of the cross-sectional sample. It should be understood that the above methods for cross-sectional analysis of the cross-sectional sample are only some of the methods, and the specific methods for cross-sectional analysis of the cross-sectional sample in this embodiment are not limited.

[0042] In summary, this invention provides a cross-sectional analysis method for PCB positioning and cutting. The method involves observing a failed PCB board using an optical microscope to identify the target abnormal region. Under the optical microscope, nanomechanical needles are used to mark the target abnormal region on the PCB board with corresponding cutting positioning marks. A focused electron beam is controlled according to preset first deposition parameters to deposit a positioning layer on the target abnormal region according to the cutting positioning marks. Based on this positioning layer, a focused ion beam is controlled according to preset second deposition parameters to deposit a protective layer on the positioning layer. Under the protection of the protective layer, the target abnormal region is cut using a focused ion beam controlled according to preset cutting parameters to obtain a cross-sectional sample. Cross-sectional analysis is performed on the cross-sectional sample to determine the cause of PCB board failure. As can be seen, this invention locates the target abnormal region on the PCB board using an optical microscope. The optical microscope can observe not only the surface morphology of the sample but also the morphology within a certain range below the surface. Furthermore, the optical microscope is highly sensitive and accurate in color recognition. Compared to locating the target abnormal region on the PCB board using a scanning electron microscope, this method can more effectively locate the target abnormal region, thus reducing the difficulty of locating the target abnormal region. In addition, by depositing a positioning layer and a protective layer in the target abnormal area, this invention can improve the cutting accuracy of cross-sectional samples while avoiding physical and chemical damage to the cross-sectional samples during the cutting process, thereby improving the accuracy of failure analysis of PCB boards.

[0043] In one embodiment, such as Figure 2 As shown, step S101 in this embodiment can be implemented through the following steps: S201: According to the preset optical magnification, observe the PCB board for any candidate abnormal areas under bright field light source and dark field light source respectively using an optical microscope.

[0044] S201: If no candidate abnormal area is observed on the PCB board under bright field light source, and a candidate abnormal area is observed on the PCB board under dark field light source, the candidate abnormal area is determined as the target abnormal area.

[0045] The preset optical magnification is greater than or equal to 10KX.

[0046] It is important to note that bright-field light sources typically illuminate the PCB surface perpendicularly. Under a bright-field light source, an optical microscope can usually only observe obvious unevenness, scratches, or contaminants—potential anomalies. Therefore, the cause of failure can usually be directly observed within these potential anomaly areas under an optical microscope, and cross-sectional analysis of the potential anomaly areas is unnecessary. Dark-field light sources, on the other hand, are typically diffused light. Under a dark-field light source, minute unevenness, scratches, contaminants, or other surface defects can be observed. Therefore, the cause of failure cannot usually be observed under an optical microscope within these potential anomaly areas, and cross-sectional analysis of these potential anomaly areas is required.

[0047] In summary, this embodiment uses an optical microscope to identify abnormal areas on the PCB board under both bright and dark light sources, which allows for a more comprehensive inspection of the PCB board's surface condition and improves the accuracy of PCB board failure analysis.

[0048] In one embodiment, such as Figure 3 As shown: Step S103 in this embodiment can be implemented through the following steps: S301: Deposit metal on the PCB board surface by sputtering for seconds, and test the conductivity of the target abnormal area by grounding with a multimeter.

[0049] The deposited metal includes, but is not limited to, any one or more of platinum (Pt), carbon (C), and gold (Au).

[0050] In this specific implementation, metal can be deposited on the PCB board surface by high-vacuum magnetron sputtering technology in seconds, and the target abnormal area can be tested by grounding with a multimeter. When the resistance value displayed by the multimeter is less than the preset resistance threshold (such as 10Ω), it is determined that the target abnormal area is conductive.

[0051] S302: When it is determined that the target anomalous area is conductive, the focused electron beam is controlled according to the first deposition parameters, and a positioning layer is deposited in the target anomalous area according to the cutting positioning mark.

[0052] S303: Tilt the PCB board to the preset target angle.

[0053] S304: Based on the positioning layer, the focused ion beam is controlled according to the second deposition parameters to deposit a protective layer in the target abnormal area according to the cutting positioning mark.

[0054] Understandably, the main purpose of tilting the PCB board in this embodiment is to optimize the uniformity of the protective layer, avoid process defects, and improve production efficiency. The target angle can be from 15° to 45°, and this embodiment does not impose a specific limitation.

[0055] Specifically, in this embodiment, the first deposition parameters include a first deposition voltage and a first deposition current, and the second deposition parameters include a second deposition voltage and a second deposition current. The first deposition voltage is less than the second deposition voltage, and the first deposition current is greater than the second deposition current. For example, the first deposition voltage can be 5kV, the first deposition current can be 5.5nA, the second deposition voltage can be 30kV, and the second deposition current can be 0.23nA. It should be noted that the values ​​of the first deposition voltage, the first deposition current, the second deposition voltage, and the second deposition current are only illustrative examples, and the specific values ​​of the first deposition voltage, the first deposition current, the second deposition voltage, and the second deposition current are not limited in this embodiment.

[0056] It is important to note that when depositing the positioning layer according to the first deposition parameters, a higher first deposition voltage generates a lower energy density, which helps to form a thinner positioning layer in the target anomaly area, avoiding over-deposition that could lead to inaccurate positioning. A higher beam current ensures that the positioning layer deposition is completed in a shorter time, improving production efficiency and also helping to maintain the uniformity of the positioning layer. When depositing the positioning layer according to the second deposition parameters, a higher second deposition voltage generates a higher energy density, which helps to form a thicker protective layer in the target anomaly area, improving the density and wear resistance of the protective layer. A lower second deposition beam current ensures a more stable deposition process, avoiding excessive heat that could cause PCB board deformation or damage. Simultaneously, a lower beam current also helps to control the thickness and uniformity of the deposited layer.

[0057] In one embodiment, the cutting parameters include a first cutting parameter and a second cutting parameter. Based on this, step S104 in this embodiment can be implemented through the following steps: Figure 4 As shown: S401: Control the focused ion beam to perform coarse cutting on the target abnormal region according to the first cutting parameters.

[0058] S402: After coarse cutting is completed, the focused ion beam is controlled according to the second cutting parameters to perform fine cutting on the target abnormal area to obtain a cross-sectional sample.

[0059] The first cutting parameters include a first cutting voltage and a first cutting beam current, and the second cutting parameters include a second cutting voltage and a second cutting beam current. The first cutting voltage may be equal to or not equal to the second cutting voltage, and the first cutting beam current is greater than the second cutting beam current. For example, the first cutting voltage can be 30kV, the first cutting beam current can be any one of 9.3nA, 21nA, or 47nA, the second cutting voltage can be 30kV, and the second cutting beam current can be 2.5nA. It should be noted that the values ​​of the first cutting voltage, first cutting beam current, second cutting voltage, and second cutting beam current mentioned above are only illustrative examples, and the specific values ​​of the first cutting voltage, first cutting beam current, second cutting voltage, and second cutting beam current are not limited in this embodiment.

[0060] It should be noted that in this embodiment, both the first and second cutting voltages are relatively large, which can ensure the cutting effect of the focused ion beam on the target abnormal area on the PCB board. In the coarse cutting process, a larger first cutting beam current is used to improve the cutting efficiency of the target abnormal area. In the fine cutting process, a smaller second cutting beam current is used to ensure the cutting accuracy of the target area. Thus, by using coarse and fine cutting, cutting efficiency can be improved while ensuring cutting accuracy.

[0061] In one embodiment, the image resolution of the optical microscope in this embodiment is greater than 200 nm.

[0062] Understandably, optical microscopes with higher image resolution can capture finer details, allowing for better observation of target abnormal areas on PCBs, thereby improving the accuracy of locating target abnormal areas on PCBs.

[0063] In one embodiment, the cutting positioning marks include a start point, an end point, a left positioning point, and a right positioning point.

[0064] In other words, this embodiment uses a four-point positioning method to mark the cutting positioning marks corresponding to the target abnormal area on the PCB board. The cutting positioning marks made using the four-point positioning method facilitate quick and accurate location of the target abnormal area, improving the efficiency of cross-sectional analysis.

[0065] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A cross-sectional analysis method for PCB positioning and cutting, characterized in that, include: The failed PCB board was observed using an optical microscope to determine the target abnormal area of ​​the PCB board. Under the observation of the optical microscope, cutting and positioning marks corresponding to the target abnormal area are marked on the PCB board using nanomechanical needles; The focused electron beam is controlled according to the preset first deposition parameters to deposit a positioning layer in the target abnormal area according to the cutting positioning mark. Based on the positioning layer, the focused ion beam is controlled according to the preset second deposition parameters to deposit a protective layer on the positioning layer. Under the protection of the protective layer, the focused ion beam is controlled according to preset cutting parameters to cut the target abnormal region and obtain a cross-sectional sample; Cross-sectional analysis was performed on the cross-sectional sample to determine the cause of failure of the PCB board; The step of observing the failed PCB board using an optical microscope to determine the target abnormal area of ​​the PCB board includes: According to the preset optical magnification, the optical microscope is used to observe whether there are any candidate abnormal areas on the PCB board under bright field light source or dark field light source respectively; If, under the bright field light source, the PCB board is not observed to have the candidate abnormal area, and under the dark field light source, the PCB board is observed to have the candidate abnormal area, then the candidate abnormal area is determined to be the target abnormal area. The process of controlling a focused electron beam according to preset first deposition parameters to deposit a positioning layer in the target abnormal region according to the cutting positioning mark, and then, based on the positioning layer, controlling a focused ion beam according to preset second deposition parameters to deposit a protective layer on the positioning layer, includes: Metal is sputtered and deposited in the target abnormal area, and the conductivity of the target abnormal area is tested by grounding with a multimeter. If the target anomalous region is determined to be conductive, the focused electron beam is controlled according to the first deposition parameters, and the deposited metal is deposited in the target anomalous region according to the cutting and positioning marks to obtain the positioning layer; Tilt the PCB board to a preset target angle; Based on the positioning layer, the protective layer is deposited on the positioning layer by controlling the focused ion beam according to the second deposition parameters; The first deposition parameters include a first deposition voltage and a first deposition current, and the second deposition parameters include a second deposition voltage and a second deposition current, wherein the first deposition voltage is less than the second deposition voltage, and the first deposition current is greater than the second deposition current; The cutting parameters include a first cutting parameter and a second cutting parameter; Under the protection of the protective layer, the focused ion beam is controlled according to preset cutting parameters to cut the target abnormal region to obtain a cross-sectional sample, including: The focused ion beam is controlled to coarsely cut the target abnormal region according to the first cutting parameters; After the coarse cutting is completed, the focused ion beam is controlled according to the second cutting parameters to perform fine cutting on the target abnormal region to obtain the cross-sectional sample.

2. The PCB positioning and cutting cross-sectional analysis method according to claim 1, characterized in that, The optical magnification is greater than or equal to 10KX.

3. The PCB positioning and cutting cross-sectional analysis method according to claim 1, characterized in that, The deposited metal includes any one or more of platinum (Pt), carbon (C), and gold (Au).

4. The PCB positioning and cutting cross-sectional analysis method according to claim 1, characterized in that, The first cutting parameters include a first cutting voltage and a first cutting beam current, and the second cutting parameters include a second cutting voltage and a second cutting beam current. The first cutting voltage may be equal to or not equal to the second cutting voltage, and the first cutting beam current is greater than the second cutting beam current.

5. The PCB positioning and cutting cross-sectional analysis method according to claim 1, characterized in that, The optical microscope has an image resolution greater than 200 nm.

6. The PCB positioning and cutting cross-sectional analysis method according to claim 1, characterized in that, The cutting positioning marks include a start point, an end point, a left positioning point, and a right positioning point.

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