Cross section analysis method for PCB positioning cutting

Abstract

The invention relates to the technical field of section analysis of printed circuit boards, in particular to a section analysis method for PCB positioning cutting, a target abnormal area is positioned on a PCB through an optical microscope, the optical microscope not only can observe the morphology of the surface layer of a sample, but also can observe the morphology within a certain range below the surface layer, and the accuracy of section analysis is improved. And meanwhile, the optical microscope is very sensitive and accurate in color identification, so that compared with the prior art in which the target abnormal area is positioned on the PCB through a scanning electron microscope, the target abnormal area can be more effectively positioned on the PCB, and the purpose of reducing the positioning difficulty of the target abnormal area is achieved. Besides, the positioning layer and the protection layer are deposited in the target abnormal area, so that the cross section sample can be prevented from being physically and chemically damaged in the cutting process on the basis of improving the cutting precision of the cross section sample, and the failure analysis precision of the PCB is improved.

Description

Technical Field

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

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

[0003] Currently, the common failure analysis method is usually to obtain the surface morphology and composition information of the failed packaging substrate through a scanning electron microscope (SEM). Based on the surface morphology and composition information, the anomaly is located on the packaging substrate. Then, a focused ion beam is used to cut a cross-sectional sample from the anomaly. Failure analysis is performed on the cross-sectional sample to determine the failure cause of the failed packaging substrate.

[0004] However, the electron beam of a scanning electron microscope has extremely low penetration power into the packaging substrate, and the scanning electron microscope can only display monochrome (gray) images, resulting in poor imaging effects of the scanning electron microscope. The gray image can only show the surface or sub-surface details of the packaging substrate. When there are non-surface abnormal areas (such as embedded foreign matter) or shallow surface color abnormal areas (such as ink color) on the packaging substrate, the target abnormal area cannot be effectively observed, and thus the abnormal area cannot be accurately located on the failed packaging substrate.

[0005] Therefore, the existing packaging substrate cross-section analysis method has the problem of difficulty in locating abnormal areas. Summary of the Invention

[0006] An embodiment of the present invention provides a cross-sectional analysis method for PCB positioning and cutting, so as to solve the problem of difficulty in locating target abnormal areas in existing package substrate cross-sectional analysis methods.

[0007] A cross-sectional analysis method for PCB positioning cutting, comprising: Observe the failed PCB board through an optical microscope to determine the target abnormal area of the PCB board; Under the observation of the optical microscope, marking a cutting positioning mark corresponding to the target abnormal area on the PCB board using a nanomechanical needle; Controlling the focused electron beam according to a preset first deposition parameter to deposit a positioning layer on the target abnormal area according to the cutting positioning mark, and controlling the focused ion beam according to a preset second deposition parameter on the basis of the positioning layer to deposit a protective layer on the positioning layer; Under the protection of the protective layer, the focused ion beam is controlled to cut the target abnormal area according to preset cutting parameters to obtain a cross-sectional sample; Perform a cross-sectional analysis on the cross-sectional sample to obtain a failure cause of the PCB board.

[0008] Optionally, the cross-sectional analysis method for PCB positioning cutting includes observing the failed PCB board through an optical microscope to determine the target abnormal area of the PCB board, including: Observe the PCB board for abnormal areas using the optical microscope under a bright field light source or a dark field light source according to a preset optical magnification; If, under the bright field light source, it is observed that the candidate abnormal area does not exist on the PCB board, and, under the dark field light source, it is observed that the candidate abnormal area exists on the PCB board, the candidate abnormal area is determined to be the target abnormal area.

[0009] In the above cross-sectional analysis method for PCB positioning and cutting, optionally, the optical magnification is greater than or equal to 10KX.

[0010] The cross-sectional analysis method for PCB positioning cutting may optionally include controlling a focused electron beam according to a preset first deposition parameter, depositing a positioning layer in the target abnormal area according to the cutting positioning mark, and controlling a focused ion beam according to a preset second deposition parameter on the basis of the positioning layer to deposit a protective layer on the positioning layer, including: sputter depositing metal in the target abnormal area in seconds, and testing whether the target abnormal area has conductivity by grounding with a multimeter; When it is determined that the target abnormal area is conductive, controlling the focused electron beam according to the first deposition parameter, and depositing the deposition metal in the target abnormal area according to the cutting positioning mark to obtain the positioning layer; Tilt the PCB to a preset target angle; On the basis of the positioning layer, the focused ion beam is controlled according to the second deposition parameter to deposit the protective layer on the positioning layer.

[0011] In the cross-sectional analysis method for PCB positioning cutting, optionally, the deposited metal includes any one or more of platinum Pt, carbon C, and gold Au.

[0012] In the above-mentioned cross-sectional analysis method for PCB positioning cutting, optionally, the first deposition parameters include a first deposition voltage and a first deposition beam current, the second deposition parameters include a second deposition voltage and a second deposition beam current, 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] In the cross-section analysis method for PCB positioning cutting, optionally, the cutting parameters include a first cutting parameter and a second cutting parameter; The method of controlling the focused ion beam to cut the target abnormal area according to preset cutting parameters under the protection of the protective layer to obtain a cross-sectional sample includes: Controlling the focused ion beam to perform rough cutting on the target abnormal area according to the first cutting parameter; After the rough cutting is completed, the focused ion beam is controlled according to the second cutting parameter to perform fine cutting on the target abnormal area to obtain the cross-sectional sample.

[0014] In the above-mentioned cross-sectional analysis method for PCB positioning cutting, optionally, the first cutting parameters include a first cutting voltage and a first cutting beam current, the second cutting parameters include a second cutting voltage and a second cutting beam current, the first cutting voltage is 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] In the above cross-sectional analysis method for PCB positioning cutting, optionally, the image resolution of the optical microscope is greater than 200 nm.

[0016] In the cross-section analysis method for PCB positioning cutting, optionally, the cutting positioning mark includes a starting point, an end point, a left positioning point, and a right positioning point.

[0017] The present invention provides a cross-sectional analysis method for PCB positioning cutting, wherein a failed PCB board is observed through an optical microscope to determine a target abnormal area of the PCB board; under the observation of the optical microscope, a cutting positioning mark corresponding to the target abnormal area is marked on the PCB board by a nanomechanical needle; a focused electron beam is controlled according to a preset first deposition parameter to deposit a positioning layer on the target abnormal area according to the cutting positioning mark, and based on the positioning layer, a focused ion beam is controlled according to a preset second deposition parameter to deposit a protective layer on the positioning layer; under the protection of the protective layer, the focused ion beam is controlled according to the preset cutting parameter to cut the target abnormal area to obtain a cross-sectional sample; a cross-sectional analysis is performed on the cross-sectional sample to obtain the failure cause of the PCB board. It can be seen that the present invention locates the target abnormal area on the PCB board through an optical microscope. The optical microscope can not only observe the surface morphology of the sample, but also the morphology within a certain range below the surface. At the same time, the optical microscope is very sensitive and accurate in color recognition. Compared with locating the target abnormal area on the PCB board through a scanning electron microscope, the target abnormal area can be located on the PCB board more effectively, thereby achieving the purpose of reducing the difficulty of locating the target abnormal area. In addition, by depositing a positioning layer and a protective layer in the target abnormal area, the present invention can improve the cutting accuracy of the cross-sectional sample and avoid physical and chemical damage to the cross-sectional sample during the cutting process, thereby improving the accuracy of failure analysis of the PCB board. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 This is a flow chart for implementing a cross-section analysis method for PCB positioning and cutting in one embodiment of the present invention; Figure 2 This is a partial implementation flow chart of a cross-section analysis method for PCB positioning and cutting in one embodiment of the present invention; Figure 3 This is a partial implementation flow chart of a cross-section analysis method for PCB positioning and cutting in one embodiment of the present invention; Figure 4 This is a partial implementation flow chart of a cross-section analysis method for PCB positioning and cutting in one embodiment of the present invention. DETAILED DESCRIPTION

[0020] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

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

[0022] It will also be understood that the term "and / or" used in the present description and appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

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

[0024] In addition, in the description of the present specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0025] References to "one embodiment" or "some embodiments" in the present specification mean that a particular feature, structure, or characteristic described in connection with that embodiment is included in one or more embodiments of the present invention. Thus, phrases such as "in one embodiment," "in some embodiments," "in other embodiments," and "in yet other embodiments" appearing in various places in this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically stated. The terms "including," "comprising," "having," and variations thereof mean "including but not limited to," unless otherwise specifically stated.

[0026] The present invention provides a cross-sectional analysis method for PCB positioning cutting, wherein a failed PCB board is observed through an optical microscope to determine a target abnormal area of the PCB board; under the observation of the optical microscope, a cutting positioning mark corresponding to the target abnormal area is marked on the PCB board by a nanomechanical needle; a focused electron beam is controlled according to a preset first deposition parameter to deposit a positioning layer on the target abnormal area according to the cutting positioning mark, and based on the positioning layer, a focused ion beam is controlled according to a preset second deposition parameter to deposit a protective layer on the positioning layer; under the protection of the protective layer, the focused ion beam is controlled according to the preset cutting parameter to cut the target abnormal area to obtain a cross-sectional sample; a cross-sectional analysis is performed on the cross-sectional sample to obtain the failure cause of the PCB board. It can be seen that the present invention locates the target abnormal area on the PCB board through an optical microscope. The optical microscope can not only observe the surface morphology of the sample, but also the morphology within a certain range below the surface. At the same time, the optical microscope is very sensitive and accurate in color recognition. Compared with locating the target abnormal area on the PCB board through a scanning electron microscope, the target abnormal area can be located on the PCB board more effectively, thereby achieving the purpose of reducing the difficulty of locating the target abnormal area. Furthermore, by depositing a positioning layer and a protective layer in the target abnormal area, the present invention can improve the cutting accuracy of cross-sectional samples while preventing physical and chemical damage to the cross-sectional samples during the cutting process, thereby improving the accuracy of PCB failure analysis. This will be described below using specific embodiments.

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

[0028] The image resolution of the optical microscope in this embodiment is greater than 200 nm.

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

[0030] In a specific implementation, this embodiment uses an optical microscope to observe a PCB to identify target abnormal areas. These target abnormal areas include, but are not limited to, non-surface target abnormal areas (e.g., embedded foreign matter) or superficial color variations (e.g., ink discoloration). When embedded foreign matter or ink discoloration is observed on a failed PCB through an optical microscope, the corresponding area is identified as the target abnormal area.

[0031] S102: Under the observation of an optical microscope, a cutting positioning mark corresponding to the target abnormal area is marked on the PCB board using a nanomechanical needle.

[0032] In a specific implementation, in this embodiment, a microscopic marking operating platform can be used to mark the cutting positioning mark corresponding to the target abnormal area on the PCB board. The microscopic marking operating platform includes an optical microscope, a mechanical nanoneedle, 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 nanoneedle is used to mark the cutting positioning mark corresponding to the target abnormal area on the PCB board. The mechanical nanoneedle is controlled by a mechanical nanoneedle operating system, which includes an operating software control platform, a three-axis drive robotic arm, a real-time display electronic screen, and a nanoneedle tip (with an accuracy of 1±0.1μm). The display electronic screen is used to display the imaging screen of the optical microscope.

[0033] S103: Control the focused electron beam according to the preset first deposition parameter, 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 parameter, and deposit a protective layer on the positioning layer.

[0034] Among them, the positioning layer is used to provide a position reference for the subsequent deposition of the protective layer and the cutting of the PCB board. The protective layer is used to effectively protect the surface of the PCB board from being etched or damaged by the ion beam when cutting the PCB board, ensuring the accuracy of experimental observation and measurement.

[0035] In a specific implementation, in this embodiment, a focused ion beam scanning electron microscope (FIB-SEM) can be used to deposit a positioning layer and a protective layer in the target abnormal area. The FIB-SEM is a system that combines a focused ion beam (FIB) and a scanning electron microscope (SEM). By controlling the FIB-SEM, the focused electron beam can be controlled according to a preset first deposition parameter 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 a preset second deposition parameter to deposit a protective layer in the target abnormal area according to the cutting positioning mark. The first deposition parameter and the second deposition parameter include a deposition voltage and a deposition beam current. The deposition voltage and the 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 to cut the target abnormal area according to the preset cutting parameters to obtain a cross-sectional sample.

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

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

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

[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 identify the cause of the failure. Only then can the processing parameters of the PCB processing equipment be adjusted in a timely manner based on the failure cause, thereby avoiding a large number of failed finished PCB boards in the subsequent production process, resulting in material waste.

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

[0042] In summary, the present invention provides a cross-sectional analysis method for PCB positioning cutting, wherein a failed PCB board is observed through an optical microscope to determine a target abnormal area of the PCB board; under the observation of the optical microscope, a cutting positioning mark corresponding to the target abnormal area is marked on the PCB board by a nanomechanical needle; a focused electron beam is controlled according to a preset first deposition parameter, a positioning layer is deposited on the target abnormal area according to the cutting positioning mark, and on the basis of the positioning layer, a focused ion beam is controlled according to a preset second deposition parameter to deposit a protective layer on the positioning layer; under the protection of the protective layer, the focused ion beam is controlled according to the preset cutting parameter to cut the target abnormal area to obtain a cross-sectional sample; a cross-sectional analysis is performed on the cross-sectional sample to obtain the failure cause of the PCB board. It can be seen that the present invention locates the target abnormal area on the PCB board through an optical microscope. The optical microscope can not only observe the surface morphology of the sample, but also observe the morphology within a certain range below the surface. At the same time, the optical microscope is very sensitive and accurate in color recognition. Compared with locating the target abnormal area on the PCB board through a scanning electron microscope, the target abnormal area can be located more effectively on the PCB board, thereby achieving the purpose of reducing the difficulty of locating the target abnormal area. In addition, by depositing a positioning layer and a protective layer in the target abnormal area, the present invention can improve the cutting accuracy of the cross-sectional sample and avoid physical and chemical damage to the cross-sectional sample during the cutting process, thereby improving the accuracy of failure analysis of the PCB board.

[0043] In one embodiment, Figure 2 As shown, step S101 in this embodiment can be implemented by the following steps: S201: Observe the PCB board using an optical microscope under a bright field light source and a dark field light source according to a preset optical magnification to determine whether there is a candidate abnormal area.

[0044] S201: If it is observed under a bright field light source that no candidate abnormal region exists on the PCB board, and under a dark field light source that a candidate abnormal region exists on the PCB board, the candidate abnormal region is determined to be a target abnormal region.

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

[0046] It should be noted that brightfield light sources typically illuminate the PCB surface perpendicularly. Under brightfield light, an optical microscope can typically only observe obvious abnormal areas such as bumps, scratches, or contaminants. Therefore, when observing an abnormal area under brightfield light, the cause of failure can usually be directly observed in the abnormal area. If the cause of failure has already been observed under an optical microscope, there is no need to perform a cross-sectional analysis of the abnormal area. Darkfield light sources typically use scattered light. Under darkfield light, an optical microscope can observe tiny bumps, scratches, contaminants, or other surface defects. Therefore, when observing an abnormal area under darkfield light, the cause of failure cannot usually be observed under an optical microscope. Therefore, a cross-sectional analysis of the abnormal area is required.

[0047] In summary, in this embodiment, by identifying abnormal areas on a PCB using an optical microscope under brightfield and darkfield light sources, the surface condition of the PCB can be more comprehensively detected, thereby improving the accuracy of PCB failure analysis.

[0048] In one embodiment, Figure 3 As shown: Step S103 in this embodiment can be implemented by the following steps: S301: Metal is deposited on the PCB surface by sputtering in seconds, and a multimeter is used to ground the target abnormal area to test whether it is conductive.

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

[0050] In a specific implementation, in this embodiment, high vacuum magnetron sputtering technology can be used to deposit metal on the surface of the PCB board in seconds, and the target abnormal area can be tested by grounding a multimeter. When the resistance value displayed by the multimeter is less than a 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 abnormal region is conductive, the focused electron beam is controlled according to the first deposition parameter, and a positioning layer is deposited in the target abnormal region according to the cutting positioning mark.

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

[0053] S304: Based on the positioning layer, controlling the focused ion beam according to the second deposition parameter, and depositing a protective layer in the target abnormal area according to the cutting positioning mark.

[0054] It is understood that the main purpose of tilting the PCB in this embodiment is to optimize the uniformity of the protective layer, avoid process defects, and improve production efficiency. The target angle can be 15° to 45°, which is not specifically limited in this embodiment.

[0055] Specifically, in this embodiment, 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. 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. For example, the first deposition voltage may be 5 kV, the first deposition beam current may be 5.5 nA, the second deposition voltage may be 30 kV, and the second deposition beam current may be 0.23 nA. It should be noted that the above values of the first deposition voltage, the first deposition beam current, the second deposition voltage, and the second deposition beam current are merely exemplary, and the specific values of the first deposition voltage, the first deposition beam current, the second deposition voltage, and the second deposition beam current are not limited in this embodiment.

[0056] It should be noted that when depositing the positioning layer according to the first deposition parameters, a larger first deposition voltage can produce a lower energy density, which helps to form a thinner positioning layer in the target abnormal area and avoid excessive deposition that leads to inaccurate positioning. A larger beam current can ensure that the deposition of the positioning layer 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 larger second deposition voltage can produce a higher energy density, which helps to form a thicker protective layer in the target abnormal area, improving the density and wear resistance of the protective layer, while a smaller second deposition beam current can ensure a more stable deposition process and avoid excessive heat generation that may cause deformation or damage to the PCB board. At the same time, a smaller 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. On this basis, step S104 in this embodiment can be implemented by the following steps: Figure 4 As shown: S401: Controlling a focused ion beam to perform rough cutting on a target abnormal area according to a first cutting parameter.

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

[0059] Among them, the first cutting parameter includes a first cutting voltage and a first cutting beam current, the second cutting parameter includes a second cutting voltage and a second cutting beam current, the first cutting voltage is 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 above-mentioned values of the first cutting voltage, the first cutting beam current, the second cutting voltage and the second cutting beam current are only exemplary descriptions, and the specific values of the first cutting voltage, the first cutting beam current, the second cutting voltage and the second cutting beam current are not limited in this embodiment.

[0060] It should be noted that, in this embodiment, the first cutting voltage and the second cutting voltage both use relatively large voltages, which can ensure the cutting effect of the focused ion beam on the target abnormal area on the PCB board. A larger first cutting beam is used during the rough cutting process to improve the cutting efficiency of the target abnormal area. In the fine cutting process, a smaller second cutting beam is used to ensure the cutting accuracy of the target area. Therefore, through rough cutting and fine cutting, the cutting efficiency can be improved while ensuring the cutting accuracy.

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

[0062] It is understandable that an optical microscope with higher image resolution can capture smaller details and better observe the target abnormal area on the PCB board, thereby improving the accuracy of locating the target abnormal area on the PCB board.

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

[0064] That is, in this embodiment, the cutting positioning mark corresponding to the target abnormal area is marked on the PCB board using the four-point positioning method. The cutting positioning mark marked by the four-point positioning method is conducive to quickly and accurately locating the position of the target abnormal area, thereby improving the efficiency of cross-sectional analysis.

[0065] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the scope of protection of the present invention.

Claims

1. A cross-sectional analysis method for PCB positioning cutting, characterized in that: include: Observe the failed PCB board through an optical microscope to determine the target abnormal area of the PCB board; Under the observation of the optical microscope, marking a cutting positioning mark corresponding to the target abnormal area on the PCB board using a nanomechanical needle; Controlling the focused electron beam according to a preset first deposition parameter to deposit a positioning layer on the target abnormal area according to the cutting positioning mark, and controlling the focused ion beam according to a preset second deposition parameter on the basis of the positioning layer to deposit a protective layer on the positioning layer; Under the protection of the protective layer, the focused ion beam is controlled to cut the target abnormal area according to preset cutting parameters to obtain a cross-sectional sample; Perform a cross-sectional analysis on the cross-sectional sample to obtain a failure cause of the PCB board.

2. The cross-sectional analysis method for PCB positioning cutting according to claim 1, characterized in that: The step of observing the failed PCB board through an optical microscope to determine a target abnormal area of the PCB board includes: Observe the PCB board for abnormal areas using the optical microscope under a bright field light source or a dark field light source according to a preset optical magnification; If, under the bright field light source, it is observed that the candidate abnormal area does not exist on the PCB board, and, under the dark field light source, it is observed that the candidate abnormal area exists on the PCB board, the candidate abnormal area is determined to be the target abnormal area.

3. The cross-section analysis method for PCB positioning cutting according to claim 2, characterized in that: The optical magnification is greater than or equal to 10KX.

4. The cross-section analysis method for PCB positioning cutting according to claim 1, characterized in that: The method controls the focused electron beam according to the preset first deposition parameter, deposits a positioning layer in the target abnormal area according to the cutting positioning mark, and controls the focused ion beam according to the preset second deposition parameter on the basis of the positioning layer, deposits a protective layer on the positioning layer, including: sputter depositing metal in the target abnormal area in seconds, and testing whether the target abnormal area has conductivity by grounding with a multimeter; When it is determined that the target abnormal area is conductive, controlling the focused electron beam according to the first deposition parameter, and depositing the deposition metal in the target abnormal area according to the cutting positioning mark to obtain the positioning layer; Tilt the PCB to a preset target angle; On the basis of the positioning layer, the focused ion beam is controlled according to the second deposition parameter to deposit the protective layer on the positioning layer.

5. The cross-section analysis method for PCB positioning cutting according to claim 4, characterized in that: The deposited metal includes any one or more of platinum Pt, carbon C, and gold Au.

6. The cross-section analysis method for PCB positioning cutting according to claim 4, characterized in that: 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. 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.

7. The cross-section analysis method for PCB positioning cutting according to claim 1, characterized in that: The cutting parameters include a first cutting parameter and a second cutting parameter; The method of controlling the focused ion beam to cut the target abnormal area according to preset cutting parameters under the protection of the protective layer to obtain a cross-sectional sample includes: Controlling the focused ion beam to perform rough cutting on the target abnormal area according to the first cutting parameter; After the rough cutting is completed, the focused ion beam is controlled according to the second cutting parameter to perform fine cutting on the target abnormal area to obtain the cross-sectional sample.

8. The cross-section analysis method for PCB positioning cutting according to claim 7, 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 is equal to or not equal to the second cutting voltage, and the first cutting beam current is greater than the second cutting beam current.

9. The cross-section analysis method for PCB positioning cutting according to claim 1, characterized in that: The image resolution of the optical microscope is greater than 200 nm.

10. The cross-section analysis method for PCB positioning cutting according to claim 1, characterized in that: The cutting positioning mark includes a starting point, an end point, a left positioning point and a right positioning point.

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