MLCC chamfer quality evaluation method

Abstract

The invention discloses an MLCC chamfer quality evaluation method. The method comprises the following steps: firstly, providing an MLCC which is not chamfered and is chamfered in the same batch as a comparison sample group; then conducting the end face of the sample, and carrying out element quantitative analysis on a selected area of the end face under the same condition by utilizing a scanning electron microscope and an integrated X-ray energy disperse spectroscopy to obtain mass percentage data of metal elements of the inner electrode and representative elements of the selected ceramic layer; on the basis of the data, an average internal electrode exposure rate characterization value of each group of samples is calculated, and the value is a ratio or a proportional function of the mass percent of the metal element to the mass percent of the ceramic representative element; and finally, objectively evaluating the chamfering processing effect by comparing the difference between the two groups of characterization values. According to the invention, objectification and quantification of the MLCC chamfer evaluation process are realized, and the accuracy and repeatability of measurement and the adaptability to products of different specifications are remarkably improved.

Description

Technical Field

[0001] This application relates to the field of MLCC chamfer quality inspection technology, and in particular to a method for evaluating the chamfer quality of MLCCs. Background Technology

[0002] In the manufacturing process of multilayer ceramic capacitors (MLCCs), the green blank needs to be chamfered after sintering. The core purpose of this process is to grind the end face of the element to fully expose the internal metal electrodes, ensuring a reliable electrical connection between the inner and outer electrodes in subsequent processes. Therefore, the degree of exposure of the inner electrodes after chamfering, i.e., the inner electrode exposure rate, is a key indicator for evaluating the quality of the chamfering process and directly affecting the product yield.

[0003] Currently, the industry generally uses the traditional geometric measurement method to evaluate the internal electrode exposure rate: under a metallographic microscope, the operator observes the end face of the component with the naked eye, subjectively selects an electrode that is considered to be the worst exposed, manually measures the length of its exposed part, and calculates the ratio of this length to the total length of the electrode as the internal electrode exposure rate of the component.

[0004] However, this method, which relies on manual observation and geometric measurement, has inherent flaws and is difficult to meet the requirements of modern precision manufacturing for detection accuracy and efficiency. Summary of the Invention

[0005] Therefore, it is necessary to develop a chamfering quality assessment method for MLCCs to address the problem that traditional measurements of the internal electrode exposure rate after chamfering of MLCC products are not accurate enough.

[0006] The above-mentioned objective of this application is achieved through the following technical solution: This application provides a method for evaluating the chamfer quality of MLCCs, including the following steps: Sintered MLCCs without chamfering were provided as the first group of samples, and chamfered MLCCs from the same batch were provided as the second group of samples. Conductivity treatment was applied to the test surfaces of the first and second groups of samples, respectively. The two prepared samples were placed in a scanning electron microscope. Under the same test conditions, the selected areas of the test end face of the two samples were quantitatively analyzed by an integrated X-ray energy dispersive spectrometer to obtain the mass percentage data of the internal electrode metal elements and the selected ceramic layer representative elements of each sample. Based on the mass percentage data, the average internal electrode exposure rate characterization value of the two groups of samples is calculated. The internal electrode exposure rate characterization value is the ratio or proportional function of the mass percentage of the internal electrode metal element to the mass percentage of the ceramic layer representative element. The average internal electrode exposure rate of the first group of samples and the second group of samples were compared. The effect of the chamfering treatment was evaluated based on the change of the internal electrode exposure rate of the second group of samples relative to the first group of samples.

[0007] In one embodiment, when the MLCC is a Class 1 ceramic capacitor, its ceramic layer composition includes Ca, Sr, Zr, Ti, and O, and the ceramic layer representative element is selected from one or both of Ca and Sr. When the MLCC is a type 2 ceramic capacitor, its ceramic layer composition includes Ba, Ti, and O3, with Ba being the representative element of the ceramic layer.

[0008] In one embodiment, the MLCC is a Class 1 ceramic capacitor, and its ceramic layer composition includes Ca, Sr, Zr, Ti, and O. When the internal electrode is Ni, the internal electrode exposure rate characterization value = W Ni / (W Ni + W Ca + W Sr ); When the internal electrode is Cu, the internal electrode exposure rate characterization value = W Cu / (W Cu + W Ca + W Sr ); When the internal electrode is Ag-Pd, the internal electrode exposure rate characterization value = (W Ag + W Pd ) / (W Ag + W Pd + W Ca +W Sr ); Among them, W Ni W Cu W Ca W Sr W Ag W Pd These represent the mass percentages of Ni, Cu, Ca, Sr, Ag, and Pd elements, respectively.

[0009] In one embodiment, the MLCC is a type 2 ceramic capacitor, and its ceramic layer composition includes Ba, Ti, and O3. When the internal electrode is Ni, the internal electrode exposure rate characterization value = W Ni / (W Ni + W Ba ); When the internal electrode is Cu, the internal electrode exposure rate characterization value = W Cu / (W Cu + WBa ); When the internal electrode is Ag-Pd, the internal electrode exposure rate characterization value = (W Ag + W Pd ) / (W Ag + W Pd + W Ba ); Among them, W Ni W Cu W Ba W Ag W Pd These represent the mass percentages of Ni, Cu, Ba, Ag, and Pd elements, respectively.

[0010] In one embodiment, a condition setting step is included before the elemental quantitative analysis step: The scanning electron microscope is set to use a secondary electron signal, with an accelerating voltage of 10kV to 15kV; and the magnification is set according to the thickness of the ceramic dielectric layer of the MLCC.

[0011] In one embodiment, setting the observation magnification based on the ceramic dielectric layer thickness of the MLCC includes: When the thickness of the ceramic dielectric layer is not less than 10 μm, the observation magnification is set to 50x to 300x. When the thickness of the ceramic dielectric layer is greater than 3 μm and less than 10 μm, the observation magnification is set to 300x to 1000x. When the thickness of the ceramic dielectric layer is no greater than 3 μm, the observation magnification is set to 1000 to 2500 times.

[0012] In one embodiment, the selected region contains 10 to 30 layers of internal electrodes.

[0013] In one embodiment, the conductivity treatment is to perform gold or carbon spraying on the surface to be tested.

[0014] In one embodiment, the step of placing the two prepared samples in a scanning electron microscope specifically includes: After releasing the vacuum, open the sample chamber of the scanning electron microscope; Apply conductive adhesive to the sample stage, and place the sample to be tested with the test surface facing upwards and centered on the conductive adhesive. Adjust the distance between the sample and the microscope tube to the preset working distance, close the sample chamber door and evacuate.

[0015] In one embodiment, the step of performing elemental quantitative analysis using an integrated X-ray energy dispersive spectrometer includes: Select the region to be analyzed in the scanning electron microscope image; Execute the acquisition command and acquire new image in the X-ray energy dispersive spectrometer software to obtain the elemental spectrum of the region; Manually or automatically calibrate the element to be measured in the periodic table interface; Execute the quantitative analysis command to obtain a statistical table of the mass percentage of each calibrated element.

[0016] This application has at least the following beneficial effects: This application employs a combination of scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) to perform quantitative elemental analysis on the end faces of MLCCs before and after chamfering, fundamentally eliminating traditional manual visual observation and geometric measurement methods. This ensures the objectivity of the detection process and eliminates errors caused by subjective selection of the worst electrode and interpretation length. Secondly, leveraging the high resolution and large depth of field of SEM, and the precise quantitative capabilities of EDX, it can clearly characterize the component distribution at the micrometer scale, without being limited by product size or dielectric layer thickness, thus possessing universality. Furthermore, this application cleverly transforms the difficult-to-measure geometric exposure area into an easily measurable chemical composition ratio by calculating the mass percentage ratio of representative elements in the internal electrode metal and ceramic, creating a stable and reliable quantitative characterization index, providing accurate data support for evaluating the effect of the chamfering process. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application and to more completely understand this application and its beneficial effects, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram showing the shrinkage of the internal electrode of an MLCC after chamfering in one embodiment; Figure 2 A schematic diagram of the selected scheme for the internal electrode with the worst exposure rate in the prior art; Figure 3 This is a schematic diagram illustrating the steps of a chamfer quality assessment method for MLCCs in one embodiment; Figure 4 This is a three-dimensional view of a sintered MLCC sample in one embodiment; Figure 5 This is a schematic diagram of the chamfered front end face of an MLCC sample in one embodiment; Figure 6 This is a schematic diagram of the chamfered rear end face of an MLCC sample in one embodiment; Figure 7This is an EDX image of the chamfered front face region of an MLCC sample in one embodiment; Figure 8 This is an EDX image of the chamfered rear end face region of an MLCC sample in one embodiment; Figure 9 This is an EDX image of the chamfered front face region of an MLCC sample in one embodiment; Figure 10 This is an EDX image of the chamfered rear end face region of an MLCC sample in one embodiment; Figure 11 This is an EDX image of the chamfered front face region of an MLCC sample in one embodiment; Figure 12 This is an EDX image of the chamfered rear end face region of an MLCC sample in one embodiment. Detailed Implementation

[0019] To facilitate understanding of this application, the following detailed description is provided in conjunction with specific embodiments. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0021] In this application, "and / or" means any and all combinations of one or more of the related listed items. "At least one" means one or more, such as one, two, or more. "Multiple" or "several" means at least two, such as two, three, etc., and "multi-layered" means at least two layers, such as two, three, etc., unless otherwise expressly and specifically defined. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise expressly and specifically defined.

[0022] When a numerical range is disclosed in this application, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to an integer, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed in this application should be understood to include any and all subranges to which they are included.

[0023] Unless otherwise specified, all steps in this application may be performed sequentially or randomly. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0024] In this application, "above" or "below" includes the number itself. For example, "below 1" includes 1.

[0025] Unless otherwise specified, the temperature parameters in this application are permitted to be either constant-temperature treatment or variations within a certain temperature range. It should be understood that the constant-temperature treatment allows temperature fluctuations within the precision range of the instrument control, such as ±5℃, ±4℃, ±3℃, ±2℃, or ±1℃.

[0026] In this application, room temperature refers to indoor temperature, normal temperature, or general temperature. Generally, room temperature can be any of the following temperature ranges: 23℃±2℃, 25℃±5℃, or 20℃±5℃.

[0027] like Figure 1 As shown, Figure 1 This is a cross-sectional view of the side of an MLCC. After sintering and chamfering, both the ceramic dielectric layer 10 and the metal internal electrode 20 inside the MLCC product shrink to varying degrees. The metal internal electrode 20 shrinks more significantly due to its different coefficient of thermal shrinkage compared to the ceramic dielectric layer 10. Excessive shrinkage of the internal electrode or insufficient chamfering and grinding can lead to inadequate exposure of the internal electrode on the end face, resulting in a loose connection during subsequent end-sealing processes, causing electrical performance failure or even product scrap. Therefore, one of the core purposes of the chamfering process is to fully expose the internal electrode on the end face of the MLCC product. Using the internal electrode exposure rate as a key quantitative indicator for evaluating chamfering quality is crucial for process control and quality improvement.

[0028] like Figure 2 As shown, Figure 2This is a schematic diagram of the cross-section of the end face after chamfering of an MLCC. Traditional methods for testing the exposure rate of internal electrodes rely on the operator's visual observation and experience under a metallographic microscope to select the electrode considered to have the worst exposure on the end face (e.g., 21 in the figure), and then estimate the exposure rate by measuring the ratio of its exposed length to the theoretical total length. This method has inherent drawbacks: First, human judgment is subject to subjective visual error, and different operators may select different worst electrodes; second, for larger products of 0402 and above, the field of view is limited at high magnification, making it impossible to observe the entire electrode and thus difficult to select accurately; third, for thin-layer, high-capacity products with a ceramic dielectric layer thickness of less than 3 micrometers, the limited depth of field and resolution of the optical microscope result in blurred images, making it impossible to clearly define the electrode boundaries. These factors collectively lead to low accuracy and poor repeatability in traditional measurement methods, failing to meet the needs of precise evaluation of chamfer quality in precision manufacturing.

[0029] The embodiments of this application aim to provide an objective, accurate, and universally applicable method for evaluating the chamfer quality of MLCCs, in order to overcome the limitations of the aforementioned traditional techniques.

[0030] Please see Figure 3 This is a flowchart illustrating a method for evaluating the chamfer quality of MLCCs according to an embodiment of this application. Figure 3 As shown, the chamfer quality assessment method for MLCCs includes the following steps: S100: Provide sintered MLCCs without chamfering as the first group of samples, and chamfered MLCCs from the same batch as the second group of samples; S200: Conduct the test end face of the first group of samples and the second group of samples respectively. S300: Place the two prepared samples in a scanning electron microscope. Under the same test conditions, use an integrated X-ray energy dispersive spectrometer to perform elemental quantitative analysis on the selected areas of the test end face of the two samples to obtain the mass percentage data of the internal electrode metal elements and the selected ceramic layer representative elements of each sample. S400: Based on the mass percentage data, calculate the average internal electrode exposure rate characterization value of the two groups of samples. The internal electrode exposure rate characterization value is the ratio or proportional function of the mass percentage of the internal electrode metal element to the mass percentage of the ceramic layer representative element. S500: Compare the average internal electrode exposure rate characterization values ​​of the first group of samples and the second group of samples. Based on the change in the internal electrode exposure rate characterization value of the second group of samples relative to the first group of samples, evaluate the effect of the chamfering treatment.

[0031] This application employs a combination of scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) to perform quantitative elemental analysis on the end faces of MLCCs before and after chamfering, fundamentally eliminating traditional manual visual observation and geometric measurement methods. This ensures the objectivity of the detection process and eliminates errors caused by subjective selection of the worst electrode and interpretation length. Secondly, leveraging the high resolution and large depth of field of SEM, and the precise quantitative capabilities of EDX, it can clearly characterize the component distribution at the micrometer scale, without being limited by product size or dielectric layer thickness, thus possessing universality. Furthermore, this application cleverly transforms the difficult-to-measure geometric exposure area into an easily measurable chemical composition ratio by calculating the mass percentage ratio of representative elements in the internal electrode metal and ceramic, creating a stable and reliable quantitative characterization index, providing accurate data support for evaluating the effect of the chamfering process.

[0032] The following is a detailed step-by-step description of the chamfer quality assessment method for MLCCs according to embodiments of this application.

[0033] S100: Provide sintered MLCCs without chamfering as the first group of samples, and chamfered MLCCs from the same batch as the second group of samples.

[0034] This application requires selecting two sets of samples from the same batch of sintered MLCC products: the first set of samples consists of products without chamfering treatment, and the second set consists of products after chamfering treatment. Selecting the same batch ensures that the two sets of samples are completely consistent in all key process parameters, such as ceramic powder, internal electrode slurry, sintering temperature profile, and holding time, thereby ensuring the highest degree of consistency between the two sets of samples in terms of material properties, shrinkage behavior, and initial microstructure.

[0035] This step aims to eliminate all interfering factors except for the chamfering process itself by establishing a control group and an experimental group within the same batch. This allows the observed differences to be primarily attributed to the chamfering process itself, providing a benchmark for subsequent performance evaluation.

[0036] S200: Conduct the test end face of the first group of samples and the second group of samples respectively.

[0037] like Figure 4 As shown, the MLCC sample has a major axis direction L, a minor axis direction W, and a stacking direction T. The major axis plane refers to any plane parallel to both the major axis direction L and the stacking direction T, also known as the L / T plane. The minor axis plane refers to any plane parallel to both the minor axis direction W and the stacking direction T, also known as the W / T plane.

[0038] The end face typically refers to the short axis end face of an MLCC (i.e., the W / T surface consisting of width W and thickness T), because the chamfering process is mainly applied to this surface to expose the internal electrodes. In this embodiment, the end faces of both sets of samples need to be prepared to form test surfaces suitable for observation.

[0039] In this embodiment, the surface to be tested needs to be conductively treated, for example, by sputtering gold or carbon to coat the surface of the MLCC sample end face with a thin and uniform conductive film. The function of this step is that the ceramic dielectric of MLCCs is essentially an insulator. During subsequent scanning electron microscopy observation, the incident electron beam accumulates charge on its surface, causing image distortion and drift (i.e., charging effect), making it impossible to obtain a clear morphology and severely interfering with component analysis. The conductive treatment provides a discharge path for these accumulated charges, thereby ensuring stable, clear images and reliable component signals, which is a technical prerequisite for the implementation of the method in this application.

[0040] S300: Place the two prepared samples in a scanning electron microscope. Under the same test conditions, use an integrated X-ray energy dispersive spectrometer to perform elemental quantitative analysis on the selected areas of the test surfaces of the two samples to obtain the mass percentage data of the internal electrode metal elements and the selected ceramic layer representative elements of each sample.

[0041] In this embodiment, the two prepared samples were placed in a scanning electron microscope (SEM). SEM features high resolution and large depth of field, enabling clear visualization of surface morphology at the micrometer and even nanometer scales, fundamentally overcoming the limitations of optical microscopes in terms of magnification and field of view. This method utilizes an X-ray energy dispersive spectroscopy (EDX) instrument integrated with the SEM to perform elemental quantitative analysis on selected areas of the test surfaces of the two sample sets under the same testing conditions.

[0042] Specifically, identical test conditions include, but are not limited to, identical electron beam accelerating voltage, identical beam current, identical working distance, identical observation magnification, and identical selected analysis region area. The purpose is to eliminate systematic errors and ensure absolute comparability of data obtained from the two sets of samples. Optionally, the selected region should also be located at the same position on the end face. EDX analysis can obtain information on the types of all elements within this analysis region and accurately calculate the mass percentage (Wt%) of specific elements. Optionally, the focus should be on the mass percentage of internal electrode metal elements (such as Ni, Cu, Ag, Pd, etc.) and ceramic layer representative elements (such as Ba, Ca, Sr, etc.).

[0043] S400: Based on the mass percentage data, calculate the average internal electrode exposure rate characterization value of the two groups of samples. The internal electrode exposure rate characterization value is the ratio or proportional function of the mass percentage of the internal electrode metal element to the mass percentage of the ceramic layer representative element.

[0044] A proportional function is a mathematical expression that uses "mass percentage of internal electrode metal elements" and "mass percentage of ceramic layer representative elements" as variables, and whose function value can characterize the relative proportional relationship between the two elements.

[0045] After obtaining the elemental mass percentage data, this application defines and calculates a quantitative index called the internal electrode exposure rate characterization value. The calculation method is as follows: the ratio of the mass percentage of the internal electrode metal element to the sum of the mass percentages of one or more selected ceramic layer representative elements, or the ratio of the mass percentage of the internal electrode metal element to the sum of the mass percentages of the internal electrode metal element and one or more selected ceramic layer representative elements. This ratio is expressed through a proportional function. The design concept of this calculation formula is that within the observation area, the material signal mainly originates from the exposed internal electrode metal and the exposed ceramic medium. Therefore, this ratio can sensitively reflect the relative area ratio of the metal phase and the ceramic phase within this area. The higher the ratio, the stronger the metal signal, i.e., the more fully the internal electrode is exposed. This is a clever conversion and characterization from chemical composition ratio to geometric exposure area ratio.

[0046] Within the specific region analyzed by SEM / EDX, the detected characteristic X-ray signals primarily originate from two components: the internal electrode metal exposed at the end face and the ceramic medium also exposed at the end face. Therefore, by calculating the ratio of the signal intensity of the internal electrode metal element to the signal of the ceramic medium, or to the total signal intensity of "internal electrode metal + ceramic medium," the relative proportion of the metallic phase within the selected region can be effectively characterized.

[0047] In this embodiment, the core purpose of selecting a representative element for the ceramic layer is to find one or a group of elemental signals that can most stably, uniquely, and accurately reflect the total amount of the ceramic phase. The selected representative element for the ceramic layer is applicable to a single element scenario: for certain ceramic systems with a single composition (such as BaTiO3), there exists an element (such as Ba) with a strong signal, high stability, and almost unique existence in the main crystalline phase. In this case, selecting only this single element as a representative element can concisely, efficiently, and accurately represent the entire ceramic phase, making the model as simple as possible.

[0048] For more complex composite ceramic systems (such as (Ca,Sr)(Zr,Ti)O3), a single, perfect element that can completely represent the entire ceramic main crystalline phase may not exist. In this case, selecting multiple core elements and adding their mass percentages together (e.g., Ca + Sr) to jointly characterize the ceramic phase becomes a more scientific and stable strategy. This approach can offset compositional fluctuations and avoid distortion of characterization values ​​due to small changes in the proportions of certain elements in the ceramic formulation (e.g., the Ca / Sr ratio); moreover, the sum of multiple key elements can more comprehensively reflect the overall content of the ceramic main crystalline phase, improving the robustness and accuracy of the model.

[0049] S500: Compare the average internal electrode exposure rate characterization values ​​of the first group of samples and the second group of samples. Based on the change in the internal electrode exposure rate characterization value of the second group of samples relative to the first group of samples, evaluate the effect of the chamfering treatment.

[0050] By comparing the average internal electrode exposure rate of the first group of samples (unbeveled) and the second group of samples (beveled), the effect of the bevel treatment is objectively evaluated based on the change in the characteristic value of the second group of samples relative to the first group of samples. For example, if the characteristic value is significantly improved after beveling, it proves that the beveling effectively removes the surface ceramic and increases the exposure of the internal electrode; if the characteristic value is not significantly improved after beveling, it proves that the beveling process is ineffective.

[0051] In practice, different element combinations and formulas are needed to calculate the internal electrode exposure rate of MLCCs with different material systems in order to ensure the accuracy of the results.

[0052] In an optional embodiment, when the MLCC is a Class 1 ceramic capacitor, its ceramic layer composition includes Ca, Sr, Zr, Ti, and O, and the ceramic layer representative element is selected from one or both of Ca and Sr. When the MLCC is a type 2 ceramic capacitor, its ceramic layer composition includes Ba, Ti, and O3, with Ba being the representative element of the ceramic layer.

[0053] For Class 1 ceramic capacitors, the ceramic layer composition is typically Ca. x Sr 1-x Zr Y Ti 1-Y O3, the ceramic layer of which comprises Ca, Sr, Zr, Ti, and O. In one embodiment, Ca and Sr are selected together as the representative elements of the ceramic layer. Specifically: When EDX analysis determines that the internal electrode is nickel (Ni), the calculation formula is used: Internal electrode exposure rate characterization value = W Ni / (W Ni + W Ca + W Sr ).

[0054] When the internal electrode is copper (Cu), the calculation formula is: Internal electrode exposure rate characterization value = W Cu / (W Cu + W Ca + W Sr ).

[0055] When the internal electrode is a silver-palladium (Ag-Pd) alloy, the calculation formula is: Internal electrode exposure rate characterization value = (W Ag +W Pd ) / (W Ag + W Pd + W Ca + W Sr ).

[0056] Among them, W Ni W Cu W Ca W Sr W Ag W Pd These represent the mass percentages of Ni, Cu, Ca, Sr, Ag, and Pd elements, respectively.

[0057] In the ceramic lattice of Class 1 ceramic capacitors, Ca and Sr have similar chemical properties and are randomly distributed at the same location in the lattice (A-site), together forming one of the basic frameworks of the ceramic lattice. In the formulation, the ratio of Ca to Sr (x and 1-x) can be adjusted to achieve different temperature characteristics. However, the total molar number of the A-site element (Ca+Sr) is essentially fixed in the crystal structure. Therefore, adding W... Ca + W Sr The sum of these phases, as a representative of the ceramic phase, is superior to using W alone. Ca or W Sr It is more stable and comprehensive, reflecting the overall content of the main crystalline phase of ceramics, and is not affected by fluctuations in the Ca / Sr ratio.

[0058] In this embodiment, zirconium (Zr), titanium (Ti), and oxygen (O) from the ceramic layer composition are not used as representative elements in the calculation. The reasons and effects are as follows: First, zirconium (Zr) and titanium (Ti) are not completely and stably dissolved in the main crystalline phase during the complex ceramic sintering process; they may precipitate as trace amounts of second phases (such as ZrO2 and TiO2). Including these in the calculations introduces noise from these non-main crystalline phases, causing the final characterization values ​​to deviate from the true exposure of the main crystalline phase and introducing unnecessary errors. Second, oxygen (O) is ubiquitous, and its signal sources are extremely complex. It originates not only from the ceramic itself but is also easily affected by adsorbed water on the sample surface, environmental contaminants, and residual gases in the instrument's vacuum chamber. Its mass percentage data is highly unstable and has poor repeatability.

[0059] Therefore, this application embodiment ensures the ceramic phase signal (i.e., W) used for calculating the internal electrode exposure rate characterization value by actively excluding interfering elements such as Zr, Ti, and O. Ca + W Sr It possesses high purity, stability, and representativeness. This screening process significantly improves the accuracy and repeatability of the final characterization values, enabling the evaluation results to truly and reliably reflect the changes in the microstructure of the end face caused by the chamfering process.

[0060] For Class 2 ceramic capacitors, the ceramic layer composition is typically BaTiO3. In one embodiment, the operator prefers Ba as the representative element of the ceramic layer. Specifically: When the internal electrode is nickel (Ni), the calculation formula is: Internal electrode exposure rate characterization value = W Ni / (W Ni + W Ba ).

[0061] When the internal electrode is copper (Cu), the calculation formula is: Internal electrode exposure rate characterization value = W Cu / (W Cu + W Ba ).

[0062] When the internal electrode is a silver-palladium (Ag-Pd) alloy, the calculation formula is: Internal electrode exposure rate characterization value = (W Ag +W Pd ) / (W Ag + W Pd + W Ba ).

[0063] Among them, W Ni W Cu W Ba W Ag W Pd These represent the mass percentages of Ni, Cu, Ba, Ag, and Pd elements, respectively.

[0064] Ba exhibits high signal intensity and good stability in this system, and it is almost exclusively present in the BaTiO3 main crystal phase. In this embodiment, selecting a single Ba element is sufficient to purely and accurately represent the ceramic phase, making the computational model more concise and efficient while maintaining high accuracy.

[0065] In other embodiments, for ceramic material systems with particularly complex compositions or known interferences, those skilled in the art can adaptively adjust the selected ceramic representative elements according to the selection principles described above.

[0066] In one specific embodiment, prior to the elemental quantitative analysis in S300, an instrument condition setting step is included. The following parameters need to be manually set in the SEM operating software: Electronic signal type: Select secondary electronic (SE) signal.

[0067] Accelerating voltage: Set within the range of 10 kV to 15 kV, for example, precisely set to 15.0 kV.

[0068] In this embodiment, the secondary electron signal is most sensitive to surface morphology and can obtain the clearest image; while the accelerating voltage of 10-15 kV is the optimal balance range to ensure image clarity and the accuracy of surface composition analysis. If the voltage is too low, the image signal-to-noise ratio will be poor, and if it is too high, the electron beam will penetrate too deeply, which is not conducive to surface morphology analysis.

[0069] In a specific embodiment, the thickness of the ceramic dielectric layer needs to be determined according to the design specifications of the MLCC product, and the observation magnification should be set accordingly. When the thickness of the dielectric layer is ≥10μm, the magnification ratio is set to 50x to 300x (e.g., 100x).

[0070] When the thickness of the dielectric layer is greater than 3μm and less than 10μm, the magnification factor is set to 300 to 1000 times (e.g., 500 times).

[0071] When the thickness of the dielectric layer is ≤3μm, the magnification ratio is set to 1000 to 2500 times (e.g., 2000 times).

[0072] In this embodiment, it is ensured that approximately 10 to 30 inner electrode layers can be clearly contained within the selected analysis area under different product structures. This makes the observation area have ideal statistical representativeness, avoiding both excessive layers and unclear details due to too low magnification, and insufficient layers and statistical inaccuracies due to too high magnification.

[0073] In step S200, one specific implementation of the conductivity treatment is gold sputtering, which involves depositing a thin film of metallic gold onto the sample surface using an ion sputtering apparatus. Another alternative implementation is carbon sputtering, which involves depositing an amorphous carbon film onto the sample surface using a carbon filament vapor deposition apparatus.

[0074] In this embodiment, gold sputtering provides superior conductivity and secondary electron emission efficiency, resulting in high-quality images; while carbon sputtering is less expensive and has a lower atomic number, thus causing less interference to subsequent analysis of ultralight elements.

[0075] In a specific embodiment, the step of placing the two sets of samples prepared in step S300 into a scanning electron microscope specifically includes: Perform a vacuum release operation on the electron microscope sample chamber, and open the sample chamber door after the gas pressure is balanced.

[0076] Apply conductive adhesive to the metal sample stage, and place the sample with the test side facing up and centered.

[0077] Adjust the sample stage position so that the sample surface is at the optimal working distance (e.g., 10 mm), then close the sample chamber door and start the vacuuming procedure.

[0078] In this embodiment, the sample is ensured to be correctly and stably placed in the optimal analysis position, and the necessary high vacuum environment is created for SEM and EDX analysis, which is the operational basis for obtaining reliable data.

[0079] In one specific embodiment, step S300, which involves performing elemental quantitative analysis using an integrated X-ray energy dispersive spectrometer, specifically includes: Use software to select the area to be analyzed in a clear SEM image.

[0080] In the EDX software interface, click the "Acquire New Image" and "Acquire" commands in sequence to obtain the spectrum of the element.

[0081] On the periodic table interface that pops up in the software, you can manually click to select or let the software automatically identify the element that needs to be measured.

[0082] Clicking the quantitative analysis command will generate and display a statistical table of the mass percentage of each element.

[0083] In this embodiment, the complete software operation chain from image acquisition to data output is clearly defined. Distinguishing all detected elements from the representative elements participating in the final calculation is a key operation to ensure the correct application of the calculation formula.

[0084] In one embodiment, the same testing conditions in step S300 further include: ensuring that the area size (e.g., 50 μm x 50 μm) and the number of electrode layers within the target (e.g., approximately 20 layers) of the selected analysis region remain substantially consistent each time when analyzing all samples from the first and second groups. This ensures that all data collection is performed on a completely comparable physical scale, completely eliminating variables introduced by differences in the area of ​​the analysis region or the observation scale, and making the difference between the control group and the experimental group data purely reflect the effect of the chamfering process.

[0085] In one specific embodiment, taking a common Ni electrode BaTiO3 ceramic capacitor (0402 / 106) as an example, the exposure rate of the MLCC product before and after chamfering was tested. See Table 1 and... Figures 5-12 As shown, where, Figure 5 This is a schematic diagram of the chamfered front end face of an MLCC sample in one embodiment. Figure 6 This is a schematic diagram of the chamfered rear end face of an MLCC sample in one embodiment. Figure 7 , 9 11 are, in order, the multi-element composite distribution map, the barium Ba elemental distribution map, and the nickel Ni elemental distribution map of the EDX image of the chamfered front face region of the MLCC obtained according to the method of the embodiments of this application. Figure 8 , 10 12 are, in order, the multi-element composite distribution map, the Ba barium element distribution map, and the Ni nickel element distribution map of the EDX image of the chamfered rear end face region of MLCC obtained according to the method of the embodiments of this application.

[0086] Before chamfering, the Ni exposure rate of the product after sintering was only about 19%, but it increased significantly to about 46.6% after chamfering.

[0087] Table 1. Internal electrode exposure rate of MLCC samples in Examples 1-6 before and after chamfering The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0088] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the appended claims.

Claims

1. A method for evaluating the chamfer quality of MLCCs, characterized in that, Includes the following steps: Sintered MLCCs without chamfering were provided as the first group of samples, and chamfered MLCCs from the same batch were provided as the second group of samples. Conductivity treatment was applied to the test surfaces of the first and second groups of samples, respectively. The two prepared samples were placed in a scanning electron microscope. Under the same test conditions, the selected areas of the test end face of the two samples were quantitatively analyzed by an integrated X-ray energy dispersive spectrometer to obtain the mass percentage data of the internal electrode metal elements and the selected ceramic layer representative elements of each sample. Based on the mass percentage data, the average internal electrode exposure rate characterization value of the two groups of samples is calculated. The internal electrode exposure rate characterization value is the ratio or proportional function of the mass percentage of the internal electrode metal element to the mass percentage of the ceramic layer representative element. The average internal electrode exposure rate of the first group of samples and the second group of samples were compared. The effect of the chamfering treatment was evaluated based on the change of the internal electrode exposure rate of the second group of samples relative to the first group of samples.

2. The chamfer quality assessment method for MLCCs as described in claim 1, characterized in that: When the MLCC is a Class 1 ceramic capacitor, its ceramic layer composition includes Ca, Sr, Zr, Ti, and O, and the ceramic layer representative element is selected from one or both of Ca and Sr. When the MLCC is a type 2 ceramic capacitor, its ceramic layer composition includes Ba, Ti, and O3, with Ba being the representative element of the ceramic layer.

3. The chamfer quality assessment method for MLCCs as described in claim 2, characterized in that, The MLCC is a Class 1 ceramic capacitor; When the internal electrode is Ni, the internal electrode exposure rate characterization value = W Ni / (W Ni + W Ca + W Sr ); When the internal electrode is Cu, the internal electrode exposure rate characterization value = W Cu / (W Cu + W Ca + W Sr ); When the internal electrode is Ag-Pd, the internal electrode exposure rate characterization value = (W Ag + W Pd ) / (W Ag + W Pd + W Ca +W Sr ); Among them, W Ni W Cu W Ca W Sr W Ag W Pd These represent the mass percentages of Ni, Cu, Ca, Sr, Ag, and Pd elements, respectively.

4. The chamfer quality assessment method for MLCCs as described in claim 2, characterized in that, The MLCC is a type 2 ceramic capacitor; When the internal electrode is Ni, the internal electrode exposure rate characterization value = W Ni / (W Ni + W Ba ); When the internal electrode is Cu, the internal electrode exposure rate characterization value = W Cu / (W Cu + W Ba ); When the internal electrode is Ag-Pd, the internal electrode exposure rate characterization value = (W Ag + W Pd ) / (W Ag + W Pd + W Ba ); Among them, W Ni W Cu W Ba W Ag W Pd These represent the mass percentages of Ni, Cu, Ba, Ag, and Pd elements, respectively.

5. The chamfer quality assessment method for MLCCs as described in claim 1, characterized in that, Prior to the elemental quantitative analysis step, a condition setting step is also included: The scanning electron microscope is set to use a secondary electron signal, with an accelerating voltage of 10kV to 15kV; and the magnification is set according to the thickness of the ceramic dielectric layer of the MLCC.

6. The chamfer quality assessment method for MLCCs as described in claim 5, characterized in that, The step of setting the observation magnification based on the thickness of the ceramic dielectric layer of the MLCC includes: When the thickness of the ceramic dielectric layer is not less than 10 μm, the observation magnification is set to 50x to 300x. When the thickness of the ceramic dielectric layer is greater than 3 μm and less than 10 μm, the observation magnification is set to 300x to 1000x. When the thickness of the ceramic dielectric layer is no greater than 3 μm, the observation magnification is set to 1000 to 2500 times.

7. The chamfer quality assessment method for MLCCs as described in claim 5, characterized in that, The selected area contains 10 to 30 layers of internal electrodes.

8. The chamfer quality assessment method for MLCCs as described in claim 1, characterized in that, The conductivity treatment involves spraying gold or carbon onto the surface to be tested.

9. The chamfer quality assessment method for MLCCs as described in claim 1, characterized in that, The step of placing the two prepared samples in a scanning electron microscope specifically includes: After releasing the vacuum, open the sample chamber of the scanning electron microscope; Apply conductive adhesive to the sample stage, and place the sample to be tested with the test surface facing upwards and centered on the conductive adhesive. Adjust the distance between the sample and the microscope tube to the preset working distance, close the sample chamber door and evacuate.

10. The chamfer quality assessment method for MLCCs as described in claim 1, characterized in that, The steps for elemental quantitative analysis using an integrated X-ray energy dispersive spectrometer include: Select the region to be analyzed in the scanning electron microscope image; Execute the acquisition command and acquire new image in the X-ray energy dispersive spectrometer software to obtain the elemental spectrum of the region; Manually or automatically calibrate the element to be measured in the periodic table interface; Execute the quantitative analysis command to obtain a statistical table of the mass percentage of each calibrated element.

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