Test screening method for MLCC products

Abstract

The invention relates to the technical field of multi-layer ceramic capacitors, in particular to a test screening method of an MLCC product. The test screening method of the MLCC product comprises the following steps: immersing the MLCC product in water, and carrying out heating and pressurizing treatment to enable water vapor to permeate into cracks of the MLCC product; performing surface drying treatment on the heated and pressurized MLCC product to remove moisture on the surface of the MLCC product; performing an electrical performance test on the MLCC product after the surface drying treatment; and screening out defective products in the MLCC products according to a result of the electrical performance test. According to the method, electrical defective products and defective products containing cracks can be screened out at the same time, the method has the advantages of being efficient, accurate, easy to operate and free of damage to qualified products, the reliability of MLCC products is effectively improved, and the service life of the MLCC products is effectively prolonged.

Description

Technical Field

[0001] This application relates to the field of multilayer ceramic capacitor technology, and in particular to a test and screening method for MLCC products. Background Technology

[0002] Multilayer ceramic capacitors (MLCCs), also known as surface mount capacitors, are capacitors that use ceramic as the dielectric material and have a multilayer stacked structure. MLCCs have advantages such as small size, large capacitance, high temperature resistance, and good high-frequency characteristics. They are suitable for various circuits, such as oscillation circuits, timing or delay circuits, coupling circuits, and decoupling circuits, and are widely used in consumer electronics, automotive electronics, base stations, servers, and security industries.

[0003] During the manufacturing process of MLCC products, defects containing cracks may occur due to limitations in raw materials and processes. For example, during high-temperature sintering, the difference in thermal expansion coefficients between the electrode layer and the ceramic dielectric layer can cause shrinkage mismatch, leading to surface and internal cracks in the ceramic body. Currently, the industry mainly relies on two methods to detect cracks: Visual inspection: This includes human eye or machine vision, but this method is ineffective for extremely small surface and internal cracks, resulting in a high rate of missed detection.

[0004] Routine electrical performance testing: For minute cracks that do not form a conductive path, the resulting changes in electrical signals are too weak for standard testing machines to distinguish them from qualified products, resulting in a large number of potentially defective "electrically good" products flowing downstream.

[0005] Therefore, traditional technologies lack a screening method that can efficiently, accurately, and non-destructively detect cracks in MLCC products. Summary of the Invention

[0006] Therefore, it is necessary to provide a testing and screening method for MLCC products to solve the problem that traditional technologies are difficult to efficiently, accurately and non-destructively screen out defective products containing cracks.

[0007] The above-mentioned objective of this application is achieved through the following technical solution: This application provides a testing and screening method for MLCC products, including the following steps: The MLCC product is immersed in water and subjected to heating and pressurization treatment, which allows water vapor to penetrate into the cracks of the MLCC product. The MLCC product after heat and pressure treatment is subjected to surface drying treatment to remove moisture from the surface of the MLCC product; Electrical performance tests were performed on MLCC products after surface drying treatment; Based on the results of the electrical performance test, defective MLCC products are screened out.

[0008] In one embodiment, the heating and pressurizing process includes the following steps: heating at a pressure of 70 kPa to 100 kPa and a temperature of 100°C to 200°C for 40 min to 60 min.

[0009] In one embodiment, the heating and pressurization process is carried out in a pressure vessel, which is a pressure cooker, a reaction vessel, or an autoclave.

[0010] In one embodiment, the surface drying process includes the following steps: drying at a temperature of 25°C to 35°C for 60 to 80 minutes, wherein the equipment for the surface drying process is a fan, an oven, or a room temperature air dryer.

[0011] In one embodiment, the time interval between the surface drying process and the electrical performance test does not exceed 24 hours.

[0012] In one embodiment, the electrical performance test includes leakage current testing and / or insulation resistance testing, and the electrical performance parameters include leakage current value and / or insulation resistance value.

[0013] In one embodiment, the leakage current value of a qualified MLCC product is denoted as I. A Screening for leakage current values ​​not less than 2I A The MLCC products are defective.

[0014] In one embodiment, the insulation resistance value of a qualified MLCC product is denoted as R. A The insulation resistance value was selected to be no higher than 0.5R. A The MLCC products are defective.

[0015] In one embodiment, prior to the heating and pressurizing process, the step further includes wrapping the MLCC product with a flexible wrapping material that allows water molecules to pass through, in order to prevent the MLCC product from scattering.

[0016] In one embodiment, the flexible wrapping material is a filter cloth, non-woven fabric, nylon mesh, or metal mesh.

[0017] In one embodiment, the water is deionized water, pure water, ultrapure water, or distilled water.

[0018] This application has at least the following beneficial effects: This application first uses heat and pressure to allow moisture to penetrate into the cracks of the MLCC product, and then uses a surface drying product to remove all the moisture from the product surface. At this time, a large amount of moisture remains inside the cracks, which seriously interferes with the original conductive path, causing obvious anomalies in electrical performance testing. Therefore, it can successfully screen out defective products containing cracks and prevent them from flowing downstream. At the same time, this method can also screen out defective products with poor electrical performance. It has the advantages of high efficiency, accuracy, simple operation, and no damage to qualified products, effectively improving the reliability and service life of MLCC products. Attached Figure Description

[0019] 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.

[0020] Figure 1 This is a flowchart illustrating a testing and screening method for MLCC products in one embodiment. Figure 2 The image shows the metallographic characterization results of a defective product selected in Example 1. Figure 3 The image shows the metallographic characterization results of a defective product selected in Example 2. Detailed Implementation

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] In this application, "above" or "below" includes the number itself. For example, "below 1" includes 1.

[0027] 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℃.

[0028] 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℃.

[0029] Currently, MLCC products typically undergo electrical performance testing using standard testing equipment to screen out defective products with poor electrical performance. However, among the qualified products that pass the standard testing, some still contain internal cracks. These cracked "electrically good" products are prone to short circuits, breakdowns, and damage after a period of operation, severely affecting the reliability of MLCC products and shortening their lifespan compared to qualified products without cracks. Therefore, it is necessary to develop an efficient, accurate, and non-destructive screening method for detecting cracks in MLCC products.

[0030] Based on this, this application provides a testing and screening method for MLCC products, which aims to efficiently, accurately and non-destructively screen out defective products containing cracks.

[0031] Please refer to Figure 1 This is a flowchart illustrating a testing and screening method for MLCC products in one embodiment. Figure 1 As shown, the testing and screening method for MLCC products includes the following steps: S100: Immerse the MLCC product in water and heat and pressurize it to allow water vapor to penetrate into the cracks of the MLCC product; S200: The MLCC product after heat and pressure treatment is subjected to surface drying treatment to remove moisture from the surface of the MLCC product; S300: Electrical performance testing of MLCC products after surface drying treatment; S400: Based on the results of electrical performance testing, defective MLCC products are screened out.

[0032] This application first uses heat and pressure to allow moisture to penetrate into the cracks of the MLCC product, and then uses a surface drying product to remove all the moisture from the product surface. At this time, a large amount of moisture remains inside the cracks, which seriously interferes with the original conductive path, causing obvious anomalies in electrical performance testing. Therefore, it can successfully screen out defective products containing cracks and prevent them from flowing downstream. At the same time, this method can also screen out defective products with poor electrical performance. It has the advantages of high efficiency, accuracy, simple operation, and no damage to qualified products, effectively improving the reliability and service life of MLCC products.

[0033] The following section provides a detailed explanation of the testing and screening methods for MLCC products, using a step-by-step approach.

[0034] S100: Immerse the MLCC product in water and heat and pressurize it to allow water vapor to penetrate into the cracks of the MLCC product.

[0035] MLCC products are manufactured through steps including material preparation, casting, printing, lamination, pressing, cutting, glue removal, sintering, chamfering, end sealing, end burning, and electroplating. Due to limitations in raw materials and processes, some defective products with cracks are easily produced, as well as some defective products with electrical performance parameters such as capacitance, loss, insulation resistance, and withstand voltage that do not meet the standards. These two types of defective products need to be screened out through appropriate testing.

[0036] In some embodiments, the heating and pressurizing treatment includes the following steps: heating at a pressure of 70 kPa to 100 kPa and a temperature of 100°C to 200°C for 40 min to 60 min.

[0037] As an example, the pressure of the heating and pressurizing treatment can be 70 kPa, 75 kPa, 80 kPa, 85 kPa, 90 kPa, 95 kPa, or 100 kPa; the temperature of the heating and pressurizing treatment can be 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, or 200℃; and the time of the heating and pressurizing treatment can be 40 min, 42 min, 45 min, 48 min, 50 min, 52 min, 55 min, 58 min, or 60 min.

[0038] Therefore, liquid water transforms into gaseous water molecules at high temperatures, and under the influence of pressure difference, it rapidly diffuses and fills the surface and internal cracks of MLCC products. By controlling the pressure, temperature, and time of the heating and pressurizing process, sufficient moisture is retained in the cracks of the MLCC products to severely interfere with their original conductive circuits, resulting in abnormal electrical performance parameters such as capacitance, loss, insulation resistance, and withstand voltage.

[0039] In some embodiments, the heating and pressurization process is carried out in a pressure vessel, such as an autoclave, reactor, or sterilizer. This pressure vessel can withstand high temperatures and pressures, ensuring that the heating and pressurization process can be carried out safely and smoothly. The autoclave can be a household pressure cooker, which is simple to operate and helps reduce the cost of testing and screening instruments.

[0040] In some embodiments, the water in step S100 is deionized water, pure water, ultrapure water, or distilled water, which contains very few impurities. This effectively prevents impurities in the water from migrating and diffusing into the MLCC products, thereby ensuring the reliability of the MLCC products. Understandably, the amount of water used should completely submerge all MLCC products to prevent cracks in some defective products from being unable to be fully penetrated by water vapor, which would affect the accuracy of the detection and screening.

[0041] In some embodiments, prior to the heat and pressure treatment, the step of wrapping the MLCC product with a flexible wrapping material that allows water molecules to pass through is included to prevent the MLCC product from scattering and to facilitate collection for the next step of surface drying treatment.

[0042] Understandably, the flexible encapsulation material allows water molecules to pass through; for example, it can be a porous or mesh material. The mesh size of the micropores or mesh should be smaller than the length, width, and thickness of the MLCC product. Simultaneously, the material itself should possess properties such as high temperature resistance, resistance to oxidation, and antistatic properties to avoid affecting the electrical performance of the MLCC product. Those skilled in the art can select suitable flexible encapsulation materials according to their needs; this application does not impose any particular restrictions in this regard.

[0043] In some embodiments, the flexible wrapping material is a filter cloth, non-woven fabric, nylon mesh, or metal mesh. The metal mesh can be a nickel mesh, copper mesh, or aluminum mesh. In some specific examples, a filter cloth is used as the flexible wrapping material. After wrapping the MLCC product, the opening is sealed, and then a specific clip is used to clamp and secure it.

[0044] S200: The MLCC product after heat and pressure treatment is subjected to surface drying treatment to remove moisture from the surface of the MLCC product.

[0045] In some embodiments, the surface drying process includes the following steps: drying at a temperature of 25°C to 35°C for 60 to 80 minutes, wherein the equipment for surface drying is a fan, an oven, or a room temperature air dryer. Preferably, the surface moisture is dried by blowing cold air or room temperature air from a fan.

[0046] As an example, the surface drying temperature can be 25℃, 26℃, 27℃, 28℃, 29℃, 30℃, 31℃, 32℃, 33℃, 34℃ or 35℃; the surface drying time can be 60min, 62min, 65min, 68min, 70min, 72min, 75min, 78min or 80min.

[0047] Therefore, by controlling the temperature and time of the surface drying process, not only can the moisture on the surface of MLCC products be fully removed, avoiding the influence of residual moisture on subsequent electrical performance tests and causing misjudgments, but it can also prevent the moisture retained in the cracks from evaporating, ensuring that defective products containing cracks can be detected.

[0048] In some embodiments, the time interval between surface drying treatment and electrical performance testing does not exceed 24 hours, for example, it can be 0h, 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h or 24h.

[0049] After surface drying, moisture remains in the cracks of defective products. However, this moisture evaporates over time. Performing electrical performance testing within 24 hours ensures that the moisture content within the cracks is sufficient to affect the electrical properties, thus guaranteeing the accuracy of the test. Preferably, electrical performance testing is performed immediately after surface drying.

[0050] S300: Perform electrical performance testing on MLCC products after surface drying treatment.

[0051] In some embodiments, electrical performance testing includes leakage current testing and / or insulation resistance testing, and the electrical performance parameters include leakage current value and / or insulation resistance value. The testing equipment includes a standard testing machine, a leakage current tester, or an insulation resistance analyzer.

[0052] Cracked defective products retain a large amount of moisture inside, which seriously interferes with their original conductive path, causing their leakage current or insulation resistance to rise abnormally. This allows for the efficient and accurate screening of cracked defective products.

[0053] S400: Based on the results of electrical performance testing, defective MLCC products are screened out.

[0054] Understandably, the defective products in step S400 include defective products with cracks and defective products with poor electrical performance. That is, the testing and screening method of this application can screen out structurally defective and electrically defective products in one go, which is both efficient and accurate, effectively reducing testing costs and improving the reliability and lifespan of MLCC products.

[0055] In some embodiments, the leakage current value of a qualified (OK) MLCC product is denoted as I. A Screening for leakage current values ​​not less than 2I A The MLCC products are defective (NG). If the leakage current value of the defective (NG) product is denoted as I... B Satisfying: I B ≥2I A .

[0056] Among them, the leakage current value I of qualified products A As a screening criterion for defective products, the following method can be used to determine it: For the same batch of MLCC products, take a small batch for electrical performance testing and observe whether the test data shows a normal distribution or a skewed distribution.

[0057] (1) If the test data conforms to a normal distribution, calculate the mean (μ) and standard deviation (σ), and use μ+3σ as the screening range to screen out 99.865% of the product data, only removing extreme outliers, and use the mean μ as the leakage current value I of qualified products. A Alternatively, μ+2σ or μ+σ can be used as the screening range.

[0058] (2) If the test data conforms to a skewed distribution, the percentile method (e.g., 99.865 percentile) is used as the screening range to avoid unreasonable screening range due to data skewness, and the mode of the skewed distribution is used as the leakage current value I of the qualified product. A In other examples, the median or average value can also be used as the leakage current value I for a qualified product. A .

[0059] (3) If the test data cannot be determined to be normally distributed or skewed, the statistical center value of the leakage current of all products shall be calculated based on the test data, and the statistical center value shall be used as the leakage current value I of the qualified product. AThe statistical center value can be either the mean or the median. If the test data contains no outliers, the statistical center value is the mean of all test data. If the test data contains outliers, the statistical center value is the median of all test data, or the mean of the test data after removing outliers.

[0060] Therefore, the above screening criteria can adapt to the data distribution of different batches of products, improve screening accuracy, and reduce the false positive rate. Those skilled in the art can select appropriate screening ranges and criteria based on the design standards and actual performance of MLCC products, which will not be elaborated further in this application.

[0061] In some embodiments, the insulation resistance value of a qualified (OK) MLCC product is denoted as R. A The insulation resistance value was selected to be no higher than 0.5R. A The MLCC products are defective (NG). If the insulation resistance value of the defective (NG) product is denoted as R... B Satisfying: R B ≤0.5R A Among them, the insulation resistance value R of qualified products A The method for determining this can refer to the leakage current value I of qualified products. A The method for determining the method will not be elaborated in this application.

[0062] The following description is further illustrated with specific embodiments and comparative examples. Unless otherwise specified, the raw materials involved in the following specific embodiments and comparative examples are all commercially available. Unless otherwise specified, the instruments used are all commercially available. Unless otherwise specified, the processes involved are conventionally selected by those skilled in the art.

[0063] Comparative Example 1 This comparative example did not employ heating and pressurization treatment or surface drying treatment, as detailed below: (1) After MLCC products are made through steps such as material preparation, casting, printing, stacking, lamination, cutting, glue removal, sintering, chamfering, end sealing, end burning and electroplating, 10,000 pcs (pieces) of MLCC products from the same batch are taken and leakage current is tested directly using a standard testing machine.

[0064] (2) First, take 1000pcs of MLCC products for leakage current test, observe that the test data conforms to normal distribution, calculate its mean μ, and take it as the leakage current value I of qualified products. A =1μA. Leakage current testing was performed on the remaining 9000 pieces of product, and the leakage current value I was selected. B MLCC products with an A value ≥2μA are considered defective. The test results are shown in Table 1.

[0065] Example 1 This embodiment uses 10,000 MLCC products tested in Comparative Example 1, and performs heat and pressure treatment and surface drying treatment as follows: (1) Wrap the MLCC product with a filter cloth that is resistant to high temperature, not easily oxidized and antistatic, and seal it. Then use the corresponding batch of clips to clamp and fix it.

[0066] (2) Secure the MLCC product wrapped in filter cloth in a household pressure cooker (supplier: Midea, model MY-YL50Easy203), and pour in pure water until the filter cloth and MLCC product are submerged. Cover the pot and adjust to the "beef / mutton" mode, which has a pressure of 70kPa~100kPa and a temperature of 100℃~200℃. After heating and pressurizing in this mode for 40 minutes, remove the pot lid and use tongs to remove the MLCC product wrapped in filter cloth.

[0067] (3) Use a measuring spoon to transfer the MLCC products onto the nickel grid, and use a brush to smooth the MLCC products so that they are stacked evenly and neatly. At 25°C, use the cold air from the fan to dry the MLCC products on the nickel grid for 80 minutes to remove the moisture from the surface of the MLCC products.

[0068] (4) Immediately after surface drying, a leakage current test is performed using a standard testing machine. First, 1000 MLCC products are tested for leakage current. The test data is observed to conform to a normal distribution, and the mean value μ is calculated as the leakage current value I of the qualified product. A =1μA. Leakage current testing was performed on the remaining 9000 pieces of product, and the leakage current value I was selected. B MLCC products with an A value ≥2μA were classified as defective. Test results are shown in Table 1. One defective product was selected for metallographic characterization; results are shown in... Figure 2 .Depend on Figure 2 It is evident that the defective product has obvious cracks.

[0069] Comparative Example 2 This comparative example did not employ heating and pressurization treatment or surface drying treatment, as detailed below: (1) After MLCC products are made through steps such as batching, casting, printing, stacking, lamination, cutting, glue removal, sintering, chamfering, end sealing, end burning and electroplating, take 10,000pcs of another batch of MLCC products and directly use a standard testing machine to test the insulation resistance.

[0070] (2) First, take 1000pcs of MLCC products for insulation resistance testing, observe that the test data conforms to a normal distribution, calculate its mean μ, and take it as the insulation resistance value R of qualified products. A=600mΩ. Insulation resistance tests were performed on the remaining 9000 pieces of product, and the insulation resistance values ​​R were selected. B MLCC products with an Ω of ≤300mΩ are considered defective. The test results are shown in Table 1.

[0071] Example 2 This embodiment uses 10,000 MLCC products tested in Comparative Example 2, and performs heat and pressure treatment and surface drying treatment as follows: (1) Wrap the MLCC product with a filter cloth that is resistant to high temperature, not easily oxidized and antistatic, and seal it. Then use the corresponding batch of clips to clamp and fix it.

[0072] (2) Secure the MLCC product wrapped in filter cloth in a household pressure cooker, and pour in pure water until it submerges the filter cloth and the MLCC product. Cover the pot and adjust it to the "beef / mutton" mode, which has a pressure of 70kPa~100kPa and a temperature of 100℃~200℃. After heating and pressurizing in this mode for 60 minutes, remove the pot lid and use tongs to remove the MLCC product wrapped in filter cloth.

[0073] (3) Use a measuring spoon to transfer the MLCC products onto the nickel grid, and use a brush to smooth the MLCC products so that they are stacked evenly and neatly. At 35°C, use the cold air from the fan to dry the MLCC products on the nickel grid for 60 minutes to remove the moisture from the surface of the MLCC products.

[0074] (4) Immediately after surface drying, insulation resistance testing is performed using a standard testing machine. First, 1000 MLCC products are tested for insulation resistance. The test data is observed to conform to a normal distribution, and the mean value μ is calculated as the insulation resistance value R of the qualified product. A =600mΩ. Insulation resistance tests were performed on the remaining 9000 pieces of product, and the insulation resistance value R was selected. B MLCC products with an ≤300mΩ resistance were considered defective; the test results are shown in Table 1. One defective product was selected for metallographic characterization; the results are shown in... Figure 3 .Depend on Figure 3 It is evident that the defective product has obvious cracks.

[0075] Table 1. Test screening results of Examples 1-2 and Comparative Examples 1-2 As shown in Table 1, for the same batch of MLCC products, the number of defective products and the defect rate were significantly improved after heat and pressure treatment and surface drying treatment. Metallographic characterization results confirmed that the selected defective products did indeed have cracks.

[0076] In summary, this application not only screens out electrically defective products, but also utilizes the synergistic effect of heating and pressurizing treatment and surface drying treatment to retain a large amount of moisture in the cracks of MLCC products. This causes them to exhibit obvious anomalies in electrical performance testing, such as breakdown, short circuits, or extreme outliers. Therefore, it can successfully screen out defective products containing cracks, preventing them from flowing downstream. Thus, this method has the advantages of high efficiency, accuracy, simple operation, and no damage to qualified products, effectively improving the reliability and service life of MLCC products.

[0077] 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.

[0078] 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 testing and screening MLCC products, characterized in that, Includes the following steps: The MLCC product is immersed in water and subjected to heating and pressurization treatment, which allows water vapor to penetrate into the cracks of the MLCC product. The MLCC product after heat and pressure treatment is subjected to surface drying treatment to remove moisture from the surface of the MLCC product; Electrical performance tests were performed on MLCC products after surface drying treatment; Based on the results of the electrical performance test, defective MLCC products are screened out.

2. The testing and screening method for MLCC products according to claim 1, characterized in that, The heating and pressurization process includes the following steps: Heat at a pressure of 70 kPa to 100 kPa and a temperature of 100°C to 200°C for 40 to 60 minutes.

3. The testing and screening method for MLCC products according to claim 1 or 2, characterized in that, The heating and pressurization process is carried out in a pressure vessel, which is a pressure cooker, a reaction vessel, or an autoclave.

4. The testing and screening method for MLCC products according to claim 1 or 2, characterized in that, The surface drying process includes the following steps: The surface is dried at a temperature of 25℃~35℃ for 60min~80min, and the equipment for the surface drying treatment is a fan, oven or room temperature air dryer.

5. The testing and screening method for MLCC products according to claim 1 or 2, characterized in that, The time interval between the surface drying treatment and the electrical performance test shall not exceed 24 hours.

6. The testing and screening method for MLCC products according to claim 1 or 2, characterized in that, The electrical performance test includes leakage current test and / or insulation resistance test, and the electrical performance parameters include leakage current value and / or insulation resistance value.

7. The testing and screening method for MLCC products according to claim 6, characterized in that, The leakage current value of the qualified MLCC products is denoted as I. A Screening for leakage current values ​​not less than 2I A The MLCC products are defective; and / or, The insulation resistance value of qualified MLCC products is denoted as R. A The insulation resistance value was selected to be no higher than 0.5R. A The MLCC products are defective.

8. The testing and screening method for MLCC products according to claim 1 or 2, characterized in that, Prior to the heating and pressurization process, the following steps are also included: The MLCC product is wrapped with a flexible wrapping material that allows water molecules to pass through, to prevent the MLCC product from scattering.

9. The testing and screening method for MLCC products according to claim 8, characterized in that, The flexible wrapping material is filter cloth, non-woven fabric, nylon mesh, or metal mesh.

10. The testing and screening method for MLCC products according to claim 1 or 2, characterized in that, The water is deionized water, pure water, ultrapure water, or distilled water.

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