MLCC product and method of manufacturing the same

Abstract

The application relates to the technical field of ceramic capacitors, in particular to an MLCC product and a manufacturing method thereof. The manufacturing method of the MLCC product comprises the following steps: S1, preparing a plurality of test samples; S2, measuring total capacitances of the test samples; S3, calculating the capacitances of the capacitor units corresponding to each K value based on the total capacitances and the numbers of the capacitor units in the test samples; S4, determining structure parameters of the MLCC product according to a target capacitance, a target thickness of the MLCC product and the capacitances of the capacitor units; and S5, performing laminated assembly according to the structure parameters to form the MLCC product. The manufacturing method not only improves the qualified rate of the capacity of the MLCC product, but also simplifies the production process, saves a large amount of manpower and materials, greatly reduces the manufacturing cost, has the advantages of high qualified rate and good economy, and is very suitable for the large-scale production of MLCC products with different sizes and different capacitances.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of MLCC manufacturing, and particularly relates to an MLCC product and a manufacturing method thereof. BACKGROUND

[0002] Multi-layer Ceramic Capacitors (MLCC) are also called chip capacitors, which are capacitors with ceramic as dielectric material and multi-layer stacked structure. MLCC has the advantages of small size, large capacity, high temperature resistance, and good high frequency characteristics, and can be applied to various circuits such as oscillation circuit, timing or delay circuit, coupling circuit, decoupling circuit, etc., and is widely used in consumer electronics, vehicle electronics, base stations, servers and security industries.

[0003] According to the temperature characteristics of ceramic dielectric materials, MLCC products can be divided into two categories: the first category includes temperature compensation type ceramic capacitors such as C0G (NP0), which is referred to as 1st ceramic; the second category includes high dielectric constant type ceramic capacitors such as X7 series, X6 series, X5 series, which is referred to as 2nd ceramic. Among them, the design capacity of C0G and other products in the 1st ceramic is small, and the control range of the capacity tolerance is small. In addition, slight fluctuations in factors such as film thickness, length and width of printed electrodes, and layering accuracy will be significantly amplified, resulting in low capacity hit rate of MLCC products. SUMMARY

[0004] Therefore, it is necessary to provide an MLCC product and a manufacturing method thereof to solve the problem of low capacity hit rate of MLCC products.

[0005] The above-mentioned purpose of the present application is achieved by the following technical solutions:

[0006] In a first aspect, the present application provides a manufacturing method of an MLCC product, comprising the following steps:

[0007] S1: preparing a plurality of test samples, each test sample comprising a plurality of first electrode layers and a plurality of second electrode layers arranged alternately along the stacking direction, the first electrode layers and the second electrode layers each comprising a ceramic dielectric film and an inner electrode printed thereon, and the inner electrodes of the two are cross arranged to form a capacitor unit; a continuous K blank dielectric layer is arranged between adjacent first electrode layers and second electrode layers; wherein K is a natural number, and for each test sample, the K values of all capacitor units inside are the same; among the plurality of prepared test samples, there are test samples with different K values;

[0008] S2: measuring the total capacitance of each test sample;

[0009] S3: calculating the capacitance of each capacitor unit corresponding to each K value based on the total capacitance measured in step S2 and the number of capacitor units in each test sample;

[0010] S4: determining the structure parameters of the MLCC product according to the target capacitance and target thickness of the MLCC product and the capacitance of each capacitor unit calculated in step S3, wherein the structure parameters include the number of capacitor units corresponding to each K value and the arrangement order of each capacitor unit in the stacking direction;

[0011] S5: performing stacking assembly according to the structure parameters determined in step S4 to form the MLCC product.

[0012] In one embodiment, the MLCC product includes a first protective cover, a capacitor core and a second protective cover arranged in sequence in the stacking direction, the capacitor core is composed of a plurality of capacitor units arranged in the stacking direction, the first protective cover is composed of M blank dielectric layers arranged in the stacking direction, and the second protective cover is composed of N blank dielectric layers arranged in the stacking direction.

[0013] In step S4, the structure parameters further include the values of M and N, wherein M and N are each independently selected from any integer not less than 5, and the absolute value of the difference between M and N is less than or equal to 2.

[0014] In one embodiment, in step S4, the arrangement order of each capacitor unit in the stacking direction satisfies: taking the central axis of the stacking direction as the reference, the absolute value of the difference between K values of capacitor units equidistant from the central axis is not more than 5.

[0015] In one embodiment, among the plurality of test samples prepared, there is a test sample having at least 3 different K values.

[0016] In one embodiment, the number of capacitor units in the same test sample is not less than 3.

[0017] In one embodiment, the K value is selected from any natural number between 0 and 8.

[0018] In one embodiment, after step S3, the following step is further included: based on the K value and the capacitance of each capacitor unit calculated in step S3, a function relationship between the K value and the capacitance of the capacitor unit is fitted to calculate the capacitance of the capacitor unit corresponding to other K values.

[0019] In one embodiment, the function relationship is a monomial polynomial function, and the determination coefficient R 2 ≥ 0.98.

[0020] In one of the embodiments, the ceramic dielectric film and the blank dielectric layer are prepared by a flow casting method, and the thickness of each ceramic dielectric film and each blank dielectric layer is consistent.

[0021] In the second aspect of the present application, an MLCC product is provided, which is prepared by the method for manufacturing the MLCC product as described above.

[0022] The present application has at least the following beneficial effects:

[0023] Based on the design idea that the capacitance of the capacitance unit and the thickness of the dielectric do not completely follow the inverse proportional relationship in the production process, the present application determines the capacitance of each capacitance unit by the following method: keeping the K value of all the capacitance units inside each test sample consistent, and preparing a plurality of test samples with a plurality of different K values; testing the total capacitance of each test sample, and calculating the capacitance of the capacitance unit corresponding to each K value according to the number of the capacitance units inside each test sample. According to the target capacitance, the target thickness of the MLCC product, and the capacitance of the capacitance unit corresponding to each K value, the structure parameters of the MLCC product can be determined, and the MLCC product can be obtained by laminating and assembling.

[0024] Therefore, the capacity design precision of the MLCC product can be greatly improved to ensure the qualified rate of the capacity, and the production process is effectively simplified without repeated adjustment of the test sample, which saves a large amount of manpower and materials, greatly reduces the manufacturing cost, and has the advantages of high qualified rate and good economy, which is very suitable for the mass production of MLCC products of different sizes and different capacitances. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, more completely understand the present application and its beneficial effects, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0026] Figure 1 A flowchart of the method for manufacturing the MLCC product in one embodiment;

[0027] Figure 2 A structure diagram of the test sample numbered 100 in one embodiment;

[0028] Figure 3 A structure diagram of the test sample numbered 200 in one embodiment;

[0029] Figure 4 A structure diagram of the test sample numbered 300 in one embodiment;

[0030] Figure 5 K values fitted for the examples and the capacitance C of the capacitance unit K as a function of the capacitance C of the capacitance unit.

[0031] Reference Signs:

[0032] 11, internal electrode; 12, ceramic dielectric sheet; 21, first electrode layer; 22, second electrode layer; 23, blank dielectric layer; 30, capacitance unit; 40, capacitance core; 51, first protective cover; 52, second protective cover; Z, stacking direction; 100, 200, 300, number of test samples. DETAILED DESCRIPTION

[0033] In order to facilitate the understanding of the present application, the present application will be further described in detail below in conjunction with specific embodiments. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0034] 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 in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0035] In the present application, the meaning of "and / or" is to include any and all combinations of one or more of the associated listed items. The meaning of "at least one" is one or more, such as one, two, and two or more. The meaning of "a plurality" or "several" is at least two, such as two, three, and the like, unless otherwise specifically defined. In the description of the present application, the meaning of "several" is at least one, such as one, two, and the like, unless otherwise specifically defined.

[0036] When a numerical range is disclosed in the present application, the above range is considered to be continuous and includes the minimum value and the maximum value of the range, as well as every value between the minimum value and the maximum value. Further, when the range refers to an integer, every integer between the minimum value and the maximum value of the range is included. In addition, when a plurality of ranges are provided to describe a feature or a characteristic, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed in the present application should be understood to include any and all sub-ranges subsumed therein.

[0037] If not otherwise specified, all steps of the present application can be performed in sequence or randomly. For example, the method comprises steps (a) and (b) means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method can further comprise step (c) means that step (c) can be added to the method in any sequence, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0038] In the present application, "above" or "below" includes the number itself. For example, 1 below includes 1.

[0039] In the present application, the temperature parameter, if not otherwise specified, allows for constant temperature treatment, and also allows for variation within a certain temperature range. It should be understood that the constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. It is allowed to fluctuate within the range of, for example, ±5°C, ±4°C, ±3°C, ±2°C, ±1°C.

[0040] In the present application, room temperature refers to indoor temperature, normal temperature or general temperature. Generally, the range of room temperature can be any of the following temperature ranges: 23°C±2°C, 25°C±5°C or 20°C±5°C.

[0041] Please refer to Table 1. The design capacity of products such as C0G in Class 1 ceramic of MLCC products is small, and the control range of capacity tolerance is small. In the MLCC product, two adjacent inner electrodes and the ceramic dielectric layer therebetween together form a capacitor unit, and the capacitance of each capacitor unit can be calculated using the following formula: C=(ε×8.854×S) / D. Wherein, C is the capacitance of the capacitor unit, in picofarad (pF); ε is the relative dielectric constant (also known as the dielectric constant) of the ceramic dielectric material; S is the cross-sectional area of the adjacent two printed electrodes, in square millimeters (mm2); D is the dielectric thickness of the capacitor unit (usually determined by the number of layers of the ceramic dielectric layer between the two adjacent inner electrodes during production), in microns (μm). In the principle described in the above formula, the more layers of ceramic dielectric between the two adjacent inner electrodes, the smaller the capacitance of the corresponding capacitor unit. In an MLCC product, there are often combinations of capacitor units with different dielectric thicknesses. 2

[0042] Table 1. Target capacitance and control range of capacitance tolerance of C0G / X7R

[0043]

[0044] ​In the traditional MLCC product design stage, after the capacitance of the capacitor unit provided with a single layer of ceramic dielectric layer is directly calculated according to the above formula, the number of capacitor units with different dielectric thicknesses and the stacking order of each capacitor unit constituting the MLCC product are usually determined according to the requirements of the target capacitance and the target thickness of the MLCC product. In the manufacturing stage, the statistical center point around which the capacitance distribution of the product is allowed in batch production is usually referred to as the capacitance center value. Due to the influence of the production process, the capacitance center value is not necessarily equal to the target capacitance. For example, the target capacitance of the MLCC product is 10 pF, and under the requirement of capacitance tolerance level A, the qualified range is 9.95 pF~10.05 pF. If the capacitance center value is 10.1 pF, it means that the hit rate of the capacitance of the batch of MLCC products is very low, that is, the proportion of the actual capacitance of the product falling within the qualified range is very low.

[0045] The applicant found through research that the reason for the low hit rate of the capacitance in the traditional technology is that, in the manufacturing process, due to the influence of the particle size of the slurry, the thickness of the film, the surface roughness, the length and width of the printed electrode, the stacking accuracy, the sintering temperature and the sintering atmosphere and other production conditions, the actual capacitance and the dielectric thickness of the capacitor unit cannot completely follow the inverse proportional relationship of the formula, resulting in a difference between the theoretical capacitance and the actual capacitance of each capacitor unit with different dielectric thicknesses. Since the capacitance of the MLCC product is the sum of the capacitances of each capacitor unit, the slight difference in the capacitance of each capacitor unit will gradually be amplified, resulting in a too high deviation between the actual capacitance and the target capacitance of the MLCC product, and ultimately leading to a very low hit rate of the capacitance.

[0046] In the traditional technology, in order to ensure the hit rate of the capacitance, a small number of test samples are usually prepared for each model of the MLCC product according to the target capacitance, and further design adjustment is made according to the deviation between the actual capacitance and the target capacitance of the test sample, so as to determine the structure parameters of the MLCC product of this model.

[0047] For example, the MLCC product with metric size 0402 may require the production of dozens of models at a time, each model corresponding to a target capacitance. Each time a slurry film is manufactured, test samples need to be prepared and adjusted repeatedly according to the above method for each model, making the production process complicated and tedious, and the test samples cannot be sold as finished products, resulting in a large waste of materials and labor, and a substantial increase in production cost.

[0048] Based on this, the first aspect of the present application provides a manufacturing method of an MLCC product, aiming to improve the qualified rate of capacity of the MLCC product, and having the advantages of simplifying process steps, saving materials and manpower, and reducing production cost.

[0049] In some embodiments, as shown in Figure 1 The manufacturing method of the MLCC product comprises the following steps:

[0050] S1: preparing a plurality of test samples, each of which comprises a plurality of first electrode layers and a plurality of second electrode layers arranged alternately along the stacking direction, the first electrode layers and the second electrode layers each comprising a ceramic dielectric film and an internal electrode printed thereon, and the internal electrodes of the two being arranged in cross to form a capacitor unit; a continuous K blank dielectric layer is arranged between adjacent first electrode layers and second electrode layers, wherein K is a natural number, and for each test sample, the K value of all capacitor units inside the test sample is the same; among the plurality of prepared test samples, there are test samples with a plurality of different K values;

[0051] S2: measuring the total capacity of each test sample;

[0052] S3: based on the total capacity measured in step S2 and the number of capacitor units inside each test sample, calculating the capacity of the capacitor units corresponding to each K value;

[0053] S4: determining the structure parameters of the MLCC product according to the target capacity and the target thickness of the MLCC product and the capacity of each capacitor unit calculated in step S3, the structure parameters including the number of capacitor units corresponding to each K value and the arrangement order of each capacitor unit in the stacking direction;

[0054] S5: stacking and assembling according to the structure parameters determined in step S4 to form the MLCC product.

[0055] Based on the design idea that the capacity of the capacitor unit and the dielectric thickness do not completely follow the inverse proportional relationship in the production process, the present application adopts the following method to determine the capacity of each capacitor unit: keeping the K value of all capacitor units inside each test sample consistent, and preparing a plurality of test samples with a plurality of different K values; testing the total capacity of each test sample, and calculating the capacity of the capacitor units corresponding to each K value according to the number of capacitor units inside each test sample. According to the target capacity and the target thickness of the MLCC product and the capacity of the capacitor units corresponding to each K value, the structure parameters of the MLCC product can be determined, and the MLCC product can be obtained by stacking and assembling.

[0056] Therefore, the capacity design precision of the MLCC product can be greatly improved, the capacity hit qualified rate is ensured, repeated adjustment of the test sample is not required, the production process is effectively simplified, a large amount of manpower and materials are saved, the manufacturing cost is greatly reduced, the advantages of high qualified rate and good economy are combined, and the method is very suitable for large-scale production of MLCC products of different sizes and different capacitances.

[0057] The following Figures 1-4 The manufacturing method of the MLCC product is described step by step.

[0058] S1: A plurality of test samples are prepared. Each test sample comprises a plurality of first electrode layers 21 and a plurality of second electrode layers 22 arranged alternately along a stacking direction Z, the first electrode layer 21 and the second electrode layer 22 each comprise a ceramic dielectric film 12 and an inner electrode 11 printed thereon, and the inner electrodes 11 of the two are arranged in cross to form a capacitor unit 30; a continuous K blank dielectric layer 23 is arranged between adjacent first electrode layers 21 and second electrode layers 22.

[0059] In some embodiments, the ceramic dielectric film 12 and the blank dielectric layer 23 are each made of the same ceramic dielectric material, so that the thickness and the relative dielectric constant ε of each capacitor unit 30 remain consistent.

[0060] In some embodiments, the ceramic dielectric film 12 and the blank dielectric layer 23 are each prepared by a tape casting method, and the thickness of each ceramic dielectric film 12 and each blank dielectric layer 23 remains consistent, so as to accurately control the dielectric thickness D of each capacitor unit 30. For example, the thickness of the ceramic dielectric film 12 and each blank dielectric layer 23 is 3 μm to 20 μm, for example, can be 3 μm, 5 μm, 7 μm, 9 μm, 11 μm, 13 μm, 15 μm, 17 μm, 20 μm, etc.

[0061] It can be understood that the ceramic dielectric material used by the ceramic dielectric film 12 and the blank dielectric layer 23 is the same, and the thickness of the two is also the same, that is, the blank dielectric layer 23 and the ceramic dielectric film 12 are actually the same film.

[0062] However, the present application is not limited thereto, and in other specific examples, the ceramic dielectric material and / or thickness used by the ceramic dielectric film 12 and the blank dielectric layer 23 can also be different, and those skilled in the art can make adaptive adjustments according to actual production conditions and product performance requirements.

[0063] The first electrode layer 21 and the second electrode layer 22 each include a ceramic dielectric film 12 and an inner electrode 11 printed thereon, the conductive material used for the inner electrodes 11 of both is the same, and the printing length, printing width and printing thickness are also the same, the only difference being that the inner electrodes 11 of both are arranged in cross in the stacking direction Z. The cross arrangement means that the vertical projection areas of the inner electrodes 11 of both in the stacking direction Z at least partially overlap.

[0064] In the film layer production process, the inner electrodes 11 of the first electrode layer 21 and the second electrode layer 22 can be printed on either surface of the ceramic dielectric film 12. In the stacking assembly process, the side with the inner electrodes 11 printed thereon of the first electrode layer 21 and the second electrode layer 22 are both arranged upward (or both arranged downward) to avoid the inner electrodes 11 of the first electrode layer 21 and the second electrode layer 22 from contacting each other and causing short circuit.

[0065] The first electrode layer 21 and the second electrode layer 22 are provided with continuous K blank dielectric layers 23. K is a natural number, i.e. K can be selected from any integer not less than zero, including but not limited to 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 100, etc. Further, K is selected from any natural number between 0 and 8. Still further, K is selected from any natural number between 0 and 4.

[0066] Since the larger the value of K is, the greater the dielectric thickness D of the capacitor unit 30 is, the lower the capacitance of the capacitor unit 30 is. If the value of K is selected from a smaller natural number, a capacitor unit 30 with higher capacitance can be obtained, which is beneficial to the preparation of MLCC products with high capacitance and small size.

[0067] The capacitor unit 30 is composed of the first electrode layer 21, the continuous K blank dielectric layers 23 and the second electrode layer 22 arranged in sequence in the stacking direction, and the value of K of all the capacitor units 30 inside each test sample is the same.

[0068] Let the number of layers of the first electrode layer 21 be a, the number of layers of the second electrode layer 22 be β, and the number of capacitor units 30 be θ, then θ = a + β - 1. Meanwhile, let the thickness of the blank dielectric layer 23 and the ceramic dielectric film 12 be d, then the dielectric thickness D of the capacitor unit 30 is (K + 1) × d. If the thicknesses of the blank dielectric layer 23 and the ceramic dielectric film 12 are different and are denoted as d1 and d2 respectively, then the dielectric thickness D of the capacitor unit 30 is K × d1 + d2.

[0069] As shown in FIG. 1, the capacitor unit 30 is composed of the first electrode layer 21, the continuous K blank dielectric layers 23 and the second electrode layer 22 arranged in sequence in the stacking direction Z. Figure 2As shown, in the test sample numbered 100, there are 5 capacitor units 30 inside. The K value of all capacitor units 30 is 1, that is, there is a blank dielectric layer 23 between the first electrode layer 21 and the second electrode layer 22. Each capacitor unit 30 is composed of the first electrode layer 21, the blank dielectric layer 23 and the second electrode layer 22 stacked in sequence.

[0070] like Figure 3 As shown, in the test sample numbered 200, there are 3 capacitor units 30 inside. The K value of all capacitor units 30 is 0, that is, there is no blank dielectric layer 23 between the first electrode layer 21 and the second electrode layer 22. Each capacitor unit 30 is composed of a first electrode layer 21 and a second electrode layer 22.

[0071] like Figure 4 As shown, in the test sample numbered 300, there is a capacitor unit 30 inside. The K value of the capacitor unit 30 is 3, that is, there are 3 blank dielectric layers 23 between the first electrode layer 21 and the second electrode layer 22. The capacitor unit 30 is composed of the first electrode layer 21, the three consecutive blank dielectric layers 23 and the second electrode layer 22 stacked in sequence.

[0072] However, this application is not limited to the three examples mentioned above. In other examples, the K value of all capacitor cells inside each test sample is the same and can be selected from any other natural number. Those skilled in the art can make appropriate adjustments based on preset conditions such as the target capacitance and target thickness of the MLCC product.

[0073] In some embodiments, the number of capacitor units 30 in the same test sample can be selected from any positive integer, such as 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 50, or 100. Further, the number of capacitor units 30 in the same test sample is not less than 3 to ensure the accuracy of the calculated capacitance of a single capacitor unit 30. Even further, the number of capacitor units 30 in the same test sample is 3 to 8 to reduce manufacturing costs while ensuring calculation accuracy.

[0074] In some embodiments, the prepared plurality of test samples includes test samples with multiple different K values. Further, the prepared plurality of test samples includes test samples with at least three different K values, more preferably three to eight. The more types of test samples with different K values, the more types of capacitor cells 30 with different thicknesses there are, and thus the more types of capacitor cells 30 can be selected when determining the structural parameters of the MLCC product. This is beneficial for further improving the capacitance hit rate of the MLCC product while also reducing costs.

[0075] As an example, the plurality of test samples prepared in step S1 include test samples with 5 different K values, which can be selected from any natural number between 0 and 8. Then, the 5 different K values of the test samples can include, but are not limited to, the combination of 0, 1, 2, 3, and 4; the combination of 1, 2, 3, 4, and 5; the combination of 2, 3, 4, 5, and 6; the combination of 3, 4, 5, 6, and 7; the combination of 4, 5, 6, 7, and 8; the combination of 0, 2, 4, 6, and 8; and the like.

[0076] In some embodiments, as shown in FIG. 1, the test sample includes, in sequence along the stacking direction Z, a first protective cover 51, a capacitor core 40, and a second protective cover 52. The capacitor core 40 is composed of a plurality of capacitor units 30 arranged along the stacking direction Z, the first protective cover 51 of the test sample is composed of m blank dielectric layers 23 arranged along the stacking direction Z, and the second protective cover 52 of the test sample is composed of n blank dielectric layers 23 arranged along the stacking direction Z. Herein, m and n are each independently selected from any positive integer not less than 5, and the absolute value of the difference between m and n is less than or equal to 2. Further, m and n are each independently selected from any positive integer between 5 and 50, such as 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50, and the like. Still further, m and n are each independently selected from any positive integer between 10 and 30. Figure 2 In some embodiments, the plurality of test samples prepared are each of the same thickness, i.e., the total number of blank dielectric layers 23, first electrode layers 21, and second electrode layers 22 inside each test sample is the same. As an example, the total number of blank dielectric layers 23, first electrode layers 21, and second electrode layers 22 inside each test sample is between 40 and 80, such as 40, 45, 50, 55, 60, 65, 70, 75, or 80, and the like.

[0077] S2: Measure the total capacitance of each test sample.

[0078] If the test sample is a Class 1 ceramic, the total capacitance can be measured according to the national standard GB / T21041-2007 “Fixed Capacitors for Electronic Equipment Part 21: Specification for Surface Mount Multilayer Ceramic Dielectric Fixed Capacitors of Class 1”, which is equivalent to the International Electrotechnical Commission standard IEC60384-21. If the test sample is a Class 2 ceramic, the total capacitance can be measured according to the national standard GB / T21042-2007 “Fixed Capacitors for Electronic Equipment Part 22: Specification for Surface Mount Multilayer Ceramic Dielectric Fixed Capacitors of Class 2”, which is equivalent to the International Electrotechnical Commission standard IEC60384-22. Those skilled in the art can select appropriate test methods for detection according to the temperature characteristics and other parameters of the test sample.

[0079]

[0080] ​S3: based on the total capacitance measured in step S2 and the number of capacitor units inside each test sample, the capacitance of each capacitor unit corresponding to each K value is calculated;

[0081] Let the total capacitance of the test sample be C total , and the capacitance of the capacitor unit inside the test sample be C K . Since the K values of the capacitor units inside the test sample are the same, the dielectric thickness D of each capacitor unit is the same, and the capacitance C K of each capacitor unit is also the same, so: total C K = θ × C total .

[0082] Therefore, based on the total capacitance C total measured in step S2, the number of capacitor units θ inside each test sample, and the corresponding K value, the capacitance C K of each capacitor unit corresponding to each K value is calculated, so that multiple sets of data composed of K and C K are obtained.

[0083] In some embodiments, after step S3, the following step is further included: based on the K value and the capacitance C K of each capacitor unit calculated in step S3, a function relationship between the K value and the capacitance C K of the capacitor unit is fitted to calculate the capacitance of the capacitor unit corresponding to other K values.

[0084] According to the multiple sets of data composed of K and C K , taking K value as the independent variable and C K as the dependent variable, the function relationship between C K and K value is fitted by using data processing software such as excel, origin, SPSS, etc. The function relationship can be used to predict the capacitance C K of the capacitor unit corresponding to other K values.

[0085] It can be understood that the other K values refer to the K values not included in the multiple test samples prepared in step S1. For example, the K values of the multiple test samples in step S1 are 0, 1, 2, and 3, respectively, and the nonlinear function relationship can be used to predict the capacitance C K of a single capacitor unit when K > 3.

[0086] Therefore, the types of test samples prepared in step S1 can be reduced, which saves materials and labor, and the C K corresponding to different K values can be quickly and accurately obtained, thereby providing more options for determining the structural parameters of the MLCC product and further improving the hit rate of the MLCC product.

[0087] K value and capacitance of the capacitance unit K a non-linear relationship, at least 3 sets of data consisting of K, C K are required in the fitting, therefore, in the plurality of test samples prepared in step S1, test samples with at least 3 different K values are included. The more different K values, the better the goodness of fit of the resulting functional relationship, and the closer the determination coefficient R 2 is to 1.

[0088] In some embodiments, in the case where the determination coefficient meets the requirement (such as R 2 ≥ 0.98), the functional relationship can be selected from any one of the following models: a quadratic function, a cubic function, and a quartic function.

[0089] In some embodiments, the functional relationship is a one-variable polynomial function with multiple degrees, and the determination coefficient R 2 ≥ 0.98, for example, can be 0.98, 0.985, 0.99, 0.995, 0.999, 0.9995, 0.9999 or 1, etc. Wherein, the one-variable polynomial function with multiple degrees refers to a polynomial function containing only one independent variable K and the highest degree of each term is greater than 2. Further, the functional relationship can be a one-variable quartic polynomial function, and its expression is: C K = aK 4 + bK 3 + cK 2 + dK + e, a, b, c, d, e are all arbitrary constants, and a is not 0.

[0090] S4: determining the structure parameters of the MLCC product according to the target capacitance, the target thickness of the MLCC product, and the capacitances of the capacitance units calculated in step S3, the structure parameters including the number of the capacitance units corresponding to each K value and the arrangement order of the capacitance units in the stacking direction.

[0091] It can be understood that in step S4, the structure parameters of the MLCC product can include one or more, and those skilled in the art can make further selection according to the actual production conditions, the stress distribution of the product, the current distribution of the product, etc. to obtain a MLCC product with high capacitance accuracy, high reliability and high stability.

[0092] In some embodiments, the MLCC product includes a first protective cover, a capacitance core body and a second protective cover arranged in sequence along the stacking direction, the capacitance core body is composed of a plurality of capacitance units arranged along the stacking direction, the first protective cover is composed of M blank dielectric layers arranged along the stacking direction, and the second protective cover is composed of N blank dielectric layers arranged along the stacking direction.

[0093] In step S4, the structural parameters of the MLCC product further include values of M and N, wherein M and N are each independently selected from any integer not less than 5, and the absolute value of the difference between M and N is less than or equal to 2. Further, M and N are each independently selected from any integer between 5 and 20, and the absolute value of the difference between M and N is less than or equal to 1. Exemplarily, M and N are each independently selected from any one of 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 and 20. Further, M and N are each independently selected from any integer between 5 and 12, for example, M=N=5 or M=8, N=9, etc.

[0094] In the MLCC product, the first protective cover and the second protective cover cover the upper and lower surfaces of the capacitor core. By limiting the number deviation of the blank dielectric layers in the first protective cover and the second protective cover, the functions of structural fixation, physical protection, environmental isolation and auxiliary heat dissipation can be improved, thereby improving the reliability, stability and service life of the MLCC product.

[0095] In some embodiments, in step S4, the arrangement order of each capacitor unit in the stacking direction satisfies:

[0096] With the central axis of the stacking direction as the reference, the absolute value of the difference between the K values of the capacitor units equidistant from the central axis is not more than 5, for example, can be 0, 1, 2, 3, 4 or 5, thereby balancing the internal stress.

[0097] It can be understood that the central axis of the stacking direction refers to the central axis of the capacitor core (or the MLCC product) in the stacking direction. If the total number of the first electrode layers, the second electrode layers and the blank dielectric layers in the capacitor core is odd, the central axis is located at the center line position of the middle film layer; if the total number is even, the central axis is located at the interface position between the two middle film layers.

[0098] In addition, the central axis can also be determined by the following method: if the MLCC product has an odd number of capacitor units inside, the middle capacitor unit is regarded as the central axis; if the MLCC product has an even number of capacitor units inside, the first electrode layer or the second electrode layer shared by the two middle capacitor units is regarded as the central axis.

[0099] Further, the absolute value of the difference between the K values of the capacitor units equidistant from the central axis is not more than 2. In this way, the MLCC product as a whole presents a symmetrical structure or an approximately symmetrical structure, which is beneficial to balance the stress distribution inside the product and avoid cracking of the ceramic body due to uneven stress distribution.

[0100] In some embodiments, the K value of each capacitor unit is monotonically non-decreasing in the direction pointing to the central axis. That is, the K value of the capacitor unit close to the central axis is not lower than the K value of the capacitor unit far from the central axis.

[0101] In the case that the internal ceramic dielectric film or the blank dielectric layer has many defects and it is difficult to remove the defects, the K value is thus distributed to reduce the current in the central region, thereby reducing the temperature difference in the internal. At the same time, during the cooling process after high-temperature sintering, the shrinkage stress of the central region is higher than that of the edge region, and the K value is thus distributed to avoid the generation of micro-cracks.

[0102] S5: Stack assembly according to the structure parameters determined in step S4 to form the MLCC product.

[0103] In some embodiments, the stack assembly of the MLCC product comprises the following steps:

[0104] (1) Stacking: The first electrode layer, the second electrode layer and the blank dielectric film are neatly stacked together according to the structure parameters to form a bar with consistent thickness.

[0105] (2) Laminating: By means of hydrostatic pressure with uniform temperature, the layers in the bar are tightly combined with each other to improve the density of the ceramic body after sintering, so that they are more tightly combined together.

[0106] (3) Cutting: The bar after laminating is cut horizontally and vertically according to the preset size using a sheet-like thin blade, so that it becomes a completely separated independent chip (also known as capacitor green body).

[0107] (4) Gel removal: The capacitor green body is subjected to heat treatment to remove organic matter such as adhesive.

[0108] (5) Sintering: The capacitor green body after gel removal is subjected to high-temperature sintering at 1100°C~1350°C using an atmosphere sintering furnace, so as to form a ceramic body with intact internal electrodes, high density, qualified size, high mechanical strength and excellent electrical performance.

[0109] (6) Chamfering: Also known as grinding, the ceramic body, water and chamfering balls are placed in a chamfering tank, and the ceramic body is moved by means of ball milling and planetary milling, so that the chamfering radius is obtained while the burrs on the surface of the ceramic body are removed, the surface is smooth, and the internal electrodes of the end surface are fully exposed.

[0110] (7) End sealing: The end electrode paste is coated on both ends of the ceramic body after chamfering by means of an end sealing machine, so that the internal electrodes of the end surface are connected and an external electrode is formed.

[0111] (8) End sintering: Under high-temperature conditions, the organic binder in the end electrode paste is fully burned, the glass powder is melted and infiltrated into the copper powder, so that the end is solidified and forms a good connection with the ceramic body and the internal electrodes.

[0112] (9) Electroplating: In an electroplating solution containing nickel ions or tin ions, the end electrode is used as a cathode, and a certain low-voltage direct current is applied to continuously deposit a nickel layer or a tin layer on the surface of the cathode.

[0113] (10) Testing and inspection: 100% testing and sorting of MLCC products are performed for the performance of capacity, loss, insulation, and voltage resistance, and defective products are removed. After being sorted according to different capacity ranges, appearance inspection is performed.

[0114] In the second aspect, the application provides an MLCC product prepared by the method for manufacturing an MLCC product described above. Thus, the MLCC product has the advantages of high capacity design precision and low preparation cost for various size and capacity design requirements, and is very suitable for large-scale industrial application.

[0115] The following will be further described in combination with specific examples and comparative examples. The raw materials involved in the following specific examples and comparative examples can be sourced from the market if not specifically stated. The instruments used can be sourced from the market if not specifically stated. The processes involved can be routinely selected by those skilled in the art if not specifically stated.

[0116] Examples

[0117] The present embodiment provides a method for testing the capacitance of a capacitor unit, which is specifically as follows:

[0118] (1) Five test samples are prepared.

[0119] Each test sample comprises 5 first electrode layers (denoted as A) and 5 second electrode layers (denoted as B) arranged alternately along the stacking direction. The first electrode layer and the second electrode layer each comprise a ceramic dielectric film and an inner electrode printed thereon, and the inner electrodes of the two are arranged in a cross shape to form a capacitor unit. A continuous K blank dielectric layer is arranged between adjacent first electrode layers and second electrode layers.

[0120] Each test sample comprises a first protective cover, a capacitor core, and a second protective cover arranged in sequence along the stacking direction. The first protective cover is composed of m blank dielectric layers arranged along the stacking direction, and the second protective cover is composed of n blank dielectric layers arranged along the stacking direction. The number of capacitor units is one less than the total number of first electrode layers and second electrode layers (i.e. 5x2-1), so the capacitor core is composed of 9 capacitor units arranged along the stacking direction. Therefore, the layer structure of each test sample can be represented as "m--(AKB)×5--n".

[0121] As shown in Table 2, the layer composition of the test sample is “23--(A0B)×5--22”, which means that the first protective cover has 23 blank dielectric layers, the second protective cover has 22 blank dielectric layers, the capacitor core is composed of 5 alternating first electrode layers and 5 second electrode layers, forming 9 capacitor units, the K value of each capacitor unit is 0, and the total number of layers is 55. The other layer compositions are similar and will not be described in detail.

[0122] (2) The total capacitance C of each test sample was measured according to JIS C5101-21. total .

[0123] (3) Based on the total capacitance C total The number of capacitor units inside each test sample is determined by C. total =9×C K The capacitance value C of a single capacitor unit corresponding to each K value is calculated. K The results are listed in Table 2.

[0124] Using K as the independent variable and the capacitance C of a single capacitor unit as the input variable... K As the dependent variable, Excel can be used to fit the data to obtain the following results: Figure 5 The univariate quartic polynomial function shown has the following expression:

[0125] C K =0.0555K 4 -0.6036K 3 +2.5337K 2 -5.4578K+7.5556, its coefficient of determination R 2 =1.

[0126] Using the above expression, the capacitance value C of a single capacitor cell when K>4 can be calculated. K .

[0127] Table 2. Capacitance data of the test samples

[0128]

[0129] Comparative Example

[0130] This comparative example uses a traditional testing method to calculate the capacitance of a capacitor cell, as detailed below:

[0131] For the test samples prepared in the examples, it can be based on C K The theoretical capacitance C of the capacitor unit is calculated by ' = (ε × 8.854 × S) ÷ D. K ', and according to C total =9×C K The theoretical total capacitance C of the test sample was calculated. total'Then, the total capacitance C of the test sample...' total The deviation η of the sum is: η = (C total -C total ')÷C total ×100%, the results are listed in Table 2.

[0132] The ceramic dielectric material used in the ceramic dielectric film and the blank dielectric layer has a relative permittivity ε = 23.36. The ceramic dielectric film and the blank dielectric layer are prepared using a casting method with a thickness d = 11 μm. The dielectric thickness of the capacitor unit is D = (K + 1) × d. The cross-sectional area S of the inner electrodes of the first electrode layer and the second electrode layer is 0.402 mm². 2 .

[0133] As shown in Table 2, with the increase of K value, the capacitance C of each capacitor unit increases. K and theoretical capacitance C K The difference between ' and ' is getting larger and larger, causing the total capacitance C of the test sample to increase. total and theoretical total capacitance C total The deviation η of ' is significantly increased, reaching nearly 20% when K=4. This shows that the test product designed based on the inverse proportional relationship has an extremely low capacity hit rate. Repeated adjustments are required to obtain a suitable test product and determine the structural parameters of the MLCC product. The whole process is cumbersome and complex, consuming a lot of materials and labor, resulting in high manufacturing costs.

[0134] Application examples

[0135] This application example uses the capacitance value C of the capacitor cell measured according to the embodiment. K Based on the target capacitance and thickness of the MLCC products, the structural parameters of different MLCC products were determined. These structural parameters include the number of capacitor cells corresponding to each K value, the arrangement order of each capacitor cell in the stacking direction, and the number of blank dielectric layers contained in the first and second protective covers, thus obtaining the layer composition shown in Table 3. Finally, the layers were stacked according to the structural parameters of the MLCC products to form a series of MLCC products.

[0136] As can be seen from Table 3, according to the 5 test samples, the structure parameters of the MLCC products with the target capacitance in the range of 8.0 pF~330 pF can be determined. Among them, the layer structure of the MLCC product numbered 12 is "4--(A0B)×11-A1B-(A0B)×11--4", which means that in the stacking direction, there are: 4 blank dielectric layers as the first protective cover; 11 first electrode layers and 11 second electrode layers arranged alternately; the first electrode layer, the blank dielectric layer and the second electrode layer arranged in turn; 11 first electrode layers and 11 second electrode layers arranged alternately; 4 blank dielectric layers as the second protective cover. The layer structures of the MLCC products with other numbers are sequentially deduced and will not be repeated here.

[0137] In summary, the embodiment can determine 5 K values and the capacitances of the corresponding capacitor units through 5 test samples, and can design at least multiple MLCC products with different target capacitances in the application example. The embodiment can effectively simplify the production process, avoid a large amount of material and labor loss, and significantly reduce the production cost while ensuring the qualified rate of the capacitance of the MLCC product.

[0138] Table 3. Target capacitance of MLCC product and corresponding layer design

[0139]

[0140] Each of the technical features of the above-described embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, however, as long as the combinations of the technical features do not exist contradictory, they should be considered as the scope of the present application.

[0141] The above-described embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the protection scope of the present application. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A method for manufacturing an MLCC product, characterized in that, Includes the following steps: S1: Prepare multiple test samples. Each test sample includes multiple first electrode layers and multiple second electrode layers arranged alternately along the stacking direction. Both the first electrode layer and the second electrode layer include a ceramic dielectric film and an internal electrode printed thereon, and the internal electrodes of the two are arranged intersectingly to form a capacitor unit. K consecutive blank dielectric layers are disposed between adjacent first electrode layers and second electrode layers, where K is a natural number. For each test sample, the K value of all capacitor units inside it is the same. The prepared multiple test samples include test samples with multiple different K values. S2: Measure the total capacitance of each of the test samples; S3: Based on the total capacitance measured in step S2 and the number of capacitor units inside each test sample, calculate the capacitance of the capacitor unit corresponding to each K value. S4: Based on the target capacitance, target thickness of the MLCC product and the capacitance of each capacitor unit calculated in step S3, determine the structural parameters of the MLCC product. The structural parameters include the number of capacitor units corresponding to each K value and the arrangement order of each capacitor unit in the stacking direction. S5: Perform stacking and assembly according to the structural parameters determined in step S4 to form the MLCC product; Following step S3, the following steps are also included: Based on the K value and the capacitance of each capacitor unit calculated in step S3, a functional relationship between the K value and the capacitance of the capacitor unit is fitted to calculate the capacitance of the capacitor unit corresponding to other K values. The functional relationship is a univariate polynomial function with a coefficient of determination R. 2 ≥0.

98.

2. The method for manufacturing MLCC products as described in claim 1, characterized in that: The MLCC product includes a first protective cover, a capacitor core, and a second protective cover arranged sequentially along the stacking direction. The capacitor core is composed of multiple capacitor cells arranged along the stacking direction. The first protective cover is composed of M blank dielectric layers arranged along the stacking direction. The second protective cover is composed of N blank dielectric layers arranged along the stacking direction. In step S4, the structural parameters also include the values ​​of M and N, wherein M and N are each independently selected from any integer not less than 5, and the absolute value of the difference between M and N is less than or equal to 2.

3. The method for manufacturing MLCC products as described in claim 2, characterized in that, In step S4, the arrangement order of each capacitor unit in the stacking direction satisfies: With the central axis of the stacking direction as a reference, the absolute value of the difference in K value between capacitor units that are equidistant from the central axis does not exceed 5.

4. The method for manufacturing MLCC products as described in claim 1, characterized in that, Among the multiple test samples prepared, there are test samples with at least 3 different K values.

5. The method for manufacturing MLCC products as described in claim 1, characterized in that, The number of capacitor units in the same test sample is not less than 3.

6. The method for manufacturing the MLCC product as described in any one of claims 1 to 5, characterized in that, The value of K is selected from any natural number between 0 and 8.

7. The method for manufacturing the MLCC product according to any one of claims 1 to 5, characterized in that, The functional relationship is a univariate quartic polynomial function, and its expression is: C K =aK 4 +bK 3 +cK 2 +dK+e; Where a, b, c, d, and e are all arbitrary constants, and a is not 0.

8. The method for manufacturing the MLCC product as described in claim 1, characterized in that, Both the ceramic dielectric film and the blank dielectric layer are prepared by casting molding, and the thickness of each ceramic dielectric film and each blank dielectric layer is consistent.

9. The method for manufacturing the MLCC product as described in claim 8, characterized in that, The thickness of the ceramic dielectric film and the blank dielectric layer is 3μm~20μm.

10. An MLCC product, characterized in that, It is manufactured using the manufacturing method of the MLCC product as described in any one of claims 1 to 9.

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