X7R type dielectric ceramic material with excellent reliability

Abstract

The invention provides an X7R type dielectric ceramic material with excellent reliability and a preparation method thereof. The dielectric ceramic material comprises needle-like BaTiO3 powder, ZrSiO4, a doping agent, an additive and a sintering aid, the doping agent is graphene modified kaolin, the additive is CaCO3, and the sintering aid is V2O5. According to the X7R type dielectric material, the needle-shaped BaTiO3 is coated with ZrSiO4, a structure with the needle-shaped BaTiO3 as a core and the ZrSiO4 as a shell is formed, and under the combined action of the dopant and the additive, the reliability of the X7R type dielectric material can be effectively improved.

Description

Technical Field

[0001] The present application relates to an X7R type dielectric ceramic material with excellent reliability and a preparation method thereof, and belongs to the technical field of ceramic capacitor materials. Background Art

[0002] In recent years, with the widespread use of electronic products, the requirements for MLCC have become higher and higher, facing the requirement of high reliability, but the corresponding materials in the domestic market are gradually unable to meet the development requirements. Therefore, developing capacitor dielectric materials with higher reliability and stability and realizing industrialization is one of the key points of the sustainable development of the domestic electronics industry.

[0003] According to the standards of the Electronic Industries Association (EIA), in X7R ceramic materials: X represents the low temperature limit of the working temperature zone -55°C, 7 represents the high temperature limit of the working temperature zone +125°C, and R represents the rate of change of capacitance at all temperature points in the working temperature zone (within the range of -55°C to +125°C) relative to the room temperature of 25°C, which is less than or equal to ±15%.

[0004] The microstructure determines the reliability and stability of dielectric ceramic materials, which requires the main component BaTiO 3 It has high crystallinity, regular particle morphology, monodispersity and high purity; at the same time, the particle sizes of the main component and the auxiliary component must not only match but also be mixed very evenly to make the crystal dense. Summary of the invention

[0005] The present invention aims to provide an X7R ceramic capacitor dielectric material and a preparation method thereof, which overcomes the deficiencies of the prior art and solves the problem of poor reliability and stability of current ceramic dielectric materials. Moreover, the dielectric ceramic material produced by the present invention can also be sintered at low temperature and has good mechanical properties.

[0006] The technical solution of the present invention is: a safe and reliable X7R type dielectric ceramic material, comprising the following components: 95-98wt% of needle-shaped BaTiO 3 ; 0.8-1.2wt% content ZrSiO 4 ; 0.1-0.5wt% modified kaolin; 0.2-0.8wt% CaCO 3 ; 0.2-0.8wt% content V 2 O 5 .

[0007] Needle-shaped BaTiO 3 It is a kind of BaTiO with needle-like morphology. 3 .

[0008] The method for preparing the ceramic material is characterized by comprising the following steps:

[0009] Step 1: Preparation of the main component needle-shaped BaTiO 3 ;

[0010] Step 2: ZrSiO 4 Put it into the slurry described in step 1 to form BaTiO 3 As the core, ZrSiO 4 A solution of shell;

[0011] Step 3: Modify kaolin with dopant and CaCO 3 Adding to the solution in step 2, and then calcining;

[0012] Step 4: Mix the calcined product with a sintering aid V 2 O 5 After mixing, wet dispersion and drying are performed to obtain a dielectric material for MLCC with X7R characteristics.

[0013] Specifically, the main component needle-shaped BaTiO was prepared by hydrothermal method. 3 The powder was then dispersed in water or ethanol solution, and milled in a ball mill at 450 rpm for 5-6 h using zirconium dioxide balls as the milling medium. 4 Put it into the slurry described in the step, stir it for 0.5h and then disperse it with ultrasound for 2h to mix the dopant graphene modified kaolin and the additive CaCO 3 At the same time, calcined at 1100℃ for 3h, the calcined product and sintering aid V 2 O 5 After mixing, wet dispersion and drying are performed to obtain a dielectric material for MLCC with X7R characteristics. The beneficial effects of the present invention are as follows:

[0014] Needle-shaped BaTiO 3 As a core structure, the dielectric constant and temperature stability characteristics of the dielectric ceramic material of the present invention can be ensured when the above addition amount is used. 4 When it is coated in ceramic materials as a shell structure, it can form agglomerates in the crystals, forming a network structure and preventing crystal growth, thereby preventing material deformation and cracking. After graphene-modified kaolin is doped and sintered, the gaps between particles are reduced and the microstructure is dense, thereby enhancing the overall performance of the material. However, the content of dopants needs to be controlled. When the amount added is small, the reliability performance is not obvious. When too much is added, the dielectric properties will decrease. The dielectric ceramic material produced by this formula has a dielectric temperature stability that meets the requirements of X7R, a dielectric constant of 2700~3200, and an insulation resistance of >2000, which is suitable for the production of MLCC products with high reliability and life. DETAILED DESCRIPTION

[0015] For ease of understanding of the present invention, the application will be described more fully below with reference to relevant embodiments. The following provides preferred embodiments of the application. However, the application can be implemented 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 understanding of the disclosure of the application more thorough and comprehensive.

[0016] Example 1

[0017] This embodiment provides a X7R ceramic capacitor dielectric material, including the following raw materials in weight percentage: 95g of needle-shaped BaTiO 3 , 0.9 g ZrSiO 4 , 0.1 g of modified kaolin, 0.5 g of CaCO 3 , 0.2g V 2 O 5 .

[0018] The preparation method of the above X7R type dielectric material is as follows:

[0019] Step 1: Preparation of the main component needle-shaped BaTiO by hydrothermal method 3 ;

[0020] Step 2: ZrSiO 4 After being put into the slurry and stirred for 0.5h, it was dispersed by ultrasonic for 2h to form BaTiO 3 As the core, ZrSiO 4 A solution of shell;

[0021] Step 3: Modify kaolin with dopant and CaCO 3 Add to the solution in step 2 and calcine at 1100°C for 3h;

[0022] Step 4: Mix the calcined product with a sintering aid V 2 O 5 After mixing, wet dispersion and drying are performed to obtain a dielectric material for MLCC with X7R characteristics.

[0023] Example 2

[0024] This embodiment provides a X7R ceramic capacitor dielectric material, including the following raw materials in weight percentage: 95g of needle-shaped BaTiO 3 , 0.9 g ZrSiO 4 , 0.5 g of modified kaolin, 0.6 g of CaCO 3 , 0.3g V 2 O 5 .

[0025] The preparation method of this embodiment is the same as that of embodiment 1.

[0026] Example 3

[0027] This embodiment provides a X7R ceramic capacitor dielectric material, including the following raw materials in weight percentage: 95g of needle-shaped BaTiO 3 , 1.2 g ZrSiO 4 , 0.5 g of modified kaolin, 0.6 g of CaCO 3 , 0.4g V 2 O 5 .

[0028] The preparation method of this embodiment is the same as that of embodiment 1.

[0029] Example 4

[0030] This embodiment provides a X7R ceramic capacitor dielectric material, including the following raw materials in weight percentage: 96g of needle-shaped BaTiO 3 , 1.2 g ZrSiO 4 , 0.3 g of modified kaolin, 0.7 g of CaCO 3 , 0.4g V 2 O 5 .

[0031] The preparation method of this embodiment is the same as that of embodiment 1.

[0032] Example 5

[0033] This embodiment provides a X7R ceramic capacitor dielectric material, including the following raw materials in weight percentage: 96g of needle-shaped BaTiO 3 , 0.8 g ZrSiO 4 , 0.3 g of modified kaolin, 0.8 g of CaCO 3 , 0.5g V 2 O 5 .

[0034] The preparation method of this embodiment is the same as that of embodiment 1.

[0035] Example 6

[0036] This embodiment provides a X7R ceramic capacitor dielectric material, including the following raw materials in weight percentage: 96g of needle-shaped BaTiO 3 , 0.8 g ZrSiO 4 , 0.2 g of modified kaolin, 0.2 g of CaCO 3 , 0.5g V 2 O 5 .

[0037] The preparation method of this embodiment is the same as that of embodiment 1.

[0038] Example 7

[0039] This embodiment provides a X7R ceramic capacitor dielectric material, including the following raw materials in weight percentage: 97g of needle-shaped BaTiO 3 , 1.0 g ZrSiO 4 , 0.2 g of modified kaolin, 0.2 g of CaCO 3 , 0.6g V 2 O 5 .

[0040] The preparation method of this embodiment is the same as that of embodiment 1.

[0041] Example 8

[0042] This embodiment provides a X7R ceramic capacitor dielectric material, including the following raw materials in weight percentage: 97g of needle-shaped BaTiO 3 , 1.0 g ZrSiO 4 , 0.4 g of modified kaolin, 0.3 g of CaCO 3 , 0.6g V 2 O 5 .

[0043] The preparation method of this embodiment is the same as that of embodiment 1.

[0044] Example 9

[0045] This embodiment provides a X7R ceramic capacitor dielectric material, including the following raw materials in weight percentage: 98g of needle-shaped BaTiO 3 , 0.9 g ZrSiO 4 , 0.4 g of modified kaolin, 0.3 g of CaCO 3 , 0.6g V 2 O 5 .

[0046] The preparation method of this embodiment is the same as that of embodiment 1.

[0047] Example 10

[0048] This embodiment provides a X7R ceramic capacitor dielectric material, including the following raw materials in weight percentage: 98g of needle-shaped BaTiO 3 , 1.2 g ZrSiO 4 , 0.4 g of modified kaolin, 0.4 g of CaCO 3 , 0.7g V 2 O 5 .

[0049] The preparation method of this embodiment is the same as that of embodiment 1.

[0050] Comparative Example 1

[0051] This embodiment provides a X7R ceramic capacitor dielectric material, including the following raw materials in weight percentage: 95g of needle-shaped BaTiO 3 , 0.9 g ZrSiO 4 , 0.05 g of modified kaolin, 0.4 g of CaCO 3 , 0.8g V 2 O 5 .

[0052] The preparation method of this embodiment is the same as that of embodiment 1.

[0053] Comparative Example 2

[0054] This embodiment provides a X7R ceramic capacitor dielectric material, including the following raw materials in weight percentage: 98g of needle-shaped BaTiO 3 , 1.0 g ZrSiO 4 , 0.6 g of modified kaolin, 0.4 g of CaCO 3 , 0.8g V 2 O 5 .

[0055] The preparation method of this embodiment is the same as that of embodiment 1.

[0056] In the above embodiments, the formula list of each dielectric ceramic material is shown in Table 1.

[0057] Table 1 X7R characteristics MLCC dielectric material composition

[0058]

[0059] Performance Testing

[0060] The X7R dielectric ceramic materials prepared by the above Examples 1-10 and Comparative Examples 1-2 are prepared according to the conventional MLCC preparation process: slurry preparation → casting → screen printing → lamination → lamination → cutting → debinding → sintering → chamfering → end sealing → sintering end to prepare MLCC; the product specification is 0805, the operating voltage is 50V, the dielectric layer thickness is 5μm, and silver-palladium inner paste is used for screen printing. The product is sintered at 1100°C in an air atmosphere. After chamfering, silver external electrodes are sealed at both ends of the product. The product is heat treated at 900°C in an air atmosphere, and then the relevant electrical properties are tested.

[0061] At room temperature of 25℃ and 45-65%RH, the capacitance C and dielectric loss DF of MLCC were tested at 1KHz and 1Vrm using an Agilent4284A bridge, and the dielectric constant was calculated based on the thickness of the dielectric layer, the effective electrode area, the screen factor, the number of dielectric layers, and the capacitance. The insulation resistance IR of MLCC was tested at 25VDC, 25℃, and 60S using a TH2683 insulation resistance tester. The withstand voltage BDV of MLCC was tested at a charging current of <20mA and a voltage application rate of 200V / 60S using a CJ2671S withstand voltage tester. The temperature coefficient TCC of MLCC was tested between -55℃ and 125℃ using a high and low temperature test chamber. The reliability life of MLCC was tested at 140℃ and 100V DC using a life test chamber, and the failure time was defined from the start of voltage application to the time when the insulation resistance IR value dropped below 1*106Ω. The length of the failure time was used as the evaluation result of the reliability life performance.

[0062] The test results are shown in Table 2. As can be seen from Table 2, within the required range of the present invention, a dielectric material with excellent dielectric properties and reliability life can be obtained.

[0063] Table 2 Performance parameters of MLCCs prepared in various embodiments and comparative examples

[0064]

[0065]

[0066] Although the present invention has been described in detail above with general descriptions and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements may be made thereto based on the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. An X7R type dielectric ceramic material, characterized in that: The dielectric material consists of: 95-98wt% of needle-shaped BaTiO3, 0.8-1.2wt% of ZrSiO4, 0.1-0.5wt% of modified kaolin, 0.2-0.8wt% of CaCO3, and 0.2-0.8wt% of V2O5.

2. As claimed in claim 1, characterized in that The dielectric material is a coated core-shell structure, wherein needle-shaped BaTiO3 powder serves as a core structure and ZrSiO4 serves as a shell structure coated on the core.

3. The ceramic material according to claim 1, characterized in that Kaolin is exfoliated using chemical intercalation to form nanoscale kaolin, which is then modified with graphene.

4. As claimed in claims 1 to 2, characterized in that ZrSiO4 is synthesized by reaction under high temperature conditions, in which SiO2 is rutile and ZrO2 is tetragonal phase.

5. The ceramic material as claimed in claim 1, wherein modified kaolin is a dopant; CaCO3 is an additive; and V2O5 is a sintering aid.

6. The method for preparing the X7R type ceramic material according to claim 1, characterized in that: Step 1: Prepare the main component needle-shaped BaTiO3; Step 2: Adding ZrSiO4 into the slurry in step 1 to form a solution with BaTiO3 as the core and ZrSiO4 as the shell; Step 3: adding the dopant-modified kaolin and the additive CaCO3 to the solution in step 2, and then calcining; Step 4: After mixing the calcined product with the sintering aid V2O5, the mixture is wet dispersed and dried to obtain the dielectric material for MLCC with X7R characteristics.

7. As claimed in claim 5, characterized in that The preparation method described in step 1 is a hydrothermal method.

8. As claimed in claim 5, characterized in that The process described in step 2 is to add ZrSiO4 into the slurry described in step 2, stir for 0.5h and then disperse with ultrasound for 2h.

9. As claimed in claim 5, characterized in that In step 3, the process includes adding the dopant-modified kaolin and the additive CaCO3 simultaneously, and calcining at 1100° C. for 3 h.

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