Multilayer ceramic capacitor and method of manufacturing the same

Abstract

The application relates to the technical field of ceramic capacitors, and particularly discloses a multilayer ceramic capacitor and a preparation method thereof. The multilayer ceramic capacitor comprises a ceramic body, first and second end faces, two first side faces and two second side faces; inner electrodes comprising first and second inner electrodes, one end of the first inner electrode extending out of the first end face of the ceramic body, and one end of the second inner electrode extending out of the second end face of the ceramic body; and two outer electrodes, the outer electrode comprising a main body part, two first extension parts and two second extension parts, the two outer electrodes being electrically connected with the first and second inner electrodes, the two first extension parts extending out of the two sides of the main body part along the z direction, and the two second extension parts extending out of the two sides of the main body part along the y direction. The multilayer ceramic capacitor and the preparation method thereof avoid the formation of sharp corners of the outer electrode, thereby preventing breakdown caused by charge concentration, and improving the electric strength of the multilayer ceramic capacitor.

Description

Technical Field

[0001] This invention relates to the field of ceramic capacitor technology, and in particular to a multilayer ceramic capacitor and its preparation method. Background Technology

[0002] Currently, the external electrodes of multilayer ceramic capacitors are generally formed using a dip-coating process, such as... Figure 1 As shown, the end of the first external electrode 3' forms a sharp corner A on the edge of the first ceramic body 1' of the multilayer ceramic capacitor. Charge easily accumulates at the sharp corner A, creating a region of highly concentrated electric field between the sharp corner A of the first external electrode 3' and the corner B of the fifth internal electrode 2' with opposite polarity. When a high voltage is applied to the multilayer ceramic capacitor, this region is prone to breakdown, resulting in low dielectric strength of the multilayer ceramic capacitor. The technical solution of this application solves the above problems through structural improvements. Summary of the Invention

[0003] The purpose of this invention is to provide a multilayer ceramic capacitor that avoids the formation of sharp corners on the external electrodes, thereby preventing breakdown due to charge concentration and improving the dielectric strength of the multilayer ceramic capacitor.

[0004] To achieve the above objectives, in a first aspect, the present invention provides a multilayer ceramic capacitor having x-direction, y-direction, and z-direction, comprising:

[0005] The ceramic body has a first end face and a second end face arranged along the x direction, two first side faces arranged along the y direction, and two second side faces arranged along the z direction, wherein the two first side faces and the two second side faces enclose and form four edges.

[0006] The internal electrode includes a first internal electrode and a second internal electrode alternately disposed within the ceramic body along the z-direction, wherein one end of the first internal electrode extends beyond a first end face of the ceramic body, and one end of the second internal electrode extends beyond a second end face of the ceramic body; and

[0007] Two external electrodes are provided, each comprising a main body, two first extensions, and two second extensions. The main bodies of the two external electrodes are respectively disposed on the first end face and the second end face, and are electrically connected to the first inner electrode and the second inner electrode, respectively. The two first extensions extend outward from both sides of the main body along the z-direction, and each of the two first extensions corresponds to and covers one of the two second side faces. The side edges of the first extensions along the y-direction are spaced apart from the edges of the second side faces along the y-direction. The two second extensions extend outward from both sides of the main body along the y-direction, and each of the two second extensions corresponds to and covers one of the two first side faces. The side edges of the second extensions along the z-direction are spaced apart from the edges of the first side faces along the z-direction.

[0008] In some embodiments, the four corners of the main body have notches, and the four edges of the ceramic body are located in the notches one by one.

[0009] In some embodiments, one end of the first inner electrode extends out of the first side surface, and the second extension of one of the outer electrodes covers the portion of the first inner electrode extending out of the first side surface. One end of the second inner electrode extends out of the first side surface, and the second extension of the other outer electrode covers the portion of the second inner electrode extending out of the first side surface.

[0010] In some embodiments, the inner electrode includes a third inner electrode and a fourth inner electrode disposed alternately in the ceramic body along the z-direction. The third inner electrode is located on the side of the first inner electrode away from the second inner electrode, and the fourth inner electrode is located on the side of the second inner electrode away from the first inner electrode. One end of the third inner electrode extends out of the first end face of the ceramic body and is electrically connected to the main body of one of the outer electrodes. One end of the fourth inner electrode extends out of the second end face of the ceramic body and is electrically connected to the main body of the other outer electrode. The third inner electrode is spaced apart from the two first side faces, and the fourth inner electrode is spaced apart from the two first side faces.

[0011] In some embodiments, the body portion includes a nickel layer and a tin layer disposed from the inside out.

[0012] In some embodiments, the main body includes a copper layer, a nickel layer, and a tin layer disposed from the inside out.

[0013] In some embodiments, both the first extension and the second extension include a nickel layer and a tin layer disposed from the inside out.

[0014] In some embodiments, both the first extension and the second extension include a first nickel layer, a copper layer, a second nickel layer, and a tin layer.

[0015] In a second aspect, the present invention provides a method for preparing a multilayer ceramic capacitor, comprising:

[0016] Ceramic powder, binder and organic solvent are mixed to form a ceramic slurry, and the ceramic slurry is cast to obtain a ceramic film;

[0017] Nickel metal paste is printed on the ceramic film and dried to form an internal electrode film;

[0018] Multiple ceramic films having internal electrode films are stacked along the z-direction to form a stacked structure. The ceramic films are then covered on both sides of the stacked structure along the z-direction to obtain a stacked body mother plate.

[0019] Nickel metal paste is printed on both sides of the laminate mother plate along the z direction and dried to form a first extension film. After the laminate mother plate with the first extension film is pressed along the z direction, it is cut into multiple slender rod-shaped laminate blocks along the y direction.

[0020] Nickel metal paste is coated on both sides of the laminated block along the y direction and dried to form a second extension film. The laminated block is then sequentially cut along the x direction to obtain multiple laminates.

[0021] The laminated body is subjected to debinding and sintering processes to obtain a ceramic body containing an inner electrode. The ceramic body is then electroplated to form an outer electrode, resulting in a multilayer ceramic capacitor.

[0022] In some embodiments, the adhesive removal process includes: heating the laminate to 250°C-350°C in air and holding it at that temperature for 0.5 hours-3 hours to remove the adhesive contained in the laminate, or heating the laminate to 350°C-600°C in nitrogen and holding it at that temperature for 2 hours-6 hours to remove the adhesive contained in the laminate; the sintering process includes: heating the laminate to 1100°C-1300°C and holding it at that temperature for 0.5 hours-3 hours in a reducing atmosphere formed by a humidified mixture of nitrogen and hydrogen to sinter the laminate into a dense structure, thereby obtaining the ceramic body containing the internal electrode.

[0023] This invention provides a multilayer ceramic capacitor and its preparation method. Compared with the prior art, its advantages are as follows:

[0024] The external electrode comprises a main body, two first extensions, and two second extensions. The two first extensions extend along the z-direction from both sides of the main body and cover the two second side surfaces respectively. The sides of the first extensions along the y-direction are spaced apart from the edges of the second side surfaces along the y-direction. The two second extensions extend along the y-direction from both sides of the main body and cover the two first side surfaces respectively. The sides of the second extensions along the z-direction are spaced apart from the edges of the first side surfaces along the z-direction. This design prevents the external electrode from forming sharp corners on the edges of the ceramic body, thereby preventing breakdown due to charge concentration and improving the dielectric strength of the multilayer ceramic capacitor. Attached Figure Description

[0025] Figure 1 This is a diagram of the current axial structure of a multilayer ceramic capacitor.

[0026] Figure 2 This is an axial view of a multilayer ceramic capacitor according to some embodiments of the present invention.

[0027] Figure 3 This is an axial view of the ceramic body of a multilayer ceramic capacitor according to some embodiments of the present invention.

[0028] Figure 4 This is a cross-sectional view of the multilayer ceramic capacitor along the z-direction according to an embodiment of the present invention.

[0029] Figure 5 This is a cross-sectional view of the first internal electrode of the multilayer ceramic capacitor along the x-direction, according to an embodiment of the present invention.

[0030] Figure 6 This is a cross-sectional view of the second inner electrode of the multilayer ceramic capacitor along the x-direction, according to an embodiment of the present invention.

[0031] Figure 7 This is a cross-sectional view of the third inner electrode of a multilayer ceramic capacitor along the x-direction, according to an embodiment of the present invention.

[0032] Figure 8 This is a cross-sectional view of the fourth inner electrode of a multilayer ceramic capacitor along the x-direction, according to an embodiment of the present invention.

[0033] Figure 9 This is a printed pattern for forming the inner electrode film of the first inner electrode and the second inner electrode in a method for preparing a multilayer ceramic capacitor according to other embodiments of the present invention.

[0034] Figure 10 This is a printed pattern for forming the inner electrode film of the third inner electrode and the fourth inner electrode in a method for preparing a multilayer ceramic capacitor according to other embodiments of the present invention.

[0035] Figure 11 This is an axonometric view of the mother plate of the multilayer ceramic capacitor in some other embodiments of the present invention.

[0036] Figure 12 This is a schematic diagram of forming a first extension film on a laminate mother plate in a method for preparing a multilayer ceramic capacitor according to other embodiments of the present invention.

[0037] Figure 13 This is a schematic diagram illustrating the cutting of a multilayer ceramic capacitor mother plate into multilayer blocks in a method for preparing a multilayer ceramic capacitor according to other embodiments of the present invention.

[0038] Figure 14 This is an axial enlarged schematic diagram of the stacked block in the fabrication method of a multilayer ceramic capacitor according to other embodiments of the present invention.

[0039] Figure 15 This is an enlarged schematic diagram of the formation of a second extension thin film on a multilayer ceramic capacitor in a method for preparing a multilayer ceramic capacitor according to other embodiments of the present invention.

[0040] Figure 16 This is an enlarged schematic diagram of cutting a multilayer ceramic capacitor block into a multilayer body in a method for preparing a multilayer ceramic capacitor according to other embodiments of the present invention.

[0041] In the figure: 1. Ceramic body; 11. First end face; 12. Second end face; 13. First side face; 14. Second side face; 15. Edge; 2. Inner electrode; 21. First inner electrode; 22. Second inner electrode; 23. Third inner electrode; 24. Fourth inner electrode; 3. Outer electrode; 31. Main body; 32. First extension; 33. Second extension; 4. First extension film; 5. Stacked block; 6. Second extension film; 1'. First ceramic body; 2'. Fifth inner electrode; 3'. First outer electrode. Detailed Implementation

[0042] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0043] It should be understood that in the description of this application, the terms "upper," "lower," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used solely for the convenience of describing this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. That is, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, unless otherwise stated, "a plurality of" means two or more.

[0044] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0045] like Figure 2-8 As shown, some embodiments of the present invention provide a multilayer ceramic capacitor having x-direction, y-direction and z-direction, which includes a ceramic body 1, an inner electrode 2 and two outer electrodes 3.

[0046] The ceramic body 1 has a first end face 11 and a second end face 12 arranged along the x-direction, two first side faces 13 arranged along the y-direction, and two second side faces 14 arranged along the z-direction. The two first side faces 13 and the two second side faces 14 enclose and form four edges 15. Specifically, the ceramic body 1 is in the shape of a cuboid.

[0047] The inner electrode 2 includes a first inner electrode 21 and a second inner electrode 22 staggered along the z-direction within the ceramic body 1. One end of the first inner electrode 21 extends out of the first end face 11 of the ceramic body 1, and one end of the second inner electrode 22 extends out of the second end face 12 of the ceramic body 1. The inner electrodes 2 are sheet-like, for example, having 100-900 electrodes to increase the capacitance of the multilayer ceramic capacitor. Adjacent inner electrodes 2 are separated by ceramic material. Capacitance can be generated by sandwiching ceramic material between adjacent inner electrodes 2. There is a gap between the inner electrodes 2 and both second side faces 14. The thickness of the inner electrode 2 can be 0.5μm-1μm. If the thickness of the inner electrode 2 is too small, the continuity of the inner electrode 2 is poor, which is not conducive to increasing the capacitance; if the thickness of the inner electrode 2 is too large, it is not conducive to reducing the thickness of the multilayer ceramic capacitor. The material of the inner electrode 2 is nickel. Specifically, the first inner electrode 21 and the second inner electrode 22 are located at the middle position of the ceramic body 1 along the z-direction.

[0048] The external electrode 3 includes a main body 31, two first extensions 32, and two second extensions 33. The main bodies 31 of the two external electrodes 3 are respectively disposed on the first end face 11 and the second end face 12, and are electrically connected to the first inner electrode 21 and the second inner electrode 22 respectively. The two first extensions 32 extend outward from both sides of the main body 31 in the z-direction, and each of the two first extensions 32 corresponds to one of the two second side faces 14. The side edges of the first extensions 32 in the y-direction are spaced apart from the edges 15 of the second side faces 14 in the y-direction. The two second extensions 33 extend outward from both sides of the main body 31 in the y-direction, and each of the two second extensions 33 corresponds to one of the two first side faces 13. The side edges of the second extensions 33 in the z-direction are spaced apart from the edges 15 of the first side faces in the z-direction. In this way, when any one of the two first side faces 13 and the two second side faces 14 is used as a mounting surface, the multilayer ceramic capacitor can be easily and firmly soldered onto the circuit board. The first extension 32 is spaced from the edges 15 of the two first side surfaces 13, and the second extension 33 is spaced from the edges 15 of the two second side surfaces 14. This prevents the external electrode 3 from forming sharp corners on the four edges 15, prevents breakdown due to charge concentration, and improves the dielectric strength of the multilayer ceramic capacitor.

[0049] Specifically, the first extension 32 and the second extension 33 are generally square in shape, with one end extending to the edge of the first end face 11 and connecting with the main body 31, and the other end extending a distance towards the second end face 12 with rounded corners. This configuration gives the first extension 32 and the second extension 33 a smooth profile, preventing breakdown caused by tip discharge and improving the dielectric strength of the multilayer ceramic capacitor. Furthermore, since the first extension 32 and the second extension 33 are connected to the main body 31, even if the main body 31 has sharp corners or protruding shapes, charges tend to accumulate in the smooth-profiled first extension 32 and the second extension 33 rather than in the sharp corners or protruding parts of the main body 31, thus preventing breakdown caused by tip discharge.

[0050] Based on the above structural design, the external electrode 3 will not form sharp corners on the edge 15 of the ceramic body 1, thereby preventing breakdown due to charge concentration and improving the dielectric strength of the multilayer ceramic capacitor.

[0051] like Figure 2 As shown, in some embodiments, the four corners of the main body 31 have notches, and the four edges 15 of the ceramic body 1 are located in the notches one by one. This facilitates the provision of the first extension 32 and the second extension 33, and makes the first extension 32 and the two second extensions 33 spaced apart from the edges 15.

[0052] like Figure 5 and 6As shown, in some embodiments, one end of the first inner electrode 21 extends out to two first side surfaces 13, and the second extension 33 of one of the outer electrodes 3 covers the portion of the first inner electrode 21 extending out to the first side surface 13. One end of the second inner electrode 22 extends out to the two first side surfaces 13, and the second extension 33 of the other outer electrode 3 covers the portion of the second inner electrode 22 extending out to the first side surface 13. Thus, the structural arrangement of the first inner electrode 21 and the second inner electrode 22 ensures electrical conductivity between the outer electrode 3 and the inner electrode 2. Preferably, one end of the first inner electrode 21 extending to the first end face 11 is connected to one end of the first inner electrode 21 extending to the two first side surfaces 13, so that when the metal layer of the main body 31 is formed by electroplating, the main body 31 is connected to the two second extensions 33, ensuring electrical conductivity between the main body 31 and the second extensions 33.

[0053] like Figure 4 As shown, in some embodiments, the inner electrode 2 includes a third inner electrode 23 and a fourth inner electrode 24 staggered along the z-direction within the ceramic body 1. The third inner electrode 23 is located on the side of the first inner electrode 21 away from the second inner electrode 22, and the fourth inner electrode 24 is located on the side of the second inner electrode 22 away from the first inner electrode 21. One end of the third inner electrode 23 extends out of the first end face 11 of the ceramic body 1 and is electrically connected to the main body 31 of one of the outer electrodes 3. One end of the fourth inner electrode 24 extends out of the second end face 12 of the ceramic body 1 and is electrically connected to the main body 31 of the other outer electrode 3. Thus, the arrangement of the third inner electrode 23 and the fourth inner electrode 24 further improves the conductivity between the outer electrode 3 and the inner electrode 2, and the staggered arrangement of the third inner electrode 23 and the fourth inner electrode 24 in the ceramic body 1 can increase the capacitance of the multilayer ceramic capacitor. The third inner electrode 23 is spaced apart from the two first side surfaces 13, and the fourth inner electrode 24 is spaced apart from the two first side surfaces 13. This ensures that a gap is formed between the second extension 33 and the edge 15 when the metal layer of the outer electrode 3 is formed by electroplating, and at the same time facilitates the formation of notches at the four corners of the main body 31.

[0054] For the aforementioned inner electrode 2 structure, in order to facilitate the formation of a metal layer on the first end face 11 and the second end face 12 through electroplating and to improve the capacitance of the multilayer ceramic capacitor, the distance between adjacent inner electrodes 2 is preferably 1.5 μm or less. Furthermore, to prevent charge concentration, the corners of the rectangular inner electrode 2 are rounded.

[0055] In some embodiments, the main body 31 includes a nickel layer and a tin layer disposed from the inside out.

[0056] In some embodiments, the main body 31 includes a copper layer, a nickel layer, and a tin layer disposed from the inside out.

[0057] In some embodiments, both the first extension 32 and the second extension 33 include a nickel layer and a tin layer disposed from the inside out.

[0058] In some embodiments, the first extension 32 and the second extension 33 each include a first nickel layer, a copper layer, a second nickel layer, and a tin layer.

[0059] For the external electrode 3 structure described above, the tin layer can improve the solderability of the multilayer ceramic capacitor.

[0060] like Figure 9-16 As shown, another embodiment of the present invention provides a method for preparing a multilayer ceramic capacitor, which includes the following steps:

[0061] S1. Ceramic powder, binder, and organic solvent are mixed to form a ceramic slurry, and the ceramic slurry is cast to obtain a ceramic film. The ceramic powder is made of materials such as barium titanate and calcium zirconate. For example, the thickness of the ceramic film is 1μm-2μm. If the thickness of the ceramic film is too small, the reliability of the multilayer ceramic capacitor will be poor. If the thickness of the ceramic film is too large, it is not conducive to improving the capacitance of the multilayer ceramic capacitor. Furthermore, the spacing between the inner electrodes exposed on the first end face 11 and the second end face 12 is large, making it difficult to form the bottom metal of the main body 31 by electroplating.

[0062] S2. Print nickel metal paste onto the ceramic thin film and dry it to form the internal electrode thin film. (Refer to...) Figure 9 and Figure 10 As shown, Figure 9 This is a printed pattern for forming the inner electrode thin film of the first inner electrode 21 and the second inner electrode 22. Figure 10 This is a printed pattern for forming the inner electrode films of the third inner electrode 23 and the fourth inner electrode 24.

[0063] S3. Reference Figure 11 As shown, multiple ceramic films with internal electrode films are stacked along the z-direction to form a laminated structure. The ceramic film obtained in step S1 is then covered on both sides of the laminated structure along the z-direction to obtain a laminated body mother plate. Covering the laminated structure on both sides along the z-direction with the ceramic film obtained in step S1 is to cover the internal electrode 2 and protect it from moisture intrusion and mechanical damage. When stacking multiple ceramic films with internal electrode films along the z-direction, adjacent ceramic films with internal electrode films are staggered by an appropriate distance in the x-direction so that after cutting the laminated body mother plate, the first internal electrode 21, the second internal electrode 22, the third internal electrode 23, and the fourth internal electrode 24 are formed.

[0064] S4, Reference Figure 12 As shown, nickel metal paste is printed on both sides of the laminate motherboard along the z-direction and dried to form the first extension film 4.

[0065] S5. Reference Figure 13 and Figure 14 As shown, after the laminated mother plate with the first extended film 4 is pressed along the z-direction, it is sequentially cut along the y-direction. Figure 13 The dashed lines in the figure indicate the cutting position) are used to form multiple slender rod-shaped stacked blocks 5. In step S5, the two cut surfaces formed by cutting and facing each other in the y direction are the first cut surface P1, which correspond to the two first side surfaces 13 of the ceramic body 1 respectively. The first inner electrode 21 and the second inner electrode 22 are exposed in the first cut surface P1, while the third inner electrode 23 and the fourth inner electrode 24 are not exposed in the first cut surface P1.

[0066] S6, Reference Figure 15 As shown, nickel metal paste is coated and dried on both sides of the laminated block 5 along the y-direction to form the second extension film 6. Specifically, nickel metal paste is coated on the first cut surface P1 of the laminated block 5. Since one laminated block 5 corresponds to multiple ceramic bodies 1, the operation of coating the laminated block 5 with nickel metal paste is relatively convenient and suitable for mass production. The second extension film 6 is spaced from both sides of the laminated block 5 along the z-direction to create a gap between the second extension 33 and the edge 15. Preferably, the second extension film 6 completely covers the first inner electrode 21 and the second inner electrode 22 exposed on the first cut surface P1.

[0067] S7, Reference Figure 16 As shown, the stacked blocks are sequentially cut along the x-direction. Figure 16 (The dashed lines in the diagram indicate the cutting positions), resulting in multiple laminated bodies. The laminated bodies are rectangular parallelepipeds. In step S7, the two opposing second cut surfaces formed in the x-direction are called second cut surfaces P2, corresponding to the first end face 11 and the second end face 12 of the ceramic body 1, respectively. The inner electrode 2 is exposed on the second cut surface P2. Specifically, the first inner electrode 21 and the third inner electrode 23 are exposed on one of the second cut surfaces P2 of the laminated body, and the second inner electrode 22 and the fourth inner electrode 24 are exposed on the other second cut surface P2. During the cutting in step S7, the first extension film 4 and the second extension film 6 are cut centered, allowing the first extension film 4 and the second extension film 6 to extend to the edge of the first end face 11, that is, allowing one end of the first extension 32 and the second extension 33 to extend to the edge of the first end face 11 so that they can connect with the main body 31.

[0068] S8. The laminate is subjected to a binder removal and sintering process to obtain a ceramic body 1 containing the internal electrode 2. Specifically, the binder removal process includes: heating the laminate to 250℃-350℃ in air and holding it at that temperature for 0.5 hours to 3 hours to remove the binder contained in the laminate, or heating the laminate to 350℃-600℃ in nitrogen and holding it at that temperature for 2 hours to 6 hours to remove the binder contained in the laminate. The sintering process includes: heating the laminate to 1100℃-1300℃ and holding it at that temperature for 0.5 hours to 3 hours in a reducing atmosphere formed by a humidified mixture of nitrogen and hydrogen (the volume of hydrogen is 0.1%-3% of the volume of nitrogen) to sinter the laminate until it is dense, thereby obtaining a ceramic body 1 containing the internal electrode 2. The inner electrode film is sintered to form the inner electrode 2, the first extension film 4 is sintered to form the nickel layer of the first extension 32, and the second extension film 6 is sintered to form the nickel layer of the second extension 33.

[0069] S9. Electroplating is performed on the ceramic body 1 to form the external electrode 3, thereby obtaining a multilayer ceramic capacitor. Specifically, the ceramic body 1 is first electroplated with nickel to form a nickel layer of the main body 31 on the first end face 11 and the second end face 12. At the same time, the thickness and continuity of the nickel layer of the first extension 32 and the nickel layer of the second extension 33 are increased. Then, the ceramic body 1 is electroplated with tin to form the external electrode 3. The external electrode 3 includes a main body 31, a first extension 32 and a second extension 33, which are two metal structures consisting of a nickel layer and a tin layer from the inside to the outside. Furthermore, the ceramic body 1 can be electroplated with copper to form a copper layer of the main body 31 on the first end face 11 and the second end face 12. Simultaneously, copper layers are formed on the nickel layers of the first extension 32 and the second extension 33. Then, the ceramic body 1 is electroplated with nickel to form nickel layers on the copper layers of the main body 31, the first extension 32, and the second extension 33. Finally, the ceramic body 1 is electroplated with tin to form the external electrode 3. The external electrode 3 includes a three-layer metal structure of the main body 31 (copper, nickel, and tin layers from the inside out) and a four-layer metal structure of the first extension 32 and the second extension 33 (nickel, copper, nickel, and tin layers from the inside out). During electroplating to form the bottom metal of the main body 31, the metal easily precipitates and grows on the end of the inner electrode 2 exposed on the first end face 11 and the second end face 12, and bridges with each other to form a continuous and uniform metal plating layer. Through the electroplating process in step S9, the surface metal of the external electrode 3 becomes a continuous and uniform tin layer, which can improve the solderability of the multilayer ceramic capacitor.

[0070] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A multilayer ceramic capacitor having x-direction, y-direction and z-direction, characterized in that, include: The ceramic body has a first end face and a second end face arranged along the x direction, two first side faces arranged along the y direction, and two second side faces arranged along the z direction, wherein the two first side faces and the two second side faces enclose and form four edges. The inner electrode includes a first inner electrode and a second inner electrode that are alternately disposed in the ceramic body along the z-direction, one end of the first inner electrode extending out of the first end face of the ceramic body, and one end of the second inner electrode extending out of the second end face of the ceramic body. as well as Two external electrodes are provided, each comprising a main body, two first extensions, and two second extensions. The main bodies of the two external electrodes are respectively disposed on the first end face and the second end face, and are electrically connected to the first inner electrode and the second inner electrode, respectively. The two first extensions extend outward from both sides of the main body along the z-direction, and each of the two first extensions corresponds to and covers one of the two second side faces. The side edges of the first extensions along the y-direction are spaced apart from the edges of the second side faces along the y-direction. The two second extensions extend outward from both sides of the main body along the y-direction, and each of the two second extensions corresponds to and covers one of the two first side faces. The side edges of the second extensions along the z-direction are spaced apart from the edges of the first side faces along the z-direction.

2. The multilayer ceramic capacitor according to claim 1, characterized in that, The main body has notches at all four corners, and the four edges of the ceramic body are located in the notches one by one.

3. The multilayer ceramic capacitor according to claim 1, characterized in that, One end of the first inner electrode extends out of the first side surface, and the second extension of one of the outer electrodes covers the portion of the first inner electrode that extends out of the first side surface. One end of the second inner electrode extends out of the first side surface, and the second extension of the other outer electrode covers the portion of the second inner electrode that extends out of the first side surface.

4. The multilayer ceramic capacitor according to claim 1, characterized in that, The inner electrode includes a third inner electrode and a fourth inner electrode that are alternately disposed in the ceramic body along the z-direction. The third inner electrode is located on the side of the first inner electrode away from the second inner electrode, and the fourth inner electrode is located on the side of the second inner electrode away from the first inner electrode. One end of the third inner electrode extends out of the first end face of the ceramic body and is electrically connected to the main body of one of the outer electrodes. One end of the fourth inner electrode extends out of the second end face of the ceramic body and is electrically connected to the main body of the other outer electrode. The third inner electrode is spaced apart from the two first side faces, and the fourth inner electrode is spaced apart from the two first side faces.

5. The multilayer ceramic capacitor according to claim 1, characterized in that, The main body includes a nickel layer and a tin layer disposed from the inside out.

6. The multilayer ceramic capacitor according to claim 1, characterized in that, The main body includes a copper layer, a nickel layer, and a tin layer arranged from the inside out.

7. The multilayer ceramic capacitor according to claim 1, characterized in that, Both the first extension and the second extension include a nickel layer and a tin layer disposed from the inside out.

8. The multilayer ceramic capacitor according to claim 1, characterized in that, Both the first extension and the second extension include a first nickel layer, a copper layer, a second nickel layer, and a tin layer.

9. A method for preparing a multilayer ceramic capacitor as described in any one of claims 1-8, characterized in that, include: Ceramic powder, binder and organic solvent are mixed to form a ceramic slurry, and the ceramic slurry is cast to obtain a ceramic film; Nickel metal paste is printed on the ceramic film and dried to form an internal electrode film; Multiple ceramic films having internal electrode films are stacked along the z-direction to form a stacked structure. The ceramic films are then covered on both sides of the stacked structure along the z-direction to obtain a stacked body mother plate. Nickel metal paste is printed on both sides of the laminate mother plate along the z direction and dried to form a first extension film. After the laminate mother plate with the first extension film is pressed along the z direction, it is cut into multiple slender rod-shaped laminate blocks along the y direction. Nickel metal paste is coated on both sides of the laminated block along the y direction and dried to form a second extension film. The laminated block is then sequentially cut along the x direction to obtain multiple laminates. The laminated body is subjected to debinding and sintering processes to obtain a ceramic body containing an inner electrode. The ceramic body is then electroplated to form an outer electrode, resulting in a multilayer ceramic capacitor.

10. The method for preparing a multilayer ceramic capacitor according to claim 9, characterized in that, The adhesive removal process includes: heating the laminate to 250℃-350℃ in air and holding it at that temperature for 0.5 hours-3 hours to remove the adhesive contained in the laminate; or heating the laminate to 350℃-600℃ in nitrogen and holding it at that temperature for 2 hours-6 hours to remove the adhesive contained in the laminate. The sintering process includes: heating the laminate to 1100℃-1300℃ in a reducing atmosphere formed by a humidified mixture of nitrogen and hydrogen and holding it at that temperature for 0.5 hours-3 hours to sinter the laminate until it is dense, thereby obtaining the ceramic body containing the internal electrode.

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