Multilayer ceramic capacitor and preparation method thereof

Abstract

The invention relates to the technical field of ceramic capacitors, and particularly discloses a multilayer ceramic capacitor and a preparation method thereof, and the multilayer ceramic capacitor comprises a ceramic body which is provided with a first end face, a second end face, two first side faces and two second side faces; the inner electrode comprises a first inner electrode and a second inner electrode, one end of the first inner electrode extends out of the first end face of the ceramic body, and one end of the second inner electrode extends out of the second end face of the ceramic body; each outer electrode comprises a main body part, two first extension parts and two second extension parts, the two outer electrodes are electrically connected with the first inner electrode and the second inner electrode, the two first extension parts extend out of the two sides of the main body part in the z direction, and the two second extension parts extend out of the two sides of the main body part in the y direction. According to the multilayer ceramic capacitor and the preparation method thereof, sharp corners are prevented from being formed on the outer electrodes, so that breakdown caused by charge concentration is prevented, and the dielectric strength of the multilayer ceramic capacitor is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic capacitors, and in particular to a multilayer ceramic capacitor and a preparation method thereof. Background Art

[0002] The external electrodes of current multilayer ceramic capacitors are generally formed by dip coating process, such as Figure 1 As shown, the end of the first external electrode 3' is formed as a sharp corner A on the edge of the first ceramic body 1' of the multilayer ceramic capacitor, and charges are easily accumulated on the sharp corner A, resulting in a highly concentrated electric field area 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 area is prone to breakdown, resulting in a low dielectric strength of the multilayer ceramic capacitor. The technical solution of the present application can solve the above problems through structural improvements. Summary of the invention

[0003] The object of the present invention is to provide a multilayer ceramic capacitor which 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] In order to achieve the above-mentioned object, the present invention provides a multilayer ceramic capacitor in a first aspect, having an x-direction, a y-direction and a z-direction, comprising:

[0005] A ceramic body having 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 four edges;

[0006] The inner electrode comprises a first inner electrode and a second inner electrode which are staggered in the ceramic body along the z direction, wherein one end of the first inner electrode extends out of a first end surface of the ceramic body, and one end of the second inner electrode extends out of a second end surface of the ceramic body; and

[0007] Two outer electrodes, the outer electrodes include a main body, two first extensions and two second extensions, the main bodies of the two outer electrodes are respectively arranged on the first end surface and the second end surface, and are respectively electrically connected to the first inner electrode and the second inner electrode, the two first extensions extend out of the two sides of the main body along the z direction, the two first extensions cover the two second side surfaces one by one, the side edges 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 out of the two sides of the main body along the y direction, the two second extensions cover the two first side surfaces one by one, the side edges of the second extensions along the z direction are spaced apart from the edges of the first side surfaces 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 in a one-to-one correspondence.

[0009] In some embodiments, one end of the first inner electrode extends out of the first side surface, wherein the second extension portion of one of the outer electrodes covers a portion of the first inner electrode extending out of the first side surface, and one end of the second inner electrode extends out of the first side surface, and the second extension portion of another of the outer electrodes covers a 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 which are staggered in the ceramic body along the z direction, the third inner electrode is located on a side of the first inner electrode away from the second inner electrode, the fourth inner electrode is located on a 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 surface 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 surface 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 surfaces, and the fourth inner electrode is spaced apart from the two first side surfaces.

[0011] In some embodiments, the main body includes a nickel layer and a tin layer disposed from the inside to the outside.

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

[0013] In some embodiments, the first extension portion and the second extension portion each include a nickel layer and a tin layer disposed from the inside to the outside.

[0014] In some embodiments, the first extension portion and the second extension portion each 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] Mixing ceramic powder, a binder and an organic solvent to form a ceramic slurry, and casting the ceramic slurry to obtain a ceramic film;

[0017] Printing nickel metal slurry on the ceramic film and drying it to form an internal electrode film;

[0018] stacking a plurality of the ceramic films formed with the internal electrode films in the z direction to form a stacked structure, and covering the ceramic films on both sides of the stacked structure in the z direction to obtain a stacked mother board;

[0019] Printing nickel metal paste on both sides of the laminate mother board along the z direction and drying it to form a first extension film, pressing the laminate mother board with the first extension film along the z direction, and then cutting it into a plurality of elongated rod-shaped laminate blocks in sequence along the y direction;

[0020] Coating nickel metal slurry on both sides of the stacked body block along the y direction and drying the slurry to form a second extension film, and sequentially cutting the stacked body block along the x direction to obtain a plurality of stacked bodies;

[0021] The laminate is subjected to a debinding and sintering process to obtain a ceramic body including an inner electrode, and the ceramic body is subjected to an electroplating process to form an outer electrode to obtain a multilayer ceramic capacitor.

[0022] In some embodiments, the debinding process includes: heating the stack to 250°C-350°C in air and keeping it warm for 0.5 hour-3 hours to remove the binder contained in the stack, or heating the stack to 350°C-600°C in nitrogen and keeping it warm for 2 hours-6 hours to remove the binder contained in the stack; the sintering process includes: in a reducing atmosphere formed by a mixed gas of humidified nitrogen and hydrogen, heating the stack to 1100°C-1300°C and keeping it warm for 0.5 hour-3 hours to sinter the stack to be dense, so as to obtain the ceramic body containing the inner electrode.

[0023] The present invention provides a multilayer ceramic capacitor and a method for preparing the same. Compared with the prior art, the present invention has the following beneficial effects:

[0024] The external electrode includes a main body, two first extensions and two second extensions, the two first extensions extend out of both sides of the main body along the z direction, the two first extensions cover the two second side surfaces one by one, 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 out of both sides of the main body along the y direction, the two second extensions cover the two first side surfaces one by one, 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, so that the external electrode will not form 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. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0026] Figure 2 1 is an axial structural diagram of a multilayer ceramic capacitor according to some embodiments of the present invention.

[0027] Figure 3 1 is an axial structural diagram of a ceramic body of a multilayer ceramic capacitor according to some embodiments of the present invention.

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

[0029] Figure 5 FIG. 4 is a cross-sectional structure of a first inner electrode of a multilayer ceramic capacitor along the x direction according to an embodiment of the present invention.

[0030] Figure 6 FIG. 4 is a cross-sectional view of a second inner electrode of a multilayer ceramic capacitor according to an embodiment of the present invention along the x direction.

[0031] Figure 7 FIG. 4 is a cross-sectional view of a third inner electrode of a multilayer ceramic capacitor according to an embodiment of the present invention along the x direction.

[0032] Figure 8 FIG. 4 is a cross-sectional structure of a fourth inner electrode of a multilayer ceramic capacitor along the x direction according to an embodiment of the present invention.

[0033] Fig. 9 The printed patterns are for forming the first internal electrode and the second internal electrode in the method for preparing the multilayer ceramic capacitor according to some other embodiments of the present invention.

[0034] Fig.10 The printed patterns are for forming the third internal electrode and the fourth internal electrode in the method for preparing the multilayer ceramic capacitor according to some other embodiments of the present invention.

[0035] Fig.11 It is an isometric view of a laminate mother board in a method for preparing a multilayer ceramic capacitor according to other embodiments of the present invention.

[0036] Fig.12 Schematic diagram of forming a first extension film on a laminate mother board in a method for preparing a multilayer ceramic capacitor according to some other embodiments of the present invention.

[0037] Fig.13 Schematic diagram of cutting a laminate mother board into laminate blocks in a method for preparing a multilayer ceramic capacitor according to some other embodiments of the present invention.

[0038] Fig.14 It is an axially enlarged schematic diagram of a stacked body block in a method for preparing a multilayer ceramic capacitor according to some other embodiments of the present invention.

[0039] Fig.15 It is an enlarged schematic diagram of forming a second extension film on a laminated body block in a method for preparing a multilayer ceramic capacitor according to some other embodiments of the present invention.

[0040] Fig.16 It is an enlarged schematic diagram of cutting a laminate block into laminates in a method for preparing a multilayer ceramic capacitor according to some 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 part; 33. second extension part; 4. first extension part film; 5. stacked body block; 6. second extension part film; 1', first ceramic body; 2', fifth inner electrode; 3', first outer electrode. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments.

[0043] It should be understood that, in the description of the present application, the terms "upper", "lower", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. The terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated, that is, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In addition, unless otherwise specified, "multiple" means two or more.

[0044] In addition, the technical features involved in the different embodiments of the present 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 an x-direction, a y-direction and a z-direction, and comprising 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 four edges 15. Specifically, the ceramic body 1 is in a rectangular parallelepiped shape.

[0047] The inner electrode 2 includes a first inner electrode 21 and a second inner electrode 22 which are staggered in the ceramic body 1 along the z direction, one end of the first inner electrode 21 extends out of the first end surface 11 of the ceramic body 1, and one end of the second inner electrode 22 extends out of the second end surface 12 of the ceramic body 1. The inner electrode 2 is in the form of a thin sheet, for example, 100-900, so as 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 electrode 2 and both second side surfaces 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 in the middle position of the ceramic body 1 along the z direction.

[0048] The outer electrode 3 includes a main body 31, two first extensions 32 and two second extensions 33. The main bodies 31 of the two outer electrodes 3 are respectively arranged on the first end face 11 and the second end face 12, and are respectively electrically connected to the first inner electrode 21 and the second inner electrode 22. The two first extensions 32 extend out of both sides of the main body 31 along the z direction. The two first extensions 32 cover the two second side faces 14 one by one. The sides of the first extensions 32 along the y direction are arranged at intervals with the edges 15 of the second side faces 14 along the y direction. The two second extensions 33 extend out of both sides of the main body 31 along the y direction. The two second extensions 33 cover the two first side faces 13 one by one. The sides of the second extensions 33 along the z direction are arranged at intervals with the edges 15 of the first side faces along 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 the mounting surface, the multilayer ceramic capacitor can be conveniently and firmly soldered on the circuit board. There is a gap between the first extension portion 32 and the edges 15 of the two first side surfaces 13, and there is a gap between the second extension portion 33 and the edges 15 of the two second side surfaces 14, thereby avoiding the external electrode 3 from forming sharp corners on the four edges 15, preventing breakdown due to charge concentration, and improving the dielectric strength of the multilayer ceramic capacitor.

[0049] Specifically, the first extension portion 32 and the second extension portion 33 are roughly square, one end of which extends to the edge of the first end face 11 and is connected to the main body 31, and the other end thereof extends a distance toward the second end face 12 and the end corner is rounded. By so configuring, the first extension portion 32 and the second extension portion 33 have a smooth profile, which can prevent breakdown caused by tip discharge and improve the dielectric strength of the multilayer ceramic capacitor. In addition, the first extension portion 32 and the second extension portion 33 are connected to the main body 31, so that even if the main body 31 has a sharp or protruding shape, the charge tends to gather in the first extension portion 32 and the second extension portion 33 with a smooth profile and is not easy to gather in the sharp corners or protruding parts of the main body 31, which can prevent breakdown caused by tip discharge.

[0050] Based on the above structural arrangement, the external electrode 3 will not form a sharp corner 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. In this way, it is convenient to set the first extension part 32 and the second extension part 33, and the first extension part 32 and the two second extension parts 33 are spaced from the edges 15.

[0052] like Figure 5 and 6As shown, in some embodiments, one end of the first inner electrode 21 extends out of two first side surfaces 13, and the second extension portion 33 of one outer electrode 3 covers the portion where the first inner electrode 21 extends out of the first side surface 13, and one end of the second inner electrode 22 extends out of two first side surfaces 13, and the second extension portion 33 of another outer electrode 3 covers the portion where the second inner electrode 22 extends out of the first side surface 13. In this way, the outer electrode 3 and the inner electrode 2 are electrically conductive through the structural arrangement of the first inner electrode 21 and the second inner electrode 22. Preferably, one end of the first inner electrode 21 extending to the first end surface 11 is connected to one end of the first inner electrode 21 extending to the two first side surfaces 13, respectively, 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 extension portions 33, so that the main body 31 and the second extension portions 33 are electrically conductive.

[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 in the ceramic body 1 along the z direction, the third inner electrode 23 is located on the side of the first inner electrode 21 away from the second inner electrode 22, 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 surface 11 of the ceramic body 1 and is electrically connected to the main body 31 of one of the outer electrodes 3, and one end of the fourth inner electrode 24 extends out of the second end surface 12 of the ceramic body 1 and is electrically connected to the main body 31 of the other outer electrode 3. In this way, by disposing the third inner electrode 23 and the fourth inner electrode 24, the degree of electrical conduction between the outer electrode 3 and the inner electrode 2 is further improved, and the third inner electrode 23 and the fourth inner electrode 24 are staggered in the ceramic body 1, which can improve 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 when the metal layer of the outer electrode 3 is formed by electroplating, a gap is formed between the second extension portion 33 and the edge 15 , and facilitates the formation of notches at the four corners of the main body 31 .

[0054] For the above-mentioned internal electrode 2 structure, in order to facilitate the formation of a metal layer by electroplating on the first end face 11 and the second end face 12 and to increase the capacitance of the multilayer ceramic capacitor, the distance between adjacent internal electrodes 2 is preferably less than 1.5 μm. In addition, in order to prevent charge concentration, the corners of the rectangular internal electrode 2 are set to be rounded.

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

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

[0057] In some embodiments, the first extension portion 32 and the second extension portion 33 each include a nickel layer and a tin layer disposed from the inside to the outside.

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

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

[0060] like Figure 9-16 As shown, some other embodiments of the present invention provide a method for preparing a multilayer ceramic capacitor, comprising the following steps:

[0061] S1. Ceramic powder, a binder and an organic solvent are mixed to form a ceramic slurry, and the ceramic slurry is cast to obtain a ceramic film, wherein the material of the ceramic powder is barium titanate, calcium zirconate, etc. Exemplarily, the thickness of the ceramic film is 1 μm-2 μm. 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, and the spacing between the inner electrodes exposed at the first end face 11 and the second end face 12 is large, and it is difficult to form the bottom metal of the main body 31 by electroplating.

[0062] S2, printing nickel metal paste on the ceramic film and drying it to form an internal electrode film. Fig. 9 and Fig.10 As shown, Fig. 9 is a printing pattern of an internal electrode film for forming the first internal electrode 21 and the second internal electrode 22, Fig.10 is a printing pattern of an internal electrode film for forming the third internal electrode 23 and the fourth internal electrode 24 .

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

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

[0065] S5. Reference Fig.13 and Fig.14 As shown, after the laminated mother board with the first extension film 4 is pressed in the z direction, it is cut in sequence in the y direction ( Fig.13 The dotted lines in the figure indicate the cutting positions) are formed into a plurality of elongated rod-shaped stacked body blocks 5. In step S5, two cut surfaces formed by cutting in the y direction are first cut surfaces P1, which correspond to the two first side surfaces 13 of the ceramic body 1, respectively. The first internal electrode 21 and the second internal electrode 22 are exposed at the first cut surfaces P1, and the third internal electrode 23 and the fourth internal electrode 24 are not exposed at the first cut surfaces P1.

[0066] S6. Reference Fig.15 As shown, nickel metal slurry is coated on both side surfaces of the stacked body block 5 along the y direction and dried to form the second extension film 6. Specifically, nickel metal slurry is coated on the first cut surface P1 of the stacked body block 5. Since one stacked body block 5 corresponds to multiple ceramic bodies 1, the operation of coating the stacked body block 5 with nickel metal slurry is relatively convenient and suitable for mass production. The second extension film 6 is spaced apart from both side surfaces of the stacked body block 5 along the z direction so as to form a space between the second extension portion 33 and the edge 15. Preferably, the second extension film 6 completely covers the first internal electrode 21 and the second internal electrode 22 exposed at the first cut surface P1.

[0067] S7, reference Fig.16 As shown, the stacked blocks are cut in sequence along the x direction ( Fig.16 The dotted line in the figure indicates the cutting position), and a plurality of stacked bodies are obtained. Among them, the stacked body is in the shape of a rectangular parallelepiped. In step S7, the two second cutting surfaces opposite to each other in the x direction formed by cutting are second cutting surfaces P2, which correspond to the first end face 11 and the second end face 12 of the ceramic body 1 respectively. The internal electrode 2 is exposed at the second cutting surface P2. Specifically, the first internal electrode 21 and the third internal electrode 23 are exposed at one of the second cutting surfaces P2 of the stacked body, and the second internal electrode 22 and the fourth internal electrode 24 are exposed at the other second cutting surface P2. When cutting in step S7, the first extension part film 4 and the second extension part film 6 are cut in the middle, so that the first extension part film 4 and the second extension part film 6 can extend to the edge of the first end face 11, that is, one end of the first extension part 32 and the second extension part 33 can extend to the edge of the first end face 11 so as to be connected with the main body 31.

[0068] S8, subjecting the laminate to a debinding and sintering process to obtain a ceramic body 1 including an inner electrode 2. Specifically, the debinding process includes: heating the laminate to 250°C-350°C in air and keeping it warm for 0.5 hours to 3 hours to remove the binder contained in the laminate, or heating the laminate to 350°C-600°C in nitrogen and keeping it warm for 2 hours to 6 hours to remove the binder contained in the laminate. The sintering process includes: heating the laminate to 1100°C-1300°C and keeping it warm for 0.5 hours to 3 hours in a reducing atmosphere formed by a mixed gas of humidified nitrogen and hydrogen (the volume of hydrogen is 0.1%-3% of the volume of nitrogen), sintering the laminate to be dense, and obtaining a ceramic body 1 including an inner 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 the ceramic body 1 to form an external electrode 3, and 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, and the thickness and continuity of the nickel layer of the first extension part 32 and the second extension part 33 are increased, and then the ceramic body 1 is electroplated with tin to form an external electrode 3, and the external electrode 3 includes a main body 31, a first extension part 32, and a second extension part 33 of a two-layer metal structure of a nickel layer and a tin layer from the inside to the outside. In addition, the ceramic body 1 can also 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, and copper layers are formed on the nickel layer of the first extension part 32 and the nickel layer of the second extension part 33, and then the ceramic body 1 is electroplated with nickel to form nickel layers on the copper layer of the main body 31, the copper layer of the first extension part 32 and the copper layer of the second extension part 33, and finally the ceramic body 1 is electroplated with tin to form the external electrode 3, the external electrode 3 includes a main body 31 with a three-layer metal structure of a copper layer, a nickel layer, and a tin layer from the inside to the outside, and a first extension part 32 and a second extension part 33 with a four-layer metal structure of a nickel layer, a copper layer, a nickel layer, and a tin layer from the inside to the outside. When the electroplating process is performed to form the bottom metal of the main body 31, the metal is easy to precipitate and grow on the end of the internal electrode 2 exposed at the first end face 11 and the second end face 12 and bridge each other to form a continuous and uniform metal plating layer. Through the electroplating treatment in step S9 , the surface metal of the external electrode 3 is a continuous and uniform tin layer, which can improve the solderability of the multilayer ceramic capacitor.

[0070] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A multilayer ceramic capacitor having an x-direction, a y-direction and a z-direction, characterized in that: include: A ceramic body having 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 four edges; The inner electrode comprises a first inner electrode and a second inner electrode which are staggered in the ceramic body along the z direction, wherein one end of the first inner electrode extends out of a first end surface of the ceramic body, and one end of the second inner electrode extends out of a second end surface of the ceramic body; as well as Two outer electrodes, the outer electrodes include a main body, two first extensions and two second extensions, the main bodies of the two outer electrodes are respectively arranged on the first end surface and the second end surface, and are respectively electrically connected to the first inner electrode and the second inner electrode, the two first extensions extend out of the two sides of the main body along the z direction, the two first extensions cover the two second side surfaces one by one, the side edges 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 out of the two sides of the main body along the y direction, the two second extensions cover the two first side surfaces one by one, the side edges of the second extensions along the z direction are spaced apart from the edges of the first side surfaces along the z direction.

2. The multilayer ceramic capacitor according to claim 1, wherein: The four corners of the main body are all provided with notches, and the four edges of the ceramic body are located in the notches in a one-to-one correspondence.

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

4. The multilayer ceramic capacitor according to claim 1, wherein: The inner electrode includes a third inner electrode and a fourth inner electrode which are staggered in the ceramic body along the z direction, the third inner electrode is located on a side of the first inner electrode away from the second inner electrode, the fourth inner electrode is located on a 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 surface 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 surface 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 surfaces, and the fourth inner electrode is spaced apart from the two first side surfaces.

5. The multilayer ceramic capacitor according to claim 1, wherein: The main body includes a nickel layer and a tin layer arranged from inside to outside.

6. The multilayer ceramic capacitor according to claim 1, wherein: The main body includes a copper layer, a nickel layer and a tin layer arranged from inside to outside.

7. The multilayer ceramic capacitor according to claim 1, wherein: The first extension portion and the second extension portion each include a nickel layer and a tin layer disposed from the inside to the outside.

8. The multilayer ceramic capacitor according to claim 1, wherein: The first extension portion and the second extension portion each 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, characterized in that: include: Mixing ceramic powder, a binder and an organic solvent to form a ceramic slurry, and casting the ceramic slurry to obtain a ceramic film; Printing nickel metal slurry on the ceramic film and drying it to form an internal electrode film; stacking a plurality of the ceramic films formed with the internal electrode films in the z direction to form a stacked structure, and covering the ceramic films on both sides of the stacked structure in the z direction to obtain a stacked mother board; Printing nickel metal paste on both sides of the laminate mother board along the z direction and drying it to form a first extension film, pressing the laminate mother board with the first extension film along the z direction, and then cutting it into a plurality of elongated rod-shaped laminate blocks in sequence along the y direction; Coating nickel metal slurry on both sides of the stacked body block along the y direction and drying the slurry to form a second extension film, and sequentially cutting the stacked body block along the x direction to obtain a plurality of stacked bodies; The laminate is subjected to a debinding and sintering process to obtain a ceramic body including an inner electrode, and the ceramic body is subjected to an electroplating process to form an outer electrode to obtain a multilayer ceramic capacitor.

10. The method for preparing a multilayer ceramic capacitor according to claim 9, characterized in that: The debinding process includes: heating the stack to 250°C-350°C in air and keeping it warm for 0.5 hour-3 hours to remove the binder contained in the stack, or heating the stack to 350°C-600°C in nitrogen and keeping it warm for 2 hours-6 hours to remove the binder contained in the stack; the sintering process includes: heating the stack to 1100°C-1300°C in a reducing atmosphere formed by a mixed gas of humidified nitrogen and hydrogen and keeping it warm for 0.5 hour-3 hours to sinter the stack to be dense, so as to obtain the ceramic body containing the inner electrode.

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