Multilayer ceramic capacitor and preparation method thereof

Abstract

The invention relates to the technical field of capacitors, and discloses a multilayer ceramic capacitor and a preparation method thereof.According to the scheme, a first side face and a second side face of a ceramic body are covered with insulating sheets respectively, so that in the process that the multilayer ceramic capacitor is welded to a circuit board, the multilayer ceramic capacitor is welded to the circuit board; even if the multilayer ceramic capacitor deflects or displaces and is contacted with the adjacent electronic component, short circuit between the multilayer ceramic capacitor and the adjacent electronic component can be well avoided. The outer electrode only covers the inner electrode, and the auxiliary electrode is exposed out of one end of the ceramic body and does not cover the two end surfaces of the insulating sheet along the first direction, so that the width of the outer electrode of the multilayer ceramic capacitor in the scheme is smaller than that of the outer electrode of the conventional multilayer ceramic capacitor; therefore, when any one of the third side surface and the fourth side surface is used as a mounting surface of the multi-layer ceramic capacitor, the size of the bonding pad can be correspondingly reduced, so that the distance between the multi-layer ceramic capacitor and the side-by-side adjacent electronic elements is reduced, and the mounting density is improved.

Description

Technical Field

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

[0002] A multilayer ceramic capacitor is composed of a ceramic body and external electrodes, and the external electrodes are arranged in pairs at both ends of the ceramic body. Generally, the multilayer ceramic capacitor is soldered to a circuit board by a method such as reflow soldering, and the external electrodes are connected to the corresponding pads by solder. In order to accommodate a certain amount of solder, the width of the pad needs to be greater than the width of the external electrode, so that the spacing between the multilayer ceramic capacitor and the adjacent electronic components is large, which is not conducive to improving the installation density. In addition, when the multilayer ceramic capacitor or the electronic components adjacent to it are deflected or displaced during welding, it may cause the electrodes of the two to contact and short-circuit. Summary of the invention

[0003] The object of the present invention is to provide a multilayer ceramic capacitor and a preparation method thereof, which is used to solve the problem in the prior art that the distance between the capacitor and adjacent electronic components is large, which is not conducive to improving the installation density, and the capacitor is prone to contact with adjacent electronic components and cause short circuit when it is deflected or displaced during welding.

[0004] In order to achieve the above objectives, in a first aspect, an embodiment of the present application provides a multilayer ceramic capacitor having a first direction, a second direction, and a third direction, including:

[0005] A ceramic body having a first end face and a second end face arranged oppositely along the first direction X, a first side face and a second side face arranged oppositely along the second direction Y, and a third side face and a fourth side face arranged oppositely along the third direction Z;

[0006] A plurality of inner electrodes are provided, wherein the plurality of inner electrodes are arranged in the ceramic body at intervals along the third direction Z, some of the inner electrodes extend to the first end surface along one side of the first direction X, some of the inner electrodes extend to the second end surface along one side of the first direction X, and both sides of the inner electrode along the second direction Y extend to the first side surface and the second side surface respectively;

[0007] Auxiliary electrodes, provided with a plurality of them and all disposed in the ceramic body, the auxiliary electrodes are spaced apart from the inner electrodes, some of the auxiliary electrodes extend to the first end surface along one side of the first direction X, some of the auxiliary electrodes extend to the second end surface along one side of the first direction X, and the auxiliary electrodes extend to the first side surface and the second side surface respectively along both sides of the second direction Y;

[0008] Two insulating sheets are provided, and the two insulating sheets cover the first side surface and the second side surface respectively; and

[0009] An external electrode, the first end surface and the second end surface are both covered with the external electrode.

[0010] In some embodiments of the present application, the ceramic body includes a plurality of ceramic films stacked along the third direction Z;

[0011] The inner electrode and the auxiliary electrode are arranged at intervals on a part of the ceramic film along the first direction X to form a first diaphragm; two auxiliary electrodes are arranged at intervals on a part of the ceramic film along the first direction X to form a second diaphragm;

[0012] A plurality of the first diaphragms are stacked along the third direction Z to form a main body unit, at least one second diaphragm is stacked on both sides of the main body unit along the third direction Z, and the ceramic film is covered on one side of the second diaphragm away from the main body unit;

[0013] One of the inner electrodes in the two first diaphragms adjacent to each other along the third direction Z extends to the first end surface, and the other inner electrode extends to the second end surface; one of the auxiliary electrodes extends to the second end surface, and the other auxiliary electrode extends to the first end surface; the two auxiliary electrodes on the second diaphragm extend to the first end surface and the second end surface respectively.

[0014] In some embodiments of the present application, at least one notch is respectively provided at both ends of the insulating sheet along the first direction X, and the notch penetrates the insulating sheet along the second direction Y; the notch close to the first end surface extends to the first end surface along one side of the first direction X, and the notch close to the second end surface extends to the second end surface along one side of the first direction X; the notch extends to the third side surface or the fourth side surface along one side of the third direction Z;

[0015] The external electrode covers the first end surface and the second end surface, and the external electrode also covers the area corresponding to the first side surface and the notch, and the area corresponding to the second side surface and the notch.

[0016] In some embodiments of the present application, the thickness of the external electrode is smaller than the thickness of the insulating sheet, so that the width of the external electrode along the second direction Y is smaller than the sum of the widths of the two insulating sheets along the second direction Y and the width of the ceramic body along the second direction Y.

[0017] In some embodiments of the present application, the insulating sheet includes a main body and two protruding parts;

[0018] The two sides of the main body along the third direction Z extend to the third side surface and the fourth side surface respectively, and the two sides of the main body along the first direction X are respectively connected to the two protrusions correspondingly;

[0019] One end of the two protrusions facing away from the main body portion extends to the first end surface and the second end surface respectively;

[0020] The protrusion is spaced apart from the third side surface or the fourth side surface along at least one side edge of the third direction Z to form the notch.

[0021] In some embodiments of the present application, two ends of the main body along the first direction X respectively cover a portion of the length of the auxiliary electrode extending to the first side surface and the second side surface.

[0022] In some embodiments of the present application, the insulating sheet is made of ceramic material.

[0023] In some embodiments of the present application, the external electrode is a two-layer metal structure, which is a nickel layer and a tin layer from the inside to the outside.

[0024] In a second aspect, the present application provides a method for preparing the multilayer ceramic capacitor in the above embodiment, comprising:

[0025] A ceramic film is prepared, and a nickel metal slurry is printed on the ceramic film according to a set position and dried to obtain: a ceramic film having both an inner electrode and an auxiliary electrode, and a ceramic film having only an auxiliary electrode;

[0026] A plurality of ceramic films with internal electrodes and auxiliary electrodes are stacked along a third direction Z, and two adjacent ceramic films with internal electrodes and auxiliary electrodes are staggered along a first direction X to obtain a first stack unit; a certain number of ceramic diaphragms with only auxiliary electrodes are stacked on both sides of the first stack unit along the third direction Z to obtain a second stack unit, and a certain number of ceramic films are stacked on both sides of the second stack unit along the third direction Z to obtain a stack mother board;

[0027] Compressing the laminate mother board along the third direction Z, and sequentially cutting the laminate mother board along the second direction Y to obtain a plurality of laminate blocks, wherein the laminate blocks have two first cut surfaces along the second direction Y;

[0028] Covering and connecting two insulating sheets to the two first cut surfaces of the stacked body block respectively;

[0029] Cutting the laminated body block covered with the insulating sheet in sequence along the first direction X to form a plurality of green ceramic sheets;

[0030] The green ceramic sheets are sequentially debinded and sintered to obtain a laminate covered with an insulating sheet;

[0031] The laminate covered with the insulating sheet is subjected to electroplating treatment to form a nickel layer and a tin layer on the first end surface and the second end surface in sequence, thereby obtaining a multilayer ceramic capacitor.

[0032] In some embodiments of the present application, a plurality of the ceramic films are stacked and pressed along the third direction to obtain the insulating sheet.

[0033] Compared with the prior art, the multilayer ceramic capacitor and its preparation method in the embodiment of the present invention have the following beneficial effects: in the process of soldering the multilayer ceramic capacitor to the circuit board, even if the multilayer ceramic capacitor is deflected or displaced and contacts the adjacent electronic components, the short circuit between the two can be avoided; at the same time, because the external electrode only covers the end of the ceramic body where the inner electrode and the auxiliary electrode are exposed, but not the two end surfaces of the insulating sheet along the first direction, the width of the external electrode of the multilayer ceramic capacitor in the present embodiment is reduced compared with the width of the external electrode of the conventional multilayer ceramic capacitor, so that when any one of the third side and the fourth side is used as the mounting surface of the multilayer ceramic capacitor, the size of the soldering pad can be reduced accordingly, thereby reducing the spacing between the multilayer ceramic capacitor and the adjacent electronic components, thereby improving the mounting density. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is an appearance diagram of a multilayer ceramic capacitor according to an embodiment of the present invention;

[0035] Figure 2 is an assembly structure diagram of a laminate and an insulating sheet in an embodiment of the present invention;

[0036] Figure 3 is an appearance diagram of a laminated body in an embodiment of the present invention;

[0037] Figure 4 A cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention Figure 1 ;

[0038] Figure 5 A cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention Figure 2 ;

[0039] Figure 6 A cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention Figure 3 ;

[0040] Figure 7 A cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention Figure 4 ;

[0041] Figure 8 It is an existing conventional inner electrode printing pattern;

[0042] Fig. 9 The inner electrode printing pattern of the embodiment of the present invention;

[0043] Fig.10 is a schematic diagram of cutting a laminated mother board into laminated blocks in an embodiment of the present invention;

[0044] Fig.11 is a schematic diagram of bonding an insulating sheet mother sheet to a stacked body block in an embodiment of the present invention;

[0045] Fig.12 This is an appearance diagram of the insulating sheet mother sheet and the laminated body block after being bonded in the embodiment of the present invention;

[0046] Fig.13 It is a schematic diagram of cutting a laminated body block covered with an insulating sheet mother sheet into green ceramic sheets in an embodiment of the present invention.

[0047] In the figure, 1, raw ceramic sheet; 11, first end face; 12, second end face; 13, first side face; 14, second side face; 15, third side face; 16, fourth side face; 17, first internal electrode; 18, second internal electrode; 19, auxiliary electrode; 2, insulating sheet; 21, main body; 22, protrusion; 3, external electrode; 4, laminated body block; 5, insulating sheet mother sheet; X, first direction; Y, second direction; Z, third direction. DETAILED DESCRIPTION

[0048] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0049] In the description of the present invention, it should be understood that the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention 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 invention. It should be understood that the terms "first", "second", etc. are used in the present invention to describe various information, but such information should not be limited to these terms, which are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present invention, "first" information may also be referred to as "second" information, and similarly, "second" information may also be referred to as "first" information.

[0050] like Figure 1-Figure 13As shown, in the first aspect, the embodiment of the present application proposes a multilayer ceramic capacitor, with a set first direction X, a second direction Y, and a third direction Z as reference directions, including a ceramic body, the ceramic body having a first end face 11 and a second end face 12 arranged oppositely along the first direction X, a first side face 13 and a second side face 14 arranged oppositely along the second direction Y, and a third side face 15 and a fourth side face 16 arranged oppositely along the third direction Z; a plurality of internal electrodes (for example, 100-900) are provided to increase the capacitance of the multilayer ceramic capacitor; a plurality of internal electrodes are arranged in the ceramic body at intervals along the third direction Z, and the internal electrodes are divided into two groups, including a first internal electrode 17 and a second internal electrode 18, the first internal electrode 17 extends to the first end face 11 along one side of the first direction X, and the second internal electrode 18 extends to the second end face 12 along one side of the first direction X, as shown in FIG. Figure 4 As shown, the first internal electrodes 17 and the second internal electrodes 18 are alternately arranged along the third direction Z and are separated by ceramics and insulated from each other; Figure 3 As shown, the first inner electrode 17 and the second inner electrode 18 extend to the first side surface 13 and the second side surface 14 along both sides of the second direction Y, and the first inner electrode 17 and the second inner electrode 18 do not expose the third side surface 15 and the fourth side surface 16; there are multiple auxiliary electrodes 19 and they are all arranged in the ceramic body. The auxiliary electrodes 19 are spaced apart from the inner electrodes. Part of the auxiliary electrodes 19 extend to the first end surface 11 along one side of the first direction X, and part of the auxiliary electrodes 19 extend to the second end surface 12 along one side of the first direction X. The auxiliary electrodes 19 extend to the first side surface 13 and the second side surface 14 along both sides of the second direction Y, and the auxiliary electrodes 19 do not expose the third side surface 15 and the fourth side surface 16 along the third direction Z. As shown Figure 1 , Figure 2 As shown, there are two insulating sheets 2, which cover the first side surface 13 and the second side surface 14 respectively; and the external electrode 3, the first end surface 11 and the second end surface 12 are both covered with the external electrode 3, and the external electrode 3 does not cover the two end surfaces of the insulating sheet 2 along the first direction X.

[0051] In this solution, the first side surface 13 and the second side surface 14 of the ceramic body are respectively covered with an insulating sheet 2, so that when the multilayer ceramic capacitor is subsequently welded to a circuit board, even if the multilayer ceramic capacitor is deflected or displaced and contacts adjacent electronic components, a short circuit will not occur between the two. At the same time, the external electrode 3 only covers the end of the first internal electrode 17, the second internal electrode 18, and the auxiliary electrode 19 that are exposed from the ceramic body, and does not cover the two end surfaces of the insulating sheet 2 along the first direction X, so that the width of the external electrode 3 of the multilayer ceramic capacitor in this solution is reduced compared with the width of the external electrode 3 of the existing conventional multilayer ceramic capacitor, so that when the multilayer ceramic capacitor is welded to the circuit board, the required pad size is also reduced accordingly, thereby reducing the spacing between the multilayer ceramic capacitor and the adjacent electronic components, thereby improving the mounting density. At the same time, due to the setting of the insulating sheet 2, the first side 13 and the second side 14 of the multilayer ceramic capacitor are covered, which can play a role in moisture-proof and mechanical damage-proof, thereby improving the reliability of the multilayer ceramic capacitor. The thickness of the insulating sheet 2 in this scheme is 50μm~200μm. If the thickness is too small, the moisture-proof and mechanical damage-proof effects of the insulating sheet 2 will be weakened; if the thickness is too large, it is not conducive to increasing the capacitance of the multilayer ceramic capacitor.

[0052] In some embodiments of the present application, the ceramic body includes a plurality of ceramic films stacked along a third direction Z; an inner electrode and an auxiliary electrode 19 are provided at intervals along the first direction X on some of the ceramic films to form a first diaphragm; two auxiliary electrodes 19 are provided at intervals along the first direction X on some of the ceramic films to form a second diaphragm; a plurality of first diaphragms are stacked along the third direction Z to form a main body unit, at least one second diaphragm is stacked on both sides of the main body unit along the third direction Z, and a ceramic film is covered on the side of the second diaphragm away from the main body unit (so that the auxiliary electrode 19, the first inner electrode 17, and the second inner electrode 18 are not exposed to the third side surface 15 and the fourth side surface 16); one of the inner electrodes (the first inner electrode 17) in the two first diaphragms adjacent to each other along the third direction Z extends to the first end surface 11, and the other inner electrode (the second inner electrode 18) extends to the second end surface 12, that is, the first inner electrodes 17 and the second inner electrodes 18 adjacent to each other along the third direction Z are staggered along the first direction X, so that the first inner electrodes 17 and the second inner electrodes 18 adjacent to each other along the third direction Z are in an opposing state along the first direction X (such as Figure 4 As shown), in this embodiment, the inner electrode is a rectangular sheet extending on the plane where the first direction X and the second direction Y are located, so as to maximize the opposing area between adjacent first inner electrodes 17 and second inner electrodes 18, thereby increasing the capacitance.

[0053] In two first diaphragms adjacent to each other along the third direction Z, one auxiliary electrode 19 extends to the second end surface 12 and the other auxiliary electrode 19 extends to the first end surface 11 ; the two auxiliary electrodes 19 on the second diaphragm extend to the first end surface 11 and the second end surface 12 respectively.

[0054] In the present embodiment, an auxiliary electrode 19 is provided, and an auxiliary electrode 19 having ends exposed at the first end face 11 and the second end face 12 is provided between the outermost inner electrode and the third side face 15 and the fourth side face 16 along the third direction Z, so that the exposed ends of the inner electrode and the exposed ends of the auxiliary electrode 19 are densely distributed on the first end face 11 and the second end face 12, so that a continuous and uniform metal layer can be formed on the first end face 11 and the second end face 12 during electroplating (which helps to improve the formation quality of the external electrode 3). The auxiliary electrode 19 in the present embodiment basically has no function of generating capacitance.

[0055] The thickness of the inner electrode in this solution can be 0.5 μm to 1 μm. If the thickness is too small, the continuity of the inner electrode is poor, which is not conducive to increasing the capacitance; if the thickness is too large, it is not conducive to reducing the thickness of the multilayer ceramic capacitor.

[0056] In some embodiments of the present application, Figure 1 , Figure 2 As shown, at least one notch is respectively provided at both ends of the insulating sheet 2 along the first direction X, and the notch penetrates the insulating sheet 2 along the second direction Y; the notch close to the first end face 11 extends to the first end face 11 along one side of the first direction X, and the notch close to the second end face 12 extends to the second end face 12 along one side of the first direction X; the notch extends to the third side face 15 or the fourth side face 16 along one side of the third direction Z; the external electrode 3 covers the first end face 11, the second end face 12 and the first side face 13, the second side face 14 and the corresponding area of ​​the notch, so that the external electrode 3 covering the first end face 11 and the first inner electrode 17 and the auxiliary electrode 19 exposed at the first end face 11 and the first side face 13 and the second side face 14 exposed at the first side face 13 and the second side face 14 are connected to each other. The first inner electrode 17 and the auxiliary electrode 19 of the side surface 14 are connected; the outer electrode 3 covering the second end surface 12 and the second inner electrode 18 and the auxiliary electrode 19 exposed at the second end surface 12, as well as the second inner electrode 18 and the auxiliary electrode 19 exposed at the first side surface 13 and the second side surface 14 are connected; in this scheme, the notch on the insulating sheet 2 can be set to 2 (the two notches are both set at the end of the insulating sheet 2 close to the third side surface 15 or the end of the fourth side surface 16), so that the side of the multilayer ceramic capacitor with the two notches is used as the mounting surface of the multilayer ceramic capacitor; or the notch is set to 4 (the insulating sheet 2 is close to the third side surface 15 and the fourth side surface 16 at both ends are provided with two notches); as Figure 2As shown, any one of the third side surface 15 or the fourth side surface 16 of the multilayer ceramic capacitor is used as the mounting surface, so that during the welding process, the first end surface 11, the second end surface 12, and the first side surface 13 and the second side surface 14 corresponding to the notch of the multilayer ceramic capacitor can be covered with solder and form a full solder joint, which can improve the installation stability of the multilayer ceramic capacitor and improve the reliability of the multilayer ceramic capacitor. In this solution, the external electrode 3 is covered at the position corresponding to the first side surface 13 and the notch and the position corresponding to the notch of the second side surface 14, so that when the multilayer ceramic capacitor is subsequently welded to the circuit board, the solder can be attached to the surface of the external electrode 3 and the surface tension of the molten solder can suppress the displacement of the multilayer ceramic capacitor in the first direction X during the welding process, thereby avoiding the position of the multilayer ceramic capacitor from deflecting during the welding process as much as possible.

[0057] In some embodiments of the present application, Figure 5 , Figure 6 , Figure 7 As shown, in this solution, the thickness of the external electrode 3 is less than the thickness of the insulating sheet 2 (the thickness of the insulating sheet 2 is 50μm to 200μm, and the thickness of the external electrode 3 is 7μm to 15μm), so that the width (W1) of the external electrode 3 along the second direction Y is less than the total width (W2) of the two insulating sheets 2 and the ceramic body along the second direction Y. The external electrode 3 is concave inward relative to the insulating sheet 2 along the second direction Y. Although part of the external electrode 3 is covered on the first side surface 13 and the second side surface 14 corresponding to the notch, the width of the external electrode 3 of the multilayer ceramic capacitor in this solution is still reduced compared with the width of the conventional multilayer ceramic capacitor, which can effectively reduce the size of the pad, reduce the spacing between the multilayer ceramic capacitor and the adjacent electronic components, and improve the installation density. In this solution, the first side surface 13 and the second side surface 14 corresponding to the notch are covered with the external electrode 3, which improves the installation stability of the multilayer ceramic capacitor while not affecting the installation density of the multilayer ceramic capacitor on the circuit board.

[0058] In some embodiments of the present application, the insulating sheet 2 includes a main body 21 and two protrusions 22; the two sides of the main body 21 along the third direction Z extend to the third side 15 and the fourth side 16 respectively, and the two sides of the main body 21 along the first direction X are respectively connected to the two protrusions 22; the ends of the two protrusions 22 away from the main body 21 extend to the first end face 11 and the second end face 12 respectively; the protrusion 22 is spaced from the third side 15 or the fourth side 16 along at least one side of the third direction Z to form a gap; in this solution, the protrusions The distances (T1) between the two side edges of the protrusion 22 along the third direction Z and the third side surface 15 and the fourth side surface 16 are set to be equal, the thickness of the ceramic body along the third direction Z is T2, and the ratio of T1 to T2 is set to 0.2-0.5. When the ratio is too small, the bonding force between the protrusion 22 and the ceramic body is insufficient and easy to peel off, and the strength of the protrusion 22 is small and easy to be damaged; when the ratio is too large, the notch area at the corner of the first side surface 13 and the second side surface 14 will be too small, resulting in difficulty in forming full solder joints when soldering multilayer ceramic capacitors on a circuit board.

[0059] In some embodiments of the present application, Figure 7 As shown, the two ends of the main body 21 along the first direction X at least respectively cover the partial length of the auxiliary electrode 19 extending to the first side surface 13 and the second side surface 14, that is, the distance between the side of the main body 21 close to the first end surface 11 and the first end surface 11 is smaller than the distance between the side of the second internal electrode 18 close to the first end surface 11 and the first end surface 11, and the distance between the side of the main body 21 close to the second end surface 12 and the second end surface 12 is smaller than the distance between the side of the first internal electrode 17 close to the second end surface 12 and the second end surface 12; thereby, the main body 21 can cover the areas where the first internal electrode 17 and the second internal electrode 18 are exposed on the first side surface 13 and the second side surface 14 and are opposite to each other, thereby improving the moisture-proof effect and improving the reliability of the multilayer ceramic capacitor.

[0060] In some embodiments of the present application, the insulating sheet 2 is made of ceramic material.

[0061] In some embodiments of the present application, the external electrode 3 is a two-layer metal structure, which is a nickel layer and a tin layer from the inside to the outside.

[0062] In a second aspect, the present application provides a method for preparing a multilayer ceramic capacitor as in the above embodiment, characterized in that it includes:

[0063] Ceramic powder, adhesive and organic solvent are mixed to form ceramic slurry, and the ceramic slurry is cast into a ceramic film. The material of the ceramic powder can be barium titanate, calcium zirconate, etc. The thickness of the ceramic film is 1μm to 3μm. If the thickness is too small, the insulation resistance and reliability of the multilayer ceramic capacitor are easy to deteriorate; if the thickness is too large, it is not conducive to improving the capacitance of the multilayer ceramic capacitor, and the distance between the end of the inner electrode exposed at the first end face 11 and the second end face 12 and the end of the auxiliary electrode 19 is too large, so it is difficult to form a continuous and uniform metal layer at a specific position of the first end face 11 and the second end face 12 by electroplating.

[0064] Nickel metal paste is printed on the ceramic film according to the set position and dried to obtain a first membrane having an inner electrode and an auxiliary electrode 19 and a second membrane having only the auxiliary electrode 19. Figure 8 As shown in the figure, it is an existing conventional internal electrode film printing pattern, L represents a virtual cutting line. In order to form an insulating sheet 2 on the first side 13 and the second side 14 of the ceramic body during subsequent cutting, a gap G needs to be reserved between the internal electrodes, for example, along the second direction Y. However, due to the influence of the cutting position accuracy, the width of the insulating sheet 2 on both sides of the ceramic body in the second direction Y is uneven, and even because the cutting line falls on the internal electrode instead of the gap G, the insulating sheet 2 cannot be formed, so that the internal electrode is exposed on the first side 13 or the second side 14 of the ceramic body, which reduces the reliability of the multilayer ceramic capacitor. Fig. 9 As shown, this is the internal electrode printing pattern in the present solution. When printing the internal electrode, there is no need to reserve a gap G on the internal electrode along the second direction Y. After subsequent cutting, the first side 13 and the second side 14 of the ceramic body can be directly covered with an insulating sheet 2 of equal width. Therefore, it is not affected by the cutting accuracy and there is no worry about the internal electrode being exposed on the surface of the multilayer ceramic capacitor.

[0065] A plurality of ceramic films having an inner electrode and an auxiliary electrode 19 are stacked along a third direction Z, and two adjacent ceramic films having an inner electrode and an auxiliary electrode 19 are staggered along a first direction X to obtain a first stack unit; a certain number of the ceramic diaphragms having only auxiliary electrodes 19 are stacked on both sides of the first stack unit along the third direction Z to obtain a second stack unit, and a certain number of ceramic films are stacked on both sides of the second stack unit along the third direction to obtain a stack mother board; the first stack unit is formed as the central part of the stack mother board, and a plurality of ceramic films having only auxiliary electrodes 19 are stacked along the third direction Z to form the outer part of the stack mother board, so that the inner electrode can be covered with the outer part of the stack mother board to prevent the inner electrode from exposing the third side surface 15 and the fourth side surface 16, and protect the inner electrode from moisture intrusion and mechanical damage, and a plurality of auxiliary electrodes 19 are arranged on the outer part of the stack mother board along the third direction Z, so as to facilitate the formation of a continuous and uniform metal layer at a specific position on the surface of the ceramic body by electroplating. When a plurality of ceramic films having internal electrodes and auxiliary electrodes 19 are stacked along a third direction Z, two adjacent ceramic films are staggered in the first direction X (offset by a certain distance) so that a first internal electrode 17 and a second internal electrode 18 are formed in the final ceramic body.

[0066] The laminate motherboard is pressed along the third direction Z, and the laminate motherboard is cut in sequence along the second direction Y to obtain a plurality of laminate blocks 4, wherein the laminate blocks 4 have two first cutting surfaces along the second direction Y; the first cutting surfaces correspond to the first side surface 13 and the second side surface 14 of the ceramic body, and the first internal electrode 17, the second internal electrode 18 and the auxiliary electrode 19 are exposed on the first cutting surfaces.

[0067] The two insulating sheets 2 are respectively covered and connected to the two first cut surfaces of the laminated body block 4 . Specifically, the insulating sheets 2 and the laminated body block 4 are combined under heating and pressure.

[0068] The stacked body block 4 covered with the insulating sheet 2 is cut in sequence along the first direction X to form a plurality of raw ceramic sheets 1; two second cut surfaces are formed at both ends of the raw ceramic sheet 1 along the first direction X, and the first internal electrode 17, the second internal electrode 18, and the auxiliary electrode 19 are all exposed on the second cut surfaces.

[0069] The raw ceramic sheet 1 is debonded and sintered in sequence to obtain a laminate covered with an insulating sheet 2; the specific process is: first, debonding is performed, which is to heat the laminate to 250°C-350°C in air and keep it warm for 0.5 hour-3 hours to remove the adhesive contained in the laminate; or, the laminate is heated to 350°C-600°C in nitrogen and kept warm for 2 hours-6 hours to remove the adhesive contained in the laminate. Then sintering is performed, which is to heat the laminate to 1100°C-1300°C and keep it warm for 0.5 hour-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), and the laminate is sintered to be dense to obtain a laminate covered with an insulating sheet 2.

[0070] The stack covered with the insulating sheet 2 is electroplated to form a nickel layer and a tin layer on the first end face 11 and the second end face 12 in sequence to obtain a multilayer ceramic capacitor; since the first end face 11 and the second end face 12 are densely covered with the exposed ends of the inner electrode and the exposed ends of the auxiliary electrode 19, metal is easily precipitated and grown on the exposed ends of the inner electrode and the exposed ends of the auxiliary electrode 19 during electroplating and bridge each other to form a continuous and uniform metal plating layer.

[0071] In some embodiments of the present application, the ceramic film is stacked and pressed along a third direction Z to obtain an insulating sheet mother sheet 5; in this scheme, the notch on the insulating sheet 2 can be formed into a vacant portion at a specific position of the insulating sheet mother sheet 5 by punching; when the insulating sheet mother sheet 5 covers the first cut surface, most of the first cut surface is covered, and since the vacant portion is formed on the insulating sheet mother sheet 5, a small portion of the first cut surface is exposed, and the exposed portion corresponds to the notch position on the insulating sheet 2, so that part of the first internal electrode 17, the second internal electrode 18 and the auxiliary electrode 19 are exposed in the first side surface 13 and the second side surface 14 area corresponding to the notch.

[0072] The working process of this scheme is as follows: prepare a ceramic film, print nickel metal paste on the ceramic film according to the set position and dry it, stack a plurality of ceramic films with internal electrodes and auxiliary electrodes 19 along a third direction Z, and stagger two adjacent ceramic films along a first direction X to obtain a first stack unit; stack a certain number of ceramic diaphragms with only auxiliary electrodes 19 on both sides of the first stack unit along the third direction Z to obtain a second stack unit, stack a certain number of ceramic films on both sides of the second stack unit along the third direction to obtain a stack mother board; stack the stack mother board along the third direction Z Compress and cut the laminate motherboard in sequence along the second direction Y to obtain a plurality of laminate blocks 4, wherein the laminate block 4 has two first cut surfaces along the second direction Y; two insulating sheets 2 are respectively covered and connected to the two first cut surfaces of the laminate block 4; the laminate block 4 covered with the insulating sheet 2 is cut in sequence along the first direction X to form a plurality of raw ceramic sheets 1; the raw ceramic sheets 1 are debonded and sintered in sequence to obtain a laminate covered with the insulating sheet 2; the laminate covered with the insulating sheet 2 is electroplated to form a nickel layer and a tin layer in sequence on the first end face 11 and the second end face 12 to obtain a multilayer ceramic capacitor.

[0073] In summary, the embodiment of the present invention provides a multilayer ceramic capacitor and a preparation method thereof. In this scheme, the first side surface 13 and the second side surface 14 of the ceramic body are respectively covered with an insulating sheet 2, so that during the process of welding the multilayer ceramic capacitor to the circuit board, even if the multilayer ceramic capacitor is deflected or displaced and contacts the adjacent electronic components, the short circuit between the two can be better avoided; at the same time, because the external electrode 3 only covers the end of the ceramic body where the inner electrode and the auxiliary electrode 19 are exposed, and does not cover the two end surfaces of the insulating sheet 2 along the first direction X, the width of the external electrode 3 of the multilayer ceramic capacitor in this scheme is reduced compared with the width of the external electrode 3 of the existing conventional multilayer ceramic capacitor, so that when any one of the third side surface 15 and the fourth side surface 16 is used as the mounting surface of the multilayer ceramic capacitor, the size of the pad can be reduced accordingly, thereby reducing the spacing between the multilayer ceramic capacitor and the adjacent electronic components side by side, thereby improving the mounting density.

[0074] 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 a first direction (X), a second direction (Y), and a third direction (Z), characterized in that: include: A ceramic body having a first end face (11) and a second end face (12) arranged opposite to each other along the first direction (X), a first side face (13) and a second side face (14) arranged opposite to each other along the second direction (Y), and a third side face (15) and a fourth side face (16) arranged opposite to each other along the third direction (Z); A plurality of internal electrodes are provided, wherein the plurality of internal electrodes are arranged in the ceramic body at intervals along the third direction (Z), some of the internal electrodes extend to the first end surface (11) along one side of the first direction (X), some of the internal electrodes extend to the second end surface (12) along one side of the first direction (X), and both sides of the internal electrodes along the second direction (Y) extend to the first side surface (13) and the second side surface (14) respectively; A plurality of auxiliary electrodes (19) are provided and all are arranged in the ceramic body, the auxiliary electrodes (19) are arranged at intervals from the inner electrode, some of the auxiliary electrodes (19) extend to the first end surface (11) along one side of the first direction (X), some of the auxiliary electrodes (19) extend to the second end surface (12) along one side of the first direction (X), and the auxiliary electrodes (19) extend to the first side surface (13) and the second side surface (14) along both sides of the second direction (Y) respectively; Two insulating sheets (2) are provided, and the two insulating sheets (2) respectively cover the first side surface (13) and the second side surface (14); and An external electrode (3), wherein both the first end surface (11) and the second end surface (12) are covered with the external electrode (3).

2. The multilayer ceramic capacitor according to claim 1, wherein: The ceramic body includes a plurality of ceramic films stacked along the third direction (Z); The inner electrode and the auxiliary electrode (19) are arranged at intervals on a portion of the ceramic film along the first direction (X) to form a first diaphragm; and two auxiliary electrodes (19) are arranged at intervals on a portion of the ceramic film along the first direction (X) to form a second diaphragm; A plurality of the first diaphragms are stacked along the third direction (Z) to form a main body unit, at least one of the second diaphragms is stacked on both sides of the main body unit along the third direction (Z), and the ceramic film is covered on one side of the second diaphragm away from the main body unit; One of the inner electrodes in the two first diaphragms adjacent to each other along the third direction (Z) extends to the first end surface (11), and the other inner electrode extends to the second end surface (12); one of the auxiliary electrodes (19) extends to the second end surface (12), and the other auxiliary electrode (19) extends to the first end surface (11); and the two auxiliary electrodes (19) on the second diaphragm extend to the first end surface (11) and the second end surface (12) respectively.

3. The multilayer ceramic capacitor according to claim 1, wherein: The insulating sheet (2) is provided with at least one notch at each end along the first direction (X), and the notch penetrates the insulating sheet (2) along the second direction (Y); the notch close to the first end surface (11) extends along one side of the first direction (X) to the first end surface (11), and the notch close to the second end surface (12) extends along one side of the first direction (X) to the second end surface (12); the notch extends along one side of the third direction (Z) to the third side surface (15) or the fourth side surface (16); The external electrode (3) covers the first end surface (11) and the second end surface (12), and the external electrode (3) also covers the area corresponding to the first side surface (13) and the notch, and the area corresponding to the second side surface (14) and the notch.

4. The multilayer ceramic capacitor according to claim 3, wherein: The thickness of the external electrode (3) is smaller than the thickness of the insulating sheet (2), so that the width of the external electrode (3) along the second direction (Y) is smaller than the sum of the widths of the two insulating sheets (2) along the second direction (Y) and the width of the ceramic body along the second direction (Y).

5. The multilayer ceramic capacitor according to claim 3, wherein: The insulating sheet (2) comprises a main body (21) and two protruding parts (22); The two side edges of the main body (21) along the third direction (Z) extend to the third side surface (15) and the fourth side surface (16) respectively, and the two side edges of the main body (21) along the first direction (X) are respectively connected to the two protrusions (22) correspondingly; One end of the two protrusions (22) facing away from the main body (21) extends to the first end surface (11) and the second end surface (12) respectively and correspondingly; The protrusion (22) is arranged at a distance from the third side surface (15) or the fourth side surface (16) along at least one side edge of the third direction (Z) to form the notch.

6. The multilayer ceramic capacitor according to claim 5, characterized in that Both ends of the main body (21) along the first direction (X) respectively cover a portion of the length of the auxiliary electrode (19) extending to the first side surface (13) and the second side surface (14).

7. The multilayer ceramic capacitor according to any one of claims 3 to 6, characterized in that: The insulating sheet (2) is made of ceramic material.

8. The multilayer ceramic capacitor according to claim 1, wherein: The outer electrode (3) is a two-layer metal structure, which comprises a nickel layer and a tin layer from the inside to the outside.

9. A method for preparing a multilayer ceramic capacitor according to any one of claims 1 to 8, characterized in that: include: A ceramic film is prepared, and a nickel metal slurry is printed on the ceramic film according to a set position and then dried to obtain: a ceramic film having both an inner electrode and an auxiliary electrode (19), and a ceramic film having only an auxiliary electrode (19); A plurality of ceramic films having internal electrodes and auxiliary electrodes (19) are stacked along a third direction (Z), and two adjacent ceramic films having internal electrodes and auxiliary electrodes (19) are staggered along a first direction (X) to obtain a first stacked body unit; a certain number of ceramic diaphragms having only auxiliary electrodes (19) are stacked on both sides of the first stacked body unit along the third direction (Z) to obtain a second stacked body unit, and a certain number of ceramic films are stacked on both sides of the second stacked body unit along the third direction (Z) to obtain a stacked body motherboard; Compressing the laminate mother plate along the third direction (Z), and sequentially cutting the laminate mother plate along the second direction (Y) to obtain a plurality of laminate blocks (4), wherein the laminate blocks (4) have two first cut surfaces along the second direction (Y); Two insulating sheets (2) are respectively covered and connected to the two first cut surfaces of the stacked body block (4); The stacked body block (4) covered with the insulating sheet (2) is sequentially cut along the first direction (X) to form a plurality of green ceramic sheets (1); Debinding and sintering the green ceramic sheet (1) in sequence to obtain a laminated body covered with an insulating sheet (2); The laminate covered with the insulating sheet (2) is subjected to electroplating treatment to sequentially form a nickel layer and a tin layer on the first end surface (11) and the second end surface (12) to obtain a multilayer ceramic capacitor.

10. The method for preparing a multilayer ceramic capacitor according to claim 9, characterized in that: The plurality of ceramic films are stacked and pressed along the third direction (Z) to obtain the insulating sheet (2).

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