Preparation method of multilayer ceramic capacitor and multilayer ceramic capacitor

Abstract

The invention relates to the technical field of ceramic capacitors, in particular to a preparation method of a multi-layer ceramic capacitor and the multi-layer ceramic capacitor. When a laminated strip is prepared, an inner electrode unit is processed on a ceramic thin film to form a ceramic electrode diaphragm; laminating the multiple layers of ceramic electrode diaphragms into a laminated body mother board by adopting a laminating process, and then cutting the laminated body mother board into laminated strips; when the protective strip is prepared, a laminating process of a laminated body mother board is adopted, a plurality of layers of ceramic films are laminated to form a protective sheet mother board, then the protective sheet mother board is divided into a plurality of protective strips, then the protective strips are attached to the outer sides of the laminated strips to form green ceramic strips, then the green ceramic strips are cut into a plurality of green ceramic bodies, and finally the green ceramic bodies are sintered. The sintering shrinkage of the laminated strip and the protective strip is consistent, so that the protective sheet is prevented from falling off from the laminated strip when the green ceramic body is sintered.

Description

Technical Field

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

[0002] The internal electrodes of multilayer ceramic capacitors are generally printed to form a plurality of array-arranged internal electrode thin film units on a ceramic film. Figure 1 As shown, currently, in order to prevent the internal electrode unit from being exposed from the two sides in the width direction of the stack after the cutting process, it is necessary to reserve a gap in the width direction of the internal electrode film unit, and then cut the stack motherboard into a stack at the reserved gap, and form two protective sheets at the positions corresponding to the above-mentioned reserved gaps on both sides of the stack. No internal electrode film is formed at the position of gap G. Since the stack forms a thickness difference between the internal electrode film unit and the gap G, the position with a larger thickness of the stack motherboard bulges after being pressed, so that the surface of the multilayer ceramic capacitor forms a bulge-like protrusion, which easily causes the vacuum suction nozzle to fail to suck the multilayer ceramic capacitor during automatic chip mounting, resulting in poor installation. However, due to the influence of the cutting position accuracy, the width of the two protective sheets cannot be guaranteed to be equal, and even because the cutting position falls on the internal electrode film unit, the internal electrode may be exposed on the side in the width direction of the stack, which reduces the reliability of the multilayer ceramic capacitor.

[0003] In order to solve the above problem, the existing method is: instead of reserving a gap between the internal electrode film units in the width direction, a protective sheet is prepared in advance, and a protective sheet with equal width is pressed on the two sides in the width direction of the stack obtained after the cutting process, thereby sealing the internal electrode, and then sintering the stack and the protective sheet to ensure the reliability of the multilayer ceramic capacitor.

[0004] However, during the sintering process of the protective sheet and the laminate, the protective sheet is easy to fall off from the laminate. The inventors have found through research that the reason why the protective sheet falls off from the side of the laminate is that the laminate is made of a ceramic film that has been subjected to a heating and pressurizing compaction process, so the laminate is relatively dense, while the protective sheet has not been subjected to a heating and pressurizing compaction process. Therefore, during the sintering process, the sintering shrinkage of the laminate and the protective sheet is inconsistent, which makes the protective sheet easy to fall off from the laminate. Summary of the invention

[0005] The technical problem to be solved by the present invention is that when a laminated body with a protective sheet is sintered and pressed, the protective sheet of the existing multilayer ceramic capacitor is easily detached from the laminated body.

[0006] In order to solve the above technical problems, the present invention provides a method for preparing a multilayer ceramic capacitor, comprising the following steps:

[0007] Step S1, preparing the stacking strips and the protective strips:

[0008] The preparation of the laminated strips comprises: processing an inner electrode unit on a ceramic film to form a ceramic electrode membrane; laminating multiple layers of the ceramic electrode membranes into a laminated motherboard by a lamination process; and cutting the laminated motherboard into laminated strips;

[0009] The preparation of the protection strip comprises: using the lamination process of the laminate motherboard to press multiple layers of the ceramic film into a protection sheet motherboard; dividing the protection sheet motherboard into a plurality of protection strips;

[0010] Step S2, pressing each of the protection strips onto the outer side of the stacking strip to form a green ceramic strip;

[0011] Step S3, cutting the green ceramic strip into a plurality of green ceramic bodies;

[0012] Step S4, sintering the green ceramic body into a finished ceramic body.

[0013] As a preferred solution, the stacking direction of the ceramic films of the protection strip in the green ceramic strip is the same as the stacking direction of the ceramic electrode membranes of the stacking strip in the green ceramic strip.

[0014] As a preferred solution, the inner electrode units are exposed at both ends of the laminated strips in a width direction.

[0015] As a preferred solution, the pressing process is a cold isostatic pressing process, the liquid medium temperature of the cold isostatic pressing is greater than or equal to 60° C. and less than or equal to 90° C., and the liquid medium pressure is greater than or equal to 30 MPa and less than or equal to 200 MPa.

[0016] As a preferred solution, the preparing of the protection strips further comprises: grinding each of the protection strips to a thickness greater than or equal to 50 μm and less than or equal to 200 μm.

[0017] As a preferred solution, the cutting surface in step S3 forms a cut surface;

[0018] The preparation of the protection strip further comprises: processing a plurality of conductive layers arranged at intervals along the length direction of the protection strip on the grinding surface of the protection strip, wherein the conductive layers are symmetrically arranged with the cut surfaces as the center.

[0019] As a preferred solution, after step S3 and before step S4, the method further includes:

[0020] Step S31, heating each of the green ceramic bodies in air to a temperature greater than or equal to 250°C and less than or equal to 350°C and keeping the temperature therefor for a period of greater than or equal to 0.5 hour and less than or equal to 3 hours; or heating each of the green ceramic bodies in nitrogen to a temperature greater than or equal to 350°C and less than or equal to 600°C and keeping the temperature therefor for a period of greater than or equal to 2 hours and less than or equal to 6 hours, so as to discharge the binder in each green ceramic body.

[0021] As a preferred solution, step S4 includes:

[0022] In a reducing atmosphere, each green ceramic body is heated to a temperature greater than or equal to 1100° C. and less than or equal to 1300° C. and kept warm for a time greater than or equal to 0.5 hour and less than or equal to 3 hours, so as to sinter each green ceramic body into a finished ceramic body.

[0023] As a preferred solution, the step S4 further includes:

[0024] Step S5, processing an external electrode on the electrode surface of the finished ceramic body, wherein the external electrode comprises a copper layer, a nickel layer and a tin layer arranged in sequence from the inside to the outside.

[0025] A multilayer ceramic capacitor is manufactured by using the above-mentioned method for manufacturing a multilayer ceramic capacitor.

[0026] The method for preparing a multilayer ceramic capacitor of the present invention has the following beneficial effects: firstly, a stacking strip and a protective strip are prepared, and then each of the protective strips is pressed onto the outside of the stacking strip; when preparing the stacking strip, an internal electrode unit is first processed on a ceramic film to form a ceramic electrode membrane, and then the multilayer ceramic electrode membrane is pressed into a stacked motherboard by a pressing process, and then the stacked motherboard is cut into stacking strips; when preparing the protective strip, a pressing process of a stacked motherboard is adopted to press the multilayer ceramic film into a protective sheet motherboard, and then the protective sheet motherboard is divided into a plurality of protective strips, and then the protective strip is attached to the outside of the stacking strip to form a green ceramic strip, and then the green ceramic strip is cut into a plurality of green ceramic bodies, and finally the green ceramic bodies are sintered. Since the protective strip is made of the same ceramic film and pressing process as the stacking strip, the stacking strip and the protective strip have the same sintering shrinkage, thereby avoiding the protective sheet from falling off the stacking strip when the green ceramic body is sintered. Moreover, the method for preparing a multilayer ceramic capacitor of the present invention facilitates mass processing of multilayer ceramic capacitors. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the current arrangement of the internal electrode unit on the ceramic film;

[0028] Figure 2 It is a schematic diagram of the arrangement of the internal electrode units on the ceramic film in the method for preparing the multilayer ceramic capacitor of the present invention;

[0029] Figure 3 It is a schematic diagram of the stacking method of the ceramic electrode membranes in the present invention to form a stacked motherboard and a schematic diagram of the arrangement method of the second cutting path L2;

[0030] Figure 4 It is a schematic diagram of the arrangement structure of the stacking area and the staggered area;

[0031] Figure 5 is a schematic diagram of the arrangement of the first cutting path;

[0032] Figure 6 Schematic diagram of the stacking method of ceramic thin film stacking as a protective sheet motherboard in the present invention

[0033] Figure 7 It is a schematic diagram of a cutting method for cutting a protection sheet motherboard into a plurality of protection strips;

[0034] Figure 8 It is a schematic diagram of the grinding method of the grinding protection sheet;

[0035] Fig. 9 is a schematic diagram of the arrangement of the conductive layer on the protective strip and the arrangement of the second cutting path L2;

[0036] Fig.10 It is a schematic diagram of the structure of a raw ceramic strip;

[0037] Fig.11 It is a schematic diagram of the structure of cutting a green ceramic strip into a plurality of green ceramic bodies;

[0038] Fig.12 is a schematic diagram of the structure of a finished ceramic body;

[0039] Fig.13 is a schematic structural diagram of a multilayer ceramic capacitor of the present invention;

[0040] Fig.14 is a flow chart of a method for preparing a multilayer ceramic capacitor of the present invention;

[0041] In the figure, G, interval, Z, first direction, X, second direction, Y, third direction, F, cutting surface, L1, first cutting path, L2, second cutting path, L3, third cutting path, 1, stacking strip, 11, ceramic electrode diaphragm, 111, ceramic film, 112, inner electrode unit, 12, stacking area, 13, staggered area, 2, protection sheet motherboard, 21, protection strip, 3, raw ceramic strip, 31, raw ceramic body, 4, conductive layer, 5, cylindrical grinding disc, 6, outer electrode, 7, inner electrode, 8, protection sheet. DETAILED DESCRIPTION

[0042] 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.

[0043] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "top", "bottom", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is 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 of 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, the "first" information may also be referred to as the "second" information, and similarly, the "second" information may also be referred to as the "first" information.

[0044] like Figures 2 to 14 As shown, a preferred embodiment of the method for preparing a multilayer ceramic capacitor of the present invention comprises the following steps:

[0045] Step S1, preparing the laminated strip 1 and the protective strip 21:

[0046] The preparation of the laminated strip 1 includes: processing an inner electrode unit 112 on a ceramic film 111 to form a ceramic electrode membrane 11; laminating the multilayer ceramic electrode membrane 11 into a laminated motherboard by a lamination process; and cutting the laminated motherboard into laminated strips 1;

[0047] The preparation of the protection strip 21 includes: using a laminate motherboard lamination process to press the multilayer ceramic film 111 into a protection sheet motherboard 2; dividing the protection sheet motherboard 2 into a plurality of protection strips 21;

[0048] Step S2 , pressing each protection strip 21 onto the outer side of the stacking strip 1 to form a green ceramic strip 3 .

[0049] Specifically, in this embodiment, the stacked strips 1 have a first direction Z, a second direction X, and a third direction Y that intersect each other. The stacking direction of the stacked strips 1 is the first direction Z, and protective strips 21 are pressed at both ends of the third direction Y of the stacked strips 1. The thickness of the ceramic film 111 in step S1 is 1 μm to 20 μm. The ceramic film 111 can be purchased or directly prepared. When preparing the ceramic film 111, ceramic powder, adhesive, and organic solvent are mixed to form a ceramic slurry, and the ceramic slurry is cast into the ceramic film 111. The material of the ceramic powder can be barium titanate, calcium zirconate, etc. The inner electrode unit 112 on the ceramic film 111 is made by printing nickel metal slurry and drying it. The multilayer ceramic electrode membranes 11 are stacked along the first direction Z and pressed into a laminated motherboard by a pressing process; in this process, the ceramic electrode membranes 11 are stacked in the following manner: each ceramic electrode membrane 11 is stacked in sequence along the first direction Z, and the ceramic film 111 without printing the internal electrode unit 112 is covered at both ends of the stacked structure along the first direction Z to obtain a laminated motherboard. The ceramic film 111 without printing the internal electrode unit 112 is covered at both ends of the first direction Z to cover the internal electrode unit 112, avoid exposing the internal electrode 7 at both ends of the stacked strip 1 in the first direction Z, and protect the internal electrode unit 112 from moisture intrusion and mechanical damage. The direction of pressing the multilayer ceramic electrode membranes 11 is the first direction Z, so that the direction of the pressing force is consistent with the stacking direction of the ceramic electrode membranes 11, which can prevent the internal electrode unit 112 from shifting in the second direction X or the third direction Y, thereby ensuring the capacitance and reliability of the multilayer ceramic capacitor.

[0050] In this embodiment, Figures 2 to 5 As shown, each ceramic electrode diaphragm 11 of the stacked motherboard has a plurality of internal electrode units 112 arranged at intervals along the second direction X. When the plurality of ceramic electrode diaphragms 11 are stacked along the first direction Z, the internal electrode units 112 of adjacent ceramic electrode diaphragms 11 are staggered by an appropriate distance in the second direction X.

[0051] When the laminated mother board is cut into laminated strips 1, the cutting path used is the first cutting path L1, the direction of the first cutting path L1 is arranged along the second direction X, the first cutting paths L1 are parallel to each other, and the distribution direction of the first cutting paths L1 is evenly spaced along the third direction Y. The distance of the internal electrode units 112 in the second direction X is approximately equal to twice the distance of the internal electrodes 7 in the second direction X, and the distance of the internal electrode units 112 in the third direction Y is greater than the distance of the internal electrodes 7 in the third direction Y. The internal electrode units 112 are arranged continuously in the third direction Y. The distribution range of the internal electrode units 112 in the third direction Y is relatively wide. There is no need to arrange a plurality of internal electrode units 112 at intervals in the third direction Y. Therefore, there will be no bulge-like protrusions on the laminated motherboard after pressing due to the interval between two adjacent internal electrodes 7. The surface of the laminated motherboard is flat after pressing, thereby ensuring the flatness of the surface of the multilayer ceramic capacitor. After the laminated motherboard is cut into laminated strips 1, the internal electrodes 7 are exposed at both ends of each laminated strip 1 in the third direction Y. The subsequent protective strips 21 are attached to the two ends of the laminated strip 1 in the third direction Y, thereby covering the exposed internal electrodes 7.

[0052] In order to further improve the shrinkage consistency of the protection strip 21 and the stacking strip 1 during sintering, in this embodiment, the stacking direction of the ceramic film 111 of the protection strip 21 in the green ceramic strip 3 is the same as the stacking direction of the ceramic electrode membrane 11 of the stacking strip 1 in the green ceramic strip 3. Specifically, Figure 6 As shown, when the protection sheet motherboard 2 is pressed by using the ceramic film 111, each ceramic film 111 is stacked along the first direction Z, and the angle between the direction of pressing the ceramic film 111 and the direction of stacking the ceramic film 111, i.e., the first direction Z, is less than or equal to 15°. If the angle is too large, the difference in sintering shrinkage between the stacking strip 1 and the protection strip 21 will be too large. When the protection sheet motherboard 2 is cut into the protection strips 21, it is cut along the third cutting path L3; as shown in FIG. Figure 7 As shown, the distribution direction of each third cutting path L3 is arranged at intervals along the third direction Y, and the length direction of each third cutting path L3 is parallel to the second direction X. The stacking direction of the ceramic film 111 of the protective strip 21 cut in this way is the same as the stacking direction of the ceramic electrode diaphragm 11 of the stacking strip 1, thereby avoiding the difference in shrinkage rate of the protective strip 21 and the stacking strip 1 during the sintering process due to anisotropy.

[0053] In this embodiment, the lamination process is a cold isostatic pressing process, the temperature of the liquid medium of the cold isostatic pressing is greater than or equal to 60°C and less than or equal to 90°C, and the pressure of the liquid medium is greater than or equal to 30MPa and less than or equal to 200MPa. In the present invention, the liquid medium of the cold isostatic pressing is water. When the water temperature is too low, the laminated motherboard cannot be fully pressed; when the water temperature is too high, the laminated motherboard will be severely deformed. When the pressure is too small, the laminated motherboard cannot be fully pressed; when the pressure is too large, the laminated motherboard will be severely deformed. The water temperature and pressure setting in this embodiment ensures the lamination quality of the laminated motherboard and the protective sheet motherboard 2.

[0054] In this embodiment, the same process is used to prepare the protective sheet motherboard 2 and the laminate motherboard, so that the density of the protective sheet motherboard 2 after the pressing process is roughly equal to the density of the laminate motherboard after the pressing process, so that the sintering shrinkage curves of the two become consistent. By setting the number of ceramic electrode membranes 11 of the laminate motherboard and the number of ceramic films 111 of the protective sheet motherboard 2, it can be ensured that the thickness of the protective sheet motherboard 2 after the pressing process is equal to the thickness of the laminate motherboard after the pressing process.

[0055] In this embodiment, preparing the protection strips 21 further includes: grinding each protection strip 21 to a thickness greater than or equal to 50 μm and less than or equal to 200 μm. If the thickness is too small, the moisture-proof and mechanical damage-proof effects of the protection strips 21 will be weakened; if the thickness is too large, it is not conducive to increasing the capacitance of the multilayer ceramic capacitor.

[0056] Specifically, the thickness of the protective strip 21 obtained by cutting alone is difficult to be as thin as required by the protective strip 21, so the thickness of the protective strip 21 is further reduced by grinding. Figure 8 As shown, when grinding the protection strip 21, the outer peripheral surface of the cylindrical grinding disc 5 is used as the grinding surface, the cylindrical grinding disc 5 is rotated with its central axis as the center, and the outer peripheral surface of the cylindrical grinding disc 5 is used to grind one end of the protection strip 21 in the third direction Y, and the cylindrical grinding disc 5 is rotated while being translated from one end of the protection strip 21 to the other end of the protection strip 21, so as to gradually reduce the thickness of the protection strip 21 along the third direction Y. In some embodiments, the flat surface of the cylindrical grinding disc 5 can also be used as the grinding surface to grind the protection strip 21.

[0057] Furthermore, in this embodiment, the thickness of the un-grinded protection strip 21 is 200 μm to 300 μm. If the thickness is too small, it is difficult to obtain a structurally complete protection strip 21 by cutting the protection sheet mother board 2; if the thickness is too large, the grinding time will be increased.

[0058] In order to improve the conductivity of the multilayer ceramic capacitor, in this embodiment, the cutting surface in step S3 forms a cut surface F; preparing the protective strip 21 also includes: processing a plurality of conductive layers 4 arranged at intervals along the length direction of the protective strip 21 on the grinding surface of the protective strip 21, and each conductive layer 4 is symmetrically arranged with each cut surface F as the center.

[0059] Specifically, Fig. 9 , Fig.11 As shown, the cut surface F is parallel to the YZ plane. In step S3, the green ceramic strip 3 is cut along the second cutting path L2, and the conductive layer 4 is arranged on the bonding surface of the protective strip 21 at intervals along the second direction X, and each protective strip 21 is arranged one by one corresponding to each cut surface F, and each cut surface F is located at the center of each conductive layer 4. The inner electrode units 112 of adjacent ceramic electrode membranes 11 are staggered at an appropriate distance in the second direction X; Figure 4 As shown, each inner electrode unit 112 in the stacking strip 1 is arranged to have a stacking area 12 and a staggered area 13 arranged along the second direction X, each inner electrode 7 in the stacking area 12 serves as the working part of the multilayer ceramic capacitor, and each inner electrode 7 in the staggered area 13 serves as the conductive part of the multilayer ceramic capacitor; in the current multilayer ceramic capacitor, the outer electrodes 6 are arranged at both ends of the second direction X of the finished ceramic body, and each inner electrode 7 contacts the outer electrode 6 through the portion exposed to the end of the first direction X, respectively. The contact quality between different inner electrodes 7 and the outer electrode 6 is different, which easily leads to differences in the conductivity of each inner electrode 7, affecting the capacitance of the multilayer ceramic capacitor. In this embodiment, the distribution distance of the conductive layer 4 in the second direction X is less than the distribution length of the staggered portion of the inner electrode 7 in the second direction X, that is, the conductive layer 4 only contacts the conductive portion of the inner electrode 7, and does not contact the working portion of the inner electrode 7. The conductive layer 4 contacts the portion of each inner electrode 7 exposed to the second direction Y, thereby playing the role of connecting each inner electrode 7 in parallel, and improving the consistency of the conductivity of each inner electrode 7.

[0060] In this embodiment, after step S3 and before step S4, the following steps are further included:

[0061] Step S31, heating each green ceramic body 31 in air to a temperature greater than or equal to 250° C. and less than or equal to 350° C. and keeping the temperature for a time greater than or equal to 0.5 hour and less than or equal to 3 hours; or heating each green ceramic body 31 in nitrogen to a temperature greater than or equal to 350° C. and less than or equal to 600° C. and keeping the temperature for a time greater than or equal to 2 hours and less than or equal to 6 hours, so as to discharge the binder in each green ceramic body 31. Discharging the binder can avoid the influence of the binder on sintering, which is beneficial to improving the sintering quality of the green ceramic body 31.

[0062] In this embodiment, step S4 includes: in a reducing atmosphere, heating each raw ceramic body 31 to a temperature greater than or equal to 1100° C. and less than or equal to 1300° C. and keeping the temperature for a period greater than or equal to 0.5 hour and less than or equal to 3 hours, so as to sinter each raw ceramic body 31 into a finished ceramic body.

[0063] After step S4, the following steps are also included:

[0064] Step S5, processing the outer electrode 6 on the electrode surface of the finished ceramic body, the outer electrode 6 includes a copper layer, a nickel layer and a tin layer arranged in sequence from the inside to the outside. Specifically, the cut surface F is the electrode surface of the finished ceramic body, and the copper metal slurry is coated on the electrode surface, and the copper metal slurry is sintered to form the copper layer of the outer electrode 6. Then, the nickel layer of the outer electrode 6 and the tin layer of the outer electrode 6 are sequentially formed on the copper layer of the outer electrode 6 by electroplating, and a multilayer ceramic capacitor is obtained.

[0065] like Fig.13 As shown, a preferred embodiment of the multilayer ceramic capacitor of the present invention is made by the above-mentioned preparation method of the multilayer ceramic capacitor, including a finished ceramic body and two external electrodes 6 arranged at two conductive ends of the finished ceramic body, the finished ceramic body has two internal electrodes 7 and two protective sheets 8, the two internal electrodes 7 are alternately stacked in the finished ceramic body, the two external electrodes 6 are respectively arranged at the two ends of the finished ceramic body opposite to each other along the second direction X, and the two protective sheets 8 are respectively located at the two ends of the finished ceramic body opposite to each other along the third direction Y.

[0066] In summary, the method for preparing a multilayer ceramic capacitor of the present invention first prepares a stacking strip 1 and a protective strip 21, and then presses each protective strip 21 on the outside of the stacking strip 1; when preparing the stacking strip 1, firstly, an inner electrode unit 112 is processed on a ceramic film 111 to form a ceramic electrode diaphragm 11, and then a pressing process is used to press the multilayer ceramic electrode diaphragm 11 into a stacked motherboard, and then the stacked motherboard is cut into stacking strips 1; when preparing the protective strip 21, a pressing process of a stacked motherboard is used to press the multilayer ceramic film 111 into a protective sheet motherboard 2, and then the protective sheet motherboard is pressed into the stacking strip 1. The protective sheet motherboard 2 is divided into a plurality of protective strips 21, and then the protective strips 21 are attached to the outside of the stacking strips 1 to form a raw ceramic strip 3, and then the raw ceramic strips 3 are cut into a plurality of raw ceramic bodies 31, and finally the raw ceramic bodies 31 are sintered. Since the protective strips 21 are made of the same ceramic film and pressing process as the stacking strips 1, the sintering shrinkage of the stacking strips 1 and the protective strips 21 are consistent, thereby preventing the protective sheet 8 from falling off the stacking strips 1 when sintering the raw ceramic bodies 31. Moreover, the preparation method of the multilayer ceramic capacitor of the present invention facilitates mass processing of multilayer ceramic capacitors.

[0067] 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 method for preparing a multilayer ceramic capacitor, characterized in that: The following steps are involved: Step S1, preparing a laminated strip (1) and a protective strip (21): The preparation of the stacked strip (1) comprises: processing an internal electrode unit (112) on a ceramic film (111) to form a ceramic electrode membrane (11); using a lamination process to press multiple layers of the ceramic electrode membrane (11) into a stacked mother board; and cutting the stacked mother board into stacked strips (1); The preparation of the protection strip (21) comprises: using the lamination process of the laminate mother board to press multiple layers of the ceramic film (111) into a protection sheet mother board (2); dividing the protection sheet mother board (2) into a plurality of protection strips (21); Step S2, pressing each of the protection strips (21) onto the outer side of the stacking strip (1) to form a green ceramic strip (3); Step S3, cutting the green ceramic strip (3) into a plurality of green ceramic bodies (31); Step S4, sintering the green ceramic body (31) into a finished ceramic body (32).

2. The method for preparing a multilayer ceramic capacitor according to claim 1, characterized in that: The stacking direction of the ceramic film (111) of the protective strip (21) in the green ceramic strip (3) is the same as the stacking direction of the ceramic electrode membrane (11) of the stacking strip (1) in the green ceramic strip (3).

3. The method for preparing a multilayer ceramic capacitor according to claim 1, characterized in that: The inner electrode units (112) are exposed at both ends of the laminated strip (1) in a width direction.

4. The method for preparing a multilayer ceramic capacitor according to claim 1, characterized in that: The pressing process is a cold isostatic pressing process, the liquid medium temperature of the cold isostatic pressing is greater than or equal to 60° C. and less than or equal to 90° C., and the liquid medium pressure is greater than or equal to 30 MPa and less than or equal to 200 MPa.

5. The method for preparing a multilayer ceramic capacitor according to claim 1, characterized in that: The preparation of the protection strips (21) further comprises: grinding each of the protection strips (21) to a thickness greater than or equal to 50 μm and less than or equal to 200 μm.

6. The method for preparing a multilayer ceramic capacitor according to claim 5, characterized in that: The cutting surface in step S3 forms a cutting surface (F); The preparation of the protective strip (21) further comprises: machining a plurality of conductive layers (4) on the grinding surface of the protective strip (21) and arranged at intervals along the length direction of the protective strip (21), wherein each of the conductive layers (4) is arranged symmetrically with each of the cut surfaces (F) as the center.

7. The method for preparing a multilayer ceramic capacitor according to claim 1, characterized in that: After step S3 and before step S4, the method further includes: Step S31, heating each of the green ceramic bodies (31) in air to a temperature greater than or equal to 250°C and less than or equal to 350°C and keeping the temperature therein for a period of greater than or equal to 0.5 hour and less than or equal to 3 hours; or heating each of the green ceramic bodies (31) in nitrogen to a temperature greater than or equal to 350°C and less than or equal to 600°C and keeping the temperature therein for a period of greater than or equal to 2 hours and less than or equal to 6 hours, so as to discharge the binder in each green ceramic body (31).

8. The method for preparing a multilayer ceramic capacitor according to claim 1, wherein: The step S4 comprises: In a reducing atmosphere, each raw ceramic body (31) is heated to a temperature greater than or equal to 1100° C. and less than or equal to 1300° C. and kept warm for a time greater than or equal to 0.5 hour and less than or equal to 3 hours, so as to sinter each raw ceramic body (31) into a finished ceramic body (32).

9. The method for preparing a multilayer ceramic capacitor according to claim 1, characterized in that: After step S4, the following steps are also included: Step S5: machining an external electrode (6) on the electrode surface of the finished ceramic body (32), wherein the external electrode (6) comprises a copper layer, a nickel layer and a tin layer arranged in sequence from the inside to the outside.

10. A multilayer ceramic capacitor, characterized in that: The multilayer ceramic capacitor is manufactured by the preparation method according to any one of claims 1 to 9.

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