Multilayer ceramic electronic components and their manufacturing methods

Abstract

To provide a multilayer ceramic electronic component and a manufacturing method for the same with which it is possible to prevent defects and heighten reliability.SOLUTION: A multilayer ceramic electronic component comprises: a ceramic element that includes a protective part having an end surface facing in a first direction, a plurality of peripheral surfaces concatenated to the end surface and extending along the first direction, and a ridge part having a recess extending along the first direction and connecting between the plurality of peripheral surfaces, and a function part which is located inward of the protective part; and an external electrode that includes an underlying film that covers the end surface, and a plating film which is formed on the underlying film. The function part includes a plurality of internal electrodes which is laminated in a second direction orthogonal to the first direction, and the ridge part is located outward of the edges of the plurality of internal electrodes in a third direction orthogonal to the first and second directions, when seen from the second direction.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a multilayer ceramic electronic component and a method for manufacturing the same.

Background Art

[0002] Multilayer ceramic electronic components such as multilayer ceramic capacitors include a ceramic body in which internal electrodes are laminated and external electrodes that cover each end face of the ceramic body. The external electrodes typically continuously cover from the end face to a part of a plurality of peripheral faces connected to the end face.

[0003] On the other hand, since the electrode material and the ceramic material constituting the external electrode have different linear expansion coefficients, stress accumulates in the external electrode due to heat treatment or heat generation after mounting, and defects such as cracks in the ceramic body or external electrode may occur.

[0004] Patent Document 1 discloses a ceramic electronic component having a fired electrode layer having first to fifth portions that are at least partially separated from each other from the viewpoint of preventing crack generation.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the configuration described in Patent Document 1, it is difficult to control the separation width of the first to fifth portions of the fired electrode layer, and it is easy to separate up to the Cu plating film covering it. When the Cu plating film is separated, insulation failure or the like may occur in the multilayer ceramic capacitor after the plating process, and it becomes difficult to ensure reliability.

[0007] In view of the above circumstances, the object of the present invention is to provide a multilayer ceramic electronic component and a method for manufacturing the same that can prevent defects and improve reliability. [Means for solving the problem]

[0008] To achieve the above objective, a multilayer ceramic electronic component according to one embodiment of the present invention comprises a ceramic body and an external electrode. The above ceramic body has a protective part and a functional part. The protective portion includes an end face facing a first direction, a plurality of circumferential surfaces connected to the end face and extending in the first direction, and a ridge having a recess extending along the first direction and connecting the plurality of circumferential surfaces. The above-mentioned functional unit is located inside the above-mentioned protective unit. The above-mentioned undercoat includes a first covering portion formed on the end face, a plurality of second covering portions formed on the plurality of circumferential surfaces, and a third covering portion formed on the recess and spaced apart at the edge from at least one of the plurality of second covering portions. The above-mentioned plating film continuously covers the first coating portion, the plurality of second coating portions, and the third coating portion.

[0009] Because the thermal expansion coefficients of the substrate film containing the electrode material and the ceramic body are different, stress is applied in different directions to each second coating portion due to heating and cooling. In the substrate film of the external electrode with the above configuration, the second coating portions on multiple circumferential surfaces and the third coating portion on the recesses are separated from each other. As a result, the influence of stress is interrupted in the discontinuous regions of the substrate film, making it difficult for stress to accumulate in the external electrode and the ceramic body. This prevents damage to the ceramic body due to such stress. Furthermore, because the ceramic body has recesses adjacent to its edges, the electrode material of the substrate film is more likely to remain in the recesses, minimizing the discontinuous regions of the substrate film. As a result, the plating film is continuously formed even on the discontinuous regions of the substrate film, preventing fracture of the entire external electrode.

[0010] The above functional unit has a plurality of internal electrodes stacked in a second direction perpendicular to the first direction, The ends of the multiple internal electrodes described above may be aligned with each other within a range of 0.5 μm in the third direction, where the ends are perpendicular to the first direction and the second direction. This ensures a sufficient proportion of the functional part within the ceramic substrate. Therefore, high-performance multilayer ceramic electronic components can be obtained without increasing their size.

[0011] A method for manufacturing a multilayer ceramic electronic component according to another embodiment of the present invention includes the step of manufacturing a ceramic body having a protective portion including an end face facing a first direction, a plurality of circumferential surfaces connected to the end face and extending in the first direction, and a ridge portion having a recess extending along the first direction and connecting the plurality of circumferential surfaces, and a functional portion disposed inside the protective portion. A conductive undercoat is formed, comprising a first coating portion formed on the end face, a plurality of second coating portions formed on each of the plurality of circumferential surfaces, and a third coating portion formed on the recess and spaced apart at the edge from at least one of the plurality of second coating portions. A plating film is formed that continuously covers the first coating portion, the plurality of second coating portions, and the third coating portion.

[0012] In the process of manufacturing the above ceramic body, A ceramic laminated chip is fabricated in which multiple internal electrodes are stacked in a second direction perpendicular to the first direction, and the multiple internal electrodes are exposed from the sides facing the first direction and a third direction perpendicular to the second direction. A first side margin portion is laminated on the above side surface, and a second side margin portion is laminated on the first side margin portion and has a greater thermal shrinkage rate than the first side margin portion. The above-mentioned ceramic laminated chip, the first side margin portion, and the second side margin portion may be fired. In this configuration, by being fired, the second side margin portion shrinks more than the first side margin portion. As a result, the outer edge of the second side margin portion is formed inward of the outer edge of the first side margin portion, and recesses are formed in these outer edges. Therefore, the ceramic green body having the above configuration can be easily manufactured.

[0013] The first side margin portion is formed by attaching a first ceramic sheet on the side surface. The second side margin portion may be formed by attaching a second ceramic sheet having a higher thermal shrinkage rate than the first ceramic sheet on the first ceramic sheet. Thereby, the first side margin portion and the second side margin portion can be easily formed.

Effect of the Invention

[0014] As described above, according to the present invention, it is possible to provide a multilayer ceramic electronic component capable of preventing defects and enhancing reliability, and a method for manufacturing the same.

Brief Description of the Drawings

[0015] [Figure 1] It is a perspective view of a multilayer ceramic capacitor according to an embodiment of the present invention. [Figure 2] It is a cross-sectional view taken along line A-A' of the multilayer ceramic capacitor. [Figure 3] It is a cross-sectional view taken along line B-B' of the multilayer ceramic capacitor. [Figure 4] It is a cross-sectional view taken along line C-C' of the multilayer ceramic capacitor. [Figure 5] It is an enlarged cross-sectional view of FIG. 4. [Figure 6] It is an enlarged cross-sectional view of a multilayer ceramic capacitor according to a comparative example of the above embodiment. [Figure 7] It is a flowchart showing an example of a method for manufacturing the multilayer ceramic capacitor. [Figure 8]It is a perspective view showing the manufacturing process of the above-mentioned multilayer ceramic capacitor. [Figure 9] It is a perspective view showing the manufacturing process of the above-mentioned multilayer ceramic capacitor. [Figure 10] It is a schematic cross-sectional view showing the manufacturing process of the above-mentioned multilayer ceramic capacitor. [Figure 11] It is a schematic cross-sectional view showing the manufacturing process of the above-mentioned multilayer ceramic capacitor. [Figure 12] It is a schematic cross-sectional view showing the manufacturing process of the above-mentioned multilayer ceramic capacitor. [Figure 13] It is a perspective view showing the manufacturing process of the above-mentioned multilayer ceramic capacitor. [Figure 14] It is a perspective view showing the manufacturing process of the above-mentioned multilayer ceramic capacitor.

Embodiments for Carrying out the Invention

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, an X-axis, a Y-axis, and a Z-axis that are orthogonal to each other are appropriately shown. The X-axis, Y-axis, and Z-axis are common throughout the drawings.

[0017] [Overall Configuration of Multilayer Ceramic Capacitor 10] Figs. 1 to 4 are views showing a multilayer ceramic capacitor 10 according to a first embodiment of the present invention. Fig. 1 is a perspective view of the multilayer ceramic capacitor 10. Fig. 2 is a cross-sectional view of the multilayer ceramic capacitor 10 taken along the line A-A' in Fig. 1. Fig. 3 is a cross-sectional view of the multilayer ceramic capacitor 10 taken along the line B-B' in Fig. 1. Fig. 4 is a cross-sectional view of the multilayer ceramic capacitor 10 taken along the line C-C' in Fig. 1.

[0018] The multilayer ceramic capacitor 10 includes a ceramic body 11 and two external electrodes 14. The two external electrodes 14 are respectively formed on the surface of the ceramic body 11.

[0019] The ceramic body 11 has a volume-forming portion 16 and a protective portion 17. The protective portion 17 constitutes the peripheral edge of the ceramic body 11 and has two end faces 11a facing in the X-axis direction, two side faces 11b facing in the Y-axis direction, two main faces 11c facing in the Z-axis direction, and a ridge portion 11e connecting the main faces 11c and the side faces 11b. The side faces 11b and the main faces 11c constitute a plurality of circumferential surfaces in this embodiment. The end faces 11a, side faces 11b and main faces 11c are, for example, composed of substantially flat surfaces, but may also be rounded.

[0020] The protective portion 17, in detail, includes a cover portion 18 located on the Z-axis side of the volume forming portion 16, a side margin portion 19 located on the Y-axis side of the volume forming portion 16, and an end margin portion 20 located on the X-axis side of the volume forming portion 16.

[0021] The capacitance forming section 16 is located inside the protective section 17 and constitutes the functional section in this embodiment. The capacitance forming section 16 consists of a plurality of first internal electrodes 12 and a plurality of second internal electrodes 13, which are stacked in the Z-axis direction via a ceramic layer 15 (see Figure 2). Both the internal electrodes 12 and 13 are sheet-like structures extending along the XY plane and are arranged alternately along the Z-axis direction.

[0022] The internal electrodes 12 and 13 are each formed from a good electrical conductor and function as internal electrodes of the multilayer ceramic capacitor 10. As the good electrical conductors forming the internal electrodes 12 and 13, metals or alloys mainly composed of nickel (Ni), copper (Cu), palladium (Pd), platinum (Pt), silver (Ag), and gold (Au) can be used.

[0023] As shown in Figure 2, the internal electrodes 12 and 13 are connected to the external electrode 14 that covers the end face 11a. The first internal electrode 12 is drawn out to one end face 11a of the ceramic body 11, for example, and connected to one of the external electrodes 14. The second internal electrode 13 is drawn out to the other end face 11a and connected to the other external electrode 14.

[0024] The ceramic layer 15 is formed of dielectric ceramics. In the multilayer ceramic capacitor 10, high dielectric ceramics are used to increase the capacitance of each ceramic layer 15 between the internal electrodes 12 and 13. Examples of high dielectric ceramics include perovskite materials containing barium (Ba) and titanium (Ti), such as barium titanate (BaTiO3).

[0025] Furthermore, the dielectric ceramics may also be made of materials other than barium titanate, such as strontium titanate (SrTiO3), calcium titanate (CaTiO3), magnesium titanate (MgTiO3), calcium zirconate (CaZrO3), calcium zirconate titanate (Ca(Zr,Ti)O3), barium zirconate (BaZrO3), or titanium oxide (TiO2).

[0026] The protective layer 17 is also formed from dielectric ceramics. The material forming the protective layer 17 can be any insulating ceramic, but using a material with the same composition as the ceramic layer 15 improves manufacturing efficiency and suppresses internal stress in the ceramic body 11.

[0027] The external electrode 14 has a base film 21 formed to cover the end face 11a and a plating film 22 formed on the base film 21. The base film 21 is composed of, for example, a baked film made by firing a conductive paste or a sputtered film. The plating film 22 is a film formed by electroplating. Each film of the external electrode 14 is made of a metal or alloy whose main components are, for example, nickel (Ni), copper (Cu), tin (Sn), palladium (Pd), platinum (Pt), silver (Ag), gold (Au), etc.

[0028] The undercoat 21 of the external electrode 14 has an end face covering portion 25 formed on the end face 11a, a main face covering portion 26c formed on the main face 11c, a side face covering portion 26b formed on the side surface 11b, and a recess covering portion 27 formed on the recess 23, which will be described later. In this embodiment, the end face covering portion 25 constitutes a first covering portion, the main face covering portion 26c and the side face covering portion 26b constitute a plurality of second covering portions, and the recess covering portion 27 constitutes a third covering portion.

[0029] In this embodiment, the side covering portion 26b and the main covering portion 26c of the base film 21 are separated from the recessed covering portion 27 at the ridge portion 11e, and this interrupted portion is also covered by the plating film 22. The configuration near the ridge portion 11e will be described in detail below.

[0030] [Detailed configuration of multilayer ceramic capacitor 10] Figure 5 is an enlarged view of Figure 4, showing the structure of the ridge 11e and its surroundings. Figure 5 shows the structure of one ridge 11e and its surroundings, but the same applies to the structures of the other ridges 11e and their surroundings.

[0031] The ridge portion 11e has a recess 23 extending along the X-axis direction. An outwardly convex edge portion 24 is formed on the outer edge of the recess 23, forming the boundary between the main surface 11c or side surface 11b and the recess 23. A pair of edge portions 24 are formed, flanking one recess 23.

[0032] The recess 23 is the portion that is recessed inward from the straight line Le when a straight line Le is drawn connecting the two edges 24 in a cross-section cut in the Z-axis direction. Small steps or irregularities that do not protrude from the straight line Le may be formed within the recess 23.

[0033] As described above, the main surface covering portion 26c of the base film 21 is formed on the main surface 11c, and the side surface covering portion 26b of the base film 21 is formed on the side surface 11b. The recess covering portion 27 of the base film 21 is formed on the recess 23. The recess covering portion 27 is spaced apart at its edge 24 from at least one of the main surface covering portion 26c and the side surface covering portion 26b. In this embodiment, the recess covering portion 27 is spaced apart from both the main surface covering portion 26c and the side surface covering portion 26b.

[0034] In this embodiment, the plating film 22 has a multi-layer structure. The plating film 22 has an interlayer 28 formed on the base film 21 and a surface film 29 formed on the interlayer 28. The interlayer 28 and the surface film 29 continuously cover the entire end face covering portion 25, main surface covering portion 26c, side surface covering portion 26b, and recessed covering portion 27 of the base film 21. The metal materials constituting the interlayer 28 and the surface film 29 may be the same or different. The metal materials may be selected from, for example, copper, nickel, tin, or alloys thereof.

[0035] The undercoat 21 has a main surface covering portion 26c, a side covering portion 26b, and a recessed covering portion 27 that are spaced apart from each other, thereby preventing defects such as cracks in the ceramic body 11 caused by temperature changes.

[0036] The electrode material constituting the base film 21 and the ceramic material constituting the ceramic body 11 have different coefficients of thermal expansion. As a result, when the base film 21 cools down after heating following firing or mounting, the base film 21 shrinks more than the ceramic body 11, generating tensile stress in the base film 21. On the other hand, compressive stress is generated in the ceramic body 11 due to this tensile stress.

[0037] Tensile stress is generated in the main surface covering portion 26c of the base film 21, for example, in the direction in the Y-axis direction. Tensile stress is generated in the side covering portion 26b of the base film 21, for example, in the direction in the Z-axis direction. As a result, tensile stress is generated in the base film 21 near the edge portion 11e, in directions different from those of the base film 21.

[0038] In this embodiment, the main surface coating portion 26c and the side coating portion 26b are spaced apart. As a result, even if the tensile stress described above occurs, stress does not accumulate in the base film 21. Therefore, it is possible to prevent large compressive stress from occurring in the ceramic body 11, which would cause defects such as cracks in the ceramic body 11.

[0039] Furthermore, in this embodiment, a recess covering portion 27 is formed on the recess 23. The recess covering portion 27 keeps the electrode material of the base film 21 within the recess 23, minimizing the spacing between the base films 21.

[0040] Figure 6 is a cross-sectional view showing the configuration of a multilayer ceramic capacitor 10A in a comparative example, and is an enlarged view showing the same part as in Figure 5. In the multilayer ceramic capacitor 10A, the protective portion 17A does not have a recess, and the side surface 11Ab and the main surface 11Ac of the ceramic body 11A are connected at the ridge portion 11Ae. The ridge portion 11Ae is composed of a curved surface that is convex outward from the ceramic body 11A.

[0041] When attempting to separate the undercoat 21A of the ceramic body 11A at the ridge portion 11Ae, the adjacent main surface coating portion 26Ac and the side coating portion 26Ab are separated. Because the ridge portion 11Ae is sharply curved at an angle close to a right angle, it is difficult to control the separation width between them. As a result, the separation width between the main surface coating portion 26Ac and the side coating portion 26Ab becomes large, and the ridge portion 11Ae tends to protrude from between them.

[0042] When a plating film 22A is formed on this undercoat 21A, the plating film 22A cannot cover the ridge portion 11Ae, resulting in a discontinuous state on the ridge portion 11Ae. As a result, a gap is formed between the ridge portion 11Ae of the ceramic body 11A and the external electrode 14A. If moisture from the atmosphere enters through this gap, the multilayer ceramic capacitor 10A will experience insulation failure, making it difficult to ensure reliability.

[0043] On the other hand, in this embodiment shown in Figure 5, the electrode material remaining in the recess 23 forms the recess covering portion 27. This restricts the spacing between the main surface covering portion 26c or the side covering portion 26b of the base film 21 and the recess covering portion 27, allowing the plating film 22 to continuously cover the entire base film 21. This prevents the formation of gaps between the external electrode 14 and the ceramic body 11, thereby preventing insulation failure. Consequently, the reliability of the multilayer ceramic capacitor 10 can be improved.

[0044] Furthermore, in the comparative example of the ceramic body 11A, one method to ensure that the ridge portion 11Ae is reliably covered by the external electrode 14A is to round the corners of the ridge portion 11Ae by barrel polishing or the like. However, as will be described later, when the side margin portion is formed by attaching a ceramic sheet, the ceramic sheet may peel off when barrel polishing is performed, and defects are likely to occur in the side margin portion.

[0045] In this embodiment, as described in the manufacturing method below, the shape of the ridge portion 11e can be optimized without barrel polishing, and defects such as peeling of the side margin portion 19 can be prevented. This further enhances the reliability of the multilayer ceramic capacitor 10.

[0046] [Manufacturing method for multilayer ceramic capacitor 10] Figure 7 is a flowchart illustrating the manufacturing method of the multilayer ceramic capacitor 10. Figures 8 to 14 schematically show the manufacturing process of the multilayer ceramic capacitor 10. The manufacturing method of the multilayer ceramic capacitor 10 will be explained below in accordance with Figure 7, with reference to Figures 8 to 14 as appropriate.

[0047] (Step S01: Fabrication of ceramic multilayer chip C) In step S01, an unfired ceramic laminated chip (laminated chip) C is produced by stacking ceramic sheets 101 and 102 for forming the volume forming section 16 and a ceramic sheet 103 for forming the cover section 18, and then cutting the stacked sheets.

[0048] The ceramic sheets 101, 102, and 103 shown in Figure 8 are composed of unfired dielectric green sheets containing a ceramic material made of dielectric ceramics, an organic binder, and other additives. An unfired first internal electrode 112 corresponding to the first internal electrode 12 is formed on ceramic sheet 101. An unfired second internal electrode 113 corresponding to the second internal electrode 13 is formed on ceramic sheet 102. No internal electrodes are formed on ceramic sheet 103.

[0049] Each internal electrode 112, 113 has multiple strip-shaped electrode patterns that cross a cutting line Lx parallel to the X-axis direction and extend along a cutting line Ly parallel to the Y-axis direction. These internal electrodes 112, 113 are formed by applying a conductive paste to ceramic sheets 101, 102 by printing or the like.

[0050] As shown in Figure 8, ceramic sheets 101 and 102 are stacked alternately in the Z-axis direction. The stack of ceramic sheets 101 and 102 corresponds to the volume-forming portion 16 and the end margin portion 20. Ceramic sheet 103 is stacked on the upper and lower surfaces of the stack of ceramic sheets 101 and 102 in the Z-axis direction. The stack of ceramic sheets 103 corresponds to the cover portion 18. The number of layers of ceramic sheets 101, 102, and 103 can be adjusted as needed.

[0051] Next, the laminate of ceramic sheets 101, 102, and 103 is pressed together from the Z-axis direction and cut along the cutting lines Lx and Ly. This produces the laminated chip C shown in Figure 9.

[0052] The multilayer chip C has an unfired capacitance forming portion 116 on which unfired internal electrodes 112 and 113 are formed, an unfired cover portion 118, and an unfired end margin portion 120. The multilayer chip C has a side surface Cb which is a cut surface corresponding to the cutting line Lx, and an end surface Ca which is a cut surface corresponding to the cutting line Ly. The ends of the unfired internal electrodes 112 and 113 are exposed from the side surface Cb.

[0053] (Step 02: Formation of side margin portion 119) In step S02, a side margin portion 119 is formed on the side surface Cb of the stacked chip C. An example of the formation method is shown below.

[0054] First, as shown in Figure 10, a laminated sheet S, which is a stack of ceramic sheets, is placed on a flat elastic member E, and the other side Cb of the laminated chip C, which has one side Cb held by tape T, is brought to face the laminated sheet S.

[0055] In this embodiment, the laminated sheet S has a laminated structure of a first ceramic sheet 104, a second ceramic sheet 105, and a third ceramic sheet 106 for side margin formation. Each ceramic sheet 104, 105, and 106, like ceramic sheets 101, 102, and 103, contains a ceramic material, an organic binder, and other additives.

[0056] The second ceramic sheet 105 has a greater thermal shrinkage rate than the first ceramic sheet 104. Furthermore, the third ceramic sheet 106 has a greater thermal shrinkage rate than the second ceramic sheet 105. The thermal shrinkage rate can be adjusted by adjusting the amount of organic binder and additives.

[0057] Next, as shown in Figure 11, the laminated sheet S is attached to the side Cb of the laminated chip C by punching it out with the side Cb. Specifically, the laminated chip C is strongly pressed against the laminated sheet S in the Y-axis direction. As a result, the laminated chip C, together with the laminated sheet S, sinks locally and deeply into the elastic member E. At this time, a shear force acts on the laminated sheet S along the outer edge of the side Cb, and when this shear force exceeds the shear strength of the laminated sheet S, the laminated sheet S is punched out.

[0058] Then, as shown in Figure 12, a portion of the laminated sheet S that has sunk together with the laminated chip C is separated. This forms a first side margin portion 119a laminated on the side surface Cb and a second side margin portion 119b laminated on the first side margin portion 119a. Furthermore, in this embodiment, a third side margin portion 119c is formed on the second side margin portion 119b. As a result, an unfired side margin portion 119, including the first side margin portion 119a, the second side margin portion 119b, and the third side margin portion 119c, is formed on the side surface Cb of the laminated chip C.

[0059] Similarly, a side margin portion 119 is formed on the other side Cb. This produces the unfired ceramic body 111 shown in Figure 13. At this stage, the recess 23 is not formed on the ridge portion 111e between the main surface 111c and the side surface 111b.

[0060] (Step S03: Firing) In step S03, the ceramic body 11 of the multilayer ceramic capacitor 10 shown in Figures 14 and 1-3 is fabricated by firing the ceramic body 111 obtained in step S02. The firing temperature in step S04 can be determined based on the sintering temperature of the ceramic body 111. Furthermore, firing can be carried out, for example, under a reducing atmosphere or a low oxygen partial pressure atmosphere.

[0061] During firing, each side margin section 119a, 119b, and 119c shrinks at a different rate. Specifically, the second side margin section 119b shrinks more than the first side margin section 119a, and the third side margin section 119c shrinks more than the second side margin section 119b.

[0062] As a result, as shown in Figure 14, a gentle step or slope is formed on the edge portion 11e of the ceramic body 11. The outer edges of each side margin portion 119a, 119b, and 119c contract inward in the Z-axis direction in this order, forming a recess 23. The outer edge of the side surface Cb of the laminated chip C forms the edge portion 24 on the main surface 11c side. The outer edge of the third side margin portion 119c forms the edge portion 24 on the side surface 11b side.

[0063] In Figure 14, the regions corresponding to each side margin section 119a, 119b, and 119c in the side margin section 19 are shown by dashed lines, but after firing, the boundaries become almost invisible.

[0064] (Step S04: Formation of the undercoat) In step S04, a conductive undercoat 21 is formed, which includes an end face covering portion 26a formed on the end face 11a, a side covering portion 26b formed on the side surface 11b, a main surface covering portion 26c formed on the main surface 11c, and a recess covering portion 27 formed on the recess 23 and spaced apart from the side covering portion 26b and the main surface covering portion 26c.

[0065] Specifically, first, unfired electrode material is applied to the end face 11a, and also to the side surface 11b, main surface 11c, and part of the ridge portion 11e that are connected to the end face 11a. The application method is, for example, the dipping method. In the dipping method, the end face 11a side of the ceramic body 11 is immersed in a dipping tank containing electrode material such as conductive paste. This allows the unfired electrode material to be applied to the side surface 11b, main surface 11c, and recess 23 almost simultaneously with the end face 11a.

[0066] The unfired electrode material is applied thinly so that the recessed coating portion 27, the side coating portion 26b, and the main surface coating portion 26c are spaced apart from each other after firing. However, they do not need to be spaced apart at the time of application. The thickness of the electrode material can be adjusted by the immersion time, the withdrawal speed, the viscosity of the electrode material, etc.

[0067] Furthermore, the method for forming the undercoat is not limited to the dipping method; for example, printing, sputtering, or a combination of these methods may also be used.

[0068] Next, the unfired electrode material is fired. The firing can be performed, for example, under a reducing atmosphere or a low oxygen partial pressure atmosphere. During firing, the electrode material formed on each surface shrinks due to heat. The shrinkage rate of the electrode material is greater than that of the ceramic body 11. As a result, the electrode material applied to each surface generates tensile stress in the direction away from the edge portion 11e. This causes the recessed covering portion 27, the side covering portion 26b, and the main surface covering portion 26c to be formed separated from each other.

[0069] (Step S05: Plating film formation) In step S05, a plating film 22 is formed that continuously covers the end face covering portion 26a, the side covering portion 26b, the main surface covering portion 26c, and the recessed covering portion 27. Specifically, the multilayer ceramic capacitor 10, on which the base film 21 has been formed, is immersed in a plating solution corresponding to the interlayer film 28 and the surface film 29, respectively, to perform electrolytic plating. This forms a plating film 22 having multiple layers of interlayer film 28 and surface film 29.

[0070] Based on the above, the multilayer ceramic capacitor 10 shown in Figures 1 to 3 is manufactured. In this embodiment, by adding the side margin portion 119 to the multilayer chip C, the positions of the ends of the internal electrodes 112 and 113 are aligned with each other within a range of 0.5 μm in the Y-axis direction. This increases the proportion of the volume occupied by the capacitance forming portion 16 within the ceramic body 11, making it possible to increase the capacitance without increasing the size of the multilayer ceramic capacitor 10.

[0071] [Other embodiments] Although various embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the present invention.

[0072] The number of ceramic sheets forming each side margin portion 19 is not limited to three. For example, by using two to four ceramic sheets to form the side margin portion 19, it is possible to form recesses 23 of a desired shape and prevent problems such as peeling of the side margin portion 19 after application.

[0073] For example, in the above embodiment, it was explained that an unfired side margin portion 119 is formed by attaching a laminated sheet S in which different ceramic sheets are stacked, but multiple ceramic sheets may also be attached one by one.

[0074] Furthermore, the method of attaching the ceramic sheet is not limited to punching out the sheet; a ceramic sheet pre-cut to a predetermined size may also be attached to the side Cb.

[0075] Alternatively, the side margin portion 19 may be formed by layering ceramic materials with different thermal shrinkage rates onto the side surface Cb of the laminated chip C. This also allows for the formation of a laminated structure with multiple side margin portions having different thermal shrinkage rates.

[0076] Furthermore, a recess can be formed by creating the cover portion 18 from multiple ceramic sheets with different thermal shrinkage rates. In this case, multiple ceramic sheets with side margins formed around the internal electrode are stacked, and multiple ceramic sheets with gradually increasing thermal shrinkage rates are stacked above and below in the Z-axis direction. This creates a ridge portion including a recess on the outer edge of the ceramic sheet used to form the cover portion.

[0077] Furthermore, the method is not limited to forming recesses by thermal shrinkage of the ceramic material; recesses may also be formed by grinding the edges of a rectangular parallelepiped ceramic body.

[0078] In the above embodiment, a multilayer ceramic capacitor 10 was described as an example of a multilayer ceramic electronic component, but the present invention is applicable to all multilayer ceramic electronic components in which ceramic layers and internal electrodes are stacked. Examples of such multilayer ceramic electronic components include chip varistors, chip thermistors, and multilayer inductors. [Explanation of Symbols]

[0079] 10…Multilayer ceramic capacitor 11…Ceramic base 11a...end face 11b...side 11c…main surface 11e…Ridge 12,13…Internal electrode 14...External electrode 21…Undercoat 22…Plating film 23…recess 24... Edge 25...First covering part (end face covering part) 26b, 26c...Second covering part (side covering part, main surface covering part) 27...Third covering portion (recessed covering portion)

Claims

1. A ceramic body having a protective portion including an end face facing a first direction, a plurality of circumferential surfaces connected to the end face and extending in the first direction, and a ridge having a recess extending along the first direction and connecting the plurality of circumferential surfaces, and a functional portion disposed inside the protective portion, An external electrode having a base film formed on the end face and a plating film formed on the base film, It is equipped with, The functional part has a plurality of internal electrodes stacked in a second direction perpendicular to the first direction, The aforementioned ridge portion, when viewed from the second direction, is located outside the ends of the plurality of internal electrodes in the third direction perpendicular to the first and second directions. The recess is recessed toward the functional portion in a cross-section including the second and third directions, more so than a virtual straight line tangent to the circumferential edge along the second direction and the circumferential edge along the third direction. The aforementioned undercoat includes a plurality of second covering portions formed on the plurality of circumferential surfaces, and a third covering portion formed on the recess and spaced apart from both of the plurality of second covering portions. The aforementioned plating film continuously covers the plurality of second and third coating portions in a multilayer ceramic electronic component.

2. A ceramic body is manufactured having a protective portion including an end face facing a first direction, a plurality of circumferential surfaces connected to the end face and extending in the first direction, and ridges having recesses extending along the first direction and connecting the plurality of circumferential surfaces, and a functional portion disposed inside the protective portion. A base film is formed on the end surface, A plating film is formed on the aforementioned undercoat, The functional part has a plurality of internal electrodes stacked in a second direction perpendicular to the first direction, The aforementioned ridge portion, when viewed from the second direction, is located outside the ends of the plurality of internal electrodes in the third direction perpendicular to the first and second directions. The recess is recessed toward the functional portion in a cross-section including the second and third directions, more so than a virtual straight line tangent to the circumferential edge along the second direction and the circumferential edge along the third direction. The aforementioned undercoat includes a plurality of second covering portions formed on the plurality of circumferential surfaces, and a third covering portion formed on the recess and spaced apart from both of the plurality of second covering portions. The plating film continuously covers the plurality of second coating portions and the third coating portions, a method for manufacturing a multilayer ceramic electronic component.

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