Multilayer ceramic capacitor

Abstract

The present invention provides a multilayer ceramic capacitor in which it is possible to impart moisture resistance to a terminal electrode, while maintaining good adhesion between the terminal electrode and a ceramic element. Disclosed is a multilayer ceramic capacitor 1 wherein: an external electrode film 22 contains at least a first glass which is composed of at least one of a barium-boron-silicon-based glass, a strontium-boron-silicon-based glass and a barium-strontium-boron-silicon-based glass, and a second glass which is composed of a bismuth-based glass; the first glass and the second glass form glass domains in the external electrode film 22; and if those exposed in the surface 42 of the external electrode film 22 but not exposed in the interface 40 between the external electrode film 22 and a ceramic element 2 among the glass domains are defined as first glass domains 52, and those not exposed in the surface 42 of the external electrode film 22 but exposed in the interface 40 between the external electrode film 22 and the ceramic element 2 are defined as second glass domains 50, the concentration ratio of bismuth to silicon is higher in portions of the first glass domains 52 exposed in the surface 42 of the external electrode film 22 than in portions of the second glass domains 50 exposed in the interface 40 between the external electrode film 22 and the ceramic element 2.

Description

Technical Field

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[0001] The present invention relates to a multilayer ceramic capacitor.

Background Art

[0002] As a method for manufacturing a terminal electrode of a multilayer ceramic capacitor, there is a method in which a conductive paste in which conductive powder such as copper and glass frit powder are dispersed in a vehicle is applied to a ceramic body, dried, and fired at a high temperature to form a terminal electrode electrically joined to an internal electrode layer. Patent Document 1 describes a method using glass frit powder containing barium.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Barium-boron-silicon-based glass can have a lower softening point than boron-silicon-based glass by containing barium. When the softening point is lowered, a dense film can be formed.

[0005] Also, barium-boron-silicon-based glass is less likely to form a reaction layer at the interface with the ceramic body. Specifically, when the ceramic body contains barium, barium-boron-silicon-based glass suppresses the movement of barium from the ceramic body due to the glass containing barium, making it difficult to form a reaction layer. Therefore, barium-boron-silicon-based glass can achieve good adhesion with the ceramic body.

[0006] However, barium-boron-silicon-based glass has poor moisture resistance and may deteriorate or dissolve when exposed to acidic plating solutions. If the glass deteriorates, the plating solution may penetrate into the terminal electrodes. This penetration of the plating solution into the terminal electrodes can cause reflow defects. Furthermore, the moisture resistance of the terminal electrodes may decrease, reducing the reliability of the multilayer ceramic capacitor.

[0007] The above describes the challenges encountered when using barium-boron-silicon glass, but similar challenges were also encountered with strontium-boron-silicon glass and barium-strontium-boron-silicon-based glass.

[0008] Therefore, the present invention aims to provide a multilayer ceramic capacitor that can provide moisture resistance to the terminal electrodes while maintaining good adhesion between the terminal electrodes and the ceramic body.

[0009] The multilayer ceramic capacitor of the present invention comprises a ceramic body having a first main surface and a second main surface facing each other in the height direction, a first side surface and a second side surface facing each other in the width direction perpendicular to the height direction, and a first end surface and a second end surface facing each other in the length direction perpendicular to the height direction and width direction, and a terminal electrode provided on the ceramic body and connected to a part of the internal electrode layer, wherein the terminal electrode includes an external electrode film in contact with the ceramic body, and the external electrode film is at least a barium-boron-silicon glass, or a strontium-boron-silicon glass, or a barium-strontium-boron-silicon glass film The material comprises a first glass consisting of at least one of the following, and a second glass consisting of a bismuth-based glass, wherein the first glass and the second glass form glass domains within the external electrode film, and the glass domains exposed on the surface of the external electrode film but not exposed at the interface of the external electrode film with the ceramic body are designated as the first glass domains, and the glass domains not exposed on the surface of the external electrode film but exposed at the interface of the external electrode film with the ceramic body are designated as the second glass domains. In this case, the concentration ratio of bismuth to silicon is higher in the portion of the first glass domain exposed on the surface of the external electrode film than in the portion of the second glass domain exposed at the interface of the external electrode film with the ceramic body. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a multilayer ceramic capacitor that can impart moisture resistance to the terminal electrodes while maintaining good adhesion between the terminal electrodes and the ceramic body. [Brief explanation of the drawing]

[0011] [Figure 1] This is a perspective view of the multilayer ceramic capacitor of this embodiment. [Figure 2] This is a cross-sectional view taken along line II in Figure 1. [Figure 3] This is a cross-sectional view taken along line II-II in Figure 1. [Figure 4] This is a cross-sectional view of the LT (Longitudinal Transverse) section near the second end face of a multilayer ceramic capacitor. [Figure 5] This figure shows a scanning electron microscope image of the external electrode film. [Figure 6] This figure shows scanning electron microscope images of other external electrode films. [Figure 7] This diagram shows a method for evaluating adhesion performance. [Modes for carrying out the invention]

[0012] Embodiments for carrying out the invention will be described with reference to Figure 1. Figure 1 is a perspective view of a multilayer ceramic capacitor 1 according to an embodiment of the present invention. Figure 1 shows a so-called two-terminal multilayer ceramic capacitor. The multilayer ceramic capacitor 1 of the present invention is not limited to a two-terminal multilayer ceramic capacitor. The multilayer ceramic capacitor 1 of the present invention may be a multi-terminal multilayer ceramic capacitor, such as a three-terminal capacitor.

[0013] The multilayer ceramic capacitor 1 includes a ceramic element 2 and terminal electrodes. The terminal electrodes include a first terminal electrode 20 and a second terminal electrode 21.

[0014] The ceramic body 2 includes multiple stacked dielectric layers and multiple internal electrode layers. The shape of the ceramic body 2 is approximately a rectangular parallelepiped.

[0015] In the ceramic substrate 2, the direction in which the dielectric layer and the internal electrode layer are stacked is defined as the height direction T. The direction perpendicular to the height direction T is defined as the width direction W. The direction perpendicular to both the height direction T and the width direction W is defined as the length direction L.

[0016] In the ceramic body 2, of the two surfaces facing each other in the height direction T, one surface is defined as the first main surface 3, and the remaining one surface is defined as the second main surface 4. In the ceramic body 2, of the two surfaces facing each other in the width direction W, one surface is defined as the first side surface 5, and the remaining one surface is defined as the second side surface 6. In the ceramic body 2, of the two surfaces facing each other in the length direction L, one surface is defined as the first end surface 7, and the remaining one surface is defined as the second end surface 8.

[0017] Regarding the cross-section of the ceramic body 2, the cross-section taken along the line I-I in FIG. 1 is referred to as the LT cross-section. Regarding the cross-section of the ceramic body 2, the cross-section taken along the line II-II in FIG. 1 is referred to as the WT cross-section.

[0018] The portion where three surfaces of the ceramic body 2 intersect is referred to as the corner portion of the ceramic body 2. The portion where two surfaces of the ceramic body 2 intersect is referred to as the ridge line portion of the ceramic body 2. It is preferable that the corner portion and the ridge line portion are rounded.

[0019] The total number of dielectric layers laminated on the ceramic body 2 is preferably not less than 15 and not more than 2000. The main material of the dielectric layer is a ceramic material. Examples of the ceramic material are dielectric ceramics mainly composed of barium titanate, calcium titanate, strontium titanate, calcium zirconate, etc. The ceramic material may be a dielectric ceramic in which auxiliary components such as manganese compounds, iron compounds, chromium compounds, cobalt compounds, nickel compounds, etc. are added to these main components.

[0020] The thickness of one layer of the dielectric layer is preferably not less than 0.3 μm and not more than 10 μm.

[0021] Based on FIG. 2, the division in the length direction L of the ceramic body 2 will be described. FIG. 2 is a cross-sectional view taken along the line I-I in FIG. 1. The ceramic body 2 can be divided in the height direction T into a first main surface side outer layer portion 10, an effective portion 11, and a second main surface side outer layer portion 12.

[0022] The first main surface-side outer layer portion 10 is the portion between the internal electrode layer closest to the first main surface 3 and the first main surface 3. The effective portion 11 is the portion where the internal electrode layers face each other. The second main surface-side outer layer portion 12 is the portion between the internal electrode layer closest to the second main surface 4 and the second main surface 4.

[0023] Of the dielectric layers, the dielectric layers located in the first main surface-side outer layer portion 10 and the second main surface-side outer layer portion 12 are defined as the outer dielectric layer 30. Of the dielectric layers, the dielectric layer located in the effective portion 11 is defined as the inner dielectric layer 31.

[0024] The size of the ceramic body 2 is not particularly limited. The length L of the ceramic body is preferably 0.2 mm or more and 10 mm or less. The length W of the ceramic body 2 is preferably 0.1 mm or more and 5 mm or less. The length T of the ceramic body 2 is preferably 0.1 mm or more and 5 mm or less.

[0025] The division of the ceramic body 2 in the longitudinal direction L will be explained. The ceramic body 2 can be divided in the longitudinal direction L into a first end face side outer layer portion 13, a longitudinally opposing portion 14, and a second end face side outer layer portion 15.

[0026] The longitudinally opposed portion 14 is the portion where two internal electrode layers face each other in the height direction T. The first end face side outer layer portion 13 is the portion between the longitudinally opposed portion 14 and the first end face 7. The second end face side outer layer portion 15 is the portion between the longitudinally opposed portion 14 and the second end face 8.

[0027] The longitudinally opposed portion 14 corresponds to the opposing electrode portion of the internal electrode layer. The first end-face side outer layer portion 13 and the second end-face side outer layer portion 15 correspond to the lead-out electrode portion of the internal electrode layer. The first end-face side outer layer portion 13 and the second end-face side outer layer portion 15 are also called the L-gap.

[0028] The division of the ceramic body 2 in the width direction W will be explained based on Figure 3. Figure 3 is a cross-sectional view taken along line II-II in Figure 1. The ceramic body 2 can be divided in the width direction W into a first side outer layer portion 16, a width-direction opposing portion 17, and a second side outer layer portion 18.

[0029] The widthwise opposing portion 17 is the portion where the internal electrode layers face each other in the height direction T. The first side outer layer portion 16 is the portion between the widthwise opposing portion 17 and the first side surface 5. The second side outer layer portion 18 is the portion between the widthwise opposing portion 17 and the second side surface 6.

[0030] The first side outer layer 16 and the second side outer layer 18 are portions in which there is no internal electrode layer in the height direction T. The first side outer layer 16 and the second side outer layer 18 are also called the W gap.

[0031] The internal electrode layer includes a plurality of first internal electrode layers 32 and a plurality of second internal electrode layers 33. The first internal electrode layers 32 are internal electrode layers exposed on the first end face 7. The second internal electrode layers 33 are internal electrode layers exposed on the second end face 8.

[0032] The first internal electrode layer 32 can be divided into a first opposing electrode portion 34 and a first drawn-out electrode portion 36. The first opposing electrode portion 34 is the portion facing the second internal electrode layer 33. The first drawn-out electrode portion 36 is the portion drawn out from the first opposing electrode portion 34 to the first end face 7 of the ceramic body 2.

[0033] The second internal electrode layer 33 can be divided into a second opposing electrode portion 35 and a second drawn-out electrode portion 37. The second opposing electrode portion 35 is the portion facing the first internal electrode layer 32. The second drawn-out electrode portion 37 is the portion drawn out from the second opposing electrode portion 35 to the second end face 8 of the ceramic body 2.

[0034] The material of the internal electrode layer can be, for example, a metal such as nickel, copper, silver, palladium, or gold. The material of the internal electrode layer can be an alloy containing at least one of the aforementioned metals, such as a silver-palladium alloy.

[0035] In the multilayer ceramic capacitor 1, capacitance is formed when the first counter electrode portion 34 and the second counter electrode portion 35 face each other via the inner dielectric layer 31. As a result, the multilayer ceramic capacitor 1 exhibits the characteristics of a capacitor.

[0036] The thickness of the internal electrode layer is preferably, for example, 0.2 μm to 2.0 μm. The total number of layers, including the first internal electrode layer 32 and the second internal electrode layer 33, is preferably 15 to 2000.

[0037] The terminal electrodes will now be described. The terminal electrodes include a first terminal electrode 20 and a second terminal electrode 21. The first terminal electrode 20 is a terminal electrode connected to the first internal electrode layer 32. The second terminal electrode 21 is a terminal electrode connected to the second internal electrode layer 33.

[0038] The first terminal electrode 20 is located on the first end face 7, a portion of the first main surface 3, a portion of the second main surface 4, a portion of the first side surface 5, and a portion of the second side surface 6. The second terminal electrode 21 is located on the second end face 8, a portion of the first main surface 3, a portion of the second main surface 4, a portion of the first side surface 5, and a portion of the second side surface 6.

[0039] The terminal electrode includes an external electrode film 22, a nickel plating film 24, and a tin plating film 25. These are arranged in the order of external electrode film 22, nickel plating film 24, and tin plating film 25 from the end face of the ceramic body 2.

[0040] The external electrode film 22 is positioned on the end face of the ceramic body 2 and covers the end face. The external electrode film 22 extends from the end face to a portion of the main surface and a portion of the side surface.

[0041] The external electrode film 22 contains glass and metal. The glass may contain boron, silicon, barium, or strontium. It may also contain at least one selected from calcium, magnesium, aluminum, lithium, etc. Glass will be described in detail later. The metal may contain at least one selected from, for example, copper, nickel, silver, palladium, silver-palladium alloy, gold, etc. The external electrode film 22 is obtained by applying a conductive paste containing glass and metal to the ceramic body 2 and firing it. The thickness of the external electrode film 22 is preferably, for example, 3 μm to 100 μm.

[0042] The nickel plating film 24 is positioned to cover the external electrode film 22. The tin plating film 25 is positioned to cover the nickel plating film 24.

[0043] The nickel plating film 24 prevents the external electrode film 22 from being corroded by the solder used when mounting the multilayer ceramic capacitor 1. The tin plating film 25 improves the wettability of the solder used when mounting the multilayer ceramic capacitor 1, making mounting easier.

[0044] The size of the multilayer ceramic capacitor 1 is not particularly limited. The preferred length of the multilayer ceramic capacitor 1, including the ceramic element 2 and terminal electrodes, is 0.2 mm to 10 mm. The preferred height of the multilayer ceramic capacitor 1, including the ceramic element 2 and terminal electrodes, is 0.1 mm to 5 mm. The preferred width of the multilayer ceramic capacitor 1, including the ceramic element 2 and terminal electrodes, is 0.1 mm to 10 mm.

[0045] The terminal electrodes will be described in more detail based on Figure 4. Figure 4 is an LT cross-sectional view showing the vicinity of the second end face 8 of the multilayer ceramic capacitor 1. Figure 4 shows the external electrode film 22 included in the second terminal electrode 21. The nickel plating film 24 and tin plating film 25 are not shown in Figure 4.

[0046] The conductive paste used to form the external electrode film 22 includes at least one of the following: barium-boron-silicon glass, strontium-boron-silicon glass, barium-strontium-boron-silicon glass, and bismuth-based glass. Here, bismuth-based glass refers to glass containing bismuth trioxide.

[0047] A cluster of glass within the external electrode film 22 is defined as a glass domain. Of the glass domains, the one exposed on the surface 42 of the external electrode film 22 but not exposed at the interface 40 between the external electrode film 22 and the ceramic body 2 is defined as the first glass domain 52.

[0048] Among the glass domains, the glass domain that is not exposed on the surface 42 of the external electrode film 22 but is exposed at the interface 8 between the external electrode film 22 and the ceramic body 2 is defined as the second glass domain 50.

[0049] The concentration ratio of bismuth to silicon is higher in the portion of the external electrode film 22 exposed on the surface 42 in the first glass domain 52 than in the portion of the external electrode film 22 exposed at the interface 8 with the ceramic body 2 in the second glass domain 50.

[0050] In the multilayer ceramic capacitor 1 of this embodiment, the bismuth concentration ratio to silicon is higher in the portion of the external electrode film 22 exposed on the surface 42 in the first glass domain 52 than in the portion of the external electrode film 22 exposed at the interface 8 with the ceramic body 2 in the second glass domain 50. This allows for good adhesion between the terminal electrode and the ceramic body 2 while providing moisture resistance to the terminal electrode. The following will explain this in order.

[0051] The glass contained in the external electrode film 22 is required to function as an adhesive between the ceramic substrate 2 and the external electrode film 22, and as a sintering aid to densify the external electrode film 22. In particular, in relation to film densification, the glass contained in the external electrode film 22 is required to have a low softening point.

[0052] Conventionally, only one type of glass has been used, such as barium-boron-silicon glass. Increasing the proportion of barium can lower the softening point. Also, it becomes less likely for a reaction layer to form at the interface with the ceramic substrate. Therefore, the bonding strength of the fixed interface does not decrease, and it becomes possible to form a good interface with the ceramic substrate.

[0053] However, barium-boron-silicon glass has poor moisture resistance. Therefore, the reliability of the multilayer ceramic capacitor 1 tends to decrease.

[0054] Therefore, another way to lower the softening point of glass is to use bismuth-based glass. Some bismuth-based glass compositions also have excellent moisture resistance.

[0055] However, when bismuth-based glass is used, the sintering of the external electrode film 22 may proceed too quickly at low temperatures. As a result, the degreasing properties of the external electrode film 22 may deteriorate, and blistering may occur on the external electrode film 22. In addition, when bismuth-based glass is used, the wettability to the ceramic substrate is worse than when barium-boron-silicon-based glass is used, resulting in a decrease in the adhesion strength to the ceramic substrate.

[0056] (First embodiment) In the multilayer ceramic capacitor 1 of this embodiment, the conductive paste used to form the external electrode film 22 contains barium-boron-silicon glass and bismuth glass. The distribution of these glasses differs within the external electrode film 22. Barium-boron-silicon glass is more abundant on the ceramic body 2 side. Bismuth glass is more abundant on the nickel plating film 24 side of the external electrode film 22, i.e., the surface 42 side. This is because the wettability of barium-boron-silicon glass and bismuth glass to the ceramic body 2 is different. Due to the difference in wettability, the distribution of barium-boron-silicon glass and bismuth glass within the external electrode film 22 differs during firing.

[0057] Preferably, the concentration ratio of bismuth to silicon in the portion of the first glass domain 52 exposed to the surface 42 of the external electrode film 22 is 1.8 times or more the concentration ratio of bismuth to silicon in the portion of the second glass domain 50 exposed to the interface 8 with the ceramic body 2 of the external electrode film 22.

[0058] The presence of a first glass domain 52 and a second glass domain 50 in the external electrode film 22 allows each glass domain to share the functions of an adhesion layer and a moisture-resistant layer. The first glass domain 52 functions as a moisture-resistant layer. The second glass domain 50 functions as an adhesion layer. By sharing functions between the first glass domain 52 and the second glass domain 50, moisture resistance can be imparted to the external electrode film 22 while maintaining good adhesion to the ceramic substrate 2.

[0059] Specifically, the first glass domain 52 improves the moisture resistance near the surface 42 of the external electrode film 22. Therefore, it is possible to prevent water from penetrating the external electrode film 22 when immersed in the plating solution. In addition, because the external electrode film 22 has moisture resistance, the moisture resistance reliability of the multilayer ceramic capacitor 1 can be improved.

[0060] Bismuth-based glass has a low softening point. However, when the amount of bismuth-based glass added is small, excessive sintering does not occur at low temperatures. Therefore, it does not negatively affect degreasing properties.

[0061] Figures 5 and 6 show scanning electron microscope images of the external electrode film 22 of the multilayer ceramic capacitor 1 of this embodiment. The bismuth / silicon ratios shown in Figures 5 and 6 indicate the concentration ratio of bismuth to silicon in the glass.

[0062] In Figure 5, the bismuth / silicon ratios at measurement sites 101 and 102 represent the bismuth / silicon ratio of the portion of the first glass domain 52 exposed to the surface 42 of the external electrode film 22.

[0063] The bismuth / silicon ratios at measurement sites 104 and 105 represent the bismuth / silicon ratio of the portion of the external electrode film 22 exposed at the interface 8 with the ceramic body 2 in the second glass domain 50.

[0064] As shown in Figure 5, the bismuth / silicon ratio is greater in the portion of the external electrode film 22 exposed on the surface 42 in the first glass domain 52 than in the portion of the external electrode film 22 exposed at the interface 8 with the ceramic body 2 in the second glass domain 50.

[0065] Furthermore, some glass domains extend long in the length direction L, as indicated by arrow 56 in Figure 5.

[0066] Within such a glass domain 56, the concentration ratio of bismuth to silicon is greater in the portion of the glass domain 56 closer to the surface 42 of the external electrode film 22 than in the portion of the glass domain 56 closer to the interface 40 between the external electrode film 22 and the ceramic body 2. In the example shown in Figure 5, the bismuth / silicon ratio in the glass domain 56 is greater at measurement site 102 than at measurement site 103.

[0067] The example shown in Figure 6 differs from the example shown in Figure 5 in the composition of the barium-boron-silicon glass. Figure 6 mainly shows the first glass domain 52.

[0068] In Figure 6, the bismuth / silicon ratios at measurement sites 111 and 112 represent the bismuth / silicon ratio of the portion of the first glass domain 52 exposed to the surface 42 of the external electrode film 22. The bismuth / silicon ratios at measurement sites 114 to 116 represent the bismuth / silicon ratio at a position closer to the interface 40 between the external electrode film 22 and the ceramic body 2, away from the surface 42 of the external electrode film 22.

[0069] As shown in Figure 6, the bismuth / silicon ratio decreases as you move from the surface 42 of the external electrode film 22 towards the interface 40 between the external electrode film 22 and the ceramic body 2.

[0070] [Table 1]

[0071] Based on Table 1, the characteristics of samples with different amounts of bismuth-based glass added are shown. In the samples shown in Table 1, the material of the metal powder is copper. The shape of the metal powder is spherical. The particle size of the metal powder is 1.6 μm.

[0072] The length L of the sample multilayer ceramic capacitor 1 is 1.0 mm. The length L of the width W and height T of the sample multilayer ceramic capacitor 1 is 0.5 mm in both directions.

[0073] The preparation of the sample will be explained. A paste for the external electrode film is created by mixing and dispersing metal powder, barium-boron-silicon glass, bismuth glass, binder resin, and solvent.

[0074] A paste for the external electrode film is applied to the ceramic body 2. The paste for the external electrode film is applied by a dipping method. The applied paste for the external electrode film is fired in a temperature range of 700°C to 900°C.

[0075] The evaluation of the film structure using scanning electron microscopy images, as shown above, was performed by embedding the sample in resin, polishing it, and creating a cross-section, followed by observation using energy-dispersive X-ray spectroscopy.

[0076] The adhesion performance evaluation assesses the adhesion performance of the terminal electrodes to the ceramic body 2. The adhesion performance evaluation will be explained with reference to Figure 7. Figure 7 is a diagram showing the method for evaluating adhesion performance. The sample for evaluation is a multilayer ceramic capacitor 1 with tin plating applied to the external electrode film 22. As shown in Figure 7, the multilayer ceramic capacitor 1 is placed on the substrate 92 with the ceramic body 2 in an upright position. Solder 90 is applied to the second terminal electrode 21, which is the terminal electrode located closer to the substrate 92. This fixes the multilayer ceramic capacitor 1 to the substrate 92. With the multilayer ceramic capacitor 1 fixed to the substrate 92, the first terminal electrode 20, which is the terminal electrode located further away from the substrate 92, was pressed in the direction indicated by arrow 94, that is, in a direction parallel to the surface of the substrate 92.

[0077] This mode of destruction caused by lateral pressure is (1) Delamination at the interface between the substrate 92 and the solder 90, (2) Delamination at the interface between the solder 90 and the tin plating film on the second terminal electrode 21, (3) Delamination at the interface between the second terminal electrode 21 and the ceramic body 2, (4) Cracks in ceramic body 2, They were classified into four categories.

[0078] The sample size was set at 10. If even one of the 10 samples exhibited the failure mode described in (3), it was judged as defective. This was indicated as "×" in Table 1.

[0079] The end faces of the capacitors after external electrode formation were visually inspected using an optical microscope to evaluate for blistering. The thickness of the external electrode film 22 after firing was set to 30 μm. 100 samples were observed. If even one blister occurred among the 100 samples, it was judged as defective ("×"), and if no blisters occurred at all, it was judged as good ("○").

[0080] The humidity resistance test was evaluated using a sample in which a nickel plating film was formed between the external electrode film and the tin plating film, as described above. The humidity resistance test was conducted under the conditions of a temperature of 125°C, a humidity of 95%RH, and an applied voltage of 3.2V. In the humidity resistance test, the logarithmic value logIR of the insulation resistance of multilayer ceramic capacitor 1 was measured. If one or more out of 20 samples showed a decrease of two orders of magnitude or more in the measured logIR compared to the initial value before 24 hours had elapsed, it was judged as defective ("×"), and if there were no such decreases, it was judged as good ("○").

[0081] As shown in Table 1 above, in samples with a volume percentage of bismuth-based glass / (barium-boron-silicon-based glass + bismuth-based glass) ranging from 5% to 35%, the adhesion performance, blistering, and humidity load tests all yielded a "○" result, and the overall evaluation was "○". On the other hand, in Comparative Examples 1 to 3, at least one item was "×", and the overall evaluation was not "○".

[0082] The method for measuring the length and thickness of each part is explained. The multilayer ceramic capacitor 1 is polished to the center position in the width direction W. Then, the LT cross-section exposed by polishing is observed using an optical microscope or similar device. From the observed LT cross-section, the length or thickness can be measured.

[0083] A method for manufacturing a multilayer ceramic capacitor 1 is described below. First, a conductive paste for the dielectric sheet and the internal electrode layer is prepared. The conductive paste for the dielectric sheet and the internal electrode layer contains a binder and a solvent. The binder and solvent may be known organic binders and organic solvents, etc.

[0084] A conductive paste for the internal electrode layer is printed onto a dielectric sheet in a predetermined pattern. The internal electrode layer pattern is formed by printing the conductive paste. Printing can be done, for example, by screen printing or gravure printing.

[0085] A predetermined number of dielectric sheets for the outer layer are stacked. The dielectric sheets for the outer layer do not have the internal electrode layer pattern printed on them. Dielectric sheets with the internal electrode layer pattern printed on them are then sequentially stacked on top of the stacked dielectric sheets. Furthermore, a predetermined number of dielectric sheets for the outer layer are stacked on top of that. A laminated sheet is manufactured by these stacking processes.

[0086] Laminated blocks are manufactured by pressing laminated sheets in the height direction. The pressing method can be hydrostatic pressing.

[0087] The laminated block is cut to a predetermined size. This cut produces the laminated chips. During the cutting process, the corners and edges of the laminated chips may be rounded. Barrel polishing can be used to round the edges.

[0088] The laminated chips are fired. This firing process produces a ceramic body. The preferred firing temperature is between 900°C and 1110°C. The firing temperature can be changed depending on the materials of the dielectric and internal electrode layers.

[0089] Terminal electrodes are formed. First, a conductive paste, which will become the external electrode film 22, is applied to the two end faces of the ceramic body 2. The conductive paste contains glass and metal, etc. The conductive paste can be applied by methods such as dipping. After application, firing is performed to form the external electrode film 22. The firing temperature is preferably between 500°C and 900°C. The firing time is preferably between 30 minutes and 2 hours.

[0090] A nickel plating film 24 is formed on the surface of the external electrode film 22. Furthermore, a tin plating film 25 is formed on the surface of the nickel plating film 24. The nickel plating film 24 and the tin plating film 25 can be formed by methods such as barrel plating. In this way, a multilayer ceramic capacitor 1 is obtained.

[0091] (Other embodiments) In the first embodiment, the conductive paste used to form the external electrode film was described as containing barium-boron-silicon glass and bismuth glass, but is not limited thereto. The conductive paste may also contain strontium-boron-silicon glass or barium-strontium-boron-silicon glass instead of barium-boron-silicon glass.

[0092] Even when using glass in other embodiments, the same effects as in the first embodiment are achieved. Specifically, when a glass domain exposed on the surface of the external electrode film but not exposed at the interface with the ceramic element of the external electrode film is designated as the first glass domain, and a glass domain not exposed on the surface of the external electrode film but exposed at the interface with the ceramic element of the external electrode film is designated as the second glass domain, the bismuth / silicon ratio was greater in the portion of the first glass domain exposed on the surface of the external electrode film than in the portion of the second glass domain 50 exposed at the interface with the ceramic element of the external electrode film. Furthermore, in a humidity load test conducted under the same conditions as in the first embodiment, it was confirmed that good humidity resistance was obtained in samples that satisfied the above-described bismuth / silicon ratio relationship.

[0093] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and various modifications and variations are possible. [Explanation of Symbols]

[0094] 1. Multilayer ceramic capacitor 2. Ceramic body 3. First main surface 4. Second main surface 5. First Aspect 6. Second Aspect 7. First end face 8. Second end face 20 First terminal electrode 21 Second terminal electrode 22 External electrode membrane 24 Nickel plating film 25 Tin plating film 30 Outer dielectric layer 31 Inner Dielectric Layer 40 Interface of the external electrode film with the ceramic substrate 42 Surface of the external electrode film 50 The second glass domain 52. First glass domain 54 Copper 56 Glass Domain 90 solder 92 circuit boards 94 Arrow L (Length direction) T (height direction) W (width direction)

Claims

1. A ceramic body comprising a plurality of stacked dielectric layers and a plurality of stacked internal electrode layers, having a first main surface and a second main surface facing each other in the height direction, a first side surface and a second side surface facing each other in the width direction perpendicular to the height direction, and a first end surface and a second end surface facing each other in the length direction perpendicular to the height direction and width direction, A multilayer ceramic capacitor comprising a terminal electrode provided on the ceramic body and connected to a part of the internal electrode layer, The terminal electrode includes an external electrode film that is in contact with the ceramic body. The external electrode film comprises at least one of the following: a first glass made from barium-boron-silicon glass, strontium-boron-silicon glass, or barium-strontium-boron-silicon glass, and a second glass made from bismuth glass. The first glass and the second glass form glass domains within the external electrode film. Of the aforementioned glass domains, A glass domain that is exposed on the surface of the external electrode film but not exposed at the interface of the external electrode film with the ceramic substrate is defined as the first glass domain. When a glass domain that is not exposed on the surface of the external electrode film but is exposed at the interface between the external electrode film and the ceramic substrate is defined as a second glass domain, The concentration ratio of bismuth to silicon is higher in the portion of the external electrode film exposed on the surface in the first glass domain than in the portion of the external electrode film exposed at the interface with the ceramic substrate in the second glass domain. Multilayer ceramic capacitor.

2. The concentration ratio of bismuth to silicon in the glass domain is higher in the portion of the external electrode film closer to the surface than in the portion of the external electrode film closer to the interface with the ceramic body. The multilayer ceramic capacitor according to claim 1.

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