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

Multilayer ceramic capacitors

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

[0002] One method for manufacturing terminal electrodes of a multilayer ceramic capacitor involves applying a conductive paste, in which conductive powder such as copper and glass frit powder are dispersed in a vehicle, to a ceramic body, drying the paste, and firing it at a high temperature to form terminal electrodes electrically connected to the internal electrode layers. Patent Document 1 describes a method using glass frit powder containing barium.

[0003] Patent No. 6354970

[0004] The barium-boron-silicon glass contains barium, which makes it possible to lower the softening point compared to boron-silicon glasses. The lower softening point allows for the formation of dense films.

[0005] Furthermore, barium-boron-silicon-based glass is less likely to form a reaction layer at the interface with the ceramic element. Specifically, when the ceramic element contains barium, the barium-containing barium-boron-silicon-based glass inhibits the barium from migrating from the ceramic element, making it less likely to form a reaction layer. Therefore, the barium-boron-silicon-based glass can achieve good adhesion to the ceramic element.

[0006] However, barium-boron-silicon glass has low moisture resistance and can be altered or dissolved when it comes into contact with acidic plating solution. When the glass is altered, the plating solution can seep into the terminal electrodes, causing poor reflow. Furthermore, the moisture resistance of the terminal electrodes can be reduced, reducing the reliability of the multilayer ceramic capacitor.

[0007] The problems encountered when using barium-boron-silicon glass have been described above, but similar problems were also encountered with strontium-boron-silicon glass and barium-strontium-boron-silicon glasses.

[0008] SUMMARY OF THE INVENTION It is therefore an object of the present invention 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 is a multilayer ceramic capacitor comprising: a ceramic body including a plurality of laminated dielectric layers and a plurality of laminated internal electrode layers, the ceramic body having first and second main surfaces opposing each other in a height direction, a first side surface and a second side surface opposing each other in a width direction perpendicular to the height direction, and a first end surface and a second end surface opposing each other in a length direction perpendicular to the height direction and the width direction; and terminal electrodes provided on the ceramic body and connected to some of the internal electrode layers, the terminal electrodes including external electrode films in contact with the ceramic body, and the external electrode films being made of at least a barium-boron-silicon glass, a strontium-boron-silicon glass, or a barium-strontium-boron-silicon glass capsule. and a second glass made of a bismuth-based glass, wherein the first glass and the second glass form glass domains within the external electrode film, and a glass domain of the glass domain that is exposed on the surface of the external electrode film but not at the interface of the external electrode film with the ceramic body is defined as a first glass domain, and a glass domain that is not exposed on the surface of the external electrode film but at the interface of the external electrode film with the ceramic body is defined as a second glass domain. In this case, the concentration ratio of bismuth to silicon is higher in the portion of the first glass domain that is exposed on the surface of the external electrode film than in the portion of the second glass domain that is exposed at the interface of the external electrode film with the ceramic body.

[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.

[0011] Fig. 2 is a perspective view of a multilayer ceramic capacitor according to an embodiment of the present invention; Fig. 3 is a cross-sectional view taken along line II in Fig. 1; Fig. 4 is a cross-sectional view taken along line II-II in Fig. 1; Fig. 5 is an LT cross-sectional view of the vicinity of a second end face of a multilayer ceramic capacitor; Fig. 6 is a diagram showing a scanning electron microscope image of an external electrode film; Fig. 7 is a diagram showing a scanning electron microscope image of another external electrode film; Fig. 8 is a diagram showing a method for evaluating adhesion performance;

[0012] An embodiment of the present invention will be described with reference to FIG. 1. FIG. 1 is a perspective view of a multilayer ceramic capacitor 1 according to an embodiment of the present invention. FIG. 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 also be a multi-terminal multilayer ceramic capacitor, such as a three-terminal multilayer ceramic capacitor.

[0013] The multilayer ceramic capacitor 1 includes a ceramic body 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 a plurality of laminated dielectric layers and a plurality of internal electrode layers, and is shaped like a rectangular parallelepiped.

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

[0016] Of the two surfaces of the ceramic body 2 that face each other in the height direction T, one surface is designated as a first main surface 3. The remaining surface is designated as a second main surface 4. Of the two surfaces of the ceramic body 2 that face each other in the width direction W, one surface is designated as a first side surface 5. The remaining surface is designated as a second side surface 6. Of the two surfaces of the ceramic body 2 that face each other in the length direction L, one surface is designated as a first end surface 7. The remaining surface is designated as a second end surface 8.

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

[0018] The intersection of three faces of the ceramic body 2 is called a corner of the ceramic body 2. The intersection of two faces of the ceramic body 2 is called a ridge of the ceramic body 2. The corners and ridges are preferably rounded.

[0019] The total number of dielectric layers stacked on the ceramic body 2 is preferably 15 or more and 2000 or less. The main material of the dielectric layers is a ceramic material. Examples of ceramic materials include dielectric ceramics containing barium titanate, calcium titanate, strontium titanate, calcium zirconate, or the like as main components. The ceramic material may also be a dielectric ceramic containing these main components plus a secondary component such as a manganese compound, an iron compound, a chromium compound, a cobalt compound, or a nickel compound.

[0020] The thickness of each dielectric layer is preferably 0.3 μm or more and 10 μm or less.

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

[0022] The first main surface side outer layer portion 10 is the portion between the first main surface 3 and the internal electrode layer closest to 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 second main surface 4 and the internal electrode layer closest to the second main surface 4.

[0023] Of the dielectric layers, the dielectric layers arranged in the first main surface side outer layer portion 10 and the second main surface side outer layer portion 12 are referred to as outer dielectric layers 30. Of the dielectric layers, the dielectric layer arranged in the effective portion 11 is referred to as inner dielectric layers 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 in the width direction is preferably 0.1 mm or more and 5 mm or less. The length T of the ceramic body 2 in the height direction 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 described. The ceramic body 2 can be divided into a first end face side outer layer portion 13, a longitudinally facing portion 14, and a second end face side outer layer portion 15 in the longitudinal direction L.

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

[0027] The longitudinally opposing portions 14 correspond to opposing electrode portions of the internal electrode layers. The first end surface side outer layer portion 13 and the second end surface side outer layer portion 15 correspond to lead electrode portions of the internal electrode layers. The first end surface side outer layer portion 13 and the second end surface side outer layer portion 15 are also called L gaps.

[0028] The division of the ceramic body 2 in the width direction W will be described with reference to 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 surface outer layer portion 16, a widthwise opposing portion 17, and a second side surface outer layer portion 18.

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

[0030] The first side surface side outer layer portion 16 and the second side surface side outer layer portion 18 are portions where no internal electrode layers exist in the height direction T. The first side surface side outer layer portion 16 and the second side surface side outer layer portion 18 are also called W gaps.

[0031] The internal electrode layers include 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 at the first end face 7. The second internal electrode layers 33 are internal electrode layers exposed at 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 lead electrode portion 36. The first opposing electrode portion 34 is a portion that faces the second internal electrode layer 33. The first lead electrode portion 36 is a portion that is led 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 lead electrode portion 37. The second opposing electrode portion 35 is a portion that faces the first internal electrode layer 32. The second lead electrode portion 37 is a portion that is led 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 layers can be, for example, a metal such as nickel, copper, silver, palladium, gold, etc. The material of the internal electrode layers 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 by the first opposing electrode portion 34 and the second opposing electrode portion 35 facing each other via the inner dielectric layer 31. This allows the multilayer ceramic capacitor 1 to exhibit capacitor characteristics.

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

[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 a first internal electrode layer 32. The second terminal electrode 21 is a terminal electrode connected to a second internal electrode layer 33.

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

[0039] The terminal electrodes include an external electrode film 22, a nickel-plated film 24, and a tin-plated film 25. These are arranged in this order from the end face of the ceramic body 2: the external electrode film 22, the nickel-plated film 24, and the tin-plated film 25.

[0040] The external electrode films 22 are disposed on and cover the end faces of the ceramic body 2. The external electrode films 22 extend from the end faces to parts of the main surfaces and parts of the side surfaces.

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

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

[0043] The nickel plating film 24 can prevent the external electrode film 22 from being eroded by solder when mounting the multilayer ceramic capacitor 1. The tin plating film 25 can improve the wettability of the solder when mounting the multilayer ceramic capacitor 1, making mounting easier.

[0044] The size of the multilayer ceramic capacitor 1 is not particularly limited. The length in the longitudinal direction of the multilayer ceramic capacitor 1 including the ceramic body 2 and the terminal electrodes is preferably 0.2 mm or more and 10 mm or less. The length in the height direction of the multilayer ceramic capacitor 1 including the ceramic body 2 and the terminal electrodes is preferably 0.1 mm or more and 5 mm or less. The length in the width direction of the multilayer ceramic capacitor 1 including the ceramic body 2 and the terminal electrodes is preferably 0.1 mm or more and 10 mm or less.

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

[0046] The conductive paste used to form the external electrode films 22 contains at least one of barium-boron-silicon glass, strontium-boron-silicon glass, and barium-strontium-boron-silicon glass, and bismuth-based glass, where bismuth-based glass refers to glass containing bismuth trioxide.

[0047] A mass of glass in the external electrode film 22 is referred to as a glass domain. Of the glass domains, a glass domain that is exposed on the surface 42 of the external electrode film 22 but not on the interface 40 between the external electrode film 22 and the ceramic body 2 is referred to as a first glass domain 52.

[0048] Of 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 referred to as a second glass domain 50 .

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

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

[0051] The glass contained in the external electrode film 22 is required to have the following functions: to act as an adhesive between the ceramic body 2 and the external electrode film 22, and to act as a sintering aid for densifying the external electrode film 22. In particular, in relation to densifying the film, the glass contained in the external electrode film 22 is required to have a low softening point.

[0052] Conventionally, only one type of glass, such as a barium-boron-silicon glass, has been used. Increasing the barium content can lower the softening point. It also makes it difficult for a reaction layer to form at the interface with the ceramic body. This prevents a decrease in the bonding strength of the bonding interface, making it possible to form a good interface with the ceramic body.

[0053] However, barium-boron-silicon glass has low moisture resistance, which makes the reliability of the multilayer ceramic capacitor 1 prone to decrease.

[0054] Therefore, as another means for lowering the softening point of glass, it is possible to use bismuth-based glass, some of which have compositions with excellent moisture resistance.

[0055] However, when bismuth-based glass is used, the sintering of the external electrode film 22 may proceed too quickly at a low temperature, which may result in poor degreasing of the external electrode film 22 and the formation of blisters in the external electrode film 22. Furthermore, when bismuth-based glass is used, the wettability to the ceramic body is poorer than when barium-boron-silicon-based glass is used, and the bonding strength to the ceramic body is reduced.

[0056] First Embodiment In the multilayer ceramic capacitor 1 of this embodiment, the conductive paste used to form the external electrode films 22 contains barium-boron-silicon-based glass and bismuth-based glass. The distribution of these glasses differs within the external electrode films 22. The barium-boron-silicon-based glass is more abundant on the ceramic body 2 side. The bismuth-based glass is more abundant on the nickel plating film 24 side of the external electrode films 22, i.e., on the surface 42 side. This is because the barium-boron-silicon-based glass and the bismuth-based glass have different wettability with respect to the ceramic body 2. Due to the different wettability, the barium-boron-silicon-based glass and the bismuth-based glass are distributed differently within the external electrode films 22 during firing.

[0057] It is preferable that the concentration ratio of bismuth to silicon in the portion of the first glass domain 52 exposed on 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 at the interface 8 with the ceramic body 2 of the external electrode film 22.

[0058] The presence of the first glass domain 52 and the second glass domain 50 in the external electrode film 22 allows each glass domain to share the functions of an adhesive 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 adhesive layer. By sharing the functions between the first glass domain 52 and the second glass domain 50, it is possible to impart moisture resistance to the external electrode film 22 while maintaining good adhesiveness between the external electrode film 22 and the ceramic body 2.

[0059] Specifically, the first glass domain 52 improves the moisture resistance near the surface 42 of the external electrode film 22. This makes it possible to prevent water from penetrating into the external electrode film 22 when immersed in a plating solution. Furthermore, 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, and therefore degreasing properties are not adversely affected.

[0061] 5 and 6 are views showing scanning electron microscope images of the external electrode films 22 of the multilayer ceramic capacitor 1 of this embodiment. The bismuth / silicon ratio shown in Fig. 5 and Fig. 6 indicates the concentration ratio of bismuth to silicon in the glass.

[0062] In FIG. 5, the bismuth / silicon ratios at measurement points 101 and 102 indicate the bismuth / silicon ratios of the portions of the first glass domain 52 exposed to the surface 42 of the external electrode film 22 .

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

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

[0065] Among the glass domains, there are glass domains that extend long in the length direction L, as indicated by arrows 56 in FIG.

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

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

[0068] 6 , the bismuth / silicon ratios at measurement positions 111 and 112 indicate the bismuth / silicon ratios at portions of the first glass domain 52 that are exposed on the surface 42 of the external electrode film 22. The bismuth / silicon ratios at measurement positions 114 to 116 indicate the bismuth / silicon ratios at positions from the surface 42 of the external electrode film 22 toward the interface 40 of the external electrode film 22 with the ceramic body 2.

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

[0070]

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

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

[0073] The preparation of the sample will be explained below: Metal powder, barium-boron-silicon glass, bismuth glass, binder resin, and solvent are kneaded and dispersed to prepare a paste for the external electrode film.

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

[0075] The evaluation of the film structure using the scanning electron microscope images and the like shown above was carried out by embedding the sample in resin, polishing it, exposing a cross section, and then observing it using energy dispersive X-ray spectroscopy.

[0076] The evaluation of adhesion performance was performed by evaluating the adhesion of the terminal electrodes to the ceramic body 2. The evaluation of adhesion performance will be described with reference to FIG. 7 . FIG. 7 is a diagram illustrating a method for evaluating adhesion performance. The evaluation sample was a multilayer ceramic capacitor 1 having tin-plated external electrode films 22. As shown in FIG. 7 , the multilayer ceramic capacitor 1 was placed on a substrate 92 with the ceramic body 2 standing upright. Solder 90 was applied to the second terminal electrode 21, which is the terminal electrode located closer to the substrate 92. This fixed 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 farther from the substrate 92, was pressed in the direction indicated by arrow 94, i.e., in a direction parallel to the surface of the substrate 92.

[0077] The destruction modes caused by this lateral pushing were classified into four types: (1) peeling at the interface between the substrate 92 and the solder 90, (2) peeling at the interface between the solder 90 and the tin-plated film on the second terminal electrode 21, (3) peeling at the interface between the second terminal electrode 21 and the ceramic body 2, and (4) cracking of the ceramic body 2.

[0078] The number of samples was 10. If even one of the 10 samples showed the failure mode (3), it was judged to be defective. This is indicated by "X" in Table 1.

[0079] After the external electrodes were formed, the end faces of the capacitor were visually inspected using an optical microscope to evaluate the presence of blisters. The thickness of the external electrode film 22 after firing was set to 30 μm. 100 samples were inspected. If even one blister was found among the 100 samples, the sample was judged as defective (×), and if no blister was found at all, the sample was judged as good (◯).

[0080] The humidity load test was performed using the above-mentioned sample in which a nickel plating film was formed between the external electrode film and the tin plating film. The humidity load test was performed under conditions of a temperature of 125°C, a humidity of 95% RH, and an applied voltage of 3.2 V. In the humidity load test, the logarithmic value logIR of the insulation resistance of the multilayer ceramic capacitor 1 was measured. If the measured logIR of one or more of the 20 samples decreased by two or more digits from the initial value before 24 hours had elapsed, the sample was judged as defective (×), and if no such decrease occurred, the sample was judged as good (◯).

[0081] As shown in Table 1 above, the samples with a volume percentage of bismuth-based glass / (barium-boron-silicon-based glass+bismuth-based glass) of 5% to 35% were all rated "good" in the adhesion performance, blister resistance, and humidity load resistance tests, and the overall rating was "good." On the other hand, in Comparative Examples 1 to 3, one of the items was rated "poor," and the overall rating was not "good."

[0082] The method for measuring the length and thickness of each part will be described below. The multilayer ceramic capacitor 1 is polished to the center position in the width direction W. The LT cross section exposed by polishing is then observed using an optical microscope or the like. The length, thickness, etc. can be measured from the observed LT cross section.

[0083] A method for manufacturing the multilayer ceramic capacitor 1 will now be described. First, a conductive paste for the dielectric sheets and the internal electrode layers is prepared. The conductive paste for the dielectric sheets and the internal electrode layers contains a binder and a solvent. The binder and the solvent may be a known organic binder and organic solvent, for example.

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

[0085] A predetermined number of dielectric sheets for the outer layer portions are stacked. No internal electrode layer patterns are printed on the dielectric sheets for the outer layer portions. Dielectric sheets with internal electrode layer patterns printed on them are stacked in order on top of the stacked dielectric sheets. Furthermore, a predetermined number of dielectric sheets for the outer layer portions are stacked on top of those. A laminated sheet is produced by stacking these layers.

[0086] The laminated sheet is pressed in the height direction to produce a laminated block, which can be pressurized by isostatic pressing.

[0087] The laminated block is cut to a predetermined size. This cutting process cuts out laminated chips. When cutting, the corners and ridges of the laminated chips may be rounded. The rounding method can be barrel polishing.

[0088] The laminated chip is fired to produce a ceramic body. The firing temperature is preferably 900° C. or higher and 1110° C. or lower. The firing temperature can be changed depending on the materials of the dielectric and internal electrode layers.

[0089] Forming the terminal electrodes. First, a conductive paste that will become the external electrode film 22 is applied to the two end surfaces of the ceramic body 2. The conductive paste contains glass, metal, etc. The conductive paste can be applied by a method such as dipping. After application, firing is performed to form the external electrode film 22. The firing temperature is preferably 500°C or higher and 900°C or lower. The firing time is preferably 30 minutes or higher and 2 hours or lower.

[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 a barrel plating method or the like. In this manner, the multilayer ceramic capacitor 1 is obtained.

[0091] Other Embodiments In the first embodiment, the conductive paste used to form the external electrode films is described as including barium-boron-silicon glass and bismuth-based glass, but is not limited to this. The conductive paste may be strontium-boron-silicon glass or barium-strontium-boron-silicon glass instead of barium-boron-silicon glass.

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

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

[0094] REFERENCE SIGNS LIST 1 Multilayer ceramic capacitor 2 Ceramic body 3 First main surface 4 Second main surface 5 First side surface 6 Second side surface 7 First end surface 8 Second end surface 20 First terminal electrode 21 Second terminal electrode 22 External electrode film 24 Nickel plating film 25 Tin plating film 30 Outer dielectric layer 31 Inner dielectric layer 40 Interface between external electrode film and ceramic body 42 Surface of external electrode film 50 Second glass domain 52 First glass domain 54 Copper 56 Glass domain 90 Solder 92 Substrate 94 Arrows L Length direction T Height direction W Width direction

Claims

1. a ceramic body including a plurality of laminated dielectric layers and a plurality of laminated internal electrode layers, the ceramic body having a first main surface and a second main surface opposing each other in a height direction, a first side surface and a second side surface opposing each other in a width direction perpendicular to the height direction, and a first end surface and a second end surface opposing each other in a length direction perpendicular to the height direction and the width direction; a terminal electrode provided on the ceramic body and connected to a part of the internal electrode layers, the terminal electrodes include external electrode films in contact with the ceramic body, the external electrode film includes at least a first glass made of at least one of barium-boron-silicon-based glass, strontium-boron-silicon-based glass, and barium-strontium-boron-silicon-based glass, and a second glass made of bismuth-based glass; the first glass and the second glass form a glass domain within the external electrode film; Among the glass domains, a glass domain exposed on a surface of the external electrode film but not exposed at an interface between the external electrode film and the ceramic body is defined as a 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 body is defined as a second glass domain, a concentration ratio of bismuth to silicon is higher in a portion of the external electrode film exposed to the surface in the first glass domain than in a portion of the external electrode film exposed at the interface with the ceramic body in the second glass domain; Multilayer ceramic capacitor.

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