Multilayer ceramic electronic component, circuit board, and manufacturing method for multilayer ceramic electronic component

Abstract

To provide a multilayer ceramic electronic component, a circuit board, and a manufacturing method for the multilayer ceramic electronic component that can achieve high reliability.SOLUTION: A multilayer ceramic electronic component 100 includes an element body 10 including a plurality of dielectric layers 11, and a plurality of internal electrode layers 12 that are laminated with the plurality of dielectric layers 11 interposed therebetween, and are provided so as to face each other and have one ends exposed, and an external electrode 20a and an external electrode 20b that are provided on respective end faces of the element body 10 being the ends in the direction in which the plurality of internal electrode layers 12 extend, are in contact with respective one ends of the plurality of internal electrode layers 12, and include glass 30. The external electrodes 20a and 20b include crystals 40 that contain at least one of the same elements as those contained in the plurality of dielectric layers 11 and are in contact with the element body 10 and the glass 30.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] This invention relates to multilayer ceramic electronic components, circuit boards, and methods for manufacturing multilayer ceramic electronic components. [Background technology]

[0002] Multilayer ceramic electronic components, such as multilayer ceramic capacitors, have been developed (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2003-063867 [Patent Document 2] Japanese Patent Publication No. 2005-228904 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] Multilayer ceramic electronic components are used in all kinds of electrical equipment, but their use in automotive applications has increased dramatically with the recent advancements in electronic control and electric vehicles. Consequently, the reliability requirements for their implementation have also increased.

[0005] First, sufficient adhesion strength must be achieved to the external electrodes. However, if the temperature at which the external electrodes are fired (firing temperature) is too low, sufficient adhesion strength may not be achieved. Therefore, raising the firing temperature of the external electrodes can be considered. However, raising the firing temperature of the external electrodes may cause cracks to form, reducing moisture resistance. Thus, achieving high reliability is difficult.

[0006] This invention has been made in view of the above problems, and aims to provide a multilayer ceramic electronic component, a circuit board, and a method for manufacturing a multilayer ceramic electronic component that can achieve high reliability. [Means for solving the problem]

[0007] The multilayer ceramic electronic component according to the present invention comprises a base body having a plurality of dielectric layers, a plurality of internal electrode layers stacked via the plurality of dielectric layers, facing each other and with one end exposed, and an external electrode provided on the end face of the base body which is the end in the direction in which the plurality of internal electrode layers are stretched, in contact with each of the one ends of the plurality of internal electrode layers, and containing glass, wherein the external electrode contains a crystal in contact with the base body and the glass, and the crystal contains the same element as at least one of the elements contained in the plurality of dielectric layers.

[0008] In the above-described multilayer ceramic electronic component, the same element as at least one of the elements contained in the plurality of dielectric layers may be barium.

[0009] In the multilayer ceramic electronic component described above, the crystals may be needle-shaped or rod-shaped.

[0010] In the above-described multilayer ceramic electronic component, the major axis of the crystal may be 100 nm or more.

[0011] In the above-described multilayer ceramic electronic component, the plurality of dielectric layers may contain zirconate.

[0012] In the above-described multilayer ceramic electronic component, the external electrode may have copper as its main component.

[0013] The above multilayer ceramic electronic component may also be a Class 1 capacitor.

[0014] The circuit board according to the present invention is a circuit board equipped with any of the above-mentioned multilayer ceramic electronic components.

[0015] The manufacturing method of a multilayer ceramic electronic component according to the present invention is a method for manufacturing a multilayer ceramic electronic component having a plurality of dielectric layers and a plurality of internal electrode layers laminated through the plurality of dielectric layers, facing each other, and provided so that one end is exposed. The method includes an activation treatment step of activating the surface of an end face of the element body, which is an end in the direction in which the plurality of internal electrode layers extend; an external electrode forming step of applying an external electrode paste containing glass to the activated surface by the activation treatment step, baking the paste to form an external electrode, and forming a crystal in the external electrode that contains the same element as at least one of the elements contained in the plurality of dielectric layers and contacts the element body and the glass.

[0016] In the above manufacturing method, the same element as at least one of the elements contained in the plurality of dielectric layers may be barium.

[0017] In the above manufacturing method, the activation treatment step may be an acid immersion or a sandblast treatment.

[0018] In the activation treatment step of the above manufacturing method, hydrochloric acid may be used.

[0019] In the external electrode forming step of the above manufacturing method, the crystal may be formed by melting the same element as at least one of the elements contained in the plurality of dielectric layers in the glass and then re-precipitating the element.

[0020] In the above manufacturing method, the crystal may be a rod-shaped or needle-shaped crystal.

Advantages of the Invention

[0021] According to the present invention, it is possible to provide a multilayer ceramic electronic component, a circuit board, and a manufacturing method thereof that can achieve high reliability.

Brief Description of the Drawings

[0022] [Figure 1] It is a partial cross-sectional perspective view of a multilayer ceramic capacitor. [Figure 2] This is a cross-sectional view along line AA in Figure 1. [Figure 3] This is a cross-sectional view along line BB in Figure 1. [Figure 4] This diagram illustrates how multilayer ceramic capacitors are mounted on a circuit board. [Figure 5] (a) and (b) are enlarged cross-sectional views of the external electrode. [Figure 6] (a) is a magnified view of the area near the interface between the external electrode and the substrate, and (b) is a diagram illustrating the aspect ratio. [Figure 7] This diagram illustrates a flow chart of the manufacturing process for multilayer ceramic capacitors. [Figure 8] (a) and (b) are diagrams illustrating the lamination process. [Modes for carrying out the invention]

[0023] The embodiments will be described below with reference to the drawings.

[0024] Figure 1 is a partial cross-sectional perspective view of a multilayer ceramic capacitor 100 according to an embodiment. Figure 2 is a cross-sectional view taken along line AA in Figure 1. Figure 3 is a cross-sectional view taken along line BB in Figure 1. As illustrated in Figures 1 to 3, the multilayer ceramic capacitor 100 comprises a base body 10 having a substantially rectangular parallelepiped shape and external electrodes 20a and 20b provided on two opposing end faces of either the base body 10. Of the four faces of the base body 10 other than the two end faces, the two faces other than the top and bottom faces in the stacking direction are referred to as side faces. The external electrodes 20a and 20b extend to the top, bottom, and two side faces of the base body 10 in the stacking direction. However, the external electrodes 20a and 20b are spaced apart from each other.

[0025] The base body 10 has a structure in which dielectric layers 11 containing a ceramic material that functions as a dielectric and internal electrode layers 12 mainly composed of metal are alternately stacked. In other words, the base body 10 comprises a plurality of internal electrode layers 12 facing each other and dielectric layers 11 sandwiched between each of the plurality of internal electrode layers 12. The edges of each internal electrode layer 12 in the direction in which it is stretched are alternately exposed at the end face of the base body 10 where the external electrode 20a is provided and at the end face where the external electrode 20b is provided. As a result, each internal electrode layer 12 is alternately conductive to the external electrode 20a and the external electrode 20b. Consequently, the multilayer ceramic capacitor 100 has a structure in which a plurality of dielectric layers 11 are stacked via internal electrode layers 12. Furthermore, in the laminate of dielectric layers 11 and internal electrode layers 12, the outermost layer in the stacking direction is an internal electrode layer 12, and the upper and lower surfaces of the laminate are covered by a cover layer 13. The cover layer 13 is mainly composed of ceramic material. For example, the cover layer 13 may have the same or different composition as the dielectric layer 11.

[0026] The dimensions of the multilayer ceramic capacitor 100 are, for example, 0.25 mm in length, 0.125 mm in width, and 0.125 mm in height; or 0.4 mm in length, 0.2 mm in width, and 0.2 mm in height; or 0.6 mm in length, 0.3 mm in width, and 0.3 mm in height; or 0.6 mm in length, 0.3 mm in width, and 0.110 mm in height; or 1.0 mm in length, 0.5 mm in width, and 0.5 mm in height; or 1.0 mm in length, 0.5 mm in width, and 0.1 mm in height; or 1.6 mm in length, 0.6 mm in width, and 0.8 mm in height; or 3.2 mm in length, 1.6 mm in width, and 1.6 mm in height; or 4.5 mm in length, 3.2 mm in width, and 2.5 mm in height, but are not limited to these dimensions.

[0027] The dielectric layer 11 mainly consists of a ceramic material having a perovskite structure represented by the general formula ABO3. Note that this perovskite structure is an ABO3 structure that deviates from the stoichiometric composition. 3-αIt includes. For example, as the ceramic material, BaTiO3 (barium titanate), CaZrO3 (calcium zirconate), CaTiO3 (calcium titanate), SrTiO3 (strontium titanate), MgTiO3 (magnesium titanate), Ba forming a perovskite structure 1-x-y Ca x Sr y Ti 1-z Zr z O3 (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1), etc., can be selected and used from at least one of them. Ba 1-x-y Ca x Sr y Ti 1-z Zr z O3 is barium strontium titanate, barium calcium titanate, barium zirconate, barium zirconium titanate, calcium zirconium titanate, barium calcium zirconium titanate, barium calcium zirconium strontium titanate, etc.

[0028] An additive may be added to the dielectric layer 11. As additives to the dielectric layer 11, oxides of magnesium (Mg), manganese (Mn), molybdenum (Mo), vanadium (V), chromium (Cr), rare earth elements (yttrium (Y), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm) and ytterbium (Yb)), or oxides containing cobalt (Co), nickel (Ni), lithium (Li), boron (B), sodium (Na), potassium (K) or silicon (Si), or glasses containing cobalt, nickel, lithium, boron, sodium, potassium or silicon can be mentioned.

[0029] The internal electrode layer 12 is mainly composed of base metals such as nickel (Ni), copper (Cu), tin (Sn), etc. As the internal electrode layer 12, noble metals such as platinum (Pt), palladium (Pd), silver (Ag), gold (Au), etc., or alloys containing these may be used.

[0030] As illustrated in Figure 2, the region where the internal electrode layer 12 connected to the external electrode 20a and the internal electrode layer 12 connected to the external electrode 20b face each other is the region in the multilayer ceramic capacitor 100 where capacitance is generated. Therefore, this region where capacitance is generated is referred to as the capacitance section 14. In other words, the capacitance section 14 is the region where adjacent internal electrode layers 12 connected to different external electrodes face each other.

[0031] The region in which internal electrode layers 12 connected to external electrode 20a face each other without being connected to an internal electrode layer 12 connected to external electrode 20b is called the end margin 15. Similarly, the region in which internal electrode layers 12 connected to external electrode 20b face each other without being connected to an internal electrode layer 12 connected to external electrode 20a is also called the end margin 15. In other words, the end margin 15 is the region in which internal electrode layers 12 connected to the same external electrode face each other without being connected to an internal electrode layer 12 connected to a different external electrode. The end margin 15 is a region in which no capacitance is generated. The end margin 15 may have the same composition as the dielectric layer 11 of the capacitance portion 14, or it may have a different composition.

[0032] As illustrated in Figure 3, in the base body 10, the region extending from the two sides of the base body 10 to the internal electrode layer 12 is called the side margin 16. That is, the side margin 16 is a region provided so as to cover the ends of the multiple internal electrode layers 12 stacked in the above-described laminated structure that extend to the two sides. The side margin 16 is also a region that does not generate capacitance. The side margin 16 may have the same composition as the dielectric layer 11 of the capacitance portion 14, or it may have a different composition.

[0033] Figure 4 illustrates a state in which a multilayer ceramic capacitor 100 is mounted on a circuit board 201. As illustrated in Figure 4, the lower surface in the stacking direction is positioned to face the land 203 on the circuit board 201. The first external electrode 20a and the second external electrode 20b are electrically connected to the circuit board 201 independently via solder 202 to the land 203 on the circuit board 201.

[0034] As illustrated in Figures 5(a) and 5(b), a plating layer may be provided on the external electrode 20a, or on the external electrode 20b. During the plating process, the external electrodes 20a and 20b function as underlayers. The plating layer mainly consists of metals such as copper, nickel, aluminum, zinc, and tin, or two or more alloys thereof. The plating layer may be a single-metal component plating layer, or multiple plating layers with different metal components. For example, the plating layer has a structure in which a first plating layer 21, a second plating layer 22, and a third plating layer 23 are formed in order from the underlayer side. The first plating layer 21 is, for example, a copper plating layer. The second plating layer 22 is, for example, a nickel plating layer. The third plating layer 23 is, for example, a tin plating layer.

[0035] Figure 6(a) is a magnified view of the area near the interface between the external electrode 20a and the base body 10. The external electrode 20a will be described below as an example, but the external electrode 20b has a similar structure to the external electrode 20a.

[0036] The external electrode 20a is a sintered body mainly composed of a metal such as copper, and is attached to the base body 10 after firing by firing. The external electrode 20a contains glass 30 to lower the firing temperature. The glass 30 is an oxide of barium, calcium, zinc, aluminum, silicon, magnesium, or boron, for example. Specifically, the glass 30 is a zinc borosilicate glass frit, etc. As illustrated in Figure 6(a), the glass 30 may be inside the external electrode 20a and not in contact with either the dielectric layer 11 or the internal electrode layer 12. On the other hand, the glass 30 may be in contact with at least one of the dielectric layer 11 and the internal electrode layer 12. Thus, there is glass 30 that is in contact with the interface between the base body 10 and the external electrode 20a. The position of the glass 30 at the interface between the external electrode 20a and the base body 10 improves the bonding strength between the external electrode 20a and the base body 10.

[0037] Furthermore, the external electrode 20a includes a crystal 40 that contacts the substrate 10 and the glass 30, as illustrated in Figure 6(a). The crystal 40 contains the same elements as at least one of the elements contained in the dielectric layer 11. The interposition of the crystal 40 at the interface between the external electrode 20a and the substrate 10 improves the bonding strength between the external electrode 20a and the substrate 10. It is thought that the crystal 40 present between the dielectric layer 11 and the glass 30 acts like a wedge, leading to improved bonding strength.

[0038] By obtaining sufficient bonding strength between the external electrode 20a and the base body 10, the firing temperature of the external electrode 20a can be lowered. This suppresses the occurrence of cracks in the base body 10. As a result, sufficient moisture resistance is achieved in the multilayer ceramic capacitor 100. Therefore, the multilayer ceramic capacitor 100 according to this embodiment can achieve high reliability.

[0039] Furthermore, since sufficient bonding strength can be obtained between the external electrode 20a and the base body 10, it is not necessary to add a large amount of glass 30 to the external electrode 20a. In this case, the leaching of glass components onto the outer surface of the external electrode 20a is suppressed, and the plating coverage rate of the plating layer can be increased. For example, in the cross-section of the external electrode 20a, the total area of ​​glass 30 can be reduced to 20% or less, 15% or less, or 12% or less.

[0040] For example, when barium titanate is used as the main ceramic component of the dielectric layer 11, the common elements between the dielectric layer 11 and the crystal 40 are barium, etc. For example, the elements contained in the main ceramic component of the dielectric layer 11 dissolve into the glass component contained in the external electrode paste when the external electrode paste for forming the external electrode 20a is baked, and then re-deposit. The crystal 40 is formed by this re-deposit. The crystal 40 is thought to exist not in the same composition as the main ceramic component of the dielectric layer 11, but rather in a form such as a composite composition of the main ceramic component of the dielectric layer 11 and the glass 30.

[0041] The crystal 40 has a long axis shape and is fibrous (needle-shaped or rod-shaped). When the crystal 40 has a needle-shaped or rod-shaped form, it functions as a wedge connecting the external electrode 20a and the base body 10, thereby increasing the bonding strength between the external electrode 20a and the base body 10.

[0042] If the crystal 40 does not have a sufficiently long axis, there is a risk that sufficient bonding strength cannot be obtained between the external electrode 20a and the base body 10. Therefore, it is preferable to set a lower limit on the long axis of the crystal 40. For example, the long axis of the crystal 40 is preferably 100 nm or more, more preferably 300 nm or more, and even more preferably 600 nm or more. For example, the long axis of the crystal 40 can be directly measured using the length measuring function of an SEM device with a polished sample.

[0043] On the other hand, if the major axis of the crystal 40 is too long, the effect of improving the adhesion strength of the external electrode may not be achieved. This is because the crystal growth will occur along the interface of the external electrode. Therefore, it is preferable to set an upper limit on the major axis of the crystal 40. For example, the major axis of the crystal 40 is preferably 2000 nm or less, more preferably 1500 nm or less, and even more preferably 1000 nm or less.

[0044] If the minor axis of the crystal 40 is too long, its function as a wedge will be weakened, and sufficient adhesion between the external electrode 20a and the base body 10 may not be obtained. Therefore, it is preferable to set a lower limit on the aspect ratio of the crystal 40. Figure 6(b) shows an example of the aspect ratio. First, let the length of the crystal 40 in the cross-section obtained by polishing be length L. Let the average width of each crystal 40 be width W. The aspect ratio is L / W. For example, the aspect ratio of the crystal 40 is 3 to 35, 5 to 20, or 8 to 15.

[0045] If a sufficient amount of crystals 40 are not formed on the external electrode 20a, sufficient bonding strength may not be obtained between the external electrode 20a and the base body 10. Therefore, it is preferable to set a lower limit on the amount of crystals 40. For example, the total area of ​​crystals 40 with respect to the glass cross-section in contact with the base body 10 in the external electrode 20a is preferably 2% or more, more preferably 5% or more, and even more preferably 8% or more.

[0046] On the other hand, if the amount of crystal 40 in the external electrode 20a is large, there is a risk of reduced contact between the internal electrode layer and the external electrode (capacitance loss). Therefore, it is preferable to set an upper limit on the amount of crystal 40. For example, in the glass cross section in contact with the base material 10 in the external electrode 20a, the total area of ​​crystal 40 is preferably 40% or less, more preferably 30% or less, and even more preferably 15% or less.

[0047] Furthermore, as illustrated in Figure 6(a), it is preferable that the crystal 40 extends into the glass 30 from the interface between the external electrode 20a and the base body 10. It is also preferable that the crystal 40 extends through the glass 30 from the interface between the external electrode 20a and the dielectric layer 11. Furthermore, it is preferable that the crystal 40 protrudes into the base body 10 from the interface between the external electrode 20a and the base body 10. With this configuration, the adhesion between the crystal 40 and the glass 30 is improved, and as a result, the bonding strength between the external electrode 20a and the base body 10 is improved.

[0048] Furthermore, according to the EIA standard, the multilayer ceramic capacitor 100 is classified into Class 2, where the main component ceramic of the dielectric layer 11 is a ferroelectric material such as barium titanate, and Class 1, where the main component ceramic of the dielectric layer 11 is a paraelectric material such as zirconate. Since paraelectric materials are chemically stable, there is a risk that sufficient adhesion cannot be obtained between the dielectric layer 11 and the glass 30. Therefore, when the main component ceramic of the dielectric layer 11 is a paraelectric material, providing crystals 40 can compensate for the adhesion between the dielectric layer 11 and the external electrode 20a. From the above, it can be seen that this embodiment is particularly effective when the main component ceramic of the dielectric layer 11 is a paraelectric material.

[0049] Next, the manufacturing method of the multilayer ceramic capacitor 100 will be described. Figure 7 is a diagram illustrating the flow of the manufacturing method of the multilayer ceramic capacitor 100.

[0050] (Process for producing raw material powder) First, a dielectric material is prepared to form the dielectric layer 11. The A-site and B-site elements contained in the dielectric layer 11 are usually present in the form of a sintered body of ABO3 particles. For example, BaTiO3 is a tetragonal compound having a perovskite structure and exhibits a high dielectric constant. This BaTiO3 can generally be obtained by synthesizing barium titanate by reacting a titanium raw material such as titanium dioxide with a barium raw material such as barium carbonate. Various methods have been conventionally known for synthesizing the main component ceramic of the dielectric layer 11, such as the solid-phase method, the sol-gel method, and the hydrothermal method. In this embodiment, any of these can be employed.

[0051] A predetermined additive compound is added to the obtained ceramic powder according to the purpose. Examples of additive compounds include oxides of magnesium (Mg), manganese (Mn), molybdenum (Mo), vanadium (V), chromium (Cr), rare earth elements (yttrium (Y), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), and ytterbium (Yb)), or oxides containing cobalt (Co), nickel (Ni), lithium (Li), boron (B), sodium (Na), potassium (K), or silicon (Si), or glass containing cobalt, nickel, lithium, boron, sodium, potassium, or silicon.

[0052] For example, a ceramic material can be prepared by wet-mixing a ceramic raw material powder with a compound containing an additive, followed by drying and pulverization. For example, the ceramic material obtained as described above may be subjected to pulverization as needed to adjust the particle size, or the particle size may be adjusted by combining this with a classification process. A dielectric material can be obtained through the above steps.

[0053] (Coating process) Next, a binder such as polyvinyl butyral (PVB) resin, an organic solvent such as ethanol or toluene, and a plasticizer are added to the obtained dielectric material and wet-mixed. Using the resulting slurry, a ceramic green sheet 52 is coated onto the substrate 51 by, for example, a die coater or a doctor blade and then dried. The substrate 51 is, for example, a polyethylene terephthalate (PET) film.

[0054] (Internal electrode formation process) Next, as illustrated in Figure 8(a), an internal electrode pattern 53 is deposited on the ceramic green sheet 52. In Figure 8(a), as an example, four layers of the internal electrode pattern 53 are deposited on the ceramic green sheet 52 at predetermined intervals. The ceramic green sheet 52 on which the internal electrode pattern 53 is deposited is used as the stacking unit. A metal paste of the main component metal of the internal electrode layer 12 is used for the internal electrode pattern 53. The deposition method may be printing, sputtering, vapor deposition, etc.

[0055] (Crimping process) Next, the ceramic green sheet 52 is peeled off the substrate 51 and the laminate units are stacked as illustrated in Figure 8(b). Then, a predetermined number of cover sheets 54 (for example, 2 to 10 layers) are stacked on the top and bottom of the laminate obtained by stacking the laminate units and heat-pressed, and then cut to a predetermined chip size (for example, 1.0 mm × 0.5 mm). In the example in Figure 8(b), the cut is made along the dotted line. The cover sheet 54 may have the same composition as the ceramic green sheet 52, or it may have different additives.

[0056] (Firing process) Subsequently, oxygen partial pressure 10 -5 ~10 -8 The material is fired in an ATM reducing atmosphere at 1100°C to 1300°C for 10 minutes to 2 hours. In this way, the base material 10 can be obtained.

[0057] (Re-oxidation process) Subsequently, a re-oxidation treatment may be performed in an N2 gas atmosphere at 600°C to 1000°C.

[0058] (Activation process) Next, the two end faces of the substrate 10 where the internal electrode layer 12 is exposed are subjected to an activation treatment to increase surface activity. For example, the two end faces of the substrate 10 are immersed in hydrochloric acid, then washed with pure water and dried. Alternatively, the two end faces of the substrate 10 may be subjected to sandblasting to increase surface activity. In addition, the two end faces of the substrate 10 may be subjected to laser treatment, corona treatment, or other methods to increase surface activity.

[0059] (Coating process) Next, external electrode paste, which will become the external electrodes 20a and 20b, is applied to the two end faces of the base body 10 using a dipping method or the like. The external electrode paste contains the main component metal of the external electrodes 20a and 20b, as well as glass frit.

[0060] (External electrode formation process) Next, the external electrodes 20a and 20b are formed by baking the external electrode paste at a temperature of approximately 700°C to 900°C.

[0061] (Plating process) Subsequently, a metal coating such as copper, nickel, or tin may be applied to the external electrodes 20a and 20b by plating.

[0062] According to the manufacturing method of this embodiment, by performing an activation treatment, the elements contained in the main component ceramic of the dielectric layer 11 dissolve in the glass component contained in the external electrode paste and then re-deposit. As a result, crystals 40 are formed. Therefore, sufficient bonding strength is achieved between the external electrodes 20a, 20b and the base body 10. Because sufficient bonding strength is obtained between the external electrodes 20a, 20b and the base body 10, the baking temperature of the external electrode paste can be lowered. For example, the baking temperature of the external electrode paste can be set to 750°C or higher and 850°C or lower. As a result, the occurrence of cracks in the base body 10 can be suppressed. As a result, sufficient moisture resistance is achieved in the multilayer ceramic capacitor 100. From the above, the multilayer ceramic capacitor 100 according to this embodiment can achieve high reliability.

[0063] Although the above embodiments describe multilayer ceramic capacitors as an example of ceramic electronic components, they are not limited to this. For example, the configurations of the above embodiments can also be applied to other multilayer ceramic electronic components such as varistors and thermistors. [Examples]

[0064] Below, a multilayer ceramic capacitor according to the embodiment was fabricated and its characteristics were investigated.

[0065] (Example 1) (Ba) 0.1 Ca 0.4 Sr 0.5 )(Zr 0.95 Ti 0.05 0.5 wt% silicon dioxide and 0.5 wt% manganese oxide were added to 3, and an organic solvent, organic binder, plasticizer, and dispersant were added and mixed to make a dielectric slurry. Using coating equipment, a ceramic green sheet with a thickness of 3.5 μm was coated. Nickel paste was printed on the ceramic green sheet as an internal electrode pattern and dried, then a predetermined number of sheets were laminated and pressed together, and cut to a predetermined size. The cut ceramic laminates were fired by weak reduction firing with nitrogen gas to obtain a base body. After firing, as an acid treatment, at least the end face of the base body (the side where the internal electrode layer is exposed) was immersed in hydrochloric acid, followed by pure washing and drying.

[0066] Subsequently, a Cu external electrode paste containing zinc borosilicate glass frit and a binder was applied to the end face of the substrate. After drying the Cu external electrode paste, it was baked at 780°C in a low-oxygen atmosphere, followed by nickel plating and tin plating. Through the above process, a multilayer ceramic capacitor with a dielectric layer thickness of 2.5 μm and a 1608 shape (length 1.6 mm, width 0.6 mm, height 0.8 mm) was obtained.

[0067] (Example 2) The curing temperature of the Cu external electrode paste was set to 800°C. All other conditions were the same as in Example 1.

[0068] (Example 3) The curing temperature of the Cu external electrode paste was set to 850°C. All other conditions were the same as in Example 1.

[0069] (Example 4) Instead of acid treatment, sandblasting was performed on the end faces of the base material. The Cu baking temperature was set to 800°C. All other conditions were the same as in Example 1.

[0070] (Comparative Example 1) In Comparative Example 1, no acid treatment was performed on the end faces of the substrate. All other conditions were the same as in Example 1.

[0071] (Comparative Example 2) In Comparative Example 2, the end faces of the substrate were not treated with acid. All other conditions were the same as in Example 2.

[0072] (Comparative Example 3) In Comparative Example 3, the end faces of the substrate were not treated with acid. All other conditions were the same as in Example 3.

[0073] (Crack test) For each of the 50 samples from Examples 1-4 and Comparative Examples 1-3, the presence or absence of cracks in the external appearance was checked, and the presence or absence of cracks in the cross-section obtained after resin embedding and polishing was also checked. When checking the cross-section, it was checked whether crystals of fibrous particles containing barium, having a length of 100 nm to 500 nm, and in contact with the glass component of the external electrode were formed between the base material and the external electrode. If fibrous particles were confirmed, it was judged as "fiber particles present". If fibrous particles were not confirmed, it was judged as "fiber particles absent". If even one sample showed cracks, it was judged as "cracks present". If no samples showed cracks, it was judged as "cracks absent".

[0074] (Humidity load test) For each of the 40 samples from Examples 1-4 and Comparative Examples 1-3, a 1000-hour humidity load test was performed on a substrate under the conditions of 85°C, 85% relative humidity, and DC 100V after mounting the samples. Characteristic degradation (decreased insulation and reduced capacitance) and external abnormalities (e.g., cracks and peeling of external electrodes) were checked. If at least one sample showed at least one characteristic degradation or external abnormality, the humidity load test was judged as a failure ("×"). If no sample showed at least one exceptional degradation or external abnormality, the humidity load test was judged as a pass ("〇").

[0075] (Adhesion strength test) For each of the 20 samples from Examples 1-4 and Comparative Examples 1-3, after reflow mounting onto a designated substrate, a pressure of 20N was applied from the side for 60 seconds. If even one sample showed delamination of the external electrode, the adhesion strength was judged as failing ("×"). If no samples showed delamination of the external electrode, the adhesion strength was judged as passing ("〇").

[0076] (Overall assessment) If the test was judged as "no cracks," the moisture load resistance was judged as passing ("○"), and the adhesion strength was judged as passing ("○"), the overall judgment was judged as passing ("○"). If the test was judged as "cracks present," or if at least one of the moisture load resistance and adhesion strength was judged as failing ("×"), the overall judgment was judged as failing ("×"). The results of each test are shown in Table 1. [Table 1]

[0077] First, in Examples 1-4, crystals of fiber particles containing at least one of the same elements (barium) as those in the dielectric layer were observed in contact with the base material and the glass of the external electrodes. This is thought to be because activation treatment was performed on both ends of the base material before the external electrode paste was baked on. On the other hand, no crystals of fiber particles were observed in Comparative Examples 1-3. This is thought to be because activation treatment was not performed on both ends of the base material before the external electrode paste was baked on.

[0078] In all of Examples 1-4, the overall evaluation was judged as a pass ("○"). This is thought to be because crystals of fiber particles formed between the substrate and the external electrode, improving reliability.

[0079] In contrast, Comparative Examples 1-3 received an overall failing grade ("×"). In Comparative Example 1, although no cracks were observed, the moisture load resistance and adhesion strength were judged as failing grades ("×"). This is thought to be because, although cracks did not occur due to the low curing temperature of the Cu external electrode paste, sufficient moisture resistance and sufficient adhesion strength could not be obtained because fiber particles were not formed. In Comparative Examples 2 and 3, although adhesion strength was obtained by increasing the curing temperature of the Cu external electrode, cracks occurred because fiber particles were not formed, and sufficient moisture resistance could not be obtained.

[0080] Although embodiments of the present invention have been described in detail above, the present invention is not limited to these specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention as described in the claims. [Explanation of symbols]

[0081] 10 Base Body 11 Dielectric layer 12 Internal electrode layer 13. Cover layer 14 Capacity part 15 End margin 16 Side margins 20a,20b external electrode 30 Glass 40 crystal 51 Base material 52 Ceramic Green Sheet 53 Internal electrode pattern 100 Multilayer Ceramic Capacitors

Claims

1. an element body having a plurality of dielectric layers and a plurality of internal electrode layers stacked with the plurality of dielectric layers interposed therebetween, facing each other, and provided with one end exposed; an external electrode including glass, the external electrode being provided on an end surface of the element body that is an end in a direction in which the plurality of internal electrode layers extend, and contacting the one end of each of the plurality of internal electrode layers; the external electrode includes a crystal that contacts the element body and the glass or extends into the glass; The crystals contain the same element as at least one of the elements contained in the plurality of dielectric layers.

2. 2. The multilayer ceramic electronic component according to claim 1, wherein the element contained in at least one of the plurality of dielectric layers is barium.

3. 3. The multilayer ceramic electronic component according to claim 1, wherein the crystals are needle-shaped or rod-shaped crystals.

4. 3. The multilayer ceramic electronic component according to claim 1, wherein the major axis of said crystals is 100 nm or more.

5. 3. The multilayer ceramic electronic component according to claim 1, wherein the plurality of dielectric layers contain zirconate.

6. 3. The multilayer ceramic electronic component according to claim 1, wherein the external electrodes are mainly composed of copper.

7. 3. The multilayer ceramic electronic component according to claim 1, which is a Class 1 capacitor.

8. 3. A circuit board provided with the multilayer ceramic electronic component according to claim 1.

9. an activation treatment step of activating a surface of an end face of the element body, which is an end in a direction in which the plurality of internal electrode layers extend, in the element body having a plurality of dielectric layers and a plurality of internal electrode layers stacked via the plurality of dielectric layers, facing each other, and provided so that one end is exposed; an external electrode forming step of applying and baking an external electrode paste containing glass to the surface activated by the activation treatment step to form external electrodes, and forming crystals in the external electrodes that contain the same element as at least any of the elements contained in the plurality of dielectric layers and that contact the element body and the glass or extend within the glass.

10. 10. The method for producing a multilayer ceramic electronic component according to claim 9, wherein the element identical to at least one of the elements contained in the plurality of dielectric layers is barium.

11. 11. The method for producing a multilayer ceramic electronic component according to claim 9, wherein the activation treatment step is an acid immersion treatment or a sandblasting treatment.

12. The method for producing a multilayer ceramic electronic component according to claim 11, wherein hydrochloric acid is used in the activation treatment step.

13. 11. The method for manufacturing a multilayer ceramic electronic component according to claim 9, wherein in the external electrode forming step, the crystals are formed by melting, in the glass, an element identical to at least any one of the elements contained in the plurality of dielectric layers, and then re-precipitating the element.

14. 11. The method for producing a multilayer ceramic electronic component according to claim 9, wherein the crystals are rod-shaped or needle-shaped crystals.

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