Multilayer ceramic electronic components and methods for manufacturing the same

Abstract

To provide a multilayer ceramic electronic component capable of suppressing generation of a crack, and provide a manufacturing method.SOLUTION: A multilayer ceramic electronic component 100 includes: an element body 10 including a plurality of dielectric laminations 11 and a plurality of inner electrode layers 12 that is laminated via the plurality of dielectric laminations 11, is opposite each other, and of which one end is provided so as to be exposed; a first outer electrode 21 that is provided to a side surface of the element body 10 as an end in a direction where the plurality of inner electrode layers 12 is extended, and is contacted to one end of each of the plurality of inner electrode layers 12, and contains a common material 23; and a second outer electrode 22 that is provided onto the first outer electrode 21, contains a glass 24, and uses a metal similar to the first outer electrode 21 as a main component.SELECTED DRAWING: Figure 6

Description

[Technical Field]

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

[0002] Multilayer ceramic electronic components are used in high-frequency communication systems, such as mobile phones. For example, multilayer ceramic capacitors are used to remove noise (see, for example, Patent Documents 1-4). Metals such as Ag, Ni, and Cu, or conductive resins are commonly used for the external electrodes of multilayer ceramic electronic components. Among these, Ni and Cu are widely used, and it is common for them to be plated with Cu, Ni, and Sn. This is due to many favorable reasons, such as reduction resistance (the Ni internal electrode acts as an external electrode in an atmosphere where it does not oxidize), ion migration resistance, ensuring contact with the internal electrode, lowering the equivalent series resistance (ESR), and low cost. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2018-098327 [Patent Document 2] Japanese Patent Publication No. 2018-014407 [Patent Document 3] Japanese Patent Publication No. 2019-195037 [Patent Document 4] Japanese Patent Publication No. 2020-155719 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] External electrodes come in two types: those formed afterwards and those formed during co-firing. For external electrodes formed afterwards, a metal paste is applied and fired onto the base body after firing. For external electrodes formed during co-firing, a metal paste is applied to an unfired base body, and both the base body and the metal paste are fired simultaneously. In either of these types, there is a risk of cracking in the base body.

[0005] This invention has been made in view of the above problems, and aims to provide a multilayer ceramic electronic component and a method for manufacturing the same that can suppress the occurrence of cracks. [Means for solving the problem]

[0006] The multilayer ceramic electronic component according to the present invention comprises a base 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 having one end exposed; a first external electrode provided on the side surface of the base body which is the end in the direction in which the plurality of internal electrode layers are extended, in contact with each of the one ends of the plurality of internal electrode layers, and containing the same material; and a second external electrode provided on the first external electrode, containing glass and having the same metal as the first external electrode as its main component.

[0007] In the above-described multilayer ceramic electronic component, the second external electrode may be in contact with the main surface of the element, which is the end in the direction in which the plurality of dielectric layers and the plurality of internal electrode layers are stacked, and with the corner of the element.

[0008] In the above-described multilayer ceramic electronic component, the plurality of internal electrodes may have the same metal as the first external electrode as their main component.

[0009] In the above-described multilayer ceramic electronic component, the first external electrode and the second external electrode may be in direct contact with each other.

[0010] In the above-described multilayer ceramic electronic component, the common material may be a metal oxide.

[0011] In the above-described multilayer ceramic electronic component, the plurality of internal electrode layers, the first external electrode, and the second external electrode are mainly composed of nickel, and the common material may contain at least one of aluminum oxide or barium titanate.

[0012] In the above-described multilayer ceramic electronic component, the plurality of internal electrodes, the first external electrode, and the second external electrode are mainly composed of copper, and the common material may contain at least one of aluminum oxide or calcium zirconate.

[0013] In the direction in which the multiple internal electrodes of the multilayer ceramic electronic component are stretched, the thickness of the first external electrode may be 5 μm or less.

[0014] In the above-described multilayer ceramic electronic component, the common material may be present in an amount of 5 wt% to 20 wt% relative to the first external electrode.

[0015] The above-mentioned multilayer ceramic electronic component may further have a plating layer on the second external electrode.

[0016] Another multilayer ceramic electronic component according to the present invention includes a base 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 having one end exposed, and an external electrode provided on the side surface of the base body which is the end in the direction in which the plurality of internal electrode layers are stretched, and having a first region in contact with one end of the plurality of internal electrode layers and a second region covering the first region, wherein the first region has a higher content of the same material than the second region, and the second region has a higher content of glass than the first region.

[0017] In the above-mentioned other multilayer ceramic electronic components, the second region may be in contact with the main surface of the element, which is the edge in the direction in which the plurality of dielectric layers and the plurality of internal electrode layers are stacked, and with the corners of the element.

[0018] In the above-mentioned other multilayer ceramic electronic component, the plurality of internal electrode layers may contain the same metal as the main component as the external electrode.

[0019] In the above-mentioned other multilayer ceramic electronic component, the co-material may be a metal oxide.

[0020] In the above-mentioned other multilayer ceramic electronic component, the plurality of internal electrode layers and the external electrode contain nickel as the main component, and the co-material may contain at least one of alumina or barium titanate.

[0021] In the above-mentioned other multilayer ceramic electronic component, the plurality of internal electrode layers and the external electrode contain copper as the main component, and the co-material may contain at least one of alumina or calcium zirconate.

[0022] The above-mentioned other multilayer ceramic electronic component may further have a plating layer on the external electrode. <00 / /

[0023] The method for manufacturing a multilayer ceramic electronic component according to the present invention includes a coating step of forming a ceramic green sheet, a printing step of forming an internal electrode pattern using a conductive paste on the ceramic green sheet, a pressing step of laminating the ceramic green sheets to obtain an unfired body, a metal paste forming step of forming a metal paste containing a co-material on the side surface of the unfired body, a firing step of firing the unfired body and the metal paste to form a first external electrode from the metal paste, and a second external electrode forming step of forming a second external electrode containing glass covering the first external electrode after the firing step.

[0024] The method for manufacturing the multilayer ceramic electronic component may further include a plating step of forming a plating layer on the second external electrode. <000 / /

Advantages of the Invention

[0025] According to the present invention, it is possible to provide a multilayer ceramic electronic component and a method for manufacturing the same that can suppress the occurrence of cracks. [Brief explanation of the drawing]

[0026] [Figure 1] This 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] (a) and (b) are diagrams illustrating the addition of external electrodes. [Figure 5] This is a diagram illustrating the external electrodes used in co-firing. [Figure 6] This is a magnified cross-sectional view of the external electrode. [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. [Figure 9] (a) is a diagram illustrating the coating process, and (b) is a diagram illustrating the baking process. [Modes for carrying out the invention]

[0027] The embodiments will be described below with reference to the drawings.

[0028] 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.

[0029] 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.

[0030] The size of the multilayer ceramic capacitor 100 is, for example, a length of 0.25 mm, a width of 0.125 mm, and a height of 0.125 mm, or a length of 0.4 mm, a width of 0.2 mm, and a height of 0.2 mm, or a length of 0.6 mm, a width of 0.3 mm, and a height of 0.3 mm, or a length of 0.6 mm, a width of 0.3 mm, and a height of 0.110 mm, or a length of 1.0 mm, a width of 0.5 mm, and a height of 0.5 mm, or a length of 1.0 mm, a width of 0.5 mm, and a height of 0.1 mm, or a length of 3.2 mm, a width of 1.6 mm, and a height of 1.6 mm, or a length of 4.5 mm, a width of 3.2 mm, and a height of 2.5 mm, but is not limited to these sizes.

[0031] The dielectric layer 11 mainly consists of, for example, a ceramic material having a perovskite structure represented by the general formula ABO3. Note that the perovskite structure contains ABO 3-α deviating from the stoichiometric composition. For example, as the ceramic material, BaTiO3 (barium titanate), CaZrO3 (calcium zirconate), CaTiO3 (calcium titanate), SrTiO3 (strontium titanate), MgTiO3 (magnesium titanate), Ba 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, and barium calcium zirconium titanate, etc.

[0032] Additives may be added to the dielectric layer 11. Examples of additives to the dielectric layer 11 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), holomium (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.

[0033] The internal electrode layer 12 mainly consists of base metals such as nickel (Ni), copper (Cu), and tin (Sn). Precious metals such as platinum (Pt), palladium (Pd), silver (Ag), and gold (Au), or alloys containing these, may also be used as the internal electrode layer 12.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] Here, we will consider external electrodes. First, we will describe an external electrode that is added later, which is obtained by firing an unfired base body in which multiple stacked units, each containing a ceramic green sheet for the dielectric layer 11 with an internal electrode pattern for the internal electrode layer 12 printed on it, are stacked, then the base layer is fired, and finally the plating layer is formed.

[0038] Figures 4(a) and 4(b) illustrate the addition of external electrodes. In Figures 4(a) and 4(b), the hatches on the base body 10 are omitted. As illustrated in Figure 4(a), the base layer 31 is baked onto the base body 10 after firing by heat-treating a metal paste. To lower the temperature of the heat treatment for baking, low-melting-point glass 32 is added to the metal paste. Since the base body 10 has high strength after firing, the occurrence of cracks and other defects can be suppressed when baking the base layer 31. However, the glass 32 reacts with the base body 10, and cracks 40 may occur at the joint of the base layer 31.

[0039] Furthermore, during the firing of the base body 10, the protruding portion of the internal electrode layer 12 may retract into the base body 10 due to shrinkage during the sintering process. In this case, there is a risk that electrical contact between the base layer 31 and the internal electrode layer 12 cannot be obtained. Therefore, it is conceivable to expose the protruding portion of the internal electrode layer 12 by scraping the surface of the base body 10. However, this would complicate the process and increase costs. There is also a risk of mechanical damage remaining.

[0040] If glass 32 is not used, the heat treatment for firing must be performed at a high temperature. In this case, the pull-out portion of the internal electrode layer 12 will retract into the base body 10, and as illustrated in Figure 4(b), the spheroidization of each position of the internal electrode layer 12 will progress, which may reduce the continuity of the internal electrode layer 12.

[0041] Furthermore, when the base body 10 is fired, the small amount of oxygen in the furnace may cause oxidation of the outermost surface of the pull-out portion of the internal electrode layer 12, potentially preventing electrical contact between the base layer 31 and the internal electrode layer 12.

[0042] Next, we will describe a co-fired external electrode obtained by applying a metal paste for the base layer to an unfired substrate, which consists of multiple stacked units in which an internal electrode pattern for the internal electrode layer 12 is printed on a ceramic green sheet for the dielectric layer 11, firing them simultaneously, and then forming a plating layer.

[0043] Figure 5 is a diagram illustrating the external electrode for simultaneous firing. In Figure 5, the hatching of the base body 10 has been omitted. Due to a mismatch between the shrinkage of the base body and the shrinkage of the base layer 33 during firing, cracks 40 may occur at the joints of the base layer 33. Therefore, a method is employed in which a co-material 34 such as metal oxide powder is added to the metal paste to slow down the shrinkage of the metal paste. However, because a certain thickness is required for the base layer 33, cracks 40 may still occur due to a mismatch between the shrinkage of the base body and the shrinkage of the base layer 33 during firing.

[0044] Furthermore, although electrical contact is ensured between the base layer 33 and the internal electrode layer 12, the common material 34 is exposed on the outer surface of the base layer 33, as illustrated in Figure 5. In this case, the plating may not adhere properly, potentially resulting in plating defects.

[0045] Therefore, the external electrodes 20a and 20b according to this embodiment have a configuration that can suppress the occurrence of cracks. Furthermore, the external electrodes 20a and 20b according to this embodiment have a configuration that can ensure electrical contact with the internal electrode layer 12, suppress a decrease in the continuity rate of the internal electrode layer 12, and suppress plating defects.

[0046] Figure 6 is an enlarged cross-sectional view of the external electrode 20b. In Figure 6, the hatch of the base body 10 has been omitted. As illustrated in Figure 6, the external electrode 20b has a structure in which a second external electrode 22 is provided on a first external electrode 21. The first external electrode 21 contains a common material 23. The second external electrode 22 contains glass 24. The main components of the first external electrode 21 and the second external electrode 22 are common. A plating layer 25 is provided on the second external electrode 22.

[0047] The first external electrode 21 contains the same material 23 and is therefore formed by simultaneous firing with the base body 10. The second external electrode 22 contains glass 24 and is therefore formed by post-firing after the base body 10 has been fired.

[0048] In the process of simultaneously firing the base body 10 and the first external electrode 21, the second external electrode 22 is formed, so it is not necessary to form the first external electrode 21 thicker than the others. Therefore, the stress during the simultaneous firing of the first external electrode 21 is relieved, and the occurrence of cracks can be suppressed. In addition, since the first external electrode 21 is positioned between the second external electrode 22 and the base body 10, the diffusion of glass 24 into the base body 10 is suppressed, and the occurrence of cracks is suppressed. Furthermore, since the second external electrode 22 containing glass 24 can be fired at a low temperature (for example, around 800°C), the occurrence of cracks is suppressed. Moreover, since the main component of the first external electrode 21 and the main component of the second external electrode 22 are the same metal, a strong bond is obtained between the first external electrode 21 and the second external electrode 22, and interfacial delamination is suppressed even when stress is applied.

[0049] From the above, the external electrode 20b according to this embodiment can suppress the occurrence of cracks. Since the external electrode 20a also has a laminated structure similar to that of the external electrode 20b, the external electrode 20a can also suppress the occurrence of cracks.

[0050] Furthermore, since the internal electrode layer 12 and the first external electrode 21 are integrated, electrical contact failures caused by the recession of the protruding portion of the internal electrode layer 12 are suppressed. Also, since the second external electrode 22 can be baked at a relatively low temperature, a decrease in the continuity of the internal electrode layer 12 can be suppressed. In addition, since the first external electrode 21 is covered by the second external electrode 22, surface exposure of the common material 23 is suppressed, and plating defects can be suppressed. Even if glass 24 is exposed on the outer surface of the second external electrode 22, the glass phase, unlike the common material, exists as a very thin glass film formed from solidified liquid phase that has seeped to the surface, and can be easily removed by general surface treatment (mechanical or chemical treatment) before plating.

[0051] Since the second external electrode 22 can be baked at a low temperature, crack formation can be suppressed even if the second external electrode 22 is formed thickly. Therefore, the thickness of the second external electrode 22 can be adjusted according to the product specifications. The material and number of plating layers formed on the second external electrode 22 can be freely set.

[0052] Preferably, the second external electrode 22 extends so as to be in contact with at least one of the top surface, bottom surface, and two sides of the base body 10, and its corner (edge). The corner is the part of the base body 10 that has curvature at its corner. In this configuration, the first external electrode 21 does not extend to the point where the second external electrode 22 contacts the base body 10. In this configuration, the contact interface between the first external electrode 21 and the base body 10 is reduced, which can suppress the occurrence of cracks during simultaneous firing of the base body 10 and the first external electrode 21.

[0053] Furthermore, since cracks are highly likely to occur on the top, bottom, and two sides of the base body 10 during simultaneous firing, crack occurrence can be effectively suppressed by not extending the first external electrode 21 to these areas. In addition, for multilayer ceramic capacitors, the dimensions of the external electrodes that wrap around to the top, bottom, and two sides are sometimes determined by product specifications due to component mounting requirements. In such cases, the second external electrode 22 can be extended.

[0054] It is preferable that the main component of the internal electrode layer 12 is the same metal as the main component of the first external electrode 21. In this case, alloying between the first external electrode 21 and the internal electrode layer 12 is suppressed, and the volume expansion of the internal electrode layer 12 within the base body 10 is suppressed. This makes it possible to suppress cracks caused by volume expansion. For example, if the main component of the first external electrode 21 is nickel, it is preferable that the main component of the internal electrode layer 12 is also nickel. If the main component of the first external electrode 21 is copper, it is preferable that the main component of the internal electrode layer 12 is also copper.

[0055] Preferably, the second external electrode 22 is provided in direct contact with the first external electrode 21. In this case, a stronger bond is obtained between the first external electrode 21 and the second external electrode 22, which are mainly composed of the same metal, and interfacial delamination is suppressed even when stress is applied.

[0056] The material of the co-material 23 is not particularly limited, but it is preferably a metal oxide (ceramic) other than glass. In this case, during co-firing, the shrinkage of the first external electrode 21 is delayed, the difference in shrinkage between the base body 10 and the first external electrode 21 becomes smaller, and the occurrence of cracks is suppressed. For example, the ceramic main component of the dielectric layer 11 can be used as the co-material 23. Other materials that can be used as the co-material 23 include barium titanate (BaTiO3), aluminum oxide (Al2O3), zirconium oxide (ZrO2), calcium oxide (CaO), magnesium oxide (MgO), and calcium zirconate (CaZrO3).

[0057] When the main component of the internal electrode layer 12, the first external electrode 21, and the second external electrode 22 is nickel, the co-material 23 is preferably aluminum oxide or barium titanate. This is because barium titanate is commonly used as the main phase of the dielectric layer 11 when nickel is used in the internal electrode layer 12, and the co-material is preferably one that minimizes the deformation of the structure and electrical properties of the dielectric layer 11 even when diffused into the dielectric layer 11.

[0058] When the main components of the internal electrode layer 12, the first external electrode 21, and the second external electrode 22 are copper, the common material 23 is preferably aluminum oxide or calcium zirconate (CaZrO3). This is because calcium zirconate is commonly used as the main phase of the dielectric layer 11 when copper is used in the internal electrode layer 12, and it is preferable to use a common material that minimizes the deformation of the structure and electrical properties of the dielectric layer 11 even when diffused into the dielectric layer 11.

[0059] In the direction in which the internal electrode layer 12 extends (the direction in which the external electrodes 20a and 20b face each other), the thickness of the first external electrode 21 is preferably 5 μm or less. In this case, the first external electrode 21 becomes thinner, and even if the base body 10 and the first external electrode 21 are fired simultaneously, the stress caused by the difference in shrinkage between the base body 10 and the first external electrode 21 is reduced, and the occurrence of cracks can be suppressed. The thickness of the first external electrode 21 is more preferably 3 μm or less, and even more preferably 2 μm or less.

[0060] If the content of the common material 23 in the first external electrode 21 is low, the stress caused by the difference in shrinkage between the base body 10 and the first external electrode 21 may not be sufficiently reduced, potentially leading to crack formation. Therefore, it is preferable to set a lower limit on the content of the common material 23 in the first external electrode 21. On the other hand, if the content of the common material 23 in the first external electrode 21 is high, the bonding between the first external electrode 21 and the second external electrode 22 may be inhibited, potentially reducing the bonding strength. Therefore, it is preferable to set an upper limit on the content of the common material 23 in the first external electrode 21. For example, the content of the common material 23 in the first external electrode 21 is preferably 5 wt% or more and 20 wt% or less of the total content of the first external electrode 21. In this case, the bonding between the first external electrode 21 and the second external electrode 22 is strengthened by the anchoring effect, and interfacial delamination is suppressed. The content of the common material 23 in the first external electrode 21 is more preferably 7 wt% or more and 15 wt% or less relative to the total amount of the first external electrode 21, and even more preferably 10 wt% or more and 13 wt% or less.

[0061] The material of the glass 24 in the second external electrode 22 is not particularly limited, but is selected according to the firing temperature of the second external electrode 22. For example, the material of the glass 24 is preferably a glass with a silicon oxide (SiO2) backbone containing Li, B, Al, Ba, Sr, Zn, etc.

[0062] If the glass content 24 in the second external electrode 22 is low, adhesion with the base body 10 may be insufficient, and delamination may occur. Therefore, it is preferable to set a lower limit on the glass content 24 in the second external electrode 22. On the other hand, if the glass content 24 in the second external electrode 22 is high, bonding with the first external electrode 21 may be insufficient, and delamination may occur. Therefore, it is preferable to set an upper limit on the glass content 24 in the second external electrode 22. For example, the glass content 24 in the second external electrode 22 is preferably 3 wt% or more and 18 wt% or less of the total amount of the second external electrode 22, more preferably 4 wt% or more and 12 wt% or less, and even more preferably 5 wt% or more and 8 wt% or less.

[0063] Furthermore, since the co-material is intended to slow down the sintering of the metal components, glass, which acts as a sintering accelerator, is not used in the same layer. Therefore, whether or not the first external electrode 21 is a co-fired external electrode can be determined by whether or not the co-material is included. On the other hand, since the second external electrode 22 contains glass, it is clear that it was added later by heat treatment at a relatively low temperature (e.g., 1100°C or below). A pure metal film that does not contain either the co-material or glass is a film formed by sputtering or the like, and is therefore different from both the first external electrode 21 and the second external electrode 22 in this embodiment.

[0064] During the process of baking the second external electrode 22, the common material 23 may diffuse into the second external electrode 22, and the glass 24 may diffuse into the first external electrode 21. In this case, the first external electrode 21 (first region) will have a higher content of the common material 23 and a lower content of the glass 24 than the second external electrode 22. The second external electrode 22 (second region) will have a lower content of the common material 23 and a higher content of the glass 24 than the first external electrode 21.

[0065] 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.

[0066] (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.

[0067] 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), holomium (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. Of these, SiO2 mainly functions as a sintering aid.

[0068] 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.

[0069] (Lamination 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 raw material powder 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 doctor blade method and then dried. The substrate 51 is, for example, a PET (polyethylene terephthalate) film.

[0070] 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 has been deposited is used as the stacking unit.

[0071] A metal paste of the main component metal of the internal electrode layer 12 is used for the internal electrode pattern 53. The film deposition method may be printing, sputtering, or vapor deposition.

[0072] Next, the ceramic green sheet 52 is peeled off the substrate 51, and the stacking units are stacked as illustrated in Figure 8(b).

[0073] Next, a predetermined number of cover sheets 54 (for example, 2 to 10 layers) are laminated on the top and bottom of the laminate obtained by stacking the laminate units, and then heat-pressed onto them, and cut to a predetermined chip size (for example, 1.0 mm x 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.

[0074] (Coating process) The ceramic laminate obtained in this manner is subjected to a binder removal treatment in an N2 atmosphere, and then a metal paste 26, which will become the first external electrode 21, is applied by a dipping method or the like, as illustrated in Figure 9(a). The metal paste 26 contains the same material 23. For example, the metal paste 26 is applied to two end faces of the laminate where the internal electrode pattern 53 is exposed.

[0075] (Firing process) Subsequently, oxygen partial pressure 10 -5 ~10 -8 The substrate 10 and the first external electrode 21 are fired at 1100-1300°C for 10 minutes to 2 hours in an atm reducing atmosphere.

[0076] (Re-oxidation process) Subsequently, a re-oxidation treatment may be performed in an N2 gas atmosphere at 600°C to 1000°C.

[0077] (Baking process) Next, as illustrated in Figure 9(b), a metal paste 27, which will become the second external electrode 22, is applied to the first external electrode 21 by a dipping method or the like. The metal paste 27 contains glass 24. For example, the metal paste 27 is applied so as to extend to at least one of the four faces of the laminate other than the two end faces where the internal electrode layer 12 is exposed. Then, the second external electrode 22 is formed by baking the metal paste 27 at, for example, about 700°C to 900°C.

[0078] (Plating process) Subsequently, a metal coating such as Cu, Ni, or Sn may be applied to the second external electrode 22 by plating.

[0079] According to the manufacturing method of this embodiment, since the second external electrode 22 is formed during the process of simultaneously firing the base body 10 and the first external electrode 21, it is not necessary to form the first external electrode 21 thicker than the others. Therefore, the stress during the simultaneous firing of the first external electrode 21 is reduced, and the occurrence of cracks can be suppressed. In addition, since the first external electrode 21 is positioned between the second external electrode 22 and the base body 10, the diffusion of glass 24 into the base body 10 is suppressed, and the occurrence of cracks is suppressed. Furthermore, since the second external electrode 22 containing glass 24 can be fired at a low temperature (for example, around 800°C), the occurrence of cracks is suppressed. Moreover, since the main component of the first external electrode 21 and the main component of the second external electrode 22 are the same metal, a strong bond is obtained between the first external electrode 21 and the second external electrode 22, and interfacial delamination is suppressed even when stress is applied. From the above, the external electrode 20b according to this embodiment can suppress the occurrence of cracks. Since the external electrode 20a has the same layered structure as the external electrode 20b, crack formation can also be suppressed in the external electrode 20a.

[0080] 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]

[0081] Below, a multilayer ceramic capacitor according to the embodiment was fabricated and its characteristics were investigated.

[0082] (Examples) BaTiO3 with an average particle size of 150 nm was used as the main raw material, and trace amounts of Ho2O3, MgO, MnCO3, and SiO2 were added and mixed to form a powder. This powder was dispersed in an organic solvent, slurred, and then a binder was added. The mixture was coated onto a PET film to a predetermined thickness and dried to obtain a ceramic green sheet. An internal electrode pattern of Ni was printed onto the sheet to form an internal electrode pattern. 100 of these laminated units were stacked, and then sandwiched between ceramic green sheets without Ni printing and pressed together. After pressing, the sheets were cut into 3216-shaped pieces and heat-treated (binder removal) in an N2 atmosphere. Subsequently, Ni metal paste (containing 10 wt% BaTiO3 powder) was dipped into the two exposed end faces of the pieces, and then fired at 1250°C in a N2-H2-H2O mixed gas. The amount of dipping was adjusted so that the thickness of the first external electrode after sintering was 5 μm or less on average. The fired sample was dipped with a Ni metal paste (containing 20 wt% glass composed of Si-Li-Zn-O). The dipping amount was adjusted so that it wrapped around the top, bottom, and two sides to approximately 0.5 mm. The second external electrode was fired at 800°C for 10 minutes in an N2 atmosphere. Subsequently, electroplating was formed on the second external electrode in the order of Cu, Ni, and Sn.

[0083] The obtained multilayer ceramic capacitor was confirmed to have a structure in which a second external electrode containing glass (without the cohesive material) covers the outside of a first external electrode containing the same material. Specifically, 20 chips were randomly selected from a large number of chips produced, embedded in resin, and polished to create cross-sectional samples. Optical microscopes and scanning electron microscopes (SEMs) were used to confirm that all 20 samples had the designed structure.

[0084] (Comparative Example 1) In Comparative Example 1, only the first external electrode was thickly coated to a thickness of 30 μm, and the second external electrode was not formed. Other conditions were the same as in the example.

[0085] (Comparative Example 2) In Comparative Example 2, the second external electrode was formed without forming the first external electrode. Other conditions were the same as in the example.

[0086] (analysis) For each of the Examples and Comparative Examples 1 and 2, 100 samples were mounted on substrates and subjected to mechanical stress tests to check for the presence or absence of cracks. Specifically, after reflow soldering to the glass epoxy substrate, a load was applied from the back of the substrate at a pressure rate of 0.5 mm / second with a support point spacing of 90 mm. The sample was bent to a deflection of 1 mm, held for 10 seconds, and then the load was released. This process was repeated 200 times. After that, the solder was heated to remove the sample from the substrate, and the presence or absence of cracks was checked. Specifically, ultrasonic testing (SAT) was used to check for cracks. As a precaution, the contact interface between the internal electrode layer and the external electrode was checked using a scanning electron microscope (SEM) to confirm the absence of reaction phases with the glass and alloying phases of the internal electrode. The results are shown in Table 1. [Table 1]

[0087] In Comparative Example 1, cracks were observed in 4 out of 100 samples using SAT or SEM. This is thought to be because the first external electrode had to be made thicker due to the absence of a second external electrode. In Comparative Example 2, cracks were observed in 65 out of 100 samples using SAT or SEM. This is thought to be because the glass diffused into the substrate due to the absence of a first external electrode. In contrast to these, in the Example, no cracks were observed in any of the samples. This is thought to be because a second external electrode containing glass and primarily composed of the same metal as the first external electrode was formed on the first external electrode containing the same material, eliminating the need to thicken the first external electrode and suppressing glass diffusion.

[0088] 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]

[0089] 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 21 1st external electrode 22 2nd external electrode 23 Common materials 24 Glass 51 Base material 52 Ceramic Green Sheet 53 Internal electrode pattern 100 Multilayer Ceramic Capacitors

Claims

1. A substrate having a plurality of dielectric layers, and a plurality of internal electrode layers stacked via the plurality of dielectric layers, facing each other and having one end exposed, The above-mentioned plurality of internal electrode layers are provided only on the side surface of the base body which is the end in the direction in which they are extended, and each of the above-mentioned plurality of internal electrode layers is in contact with one end of the above-mentioned plurality of internal electrode layers, and the first external electrode includes the same material, A multilayer ceramic electronic component having a second external electrode provided on the first external electrode, extending to four surfaces adjacent to the side surface of the base body, containing glass, and having the same metal as the first external electrode as its main component.

2. The multilayer ceramic electronic component according to claim 1, wherein the second external electrode is in contact with the main surface of the substrate, which is the end in the direction in which the plurality of dielectric layers and the plurality of internal electrode layers are stacked, and with the corner of the substrate.

3. The multilayer ceramic electronic component according to claim 1 or claim 2, wherein the plurality of internal electrodes are mainly composed of the same metal as the first external electrode.

4. The multilayer ceramic electronic component according to any one of claims 1 to 3, wherein the first external electrode and the second external electrode are in direct contact.

5. The multilayer ceramic electronic component according to any one of claims 1 to 4, wherein the aforementioned co-material is a metal oxide.

6. The plurality of internal electrode layers, the first external electrode, and the second external electrode are mainly composed of nickel. The multilayer ceramic electronic component according to any one of claims 3 to 5, wherein the aforementioned material comprises at least one of aluminum oxide or barium titanate.

7. The plurality of internal electrodes, the first external electrode, and the second external electrode are mainly composed of copper. The multilayer ceramic electronic component according to any one of claims 3 to 5, wherein the aforementioned material comprises at least one of aluminum oxide or calcium zirconate.

8. The multilayer ceramic electronic component according to any one of claims 1 to 7, wherein the thickness of the first external electrode is 5 μm or less in the direction in which the plurality of internal electrodes are stretched.

9. The multilayer ceramic electronic component according to any one of claims 1 to 8, wherein the aforementioned material is contained in an amount of 5 wt% or more and 20 wt% or less relative to the first external electrode.

10. The multilayer ceramic electronic component according to any one of claims 1 to 9, further comprising a plating layer on the second external electrode.

11. The first external electrode does not contain glass. The multilayer ceramic electronic component according to any one of claims 1 to 10, wherein the second external electrode does not contain the same material.

12. A substrate having a plurality of dielectric layers, and a plurality of internal electrode layers stacked via the plurality of dielectric layers, facing each other and having one end exposed, An external electrode is provided on the side surface of the substrate, which is the end in the direction in which the plurality of internal electrode layers are extended, and has a first region in contact with one end of the plurality of internal electrode layers and a second region covering the first region, wherein the first region is provided only on the side surface and has a higher content of the same material than the second region, and the second region extends to four sides adjacent to the side surface of the substrate and has a higher glass content than the first region, A multilayer ceramic electronic component in which the main component metal of the first region and the main component metal of the second region are the same.

13. The multilayer ceramic electronic component according to claim 12, wherein the second region is in contact with the main surface of the substrate, which is the end in the direction in which the plurality of dielectric layers and the plurality of internal electrode layers are stacked, and with the corner of the substrate.

14. The multilayer ceramic electronic component according to claim 12 or claim 13, wherein the plurality of internal electrode layers are mainly composed of the same metal as the external electrode.

15. The multilayer ceramic electronic component according to any one of claims 12 to 14, wherein the aforementioned co-material is a metal oxide.

16. The plurality of internal electrode layers and the external electrode are mainly composed of nickel, The multilayer ceramic electronic component according to claim 14 or claim 15, wherein the aforementioned material comprises at least one of alumina or barium titanate.

17. The plurality of internal electrode layers and the external electrode are mainly composed of copper, The multilayer ceramic electronic component according to claim 14 or claim 15, wherein the aforementioned material comprises at least one of alumina or calcium zirconate.

18. The multilayer ceramic electronic component according to any one of claims 12 to 17, further comprising a plating layer on the external electrode.

19. A step of preparing an unfired substrate having a plurality of ceramic green sheets and a plurality of internal electrode patterns laminated on the plurality of ceramic green sheets, facing each other and having one end exposed, A metal paste forming step in which a metal paste containing the same material is formed only on the side surface of the base body which is the end in the direction in which the plurality of internal electrode patterns are extended, and which is in contact with one end of each of the plurality of internal electrode patterns, A firing step in which the unfired body and the metal paste are fired, and a first external electrode is formed from the metal paste, A method for manufacturing a multilayer ceramic electronic component, comprising: a second external electrode forming step, after the firing step, forming a second external electrode that covers the first external electrode, extends to four sides adjacent to the side surface of the base body, contains glass, and has the same metal as the main component metal of the first external electrode as its main component metal.

20. The method for manufacturing a multilayer ceramic electronic component according to claim 19, further comprising a plating step of forming a plating layer on the second external electrode.

21. The first external electrode does not contain glass. The method for manufacturing a multilayer ceramic electronic component according to claim 19 or claim 20, wherein the second external electrode does not contain any co-material.

Images