Multilayer ceramic capacitor and its manufacturing method

Abstract

To provide a multilayer ceramic capacitor and a method of manufacturing the same.SOLUTION: There is provided a multilayer ceramic capacitor including: a ceramic body including dielectric layers; a plurality of internal electrodes disposed at the inside of the ceramic body; and first and second side margin portions disposed on end portions of the internal electrodes. The ceramic body includes: an active portion including the plurality of internal electrodes disposed to face each other with each of the dielectric layers interposed therebetween and forming capacitance; and cover portions disposed on upper and lower portions of the active portion. Each of the first and second side margin portions is divided into a first region and a second region. Each of the cover portions is divided into a first region and a second region, and contents of magnesium (Mg) contained in the second regions of the cover portions and the first and second side margin portions are larger than those of magnesium (Mg) contained in the first regions thereof, respectively.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a multilayer ceramic capacitor and a manufacturing method thereof, the reliability of which can be improved by adjusting the content of magnesium (Mg) contained in a side margin portion and a cover portion. [Background technology]

[0002] Typically, electronic components using ceramic materials, such as capacitors, inductors, piezoelectric elements, varistors, or thermistors, comprise a ceramic body made of a ceramic material, an internal electrode formed inside the body, and an external electrode provided on the surface of the ceramic body so as to be connected to the internal electrode.

[0003] In recent years, as electronic products become smaller and more multifunctional, chip components also tend to become smaller and more functional. This has created a demand for multilayer ceramic capacitors that are small yet have a large capacitance.

[0004] In order to miniaturize and increase the capacitance of multilayer ceramic capacitors, it is necessary to maximize the effective electrode area (increase the effective volume fraction required to achieve capacitance).

[0005] In order to realize a small-sized and high-capacity multilayer ceramic capacitor as described above, in manufacturing a multilayer ceramic capacitor, the internal electrodes are exposed in the width direction of the body, thereby maximizing the area of ​​the internal electrodes in the width direction by a margin-free design, and after the chip is manufactured and before firing, a method is applied in which a side margin portion is separately attached to the electrode exposed surface in the width direction of the chip to complete the chip.

[0006] However, in the above method, during the process of forming the side margin portion, many voids are generated at the interface where the ceramic body and the side margin portion contact each other, which may reduce reliability.

[0007] In addition, voids formed at the interface where the ceramic body and the side margins come into contact cause electric field concentration, which causes a problem of a lower breakdown voltage (BDV).

[0008] Furthermore, the voids may cause a decrease in the sintered density of the outer side, resulting in a decrease in the reliability of moisture resistance.

[0009] Therefore, research is needed to prevent the decrease in breakdown voltage (BDV) and the decrease in moisture resistance reliability in ultra-small and high-capacity products. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Korean Patent Publication No. 2010-0136917 Summary of the Invention [Problem to be solved by the invention]

[0011] An object of the present invention is to provide a multilayer ceramic capacitor and a manufacturing method thereof, which can improve reliability by adjusting the magnesium (Mg) content in a side margin portion and a cover portion. [Means for solving the problem]

[0012] One embodiment of the present invention is a multilayer ceramic capacitor including: a ceramic body including a dielectric layer, the ceramic body having a first surface and a second surface opposed to each other, a third surface and a fourth surface connecting the first surface and the second surface, and a fifth surface and a sixth surface connected to the first surface to the fourth surface and opposed to each other; a plurality of internal electrodes disposed inside the ceramic body, exposed to the first surface and the second surface, and having one end exposed to the third surface or the fourth surface; and a first side margin portion and a second side margin portion disposed on ends of the internal electrodes exposed to the first surface and the second surface, the ceramic body including the plurality of internal electrodes arranged to face each other with the dielectric layer therebetween, an active portion in which capacitance is formed; and a cover portion formed on an upper and lower portion of an active portion, the first and second side margin portions being divided into a first region adjacent to outer surfaces of the side margin portions and a second region adjacent to internal electrodes exposed to the first and second surfaces, the cover portion being divided into a first region adjacent to an outer surface of the ceramic body and a second region adjacent to an outermost internal electrode of the plurality of internal electrodes, and a magnesium (Mg) content in the second region of the cover portion and the second regions of the first and second side margin portions is higher than a magnesium (Mg) content in the first region of the cover portion and the first regions of the first and second side margin portions, respectively.

[0013] Another embodiment of the present invention provides a method for manufacturing a ceramic green sheet laminate, the method comprising the steps of: manufacturing a first ceramic green sheet on which a plurality of first internal electrode patterns are formed at predetermined intervals, and a second ceramic green sheet on which a plurality of second internal electrode patterns are formed at predetermined intervals; laminating the first ceramic green sheet and the second ceramic green sheet such that the first internal electrode pattern and the second internal electrode pattern cross each other to form a ceramic green sheet laminate body; cutting the ceramic green sheet laminate body so that ends of the first internal electrode pattern and the second internal electrode pattern have side surfaces exposed in a width direction; forming a first side margin portion and a second side margin portion on the side surfaces on which the ends of the first internal electrode pattern and the second internal electrode pattern are exposed; and firing the cut laminate body to manufacture a ceramic body including a dielectric layer and first and second internal electrodes. The ceramic body includes the first and second internal electrodes arranged to face each other with the dielectric layer therebetween, an active portion in which capacitance is formed, and a cover portion formed on an upper and lower portion of the active portion, the first and second side margin portions are divided into a first region adjacent to an outer surface of the side margin portion and a second region adjacent to the first and second internal electrodes, the cover portion is divided into a first region adjacent to an outer surface of the ceramic body and a second region adjacent to an outermost internal electrode of the first and second internal electrodes, and a magnesium (Mg) content in the second region of the cover portion and the second region of the first and second side margin portions is higher than a magnesium (Mg) content in the first region of the cover portion and the first region of the first and second side margin portions, respectively. Effect of the Invention

[0014] According to one embodiment of the present invention, the first and second side margin portions are divided into a first region adjacent to an outer surface of the side margin portion and a second region adjacent to the internal electrode, and the magnesium (Mg) content in the second region is adjusted to be higher than the magnesium (Mg) content in the first region, thereby increasing the breakdown voltage (BDV) and improving reliability.

[0015] Specifically, by adjusting the magnesium (Mg) content in the side margin region adjacent to the width direction of the ceramic body, the length of the oxide layer at the tip of the internal electrode exposed to the width direction of the ceramic body can be controlled, thereby increasing the breakdown voltage (BDV) and improving the moisture resistance reliability.

[0016] In addition, the cover portion is divided into a first region adjacent to the outer surface of the ceramic body and a second region adjacent to the outermost internal electrode among the plurality of internal electrodes, and the magnesium (Mg) content in the second region is adjusted to be greater than the magnesium (Mg) content in the first region, thereby increasing the density of the first region adjacent to the outer surface of the ceramic body and improving moisture resistance reliability. [Brief description of the drawings]

[0017] [Figure 1] 1 is a schematic perspective view showing a multilayer ceramic capacitor according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a perspective view showing the appearance of the ceramic body of FIG. [Diagram 3] 3 is a perspective view showing the ceramic green sheet laminate body of FIG. 2 before firing. FIG. [Figure 4] FIG. 3 is a side view seen from a direction B in FIG. 2. [Figure 5a] 5A to 5C are cross-sectional views illustrating a method for manufacturing a multilayer ceramic capacitor according to another embodiment of the present invention. [Figure 5b]5A to 5C are cross-sectional views illustrating a method for manufacturing a multilayer ceramic capacitor according to another embodiment of the present invention. [Figure 5c] 5A to 5C are cross-sectional views illustrating a method for manufacturing a multilayer ceramic capacitor according to another embodiment of the present invention. [Figure 5d] 10 is a perspective view illustrating a method for manufacturing a multilayer ceramic capacitor according to another embodiment of the present invention. [Figure 5e] 5A to 5C are cross-sectional views illustrating a method for manufacturing a multilayer ceramic capacitor according to another embodiment of the present invention. [Figure 5f] 5A to 5C are cross-sectional views illustrating a method for manufacturing a multilayer ceramic capacitor according to another embodiment of the present invention. [Figure 6] 1 is a graph comparing breakdown voltage (BDV) according to an embodiment of the present invention and a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. Furthermore, the embodiments of the present invention are provided to more completely explain the present invention to those having average knowledge in the art. Therefore, the shapes and sizes of elements in the drawings may be enlarged or reduced (or highlighted or simplified) for a clearer description.

[0019] FIG. 1 is a schematic perspective view showing a multilayer ceramic capacitor according to an embodiment of the present invention.

[0020] FIG. 2 is a perspective view showing the appearance of the ceramic body of FIG.

[0021] FIG. 3 is a perspective view showing the ceramic green sheet laminate body of FIG. 2 before firing.

[0022] FIG. 4 is a side view seen from the direction B in FIG.

[0023] 1 to 4, the multilayer ceramic capacitor 100 according to the present embodiment includes a ceramic body 110, a plurality of internal electrodes 121, 122 formed inside the ceramic body 110, and external electrodes 131, 132 formed on the outer surface of the ceramic body 110.

[0024] The ceramic body 110 may have a first surface 1 and a second surface 2 facing each other, a third surface 3 and a fourth surface 4 connecting the first surface and the second surface, and a fifth surface 5 and a sixth surface 6 which are an upper surface and a lower surface.

[0025] The first surface 1 and the second surface 2 can be defined as surfaces facing each other in the width direction of the ceramic body 110, the third surface 3 and the fourth surface 4 can be defined as surfaces facing each other in the length direction, and the fifth surface 5 and the sixth surface 6 can be defined as surfaces facing each other in the thickness direction.

[0026] The shape of the ceramic body 110 is not particularly limited, but may be a rectangular parallelepiped as shown in the drawing.

[0027] A plurality of internal electrodes 121, 122 formed inside the ceramic body 110 have one end exposed to the third surface 3 or the fourth surface 4 of the ceramic body.

[0028] The internal electrodes 121 and 122 may be a pair of a first internal electrode 121 and a second internal electrode 122 having different polarities.

[0029] One end of the first internal electrode 121 may be exposed to the third surface 3 , and one end of the second internal electrode 122 may be exposed to the fourth surface 4 .

[0030] The other ends of the first internal electrode 121 and the second internal electrode 122 are formed at a predetermined distance from the third surface 3 or the fourth surface 4.

[0031] First and second external electrodes 131 and 132 are formed on a third surface 3 and a fourth surface 4 of the ceramic body and may be electrically connected to the internal electrodes, respectively.

[0032] The multilayer ceramic capacitor 100 according to one embodiment of the present invention includes a plurality of internal electrodes 121, 122 disposed inside the ceramic body 110, exposed to the first and second surfaces 1, 2, and having one end exposed to the third or fourth surface 3 or 4, and a first side margin portion 112 and a second side margin portion 113 disposed on the ends of the internal electrodes 121, 122 exposed to the first and second surfaces 1 and 2.

[0033] A plurality of internal electrodes 121, 122 are formed inside the ceramic body 110. Ends of the plurality of internal electrodes 121, 122 are exposed to a first surface 1 and a second surface 2, which are surfaces in the width direction of the ceramic body 110, and a first side margin portion 112 and a second side margin portion 113 are disposed on the exposed ends.

[0034] The average thickness of the first side margin portion 112 and the second side margin portion 113 may be not less than 2 μm and not more than 10 μm.

[0035] According to an embodiment of the present invention, the ceramic body 110 may be composed of a laminate in which a plurality of dielectric layers 111 are stacked, and a first side margin portion 112 and a second side margin portion 113 disposed on both sides of the laminate.

[0036] The plurality of dielectric layers 111 are in a sintered state, and the boundaries between adjacent dielectric layers may be integrated to an extent that they are not recognizable.

[0037] The length of the ceramic body 110 corresponds to the distance from the third surface 3 to the fourth surface 4 of the ceramic body.

[0038] The length of said dielectric layer 111 defines the distance between the third face 3 and the fourth face 4 of the ceramic body.

[0039] Although not limited thereto, according to an embodiment of the present invention, the length of the ceramic body may be 400 to 1400 μm, more specifically, the length of the ceramic body may be 400 to 800 μm, or 600 to 1400 μm.

[0040] The internal electrodes 121 and 122 may be formed on the dielectric layer 111, and the internal electrodes 121 and 122 may be formed inside the ceramic body by sintering with one dielectric layer sandwiched therebetween.

[0041] 3, a first internal electrode 121 is formed on a dielectric layer 111. The first internal electrode 121 is not formed over the entire length of the dielectric layer. That is, one end of the first internal electrode 121 may be formed at a predetermined distance from the fourth surface 4 of the ceramic body, and the other end of the first internal electrode 121 may be formed up to the third surface 3 and exposed to the third surface 3.

[0042] The end of the first internal electrode exposed to the third surface 3 of the ceramic body is connected to the first external electrode 131 .

[0043] Unlike the first internal electrode, one end of the second internal electrode 122 is formed at a predetermined distance from the third surface 3, and the other end of the second internal electrode 122 is exposed to the fourth surface 4 and connected to the second external electrode 132.

[0044] In order to realize a high-capacity multilayer ceramic capacitor, the internal electrodes may be laminated in 400 layers or more, but the number of layers is not necessarily limited to this.

[0045] The dielectric layer 111 may have the same width as the first internal electrode 121. That is, the first internal electrode 121 may be formed over the entire dielectric layer 111 in the width direction.

[0046] Although not limited thereto, according to an embodiment of the present invention, the width of the dielectric layer and the width of the internal electrode may be 100 to 900 μm. More specifically, the width of the dielectric layer and the width of the internal electrode may be 100 to 500 μm, or 100 to 900 μm.

[0047] As the ceramic body becomes smaller, the thickness of the side margin portion may affect the electrical characteristics of the multilayer ceramic capacitor. According to an embodiment of the present invention, the thickness of the side margin portion is formed to be 10 μm or less, thereby improving the characteristics of the miniaturized multilayer ceramic capacitor.

[0048] That is, by forming the thickness of the side margin portion to be 10 μm or less, the overlapping area of ​​the internal electrodes that form the capacitance can be maximized, and a high-capacity, small-sized multilayer ceramic capacitor can be realized.

[0049] The ceramic body 110 may include an active part A that contributes to the formation of the capacitance of the capacitor, and upper and lower cover parts 114 and 115 that serve as upper and lower margin parts formed on the upper and lower parts of the active part A, respectively.

[0050] The active portion A can be formed by repeatedly stacking a plurality of first and second internal electrodes 121 and 122 with a dielectric layer 111 interposed therebetween.

[0051] The upper cover portion 114 and the lower cover portion 115 may have the same material and structure as the dielectric layer 111, except that they do not include internal electrodes.

[0052] That is, the upper cover part 114 and the lower cover part 115 may include a ceramic material, for example, a barium titanate (BaTiO3) based ceramic material.

[0053] The upper cover part 114 and the lower cover part 115 may each have a thickness of 20 μm or less, but are not necessarily limited thereto.

[0054] The upper cover part 114 and the lower cover part 115 may be formed by stacking a single dielectric layer or two or more dielectric layers in the vertical direction on the upper and lower surfaces of the active part A, respectively, and may basically serve to prevent damage to the internal electrodes due to physical or chemical stress.

[0055] In an embodiment of the present invention, the internal electrodes and the dielectric layers are cut and formed at the same time, and the width of the internal electrodes and the width of the dielectric layers may be the same, which will be described in more detail below.

[0056] In the present embodiment, the width of the dielectric layer is formed to be the same as the width of the internal electrodes, so that ends of the internal electrodes 121 and 122 can be exposed to the first and second surfaces of the ceramic body 110 in the width direction.

[0057] A first side margin portion 112 and a second side margin portion 113 may be formed on both widthwise sides of the ceramic body 110 where the ends of the internal electrodes 121 and 122 are exposed.

[0058] The first side margin portion 112 and the second side margin portion 113 may have a thickness of 10 μm or less. As the thicknesses of the first side margin portion 112 and the second side margin portion 113 are smaller, an overlapping area of ​​the internal electrodes formed in the ceramic body may become relatively larger.

[0059] The thickness of the first side margin portion 112 and the second side margin portion 113 is not particularly limited as long as it is a thickness that can prevent short-circuiting of the internal electrodes exposed on the side surface of the ceramic body 110, and may be, for example, 2 μm or more.

[0060] If the thickness of the first and second side margin portions is less than 2 μm, the mechanical strength against external impact may be reduced, and if the thickness of the first and second side margin portions is more than 10 μm, the overlapping area of ​​the internal electrodes may be relatively reduced, making it difficult to ensure high capacitance of the multilayer ceramic capacitor.

[0061] In order to maximize the capacitance of a multilayer ceramic capacitor, methods such as thinning the dielectric layers, highly stacking the thinned dielectric layers, and improving the coverage of the internal electrodes have been considered.

[0062] Also, a method has been devised for increasing the overlapping area of ​​the internal electrodes that form the capacitance.

[0063] In order to increase the overlapping area of ​​the internal electrodes, it is necessary to minimize the marginal area where no internal electrodes are formed.

[0064] In particular, as multilayer ceramic capacitors become smaller, it is necessary to minimize the area of ​​the marginal portion in order to increase the overlapping area of ​​the internal electrodes.

[0065] According to this embodiment, the internal electrodes are formed over the entire width of the dielectric layer, and the thickness of the side margins is set to 10 μm or less, so that the internal electrodes have a wide overlapping area.

[0066] Generally, the higher the number of dielectric layers, the thinner the dielectric layers and the internal electrodes become. Therefore, short circuits of the internal electrodes may occur frequently. In addition, if the internal electrodes are formed only on a part of the dielectric layers, steps may be generated due to the internal electrodes, which may reduce the accelerated life and reliability of the insulation resistance.

[0067] However, according to the present embodiment, even if thin internal electrodes and dielectric layers are formed, the internal electrodes are formed across the entire width of the dielectric layers, so that the overlapping area of ​​the internal electrodes is increased, thereby increasing the capacitance of the multilayer ceramic capacitor.

[0068] In addition, by reducing the steps due to the internal electrodes, the accelerated life of the insulation resistance is improved, so that a multilayer ceramic capacitor having excellent capacitance characteristics and reliability can be provided.

[0069] According to an embodiment of the present invention, the first and second side margin portions 112, 113 are divided into first regions 112a, 113a adjacent to outer surfaces of the side margin portions 112, 113 and second regions 112b, 113b adjacent to internal electrodes 121, 122 exposed to the first surface 1 and the second surface 2 of the ceramic body 110, and the magnesium (Mg) content in the second regions 112b, 113b is higher than the magnesium (Mg) content in the first regions 112a, 113a.

[0070] The first and second side margin portions 112 and 113 arranged on the sides of the ceramic body 110 are divided into two regions having different compositions. In this case, the magnesium (Mg) content in the second regions 112b and 113b is adjusted to be greater than the magnesium (Mg) content in the first regions 112a and 113a, thereby increasing the breakdown voltage (BDV) and improving reliability.

[0071] Specifically, the length of the oxide layer at the tip of the internal electrode exposed on the side surface in the width direction of the ceramic body can be controlled by adjusting the content of magnesium (Mg) contained in the second regions 112b and 113b of the side margin parts adjacent to the internal electrodes 121 and 122 exposed on the first and second faces 1 and 2 of the ceramic body 110. This can increase the breakdown voltage (BDV) and improve the moisture resistance reliability.

[0072] Generally, during the process of forming the side margin, many voids are generated at the interface where the ceramic body and the side margin contact each other, which may reduce reliability.

[0073] In addition, voids formed at the interface where the ceramic body and the side margins come into contact cause electric field concentration, which causes a problem of a lower breakdown voltage (BDV).

[0074] Furthermore, the voids may cause a decrease in the sintered density of the outer side, resulting in a decrease in the reliability of moisture resistance.

[0075] According to one embodiment of the present invention, by adjusting the magnesium (Mg) content contained in the second regions 112b, 113b inside the side margin portion adjacent to the internal electrodes 121, 122 exposed to the first surface 1 and the second surface 2 of the ceramic body 110, an oxide layer can be formed in the void generated at the interface where the ceramic body and the side margin portion contact each other.

[0076] As mentioned above, when an oxide layer is formed in the voids generated at the interface where the ceramic body and the side margins come into contact, the insulation is ensured and the concentration of the electric field can be alleviated, which increases the breakdown voltage (BDV) and reduces short circuits.

[0077] In addition, the first and second side margin portions 112, 113 arranged on the sides of the ceramic body 110 are divided into two regions having different compositions, and in this case, the magnesium (Mg) content contained in each region is made different, thereby increasing the density of the first and second side margin portions 112, 113 and improving the moisture resistance characteristics.

[0078] Specifically, by adjusting the magnesium (Mg) content in the second regions 112b, 113b of the first and second side margin portions 112, 113 to be greater than the magnesium (Mg) content in the outer first regions 112a, 113a, the density of the first regions 112a, 113a of the first and second side margin portions 112, 113 can be improved, thereby improving the moisture resistance characteristics.

[0079] In particular, by reducing the magnesium (Mg) content in the first regions 112a, 113a of the first and second side margin portions 112, 113 adjacent to the outer surfaces of the side margin portions 112, 113, the adhesion between the first external electrode 131 and the second external electrode 132 can be improved.

[0080] The magnesium (Mg) content in the second regions 112b, 113b of the first and second side margin portions 112, 113 can be adjusted to be greater than the magnesium (Mg) content in the first regions 112a, 113a by making the composition of the dielectric material for forming the ceramic body and the composition of the dielectric material for forming the first and second side margin portions different from each other during the manufacturing process of the multilayer ceramic capacitor.

[0081] That is, when the magnesium (Mg) content in the composition of the dielectric for forming the first and second side margin portions is increased, different from the composition of the dielectric for forming the ceramic body, and the magnesium (Mg) content is adjusted by diffusion during the sintering and firing processes, the magnesium (Mg) content in the second regions 112b, 113b can be adjusted to be higher than the magnesium (Mg) content in the first regions 112a, 113a.

[0082] This can reduce the electric field concentrated at the tips of the internal electrodes, thereby preventing dielectric breakdown, which is one of the main defects of multilayer ceramic capacitors, and improving the reliability of the multilayer ceramic capacitor.

[0083] According to an embodiment of the present invention, the magnesium (Mg) content of the second regions 112b, 113b of the first and second side margin portions 112, 113 may be greater than or equal to 10 mol and less than or equal to 30 mol with respect to the titanium (Ti) contained in the first and second side margin portions.

[0084] The magnesium (Mg) content of the second regions 112b, 113b of the first and second side margin portions 112, 113 is adjusted to be 10 moles or more and 30 moles or less with respect to the titanium (Ti) contained in the first and second side margin portions, thereby increasing the breakdown voltage (BDV) and improving the moisture resistance reliability.

[0085] If the magnesium (Mg) content of the second regions 112b, 113b of the first and second side margin portions 112, 113 is less than 10 moles relative to the titanium (Ti) contained in the first and second side margin portions, an oxide layer may not be sufficiently formed in a void generated at the interface where the ceramic body and the side margin portions contact each other, resulting in a lower breakdown voltage (BDV) and an increase in short circuit defects.

[0086] Meanwhile, if the magnesium (Mg) content of the second regions 112b, 113b of the first and second side margin portions 112, 113 exceeds 30 moles relative to the titanium (Ti) contained in the first and second side margin portions, problems such as non-uniform distribution of reliability and breakdown voltage (BDV) due to reduced sinterability may occur.

[0087] Referring to FIG. 4, the upper and lower cover parts 114, 115 are divided into a first region 114a, 115a adjacent to an outer surface of the ceramic body 110 and a second region 114b, 115b adjacent to the outermost internal electrode of the plurality of internal electrodes 121, 122, and are characterized in that the magnesium (Mg) content in the second regions 114b, 115b is higher than the magnesium (Mg) content in the first regions 114a, 115a.

[0088] The upper and lower cover parts 114, 115 of the ceramic body 110 are divided into two regions having different compositions, and in this case, the magnesium (Mg) content in each region is made different, thereby increasing the density of the upper and lower cover parts 114, 115 and improving the moisture resistance.

[0089] The magnesium (Mg) content in the second regions 114b and 115b of the upper and lower cover parts 114 and 115 may be greater than the magnesium (Mg) content in the first regions 114a and 115a.

[0090] By adjusting the magnesium (Mg) content in the second regions 114b, 115b of the upper and lower cover parts 114, 115 to be greater than the magnesium (Mg) content in the outer first regions 114a, 115a, the density of the first regions 114a, 115a of the upper and lower cover parts 114, 115 can be increased, thereby improving the moisture resistance characteristics.

[0091] In particular, by reducing the magnesium (Mg) content in the first regions 114a, 115a of the upper and lower cover parts 114, 115 adjacent to the outer surfaces of the ceramic body 110, the adhesion between the first external electrode 131 and the second external electrode 132 can be improved.

[0092] In addition, the content of magnesium (Mg) in the second regions 114b and 115b of the upper and lower cover parts 114 and 115 may be 10 moles or more and 30 moles or less based on the titanium (Ti) contained in the upper and lower cover parts 114 and 115.

[0093] The magnesium (Mg) content of the second regions 114b, 115b of the upper and lower cover parts 114, 115 is adjusted to be 10 moles or more and 30 moles or less relative to the titanium (Ti) contained in the upper and lower cover parts 114, 115, thereby improving the moisture resistance reliability.

[0094] If the magnesium (Mg) content of the second regions 114b, 115b of the upper and lower cover parts 114, 115 is less than 10 moles relative to the titanium (Ti) contained in the upper and lower cover parts 114, 115, the dielectric grains in the second regions 114b, 115b of the upper and lower cover parts 114, 115 grow excessively, so that the DC-bias characteristics are not ensured and it is difficult to ensure the required capacitance.

[0095] On the other hand, if the magnesium (Mg) content of the second regions 114b, 115b of the upper and lower cover parts 114, 115 exceeds 30 moles relative to the titanium (Ti) contained in the upper and lower cover parts 114, 115, a problem may occur in that the distribution of moisture resistance reliability is uneven due to a decrease in sinterability.

[0096] The second regions 114 b and 115 b of the upper and lower cover parts 114 and 115 may further include an additive for enhancing adhesion to the ceramic body 110 .

[0097] The magnesium (Mg) content in the second regions 114b, 115b of the upper and lower cover parts 114, 115 can be adjusted to be greater than the magnesium (Mg) content in the first regions 114a, 115a by making the composition of the dielectric material for forming the ceramic body and the composition of the dielectric material for forming the cover parts different from each other during the manufacturing process of the multilayer ceramic capacitor.

[0098] That is, when the magnesium (Mg) content in the composition of the dielectric for forming the cover part is increased differently from the composition of the dielectric for forming the ceramic body, and the magnesium (Mg) content is adjusted by diffusion during the sintering and firing process, the magnesium (Mg) content in the second regions 114b, 115b of the upper and lower cover parts 114, 115 can be adjusted to be higher than the magnesium (Mg) content in the first regions 114a, 115a.

[0099] According to an embodiment of the present invention, the dielectric layer 111 has a thickness of 0.4 μm or less, and the internal electrodes 121 and 122 have a thickness of 0.4 μm or less, thereby providing an ultra-small multilayer ceramic capacitor.

[0100] When a thin dielectric layer and an internal electrode are applied, such as in one embodiment of the present invention, in which the dielectric layer 111 is 0.4 μm or less in thickness and the internal electrodes 121, 122 are 0.4 μm or less in thickness, the reliability problem caused by voids occurring on the outer surfaces of the ceramic body and the side margin portion is a very important issue.

[0101] That is, in the case of the conventional multilayer ceramic capacitor, even if the magnesium (Mg) content of each region of the side margin part included in the multilayer ceramic capacitor is not adjusted as in the embodiment of the present invention, there is no significant problem in reliability.

[0102] However, in products in which thin dielectric layers and internal electrodes are applied, such as in one embodiment of the present invention, the magnesium (Mg) content in each region of the side margin must be adjusted to prevent voids generated at the interface where the ceramic body and the side margin contact, resulting in reduced BDV and reliability.

[0103] That is, in one embodiment of the present invention, the magnesium (Mg) content of the second regions 112b, 113b is adjusted to be 10 moles or more and 30 moles or less relative to the titanium (Ti) contained in the first and second side margin portions, so that even when the dielectric layer 111 and the first and second internal electrodes 121, 122 are thin films having a thickness of 0.4 μm or less, the breakdown voltage (BDV) can be increased and moisture resistance reliability can be improved.

[0104] However, the above thin film does not mean that the thickness of the dielectric layer 111 and the first and second internal electrodes 121, 122 is 0.4 μm or less, but can be understood as the concept of including a dielectric layer and internal electrodes that are thinner than conventional products.

[0105] Meanwhile, the width of the first regions 112a, 113a of the first and second side margin portions 112, 113 may be 12 μm or less, and the width of the second regions 112b, 113b may be 3 μm or less, but is not necessarily limited thereto.

[0106] Referring to FIG. 4, the ratio of the thickness tc1 of the first or second side margin region contacting the end of the centrally located internal electrode among the multiple internal electrodes 121, 122 to the thickness tc2 of the first or second side margin region contacting the end of the outermost internal electrode may be 1.0 or less.

[0107] There is no particular lower limit to the ratio of the thickness tc2 of the first or second side margin region in contact with the end of the internal electrode located at the outermost position to the thickness tc1 of the first or second side margin region in contact with the end of the internal electrode located in the central portion, but it is preferable that the ratio be 0.9 or more.

[0108] According to one embodiment of the present invention, unlike the conventional technology, the first or second side margin portion is formed by attaching a ceramic green sheet to a side of a ceramic body, so that the thickness of each position of the first or second side margin portion is uniform.

[0109] That is, conventionally, the side margins have been formed by coating or printing a ceramic slurry, and therefore the thickness of the side margins varies greatly from position to position.

[0110] Specifically, in the past, the thickness of the first or second side margin region that contacts the end of the internal electrode arranged in the center of the ceramic body was made thicker than the thickness of other regions.

[0111] For example, in the past, the ratio of the thickness of the first or second side margin region that contacts the end of the internal electrode located at the outermost position to the thickness of the first or second side margin region that contacts the end of the internal electrode located in the central portion was less than 0.9, and there was a large variation.

[0112] In the conventional case where there was large variation in thickness from position to position in the side margin portion, the side margin portion occupied a large portion of a multilayer ceramic capacitor of the same size, making it impossible to ensure a large size for the capacitance forming portion, and therefore difficult to ensure high capacitance.

[0113] In contrast, in one embodiment of the present invention, the average thickness of the first and second side margin portions 112, 113 is 2 μm or more and 10 μm or less, and the ratio of the thickness tc2 of the first or second side margin portion region contacting the end of the internal electrode located at the outermost position to the thickness tc1 of the first or second side margin portion region contacting the end of the internal electrode located in the center of the multiple internal electrodes 121, 122 is 0.9 or more and 1.0 or less, so that the thickness of the side margin portion is thin and there is little variation in thickness, and therefore a large size can be ensured for the capacitance forming portion.

[0114] This makes it possible to realize a high-capacity multilayer ceramic capacitor.

[0115] Meanwhile, referring to FIG. 4, the ratio of a thickness tc1 of the first or second side margin region contacting an end of the internal electrode located in the center among the plurality of internal electrodes 121, 122 to a thickness tc3 of the first or second side margin region contacting a corner of the ceramic body 110 may be 1.0 or less.

[0116] It is preferable that the lower limit of the ratio of the thickness tc3 of the first or second side margin region in contact with the corner of the ceramic body 110 to the thickness tc1 of the first or second side margin region in contact with the end of the internal electrode arranged in the central portion is 0.9 or more.

[0117] Due to the above-mentioned features, there is little variation in thickness between the regions of the side margin portion, so that the size of the capacitance forming portion can be ensured to be large, thereby making it possible to realize a multilayer ceramic capacitor with high capacitance.

[0118] 5a to 5f are cross-sectional and perspective views illustrating a method for manufacturing a multilayer ceramic capacitor according to another embodiment of the present invention.

[0119] According to another embodiment of the present invention, a method for manufacturing a ceramic green sheet laminate including the steps of: manufacturing a first ceramic green sheet on which a plurality of first internal electrode patterns are formed at predetermined intervals, and a second ceramic green sheet on which a plurality of second internal electrode patterns are formed at predetermined intervals; laminating the first ceramic green sheet and the second ceramic green sheet such that the first internal electrode pattern and the second internal electrode pattern cross each other to form a ceramic green sheet laminate body; cutting the ceramic green sheet laminate body so that ends of the first internal electrode pattern and the second internal electrode pattern have side surfaces exposed in a width direction; forming a first side margin portion and a second side margin portion on the side surfaces on which the ends of the first internal electrode pattern and the second internal electrode pattern are exposed; and firing the cut laminate body to manufacture a ceramic body including a dielectric layer and first and second internal electrodes. the ceramic body includes the first internal electrode and the second internal electrode arranged to face each other with the dielectric layer interposed therebetween, an active portion in which capacitance is formed, and a cover portion formed on an upper portion and a lower portion of the active portion, the first and second side margin portions are divided into a first region adjacent to an outer surface of the side margin portion and a second region adjacent to the first and second internal electrodes, the cover portion is divided into a first region adjacent to an outer surface of the ceramic body and a second region adjacent to an outermost one of the first and second internal electrodes, and a magnesium (Mg) content included in the second region of the cover portion and the second region of the first and second side margin portions is higher than a magnesium (Mg) content included in the first region of the cover portion and the first region of the first and second side margin portions, respectively.

[0120] Hereinafter, a method for manufacturing a multilayer ceramic capacitor according to another embodiment of the present invention will be described.

[0121] 5a, a plurality of stripe-shaped first internal electrode patterns 221 are formed at predetermined intervals on a ceramic green sheet 211. The plurality of stripe-shaped first internal electrode patterns 221 may be formed parallel to each other.

[0122] The ceramic green sheet 211 may be formed of a ceramic paste including ceramic powder, an organic solvent, and an organic binder.

[0123] The ceramic powder is a material having a high dielectric constant, and may be, but is not limited to, a barium titanate (BaTiO3)-based material, a lead complex perovskite-based material, or a strontium titanate (SrTiO3)-based material, and is preferably barium titanate (BaTiO3) powder. When the ceramic green sheet 211 is fired, it becomes the dielectric layer 111 constituting the ceramic body 110.

[0124] The stripe-shaped first internal electrode pattern 221 may be formed by an internal electrode paste containing a conductive metal, which may be, but is not limited to, nickel (Ni), copper (Cu), palladium (Pd), or an alloy thereof.

[0125] The method for forming the stripe-shaped first internal electrode pattern 221 on the ceramic green sheet 211 is not particularly limited, and may be, for example, a printing method such as a screen printing method or a gravure printing method.

[0126] Although not shown, a plurality of stripe-shaped second internal electrode patterns 222 may be formed on another ceramic green sheet 211 at predetermined intervals.

[0127] Hereinafter, the ceramic green sheet on which the first internal electrode pattern 221 is formed will be referred to as a first ceramic green sheet, and the ceramic green sheet on which the second internal electrode pattern 222 is formed will be referred to as a second ceramic green sheet.

[0128] Next, as shown in FIG. 5b, the first and second ceramic green sheets may be alternately laminated such that the stripe-shaped first internal electrode pattern 221 and the stripe-shaped second internal electrode pattern 222 are cross-laminated.

[0129] Thereafter, the first internal electrode 121 can be formed by the stripe-shaped first internal electrode pattern 221, and the second internal electrode 122 can be formed by the stripe-shaped second internal electrode pattern 222.

[0130] According to another embodiment of the present invention, the first and second ceramic green sheets have a thickness td of 0.6 μm or less, and the first and second internal electrode patterns have a thickness te of 0.5 μm or less.

[0131] The present invention is characterized in that the present invention is an ultra-small and high-capacity multilayer ceramic capacitor having a dielectric layer thickness of 0.4 μm or less and an internal electrode thickness of 0.4 μm or less. Accordingly, the first and second ceramic green sheets have a thickness td of 0.6 μm or less, and the first and second internal electrode patterns have a thickness te of 0.5 μm or less.

[0132] FIG. 5c is a cross-sectional view showing a ceramic green sheet laminate body 220 in which first and second ceramic green sheets are laminated according to one embodiment of the present invention, and FIG. 5d is a perspective view showing a ceramic green sheet laminate body 220 in which first and second ceramic green sheets are laminated.

[0133] Referring to Figures 5c and 5d, a first ceramic green sheet having a plurality of parallel stripe-shaped first internal electrode patterns 221 printed thereon and a second ceramic green sheet having a plurality of parallel stripe-shaped second internal electrode patterns 222 printed thereon are alternately stacked with each other.

[0134] More specifically, the first ceramic green sheet may be laminated such that the center of the stripe-shaped first internal electrode pattern 221 printed on the first ceramic green sheet overlaps with the space between the stripe-shaped second internal electrode patterns 222 printed on the second ceramic green sheet.

[0135] 5d, the ceramic green sheet laminated body 220 may be cut across the plurality of stripe-shaped first internal electrode patterns 221 and the stripe-shaped second internal electrode patterns 222. That is, the ceramic green sheet laminated body 220 may become a laminated body 210 cut along cutting lines C1-C1 and C2-C2 that are perpendicular to each other.

[0136] More specifically, the stripe-shaped first internal electrode pattern 221 and the stripe-shaped second internal electrode pattern 222 can be cut in the length direction to divide them into a plurality of internal electrodes having a certain width. At this time, the laminated ceramic green sheets are also cut together with the internal electrode patterns. As a result, the dielectric layer can be formed to have the same width as the width of the internal electrodes.

[0137] Also, it is possible to cut along the cutting line C2-C2 to match the size of each individual ceramic body. That is, before forming the first side margin portion and the second side margin portion, the rod-shaped laminate is cut along the cutting line C2-C2 to match the size of each individual ceramic body, thereby forming a plurality of laminate bodies 210.

[0138] That is, the rod-shaped laminate can be cut so that the predetermined intervals formed between the centers of the overlapping first internal electrodes and the second internal electrodes are cut along the same cutting line, whereby one end of the first internal electrodes and one end of the second internal electrodes can be alternately exposed on the cut surface.

[0139] Then, a first side margin portion and a second side margin portion may be formed on the first and second side surfaces of the laminated body 210 .

[0140] Next, as shown in FIG. 5e, a first side margin portion 212 and a second side margin portion (not shown) can be formed on the first and second side surfaces of the laminated body 210, respectively.

[0141] Specifically, the first side margin portion 212 is formed by placing the side ceramic green sheet 212 on top of a punched elastic material 300 made of rubber.

[0142] Next, the multilayer body 210 is rotated 90 degrees so that a first side surface of the multilayer body 210 faces the side surface ceramic green sheet 212, and then the multilayer body 210 is pressed and adhered to the side surface ceramic green sheet 212.

[0143] When the laminated body 210 is pressed against the side ceramic green sheet 212 to transfer the side ceramic green sheet 212 to the laminated body 210, the side ceramic green sheet 212 is formed up to the corners of the side of the laminated body 210 by the rubber punching elastic material 300, and the remaining portion can be cut off.

[0144] FIG. 5F shows that the side surface ceramic green sheets 212 are formed up to the corners of the side surfaces of the laminated body 210.

[0145] Thereafter, the laminated body 210 can be rotated to form a second side margin portion on a second side surface of the laminated body 210 .

[0146] Next, the laminated body 210 having the first and second side margins formed on both sides thereof may be calcined and fired to form a ceramic body including the dielectric layer and the first and second internal electrodes.

[0147] Then, external electrodes may be formed on a third side surface of the ceramic body where the first internal electrode is exposed and a fourth side surface of the ceramic body where the second internal electrode is exposed.

[0148] According to another embodiment of the present invention, the side ceramic green sheets are thin and have little variation in thickness, so that a large size of the capacitance forming portion can be ensured.

[0149] Specifically, the average thickness of the first and second side margin portions 112, 113 after firing is between 2 μm and 10 μm, and there is little variation in thickness from position to position, so that a large size of the capacitance forming portion can be ensured.

[0150] This makes it possible to realize a high-capacity multilayer ceramic capacitor.

[0151] In addition, descriptions of features that are the same as those in the embodiment of the present invention described above will be omitted here to avoid duplication.

[0152] The present invention will be described in more detail below by way of experimental examples. However, these are merely for the purpose of concretely understanding the invention, and the scope of the present invention is not limited to these experimental examples.

[0153] (Experimental Example) According to an embodiment of the present invention, a comparative example in which a conventional side margin portion is formed and an example in which a side margin portion including first and second regions having different magnesium (Mg) contents is formed were prepared.

[0154] Then, a ceramic green sheet laminate body was formed so that the internal electrodes were exposed in the width direction and side ceramic green sheets could be attached to the electrode exposed portions of the green chips that had no margins, as in the above comparative example and example, to form side margin portions.

[0155] A ceramic green sheet for forming the side faces was attached to both sides of the ceramic green sheet laminate body while applying a constant temperature and pressure under conditions that minimized deformation of the chip, to produce a multilayer ceramic capacitor green chip of 0603 size (width x length x height: 0.6 mm x 0.3 mm x 0.3 mm).

[0156] The multilayer ceramic capacitor test pieces thus manufactured were calcined in a nitrogen atmosphere at 400°C or less, and then sintered at a firing temperature of 1200°C or less and with a hydrogen concentration of 0.5% H2 or less. Then, electrical characteristics such as appearance defects, insulation resistance, and moisture resistance were comprehensively checked.

[0157] FIG. 6 is a graph comparing the breakdown voltage (BDV) of the embodiment of the present invention and the comparative example.

[0158] In FIG. 6, Comparative Example 1 is a conventional multilayer ceramic capacitor structure in which there is no difference in the magnesium (Mg) content contained in the side margin portion, Examples 1 and 2 are cases in which the magnesium (Mg) content contained in the second regions 112b, 113b of the first and second side margin portions 112, 113 adjacent to the first and second internal electrodes 121, 122 is 10 mol and 30 mol, respectively, and Comparative Example 2 is a case in which the magnesium (Mg) content contained in the second regions 112b, 113b of the first and second side margin portions 112, 113 adjacent to the first and second internal electrodes 121, 122 is 50 mol.

[0159] It can be seen that in the cases of Examples 1 and 2, the breakdown voltage (BDV) is increased compared to Comparative Example 1, which is a conventional multilayer ceramic capacitor.

[0160] In the case of Comparative Example 2, although the breakdown voltage (BDV) increases, the distribution is non-uniform, and the distribution of the moisture resistance reliability is also non-uniform. Therefore, in the present invention, it is preferable that the magnesium (Mg) content contained in the second regions 112b, 113b of the first and second side margin portions 112, 113 is 30 moles or less.

[0161] Although the embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that the scope of the present invention is not limited thereto, and that various modifications and variations are possible within the scope of the technical idea of ​​the present invention described in the claims. [Explanation of symbols]

[0162] 110 Ceramic body 111 Dielectric layer 112, 113 First and second side margin portions 121, 122 First and second internal electrodes 131, 132 First and second external electrodes

Claims

1. a ceramic body including a dielectric layer, the ceramic body having first and second surfaces facing each other, third and fourth surfaces connecting the first and second surfaces, and fifth and sixth surfaces connected to the first to fourth surfaces and facing each other; a plurality of internal electrodes disposed inside the ceramic body, exposed to the first and second surfaces, and having one end exposed to the third or fourth surface; a first side margin portion and a second side margin portion disposed on ends of the internal electrodes exposed on the first surface and the second surface, the ceramic body includes the plurality of internal electrodes arranged to face each other with the dielectric layer interposed therebetween, an active portion in which capacitance is formed, and cover portions formed above and below the active portion, The first and second side margin portions are divided into a first region adjacent to an outer surface of the side margin portion and a second region adjacent to the internal electrodes exposed on the first surface and the second surface, the cover portion is divided into a first region adjacent to an outer surface of the ceramic body and a second region adjacent to an outermost internal electrode among the plurality of internal electrodes, The magnesium (Mg) content in the second regions of the cover portion and the first and second side margin portions is higher than the magnesium (Mg) content in the first regions, respectively; a content of magnesium (Mg) in the second region is 10 moles or more and 30 moles or less relative to titanium (Ti) in barium titanate or strontium titanate contained in the cover portion and the first and second side margin portions.

2. 2. The multilayer ceramic capacitor according to claim 1, wherein a ratio of a thickness of the first or second side margin region contacting an end of an internal electrode arranged at an outermost position to a thickness of the first or second side margin region contacting an end of an internal electrode arranged at a center among the plurality of internal electrodes is 0.9 or more and 1.0 or less.

3. 3. The multilayer ceramic capacitor according to claim 1, wherein a ratio of a thickness of the first or second side margin region contacting an end of an internal electrode arranged in a central portion among the plurality of internal electrodes to a thickness of the first or second side margin region contacting a corner of the ceramic body is 0.9 or more and 1.0 or less.

4. 4. The multilayer ceramic capacitor according to claim 1, wherein the dielectric layer has a thickness of 0.4 μm or less.

5. 5. The multilayer ceramic capacitor according to claim 1, wherein the internal electrodes have a thickness of 0.4 [mu]m or less.

6. 4. The multilayer ceramic capacitor according to claim 1, wherein the dielectric layers have a thickness of 0.4 μm or less, and the internal electrodes have a thickness of 0.4 μm or less.

7. The multilayer ceramic capacitor according to claim 1 , wherein the first side margin portion and the second side margin portion have an average thickness of 2 μm or more and 10 μm or less.

8. manufacturing a first ceramic green sheet having a plurality of first internal electrode patterns formed at predetermined intervals and a second ceramic green sheet having a plurality of second internal electrode patterns formed at predetermined intervals; forming a ceramic green sheet laminate body by stacking the first ceramic green sheet and the second ceramic green sheet such that the first internal electrode pattern and the second internal electrode pattern cross each other; cutting the ceramic green sheet laminate body so that ends of the first internal electrode pattern and the second internal electrode pattern have exposed side surfaces in a width direction; forming a first side margin portion and a second side margin portion on the side surfaces where the ends of the first internal electrode pattern and the second internal electrode pattern are exposed; and firing the multilayer body having the first and second side margin portions formed thereon to manufacture a ceramic body including dielectric layers and first and second internal electrodes, the ceramic body includes the first internal electrode and the second internal electrode arranged to face each other with the dielectric layer interposed therebetween, an active portion in which capacitance is formed, and cover portions formed above and below the active portion, The first and second side margin portions are divided into a first region adjacent to an outer surface of the side margin portion and a second region adjacent to the first and second internal electrodes, the cover part is divided into a first region adjacent to an outer surface of the ceramic body and a second region adjacent to an outermost internal electrode of the first and second internal electrodes, The magnesium (Mg) content in the second regions of the cover portion and the first and second side margin portions is higher than the magnesium (Mg) content in the first regions, respectively; a content of magnesium (Mg) in the second region is 10 mol to 30 mol relative to titanium (Ti) in barium titanate or strontium titanate contained in the cover portion and the first and second side margin portions.

9. 9. The method for manufacturing a multilayer ceramic capacitor according to claim 8, wherein the first and second ceramic green sheets have a thickness of 0.6 [mu]m or less, and the first and second internal electrode patterns have a thickness of 0.5 [mu]m or less.

10. 10. The method for manufacturing a multilayer ceramic capacitor according to claim 8, wherein a ratio of a thickness of the first or second side margin region contacting an end of an internal electrode arranged at the outermost position to a thickness of the first or second side margin region contacting an end of an internal electrode arranged at a center of the first and second internal electrodes is 0.9 or more and 1.0 or less.

11. 11. The method for manufacturing a multilayer ceramic capacitor according to claim 8, wherein the ratio of the thickness of the first or second side margin region contacting an end of the internal electrode arranged in the center of the first and second internal electrodes to the thickness of the first or second side margin region contacting a corner of the ceramic green sheet laminate body is 0.9 or more and 1.0 or less.

12. 12. The method for manufacturing a multilayer ceramic capacitor according to claim 8, wherein the first side margin portion and the second side margin portion have an average thickness of 2 μm or more and 10 μm or less.

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