Patent Publication Number: US-11640874-B2

Title: Multi-layered ceramic capacitor

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a continuation application of U.S. patent application Ser. No. 16/690,410 filed on Nov. 21, 2019, which claims the benefit of priority to Korean Patent Application No. 10-2019-0096691 filed on Aug. 8, 2019 in the Korean Intellectual Property Office, the disclosures of which are incorporated herein by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a multilayer ceramic capacitor. 
     BACKGROUND 
     Among capacitor components, a multilayer ceramic capacitor (MLCC) has advantages of small size, high capacity, and ease of mounting. 
     In recent years, a ceramic electronic component, especially, a multilayer ceramic capacitor, has been implemented with ultra-high capacity according to market demand. In order to secure such capacity, the number of stacked layers must be increased, but as the number of stacked layers increases, reliability of the chip may decrease. 
     This problem is due to a step by a thickness of the internal electrode increases as the number of stacked layers increases. As the number of stacked layers increases, a dielectric layer may be elongated to fill the step, which may cause delamination between an active layer and a cover layer and a crack in a calcination process. 
     Therefore, there is a demand for development of a multilayer ceramic capacitor that is ultra small with ultra high-capacity and which satisfies mechanical reliability and moisture resistance reliability of the chip. 
     SUMMARY 
     An aspect of the present disclosure is to provide a multilayer ceramic capacitor having improved mechanical strength. 
     Another aspect of the present disclosure is to provide a multilayer ceramic capacitor having excellent moisture resistance reliability. 
     Another aspect of the present disclosure is to provide a multilayer ceramic capacitor capable of securing high capacity while preventing cracks or delamination. 
     According to an embodiment of the present disclosure, a multilayer ceramic capacitor may be provided. The multilayer ceramic capacitor includes a body including a first dielectric layer on which a first internal electrode, a first coupling portion, and a second internal electrode are disposed, a second dielectric layer on which a third internal electrode, a second coupling portion, and a fourth internal electrode are disposed, and a third dielectric layer on which a fifth internal electrode or a sixth internal electrode is disposed, and including fifth and sixth surfaces opposed in a first direction, third and fourth surfaces opposed in a second direction, and first and second surfaces opposed in a third direction; and first and second external electrodes connected to the first to sixth internal electrodes, and disposed on both surfaces of the body in the first direction. The first to third dielectric layers are sequentially stacked. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The above and other aspects, features, and advantages of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG.  1    is a schematic perspective view illustrating a multilayer ceramic capacitor according to an embodiment of the present disclosure; 
         FIG.  2    is a perspective view illustrating the body of  FIG.  1   ; 
         FIG.  3    is a perspective view of the body of  FIG.  2    viewed from another direction; 
         FIGS.  4  to  7    are plan views schematically illustrating internal electrodes according to an embodiment of the present disclosure; 
         FIG.  8    is a perspective view illustrating a stacking procedure of internal electrodes of  FIGS.  4  to  7   ; 
         FIG.  9    is a perspective view illustrating a body according to another embodiment of the present disclosure; 
         FIG.  10    is a perspective view of the body of  FIG.  9    viewed from another direction; 
         FIGS.  11  and  12    are plan views schematically illustrating internal electrodes according to another embodiment of the present disclosure; and 
         FIG.  13    is a perspective view illustrating a stacking procedure of internal electrodes to which  FIGS.  11  and  12    are applied. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, embodiments of the present disclosure will be described as follows with reference to the attached drawings. The present disclosure may, however, be exemplified in many different forms and should not be construed as being limited to the specific embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be through and complete, and will fully convey the scope of the disclosure to those skilled in the art. Accordingly, shapes and sizes of elements in the drawings may be exaggerated for clarity of description, and elements indicated by the same reference numeral are same elements in the drawings. 
     In the drawings, irrelevant descriptions will be omitted to clearly describe the present disclosure, and to clearly express a plurality of layers and areas, thicknesses may be magnified. The same elements having the same function within the scope of the same concept will be described with use of the same reference numerals. Throughout the specification, when a component is referred to as “comprise” or “comprising,” it means that it may include other components as well, rather than excluding other components, unless specifically stated otherwise. 
     In the drawings, an X direction may be defined as a first direction and an L direction or a length direction, a Y direction may be defined as a second direction, a W direction or a width direction, and a Z direction may be defined as a third direction, a T direction and a thickness direction. 
     Hereinafter, a multilayer ceramic capacitor according to an embodiment of the present disclosure will be described in detail with reference to  FIGS.  1  to  8   . 
     A multilayer ceramic capacitor  100  according to an embodiment of the present disclosure may include a body  110  including a first dielectric layer on which a first internal electrode  121 , a first coupling portion  141 , and a second internal electrode  122  are disposed, a second dielectric layer on which a third internal electrode  123 , a second coupling portion  142 , and a fourth internal electrode  124  are disposed, and a third dielectric layer on which a fifth internal electrode  125  or a sixth internal electrode  126  is disposed, and having fifth and sixth surfaces S 5  and S 6  opposing each other in a first direction and first and second surfaces S 1  and S 2  opposing in a third direction; and first and second external electrodes  131  and  132  disposed on both surfaces of the body  110  in the first direction. In this case, the first to third dielectric layers may be sequentially stacked and disposed in the Z (i.e., the third) direction. 
     The specific shape of the body  110  is not particularly limited, but as illustrated, the body  110  may be formed to have a hexahedral or similar shape. Due to shrinkage of the ceramic powder contained in the body  110  during a firing process, the body  110  may have a substantially hexahedral shape, although it may not be a hexahedral shape with completely straight lines. 
     The body  110  may have first and second surfaces S 1  and S 2  opposing each other in a thickness direction (Z direction), third and fourth surfaces S 3  and S 4  connected to the first and second surfaces S 1  and S 2  and opposing each other in a width direction (Y direction), and fifth and sixth surfaces S 5  and S 6  connected to the first and second surfaces S 1  and S 2  and connected to the third and fourth surfaces S 3  and S 4  and opposing each other in a length direction (X direction). In this case, one surface selected from the first, second, fifth, and sixth surfaces S 1 , S 2 , S 5 , and S 6  may be a mounting surface. 
     The plurality of dielectric layers  111  forming the body  110  are in a sintered state, and a boundary between adjacent dielectric layers  111  may be integrated, such that it may be difficult to confirm without using a scanning electron microscope (SEM). 
     According to an embodiment of the present disclosure, a raw material for forming the dielectric layer  111  is not particularly limited as long as sufficient electrostatic capacitance may be obtained therewith. For example, the raw material for forming the dielectric layer  511  may be a barium titanate (BaTiO 3 ) material, a lead composite perovskite material, a strontium titanate (SrTiO 3 ) material, or the like. The barium titanate-based material may include BaTiO 3 -based ceramic powder, and examples of the ceramic powder may be (Ba 1-x Ca x )TiO 3 , Ba(Ti 1-y Ca y )O 3 , (Ba 1-x Ca x ) (Ti 1-y Zr y )O 3  or Ba(Ti 1-y Zr y )O 3  in which calcium (Ca), zirconium (Zr), or the like, are partially dissolved in BaTiO 3 . A material for forming the dielectric layer  111 , various ceramic additives, organic solvents, plasticizers, binders, dispersants, and the like, may be added to powders such as barium titanate (BaTiO 3 ) according to the purpose of the present disclosure. 
     A cover portion having a predetermined thickness may be formed in a lower portion of a lowermost internal electrode and an upper portion of an uppermost internal electrode of the body  110 . In this case, the cover portion may include the same component as that of the dielectric layer  111 , and may be formed by stacking at least one dielectric layer constituting the cover portion in the upper portion of the uppermost internal electrode and the lower portion of the lowermost internal electrode of the body  110 . 
     Meanwhile, the cover portion may be different from each other in the content of the dielectric layer and magnesium (Mg) in which the internal electrode is disposed. Accordingly, contactability with the internal electrode may be improved, and moisture resistance reliability may be improved by increasing density of the cover portion according to the content of magnesium (Mg). 
     The first dielectric layer may include a first internal electrode  121 , a first coupling portion  141 , and a second internal electrode  122 . Referring to  FIG.  4   , the first coupling portion  141  may be disposed between the first internal electrode  121  and the second internal electrode  122 . In this case, the first coupling portion  141  may mean a partial region of the first dielectric layer. The first coupling portion  141  may mean a region between the first internal electrode  121  and the second internal electrode  122  disposed on the first dielectric layer, and more specifically, the first coupling portion  141  may be located between the first internal electrode  121  and the second internal electrode  122  in the Y direction, and may mean an unallocated region of the first internal electrode  121  and the second internal electrode  122 , for example may be a region of W 1  of  FIG.  4   . 
     The second dielectric layer may include a third internal electrode  123 , a second coupling portion  142 , and a fourth internal electrode  124 . Referring to  FIG.  5   , a second coupling portion  142  may be disposed between the third internal electrode  123  and the fourth internal electrode  124 . In this case, the second coupling portion  142  may mean a partial region of the second dielectric layer. The second coupling portion  142  may mean a region between the third internal electrode  123  and the fourth internal electrode  124  disposed on the second dielectric layer, and more specifically, the second coupling portion  142  may be located between the third internal electrode  123  and the fourth internal electrode  124  in the Y direction, and may mean an unallocated region of the third internal electrode  123  and the fourth internal electrode  124 . In a multilayer ceramic capacitor according to the present embodiment, a first coupling portion  141  and a second coupling portion  142  may be disposed on the dielectric layer to increase a bonding area between homogeneous materials, thereby improving mechanical strength of the capacitor chip. 
     In an embodiment of the present disclosure, the first coupling portion and the second coupling portion may be bonded. In the present specification, “adhesion” may mean a state in which surfaces of an adhering material and an adherend are coupled to each other by a coupling force of an interface. The coupling force of the interface may be due to chemical interaction between surface molecules of the adhering material and the adherend, or may be due to mechanical coupling. The first coupling portion and the second coupling portion may be bonded by physical or chemical coupling. When a tensile strength required to separate the first coupling portion from the second coupling portion is called as an adhesive force, the adhesive force between the first coupling portion and the second coupling portion is not particularly limited, buy may be, for example, 1 Mpa or more, 100 Gpa or less. In the present embodiment, the first coupling portion and the second coupling portion may be bonded by physical and/or chemical coupling to prevent delamination in the active layer. 
     The internal electrode may include a first internal electrode  121  and a second internal electrode  122  disposed on the same dielectric layer, a third internal electrode  123  and a fourth internal electrode  124  disposed on a different dielectric layer from the dielectric layer and disposed on the same dielectric layer, and a fifth internal electrode  125  and a sixth internal electrode  126  disposed on a dielectric layer different from the dielectric layer, respectively. In this case, a dielectric layer on which the first internal electrode  121  and the second internal electrode  122  are disposed may be defined as a first dielectric layer, a dielectric layer on which the third internal electrode  123  and the fourth internal electrode  124  are disposed may be defined as a second dielectric layer, and a dielectric layer on which the fifth internal electrode  125  or the sixth internal electrode may be defined as a third dielectric layer. 
       FIGS.  4  to  7    are plan views illustrating first to sixth internal electrode.  FIG.  4    illustrates a first dielectric layer including a first internal electrode  121  and a second internal electrode  122  and on which the first coupling portion  141  is disposed.  FIG.  5    illustrates a second dielectric layer including a third internal electrode  123  and a fourth internal electrode  124 , and on which the second coupling portion  142  is disposed.  FIGS.  5  and  6    illustrate a third dielectric layer on which the fifth internal electrode  125  and the sixth internal electrode  126  are disposed, respectively. 
     According to an embodiment of the present disclosure, the first dielectric layer to the third dielectric layer may be sequentially stacked. Referring to  FIGS.  2  to  7   , the first internal electrode  121 , the second internal electrode  122 , and the fifth internal electrode  125  may be disposed to be exposed to the third surface S 3  of the body  110 . In this case, the first internal electrode  121 , the second internal electrode  122 , and the fifth internal electrode  125  may be connected to a first external electrode  131  disposed on the third surface S 3  of the body  110 . 
     As in the above embodiment, referring to  FIGS.  2  to  7   , the third internal electrode  123 , the fourth internal electrode  124 , and the sixth internal electrode  126  may be disposed to be exposed to the fourth surface S 4  of the body  110 . In this case, the third internal electrode  123 , the fourth internal electrode  124 , and the sixth internal electrode  126  may be connected to a second external electrode  132  disposed on the fourth surface S 4  of the body  110 . 
     According to the above embodiment, the first coupling portion  141  and the second coupling portion  142  may be adhered to each other to increase mechanical strength of the chip. In addition, since the fifth internal electrode  125  and the sixth internal electrode  126  are disposed to oppose each other, the capacity of the multilayer ceramic capacitor according to the present disclosure may be further increased, thereby enabling implementation of a high-capacity chip. 
     In one example, a width W 1  of a first coupling portion  141  and/or a second coupling portion  142  may be 0.1 to 0.7 times a width of the fifth internal electrode  125  or the sixth internal electrode  126 . The width W 1  of the first coupling portion  141  and/or the second coupling portion  142  may be 0.10 times or more, 0.12 times or more, 0.14 times or more, 0.16 times or more, 0.18 times or more or 0.20 times or more, 0.70 times or less, 0.68 times or less, 0.66 times or less, 0.64 times or less, 0.62 times or less, or 0.60 times or less, but is not limited thereto. The width W 1  of the first coupling portion  141  and/or the second coupling portion  142  may satisfy the above range, thereby further improving mechanical reliability of the multilayer ceramic capacitor according to the present disclosure. 
     In an embodiment of the present disclosure, the body  110  may be configured such that a first dielectric layer, a second dielectric layer, and a third dielectric layer including the fifth internal electrode  125 , or a first dielectric layer, a second dielectric layer, and a third dielectric layer including the sixth internal electrode  126  are sequentially stacked. According to the present embodiment, a third dielectric layer may be disposed such that the fifth internal electrode and the sixth internal electrode oppose each other with the first dielectric layer and the second dielectric layer interposed therebetween. When the structure is applied, it is possible to improve the mechanical strength of the chip due to the first and second coupling portions of the first dielectric layer and the second dielectric layer and to maximize an improvement in capacitance of the multilayer ceramic capacitor according to the present disclosure. 
       FIGS.  9  to  13    are views illustrating another embodiment of the present disclosure. Referring to  FIGS.  9  to  13   , in the multilayer ceramic capacitor according to the present embodiment, the first internal electrode  221 , the third internal electrode  223 , and the fifth internal electrode  225  may be exposed to the third surface S 3  of the body  210 . In this case, the first internal electrode  221 , the third internal electrode  223 , and the fifth internal electrode  225  may be connected to a first external electrode  231  disposed on the third surface S 3  of the body  210 . 
     According to an embodiment of the present disclosure, a second internal electrode  222 , a fourth internal electrode  224 , and a sixth internal electrode  226  may be exposed to the fourth surface S 4  of the body  210 . In this case, the second internal electrode  222 , the fourth internal electrode  224 , and the sixth internal electrode  226  may be connected to a second external electrode  232 . 
     A material for forming the first to sixth internal electrodes  221 ,  222 ,  223 ,  224 ,  225 , and  226  is not particularly limited, and may be formed using a conductive paste including one or more materials, for example, of silver (Ag), palladium (Pd), gold (Au), platinum (Pt), nickel (Ni), copper (Cu), tin (Sn), tungsten (W), palladium (Pd), titanium (Ti) and alloys thereof. As a printing method of the conductive paste, a screen printing method or a gravure printing method may be used, but the present disclosure is not limited thereto. 
     In different embodiments, the width W 2  of coupling portion  222  and the width W 3  of coupling portion  242  may be same or different. The ratio of widths W 2  and W 3  to the width of the fifth or sixth internal electrodes  225 / 226  may be in a range from about 0.1 to 0.7 in either case, in various embodiments. 
     According to an embodiment of the present disclosure, first and second external electrodes  131  and  132  may be disposed on both surfaces of the body  110 . The first and second external electrodes  131  and  132  may be disposed on the third surface S 3  and the fourth surface S 4  of the body  110 , respectively. 
     The first external electrode  131  and the second external electrode  132  may be connected to the aforementioned internal electrodes, respectively, and may have opposite polarities. Therefore, even if the first to sixth internal electrode described above are disposed on different dielectric layers, a fast multilayer ceramic capacitor according to the present disclosure may act as a single chip, and may realize high-capacity while improving mechanical strength and moisture resistance reliability of the chip itself. 
     A material for forming the first and second external electrodes  131  and  132  is not particularly limited, and may be formed using a conductive paste including one or more materials, for example, of silver (Ag), palladium (Pd), gold (Au), platinum (Pt), nickel (Ni), copper (Cu), tin (Sn), tungsten (W), palladium (Pd), titanium (Ti) and alloys thereof. A method for forming the first and second external electrodes  131  and  132  needs not be particularly limited. For example, the first and second external electrodes  131  and  132  may be formed by dipping a body into a paste containing a conductive metal and glass, or by transferring a dry film obtained by drying the metal paste onto the third surface S 3  and the fourth surface S 4  of the body  110 . 
     As set forth above, according to an embodiment of the present disclosure, it is possible to provide a multilayer ceramic capacitor having excellent mechanical strength by using a coupling portion inside a dielectric layer. 
     According to another embodiment of the present disclosure, a multilayer ceramic capacitor having excellent moisture resistance reliability may be provided. 
     According to another embodiment of the present disclosure, a multilayer ceramic capacitor capable of preventing a crack or delamination while having a high capacity may be provided. 
     However, various and advantageous advantages and effects of the present disclosure are not limited to the above description, and will be more readily understood in the course of describing specific embodiments of the present disclosure. 
     While exemplary embodiments have been shown and described above, it will be apparent to those skilled in the art that modifications and variations could be made without departing from the scope of the present invention as defined by the appended claims.