Patent Publication Number: US-2023135429-A1

Title: Method for fabricating multilayer ceramic electronic component

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application claims the benefit of priority to Korean Patent Application No. 10-2021-0146795 filed on Oct. 29, 2021 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a method for manufacturing a multilayer ceramic electronic component. 
     2. Description of Related Art 
     Electronic components using ceramic materials include capacitors, inductors, piezoelectric elements, varistors, thermistors, and the like. 
     A multilayer ceramic capacitor (MLCC), one such ceramic electronic component, has advantages of such as miniaturization, high capacitance, and ease of mounting. 
     The multilayer ceramic capacitor is a chip-type condenser, mounted on the printed circuit boards of various types of electronic products, including a computer, a personal digital assistant (PDA), a mobile phone, or the like, serving to charge or discharge electricity, and has various sizes and stacked shapes depending on the purpose and capacitance used. 
     The multilayer ceramic capacitor may be manufactured by stacking a plurality of ceramic green sheets on which a plurality of internal electrode patterns are arranged to prepare a ceramic laminate, and forming a ceramic body including a dielectric layer and internal electrodes by sintering the ceramic laminate, and then forming an external electrode on an external surface of the ceramic body. 
     In this case, a shrinkage amount of the dielectric layer and the internal electrode is different in a process of sintering the laminate, the ceramic body is deformed such as being stretched or contracted in length, width, and thickness directions after sintering. Accordingly, when the multilayer ceramic capacitor is mounted on a substrate or the like, there may be a problem in that an occurrence of a short defect due to contact between other, adjacent electronic components increases. 
     SUMMARY 
     An aspect of the present disclosure is to provide a method for manufacturing a multilayer ceramic electronic component having high reliability by preventing occurrence of short circuit defects due to deformation of a sintered ceramic body. 
     According to an aspect of the present disclosure, a method for manufacturing a multilayer ceramic electronic component may include: an operation of forming a conductive paste for internal electrodes on a ceramic green sheet; an operation of forming a ceramic laminate by laminating a plurality of the ceramic green sheets; an operation of forming a ceramic body including a dielectric layer and a plurality of internal electrodes by sintering the ceramic laminate; an operation of trimming at least one surface of the ceramic body; and an operation of forming at least one external electrode on the at least one trimmed surface of the ceramic body. 
     According to another aspect of the present disclosure, a method for manufacturing a multilayer ceramic electronic component may include: an operation of stacking a plurality of ceramic green sheets each of which includes a conductive paste and an internal electrode, to form a ceramic laminate; an operation of sintering the ceramic laminate to form a ceramic body having a cross-section of a substantially trapezoidal shape; an operation of trimming at least one side surface of the ceramic body with the trapezoidal shape; and an operation of forming at least one external electrode on the trimmed at least one side surface of the ceramic body. 
    
    
     
       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 perspective view schematically illustrating a multilayer ceramic electronic component manufactured according to an embodiment of the present disclosure; 
         FIG.  2    is a cross-sectional view taken along line A-A′ of the multilayer ceramic electronic component of  FIG.  1   ; 
         FIG.  3    is a process flow diagram illustrating a manufacturing process of a multilayer ceramic electronic component according to an embodiment of the present disclosure; 
         FIG.  4    is a cross-sectional view illustrating a ceramic body deformed by sintering; 
         FIG.  5    is a cross-sectional view schematically illustrating a method of manufacturing a multilayer ceramic electronic component according to an embodiment of the present disclosure; 
         FIG.  6    is a cross-sectional view of a multilayer ceramic electronic component manufactured according to a conventional method for manufacturing a multilayer ceramic electronic component; and 
         FIG.  7    is a cross-sectional view schematically illustrating a laser processing according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, embodiments of the present disclosure will be described as follows with reference to the attached drawings. It is not intended to limit the techniques described herein to specific embodiments, and it should be understood to include various modifications, equivalents, and/or alternatives to the embodiments of the present disclosure. In connection with the description of the drawings, similar reference numerals may be used for similar components. 
     In the drawings, for clarity of description, parts irrelevant to the description may be omitted, and thicknesses of elements may be magnified to clearly represent layers and regions. Components having the same functions within a scope of the same idea may be described using the same reference numerals. In the present specification, expressions such as “having”, “may have”, “include” or “may include” may indicate a presence of corresponding features (e.g., components such as numerical values, functions, operations, components, or the like), and may not exclude a presence of additional features. 
     In the drawings, a first direction may be defined as a stacking direction or a thickness (T) direction, a second direction may be defined as a length (L) direction, and a third direction may be defined as a width (W) direction. 
       FIG.  1    is a perspective view of a multilayer ceramic electronic component  100  manufactured according to a method of manufacturing a multilayer ceramic electronic component according to an embodiment of the present disclosure, and  FIG.  2    is a cross-sectional view taken along line A-A′ of the multilayer ceramic electronic component  100  of  FIG.  1   . 
     Referring to  FIGS.  1  and  2   , the ceramic body  110  may include a plurality of dielectric layers  111  and first and second internal electrodes  121  and  122  formed on the dielectric layers  111 , and may be formed by stacking a plurality of dielectric layers  111  on which the first and second internal electrodes  121  and  122  are formed. In addition, the first and second internal electrodes  121  and  122  may be disposed to face each other with one dielectric layer  111  interposed therebetween. In addition, first and second external electrodes  131  and  132  may be formed on an external surface of the ceramic body  110  to be electrically connected to the first and second internal electrodes  121  and  122 , respectively. 
       FIG.  3    is a process flow diagram illustrating a manufacturing process of the multilayer ceramic electronic component  100  according to an embodiment of the present disclosure. 
     Referring to  FIG.  3   , a method for manufacturing a multilayer ceramic electronic component according to an embodiment of the present disclosure may include an operation of forming a conductive paste for internal electrodes on a ceramic green sheet (P1), an operation of forming a ceramic laminate by stacking the plurality of ceramic green sheets (P2), an operation of forming a ceramic body including a dielectric layer and a plurality of internal electrodes by sintering the ceramic laminate (P3), an operation of trimming at least one surface of the ceramic body (P4); and an operation of forming an external electrode on the trimmed surface of the ceramic body (P5). 
     In the method of manufacturing a multilayer ceramic electronic component according to an embodiment of the present disclosure, first, a slurry including ceramic powder such as barium titanate (BaTiO3) may be coated on a carrier film and dried to prepare a ceramic green sheet. 
     The ceramic green sheet may be formed by mixing ceramic powder, a binder, and a solvent to prepare a slurry, and manufacturing the slurry into a sheet having a thickness designed by a doctor blade method, or the like. 
     Next, a conductive paste for internal electrodes including conductive powder and common material powder may be prepared. Although not limited thereto, the conductive powder may include at least one selected from a group consisting of nickel (Ni), copper (Cu), gold (Au), silver (Ag), palladium (Pd), platinum (Pt), and alloys thereof. 
     The common material powder may include a ceramic material, and the same material as the dielectric material included in the ceramic green sheet may be used. Although not limited thereto, the common material powder may include at least one of barium titanate and an oxide of barium titanate. 
     Next, the conductive paste for internal electrodes may be formed on the ceramic green sheet by a screen-printing method, a gravure printing method, or the like (P1). In addition, a plurality of ceramic green sheets on which the conductive paste is formed may be stacked to form a ceramic laminate (P2). Subsequently, the laminate may be sintered to form a ceramic body including a dielectric layer and a plurality of internal electrodes (P3). 
     Meanwhile, the operation of sintering of the laminate is not limited thereto, but may be performed under a reducing atmosphere in which nitrogen (N 2 ) gas and hydrogen (H 2 ) gas are mixed. In general, a sintering time of the laminate is not particularly limited because it may proceed while being changed depending on a capacitance, a ceramic composition, an internal electrode composition, and the like, but may be, for example, 1 to 30 hours. The sintering temperature is also not particularly limited because it may change depending on the ceramic composition, the internal electrode composition, and the like, but may be, for example, 1000 to 1300° C. 
     Referring to  FIG.  2   , the ceramic body  110  may include an active portion A in which a plurality of internal electrodes are disposed and a cover portion C in which internal electrodes are not disposed. 
     Meanwhile, since a shrinkage amount of the internal electrodes  121  and  122  when the ceramic body  110  is sintered in the manufacturing process of the multilayer ceramic electronic component  100  is greater than a shrinkage amount of the dielectric layer  111 , contraction stress acting on the active portion A may be relatively greater than contraction stress acting on the cover portion C. Accordingly, as shown in  FIG.  4   , a cross-section of the ceramic body  110 , in contact with the outside may be deformed, such as being stretched or contracted. Due to the deformation of the ceramic body  110 , when a final multilayer ceramic electronic component  100  is mounted, a short circuit defect, or the like, due to contact with other adjacent electronic components, may occur, and a problem in which capacitance formation may not be optimized may occur. 
     Referring to  FIG.  5   , the method for manufacturing a multilayer ceramic electronic component according to an embodiment of the present disclosure may include an operation of trimming at least one surface of the ceramic body  110  (P4). A cross-section of the ceramic body  110  deformed by sintering may be removed by trimming at least one surface of the ceramic body  110 . 
     Referring to  FIGS.  2  and  3   , the method of manufacturing the multilayer ceramic electronic component  100  according to an embodiment of the present disclosure may include an operation of forming an external electrode on the trimmed surface of the ceramic body (P5). The operation of forming the external electrodes  131  and  132  may be performed by applying a paste for external electrodes to the outside of the ceramic body  110 . The application of the paste for external electrodes may be performed by dipping the ceramic body  110  into the paste for external electrodes, but an embodiment of the present disclosure is not limited thereto. 
     Referring to  FIG.  6   , in the related art, an external electrode  13  was formed without trimming the ceramic body  10  separately. In this case, when the ceramic body  10  is dipped into a conductive paste for external electrodes to form the external electrode  13 , a problem in which the external electrode  13  is not uniformly formed on the deformed ceramic body  10  due to sintering shrinkage having occurred. As such, when a thickness of the external electrode  13  formed on the ceramic body  10  is non-uniform, poor plating and poor shape uniformity may be caused, and a portion where the external electrode  13  is thinly coated may be vulnerable to penetration of a plating solution, thereby reducing reliability. 
     On the other hand, according to the method of manufacturing a multilayer ceramic electronic component according to an embodiment of the present disclosure, since the external electrode is formed on the trimmed surface of the ceramic body, the external electrode may be uniformly formed. Accordingly, it is possible to manufacture a multilayer ceramic electronic component having high reliability compared to the conventional manufacturing method. 
     According to the method of manufacturing a multilayer ceramic electronic component according to an embodiment of the present disclosure, at least one surface of the ceramic body may include a first surface S1 and a second surface S2 facing each other, and the operation of forming the external electrode may include an operation of forming first and second external electrodes  131  and  132  on the first surface S1 and the second surface S2, respectively. 
     Therefore, referring to  FIGS.  2  and  5   , first and second external electrodes  131  and  132  may be formed on the trimmed first and second surfaces S1 and S2 of the ceramic body  110  to face each other. The first external electrode  131  may be connected to a plurality of first internal electrodes  121  exposed to the first surface, and the second external electrode  132  may be connected to a plurality of second internal electrodes  122  exposed to the second surface. 
     According to an embodiment of the present disclosure, in the ceramic body  110 , when a stacking direction of the plurality of internal electrodes  121  and  122  is a first direction, and a direction, perpendicular to the first and second surfaces is a second direction, the ceramic body may include regions having different lengths in the second direction, and the trimming operation may be an operation of removing a portion of a region having a longer length in the second direction from the ceramic body. 
     Referring to  FIG.  5   , the ceramic body  110  may include regions having different lengths in the second direction, and a portion of the region having a longer length in the second direction may be removed. That is, trimming may be performed so that the lengths of all regions of the first and second surfaces S1 and S2 of the ceramic body no in the second direction are uniformly formed. As a result, first and second external electrodes  131  and  132  formed on the first and second surfaces S1 and S2 may be uniformly formed. 
     In the method of manufacturing a multilayer ceramic electronic component according to an embodiment of the present disclosure, when a length in the second direction from an upper surface of the ceramic body is L1, and a length in the second direction from a lower surface of the ceramic body is L2, a condition of L2&gt;L1 can be satisfied. 
     Referring to  FIG.  4   , as described above, the ceramic body  110  may be deformed due to a difference in contraction stress acting on the ceramic body  110  during sintering. Although the upper and lower surfaces of the deformed ceramic body  110  may be symmetrically contracted with respect to the second direction, when a temperature increase rate during the sintering process is high, the upper and lower surfaces of the ceramic body  110  may be asymmetrically contracted with respect to the second direction. Accordingly, the ceramic body  110  may have a length in the second direction on the lower surface longer than the length in the second direction on the upper surface (L2&gt;L1). 
     In addition, the ceramic body no may have a shape in which the length in the second direction gradually increases from the upper surface to the lower surface thereof. Accordingly, as shown in  FIG.  4   , a cross-section of the ceramic body  110  when viewed from a third direction may be substantially trapezoidal. 
     In the method for manufacturing a multilayer ceramic electronic component according to an embodiment of the present disclosure, when a length of the ceramic laminate in a second direction before sintering is L0, a condition of (L0−L1)/L0≥0.15 may be further satisfied. 
     As shown in  FIG.  4   , when the length of the ceramic laminate in the second direction before sintering satisfies the above conditions, even after shrinkage deformation of the ceramic body no by sintering and an operation of trimming of the ceramic body no, the ceramic body no may maintain a size of a certain level or more, and have greater capacitance than an existing multilayer ceramic electronic component formed therein. 
     Referring to  FIG.  7   , according to an embodiment of the present disclosure, the trimming operation may be performed by laser processing. In the case of dicing cutting, as blades physically contact internal electrodes  221  and  222 , short circuit defects, or the like, may occur due to deformation of the internal electrodes  221  and  222 , so it is preferable to be performed by laser cutting. 
     In this case, the trimming operation by laser processing may be performed by irradiating a laser beam toward the ceramic body  210  from a lower portion of the ceramic body  210  according to a deformed shape of the ceramic body  210 . 
     Experimental Example 
     Table 1 below compares a short rate of the multilayer ceramic electronic component Ref according to the conventional manufacturing method and the multilayer ceramic electronic component Exp manufactured according to an embodiment of the present disclosure. The short rate is obtained by measuring a short rate occurring at a measurement voltage of 0.5 V and a frequency of 1 kHz, for 100 electronic components, respectively, according to the manufacturing method. 
     When a measured capacitance of the multilayer ceramic electronic component is 3.2 μF or less or 4.2 μF or more, or a measured dielectric factor (DF) of the multilayer ceramic electronic component is 4.0% or less or 7.0% or more, it is determined that a short-circuit defect occurred. 
     Referring to Table 1 below, in the case of the conventional multilayer ceramic electronic component, a short-circuit rate of 8% is shown, but in the multilayer ceramic electronic component manufactured according to an embodiment of the present disclosure, a short-circuit rate of 2% was shown, it can be seen that the short-circuit rate of the multilayer ceramic electronic component manufactured according to an embodiment of the present disclosure was significantly reduced. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Ref. 
                 EXP 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 Short-circuit rate(%) 
                 8.0 
                 2.0 
               
               
                   
                   
               
            
           
         
       
     
     Table 2 below compares capacitance and a dielectric factor (DF) of the multilayer ceramic electronic component (Ref) according to the present conventional manufacturing method and the multilayer ceramic electronic component (Exp) manufactured according to an embodiment of the present disclosure according to a sintering temperature. 
     100 multilayer ceramic electronic components having no short-circuit defects even after sintering were selected in an amount of 100 each according to the manufacturing method, and the capacitance and the dielectric factor (DF) were measured at a measurement voltage 0.5V and a frequency of 1 KHz, and then an average value thereof was obtained. 
     Referring to Table 2 below, it can be seen that the multilayer ceramic electronic component manufactured according to the embodiment of the present disclosure has better capacitance than the multilayer ceramic electronic component manufactured according to the conventional manufacturing method. 
     
       
         
           
               
               
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 sintering 
                 Capacitance (μF)/DF(%) 
                   
               
            
           
           
               
               
               
            
               
                 temperature 
                 Ref. 
                 EXP 
               
               
                   
               
               
                 1120° C. 
                 3.81 μF/5.01% 
                     3.84 μF/(5.10%) 
               
               
                 1130° C. 
                 3.89 μF/5.12% 
                 3.95 μF/5.18% 
               
               
                 1140° C. 
                 3.74 μF/4.89% 
                 3.79 μF/4.95% 
               
               
                   
               
            
           
         
       
     
     As set forth above, as one of the various effects of the present disclosure, a method for manufacturing a multilayer ceramic electronic component having high reliability by preventing occurrence of short circuit defects caused by deformation of a sintered ceramic body may be provided. 
     However, various and advantageous advantages and effects of the present invention are not limited to the above description, and will be more readily understood in the process of describing specific embodiments of the present invention. 
     While the embodiments have been illustrated 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 in the embodiment as defined by the appended claims.