Patent Publication Number: US-9424980-B2

Title: Electronic component and method of producing same

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority from Japanese Patent Application No. 2011-152589 filed on Jul. 11, 2011, the entire contents of which are hereby incorporated by reference into this application. 
     TECHNICAL FIELD 
     The technical field relates to an electronic component and a method of producing the same, and in particular, to an electronic component that includes a laminate and a method of producing the same. 
     BACKGROUND 
     An example of a conventional electronic component is a stacked inductor described in Japanese Unexamined Patent Application Publication No. 2010-165975.  FIG. 9  is an exploded perspective view of a stacked inductor  500  described in this patent literature. 
     As illustrated in  FIG. 9 , the stacked inductor  500  includes a laminate  502 , external electrodes  508  and  510 , and a coil L. The laminate  502  is one in which insulating layers  504   a  to  504   d  are stacked. The coil L is incorporated in the laminate  502  and includes coil conductive patterns  506   a  to  506   c  and via hole conductors V 501  and V 502 . Each of the coil conductive patterns  506   a  to  506   c  has a substantially ring shape which is formed by cutting a part of a ring shape off. The coil conductive patterns  506   a  to  506   c  are disposed on the insulating layers  504   b  to  504   d , respectively. The via hole conductor V 501  connects the coil conductive patterns  506   a  and  506   b . The via hole conductor V 502  connects the coil conductive patterns  506   b  and  506   c . Thus, the coil L has a substantially helical shape. 
     The external electrode  508  includes external electrode patterns  508   a  to  508   c . Each of the external electrode patterns  508   a  to  508   c  has a substantially L shape. The external electrode patterns  508   a  to  508   c  are disposed in corners of the insulating layers  504   b  to  504   d , respectively. The external electrode  510  includes external electrode patterns  510   a  to  510   c . Each of the external electrode patterns  510   a  to  510   c  has a substantially L shape. The external electrode patterns  510   a  to  510   c  are disposed in corners of the insulating layers  504   b  to  504   d , respectively. The top and bottom of the external electrodes  508  and  510  in the stacking direction thereof are overlaid with the insulating layers  504   a  and  504   d , respectively. 
     SUMMARY 
     The present disclosure provides an electronic component capable of suppressing the occurrence of breakage of a laminate and a method of producing the electronic component. 
     According to an aspect of the present disclosure, an electronic component includes a laminate in which plural insulator layers are stacked and an external electrode exposed to an exterior of the laminate includes plural conductive layers stacked in a staking direction. Each of the conductive layers pass through a first part of the plural insulator layers in a stacking direction. At least one side of the external electrode in the stacking direction is overlaid with a second part of the plural insulator layers. At least one side surface of the external electrode facing in the stacking direction includes a portion that is uneven with another portion of the side surface. 
     According to another aspect of the present invention, a method of producing an electronic component includes a first step of forming an outer insulator layer, a second step of forming, on the outer insulator layer, an inner insulator layer in which an opening is formed, a third step of forming a conductive layer on the inner insulator layer, the conductive layer having an area larger than the opening and overlapping the opening, and a fourth step of cutting a mother laminate including the outer insulator layer and the inner insulator layer into a plurality of laminates. In the fourth step an external electrode including the conductive layer is exposed from the laminate in a first cut surface formed by the cutting. 
     Other features, elements, characteristics, and advantages of the present disclosure will become more apparent from the following detailed description with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an electronic component according to a first exemplary embodiment. 
         FIG. 2  is an exploded perspective view of the electronic component illustrated in  FIG. 1 . 
         FIG. 3A  illustrates the electronic component in plan view from a negative z-axis direction,  FIG. 3B  illustrates the electronic component in plan view from a negative x-axis direction, and  FIG. 3C  illustrates the electronic component in plan view from a positive x-axis direction. 
         FIGS. 4A to 4D  are plan views of the electronic component in production. 
         FIGS. 5A to 5D  are plan views of the electronic component in production. 
         FIGS. 6A to 6D  are plan views of the electronic component in production. 
         FIGS. 7A to 7C  are plan views of the electronic component in production. 
         FIG. 8A  illustrates an electronic component in plan view from the negative z-axis direction,  FIG. 8B  illustrates the electronic component in plan view from the negative x-axis direction, and  FIG. 8C  illustrates the electronic component in plan view from the positive x-axis direction. 
         FIG. 9  is an exploded perspective view of a stacked inductor described in the related art. 
     
    
    
     DETAILED DESCRIPTION 
     The inventor realized that in the stacked inductor  500  described in Japanese Unexamined Patent Application Publication No. 2010-165975, the laminate  502  may be damaged. More specifically, the process of producing the stacked inductor  500  contains a dividing step of dividing a mother laminate into individual laminates  502  and a firing step of firing the laminates  502 . In the dividing step and the firing step, a stress is applied to each of the laminates  502 . Because the material of the laminate  502  differs from the material of the external electrodes  508  and  510 , when a stress is applied to the laminate  502 , an internal stress remains between the laminate  502  and the external electrodes  508  and  510 . If the laminate  502  is subjected to barrel polishing or plating in the state where the internal stress remains, the impact of the barrel polishing or plating may cause breakage such as a crack or the like in a portion in each of the insulating layers  504   a  and  504   d , the portion being in contact with the external electrodes  508  and  510 . 
     An electronic component according to exemplary embodiments and a method of producing the same that can address the above-described breakage issues will now be described. 
     A configuration of an electronic component according to an exemplary embodiment is described below with reference to the drawings.  FIG. 1  is a perspective view of an electronic component  10  according to a first exemplary embodiment.  FIG. 2  is an exploded perspective view of the electronic component  10  illustrated in  FIG. 1 . In the following description, the stacking direction of the electronic component  10  is defined as the y-axis direction. In plan view from the y-axis direction, the direction in which the long sides of the electronic component  10  extend is defined as the x-axis direction and the direction in which the short sides of the electronic component  10  extend is defined as the z-axis direction.  FIG. 3A  illustrates the electronic component  10  in plan view from the negative z-axis direction,  FIG. 3B  illustrates the electronic component  10  in plan view from the negative x-axis direction, and  FIG. 3C  illustrates the electronic component  10  in plan view from the positive x-axis direction. 
     As illustrated in  FIGS. 1 and 2 , the electronic component  10  includes a laminate  12 , external electrodes  14  ( 14   a ,  14   b ), and a coil L (not illustrated in  FIG. 1 ). 
     As illustrated in  FIG. 2 , the laminate  12  is one in which a plurality of insulator layers  16  ( 16   a  to  16   h ) are stacked in this order from negative to positive in the y-axis direction. The laminate  12  has a substantially rectangular parallelepiped shape. The laminate  12  includes an upper surface S 1 , a lower surface S 2 , end surfaces S 3  and S 4 , and side surfaces S 5  and S 6 . The upper surface S 1  is the surface of the laminate  12  in the positive z-axis direction. The lower surface S 2  is the surface of the laminate  12  in the negative z-axis direction and a mounting surface that faces a circuit substrate when the electronic component  10  is mounted on the circuit substrate. The upper surface S 1  is a series of the long sides (outer edges) of the insulator layers  16  facing in the positive z-axis direction, and the lower surface S 2  is a series of the long sides (outer edges) of the insulator layers  16  facing in the negative z-axis direction. The end surface S 3  is the surface of the laminate  12  facing in the negative x-axis direction, and the end surface S 4  is the surface of the laminate  12  facing in the positive x-axis direction. The end surface S 3  is a series of the short sides (outer edges) of the insulator layers  16  facing in the negative x-axis direction, and the end surface S 4  is a series of the short sides (outer edges) of the insulator layers  16  facing in the positive x-axis direction. The end surfaces S 3  and S 4  are adjacent surfaces to the lower surface S 2 . The side surface S 5  is the surface of the laminate  12  facing in the positive y-axis direction, and the side surface S 6  is the surface of the laminate  12  facing in the negative y-axis direction. 
     As illustrated in  FIG. 2 , each of the insulator layers  16  can have a substantially rectangular shape and can be made of an insulating material whose main component is a borosilicate glass, for example. In the following description, the surface of the insulator layer  16  facing in the positive y-axis direction is referred to as a front surface, and the surface of the insulator layer  16  facing in the negative y-axis direction is referred to as a back surface. 
     The coil L includes coil conductive layers  18  ( 18   a  to  18   g ) and via hole conductors V 1  to V 6 . The coil L has a substantially helical shape turning clockwise in plan view from the positive y-axis direction and winding from negative to positive in the y-axis direction. The coil conductive layers  18   a  to  18   g  are disposed on the insulator layers  16   a  to  16   g , respectively. Each of the coil conductive layers  18   a  to  18   g  has a substantially rectangular ring shape which is formed by cutting off (i.e., excluding) a part of a rectangular ring shape. The number of turns of each of the coil conductive layers  18   a  to  18   g  is about 3/4. Each of the coil conductive layers  18  can be made of a conductive material whose main component is silver, for example. In the following description, the upstream end in the clockwise direction of each coil conductive layer  18  is referred to as an upstream end, and the downstream end in the clockwise direction of each coil conductive layer  18  is referred to as a downstream end. 
     The via hole conductors V 1  to V 6  pass through the insulator layers  16   b  to  16   g  in the y-axis direction, respectively. The via hole conductors V 1  to V 6  can be made of a conductive material whose main component is silver, for example. The via hole conductor V 1  connects the downstream end of the coil conductive layer  18   a  and the upstream end of the coil conductive layer  18   b . The via hole conductor V 2  connects the downstream end of the coil conductive layer  18   b  and the upstream end of the coil conductive layer  18   c . The via hole conductor V 3  connects the downstream end of the coil conductive layer  18   c  and the upstream end of the coil conductive layer  18   d . The via hole conductor V 4  connects the downstream end of the coil conductive layer  18   d  and the upstream end of the coil conductive layer  18   e . The via hole conductor V 5  connects the downstream end of the coil conductive layer  18   e  and the upstream end of the coil conductive layer  18   f . The via hole conductor V 6  connects the downstream end of the coil conductive layer  18   f  and the upstream end of the coil conductive layer  18   g.    
     As illustrated in  FIG. 1 , the external electrode  14   a  is embedded in the laminate  12  and is exposed to the exterior of the laminate  12  so as to extend over the border between the end surface S 3  and the lower surface S 2 . That is, in plan view from the y-axis direction, the external electrode  14   a  is substantially L-shaped. As illustrated in  FIG. 2 , the external electrode  14   a  is one in which external electrode conductive layers  20  ( 20   a  to  20   d ),  21  ( 21   a  to  21   d ), ( 22   a  to  22   d ), and  25  ( 25   a  to  25   i ) are stacked. The external electrode conductive layers  20  ( 20   a  to  20   d ),  21  ( 21   a  to  21   d ),  22  ( 22   a  to  22   d ), and  25  ( 25   a  to  25   i ) are stacked, thus passing through the insulator layers  16   b  to  16   g  in the y-axis direction and being electrically coupled together, as illustrated in  FIG. 2 . 
     The external electrode conductive layers  25   b ,  25   d ,  25   f , and  25   h  pass through the insulator layers  16   c ,  16   d ,  16   e , and  16   f , respectively, in the y-axis direction and are substantially L-shaped. In plan view from the y-axis direction, the external electrode conductive layers  25   b ,  25   d ,  25   f , and  25   h  are in contact with the short side of each of the insulator layers  16   a  and  16   h  in the negative x-axis direction and the long side thereof in the negative z-axis direction. 
     The external electrode conductive layers  25   a  to  25   i  coincide with each other in plan view from the y-axis direction. The external electrode conductive layer  25   b  is in contact with the external electrode conductive layers  25   a  and  25   c . The external electrode conductive layer  25   d  is in contact with the external electrode conductive layers  25   c  and  25   e . The external electrode conductive layer  25   f  is in contact with the external electrode conductive layers  25   e  and  25   g . The external electrode conductive layer  25   h  is in contact with the external electrode conductive layers  25   g  and  25   i.    
     The external electrode conductive layers  20   a ,  21   a , and  22   a  are disposed on the front surface of the insulator layer  16   a  and are substantially rectangular. The external electrode conductive layers  20   a ,  21   a , and  22   a  have a shape different from the shape of each of the external electrode conductive layers  25   a  to  25   i  in plan view from the y-axis direction and overlap the external electrode conductive layers  25   a  to  25   i  in plan view from the y-axis direction. More specifically, the external electrode conductive layer  21   a  is disposed in the corner of the insulator layer  16   a  in the negative x-axis direction and in the negative z-axis direction. The external electrode conductive layer  20   a  is disposed on the positive z-axis direction side with respect to the external electrode conductive layer  21   a  and is in contact with the short side of the insulator layer  16   a  in the negative x-axis direction. The external electrode conductive layer  20   a  is connected to the upstream end of the coil conductive layer  18   a . The external electrode conductive layer  22   a  is disposed on the positive x-axis direction side with respect to the external electrode conductive layer  21   a  and is in contact with the long side of the insulator layer  16   a  in the negative z-axis direction. 
     The external electrode conductive layers  20   b ,  21   b , and  22   b  pass through the insulator layer  16   b  in the y-axis direction and coincide with the external electrode conductive layers  20   a ,  21   a , and  22   a , respectively, in plan view from the y-axis direction. The external electrode conductive layers  20   b ,  21   b , and  22   b  are in contact with the external electrode conductive layers  20   a ,  21   a , and  22   a , respectively. 
     The external electrode conductive layers  20   c ,  21   c , and  22   c  pass through the insulator layer  16   g  in the y-axis direction and coincide with the external electrode conductive layers  20   a ,  21   a , and  22   a , respectively, in plan view from the y-axis direction. 
     The external electrode conductive layers  20   d ,  21   d , and  22   d  coincide with the external electrode conductive layers  20   c ,  21   c , and  22   c , respectively, in plan view from the y-axis direction. The external electrode conductive layers  20   d ,  21   d , and  22   d  are in contact with the external electrode conductive layers  20   c ,  21   c , and  22   c , respectively. 
     In the external electrode  14   a , in which the external electrode conductive layers  20 ,  21 ,  22 , and  25  are stacked in the above-described way, a side surface S 10  of the external electrode  14   a  located at the end in the negative y-axis direction and a side surface S 11  of the external electrode  14   a  located at the end in the positive y-axis direction are uneven, as illustrated in  FIGS. 3A and 3B . 
     More specifically, the side surface S 10  is defined by the external electrode conductive layers  20   a ,  20   b ,  21   a ,  21   b ,  22   a ,  22   b , and  25   a . The external electrode conductive layers  20   a ,  20   b ,  21   a ,  21   b ,  22   a , and  22   b  protrude in the negative y-axis direction farther than the external electrode conductive layer  25   a . Thus, the side surface S 10  has a shape in which in plan view from the negative z-axis direction both ends thereof in the x-axis direction protrude in the negative y-axis direction and a substantially central portion thereof in the x-axis direction is depressed in the positive y-axis direction. The side surface S 10  also has a shape in which in plan view from the negative x-axis direction both ends thereof in the z-axis direction protrude in the negative y-axis direction and a substantially central portion thereof in the z-axis direction is depressed in the positive y-axis direction. 
     The side surface S 11  is defined by the external electrode conductive layers  20   c ,  20   d ,  21   c ,  21   d ,  22   c ,  22   d , and  25   i . The external electrode conductive layers  20   c ,  20   d ,  21   c ,  21   d ,  22   c , and  22   d  protrude in the positive y-axis direction farther than the external electrode conductive layer  25   i . The side surface S 11  has a shape in which in plan view from the negative z-axis direction both ends thereof in the x-axis direction protrude in the positive y-axis direction and a substantially central portion thereof in the x-axis direction is depressed in the negative y-axis direction. The side surface S 11  also has a shape in which in plan view from the negative x-axis direction both ends thereof in the z-axis direction protrude in the positive y-axis direction and a substantially central portion thereof in the z-axis direction is depressed in the negative y-axis direction. 
     As illustrated in  FIG. 1 , the external electrode  14   b  is embedded in the laminate  12  and is exposed to the exterior of the laminate  12  so as to extend over the border between the end surface S 4  and the lower surface S 2 . That is, in plan view from the y-axis direction, the external electrode  14   b  is substantially L-shaped. As illustrated in  FIG. 2 , the external electrode  14   b  is one in which external electrode conductive layers  30  ( 30   a  to  30   d ),  31  ( 31   a  to  31   d ), ( 32   a  to  32   d ), and  35  ( 35   a  to  35   i ) are stacked. The external electrode conductive layers  30  ( 30   a  to  30   d ),  31  ( 31   a  to  31   d ),  32  ( 32   a  to  32   d ), and  35  ( 35   a  to  35   i ) are stacked, thus passing through part of the insulator layers  16  (the insulator layers  16   b  to  16   g ) in the y-axis direction and being electrically coupled together, as illustrated in  FIG. 2 . 
     The external electrode conductive layers  35   b ,  35   d ,  35   f , and  35   h  pass through the insulator layers  16   c ,  16   d ,  16   e , and  16   f , respectively, in the y-axis direction and are substantially L-shaped. In plan view from the y-axis direction, the external electrode conductive layers  35   b ,  35   d ,  35   f , and  35   h  are in contact with the short side of each of the insulator layers  16   a  and  16   h  (rest of the insulator layers  16 ) in the positive x-axis direction and the long side thereof in the negative z-axis direction. 
     The external electrode conductive layers  35   a  to  35   i  coincide with each other in plan view from the y-axis direction. The external electrode conductive layer  35   b  is in contact with the external electrode conductive layers  35   a  and  35   c . The external electrode conductive layer  35   d  is in contact with the external electrode conductive layers  35   c  and  35   e . The external electrode conductive layer  35   f  is in contact with the external electrode conductive layers  35   e  and  35   g . The external electrode conductive layer  35   h  is in contact with the external electrode conductive layers  35   g  and  35   i.    
     The external electrode conductive layers  30   a ,  31   a , and  32   a  are disposed on the front surface of the insulator layer  16   a  and are substantially rectangular. The external electrode conductive layers  30   a ,  31   a , and  32   a  have a shape different from the shape of each of the external electrode conductive layers  35   a  to  35   i  in plan view from the y-axis direction and overlap the external electrode conductive layers  35   a  to  35   i  in plan view from the y-axis direction. More specifically, the external electrode conductive layer  31   a  is disposed in the corner of the insulator layer  16   a  in the positive x-axis direction and in the negative z-axis direction. The external electrode conductive layer  30   a  is disposed on the positive z-axis direction side with respect to the external electrode conductive layer  31   a  and is in contact with the short side of the insulator layer  16   a  in the positive x-axis direction. The external electrode conductive layer  32   a  is disposed on the negative x-axis direction side with respect to the external electrode conductive layer  31   a  and is in contact with the long side of the insulator layer  16   a  in the negative z-axis direction. 
     The external electrode conductive layers  30   b ,  31   b , and  32   b  pass through the insulator layer  16   b  in the y-axis direction and coincide with the external electrode conductive layers  30   a ,  31   a , and  32   a , respectively, in plan view from the y-axis direction. The external electrode conductive layers  30   b ,  31   b , and  32   b  are in contact with the external electrode conductive layers  30   a ,  31   a , and  32   a , respectively. 
     The external electrode conductive layers  30   c ,  31   c , and  32   c  pass through the insulator layer  16   g  in the y-axis direction and coincide with the external electrode conductive layers  30   a ,  31   a , and  32   a , respectively, in plan view from the y-axis direction. 
     The external electrode conductive layers  30   d ,  31   d , and  32   d  coincide with the external electrode conductive layers  30   c ,  31   c , and  32   c , respectively, in plan view from the y-axis direction. The external electrode conductive layers  30   d ,  31   d , and  32   d  are in contact with the external electrode conductive layers  30   c ,  31   c , and  32   c , respectively. The external electrode conductive layer  30   d  is connected to the downstream end of the coil conductive layer  18   g.    
     The external electrode conductive layers  30 ,  31 ,  32 , and  35  are stacked in the above-described way, whereby a side surface S 12  of the external electrode  14   b  located at the end in the negative y-axis direction and a side surface S 13  of the external electrode  14   b  located at the end in the positive y-axis direction are uneven, as illustrated in  FIGS. 3A and 3C . 
     More specifically, the side surface S 12  is defined by the external electrode conductive layers  30   a ,  30   b ,  31   a ,  31   b ,  32   a ,  32   b , and  35   a . The external electrode conductive layers  30   a ,  30   b ,  31   a ,  31   b ,  32   a , and  32   b  protrude in the negative y-axis direction farther than the external electrode conductive layer  35   a . The side surface S 12  has a shape in which in plan view from the negative z-axis direction both ends thereof in the x-axis direction protrude in the negative y-axis direction and a substantially central portion thereof in the x-axis direction is depressed in the positive y-axis direction. The side surface S 12  also has a shape in which in plan view from the positive x-axis direction both ends thereof in the z-axis direction protrude in the negative y-axis direction and a substantially central portion thereof in the z-axis direction is depressed in the positive y-axis direction. 
     The side surface S 13  is defined by the external electrode conductive layers  30   c ,  30   d ,  31   c ,  31   d ,  32   c ,  32   d , and  35   i . The external electrode conductive layers  30   c ,  30   d ,  31   c ,  31   d ,  32   c , and  32   d  protrude in the positive y-axis direction farther than the external electrode conductive layer  35   i . The side surface S 13  has a shape in which in plan view from the negative z-axis direction both ends thereof in the x-axis direction protrude in the positive y-axis direction and a substantially central portion thereof in the x-axis direction is depressed in the negative y-axis direction. The side surface S 13  also has a shape in which in plan view from the positive x-axis direction both ends thereof in the z-axis direction protrude in the positive y-axis direction and a substantially central portion thereof in the z-axis direction is depressed in the negative y-axis direction. 
     The portion of each of the external electrodes  14   a  and  14   b  exposed from the laminate  12  to the outside is subjected to nickel plating and tin plating and to prevent corrosion. 
     Each of both sides of the each of the external electrodes  14   a  and  14   b  in the y-axis direction is overlaid with the insulator layer  16   a  or  16   h . Thus, the external electrodes  14   a  and  14   b  are not exposed in the side surfaces S 5  and S 6 . 
     A method of producing the electronic component  10  according to the first exemplary embodiment will now be described with reference to the drawings.  FIGS. 4A to 7C  are plan views of the electronic component  10  in production. 
     First, as illustrated in  FIG. 4A , insulating paste whose main component is a borosilicate glass is applied by screen printing to form an insulating paste layer  116   a . The insulating paste layer  116   a  is a paste layer that is to become the insulator layer  16   a , which is an outer insulator layer located outside the coil L. 
     Next, as illustrated in  FIG. 4B , the coil conductive layers  18   a  and the external electrode conductive layers  20   a ,  21   a ,  22   a ,  30   a ,  31   a , and  32   a  are formed by a photolithography step. Specifically, photosensitive conductive paste whose metal main component is silver is applied by screen printing to form a photosensitive conductive paste layer on the insulating paste layer  116   a . In addition, the photosensitive conductive paste layer is irradiated with ultraviolet rays or other rays through a photomask and developed using an alkaline solution or other solution. 
     Then, as illustrated in  FIG. 4C , an insulating paste layer  116   b  having a plurality of opening group h 1  and via holes H 1  is formed by a photolithography step. Specifically, insulating paste is applied by screen printing to from an insulating paste layer on the insulating paste layer  116   a . In addition, the photosensitive conductive paste layer is irradiated with ultraviolet rays or other rays through a photomask and developed using an alkaline solution or other solution. The insulating paste layer  116   b  is a paste layer that is to become the insulator layer  16   b , which is an inner insulator layer on which the coil L is disposed. Each of the opening group h 1  has substantially the same shape as that of set of the external electrode conductive layers  20   a ,  21   a ,  22   a ,  30   a ,  31   a , and  32   a  and overlaps the external electrode conductive layers  20   a ,  21   a ,  22   a ,  30   a ,  31   a , and  32   a.    
     Then, as illustrated in  FIG. 4D , the coil conductive layers  18   b , the external electrode conductive layers  20   b ,  21   b ,  22   b ,  30   b ,  31   b ,  32   b ,  25   a , and  35   a , and the via hole conductors V 1  are formed by a photolithography step. Specifically, photosensitive conductive paste whose metal main component is silver is applied by screen printing to form a photosensitive conductive paste layer on the insulating paste layer  116   b . In addition, the photosensitive conductive paste layer is irradiated with ultraviolet rays or other rays through a photomask and developed using an alkaline solution or other solution. In the step, the conductive layers are formed on the insulating paste layer  116   b  so as to have an area larger than corresponding opening group h 1  and overlap the corresponding opening group h 1 . In this way, the external electrode conductive layers  20   b ,  21   b ,  22   b ,  30   b ,  31   b , and  32   b  are formed in the opening group h 1 . The via hole conductors V 1  are formed in the via holes H 1 . In  FIG. 4D , the external electrode conductive layers  20   b ,  21   b ,  22   b ,  30   b ,  31   b , and  32   b  and the via hole conductors V 1  are not illustrated because they are hidden by the coil conductive layer  18   b  and the external electrode conductive layers  25   a  and  35   a.    
     Then, as illustrated in  FIG. 5A , an insulating paste layer  116   c  having openings h 2  and via holes H 2  is formed by a photolithography step. Specifically, insulating paste is applied by screen printing to form an insulating paste layer on the insulating paste layer  116   b . In addition, the photosensitive conductive paste layer is irradiated with ultraviolet rays or other rays through a photomask and developed using an alkaline solution or other solution. The insulating paste layer  116   c  is a paste layer that is to become the insulator layer  16   c , which is an internal insulator layer. Each of the openings h 2  has a cross shape in which the two external electrode conductive layers  25   b  and the two external electrode conductive layers  35   b  are combined. 
     Then, as illustrated in  FIG. 5B , the coil conductive layers  18   c , the external electrode conductive layers  25   b ,  25   c ,  35   b , and  35   c , and the via hole conductors V 2  are formed by a photolithography step. Specifically, photosensitive conductive paste whose main metal component is silver is applied by screen printing to form a photosensitive conductive paste layer on the insulating paste layer  116   c . In addition, the photosensitive conductive paste layer is irradiated with ultraviolet rays or other rays through a photomask and developed using an alkaline solution or other solution. In this way, the external electrode conductive layers  25   b  and  35   b  are formed in the openings h 2 . The via hole conductors V 2  are formed in the via holes H 2 . In  FIG. 5B , the external electrode conductive layers  25   b  and  35   b  and the via hole conductors V 2  are not illustrated because they are hidden by the coil conductive layers  18   c  and the external electrode conductive layers  25   c  and  35   c.    
     Then, as illustrated in  FIG. 5C , an insulating paste layer  116   d  having openings h 3  and via holes H 3  is formed by a photolithography step. Specifically, insulating paste is applied by screen printing to from an insulating paste layer on the insulating paste layer  116   c . In addition, the photosensitive conductive paste layer is irradiated with ultraviolet rays or other rays through a photomask and developed using an alkaline solution or other solution. The insulating paste layer  116   d  is a paste layer that is to become the insulator layer  16   d , which is an inner insulator layer. Each of the openings h 3  has substantially the same shape as that of each of the openings h 2 . 
     Then, as illustrated in  FIG. 5D , the coil conductive layers  18   d , the external electrode conductive layers  25   d ,  25   e ,  35   d , and  35   e , and the via hole conductors V 3  are formed by a photolithography step. Specifically, photosensitive conductive paste whose metal main component is silver is applied by screen printing to form a photosensitive conductive paste layer on the insulating paste layer  116   d . In addition, the photosensitive conductive paste layer is irradiated with ultraviolet rays or other rays through a photomask and developed using an alkaline solution or other solution. In this way, the external electrode conductive layers  25   d  and  35   d  are formed in the openings h 3 . The via hole conductors V 3  are formed in the via holes H 3 . In  FIG. 5D , the external electrode conductive layers  25   d  and  35   d  and the via hole conductors V 3  are not illustrated because they are hidden by the coil conductive layers  18   d  and the external electrode conductive layers  25   e  and  35   e.    
     Then, as illustrated in  FIG. 6A , an insulating paste layer  116   e  having openings h 4  and via holes H 4  is formed by a photolithography step. Specifically, insulating paste is applied by screen printing to form an insulating paste layer on the insulating paste layer  116   d . In addition, the photosensitive conductive paste layer is irradiated with ultraviolet rays or other rays through a photomask and developed using an alkaline solution or other solution. The insulating paste layer  116   e  is a paste layer that is to become the insulator layer  16   e , which is an internal insulator layer. Each of the openings h 4  has substantially the same shape as that of each of the openings h 2 . 
     Then, as illustrated in  FIG. 6B , the coil conductive layers  18   e , the external electrode conductive layers  25   f ,  25   g ,  35   f , and  35   g , and the via hole conductors V 4  are formed by a photolithography step. Specifically, photosensitive conductive paste whose main metal component is silver is applied by screen printing to form a photosensitive conductive paste layer on the insulating paste layer  116   e . In addition, the photosensitive conductive paste layer is irradiated with ultraviolet rays or other rays through a photomask and developed using an alkaline solution or other solution. In this way, the external electrode conductive layers  25   f  and  35   f  are formed in the openings h 4 . The via hole conductors V 4  are formed in the via holes H 4 . In  FIG. 6B , the external electrode conductive layers  25   f  and  35   f  and the via hole conductors V 4  are not illustrated because they are hidden by the coil conductive layers  18   e  and the external electrode conductive layers  25   g  and  35   g.    
     Then, as illustrated in  FIG. 6C , an insulating paste layer  116   f  having openings h 5  and via holes H 5  is formed by a photolithography step. Specifically, insulating paste is applied by screen printing to from an insulating paste layer on the insulating paste layer  116   e . In addition, the photosensitive conductive paste layer is irradiated with ultraviolet rays or other rays through a photomask and developed using an alkaline solution or other solution. The insulating paste layer  116   f  is a paste layer that is to become the insulator layer  16   f , which is an inner insulator layer. Each of the openings h 5  has substantially the same shape as that of each of the openings h 2 . 
     Then, as illustrated in  FIG. 6D , the coil conductive layers  18   f , the external electrode conductive layers  25   h ,  25   i ,  35   h , and  35   i  and the via hole conductors V 5  are formed by a photolithography step. Specifically, photosensitive conductive paste whose metal main component is silver is applied by screen printing to form a photosensitive conductive paste layer on the insulating paste layer  116   f . In addition, the photosensitive conductive paste layer is irradiated with ultraviolet rays or other rays through a photomask and developed using an alkaline solution or other solution. In this way, the external electrode conductive layers  25   h  and  35   h  are formed in the openings h 5 . The via hole conductors V 5  are formed in the via holes H 5 . In  FIG. 6D , the external electrode conductive layers  25   h  and  35   h  and the via hole conductors V 5  are not illustrated because they are hidden by the coil conductive layers  18   f  and the external electrode conductive layers  25   i  and  35   i.    
     Then, as illustrated in  FIG. 7A , an insulating paste layer  116   g  having a plurality of opening group h 6  and via holes H 6  is formed by a photolithography step. Specifically, insulating paste is applied by screen printing to form an insulating paste layer on the insulating paste layer  116   f . In addition, the photosensitive conductive paste layer is irradiated with ultraviolet rays or other rays through a photomask and developed using an alkaline solution or other solution. The insulating paste layer  116   g  is a paste layer that is to become the insulator layer  16   g , which is an internal insulator layer. Each of the opening group h 6  has substantially the same shape as that of set of the external electrode conductive layers  20   d ,  21   d ,  22   d ,  30   d ,  31   d , and  32   d  and overlaps the external electrode conductive layers  20   d ,  21   d ,  22   d ,  30   d ,  31   d , and  32   d.    
     Then, as illustrated in  FIG. 7B , the coil conductive layers  18   g  and the external electrode conductive layers  20   c ,  20   d ,  21   c ,  21   d ,  22   c ,  22   d ,  30   c ,  30   d ,  31   c ,  31   d ,  32   c , and  32   d  and the via hole conductors V 6  are formed by a photolithography step. Specifically, photosensitive conductive paste whose metal main component is silver is applied by screen printing to form a photosensitive conductive paste layer on the insulating paste layer  116   g . In addition, the photosensitive conductive paste layer is irradiated with ultraviolet rays or other rays through a photomask and developed using an alkaline solution or other solution. In this way, the external electrode conductive layers  20   c ,  21   c ,  22   c ,  30   c ,  31   c , and  32   c  are formed in the openings h 6 . The via hole conductors V 6  are formed in the via holes H 6 . In  FIG. 7B , the external electrode conductive layers  20   c ,  21   c ,  22   c ,  30   c ,  31   c , and  32   c  and the via hole conductors V 6  are not illustrated because they are hidden by the coil conductive layers  18   g  and the external electrode conductive layers  21   d ,  22   d ,  30   d , and  31   d.    
     Then, as illustrated in  FIG. 7C , an insulating paste layer  116   h  is formed on the insulating paste layer  116   g  by application of insulating paste by screen printing. The insulating paste layer  116   g  is a paste layer that is to become the insulator layer  16   h , which is an outer insulator layer. Through the above-described steps, a mother laminate  112  is obtained. 
     Then, the mother laminate  112  is cut into a plurality of unfired laminates  12  by, for example, dicing. In the step of cutting the mother laminate  112 , each of the external electrodes  14   a  and  14   b  is made to be exposed from each of the laminates  12  in two neighboring cut surfaces formed by the cutting. The two neighboring cut surfaces for the external electrode  14   a  are the lower surface S 2  and the end surface S 3 , whereas those for the external electrode  14   b  are the lower surface S 2  and the end surface S 4 . 
     Then, the unfired laminate  12  is fired under a predetermined condition, and the fired laminate  12  is obtained. In addition, the laminate  12  is subjected to barreling. 
     Lastly, the portions in the external electrodes  14   a  and  14   b  exposed from the laminate  12  are subjected to nickel plating with a thickness of approximately 2 μm to 7 μm and tin plating with a thickness of approximately 2 μm to 7 μm. Through the above-described steps, the electronic component  10  is completed. 
     In the electronic component  10  configured in the above-described way, the occurrence of breakage of the laminate  12  can be suppressed. More specifically, the process of producing the stacked inductor  500  described in Japanese Unexamined Patent Application Publication No. 2010-165975 contains a dividing step of dividing a mother laminate into individual laminates  502  and a firing step of firing the laminates  502 . In the dividing step and the firing step, a stress is applied to each of the laminates  502 . Because the material of the laminate  502  differs from the material of the external electrodes  508  and  510 , when a stress is applied to the laminate  502 , an internal stress remains between the laminate  502  and the external electrodes  508  and  510 . If the laminate  502  is subjected to barrel polishing or plating in the state where the internal stress remains, the impact of the barrel polishing or plating may cause in a portion in each of the insulating layers  504   a  and  504   d , the portion being in contact with the external electrodes  508  and  510 . As the result, breakage such as a crack or the like is caused in the portion therein. 
     In contrast, in the electronic component  10 , the side surfaces S 10  to S 13  located on both sides of the external electrodes  14   a  and  14   b  in the y-axis direction are uneven. Therefore, the area in which the insulator layers  16   a  and  16   h  on both sides of the external electrodes  14   a  and  14   b  in the y-axis direction are in contact with the external electrodes  14   a  and  14   b  is increased, whereby the adhesion therebetween is high. As a result, even if an impact occurs in the laminate  12 , the occurrence of breakage such as a crack in the portions of the insulator layers  16   a  and  16   h  in contact with the external electrodes  14   a  and  14   b  is suppressed. That is, breakage of the electronic component  10  is suppressed. 
     In the electronic component  10  of the preferred embodiments, both sides of the external electrodes  14   a  and  14   b  in the y-axis direction is overlaid with the insulator layers  16   a  and  16   h . However, it is not restrictive and it is possible to change to only one of the external electrodes being overlaid with insulator layer. 
     Next, an electronic component  10   a  according to a variation is described with reference to the drawings.  FIG. 8A  illustrates the electronic component  10   a  in plan view from the negative z-axis direction,  FIG. 8B  illustrates the electronic component  10   a  in plan view from the negative x-axis direction, and  FIG. 8C  illustrates the electronic component  10   a  in plan view from the positive x-axis direction. 
     The electronic component  10   a  differs from the electronic component  10  in the shape of each of the external electrodes  14   a  and  14   b . The electronic component  10   a  does not include the external electrode conductive layers  21  and  31 . Thus, the side surface S 10  has a shape in which in plan view from the negative z-axis direction the end in the positive x-axis direction protrudes in the negative y-axis direction farther than the other portions. The side surface S 10  also has a shape in which in plan view from the negative x-axis direction the end in the positive z-axis direction protrudes in the negative y-axis direction farther than the other portions. 
     Similarly, the side surface S 11  has a shape in which in plan view from the negative z-axis direction the end in the positive x-axis direction protrudes in the positive y-axis direction farther than the other portions. The side surface S 11  also has a shape in which in plan view from the negative x-axis direction the end in the positive z-axis direction protrudes in the positive y-axis direction farther than the other portions. 
     The side surface S 12  has a shape in which in plan view from the negative z-axis direction, the end in the negative x-axis direction protrudes in the negative y-axis direction farther than the other portions. The side surface S 12  also has a shape in which in plan view from the positive x-axis direction, the end in the positive z-axis direction protrudes in the negative y-axis direction farther than the other portions. 
     Similarly, the side surface S 13  has a shape in which in plan view from the negative z-axis direction the end in the negative x-axis direction protrudes in the positive y-axis direction farther than the other portions. The side surface S 13  also has a shape in which in plan view from the positive x-axis direction the end in the positive z-axis direction protrudes in the positive y-axis direction farther than the other portions. 
     In the above-described electronic component  10   a , breakage of the laminate can be suppressed. More specifically, a corner of the laminate is easily broken by an impact from the outside. In the electronic component  10   a , the width of the external electrode  14   a  in the y-axis direction is not a maximum in the corner between the lower surface S 2  and the end surface S 3 , and the width of the external electrode  14   b  in the y-axis direction is not a maximum in the corner between the lower surface S 2  and the end surface S 4 . Therefore, the distance d 2  from each of the external electrodes  14   a  and  14   b  to each of the side surfaces S 5  and S 6  in the corner of the electronic component  10   a  is larger than the distance d 1  from each of the external electrodes  14   a  and  14   b  to each of the side surfaces S 5  and S 6  in the corner of the electronic component  10 . Accordingly, in the electronic component  10   a , the occurrence of breakage in a corner of the laminate  12  can be suppressed. 
     To form the above-described external electrodes  14   a  and  14   b , in the steps illustrated in  FIGS. 4C and 7A , the insulating paste layers  116   b  and  116   g  are formed such that the openings h 1  and h 6  are not located in the corner between the two neighboring cut surfaces formed by cutting of the mother laminate  112 . In addition, in the steps illustrated in  FIGS. 4B and 7B , the external electrode conductive layers  21  and  31  are not formed. 
     In the electronic components  10  and  10   a , all of the side surfaces S 10  and S 11  of the external electrode  14   a  and the side surfaces S 12  and S 13  of the external electrode  14   b  are uneven. However, suppression of lamination breakage can be achieved with at least one of the side surfaces S 10  and S 11  uneven and/or at least one of the side surfaces S 12  and S 13  uneven. 
     In the electronic components  10  and  10   a , both sides of the external electrodes  14   a  and  14   b  in the y-axis direction is overlaid with the insulator layers  16   a  and  16   h . However, these examples are not restrictive and it is possible to change them to only one of the external electrodes being overlaid with insulator layer. 
     As described above, preferred embodiments of the present invention are useful in an electronic component and a method of producing the same and, in particular, advantageous in that breakage of a laminate can be suppressed. 
     While exemplary embodiments have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the disclosure.