Multilayer ceramic capacitor

Abstract

A multilayer ceramic capacitor 1 having internal electrode layers 3, internal dielectric layers 2 having the thickness of less than 2 μm, and external dielectric layers 20 wherein; the internal dielectric layers 2 and the external dielectric layers 20 include a plural number of dielectric particles 2 a, 20 a, and when y 1 is ratio(D 50 a/D 50 b) of D 50 a and D 50 b where D 50 a is an average particle size of dielectric particles 2 a included in the internal dielectric layers 2 and D 50 b is an average particle size of dielectric particles 20 a included in the external dielectric layer 20 and located at least 5 μm away from an internal electrode layer 3 a, arranged outermost part of all the internal electrode layers, to the stacked direction, and x is thickness of the internal dielectric layer 2, y 1 and x satisfy the following equations, y 1 ≦−0.75x+2.275 and y 1 ≧−0.75x+1.675. According to the present invention, even when thickness of internal dielectric layers 2 were made thinner, a multilayer ceramic capacitor 1 wherein improvements in all kinds of electric characteristics, specially an improvement in TC bias characteristic while having sufficient dielectric constant can be expected.

1. A multilayer ceramic capacitor having internal electrode layers, internal dielectric layers having thickness of less than 2 μm, and external dielectric layers wherein,  wherein: 
 the internal dielectric layers include a plural number of dielectric particles,  
 and when y 2  is ratio of dielectric particles (coarse particles), having an average particle size of at least 2.25 times larger than D 50 a, existing in dielectric particles where D 50 a is an average particle size of the dielectric particles included in the internal dielectric layers, and  
 x is thickness in μm of the internal dielectric layer,  
 y 2  and x satisfy the following equations;  equations: y 2 ≦−25x+37.5 and y 2 ≧−2.75x+4.125.  
 
     
     
       2. A multilayer ceramic capacitor having internal electrode layers, internal dielectric layers having thickness of less than 2 μm, and external dielectric layers wherein,  wherein: 
 the internal dielectric layers and the external dielectric layers include a plural number of dielectric particles,  
 and when y 1  is ratio(D 50 a/D 50 b) of D 50 a and D 50 b where D 50 a is an average particle size of dielectric particles included in the internal dielectric layers and D 50 b is an average particle size of dielectric particles included in the external dielectric layer and located at least 5 μm away from an internal electrode layer, arranged outermost part of all the internal electrode layers, to the stacked direction,  
 y 2  is ratio of dielectric particles (coarse particles),having an average particle size of at least 2.25 times larger than D 50 a, existing in the dielectric particles included in the internal dielectric layer, and  
 x is thickness in μm of the internal dielectric layer,  
 y 1  and x satisfy the following equations;  equations: y 1 ≦−0.75x+2.275 and y 1 ≧−0.75x+1.675 and  
 y 2  and x satisfy the following equations;  equations: y 2 ≦−25x+37.5 and y 2 ≧−2.75x+4.125.  
 
     
     
       3. A multilayer ceramic capacitor having internal electrode layers, internal dielectric layers having thickness of less than 2 μm, and external dielectric layers wherein,  wherein: 
 the internal dielectric layers and external dielectric layers include a plural number of dielectric particles,  
 and when y 3  is ratio (D 50 a/D 50 c) of D 50 a and D 50 c where D 50 a is an average particle size of dielectric particles included in the internal dielectric layers and D 50 c is an average particle size of main component material used to form internal dielectric layers, and  
 x is thickness in μm of the internal dielectric layers,  
 y 3  and x satisfy the following equations;  equations: y 3 ≦−0.95x+2.865 and y 3 ≧−0.95x+2.115.  
 
     
     
       4. A multilayer ceramic capacitor comprising internal electrode layers, internal dielectric layers having thickness of less than  2  μm, and external dielectric layers, wherein:
   the internal dielectric layers and the external dielectric layers include a plural number of dielectric particles,        and when y 1  is ratio  ( D 50 a/D 50 b )  of D 50 a and D 50 b where D 50 a is an average particle size of dielectric particles included in the internal dielectric layers and D 50 b is an average particle size of dielectric particles included in the external dielectric layer and located at least  5  μm away from an internal electrode layer, arranged outermost part of all the internal electrode layers, to the stacked direction,        y 2  is ratio of dielectric particles  ( coarse particles )  having an average particle size of at least  2 . 25  times larger than D 50 a, existing in the dielectric particles included in the internal dielectric layer, and        x is thickness in μm of the internal dielectric layers,        y 1  and x satisfy the following equations: y 1 ≦− 0 . 75 x+ 2 . 275 , y 1 > 1  and y 1 ≧− 0 . 75 x+ 1 . 675  and        y 2  and x also satisfy a relationship.