Multilayer Ceramic Capacitor Electrode Surface Roughness Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The reduction in thickness of dielectric and internal electrode layers in multilayer ceramic capacitors leads to a difference in sintering start temperatures, causing the internal electrode layer to contract unevenly, resulting in surface roughness and reliability degradation due to co-material extrusion and liquid phase flocculation at the interface between the electrode and dielectric layers.
Innovation Solution
A multilayer ceramic capacitor design with an arithmetic average roughness of the internal electrode layer of 30 nm or less and a maximum height of 360 nm or less, achieved through the use of a metal conductive paste with a specific grain size distribution and a co-material, ensures even thickness and suppressed co-material extrusion, maintaining the continuity modulus and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the thickness of the internal electrode layer is reduced to downsize the capacitor, then the chip size is reduced, but the co-material tends to be extruded to the dielectric layer side, causing surface roughness to increase and reliability to degrade
Solution Approach 1:
The patent applies parameter changes by precisely controlling the grain size distribution of metal powder (average grain diameter 100 nm or less, standard deviation 15 or less) and co-material (average grain diameter less than 10 nm, standard deviation 5 or less), and optimizing the amount of co-material (2.5-25 weight parts per 100 weight parts of metal powder). These parameter optimizations suppress co-material extrusion while maintaining continuity modulus, thereby preventing reliability degradation even with reduced electrode thickness
Solution Approach 2:
The patent uses composite materials by combining metal powder with co-material in specific proportions and grain size distributions. This composite structure in the internal electrode layer suppresses co-material extrusion to the dielectric layer side during sintering, maintaining surface flatness and preventing liquid phase flocculation, thus ensuring reliability in thinned capacitors
2Volume of moving object
If the thickness of the internal electrode layer is reduced, then the chip size is reduced, but the thickness becomes uneven in the stacking direction, causing liquid phase to flocculate at the interface and reliability to degrade
Solution Approach 1:
The patent applies parameter changes by optimizing the grain size distribution of metal powder (standard deviation 15 or less) and co-material (standard deviation 5 or less), ensuring uniform particle sizes that pack evenly during stacking. This results in uniform electrode thickness in the stacking direction, preventing liquid phase flocculation at interfaces and maintaining manufacturing precision in thinned capacitors
3Stability of the object's composition
If a co-material of ceramic is added to the internal electrode layer to delay contraction, then the continuity modulus is maintained, but the co-material is extruded to the dielectric layer side, causing surface roughness to increase
Solution Approach 1:
The patent applies parameter changes by optimizing the grain size of co-material (average less than 10 nm, standard deviation 5 or less) and its amount (2.5-25 weight parts per 100 weight parts of metal powder). These optimized parameters allow the co-material to remain dispersed within the electrode layer during sintering, maintaining continuity modulus while preventing extrusion to the dielectric layer side, thus keeping surface roughness low
Solution Approach 2:
The patent uses composite materials with specifically designed grain size distributions where fine co-material particles (average less than 10 nm) are dispersed in metal powder. This composite structure prevents co-material aggregation and extrusion during sintering, maintaining both continuity modulus and surface flatness in the internal electrode layer
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively suppresses the degradation of reliability by maintaining a high continuity modulus and preventing liquid phase flocculation, achieving desirable characteristics in multilayer ceramic capacitors with reduced thickness.
Implementation Method 1
a second step of firing a ceramic multilayer structure in which a plurality of multilayer units obtained in the first step are stacked, wherein an arithmetic average roughness Ra of at least a part of an internal electrode formed by sintering of the metal powder in the second step is 30 nm or less
Data Source
AI summary
A multilayer ceramic capacitor includes: a multilayer structure in which each of a plurality of dielectric layers and each of a plurality of internal electrode layers are alternately stacked, a main component of the dielectric layers being ceramic, a main component of the internal electrode layer being a metal, wherein an arithmetic average roughness Ra of at least a part of the internal electrode layer is 30 nm or less, wherein a maximum height Rz of the at least a part of the internal electrode layer is 360 nm or less.