Multilayer Ceramic Capacitor Internal Electrode Grain Control
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Solution Overview
Problem
The reduction in thickness of dielectric and internal electrode layers in multilayer ceramic capacitors to achieve downsizing leads to a decrease in the continuity modulus and strength of the internal electrode, making it prone to cracking during mechanical shock due to excessive sintering and spheroidization of metal components.
Innovation Solution
A multilayer ceramic capacitor design with a high existence rate of crystal grains in the internal electrode layer, where the crystal grain diameter is small and the co-material is ceramic, is achieved through a manufacturing method involving a metal conductive paste with a sharp grain size distribution and controlled sintering conditions, ensuring a high continuity modulus and strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the thickness of dielectric layers and internal electrodes is reduced to achieve downsizing, then the chip size is reduced, but the internal electrode strength decreases and cracks may occur during mounting
Solution Approach 1:
The patent changes the grain size distribution parameters of the metal powder, specifically using an average grain diameter of 100 nm or less with a standard deviation of 1.5 or less. This parameter change prevents excessive sintering and spheroidization during the sintering process, maintaining the continuity modulus and strength of the internal electrode even when the layer thickness is reduced for downsizing.
Solution Approach 2:
The patent uses a composite metal powder composition with a main component (average grain diameter 100 nm or less) and co-material (average grain diameter 10 nm or less). This composite structure creates a dual-grain-size system where the fine co-material fills gaps and restricts grain growth of the main component during sintering, preventing spheroidization and maintaining electrode integrity at reduced thicknesses.
2Volume of moving object
If the thickness of internal electrodes is reduced, then the chip size is reduced, but the continuity modulus of the internal electrode decreases making it prone to breaking
Solution Approach 1:
The patent严格控制 the grain size distribution parameters (standard deviation ≤ 1.5) to prevent excessive sintering. This parameter control maintains the continuity modulus by preventing the metal grains from spheroidizing and separating during the sintering process, ensuring reliable electrical connectivity even in thinned internal electrodes.
Solution Approach 2:
The fine co-material particles (average grain diameter 10 nm or less) act as intermediaries that fill the spaces between main component grains and restrict their movement and spheroidization during sintering. This intermediary effect maintains the continuity of the internal electrode structure and prevents cracking.
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 approach enhances the strength and continuity modulus of the internal electrode, reducing the likelihood of cracking and maintaining the desired mechanical properties even at reduced thicknesses, thereby ensuring the reliability of the multilayer ceramic capacitors.
Implementation Method 1
a second step of baking a ceramic multilayer structure obtained by stacking a plurality of layer units obtained by the first step
Data Source
AI summary
A multilayer ceramic capacitor includes: a multilayer structure in which each of dielectric layers and each of internal electrode layers are alternately stacked, a main component of the dielectric layers being ceramic, a main component of the internal electrode layers being a metal, wherein: an existence rate of crystal grains satisfying b/a<1 of crystal grains included in the internal electrode layer is 70% or more, when a thickness of the internal electrode layer is “a” and a length of crystal grains of a main component metal of the internal electrode layer in an extension direction of the internal electrode layer is “b”; and the internal electrode layer includes a grain of which a main component is ceramic.