Multilayer Ceramic Capacitor Cover Layers for Delamination Control
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Solution Overview
Problem
Multilayer ceramic capacitors face issues with increased curvature due to printing saddles, leading to degraded insulating properties and risk of delamination, as the capacity density increases, and the anchor effect is compromised, especially with high stacking densities and large-sized capacitors.
Innovation Solution
A ceramic electronic device with a multilayer structure featuring a specific curvature ratio (Q = (A+B)/2C×100% between 0.5% and 1.6%) is achieved by adjusting the non-permeable volume portion and dilution rate in the screen-printing process, ensuring optimal adhesion and insulating properties through controlled porosity and reduced printing saddle effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the capacity density and stacking density of multilayer ceramic capacitors are increased, then the size and capacity of the capacitors are improved, but the curvature of the interface between cover layers increases due to printing saddles, leading to degraded insulating properties and delamination risk
Solution Approach 1:
The patent applies parameter changes by precisely controlling the curvature ratio Q (defined as (A+B)/2C×100%) within the range of 0.5% to 1.6%, where A and B are heights of curvature portions and C is the shortest height from first to second cover layer. This quantitative parameter control resolves the contradiction by maintaining optimal interface geometry that prevents delamination while accommodating high capacity density requirements.
Solution Approach 2:
The patent applies local quality by creating a controlled curvature distribution at the interface between the first and second cover layers. Specifically, the interface is designed to have curvature portions with heights A and B at both ends, creating a localized geometric feature that manages stress distribution. This local geometric control ensures reliable adhesion at critical interface regions while maintaining overall high stacking density.
2Productivity
If the stacking density is increased to achieve larger capacity, then the anchor effect is compromised due to increased curvature, leading to delamination risk
Solution Approach 1:
The patent resolves this contradiction by establishing a specific parameter range for the curvature ratio Q (0.5% to 1.6%). This quantitative control of interface geometry ensures that the anchor effect is maintained even at high stacking densities. The parameter optimization balances the competing requirements of high density and strong adhesion.
Solution Approach 2:
The patent intentionally introduces controlled curvature at the interface between cover layers, using the curvature ratio Q as a design parameter. Rather than eliminating curvature, the invention optimizes it to specific ranges, transforming the potentially harmful printing saddle effect into a controlled geometric feature that actually enhances adhesion by distributing stress more effectively across the interface.
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 reduces delamination risks and maintains excellent insulating properties by balancing the curvature ratio, enhancing the reliability and performance of multilayer ceramic capacitors across varying sizes and densities.
Implementation Method 1
forming a plurality of stack units by screen-printing each of internal electrode patterns including metal powder on each of dielectric green sheets including ceramic powder
Implementation Method 2
forming a first cover layer from the first cover sheet and a second cover layer from the second cover sheet by firing the ceramic multilayer structure
Data Source
AI summary
A ceramic electronic device includes a multilayer structure having a substantially rectangular parallelepiped shape, a first cover layer, and a second cover layer that is provided on a second end of the multilayer structure in the stacking direction, a main component of the second cover layer being ceramic, a porosity of the second cover layer being higher than that of the first cover layer. Q=(A+B)/2C×100(%) is 0.5% or more and 1.6% or less, when, at an interface of the second cover layer on a side of the first cover layer, two heights of curvature portions of both ends of the interface are respectively a height A and a height B, and a shortest height from the first cover layer to the second cover layer is a height C.