Multilayer Ceramic Capacitor Dummy Electrode Layers Warpage Crack Prevention
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Solution Overview
Problem
Multilayer ceramic electronic components face challenges in achieving high reliability due to warpage cracks, especially in high capacitance components, where methods like increasing the lead frame margin or using impact-absorbing materials are limited in effectiveness and cost, and may restrict mounting area and height.
Innovation Solution
Incorporating a plurality of dummy electrode layers in the cover layer of the ceramic body, positioned at the edges of external electrodes, with a specific thickness and number configuration to enhance bending strength and resistance to external impacts, where the number of dummy electrode layers is calculated as {(T×x)−(AL×AT)}/DT, with x ranging from 9.0% to 16.2%, and the layers being 40 μm or more in length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of stacked layers is increased to achieve high capacitance, then capacitance is improved, but the component becomes more susceptible to warpage cracks and reliability deteriorates
Solution Approach 1:
The patent divides the cover layer into multiple segments by stacking dummy electrode layers (non-capacitance formation parts) between the capacitance formation parts. This segmentation reinforces the cover layer structure, preventing warpage cracks while maintaining the high capacitance achieved through multiple stacked layers. The dummy electrode layers act as structural reinforcement segments distributed throughout the cover layer.
2Volume of moving object
If the thickness of the dielectric layer is reduced to enable miniaturization, then component size is improved, but the component becomes more susceptible to warpage cracks and reliability deteriorates
Solution Approach 1:
The patent creates a composite structure within the cover layer by combining capacitance formation parts (with internal electrodes) and non-capacitance formation parts (dummy electrode layers). This composite configuration provides structural reinforcement against warpage cracks while maintaining the reduced thickness and miniaturized size of the component. The dummy electrode layers serve as reinforcement elements within the composite cover layer structure.
3Reliability
If conventional methods such as using lead frames or impact-absorbing materials are applied to prevent warpage cracks, then reliability is improved, but manufacturing cost increases and mounting area is restricted
Solution Approach 1:
The patent makes the cover layer multi-functional by integrating both capacitance formation and structural reinforcement functions into a single component structure. The dummy electrode layers serve dual purposes: they provide structural reinforcement to prevent warpage cracks while also being part of the overall electrode system. This eliminates the need for separate lead frames or impact-absorbing materials, reducing manufacturing cost and mounting area requirements.
4Reliability
If the margin in length direction is increased to prevent warpage cracks, then reliability is improved, but capacitance decreases due to reduced active area
Solution Approach 1:
The patent shifts the reinforcement approach from the length direction (increasing margin) to the thickness direction (stacking dummy electrode layers). By placing non-capacitance formation parts within the cover layer thickness, the patent provides structural reinforcement without reducing the lengthwise active area of internal electrodes. This dimensional shift maintains capacitance while improving reliability against warpage cracks.
Data Source
AI summary
A multilayer ceramic capacitor may include: a ceramic body including dielectric layers; first and second internal electrodes disposed in the ceramic body; and first and second external electrodes formed to end surfaces of the ceramic body. The ceramic body may includes an active layer, a capacitance formation portion, and a cover layer, a non-capacitance formation portion, the cover layer includes a plurality of dummy electrode layers. When the number of the first and second internal electrodes is defined as AL, a thickness of each of the first and second internal electrodes is defined as AT, a thickness of each of the dummy electrode layers is defined as DT, and the number of the dummy electrode layers is defined as DL, DL is equal to {(T×x)−(AL×AT)}/DT, x being 9.0% or more.