Multilayer Ceramic Capacitor Void Distribution for Electrostriction Cracks
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Solution Overview
Problem
Conventional multilayer ceramic capacitors experience cracks due to electrostriction when high voltage is applied, leading to degradation in high-temperature load reliability and moisture resistance, as stress concentrates at the ends of the capacitor, making effective screening difficult.
Innovation Solution
The multilayer ceramic capacitor design includes dielectric layers with varying void distributions, where end portions have fewer voids than central portions, reducing electrostrictive stress concentration and improving sintering, thereby minimizing crack formation and increasing capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high voltage is applied to the multilayer ceramic capacitor, then the screening effectiveness is improved, but electrostriction occurs causing cracks in the dielectric layer
Solution Approach 1:
The patent applies local quality by creating a specific void distribution pattern within the dielectric layer. Voids are concentrated in the central region of the dielectric layer while the end regions (where electrostrictive stress concentrates during high voltage application) have fewer or no voids. This localized structural differentiation allows the dielectric layer to withstand high voltage screening tests without cracking at the stress concentration points, thus resolving the contradiction between screening effectiveness and dielectric strength.
2Ease of manufacture
If voids are present in the dielectric layer, then the manufacturing process is simplified, but mechanical strength decreases and crack formation is promoted
Solution Approach 1:
The patent resolves this contradiction by implementing local quality through spatially differentiated void distribution. The manufacturing process allows voids to form in the central region of the dielectric layer where they do not compromise mechanical strength, while the end regions are designed to be void-free or have minimal voids. This localized control maintains manufacturing simplicity while ensuring mechanical strength at critical stress concentration points.
Solution Approach 2:
The patent converts the potentially harmful effect of voids into a beneficial design feature. Instead of eliminating all voids (which would complicate manufacturing), the invention strategically positions voids in the central region where they can be tolerated, while ensuring void-free zones at the ends where mechanical strength is critical. This transforms the manufacturing challenge of void formation into a design opportunity for optimized stress distribution.
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
This design effectively reduces cracks caused by electrostriction, enhances mechanical strength, and increases capacitance by optimizing void distribution in dielectric layers, particularly at the ends of the capacitor.
Implementation Method 1
electrostriction occurs when a voltage is applied. The stress caused by the electrostriction concentrates at the ends in the length direction and the width direction of an effective portion of the multilayer ceramic capacitor
Data Source
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AI summary
[Problem] To provide a multilayer ceramic capacitor capable of suppressing occurrence of cracks generated inside a laminate due to electrostriction when a high voltage is applied. [Solution] A multilayer ceramic capacitor according to the present invention has: a laminate formed of an inner layer part that includes a plurality of laminated dielectric layers and a plurality of laminated internal electrode layers, that includes a first main surface and a second main surface facing each other in the height direction being the lamination direction of the plurality of dielectric layers, a first lateral surface and a second lateral surface facing each other in the width direction orthogonal to the height direction, and a first end surface and a second end surface facing each other in the length direction orthogonal to the height direction and the width direction, and that is obtained by alternately laminating the dielectric layers and the internal electrode layers, and an outer layer part disposed so as to sandwich the inner layer part from the first main surface side and the second main surface side; a first external electrode disposed on the first end surface; and a second external electrode disposed on the second end surface. The inner layer part is formed of inner dielectric layers among the plurality of dielectric layers disposed in the inner layer part. The inner dielectric layers contain voids. The inner dielectric layers have a width-direction center part-side dielectric layer disposed in a region of a center part in the width direction of the inner layer part, and a width-direction end part-side dielectric layer disposed in a region of an end part in the width direction of the inner layer part. The amount of voids contained in the width-direction end part-side dielectric layer is less than the amount of voids in the width-direction center part-side dielectric layer.