Multilayer Ceramic Capacitor Gradient Si Ti Composition
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Solution Overview
Problem
Multilayer ceramic capacitors face cracking issues due to internal stress caused by the difference in thermal contraction coefficients between dielectric and conductive layers, which existing technologies fail to adequately address.
Innovation Solution
The design incorporates a multilayer ceramic capacitor with a specific composition ratio of Si to Ti in the dielectric layers and a boundary region with a higher Si content, where the outer portion clamps the inner portion via deformed portions, reducing internal stress and preventing cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the multilayer ceramic capacitor uses conventional dielectric layers with uniform composition, then the manufacturing process is simple, but internal stress occurs due to thermal contraction coefficient differences causing cracks
Solution Approach 1:
The dielectric layer is divided into three regions with different Si/Ti composition ratios: the first outer layer portion has a higher Si/Ti ratio than the inner layer portion, the second outer layer portion has an even higher Si/Ti ratio than the first outer layer portion, creating a gradient structure that locally optimizes thermal contraction properties to match conductive layers and reduce internal stress
Solution Approach 2:
The dielectric layer is constructed as a composite structure with multiple portions having different chemical compositions (varying Si/Ti ratios), combining the benefits of each composition region to simultaneously reduce internal stress and maintain electrical performance
2Reliability
If the dielectric layer composition is optimized to reduce internal stress, then crack occurrence is prevented, but the manufacturing precision requirements increase
Solution Approach 1:
By creating distinct regions with different Si/Ti ratios, the patent allows each region to be optimized independently for its specific function (stress reduction vs. electrical performance), making the overall composition control more manageable than attempting to optimize a uniform structure
Solution Approach 2:
The dielectric layer is segmented into multiple portions along the stacking direction, each with controlled composition characteristics, allowing progressive optimization of stress distribution while maintaining manufacturing feasibility through staged composition control
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 configuration significantly reduces or prevents cracking by effectively managing internal stress, enhancing the reliability and durability of the capacitor.
Implementation Method 1
an internal stress is produced due to the difference in the coefficient of thermal contraction between dielectric layers and conductive layers
Implementation Method 2
The boundary region includes a portion which inclines toward the first main surface as the boundary region gets closer to one of the end surfaces or the side surfaces
Data Source
AI summary
A multilayer ceramic capacitor includes a body and at least two outer electrodes. The body includes first and second main surfaces, an inner layer portion and first and second outer layer portions. In the inner layer portion, dielectric layers and conductive layers are alternately stacked on each other. The second outer layer portion includes an outer portion and an inner portion. A boundary region adjacent to the inner portion in the outer portion inclines toward the first main surface.