Monolithic Ceramic Capacitor High Stacking Density Crack Resistance
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Solution Overview
Problem
Monolithic ceramic capacitors with smaller sizes and higher capacities are prone to structural defects such as cracks and delamination during firing and thermal shocks, particularly when ceramic layers are thinner and stacked in larger numbers.
Innovation Solution
A monolithic ceramic capacitor design with a ceramic sintered body having a parallelepiped shape, featuring a high number of stacked ceramic layers (at least 232) and a high volume proportion of inner electrodes (at least 0.37), along with narrow side gap portions (≤40 μm), which enhances mechanical strength and resistance to thermal shocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of stacked inner electrodes is increased and the thickness of the dielectric layer is reduced to achieve larger electrostatic capacity in smaller size, then the electrostatic capacity is improved, but structural defects such as cracks and delamination are more likely to occur during firing and thermal shocks
Solution Approach 1:
The invention changes the geometric parameters of the inner electrodes, specifically making the width W larger than the thickness T (W > T), and controlling the thickness ratio between dielectric layer and inner electrode to be 0.05 ≤ thickness ratio ≤ 0.2. These parameter changes optimize the stress distribution during firing and thermal shock, preventing cracks while maintaining high capacity with many stacked layers (N ≥ 232).
Solution Approach 2:
The invention applies different dimensional characteristics to different parts of the inner electrode structure. The inner electrodes have width W and thickness T with W > T, creating an asymmetric local geometry that distributes mechanical stress more favorably during thermal processing, thereby preventing delamination and cracks while maintaining high electrostatic capacity.
2Volume of moving object
If ceramic layers are made thinner and stacked in larger numbers to reduce capacitor size, then the size is reduced and capacity is increased, but cracks are more likely to occur when thermal shocks are applied during soldering
Solution Approach 1:
The invention controls specific parameter ratios: the thickness ratio between dielectric layer and inner electrode (0.05 ≤ thickness ratio ≤ 0.2) and the dimensional relationship W > T for inner electrodes. These parameter changes enable the structure to withstand thermal shocks during soldering while achieving high stacking density (N ≥ 232 layers) for compact size.
Solution Approach 2:
The asymmetric inner electrode geometry (W > T) and controlled thickness ratios act as a preventive measure before thermal shock occurs. This structural design anticipates and cushions against the harmful effects of thermal expansion and contraction during soldering, preventing crack formation in advance.
Data Source
AI summary
A monolithic ceramic capacitor includes a ceramic sintered body including a plurality of stacked ceramic layers, and first and second inner electrodes alternately arranged inside the ceramic sintered body to oppose each other in a stacking direction of the ceramic layers with the ceramic layers interposed between the adjacent first and second inner electrodes. Among the ceramic layers, a number N of the ceramic layers disposed between the first inner electrodes and the second inner electrodes is at least 232. A proportion of volume occupied by the first and second inner electrodes in the ceramic sintered body is at least about 0.37. A size of each of side gap portions is about 40 μm or less.