Multilayer Ceramic Capacitor Stress Reduction via Layer Design
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Solution Overview
Problem
Multilayer ceramic capacitors face reliability issues due to cracks caused by internal stress from the difference in thermal shrinkage coefficients between ceramic dielectric layers and conductive layers, which can lead to reduced product reliability and manufacturing yield.
Innovation Solution
The design includes a multilayer ceramic capacitor with specific configurations such as inclined extension portions of conductive layers and varying dimensions of outer layer sections to reduce internal stress, using barium titanate and Si-containing ceramic dielectric layers with differing composition ratios and rare earth element content to manage thermal shrinkage, and a manufacturing process that applies pressure to ensure adhesion and prevent delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional ceramic dielectric materials are used, then manufacturing is simpler, but cracks occur due to large difference in thermal shrinkage coefficients between ceramic and conductive layers
Solution Approach 1:
The patent modifies the compositional parameters of the ceramic dielectric material by controlling SiO2 content (5-20 mass%) and BaTiO3 content (70-85 mass%), which changes the thermal shrinkage coefficient to be closer to that of the conductive layers, thereby reducing internal stress while maintaining manufacturability.
Solution Approach 2:
The patent uses a composite ceramic dielectric material containing multiple phases (BaTiO3, SiO2, and other oxides) with carefully controlled composition ratios, creating a composite structure that balances thermal expansion properties with dielectric performance and manufacturing feasibility.
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 cracks, enhancing the reliability and yield of multilayer ceramic capacitors by managing internal stress and maintaining electrostatic capacitance while minimizing size and material usage.
Implementation Method 1
an internal stress produced by the difference in the coefficients of thermal shrinkage between the ceramic dielectric layers and the conductive layers
Data Source
AI summary
A multilayer ceramic capacitor includes a body and first and second outer electrodes. The body includes a multilayer unit with ceramic dielectric layers and conductive layers alternately stacked on each other. The body is sectioned into a thickness-direction inner layer section that includes the multilayer unit and thickness-direction first and second outer layer sections that sandwich the thickness-direction inner layer section therebetween. A dimension of the thickness-direction second outer layer section is greater than a dimension of the thickness-direction first outer layer section. A conductive layer closest to a first principal surface and a conductive layer closest to a second principal surface are first and second outermost conductive layers, respectively. A curving amount of an extension portion of the second outermost conductive layer is greater than that of an extension portion of the first outermost conductive layer.