Multilayer Ceramic Capacitor Asymmetric Outer Layers
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Solution Overview
Problem
Multilayer ceramic capacitors face cracks due to internal stress from the difference in thermal contraction coefficients between dielectric and conductive layers, which existing technologies fail to adequately address while maintaining sufficient electrostatic capacitance.
Innovation Solution
A multilayer ceramic capacitor design with a specific structure, including a body with dielectric and conductive layers stacked in a particular configuration, where the height of the inner layer portion is smaller than its width, and the outer layers have varying compositions and thicknesses to manage thermal stress, and the capacitors are mounted on substrates with lands that apply compressive stress to reduce delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the inner layer portion is made thick by increasing the number of layers to increase electrostatic capacitance, then the electrostatic capacitance is improved, but the internal stress from thermal contraction difference causes cracks at the boundary between inner and outer layer portions
Solution Approach 1:
The patent applies local quality by making the second outer layer portion thicker than the first outer layer portion. This asymmetric thickness distribution creates a stress-absorbing structure where the thicker second outer layer portion compensates for the internal stress generated by the thick inner layer portion during thermal contraction, preventing cracks while maintaining high capacitance
Solution Approach 2:
The patent employs asymmetry by designing the second outer layer portion with greater thickness than the first outer layer portion. This asymmetric configuration is specifically tailored to counterbalance the internal stress distribution pattern that arises from the thick inner layer portion, thereby preventing delamination and cracks during thermal cycling
2Shape
If the height of the body in stacking direction is made smaller than the width, then the aspect ratio is optimized for mounting, but the internal stress distribution becomes more complex requiring specific layer thickness control
Solution Approach 1:
The patent applies local quality by specifying different thickness requirements for different outer layer portions. The second outer layer portion is made thicker than the first outer layer portion, creating localized stress compensation zones that simplify the overall design by providing a straightforward thickness control rule rather than complex multi-parameter optimization
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
Significantly reduces or prevents cracks caused by internal stress while securing a sufficient electrostatic capacitance, enhancing the reliability and performance of the capacitors.
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 outer electrodes and the lands are positioned such that a compressive stress acts on the boundary between the inner layer portion and the outer layer portion
Data Source
AI summary
A body of a multilayer ceramic capacitor includes an inner layer portion and first and second outer layer portions sandwiching the inner layer portion therebetween. The inner layer portion includes an area extending from a conductive layer positioned closest to a first main surface to a conductive layer positioned closest to a second main surface in the stacking direction. The height of the body is smaller than the width of the body. The height of the inner layer portion is smaller than the width of the inner layer portion. The first outer layer portion includes a dielectric layer positioned closest to the first main surface. The second outer layer portion includes a dielectric layer positioned closest to the second main surface, and is thicker than the first outer layer portion. The total height of the first and second outer layer portions is smaller than the height of the inner layer portion.