Copper External Electrode Structure for Crack-Resistant MLCCs
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Solution Overview
Problem
The use of fine metal powder in forming external electrodes for multilayer ceramic capacitors leads to a decrease in crystallite size, increasing internal stress and decreasing ductility, which can result in cracks and reduced reliability of the capacitors.
Innovation Solution
The multilayer electronic component includes an external electrode with metal crystallites of specific sizes, ranging from 70 nm to 100 nm, measured from the peak of a (111) plane obtained from an X-ray diffraction pattern, to optimize stress distribution and ductility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fine metal powder is used to form external electrodes, then the sintering temperature is lowered and capacitance per unit volume is improved, but the crystallite size decreases and reliability deteriorates
Solution Approach 1:
The patent applies parameter changes by carefully controlling the crystallite size of metal particles within a specific range (70-100 nm) to resolve the contradiction. This size control allows the external electrode to maintain both fine granularity for high capacitance and sufficient crystallite size for reliability, preventing the harmful effects of excessive fine-powder refinement while achieving improved capacitance per unit volume.
Solution Approach 2:
The patent applies local quality by differentiating the requirements for different regions of the external electrode. The terminal portion uses metal particles with crystallite size of 70-100 nm to ensure reliability and impact absorption, while other portions can use finer particles for high capacitance. This localized differentiation allows each region to optimize its properties for its specific function.
2Temperature
If fine metal powder is used, then the external electrode can be heat treated at low temperature, but the number of interfaces between crystallites increases and internal stress increases
Solution Approach 1:
The patent resolves this contradiction by establishing an optimal crystallite size range (70-100 nm) that balances the competing requirements. This parameter control allows low-temperature sintering to be achieved while maintaining a crystallite size large enough to limit the number of interfaces and reduce internal stress, preventing the electrode from becoming overly brittle.
Solution Approach 2:
The patent converts the potentially harmful effect of fine powder (increased interfaces and stress) into a benefit by precisely controlling the crystallite size. Instead of avoiding fine particles entirely, the invention utilizes particles in the 70-100 nm range that provide fine-granularity benefits while avoiding the harmful stress concentration that would occur with smaller crystallites.
3Length of moving object
If fine metal powder is used, then the external electrode size is reduced, but the ductility decreases and crack resistance worsens
Solution Approach 1:
The patent applies parameter changes by controlling the crystallite size parameter to fall within the 70-100 nm range. This specific parameter range allows the external electrode to maintain a compact size while preserving sufficient ductility and crack resistance, as the crystallites are large enough to effectively absorb external impacts without being so large as to increase the overall electrode dimensions.
Solution Approach 2:
The patent applies local quality by ensuring that the terminal portion of the external electrode, which is most susceptible to impact and cracking, has metal particles with crystallite size of 70-100 nm. This localized quality control in the critical impact zone provides enhanced ductility and crack resistance where it is most needed, while allowing other portions to be more compact.
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 approach enhances the reliability of the multilayer electronic component by effectively absorbing external impacts, preventing cracks, and maintaining the structural integrity of the capacitors.
Implementation Method 1
the metal included in the external electrode has crystallites having a size of 70 nm or more and 100 nm or less... effectively absorbing external impacts transmitted to the multilayer ceramic capacitor
Data Source
AI summary
Provided is a multilayer electronic component, the multilayer electronic component including: a body including a dielectric layer and internal electrodes alternately disposed with the dielectric layer; an external electrode disposed on the body and connected to the internal electrodes, wherein the external electrode includes a metal including Cu, wherein the metal included in the external electrode has crystallites having a size of 70 nm or more and 100 nm or less, measured from a peak of a plane obtained from an X-ray diffraction pattern.