MLCC Side Margin Magnesium Tuning for Interface Void Reduction
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Solution Overview
Problem
Miniaturization and high capacitance requirements in multilayer ceramic capacitors lead to increased voids at the interface between the ceramic body and side margin portions, reducing reliability by lowering breakdown voltage and moisture resistance, and decreasing bonding strength.
Innovation Solution
A multilayer ceramic capacitor design with a ceramic body featuring internal electrodes exposed to opposing surfaces, integrated side margin portions, and cover portions with different dielectric compositions, where the side margin portions have a higher magnesium content than the cover portions, formed by laminating ceramic green sheets and firing to reduce interface junctions and enhance reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the internal electrode is exposed in the width direction to increase effective electrode area, then capacitance is improved, but voids are generated at the interface between ceramic body and side margin portion, reducing reliability
Solution Approach 1:
The patent changes the magnesium content parameter in the side margin portion dielectric composition (higher Mg content than cover portions) to improve sintered density and reduce voids at the interface, thereby resolving the reliability issue while maintaining the exposed electrode design for high capacitance
Solution Approach 2:
The patent uses composite dielectric materials with different compositions in different regions: the side margin portion has a dielectric composition with higher magnesium content while cover portions have different compositions, creating a composite structure that optimizes both capacitance and interface reliability
2Ease of manufacture
If voids are generated at the interface between ceramic body and side margin portion, then manufacturing is simplified, but breakdown voltage is lowered due to electric field concentration
Solution Approach 1:
By adjusting the magnesium content parameter in the side margin portion dielectric to be higher than in cover portions, the patent reduces void formation and improves outer sintered density, thereby preventing electric field concentration and maintaining high breakdown voltage while preserving the ease of marginless manufacturing
3Ease of manufacture
If voids are generated at the interface between ceramic body and side margin portion, then manufacturing process is simplified, but moisture resistance reliability is decreased
Solution Approach 1:
The patent changes the dielectric composition parameter by increasing magnesium content in the side margin portion, which improves outer sintered density and reduces voids, thereby enhancing moisture resistance reliability while maintaining the simplified manufacturing process
4Adaptability or versatility
If side margin portion is attached separately to complete the capacitor, then manufacturing flexibility is improved, but bonding strength is decreased due to interface junction
Solution Approach 1:
The patent merges the side margin portion with the cover portions to form an integrated outer structure, eliminating the separate attachment process and its associated interface junctions, thereby improving bonding strength while maintaining manufacturing flexibility through the integrated green sheet lamination process
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
The design improves capacitance and reliability by reducing voids, increasing breakdown voltage, and enhancing moisture resistance through the integration of side margin portions and cover portions with distinct dielectric compositions, thereby addressing the challenges of miniaturization and high capacitance.
Implementation Method 1
a plurality of internal electrodes are disposed inside the ceramic body to overlap each other with the dielectric layer interposed therebetween to form capacitance
Implementation Method 2
The cut ceramic green sheet laminated body is fired to provide a ceramic body including an active portion having a dielectric layer
Data Source
AI summary
A multilayer ceramic capacitor includes a ceramic body including a dielectric layer, a plurality of internal electrodes disposed inside the ceramic body and each exposed to first and second surfaces of the ceramic body and to one of the third and fourth surfaces, and a first side margin portion and a second side margin portion disposed on sides of the plurality of internal electrodes exposed to the first and second surfaces. The ceramic body includes an active portion including the plurality of internal electrodes disposed to overlap each other with the dielectric layer interposed therebetween to form capacitance, an upper cover portion disposed above the active portion, and a lower cover portion disposed below the active portion. The first and second side margin portions have a dielectric composition different from a dielectric composition of one of the upper cover portion and the lower cover portion.