Multilayer Ceramic Capacitor Electrode Design for Gap Reduction
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Solution Overview
Problem
In multilayer ceramic capacitors, the conductor resistance at the connection points between internal electrode layers and external electrodes is high, leading to decreased capacitor performance and non-uniform dielectric characteristics due to sintering shrinkage differences between dielectric and conductive materials, resulting in gaps that can allow moisture intrusion and reliability issues.
Innovation Solution
The use of a multilayer ceramic capacitor design where internal electrode layers include a connection electrode portion with a higher melting point material ratio, matching the sintering behavior of the dielectric layers, and an internal electrode portion with a conductive material, reducing conductor resistance and eliminating gaps between dielectric and internal electrode layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive paste layer is formed on green sheets and laminated to prepare the stacked body, then the internal electrode layers are connected to external electrodes, but gaps are formed between dielectric layers and internal electrode layers due to different sintering shrinkage behaviors, causing plating solution or moisture intrusion and deteriorating insulating property
Solution Approach 1:
The patent applies local quality by creating a semiconductor portion of the dielectric at the periphery of the ends of internal electrodes, where it differs in electrical properties from the bulk dielectric. This localized modification prevents gap formation at critical interfaces without altering the overall dielectric characteristics, thereby maintaining insulating property while eliminating moisture intrusion paths
Solution Approach 2:
The patent changes the electrical parameter (conductivity) of the dielectric material locally by creating a semiconductor portion through controlled doping or compositional modification. This parameter change allows the peripheral region to better match the sintering shrinkage behavior of adjacent metal layers, preventing gap formation and improving reliability
2Reliability
If the semiconductor portion of the dielectric is disposed between internal electrode layers and external electrode to structurally separate them, then moisture intrusion is prevented, but conductor resistance of connection portion increases and capacitor performance decreases
Solution Approach 1:
The patent carefully controls the spatial extent of the semiconductor portion, limiting it to the periphery of the internal electrode ends. This localized approach provides moisture barrier functionality at the interface while maintaining low conductor resistance in the central connection path, thus preventing both moisture intrusion and excessive resistance
Solution Approach 2:
The patent creates a composite structure where the dielectric layer contains both insulating bulk material and localized semiconductor regions. This composite approach combines the moisture-blocking properties of semiconductor material with the low-resistance properties of conductive metal electrodes, achieving both reliability and performance
3Manufacturing precision
If the dielectric layer is made into a semiconductor through firing temperature or atmosphere control, then gap formation is reduced, but management of the process becomes difficult and dielectric characteristics become non-uniform
Solution Approach 1:
The patent applies local quality by creating semiconductor portions only at specific locations (periphery of internal electrode ends) through targeted compositional design or localized doping, rather than converting the entire dielectric layer to semiconductor. This approach reduces gap formation at critical interfaces while maintaining uniform insulating characteristics throughout the bulk dielectric, avoiding the need for complex process control
4Reliability
If the semiconductor portion range is increased to prevent gap formation, then reliability improves, but dielectric characteristics of the entirety of the capacitor deteriorate and become non-uniform
Solution Approach 1:
The patent optimizes the extent of semiconductor portions to be confined to the periphery of internal electrode ends, providing gap prevention exactly where needed at the interfaces. The bulk dielectric maintains its uniform insulating characteristics, ensuring stable capacitor performance while preventing moisture intrusion and gap formation at critical locations
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 design reduces conductor resistance and maintains uniform dielectric characteristics, preventing moisture intrusion and enhancing the reliability and performance of the multilayer ceramic capacitors by ensuring a continuous conductive path and strong coupling between internal electrode and dielectric layers.
Implementation Method 1
a ceramic powder that is a dielectric, and a metal powder of silver (Ag) or the like that is a conductive material of the internal electrode layer have sintering shrinkage behaviors different from each other
Implementation Method 2
the connection electrode portion containing a first conductive material and a material having a melting point higher than that of the first conductive material
Data Source
AI summary
There is provided a multilayer ceramic capacitor in which an increase in conductor resistance at an end of an internal electrode layer is suppressed, and in which a gap between the internal electrode layer and a dielectric layer is reduced. A multilayer ceramic capacitor includes a stacked body including dielectric layers and internal electrode layers alternately laminated; and an external electrode disposed on an end surface of the stacked body and connected to the internal electrode layers, the internal electrode layers each including a connection electrode portion connected to the external electrode, and an internal electrode portion which is connected to the connection electrode portion and extends toward an inner side of the stacked body, a ratio of a material having a melting point higher than that of a conductive material being higher in the connection electrode portion than in the internal electrode portion.