Laminated Ceramic Capacitor Terminal Electrodes ESL Reduction
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Solution Overview
Problem
Miniaturization of laminated ceramic capacitors increases the risk of short-circuit failure and limits the reduction of ESL due to reduced terminal electrode width, making it difficult to achieve low ESL and high-frequency characteristics while maintaining manufacturing yield and reliability.
Innovation Solution
The design incorporates terminal electrodes with a connecting portion and a spreading portion, where the spreading portion has a wider width than the connecting portion, allowing for reduced ESL and increased spacing between electrodes to prevent short-circuit failures, and ensuring sufficient solder adhesion and stress dispersion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the capacitor body is miniaturized to meet market demand, then the size of the capacitor is reduced, but the width of terminal electrodes is reduced which increases ESL and deteriorates high-frequency characteristics
Solution Approach 1:
The terminal electrode transitions from a simple rectangular prism shape to an hourglass shape with varying cross-sectional area along its length. The first end portion has a larger cross-sectional area than the second end portion, creating a dimensional variation that reduces ESL while maintaining compact overall size. This dimensional change allows the electrode to function effectively in miniaturized capacitors.
Solution Approach 2:
Different portions of the terminal electrode are given different cross-sectional areas to optimize local functions. The first end portion (near the internal electrode) has a larger area to reduce ESL and improve high-frequency characteristics, while the second end portion (external terminal) has a smaller area to maintain compact size and proper spacing with adjacent electrodes. This local differentiation resolves the contradiction between miniaturization and high-frequency performance.
2Reliability
If the electrode width of terminal electrodes is increased to reduce ESL, then ESL is reduced, but it becomes difficult to ensure sufficient space for formation of terminal electrodes on the side faces of miniaturized body
Solution Approach 1:
The terminal electrode utilizes variation in the third dimension (length along the electrode) to achieve larger effective area for ESL reduction, rather than increasing area in the two-dimensional plane of the side face. The hourglass shape allows the electrode to have sufficient cross-sectional area at the first end portion while maintaining compact overall dimensions that fit within the miniaturized capacitor body.
Solution Approach 2:
The terminal electrode's cross-sectional area is locally optimized: the first end portion has a larger area to reduce ESL, while the second end portion has a smaller area to accommodate spatial constraints on the side face. This local differentiation allows ESL reduction without compromising the available space for multiple terminal electrodes on the miniaturized body.
3Area of stationary object
If sufficient space is ensured for formation of terminal electrodes, then terminal electrodes can be formed, but the distance between adjacent terminal electrodes decreases which increases risk of short-circuit failure
Solution Approach 1:
The terminal electrode has a smaller cross-sectional area at the second end portion (external terminal) compared to the first end portion. This local reduction in size at the critical external terminal region increases the distance between adjacent terminal electrodes, thereby reducing the risk of short-circuit failure during electroplating and in final operation, while the larger first end portion maintains effective ESL performance.
4Reliability
If the terminal electrode width is increased to reduce ESL, then high-frequency characteristics are improved, but manufacturing yield decreases due to increased risk of short-circuit failure
Solution Approach 1:
The terminal electrode employs an hourglass shape with different cross-sectional areas at different ends. The first end portion has a larger area to achieve low ESL and excellent high-frequency characteristics, while the second end portion has a smaller area to prevent short-circuit failure during electroplating. This local differentiation simultaneously achieves high-frequency performance and manufacturing reliability, resolving the contradiction between manufacturing yield and high-frequency characteristics.
Data Source
AI summary
A laminated ceramic capacitor includes a body having an inner layer portion and an outer layer portion and a plurality of terminal electrodes spaced apart from each other in a length direction of the body. The inner layer portion has a plurality of internal electrodes stacked in a height direction of the body. The internal electrodes have led-out portions led out to a side face of the body. The outer layer portion is disposed on one of opposite faces of the inner layer portion in the height direction. The terminal electrodes are each provided with a connecting portion and a spreading portion. The connecting portion extends along the height direction to cover corresponding one of the led-out portions. The spreading portion has a width gradually increasing from one of opposite ends of the connecting portion in the height direction toward an edge of the side face.