Multilayer Capacitor Electrode Design for Low ESL and Controlled ESR
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Solution Overview
Problem
Multilayer ceramic capacitors face challenges in controlling equivalent series resistance (ESR) effectively, leading to impedance mismatching and reduced noise absorption effects, particularly at increased clock frequencies in ICs, which can cause malfunction due to distorted signal waveforms and reduced frequency band performance.
Innovation Solution
A multilayer capacitor design with a combination of low ESL and high ESR characteristics is achieved by varying the dimensions and configurations of internal and external electrodes, allowing for flexible control of resonance points and frequency characteristics through adjustments in electrode contact areas and layer numbers, thereby stabilizing the lamination state and enhancing ESR control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the current path is made wide and short to reduce ESL, then the ESR is reduced accordingly, but this causes impedance mismatching and ringing that distorts signal waveforms
Solution Approach 1:
The patent applies local quality by creating different current path configurations in different regions of the capacitor. Specifically, it uses multiple internal electrodes with different contact areas to external terminal electrodes, where some paths are optimized for low ESL (wider, shorter paths) and others provide higher ESR through narrower or longer paths. This local differentiation allows the capacitor to simultaneously achieve low overall ESL while maintaining appropriate ESR for signal integrity.
Solution Approach 2:
The patent employs composite materials by combining multiple electrode structures with different geometrical configurations within the same capacitor body. The internal electrodes are made with varying contact areas to external terminal electrodes, creating a composite structure that integrates both low-ESL and controlled-ESR characteristics in a single device, rather than requiring separate capacitors for each function.
2Quantity of substance
If the number of ceramic layers and internal electrodes is increased to increase capacitance, then the ESR is reduced, but this further decreases ESR below optimal levels for circuit impedance matching
Solution Approach 1:
The patent applies local quality by creating different current path configurations in different regions of the capacitor. Specifically, it uses multiple internal electrodes with different contact areas to external terminal electrodes, where some paths are optimized for low ESL (wider, shorter paths) and others provide higher ESR through narrower or longer paths. This local differentiation allows the capacitor to simultaneously achieve low overall ESL while maintaining appropriate ESR for signal integrity.
Solution Approach 2:
The patent employs parameter changes by systematically varying the contact areas of multiple internal electrodes to external terminal electrodes. By changing this geometric parameter across different electrode configurations, the patent achieves a distribution of ESR values that collectively provide optimal impedance matching. The number of internal electrodes and their respective contact areas are adjusted as design parameters to balance capacitance, ESL, and ESR requirements.
3Object-affected harmful factors
If the ESR becomes too low, then the noise absorption effect is improved, but the impedance frequency characteristic becomes too steep near resonance frequency, reducing anti-resonance point performance
Solution Approach 1:
The patent employs parameter changes by systematically varying the contact areas of multiple internal electrodes to external terminal electrodes. By changing this geometric parameter across different electrode configurations, the patent achieves a distribution of ESR values that collectively provide optimal impedance matching. The number of internal electrodes and their respective contact areas are adjusted as design parameters to balance capacitance, ESL, and ESR requirements.
Solution Approach 2:
The patent employs composite materials by combining multiple electrode structures with different geometrical configurations within the same capacitor body. The internal electrodes are made with varying contact areas to external terminal electrodes, creating a composite structure that integrates both low-ESL and controlled-ESR characteristics in a single device, rather than requiring separate capacitors for each function.
Data Source
AI summary
In a capacitor body, a single second capacitor unit is interposed between two first capacitor units. The width direction dimension of each of extended portions of first and second internal electrodes included in the first capacitor unit is larger than the width direction dimension of each of extended portions of third and fourth internal electrodes included in the second capacitor unit. The area of each of the respective portions of a first opposed portion of the first internal electrode and a second opposed portion of the second internal electrode, the respective portions being opposed to each other, is smaller than the area of each of respective portions of opposed portions of the third and fourth internal electrodes, the respective portions being opposed to each other. Thus, a multilayer capacitor has a characteristic that is a combination of a low-ESL characteristic of the first capacitor unit and a high-ESR characteristic of the second capacitor.