Laminated Capacitor Mounting Structure for Power Supply Impedance Control
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Solution Overview
Problem
Existing methods for mounting laminated capacitors on wiring boards face challenges in maintaining power supply impedance within target values while minimizing the mounting area, as they struggle to accurately adjust Equivalent Series Resistance (ESR) and Equivalent Series Inductance (ESL) to prevent anti-resonance and reduce impedance across various frequency bands.
Innovation Solution
A mounted structure of laminated capacitors with a rectangular shape, featuring alternately laminated internal electrodes and dielectric layers, and external electrodes connected to power supply and ground patterns, where multiple capacitors with a quality factor less than 0.5 are connected in parallel to adjust ESR and ESL, ensuring that at least half of the power supply terminals are within a combined cover area, allowing for precise impedance control across different frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If multiple two-terminal capacitors are mounted to reduce ESL, then power supply impedance is reduced, but mounting area increases
Solution Approach 1:
The capacitor is divided into multiple capacitor units (first capacitor unit, second capacitor unit, etc.) that are connected in parallel within a single capacitor body. This segmentation allows the ESL to be reduced by having multiple low-ESL units in parallel, while the entire structure is mounted as a single component, thereby reducing the mounting area compared to using multiple separate two-terminal capacitors.
Solution Approach 2:
Multiple capacitor units are nested within a single capacitor body structure. The first capacitor unit, second capacitor unit, and other capacitor units are arranged in parallel within the same physical housing, creating a nested configuration that achieves the electrical benefits of multiple capacitors while occupying the space of only one mounted component.
2Manufacturing precision
If multiple capacitors are used to accurately adjust ESR and ESL, then impedance control precision is improved, but device complexity increases
Solution Approach 1:
Multiple capacitor units that would traditionally require separate components are merged into a single laminated capacitor body. The first capacitor unit, second capacitor unit, and other units are integrated within one component structure, achieving accurate impedance control through the combined effect of multiple units while reducing device complexity by mounting only one component.
Solution Approach 2:
The single laminated capacitor performs multiple functions that would otherwise require separate components: it provides ESL reduction through parallel-connected units, ESR adjustment through units with different resistance characteristics, and anti-resonance suppression. This multi-functionality within a single component achieves precise impedance control without increasing the number of mounted parts.
Data Source
AI summary
A wiring board is provided with power supply patterns for each type of power supply of an IC. An IC has a plurality of power supply terminals for each type of power supply. For each type of power supply, two or more laminated capacitors are provided in parallel between the power supply of IC and a ground. Two or more laminated capacitors provided for each type of power supply include a laminated capacitor having a Q factor of less than about 0.5. For each type of power supply, in order to satisfy a target impedance, two or more laminated capacitors are arranged and distributed such that at least half of the plurality of power supply terminals are included in a region obtained by combining cover areas.