Planar Solid Electrolytic Capacitor Layout for Low Inductance
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Solution Overview
Problem
Solid electrolytic capacitors struggle to perform at high frequencies and exhibit high inductance, limiting their effectiveness in decoupling and high-speed switching applications due to their inherent electrical properties.
Innovation Solution
A solid electrolytic capacitor design featuring a sintered anode body, a dielectric layer, and a conductive polymer solid electrolyte, which minimizes Equivalent Series Inductance (ESL) and Equivalent Series Resistance (ESR) across a wide range of frequencies and temperatures, enhancing decoupling performance and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solid electrolytic capacitors use conventional structures with metal lead wires pressed around the anode, then they achieve low ESR and reliable construction, but they exhibit high inductance that limits high-frequency performance
Solution Approach 1:
The capacitor is divided into multiple capacitor elements (first capacitor element and second capacitor element) with opposing polarities. Each element has its own anode body, dielectric, and solid electrolyte. This segmentation allows the inductance of each element to be minimized independently and enables the elements to be connected in parallel, reducing total inductance while maintaining construction reliability.
Solution Approach 2:
The capacitor elements are arranged in a planar configuration rather than a conventional vertical stacking. The first and second capacitor elements are positioned adjacent to each other in the same plane, with their cathode terminations connected through conductive polymer material. This dimensional arrangement reduces the loop area and associated inductance while maintaining reliable electrical connections.
2Device complexity
If solid electrolytic capacitors use conventional single-element designs, then they achieve simpler construction, but they cannot provide sufficient decoupling performance across broadband frequencies
Solution Approach 1:
Multiple capacitor elements with opposing polarities are merged into a single capacitor component. The first capacitor element has positive polarity and the second has negative polarity, and they are connected in parallel through their cathode terminations using conductive polymer material. This merging provides broadband decoupling performance while maintaining a single-component configuration that does not significantly increase device complexity.
Solution Approach 2:
The opposing polarity capacitor elements serve multiple functions simultaneously: they provide decoupling capacitance across a broad frequency range, reduce total inductance through parallel connection, and enable miniaturization by replacing multiple separate capacitors with a single multi-functional element.
3Quantity of substance
If solid electrolytic capacitors use traditional configurations, then they achieve adequate capacitance, but they require multiple capacitors to be spaced apart, preventing miniaturization
Solution Approach 1:
The second capacitor element is positioned adjacent to and partially overlapping with the first capacitor element in a planar arrangement. The cathode termination of the first element and the cathode termination of the second element are connected through conductive polymer material that acts as an interconnect. This nested arrangement allows both capacitor elements to occupy overlapping or adjacent spaces, reducing the overall footprint and enabling miniaturization while maintaining adequate total capacitance.
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 capacitor achieves low ESL and ESR values, enabling robust broadband decoupling, high-speed switching, and excellent DC power filtering capabilities, with improved performance under varying temperature and humidity conditions, replacing multiple lower capacitance capacitors and allowing for miniaturization.
Implementation Method 1
Conductive polymers are often employed as the solid electrolyte due to their advantageous low equivalent series resistance
Implementation Method 2
a dielectric that overlies the anode body, and a solid electrolyte that overlies the dielectric
Implementation Method 3
Solid electrolytic capacitors (e.g., tantalum capacitors) are typically made by pressing a metal powder (e.g., tantalum) around a metal lead wire, sintering the pressed part
Data Source
AI summary
A capacitor that is capable of exhibiting good electrical properties under a wide variety of different conditions is provided. The capacitor contains a capacitor element that includes a sintered porous anode body, a dielectric that overlies the anode body, and a solid electrolyte that overlies the dielectric and includes a conductive polymer. The capacitor also contains multiple exposed anode lead portions that are electrically connected to respective anode terminations and a planar cathode termination that is electrically connected to the solid electrolyte.