Implantable Electrolytic Capacitor Shell for Heat and Cracking Control
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Solution Overview
Problem
High voltage capacitors used in implanted medical devices face challenges with high energy density requirements, leading to increased manufacturing complexity, cracking, and heat build-up due to tight tolerances and thin pockets, which affect reliability and yield.
Innovation Solution
A capacitor design with a capacitor stack enclosed by a first and second cover portion, utilizing molybdic acid etching for increased anode surface area, simplified geometries, and automated manufacturing processes to reduce cracking and heat issues, ensuring a neutrally charged output without additional circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thin pockets of PEEK are utilized for protection of the stacked electrolytic capacitor, then protection is provided, but manufacturing complexity increases and cracking risk increases
Solution Approach 1:
The capacitor is divided into multiple stacked layers (anode, cathode, electrolytic paper) that can be manufactured and assembled separately. This segmentation allows for simplified individual component manufacturing while providing protection through the layered structure itself, reducing the need for complex external protective elements like thin PEEK pockets.
Solution Approach 2:
The capacitor layers are nested within a boot structure that provides protection. The boot encapsulates the capacitor stack, providing mechanical protection and electrical isolation without requiring additional thin protective pockets. This nesting approach simplifies manufacturing by integrating protection into the capacitor structure itself.
2Quantity of substance
If higher packaging efficiency is achieved through improved surface area creation, then energy density increases, but tolerances on case/lid configurations and boot geometries must be tighter
Solution Approach 1:
The invention changes the geometric parameters of the capacitor components, specifically using arcuate transitions instead of sharp corners and optimized angular relationships (45-60 degrees). These parameter changes allow for improved packaging efficiency and energy density while maintaining relaxed manufacturing tolerances, as the curved geometries are more tolerant to dimensional variations than sharp-edged configurations.
3Quantity of substance
If lower tolerances are implemented, then packaging efficiency improves, but reliability decreases and yield decreases
Solution Approach 1:
The invention applies curvature to the capacitor component geometries, using arcuate transitions at corners and optimized angular relationships. These curved geometries provide improved packaging efficiency while being inherently more robust to manufacturing tolerances, thereby maintaining reliability and yield. The curved surfaces distribute stress more evenly and are less sensitive to dimensional variations than sharp-cornered designs.
4Volume of moving object
If the capacitor is made smaller for IMD application, then device size is minimized, but heat build-up and deformation increase due to internal resistance
Solution Approach 1:
The arcuate transitions and curved geometries in the capacitor design improve heat distribution and reduce stress concentration, allowing for compact sizing while minimizing heat build-up. The curved surfaces provide better thermal pathways and reduce localized heating that would occur at sharp corners and edges.
Solution Approach 2:
The optimized angular parameters (45-60 degrees) and arcuate transitions change the thermal and mechanical characteristics of the capacitor, enabling compact design while maintaining acceptable temperature levels. These parameter changes improve heat dissipation pathways and reduce internal stress that would lead to deformation.
5Strength
If complex manufacturing processes are used, then protection is improved, but cost increases and manufacturing time increases
Solution Approach 1:
The capacitor is segmented into standardizable layers that can be manufactured using conventional processes and assembled through straightforward stacking. This segmentation enables protection through the layered structure itself rather than requiring complex protective processes, reducing both cost and manufacturing time while maintaining adequate protection.
Solution Approach 2:
The boot structure nested around the capacitor stack provides protection through a simple encapsulation process rather than complex manufacturing steps. The nesting approach allows for cost-effective production using conventional molding and assembly processes while providing adequate mechanical and electrical protection.
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 design enhances manufacturing efficiency, reduces costs, and improves reliability by minimizing cracking and heat build-up, while maintaining high energy density and compact size for implanted medical devices.
Implementation Method 1
utilizing molybdic acid etching for increased anode surface area
Data Source
AI summary
A capacitor is provided that includes a capacitor stack including an anode layer, cathode layer, and electrolytic layer electrically coupled together, the capacitor stack including a capacitor stack periphery. The capacitor also includes a first cover portion having a first cover portion periphery that aligns with the capacitor stack periphery, and a second cover portion having a second cover portion periphery that aligns with the capacitor stack periphery and received the first cover portion periphery to form a shell body for encasing the capacitor stack therein. The capacitor stack is isolated from the second cover portion to provide a neutrally charged second cover portion that is electrically coupled within an implanted medical device.