Feedthrough Array Ferrule Flanges for Hermetic IMD Sealing
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Solution Overview
Problem
Implantable medical devices (IMDs) are susceptible to electromagnetic interference (EMI) that can disrupt their function, and existing feedthrough arrays may compromise the hermeticity of the IMD housing during assembly and welding processes, leading to potential cracks in ceramic insulators.
Innovation Solution
A feedthrough array design featuring a ferrule with inwardly extending flanges for enhanced mechanical rigidity and a braze assembly with a ceramic insulator positioned at a controlled distance from the weld zone to prevent cracking, along with a capacitive filter to shunt EMI, and a method for manufacturing that includes gold sputtering to reduce oxide formation and contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the ceramic insulator is positioned close to the ferrule for compact assembly, then the device complexity is reduced, but the ceramic insulator is susceptible to cracking during welding due to thermal stress
Solution Approach 1:
The patent positions the ceramic insulator at a predetermined distance from the weld zone before welding occurs. This preliminary positioning prevents thermal stress from reaching the ceramic insulator during the welding process, eliminating the risk of cracking while maintaining a relatively compact overall assembly configuration.
2Ease of manufacture
If the ferrule is made thin-walled for easier manufacturing, then the ease of manufacture is improved, but the mechanical rigidity and structural integrity are compromised
Solution Approach 1:
The patent adds flanges extending radially outward from the ferrule wall, transforming the structure from a simple thin-walled tube to a dimensionally enhanced component. These flanges increase the moment of inertia and provide additional structural support, enabling the ferrule to maintain mechanical rigidity while keeping the main wall thickness minimal for ease of manufacture.
3Device complexity
If conventional feedthrough arrays are used without modified ferrule design, then the device complexity is reduced, but EMI filtering effectiveness is compromised due to poor capacitive filter coupling
Solution Approach 1:
The patent creates localized regions of enhanced electrical coupling between the capacitive filter and ferrule through the flange structures. The flanges provide dedicated contact areas with improved surface area and conductivity, ensuring effective EMI filtering at critical locations without requiring a complete redesign of the entire feedthrough array structure.
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 the structural integrity of the feedthrough array, reduces the likelihood of ceramic insulator cracking during welding, and improves the filtering efficiency by maintaining hermeticity and reducing insertion loss.
Implementation Method 1
capacitive filter arrays have been incorporated in the feedthrough arrays to filter each of the feedthroughs, shunting EMI at the entrance to the IMD
Implementation Method 2
a method for manufacturing that includes gold sputtering to reduce oxide formation and contact resistance
Data Source
AI summary
A feedthrough array for use in an implantable medical device is provided including an insulator, a plurality of conductive feedthrough pins extending through the insulator, and a ferrule including a flange extending inwardly from a ferrule sidewall along at least a majority of a length of a first ferrule side. A capacitor is disposed over the insulator and conductively coupled to the ferrule flange.