Implantable Pulse Generator Feedthrough Welding
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Solution Overview
Problem
Conventional methods for fabricating implantable pulse generators face challenges in creating reliable and hermetically sealed electrical connections between the pulse generator's internal circuitry and external leads, particularly due to differences in melting temperatures and thermal diffusivity of materials like platinum and MP35N, which can lead to incomplete welds and disconnections during the welding process.
Innovation Solution
The method involves using a feedthrough assembly with ferrule tube connectors and welding components that include a first portion engaging the feedthrough pins and a second portion engaging conductor wires, applying welding energy directly to these components to form a robust electrical connection, ensuring each feedthrough pin is welded to a ferrule tube connector and the conductor wire is securely attached within a slot, thereby establishing a reliable and hermetic connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional welding methods are used to connect feedthrough pins to conductor wires, then the manufacturing process is simple, but the reliability of electrical connection deteriorates due to incomplete welds and disconnections
Solution Approach 1:
A ferrule tube connector is introduced as an intermediary component between the feedthrough pin and the conductor wire. The ferrule receives both the pin and wire, providing a common interface for welding. This mediator resolves the material incompatibility issues by creating a controlled joint environment where reliable electrical and mechanical connections can be established despite differences in melting temperatures and thermal diffusivity between dissimilar materials.
2Manufacturing precision
If direct welding between dissimilar materials (platinum and MP35N) is performed, then the manufacturing process is straightforward, but the manufacturing precision deteriorates due to incomplete welds
Solution Approach 1:
The direct welding operation between dissimilar materials is segmented into two separate welding operations: first welding the feedthrough pin to the ferrule, then welding the conductor wire to the ferrule. This segmentation allows each welding operation to be optimized for its specific material pair, improving weld quality and manufacturing precision while managing the complexity through standardized connection geometry.
3Reliability
If hermetic sealing is implemented to prevent disconnections, then the reliability improves, but the device complexity increases due to additional sealing structures
Solution Approach 1:
The electrical connection function and hermetic sealing function are merged into a single integrated ferrule structure. The ferrule serves dual purposes: providing an electrical connection interface for welding the pin and wire, and simultaneously providing hermetic sealing when filled with sealing material. This merging eliminates the need for separate sealing structures, reducing overall device complexity while maintaining reliability.
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
This approach ensures a robust and hermetically sealed electrical connection between the pulse generator's circuitry and the lead body, enhancing the reliability and durability of the implantable pulse generator by preventing disconnections and improving the manufacturing yield, even under the mechanical stresses experienced in the body.
Implementation Method 1
performing one or more weld operations for each welding component to connect each welding component with a respective feedthrough pin and a respective conductor wire by applying a majority of welding energy directly to the welding components
Data Source
Figure 1~2C
Figure 3A~3E
Figure 4~7
AI summary
In one embodiment, a method of fabricating an implantable pulse generator, comprises: providing a lead body including a plurality of conductors, the plurality of conductors being enclosed in insulative material along a first length of the conductors, a second length of the conductors being exposed from the insulative material; providing a feedthrough component comprising a plurality of feedthrough pins; electrically coupling pulse generating circuitry through switching circuitry with the plurality of feedthrough pins; hermetically enclosing the pulse generating circuitry and switching circuitry within a housing, the feedthrough component being welded to the housing; laser machining each of the plurality of feedthrough pins to comprise a notch along a surface of the respective feedthrough pin; placing a respective conductor of the plurality of conductors in the slot of each of the plurality of feedthrough pins; and performing welding operations to connect the plurality of conductors of the lead body with the plurality of feedthrough pins of the feedthrough component.