Ferrule Tube Connector Welding for Implantable Pulse Generator Feedthroughs
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Solution Overview
Problem
Conventional implantable pulse generators for neurostimulation systems face challenges in securely and reliably connecting feedthrough wires to pins due to differences in melting temperatures and thermal diffusivity between platinum and MP35N materials, leading to incomplete bonding during welding processes.
Innovation Solution
The method involves using a ferrule tube connector with a slot to house the conductor, and employing surface features on the feedthrough pins to shield the conductor from direct laser exposure, ensuring proper alignment and bonding through conductive heating, and using adaptations like ribbon clamps to manage wire strands and apply compressive forces for successful welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional welding processes are used to connect feedthrough wires to pins, then the manufacturing process is simple, but incomplete bonding occurs due to differences in melting temperatures and thermal diffusivity between platinum and MP35N materials
Solution Approach 1:
The patent introduces an intermediary ferrule tube connector between the feedthrough pin and the conductor wire. This ferrule serves as a mediator that facilitates the welding process by providing a suitable bonding surface and protecting the conductor from direct laser exposure, thereby achieving complete bonding despite the different material properties of platinum and MP35N
Solution Approach 2:
The patent modifies the welding parameters by using a ferrule tube connector with specific geometric features (inner diameter, slots) that control the laser beam interaction. The ferrule's structure changes the thermal field distribution during welding, enabling complete bonding by controlling heat transfer to the conductor wire
2Productivity
If direct laser welding is applied to connect conductors to feedthrough pins, then welding efficiency is high, but conductor wire pull-away occurs due to thermal effects
Solution Approach 1:
The patent converts the harmful direct laser exposure that causes conductor pull-away into a beneficial controlled heating process. By using the ferrule tube connector with slots, the laser energy is directed to heat the ferrule material itself, which then facilitates bonding without causing the conductor wire to pull away. The harmful thermal effect is redirected to serve the bonding function
3Reliability
If platinum feedthrough pins are used, then electrical conductivity is excellent, but welding difficulty increases due to high melting temperature and low thermal diffusivity
Solution Approach 1:
The ferrule tube connector acts as an intermediary that bridges the gap between the platinum feedthrough pin and the MP35N conductor wire. It provides a suitable welding interface that accommodates the different thermal properties of the materials, enabling successful bonding without requiring the platinum itself to be directly welded to the conductor
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 enhances the manufacturing yield by preventing wire pulling away during welding, ensuring robust electrical connections and hermetic sealing of the implantable pulse generator components.
Implementation Method 1
employing surface features on the feedthrough pins to shield the conductor from direct laser exposure
Implementation Method 2
ensuring proper alignment and bonding through conductive heating
Implementation Method 3
performing welding operations to connect the plurality of conductors of the lead body with the ferrule tube connectors
Implementation Method 4
hermetically enclosing the pulse generating circuitry and switching circuitry within a housing
Data Source
AI summary
In one embodiment, a method of fabricating an implantable pulse generator, comprises: providing a lead body including a plurality of conductors; providing a feedthrough component comprising feedthrough pins; electrically coupling pulse generating circuitry through switching circuitry with the feedthrough pins; hermetically enclosing the pulse generating circuitry and switching circuitry within a housing; providing a ferrule tube connector about each feedthrough pin wherein (i) each ferrule tube connector comprises an inner diameter that is sized to make contact about a circumference of respective feedthrough pin, and (ii) each ferrule tube connector comprises at least one slot in an upper portion of the respective ferrule tube connector; placing a respective conductor of the plurality of conductors in the slot of each of the ferrule tube connectors; and performing welding operations to connect the plurality of conductors of the lead body with the ferrule tube connectors.