Welded Feedthrough for Implantable Devices
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Solution Overview
Problem
Existing feedthrough devices for implantable medical devices face challenges in achieving a long-lasting, hermetic seal due to difficulties in metallizing conducting wires within ceramic insulation elements, leading to potential leaks over time, especially when using expensive procedures like soldering or brazing.
Innovation Solution
A method involving a two-part laser welding process where a first laser gradually heats the ceramic insulator to a controlled temperature range (1,300 to 1,600 degrees Centigrade) to minimize thermal shock, followed by a second laser for welding the ferrule to the insulator without using braze or solder, ensuring a hermetic seal without compromising the integrity of the ceramic material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conducting wires are introduced into ceramic insulation element without gaps, then hermetic sealing is achieved, but metallization of internal surface becomes difficult to apply
Solution Approach 1:
The patent replaces traditional mechanical metallization methods (spray coating, dip coating, electrodeposition) with a chemical vapor deposition (CVD) process. The CVD process uses chemical reactions to deposit metal layers uniformly on the internal surface of the bore hole, overcoming the difficulty of applying metallization to complex geometries without requiring direct mechanical contact or line-of-sight access.
Solution Approach 2:
The patent changes the metallization process parameters by using CVD conditions (temperature, pressure, gas composition) to achieve uniform metal deposition on the internal surface. By controlling the CVD process parameters, the patent achieves homogeneous metallization that adheres well to the ceramic surface, enabling reliable soldering of conducting wires while maintaining hermetic sealing.
2Duration of action of moving object
If expensive procedures like soldering or brazing are used to connect wires to insulation element, then long-lasting connection is achieved, but risk of leaks over time increases
Solution Approach 1:
The patent replaces thermal joining processes (soldering and brazing) with a mechanical press-fit connection. The conducting wires are directly inserted into the metallized bore hole and secured through interference fit and adhesive bonding, eliminating the need for high-temperature thermal processes that can create stress concentrations and potential leak paths in the ceramic material.
Solution Approach 2:
The patent introduces a metallization layer as an intermediary between the ceramic insulation element and the conducting wires. This metallization layer serves as both the bonding surface for the wires and the conductive path, eliminating the need for separate soldering or brazing operations that could compromise the hermetic seal.
3Reliability
If homogeneous metallization of internal surface is ensured, then reliable wire connection is achieved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive manual or multi-step metallization processes with a single-step chemical vapor deposition process. The CVD process automatically achieves homogeneous metallization of the internal surface through chemical reactions, eliminating the need for multiple coating steps, manual application, or expensive equipment required for traditional metallization methods.
Solution Approach 2:
The patent optimizes CVD process parameters (temperature, pressure, gas flow rates, deposition time) to achieve uniform metal thickness and composition throughout the bore hole. By carefully controlling these parameters, the patent achieves reliable wire connections with a cost-effective single-step process rather than multiple expensive metallization steps.
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 reduces the risk of leaks and maintains hermeticity by minimizing thermal shock and eliminating the need for braze or solder, thereby enhancing the reliability and longevity of the feedthrough device's electrical connection.
Implementation Method 1
A first laser is used to heat an insulator to a controlled temperature range (1,300 to 1,600 degrees Centigrade) to minimize thermal shock
Implementation Method 2
A second laser is used for welding a ferrule to the insulator
Data Source
AI summary
One aspect is a feedthrough for a medical implantable device including a ferrule having a metal that is configured to be welded to a case of the implantable device. The ferrule substantially surrounds an insulator and shares an interface therewith, the insulator having a glass or ceramic material. Conductive elements are formed through the insulator providing an electrically conductive path through the insulator. There is no braze or solder at the interface between the ferrule and the insulator and that there is no braze or solder adjacent the conductive elements.