Laser-Bonded Feedthrough Assembly for Hermetic Sealing
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Solution Overview
Problem
Existing hermetically sealed enclosures for implantable medical devices face challenges in maintaining stable electrical coupling between internal and external components, particularly due to high temperature requirements for bonding corrosion-resistant materials, which can lead to material stress and limited conductor count within the lead body.
Innovation Solution
A hermetically sealed package with a feedthrough assembly that includes a non-conductive substrate and conductive material within a via, where the external contact is laser-bonded to the substrate, eliminating the need for ferrules and high-temperature brazing, and allowing for low-stress assembly and internal metallization for electronic device integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high temperature brazing is used to join corrosion-resistant conductive materials with corrosion-resistant insulative materials, then hermetic seal reliability is improved, but material stress and assembly complexity increase
Solution Approach 1:
The patent changes the temperature parameter from high-temperature brazing to low-temperature laser bonding. The laser bonding process operates at significantly lower temperatures than traditional brazing, thereby joining the corrosion-resistant conductive material (e.g., tungsten, platinum, or iridium) and corrosion-resistant insulative material (e.g., alumina or zirconia) without inducing excessive thermal stress in the materials.
Solution Approach 2:
The patent replaces the mechanical/thermal brazing process with a laser-based bonding process. Instead of using high-temperature heat sources and fluxes typical of brazing, the invention uses focused laser energy to create localized bonds between the conductive material and insulative material, eliminating the need for corrosive fluxes and reducing overall thermal exposure.
2Reliability
If traditional ferrule-based feedthrough assemblies are used, then electrical connection is achieved, but the number of conductors that can be integrated is limited
Solution Approach 1:
The patent merges multiple separate components (ferrule, insulator, conductor) into an integrated feedthrough assembly where the conductive material is directly bonded to the insulative material. This integration eliminates the need for separate ferrules and allows multiple conductors to be arranged in a compact configuration within the lead body, increasing the effective conductor count while maintaining connection stability.
Solution Approach 2:
The patent transitions from a radial arrangement of conductors in traditional ferrule-based assemblies to a more efficient spatial arrangement enabled by direct laser bonding. The conductive traces can be routed in two-dimensional patterns on the insulative material surface, allowing multiple conductors to be packed more densely and efficiently within the same volume.
3Reliability
If high temperature processing is used to create hermetic seals, then seal integrity is improved, but conductor stability and material integrity deteriorate
Solution Approach 1:
The patent changes the thermal processing parameters from high-temperature prolonged heating to low-temperature rapid laser bonding. The laser bonding process achieves hermetic seal integrity through localized, rapid heating that creates strong bonds without subjecting the conductive materials to prolonged high-temperature exposure that would cause drift or degradation.
Solution Approach 2:
The patent uses rapid laser bonding to quickly achieve hermetic sealing without lingering in the high-temperature regime. The laser energy is delivered in a concentrated, time-efficient manner that creates the necessary bonds and seals before thermal diffusion can cause conductor instability or material degradation.
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 solution provides a stable, low-stress electrical pathway from the external environment to internal devices, reducing the number of conductors needed within the lead body while protecting electronic components from external factors, and enabling the integration of multiple electrodes and multiplexing circuits within a compact form factor.
Implementation Method 1
The external contact is hermetically sealed to the outer surface of the non-conductive substrate by a laser bond surrounding the via
Data Source
AI summary
Various embodiments of a hermetically-sealed package and methods of forming such packages are disclosed. In one or more embodiments, the hermetically-sealed package can include a housing and a feedthrough assembly that forms a part of the housing. The feedthrough assembly can include a non-conductive substrate and a feedthrough. The feedthrough can include a via from an outer surface to an inner surface of the non-conductive substrate, a conductive material disposed in the via, and an external contact disposed over the via on the outer surface of the non-conductive substrate. The external contact can be electrically coupled to the conductive material disposed in the via. Further, the external contact can be hermetically sealed to the outer surface of the non-conductive substrate by a laser bond surrounding the via.