Ferrule-Free Ceramic Feedthrough Brazing for Implantable Devices
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Solution Overview
Problem
Existing feedthrough devices for implantable medical devices face challenges in achieving a high-quality hermetic seal without using a ferrule, which can be damaged by laser welding and may lead to leaks and increased manufacturing complexity.
Innovation Solution
A method involving a braze preform placed between the insulator and case, where the insulator and case are preheated, and a laser is used to heat the case and insulator, causing the preform to melt and fill the narrow space between them, creating a hermetic seal without a ferrule, while avoiding direct laser energy on the preform to prevent spattering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If laser welding is used to join ferrule to case, then hermetic seal is achieved, but insulator is damaged due to temperature rise
Solution Approach 1:
A braze preform is introduced as an intermediary material between the ferrule and case. The preform melts during laser brazing to create a hermetic seal, while the laser energy is directed away from the insulator to prevent damage. This mediator enables the sealing function without exposing the insulator to harmful temperatures.
Solution Approach 2:
The harmful effect of laser-induced temperature rise on the insulator is extracted and eliminated by directing laser energy away from the insulator and toward the braze preform and metal components only, thereby achieving sealing without damaging the insulator.
2Reliability
If ferrule is used for hermetic sealing, then seal quality is improved, but device complexity increases
Solution Approach 1:
The sealing function is merged directly into the feedthrough assembly by brazing the ferrule to the case without requiring additional ferrule components. The braze preform integrates the sealing material into the assembly process, eliminating the need for separate ferrule installation steps and reducing overall device complexity.
3Productivity
If direct laser energy is applied to preform, then brazing speed increases, but spattering occurs reducing seal quality
Solution Approach 1:
Different regions of the assembly receive different laser energy treatment. The laser is directed specifically at the braze preform and metal components to enable rapid brazing, while the insulator region is protected from direct laser energy. This localized energy application achieves high brazing speed without causing spattering that would compromise seal quality.
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 method ensures a high-quality hermetic seal between the feedthrough assembly and the case, reducing the risk of damage to the insulator and simplifying the manufacturing process by eliminating the need for a ferrule, thereby enhancing the reliability and efficiency of the sealing process.
Implementation Method 1
The insulator is heated with a laser until the temperature of the adjacent preform is raised above its melting point
Implementation Method 2
the temperature of the adjacent preform is raised above its melting point such that it flows and fills the space between the insulator and the case
Implementation Method 3
The insulator and case are preheated, and a laser is used to heat the case and insulator
Data Source
Figure 1A~1B
Figure 2~3A
Figure 3B~3C
AI summary
The invention relates to an implantable medical device, comprising a feedthrough assembly comprising an insulator and a plurality of conducting elements extending therethrough. A case with an opening into which the feedthrough assembly is placed defines a narrow space therebetween and a braze material fills the narrow space, thereby hermetically sealing the feedthrough assembly to the case. According to the invention, one of the feedthrough assembly and the case comprise a feature configured to securely hold the braze and the implantable medical device does not include a ferrule.