Feedthrough Manufacturing via Diffusion Welding and Laser Machining
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Solution Overview
Problem
Conventional methods for manufacturing feedthroughs for human implantable medical devices face challenges such as titanium oxidation, complex multi-step processes, limited materials for brazing, and difficulties in ceramic metallizing due to small hole sizes, which affect hermetic sealing reliability and biological compatibility.
Innovation Solution
A method using dual diffusion welding and laser machining to form a feedthrough body, eliminating the need for flux and filler metals, and utilizing capillary phenomena to simplify the process and enhance hermetic sealing, while avoiding the oxidation of titanium and reducing impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional brazing methods are used to manufacture feedthrough, then hermetic sealing can be achieved, but titanium oxidation occurs which decreases reliability and complicates the process
Solution Approach 1:
The patent removes the harmful flux material from the brazing process entirely, extracting the oxidation prevention function to a separate inert gas atmosphere control step. This eliminates the need for flux coating and removal operations, simplifying the process while maintaining hermetic sealing reliability through direct brazing in controlled atmosphere.
Solution Approach 2:
The patent employs an inert gas atmosphere (argon or nitrogen) throughout the brazing process to prevent titanium oxidation. By controlling the gas environment in the brazing chamber, the method eliminates oxidation issues without requiring flux, thereby improving reliability while reducing process complexity compared to conventional flux-based methods.
2Reliability
If multi-step brazing with flux coating is used, then hermetic sealing is achieved, but the process becomes very complicated with multiple steps
Solution Approach 1:
The patent extracts and eliminates the flux coating step from the manufacturing process. By using inert gas atmosphere control instead, the method achieves hermetic sealing without requiring the complex multi-step sequence of flux application, brazing, and flux removal, thereby improving ease of manufacture while maintaining sealing reliability.
Solution Approach 2:
The patent merges the oxidation prevention function (normally achieved through flux) with the inert gas atmosphere control. This consolidation eliminates the need for separate flux coating and removal steps, combining multiple functions into a single controlled atmosphere brazing process that is simpler to manufacture while achieving the same hermetic sealing result.
3Strength
If ceramic metallizing with MoMn paste is used, then welding of ceramic with platinum/iridium pin is achieved, but the small hole size makes metallizing difficult
Solution Approach 1:
The patent replaces the complex MoMn paste metallizing process with a simple platinum/iridium pin insertion method. The pin itself serves as the welding element, eliminating the need for difficult metallizing operations in small holes. This approach prioritizes ease of manufacture while achieving sufficient weld strength through direct mechanical and thermal bonding.
Solution Approach 2:
The patent replaces the chemical metallizing process (MoMn paste application and firing) with a direct mechanical insertion and diffusion bonding process. By inserting the platinum/iridium pin directly into the ceramic hole and bonding through diffusion welding in controlled atmosphere, the method achieves strong ceramic-pin joints without the difficulty of metallizing small holes, improving ease of manufacture.
4Reliability
If diffusion welding with nail head feedthrough pin is used, then hermetic sealing is achieved, but the nail head is hard to manufacture via forging or casting
Solution Approach 1:
The patent extracts and eliminates the complex nail head feature from the feedthrough pin design. By using a simple cylindrical pin geometry without protruding heads, the method maintains hermetic sealing through diffusion bonding while dramatically improving ease of manufacture. The simplified pin shape can be easily produced through standard machining or drawing processes without requiring complex forging or casting operations.
Solution Approach 2:
Instead of creating a complex nail head shape that protrudes from the pin, the patent inverts the approach by using a simple cylindrical pin that fits into the ceramic hole. The hermetic sealing is achieved through the diffusion-bonded interface between the pin surface and ceramic wall, eliminating the need for shaped heads and simplifying manufacturing while maintaining sealing 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 enhances reproducibility and productivity by simplifying the manufacturing process, improving the strength of the weld, and reducing impurities, resulting in more reliable and biocompatible feedthroughs with improved hermetic sealing and reduced complexity.
Implementation Method 1
a laser is irradiated to the ceramic structure into which the platinum/iridium pin is inserted, to form a hole in the ceramic structure
Implementation Method 2
A melted platinum/iridium pin moves toward an upper side of the ceramic structure through the hole of the ceramic structure, so that the platinum/iridium pin is partially exposed through the upper side of the ceramic structure
Implementation Method 3
for diffusion welding the ceramic structure of the feedthrough structure, the platinum/iridium pin and the titanium flange with each other
Data Source
AI summary
A method of manufacturing a feedthrough having an enhanced hermetic sealing and used for a human implantable medical device such as a deep brain stimulator, a implantable AED, a implantable spinal cord stimulator and so on. Thus, more enhanced reproducibility and productivity in the diffusion welding and the laser hole machining may be guaranteed in the present method of manufacturing the feedthrough, compared to the conventional method using the ceramic metallizing and the brazing.