Platinum Paste Filled Alumina Feedthrough Insulator for Hermetic Seal
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hermetic terminals and feedthroughs in implantable medical devices face challenges such as biocompatibility, resistance to degradation under bias current or voltage, and susceptibility to electromagnetic interference (EMI), which can lead to device malfunction and tissue damage, especially during MRI procedures. Additionally, the use of ceramic materials can result in brittle failures due to tensile stress, and the high cost and toxicity of platinum-based leadwires pose further issues.
Innovation Solution
A hermetic feedthrough design utilizing a monolithic alumina insulator substrate with a platinum conductive pathway, where the hermetic seal is achieved through intimate bonding of platinum within the alumina substrate, eliminating the need for braze materials and using a platinum paste with adjusted solids loading and sintering parameters to create a tortuous interface that tolerates stress and prevents fluid erosion, while also reducing the use of expensive noble metals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ceramic materials are used for hermetic terminals, then hermeticity and biocompatibility are improved, but brittleness and susceptibility to tensile stress failure worsen
Solution Approach 1:
The patent uses a composite structure combining alumina ceramic substrate with platinum conductive paste filled vias. The ceramic provides hermeticity and biocompatibility, while the metal paste and intimate bonding create a tortuous interface that tolerates stress and prevents brittle failure. This composite approach allows the system to benefit from both materials' strengths while mitigating their weaknesses.
2Reliability
If platinum-based leadwires are used, then electrical conductivity and biocompatibility are improved, but cost and toxicity concerns worsen
Solution Approach 1:
The patent replaces expensive platinum leadwires with a platinum paste filling method that uses significantly less noble metal. The conductive pathway is created through screen-printed or deposited paste that is sintered into the ceramic, reducing material cost while maintaining electrical conductivity and biocompatibility functions.
Solution Approach 2:
The patent changes the form and distribution of platinum from solid leadwires to a paste formulation with controlled solids loading. By adjusting paste composition, screen printing parameters, and sintering conditions, the invention achieves adequate conductivity with reduced platinum content, lowering cost while maintaining performance.
3Reliability
If braze materials are used for hermetic sealing, then sealing effectiveness is improved, but device complexity and manufacturing steps worsen
Solution Approach 1:
The patent merges the hermetic sealing function with the conductive pathway formation by filling the same via structure with conductive paste that serves both electrical and sealing purposes. The intimate bonding between the paste and ceramic wall creates hermetic seal without requiring separate braze materials or additional sealing steps, simplifying manufacturing.
Solution Approach 2:
The patent extracts the braze material function from the system by using the conductive paste itself to provide both electrical conductivity and hermetic sealing. This eliminates the need for separate braze materials and reduces manufacturing complexity while maintaining sealing effectiveness.
4Reliability
If high solids loading paste is used, then electrical conductivity is improved, but manufacturing precision and control worsen
Solution Approach 1:
The patent optimizes paste formulation parameters including solids loading, vehicle composition, and rheological properties to achieve adequate conductivity while maintaining manufacturability. By carefully controlling paste viscosity, particle size distribution, and organic binder content, the invention balances electrical performance with screen printing and filling process control.
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
The solution provides a sustainable hermetic seal that withstands thermal expansion mismatch and EMI, reduces the risk of device failure, and eliminates the need for costly platinum-based leadwires, ensuring reliable and long-lasting performance of implantable medical devices.
Implementation Method 1
pressing the ceramic body and the conductive paste
Implementation Method 2
sintering the ceramic body and the conductive paste together to form the feedthrough dielectric body
Implementation Method 3
hermetically sealing the feedthrough dielectric body to a ferrule
Data Source
AI summary
A method for manufacturing a singulated feedthrough insulator for a hermetic seal of an active implantable medical device (AIMD) is described. The method begins with forming a green-state ceramic bar with a via hole filled with a conductive paste. The green-state ceramic bar is dried to convert the paste to an electrically conductive material filling via hole and then subjected to a pressing step. Following pressing, a green-state insulator is singulated from the green-state ceramic bar. The singulated green-state insulator in next sintered to form an insulator that is sized and shaped for hermetically sealing to close a ferrule opening. The thusly produced feedthrough is suitable installation in an opening in the housing of an active implantable medical device.