Filled-Glass Feedthrough Seal for Thermal Stress Matching
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Solution Overview
Problem
Existing feedthrough assemblies for implantable medical devices face challenges in achieving adjustable mechanical properties for the insulating materials used, which are crucial for ensuring reliable seals and reducing tensile stresses.
Innovation Solution
A feedthrough assembly is developed using a glass seal with single-phase particulates, specifically a filled glass composition comprising 25-40% B2O3, 0-25% CaO, 0-25% MgO, 0-10% La2O3, 5-15% SiO2, and 10-20% Al2O3, along with optional additions like Al2O3, Y2O3, and ZrO2, to enhance mechanical properties and reduce residual stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional glass seals are used in feedthrough assemblies, then the sealing function is achieved, but the mechanical properties cannot be adjusted to match specific application requirements
Solution Approach 1:
The patent applies composite materials by combining glass matrix with dispersed particulate phases (such as crystalline phases, glass ceramics, or other compatible materials) to create a filled glass composition. This composite structure enables independent optimization of mechanical properties (through particulate selection and distribution) while preserving the sealing functionality of the glass matrix, thus resolving the contradiction between adaptability and reliability.
Solution Approach 2:
The patent employs parameter changes by systematically varying the composition, size, shape, and distribution of particulate phases within the glass matrix. By adjusting these parameters, the mechanical properties (strength, toughness, thermal expansion) can be tuned to match specific application requirements while maintaining the hermetic sealing capability of the glass seal.
2Ease of manufacture
If insulating materials with fixed mechanical properties are used, then manufacturing is simplified, but tensile stresses cannot be effectively managed in the seal
Solution Approach 1:
The patent uses parameter changes by adjusting the particulate content, type, and distribution within the glass matrix to modify the mechanical properties of the seal material. This enables optimization of stress distribution and tensile strength to match the specific mechanical demands of the application, while the standardized composite formulation approach maintains manufacturing simplicity.
3Ease of manufacture
If conventional glass compositions are used, then the feedthrough assembly can be manufactured, but thermal expansion mismatch causes residual stress and potential failure
Solution Approach 1:
The patent applies parameter changes by selecting and adjusting the glass matrix composition and particulate phase characteristics to match the thermal expansion coefficient with surrounding materials (such as ferrules, insulators, or housing). This thermal expansion matching reduces residual stresses during temperature cycling while maintaining manufacturability through established composite processing techniques.
Solution Approach 2:
The patent uses composite materials to achieve thermal expansion matching by incorporating particulate phases with specific thermal properties into the glass matrix. The composite structure allows independent optimization of thermal expansion characteristics while maintaining the manufacturing advantages of glass-based seal materials.
Data Source
AI summary
A feedthrough assembly includes: a ferrule; an insulating structure; and a seal fixedly securing the insulating structure within the ferrule, the seal comprising a glass and single-phase particulate dispersed therein; wherein the glass includes: 25% to 40% B2O3; 0 to 25% CaO; 0 to 25% MgO; 0 to 25% SrO; 0 to 10% La2O3; 5% to 15% SiO2; and 10% to 20% Al2O3; wherein all percentages are mole percentages of the glass.