Glass Feedthrough
Hermetic electrical feedthrough assemblies provide isolated conductor paths through pressure boundaries in sensor housings. A borosilicate glass-to-metal header utilizes glass preforms fused between alloy pins and an outer metallic body under elevated temperature cycles. The structural bond maintains mechanical integrity up to elevated pressures while isolating electrical signals.
Moisture ingress through the interface remains below detection thresholds when thermal expansion coefficients match closely across materials.
Thermal Expansion
Matched expansion characteristics between the borosilicate glass matrix and nickel-iron alloy conductors prevent stress cracking during manufacturing and thermal cycling. Differential expansion between metals and glass creates radial forces during cooling phases that seal micro-voids at the glass boundary. If temperatures exceed structural strain limits, structural micro-fractures develop that degrade insulation resistance.
Hermetic Isolation
Gas tight boundaries formed by fused glass resist chemical attack and mechanical deformation. Electrical pin isolation prevents current leakage between signal conductors and grounded instrument housings. Environmental conditions involving salt spray or industrial solvents do not degrade the inorganic glass surface, preserving measurement fidelity.
Pin Degradation
Surface oxidation on feedthrough pins during high-temperature glass melting can alter contact resistance if cleaning procedures fail. Metal oxide layers must maintain controlled thickness during processing to ensure consistent glass bonding. Corrosion of exposed pin surfaces in marine environments requires plated outer coatings to prevent conductive pathway formation.
