Product Name:
Glass-Sealing Alloy Wire 4J28 | Fe-Ni Alloy Wire | Soft Magnetic
Material
Material:
4J28 (Fe-Ni Alloy, Kovar-type Glass-Sealing Alloy)
Specifications:
Available in various diameters (0.02 mm to 3.0 mm), lengths
customizable
Applications:
Glass-to-metal sealing, electronic tubes, sensors, vacuum
components, and other precision electronic devices
Surface Treatment:
Bright surface, oxide-free, annealed or cold-drawn
Packaging:
Coil/Spool form, plastic wrapping, vacuum-sealed bag or customized
packaging upon request
Product Description:
4J28 alloy wire, also known as Fe-Ni alloy wire, is a precision
soft magnetic and glass-sealing material. With a composition
primarily consisting of iron and approximately 28% nickel, it
provides exceptional thermal expansion matching with borosilicate
glass, making it widely used in electronic packaging and
glass-to-metal sealing applications.
4J28 wire exhibits excellent sealing properties, stable magnetic
performance, and reliable mechanical characteristics. It is
extensively used in electronic tubes, hermetic packaging,
semiconductor housings, and high-reliability aerospace and military
components.
Features:
Excellent Glass-to-Metal Sealing: Ideal thermal expansion
compatibility with borosilicate glass for tight, hermetic seals
Good Magnetic Properties: Suitable for soft magnetic applications
and stable magnetic response
High Dimensional Precision: Available in ultra-fine diameters,
precision-drawn for sensitive electronic components
Oxidation Resistance: Bright surface, oxidation-free, suitable for
vacuum and high-reliability sealing
Customizable: Dimensions, packaging, and surface conditions can be
tailored to specific customer needs
Applications:
Electronic tubes and vacuum devices
Glass-to-metal sealed relays and sensors
Semiconductor and hermetic packages
Aerospace and military-grade electronic components
Optical and microwave components requiring precise thermal
expansion matching
Technical Parameters:
Chemical Composition:
Ni: 28.0 ± 1.0%
Co: ≤ 0.3%
Mn: ≤ 0.3%
Si: ≤ 0.3%
C: ≤ 0.03%
S, P: ≤ 0.02% each
Fe: Balance
Density: ~8.2 g/cm³
Thermal Expansion Coefficient (30–300°C): ~5.0 × 10⁻⁶ /°C
Melting Point: Approx. 1450°C
Electrical Resistivity: ~0.45 μΩ·m
Magnetic Permeability (μ): High at low magnetic field intensities
Tensile Strength: ≥ 450 MPa
Elongation: ≥ 25%
Packaging & Shipping:
Packaging:
Plastic spools, vacuum bags, anti-rust wrapping, and customized
labels upon request
Shipping Methods:
Air freight, sea freight, express delivery
Lead Time:
7–15 working days based on order quantity
