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%