Product Overview

4J42 wire is a precision-controlled expansion alloy composed of iron and approximately 42% nickel. It is engineered to closely match the thermal expansion of borosilicate glass and other packaging materials, making it an ideal choice for hermetic sealing, electronic packaging, and aerospace applications.

Chemical Composition

• Nickel (Ni): ~42%

• Iron (Fe): Balance

• Minor elements: Mn, Si, C (trace amounts)

CTE (Coefficient of Thermal Expansion, 20–300°C): ~5.5–6.0 × 10⁻⁶ /°C
Density: ~8.1 g/cm³
Electrical Resistivity: ~0.75 μΩ·m
Tensile Strength: ≥ 430 MPa
Magnetic Properties: Soft magnetic, low coercivity

Specifications

• Diameter: 0.02 mm – 3.0 mm

• Surface: Bright, oxide-free

• Form: Spool, coil, cut-to-length

• Condition: Annealed or cold drawn

• Customization: Available on request

Key Features

• Matched thermal expansion for glass and ceramics

• Stable mechanical and magnetic properties

• Excellent vacuum compatibility

• Ideal for electronic sealing, relays, and sensor leads

• Low expansion with good ductility and weldability

Applications

• Glass-to-metal hermetic seals

• Semiconductor lead frames

• Electronic relay headers

• Infrared and vacuum sensors

• Communication devices and packaging

• Aerospace connectors and enclosures