Product Description
4J29 alloy sheet, also known internationally as Kovar alloy (UNS
K94610, ASTM F15), is a nickel-iron-cobalt alloy with controlled
thermal expansion characteristics. It is widely used in hermetic
sealing applications due to its precisely matched coefficient of
expansion with hard glass and ceramics.
The alloy maintains dimensional stability across a wide temperature
range, making it ideal for use in electronic components requiring
tight tolerances and vacuum integrity. Typical applications include
glass-to-metal seals in transistors, vacuum tubes, integrated
circuits, microwave packages, and optical housings.
Available in cold-rolled or annealed condition, 4J29 sheets offer
excellent workability, uniform grain structure, and high surface
finish for precision forming and sealing processes.
Key Features
Matched thermal expansion with borosilicate and aluminosilicate
glasses
Excellent hermeticity and vacuum sealing performance
Stable mechanical properties across temperature ranges
Easily machined, deep drawn, or stamped
Good oxidation resistance in air
Compliant with ASTM F15 and GB/T 14986 standards
Typical Applications
Hermetic glass-to-metal seals
Electronic packaging (IC, transistor, diode headers)
Microwave devices and optical components
Relay housings, vacuum tubes, and sensor shells
Aerospace and communication electronics
Chemical Composition (%)
| Element | Content (%) |
|---|
| Nickel (Ni) | 29.0 ± 1.0 |
| Cobalt (Co) | 17.0 ± 1.0 |
| Iron (Fe) | Balance |
| Silicon (Si) | ≤ 0.3 |
| Manganese (Mn) | ≤ 0.5 |
| Carbon (C) | ≤ 0.05 |
| Chromium (Cr) | ≤ 0.2 |
| Phosphorus (P) | ≤ 0.015 |
| Sulfur (S) | ≤ 0.015 |
| Aluminum (Al) | ≤ 0.1 |
| Copper (Cu) | ≤ 0.2 |
Mechanical Properties (Annealed)
| Property | Typical Value |
|---|
| Tensile Strength | ≥ 450 MPa |
| Yield Strength | ≥ 300 MPa |
| Elongation (L=50 mm) | ≥ 20% |
| Hardness (HV) | ≤ 200 HV |
| Density | 8.3 g/cm³ |
| Coefficient of Expansion | 5.0 × 10⁻⁶ /°C (30–400°C~) |
| Melting Range | 1450 – 1500°C |
| Electrical Resistivity | ~0.42 μΩ·m |
Available Specifications
| Item | Details |
|---|
| Thickness Range | 0.05 mm – 5.0 mm (custom sizes available) |
| Width | Up to 600 mm (slit widths available) |
| Length | Up to 3000 mm (or coils upon request) |
| Surface Finish | Bright, Cold-Rolled, Ground, or Annealed Matte |
| Tolerance | Thickness: ±0.01 mm; Width: ±0.5 mm (custom precision available) |
| Delivery Condition | Annealed / Stress Relieved / Pickled |
| Packaging | Vacuum sealed + export wooden case; rust-preventive wrap included |
| Certification | ISO 9001 / Material Certificate (EN 10204 3.1/3.2) / RoHS / REACH |
| Country of Origin | China (OEM support available) |
Optional Services:
Custom stamping or laser cutting
Surface cleaning for vacuum applications
Pre-punched or slotted formats
Cleanroom packaging
