4J29 Kovar Alloy Specification
Glass-Sealing Fe-Ni-Co Alloy for Electronic Applications
Product Specification
| Standard | GB/T 15018 (China), ASTM F15 (USA), EN 1.3912 (Europe) |
| Material Designation | 4J29 (Fe-Ni-Co), Kovar, Ni29Co18 |
| Tolerance | h7-h11 (on request) |
| Melt Method | Vacuum Induction Melting (VIM) |
| Available Forms & Sizes | Strip: 0.05-3.0mm thick (≤300mm width) Wire: φ0.10mm – φ5.0mm Bar: 3-100mm diameter Custom profiles upon request |
Chemical Composition (wt%)
| Element | Min | Max |
| Nickel (Ni) | 28.5 | 29.5 |
| Cobalt (Co) | 16.8 | 17.8 |
| Iron (Fe) | Balance | |
| Manganese (Mn) | – | 0.50 |
| Silicon (Si) | – | 0.30 |
| Carbon (C) | – | 0.03 |
| Phosphorus (P) | – | 0.02 |
| Sulfur (S) | – | 0.02 |
Thermal Expansion Properties
| Temperature Range (°C) | Average CTE (×10⁻⁶/°C) | Matching Glass Types |
| 20 – 300 | 4.7 – 5.5 | Corning 7052, DM-308 |
| 20 – 400 | 5.8 – 6.6 | Corning 7056, 7040 |
| 20 – 450 | 6.2 – 7.0 | Alumina ceramics |
| 20 – 500 | 7.4 – 8.2 | Hard glasses |
Physical & Mechanical Properties
- Density: 8.17 g/cm³
- Melting Point: 1450°C
- Resistivity: 0.49 μΩ·m at 20°C
- Curie Temperature: 430°C
- Tensile Strength: 520-600 MPa
- Yield Strength: 380-450 MPa
- Elongation: ≥30%
- Hardness: 150-200 HV
- Thermal Conductivity: 17.0 W/(m·K) at 20°C
Applications
- Microelectronic packages and chip carriers
- Microwave and RF component housings
- Medical device hermetic seals (pacemakers, implants)
- Aerospace sensor housings and connectors
- High-power lamp bases and vacuum tube leads
- Laboratory equipment requiring glass-metal seals
Special Processing Notes
- Recommended heat treatment: 850°C±10°C water quench for optimal CTE
- Hydrogen firing at 1000°C for 15-30 minutes required for glass sealing applications
- Avoid nickel plating before glass sealing operations
- Store in dry, controlled environment to prevent surface oxidation
Document generated on 2026/1/29 | For reference purposes only
