Kovar Alloy in Ceramic to Metal Seals
Core matching material for hermetic ceramic-metal sealing, reliable solution for vacuum & electronic packaging
General Introduction
Why Kovar for Ceramic to Metal Seals?
Kovar is a Fe-Ni-Co low-expansion alloy, which has a thermal expansion coefficient highly matched with alumina ceramic. It is the most widely used metal material for ceramic-to-metal hermetic seals worldwide.
In ceramic-metal sealing structures, Kovar acts as the transition metal between ceramic and external components. It solves the cracking, air leakage and seal failure problems caused by thermal stress during high-temperature sealing and long-term service.
Our customized Kovar parts and finished seals have stable air tightness, excellent insulation and wide temperature adaptability, fully meeting industrial, aerospace and medical grade requirements.
Core Position
- Main body of ceramic-metal sealing assembly
- Connection carrier for wiring & installation
- Pressure & temperature resistant structural part
- Hermetic guarantee for vacuum environment
Working Principle of Matching Sealing
Thermal Expansion Matching
Kovar’s expansion curve is consistent with 95% alumina ceramic. No large thermal deformation during heating and cooling.
High Temperature Sealing
Adapt to high-temperature brazing process. Firm combination between Kovar and ceramic without peeling.
Hermetic Performance
Tight interface bonding. Ultra-low leak rate, long-term stable vacuum sealing effect.
Sealing Process Flow: Kovar blank processing → Surface treatment → Assemble with ceramic parts → High-temperature brazing → Performance testing → Finished ceramic to metal seal. The whole process relies on Kovar’s stable physical properties to ensure the overall structural strength and sealing reliability of the product.
Advantages of Kovar in Sealing Components
Anti-Crack
Effectively prevent ceramic cracking caused by thermal expansion difference, greatly improve product yield.
Excellent Seal
Leakage rate up to 1×10⁻⁹ Pa·m³/s, suitable for high vacuum and high precision equipment.
Easy Machining
Good cutting, stamping and welding performance, support complex customized structure design.
Long Service Life
Stable chemical property, anti-oxidation, adapt to harsh working environment for years.
Key Technical Parameters
| Parameter Item | Standard Value | Remark |
|---|---|---|
| Main Composition | Ni 28.5~29.5%, Co 16.8~17.8%, Fe Balance | International standard Kovar |
| Thermal Expansion Coefficient | (4.5~5.5)×10⁻⁶ /℃ (20~400℃) | Match 95% alumina ceramic |
| Working Temperature | -70℃ ~ 450℃ | Continuous working |
| Leak Rate of Finished Seal | ≤1×10⁻⁹ Pa·m³/s | Hermetic grade |
| Density | 8.3 g/cm³ | Physical property |
Main Product Types
Kovar Raw Materials
Provide Kovar rod, plate, tube, wire and sheet. Standard chemical composition, uniform texture, for secondary processing of sealing parts.
Kovar Precision Parts
Machined Kovar pins, bases, shells and connectors, matched for various ceramic to metal seal assemblies.
Standard Ceramic-Metal Seals
Mass-produced universal seals with Kovar framework, widely used for conventional electronic components.
Custom Sealing Assemblies
Custom design according to drawings & samples, special size, pin layout and structure for special equipment.
Application Scenarios
Aerospace
Aviation & satellite vacuum components
Semiconductor
Chip packaging & sensor bases
Medical Devices
Diagnostic & medical vacuum instruments
Vacuum Industry
Vacuum tubes, optical & vacuum equipment
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