Kovar,Rodar,UNS K94610,E FORU

### **Kovar® / Rodar® / UNS K94610** **Iron-Nickel-Cobalt Low Expansion Alloy for Precision Electronic Sealing

** --- #### **1. Overview

** **Rodar**, also known generically as **Kovar**, is a precision iron-nickel-cobalt alloy formulated to provide a thermal expansion characteristic that closely matches borosilicate glass and certain ceramic materials from room temperature up to 450°C. This controlled thermal expansion behavior is crucial for creating reliable, stress-free hermetic seals in electronic components, preventing cracking or failure during thermal cycling. Rodar is particularly valued for its consistent performance, excellent sealing characteristics, and proven reliability in critical electronic packaging applications. 

 --- #### 

**2. Chemical Composition (Weight %)

** The typical chemical composition of Rodar is outlined below. The balance is Iron (Fe). 

 | Element | Content (%) | Key Function | 

| :--- | :--- | :--- | 

| **Iron (Fe)** | Balance | Forms the primary matrix and foundation of the alloy system. | 

| **Nickel (Ni)** | 28.0 - 29.0 | Primary regulator of thermal expansion coefficient to match sealing glasses. | 

| **Cobalt (Co)** | 16.5 - 17.5 | Fine-tunes thermal expansion properties and enhances metallurgical stability. | 

| **Manganese (Mn)** | 0.20 - 0.40 | Serves as a deoxidizer and improves hot workability during manufacturing. | 

| **Silicon (Si)** | 0.15 max | Carefully controlled to ensure proper oxide formation for glass adhesion. | 

| **Carbon (C)** | 0.02 max | Minimized to prevent gas evolution during high-temperature sealing processes. | 

| **Aluminum (Al)** | 0.10 max | Controlled to maintain surface quality for optimal sealing performance. | 

| **Magnesium (Mg)** | 0.10 max | Enhances oxide layer characteristics for improved glass bonding. |

 | **Zirconium (Zr)** | 0.05 max | Improves high-temperature grain boundary stability. | 

| **Sulfur (S)** | 0.010 max | Kept at minimal levels to prevent hot shortness. | 

| **Phosphorus (P)** | 0.010 max | Minimized to maintain alloy ductility and workability. | 

 --- #### **3. Physical Properties** 

| Property | Value / Condition | 

| :--- | :--- | 

| **Density** | 8.35 g/cm³ (0.301 lb/in³) | 

| **Melting Point** | ~ 1450 °C (2640 °F) | 

| **Mean Coefficient of Thermal Expansion** | 20 - 300°C (68 - 572°F): **5.0 x 10⁻⁶/°C** (2.8 x 10⁻⁶/°F)
20 - 400°C (68 - 752°F): **5.2 x 10⁻⁶/°C** (2.9 x 10⁻⁶/°F)
20 - 450°C (68 - 842°F): **5.4 x 10⁻⁶/°C** (3.0 x 10⁻⁶/°F) | 

| **Thermal Conductivity** | 16.8 W/m·K (116 Btu·in/hr·ft²·°F) at 20°C (68°F) | 

| **Specific Heat Capacity** | 440 J/kg·K (0.105 Btu/lb·°F) at 20°C (68°F) | 

| **Electrical Resistivity** | 0.48 μΩ·m at 20°C (68°F) | 

| **Modulus of Elasticity (Young's Modulus)** | 137 GPa (19.9 x 10⁶ psi) at 20°C (68°F) | 

| **Curie Temperature** | ~ 430 °C (806 °F) | 

| **Magnetic Properties** | Ferromagnetic below Curie temperature | 

 --- #### **4. Mechanical Properties 

(Typical for Annealed Condition)** 

| Property | Value at Room Temperature | 

| :--- | :--- | 

| **Tensile Strength** | 510 MPa (74 ksi) | 

| **Yield Strength (0.2% Offset)** | 340 MPa (49 ksi) | 

| **Elongation (in 50 mm / 2 in)** | 32% | 

| **Reduction of Area** | 65% | 

| **Hardness (Rockwell B)** | 68 HRB | 

| **Vickers Hardness** | 130 HV | 

 --- #### **5. International Standards

** Rodar (Kovar) complies with the following international specifications: 

 *   **ASTM:**    

*   **F15:** Standard Specification for Iron-Nickel-Cobalt Sealing Alloy 

*   **AMS:**    

*   **AMS 7724:** Sheet, Strip, and Plate    

*   **AMS 7725:** Bar, Wire, and Rod 

*   **UNS:** K94610 

*   **ISO:**    

*   **ISO 9453:** Soft solder alloys (related sealing applications) 

*   **IEC:**    

*   **IEC 60068:** Environmental testing (for sealed components) 

*   **JIS:**    

*   **JIS C 2531:** Iron-nickel alloy for sealing use 

 --- #### **6. Product Applications

** Rodar is essential in applications requiring precise thermal expansion matching: 

 *   **Semiconductor Packaging:

**    *   Microprocessor and memory device packages    

*   Power semiconductor housings    

*   Sensor and MEMS packaging 

*   **Aerospace & Defense Systems:*

*    *   Hermetic connectors and feedthroughs    

*   Radar and communication system components    

*   Avionics control modules 

*   **Medical Device Manufacturing:

**    *   Implantable medical electronics    

*   Diagnostic equipment sensors    

*   Surgical instrument components 

*   **Telecommunications:

**    *   Fiber optic transceiver packages    

*   Base station electronic components    

*   Satellite communication hardware 

*   **Automotive Electronics:

**    *   Engine control modules   

 *   Sensor packages for harsh environments    

*   Power electronic components

 --- #### **7. Key Characteristics & Advantages

** *   **Precision Thermal Expansion Matching:

** CTE of 5.0-5.4 x 10⁻⁶/°C perfectly matches borosilicate glass and alumina ceramics 

*   **Exceptional Seal Integrity:** Creates reliable, long-lasting hermetic seals resistant to thermal cycling 

*   **Excellent Mechanical Stability:** Maintains dimensional stability under thermal stress 

*   **Superior Surface Characteristics:** Optimized for oxide layer formation essential for glass bonding 

*   **Good Electrical Conductivity:** Suitable for applications requiring electrical feedthroughs 

*   **Excellent Manufacturing Properties:** Can be easily deep-drawn, stamped, and machined to precise tolerances 

*   **Proven Field Reliability:** Decades of successful application in critical electronic systems 

*   **Consistent Batch-to-Batch Performance:** Tight compositional control ensures reproducible results

 --- **Disclaimer:

** *Kovar® and Rodar® are registered trademarks. The values provided are typical and for informational purposes only. For critical applications, always consult the official material data sheets from the supplier and relevant design codes. Successful implementation requires proper surface preparation, controlled oxidation, and appropriate sealing parameters.*

Packing of Kovar,Rodar,UNS K94610

 Standard Packing:

 Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and steel drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 1680 gallon liquid totes Special package is available on request.