Kovar ®
KOVAR Alloy Materials for Uniform Thermal Expansion
KOVAR ® (ASTM F15) is an alloy of nominally 53% iron, 29% nickel, and 17% cobalt produced with very tight composition controls that assure precise and uniform thermal expansion and mechanical properties.
This low and very uniform thermal expansion enables the material to be used in glass-to-metal seals in electronic components which have final usage in all major industries. With characteristics similar to hard glass, KOVAR ® is widely used in the electronics industry for these electronic packaging applications requiring hermetic seals.
What you need to know about buying KOVAR materials:
- Produced to ASTM F15, KOVAR ® material can be provided in wire, rod, bar, strip, and sheet format.
- It is important to provide the temper designation that is required as defined in ASTM F15 from annealed to full hard (can be Tempers “A” through “E”).
- Deep drawing tempers are available when requested.
- Surface finish can be as hot rolled, as forged, centerless ground, polished, cold rolled, and as drawn (for wire).
Product Selection and Purchasing Options for KOVAR
Beyond KOVAR ®, Leading Edge offers a wide range of products in multiple shapes and sizes, even in small quantities. Many are available for immediate shipment from our warehouse. If we don’t have the specialty material you need, there’s a good chance we can find it. With our flexible purchasing options, you can ensure materials are available when they’re needed. Purchasing options include blanket orders, just-in-time delivery, and consignment materials.
Industry Standards and Requirements
Industries constantly evolve, driven by a growing demand for scientific and technological advancement. Successful experimentation must ensure material integrity, safety, performance, and compliance with strict environmental and operational regulations.
These standards typically focus on aspects like purity, quality, and durability to guarantee that refractory metals meet the demanding conditions of high-stakes research applications. Because they serve multiple industries and extreme environments, this list includes more than average standards and requirements.
Standards and Requirements:
- ASTM International (American Society of Mechanical Engineers): Standards for materials used in energy applications.
- SAE Aerospace Material Specifications (AMS, formerly known as the Society of Automotive Engineers or SAE)
- ASME BPVC (Boiler and Pressure Vessel Code): Guidelines for materials used in pressure vessels and reactors.
- Department of Defense (DoD) Military Standards or Military Specifications (MIL) on the Defense Logistics Agency (DLA) ASSIST Database
We adhere to quality compliance certification standards and statutory regulations that pertain to our exotic materials, processes, custom machining services, traceability, and other aspects of our in-house expertise. Our materials specialists provide expert counsel on metal selection and inspection to ensure you receive materials that meet or exceed your expectations.
Leading Edge Metals & Alloys Certifications include:
- ISO9001:2015 and AS9100D Registered
- ITAR Registered
- NIST SP 800-171 and CMMC Complian
Our deep understanding of this industry stems from our extensive experience, skilled metallurgy professionals, and a history of successful partnerships with leading national research labs.
FAQs About KOVAR
Customers should share sealing material type (glass or ceramic), operating temperature range, thermal cycling conditions, fabrication method, and compliance requirements. These inputs help ensure correct temper, finish, and specification alignment.
Yes. LEMA supplies machined KOVAR® components, near-net shapes, and cut-to-size blanks, supporting prototypes, low-volume production, and specialized electronic applications.
Both alloys offer controlled thermal expansion, but KOVAR® is optimized for matching glass and ceramics, while INVAR® 36 is selected for minimal expansion in precision mechanical structures. Selection depends on whether sealing or dimensional stability is the primary requirement.
Surface finish is critical for sealing applications. Oxidation, contamination, or improper surface condition can compromise glass-to-metal bonds. Customers should specify surface finish requirements when parts will be sealed or brazed.
Yes. KOVAR can be welded and brazed using appropriate procedures. Welding parameters and filler selection must account for thermal expansion behavior and service conditions, particularly in hermetic or vacuum environments.
KOVAR is available in annealed through full-hard tempers (A–E) as defined in ASTM F15. Deep-drawing tempers must be specified at the time of inquiry to ensure proper forming behavior.
KOVAR is produced to ASTM F15, which defines composition, mechanical properties, thermal expansion behavior, and temper conditions. This standard is critical for applications involving hermetic sealing and precision electronics. Although the ASTM F-15 specification is no longer being updated, the mills will still produce and certify to the last revision.
Customers should specify ASTM F15 compliance, product form, temper condition, dimensions, surface finish, and whether the part will be used for glass-to-metal sealing. These details allow LEMA to supply material optimized for fabrication and performance.
KOVAR machines similarly to low-alloy steels but requires careful control of heat input and surface condition, especially for sealing applications. Surface cleanliness, finish, and oxidation control are critical when parts will undergo glass sealing or brazing.
Leading Edge Metals & Alloys supplies KOVAR in sheet, strip, plate, rod, bar, wire, and pre-cut blanks, as well as machined or formed components. Availability depends on temper, thickness, and application requirements.
Electronic and vacuum systems often combine metal components with glass or ceramic insulators. KOVAR prevents seal failure by expanding and contracting at nearly the same rate as the sealing material, maintaining long-term hermetic integrity in high-reliability environments.
KOVAR is most commonly used in electronic packaging, hermetic enclosures, vacuum devices, feedthroughs, sensors, and aerospace and defense electronics. These applications require airtight seals and dimensional stability under temperature changes.
KOVAR offers predictable, tightly controlled thermal expansion, good mechanical strength, and excellent dimensional stability. Its composition enables reliable glass-to-metal and ceramic-to-metal sealing across repeated thermal cycles.
KOVAR® (UNS K94610) is used instead of conventional steels or stainless alloys when controlled thermal expansion is critical. Conventional metals expand and contract at rates that can crack glass or ceramic seals, while KOVAR® is engineered to closely match the expansion of borosilicate and aluminosilicate glass.
