Kovar is a nickel-cobalt-ferrous alloy with thermal expansion properties comparable to glass. This makes it ideal for a number of industrial applications – including telecomms, defence, digital printing, medical and aerospace – but it is well known as a challenging material to work with due to its risk of corrosion, something the experts at Tecan have applied specific control processes for.

Characteristics

  • Strong – high tensile and yield strength, making it ideal for high-pressure or high-stress applications.
  • Flexible to work with.
  • Low thermal expansion coefficient -ensures high dimensional stability over a wide temperature range.
  • Ferromagnetic properties -suitable magnetic shielding applications.
  • Hermetic sealing capabilities -suitable for applications requiring a vacuum seal.
  • Low thermal conductivity -suitable for controlled thermal expansion and stability.

typical aaplications

  • analytical instruments
  • conductors
  • electronic and ion sources
  • vacuum components
  • microwave tubes
  • radiofrquency electronics
  • hermetic seals
  • power tubes
  • transistors
  • diodes
  • x-ray tubes

As referred to above, despite its benefits, Kovar is highly susceptible to corrosion. Because of this, an additional layer of nickel and gold plating can also be applied to Kovar to improve its resistance to corrosive environments, or as needed for its application. It should be noted that it is important that this is applied expertly and under tight controls for it to be effective.

Kovar substrate plating with gold

As a non-reactive metal, unaffected by moisture and heat, gold does not oxidise and can withstand electrical connections that create elevated temperatures. As such, it is an ideal plating material. Tecan has a long pedigree in working with gold and has a proven track record in accurately plating the most miniature of precision parts for a number of industries including high reliability multi-function RF systems for defence and aerospace applications where accuracy is crucial.

Kovar nickel plating

It should be noted that when gold is applied to a Kovar substrate, metal ions within the alloys of the Kovar can diffuse into the gold layer, affecting the latter’s hardness and oxidising-resistance. To prevent this, we recommend that an anti-diffusion underplate such as nickel (electroless or sulphamate) should be applied.

In addition, it is recommended that a Kovar nickel plating finish is used under the gold plating where a bright finish is desirable and flex or deformation is not required. Where the latter is required, we recommend that sulphamate nickel is used as the underplate for higher ductility.

hermetic applications

As a nickel–cobalt ferrous alloy, Kovar is designed to have similar controlled thermal expansion characteristics to borosilicate (or Pyrex) glass and alumina ceramics. Because of this low coefficient, it is ideal for hermetic metal to glass sealing applications.

The hermetic seal creates a bond free of the trouble and failures caused by dirt, dust, moisture, mould spores or lack of pressure at high altitudes. As a result, Kovar provides many advantages in demanding end-use applications that operate in strictly controlled environments, such as defence, aerospace, medical, commercial and aerospace.

Combined with the benefits of Kovar gold plating or Kovar nickel plating, we provide our customers a specialised material with many unique properties.

Kovar etching for intricate designs

At Tecan we combine the precision of chemical etching with Kovar. The high-throughput etching process helps us to selectively remove materials from the Kovar substrate and create intricate patterns or features. The nickel-iron-cobalt alloy has excellent mechanical properties that help it withstand tough chemical conditions and stay intact during etching processes. This process differs significantly to precision CNC machining because it requires no hard contact with a part, and so imparts no risk to the flatness of the part.

The key benefit of using Kovar in manufacturing intricate parts and components for defence, aerospace, or medical applications is its excellent thermal expansion properties. This allows the components in aerospace and defence applications to withstand thermal cycling when required.

our etching capabilities

We use the latest technology and state-of-the-art facilities to etch Kovar with precision, according to your specifications.

Kovar etching from Tecan has numerous benefits:

  • We are able to bring together the best features of multitple manufacturing processes (including laser machining) to deliver the finest precision parts.
  • We have the ability to create intricate features with minimal distortion and precision etched parts with exceptional hermetic sealing capabilities
  • We can manufacture components with improved corrosion resistance
  • We apply tight process control
  • We have in house plating capabilities for cost and lead time cost-effectiveness

Quality control is key

Our electroless nickel plating quality control custom services for electrodeposition on Kovar are handled by our highly trained technical specialists and production staff that provide expertise, leadership and high standards of excellence. We are committed to confident and competent manufacture and our Kovar plating quality control process provides the keys to continued improvement and customer satisfaction.

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