Industrial products

Industrial Products

Solderable coatings

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Solderable coatings for the attachment of optical components made of sapphire and industrial glass (endoscopy, telecommunications, laser)
Soldering has some advantages over conventional methods of fixing components, such as clamps, screws or chucking devices:

  • No additional mechanical parts are needed for fixation
  • The soldered system is impervious to liquids and gas
  • It is largely free of stress

Soldering boasts resistance to much higher temperatures than adhesive systems and is suitable for use in autoclave applications.


Composition of a solderable coat on sapphire, YAG or mineral glass
The solderable layering consists of a substrate bonding coat, a diffusion barrier coat and a topcoat with wetting action. The barrier coat prevents the metal coatings from alloying with each other during the soldering process. The thickness of the layers depends on the solder, the soldering temperature and the materials which are being joined (coefficients of thermal expansion). The coating quality determines the adhesion of the soldered coats, as does the cleanliness of the surfaces.
Solderable coats can be applied using PVD on its own or in combination with electroplating.
Blösch AG offers the following coats as standard:

  • Cr/Cu/Ni/Au and Ti/Au for AuSn (80/20) solder
  • Cr/Cu/Ni/Sn for Ag/Sn solders
  • Other combinations on request


Technical data for the solderable coats
Strength of adhesion on glass: > 10 N/mm2
Suitability of metal coating for autoclave applications on sapphire: > 300 cycles
Temperature resistance: min. 400° C (depending on soldering time)

Electroplating

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Precious metal coatings are also widely used in medicine and metrology. Electroplating is the only method which can be used to achieve coating thicknesses of 2 µm and above. Parts can also be coated selectively, thanks to special covering and masking techniques. Electroplating can also be combined with PVD coating processes to deposit coatings on non-conductive materials such as ceramic and sapphire.
Blösch AG has developed a technology which makes it possible to silver-plate the balls of a ball bearing, working with electroplating applications in the nanometer range. Bearing noise is then completely eliminated.

Antireflection coating on spherical lenses

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Spherical lenses are used in large numbers in the telecommunications industry to inject and output laser light in optical fibres and for optical connection of two glass fibres. The lenses are made of optical glass, such as BK-7, sapphire, lanthanum glass, etc., and once again the laws of optics apply, i.e. some of the light is reflected each time the light beam passes from the air to the glass and vice versa. The spherical lenses are given an antireflection (AR) coating in order to minimise the loss of light output. In conventional coating the lenses are clamped in a tool holder and coated by physical vapour deposition (PVD). The balls are only partially coated in this process and cannot therefore be fitted in the lenses in any direction. Moreover, the process only works on balls with diameters larger than 1.5 mm. Blösch AG has developed its own process to eliminate these disadvantages. In this process the coating covers the entire surface of the sphere up to a diameter of 0.35 mm.

SINI scratch-resistant antireflection coating

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Conventional antireflection coatings produced by high-vacuum vapour deposition may be excellent at reducing reflection but they are not very resistant to scratches. This is a disadvantage on glasses subject to mechanical load, such as watch glasses or bar code scanners made of sapphire. The SINI antireflection coating eliminates this disadvantage. In addition to excellent reflection reduction on mineral glass and sapphire, SINI boasts levels of scratch resistance on a par with sapphire.

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