Technical News:
Electroplating of strip with Miralloy®,
a Cu-Sn- or Cu-Sn-Zn Alloy
General:

Up to now, only single parts could be electroplated with Miralloy®, a Copper-Tin or Copper-Tin-Zinc Alloy of the company UMICORE. From the beginning of 2001, OTEK Brieselang is now as the first job plater in the world able to do the plating not only of small (bulk) parts but also the reel-to-reel electroplating of strip with Miralloy®.

What is „Miralloy®“?

The term „Miralloy®“ designates electroplating processes for the deposition of bronze alloy coatings of copper and tin, or of copper, tin and zinc. Depending on the type of electrolyte used, white or yellow layers can be deposited. The coatings offered by OTEK are white coatings, containing about 55 % copper, 30 % tin and 15 % zinc.

Coating properties:

The Miralloy® coatings are characterized by a very good metal distribution and, depending on the type of bath, a high tarnish resistance, levelling, abrasion resistance, excellent corrosion resistance, and good soldering properties. Miralloy® layers have a finely crystalline and homogeneous structure. The coating hardnesses of Miralloy® white with 550 HV 0.1 are between the values of matt and bright nickel. Miralloy® coatings with activated flux additionally have a good solderability and weldability. Excellent antitarnishing properties and good corrosion resistance of the Miralloy® layers compensates for the higher contact resistance compared to silver. Miralloy® coatings on the other hand ensure an acceptable contact resistance even in an atmosphere containing sulphur and thus reduce the failure rate of components. Miralloy® layers are non-magnetic (i.e. diamagnetic) and therefore particularly suitable for high-frequency applications.

Skin-compatibility
and oligodynamic effect:

Miralloy® layers according to current scientific knowledge cause no allergies as they are known of nickel, and thus suggest themselves as suitable alternatives. In combination with nickel-free substrate materials and further nickel-free processes, the Miralloy® process permits the manufacture of completely skin-compatible articles. The skin compatibility was proved by wear tests with sensitive test persons. Miralloy® is therefore used worldwide for coating nickel-free articles, up to now, however, for single parts only. Miralloy® surfaces have a germicidal effect. Studies have shown that Miralloy® layers in this respect behave similar to or even better than silver or copper.

Fields of application:

Miralloy® coatings offer a wealth of possible applications. Miralloy® layers do not have the allergenic effect of nickel coatings - Miralloy® therefore is an excellent alternative to nickel. Apart from that the complete range of properties can be utilized. Miralloy® offers possible solutions even to complicated coating tasks and can also be used in combination with other metals, e.g. copper as an undercoat, or with precious metals as final layers.