MIRALLOY® Copper-Tin-(Zinc-) Electrolytes

Barrel and rack plating electrolyte for functional applications

MIRALLOY® has been offering nickel-free plating for the connector, clothing and fashion jewellery industries for more than 30 years. You can benefit from our experience and the ongoing development of our product range. The trademark MIRALLOY® comes from the English words “mirror“ and “alloy“. It refers to the Bronze Age, when copper and tin were used to make mirrored alloys.

MIRALLOY® denotes electroplating processes for the deposition of alloy coatings of copper and tin or of copper, tin and zinc. Depending on the electrolyte used, white or yellow layers can be deposited. You can choose electrolytes for rack and barrel plating from the wide range of MIRALLOY® processes available.

Electrolyte characteristics

Electrolyte type


Metal content

8.5 g/l Cu
34 g/l Sn
0.75 g/l Zn

pH value

> 13

Operating temperature

60 (58 - 62) °C

Current density range

0.5 (0.3 - 1) A/dm²

Plating speed

0.12 μm/min at 0.5 A/dm²

Anode material

MMO (type PLATINODE® 167, graphite)

Electrical conductivity

>50 m*(Ω*mm²)-1

Coating characteristics



Alloy composition

55 wt. % Cu
30 wt. % Sn
15 wt. % Zn

Colour of deposit



550 HV

Max. coating thickness

5 μm


  • White layer, similar to silver
  • Diamagnetic
  • High reflectivity
  • Good wear and corrosion protection
  • Abrasion- and tarnish-resistant
  • Can be combined with precious metals
  • Good sliding properties
  • High hardness
  • Solderable and weldable
  • Very good metal distribution
  • Low porosity
  • Free from heavy metals like CR, Pb, Co, Th etc.
  • Low intermodulation
  • Platings are RoHS-compliant


  • High frequency connectors
  • Battery covers
  • Hydraulic parts
  • Contact pins
  • Cooling coils
  • Bearing shells
  • Conducting elements

MIRALLOY® coatings are characterized by an excellent thickness distribution even in the case of parts with complex shapes. The coating hardnesses of MIRALLOY® layers are 400 HV 0.1 (MIRALLOY® yellow) and 550 HV 0.05 (MIRALLOY® white). The layers are abrasion-resistant. For this reason yellow MIRALLOY® layers are particularly suitable for coating bearing shells or pistons. Furthermore, the layers are diamagnetic. Therefore connectors for high-frequency technology provided with MIRALLOY® coatings reach very low intermodulation values in the mobile radio frequency range.

Intermodulation at 935/960 Mhz (GSM)
f1 = 935 MHz at 43 dBm (20 W)               ------->               fIM3 = 2 x f1 - f2 = 910 MHz
f2 = 960 MHz at 43 dBm (20 W)

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Questions about the product?

Markus Legeler

+49 7171 607 204

For inquiries and additional information
please contact

Umicore AG & Co. KG
Rodenbacher Chaussee 4
63457 Hanau-Wolfgang

Tel.: +49 (6181) 59 6005
Fax: +49 (6181) 59 2970
Email: chemistry@umicore.com
Website: www.chemistry.umicore.com

The information and statements contained herein are provided free of charge. They are believed to be accurate at the time of publication, but Umicore makes no warranty with respect thereto, including but not limited to any results to be obtained or the infringement of any proprietary rights. Use or application of such information or statements is at the user´s sole discretion, without any liability on the part of Umicore. Nothing herein shall be construed as a license or recommendation for use, which infringes upon any proprietary rights. All sales are subject to Umicore´s General Conditions of Sale and Delivery.