Duplex tin coating

1. Characteristics and properties

The alternative to lead tin coatings consists of 1/3 bright tin (2-3µm), 2/3 matt tin (4-6µm) and min. 2µm special nickel. The coating combination offers good meltability, high ductility, very good optical properties and minimizes whisker formation. In this process, both the positive electrical properties of a matt tin coating and the good physical and optical properties of a bright tin plating (insensitivity to touch) are combined in one layer system.

2. Benefits and areas of application

Duplex tin plating is used as an alternative to lead tin plating as the use of heavy metals is limited or completely prohibited by European legislation (RoHS) at the end of certain periods. As a result, tin-lead alloy coatings must be substituted by a more environmentally friendly substitute. The nickel plating (Special Nickellectronic) specially developed for connectors allows internal stresses and whisker formation to be reduced to a minimum.

Duplex tinning passes the solderability test according to DIN EN 60068-2-20 without annealing colours and is used in large parts of the galvanic coating of electronic components.

3. Basic material

Workpieces made of steel, stainless steel, aluminium and non-ferrous metals as well as their alloys can be coated after appropriate pre-treatment.

4. Required delivery condition

The goods provided must be largely metallically bright. Residual oils or residual impurities must be removable with conventional aqueous alkaline degreasers. Oils containing silicone, alkali/alkaline earth and high-pressure additives must be avoided at all costs.