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===7.1.1.1.2 Non-Precious Metal Electrolytes===
The most important non-precious metals that are deposited by electroplating
are: Copper, nickel, tin, and zinc and their alloys. The deposition is performed in
the form of pure metals with different electrolytes used ''(Table 7.4).''
*'''Copper electrolytes''' Copper electrolytes are used for either depositing an intermediate layer on strips or parts, for building up a printed circuit board structure, or for the final strengthening during the production of printed circuit boards.
*'''Tin electrolytes''' Pure tin and tin alloy deposits are used as dull or also bright surface layers on surfaces required for soldering. In the printed circuit board manufacturing they are also utilized as an etch resist for the conductive pattern design after initial copper electroplating.
Table 7.3: Precious Metal Electrolytes for Decorative Applications
*'''Nickel electrolytes''' Nickel layers are mostly used as diffusion barriers during the gold plating of copper and copper alloys or as an intermediate layer for tinning
*'''Bronze electrolytes''' Bronze coatings – in white or yellow color tones – are used either as an allergy free nickel replacement or as a surface layer for decorative purposes. For technical applications the bronze layers are utilized for their good corrosion resistance and good brazing and soldering properties.
Table 7.2: Typical Electrolytes for the Deposition of Non-Precious Metals
===7.1.1.2 Electroplating of Parts===
The complete or all-around electroplating of small mass produced parts like
contact springs, rivets, or pins is usually done as mass plating in electroplating
barrels of different shape. During the electroplating process the parts are
continuously moved and mixed to reach a uniform coating.
Larger parts are frequently electroplated on racks either totally or by different
masking techniques also partially. Penetrating the coating into the interior of
drilled holes or tubes can be achieved with the use of special fixtures.
===Electroplated Parts===
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*'''Materials'''
*'''Coating thickness'''
Precious metals: 0.2 – 5 μm (typical layer thicknesses; for Ag also up to 25 μm)
Non-precious metals: Up to approx. 20 μm
Tolerances: Strongly varying depending on the geometrical shape of
parts (up to 50% at a defined measuring spot).
It is recommended to specify a minimum value for the
coating thickness at a defined measuring spot
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*'''Quality criteria'''
Besides others the following layer parameters are typically monitored in-process and documented:
*Coating thickness *Solderability
*Adhesion strength *Bonding property
*Porosity Contact *resistance
These quality tests are performed according to industry standards, internal
standards, and customer specifications resp.
===7.1.1.3 Electroplating of Semi-finished Materials===
