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→Precious Metal Electrolytes
widely used ones ''(Tables 7.1 and 7.2)''.
The following precious metal electrolytes are the most important ones:
*Gold electrolytes < br/>For functional and decorative purposes pure gold, hard gold, low-karat
gold, or colored gold coatings are deposited. Depending on the
requirements, acidic, neutral, or cyanide electrolytes based on
potassium gold cyanide or cyanide free and neutral electrolytes based
on gold sulfite complexes are used.
*Palladium and Platinum electrolytes < br/> Palladium is mostly deposited as a pure metal, for applications in
electrical contacts however also as palladium nickel. For higher value
jewelry allergy protective palladium intermediate layers are used as a
diffusion barrier over copper alloy substrate materials. Platinum is mostly
used as a surface layer on jewelry items.
*Ruthenium electrolytes < br/>Ruthenium coatings are mostly used for decorative purposes creating a
fashionable “grey” ruthenium color on the surface. An additional color
variation is created by using “ruthenium-black” deposits which are
mainly used in bi-color decorative articles.
*Rhodium electrolytes < br/>Rhodium deposits are extremely hard (HV 700 – 1000) and wear
resistant. They also excel in light reflection. Both properties are of value
for technical as well as decorative applications. While technical
applications mainly require hard, stress and crack free coatings, the
jewelry industry takes advantage of the light whitish deposits with high
corrosion resistance.
*Silver electrolytes < br/>Silver electrolytes without additives generate dull soft deposits (HV ~ 80)
which are mainly used as contact layers on connectors with limited
insertion and withdrawal cycles. Properties required for decorative
purposes such as shiny bright surfaces and higher wear resistance are
achieved through various additives to the basic Ag electrolyte.
Table 7.2: Precious Metal Electrolytes for Technical Applications
=====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 < br/>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 < br/>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 < br/>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 < br/>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
==== Electroplating of Parts====