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*'''Materials'''
<table border="1" cellspacing="0" style="border-collapse:collapse"><tr><td><p class="s8">Type of Coatings</p></td><td><p class="s8">Coating Thickness</p></td><td><p class="s8">Remarks</p></td></tr><tr><td><p class="s8">Precious Metals</p></td><td/><td/></tr><tr><td><p class="s8">Pure gold</p><p class="s8">Hard gold (AuCo 0.3)</p></td><td><p class="s8">0.1 - 3 µm</p></td><td><p class="s8">In special cases up to 10 µm</p></td></tr><tr><td><p class="s8">Palladium-nickel (PdNi20)</p></td><td><p class="s8">0.1 - 5 µm</p></td><td><p class="s8">Frequently with additional 0.2 µm AuCo 0.3</p></td></tr><tr><td><p class="s8">Silver</p></td><td><p class="s8">0.5 - 10 µm</p></td><td><p class="s8">In special cases up to 40 µm</p></td></tr><tr><td><p class="s8">Non-precious Metals</p></td><td/><td/></tr><tr><td><p class="s8">Nickel</p></td><td><p class="s8">0.5 - 4 µm</p></td><td><p class="s8">Diffusion barrier especially for gold layers</p></td></tr><tr><td><p class="s8">Copper</p></td><td><p class="s8">1 - 5 µm</p></td><td><p class="s8">Intermediate layer used in tinning of CuZn</p></td></tr><tr><td><p class="s8">Tin, tin alloys</p></td><td><p class="s8">0.8 - 25 µm</p></td><td><p class="s8">materials</p></td></tr></table>
*'''Carrier Materials'''
Copper, copper alloys, nickel, nickel alloys, stainless steel
*'''Dimensions and Tolerances'''
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Dimensions
Carrier thickness d= 0.1 - 1 mm
Carrier width B= 6 - 130 mm
Distance b > 2 mm
Coating width a= 2 - 30mm
Coating thickness s = 0.2 - 5 μm
(typical range)
Distance from edge b > 0.5 mm
depending on the carrier thickness
and the plating process
*'''Tolerances'''
Coating thickness approx. 10 %
Coating thickness and position + 0,5 mm
*'''Quality Criteria'''
Mechanical properties and dimensional tolerances of the carrier materials follow
the typical standards, i.e. DIN EN 1652 and 1654 for copper and copper alloys.
Depending on the application the following parameters are tested and
recorded (see also: Electroplating of parts):
*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.
===7.1.2 Electroless Plating===
===7.1.2.1 Introduction===
Electroless plating is defined as a coating process which is performed without
the use of an external current source. It allows a uniform metal coating
independent of the geometrical shape of the parts to be coated. Because of the
very good dispersion capability of the used electrolytes also cavities and the
inside of drilled holes in parts can be coated for example.
In principal two different mechanisms are employed for electroless plating:
processes in which the carrier material serves as a reduction agent (Immersion
processes) and those in which a reduction agent is added to the electrolyte
(Electroless processes).
