passivation coatings are applied as protection against silver sulfide formation.

For thin coatings starting from the liquid phase two processes are used

differentiated by the metallic deposition being performed either with or without

while the second one is a chemical deposition process.

For electroplating of metals, especially precious metals, water based solutions

(electrolytes) are used which contain the metals to be deposited as ions (i.e.

well as the most widely used electroplating processes are described.

The actual metal deposition occurs in the electrolytic solution which contains

the plating material as metal ions. Besides this basic ingredient, the electrolytes

deposit.

All precious metals can be electroplated with silver and gold by far the most

widely used ones ''(Tables 7.1 and 7.2)''.

<table border="1" cellspacing="0" style="border-collapse:collapse"><tr><td><p class="s8">AUROMET TN</p></td><td><p class="s8">3.2 - 4.2</p></td><td><p class="s8">ca. 70</p></td><td><p class="s8">99.99% Au</p></td><td><p class="s8">Base-deposits</p></td></tr><tr><td><p class="s8">AUROMET XPH</p></td><td><p class="s8">0.3 - 0.6</p></td><td><p class="s8">160 - 180</p></td><td><p class="s8">99.8% Au</p></td><td><p class="s8">Base-deposits for stainless steel etc.</p></td></tr><tr><td><p class="s8">DODUREX COC</p></td><td><p class="s8">4.6 - 4.9</p></td><td><p class="s8">160 - 180</p></td><td><p class="s8">99.6% Au</p></td><td><p class="s8">Printed circuit boards, connectors, contact parts, etc.; hard gold coatings for rack and barrel plating</p></td></tr><tr><td><p class="s8">DODUREX HS 100</p></td><td><p class="s8">4.3 - 4.6</p></td><td><p class="s8">160 - 180</p></td><td><p class="s8">99.6% Au</p></td><td><p class="s8">High speed process for connectors and</p><p class="s8">PCB plating</p></td></tr><tr><td><p class="s8">PURAMET 202</p><p class="s8">PURAMET 402</p></td><td><p class="s8">5.5 - 6.5</p><p class="s8">7.0 - 7.5</p></td><td><p class="s8">60 - 80</p><p class="s8">60 - 80</p></td><td><p class="s8">99.99% Au</p><p class="s8">99.99% Au</p></td><td><p class="s8">High purity gold coatings for electrical</p><p class="s8">and electronic parts incl. semi conductors and PCBs; for demanding requirement on bonding properties</p></td></tr></table>

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

Table 7.2: Typical Electrolytes for the Deposition of Non-Precious Metals

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

standards, and customer specifications resp.

The process for overall electroplating of strips, profiles, and wires is mostly

performed on continuously operating reel-to-reel equipment. The processing

cracks are generated in the electroplated layers.

Since precious metals are rather expensive it is necessary to perform the

electroplating most economically and coat only those areas that need the layers