The actual metal deposition occurs in the electrolytic solution which containsthe plating material as metal ions. Besides this basic ingredient, the electrolytescontain additional components depending on the processes used, such as forexample conduction salts, brighteners, and organic additives which are codepositedinto the coatings, influencing the final properties of the electroplatingdeposit.

All precious metals can be electroplated with silver and gold , also they are by far the mostwidely used ones ''(Tables <xr id="tab:Precious Metal Electrolytes for Technical Applications"/><!--(Tab. 7.1 2)--> and <xr id="tab:Precious Metal Electrolytes for Decorative Applications"/>)<!--(Tab. 7.23)''-->.

*Gold electrolytes < br/>For functional and decorative purposes pure gold, hard gold, low-karatgold, or colored gold coatings are deposited. Depending on therequirements, acidic, neutral, or cyanide electrolytes based onpotassium gold cyanide or cyanide free and neutral electrolytes basedon gold sulfite complexes are used.<br /> *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.<br /> *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.<br /> *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.<br /> *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.<br />  <figtable id="tab:Precious Metal Electrolytes for Technical Applications"><caption>'''<!--Table 7.2:-->Precious Metal Electrolytes for Technical Applications'''</caption>

*Palladium and Platinum {| class="twocolortable" style="text-align: left; font-size: 12px"|-!Type of Electrolyte !pH-Range!colspan="2" style="text-align:center"|Deposit Properties Hardness !Areas of Application|-!!!HV!Purity [kt] !|-|colspan="5" |'''Gold electrolytes '''|-|AUROMET TN|3.2 - 4.2|ca. 70|99.99% Au|Base-deposits|-|AUROMET XPH|0.3 - 0.6|160 - 180|99.8% Au|Base-deposits for stainless steel etc.|-|DODUREX COC|4.6 - 4.9|160 - 180|99.6% Au|Printed circuit boards, connectors, contact parts, etc.;< br/> Palladium is mostly deposited as a pure metal, hard gold coatings for rack and barrel plating|-|DODUREX HS 100|4.3 - 4.6|160 - 180|99.6% Au|High speed process for applications inconnectors and PCB plating|-|PURAMET 202<br />PURAMET 402|5.5 - 6.5<br />7.0 - 7.5|60 - 80<br />60 - 80|99.99% Au<br />99.99% Au|High purity gold coatings for electrical and electronic parts incl. semi<br />conductors and PCBs; for demanding requirement on bonding properties|-|colspan="5" |'''Platinum metal electrolytes'''|-|RHODOPLAT T|strongly acidic|900|99.0% Rh|Ductile rhodium deposits for thicker layers, reed contacts, sliding contacts however also as palladium nickel|-|RUTHENIUMBAD|stronglyacidic|900|99.0% Ru|Crack free thick ruthenium deposits|-|PLATINBAD 5|stronglyacidic|240 - 260|99.9% Pt|High temperature switching devices, etc|-|DODUPAL 3|7.0 - 8.0|220 - 250|99. For higher value9% Pdjewelry allergy protective |Thin palladium intermediate layers are used as adiffusion barrier over copper alloy substrate materials|-|DODUPAL 5|7.0 - 8.0|220 - 250|99.9% Pd|Connectors and contact parts|-|DODUPAL 10|8. Platinum is mostly0 - 8.5|350 - 400|80.0% Pd|Pd/Ni for connectors and contact parts|-|colspan="5" |'''Silver electrolytes'''|-|ARGOL 30|cyanidebasedused as |a surface layer on jewelry itemspprox. 90|99.9% Ag|rowspan="4" |Contact parts, connectors|-|ARGOL HS 100|approx. 9.0|90 - 120|99.9% Ag|-|ARGOL 2000|approx. 12.0|||-|ARGOL 400||160 - 180||}</figtable>

*Ruthenium electrolytes =====< br/>Ruthenium coatings are mostly used for decorative purposes creating afashionable “grey” ruthenium color on the surface!--7.1.1.1. An additional colorvariation is created by using “ruthenium2--black” deposits which aremainly used in bi>Non-color decorative articles.Precious Metal Electrolytes=====

*Rhodium electrolytes < br/>Rhodium deposits The most important non-precious metals that are deposited by electroplating are extremely hard (HV 700 – 1000) : Copper, nickel, tin and wearresistant. They also excel in light reflection. Both properties are of valuefor technical zinc as well as decorative applicationstheir alloys. While technicalapplications mainly require hard, stress and crack free coatings, The deposition is performed in thejewelry industry takes advantage form of pure metals with different electrolytes used (<xr id="tab:Typical Electrolytes for the light whitish deposits with highcorrosion resistanceDeposition of Non-Precious Metals"/><!--(Table 7.4)-->).

*Silver Copper electrolytes < br/>Silver Copper electrolytes without additives generate dull soft deposits (HV ~ 80)which are mainly used as contact layers for either depositing an intermediate layer on connectors with limitedinsertion and withdrawal cycles. Properties required strips or parts, for building up a printed circuit board structure or for decorativepurposes such as shiny bright surfaces and higher wear resistance areachieved through various additives to the basic Ag electrolytefinal strengthening during the production of printed circuit boards.<br />

Table 7*Tin electrolytes <br>Pure tin and tin alloy deposits are used as dull or also bright surface layers on surfaces required for soldering.2: Precious Metal Electrolytes In the printed circuit board manufacturing, they are also utilized as an etch resist for Technical Applicationsthe conductive pattern design after initial copper electroplating.<br />

The most important non-precious metals that are deposited by electroplatingare<figtable id="tab: Copper, nickel, tin, and zinc and their alloys. The deposition is performed inPrecious Metal Electrolytes for Decorative Applications">the form of pure metals with different electrolytes used <caption>'''(<!--Table 7.4)3:-->Precious Metal Electrolytes for Decorative Applications''.'</caption>

*Copper {| class="twocolortable" style="text-align: left; font-size: 12px"|-!Type of Electrolyte !pH-Bereich!colspan="2" style="text-align:center"|Deposit Properties!Areas of Application|-!!!Hardness HV!Purity [kt] !|-|colspan="5" |'''Gold electrolytes '''|-|DURAMET 1N14<br />DURAMET 2N18<br />DURAMET 3N<br />DURAMET 265S<br />DURAMET 333S<br />DURAMET 386S|3.4 - 3.8<br />3.4 - 3.8<br />3.4 - 3.8<br />3.4 - 3.8<br />3.2 - 3.6<br />3.4 - 3.8|1N<br />2N<br />3N<br />Hamilton<br />1N<br />Hamilton|23<br />23<br />23<br />23<br />23<br />23|Jewelry, watches, writing instruments, frames for glasses, fixtures|-|HELODOR 630|8.5 - 9.5|rose colored|22|Frames for glasses, jewelry, watches, writing instruments|-|DODUPLAT Y18<br />DODUPLAT Y18HS|9.5 - 10.5<br />9.5 - 11|2N<br />2N|18< br/>Copper 16|Jewelry, watches, writing instruments|-|AUROMET TN<br />AUROMET 2<br />AUROMET 4|3.2 - 4.2<br />3.2 - 4.0<br />3.2 - 4.2|Pure Gold<br />2 - 3N<br />2 - 3N|23<br />23<br />23|Colored gold for jewelry, watches, writing instruments, fixtures, frames for glasses, etc.|-|colspan="5" |'''Platinum metal electrolytes are used '''|-|RHODIOR 2<br />RHODIOR 20<br />RHODIOR 25<br />RHODIOR 40|< 1<br />< 1<br />< 1<br />< 1|white<br />white<br />white<br />white|99.99%Rh<br />99.99%Rh<br />99.99%Rh<br />99.99%Rh|Bright white rhodium coatings with high hardness for either depositing an intermediate layer onjewelry, watches, writing instruments, etc.|-|RUTHENIUMBAD|strongly acidic|grey/blackstrips or parts|99.0%Ru|Very hard and luster retaining Ruthenium coating|-|PLATINBAD|strongly acidic|white|99.9%Pt|Jewelry, watches, etc.|-|DODUPAL 3|7.0 - 7.6|Pd - color|95%Pd|Thin Pd/Zn coating as Ni-free diffusion barrier|-|DODUPAL 10|8.0 - 8.5|white|80%Pd|Pd/Zn alloy for building up a printed circuit board structure, or jewelry|-|DODUPAL 12|7.0 - 8.0|white|95%Pd|Pd/Zn alloy for thedecorations|-|colspan="5" |'''Silver electrolytes'''|-|ARGOL 2000|11.5 - 12.5|bright whitefinal strengthening during the production of printed circuit boards|99.9%Ag|Jewelry, watches, decoration|}</figtable>

*Tin Nickel electrolytes < br/>Pure tin and tin alloy deposits Nickel layers are mostly used as dull diffusion barriers during the gold plating of copper and copper alloys or also bright surfacelayers on surfaces required for soldering. In the printed circuit boardmanufacturing they are also utilized as an etch resist intermediate layer for the conductivepattern design after initial copper electroplating.tinning<br />

Table 7*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.3: Precious Metal Electrolytes For technical applications the bronze layers are utilized for Decorative Applicationstheir good corrosion resistance and good brazing and soldering properties.<br />

*Bronze electrolytes < br/figtable id="tab:Typical Electrolytes for the Deposition of Non-Precious Metals">Bronze coatings – in white or yellow color tones – are used either as anallergy free nickel replacement or as a surface layer <caption>'''<!--Table 7.4:-->Typical Electrolytes for decorativepurposes. For technical applications the bronze layers are utilized for theirgood corrosion resistance and good brazing and soldering properties.Deposition of Non-Precious Metals'''</caption>

Table 7{| class="twocolortable" style="text-align: left; font-size: 12px"|-!Type of Electrolyte !pH-Range!Electrolyte<br />temperature [°C]!Current density<br />[A/dm²]!Yield [%]|-|colspan="5" |'''Copper electrolytes'''|-|Cyanide copper|10 - 13|40 - 65|0 .5 - 4|70-95|-|Acidic copper|<1|20 - 35|2: Typical Electrolytes for the Deposition of Non-Precious Metals8|<100|-|colspan="5" |'''Nickel electrolytes'''|-|Watts nickel<br />(Sulfate)|3 - 5|40 - 70|3 - 10|95-97|-|Sulfamate nickel|3 - 4|30 - 60|5 - 20|95-97|-|colspan="5" |'''Tin electrolytes'''|-|Acidic tin (Sulfate)|<1|18 - 25|1 - 3|<100|-|Alkaline tin|>10|75 - 80|2 - 17|max.95|-|colspan="5" |'''Bronze electrolytes'''|-|DODUBRONCE W|Strongly alkaline|55 - 60|0.5 - 1.5||-|DODUBRONCE G|Strongly alkaline|45 - 50|2 - 3.5||-|DODUBRONCE AF|Strongly alkaline|58 - 62|0.5 - 1.5||}</figtable>

The complete or all-around electroplating of small mass produced parts , likecontact springs, rivets, or pins is usually done as mass plating in electroplatingbarrels of different shape. During the electroplating process the parts arecontinuously moved and mixed to reach a uniform coating.

Larger parts are frequently electroplated on racks either totally or by differentmasking techniques also partially. Penetrating the coating into the interior ofdrilled holes or tubes can be achieved with the use of special fixtures.

*'''Materials'''<figure id="fig:Electroplated Parts">[[File:Electroplated Parts.jpg|left|Figure 1: Electroplated Parts]]</figure> 

<table borderdiv class="1clear" cellspacing></div>'''Materials'''{| class="0twocolortable" style="bordertext-collapsealign:collapseleft; font-size: 12px;width:70%"><tr><td><p class|-!colspan="s92">Coatings</p></td></tr><tr><td><p classstyle="s9text-align:center">|Coatings|-|Precious metals</p></td><td><p class="s9">|Pure gold, hard gold (HV 150 – 250), palladium, palladium-nickel, rhodium,<br /p><p class="s9">rhodium, pure silver, hard silver (HV 130 – 160)</p></td></tr><tr><td><p class="s9">|-|Non-precious metals</p></td><td><p class="s9">|Copper, nickel, tin, tin alloys</p></td></tr><tr><td><p class="s9">|-|Carrier materials</p></td><td><p class="s9">|Copper, copper alloys, nickel, nickel alloys, iron, steel,</p><p class="s9">aluminum, aluminum alloys, composite materials<br /p><p class="s9">composite materials such as aluminum – silicon carbide</p></td></tr></table>|}

*'''Coating thickness'''

{| class="twocolortable" style="text-align: left; font-size: 12px;width:70%"|-|Precious metals: |0.2 – 5 μm (typical layer thicknesses; for Ag also up to 25 μm)|-|Non-precious metals: |Up to approx. 20 μm|-|Tungsten |0.5 N|-|Tolerances: |Strongly varying depending on the geometrical shape ofparts (up to 50% at a defined measuring spot).<br />It is recommended to specify a minimum value for thecoating thickness at a defined measuring spot|}

*'''Quality criteria'''

*Coating thickness *Solderability*Adhesion strength *Porosity *Solderability*Bonding property*Porosity Contact *resistance These quality tests are performed according to industry standards, internalstandards, and customer specifications resp.

The process for overall electroplating of strips, profiles, and wires is mostlyperformed on continuously operating reel-to-reel equipment. The processingsteps for the individual operations such as pre-cleaning, electroplatingor rinsing, rinsingare following the same principles as those employed in parts electroplating.

The overall coating is usually applied for silver plating and tin coating of stripsand wires. Compared to hard gold or palladium , these deposits are ratherductile, ensuring that during following stamping and forming operations , nocracks are generated in the electroplated layers.

Since precious metals are rather expensive , it is necessary to perform theelectroplating most economically and to coat only those areas that need the layersfor functional purposes. This leads from overall plating to selectiveelectroplating of strip material in continuous reel-to-reel processes. Dependingon the final parts design and the end application , the processes can be appliedto solid strip material , as well as pre-stamped and formed continuous strips orutilizing wire-formed or machined pins , which have been arranged as bandoliersattached to conductive metal strips.

The core part of selective precious metal electroplating is the actualelectroplating cell. In it Inside the cell, the anode is arranged closely to the cathodic polarizedmaterial strip. Cathode screens or masks may be applied between the two , tofocus the electrical field onto closely defined spots on the cathode strip.

Special high performance electrolytes are used in selective electroplating toreach short plating times and allow a high flow rate of the electrolyte for a fastelectrolyte exchange in the actual coating area.

For a closely targeted electroplating of limited precious metal coating of contactsprings , so-called brush-electroplating cells are employed ''(<xr id="fig:Brush Tampon plating cell"/><!--(Fig. 7.1)''-->). The “brush”or “tampon” consists of a roof shaped titanium metal part covered with a specialfelt-like material. The metal body has holes in defined spots , through which theelectrolyte reaches the felt. Also located In the same spots is also the anode , consisting of afine platinum net. The pre-stamped and in the contact area pre-formed contactspring part is guided under a defined pressure over the electrolyte soaked feltmaterial and gets wetted with the electrolyte. This allows the metalelectroplating in highly selective spots.

Fig. 7<figure id="fig:Brush Tampon plating cell">[[File:Brush Tampon plating cell.jpg|right|thumb|Figure 1:Brush (or “Tampon”) plating cell;1 Strip; 2 Anode; 3 Electrolyte feed;4 Felt covered cell]]</figure>For special applications, such as for example electronic component substrates, a dot shaped precious metal coating is required. This is achieved with two belt masks running synchronous to the carrier material. One of these two masks has windows, which are open to the spot areas targeted for precious metal plating coverage.

Overall or selective electroplating of both sides of solid strips or pre-stampedparts in strip form

Stripe electroplating on solid strips through wheel cells or using maskingtechniques

One-sided selective coating of solid, pre-stamped, or metallically belt-linkedstrips by brush plating

Electroplating in spots of solid strips with guide holes or pre-stamped parts instrip form

bild[[File:Typical examples of electroplated semi finished materials.jpg|left|Typical examples of electroplated semi-finished materials (overall or selectively)]] <div class="clear"></div>'''Materials'''{| class="twocolortable" style="text-align: left; font-size: 12px;width:70%"|-!Type of Coatings!Coating Thickness!Remarks|-|colspan="3" |'''Gold electrolytes'''|-|Pure gold<br />Hard gold (AuCo 0.3)|0.1 - 3 μm|In special cases up to 10 μm|-|Palladium-nickel (PdNi20)|0.1 - 5 μm|Frequently with additional 0.2 μm AuCo 0.3|-|Silver|0.5 - 10 μm|In special cases up to 40 μm|-|colspan="3" |'''Non-precious Metals'''|-|Nickel|0.5 - 4 μm|Diffusion barrier especially for gold layers|-|Copper|1 - 5 μm|Intermediate layer used in tinning of CuZn|-|Tin, tin alloys|0.8 - 25 μm|materials|}

*'''Carrier Materials'''Copper, copper alloys, nickel, nickel alloys, stainless steel

*[[File:Dimensions and Tolerances.jpg|left|Dimensions and Tolerances]] <br style="clear:both;"/> '''Carrier MaterialsTolerances'''Copper, copper alloys, nickel, nickel alloys, stainless steel

*'''Dimensions {| class="twocolortable" style="text-align: left; font-size: 12px;width:30%"|-|Coating thickness approx.|&#177; 10 % |-|Coating thickness and Tolerances'''position|&#177; 0,5 mm |}

Dimensions'''Quality Criteria'''Carrier thickness d= 0Mechanical properties and dimensional tolerances of the carrier materials follow the typical standards, i.1 - 1 mmCarrier width B= 6 - 130 mmDistance b > 2 mmCoating width a= 2 - 30mmCoating thickness s = 0e.2 - 5 μm(typical range)Distance from edge b > 0DIN EN 1652 and 1654 for copper and copper alloys.5 mmdepending Depending on the carrier thicknessapplication, the following parameters are tested and the plating processrecorded (see also: Electroplating of parts):

*'''Tolerances'''Coating thickness approx. 10 %Coating thickness and position + 0,5 mm*Solderability*Adhesion strength *Bonding property *Porosity *Contact resistance

*'''Quality Criteria'''Mechanical properties and dimensional tolerances of the carrier materials followthe typical These quality tests are performed according to industrial standards, i.e. DIN EN 1652 and 1654 for copper internal standards and copper alloyscustomer specifications resp.Depending on the application the following parameters are tested andrecorded (see also: Electroplating of parts):

*==References==[[Surface Coating thickness *Solderability*Adhesion strength *Bonding property *Porosity *Contact resistanceTechnologies#References|References]]