Besides manufacturing contact materials from the solid phase, i.e. by melt orpowder metallurgy, the production starting in the liquid or gaseous phase isgenerally preferred when thin layers in within the μm range are required , which cannotbe obtained economically by conventional cladding methods(<xr id="tab:Overview_of_Important_Properties_of_Electroplated_Coatings_and_their_Applications"/><!--(Tab. 7.1)-->). Such coatingsfulfill different requirements depending on their composition and thickness.They can serve as corrosion or wear protection or can fulfill the need for thincontact layers for certain technical applications. In addition they serve fordecorative purposes as a pleasing and wear resistant surface coating.

<figtable id="tab:Overview_of_Important_Properties_of_Electroplated_Coatings_and_their_Applications"><caption>'''<!--Table 7.1: -->Overview of Important Properties of Electroplated Coatingsand their Applications'''</caption>

To reduce the {| class="twocolortable" style="text-align: left; font-size: 12px"|-!Properties!Applications!Examples|-|Color|Pleasing appearance|Brass plated lamps and furniture hardware|-|Luster|Decorative appearance, Light reflection|Chrome plated fixtures, silver coated mirrors|-|Hardness / Wear Resistance|Prolonging of mechanical wear life|Hard chrome plated tools|-|Sliding properties|Improvement of thin dry sliding wear|Lead-tin-copper alloys for slide bearings|-|Chemical stability|Protection against chemical effects|Lead-Tin coatings as etch resist on PC boards|-|Corrosion resistance|Protection against environmental corrosion|Zinc coatings on steel parts|-|Electrical conductivity|Surface conduction of electrical current|Conductive path on PC boards|-|Thermal conductivity|Improved heat conduction on the surface |Copper plated bottoms for cookware|-|Machining capability|Shaping through machining|Copper coatings on low pressure cylinders|-|Magnetic properties|Increase of coercive force [[#text-reference|^*)]] |Cobalt-nickel layers on sliding magnetic storage media|-|Brazing and connectorsoldering|Brazing without aggressive fluxes|Tin-Lead coatings on PC board pathscontacts additional lubricants |-|Adhesion strength|Improvement of adhesion|Brass coating on reinforcement steel wires in liquid form are often used. On silver contactstires|-|Lubricating properties|Improvement of formability|Copper plating for wire drawing|}</figtable>passivation coatings are applied as protection against silver sulfide formation.<div id="text-reference">*) Coercive force= force to retaim the adopted magnetisation</div>

===7.1 Coatings from To reduce the Liquid Phase===For mechanical wear of thin coatings starting from the surface layers on sliding and connector contacts, additional lubricants in liquid phase two processes form are often useddifferentiated by the metallic deposition being performed either with or withoutthe use of an external electrical current source. The first one is electroplatingwhile the second one is a chemical deposition processOn silver contacts, passivation coatings are applied as protection against silver sulfide formation.

===7.1.1 Electroplating (or Galvanic Deposition)=Coatings from the Liquid Phase==For electroplating of metalsthin coatings starting from the liquid phase, especially precious metals, water based solutions(electrolytes) two processes are used which contain differentiated by the metals to be deposited as ions (i.e.dissolved metal salts). An electric field between metallic deposition being performed either with or without the anode and the work piecesas the cathode forces the positively charged metal ions to move to the cathodewhere they give up their charge and deposit themselves as metal on the surfaceuse of the work piece.Depending on the application, for electric and electronic or decorative end use,different electrolytic bath solutions (electrolytes) are usedan external electrical current source. The first one is electroplatingequipment used for precious metal plating and its complexity varies widelydepending on , while the second one is a chemical deposition process technologies employed.Electroplating processes are encompassing besides the pure metal depositionalso preparative and post treatments of the goods to be coated. An importantparameter for creating strongly adhering deposits is the surface of the goods tobe metallic clean without oily or oxide film residues. This is achieved throughvarious pre-treatment processes specifically developed for the types of materialand surface conditions of the goods to be plated.In the following segments electrolytes – both precious and non-precious – aswell as the most widely used electroplating processes are described.

===7.1.1.1 Electroplating Solutions – Electrolytes(or Galvanic Deposition)===The actual For electroplating of metals, especially precious metals, water based solutions (electrolytes) are used, which contain the metals to be deposited as ions (i.e. dissolved metal deposition occurs in salts). An electric field between the electrolytic solution which containsanode and the plating material work pieces as the cathode, forces the positively charged metal ionsto move to the cathode where they give up their charge and deposit themselves as metal on the surface of the work piece. Besides this basic ingredientDepending on the application, the for electric and electronic or decorative end use, different electrolytic bath solutions (electrolytescontain additional components ) are used. The electroplating equipment used for precious metal plating and its complexity varies widely, depending on the process technologies employed.Electroplating processes usedare encompassing, besides the pure metal deposition, such as also preparative and post treatments of the goods to be coated. An important parameter forexample conduction salts, brightenerscreating strongly adhering deposits is that the surface of the goods has to be metallic clean without oily or oxide film residues. This is achieved through various pre-treatment processes, specifically developed for the types of material and organic additives which are codepositedsurface conditions of the goods to be plated.into In the coatingsfollowing segments, influencing the final properties of electrolytes – both precious and non-precious – as well as the most widely used electroplatingdepositprocesses are described.

===7.1.1.1.1 Precious Metal Electrolytes===All precious metals can be electroplated with silver and gold by far the mostwidely used ones ''Main Articel: [[Electroplating (or Galvanic Deposition)| Electroplating (Tables 7.1 and 7.2or Galvanic Deposition)''.The following precious metal electrolytes are the most important ones:]]

*'''Gold electrolytes''' For functional and decorative purposes pure gold, hard gold, low===<!-karat gold, or colored gold coatings are deposited-7. 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 used1.2-->Electroless Plating===

*'''Palladium and Platinum electrolytes''' Palladium Electroless plating is mostly deposited defined as a pure coating process which is performed without the use of an external current source. It allows a uniform metalcoating, 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 applications in electrical contacts however also as palladium nickelexample. For higher value jewelry allergy protective palladium intermediate layers In principal, two different mechanisms are used employed for electroless plating: processes in which the carrier material serves as a diffusion barrier over copper alloy substrate materials. Platinum reduction agent (Immersion processes) and those in which a reduction agent is mostly used as a surface layer on jewelry itemsadded to the electrolyte (Electroless processes).

*'''Rhodium electrolytes''' Rhodium deposits are extremely hard ==<!--7.2-->Coatings from the Gaseous Phase (Vacuum Deposition)==The term PVD (HV 700 – 1000physical vapor deposition) defines processes of metal, metal alloys and wear resistant. They also excel chemical compounds deposition in light reflectiona vacuum by adding thermal and kinetic energy by particle bombardment. Both properties The main processes 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 following four coating variations (<xr id="tab:Characteristics of the light whitish deposits with high corrosion resistanceMost Important PVD Processes"/><!--(Table 7.6-->):

*'''Silver electrolytes''' Silver electrolytes without additives generate dull soft deposits Vapor deposition *Sputtering (HV ~ 80Cathode atomization) 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.*Arc vaporizing *Ion implantation

Table 7In all four processes, the coating material is transported in its atomic form to the substrate and deposited on it as a thin layer (a few nm to approx.2: Precious Metal Electrolytes for Technical Applications10 μm)

*<figtable id="tab:Characteristics of the Most Important PVD Processes"><caption>'''Copper electrolytes<!--Table 7.6:-->Characteristics of the Most Important PVD Processes''' 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.</caption>

*'''Tin electrolytes''' Pure tin and tin {| class="twocolortable" style="text-align: left; font-size: 12px"|-!Process!Principle!Process Gas Pressure!Particle Energy!Remarks|-|Vapor deposition|Vaporizing in a crucible <br />(electron beam or resistance heating)|10^-3 Pa|< 2eV|Separation of alloy deposits are used as dull or also bright surface layers on surfaces required for soldering. In components may occur|-|Arc vaporizing|Vaporizing of the printed circuit board manufacturing they are also utilized as target <br />plate in an etch resist for electrical arc|10^-1 Pa-1Pa|80eV-300eV|Very good adhesion due to ion bombardement|-|Sputtering|Atomizing of the target plate<br />(cathode) in a gas discharge|10^-1 Pa-1Pa|10eV-100eV|Sputtering of non-conductive pattern design after initial copper electroplating.materials possible through RF operation|-|Ion implantation|Combination of vapor <br />deposition and sputtering|10^-1 Pa-1Pa|80eV-300eV|Very good adhesion from ion bombardment but also heating of the substrate material|}</figtable>

*'''Nickel electrolytes''' Nickel layers are mostly used as diffusion barriers during The sputtering process has gained the gold plating economically most significant usage. Its process principle is illustrated in (<xr id="fig:Principle of copper and copper alloys or as an intermediate layer for tinningsputtering"/><!--(Fig. 7.5)-->).

*'''Bronze electrolytes''' Bronze coatings – <figure id="fig:Principle of sputtering">[[File:Principle of sputtering.jpg|right|thumb|Figure 1: Principle of sputtering Ar = Argon atoms; e = Electrons; M = Metal atoms]]</figure>Initially, a gas discharge is ignited in white or yellow color tones – a low pressure (10^-1 -1 Pa) argon atmosphere. The argon ions generated, are used either as accelerated in an allergy free nickel replacement or as electric field and impact the target of material to be deposited with high energy. Caused by this energy, atoms are released from the target material which condensate on the oppositely arranged anode (the substrate) and form a surface layer for decorative purposeswith high adhesion strength. For technical applications Through an overlapping magnetic field at the bronze layers are utilized for their good corrosion resistance and good brazing and soldering propertiestarget location, the deposition rate can be increased, making the process more economical.

Table 7.2The advantages of the PVD processes and especially sputtering for electrical contact applications are: Typical Electrolytes for the Deposition of Non-Precious Metals

===7.1.1.2 Electroplating *High purity of Parts===the deposit layers The complete or all-around electroplating of small mass produced parts like*Low thermal impact on the substrate contact springs, rivets, or pins is usually done as mass plating in electroplating*Almost unlimited coating materials barrels of different shape. During the electroplating process the parts are*Low coating thickness tolerance continuously moved and mixed to reach a uniform coating.*Excellent adhesion (also by using additional intermediate layers)

Larger parts Coatings produced by PVD processes are frequently electroplated used for contact applications, for example 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 miniature-profiles, in electrical engineering and for electronic components, for solderability in joining processes, for metalizing of special fixturesnonconductive materials, as well as in semiconductors, opto-electronics, optics and medical technology applications.

There are few limitations regarding the geometrical shape of substrate parts. Only the interior coating of drilled holes and small diameter tubing can be more problematic (ratio of depth to diameter should be < 2:1). Profile wires, strips and foils can be coated from one side or both; formed parts can be coated selectively by using masking fixtures that at the same time serve as holding fixtures (<xr id===Electroplated Parts===bild"fig:Examples of vacuum coated semi finished materials and parts"/>).

*'''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 μmTolerances<figure id="fig: Strongly varying depending on the geometrical shape Examples ofvacuum coated semi finished materials and parts (up to 50% at a defined measuring spot).It is recommended to specify a minimum value for thecoating thickness at a defined measuring spot als Bild? *'''Quality criteria''' ">Besides others the following layer parameters are typically monitored in-process and documented[[File: *Coating thickness *Solderability*Adhesion strength *Bonding property*Porosity Contact *resistance These quality tests are performed according to industry standards, internalstandards, and customer specifications resp. ===7.1.1.3 Electroplating Examples of Semi-vacuum coated semi finished Materials===The process for overall electroplating of strips, profiles, materials and wires is mostlyperformed on continuously operating reel-to-reel equipment. The processingsteps for the individual operations such as pre-cleaning, electroplating, 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. ===7.1.1.4 Selective Electroplating===Since precious metals are rather expensive it is necessary to perform theelectroplating most economically and 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 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 ''(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. 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. 7.1jpg|left|Figure 2:Brush (or “Tampon”) plating cell;1 Strip; 2 Anode; 3 Electrolyte feed;4 Felt covered cell For special applications, such as for example electronic component substrates,a dot shaped precious metal coating is required. This is achieved with two beltmasks running synchronous to the carrier material. One of these two masks haswindows which are open to the spot areas targeted for precious metal platingcoverage. ===Summary of the processes for selective electroplating=== *'''Immersion electroplating'''Overall or selective electroplating of both sides of solid strips or pre-stampedparts in strip form *'''Stripe electroplating'''Stripe electroplating on solid strips through wheel cells or using maskingtechniques *'''Selective electroplating'''One-sided selective coating of solid, pre-stamped, or metallically belt-linkedstrips by brush plating *'''Spot electroplating'''Electroplating in spots of solid strips with guide holes or pre-stamped parts instrip form ===Typical examples Examples of electroplated vacuum coated semi-finished materials=== (overall or selectively)and parts]]bild</figure>

<table borderclass="1twocolortable" cellspacing><tr><th rowspan="02" style><p class="border-collapse:collapses8">Substrate Materials</p><tr/th><tdth colspan="12"><p class="s8">Type of CoatingsCoating Materials</p></th></tr><tr><th><p><span>Ag</span></p></th><th><p><span>Au</span></p></th><th><p><span>Pt</span></p></th><th><p><span>Pd</span></p></th><th><p><span>Cu</span></p></th><th><p><span>Ni</span></p></th><th><p><span>Ti</span></p></th><th><p><span>Cr</span></p></tdth><th><p><span>Mo</span></p></th><th><p><span>W</span></p></th><th><p><span>Ai</span></p></th><th><p><span>Si</span></p></th></tr><tr><td><p class="s8">Coating ThicknessPrecious metal / alloys</p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p class="s8">Remarks<span>[[File:K7-gef.png]]</span></p></td></tr><tr><td><p class="s8">Precious MetalsNF metals / alloys</p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td></tr><tr><td><p class="s8">Pure goldFe alloys / stainless steel</p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p class="s8">Hard gold (AuCo 0</td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.3)png]]</span></p></td><td><p class="s8">0<span>[[File:K7-gef.1 png]]</span></p></td><td><p><span>[[File:K7- 3 µmgef.png]]</span></p></td><td><p class="s8">In special cases up to 10 µm<span>[[File:K7-gef.png]]</span></p></td></tr><tr><td><p class="s8">Palladium-nickel Special metals (PdNi20Ti, Mo, W)</p></td><td><p class="s8">0<span>[[File:K7-leer.png]]</span></p></td><td><p><span>[[File:K7-gef.1 png]]</span></p></td><td><p><span>[[File:K7- 5 µmgef.png]]</span></p></td><td><p class="s8">Frequently with additional 0<span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.2 µm AuCo 0png]]</span></p></td><td><p><span>[[File:K7-gef.3png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</trspan></p><tr/td><td><p class="s8">Silver<span>[[File:K7-gef.png]]</span></p></td><td><p class="s8">0<span>[[File:K7-gef.5 png]]</span></p></td><td><p><span>[[File:K7- 10 µmleer.png]]</span></p></td><td><p class="s8">In special cases up to 40 µm<span>[[File:K7-gef.png]]</span></p></td></tr><tr><td><p class="s8">NonCarbide steels (WC-precious MetalsCo)</p></td><td><p><span>[[File:K7-leer.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></trp></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p><tr/td><td><p class="s8">Nickel<span>[[File:K7-gef.png]]</span></p></td><td><p class="s8">0<span>[[File:K7-gef.5 png]]</span></p></td><td><p><span>[[File:K7- 4 µmgef.png]]</span></p></td><td><p class="s8">Diffusion barrier especially for gold layers<span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></trp><tr/td><td><p class="s8">Copper<span>[[File:K7-gef.png]]</span></p></td><td><p class="s8">1 <span>[[File:K7- 5 µmleer.png]]</span></p></td><td><p class="s8">Intermediate layer used in tinning of CuZn<span>[[File:K7-gef.png]]</span></p></td></tr><tr><td><p class="s8">TinCeramics (Al<span class="s16">2</span>O<span class="s16">3</span>, tin alloysAlN)</p></td><td><p><span>[[File:K7-leer.png]]</span></p></td><td><p><span>[[File:K7-leer.png]]</span></p></td><td><p class="s8">0<span>[[File:K7-gef.8 png]]</span></p></td><td><p><span>[[File:K7- 25 µmgef.png]]</span></p></td><td><p class="s8">materials<span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></trp></td><td><p><span>[[File:K7-gef.png]]</span></p></tabletd><td><p><span> *'''Carrier Materials'''Copper, copper alloys, nickel, nickel alloys, stainless steel *'''Dimensions and Tolerances''' Bild  DimensionsCarrier thickness d= 0[[File:K7-gef.1 png]]</span></p></td><td><p><span>[[File:K7- 1 mmCarrier width B= 6 gef.png]]</span></p></td><td><p><span>[[File:K7- 130 mmDistance b gef.png]]</span></p></td><td><p><span> 2 mmCoating width a= 2 [[File:K7- 30mmCoating thickness s = 0leer.2 png]]</span></p></td><td><p><span>[[File:K7- 5 μmgef.png]]</span></p></td></tr><tr><td><p class="s8">Glasses (typical rangeSiO<span class="s16">2</span>, CaF)Distance from edge b </p></td><td><p><span> 0[[File:K7-leer.5 mmdepending on the carrier thicknessand the plating process *'''Tolerances'''Coating thickness approxpng]]</span></p></td><td><p><span>[[File:K7-leer. 10 %Coating thickness and position + 0,5 mm *'''Quality Criteria'''Mechanical properties and dimensional tolerances of the carrier materials followthe typical standards, ipng]]</span></p></td><td><p><span>[[File:K7-gef.epng]]</span></p></td><td><p><span>[[File:K7-gef. DIN EN 1652 and 1654 for copper and copper alloyspng]]</span></p></td><td><p><span>[[File:K7-gef.Depending on the application the following parameters are tested andrecorded (see alsopng]]</span></p></td><td><p><span>[[File: Electroplating of parts)K7-gef.png]]</span></p></td><td><p><span>[[File: *Coating thickness *Solderability*Adhesion strength *Bonding property *Porosity *Contact resistance These quality tests are performed according to industry standards, internalstandards, and customer specifications respK7-gef. ===7png]]</span></p></td><td><p><span>[[File:K7-gef.1png]]</span></p></td><td><p><span>[[File:K7-gef.2 Electroless Plating=== ===7png]]</span></p></td><td><p><span>[[File:K7-gef.1png]]</span></p></td><td><p><span>[[File:K7-leer.2png]]</span></p></td><td><p><span>[[File:K7-gef.1 Introductionpng]]</span></p></td></tr><tr><td><p class===Electroless plating is defined as a coating process which is performed withoutthe use of an external current source. It allows a uniform metal coatingindependent of the geometrical shape of the parts to be coated. Because of thevery good dispersion capability of the used electrolytes also cavities and theinside 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 "s8">Plastics (Immersionprocesses) and those in which a reduction agent is added to the electrolyte(Electroless processesPA, PPS)</p></td><td><p><span>[[File:K7-gef. ===7png]]</span></p></td><td><p><span>[[File:K7-gef.1png]]</span></p></td><td><p><span>[[File:K7-gef.2png]]</span></p></td><td><p><span>[[File:K7-gef.2 Immersion Processes===The immersion processes are usually applied in the plating of the metals gold,silver, and tinpng]]</span></p></td><td><p><span>[[File:K7-gef. If the material to be coated is less precious, ipng]]</span></p></td><td><p><span>[[File:K7-gef.epng]]</span></p></td><td><p><span>[[File:K7-gef. exhibits anegative standard potential against the metal ions in the surrounding solution, itgoes into solution releasing electrons while the more precious metal ions arereduced by absorbing electrons and being deposited on the electrodepng]]</span></p></td><td><p><span>[[File:K7-gef. Thisprocess can continue until the complete surface of the substrate is coveredwith a thin layer of the more precious metalpng]]</span></p></td><td><p><span>[[File:K7-gef. This limits the maximum achievablelayer thickness to approxpng]]</span></p></td><td><p><span>[[File:K7-gef. 0png]]</span></p></td><td><p><span>[[File:K7-gef.1 μm ''(Table 7.5)''png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td></tr></table>

Table 7.5: Immersion Gold Electrolytes<table border="1" cellspacing="0" style="border-collapse:collapse"><tr><td><p class="s8">Type of Electrolyte</p></td><td><p class="s8">pH-Range</p></td><td><p class="s8">Coating Properties</p></td><td><p class="s8">Application Ranges</p></td></tr><tr><td><p class="s8">Type of Electrolyte</p></td><td><p class="s8">pH-Range</p></td><td><p class="s8">Hardness</p><p class="s8">HV 0.025</p></td><td><p class="s8">Punity</p></td><td><p class="s8">Application Ranges</p></td></tr><tr><td><p class="s8">Immersion Gold electrolytes</p></td><td/><td/><td/><td/></tr><tr><td><p class="s8">AUROL 4</p><p class="s8">AUROL 16</p><p class="s8">AUROL 20</p></td><td><p class="s8">3.8 - 4.2</p><p class="s8">5.8 - 6.2</p><p class="s8">5.8 - 6.2</p><p class="s8">5.8 - 6.2</p></td><td><p class="s8">60 - 80</p><p class="s8">60 - 80</p><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><p class="s8">99.99% Au</p><p class="s8">99.99% Au</p></td><td><p class="s8">Thin gold layers on Ni, Ni alloys,</p><p class="s8">Fe and Fe alloys for PCB technology and technical applications</p></td></tr></table> ===7.1.2.3 Electroless Processes===The electroless metal plating with adding reduction agents to the electrolyte isbased on the oxidation of the reducing agent with release of electrons whichthen in turn reduce the metal ions. To achieve a controlled deposition from suchsolutions the metal deposition has to happen through the catalytic influence ofthe substrate surface. Otherwise a “wild” uncontrollable deposition would occur. In most casespalladium containing solutions are used for the activation which seed thesurfaces with palladium and act as catalysts in the copper and nickelelectrolytes. The electrolytes contain besides the complex ion compounds of the metals tobe deposited also stabilizers, buffer and accelerator chemicals, and a suitablereduction agent. These electrolytes are usually operating at elevated temperatures (50° – 90°C).The deposits contain besides the metals also process related foreign inclusionssuch as for example decomposition products of the reduction agents.The electroless processes are used mainly for copper, nickel, and golddeposits. ===7.1.2.4 Electroless Deposition of Nickel/Gold=== Electroless deposited nickel coatings with an additional immersion layer of goldare seeing increased importance in the coating of printed circuit boards (PCBs).The process sequence is shown in ''(Fig. 7.2)'' using the example of theDODUCHEM process. Tabelle After the pre-cleaning (degreasing and etching) a palladium sulfate activator isused which activates the exposed copper surfaces on the printed circuit boardand thus facilitates the nickel deposition. The electroless working chemicalnickel electrolyte contains – besides other ingredients – Sodium-hypophosphite,which is reduced to phosphorus in a parallel occurring process andincorporated into the nickel deposit. At the temperature of 87 – 89°C a veryhomogeneous nickel-phosphorus alloy layer with approx. 9 wt% P is depositedwith layer thicknesses > 5 μm possible. During a consecutive processing stepa very thin and uniform layer (< 0.1 μm) of gold is added in an immersionelectrolyte. This protects the electroless nickel layer against corrosion achievinga solderable and well bondable surface for thick or fine aluminum bond wires. It is possible to enhance this layer combination further by adding a immersionpalladium layer between the electroless nickel and the gold coating(DODUBOND process). This Pd layer acts as a diffusion barrier and allows theusage of this surface combination also for gold wire bonding. As an alternative, for gold wire bonding applications a thicker gold layer of 0.2 –0.5 μm can be applied using an electroless process. Typical electrolytes work ata temperature of approx. 80°C with deposition rates of 0.3 – 0.4 μm per 30minutes. There are however limitations with these electroless electrolytesconcerning their stability and the robustness of the process compared to otherelectroplating processes which reduces their wider usage ''(Fig. 7.3)''. Fig. 7.3:Coating compositionof a printed circuit board withreductively enhanced gold ===7.1.2.5 Immersion Deposition of Tin===A tin coating by ion exchange is usually not possible since copper is the moreprecious metal. By adding thio-urea the electro-chemical potential of copper isreduced to a level (approx. 450 mV, significantly lower than tin) that allows theexchange reaction. Using a suitable electrolyte composition and enhancersolutions like with the DODUSTAN process ''(Fig. 7.4)'' tin coatings can beproduced that, even under usually unfavorable conditions of copperconcentrations of 7 g/l in the electrolyte, are well solderable. Fig. 7.4: Process flow for electroless tin deposition using the DODUSTAN process The immersion tin deposition is suitable for the production of a well solderablesurface on printed circuit boards and electronic components. It is also used asan etch resist against ammonia based solutions or as corrosion and oxidationprotection of copper surfaces. ===7.2 Coatings from the Gaseous Phase (Vacuum Deposition)===The term PVD (physical vapor deposition) defines processes of metal, metalalloys, and chemical compounds deposition in a vacuum by adding thermal andkinetic energy through particle bombardment. The main processes are thefollowing four coating variations ''(Table 7.6)'': *Vapor deposition *Sputtering (Cathode atomization)*Arc vaporizing *Ion implantation In all four processes the coating material is transported in its atomic form to thesubstrate and deposited on it as a thin layer (a few nm to approx. 10 μm) Table 7.6: Characteristics of the Most Important PVD Processes tabelle fehlt! The sputtering process has gained the economically most significant usage. Itsprocess principle is illustrated in ''(Fig. 7.5)''. Fig. 7.5: Principle of sputtering Ar = Argon atoms; e = Electrons; M = Metal atoms Initially a gas discharge is ignited in a low pressure (10 – 1 Pa) argonatmosphere. The argon ions generated are accelerated in an electric field andimpact the target of material to be deposited with high energy. Caused by thisenergy atoms are released from the target material which condensate on theoppositely arranged anode (the substrate) and form a layer with high adhesionstrength. Through an overlapping magnetic field at the target location thedeposition rate can be increased, making the process more economical. The advantages of the PVD processes and especially sputtering for electricalcontact applications are: *High purity of the deposit layers *Low thermal impact on the *Almost unlimited coating materials substrate*Low coating thickness tolerance *Excellent adhesion (also by using additional intermediate layers) Coatings produced by PVD processes are used for contact applications, forexample on miniature-profiles, in electrical engineering and for electroniccomponents, for solderability in joining processes, for metalizing of nonconductivematerials, as well as in semiconductors, opto-electronics, optics,and medical technology applications. There are few limitations regarding the geometrical shape of substrate parts.Only the interior coating of drilled holes and small diameter tubing can be moreproblematic (ratio of depth to diameter should be < 2:1). Profile wires, strips,and foils can be coated from one side or both; formed parts can be coatedselectively by using masking fixtures that at the same time serve as holdingfixtures. *'''Examples of vacuum coated semi-finished materials and parts'''bild *'''Materials'''Selection of possible combinations of coating and substrate materials <table border="1" cellspacing="0" style="border-collapse:collapse"><tr><td><p class="s8">Substrate Materials</p></td><td><p class="s8">Coating Materials</p></td></tr><tr><td><p class="s8">Substrate Materials</p></td><td><p><span>Ag</span></p></td><td><p><span>Au</span></p></td><td><p><span>Pt</span></p></td><td><p><span>Pd</span></p></td><td><p><span>Cu</span></p></td><td><p><span>Ni</span></p></td><td><p><span>Ti</span></p></td><td><p><span>Cr</span></p></td><td><p><span>Mo</span></p></td><td><p><span>W</span></p></td><td><p><span>Ai</span></p></td><td><p><span>Si</span></p></td></tr><tr><td><p class="s8">Precious metal / alloys</p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td></tr><tr><td><p class="s8">NF metals / alloys</p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td></tr><tr><td><p class="s8">Fe alloys / stainless steel</p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td></tr><tr><td><p class="s8">Special metals (Ti, Mo, W)</p></td><td><p><span>can be produced[[File:K7-leer.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-leer.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td></tr><tr><td><p class="s8">Carbide steels (WC-Co)</p></td><td><p><span>[[File:K7-leer.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-leer.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td></tr><tr><td><p class="s8">Ceramics (Al<span class="s16">2</span>O<span class="s16">3</span>, AlN)</p></td><td><p><span>[[File:K7-leer.png]]</span></p></td><td><p><span>[[File:K7-leer.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-leer.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td></tr><tr><td><p class="s8">Glasses (SiO<span class="s16">2</span>, CaF)</p></td><td><p><span>[[File:K7-leer.png]]</span></p></td><td><p><span>[[File:K7-leer.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-leer.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td></tr><tr><td><p class="s8">Plastics (PA, PPS)</p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td><td><p><span>[[File:K7-gef.png]]</span></p></td></tr></table>can be produced with intermediate layer

{| class="twocolortable" style="text-align: left; font-size: 12px;width:40%"|-!colspan="2" style="text-align:center"|'''Dimensions'''|-|Coating thickness: |10 nm - 15 μm|-|Coating thicknesses for contact applications: |0.1 - 10 μm|}

For the geometry of semi-finished products to be coated , there are fewrestrictions. Only the coating of the inside of machined holes and tubing has

Coating thickness +&#177;10 - 30 %, depending on the thickness

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, internalstandards, and customer specifications resp.

===<!--7.3 -->Comparison of Deposition Processes===The individual deposition processes have in part different performancecharacteristics. For each end application , the optimal process has to be chosen, considering all technical and economical factors. The main selection criteriashould be based on the electrical and mechanical requirements for the contactlayer and on the design characteristics of the contact component. <xr id="tab:Comparison of different coating processes"/><!--Table 7.7--> gives some indications for a comparative evaluation of the different coatingprocesses.

The electroless metal coating is not covered here because of the low thicknessof deposits , which makes them in most cases not suitable for contact

The main differences between the <figtable id="tab:Comparison of different coating processes are found in the coating">materials and thickness<caption>'''<!--Table 7. While mechanical cladding and sputtering allow theuse 7:-->Comparison of almost any alloy material, electroplating different coating processes are limited to metalsand selected alloys such as for example high-carat gold alloys with up to .3wt% Co or Ni. Electroplated and sputtered surface layers have a technologicaland economical upper thickness limit of about 10μm. While mechanical claddinghas a minimum thickness of approx. 1 μm, electroplating and sputteringcan also be easily applied in very thin layers down to the range of 0.1 μm.'''</caption>

The properties of the coatings are closely related to the coating process.{| class="twocolortable" style="text-align: left; font-size: 12px"|-!Process / Coating Properties!Mechanical Processes (Cladding)!Electroplating!Vaccum Deposition (Sputtering)|-|Coating materialStarting materials for cladding |formabe metal and sputtering targets precious alloys|metals, alloys only limited|metals and theiralloysalloys which |-|Coating thickness|> 1μm|0.1 - approx. 10 μm <br />(in the case special cases up to 100 μm)|0.1 approx. 10 μm|-|Coating configuration|selectively, stamping edges not coated|all around and selectively<br />stamping edges coated|mostly selectivity|-|Adhesion|good|good|very good|-|Ductility|good|limited|good|-|Purity|good|inclusions of gold and palladium based foreign materials are vacuummelted and therefore exhibit a |very high puritygood|-|Porosity|good|good for > approx. During electroplating, depending1μm|good|-|Temperature stability|goodvery good|good|very goodon the type of electrolytes and the deposition parameters, some electrolyte|-components such as carbon and organic compounds are incorporated into|Mechanical wearthe precious metal coating. Layers deposited from the gaseous phase however|littleare |very pure.little|little|-|Environmental impact|little|significant|none|}</figtable>

===7.4 Hot (-Dipped) Tin Coated Strip Materials===During hot-dip tinning pre-treated strip materials The main differences between the coating processes are coated with pure tin or tinalloys from a liquid solder metal. During overall (or all-around) tinning found in thestripsthrough a liquid metal melt. For strip tinning rotating rolls are partiallyimmersed into a liquid tin melt coating materials and transport the liquid onto the strip which isguided above themthickness. Through special wiping While mechanical cladding and gas blowing procedures sputtering allow thedeposited tin layer can be held within tight tolerances. Hot tinning is performeddirectly onto the base substrate use of almost any alloy material without any pre, electroplating processes are limited to metals and selected alloys, such as for example high-coating carat gold alloys with eithercopper up to .3 wt% Co or nickelNi. Special cast-on processes or the melting Electroplated and sputtered surface layers have a technological and economical upper thickness limit of about 10μm. While mechanical cladding has a minimum thickness of solder foils ontothe carrier strip allow approx. 1 μm, electroplating and sputtering can also be easily applied in very thin layers down to the production range of thicker solder layers(> 15 0.1 μm).

The main advantage properties of hot tinning of copper the coatings are closely related to the coating process. Starting materials for cladding and sputtering targets precious metals and copper their alloys as compared totin electroplating is , which in the formation case of an inter-metallic copper-tin phase (Cu₃Sngold and palladium based materials,Cu₆ Sn₅) at the boundary between the carrier material are vacuum melted and the tin layertherefore exhibit a very high purity. This thin(0.3 – 0.5 μm) intermediate layerDuring electroplating, which is formed during depending on the type of electrolytes and the thermal tinningprocessdeposition parameters, is rather hard some electrolyte components such as carbon and reduces in connectors organic compounds are incorporated into the frictional force andmechanical wearprecious metal coating. Tin coatings produced by hot tinning have a good adhesion toLayers deposited from the substrate material and do not tend to tin whisker formationgaseous phase however are very pure.

A special process of ==<!--7.4-->Hot (-Dipped) Tin Coated Strip Materials==During hot -dip tinning, pre-treated strip materials are coated with pure tin or tin alloys from a liquid solder metal. During overall (or all-around) tinning is the “Reflow” processstrips through a liquid metal melt. After depositing For strip tinning, rotating rolls are partially immersed into a liquid tincoating by electroplating melt and transport the liquid onto the strip, which is guided above them. Through special wiping and gas blowing procedures, the deposited tin layer can be held within tight tolerances. Hot tinning is shortperformed directly onto the base substrate material without any pre-time melted in a continuous processcoating with either copper or nickel.The properties Special cast-on processes or the melting of solder foils onto the carrier strip, also allows the production of these reflow tin coatings are comparable to those created byconventional hot tinningthicker solder layers ( > 15 μm).

Besides overall The main advantage of hot tinning of copper and copper alloys, compared to tin coating electroplating, is the formation of strip an inter-metallic copper-tin phase (Cu₃Sn, Cu₆Sn₅) at the boundary between the carrier material and the tin layer. This thin (0.3 – 0.5 μm) intermediate layer, which is formed during the thermal tinning process, is rather hard and reduces the frictional force and mechanical wear in connectors. Tin coatings produced by hot tinning can also be applied inhave a good adhesion to the form of single or multiple stripes on both sides of a continuous substratestripmaterial and do not tend to tin whisker formation.

*'''Typical examples A special process of hot tinned strip materials'''tinning is the “Reflow” process. After depositing a tin coating by electroplating, the layer is short-time melted in a continuous process.bildThe properties of these reflow tin coatings are comparable to those created by conventional hot tinning.

Coating materials: Pure tin, tin alloys<br>Substrate materials: Cu, CuZn, CuNiZn, CuSn, CuBe and others<br />

{| class="twocolortable" style="text-align: left; font-size: 12px;width:40%"|-|Width of tinning: > |&#8805; 3 + &#177; 1 mm|-|Thickness of tinning: |1 - 15 μm|-|Tolerances (thickness): + |&#177; 1 - +&#177; 3 μm depending on tin thickness|}

Mechanical strength and dimensional tolerances of hot tinned strips are closelyrelated to the standard for Cu and Cu alloy strips according to DIN EN 1652 andDIN EN 1654.

===<!--7.5 -->Contact Lubricants===By using suitable lubricants , the mechanical wear and frictional oxidation ofsliding and connector contacts can be substantially reduced. In the electricalcontact technology , solid, as well as high and low viscosity liquid lubricants areused.

Solid lubricants include for example 0.05 – 0.2 μm thin hard gold layers , whichare added as surface layers on top of the actual contact material.

Among the various contact lubricants offered on the market , contact lubricationoils have shown performance advantages. They are mostly synthetic, chemically inert, and silicone-free oils such as for example the DODUCONTAcontact lubricants which differ in their chemical composition and viscosity.

For sliding contact systems with contact forces < 50 cN and higher slidingspeeds , oils with a lower viscosity (<50 mPa·s) are preferential. For applicationswith higher contact forces and operating at higher temperatures , contact oilswith a higher viscosity are advantageous. Contact oils are mainly suited forapplications at low current loads. At higher loads and in situations wherecontact separation occurs during the sliding operation , thermal decompositionmay be initiated , which causes the lubricating properties to be lost.

==<!--7.6-->Passivation of Silver Surfaces==The formation of silver sulfide during the shelf life of components with silver surface in sulfur containing environments, can be significantly eliminated by coating them with an additional protective film layer (Passivation layer). For electrical contact use, such thin layers should be chemically inert and sufficiently conductive, otherwise they are easily broken by the optimum lubrication only a very thin layer of applied contact oil is requiredforce.Therefore it is <figure id="fig:Typical process flow for example recommended to dilute the oil in iso-propylenealcoholSILVERBRITE W ATPS process">during [[File:Typical process flow for the application to contact partsSILVERBRITE W ATPS process. After evaporation of jpg|right|thumb|Figure 4: Typical process flow for the alcoholSILVERBRITE W ATPS process]]</figure>The passivation process SILVERBRITE W ATPS is a thin water-based tarnish preventer for silver (<xr id="fig:Typical process flow for the SILVERBRITE W ATPS process"/>). It is free of chromium(VI) compounds and uniform solvents. The passivating layer of lubricant is retained on applied by immersion, which creates a transparent organic protective film which barely changes the appearance and only slightlyincreases the good electrical properties such as for example the contact surfacesresistance. The good solderability and bond properties of silver are notnegatively affected. Because of its chemical composition, this protective layer has some lubricating properties which reduce the insertion and withdrawal forces of connectors noticeably.

 *'''Properties of the Synthetic DODUCONTA Contact Lubricants''' <table border="1" cellspacing="0" style="border-collapse:collapse"><tr><td><p class="s8">Lubricant</p></td><td><p class="s8">DODUCONTA</p></td></tr><tr><td><p class="s8">Lubricant</p></td><td><p class="s8">B5</p></td><td><p class="s8">B9</p></td><td><p class="s8">B10</p></td><td><p class="s8">B12K</p></td><td><p class="s8">B25</p></td></tr><tr><td><p class="s8">Contact force</p></td><td><p class="s8">&gt;1N</p></td><td><p class="s8">0.1 - 2N</p></td><td><p class="s8">&lt; 0.2N</p></td><td><p class="s8">0.2 - 5N</p></td><td><p class="s8">&lt;1N</p></td></tr><tr><td><p class="s8">Density (20°C)</p><p class="s8">[g/cm³]</p></td><td><p class="s8">1.9</p></td><td><p class="s8">1.0</p></td><td><p class="s8">0.92</p></td><td><p class="s8">1.0</p></td><td><p class="s8">1.0</p></td></tr><tr><td><p class="s8">Specificel. Resis-</p><p class="s8">tance [<span class="s9">S · </span>cm]</p></td><td/><td><p class="s8">2 x 10<span class="s18">10</span></p></td><td><p class="s8">10<span class="s18">10</span></p></td><td><p class="s8">6 x 10<span class="s18">9</span></p></td><td><p class="s8">5 x 10<span class="s18">8</span></p></td></tr><tr><td><p class="s8">Viscosity (20°C)</p><p class="s8">[mPa·s]</p></td><td><p class="s8">325</p></td><td><p class="s8">47</p></td><td><p class="s8">21</p></td><td><p class="s8">235</p></td><td><p class="s8">405</p></td></tr><tr><td><p class="s8">Congeal temp.[°C]</p></td><td/><td><p class="s8">-55</p></td><td><p class="s8">-60</p></td><td><p class="s8">-40</p></td><td><p class="s8">-35</p></td></tr><tr><td><p class="s8">Flash point[°C]</p></td><td/><td><p class="s8">247</p></td><td><p class="s8">220</p></td><td><p class="s8">238</p></td><td><p class="s8">230</p></td></tr><tr><td/><td><p class="s8">220</p></td><td/><td/></tr></table>  *'''Applications of the Synthetic DODUCONTA Contact Lubricants''' <table border="1" cellspacing="0" style="border-collapse:collapse"><tr><td><p class="s8">Lubricant</p></td><td><p class="s8">Applications</p></td></tr><tr><td><p class="s8">DODUCONTA B5</p></td><td><p class="s8">Current collectors, connectors, slider switches</p></td></tr><tr><td><p class="s8">DODUCONTA B9</p></td><td><p class="s8">Wire potentiometers, slip rings, slider switches, measuring range selectors, miniature connectors</p></td></tr><tr><td><p class="s8">DODUCONTA B10</p></td><td><p class="s8">Precision wire potentiometers, miniature slip rings</p></td></tr><tr><td><p class="s8">DODUCONTA B12K</p></td><td><p class="s8">Wire potentiometers, slider switches, miniature slip rings, connectors</p></td></tr><tr><td><p class="s8">DODUCONTA B25</p></td><td><p class="s8">Current collectors, measuring range selectors, connectors</p></td></tr></table>  ===7.6 Passivation of Silver Surfaces===The formation of silver sulfide during the shelf life of components with silversurface in sulfur containing environments can be significantly eliminated bycoating them with an additional protective film layer (Passivation layer). Forelectrical contact use such thin layers should be chemically inert andsufficiently conductive, or be easily broken by the applied contact force. The passivation process SILVERBRITE W ATPS is a water-based tarnishpreventer for silver. It is free of chromium(VI) compounds and solvents. Thepassivating layer is applied by immersion which creates a transparent organicprotective film which barely changes the appearance and only slightlyincreases the good electrical properties such as for example the contactresistance. The good solderability and bond properties of silver are notnegatively affected. Because of its chemical composition this protective layerhas some lubricating properties which reduce the insertion and withdrawalforces of connectors noticeably. Fig. 7.7: Typical process flow for the SILVERBRITE W ATPS process ===References===

schwefelhaltiger Umgebung<trade>th</trade>. VDE – Fachbericht 65 (2009) 51 – 58 [[de:Beschichtungsverfahren]]