Semi-finished contact pre-materials can be manufactured from solid preciousmetals, precious metal alloys, or precious metal containing composite materials.They are made in wire, strip, and profile form by known processing technologiessuch as extrusion and subsequent annealing and drawing or roll-forming. Theyare supplied following the manufacturer's internal standards usually related toDIN EN specifications for copper based materials. The most important materialsare two – or multiple material layered semi-finished materials with the contactmaterial bonded in its solid phase to non-precious carriers by cladding, brazing,or welding. The contact material can also be deposited on the carrier from the

===Clad Semi-Finished Pre-Materials (Contact-Bimetals)===Clad materials consist of two or more layers of different materials, the contactmaterial and the carrier, which are firmly bonded to each other. Depending onthe electrical requirements the contact material is mainly an alloy of gold,palladium, or silver based , while the carrier material are mainly copper alloys. Tobond these materials , various technologies are utilized, the two most importantones being described in more detail below.

During ''hot cladding'', the classic process, the materials to be clad areassembled into a cladding package in block or plate form, heated to about800°C and clad (or “welded”"welded") together under high pressure ''(<xr id="fig:Hot_cladding_of_pre_materials"/><!--(Fig. 3.3)''-->). At theinterface between the two materials , a non-separable bond is formed by eitherdiffusion of the reaction partners or in liquid phase by forming a AgCu eutecticalloy when an additional brazing alloy foil is placed between the two materials.Further processing is done by rolling with required annealing steps betweensubsequent thickness reductions. The disadvantage of this process is theusually limited short length of final material strips.

In the ''Cold Roll-Cladding'' process, the bond between the contact and carrier material is achieved by cold deformation of > 50% in one rolling pass (<xr id="fig:Cold roll-cladding of semi-finished strips (schematic)"/><!-- (Fig. 3.3: Hot cladding 4)-->). The high plastic deformation causes cold welding in the boundary layer between the two materials. To increase the quality and strength of prethe bond, a subsequent diffusion annealing is performed in most cases. This process is most suitable for clad semi-materials finished strips with thin contact material layers (&ge; 2 μm) and large strip length (schematic> 100 m).

In the ''Cold Roll-Cladding'' process the bond between the *Typical configurations of clad contact and carriermaterial is achieved by cold deformation of > 50% in one rolling pass ''strips (Fig. 3.4)''.The high plastic deformation causes cold welding in the boundary layer betweenthe two materials. To increase the quality and strength <xr id="fig:Typical configurations of the bond a subsequentdiffusion annealing is performed in most cases. This process is most suitable forclad semi-finished contact strips with thin contact material layers (> 2 μm) and large striplength ("/> 100 m).

Fig. 3*Contact materials <br />Ag, Ag-alloys.4: Cold roll-cladding of semi-finished strips (schematic), Ag/Ni, in special cases also Ag/SnO₂ and Ag/ZnO <br />

*Typical configurations of clad contact stripsbildCarrier materials: Cu, CuSn, CuNiZn, CuNiSn, CuFe, CuBe et al.

*Contact materialsbildDimensions (<xr id="fig:Dimensions"/>)

*Carrier materialsbild? *DimensionsbildWhen specifying the contact material layer thickness it is recommended to use theminimum required thickness.

Strength properties and dimensional tolerances of clad contact bi-metals arederived from the standards DIN EN 1652 and DIN EN 1654 for Cu alloys. Whenspecifying the width of the contact material layer , it is recommended to use theminimum required value. All dimensions should be specified originating from onestrip edge. == Brazed Semi-Finished Contact Materials (Toplay–Profiles)==The toplay process starts with a flat or profile – shaped contact material stripwhich is fed together with the wider non-precious carrier material and in mostcases an intermediate thin foil of brazing alloy into a induction brazing machine''(Fig. 3.5)''. An evenly distributed and reliable braze joint can be achieved this waybetween contact and carrier materials. The combined material strip is rather softafter the brazing process and re-hardened during a subsequent profile rollingstep. In this way different shapes and configurations can easily be achieved. Fig. 3.5: Toplay brazing with an inductive heating inline equipment (schematic)

*<div class="multiple-images"><figure id="fig:Hot_cladding_of_pre_materials">[[File:Hot cladding of pre-materials (schematisch).jpg|right|thumb|Figure 1: Hot cladding of pre-materials (schematic)]]</figure><figure id="fig:Cold roll-cladding of semi-finished strips (schematic)">[[File:Cold roll-cladding of semi-finished strips (schematic).jpg|right|thumb|Figure 2: Cold roll-cladding of semi-finished strips (schematic)]]</figure><figure id="fig:Typical configurations of clad contact strips">[[File:Typical configurations of toplay clad contact profilesstrips.jpg|right|thumb|Figure 3: Typical configurations of clad contact strips]]</figure><figure id="fig:Dimensions">[[File:Dimensions.jpg|right|thumb|Figure 4: Dimensions]]</figure></div>bild<div class="clear"></div>

*=== Brazed Semi-Finished Contact Materials (Toplay–Profiles)===The toplay process starts with a flat or profile – shaped contact material strip which is fed together with the wider non-precious carrier material and in most cases an intermediate thin foil of brazing alloy into a induction brazing machine (<xr id="fig:Toplay brazing with an inductive heating inline equipment (schematic)"/><!--(Fig. 3.5)-->). An evenly distributed and reliable braze joint can be achieved this way between contact and carrier materialsbild. The combined material strip is rather soft after the brazing process and re-hardened during a subsequent profile rolling step. In this way different shapes and configurations can easily be achieved.

*Carrier materialsbildTypical configurations of toplay contact profiles (<xr id="fig:Typical configurations of toplay contact profiles2"/>)

*Quality criteriaContact materials <br />Ag, dimensions AgNi 0,15, AgCu, AgCuNi (ARGODUR 27), Ag/Ni, Ag/SnO₂ and tolerancesbildAg/ZnO<br />

Strength properties and dimensional tolerances of toplay profiles are derivedfrom the standards DIN EN 1652 and DIN EN 1654 for *Carrier materials: Cu alloys, CuZn, CuSn et al.<br />

== Seam–Welded Contact Strip Materials *Quality criteria, dimensions and tolerances (FDR–Profiles)<xr id==Seam–welding is the process by which the contact material in the form of a solidwire, narrow clad strip, or profile is attached to the carrier strip by overlapping orcontinuous weld pulses between rolling electrodes ''(Fig. 3.6"fig:Quality criteria dimensions and tolerances"/>)''. The weld joint iscreated by simultaneous effects of heat and pressure. Except for the very smallactual weld joint area the original hardness of the carrier strip is maintainedbecause of the limited short time of the heat supply. Therefore also spring-hardbase materials can be used without loss of their mechanical strength. The use ofclad contact pre-materials and profiles allows to minimize the use of the costlyprecious metal component tailored to the need for optimum reliability over theexpected electrical life of the contact components.

*Typical configurations Strength properties and dimensional tolerances of seam–welded contact stripstoplay profiles are derived from the standards DIN EN 1652 and stamped partsbildFig. 3DIN EN 1654 for Cu alloys.6: Seam-welding process (schematic)

*Quality criteria and tolerancesStrength properties and dimensional tolerances of toplay Contact profiles in larger sizes are derived from often used for switching devices in the low voltage technology. For these, thestandards DIN EN 1652 and DIN EN 1654 for Cu alloyscontact layer mostly consists of arc erosion resistant materials such as silver–nickel, silver–metal oxides or the weld resistant silver– graphite.The brazable or weldable underside of the metal oxide or silver–graphite materials is usually pure silver with also quite often a thin layer of a phosphorous containing brazing alloy applied to aid the welding process.

== Contact Profiles *Typical configurations of multi-layer contact profiles (Contact Weld Tapes)<xr id==Contact profiles span a broad range "fig:Typical configurations of dimensions. Width and thickness are typicallybetween 0.8 – 8.0 mm and 0.2 – 3.0 mm resp. Special configurations, often definedas miniaturemulti-layer contact profiles or even micro–profiles can have awidth < 2.0 mm."/>)

Miniature–profiles are mostly composed of a contact*Contact materials <br />Au-bimetal material with the contactmaterial being a precious metal alloy or composite material cladAlloys, welded or coated byelectroplating or vacuumPd-deposition (sputtered) onto a weldable base material. Sincethese profiles are attached to carrier strip materials usually by segment– or seam–welding to the base materialsAlloys, materials with good welding properties such as nickelAg-Alloys,copper-nickelAg/Ni, copper-tinAg/SnO₂, as well as copper-nickel-zinc alloys are used. The bottomsurface of the profiles usually has formed weld rails or similar patterns to ensure asolid continuous metallurgical weld joint between the profile and the contact carrier.Ag/ZnO<br />

Contact profiles in larger sizes are often used *Carrier materials <br />(weldable substrate material for switching devices in the low voltagetechnology. For these the contact multi-layer mostly consists of arc erosion resistantmaterials such as silver–nickel) Cu, Ni, CuNiFe, CuNiZn, CuSn, silver–metal oxides or the weld resistant silver–graphite. The brazable or weldable underside of the metal oxide or silver–graphitematerials is usually pure silver with also quite often a thin layer of a phosphorouscontaining brazing alloy applied to aid the welding process.CuNiSn, NiCuFe<br />

*Typical configurations of multiBrazing alloy <br />L-layer contact profilesbildAg15P<br />

*Contact materialsbildQuality criteria <br />Beause of the variety of configurations of contact profiles, usually the quality issues are separately agreed upon between the manufacturer and the user.<br />

*Carrier materialsDimensions and tolerances (<xr id="fig:Contact Profiles Dimensions and tolerances"/>)bildThe thickness of the Au top-layer, which is sputtered for example, is between 0.2 and 5 μm, depending on the requirements. Tolerance of thickness is about &plusmn; 10%.

*Brazing alloy<div class="multiple-images">bild<figure id="fig:Typical configurations of multi-layer contact profiles"> *Quality criteriaBeause of the variety [[File:Typical configurations of multi-layer contact profiles.jpg|right|thumb|Figure 8: Typical configurations of multi-layer contact profiles usually the quality]]issues are separately agreed upon between the manufacturer </figure><figure id="fig:Contact Profiles Dimensions and the usertolerances">[[File:Contact Profiles Dimensions and tolerances. *jpg|right|thumb|Figure 9: Contact Profiles Dimensions and tolerances]]bild</figure>The thickness of the Au top-layer, which is sputtered for example, is between 0.2</div>and 5 μm, depending on the requirements. Tolerance of thickness is about + 10%.<div class="clear"></div>