800°C and clad (or "welded") together under high pressure (<xr id="fig:Hot_cladding_of_pre_materials"/><!--(Fig. 3.3)-->). At the interface between the two materials, a non-separable bond is formed by either diffusion of the reaction partners or in liquid phase by forming a AgCu eutectic alloy when an additional brazing alloy foil is placed between the two materials. Further processing is done by rolling with required annealing steps between subsequent thickness reductions. The disadvantage of this process is the usually 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. 3.4)-->). The high plastic deformation causes cold welding in the boundary layer between the two materials. To increase the quality and strength of the bond, a subsequent diffusion annealing is performed in most cases. This process is most suitable for clad semi-finished strips with thin contact material layers (&ge; 2 μm) and large strip length (> 100 m).

*Typical configurations of clad contact strips (<xr id="fig:Typical configurations of clad contact strips"/>)

*Contact materials <br />Ag, Ag-alloys., Ag/Ni, in special cases also Ag/SnO₂ and Ag/ZnO <br />

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

When specifying the contact material layer thickness it is recommended to use the minimum required thickness.

=== 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 materials. 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.

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

*Carrier materials: Cu, CuZn, CuSn et al.<br />

*Quality criteria, dimensions and tolerances (<xr id="fig:Quality criteria dimensions and tolerances"/>)

<figure id="fig:Quality criteria dimensions and tolerances">

[[File:Quality criteria dimensions and tolerances.jpg|right|thumb|Figure 7: Quality criteria dimensions and tolerances]]

</figure>

=== Contact Profiles (Contact Weld Tapes)===

*Typical configurations of multi-layer contact profiles (<xr id="fig:Typical configurations of multi-layer contact profiles"/>)

*Contact materials <br />Au-Alloys, Pd-Alloys, Ag-Alloys, Ag/Ni, Ag/SnO₂, Ag/ZnO<br />

*Dimensions and tolerances (<xr id="fig:Contact Profiles Dimensions and tolerances"/>)

<figure id="fig:Contact Profiles Dimensions and tolerances">

[[File:Contact Profiles Dimensions and tolerances.jpg|right|thumb|Figure 9: Contact Profiles Dimensions and tolerances]]

</figure>

==References==