For the joining of contact materials with carrier substrates , brazing alloys with working temperatures > 600 °C are used exclusively. The working temperature is defined as the lowest surface temperature , by which the brazing material wets the materials to be joined. This temperature is within the melting range and between the solidus (temperature at which melting starts) and liquidus (temperature at complete liquid state) point of the brazing alloy. Silver-based brazing alloys have good electrical conductivity and a sufficient mechanical strength , which allows a bonding process without significant changes in the 4 microstructure of the material to be joined.

For electrical contacts , usually low-melting alloys with a minimum of 20 wt-% silver and additions of cadmium, zinc or tin are used to lower the melting point are used (<xr id="figtab:fig4.1Commonly_Used_Brazing_Alloys_for_Electrical_Contacts"/> <!--(Table 4.1)-->). Because of the toxicity of cadmium , most cadmium containing brazing alloys have been replaced by zinc and tin containing brazing alloys. For Alloys containing nickel and manganese are also used for higher requirements on corrosion resistance requirements or for easier wetting of stainless steel nickel and manganese containing alloys are also used.. Using any of these brazing alloys in an air environment is only possible with the addition of oxide reducing fluxes.For high temperature brazing in vacuum or protective atmosphere vacuum melted silver-copper eutectic brazing alloys are used. These also allow subsequent forming operations due to their higher ductility.For the brazing of contacts with a silver bottom layer to copper backings phosphorous containing brazing alloys which eliminate the need for a flux application are widely used.The brazing alloy is typically introduced into the joint area in the form of wire segments, foil, shims, or as powder or paste. For larger production volumes it is economically advantageous to pre-coat contact tips with a thin layer (&le; 100 µm) of brazing alloy.

== Fluxes ==Brazing fluxes consist of nonFor high temperature brazing in vacuum or protective atmosphere, vacuum melted silver-metallic materials, mostly salt mixtures of boron and halogen compounds <xr id="tab:tab4copper eutectic brazing alloys are used.2"/> (Table 4These also allow subsequent forming operations due to their higher ductility.2). Their purpose is to remove oxides from For the brazing surfaces and prevent their new build-up in order of contacts with a silver bottom layer to allow copper backings, phosphorous containing brazing alloys which eliminate the need for a thorough wetting of these surfaces by the liquefied flux application, are widely used.The brazing alloy. Fluxes have to be activated already at a temperature below is typically introduced into the joint area in the working range form of the brazing alloywire segments, foil, shims or as powder or paste. They are selected mainly according For larger production volumes it is economically advantageous to the working temperature pre-coat contact tips with a thin layer (&le; 100 µm) of the brazing alloy and the base material to be joined.

<figtable id="tab:Commonly_Used_Brazing_Alloys_for_Electrical_Contacts"><caption>'''Tab <!--Table 4.1 2:-->Commonly Used Brazing Alloys for Electrical Contacts''' als Bild gemacht</caption>

<xr id{| class="twocolortable" style="figtext-align:fig4.1left; font-size: 12px"|-!Designation<br/>DIN EN 1044!BrazeTec<br/>Designation!Designation US<br/>(equivalent or closest similar brazing alloy)!Designation<br/>DIN EN ISO 3677!Composition<br/>wt %!Melting Range (solidus)<br/>[°C]!Melting Range (liquidus)<br/>[°C]!Working Temperature<br/>[File:Commonly Used Brazing °C]!Electrical Conductivity<br/>[MS/m]!Density<br/>[g/m³]!Application|-|AG103|BrazeTec 5507|BAg-7|B-Ag55ZnCuSn<br/>630/660|Ag54 - 56<br/>Cu20 - 23<br/>Zn20 - 24<br/>Sn1,5 - 2,5|630|660|650|8,4|9,6|Cu, Cu-Alloys for Electrical Contacts.jpg, Ag-materials<br/>Fe, Ni|-|Ag502|BrazeTec 4900|BAg-22|B-Ag49ZnCuMnNi<br/>680/705|Ag48 - 50<br/>Zn21 - 25<br/>Cu15 - 17<br/>Mn6,5 - 8,5<br/>Ni4 - 5|680|705|690|4,0|8,9|W, Mo, carbide steel<br/>Fe, Ni|-|Ag401|BrazeTec 7200|BAg-8|B-Ag72Cu-780|Ag71 - 73<br/>Cu Rest|780|780|right780|thumb46,1|Commonly Used Brazing 10,0|Cu, Cu-Alloys for Electrical Contacts]], Ag-materials<br/>vacuum brazing|-|CP 102|BrazeTec S15|BCuP-5|B-Cu80AgP<br/>645/800|Ag14,5 - 15,5<br/>P4,7 - 5,3<br/>Cu Rest|645|800|710|7,0|8,4|Cu, Cu-Legierungen, Ag-materials</figurefigtable>

Since == Fluxes ==Brazing fluxes consist of non-metallic materials, mostly salt mixtures of boron and halogen compounds (<xr id="tab:Fluxes for the residues Brazing of fluxes are hygroscopic Heavy Metals"/><!--(Table 4.2)-->). Their purpose is to remove oxides from the brazing surfaces and can cause corrosion they prevent their new build-up, in order to allow a thorough wetting of these surfaces by the liquefied brazing alloy. Fluxes have to be removed completely after activated already at a temperature below the working range of the brazing process in very hot or boiling wateralloy. Depending on They are selected mainly according to the working temperature of the type brazing alloy and process used, fluxes are being applied in liquid form or as powders or pastesthe base material to be joined.

<figtable id="tab:tab4.2Fluxes for the Brazing of Heavy Metals"><caption>'''<!--Table 4.2: -->Fluxes for the Brazing of Heavy Metals'''</caption>

<table border="1" cellspacing="0" styleclass="border-collapse:collapsetwocolortable"><tr><tdth><p class="s8">Designation</p><p class="s8">DIN EN 1045</p></tdth><tdth><p class="s8">Designation US (similar)</p></tdth><tdth><p class="s8">Active tempe- rature range [°C]</p></tdth><tdth><p class="s8">Chemical ingredients</p></tdth><tdth><p class="s8">Base materials used for</p></tdth></tr><tr><td><p class="s8">TYP FH 10</p></td><td><p class="s8">FB 3-A</p></td><td><p class="s8">550 - 800</p></td><td><p class="s8">Boron compounds, Fluorides</p></td><td><p class="s8">All metals and alloys except light metals, alloyed steels, carbide steels</p></td></tr><tr><td><p class="s8">TYP FH 11</p></td><td><p class="s8">FB 4-A</p></td><td><p class="s8">550 - 800</p></td><td><p class="s8">Boron compounds,</p><p class="s8">Fluorides, Chlorides</p></td><td><p class="s8">Copper,</p><p class="s8">Aluminum bronze</p></td></tr><tr><td><p class="s8">TYP FH 12</p></td><td><p class="s8">FB 3-C</p></td><td><p class="s8">550 - 850</p></td><td><p class="s8">Boron,</p><p class="s8">Boron compounds, Fluorides</p></td><td><p class="s8">Special brass,</p><p class="s8">any steel alloys, carbide steel</p></td></tr><tr><td><p class="s8">TYP FH 21</p></td><td><p class="s8">FB 3-I</p></td><td><p class="s8">750 - 1100</p></td><td><p class="s8">Boron compounds, Chlorides</p></td><td><p class="s8">All metals and alloys</p><p class="s8">except light metals</p></td></tr></table>