=== 4.1 Brazing Alloys ===<onlyinclude>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. </onlyinclude>Silver-based brazing alloys have good electrical conductivity and a sufficient mechanicalstrength which allows a bonding process without significant changes in the 4microstructure of the material to be joined.

For electrical contacts usually low-melting the joining of contact materials with carrier substrates, brazing alloys with a minimum of 20 wt-% silver and additions of cadmium, zinc or tin to lower the melting point working temperatures > 600 °C are used ''(Table 4exclusively.1)''. Because of The working temperature is defined as the toxicity of cadmium most cadmium containing brazing alloys have been replaced lowest surface temperature, by zinc and tin containing which the brazing alloysmaterial wets the materials to be joined. For higher requirements on corrosion resistance or for easier wetting of stainless steel nickel This temperature is within the melting range and between the solidus (temperature at which melting starts) and manganese containing alloys are also used. Using any liquidus (temperature at complete liquid state) point of these the brazing alloys in an air environment is only possible with the addition of oxide reducing fluxesalloy.For high temperature brazing in vacuum or protective atmosphere vacuum melted silverSilver-copper eutectic based brazing alloys are used. These also allow subsequent forming operations due to their higher ductility.For the brazing of contacts with have good electrical conductivity and a silver bottom layer to copper backings phosphorous containing brazing alloys sufficient mechanical strength, which eliminate the need for allows a flux application are widely used.The brazing alloy is typically introduced into the joint area bonding process without significant changes in the form microstructure of wire segments, foil, shims, or as powder or paste. For larger production volumes it is economically advantageous the material to pre-coat contact tips with a thin layer (< 100 µm) of brazing alloybe joined.

=== 4.2 Fluxes ===Brazing fluxes consist For electrical contacts, usually low-melting alloys with a minimum of non20 wt-metallic materials% silver and additions of cadmium, mostly salt mixtures of boron and halogen compounds ''zinc or tin are used to lower the melting point (<xr id="tab:Commonly_Used_Brazing_Alloys_for_Electrical_Contacts"/><!--(Table 4.21)-->)''. Their purpose is to remove oxides fromBecause of the toxicity of cadmium, most cadmium containing brazing surfaces alloys have been replaced by zinc and tin containing brazing alloys. Alloys containing nickel and prevent their new build-up in order to allow a thorough manganese are also used for higher corrosion resistance requirements or for easier wetting of these surfaces by the liquefied brazing alloystainless steel.. Fluxes have to be activated already at a temperature below the working range Using any of the these brazing alloy. They are selected mainly according to alloys in an air environment is only possible with the working temperature addition of the brazing alloy and the base material to be joinedoxide reducing fluxes.

{| classFor 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. <figtable id="twocolortabletab:Commonly_Used_Brazing_Alloys_for_Electrical_Contacts">|+ <caption>'''<!--Table 4.12: -->Commonly Used Brazing Alloys for Electrical Contacts'''</caption> {| class="twocolortable" style="text-align: left; font-size: 12px"|-!Designation<br/>DIN EN 1044!BrazeTec<br/>Designation!DesignationUS<br/>(equivalent or closest similar brazing alloy)!Designation<br/>DIN EN ISO 3677!Composition <br/>wt %!Melting Range (solidus)<br/>[°C]! colspan="2" style="" |Melting rangeRange (liquidus)<br/>[°C]!WorkingTemperature<br/>[°C]!ElectricalConductivity<br/>[MS/m]!Density<br/>[g/m³]

!DIN EN 1044|AG103!US (equivalent or closest|BrazeTec 5507similar brazing alloy)|BAg-7!DIN EN ISO 3677|B-Ag55ZnCuSn<br/>630/660!wt%|Ag54 - 56<br/>Cu20 - 23<br/>Zn20 - 24<br/>Sn1,5 - 2,5!|630!|660!Temperature|650[°C]|8,4![MS/m]|9,6![g|Cu, Cu-Alloys, Ag-materials<br/m³]!>Fe, Ni

|AG 304*) Ag401|BrazeTec 7200| BAg-1 |8| B-Ag40ZnCdCuAg72Cu-780595|Ag71 - 73<br/630 >Cu Rest| Ag39 - 41 780Cd18 - 22|780Cu18 - 20|780Zn19 - 23|46,1| 595 || 630 || 610 || 14.10,0 || 9.3 || Cu,Cu alloys-Alloys,Ag -materials, Fe, Ni<br/>vacuum brazing

|AG 306*) CP 102|BrazeTec S15| BAgBCuP-2a5|B-Ag30CuCdZn-600Cu80AgP<br/>645/765 800| Ag30 Ag14,5 - 32Cu28 15,5<br/>P4,7 - 305,3<br/>Cu RestCd21 - 25|645Zn21 - 25 |800| 600 710|| 690 || 680 || 13.7,0 |8,4|9.2 || Cu, Cu alloys-Legierungen,Ag-materials</figtable> == Fluxes ==Ag Brazing fluxes consist of non-metallic materials, Femostly salt mixtures of boron and halogen compounds (<xr id="tab:Fluxes for the Brazing of Heavy Metals"/><!--(Table 4.2)-->). Their purpose is to remove oxides from the brazing surfaces and prevent their new build-up, Niin order to allow a thorough wetting of these surfaces by the liquefied brazing alloy. Fluxes have to be activated already at a temperature below the working range of the brazing alloy. They are selected mainly according to the working temperature of the brazing alloy and the base material to be joined. Since the residues of fluxes are hygroscopic and can cause corrosion, they have to be removed completely after the brazing process in very hot or boiling water. Depending on the type and process used, fluxes are being applied in liquid form or as powders or pastes.

Since the residues of fluxes<reftable class="twocolortable">residues of fluxes<tr><th><p class="s8">Designation</refp> are hygroscopic <p class="s8">DIN EN 1045</p></th><th><p class="s8">Designation US (similar)</p></th><th><p class="s8">Active tempe- rature range [°C]</p></th><th><p class="s8">Chemical ingredients</p></th><th><p class="s8">Base materials used for</p></th></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 can cause corrosion they have to be removed completely after the brazing process in very hot or boiling water. Depending on the type 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 process used, fluxes are being applied in liquid form or as powders or pastes.alloys</p><p class="s8">except light metals</p></td></tr></table></figtable>

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