Open main menu

Electrical Contacts β

Changes

Brazing Alloys and Fluxes

1,058 bytes added, 09:05, 10 January 2023
Brazing Alloys
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 (<xr id="tab:Commonly_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 Because of the toxicity of cadmium, most cadmium containing brazing alloys have been replaced by zinc and tin containing brazing alloys. Alloys containing nickel and manganese are also used for higher corrosion resistance requirements or for easier wetting of stainless steel.. Using any of these brazing alloys in an air environment is only possible with the addition of oxide reducing fluxes.
 
<figtable id="tab:Commonly_Used_Brazing_Alloys_for_Electrical_Contacts">
[[File:Commonly Used Brazing Alloys for Electrical Contacts.jpg|right|thumb|Commonly Used Brazing Alloys for Electrical Contacts]]
</figtable>
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.
 
<figtable id="tab:Commonly_Used_Brazing_Alloys_for_Electrical_Contacts">
<caption>'''<!--Table 4.2:-->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
!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/>[°C]
!Electrical Conductivity<br/>[MS/m]
!Density<br/>[g/m<sup>3</sup>]
!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, 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
|780
|46,1
|10,0
|Cu, Cu-Alloys, 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
</figtable>
== Fluxes ==